L20 Cancer Genetics Flashcards
cancer is a genetic disease at the somatic level and is characterized by gene products derived from…
mutated or abnormally expressed genes
cancer is due to genomic alterations in cells like…
1) single nucleotide substitutions
2) large-scale chromosome rearrangements
3) amplifications and deletions
only blank % of cancers are associated with germ-line mutations
5%
2 fundamental properties of cancer cells
1) proliferation
2) metastasis
cancer cell proliferation
abnormal cell growth and division
cancer cell metastasis
defects in normal restraints that keep cells from spreading and colonizing other parts of body
normal cells have functions tightly controlled by…
genes expressed properly
uncontrolled cell proliferation and metastatic spread makes cancer…
dangerous and malignant
benign tumors occur when cell loses…
genetic control over cell growth
benign tumor results in…
multicellular mass
benign tumors are removed by… and cause no…
surgery; serious harm
malignant tumors
cells break loose, enter bloodstream, invade other tissues, form secondary tissues (metastases), are life-threatening
all cancer cells in primary and secondary tumors are…
clonal
what does clonal mean?
tumors that have originated from common ancestral cell that accumulated numerous specific mutations
driver mutations give…
growth advantage (proliferation/metastasis) to tumor cells
tens of thousands of somatic mutations are present in…
cancer cells
fewer than a dozen mutated genes may be sufficient to…
create a cancer cell
passenger mutations have…
no direct contribution to cancer phenotype
Cancer Stem Cell Hypothesis states that tumor cells that do proliferate give rise to…
cancer stem cells that have capacity for self-renewal
stem cells are…
undifferentiated cells with the capacity for self-renewal
carcinogens are…
cancer-causing agents
delay between exposure to carcinogen and appearance of cancer is indicative of it being a…
multistep process
ex: leukemia from radiation exposure with incubation period of 5-8 yrs
tumorigenesis
development of malignant tumor
each step of tumorigenesis is a result of…
two or more genetic alterations
tumorigenesis releases cancer stem cell from…
normal cellular controls
each step of tumorigenesis confers selective advantage to…
growth and survival of cell
tumorigenesis is propagated through…
successive clonal expansion
what 3 things do cancer cells show higher rates of?
1) mutations
2) chromosomal abnormalities
3) genomic integrity - increases mutation rate for every gene in genome
mutator phenotype is when there’s a high level of…
genomic instability of cancer cells
it is highly improbably that mutator phenotypes can…
revert
genomic instability in cancer cells is characterized by…
- somatic point mutations (single-nucleotide swap)
- chromosomal effects
examples of chromosomal effects in genomic instability
translocations, aneuploidy, chromosome loss, DNA amplification, deletions
reciprocal chromosomal translocation
balanced exchange of genetical material between chromosomes
reciprocal chromosomal translocations are characteristic of many cancers such as…
leukemia and lymphoma
epigenetics is the study of…
chromosome-associated changes that affect gene expression but do not alter nucleotide sequence of DNA
epigenetic effects may be present in…
somatic or germ-line cells
examples of epigenetic modifications
- DNA methylation
- histone acetylation
- histone phosphorylation
cancer cells contain altered…
DNA methylation patterns, typically less in cancer cells than normal cells
promoters in genes are blankmethylated in cancer cells
hypermethylated
cancer cells having less DNA methylation and hypermethylated promoters results in…
repression of transcription
what happens to histones in cancer cells?
genes that encode histone-modifying enzymes are often mutated or aberrantly expressed in cancer cells
cancer cells have loss of…
cell proliferation control
