Ch. 8 - Cancer

• disease of the cell cycle where cancer cells don’t heed the normal signals that regulate the cycle • divide excessively and may invade other tissues of the body

• function to trigger and coordinate events of the cycle • there are critical points (checkpoints), where stop and go signals regulate the cycle • the default at these checkpoints is to stop unless a “go-ahead” signal (via protein) is given

Occur at G1, G2, and metaphase

• all key processes up to that point have been completed - if they receive a message from outside of the cell that indicated that they should (such as a growth factor)

-when a cell doesn’t continue to divide but stops at G1 indefinitely, unless damage occurs or they receive a signal from a growth factor to continue to divide

• binds to a receptor protein at the surface of the cell - which starts a signal transduction pathway to the next protein until it reaches the cell control system

• abnormally growing cells remain at the site but don’t spread to other parts of the body • can still cause problems, especially if they occur in the brain

An abnormally growing mass of body cells

• Those that can spread from their original site and can also secrete signal molecules that cause blood vessels to grow towards them • hijacks your system of O2 and nutrients to fuel their own growth • if you have this you have cancer

Spread of cancer cells beyond their original site

• carcinomas: originate in the external covering of the body (skin) or internal lining of the body (lining of intestine) • sarcomas: arise in tissues that support the body such as bone, muscle, cartilage, etc • leukaemia and lymphomas: are cancers of the blood-forming tissues such as bone marrow, spleen and lymph nodes

Single gene that causes a normal cell to become cancerous

• Normal gene that has the potential to become an oncogene - code for proteins that stimulate cell division or those that suppress cell growth

From a virus (HPV, Hep B, H. Pylori) or from mutation of one of its own genes

• require 4+ mutations and take a long time to develop - multiple changes must occur at the DNA level for a cell to become fully cancerous

• benign: non-cancerous, stay in one place, don’t spread, don’t usually come back once removed • precancerous: may develop into cancer if not treated or not normal • cancerous: cells have grown into nearby tissue and may produce cells that can break away and travel through the blood or lymphatic system

Normal looking cells that grow faster than normal. Some may be precancerous, most aren’t