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Cell Cycle and Cancer

Cell Cycle and Cancer. Daniel Hochhauser. MILESTONES IN CELL DIVISION: TO CYCLE OR NOT TO CYCLE: A CRITICAL DECISION IN CANCER Malumbres and Barbacid Nature Reviews Cancer 1, 222-231 (2001). HALLMARKS OF CANCER Hanahan and Weinberg Cell 100,1 57-70 (2000).

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Cell Cycle and Cancer

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  1. Cell Cycle and Cancer Daniel Hochhauser

  2. MILESTONES IN CELL DIVISION: TO CYCLE OR NOT TO CYCLE: A CRITICAL DECISION IN CANCER Malumbres and Barbacid Nature Reviews Cancer 1, 222-231 (2001) HALLMARKS OF CANCER Hanahan and Weinberg Cell 100,1 57-70 (2000)

  3. Cell Cycle = round of chromosomal replication in S phase followed by segregation of the replicated chromosomes into two daughter nuclei during M phase

  4. G2 / M phase transition is performed by a protein kinase conserved throughout eukaryotes MPF - protein kinase catalytic subunit p34 cdc2 - B-type cyclin

  5. G2 / M phase transition is performed by a protein kinase conserved throughout eukaryotes MPF - protein kinase catalytic subunit p34 cdc2 - B-type cyclin i.e a kinase and a cyclin

  6. RESTRICTION POINT Cells no longer require presence of serum to commit themselves to initiating DNA replication

  7. RESTRICTION POINT Cells no longer require presence of serum to commit themselves to initiating DNA replication THE RESTRICTION POINT IS ABROGATED IN CANCER

  8. Uncontrolled cell proliferation requires multi-step gene damage eg gain of function of oncogenes (accelerator) and loss of function of tumour suppressors (brakes) Oncogene Tumour suppressor CYCLINS CDKI

  9. ONCOGENES when activated override brakes to cell cycle progression Cyclins and cyclin-dependent kinase ( cyclin D1, CDK4)

  10. Tumour suppressor genes when disabled allow accelerated cell cycle progression Cyclin-dependent kinase inhibitors (p16, pRB)

  11. CELL CYCLE

  12. E2F pRB G1 NORMAL CELL CYCLE

  13. P E2F pRB pRB G1/S E2F NORMAL CELL CYCLE TS

  14. P E2F pRB pRB E2F NORMAL CELL CYCLE G2/M TS E2F1,DHFR….

  15. Viral Targeting of pRb T Ag HPVE7pRB E1A

  16. INACTIVATION OF pRB in TUMORS • Retinoblastoma (two- hit) • small-cell lung cancer • soft tissue sarcoma • glioblastoma • breast cancer • bladder carcinoma

  17. Inactivation of pRB by deletion, mutation, phosphorylation results in increased ‘free’ E2F Proliferation E2FApoptosis

  18. POSITIVE REGULATORS OF G1 PHASE PROGRESSION

  19. CDK-CYCLIN COMPLEXES • Intrinsically inactive catalytic subunit (CDK) • Positive regulatory subunit (cyclin) • Phosphorylation of conserved threonine residue

  20. CYCLIN D • 3 Cyclin D genes • synthesised by mid-G1 phase and maximum at G1/S boundary • stimulated by growth factors • promote catalytic activity of CDK4 and CDK6 • Major substrate is retinoblastoma protein • Cells lacking pRb do not require cyclin D1 activation

  21. CYCLIN E • synthesis at late G1 phase • complexes with CDK2

  22. NEGATIVE REGULATORS OF G1 PHASE PROGRESSION

  23. CYCLIN-DEPENDENT KINASE INHIBITORS p21cip1 CIP/KIP p27kip1 p57kip2 p16INK4a p15INK4b INK4 p18INK4c p19INK4d

  24. INK4 CDKI • specifically target CDK’s • INK4 proteins sequester cdk4/6 into complexes liberating cip/kip proteins • ability to arrest in G1 dependent on intact pRb • p16 and p19 alternative transcripts • p16 • familial malignant melanoma • ectopic expression results in G1 arrest

  25. cell cycle arrest

  26. Cip/Kip CDKI • p21= waf1=Sdi1 inhibits cyclin/CDK function through cell cycle

  27. Cip/Kip CDKI • p21= waf1=Sdi1 inhibits cyclin/CDK function through cell cycle • universally inhibits cdks

  28. Cip/Kip CDKI • p21= waf1=Sdi1 inhibits cyclin/CDK function through cell cycle • universally inhibits cdks • activated by p53 -critical in induction of cell cycle arrest

  29. CELL CYCLE GENE ALTERATIONS IN CANCER • pRb deletion / mutation • p16 deletion / mutation

  30. CELL CYCLE GENE ALTERATIONS IN CANCER • pRb deletion / mutation • p16 deletion / mutation • p27 inactivation (methylation)

  31. CELL CYCLE GENE ALTERATIONS IN CANCER • pRb deletion / mutation • p16 deletion / mutation • p27 inactivation (methylation) • cyclin D1 overexpression • cyclin E overexpression • CDK4 overexpression

  32. Keyomarsi et al N Engl J Med. 2002

  33. p53 MDM2 CELL CYCLE PROGRESSION

  34. SERINE-15 P ATM p53 MDM2 CELL CYCLE ARREST

  35. Increasing endogenous CDK inhibition Proteasome inhibitor PS-341 20S proteasome Histone deacetylase inhibitors Altering cyclin levels Flavopiridol Cyclin D Rapamycin (CCI-779) Cyclins D and A

  36. Direct inhibitors of cyclin-dependent kinases Flavopiridol CDK1, 2, 4 UCN-01/staurosporine CDK1, 2, 4, PKC, chk1

  37. Cyclin D1overexpression, pRB deletion Hanahan and Weinberg

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