2J- Cancer Genetics Flashcards
What do tumor supressor genes normally block?
uncontrolled cell proliferation by participating in the cell cycle regulation pathways.
What happens when the pRb molecule is phosphorylated?
It is inactive and allows the cell to proceed into the S phase.
What molecules encodes pRb?
RB1
What would happen if there is a loss-of-fxn mutation, deletion or hypermethylation in RB1?
pRb is not made there is uncontrolled cell division
What would happen if there are mutations in the CDK inhbitors?
uncontrolled cell growth
What are oncogenes?
They are genes that cause excessive cell proliferation
What genes typically make oncogenes?
proto-oncogenes (i.e. genes involved in regulation of normal cell growth)
What are some examples of proto-oncogenes?
GFs, GF receptors, signal transduction molecules and nuclear transcription factors
Are tumor supressor genes caused by gain or loss-of-fxn?
Loss of fxn
What types of mutations at the cell level causes problems in tumor supressor genes?
recessive
Are oncogenes caused by gain or loss-of-fxn?
gain of fxn
What types of mutations at the cell level causes problems in ocogenes?
Dominant
Some boob cancers are the result of defective repair of what type of DNA damage?
double stranded breaks
Some butt cancers are the result of defective repair of what type of DNA damage?
DNA mismatch repair
Xeroderm pigmentosum is the result of defective repair of what type of DNA damage?
nucleotide excision repair
What is the fxn of APC?
tumor suppressor gene, also participates in the phosphorylation and degradation of β-catenin
What disease is caused by dysfxnl APC?
Familial adenomatous polyposis (FAP)
What is the fxn of p53?
acts as a transcription factor that regulates genes that affect cell growth, prolif, and survival, induces apoptosis if DNA is damaged
What makes p53?
TP53. If it is mutated, p53 isnt made.
What disease is caused by dysfxnl p53?
Li-Fraumeni syndrome
What is the fxn of BRCA1?
participates in the DNA repair process, especially in double stranded breaks.
What disease is caused by dysfxnl BRCA1?
Familial breast and ovarian cancer
What is the fxn of NF1?
It’s product, neurofibromin, plays a role in signal transduction by down-regulation of RAS
What disease is caused by dysfxnl NF1?
Neurofibromatosis type 1
A cell can initiate a tumor ONLY when it contains how many damaged alleles?
2
What is the Multi hit concept of carcinogenesis?
more than one mutation is required for development of a tumor cell
What is Familial Adenomatous Polyposis (FAP) ?
There are a large # of polyps, so there is a high probability that at least one will produce a cancerous tumor by age 45
What causes Hereditary nonpolyposis colon cancer (HNCC)?
mutations occur in DNA mismatch repair genes
What enzyme is present in 85-90% of tumors that replases temomeric segments?
telomerase
What can gene mapping identify?
the region an inherited cancer gene is located but can’t identify the disease gene!
What is Genomic Instability?
mutations, chromosome breaks, aneuploidy; contributes to tumorigenesis b/c mutations and chromosome defects can activate oncogenes or deactivate tumor suppressor genes
