29 Flashcards
cancer
uncontrolled proliferation of cells
what are 4 features of cancer?
Ignore inhibitory growth signals:
Normal cells stop dividing when they contact one another to indicate that there’s no room left & they form a monolayer
Cancer cells continue to divide, pile up & force the tissue out of place
Growth occurs independent of stimulatory growth signals
Normal cells require checkpoints, external signals to proceed through the cycle
Capable of continuous division
Normal cells senesce after ~50 divisions due to shorter telomere
Cancer Telomerase continues to restore telomere length, telomeres remain the same length & the cells don’t die off
Aneuploidy
Normal cells die off if c’some number deviates from the norm
Cancer cells are more tolerant of aneuploidy up to a certain point
carcinogen
chemical that causes cancer, a type of mutagen
A _____ is something that causes the DNA to be mutated, it is a ______ when it causes cancer
mutagen
carcinogen
how does increasing the rate of mitosis lead to cancer?
increases the opportunities for mutations
what are external factors that cause cancer?
Mutagens: mutate DNA
Radiation
Chemicals –> Carcinogens
Stimulates the rate of mitosis
Hormones (ex: breast tissue & prostate gland) Chronic tissue injury increases rate in stem cells needed to repair damage (ex: heregulin in lungs) Agents causing inflammation which generates oxidizing agents white blood cells are recruited to kill off foreign agents, but if their activities are excessive then their oxidative products (from the mitochondrion) will lead to too much harm Viruses stimulate mitosis of their host, ex: HPV & cervical cancer, hepatitis & liver cancer
how many mutations are required for cancer to develop?
6-8
what are 6 diff categories of genes mutated in cancer?
Oncogenes – mutated or over-expressed products stimulate mitosis even though normal growth signals are absent
Tumor suppressor genes – genes normally inhibit mitosis when a mutation is detected (ex: p53 – halts cell cycle until mutation is resolved or directs cell to death if it’s unable to be resolved, if there is a mutation then the cell will divide)
Genes that regulate apoptosis – genes indicate to the cell to undergo apoptosis when damage is unresolvable, mutation enables cells to ignore this signal
Genes that maintain telomeres, telomerase - normal cells die when their telomeres are too short after so many divisions, cancer cells regain the ability to express their telomerase & are immortal
Metastasis genes: enables cells of the tumor to separate from the primary tumor & migrate, includes 2 kinds:
Mutations in genes that enable the cells to adhere to one another, ex: cadherin genes holding epithelial cells together
Mutations in genes that enable cells to adhere to their substrate, ex: integrin genes required for attachment to the basal lamina
hyperplasia
faster growth than neighboring cells
dysplasia
irregular growth
describe the progression of cancer
comes from a single lineage of cells that undergo progressive mutations
Comes from a single cell During mitosis one cell receives a mutation, if this mutation is cancer-causing then this will lead to a lineage of cells with the same mutation & a tumor will develop Growth advantage Descendants will the suffer further mutations & further deregulates the cell cycle Eventually, more mutations occurred (6-8) & the cells are completely unregulated leading to cancer
explain the relation of cancer with age
increasing probability of cancer with an increase in age
cancer has less to with chemical exposure & more to do with increased longevity
how do you prevent viruses from causing cancer?
vaccines
what viruses cause cancer?
o 2 papilloma viruses
o Hepatitis B & C
o Epstein-Barr virus a type of herpes virus
o T-cell leukemia (HTLV-1 & HTLV-2)
how does radiation lead to cancer treatment?
damages cancer cells to the point where they cannot be repaired.
Normal cells seize to divide until the damage can be fixed, but cancer cells continue to divide & die off
