Flashcards in cancer biology (gain/loss of function) Deck (22):
What are oncongenes?
regulatory genes that control cell division and growth
What can oncogenes do to form cancer?
can increase growth - produce growth factors
decrease growth factor requirements -increase growth factor receptors
What is Ras?
gene that can transfect cells with Ras and see tumor development
Ras mutation is found in 25% of human tumors
What can be done to oncogene that can result in cancer formation?
move it next to a strong promoter
How is burkitts B cell lymphoma produced?
Moving the myc ocongene next to the B cell (immunoglobulin) promoter. this turns on the gene to a;ways produce b cells
What are oncogenes that control cell death if the cell is abnormally growing?
tumor suppressor genes
What happens if a a tumor suppressor gene is lost?
could lead to tumor development
What is the function of tumor suppressor genes?
normal genes that monitor any cell and if any DNA damage the cell goes to apoptosis.
just don't monitor tumor cells
What is p53?
a tumor suppressor gene
How many human tumors lack the p53 function?
~50% of human tumors have p53 that is mutated
Which residues are mostly mutated in p53?
the parts that come in contact with DNA
Why are cancers more prevalent in the elderly?
1) more carcinogen exposure
2)decreased immune activity
3) age associated changes (hormone changes)
4) greater chance of multiple mutations
How many genetic changes does colon cancer need before cancer develops?
3-6 genetic changes
What are the function of natural killer cells?
they monitor abnormal cells
NKC does not work as well in the elderly
What is the APC gene?
it is a tumor suppressor gene
What is a mutation in the APC gene lead to?
doesn't monitor cells in colon
polyp formation in the colon
the earlier in life APC mutation the higher chance of developing colon cancer earlier in life
What are lose of function mutation?
loss of the function of a gene leads to cancer
ex: tumor suppressor genes lead to uncontrolled growth
What are gain of function mutation?
when a gene mutation heads to a gain of function leads to uncontrolled growth
ex: oncognes that produce growth regulators
is cancer caused by a single mutation?
it takes multiple mutations to cause cancer
What are the multiple mutations that effect TSGs/oncogenes are due to?
Carcinogens (chemical agents, UV radiation)
inherited mutation that affect TSGs
How many mutations is needed to produce cancer cells in a gain of function mutation?
only one allele needs to be mutated to show some overactivity. this happens in oncogenes that code for growth factors