Lecture 3 - Cancers Flashcards
what is neoplasia?
new growth or proliferation of cells that serves no physiological purpose
how many times can a cell replicate approx?
50 times
telomeres shorten each time a cell divides until it can divide no more
tumour suppressant genes can also inhibit cell growth
what are the 3 ways a cell can misbehave in terms of cell replication?
- cancerous cells - divide without appropriate signals from hormones/growth factors
- mutations in tumour suppressant genes
- active telomerase allows for lengthening of telomeres
if these occur = unregulated cell proliferation
why do cancer cells proliferate?
do not respond to apoptosis signals and keep replicating instead of dying
how to cancerous cells maintain proliferation in terms of energy consumption?
undergo angiogenesis to make new blood vessels to get more blood and therefore more glucose to the area
what are some hallmarks of cancer cells?
genome instability and mutation
evade growth suppressors
sustain proliferative signalling
tumour promoting inflammation
telomers don’t shorten
get larger and move around body
avoid immune destruction
induce angiogenesis
resist apoptosis
what are the 5 stages of cancer cell evolution
normal cell – hyperplasia – dysplasia – cancer in situ – invasive
How is growth factor and cancer cells related?
cancer cells can make own growth factor to keep growing or can increase receptor numbers to use more growth factor
what are the main differences between benign and malignant tumours?
benign are encapsulation and don’t metastasize, are localised and usually slow growing
malignant are not encapsulation, grow rapidly and can metastasize
what are the two perspectives on development of cancer?
- genetic and molecular mechanism
- external and contextual factors
what are examples of acquired mutations?
tabacco
UV light
virus
age
what are examples of inherited or germline mutations?
Tumour suppressor genes
BRCA1 and 2
what are examples of oncogenes?
HER2 - controls cancer growth and spread
RAS genes - for cell communication pathways - cell growth and death
what is knudson’s two hit hypothesis?
- both alleles need to be damaged in order for cancer to occur
- i.e. if there if one allele has an inherited mutation, the other allele must be damaged for cancer to occur
- if both alleles have no inherited mutations, the BOTH need to be damaged in order for cancer to occur
what are tumour suppressant genes?
A type of gene that regulates cell growth. When a tumor suppressor gene is mutated, uncontrolled cell growth may occur.
ex BRCA1 and BRCA2 - defect in DNA repair can lead to breast cancer
ex BRAF - melanoma
what are some risk factors for cancer?
smoking
physical inactivity, diet etc
alcohol
infections
pollution
carcinogens
radiation
how does smoking cause cancer and what is the best prevention?
damage DNA and mutate tumour suppressant genes
prevention: cessation
how does physical inactivity cause cancer, best prevention?
obesity can cause increased bioavailability of growth factors and sex hormones and increase tumour regulating adipocytes
prevention: healthy weight, diet, lifetsyle
how does alcohol increase risk of cancer?
byproducts of alcohol metabolism are carcinogenic
how do infections increase risk of cancer? what is the best prevention?
alter immune system function by reduction of T-cell activation and production of pro-inflammatory cytokines
prevention: vaccinations
how does environmental pollution increase risk of cancer? what is the best prevention?
inhalation of carcinogens, consumption of contaminated food and water
prevention: limit exposure
how do occupational carcinogens increase risk of cancer? what is the best prevention?
modified immune response, tumour suppressor action and inflammation
Prevention: reduction or elemination
how does radiation increase risk of cancer? what is the best prevention?
deactivation of enzymes or rupturing or modifying of DNA
prevention: limit time or distance to exposure
how is Epstein Barr virus related to cancer?
herpes virus increases risk of Burkitt lymphoma, Hodgkin’s and non-hodgekin’s lymphoma and stomach cancer.
no vaccine
