Identification of a serum-inducible messenger RNA (5B10) as the mouse homologue of calcyclin: tissue distribution and expression in metastatic, ras-transformed NIH 3T3 cells.

A mouse mRNA, provisionally designated 5B10, has been cloned based on its inducibility by serum in quiescent murine fibroblasts. Here we report the full-length complementary DNA sequence and a partial characterization. There are about five copies of the gene in the mouse genome. Sequence analysis of the 5B10 coding region reveals 94 and 97% amino acid identity to human and rat calcyclin, respectively. Although the coding region has been highly conserved during evolution of the rodent and human genomes, the untranslated flanking sequences differ significantly. A protein of Mr about 8000 was produced by in vitro translation of the mRNA transcribed in vitro from 5B10 complementary DNA in a riboprobe vector. An antiserum raised against a portion of the predicted human calcyclin protein cross-reacted with this mouse protein. 5B10 mRNA was found in greatest amount in organs containing proliferating cells, e.g., epidermis, skin, stomach, uterus of pregnant mouse, placenta, and decidua. Brain, liver, mature thymus, and skeletal muscle had little or no detectable 5B10 mRNA. 5B10 mRNA levels were higher in cells treated with 7,12-dimethylbenzanthracene and 12-O-tetradecanoylphorbol-13-acetate than in their normal counterparts, suggesting a role in tumorigenesis. In addition, high 5B10 mRNA levels were associated with metastatic ability in a series of ras-transformed cells, in proportion to levels of ras p21 expressed by the cells, implicating 5B10 even more deeply in carcinogenesis.