4 Viruses and Cancer Flashcards
what does HBV and HCV cause
hepatocellular carcinoma
what does EBV cause
nasopharyngeal carcinoma
Burkitt’s lymphoma
Hodgkins disease
what does HPV cause
cervical carcinoma
what does HHV-8 cause
Kaposi’s sarcoma
what does HTLV-1 cause
adult T cell leukaemia/lymphoma
what does MCV cause
Merkel cell cancers
Criteria viruses and cancer
- epidemiology
- virus in tumour tissue
- mechanisms of oncogenesis
Mechanisms of Oncogenesis
- modulation of cell cycle control
- modulation of apoptosis
- ROS mediated damage
- additional events
cell cycle S
synthesis
cell cycle G2
Gap 2
cell cycle M
mitosis
cell cycle G1
Gap 1
cell cycle G0
resting
what happens in S phase
viral transcription
what is formed after S phase
DNA replication proteins (viral DNA replication)
Cyclin D pathway - G0
no cell cycle as E2F bound by protein complex (mainly made of Rb)
viral cell cycle
E2F switches cell on - cell cycle genes and leads to proliferation
Cyclin D – cyclin dependent kinases, needs phosphorylation of Rb, releases E2F represses
Cyclin E activated
E2F can drive cellular expression
Modulation of Apoptosis
Normal cells
Cell proliferating – cell is transformed
Permitted by transformation become benign tumour
Local invasion and proliferation
Early metastasis (spreading)
Metastatic cancer and resistance to therapy
what leads to appoptosis e.g.
loss of pro-apoptotic signals
checkpoint defect
oncogene activation
mutation of DNA damage sensing system
what are used to modulate apoptosis
- p53
- Bcl-2
- FLICE inhibitory proteins
what is P53
transcription factor - tumor suppressor activity
what happens to P53 if have cancer
No human cancer that cell expresses functional P53
what activates BH3
stress signal
what happens when BH3 is activated
leads to apoptosis
