Cancer Bio II Flashcards
What are oncogenes?
genes that are “turned on” in cancer that have a stimulatory effect on cells
What are tumor suppressor genes?
genes that are “turned off” in cancer whose products normall negatively regulate cell proliferation, promote apoptosis or maintain in vivo homeostatic growth
What are genomic guardian genes?
Genes whose dysfunction may create genomic instability, e.g. DNA repair genes or recombination genes
What are proto-oncogenes?
Normal cellular genes that can be altered to a gene that converts a normal cell to a tumor cell
What are four mechanisms of conversion of proto-oncogenes?
Mutation within the gene
Translocation e.g. Philadelphia chromosme
Over-expression
Amplification
What is Ras?
Oncogene affecting signal transduction
Most cancer-causing mutations affect its ability to hydrolyze GTP
Three types: H-ras, K-ras, N-ras
What is responsible for transforming the activity of H-ras in bladder carcinoma?
Single nucleotide chain resulting in Gly->Val
What is Myc?
Onco gene involved in cell-cycle regulation, the control of proliferation and development
Activated by chromosomal translocation
Four types: MycC, MycL, MycN, and MycL2
What is ErbB-2?
Encodes for a receptor Protein-tyrosine kinase
Oncogene that is activated via gene amplification
Prognostic of highly malignant tumor
What is loss of heterozygosity?
Refers to the loss of an allele in tumor DNA compared to matched normal DNA from the same individual
Causes loss of function for a tumor suppressor gene during tumor initiation or progression
What is retinoblastoma?
Tumor with distinct genetic inheritance
Caused by both alleles of the Rb protein being lost (Two hit hypothesis)
Why is noninherited retinoblastoma rare?
its development requires two independent somatic mutations to inactivate both normal copies of the Rb gene in the same cell
What is p53?
Nuclear protein that increases when there is DNA damage
Increases expression of DNA repair enzymes and can cause apoptosis
Mutated in a wide variety of human tumors
How do tumors progress?
Angiogenesis - need a blood supply
Invade surrounding tumors - malignancy
Resist immune attack
Extravasate and develop tumors in distant organs
What are positive effectors of Angiogenesis?
VEGF
Angiogenin
FGFs
