Download News Letter - Indian Association for Cancer Research

Indian Association for Cancer Research
NEWSLETTER
Volume 26 - Issue 2 November - 2010
CONTENTS :
Lead Articles:
1. Recent development in cancer diagnosis
- Dr. Hafiz Ahmed
2. Epithelial-Mesenchymal Transition in Cancer
-Dr. Sharmila Bapat
Activities:
3. Cancer News
4. Spotlight on ……….
EDITORIAL BOARD
Editor :
DR. PRABHUDAS PATEL
Head, Biochemistry Research Division,
The Gujarat Cancer & Research Institute,
Ahmedabad-380 016
E-mail : [email protected]
Members :
DR. SHILIN SHUKLA
(Ahmedabad)
DR. RAKESH RAWAL
(Ahmedabad)
DR. BHUDEV DAS
(Noida)
DR. M. RADHAKRISHNA PILLAI
(Thiruvananthapuram)
DR. NISHIGANDHA NAIK
(Navi Mumbai)
DR. NEETA SINGH
(New Delhi)
DR. SUDHIR KRISHNA
(Bangalore)
DR. BHARAT AGGARWAL
(USA)
DR. NEWELL JOHNSON
(Australia)
IACR EXECUTIVE COMMITTEE
2009-12
President
Vice-President
Secretary
Joint-Secretary
Treasurer
Members
Dr. Rita Mulherkar
Dr. Nishigandha Naik
Dr. Tanuja Teni
Dr. Sorab Dalal
Dr. Asha Ramchandani
Dr. Arun Kumar
Dr. Sharmila Bapat
Dr. R. I. Dave
Dr. Dinesh Gupta
Dr. H. N. Jayaram
Dr. Surya B. Prasad
Dr. Ajit Saxena
Navi Mumbai
Mumbai
Navi Mumbai
Navi Mumbai
Navi Mumbai
Bangalore
Pune
Ahmedabad
New Delhi
Indianapolis, USA
Shillong
Jammu-Tawi
Indian Association for Cancer Research
NEWSLETTER
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1
From the Editor's Desk …….
Greetings !
It gives me enormous pleasure to bring out another issue of IACR newsletter. This issue of the
newsletter contains two articles by eminent and distinguished scientists. One is review article by Dr.Hafiz
Ahmed on “Recent development in cancer diagnosis”. As we are aware that cancer is a leading cause of
death worldwide and the diagnosis of cancer relies primarily on invasive tissue biopsy, as noninvasive
diagnostic tests are generally insufficient to define a disease process of cancer. The conventional
histopathology based on light microscopy, however, has recently been complemented with ultrastructure,
immuno-histochemistry and molecular diagnostics. In the past several years, there has been increasing
interest and enthusiasm in molecular biology as tools for cancer early detection, diagnosis, prognosis and
treatment. Molecular medicine has led to the discovery and application of molecular tumor markers, which
make histology more accurate and additionally help to prognosticate cancer and has raised new
possibilities in the diagnosis and treatment of human cancers. Recent advances in high-throughput
technologies in genomics, proteomics, and metabolomics have facilitated in this. In this review, Dr. Hafiz
Ahmed has given an overview of how the use of these technologies can aid in biomarker discovery,
including DNA/RNA, protein, and metabolites, which provide information on the occurrence and
progression of the disease. As more potential biomarkers are discovered, further studies are needed to
validate these markers. The ultimate use of these biomarkers should be in clinical applications for cancer
detection and treatment.
The other article is on “Epithelial Mesenchymal Transition in Cancer” by Dr. Sharmila Bapat.
Epithelial-mesenchymal transition (EMT) is critical for appropriate embryonic development, and this
process is re-engaged in adults during wound healing, tissue regeneration, organ fibrosis, and cancer
progression. Dr. Bapat has brilliantly summarized recent novel insights into the molecular processes and
players underlying EMT as well as molecular mechanisms of EMT and its involvement in cancer
progression. I sincerely hope that these articles will be useful and add up to the knowledge of young
scientists.
In the spotlight section, we have highlighted the contribution of Dr. Pier Paolo Pandolfi, recipient of
the Pezcoller Foundation-AACR International Award for Cancer Research -2011.
It has been a great pleasure and experience to bring out IACR newsletter as the editor since March,
2007, which I have always enjoyed. However, the change is the demand of time for improvement and
progress of any activity so that new innovative ideas and thoughts can come up and put in a new way.
Taking this as a thought, I would like to request other senior IACR members to bring out IACR newsletter
from next issue i.e. from March, 2011.
I take the opportunity to pay my sincere thanks to the executive committee of IACR and IACR
members for their cooperation and support which has been significantly useful in carrying out the IACR
newsletter activity. I am also thankful to Ms. Ragini Singh for her help in bringing out IACR newsletter
during 2007-10.
My best wishes to IACR family members.
Prabhudas S. Patel
Editor, IACR Newsletter
Volume 26 - Issue 2 November - 2010
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NEWSLETTER
Indian Association for Cancer Research
Recent development in cancer diagnosis
Hafiz Ahmed
Department of Biochemistry and Molecular Biology,
University of Maryland School of Medicine & Greenebaum Cancer Center,
701 East Pratt Street, Baltimore, Maryland, USA,
[email protected]
Cancer is the leading cause of death worldwide (1).
There are an estimated 12 million new cancer diagnoses
and more than 7 million deaths worldwide in the year
2010 (1). It is estimated that new cancer diagnoses will
double by 2020 and nearly triple by 2030 (1). However,
cancer death can be reduced or prevented if detected at
their early stages. Conventional histopathology,
immunohistochemistry or image based screening tools
such as mammography for breast cancer and chest Xray for lung cancer may render specific detection of
cancer, but may not be sensitive enough for early
detection of the disease. Moreover, some of these tools
are invasive and therefore, it is imperative to develop
noninvasive techniques that distinguish between
patients with and without cancer, as well as between
stages of cancer. The introduction of advanced
sophisticated technologies like proteomics (2), mass
spectrometry, microarray (mRNA, micro RNA [3],
protein, lectin, glycan [4]), automated DNA
sequencing, comparative genomic hybridization, and
epigenetics (DNA methylation) have allowed to search
for new cancer biomarkers that may be useful for noninvasive (or minimally invasive) early detection from
biological fluids such as serum, urine, sputum as well as
fluid-derived exosomes (5) and circulating tumor cells
(6) and thereby prevention of the disease.
Proteomics allows both qualitative and quantitative
assessment of changes in protein expression related to
specific cellular responses. After two-dimensional gel
electrophoresis (2DE), protein spots on the gel are
detected robotically and their sequences analyzed by
tandem mass spectrometric methods. Recently,
quantitative proteomics coupled with metabolic or
post-extraction stable-isotope labeling alone, or in
combination with affinity tags allows rapid
advancements in global detection and quantitation of
proteins important for not only biomarker discovery,
but also cell function and disease mechanism (2). Many
protein markers for various cancers such as NMP22
(bladder cancer), CEA (colorectal cancer), CA15-3 and
Volume 26 - Issue 2 November - 2010
Her2/Neu (breast cancer), alpha-fetoprotein (liver
cancer), CA-19-9 (pancreatic cancer), and CA-125
(ovarian cancer) have been identified using proteomics
(2).
The alteration in protein glycosylation on the cell
surface and in body fluids such as serum has been
shown to correlate with the progression of cancer. Thus,
a high-throughput technique for quantitative analysis of
glycan structure on glycoproteins may be useful for
identifying new glycoprotein biomarkers suitable for
early cancer detection. Moreover, since lectins can
specifically and reversibly bind glycans with different
structural moieties, they serve as excellent tools in
screening glycosylation differences between various
samples. The fucosylated haptoglobin has recently been
identified as a marker for pancreatic cancer using this
approach (4).
Gene expression profiling or microarray analysis has
been now a standard technique which enabled the
measurement of thousands of genes in a single RNA
sample (7). Although a variety of microarray platforms
have been developed over the years to accomplish this,
but the basic principle is that a glass slide or membrane
is spotted or "arrayed" with DNA fragments or
oligonucleotides that represent specific gene coding
regions. Fluorescently labeled (usually Cy3 or Cy5)
purified RNA from tumor specimen is then hybridized
to the oligonucleotide array. Reference RNA such as
from normal tissue is labeled with a dye different from
the tumor specimen and hybridized also simultaneously
to the array to facilitate comparison of data across
multiple experiments. APRIL/TNFSF13 (a TNF
superfamily ligand) has recently been identified as a
novel clinical chemo-resistance biomarker in colorectal
adenocarcinoma by this approach (8).
microRNAs (miRNAs) are post-transcriptional
regulators that suppress the translation of target
mRNAs by binding to their 3′ untranslated region
Indian Association for Cancer Research
NEWSLETTER
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Fig. 1 Simplified figure showing gene transcription by unmethylated promoter and gene silencing by the methylated
promoter. In normal cells, promoter of some genes such as tumor suppressor protein, DNA repair proteins is unmethylated
and accessible to binding to the transcription factors (TF) allowing transcription. But, in many cancers these genes are
methylated by DNA methyltransferase 1 and therefore bound by the methyl-CpG binding proteins (MBD) and histone
deacetylase (HDAC). Thus the methylated promoter is not accessible to binding to the transcription factors and inactive. In
tumor tissues and biological fluids such as serum and urine, the methylated DNA is measured by various methods for the
development of diagnostic and prognostic tools for the cancer. HAT indicates histone acetyltransferase; RNA pol II, RNA
polymerase II; and HMT, histone methyltransferase;
during various cellular processes, such as proliferation,
differentiation, and cell death. miRNAs are an ideal
class of blood-based biomarkers for cancer detection
because their expression is frequently dysregulated in
cancer and their expression patterns in human cancer
appear to be tissue-specific. The miRNA miR-141 has
been identified as a marker for prostate cancer (6).
Comparative genomic hybridization allows detection
of chromosomal gains and losses in genomic
complement (9). Identification of the structurally
aberrant cancer gene has become essential, as many
mutations are not discernible at the cytogenetic level.
Several diagnostic molecular markers such as K ras
mutation (colon cancer) (10) and p53 mutation (bladder
cancer, head and neck cancer) (11) have been identified
by this method. A recently described gene fusion
between TMPRSS2 and ETS family genes in prostate
cancer may have clinical applications in diagnosis,
prognosis and therapy (12).
The detection of circulating tumor cells (CTCs) may
Volume 26 - Issue 2 November - 2010
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NEWSLETTER
represent an early indication of micro-metastasis or
aggressive tumors which are able to shed tumor cells
into the blood (13). The CTCs are captured using
antibody labeled magnetic beads and characterized for
gene expression analysis by RT-PCR. The detection of
CTCs is being used as a prognostic test in patients with
metastatic cancers of the breast, prostate and colon.
The exacerbated release of 40-100 nm membrane
vesicles (called exosomes) in tumor cells, suggests an
important role of exosomes in diagnosis and biomarker
studies (14). They are found in vivo in body fluids such
as blood, urine, amniotic fluid, malignant ascites,
bronchoalveolar lavage fluid, synovial fluid, and breast
milk. Exosomes contain mRNA, microRNA (miRNA),
protein/glycoprotein, and lipid/glycolipid. In addition
to a common set of membrane and cytosolic molecules,
exosomes harbor distinct subsets of molecules linked to
cell type-associated functions. Prostate cancer derived
urine exosomes are shown to contain two known
prostate cancer biomarkers, PCA-3 and TMPRSS2:
ERG, showing the potential for diagnosis and
monitoring cancer patient's status (15). Recently,
miRNA profiling (such as miR-21, miR-141, miR-200a,
miR-200c, miR-200b, miR-203, miR-205 and miR-214)
of circulating tumor exosomes has been used as
surrogate diagnostic markers for ovarian cancer (16).
Epigenetic alterations, including hypermethylation of
CpG islands in the gene promoters are believed to be
early events in neoplastic progression (17).
Hypermethylation of tumor suppressor gene promoters
contributes to their silencing during the neoplastic
process (17, Fig. 1). Thus, methylated gene promoters
can serve as markers for the detection of cancer from
clinical specimens such as tissue biopsies or body fluids
(18). DNA is stable and its modifications can be
reliably detected both qualitatively and quantitatively
by PCR-based techniques. PCR also allows detection of
as few as one cancer cell (or genome copy) in a
background of thousands of normal cells, thereby
permitting detection of a cancer before it can be
visualized by imaging or traditional pathology.
Therefore, methylated DNA sequences can form the
basis of a sensitive and specific, robust and informative
test for the detection of cancer. A spectrum of methods is
available for the identification and quantitation of
methylated DNA. These include cytosine deamination
PCR, semi-quantitative and quantitative methylationspecific PCR (MSP), differential methylation
hybridization (DMH), restriction landmark genomic
scanning (RLGS), single-nucleotide primer extension
Volume 26 - Issue 2 November - 2010
Indian Association for Cancer Research
(SNuPE), pyrosequencing, and methylation microarray
for large-scale genome analysis. However, MSP is a
simple and sensitive method, and is the most commonly
employed method for methylation analysis. In prostate
cancer, GSTP1, RASSF1A, RARb2 and galectin-3
promoters are frequently methylated (18, 19); while
ARF, APC, and DAPK have been found methylated in
bladder cancer (18). Among the genes commonly
hypermethylated in breast cancer are the p16NK4A,
estrogen receptor (ER) alpha, the progesterone receptor
(PR), BRCA1, GSTP1, TIMP-3, and E-cadherin (20).
Although several hundreds of biomarkers have been
found promising for cancer diagnosis, only a handful of
biomarkers have been approved by the US Food and
Drug Administration during the past two decades (21).
This is because most biomarkers lack sufficient
sensitivity and/or specificity. To be useful, biomarkers
must distinguish between people with cancer and those
without. No single biomarker is likely to have 100%
sensitivity and 100% specificity for a particular
neoplasm. Instead, panels of biomarkers seem to be a
promising alternative for the use in clinical laboratories.
For example, GSTP1 methylation is detected as low as
one prostate cancer cell, but not specific to prostate
cancer as the GSTP1 methylation is also present in
breast and renal cancers. However, two or multiple
genes cohort such as GSTP1/galectin-3 or
GSTP1/RARβ2/APC has been shown to be more
specific and sensitive biomarkers for prostate cancer
(18, 19). However, optimization of this combined assay
and its validation in large scale studies are necessary
before this combined assay can be considered clinically
useful.
Acknowledgments : The work carried out in the
author's laboratory has been supported by the UMBI
Presidential Proof of Concept Award and the National
Institute of Health Grants RO3 CA133935-01 and
R41CA141970-01A2.
References
1. Cancer Projected To Become Leading Cause Of
Death Worldwide In 2010. ScienceDaily, Dec. 9,
2008.
2. Xiao GG, Recker RR, Deng HW. Recent Advances
in Proteomics and Cancer Biomarker Discovery.
Clinical Medicine: Oncology 2008; 2:63-72
3. Grady WM, Parkin RK et al. Epigenetic silencing
of the intronic microRNA hsa-miR-342 and its host
gene EVL in colorectal cancer. Oncogene. 2008;
27:3880-8.
Indian Association for Cancer Research
4. Li C, Simeone DM, Brenner DE et al. Pancreatic
cancer serum detection using a lectin/glycoantibody array method. J Proteome Res. 2009;
8:483-92. Pisitkun T
5. , Johnstone R, Knepper MA. Discovery of urinary
biomarkers. Mol Cell Proteomics. 2006; 5:176071.
6. Mitchell PS, Parkin RK et al. Circulating
microRNAs as stable blood-based markers for
cancer detection. Proc Natl Acad Sci U S A. 2008;
105:10513-8.
7. López-Casas PP, López-Fernández LA. Geneexpression profiling in pancreatic cancer. Expert
Rev Mol Diagn. 2010; 10:591-601.
8. Petty RD, Samuel LM et al. APRIL is a novel
clinical chemo-resistance biomarker in colorectal
adenocarcinoma identified by gene expression
profiling. BMC Cancer. 2009; 9:434.
9. Staaf J, Borg A. Zoom-in array comparative
genomic hybridization (aCGH) to detect germline
rearrangements in cancer susceptibility genes.
Methods Mol Biol. 2010; 653:221-35.
10. Winder T, Lenz HJ. Molecular predictive and
prognostic markers in colon cancer. Cancer Treat
Rev. 2010; 36:550-6.
11. Volanis D, Kadiyska T et al. Environmental factors
and genetic susceptibility promote urinary bladder
cancer. Toxicol Lett. 2010;1 93:131-7.
12. Kumar-Sinha C, Tomlins SA, Chinnaiyan AM.
Recurrent gene fusions in prostate cancer. Nat Rev
Cancer. 2008; 8:497-511.
13. Andreopoulou E, Cristofanilli M. Circulating
tumor cells as prognostic marker in metastatic
breast cancer. Expert Rev Anticancer Ther. 2010;
10:171-7.
14. Simpson RJ, Lim JW, Moritz RL, Mathivanan S.
Exosomes: proteomic insights and diagnostic
potential. Expert Rev Proteomics. 2009; 6:267-83.
15. Nilsson J, Skog J et al. Prostate cancer-derived
urine exosomes: a novel approach to biomarkers for
prostate cancer. Br J Cancer. 2009; 100:1603-7.
16. Taylor DD, Gercel-Taylor C. MicroRNA signatures
of tumor-derived exosomes as diagnostic
biomarkers of ovarian cancer. Gynecol Oncol.
2008; 110:13-21.
17. Strathdee G, Brown R. Aberrant DNA methylation
in cancer: potential clinical interventions. Expert
Rev Mol Med 2002; 4:1-17.
18. Cairns P. Gene methylation and early detection of
genitourinary cancer: the road ahead. Nature
Reviews Cancer. 2007; 7:531-43.
19. Ahmed H. Promoter methylation in prostate cancer
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and its application for the early detection of prostate
cancer using serum and urine samples. Biomarkers
in Cancer, 2010; 2:17-33.
20. Das PM, Singal R. DNA methylation and cancer. J
Clin Oncol. 2004; 22:4632-42.
21. Srivastava S. Cancer Biomarker Discovery and
Development in Gastrointestinal Cancers: Early
Detection Research Network—A Collaborative
Approach. Gastrointest Cancer Res. 2007; 1:
S60–S63.Figure legend
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Indian Association for Cancer Research
Epithelial-Mesenchymal Transition in Cancer
Sharmila A. Bapat
Research Scientist, National Centre for Cell Science,
Pune, India
1. Introduction
Migration of epithelial cells has been identified to be a
crucial event during development, organogenesis and
cancer (Aranda et al., 2008). The process is mediated
through changes in cellular architecture and polarity
and involves a change in morphology of rigid, polar
epithelia to a motile mesenchymal-like shape. The
morphological transformation thus mediated is often
referred to as Epithelial-mesenchymal transition
(EMT). Although first described during development
(Hay ED, 1995), there is considerable debate regarding
the similarity of EMT programs in the three different
contexts. During development and organogenesis,
EMT is an important mechanism that regulates
epithelial plasticity by directing cell fate versus cell
behavior.
Down regulation components of the
adherans, tight, desmosomal junctions have been often
described as the hallmark of EMT through
demonstration of its association with altered cell-cell
adhesion and cytoskeleton organization and disruption
of cell polarity pathways (Boyer et al., 1988; Savagner
P, 2001; Kurrey et al., 2005).
The classical hallmarks of cancer include limitless
replicative potential, growth factor independence,
insensitivity to anti-growth signals, evasion of
programmed cell death, sustained angiogenesis and
tissue invasion for metastasis (Hanahan & Weinberg,
2000). Study of metastatic processes in cancer over the
last decade has identified that carcinoma cells often
evoke the EMT program to become invasive and are
thought to be responsible for seeding distant
dissemination, eventually leading to cancer-related
mortality. Following the migration to an amenable
microenvironment, the metastasizing cells undergo a
reversal of the phenomenon viz. a mesenchymal to
epithelial (MET) process that ensures establishment of
cells at this site and consequent development of a
secondary tumor (Fig. 1).
More recently, EMT in the context of cancer has also
been associated with resistances to senescence,
apoptosis, immune surveillance and therapy, and most
interestingly, the acquisition of stem cell–like
Volume 26 - Issue 2 November - 2010
characteristics by tumor cells. While the field has grown
considerably over the last decade since the involvement
of EMT in cancer began to be addressed, the present
review discusses a few of the cutting-edge implications
of the phenomenon and its associated cellular
implications.
2. EMT & MET in Cancer Metastases
An all-encompassing definition of EMT has described
it as the culmination of protein modification and
transcriptional events in response to a defined set of
extracellular stimuli leading to a long term, albeit
sometimes reversible, cellular change (Hugo et
al.,2010). The process thus appears to be regulated at
two levels through interactions between cell extrinsic
and intrinsic factors. The cell extrinsic factors that
trigger EMT include effects on tumor cells like –
(i)
Depletion of nutrients and limited gaseous
exchange brought upon by an enlarging tumor,
and
(ii)
Growth, proliferation and maintenance signals
from the tumor niche through remodeling of
the extra-cellular matrix components as well as
tumor stroma that can produce and/or recruit
cytokines and growth factors that influence
surrounding cells through autocrine or
paracrine mechanisms.
Within the tumor cell, the effects of the microenvironment set into motion signaling molecules that
trigger off definitive cascades of reactions, signaling
and specific transcriptional programs. The altered gene
expression patterns ultimately culminate protein
profiles that contribute to the process. Core elements of
EMT include reduction of cell–cell adherence via the
transcriptional repression and delocalization of
cadherins (adherens junctions), occludin and claudin
(tight junctions), and desmoplakin (desmosomes). The
cadherin supporting molecule b-catenin is often lost
from the cell membrane and translocates to the nucleus
to not only participate in EMT signaling events
Indian Association for Cancer Research
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Figure 1 : Epithelial - Mesenchymal Transitions in Cancer
(Klymkowsky, 2005), but further establishes its own
transcriptional program that supports transformation
and disease progression.
At the cytoskeletal level, circumferential F-actin fibres
are replaced by a network of stress fibers, at the tips of
which localize ECM adhesion molecules including
integrins, paxillin, focal adhesion kinase. These
changes potentially allow cells to separate, lose the
apico-basal polarity typical of epithelial cells, and gain
a more variable cell shape and changeable cell
adhesions, all of which facilitate cell movement.
Expression of epithelial intermediate filaments,
containing cytokeratins, is typically reduced and the
equivalent mesenchymal filament protein vimentin
increased. Matrix metalloproteases such as MMP-1, -2,
-3, -7, and -14 are frequently upregulated, potentially
enabling cells to detach from each other (via E-cadherin
cleavage) and to penetrate the basement membrane and
migrate away from the primary tumor. Thereby, the
process is a highly co-ordinated one that involves
several pathways to be activated and others to be
inactive.
EMT in some cases is reversible, which enables
migrating cells to remain responsive to changing
environmental cues. Such mesenchymal to epithelial
transition (MET) events are further important in
establishing tumors at seconday sites after metastases.
This suggests that cellular plasticity, the ability to
undergo EMT and subsequently MET in the appropriate
microenvironments, is a key feature of a successful
metastatic cell.
3. Signaling Cues in EMT
Several signaling circuits are now recognized to play a
role in triggering EMT in cancer.
The following
pathways have been maximally investigated in this
context –
(i) Transforming growth factor-β (TGF- β)
TGF-β is a secreted cytokine with diverse roles in
regulating cellular processes such as proliferation,
migration and apoptosis. It is strongly correlated with
EMT which can be effected through several pathways
including Smad2/3 (Piek et al., 2001), Rho GTPases
(Bhowmick et al., 2001), PI3K and AKT (Bakin et al.,
2000, 2002), NF-κB (Huber et al., 2005), ERK1/2 (Xie
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et al., 2003), p38 MAPK (Bhowmick et al., 2001;
Galliher and Schiemann 2006, 2007, 2008), JNK
(Hocevar et al., 2001), Integrin-linked kinase (Lin et
al., 2007).
(ii) Bone morphogenetic protein 4 (BMP4)
Bone morphogenetic proteins (BMPs) are critical
morphogens and play key roles in epithelialm e s e n c h y m a l t r a n s i t i o n s ( E M Ts ) d u r i n g
embryogenesis and organogenesis (Molloy et al.,
2008). In the context of cancer, BMP4 induced MSX2
expression through the ERK and p38 MAPK pathways
in collaboration with the Smad signaling pathway that
resulted in the repression of E-cadherin, induction of
vimentin and enhanced cell migration (Hamada et al.,
2007). Another pathway of EMT activation is through
Rho GTPase activation (Thériault et al., 2007).
(iii) Epidermal growth factor (EGF)
EGF is known to induce EMT following binding to its
receptor, EGFR. EGFR is expressed in a large majority
of malignant ovarian tumors and correlated with poor
prognosis and chemoresistance (Barr et al., 2008).
Most studies suggest that EGF has synergistic
interactions TGFβ towards inducing more invasive
phenotypes of epithelial cancer cells (Xu et al,. 2010).
This cross-talk involves several pathways including
mitogen-activated protein kinase (MAPK) and AKT
signaling that induce the expression of a series of matrix
metalloproteinases, cathepsin, Phospholipase C (PLC)
and Cox2 (Uttamsingh et al,. 2008).
(iv) Endothelin-1 (ET-1)
Endothelin-1 (ET-1) is vasoconstrictor peptide isolated
from the first time from the culture media of porcine
endothelial cells. ET-1 acts by binding to two G-protein
coupled transmembrane receptors, ETA and ETB, and it
has been implicated in several physiological and
pathological conditions, including cancer. Activation
of ETA by ET-1 triggers a phosphatidylinositol 3kinase-dependent integrin-linked kinase (ILK)mediated signaling pathway leading to glycogen
synthase kinase-3 β (GSK-3 β) inhibition, Snail and βcatenin stabilization and transcriptional programs that
control EMT (Bagnato & Rosanò, 2007).
(v) Hepatocyte growth factor (HGF)
Hepatocyte growth factor (HGF) is a stromal-derived
factor that activates various signal transduction
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Indian Association for Cancer Research
pathways including MAPK, PI3 K and AKT. The
effects of this growth factor are recognized as being
more of cell scattering rather than EMT; however, high
expression of HGF and c-MET has been associated with
an invasive phenotype and poor prognosis in several
cancers (Elliott et al., 2002). Combinatorial growth
factor effects of HGF with VEGF and TGFβ suggests
co-operative effects that together contribute to cancer
metastasis, suggesting that might modulate HGF
signaling (Chung et al., 2011).
4. Transcription Factors in EMT
The effects of most if not all the signaling mechanisms
at the transcriptional level are mediated by several
repressors including that target the expression of
adherent junction components (E-cadherin, β-catenin),
tight junction components (Occludin, Zonula
Occludin-1) and desmosomal junction component
(Desmoglein-2). While there is an increasing list of
such transcriptional repressors, the ones that are
currently established to be involved include Snail, Slug,
Twist, Zeb1, Zeb2, FoxC2, TCF3 and Goosecoid.
Expression of these is considered as prerequisite for
invasion and metastasis and extensive profiling has
established a negative correlation with patient
prognosis in a majority of cases (Nieto et al., 1994;
Moreno-Bueno et al., 2008,2009). These factors may
regulate each other in a hierarchical pattern where Snail
and Slug are initially induced, leading to the activation
of the others (Hugo et al., 2010). Several interregulatory relationships are necessary to support such
transcriptional cascades, and defining these is
considered as being important in maintaining the EMT
phenotype.
Over the last few years, it is realized that the
transcriptional programs thus identified not only
primarily induce invasion and metastasis, but also play
important role(s) in cell survival. This has increasingly
led to an intense examination of the role of the EMT
associated transcriptional factors in immune regulation,
resistance to senescence and apoptosis as well as stem
cell biology, implying their wide range of influence in
EMT-dependent and -independent functions during
development and disease.
5. EMT & the “Stemness” phenomenon
Many tumors have been found to contain a subset of
cells referred to as cancer stem cells (CSCs). In contrast
to a large majority of the tumor, these cells are
undifferentiated and they (re)express stem cell
Indian Association for Cancer Research
specification genes. The cells can divide
asymmetrically to yield differentiated cells as well as
cells comprising the original heterogeneous population
of the tumor while maintaining their number. Because
cancer stem cells display some properties of stem cells,
it has been presumed that the presence of such cells in
tumors reflects a stem cell origin for cancer. However,
recent studies suggest that cancer can originate with
outgrowth of differentiated somatic cells, and that cells
with properties of cancer stem cells can be generated as
tumors progress through a de-differentiation program.
In several instances, the occurrence of such cells may be
linked to reprogramming of differentiated somatic cells
to a stem cell-like phenotype by overexpression of
transcription factors involved in epithelialmesenchymal transition (EMT).
The clinical significance of CSCs is important since it is
opined that these cells survive radio/chemotherapy and
can regenerate fresh tumors after treatment. There are
two facets to this school of thought. According to one
line of research, it appears that CSCs are derived from
transformed tumor cells through EMT, and this feature
ensures their enrichment in post-treatment recurrent
disease. The other school of thought emphasizes on the
quiescent nature of stem cells whereby they are able to
evade most chemotherapies since these drugs are
designed to target actively dividing cells. This evasion
may result in tumor dormancy and minimal residual
disease to finally culminate in a recurrent, aggressive
disease. Thus, the recently emerging relationship
between EMT and cancer stem cells is an exciting
development in the field.
6. Future Directions
EMT has indeed emerged as one of the hottest topics in
cancer biology over the decade, since it is realized to be
the first step for tumor cells towards stromal invasion,
intravasation, extravasation and distant metastasis that
ensues disease progression and a increasingly poor
prognosis for a majority of patients. Understanding the
regulation of the process will thus shed insights on the
mechanism of tumor progression towards disease
management through development of novel antimetastasis therapies.
Profiling of the EMT-associated transcription factors,
their upstream signaling cascades and specific
transcriptomes is increasingly being studied and the
resultant data probed with a view of development of an
“EMT signature” for potential use in drug development,
NEWSLETTER
09
prognostic testing, and prediction of treatment
outcomes. While the classical EMT markers including
low E-cadherin, high vimentin, and N-cadherin
expression are useful to identify cells with a propensity
towards EMT or are circulating tumor cells, screening
of stem cell, anti-apoptosis and drug resistance markers
will enhance the predictive power of such signatorial
profiles.
To cite an example, genome-wide
transcriptional profiling of breast tumors often reveals
cellular subgroups with mesenchymal tendencies and
enhanced invasive properties (Basal B), that are distinct
from subgroups with either predominantly luminal or
mixed basal/luminal features (Neve et al., 2006). EMT
gene signatures show specific enrichment within the
Basal B subgroup of cell lines, consistent with their
over-expression of various EMT transcriptional
drivers. Basal B cells are also CD44high/CD24low a
phenotype described in association with mammary
stem cells. These findings confirm and extend the
importance of EMT with Basal B tumors and also may
be important in designing molecular classification
schemes for metastatic tumors.
References
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Thiery JP. Cell adhesion systems: molecular
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Galliher AJ, Schiemann WP. Src phosphorylates
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TGF-β stimulation of p38 MAPK during breast
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Galliher AJ, Schiemann WP. β3 integrin and Src
facilitate TGF-β mediated induction of epithelialmesenchymal transition in mammary epithelial
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Galliher-Beckley AJ, Schiemann WP. Grb2
binding to Tyr284 in TGF-β is essential for
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Hamada S, Satoh K, Hirota M, Kimura K, Kanno
A, Masamune A, Shimosegawa T. Bone
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Huber MA, Kraut N, Beug H. Molecular
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Hugo HJ, Kokkinos MI, Blick T, Ackland ML,
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Klymkowsky MW. beta-catenin and its regulatory
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network. Hum Pathol. 2005 ;36(3):225-7.
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at the transcription level. Gynecol Oncol 2005
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JJ. Critical involvement of ILK in TGF-β1stimulated invasion/migration of human ovarian
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Madrigal-Estebas L, Mahon BP, O'Dea S. BMP4
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D, Cubillo E, Santos V, Palacios J, Portillo F, Cano
A. The morphological and molecular features of
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Transcriptional regulation of cell polarity in EMT
and cancer. Oncogene. 2008 ;27(55):6958-69.
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Control of cell behavior during vertebrate
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24. Nolan ME, Aranda V, Lee S, Lakshmi B, Basu S,
Allred DC, Muthuswamy SK. The polarity protein
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29. Xie L, Law B, Aakre M, et al. TGF-β-regulated
gene expression in a mouse mammary gland
epithelial cell line. Breast Cancer Res
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30. Xu Z, Jiang Y, Steed H, Davidge S, Fu Y. TGFβ
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Epithelial-Mesenchymal Transitions in
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NEWSLETTER
Indian Association for Cancer Research
Cancer News
(Courtesy: www.cancer.gov)
Researchers discover key mutation in acute myeloid leukemia
NIH-supported discovery may lead to treatment changes; demonstrates power of The Cancer Genome Atlas strategy
Researchers have discovered mutations in a particular
gene that affects the treatment prognosis for some
patients with acute myeloid leukemia (AML), an
aggressive blood cancer that kills 9,000 Americans
annually. The scientists report their results in the Nov.
11, 2010, online issue of The New England Journal of
Medicine.
The Washington University School of Medicine in St.
Louis team initially discovered a mutation by
completely sequencing the genome of a single AML
patient. They then used targeted DNA sequencing on
nearly 300 additional AML patient samples to confirm
that mutations discovered in one gene correlated with
the disease. Although genetic changes previously were
found in AML, this work shows that newly discovered
mutations in a single gene, called DNA
methyltransferase 3A or DNMT3A, appear responsible
for treatment failure in a significant number of AML
patients. The finding should prove rapidly useful in
treating patients and which may provide a molecular
target against which to develop new drugs.
The study was carried out by researchers from the
Washington University Genome Center and the
Siteman Cancer Center at Barnes-Jewish Hospital and
Washington University School of Medicine. In the
study, the researchers found DNMT3A mutations in 21
percent of all AML patients studied and in 34 percent of
the patients classified as having an intermediate risk of
treatment failure based on widely used laboratory tests
of their leukemia cells. More than half of AML patients
are classified as having an intermediate risk and are then
typically treated with standard chemotherapy.
Scientists identify molecular link between BRCA1
protein levels and obesity
NCI researchers have defined a possible molecular link
between breast cancer risk and obesity. New study
results show that a protein called C-terminal binding
protein (CtBP) acts to control a gene linked to breast
cancer risk in rapidly growing cells by monitoring and
responding to how the cells use and store energy
Volume 26 - Issue 2 November - 2010
(metabolic state). The cancer susceptibility gene,
BRCA1, performs many functions in the cell, including
the regulation of cellular growth and division as well as
the repair of DNA or genetic damage. In breast tissue,
BRCA1 expression rapidly increases in response to the
growth effects caused by estrogen. This study, led by
Kevin Gardner, M.D., Ph.D., Laboratory of Receptor
Biology and Gene Expression,found that under
conditions where there is a metabolic
imbalance—available cellular energy is greater than the
energy required to carry out cellular functions—the
activity of CtBP increases and suppresses the
expression of BRCA1.The paper is published in the
Nov. 21, 2010 issue of Nature Structural and Molecular
Biologywith post-doctoral fellow, Li-Jun Di, Ph.D., as
first author.
The scientists demonstrated metabolic imbalance either
by manipulating the metabolic state of the human breast
cancer cells with drugs, or by deleting expression of the
CtBP gene. When they created a cellular energy
imbalance, a condition when the cell's energy stores are
very high compared with normal energy usage—much
in the way energy imbalance occurs in obesity in
humans—the cells produced less BRCA1 type 1 breast
cancer susceptibility protein. When they decreased the
levels of CtBP or reversed the energy imbalance, they
could recover or rescue BRCA1 expression. Past
studies have determined that high-fat diets increase the
risk and severity of mammary cancer in mice and that
calorie restriction has beneficial effects that can reverse
this trend. The goal of Gardner and his team is to
examine these experimentally induced mammary
cancers in combination with available breast-tissue
samples from patients in clinical studies to see if
increased CtBP activity and lowered BRCA1
expression are important molecular events in breast
cancer.
News Note: An integrated DNA approach predicts
therapeutic response in patients with advancedstage liver cancer
NCI scientists have identified epigenetic and genetic
signatures in liver cancer cells that may one day be used
Indian Association for Cancer Research
NEWSLETTER
13
to predict clinical outcomes, with a high degree of
accuracy, in patients with advanced-stage liver cancer.
The incidence of liver cancer is increasing faster than
that of other cancers in the United States. While earlystage liver cancer is amenable to potentially curative
therapies, only about 30 percent of patients are
diagnosed with early-stage disease. The new research
addresses the needs of the subgroup of patients with
advanced-stage disease who have few therapeutic
options. Results of the study appear in the Oct. 20, 2010,
Science Translational Medicine.
Liver tumors that progress from premalignant lesions to
end-stage liver cancer are driven by genetic changes, as
well as those indirectly related to the tumor's DNA
(epigenetic changes). Many epigenetic changes are
reversible with the application of drugs, thereby
offering a multi-target strategy against cancer.
Zebularine inhibits an abnormal epigenetic activity
called methylation that is frequently linked to cancer. In
this study, the research team characterized the
epigenetic changes induced by the drug zebularine in
liver cancer cells. In an animal xenograft model (human
tumor cells transplanted into mice) they found a distinct
signature that identified two groups of tumor cell
responses,those sensitive and those resistant to
zebularine. Zebularine treatment of liver tumors
bearing the sensitive profile resulted in increased
survival and a decrease in metastasis to the lungs.
Importantly, if this same result repeats itself in cancer
patients, a zebularine sensitive signature could identify
a subclass of patients—who today have poor survival
and few treatment options—able to benefit from
therapeutic agents that target the cancer epigenome.
Volume 26 - Issue 2 November - 2010
14
NEWSLETTER
Indian Association for Cancer Research
Congratulations
Dr. Heena Dave
Dr. Heena Dave, working at Receptor & Growth Factor Laboratory, The Gujarat Cancer & Research Institute,
Ahmedabad has recently completed her 'Fulbright-Nehru Doctoral and Professional Research Fellowship 2009 –
2010'. This fellowship was awarded by US Department of State and Government of India. She was working at Weill
Medical College of Cornell University, New York, US. She presented a paper at 101st Annual Meeting of American
Association for Cancer Research at Washington, DC, USA during April 17th – April 21st, 2010. She was awarded Dr.
Benjamin L. Van Duuren Award for her paper. She was amongst one of the three awardees in 2010 from amongst
Indian and African Fulbrighters in the fields of natural sciences and public health. The title of her presentation was:
Transforming growth factor beta as potential prognostic biomarker of breast cancer: Evidence of 'TGF-β switch'
(Abstract Number: 1754). This work was carried out at Receptor & grwoth Factor Laboratory, The Gujarat Cancer &
Research Institute, Ahmedabad and was a part of her Ph. D. project. Recently, she was awarded Ph. D. degree (Life
Sciences) from Gujarat University under the guidance of Dr. Sunil Trivedi. The title of her thesis was 'Study of
Transforming Growth Factor Beta Axis in Breast Cancer'.
We heartily congratulate our life member.
Volume 26 - Issue 2 November - 2010
Indian Association for Cancer Research
NEWSLETTER
15
Spotlight on……..
Dr. Pier Paolo Pandolfi,
Recipient of the Pezcoller Foundation-AACR International Award
for Cancer Research -2011
IACR family congratulates,Dr. Pier Paolo Pandolfi
for his success!!
Pier Paolo Pandolfi, M.D., Ph.D., is the recipient of
the 2011 Pezcoller Foundation-AACR International Award for Cancer Research for his
outstanding work in the field of cancer genetics and
mouse models for cancer. This work has
contributed to new therapies for treating cancers.
“Dr. Pandolfi's research has had a profound impact
on our understanding of the molecular
underpinnings of acute promyelocytic leukemia
(APL),” said Margaret Foti, Ph.D., M.D., chief
executive officer of the AACR. “His laboratory's
mouse models for various subtypes of APL have
shown efficacy when utilizing different drug
combinations. Clearly, this innovative research is
leading to progress in the treatment of other types
of cancer.”
Pandolfi is the George C. Reisman Professor of
Medicine and a Professor of pathology at Harvard
Medical School, Director of research at the Beth
Israel Deaconess Cancer Center, and Director of
the cancer genetics program and chief of the
division of genetics in the department of medicine
at the Beth Israel Deaconess Medical Center. His
studies have had an impact on the cancer research
arena by broadening the understanding of the
molecular basis of cancer.
The research carried out in Pandolfi's laboratory
has been important in understanding the molecular
mechanisms and genetics underlying the
pathogenesis of leukemias, lymphomas and solid
tumors, as well as in modeling these cancers in
mice.
Among his many accomplishments, Pandolfi and
colleagues have characterized the function of
oncoproteins and genes involved in the
chromosomal translocations of APL, as well as of
major tumor suppressors such as PTEN and p53,
and novel proto-oncogenes, such as POKEMON.
These accomplishments have led to the
development of novel and effective therapeutic
strategies, and, as a result, APL is now considered a
curable disease.
Additional novel therapeutic concepts have
emerged from Pandolfi's research, which are
currently being tested in clinical trials. More
recently, Pandolfi and colleagues have presented a
new theory describing how mRNA, both coding
and non-coding, exerts biological functions with
profound implications for human genetics, cell
biology and cancer biology.
Pandolfi received his medical degree in 1989 and
his doctorate in 1996 from the University of
Perugia in Italy, after he studied philosophy at the
University of Rome. He received postgraduate
training at the National Institute for Medical
Research and the University of London in the
United Kingdom.
In 1994, Pandolfi became an assistant member of
the molecular biology program and the department
of human genetics at Memorial Sloan-Kettering
Cancer Center. He grew through the ranks to
become a member in the cancer biology and
genetics program at the Sloan-Kettering Institute;
Professor of molecular biology and human
genetics, and Professor of molecular biology in
pathology and laboratory medicine at the Weill
Graduate School of Medical Sciences at Cornell
University; and head of the molecular and
developmental biology laboratories, and the
incumbent of the Albert C. Foster Endowed Chair
Volume 26 - Issue 2 November - 2010
16
NEWSLETTER
for Cancer Research at Memorial Sloan-Kettering
Cancer Center.
Among his lauded career experiences, Pandolfi has
also received numerous awards including: the
LLSA Scholar Award (1997); the Irma T. Hirschl
Trust Award (1999); the Alexandra J. Kefalides
Prize for Leukemia Research (1999); the Hamdan
Award for Medical Research Excellence (2000);
the Lombroso Prize for Cancer Research of the
Weizmann Institute of Science (2001); the
Leukemia and Lymphoma Society's Stohlman
Scholar Award (2001); the William and Linda
Steere Foundation Award (2004); and, the prize for
Scientific Excellence in Medicine from the
American-Italian Cancer Foundation (2005).
He also has been awarded the National Institutes of
Health MERIT Award, the Fondazione Cortese
International Award, the Prostate Cancer
Foundation Creativity Award and the Ischia
International Award. In 2006, Pandolfi was elected
as a member of the American Society for Clinical
Investigation and the American Association of
Physicians, and the following year he became a
member of the European Molecular Biology
Organization.
The Pezcoller Foundation-AACR International
Award, recognizes an individual scientist of
international renown who has made a major
scientific discovery in basic or translational cancer
research.
Volume 26 - Issue 2 November - 2010
Indian Association for Cancer Research