Chapter 16 Flashcards
(22 cards)
What the similarities shared among different types of cancer cells?
1) Aberrant chromosome numbers (aneuploidy)
2) Fail to elicit apoptosis
3) High metabolic requirements
What are some characteristics of cancer stem cells (CSC0?
1) thought to self-replicate and produce progenitors that generate all of the cell types that make up a tumor
2) Adapt and can resist chemotherapy-radiation therapy
What are tumor-suppressor genes?
Encode proteins that restrain cell growth
What is the Retinoblastoma gene?
1) First tumor-suppressor gene to be discovered
2) Inherited in certain families
3) Development of RB requires both copies of RB to be altered
What is the role of pRB in regulating the cell cycle?
1) Protein encoded by pRB gene regulates G1 to S transition
2) TFs of E2F family are targeted by pRB
3) Arrest of the cell cycle in G1, required for normal cell differentiation is directed by pRB.
What is the function of p53 protein?
1) Acts as a transcription factor, activating the expression of a gene that inhibits the G1-S transition
2) Triggers apoptosis in cells whose DNA is damaged beyond repair
What happens to p53 concentration when the cell sustains DNA damage?
rises
What are oncogenes?
1) Encode proteins that promote the loss of growth control and the conversion of a cell to a malignant state
2) Altered cellular gene (proto-oncogene)
3) Act dominantly
What needs to be happen for a cell to become malignant?
1) Both alleles of a tumor-suppressor gene must be lost
2) Proto-oncogene must be converted into oncogene
What are the mechanisms by which protooncogenes can be converted into oncogenes?
1) Gene can be mutated to alter the properties of the gene product so that it doesn’t function normally
2) Gene can become duplicated resulting in gene amplification and excess protein production
3) Chromosome rearrangement that brings a DNA sequence into close proximity of the gene, to either alter the expression of the gene or the nature of the gene product
What is the significance of the Simian sarcoma virus?
contains the oncogene (sis) which is derived from a cellular gene which codes for the growth factor PDGF
What does the Oncogene (erbB) do?
directs the formation of an altered EGF receptor that stimulates the cell regardless of the presence of growth factor
What is Raf?
Serine-threonine protein kinase in the MAP kinase cascade, can be converted into an oncogene by mutations that turn it into an enzyme that is always “on”
What is Src?
Oncogene product, protein tyrosine kinase which phosphorylates proteins involved in signal transduction, control of the cytoskeleton, and cell adhesion
What is an oncogene that encode nuclear transcription factors?
Myc protein stimulates cells to re-enter cell cycle from G0 stage
* Overexpression may cause cells to proliferate uncontrollably
What is an example of an oncogene that encode products that affect apoptosis?
Bcl-2 gene leads to suppression of apoptosis, allowing abnormal cells to proliferate into tumors
What is Passive immunotherapy?
Utilizes the stategy of administering antibodies as therapeutic agents
What are some antibodies associated with passive immunitherapy?
1) Herceptin- antibody against growth factors that stimulates proliferation of breast cancer cells
2) Rituxan- antibody that binds to cell surface proteins of non-Hodgkin’s lymphomas
3) Vestibix- antibody directed against the EGF receptor or colon cancer
What is active immunotherapy?
tries to get the patient’s own immune system to act against malignant cells
What are some possible active immunotherapy treatments?
1) Dendritic cells may be taken from cancer patients and can be made to display tumor proteins, then injected back into the patient so that the tumor can be rejected
2) Develop cancer vaccines against telomerase
3) Tumor-infiltrating lymphocyte therapy
What is angiogenesis?
As a tumor grows, it stimulates the formation of new blood vessels
What is a compound that could inhibit angiogenesis?
1) Avastin (mAb): Interruption of VEGF-VEGFR interaction
2) Inhibition of angiogenesis denies the tumor access to nutrients and oxygen needed to grow
