oncogene

oncogene

 [ong´ko-jēn]

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.

on·co·gene

(ong'kō-jēn),

1. 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, antioncogene.

2. A gene found in certain DNA tumor viruses. It is required for viral replication.

Synonym(s): transforming gene

[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.

oncogene

(ŏn′kə-jēn, ŏng′-)

n.

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.

oncogene

[ong′kōjēn]

Etymology: Gk, onkos + genein, to produce

a potentially cancer-inducing gene. Under normal conditions such genes play a role in the growth and proliferation of cells, but, when altered in some way by a cancer-causing agent such as radiation, a carcinogenic chemical, or an oncogenic virus, they may cause the cell to be transformed to a malignant state.

on·co·gene

(on'kō-jēn)

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.
See: antioncogene

oncogene

a gene causing cancer induction (ONCOGENESIS) in the host.

Oncogene

A gene that has to do with regulation of cancer growth. An abnormality can produce cancer.

Mentioned in: Breast Cancer

on·co·gene

(ong'kō-jēn)

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]