L18: Tumors Flashcards
What is metastasis?
spreading of cancer cells through lymph of bloodstream to distant parts of the body
What is malignant transformation?
when a cell has become able to form a cancer
What are proto-oncogenes?
genest that normally contribute positively to the initiation and execution of cell division
What are oncogenes?
mutant forms of proto-oncogenes that contribute to malignant transformation
What are mutagens?
chemical or physical agents that increase mutation rate
What are carcinogens?
a mutagen that increases the risk of cancer cell formation
What are the two type of genes that if mutated, can lead to cancer?
- proto-oncogenes
2. tumor suppressor genes
About how many mutations does a cell have to to acquire to become a cancer cell?
5-6 usually but can be more or less
What type of mutations do chemical carcinogens typically give rise to?
single base change mutations
What type of mutations does radiation tend to induce?
more pronounced mutations (DNA breaks, cross-linked nucleotides, abnormal recombination, etc)
What is an oncovirus?
pathogenic virus that infects cells and begins to exrpess virally encoded proteins that can over-ride the cell’s normal mechanisms for regulating cell division.
Can also prevent normal tumor suppression mechanisms
What type of immune cells can easily recognize and kill tumor cells?
allogeneic CD8 T cells.
Allogeneic meaning from other individuals or antigen-distinct
What are tumor antigens?
antigens found on tumor cells, but not on normal cells
What are tumor-associated antigens?
antigens found on tumor cells and normal cells, but in smaller numbers on normal cells
What are most tumor antigens recognized and what class MHC do they bind to?
most bind to MHC class I and are recognized by CD8 T cells. They do however have the ability to be recognized by B cells
Can a person be “vaccinated” against specific tumors?
Theoretically yes. as long as there is an antigen to be recognized
How do tumor cells evade immune responses?
they are similar enough to appear as self molecules. almost half have mutations in MHC class I HLA, so they cannot be recognized by effector CTLs. Some create an immunosuppression zone by producing cytokines to suppress immune responses
Are tumor cells that do not express MHC class I susceptible to NK cell killing?
yes, but only if they are devoid of production of all the MHC class I alleles.
What is the major downside of using monoclonal antibody treatments for tumor-specific treatments?
the foreign antibodies are recognized by the immune system and can only be used once without causing a severe immune reaction
How can T cell responses be boosted to help fight cancer?
T cells specific for tumor antigens can be isolated from a patient and can be grown in vitro, then injected back into the patient.
How is recombinant DNA being used to treat cancer?
Tumor cells are transfected with it to produce cytokines or chemokines that either stimulate or chemattract DCs to the tumor to facilitate uptake and presentation of tumor antigens to naive T cells.
What are sarcomas?
cancer of cells other than epithelial cells
What are carcinomas?
cancer of epithelial cells
What are leukemias?
cancer of circulating cells
