Molecular Basis of Cancer Flashcards
In HPV, what does E6 protein inhibit? E7?
E6 inhibits p53; E7 inhibits p53, p21 and pRB
Define Epigenetic changes
Any process that alters gene activity without changing the DNA sequence; DNA methylation
Where does DNA methylation usually occur?
Usually where cytosine bases occur consecutively.
Discuss hypomethylation in cancer cells
Causes chromosomal instability, Reactivation of transposable elements and a loss of imprinting.
Discuss hypermethylation in cancer cells.
Can cause inactivation of tumor suppression genes
Explain the tumorigenesis model
Tumors are clonal expansions of a single progenitor. Malignant tumors are often heterogenenous
Discuss the canonical model of heterogenous cancers
Every cancerous cell has the capacity to regenerate a tumor.
Discuss the Cancer stem model of heterogeneous cancers
A very small subset of cells within the tumor population actually has the capacity to initiate and sustain tumor growth
Describe a problem with the canonical cancer model.
Cells derived from tumors are frequently heterogenous
What are the two qualities cancer stem cell must possess?
- Self-renewal
- Differentiation
They are more likely to accumulate the initial mutations that short lived differentiated progeny.
Discuss oncogenes
Mutant alleles are considered dominant. .
Discuss tumor suppressors and Haploinsufficiency
Two hit hypothesis; The level of tumor suppressor produced by the cell is half the normal level.
Match the Cyclins with their cdks
Cyclin D, cdk 4, G1
Cyclin E, cdk 2, S
Cyclin A, cdk 2, G2
Cyclin B, cdk 1, M
What happens to the levels of telomerase once the body is fully formed?
Repressed in many somatic cells.
Describe telomerase levels in cancer cells.
Its activated and keeps rebuilding telomeres, extending the lifetime of the cell.
