| Background/AimsPancreatic cancer is a highly malignant tumor.In the past decades,the treatment of pancreatic cancer has made some progress,but its 5-year overall survival rate is still less than 10%.Postoperative adjuvant chemotherapy such as modified FOLFIRINOX can prolong the postoperative survival of patients with pancreatic cancer,but high-dose chemotherapy has common and serious side effects,and reduces the quality of life of patients.Photodynamic therapy(PDT)is a method of tumor treatment through photosensitizer(PS)and specific wavelength laser.PDT has the advantages of minimally invasive,low mutagenic potential,low systemic toxicity,targeted tumor site to produce therapeutic effect.IR700DX-6T and IR700DX-are two chemically synthesized PS,targeting translocator protein(TSPO)and type 2cannabinoid receptor(CB2R),respectively for PDT of cancer.Recently,we found that IR700DX-6T and IR700DX-mbc94 exhibited high selectivity and efficiency in PDT for breast cancer and malignant astrocytoma.Yet,the phototherapeutic effects of the PS on pancreatic cancer and underlying mechanisms remain unknown.This study investigated the effect of IR700DX-6T-or IR700DX-mbc94-PDT on pancreatic cancer and whether the treatment involves eliciting anticancer immune responses in support of superior therapeutic efficacy.Methods(1)The expressions of TSPO and CB2 R in Panc-1,Panc-2,Miapaca-2,FC1245 cells and pancreatic cancer tissues were detected by Western blot(WB)and immunohistochemistry(HE).(2)In vitro cell experiment was used to observe the inhibitory effect of IR700DX-6T-or IR700DX-mbc94-PDT on the activity of pancreatic cancer FC1245,Panc-2,Miapaca-2 and Panc-1 cells.(3)To verify the PDT effect of IR700DX-6T-or IR700DX-mbc94-PDT on pancreatic cancer FC1245 and Panc-2 cells by detecting intracellular ATP content.(4)The subcellular localization of IR700DX-6T or IR700DX-mbc94 and its target protein in pancreatic cancer cells were observed by fluorescence co localization experiment.(5)By detecting the inhibitory effect of PDT on tumor formation in mice and the rescue experiment of anti-CD8 antibody inhibiting CD8 + T cells,the immunostimulatory effects of IR700DX-6T-or IR700DX-mbc94-PDT on CD8+ T cells in mice were detected by flow cytometry and immunohistochemistry.(6)In vivo,flow cytometry was used to detect the effect of IR700DX-6T-or IR700DX-mbc94-PDT on the maturation of dendritic cells(DCs),and the effect of two kinds of PS mediated PDT on the maturation of bone marrow-derived dendritic cells(BMDCs)was verified in vitro.(7)The inhibitory effect of IR700DX-6T-or IR700DX-mbc94-PDT on regulatory T cells(Tregs)in vivo was detected by flow cytometry and immunohistochemistry.Results(1)The expression of TSPO and CB2 R was up-regulated in pancreatic cancer cells and tissues(P < 0.05).(2)FC1245,Panc-2,Miapaca-2 and Panc-1 cells were treated with different concentrations of IR700DX-6T(0.25,0.50,1.00 and 2.00μM),the inhibition of cell activity was dose-dependent,and the difference was statistically significant(P < 0.05).The inhibitory effect of IR700DX-6T on FC1245,Panc-2,Miapaca-2 and Panc-1 cells peaked at 6,8,10 and 8 h.(3)FC1245,Panc-2,Miapaca-2 and Panc-1 cells were treated with different concentrations of IR700DX-mbc94(0.25,0.50,1.00 and 2.00μM),the inhibition of cell activity was dose-dependent,and the difference was statistically significant(P <0.05).The inhibitory effect of IR700DX-mbc94 on FC1245,Panc-2,Miapaca-2 and Panc-1 cells peaked at 6,6,6 and 4 h.(4)FC1245 and Panc-2 cells were incubated with different concentrations of IR700DX-6T or IR700DX-mbc94(0.25、0.50、1.00 and 2.00μM),the intracellular ATP content was inhibited in a dose-dependent manner(P < 0.05).(5)IR700DX-6T locates in mitochondria and selectively interacts with TSPO in mitochondria.IR700DX-mbc94 targets CB2 R and locates in cell membrane.(6)IR700DX-6T-or IR700DX-mbc94-PDT can significantly induce CD8+ T cells to promote anti-tumor immune response(P < 0.05),and IR700DX-6T has a slightly stronger activation effect on CD8+ T cells than IR700DX-mbc94.(7)IR700DX-6T-or IR700DX-mbc94-PDT can promote the maturation of DCs(P < 0.05).IR700DX-6T-PDT can promote the maturation of DCs more than IR700DX-mbc94.(8)IR700DX-6T-or IR700DX-mbc94-PDT can inhibit Tregs and increase anti-tumor immune response(P < 0.05).IR700DX-6T-PDT has stronger ability to inhibit Tregs.Conclusions(1)The protein levels of TSPO and CB2 R were significantly increased in pancreatic cancer;(2)IR700DX-6T-PDT and IR700DX-mbc94-PDT had significant inhibitory effect on pancreatic cancer;(3)IR700DX-6T-PDT and IR700DX-mbc94-PDT activated anti-tumor immune response,stimulated CD8+ T cells and DCs,and inhibited Tregs;... |
