HMB265H1 Lecture Notes - Lecture 21: Tumor Suppressor Gene, Ras Subfamily, X-Inactivation

• School: UTSG
• Department: Human Biology
• Course: HMB265H1
• Professor: Maria Papaconstantinou

Document Summary

More than 100 diseases in which cells grow out of control and can destroy healthy tissue. Caused by failures in the mechanisms that control growth, proliferation and apoptosis. Results from genetic damage (mutation) or altered gene expression. Changes found in cancer cells: uncontrolled growth, autocrine stimulation: cancer cells secrete signalling molecules that act on the same cell they were secreted from. They allow for increased growth and proliferation: contact inhibition: normal cells slow their proliferation rate as they begin to contact other cells. This is inhibited in cancer cells: cell death: cells do not undergo programmed cell death (apoptosis) and are not killed by irradiation. Irradiation normally causes cells to undergo apoptosis to prevent a mutated cell from continuing to replicate: gap junctions: cancer cells do not have gap junctions. This undermines cell- cell communication that normally serves to limit growth: genomic instability. Defects in replication and repair machinery results in unfaithful replication of dna.