The cytotoxic effect of gossypol (GP), a phytochemical compound, and zoledronic acid (ZA), a nitrogen-containing bisphosphonate, was evaluated in the human androgen receptor-negative and drug-resistant DU-145 prostate cancer cell line, an experimental cellular model for studying the behavior of aggressive metastatic human prostate carcinoma. The gene discussed is AR; the disease is prostate carcinoma.