Marked induction of HSP47, a collagen-binding stress protein, during solid tumor formation of ascitic Sarcoma 180 in vivo.

HSP47, a heat shock-inducible glycoprotein of Mr = 47,000, is assumed to be a molecular chaperone specific for collagen. In addition to its stress inducibility, HSP47 has transformation-sensitivity; that is, the synthesis of HSP47 decreases after malignant transformation. We developed a rat monoclonal antibody against mouse HSP47, which we then used to examine the amounts of HSP47 in transplanted tumors. HSC70 (HSP73) was expressed constitutively in these ascites as well as solid tumors. While HSP47 was not expressed in ascitic form of Sarcoma 180, its expression was markedly induced during solid tumor formation of ascitic Sarcoma 180 cells after subcutaneous transplantation. The average survival period of ascites Sarcoma 180-bearing mice was 20.3 +/- 3.6 days (mean +/- SD), and was much shorter than that of solid Sarcoma 180-bearing mice. These findings suggest an important role of HSP47 in solid tumor formation as well as a possible marker for tumor malignancy.