Oncogenic Viruses - Ryan Flashcards
What is Rous sarcoma virus?
first solid tumor linked to viral infeciton
What is avian leukemia virus?
first demonstration of a cancer caused by virus.
How do viruses cause cancer?
- activate signaling pathways to stimulate growth
- release cell cycle control to allow uncontrolled growth
- infected cell destruction leads to unplanned regeneration.
What are the criteria that must be met to identify a virus as cancer causing?
- coincident geographic distribution of infection and cancer.
- higher incidence of viral markers in cases vs control
- viral markers precede the cancer
- reduction in infections rates reduces cancer
- viruses should transform cells in vitro
- virus genomes present in tumor but not normal cells
- tumor induction in experimental animals
What are transformed cells?
immortalized but lose many growth properties. Loss of contact inhibition, reduced need for growth factors, appear round as opposed to normal shape, may cause tumors when introduced to animals.
What is RSV?
viruses known to be transducing retroviruses.
Cause tumors rapidly and 100% of the time. Contain v-oncogenes in their genomes.
What are nontransducing retroviruses?
high rate of tumor formation.
intermediate time to tumor (weeks to months).
Virus that places itself in a location that happens to promote oncogenes. Doesn’t carry the oncogene itself.
What are nontransducing, long latency retroviruses?
low rate of tumor formation.
Years to tumor formation.
HTLV-1
What type of signaling does HTLV-1 use?
infects and transforms CD4 T cells. Cuases adult T cell luekemia and lymphoma (ATL).
uses TAX, which activates Ikk complex to free NF-kB.
What type of signaling does EBV use?
herpesvirus.
Actute infection can cause mononucleuosis.
Is latent in B cells and epithelial cells.
Causes Burkitts lymphoma, hodgkin’s posttranslational lymphoma, nasopharyngeal carcinoma.
Uses LMP-1 (latency membrane protein) that oligomerizes in the absence of ligand and leads to immortalization.
Can cause Burkitt lymphoma by longevity.
What signaling does KSHV do?
herpesvirus that is latent in B cells and monocytes, T cells and endothelium.
Kaposi’s sarcoma, pleural effusion lymphoma, Castleman’s disease.
encodes numerous genes linked to transformation.
vGPCR (G protein coupled receptor) that stimulates cell growth.)
Encodes vCyclin that binds and activates CdK6, which leads to constitutive activation of cell cycle.
What is SV40?
Simian virus 40. Was in earliest polio vaccine.
Polyoma virus (Papova).
sT antigen binds and inhibits protein phosphatase 2A, which sustains signaling cascade
What is HPV?
low risk genotypes cause benign warts.
In high risk genotypes can cause cervical and head and neck cancers. There is an anticancer vaccine against it.
Disrupts E2 regulation by binding Rb.
What are HepB and C?
Cause unplanned regeneration. result of decade-old chronic infections. Hepatic cancers
