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NF-κB–driven suppression of FOXO3a contributes to EGFR
mutation-independent gefitinib resistance
Abstract
Therapy with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors
(EGFR-TKIs, such as gefitinib or erlotinib) significantly prolongs survival time for
patients with tumors harboring an activated mutation on EGFR; however, up to 40%
of lung cancer patients exhibit acquired resistance to EGFR-TKIs with an unknown
mechanism. FOXO3a, a transcription factor of the forkhead family, triggers apoptosis,
but the mechanistic details involved in EGFR-TKI resistance and cancer stemness
remain largely unclear. Here, we observed that a high level of FOXO3a was
correlated with EGFR mutation-independent EGFR-TKI sensitivity, the suppression
of cancer stemness, and better progression-free survival in lung cancer patients. The
suppression of FOXO3a obviously increased gefitinib resistance and enhanced the
stem-like properties of lung cancer cells; consistent overexpression of FOXO3a in
gefitinib-resistant lung cancer cells reduced these effects. Moreover, we identified that
miR-155 targeted the 3′UTR of FOXO3a and was transcriptionally regulated by
NF-κB, leading to repressed FOXO3a expression and increased gefitinib resistance, as
well as enhanced cancer stemness of lung cancer in vitro and in vivo. Our findings
indicate that FOXO3a is a significant factor in EGFR mutation-independent gefitinib
resistance and the stemness of lung cancer, and suggest that targeting the
NF-κB/miR-155/FOXO3a pathway has potential therapeutic value in lung cancer with
the acquisition of resistance to EGFR-TKIs.
SABR vs conventional fractionated radiotherapy in early-stage NSCLC:
preliminary CMUH experiences
Background: Stereotactic ablative radiotherapy [SABR] was an attracting alternative
for non-operated early stage non-small cell lung cancer [NSCLC] when compared to
conventional fractionated radiotherapy [CFRT]. To our knowledge, however, there
was not high level evidence yet as stated in a review paper [Eur J Cancer 2014; 50(3):
525-34]. Therefore, we aimed to share our preliminary experiences regarding the
clinical outcomes of patients treated by either SABR or CFRT.
Methods: We identified non-operated early stage [T1-3N0M0] NSCLC patients
treated with either SABR or CFRT within Jan, 2012 to Feb, 2016 via our department
registration. Clinical variables and outcomes were collected via chart review after
double checked with refereeing physicians in late Jun, 2016. We used the date of start
of radiotherapy [RT] as the index date. Local control was evaluated via
cross-sectional image like computed tomography or positron emission tomography.
Disease status was determined based on overall clinical information. Survival status
was evaluated via medical record as well as information from hospital cancer registry.
We also evaluated if there was any complication related in-patient care as determined
by discharge diagnosis. Kaplan-Meier method and log rank test was used for
statistical analysis.
Results: Sixteen patients were included in our analysis. Most of them were male
[n=14] and aged [all >=75 y/o except 71 y/o for one and 57 y/o for another]. Most of
them were squamous cell carcinoma [n=7] or adenocarcinoma [n=7]. Eight patients
were treated with SABR while another eight patients were treated with CFRT. After
median follow-up of 23 months [range 4 – 48], the 2-year overall survival rates for
SABR vs CFRT were 67% vs 73%, respectively. The 3-year overall survival rates for
SABR vs CFRT were 67% vs 48% [p-value 0.8], respectively. The 2-year local
control rates for SABR vs CFRT were 100% vs 50%, respectively. The 3-year local
control rates for SABR vs CFRT were 100% vs 25%, respectively. The 2-year
progression-free survival rates for SABR vs CFRT were 35% vs 29%. The 3-year
progression-free survival rates for SABR vs CFRT were 35% vs 14% [p-value =0.41],
respectively. No patients had been admitted due to RT side effect except one received
CFRT had been admitted due to RT pneumonitis five months after RT completed.
Conclusions: When compared to CFRT, SABR achieved excellent local control and at
least non-inferior overall survival for non-operated early stage NSCLC. Our
experiences should be interpreted with caution given the imbalance in baseline
characteristics, small case number, short follow-up, and the non-randomized treatment
selection.
Nivolumab EAP experience in NSCLC
John Wen-Cheng Chang
Background: Nivolumab was approved in both squamous (CheckMate-017) and
non-squamous type of non‑small cell lung cancer (NSCLC) (CheckMate-057). Here
we present our experience of nivolumab expanded access program in NSCLC.
Methods: Stage III/IV patients with histologically proven NSCLC were enrolled in
this EAP study if they failed cisplatin-based chemotherapy. Eligible patients were
treated with nivolumab 3 mg/kg every 2 weeks. The response was evaluated by
computed tomography (CT) scan after 6th dose. Toxicities, especially immune-related
adverse events (irAEs) were evaluated by the principal investigators and by the
immune oncology group. Progression‑free survival (PFS) and overall survival(OS)
were assessed by Kaplan-Meier survival analysis.
Results: Thirteen patients were enrolled in this study. Median age was 58 years.
Eleven (85%) were male. Adenocarcinoma comprised 46%; squamous cell carcinoma,
46%; adenosquamous cell carcinoma, 8%. Stage III and IV were 23% and 77%,
respectively. A total of 6 patients were evaluated by at least one CT scan. Three cases
experienced tumor shrinkage and the other 3 cases were disease progression. One
grade 3 skin irAE with itchy maculopapular rash over face, anterior and posterior
trunk on day 6 after the first dose of nivolumab was treated successfully with systemic
steroid. Another case experienced rapid accumulation of pleural effusion whose
cytology was negative for malignancy. No treatment-related death was encountered.
We have observed an increased CD8+ T cells infiltration from an enlarging sternal
mass biopsy. Other data will be presented in the meeting.
Conclusions: Nivolumab is active in our patients with NSCLC. The irAEs were
manageable with adequate timing and dose of systemic steroid and best supportive
care.
Role of GSK3BETA-MEDIATED EZH2 PHOSPHORYLATION in LUNG
CANCER
How-Wen Ko
Department of Thoracic Medicine
Chang Gung Memorial Hospital at Linko
Despites advances in treatment, tumor recurrence and metastasis are still the
major obstacles in anti-cancer management. For example in lung cancer, it is
still the leading cause of cancer-related death in Taiwan and worldwide. The
5-year overall survival rate for stage I patients is around 60%, that of patients
with distant metastatic disease falls to less than 5%. Therefore, a better
understanding of the molecular mechanisms underlying cancer pathogenesis
is important and will potentially contribute to the development of novel
therapeutic strategies. Enhancer of zeste homolog 2 (EZH2) is a
methyltransferase. It is the enzymatic core subunit of polycomb repressive
complex 2 (PRC2), promotes cell growth and migration through catalyzing
trimethylation of histone H3 at Lys 27 (H3K27me3). Evidence has shown that
EZH2 is highly expressed in many types of solid tumors, including lung and
breast cancer, and its higher expression is associated with aggressive disease
and poor outcome, suggesting that it is important in tumorigenesis. During the
process of tumorigenesis, inactivation of tumor suppressors is a critical step.
EZH2’s expression can be controlled by phosphorylation. However, the
regulation of EZH2 activity by tumor suppressor kinase is not well understood.
Glycogen synthase kinase 3 beta (GSK3), a multifunctional serine/threonine
kinase, is involved in many cellular processes. GSK3 also participates in
neoplastic transformation, tumor development and regulate cancer cell
metastasis. Inactivation of GSK3 contributes to tumor development in certain
types of cancers. Most GSK3 substrates contain a phosphorylation motif
(Ser/Thr-X-X-X-Ser/Thr, where X is representative of any amino acid).
Interestingly, we noticed that the EZH2 amino acid sequence contains this
motif, suggesting that EZH2 might be regulated by GSK3. In this study, we
investigated their interaction and, indeed, validated that GSK3 physically
interacts with EZH2 in NSCLC and many other cells. We further examined
whether GSK3 regulate EZH2 activity and found that inhibition of GSK3 by a
GSK3 inhibitor, lithium chloride, increases EZH2 downstream, H3K27
trimethylation expression; conversely, enhancing GSK3 activity using a
GSK3 enhancer, the anticancer drug staurosporine, reduced the H3K27
trimethylation level. There was no change in EZH2 level. Through a mass
spectrometry analysis and in vitro kinase assay, we confirmed that GSK3
phosphorylates EZH2 at Ser363 and Thr367. Cells expressing
GSK3nonphosphorylatable mutant EZH2 have higher H3K27me3 level and,
consistently, GSK3phospho-mimic mutant EZH2 expressing cells have lower
H3K27me3 expression. In addition, nonphosphorylatable mutant EZH2
enhanced ability of cell migration and anchorage-independent growth. To
examine the pathological relevance of EZH2 regulation by GSK3, we
analyzed correlation between the activity of GSK3 and the enzymatic activity
of EZH2 in human tumor specimens. Similarly, immunohistochemical staining
revealed that inactivation of GSK3 as measured by its phosphorylation at
Ser9 is positively correlated with higher level of H3K27 trimethylation,
suggesting that GSK3 activity is inversely related to EZH2 activity.
Collectively, this study indicates that GSK3 has a critical role in regulating
EZH2-mediated oncogenesis. Because of EZH2’s importance in tumorigenesis,
several inhibitors targeting EZH2 have been developed and tested in
preclinical and clinical trials. Moreover, a significant portion of NSCLC patients
harbors KRAS or EGFR mutation, both can lead to inactivation of GSK3.
Thus, the regulation identified in this study potentially provides a therapeutic
strategy that GSK3 inactivation may be a useful marker to guide anti-EZH2
treatment in NSCLC patients.
Abstract
We used CT features of small pulmonary nodules to quantify their characteristics
from thin-section CT images and 10 machine learning classifiers to achieve the
highest classification accuracy for these nodules of different benign and malignant
classes. 122 small nodules (1.14±0.45 cm) were reviewed from 103 patients
undergoing a wedge resection or lobectomy after a preoperative CT localization.
Thin-section CT images were acquired for manual delineation and quantitative
analysis with 374 CT features. Nodules were first divided into groups of 48 benign
lesions (B) and 74 malignant lesions (M). Then the benign group was further divided
into 14 intrapulmonary lymph nodes (B1) and 34 other benign nodular lesions (B2),
while malignant subgroups included 48 primary non-small cell lung cancer tumors
(M1) and 26 metastatic tumors (M2). Machine learning classification was repeated
100 times to determine the accuracy and corresponding uncertainties. 64% of CT
features was discriminative for B-M; 11% for B1-B2; 58% for M1-M2. Shape-related
features suggested the average morphology of M1 nodules appeared irregular than
that of M2. The baseline accuracy was 74/122=60% for B-M; 34/48=71% for B1-B2;
48/74=65% for M1-M2. The highest classification accuracy for B-M was 78.93%
and a 30% increase over the baseline; 81.75% accuracy for B1-B2 and 15% increase;
86.30% accuracy for M1-M2 and 33% increase. In a clinical scenario where
thin-section CT was used to follow up the small nodules detected by low-dose lung
screening CT, our computer-aided work may further assist risk assessment and
management for these nodules.
Diagnostic Performance of FDG-PET/MRI for
Mediastinal Lymph Node Metastases in Non-Small Cell
Lung Cancer
Abstract
FDG PET/CT has become the reference standard in oncologic
imaging and impact on cancer staging and restaging significantly. The
promise of PET/MRI includes multiparametric imaging to further
improve diagnosis and phenotyping of cancer(1). The available data show
that FDG PET/MRI and PET/CT provide comparable diagnostic
information when MRI is used simply to provide the anatomic framework.
Diagnostic advantages may be achievable in prostate cancer and in bone
metastases, whereas disadvantages exist in lung nodule assessments.
Therefore, we should explore the multiparametric potential of MRI,
especially when the evaluation of mediastinal or hilar lymph nodes by
PET/CT may be interfered by chronic inflammation or tuberculosis in
high risk environments(2).
During the last decade, diffusion-weighted MR imaging (DWI),
which is highly sensitive to micro-environmental alterations at the
cellular level, has proven to be a valuable method for tracing of
microscopic tissue structure. DW-MRI offers quantitative and early
imaging biomarkers of tumor staging, therapeutic response and clinical
outcome. For diagnosing malignant pulmonary nodules/masses, DWI and
PET showed sensitivities of 0.70 and 0.72 and specificities of 0.97 and
0.79, respectively(3). Although there was no significant difference in
sensitivity between the two methods, DWI showed a significantly higher
specificity than PET because of fewer false-positives for active
inflammatory lesions (p= 0.03). In the N-staging of lung cancer,
DW-MRI without proper respiratory or cardiac gating techniques does
not show a clear advantage over conventional MRI. Apparent diffusion
coefficient (ADC) has significant inverse correlation with tracer uptake
(SUV), which points out the association of metabolic activity and tumor
cellularity. With proper settings of DW-MRI, the accuracy (91%) with
DWI was significantly higher than that (48%) with PET-CT for multiple
hilar and mediastinal lymph nodes (P=0.0129)(4).
With better soft tissue contrast of MRI, hybrid PET/MRI has
substantial interobserver agreement in N staging and lead to comparable
therapeutic decisions of PET/CT. PET/MR can be considered an
alternative to PET/CT for NSCLC staging just based on conventional
techniques. The introduction of quantitative DW-MRI and hybrid
PET-MRI biomarkers into the treatment management of patients with
lung cancer may aid physicians to individualize therapy, thereby
minimizing unnecessary systemic toxicity associated with ineffective
therapies, saving valuable time, reducing patient care costs and ultimately
improving clinical outcome(5).
References
1.
Rauscher I, Eiber M, Furst S, Souvatzoglou M, Nekolla SG, Ziegler SI, et al. PET/MR
imaging in the detection and characterization of pulmonary lesions: technical and diagnostic
evaluation in comparison to PET/CT. J Nucl Med. 2014;55(5):724-9. doi:
10.2967/jnumed.113.129247. PubMed PMID: 24652827.
2.
Heusch P, Buchbender C, Kohler J, Nensa F, Gauler T, Gomez B, et al. Thoracic staging in
lung cancer: prospective comparison of 18F-FDG PET/MR imaging and 18F-FDG PET/CT. J
Nucl Med. 2014;55(3):373-8. doi: 10.2967/jnumed.113.129825. PubMed PMID: 24504054.
3.
Mori T, Nomori H, Ikeda K, Kawanaka K, Shiraishi S, Katahira K, et al. Diffusion-weighted
magnetic resonance imaging for diagnosing malignant pulmonary nodules/masses:
comparison with positron emission tomography. J Thorac Oncol. 2008;3(4):358-64. doi:
10.1097/JTO.0b013e318168d9ed. PubMed PMID: 18379353.
4.
Usuda K, Maeda S, Motono N, Ueno M, Tanaka M, Machida Y, et al. Diffusion Weighted
Imaging Can Distinguish Benign from Malignant Mediastinal Tumors and Mass Lesions:
Comparison with Positron Emission Tomography. Asian Pac J Cancer Prev.
2015;16(15):6469-75. PubMed PMID: 26434861.
5.
Galban CJ, Hoff BA, Chenevert TL, Ross BD. Diffusion MRI in early cancer therapeutic
response assessment. NMR Biomed. 2016. doi: 10.1002/nbm.3458. PubMed PMID:
26773848.
Abstract
Lung cancer is a leading cause of death worldwide. In Taiwan, the incidence of
death caused by lung cancer in 2012 was 25.5 deaths per 100,000 population.
According to National Comprehensive Cancer Network guideline, the standard
treatment modality in resectable non-small cell lung cancer is anatomic resection with
mediastinal lymph node dissection. As low dose computed tomography was
utilized as screening tool, more early stage lung cancer which presented as ground
glass opacity or partial sold lesion were identified after surgical resection.
According to literature review, around 5 % detection rate was identified as early stage
lung cancer in high risk populations. However, for solitary pulmonary nodules, the
whole consensus of management still depended on size criteria.
In National
Comprehensive Cancer Network guideline, solitary pulmonary lesion was divided
into 4 categories, including < 8 mm pulmonary nodules, ≧ 8 mm non calcified
pulmonary nodule, ≤ 10 mm non solid and partial solid pulmonary nodule and those
pulmonary lesion. Only clinical suspicious lesions which presented hot spot lesion
in PET-CT or increased in size, surgical biopsy was recommended and corresponding
therapy would be given to it stage.
In lung RADS category, which was utilized by
radiologist, it was also depended on the diameter.
For patients who belonged to category 1 to3, the probably of malignancy was around
1 to 2 %. For patients was classified into category 4, the risk of malignancy was
around 5to 15 % and more aggressive surveillance program or surgical biopsy was
recommended. However, the guidelines did not reveal the clinical significance
between image and final histopathology presentations.
The standard treatment modality in resectable non-small cell lung cancer is
anatomic resection with mediastinal lymph node dissection. In National
Comprehensive Cancer Network guideline, thoracoscopic lobectomy become an
acceptable approach for lung cancer patient because of comparable survival result,
less pain and complications. As the advance of surgical technique, thoracoscopic
segmentectomy and mediastinal lymph node dissection was done in elderly patients
and those with comorbidities. From literature review, similar survival outcome and
identified in early stage lung cancer. In addition, sub-centimeter lung cancers with a
GGO component on HRCT can be considered "early" lung cancers because of no
lymph node metastases. In these cases, limited resection may be warranted to
achieve a cure. However, the relationship between image presentation and final
histopathology characteristic was not clarified.
In this study, we retrospective
review the non cell lung cancer patients who receive lobectomy and mediastinal
lymph node dissection between 2010 January to 2014April and try to identify the
relationship between image characteristics and final histo-patholgic presentations.
This would provide more useful clinical information in management solitary
pulmonary nodule instead of size criteria that utilized in current guidelines. In
addition, more accurate surgical approach, such as segmentectomy and lobectomy,
could be decided by pre-operation image clues.
Surgical treatment and outcome of patients with early stage
non-small cell lung cancer - impact of new WHO adenocarcinoma
histologic classification
Lung cancer is the leading cause of cancer deaths worldwide. For early-stage
non-small cell lung cancer (NSCLC), surgical resection is the treatment of choice for
curative-intent therapy. Five-year survival in patients with resected stage I NSCLC
ranges between 55% and 80%.Tumor recurrence is the most common cause that leads
to mortality after a curative resection. Among the stage I NSCLC, 30% to 40% of
patients develop tumor recurrence after surgical resection.
The seventh edition of the TNM classification for lung cancer has been published in
2009, and our previous studies have reported the surgical outcomes of complete
resected early stage NSCLC and analyzed the prognostic factors and recurrence
pattern as well by using the previous and new TNM definition and classification. In
2011, the International Association for the Study of Lung Cancer (IASLC), The
American Thoracic Society (ATS), and the European Respiratory Society (ERS)
proposed a new classification system for lung adenocarcinoma, which had been
adapted and published in the 2015 World Health Organization (WHO) classification
of lung tumors. A large amount of studies, including ours, have reported the impact of
the new classification on death and recurrence in lung adenocarcinoma. Our data
demonstrated that micopapillary and solid predominant subtypes were significantly
poor prognostic factors for death and recurrence among patients undergoing resection
for lung adenocarcinoma. More recently, we investigated the effect of adjuvant
chemotherapy and the predictors of benefit from adjuvant chemotherapy in patients
with stage IB lung adenocarcinoma. We reported firstly in the literature to show the
predictive value of a micropapillary/solid–predominant pattern for benefits from
adjuvant chemotherapy in stage IB lung adenocarcinoma.
In this report, we will present our research data and review the update literature
regarding this new classification and discuss its clinical impact in combining with the
7th edition of the TNM system among the patient with early stage lung cancer. This
information is important for designing the future clinical trials concerning the optimal
surgical resection margin and selection of patients to receive postoperative adjuvant
therapy.
Functional lung avoidance by individualized proton therapy
Radiation therapy is one of the mainstay therapies for localized lung
cancer. In spite of the advances of the treatment techniques, radiation
therapy could be associated with substantial pulmonary toxicity in some
patients. Current radiotherapy planning techniques aim to minimize the
radiation dose to the lungs, without accounting for regional variations in
lung function. This approach does not account for the fact that lung tissue
can be heterogeneous, especially in smokers or patients with chronic
obstructive pulmonary disease (COPD), whose lungs are frequently
characterized by large regions of unventilated parenchyma such as bullae.
Ideally, radiotherapy treatment planning should be able to exploit these
regional differences in lung function by minimizing dose to the more highly
functional lung while favoring radiation deposition in areas of less
highly-functioning or non-functioning lung.
It has been hypothesized that preferential avoidance of normal
functional lung during radiotherapy may reduce toxicity. However, it is
difficult to achieve good avoidance by photon beam. In conventional photon
irradiation, the highest radiation dose is delivered directly on entry into the
body and the beam traverses the body. With modern volumetric modulated
arc therapy (VMAT), the high dose regions of photon therapy can conform
to the target, but there are substantial low dose region along the photon
beam direction. In contrast, protons traveling in tissues follow a
predetermined track, have minimal side scatter, and deliver most of their
energy near the end of their track. This property can be used to shape the
dose distribution to fit virtually any tumor volume with limited low dose
regions. Proton therapy, with few entrance beams and limited dose ranges, is
ideal to reduce the pulmonary toxicity by avoiding the normal functional
lung.
Over the last decade, functional measurements and maps can be
obtained from thoracic imaging, such as single photon emission computed
tomography (SPECT), high resolution four-dimensional x-ray computed
tomography (4DCT), and hyperpolarized noble gas magnetic resonance
imaging (MRI). In this preliminary study, we explore the feasibility for
mapping the pulmonary function by using lung perfusion scan and 4-D
ventilation scan (Vespir, provided by Dr. Kipritidis, University of Sydney).
After incorporated to the proton treatment planning system (Eclipse version
13.1), both studies had good geometric correlation. The perfusion scan
showed more directional dependence on gravity than the 4-D ventilation
scan. The applications of these image modalities on proton treatment plan
could reduce the lung toxicity by specific avoidance of functional lung.
Alterations of the EGFR and Hippo/ Yes-associated protein (YAP) pathway
have been found in non-small cell lung cancer (NSCLC).
In part 1, we have investigated the connection between ERK1/2 and
Hippo/YAP pathway in NSCLC. Herein, we show that ERK1 and ERK2 have
an effect on the Hippo/YAP pathway in human NSCLC cells. Firstly, inhibition of
ERK1/2 by siRNA or small-molecular inhibitors decreased the YAP protein level,
the reporter activity of the Hippo pathway, and the mRNA levels of the Hippo
downstream genes, CTGF, Gli2, and BIRC5. Secondly, degradation of YAP
protein was accelerated after ERK1/2 depletion in NSCLC cell lines, in which
YAP mRNA level was not decreased. Thirdly, forced over-expression of the
ERK2 gene rescued the YAP protein level and Hippo reporter activity after
siRNA knockdown targeting 3'UTR of the ERK2 gene in NSCLC cells. Fourthly,
depletion of ERK1/2 reduced the migration and invasion of NSCLC cells.
Combined depletion of ERK1/2 had a greater effect on cell migration than
depletion of either one separately. Finally, the MEK1/2 inhibitor Trametinib
decreased YAP protein level and transcriptional activity of the Hippo pathway in
NSCLC cell lines. Our results suggest that ERK1/2 inhibition participates in
reducing YAP protein level, which in turn down-regulates expression of the
downstream genes of the Hippo pathway to suppress migration and invasion of
NSCLC cells.
In part 2, we have shown that YAP Promotes Erlotinib Resistance in
Human NSCLC Cells. YAP is a main mediator of the Hippo pathway, which
promotes cancer development. Here we show that YAP promotes resistance to
erlotinib in human NSCLC cells. We found that forced YAP overexpression
through YAP plasmid transfection promotes erlotinib resistance in HCC827
(exon 19 deletion) cells. In YAP plasmid-transfected HCC827 cells, GTIIC
reporter activity and Hippo downstream gene expression of AREG and CTGF
increased significantly (P<0.05), as did ERBB3 mRNA expression (P<0.05).
GTIIC reporter activity, ERBB3 protein and mRNA expression all increased in
HCC827 erlotinib-resistance (ER) cells compared to parental HCC827 cells.
Inhibition of YAP by small interfering RNA (siRNA) increased the cytotoxicity of
erlotinib to H1975 (L858R+T790M) cells. In YAP siRNA-transfected H1975
cells, GTIIC reporter activity and downstream gene expression of AREG and
CTGF decreased significantly (P<0.05). Verteporfin, YAP inhibitor had an
effect similar to that of YAP siRNA; it increased sensitivity of H1975 cells to
erlotinib and in combination with erlotinib, synergistically reduced migration,
invasion and tumor sphere formation abilities in H1975 cells. Our results
indicate that YAP promotes erlotinib resistance in the erlotinib-sensitive
NSCLC cell line HCC827. Inhibition of YAP by siRNA increases sensitivity of
erlotinib-resistant NSCLC cell line H1975 to erlotinib.
In part 3, we have shown that YAP regulates cancer stem cell-like
properties via ABCG2 in human lung cancer cells. A small population of
cancer cells called cancer initiating cells or cancer stems cells (CSCs) involved
in drug resistance, metastasis, and cancer relapse. Finding pathways
regulating CSCs properties is very important for clinical therapy. ATP-binding
cassette sub-family G member 2 (ABCG2) plays a role in the side population
(SP) cell formation and contributes to chemotherapy resistance in common
forms of cancers. We asked whether YAP regulates ABCG2 in lung cancer
cells. In this study, we found ABCG2 and YAP were both overexpressed in lung
cancer SP cells. Disruption of YAP expression by siRNA attenuated the
expression of ABCG2 transcript and protein and significantly reduced the SP
fraction in lung cancer cells. Overexpression of YAP in lung cancers led to an
increase in ABCG2 expression and increased SP fraction. YAP directly
transcriptionally regulated ABCG2 by co-binding to the promoter of ABCG2
(with TEAD). Moreover, the YAP inhibitor vertepofin downregulated ABCG2
level through inhibition of YAP in lung cancer cells and sensitized them to the
chemotherapy drug doxorubicin. Our study adds new function for YAP that
may be relevant to drug resistance and cancer therapy through regulation of
ABCG2.
In part 4, we have shown that YAP is an oncogenic driver and a key
therapeutic target of mesothelioma. Malignant pleural mesothelioma
(mesothelioma) is a very aggressive form of cancer that resistant to current
therapy. The poor prognosis of this disease has been associated with elevated
Yes-associated protein (YAP) activity due to mutations of Hippo pathway
components. Here, we show that specific targeting of YAP has a remarkable
effect on the Hippo pathway and tumor activity of human mesothelioma cells.
Firstly, overexpression of YAP was detected in 62.5% (40/64) of clinical
samples with nuclear staining by immunohistochemistry and in 4/6
mesothelioma cell lines by real-time PCR. TEAD4, which belongs to TEAD
family of transcription factors and mediates the biological function of YAP, was
also overexpressed in 54.7% (35/64) of these tissues and in the same 4/6
mesothelioma cell lines. Secondly, silencing of YAP by siRNAs down-regulated
the reporter activity of the Hippo pathway, whereas forced over-expression of
the YAP gene rescued the Hippo reporter activity after siRNA knockdown
targeting 3’UTR of the YAP gene in mesothelioma cells. Thirdly, the YAP
inhibitor verteporfin, which disrupts the formation of the YAP-TEAD complex,
also down-regulated transcriptional activity of the Hippo pathway in
mesothelioma cell lines. Fourthly, verteporfin treatment showed high sensitivity
to decrease the cell viability of mesothelioma cell lines. Finally, inhibition of
YAP by verteporfin treatment reduced the migration, invasion and self-renewal
of cancer stem cells in mesothelioma cells. Our results collectively suggest
that YAP is an oncogenic driver and a key therapeutic target of mesothelioma.
In part 5, we have recently been investigating the role of Hippo/YAP
signaling in metastasis of lung adenocarcinoma and mesothelioma in
several animal models. In addition, we are currently investigating and
developing small molecule inhibitors targeting Hippo/YAP pathway for targeted
therapy of lung cancer and mesothelioma.
Image-guided photon and proton radiotherapy in early stage NSCLC: Aim for a
cure
Joe Y. Chang, MD, PhD, Professor
Director of Stereotactic Ablative Radiotherapy, MD Anderson Cancer Center
Non–small cell lung cancer (NSCLC) remains the number one cause of cancer death
in the world. It is anticipated that the incidence and mortality will continue to increase
worldwide due to smoking, environmental pollution, and an aging population. The
anticipated increase in curable lung cancer incidence due to lung screening throughout
the world demands more effective and less morbid treatments for lung cancer.
Clinical studies in early stage NSCLC have shown that ablative dose can improve
local disease control and potentially impact survival. For example, stereotactic
ablative radiotherapy, which delivers a biological effective dose (BED), of greater
than 100 Gy achieves local control rates of >95% and improves overall survival
compared with conventional radiotherapy. Randomized studies indicated that SABR
is better tolerated—and might lead to better overall survival—than surgery for
operable clinical stage I NSCLC. These findings justify a larger randomised clinical
trial to investigate the superiority of SABR for such patients. SABR should be
considered as an option for treatment of operable stage I NSCLC (Chang et al: Lancer
Oncology 16:630, 2015).
Conventional radiotherapy, in addition to its well-established tumoricidal effects, can
also activate the host immune system. Radiation therapy modulates tumour
phenotypes, enhances antigen presentation and tumour immunogenicity, increases
production of cytokines and alters the tumour microenvironment, enabling destruction
of the tumour by the immune system. Investigating the combination of radiotherapy
with immunotherapeutic agents, which also promote the host antitumour immune
response is, therefore, a logical progression. As the spectrum of clinical use of
stereotactic radiotherapy continues to broaden, the question arose as to whether the
ablative radiation doses used can also stimulate immune responses and, if so, whether
we can amplify these effects by combining immunotherapy and stereotactic ablative
radiotherapy (SABR). Preclinical and Clinical data on the effectiveness of combining
these two techniques - immunotherapy and SABR - in an approach that we have
termed 'ISABR', have demonstrated promising results (Bernstein and Chang et al:
Nature Review Clinical Oncology March 8, 2016).
The unique characteristic of proton therapy is the Bragg peak which deposits the bulk
of its cancer killing at a particular depth. The Bragg peak is depended on the
protons’ initial energy and density/depth of the tissue in the beam path. PT decreases
radiation exposure to organs at risk.
Unlike photons that cause ionizing damage of
DNA throughout the beam penetration, including the significant exit dose, protons
have the potential to reduce radiation-induced toxicities by their lack of exit dose.
These features of proton therapy could be particularly beneficial in patients who have
poor pulmonary function, cardiovascular disease, recurrent disease, or other
individuals at high-risk to develop severe side effects in general (such as the elderly).
Despite proton therapy’s theoretical advantages, there is debate in the oncology
community for its use in lung cancer. First, the technical challenges of proton therapy
limit its broad adoption. Second, due to the higher cost of proton therapy, a definitive
side-by-side comparison of proton therapy with modern photon radiotherapy such as
intensity-modulated radiotherapy (IMRT) or volumetric intensity modulated arc
therapy (VMAT) is needed. PTCOG thoracic subcommittee task group reviewed the
potentials, limitations and future optimization of proton therapy in early-stage and
advanced NSCLC (Chang et al: Int J Radiat Oncol Biol Phys. 2016 May
1;95(1):505-16). For early stage NSCLC, proton therapy delivers excellent dose
distributions in patients with early-stage NSCLC with associated high rates of local
control and survival. However, similar outcomes have been achieved with the use of
SABR using photon, which is more widely available, diminishing the relative benefits
to some degree. Nevertheless, patients with larger early-stage tumors and tumors
located more centrally or close to the brachial plexus may benefit more from the use
of proton therapy. In particular, in patients who do not meet dosimetric constraints
with photon based on SABR, proton therapy may allow patients to receive a more
effective treatment than standard fractionated radiation therapy. The use of volumetric
image guidance will help to minimize the PTV margin such that target volume
comparisons between proton therapy and SBRT are identical. The biological
effectiveness of proton therapy in different tumors with different genetic profiles and
its combination with systemic therapy such as immunotherapy need to be further
investigated.
PET/MR in lung imaging: Potential and pitfall
PET/MR permits simultaneous or near simultaneous acquisition of morphologic and
functional MR information with metabolic PET information. Synergistic combination
of metabolic and MR information could potentially have tremendous impact on
diagnosis, staging, and management of various malignancies including lung cancer.
Despite this potential, there remain various challenges and unsolved problems in
implementing PET/MR in clinical practice. This talk will focus on opportunity and
challenges of PET/MR in lung imaging.
Management of Ground Glass Opacities.
The rate of detection of patients with ground glass opacities has been increasing.
Often patients are seen that have more than one such lesion. Management of these
patients has been difficult, because they present a number of clinical questions,
including 1) Is this a lung cancer? 2) Is this a cancer that will cause problems
(symptoms, mortality) over the next 5-10 years? 3) What are the right triggers for
intervention? 4) What intervention is needed? 5) Are multiple lesions related to one
another? 6) What causes these lesions to develop? 7) What accounts for the increase
in prevalence? This talk will review the data that pertains to these questions and
attempt to provide a framework for patient management.