SEVERAL GENES ENCODING RIBOSOMAL-PROTEINS ARE OVER-EXPRESSED IN PROSTATE-CANCER CELL-LINES - CONFIRMATION OF L7A AND L37 OVER-EXPRESSION INPROSTATE-CANCER TISSUE SAMPLES

A cDNA library specific for mRNA over-expressed in prostate cancer was generated by subtractive hybridization of transcripts originating fro m prostatic hyperplasia and cancer tissues. cDNA encoding ribosomal pr oteins L4, L5, L7a, L23a, L30, L37, S14 and S18 was found to be presen t among 100 analyzed clones. Levels of ribosomal mRNA were significant ly higher at least in one of the prostate-cancer cell lines, LNCaP, DU -145 and PC-3, than in hyperplastic tissue, as determined by slot-blot hybridization. Furthermore, L23a- and S14-transcript levels were sign ificantly elevated in PC-3 cells as compared with those in the normal prostate epithelial cell line PrEC. Generally, dramatic changes in the mRNA content of the ribosomal proteins were not detected, the most ev ident over-expression bei ng that of L37 mRNA, which was 3.4 times mor e abundant in LNCaP cells than in hyperplastic prostate tissue. The ov er-expression of L7a and L37 mRNA was confirmed in prostate-cancer tis sue samples by in situ hybridization. Elevated cancer-related expressi on of L4 and L30 has not been reported, but levels of the other riboso mal proteins are known to be increased in several types of cancers. Th ese results therefore suggest that prostate cancer is comparable with other types of cancers, in that a larger pool of some ribosomal protei ns is gained during the transformation process, by an unknown mechanis m. Int. J. Cancer 78:27-32, 1998. (C) 1948 Wiley-Liss, Inc.