RESUMO
: Initially, patients that respond to cisplatin (DDP) treatment later relapse and develop chemoresistance. Agents that enhance DDP effectiveness will have a significant impact on cancer treatment. We have shown pronounced inhibitory effects of the progesterone-calcitriol combination on endometrial and ovarian cancer cell growth. Here, we examined whether and how progesterone-calcitriol combination potentiates DDP anti-tumor effects in cancer cells. Ovarian and endometrial cancer cells treated with various concentrations of DDP showed a concentration-dependent decrease in cell proliferation. Concurrent treatment of cells with DDP and progesterone-calcitriol ombination potentiated anticancer effects of DDP compared to DDP-calcitriol, or DDP-progesterone treated groups. The anticancer effects were mediated by increased caspase-3, BAX, and decreased BCL2 and PARP-1 expression in DDP and progesterone-calcitriol combination-treated cells. Stimulation of the PI3K/AKT and MAPK/ERK pathways seen in cancer cells was reduced in DDP-progesterone-calcitriol treated cells. Pretreatment of cells with specific inhibitors further diminished AKT and ERK expression. Furthermore, progesterone-calcitriol potentiated the anti-growth effects of DDP on cancer cells by attenuating the expression of SMAD2/3, multidrug resistance protein- 1 (MDR-1), and ABC transporters (ABCG1, and ABCG2), thereby impeding the efflux of chemo drugs from cancer cells. These results suggest a potential clinical benefit of progesterone-calcitriol combination therapy when used in combination with DDP.
RESUMO
BACKGROUND: Strategies are needed to coordinately block drivers and induce suppressors of cancer to reduce incidence and improve outcomes for individuals with inherited or acquired risk. We previously reported the chemopreventive and therapeutic efficacy of the combination of progestin and calcitriol in transformed and malignant endometrioid endometrial cancer (EC) and in ovarian cancer models involving attenuated expression of TGF-ß signaling proteins and progestin-mediated inhibition of calcitriol-induced CYP24A1 expression. This study aims to expand the applications for this combination to other subtypes of endometrial and ovarian cancers, including those with mutations in ARID1A or PIK3CA, DNA mismatch repair (MMR) deficiency or BRCA1 null status. METHODS: Ovarian and EC cell lines of different histotypes were cultured with either progesterone, calcitriol, or the combination of progesterone and calcitriol for 3 or 5 days. The end points for this in vitro investigation included assessments of cell growth by (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assays and the expression of TGF-ß ligands, receptors, SMAD proteins and CYP24A1 by western blotting. RESULTS: Treatment of ovarian clear cell carcinoma, endometrioid carcinoma, papillary serous adenocarcinoma, BRCA1 null, and DNA MMR deficient EC cell lines with progesterone alone or in combination with calcitriol inhibited cell growth and expression of TGF-ß1, TGF-ß2, TGF-Rß1, TGF-ßR2, pSMAD2/3 and CYP24A1. Expression of TGF-ßR3, SMAD-4, progesterone receptor (PR) and vitamin-D receptor (VDR) was not altered in any cell line tested except, ES-2, where VDR expression was upregulated in response to treatment. CONCLUSIONS: These results suggest that progesterone alone and progesterone-calcitriol combination have broad application in both chemopreventive and therapeutic settings that merit further development in a wide variety of ovarian and ECs, including those derived from germline or somatic mechanisms. Moreover, our data suggest that TGF-ß signaling proteins and CYP24A1 may be effective surrogate markers indicative of treatment response.
