Rh2 Synergistically Enhances Paclitaxel or Mitoxantrone in Prostate Cancer Models

Purpose: We explored the efficacy of the ginsenoside Rh2 and examined its impact on the effective dose of paclitaxel and mitoxantrone in the LNCaP prostate tumor model.Materials and Methods: Cultured LNCaP cell viability was assessed following treatment (48 hours) with Rh2 (0 to 40 μM) alone or in combination with paclitaxel and mitoxantrone. Synergism or antagonism observed when combining treatment was calculated using CalcuSyn software (Biosoft®). In addition, the inhibition of LNCaP human xenograft tumor growth was examined in vivo when Rh2 treatment was combined with chemotherapy. Harvested tumors were immunohistochemical stained with p27kip and Ki67.Results: Rh2 and paclitaxel act synergistically in cultured LNCaP cells to lower ED50 and ED75 values. Rh2 and mitoxantrone are also synergistic. However, when combined as ED95, an antagonistic effect was observed in this cell line. Treatment of LNCaP tumors by Rh2 plus paclitaxel produced a significant decrease in tumor growth and serum prostate specific...