Final Flashcards
How does RNA tumor viruses generally exert their effects?
They turn on growth signalling pathways in the absence of stimuli.
(Add gasoline to the system)
How does DNA tumor generally act?
By sequestering proteins that control cell proliferation (Rb, p53), to shift the cells into S phase (DNA replication)
What are the DNA tumor viruses that induce tumors in natural host?
- Papilloma
- Herpes
- Hepatitis B
What are the DNA tumor viruses that induce tumors in experimental systems?
- Adenovirus
- Polyomaviruses
- SV40(controversial)
What are the cellular targets and gene product of SVP40?
Rb and p53, Large T antigen
What are the cellular targets and gene product of Papillomavirus?
Rb and p53, E5 E6 E7.
Does fusion of normal cell with tumor cell supresses growth properties of cells?
Yes.
How does p53 acts?
It triggers p21 so it binds do CDK2/cyclin E which makes the complex inactive.
How does pRb acts?
It binds to E2F, restraining it to synthesizes DNA enzymes.
True or false?
Retinoblastoma is genetic.
False, not always.
40% is genetic (1 parent carrier)
60% no genetic link
Can you develop retinoblastoma at 7 years?
No, once older than 5 retinoblastoma stops growing. However, you can develop osteosarcoma until 20 years old.
On what chromosome is Rb gene?
Chromosome 13
True or false?
Inactivation of Rb on two alleles in a nonhereditary way often leads to a tumor.
False. Only about 1/30 000 normal people develop tumor if their 2 alleles are mutated on Rb genes.
Hereditary retinoblastoma often leads to develop a tumor.
Name two consequences of RB1 inactivation.
- Defects in cell cycle exit
2. Mithochondrial defects.
Is Rb active a longtime during the cell cycle?
No
