Adenovirus encoding HIV-1 Vpr activates caspase 9 and induces apoptotic cell death in both p53 positive and negative human tumor cell lines.

The targeted delivery of genes whose products arrest the cell cycle and/or induce apoptosis represent an important tool for the understanding and controlling forms of unregulated cell growth. The vpr gene product of HIV-1 has been reported to interfere with cell growth and induce apoptosis, but the mechanism of its action is not clearly understood. In order to study these important properties of Vpr, we created a recombinant adenovirus H5.010CMV-vpr (adCMV-vpr) as a tool to deliver the vpr gene to various cell lines to examine its biology. Vpr protein expression was confirmed by Western blot analysis in adCMV-vpr infected cells. We tested the effects of adCMV-vpr on cell growth of several tumor cell lines. Infection of both p53 positive and p53 deficient tumor cell lines with adCMV-vpr resulted in dramatic induction of cell death in short-term assays. We observed that apoptosis was induced through the mitochondrial pathway as we observed changes in the cytochrome c content accompanied by caspase 9 activation. As Bcl-2 is reported to interfere with apoptosis through the mitochondrial pathway, we examined the effect of adCMV-vpr in Bcl-2 over expressing cell lines. We observed that Bcl-2 overexpression does not inhibit adCMV-vpr induced apoptosis. The properties of adCMV-vpr inducing apoptosis through caspase 9 in a p53 pathway independent manner suggest that this is an important reagent. Such a vector may give insight into approaches designed to limit the growth of pathogenic human cells.

Immunopharmacologic analysis of an autologous, hapten-modified human melanoma vaccine.

PURPOSE: We have previously reported a clinical trial of a human cancer vaccine consisting of autologous tumor cells modified with the hapten, dinitrophenyl (DNP), in patients with clinical stage III melanoma. Here we present a follow-up report expanded to 214 patients with 5-year follow-up. PATIENTS AND METHODS: Two hundred fourteen patients with clinical stage III melanoma (117 patients with stage IIIC and 97 patients with stage IIIB) who were melanoma-free after standard lymphadenectomy were treated with multiple intradermal injections of autologous, DNP-modified vaccine mixed with bacille Calmette-Guérin. Four vaccine dosage schedules were tested sequentially, all of which included low-dose cyclophosphamide. Patients were tested for delayed-type hypersensitivity (DTH) to autologous melanoma cells, both DNP-modified and unmodified, and to control materials. RESULTS: The 5-year overall survival (OS) rate of the 214 patients was 44%. DTH responses to unmodified autologous melanoma were induced in 47% of patients. The OS of this DTH-positive group was double that of DTH-negative patients (59.3% v 29.3%; P <.001). In contrast, positive DTH responses to DNP-modified autologous melanoma cells and to purified protein derivative developed in almost all patients but did not affect OS. Surprisingly, the OS after relapse was also significantly longer in patients who developed positive DTH to unmodified tumor cells (25.2% v 12.3%; P <.001). Finally, the development of DTH was dependent on the schedule of administration of the vaccine, specifically, the timing of an induction dose administered at the beginning of the treatment program. CONCLUSION: This study underscores the importance of the immunopharmacology of the autologous, DNP-modified vaccine and may be relevant to other cancer vaccine technologies.