Lecture 17 - Cancer Flashcards
(14 cards)
1
Q
What is cancer
A
a group of diseases characterized by:
- uncontrolled cell growth
- invasion of cells into surrounding tissue
- metastasis
2
Q
What are the hallmarks of cancer
A
- sustaining proliferative signaling
- evading growth suppressors
- activating invasion and metastasis
- enabling replicative immortality
- inducing angiogenesis
- resisting cell death
3
Q
What causes cancer
A
- genetic mutations
- chemical carcinogens
- radiation
- viral or bacterial infections
- heritable and/or lifestyle factors
4
Q
How do genetic mutations cause cancer
A
- inactivation of tumor suppressors
- alteration of DNA repair gene function
- overexpression of oncogenes
5
Q
What is associated with a poor prognosis in cancer
A
tumor associated macrophages
6
Q
What are tumor specific antigens
A
- specific to the tumor itself
- structurally novel proteins
7
Q
What are tumor associated antigens
A
- normal proteins, not limited to tumor
- failed to elicit complete tolerance by immune system
8
Q
What is evidence for TAA recognition
A
- immune attack on cancer cells can kill off normal cells too
- vitiligo –> immune system attacks cancer but also melanocytes in normal cells
9
Q
What are the 3 Es
A
- elimination
- equilibrium
- escape
10
Q
What is elimination
A
- tumor cell invasion causes an inflammatory response
- innate immune system attacks tumor mass via infiltrating lymphocytes
- release IFN-y cytokine
- IFN-y release stimulates chemokine production
-tumor cell death - dendritic cell
- NK cells and macrophages activate each other
- adaptive immune response
11
Q
What is elimination
A
- selection pressure on tumor by lymphocytes and IFN-y
- tumor cells develop immunological resistance
- can last years
12
Q
What is escape
A
- growth takes over
- takes years to develop a clinically apparent tumor
- most times by the time it is detected it is immuno-resistant
13
Q
What are immunoevasion strategies
A
- hide identity
- avoid apoptosis
- induce immunocyte apoptosis
- neutralize complement
- inactivate immunocytes
14
Q
How do tumor cells hide their identity
A
- stop displaying TAA or TSA
- repress MHCI transcription
- avoid apoptosis using killer immunoglobulin-like receptors
- only suppress 1/6 of MHC class I molecules
- induce immunocyte apoptosis using FasL
- regulate the IS (overexpress anti-complement proteins)
- exploit the immune system
