Viruses And Cancer Flashcards
(43 cards)
What are the two ways in which we associate virus with cancer?
- Epidemiology, line up presence of cancer with presence of virus.
- If you introduce viral genes into the cell, do they induce oncogenesis
What are the 3 mechanisms of oncogenesis?
- Modulation of cell cycle control
- Modulation of apoptosis
- ROS-mediated damage
What is the way in each virus can directly cause cancer?
Via oncogenes
how can viruses indirectly cause cancer?
Via immunomodulation
What does pRB do?
Control of G1/G0 - S phase blockade
What does cyclin D1 do?
Regualtion of CDk4/6
Triggered by the PI3K/AKT pathway
What does beta-catenin do?
Accumulation during S-phase induces cell proliferation
Prevents apoptosis
When are S phase genes repressed?
When Rb and E2F are in complex
When are there induction of s phase genes ?
When Rb and E2F are apart
What is G1/S phase controlled by in the cell cycle?
Cyclin dependent kinases
How is apoptosis triggered extrinsically?
Usually between interactions between Fas ligand and Fas on the plasma membrane
How is apoptosis triggered internally?
Through release of MMPs and AIF protein. This induces apoptosis through DNA fragmentation
What type of molecule is Bcl2?
A molecule that is pro survival
What is the normal extrinsic pathway for apoptosis?
Caspases cause depolarisation of mitochondrial membranes
Lead to release of cytochrome c, activation of caspase 8, then leads to apoptosis
What does Bcl2 do to extrinsic apoptosis pathway?
Blocks this pathway, stops release of cytochrome c
What does EBV do with Bcl2?
Encodes its own protein
How does PI3K/AKT pathway affect cellular growth?
Is triggered or maintained, these are kinases that lead to promotion of cell growth
What does NS5A do to AKT/PI3K pathwya?
Blocks the regulator
What do v-FLIPs do?
Inhibit apoptosis signalling through death receptors
What do free radicals target?
DNA
Protein
RNA
Lipids
How do free radicals promote cancer?
- Mutating cancer related genes
- Activating signal transduction pathways
- Promoting angiogenesis
- Exerting selective pressure (p53 and NO.)
What are 4 key examples of virus-associated cancer?
Burkitt’s lymphoma
Nasopharyngeal carcinoma
Cervical cancer
Hepatocellular carcinoma
Where is Burkitt’s lymphoma and what populations is it affecting?
Young children, slightly biased to males
Where malaria is endemic
What role does malaria have on Burkitt’s lmyphoma?
We all harbour EBV, but malaria has a role in causing illness due to being immunosuppressed