Deregulation of signal transduction and cell cycle in Cancer

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1 Deregulation of signal transduction and cell cycle in Cancer Tuangporn Suthiphongchai, Ph.D. Department of Biochemistry Faculty of Science, Mahidol University Room Pr324

2 Outlines What is Cancer? Development of Cancer Cause of cancer Oncogenes & their discovery (RNA Tumor viruses) Tumor suppressor genes Tumor viruses Properties of cancer (Hallmark of Cancer) Molecular approaches for cancer treatment

3 Gene alteration Uncontrolled proliferation Benign tumor Malignant tumor invasion

4 Types of Cancer Most cancers are in three main groups: Carcinomas malignancies of epithelial cells (about 90% of human cancers). Sarcomas solid tumors of connective tissue such as muscle, bone, cartilage, and fibrous tissue (rare in humans). Leukemias and lymphomas arise from the bloodforming cells and immune system cells, respectively. Tumors are further classified according to tissue of origin.

5 Development of Cancer Tumor clonality Tumors develop from single cells that begin to proliferate abnormally. The single-cell origin has been demonstrated by analysis of X chromosome inactivation patterns.

6 Multistep Process of tumor development Mutation and natural selection for cells with selective advantage (:proliferation, survival) Most cancers develop late in life as a consequence of multiple abnormalities, which accumulate over many years. proliferation Tumor initiation: mutation leads to abnormal proliferation of a single cell, which grows into a population of clonal tumor cells. Tumor progression: additional mutations occur within cells of the tumor population.

7 Colon Carcinoma Development benign neoplasm Clonal selection: proliferative adv Figure 19.5 Development of colon carcinomas (Part 1)

8 Regulatory gene Cause of Cancer Carcinogens: - substances that cause cancer - induce DNA mutation - stimulate proliferation (Tumor promoter) Carcinogen:- Chemical - Radiation: UV - Infection: Virus, Bacteria, parasite Alter regulatory gene Stimulate growth Inhibit growth Stimulate growth Inhibit growth Controlled growth Uncontrolled growth Cancer cell:- lack normal control of cell growth

9 Carcinogens damage DNA, induce mutation: - UV radiation: double strand break - Chemical carcinogens: Mold-contaminated penuts/grains Smoke is responsible for about 1/3 of cancer deaths. Tobacco Form DNA adduct Figure 19.6 Structure of representative chemical carcinogens

10 Carcinogens cont. act as Tumor promoters: enhance cell proliferation: - Hormone: estrogen - Asbestos - Helicobacter pylori - Some tumor viruses

11 Regulatory gene Stimulate growth Inhibit growth Cause of Cancer Carcinogens: - substances that cause cancer - induce DNA mutation - stimulate proliferation (Tumor promoter) Carcinogen:- Chemical - Radiation - Infection: Virus, Bact, parasite Oncogenes Alter regulatory gene Stimulate growth Tumor Suppressor Inhibit growth Controlled growth Uncontrolled growth Cancer cell:- lack normal control of cell growth

12 Oncogenes specific genes that can induce cell transformation. Discovery of oncogenes - Rous sarcoma virus (RSV) induces sarcomas in chicken and transforms chicken embryo fibroblasts in culture. - Avian leukosis virus (ALV) (related virus) infect cell without transformation.

13 RSV vs ALV genomes They identified src as an oncogene. Vertebrate cells also contain src-related gene called Proto-oncogene.

14 > 40 oncogenic retroviruses have been isolated. All contain at least oncogene.

15 Vertebrate cells also contain src-related gene called Proto-oncogene. Proto-oncogenes: normal-cell genes from which retroviral oncogenes originate. Functions: control normal growth & development - Signal transduction (e.g., growth factors, their receptors, src, ras, raf ). - Cell cycle regulation: cyclin D - Apoptotic inhibition: Bcl-2 - Differentiation: RAR-, Erb-A Oncogenes are abnormally expressed or mutated forms of the proto-oncogenes to make them more active. In retrovirus, oncogenes express at very high level.

16 Proto-oncogenes often encode proteins in the signaling pathways. GF: c-sis (PDGF B chain) KS/HST (FGF related) wnt1 G prot: G, Ras Kinase S/T K: raf, MAPK, Akt Y K: src, abl Lipid K: PI3K Sustain cell proliferation GFR: EGFR family Tel (PDGFR) c-met (HGFR) c-fms (CSF-1 R) Other: crk (SH2/SH3 regulator) Transcription factor: c-fos, c-jun, c-myc, NFkB, RAR, Lodish Ch23 Cancer

17 Tumor Viruses How do DNA tumor viruses such as Papillomavirus, Adenovirus cause cancer?

18 Protooncogene Oncogene 1) Acquisition by virus - Under control of strong promoter (viral promoter) - deletion during acquisition by virus 2) Point mutations/deletion/ Insertion): Ras V12. Ras mutation present in ~30% of all tumors

19 3. Translocation: abl (Tyrosine kinase) from Ch9 to Ch22 in chronic myeloid leukemia fusion protein bcr-abl T5 4. Gene amplification: high expression level

20 Figure Oncogenes and cell survival Genes encoding PI 3- kinase and Akt act as oncogenes. They prevent apoptosis of many cells. Bcl-2 oncogene increases expression of Bcl-2, which blocks apoptosis.

21 Proto-oncogene and Tumor suppressor gene

22 Tumor Suppressor Tumor suppressor genes normal function in inhibiting cell proliferation and tumor development. Loss or mutate both copies of gene

23 Retinoblastoma (Rb) Retinoblastoma = rare childhood eye tumor Occur in a certain families inherit Evidence shows Retinoblastoma results from loss of Rb gene Deletion of chromosome 13q14 Rb consistently loss or mutate in retinoblastoma Introduce normal Rb reverses tumorigenicity Rb gene involve in other cancer: breast, lung cancer

24 Rb protein blocks cell cycle progression at the restriction point (G1-S transition). Lodish

25 Rb function in regulation of restriction point Retinoblastoma protein (Rb) inhibits E2F transcriptional activity. Cdk4,6/cyclin D phosphorylates & inactivates Rb, dissociating it from E2F, so E2F can activate S-phase gene transcription INK4 P15, p16 : GF p21, p27 DHFR, TS Ballatori SE & Hinds PW Signal Transduction and Targeted Therapy (2016)

26 P53: Inactivate in a wide variety of cancer (~50%) Li Fraumineni syndrome - p53 mutation - high risk of cancer - Often develop cancer in childhood p21 (PUMA, Noxa) (Gadd45) (p21)

27 Hallmarks of Cancer 1 2 Common Properties of Cancer cells PD Hanahan & Weinberg Cell

28 1. Sustaining proliferative signal - Normal cells require growth factors. - Cancer cells can grow in the absence of growth factors. - produce growth factors that stimulate their own proliferation. - Abnormal intracellular signaling: Ras, protein kinases

29 2. Evading from growth suppressor: Antigrowth signal (:TGF-beta, cell-cell contact,..) usually act at restriction point. This point is often deregulated in cancers: down-regulation of Rb or cdk inhibitor, upregulation of G1 cyclin/cdk.

30 3. Resisting cell death Cancer escapes from apoptosis by: Upregulation of anti-apoptotic Bcl Family members (Bcl-2/Bcl-xL) Downregulation of pro-apoptotic Bcl Family members (Bax, Bad) Escape from p53 mediated cell death: delete or mutate p53 Mutation or downregulation of the Death ligand receptors Upregulation can be through the Akt pathway which turns on NFkB (to regulate FLIP/IAPs, etc) IAP (inhibitor of apoptosis) inhibits caspase 3 & 9

31 4. Replicative immortality - up-regulation of telomerase - Telomere = Chromosome end - Telomeres shorten each round of cell division - When it reaches a critical length cell stop proliferation and become senescent Hall Sci Based Med 2014

32 5. Invasion & Metastasis Morphology & Motility:- cytoskeleton ECM degradation:- protease Reduced adhesion molecules 6. Angiogenesis promote formation of new blood vessels. Cancer cells secrete angiogenic factors : VEGF to promote angiogenesis. supply O 2 & nutrient. facilitate metastasis Krzeszinski & Wan Trends in Pharmacol Sci 2015

33 Signaling Interactions in the Tumor Microenvironment Hanahan & Weinberg Cell 2011

34 Molecular approaches for cancer treatment Most Conventional chemotherapeutic drugs damage DNA or inhibit DNA replication. They are toxic to normal cells as well. New Approaches Anti-angiogenesis: block endothelial cell proliferation -> interfere vessel formation, less toxic to normal cells. Immunotherapy: Chimeric antigen receptor (CAR) T cell, PD-1 inhibitor Targeted Therapy Drugs that target specific proteins: Monoclonal antibody against variety of growth factors or their receptors. Eg. Herceptin mab to ErbB 2, Erbitux mab against EGFR

35 Hanahan & Weinberg Cell 2011 PD-1 inhibitor

36 Eg. B-Raf most commonly mutated in melanoma. Drug target B- Raf is used in melanoma.

37 References 1. Cooper GM. The Cell: A molecular approach 7th ed ASM Press, Chapter Lodish H et al. Molecular Cell Biology, 8 th ed., 2016, chapter Hanahan D& Weinberg R. Hallmarks of Cancer: the Next Generation. Cell 2011;144:646

38 Intracellular Signaling Networks Regulate the Operations of the Cancer Cell Hanahan & Weinberg Cell 2011

39 Assignment for the second class Students will be divided into 4 groups. You will work in a group to answer the following questions (1 question/ group) and explain it to your friends during the next class. 1. Explain briefly DNA repair mechanisms. Give at least one example of defect in DNA repair mechanism that link to cancer. 2. How do DNA tumor viruses such as Papillomavirus, Adenovirus cause cancer? 3. What is Warburg Effect? How is it involved in metabolic energetic alteration in cancer? Explain at the molecular level how this alteration occur. 4. How do cancer cells escape from immune response? Explain the function of PD-1, PDL-1 in this process and how it can be used as target for immunotherapy of cancers.

40 Hallmarks of Cancer 1 2 Common Properties of Cancer cells PD Hanahan & Weinberg Cell