myc

Myc

(mĭk)

n.

Any of several genes encoding DNA-binding proteins that can promote the development of various cancers when present at high concentrations.

The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

myc

An oncogene on chromosome 8q24 of cellular (c-myc) or viral (v-myc) origin, which was first identified in the genome of a group of acutely transforming retroviruses capable of inducing avian neoplasia, possibly linked to RNA processing.

Physiological
c-myc is present in normal tissues; the protein product is required for progression through the cell cycle. Myc-null cell lines show profound growth defect, with lengthening of G1 and G2 phases of the cell cycle. There is a marked reduction in cyclin D1-CDK4 and D1-CDK6 complexes during entry to S phase, with lesser reductions in cyclin E2-CDK2 and cyclin A-CDK2. Myc induces expression of cyclins D1 and D2.

Pathological
Oncogenic expression of c-myc involves mutations on exon 2, which occur in more than 50% of Burkitt's lymphomas. The typical translocation in Burkitt’s lymphoma is t(8;14)(q24;q23), juxtaposing the c-myc and the immunoglobulin heavy-chain genes. Variant translocations are to 2p11 or 22q11, juxtaposing kappa or lambda light-chain genes respectively. FISH performed with dual probes can demonstrate the IgH/c-myc translocation. Tricolour with a probe against the centromere of chromosome 8 will control c-myc amplification or loss of the derivative chromosome 8; dual colour break-apart probes will show splitting of the gene.

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