Exam 3: Chp 20 - Cancer Flashcards
(32 cards)
What 2 heritable processes define cancer cells
1) Reproduce in defiance of normal constraints
2) Invade and colonize places usually inhabited by other cells
Cancer cells do not respond appropriately to
social control extracellular signals
Tumors occur when
an an abnormal cell grows and proliferates out of control
Benign tumor
noninvasive tumor
Malignant tumor
can invade surrounding tissue and form secondary tumors called metastases
Balance of cell death and proliferation in cancer
either apoptosis downregulated or proliferation upregulated
Tumor microenvironment
consists of many kinds of cells
6 attributes of cancer cells
1) grow when they should not
2) divide when they should not
3) escape from their home tissue
4) survive and continue dividing even during conditions of stress
5) genetically and epigenetically unstable
6) escape replicative senescence by producing telomerase or stabilizing their telomeres
Cancer critical genes
genes whose alteration contributes to the causation or evolution of cancer
Two types of mutations in cancer critical genes
1) gain of function
2) loss of function
oncogene
a mutation that causes a gain of function = cancer
proto-oncogene
gene that can undergo a “gain of function” mutation to cause cancer
How many mutations are required to create an oncogene?
only one mutation on one allele
tumor suppressor gene
a mutation that causes loss of function = cancer
How many mutations are required to cause loss of function of a tumor suppressor gene?
a mutation of BOTH alleles
Three gain of function mutations
1) change in DNA sequence
2) gene amplification
3) chromosome rearrangement
two sources of change in DNA sequence causes gain of function
1) deletion or point mutation
2) regulatory mutation
6 major mutations/causes that cause loss of function
1) aneuploidy causes chromosome loss
2) miotic recombination event
3) gene conversion during miotic recombination
4) deletion
5) point mutation
6) epigenetic silencing
3 predominantly mutated pathways in cancer
1) Rb pathway
2) RTK/Ras/PI3K pathway
3) p53 pathway
Mutations in Myc cause
contribute to cancer by over activating G1-Cdk, phosphorylates E2F, allows E2F to be active
What does overactivation of the RTK/Ras/PI3K pathway cause?
Decreased apoptosis
Increased cell growth and division
What do mutations in p53 pathway do?
prevent blocking entry into cell cycle
prevent apoptosis
What does human papillomavirus cause?
uterine cervix cancer
Human papillomavirus under normal conditions
only impacts host cell when virus is programmed to produce infectious progeny in outer epithelial layers; manifests as a benign growth or wart
