A recombinant defective adenoviral agent expressing anti-bcl-2 ribozyme promotes apoptosis of bcl-2-expressing human prostate cancer cells

Over-expression of bcl-2, a potent anti-apoptosis protein, is likely to be one of the genetic mechanisms through which human prostate cancer cells dev elop resistance to hormonal and other forms of therapy. To develop a therap eutic agent for hormone-resistant prostate cancer based on suppression of b cl-2 expression, we had previously designed and synthesized a dual-hammerhe ad ribozyme capable of recognizing and specifically cleaving human bcl-2 mR NA in vitro as well as in vivo. To increase the efficiency by which the ant i-bcl-2 ribozyme can be delivered to target cells, we have created a recomb inant replication deficient (defective) adenoviral agent capable of express ing the anti-bcl-2 ribozyme upon infection. This viral agent effectively re duces intracellular levels of bcl-2 mRNA and protein in cultured LNCaP pros tate cancer cells following standard infection procedures. Likewise, the de fective adenovirus-anti-bcl-2 ribozyme induces extensive apoptosis in sever al androgen-sensitive (LNCaP) and androgen-insensitive (LNCaP/bcl-2 and PC- 3) human prostate cancer cell lines that express differing amounts of bcl-2 protein. One androgen-insensitive prostate cancer cell line, DU-145, lacki ng in bcl-2 expression, was found to be completely refractory to the effect s of the virus ribozyme, supporting the concept that the cytotoxic effects of the ribozyme are based solely on its effects on bcl-2 expression. Our re sults support further development of this adenovirus/anti-bcl-2 ribozyme fo r potential gene therapeutic purposes in certain forms of hormone-resistant prostate cancer where over-expression of bcl-2 proto-oncogene is indicated . (C) 1999 Wiley-Liss, Inc.