Deregulation of c-myc gene expression in human colon carcinoma is not accompanied by amplification or rearrangement of the gene.
The structure and expression of the c-myc oncogene were examined in 29 primary human colon adenocarcinomas. Dot blot hybridization of total RNA showed that 21 tumors (72%) had considerably elevated expression of c-myc (5- to 40-fold) relative to normal colonic mucosa. These data were corroborated by Northern blots of polyadenylated RNA, which showed a 2.3-kilobase transcript. Southern analysis of the c-myc locus in these tumors indicated the absence of amplification or DNA rearrangement in a 35-kilobase region encompassing the gene. In a parallel study, elevated expression of c-myc without amplification or DNA rearrangement was also observed in three of six colon carcinoma cell lines examined; in addition, unlike a normal colon cell line control, these three cell lines exhibited constitutive, high-level expression of the gene during their growth in cultures. These results indicate that elevated expression of the c-myc oncogene occurs frequently in primary human colon carcinomas and that the mechanism involved in the regulation of c-myc expression is altered in tumor-derived cell lines.
D002460:Cell Line; D002478:Cells, Cultured; D003106:Colon / Q000378:metabolism; D003110:Colonic Neoplasms / Q000235:genetics*; D005784:Gene Amplification; D005809:Genes, Regulator; D006801:Humans; D009693:Nucleic Acid Hybridization; D009857:Oncogenes; D012334:RNA, Neoplasm / Q000302:isolation & purification; D014158:Transcription, Genetic
D012334:RNA, Neoplasm