Aquaporin 3 Promotes Gastric Cancer Resistance To Cisplatin By Enhancing Autophagy

Background:Gastric carcinoma(GC)remains one of the most common and lethal malignancies worldwide,especially in China.Despite the development of new therapeutic strategies in recent decades,radical surgery and platinum-based chemotherapy are still the standard treatments for GC,and cisplatin(cis-diamminedichloroplatinum,cDDP)is one of the first-line chemotherapeutic agents for GC.Cisplatin exerts its cytotoxic effect predominantly by forming intra-strand cross-links in DNA that block transcription and DNA replication,resulting in cell apoptosis.However,resistance to cDDP in GC is increasing,which leads to a major limitation in its clinical application.Mechanisms of cDDP resistance are complicated,including decreased drug uptake,increased drug efflux,increased DNA damage repair,alterations in apoptotic signaling pathways and induced autophagy.Understanding the mechanism of cDDP resistance is crucial for GC therapy.Aquaporins(AQPs)are a family of small,integral membrane proteins that facilitate water transport across the plasma membranes of cells in response to osmotic gradients,and in some cases AQPs can transport glycerol("aquaglyceroporins").AQP3 is a member of the aquaglyceroporin family that has been recently been found to transport H2O2.Mounting evidence further implicates AQPs in promoting cancer cell migration and proliferation,adding AQPs to an expanding list of effectors in tumor biology.Our previous study demonstrated that AQP3 is overexpressed in GC tissues,that its expression is associated with histological classification,lymph node metastasis,and lymphovascular invasion,and that the up-regulation of AQP3 promotes the invasion and metastasis of GC cells via promoting the epithelial-mesenchymal transition(EMT)and the stem-like properties of gastric cancer cells.Autophagy is a catabolic process whereby intracellular components and organelles are enveloped in double-membraned vesicles,and then transported to fuse with the lysosomal where the contents are degraded and recycled into the cytosol.Autophagy is a common phenomenon in physiological conditions and pathological conditions.Not only involved in maintaining cell homeostasis,but also the occurrence and development of tumors and tumor resistance is closely related.Although AQP3 overexpression has been demonstrated to contribute to chemoresistance in melanoma to arsenite,little is known about the role of AQP3 in chemosensitivity of GC to cytotoxic agents.It will provide theoretical basis and experiment for AQP3 as the target of gastric cancer treatment.Methods:1.The human gastric carcinoma cell lines,MGC803,SGC7901 and AGS were enrolled in this study.Cells were constructed by lentiviral transfection to up-regulate and down-regulate AQP3(marked with MGC803-AQP30low,SGC7901-AQP30low,AGS-AQP3high).2.After treated with cDDP or CQ,CCK-8 assays were to test proliferation of GC cells.3.Western blotting assays were used to evaluate the change of AQP3 expression in the human GC cell lines after co-culture with cDDP.Autophagy related proteins were tested by immunofluorescence and western blotting.Results:1.AQP3 overexpression induced cDDP resistance in AGS cells,and AQP3 knockdown increased the chemosensitivity of MGC803 and SGC7901 cells.2.Up-regulate AQP3 increase autophagy in AGS cells,and down-regulate AQP3 weaken autophagy level of MGC803 and SGC7901 cells.3.Chloroquine increases the sensitivity of GC cells to cDDP and reverses AQP3-induced chemoresistance.Conclusions:AQP3 facilitates cisplatin resistance in gastric cancer cells via autophagy,and suggest that the development of AQP3-based tumor therapeutics could play a key role in future GC treatment strategies.