Cancer-Predisposing Genes
المؤلف:
Mary Louise Turgeon
المصدر:
Immunology & Serology in Laboratory Medicine
الجزء والصفحة:
5th E, P478-479
2025-11-09
67
Cancer-predisposing genes may act in the following ways:
• Affect the rate at which exogenous precarcinogens are metabolized to actively carcinogenic forms that can damage the cellular genome directly
• Affect a host’s ability to repair resulting damage to DNA
• Alter the immune ability of the body to recognize and eradicate incipient tumors
• Affect the function of the apparatus responsible for the regulation of normal cell growth and associated proliferation of tissue
Relatively few cancer-predisposing genes have been described. An absence of functional alleles at specific loci, however, allows the genesis of the malignant process (Table 1). For example, individuals with certain mutations in the gene BRCA2 are at a very high risk (up to 85%) for developing breast cancer and other cancers (e.g., ovarian cancer) because a DNA repair path cannot properly repair ongoing wear and tear to the DNA.
Table1. Tumors Associated With Homozygous Loss of Specific Chromosomal Loci
A mutation in a gene thought to be responsible for colon cancer may initially cause it. This gene, APC, normally limits the expression of a protein, survivin. When APC is altered, survivin works overtime and, instead of dying, stem cells in the colon overpopulate, resulting in cancer. Survivin is overex pressed in colon cancer. It prevents programmed cell death, or apoptosis, the process whereby cells normally die. Rather than dying on schedule, cancer cells instead grow out of control. The APC gene controls the amount of survivin by shutting down its production.
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