The Function And Regulation Mechanism Of SDF2L1 In The Chemoresistance Of Pancreatic Cancer

Background Pancreatic cancer has extremely high malignancy and poor prognosis,with a 5year survival rate of less than 10%.Chemoresistance is a major obstacle from prognosis improvement.RNA sequencing of PDX model suggested that SDF2L1 was associated with resistance to gemcitabine.Localizing in the endoplasmic reticulum,SDF2L1 is involved in recognizing misfolded proteins and initiating UPR in response to environmental stimuli such as hypoxia and lack of nutrition supply.Most studies of SDF2L1 focus on diseases caused by chronic endoplasmic reticulum stress,such as chronic lung disease,fatty liver and pathological pregnancy.The role of SDF2L1 in pancreatic cancer chemoresistance remains unclear.Objectives To investigate the clinical relevance of SDF2L1 expression in pancreatic cancer.To study the effect of SDF2L1 on chemoresistance,proliferation,colony formation and migration ability of pancreatic cancer cells.To explore the molecular mechanism of SDF2L1-mediated chemoresistance in pancreatic cancer.We aim to provide a new perspective to decipher the mechanism of chemoresistance in pancreatic cancer,which might shed light on new therapeutic targets and novel treatment.Methods Firstly,expression of SDF2L1 in pancreatic cancer was detected by immunohistochemical staining.Expression of SDF2L1 in different cell lines was detected by RT-qPCR and Western Blot.Secondly,siRNA,plasmid and lentivirus were constructed to interfere the expression of SDF2L1 in pancreatic cancer cells.Effects of knockdown or overexpression of SDF2L1 on drug resistance,proliferation and migration ability of pancreatic cancer cells were investigated by CCK-8 method,colony formation assay,scratch healing assay and Transwell assay.The effects of SDF2L1 overexpression on pancreatic cancer growth and chemoresistance were validated in vivo with subcutaneous transplantation model in nude mice.Further,RT-qPCR and Western Blot were applied to explore the regulation of SDF2L1 on UPR and potential downstream pathways.Rescue experiments were conducted by deleting endoplasmic reticulum localization sequence of SDF2L1 and introducing UPR inhibitor HA 15.Results Immunohistochemical staining results suggested that expression of SDF2L1 was significantly higher in pancreatic cancer than paraneoplastic tissues.Expression of SDF2L1 was also found to be correlated with poor prognosis.RT-qPCR and Western Blot indicated that expression of SDF2L1 was higher in gemcitabine resistant cell lines than in wild-type cell lines.Gemcitabine could induce an increase in SDF2L1 expression in pancreatic cancer cells.Subsequent studies demonstrated that knockdown of SDF2L1 reduced drug resistance,proliferation and migration ability of pancreatic cancer cells,while overexpression of SDF2LI enhanced drug resistance and migration ability.Overexpression of SDF2L1 was also found to be associated with lower tumor growth inhibition of gemcitabine in vivo.Further studies revealed that SDF2L1 activated UPR pathway,NF-κB pathway and EMT pathway,and downregulated autophagy pathway.The introduction of UPR inhibitor or deletion of endoplasmic reticulum localization sequence of SDF2L1 reversed these regulations,thus deprived pancreatic cancer cells of SDF2L1-related chemoresistance.Conclusion Expression of SDF2L1 in pancreatic cancer is higher than paraneoplastic tissues and is associated with poor prognosis.Gemcitabine induces an increase in SDF2L1 expression in pancreatic cancer cells.SDF2L1 leads to chemoresistance in pancreatic cancer by localizing to the endoplasmic reticulum,initiating the UPR,inhibiting autophagy and activating the NF-κB and EMT pathways.