a gene found in the chromosomes of tumor cells whose activation is associated with the initial and continuing conversion of normal cells into cancer cells.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
Any of a family of genes that normally encodes proteins that are involved in cell growth or regulation (e.g., protein kinases, GTPases, nuclear proteins, growth factors) but that may foster malignant processes if mutated or activated by contact with retroviruses. Identified oncongenes include ras
, originally noted in bladder tumors, and p53, a mutated version of a gene on chromosome 17 that has been shown to be involved in more than half of all human cancers. Oncogenes can work in concert to produce cancer, and their action may be exacerbated by retroviruses, jumping genes, or inherited genetic mutations.
See also: tumor suppressor gene
2. A gene found in certain DNA tumor viruses. It is required for viral replication.
[onco- + gene]
Genes of mutations that can permit or induce uncontrolled cellular proliferation and malignant change are of two types: protooncogenes and tumor suppressor genes (antioncogenes). Protooncogenes encode proteins that stimulate DNA synthesis and cell division, including peptide growth factors and their cellular membrane receptors; second-messenger cascade proteins, which transmit information from cell membrane to nucleus; and nuclear transcription factors, which control gene expression by binding to DNA. Conversion of a protooncogene to an oncogene by amplification, translocation, or point mutation can lead to unrestrained cellular proliferation and malignant change. Only 1 copy (allele) of a protooncogene need undergo mutation to induce tumor formation. Protooncogenes are not involved in inherited cancer syndromes, with the exception of the RET protooncogene in multiple endocrine neoplasia. Tumor suppressor genes (antioncogenes), which encode proteins that normally serve to restrain cell proliferation, can be inactivated by point mutation, deletion, or loss of expression. An inherited mutation in 1 copy of a tumor suppressor gene is the basis of most familial predispositions to cancer. Malignant cellular proliferation does not occur until the remaining, functional copy of the gene is inactivated by mutation or by deletion of part or all of its chromosome. In a person born with two normal copies of a tumor suppressor gene, both must be inactivated by mutation before tumor formation occurs. BRCA1 and BRCA2, which predispose to familial early-onset breast cancer and ovarian cancer, are tumor suppressor genes.
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oncogene (ŏn′kə-jēn, ŏng′-)
1. Any of various mutated genes that cause the transformation of normal cells into cancerous cells.
2. Any of various viral genes that transform host cells into cancerous cells.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
Any of a family of genes, which under normal circumstances, code for proteins involved in cell growth or regulation (e.g., protein kinases, GTPases, nuclear proteins, growth factors) but may foster malignant processes if mutated or activated by contact with retroviruses. Oncogenes often work in concert to produce cancer, and their action may be exacerbated by retroviruses, jumping genes, or inherited genetic mutations.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
oncogene a gene causing cancer induction (ONCOGENESIS) in the host.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
A gene that has to do with regulation of cancer growth. An abnormality can produce cancer.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
Any of a family of genes that normally encodes proteins involved in cell growth or regulation but may foster malignant processes if mutated or activated by contact with retroviruses.
[onco- + gene]
Medical Dictionary for the Dental Professions © Farlex 2012