Journal Article

Co-overexpression of DEAD box protein rck/p54 and c-myc protein in human colorectal adenomas and the relevance of their expression in cultured cell lines

Keisuke Hashimoto, Yoshihito Nakagawa, Hiroshi Morikawa, Masami Niki, Yutaro Egashira, Ichiro Hirata, Kenichi Katsu and Yukihiro Akao

in Carcinogenesis

Volume 22, issue 12, pages 1965-1970
Published in print December 2001 | ISSN: 0143-3334
Published online December 2001 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/22.12.1965
Co-overexpression of DEAD box protein rck/p54 and c-myc protein in human colorectal adenomas and the relevance of their expression in cultured cell lines

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The RCK gene was cloned through a study of the breakpoint of the t(11;14)(q23;q32) chromosomal translocation observed in a human B-cell lymphoma and overexpression of the protein (rck/p54) due to the translocation was shown to be associated with malignant transformation. The rck/p54 protein belongs to the DEAD box protein/RNA helicase family, which has a variety of functions such as translation initiation, pre-mRNA splicing and ribosome assembly. It is considered that rck/p54 protein may have significant effects on the mRNA structure of genes associated with cell proliferation, facilitating protein synthesis. Expression of rck/p54 in colorectal adenomas, which are a premalignant lesion of colorectal cancer, was examined by Western blot analysis and immunohistochemistry. The rck/p54 protein was found to be overexpressed in tumor tissues resected from 17 of 26 cases (65.4%) of colorectal adenomas and 13 of 14 c-myc-positive cases (92.8%) also co-overexpressed rck/p54 protein. Thus, a significant correlation between rck/p54 and c-myc co-overexpression was found (Spearman's rank correlation, P = 0.0018). We demonstrate that overexpression of rck/p54 in two different cell lines, COS 7 and human colorectal cancer cell line SW480, caused an increase in c-myc protein levels by enhancement of its translation efficiency and/or stabilization of its mRNA. These results suggest that rck/p54 of the DEAD box protein/RNA helicase family may contribute to cell proliferation and carcinogenesis in the development of human colorectal tumors at the translational level by increasing synthesis of c-myc protein.

Keywords: PBS, phosphate-buffered saline; SSCP, single strand conformation polymorphism; TPBS, PBS containing 0.1% Tween 20.

Journal Article.  4751 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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