chapter 12

• hyperplasia


  cells divide more rapidly than normal
• dysplasia


  cells change form, look abnormal under microscope
• in situ cancer


  cells look malignant but haven't moved from original tumor site
• invasion


  cells move into tissue surrounding tumor
• metastasis


  cells spread to distant organs
• clinical staging


  stage 4 is most malignant (metastatic)
• proto-oncogence


  normal form of a gene that stimulates cell division when activated by appropriate signals
• oncogene


  mutated form of a proto-oncogene that activates cell division constantly
• tumor suppressor


  gene that normally blocks inappropriate cell division. Mutated form fails to do so
• pathway activated by growth factors leading to cell cycle entry


  Growth factor activates receptor

  Active GF receptor activates Ras

  Active Ras activates MAP kinase

  MAP kinase enters nucleus and stimulates transcription of genes including Myc

  Myc activates transcription of E2F

  E2f causes cell to enter cell cycle.

  BUT - E2F is blocked by tumor suppressor RB if cell growth is not appropriate. If RB is mutated it fails to block E2F activity.
• ras


  mutated in about 30% of human cancers
• p53


  most commonly mutated gene in human cancers
• RB


  tumor suppressor that causes inherited cancer in retina of the eye
• BRCA1 and 2


  tumor suppressor, involved in DNA repair. Mutant causes inherited predisposition to breast cancer
• risk factors


  age, smoking, uv radiation, red meat
• viral cancer


  some strains of HPV causes cervical cancer