BSI Lecture 27-28 Mechanisms of Cancer Flashcards
____ cells reproduce in defiance of normal restraints and invade other tissues or territories normally reserved for other cells
Cancer
T or F? Majority of cancers initiated by genetic aberration
True
Several ________ are required to cause cancer.
Mutations
These arise from epithelial cells
Carcinomas
These arise from connective and muscle cells
Sarcomas
These arise from hemopoietic cells
Leukemias
tumors that are self-limiting in their growth and not invasive are ________
Benign
tending to infiltrate, metastasize and terminate fatally are ________
Malignant
To change from benign to malignant is ______
Transformation
A mutated proto-oncogene usually involved with controlling cell proliferation is a(n) ______
Oncogene
Oncogene will contribute to ______. These refer to normal or mutated genes that stimulate the cell cycle.
Tumorigenesis
What is the opposite of oncogene?
Tumor supressor gene
Normal gene that can be converted into a cancer- promoting oncogene by mutation is a _______-_______-
Proto-oncogene
____-_________ gene refers to the wild type form of the gene.
Proto-oncogene
Conversion of proto-oncogene to oncogene is called _________
Activation
Gene that normally functions to suppress tumorigenesis
Tumor supressor gene
T or F? For tumor suppressor gene, loss of function mutation enhances susceptibility to cancer
True
T or F? Tumor suppressor genes need loss of function of one allele
False, both alleles
T or F? Most cancers arise from a single normal cell.
False, abnormal
Evolution of a tumor cell: _________ or _______ _______ gives replicative advantage over other cells
Abnormality; genetic defect
T or F? Tumor cells follows rules of mutation and natural selection that govern evolution.
True
Evolution of a Tumor cells: as advantaged cell divides, another mutation may occur giving even more advantage for ______ and ________
survival; proliferation
Offspring of a well-adapted cell will divide the fastest eventually taking over the tumor becoming the _______ ______ in developing tumor
dominant clone
What is a dominant clone?
It is the dominant version of the tumor cells
Tumor evolution takes many years to develop a progeny of cells that have the number and appropriate mutations that make it a ______ cancer
malignant
T or F? Invade refers to invading underlining tissues
True
____ means the cancer has spread to another location in the body.
Metastasize
T or F? Cancer cells only require one mutation to invade and spread.
False
T or F? Oncogene only require mutation in one of the allele.
True
DNA acquires mutations at a fast rate than normal is ______ _______
Genetic instability
Oncogene require a ______ of function mutation.
gain
Defective DNA repair systems or inability to maintain integrity of chromosomes is an example of _____ ______
Genetic instability
Mutation in some gene responsible for genomic stability is an example of ______ ______
Genetic instability
T or F? Genetic instability allows for slower accumulation of mutation.
False, more rapid
How can cancer sustain proliferative (stimulating cell to divide when its not suppose to)?
1) increase the number of growth factor receptors
2) Mutant receptors that transmit signals without growth factors
3) Mutation in signaling proteins that are normally activated by GF
Cancer can evade growth suppressors by causing what to happen?
- Mutations in tumor suppressor genes (egp53, Rb)
2. Cell cycle not halted when supposed to be halted.
How can cancer evade apoptosis.
- Increased expression of anti-apoptotic proteins, such as Bcl-2, XIAP, cFLIP.
- Decreased expression of pro-apoptotic proteins (such as p53, Fas)
Once the telemores shorten to a certain point (usually after 50-70 cell divisions), the cell stops dividing and is considered “________”
Senescent
Which cells expresses telomerase?
Stem cells and immune cells
How do cancer cells acquire limitless replicative potential?
Cancer cells reactivate telomerase (90% of all tumors have reactivated telomerase)
therefore, cancer cells can divide an unlimited number of times (replicative immortality. The 10% that do not reactivate telomerase find an alternative pathway to maintain telomere length)
What is the most potent stimulus of angiogenesis?
VEGF
Cancer cells secrete high levels of angiogenic molecules inducing ________ of the tumor
Hypervascularization
T or F? Gain of function mutations in key genes which are central in cell motility can cause tissue invasion and metastasis?
True
T or F? Disruption in adhesive mechanisms that keep cells tethered together can lead to cancer invading the tissue and metastasis.
True
A mutation that causes an increase in the activity or amount of a protein is a ______ of function mutation.
Gain
A mutation that causes an decrease in the activity or amount of a specific protein is a ______ of function mutation.
Loss
Change of one base pair is a _____ ____
Point mutation
Removal of one or more base pairs is ______
Deletions
Addition of one or more base pairs is _____
Insertions
Part of gene recombines with other genes is _______
Translocations
Extra copies of particular genes is ______
Amplifications
Failure of sister chromatids to separate or one daughter cell will lose a chromosome; the other will gain a chromosome.
Nondisjunction
Mutations in MDM2 and ATM will cause indirect activation of ______
p53
50% of mutation involves various mutations in ____
p53
