Associate Professor KCOM/A.T.Still University Kirksville, Missouri, United States
Pandurangan Ramaraj (KCOM/A.T.Still University)
Our previous study showed that steroids especially progesterone and RU-486 significantly inhibited human melanoma (BLM) cell growth in-vitro. As lack of vitamin-D can lead to cancer and vitamin-D is synthesized in the skin by the UV rays, we decided to check the combined effect of vitamin-D3 and progesterone on human melanoma cell growth. Along with vitamin-D3, we also decided to include vitamin-A and RU-486. So our aims were to check the in-vitro effects of active vitamin-D3 and vitamin-A combined with progesterone and RU-486 on human melanoma (BLM) cell growth. Initially dose-curve (100 nM to 100 µM concentration) study was carried out with vitamin-D3 and vitamin-A (retinoic acid) to determine the optimal concentrations of vitamins-D3 and A for co-incubation with progesterone (50 µM) and RU-486 (50 µM). Vitamin-D3 and vitamin-A showed a dose-dependent decrease in cell growth. Based on the dose-curve, it was decided to use 25 µM (at 57% cell growth) of vitamin-D3 and 50 µM (at 55% cell growth) of vitamin-A for co-incubation between them and also with progesterone and RU-486 separately. Co-incubation of vitamin-D3 and vitamin-A showed an additive effect on the decrease of cell growth (at 20%). Similarly co-incubation of vitamin-D3 with progesterone (at 33% cell growth) and RU-486 (at 28% cell growth) as well as co-incubation of vitamin-A with progesterone (at 31% cell growth) and RU-486 (at 18% cell growth) showed an additive effect on the decrease of cell growth. Since our previous study also showed the involvement of IL-8 in the regulation of melanoma cell growth, supernatants from the treated cells were subjected to Elisarray. There was a decrease in IL-8 secretion with vitamin-D3 treatment. But, vitamin-A alone treatment showed an increase in IL-8 secretion. However, co-incubation of vitamin-A with vitamin-D3, progesterone and RU-486 showed a decrease in IL-8 secretion. These studies suggested that a combination of vitamins and steroids might be effective in decreasing melanoma cell growth than vitamin or steroid alone.
Conclusion: Co-incubation of vitamins with steroids indicated a combo drug effect on the decrease of melanoma cell growth. Hence, various combinations of vitamin-D3, vitamin-A and steroids would be tested for their effect on melanoma cell growth in vitro.