Ch. 19 Cancer and the Immune System Flashcards
benign
unable to invade healthy surrounding tissue
malignant
becomes progressively more invasive
metastasis
invasion of other distant tissues
Carcinomas arise from
epithelial cells; skin, gut, glands, lining of internal organs
Sarcomas arise from
mesodermal connective tissues; bone, fat, cartilage
Sarcomas arise from
mesodermal connective tissues; bone, fat, cartilage
Myelomas arise from
plasma cells
Leukemia’s arise from
WBCs in blood
Lymphomas arise from
WBCs in lymphatic tissues
3 carcinogens that can promote development of cancer
- chemical subs (formaldehyde)
- physical agents (asbestos)
- Irradiation (x-rays)
- viruses
What agency is responsible for tracking possible links to cancer?
International Agency for Research on Cancer (IARC)
What did Dr. Rous discover?
observed that a cancer-causing retrovirus (Rous sarcoma virus) leads to malignant transformation; malignant sarcomas in chickens could be transferred to another via cell-free filtrate
What did Dr. Temin discover?
suggested that oncogenes may be normal in cells and viruses might acquire these growth-promoting genes from previously infected cells (proto-oncogenes)
Proto-oncogenes
produce essential growth-controlling proteins; may lead to cancer if altered to lose control of expression or protein function.
What ways can convert a proto-oncogene to a v- or c-oncogene?
- actions of transforming viruses
- exposure to carcinogenes
- genetic predispositions
How can malignant transformation be accomplished by a virus like RSV?
RNA retroviruses reverse transcribe their genomes into DNA and integrate into the host genome–> viral genome has close contact with neighboring genes –> RSV acquires a copy of src causing infected cells to misregulate their growth because they have an extra copy of the src once infected
Oncogenes
enhance cell survival when their control mechanisms fail; become enemy when activity is enhanced
Tumor-suppressor genes
allow cancer cell survival when they fail; become the villain when activity is depressed
Which one needs to be underactive to promote cancer (oncogene or tumor suppressor gene)?
tumor suppressor gene
Which one needs to be overactive to promote cancer (oncogene or tumor suppressor gene)?
oncogene