Anticancer effect of a lentiviral vector capable of expressing HIV-1 Vpr

A lentiviral vector capable of expressing the HIV-1 vpr gene (Vpr lentivira l vector) was constructed, and its in vivo anticancer effect was determined against cutaneous tumors derived from the AT-84 oral cancer cells in immun ocompetent mice. A single intratumoral injection of the Vpr lentiviral vect or not only significantly reduced the primary tumor volume but also complet ely regressed tumors in >40% of animals. More interestingly, the mice of wh ich the primary tumors were completely regressed by the Vpr lentiviral vect or were additionally protected from a secondary challenge of AT-84 cells. T hese data suggest that the Vpr lentiviral vector elicits its anticancer act ivity in part by the activation of the immune system. The above suggestion is additionally supported by the failure of the lentiviral vector to demons trate anticancer activity in immunocompromised nude or SCID mice. The Vpr l entiviral vector offers a powerful new strategy for cancer gene therapy and may be useful for the control of solid tumors, such as human oral squamous cell carcinomas.