Background: Targeting of the epidermal growth factor receptor (EGFR) pathway is a promising treatment strategy for aggressive androgen-refractory prostate cancer (PCa). The effect of treating the androgen-resistant PCa cell line DU145 with a combination of the anti-EGFR drug cetuximab and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) was evaluated.
Materials and methods: DU145 cells were treated with 5 nM cetuximab, 100 nM 1,25(OH)2D3 or a combination of both. The effect of the treatments on cell growth, cell-cycle and apoptosis was evaluated.
Results: Single-drug treatments decreased DU145 cell growth by up to 25% and caused a 1.5-to 1.7-fold increase of apoptosis, but did not affect the cell-cycle distribution. However, dual treatment with a combination of cetuximab and 1,25(OH)2D3 inhibited DU145 cell proliferation by 40%, caused considerable cell-cycle arrest in the Go/Gl-phase, and enhanced apoptosis by 2.5-fold (compared to the control, p < 0. 0001, p <0. 006 and p <0. 0001, respectively).
Conclusion: A combination of cetuximab and 1,25(OH)2D3 efficiently suppresses hormone-resistant PCa cell growth and could provide a basis for its clinical application.