Control of the Cell Cycle & Cancer

1. Control of the Cell Cycle & Cancer • Cells divide at different rates. • How is this division controlled?

2. Factors affecting cell division 1] Anchorage dependence

3. Factors affecting cell division • 2] Contact Inhibition - healthy cells stop dividing when they come in contact with other cells.

4. Factors affecting cell division 3] Growth factors

5. Factors affecting cell division 4] Checkpoints Red lights at locations of the cell cycle

6. Control of the Cell Cyclecheckpoints

7. Control of the Cell Cyclecheckpoints

8. Control of the Cell Cycle • G 1 (restriction) checkpoint- **important** • Cell “decides” to: • 1. Divide- enters S phase & DNA will replicate. • 2. Enter Go phase- Nerve, muscle and red blood cells remain in the Go phase. • 3. Die

9. Molecular control of the cell cycle at the G2 checkpoint

10. Cancer • Control system does not function properly. • Continuous cell division occurs. • Forms tumors- abnormal cell masses.

11. CancerTumors Types: • Benign • do not spread • less dangerous • surgical removal • Malignant • can metastasize- spreads via lymph & blood vessels & forms new tumors • displaces normal tissue

12. Reasons for continuous cell division • 1) Some cells run the red lights- go past checkpoints in the absence of growth factor. • 2) Others make their own growth factor. • 3) Disregard contact inhibition. • 4) Disregard anchorage dependence.

13. Cancer cells-do not exhibit anchorage dependence or contact inhibition.

14. Carcinogens-cancer causing agents • 1.Viral oncogenes • oncos = cancer, Greek • insert cancer causing genes into host DNA • RSV [Rous sarcoma virus] causes cancer in chickens p.207 • 2.UV light • 3.High fat diet • 4.Tobacco • 5.Hormones

15. The growth and metastasis of a malignant breast tumor

16. Breast cancer cell

17. Mammogram: normal (left) and cancerous (right)