oncogene

1. Any of a family of genes that normally encode proteins 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. SYN: transforming gene. [onco- + gene] Genes whose mutations can permit or induce uncontrolled cellular proliferation and malignant change are of 2 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 o. 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 2 normal copies of a tumor suppressor gene, both must be inactivated by mutation before tumor formation occurs. BRCA1 and BRCA2, which are associated with familial early-onset breast cancer and ovarian cancer, are tumor suppressor genes.
- ras o. point mutations first described in rat sarcoma cells that can be shown to have transforming activity in culture as well as in tumorigenesis models in mice; the ras gene family is composed of three closely related genes on three different chromosomes; abnormalities have been identified in a variety of human tumors.

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on·co·gene 'äŋ-kō-.jēn n a gene having the potential to cause a normal cell to become cancerous

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n.
a gene in viruses (v-onc) and mammalian cells (c-onc) that can cause cancer. It results from the mutation of a normal gene. An oncogene is capable of both initiation and continuation of malignant transformation of normal cells. It probably produces proteins (growth factor) regulating cell division that, under certain conditions, become uncontrolled and may transform a normal cell to a malignant state.

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on·co·gene (ongґko-jēn) a gene capable under certain conditions of causing the initial and continuing conversion of normal cells into cancer cells. The term may be used to denote such a gene occurring in a viral genome (v-onc) or a cellular gene derived from alteration of a proto-oncogene (c-onc).

Medical dictionary. 2011.

Look at other dictionaries:

  • oncogène — [ ɔ̃kɔʒɛn ] adj. • 1951; du gr. onkos « grosseur, tumeur » et gène ♦ Didact. Qui favorise le développement des tumeurs, notamment des tumeurs malignes (⇒ cancérigène). Virus oncogène. Gène oncogène ou n. m. un oncogène : gène, souvent porté par… …   Encyclopédie Universelle

  • oncogene — oncogene. См. онкоген. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • oncogene — (n.) 1969, from ONCO (Cf. onco ) + gene, from root of Gk. gignere (perf. genui) beget, from PIE *gen produce (see GENUS (Cf. genus)) …   Etymology dictionary

  • oncogene — ☆ oncogene [äŋ′kə jēn΄ ] n. [< Gr onkos, mass + GENE] any of various genes that, when activated as by radiation or a virus, may cause a normal cell to become cancerous oncogenic [äŋ′kəjen′ik] adj …   English World dictionary

  • Oncogene — For the journal, see Oncogene (journal). An oncogene is a gene that has the potential to cause cancer.[1] In tumor cells, they are often mutated or expressed at high levels.[2] An oncogene is a gene found in the chromosomes of tumor cells whose… …   Wikipedia

  • Oncogène — Les oncogènes sont une catégorie de gènes dont l expression favorise la survenue de cancers. Ce sont des gènes qui commandent la synthèse d oncoprotéines (protéines anormales stimulant la division et la différenciation cellulaire) et déclenchent… …   Wikipédia en Français

  • oncogene — /ong keuh jeen /, n. Genetics. any gene that is a causative factor in the initiation of cancerous growth. [1965 70; ONCO + GENE] * * * Gene that can cause cancer. It is a sequence of DNA that has been altered or mutated from its original form,… …   Universalium

  • oncogene — A gene that causes cells to grow in an uncontrolled (i.e. tumourous) manner. Oncogenes are mutant forms of normal functional genes (called proto oncogenes) that have a role in regulating cell proliferation. See: cellular oncogene; dominant… …   Glossary of Biotechnology

  • Oncogene — Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. Sur les autres projets Wikimedia : « oncogène », sur le Wiktionnaire (dictionnaire universel) Les oncogènes, une catégorie de gènes… …   Wikipédia en Français

  • oncogene — Mutated and/or overexpressed version of a normal gene of animal cells (the proto oncogene) that in a dominant fashion can release the cell from normal restraints on growth, and thus alone, or in concert with other changes, convert a cell into a… …   Dictionary of molecular biology

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