Abstract 3086: Cyclopamine tartrate, an anti-cancer agent targeting Hedgehog signaling, strongly interferes with mitochondrial function and suppresses aerobic respiration

Abstract

Abstract The Hedgehog (Hh) pathway is a major regulator of many fundamental processes in mammalian embryonic development. These processes include stem cell maintenance, determination of cell fate, tissue polarity, cell survival, cell differentiation and proliferation. Although this pathway is usually silenced in adult tissues, constitutive activation of the Hh pathway can lead to tumorigenesis. This aberrant characteristic can be observed in different types of human cancer including basal cell carcinomas, medulloblastoma, lung cancer, ovarian cancer, gastrointestinal cancer, breast and prostate cancer. This pathway has been shown to regulate proliferation of cancer stem cells and increase tumor invasiveness. Targeted inhibition of Hh signaling pathway is shown to be effective in cancer treatment and prevention. Therefore, the discovery of Hh pathway inhibitors can pave the way of finding effective cancer treatments. The steroidal alkaloid cyclopamine was the first compound found to inhibit Hh signaling and has been invaluable for understanding the function of Hh signaling in development and cancer. Cyclopamine tartrate (CycT) is an improved analogue of cyclopamine with increased water solubility and bioavailabilty. We performed numerous experiments to examine the effect of CycT in inhibiting Hh signaling on an array of non-small-cell lung cancer (NSCLC) lines. We discovered that CycT has a novel activity in disrupting mitochondrial function and aerobic respiration. Our data show that CycT causes a substantial decrease in aerobic respiration of NSCLC cells, similar to the effect of glutamine deprivation. Mitotracker staining showed that CycT causes mitochondrial fragmentation by increasing mitochondrial fission, which is indicated by the localization of DRP1 at fission sites. Further experiments showed that CycT increases ROS generation, which is presumably a consequence of mitochondrial hyperpolarization. Concomitantly, CycT causes apoptosis and suppress proliferation of NSCLC cells. Citation Format: Md Maksudul Alam, Sagar Sohoni, Sarada Preeta Kalainayakan, Massoud Garrossian, Li Zhang. Cyclopamine tartrate, an anti-cancer agent targeting Hedgehog signaling, strongly interferes with mitochondrial function and suppresses aerobic respiration. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3086.