DECREASE IN THE EXPRESSION OF A NOVEL TGF BETA-1-INDUCIBLE AND RAS-RECISION GENE, TSC-36, IN HUMAN CANCER-CELLS

TSC-36, a TGF beta 1-inducible gene, encodes a polypeptide that shows significant similarity to SPARC (secreted protein rich in cysteine), a nd follistatin, an activin-binding protein. The expression of the TSC- 36 gene was reported to be extinguished in v-ras-transformed mouse fib roblastic cells, and also was found also to be abrogated in cells tran sformed with v-myc. The level of expression was, however, not affected in cells transformed with v-src, v-abl, or v-raf. The TSC-36 cDNA was first isolated from mouse cells, and recently its rat and human homol ogues have been reported which show striking similarity with each othe r. In various human tumor cells, TSC-36 mRNA was almost undetectable. TSC-36 mRNA was detected in various mouse organs, but its level was th e highest in the lung. TSC-36 mRNA level was the highest in the lung a mong mouse organs, and on in situ hybridization, the TSC-36 transcript was detected in the alveolar epithelium but not in the bronchial epit helium. These features suggest possible usage of TSC-36 as one of the markers in human tumors. (C) 1997 Elsevier Science Ireland Ltd.