Non-viral Vector-mediated Selective Gene Delivery To Pancreatic Stellate Cells Enables Effective Therapy For Pancreatic Cancer

Pancreatic cancer is one of the most lethal malignancies with a 5-year survival rate below 8%.Activated pancreatic stellate cells(PSCs)account for the major component in pancreatic tumor microenvironment.It has been proven that PSCs contribute to cancer progression and metastases.More importantly,dense stroma containing plentiful PSCs impedes the delivery of therapeutics and increases the therapy difficulty for pancreatic cancer.In addition,the elimination of PSCs results in immunosuppression and further accelerates tumor metastases.Therefore,it's important to keep the PSCs undamaged during the treatment of pancreatic cancer.Gene therapy requires the effective delivery of therapeutic genes to target cells or tissues.Nonviral gene vectors have been extensively studied in cancer research areas because of safety,biocompatibility and low immunogenicity.However,compared to viral vevtors,.the transfection efficiency of nonviral vectors is cell line-dependent and relatively lower.TRAIL(TNF-related apoptosis inducing ligand)is a member of TNF superfamily.The tumor cell specific apoptotic induction and the bystander effect of TRAIL have been well characterized.Considering the characteristics of pancreatic tumor microenvironment,we demonstrate the concept of delivering TRAIL gene to PSCs for pancratic cancer therapy.We propose that trail proteins expressed by PSCs could result in the apoptosis of nearby cancer cells without significant cytotoxicity to PSCs.Pancreatic cancer cells can hardly be transfected by nonviral vectors.used in our experiments.PSCs could be efficiently transfected by BPEI(Branched PEI,25KDa).The PSCs specific transfection was also observed in the coculture model.Later we cocultured PSCs with BxPC-3 cells or SW1990 cells,then they were transfected with pEGFP-TRAIL.PSCs expressed GFP effectively and grew normally,PI-positive staining of cancer cells showed trail protein expressed by PSCs induced the apoptosis of surrounding cancer cells.For antitumor experiment,we established an orthotropic nude model of human pancreatic cancer containing BxPC-3 cells and PSCs,y-PGA was coated on the surface of polyplex(BPEI/DNA)to lower systemic toxicity and improve therapeutic effect.In conclusion,utilizing BPEI mediated selective high transfection efficiency on PSCs,we successfully transfected TRAIL gene to PSCs.It has been observed that the nearby pancreatic cancer cells were killed by trail proteins expressed by PSCs,which were enriched in pancreatic tumor microenvironment.This strategy could not only overcome the poor penetration problems of chemodrugs,but also provides a novel therapy for pancreatic cancer,which selectively induces the death of cancer cells.