Download Cell transformation

Development of transformed
cell
Seminar of Molecular and Cell Biology
Mgr. Jan Šrámek
[email protected]
Syllabi
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Cell transformation
Characteristic of tranformed cells
Mechanisms of transformation
Cancerogenes
Tumors nad their classification
Cancer therapy
Cell transformation
• Process of transformation of normal cell that react to feedback
homeostatic mechanisms to cell with autonomous growth and
ability of invasion.
• All cancer cell are transformed cell
• But! Not all transformed cells are cancer cells (e.g. cells of cell
cultures)
Characteristic of tranformed cells
Abnormal proliferation in space and time represents basic characteristic of
transformed (tumor) cells.
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Independence on stimulatory cytokines
Loss of ‘anchorage dependence’
Capability of non-regulated clonal growth and loss of contact inhibition
Immortality (no dependence on ‘lifespan limit’) and resistance to apoptosis
Inability to differentiate
Increase activity of telomerase
Ability of angiogenesis
Different cell surface molecules and chromosomal reconstruction
Genetic instability
(ability to survive in host organism)
Mechanisms of transformation
• Multistage process (cancer incidence correlates with age)
• Non-returnable process
• Under selection stress
• Spontaneous x induced
• Genetic changes (mutations):
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Cancer incidence is 10-8 (includes 4 mutations, spontaneous mutation incidence is 10-6 per
one cell division, number of cell divisions in human life is 1016; 10(-6)x4/1016 = 10-8)  1 human
per 100 milion x reality
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Influence of other factor: mutagenes, immune system
Multistage process
sequential acumulation of genetic changes (4–7 mutations), according to dozens of
different genes
Cancer cell
1. mutation
2. mutation
3. mutation
4. mutation
Mechanisms of transformation
• Multistage process (cancer incidence correlates with age)
• Non-returnable process
• Under selection stress
• Spontaneous x induced
• Genetic changes (mutations)
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Cancer incidence is 10-8 (includes 4 mutations, spontaneous mutation incidence is 10-6 per
one cell division, number of cell divisions in human life is 1016; 10(-6)x4/1016 = 10-8)  1 human
per 100 milion x reality
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Influence of other factor: mutagenes, immune system
Process under the selection stress
Mechanisms of transformation
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Multistage process (cancer incidence correlates with age)
Non-returnable process
Under selection stress
Spontaneous x induced
Genetic changes (mutations)
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Cancer incidence is 10-8 (includes 4 mutations, spontaneous mutation incidence is 10-6 per
one cell division, number of cell divisions in human life is 1016; 10(-6)x4/1016 = 10-8)  1 human
per 100 milion x reality
Influence of other factor: carcinogens, immune system
Immune system
Cancer incidence
Cancer incidence
10-8
10-8
Carcinogens
Theory of immune survailence
Cancer incidence is higher due to loss of
immune system efficiency
▫ Majority of cancer cells is eliminated by
immune system in organism (Tclymphocytes).
▫ Sooner, mean lifespan was about 35–40
years. Nowadays, mean lifespan increased
markedly in western countries.
▫ Maximum efficiency of immune system is
between 30–40 years of life.
The main role of genetic changes
▫ Accumulation of genetic changes (mutations)
▫ Primary role of oncogenes and antioncogenes (tumor-supressor genes)
▫ Change of function (quality) and/or level of expression (quantity) of onco/antioncogenes via:
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Point mutations
Deletions
Chromosomal translocations
Gene amplifications
(c-abl)
(c-abl)
(c-ras)
(c-ras)
(c-myc, c-myb,
c-myb, N-ras)
N-ras)
(c-myc,
Philadelphia chromosome
Regulation domain
Tyrosin-kinase domain
Reciprocal translocation between the 9th and 22nd chromosome.
Fusion of Bcr (22nd Chromosome) and of Abl genes (proto-oncogene [tyrosin kinase] of 9th chromosome).
Bcr protein is extensively produced in lymphocytes and has unclear function.
Bcr/Abl fusion protein p210 has encrease tyrozin-kinase activity (no regulation domain)  no regulation of
signaling.
Responsible for many types of leukemia.
Point mutation of c-ras gene
Ras
Ras protein has GTP function
Signaling molecule
Mutation of c-ras gene leads to continuous activation of Ras protein  increase expression of proteins
stimulating cell division  tumor development
Carcinogens
Cause genetic changes via interactions with DNA leading to cell
transformation.
Factors causing cell transformation:
• Chemical
• Physical
• Biological
Chemical carcinogens
Cause transitions, transversions, bases modifications or covalentely bind to DNA
Cause 80 % of all human tumors
Bases analogs: 5-bromuracil (BU) – supersede T  base transition
Agens modifying bases:
HNO2: deamination of C on U, A on hX, G on X  transition
HSO-3: deamination of C on U  transition
NH2OH
H2N-O-CH3
Alkyl agent: alkylsulfates, N-alkyl-N-nitrosamines (nitrates). Alkyl C, T and G  block or
change base pairing, cause between- and interchain crossbonds  block of replication
and trancription
Psoralenes: intercalar agens, furocumarin, 8-metoxypsoralene
Pre-carcinogens: metabolic activation via specific enzymes (cyt. P450) is necessary
N-acetyl-2-aminofluoren (AAF), α-Nafthylamine, Benzo(a)pyren, Aflatoxins, Nitrates and
others
Examples from history
• 1761: John Hill – polyps in snuffers of tabacco
• 1775: Sir Percival Pott – scrotal carcinoma in chimney sweepers (first
documented work disease), long-term exposition to carcinogens (asbest,
benzen, nitrosamins….)
• 1795: Samuel von Soemmering – smoking of pipe as a carcinogen.
Sir Percival Pott
Samuel von Soemmering
Benzo(a)pyren activation
P450
P450
Tumorigenesis of aromatic hydrocarbons
„fjord“
Non-planar
Diolepoxides
React with DNA (A)
More carcinogenic
„bay“
Planar
Less reactive
Less carcinogenic
α-Nafthylamine activation
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Used in weld industry
Strong carcinogen having latence 15-20 years
In liver tranformed to carcinogen, than conjugated to glykoside
Hydrolysis in bladder: release of active carcinogen  bladder carcinomas
OR
OH
NH2
NH2
NH2
Bladder
NH-OH
NH-OR
Physical carcinogens
• Ionize radiation:
▫ dsDNA breaks.
▫ generate crossbonds (covalent bond between antiparalel nucleotids)
▫ base modifications (8-hydroxyguanin, 5-hydroxymetyluracil…).
• UV radiation: atom excitation  generate thymin dimers  block of
replication and transcription processes.
crossbonds
Breaks
crossbond
strand
strand
Biological carcinogens
• Viruses:
▫ Oncogene RNA viruses: retroviruses (classical oncogenes)
 HIV – probably supporting function only, Kaposi sarcoma…
 Human lymphotropic virus type I and II (HLTV-1, HLTV-2) – T-leukemia,
lymphomas
 HCV – hepatocarcinomas
▫ Oncogene DNA viruses:
 Papovaviruses (HPV) – anogenital tumors
 Herpesviruses - Epstein-Barr virus (EBV) – lymphomas (BL, HD),
nasopharingeal carcinomas (NPC); and others (HCMV; HSV-2; KSHV)
 Hepadnaviruses - hepatitis B virus (HBV) - hepatocarcinomas
 Adenoviruses (animals)
HPV
• Virus genome is circular dsDNA (8 kb)
• Protein E7
▫ Inhibition of Rb-proteinu
▫ Inactivation of p21Cip and p27Kip
▫ Abolishes inhibition effect of TGF- on growth of cells
▫ Causes development of multiple centrosomes
• Protein E6
▫ p53 degradation (using of ubiquitin ligase E6AP)
▫ interact with Bak (inhibition of apoptosis)
▫ activate hTERT expression (activation of telomerase)
• Genome is integrated in several places of host genome
• Integration is specific according to genome of the virus –
leads to disorder of protein E2 expression (regulate E6 and
E7 expression)
Effect of Papillomaviruses (Papovaviruses)
proteins E6 and E7 on cell transformation
Effect of Papillomaviruses (Papovaviruses)
proteins E6 and E7 on cell transformation
proliferation
Unlimited
replication
capacity
Loss of
polarity
Loss of cell
adhesion
invasion
Apoptosis, cell cycle
arrest
Biological carcinogens
• „Infectionous cancer“:
▫ Dogs CTVT (Stickers sarcoma)
▫ Non-viral parasitic cancer of Swan cells (DFTD) of Tasmanian devil
(Sarcophilus harrisii)
Histiocytes
Tumor
• Structure consists of cancer and connective cells that are under the controle
of cancer cells (stroma and blood cells).
• No physiological function in an organism.
• Its growth is not in conformity with surrounding tissue and organism
homeostasis
• Developed in places with high proliferating activity that are simultaneously
the most displayed to carcinogenes, i.e. mainly epithels (skin, lung,
digestive tract, but breast gland)
• The only one transformed cell is sufficient to develope tumor! (clonal
character)
Tumors classification I
According to its infiltration ability:
• Benign: solid bordered structure, located in one place, slow proliferation,
symtoms of local character.
• Malign: infiltrate surrounding tissues and using blood and lymphatic system
the whole body, in „infected“ tissues produce secondary tumors (metastases)
• primary x secondary tumors.
Tumors classification II
According to type of source cells:
• Carcinomas – tumors of epithelial cells (ca 89 % of human tumors)
• Sarcomas – solid tumors developed from supporting or connective cells
(tissue) – muscle, bone, cartilage (ca 2 % of human tumors)
• Leukemias and lymphomas – developed from hematopoietic cells and
immune cells (ca 8 % of human tumors)
• Gliomas – developed from nerve tissue (ca 1 % of human tumors)
Tumors classification III
According to affected organ (tissue):
• Breast carcinoma
• Colorectal carcinoma
• Cervical carcinoma
• Gland carcinoma
• Stomach cancer
• Ovarian carcinoma
• Leukemia
• And many others
Process of tumor development
Process of metastasis development
Primary tumor
Secondary tumor - metastasis
Cancer therapy
Classical approach:
Local therapy – surgical strike, local radiation ( radiation)
Systematical approach (combinated with surgical strike and radiation) –
Chemotherapy
Chemotherapy:
Cytotoxic agents: cyclophosphamide, cisplatinum, methotrexate, doxorubicin
(interaction with DNA)
Cytostatics: Vinca alcaloides (vinblastine, vincristine)
Application of cytokines:
Inhibitors of cell proliferation and inductors of apoptosis: Interferones, TNF
Support influence of cytokines: IL-2, GM-CSF
Biological therapy (targeted therapy, [Gene therapy])
‘Antisense’ oligonucleotides: target to specific oncogenes
Transfection: functional anti-oncogenes
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Biologicac therapy (targeted therapy)
Use defensive capacity of immune system and/or targeted drugs
(modificators of immune response) – cause specificaly only (or mainly)
on specific type of cells (e.g. cancer cells or immune cells):
• Blocks, restore or reduce precesses that are responsible for tumor progression
• Marks cancer cells to be well recognizable by immune system
• Improve ability of some immune cells (T-lymphocytes, macrophags) to destroy
cancer cells
• Changes growing ability of cancer cells
• Blocks or restore processes responsible for cell tranformation
• Improves ability of organism to repair or replace damaged cells injured by other
types of cancer therapy
• Blocks cancer cells spreading
Biological therapy (targeted therapy)
Preparation:
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Monoclonal antibodies
Differenciacal therapy
Inhibitors of proteasom, tyrosinkinases
Anti-angiogene therapy
Antisense oligonucleotides
High prices
Limited usage depending on these criterias:
▫ Tumor subtype
▫ Other types of cancer therapies are non-effective
▫ Undesirable effect of other types of cancer therapies
Monoclonal antibodies
Biological therapy (targeted therapy)
Preparation:
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Monoclonal antibodies
Differenciacal therapy
Inhibitors of proteasom, tyrosinkinases
Anti-angiogene therapy
Antisense oligonucleotides
High prices
Limited usage depending on these criterias:
▫ Tumor subtype
▫ Other types of cancer therapies are non-effective
▫ Undesirable effect of other types of cancer therapies
Differential therapy
Developmental line
Differentiated cell
Progenitor cell
Mutations
Differentiated cell
Cancer cell
Specific drug
Biological therapy (targeted therapy)
Preparation:
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Monoclonal antibodies
Differenciacal therapy
Inhibitors of proteasom, tyrosinkinases
Anti-angiogene therapy
Antisense oligonucleotides
High prices
Limited usage depending on these criterias:
▫ Tumor subtype
▫ Other types of cancer therapies are non-effective
▫ Undesirable effect of other types of cancer therapies
Inhibition of proteasome
Biological therapy (targeted therapy)
Preparation:
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Monoclonal antibodies
Differenciacal therapy
Inhibitors of proteasom, tyrosinkinases,
Anti-angiogenesis therapy
Antisense oligonucleotides
High prices
Limited usage depending on these criterias:
▫ Tumor subtype
▫ Other types of cancer therapies are non-effective
▫ Undesirable effect of other types of cancer therapies
Anti-angiogenesis therapy
Cancer cells release
angiogenesis factors (VEGF)
Vessel reaction
Tumor has nutrition support and can
grow and invade throught blood system
Using of angiogene drugs blocks
angiogenesis effect
Biological therapy (targeted therapy)
Preparation:
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Monoclonal antibodies
Differenciacal therapy
Inhibitors of proteasom, tyrosinkinases,
Anti-angiogene therapy
Antisense oligonucleotides
High prices
Limited usage depending on these criterias:
▫ Tumor subtype
▫ Other types of cancer therapies are non-effective
▫ Undesirable effect of other types of cancer therapies
Antisense oligonucleotides
Biological therapy (targeted therapy)
High prices
Limited usage depending on these criterias:
 Tumor subtype
 Other types of cancer therapies are non-effective
 Undesirable effect of other types of cancer therapies
Biological therapy (targeted therapy)
Suitable types of tumors for biological therapy:
• Kidney tumors
• Prostate tumors
• Intestine tumors
• Lung tumors
• Breast gland tumors
• Female genital tumors
• Melanoma
• Kaposi’s sarkoma
Thank you for your attention