MCM 2-20 Viral Oncogenesis Flashcards
characteric shape, genome and mechanism of oncogenic viruses?
no characteristic shape, genome, or mechanism
what is the characteristic target cell, patient, pathway of oncogenic virueses?
not any
T/F, animal models are not reliable predictors of human effects of oncogenic viruses
true.
6 features of human cancer cells
make tumors if transplanted to animals undifferentiated immortal not contact inhibited resistant to apotosis absormal chromosomes
all these features can be induced experimentally by viruses
growth of himan cells is controlled by genes. Three important ones?
what are they called?
myc - transcription factor
src - membrane signaling of growth factor binding
ras - signal transduction from surface receptors
called protooncogenes
cell cycle is controlled by tumor supressor genes. Two important ones?
p53 - activated by DNA damage, stops cell cycle until repair or causes apoptosis. Prevents accumulation of mutations.
Retinoblastoma - inhibits the cell cycle by inhibiting E2F which stimualtes the cell cycle
Both p53 and Rb can shut down or slow the cell cycle.
how can oncogenes become overexpressed in certain cancers?
by amplification, mutation, or translocations of the genes close to active promoters (burkitts)
____ is often mutated in cancer
____ is sometimes mutated
p53 is often mutated, Rb is sometimes mutated
What viruses target tumor suppressor genes?
tumor suppressor genes like P53 and Rb are targeted by DNA viruses
cell transformation can be caused by _________ viruses
RNA or DNA viruses
RNA oncogenic viruses carry activated oncogenes OR insert promoter to activate an oncogene. RNA oncogenic viruses have to do with activated or activating oncogenes
DNA viruses degrade or block the cell cycle genes (inactivate p53 or Rb)
Oncogenic viruses are species specific (T/F)
true
important protein in SV40 virus?
“large T- antigen” for causing tumors cancer. Large T inactivates and binds p53 and Rb
T-antigen must be continually expressed.
T-antigen allows cells to proliferate without control
SV40 does not cause tumors in humans, but it does in hamsters.
oncogenic adenoviruses are species-specific (T/F)
True.
important proteins/genes in adenovirus oncogenicity?
E1a and E1b are similar to T-antigen, same effects in ANIMAL cells. Always expressed in transformed cells.
no human tumors contain adenoviruses.
viruses that cause cancer in humans
papillomaviruses - warts - cervical cancer
EBV - mono - burkitts lymphoma and nasopheargeal cancer
HEP b - hepatitis B - hepatocellular carincoma (liver cancer)
Kaposi’s sarcoma - Karposi’s sarcoma
Human T-cell LEukima Virus - Leukemias, lymphomas