SMDT1-driven change in mitochondrial dynamics mediate cell apoptosis in PDAC

Mitochondrial Ca²⁺ uptake, an important governing for Ca²⁺ homeostasis, is catalyzed by the mitochondrial calcium uniporter (MCU) complex. SMDT1, as a subunit of MCU complex, was essential for bridging the calcium-sensing role of MICU1 and MICU2 with the calcium-conducting role of MCU. However, the molecular mechanism and regulatory purpose of SMDT1 remain largely unexplored, especially no study was reported in cancer. Here, we firstly reported that how SMDT1 exerted its role through mediating mitochondrial dynamic in PDAC malignancy. In this study, by screening online of subunit of MCU complex, we confirmed that SMDT1 expression was significantly positive correlated with PDAC prognosis. The GEO datasets showed decreased SMDT1 expression in PDAC tumor compared with non-tumor tissues. SMDT1 overexpression could notably inhibit cell proliferation and induce cell apoptosis. Further analysis demonstrated that up-regulated SMDT1 in ASPC1 and Canpan1 cells led to increased accumulation of pro apoptotic protein BAX and decrease in anti-apoptotic proteins Bcl-2 and Bclx. And more releasing of cytochrome c located in cytosolic. Mechanistically, in the morphological analysis of mitochondria, more fragmented mitochondria were presented in SMDT1 overexpression cells by promting the phosphorylation of Drp1, increasing Fis and decreasing MFN1. Meanwhile, more Drp1 was translocated on the mitochondrial from the cytoplasm in up-regulated SMDT1 cells. On the basis of the evidence above we deduce that SMDT1-driven change in mitochondrial dynamics mediated cells apoptosis in PDAC. And, SMDT1 could serve as an important therapeutic target to normalize mitochondrial dynamic responsible for poor prognosis in PDAC.