Cancer Genetics Flashcards
(32 cards)
What is a tumor?
An abnormal mass of cells resulting from a defect in cell proliferation and survival control
What is a benign tumor? A malignant one?
Benign- similar to surrounding cells, slow growing, non-invasive, no metastasis; Malignant- rapid growth, undifferentiated, invasive, potentially metastatic
What is responsible for about 90% of cancer-related deaths?
Metastasis
What is the general classification of cancers of epithelial tissues?
Carcinoma
What is the general classification of cancers of connective and fibrous tissues?
Sarcoma
What are cancers of circulating blood cells of the bone marrow classified as?
Leukemias
What classification of cancer makes up 90% of human cancers?
Carcinoma
According to the multiple hit model of molecular cancer development, what are the six capabilities the original, non-cancerous cell must aquire through mutations or alterations?
Independence from external growth signals, Insensitivity to external anti-growth signals, Evading apoptosis and cellular death, Immortalization (infinite replication and division), Promotion of angiogenesis, Capability of tissue evasion and metastasis
What is the difference between a monoclonal and polyclonal tumor?
Monoclonal tumors derive from a single cell; polyclonal tumors derive from several individual cells within a similar tissue type all receiving a series of mutations
What is an oncogene?
A gene whose normal activity promotes cellular proliferation or division
What is a tumor supressor?
A gene whose wild type protein product functions to block cell division or promote cellular death
What is the non-mutant or wildtype version of an oncogene?
Proto-oncogene?
What kind of mutation activates a proto-oncogene to an oncogene?
Gain of function mutation
By what mechanisms can mutations result in activation of oncogenes?
Point mutation resulting in a constiutively active form of the protein; Amplification (more copies of gene present); Higher transcription (insertion into transcriptionally active area); translocation resulting in fused proteins
What is the mechanism by which Ras becomes an oncogene?
A single point mutation is intriduced (Gly–>Val) resulting in a protein that hydrolyzes GTP very inefficiently, effectively making it excessively active promoting genes important for growth and survival
Through what mechanism does Myc become oncogenic?
Amplification of the c-Myc gene
What kind of protein is Myc?
Transcription factor
What is the Philadelphia chromosome? With what cancer is it associated?
It results from a translocation between the p34 region of chromosome 9 and the p11 region of chromosome 22; chronic myelogenous leukemia
What is the protein product of the Philadephia chromosome?
Fused Bcr-Abl gene
What are the functions of tumor suppressor genes?
Regulators of cell cycle; inducer of apoptosis; transcription factors (repressors or activators)
What concept can serve as a general paradigm for how loss of tumor surpressors must occur for cancer to develop?
Two-Hit Model
What are the mechanisms by which a tumor suppressor can become inactive?
Loss of heterozygosity; silencing through epigenetics
How are genes silecenced through epigenetics?
Methylaton at promoters
What is the “guardian of the genome”
p53
