The cancer-associated Sm-like oncogene: A novel target for the gene therapy of pancreatic cancer

Abstract

Background: The prognosis for pancreatic cancer (PC) remains dismal, providing a clear need for the development of novel therapies. We have previously shown that the cancer-associated Sm-like (CaSm) oncogene is overexpressed in the great majority of pancreatic tumors and is required to maintain the transformed phenotype. The purpose of this study was to determine whether the application of CaSm antisense gene therapy would generate a significant antitumor effect against PC. Methods: An adenoviral vector (Ad-αCaSm) expressing a 900–base pair antisense RNA to CaSm was created. The PC cell lines AsPC-1 and Capan-1 were infected with this vector and examined for changes in in vitro proliferation by using methyl thiazol tetrazolium and soft agar assays. SCID-Bg mice bearing subcutaneous AsPC-1 tumors were treated with Ad-αCaSm (1 × 109 plaque-forming units) as a single intratumor injection with tumor growth and survival monitored. Results: AsPC-1 and Capan-1 cells showed decreased in vitro proliferation (93%, P =.0041, and 70%, P =.0038, respectively) and anchorage independent growth (55%, P =.02, and 45%, P =.03, respectively) after treatment. Ad-αCaSm reduced in vivo AsPC-1 tumor growth by 40% (n = 10), extending median survival time from 35 to 60 days. Conclusions: Ad-αCaSm demonstrates a significant antitumor effect against pancreatic cancer both in vitro and in vivo. These results support the role of CaSm as a significant gene involved in the neoplastic transformation of pancreatic tumors. Thus CaSm represents a novel gene target in PC and holds potential as a new treatment approach either alone or in combination with existing therapies. (Surgery 2000;128:353-60.)