Orai3 orchestrates gemcitabine resistance in pancreatic cancer via NFATc1-SLIT3 axis

Pancreatic Cancer (PC) is one of the most aggressive cancers and is associated with poor prognosis. Gemcitabine is the first-line chemotherapy for PC. While gemcitabine-based regimes offer survival benefits, the acquired gemcitabine resistance leads to reoccurrence, metastasis and the long-term survival rate remains dismal. Although there is substantial clinical evidence for gemcitabine resistance, the cellular and molecular mechanisms driving gemcitabine resistance remain largely unappreciated. Here, we reveal that Orai3, a Ca2+ selective channel, is a crucial driver of gemcitabine resistance. We demonstrate that Orai3 is upregulated in gemcitabine-resistant PC cells. Orai3 silencing in these cells decreases proliferation, induces cell cycle arrest, enhances apoptosis, and moderates stemness characteristics. Notably, studies in zebrafish model corroborate the significance of Orai3 in gemcitabine resistance in vivo. Mechanistically, our unbiased RNA-seq analysis coupled with robust functional studies show that SLIT3 works downstream of Orai3 to drive gemcitabine resistance. Finally, we report that NFATc1 transcription factor bridges Orai3 to SLIT3 transcription. Taken together, this study identifies Orai3 as a key orchestrator of gemcitabine resistance and uncovers a unique Orai3-NFATc1-SLIT3 signaling module that drives chemoresistance. Hence, this work reveals Orai3 as a promising target for synergistic therapeutic approach to combat chemoresistance.