Abstract 1929: Progesterone induces apoptosis by activation of caspase-8 and calcitriol via activation of caspase-9 pathways in ovarian and endometrial cancer cells in vitro

Abstract

Abstract Previously we have shown that progesterone and calcitriol induce apoptosis of cancer cells. However, the apoptotic mechanisms of the two agents have not been well characterized yet. Herein, we investigated the molecular mechanisms of how progesterone and calcitriol induce apoptosis in cancer cells. DNA fragmentation was upregulated by progesterone and calcitriol in ovarian and endometrial cancer cells. Time-dependent treatment of ovarian cancer cells, ES-2, and TOV-21G with progesterone enhanced caspase -8 activity after 12 h, whereas OV-90, TOV-112D, HEC-1A, and HEC-59 cells showed increased activity after 24h. Caspase 9 activity was increased in all cell lines after 24h treatment with calcitriol. Pretreatment of cancer cells with a caspase-8 inhibitor (z-IETD-fmk) or caspase-9 inhibitor (Z-LEHD-fmk) significantly attenuated progesterone and calcitriol induced caspase-8 and caspase-9 expression, respectively. The expression of FasL, Fas, FAD, and pro-caspase-8, which constitute the death-inducing signaling complex (DISC), was upregulated in progesterone treated cancer cells. Knockdown of FAS or FADD with specific siRNAs significantly blocked progesterone-induced caspase-8. Cleavage of the BID was not affected by caspase-8 activation suggesting the absence of cross-talk between caspase-8 and caspase-9 pathways. Calcitriol treatment decreased mitochondrial membrane potential and increased the release of cancer cytochrome C. These findings indicate that progesterone induces apoptosis through activation of caspase-8 and calcitriol through caspase-9 activation in cancer cells. A combination of progesterone-calcitriol activates both extrinsic and intrinsic apoptotic pathways in cancer cells. Citation Format: Latoya Mcglorthan, Ana Paucarmayta, Yovanni Casablanca, George L. Maxwell, Viqar Syed. Progesterone induces apoptosis by activation of caspase-8 and calcitriol via activation of caspase-9 pathways in ovarian and endometrial cancer cells in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1929.