A novel immunocytolytic factor secreted by pancreatic adenocarcinoma

Polyethyleneimine modification of aluminum hydroxide nanoparticle enhances antigen transportation and cross-presentation of dendritic cells

Background

The aim of this study was to explore the feasibility of delivering tumor antigens and enhancing the antigen cross-presentation of dendritic cells (DCs) by aluminum hydroxide nanoparticle with polyethyleneimine (PEI) modification (LV@HPA/PEI).

Materials and methods

The LV@HPA nanoparticles were modified by PEI first, then the influence of LV@HPA/PEI on DCs was examined. The distinct expression of ovalbumin (OVA) protein transported into DCs by LV@HPA/PEI was observed by flow cytometry and Western blot. The biocompatibility of LV@HPA/PEI, maturity and antigen cross-presentation of DCs was observed in vitro. Tumor derived autophagosomes (DRibbles) combined with LV@HPA/PEI were loaded into DCs, and DC vaccines were used to immunize mice. The percentage of CD3⁺CD8⁺IFN-γ⁺ T cells in immunized mice was determined by flow cytometry. Additionally, the functional properties of the LV@HPA/PEI-DRibble-DCs vaccine were examined in vivo in PancO2 tumor-bearing mice.

Results

In our study, we described how LV@HPA/PEI can be a functionalized antigen delivery system with notable antigen transport effect and negligible cytotoxicity. It was found that LV@HPA/PEI could be easily internalized into DCs to assist antigen release into the cytoplasm. In addition, DCs matured gradually after loading with LV@HPA/PEI-OVA, which increased significantly the cytokine IL-12 secretion and expression of surface molecules CD80 and CD86. Interestingly, DCs loaded with LV@HPA/PEI-DRibbles could promote the activation of tumor-specific T cells both in murine and in human T cells. In the following in vivo experiments, the vaccine of LV@HPA/PEI-DRibble-DCs significantly inhibited tumor growth and improved the survival rate of the PancO2 tumor-bearing mice.

Conclusion

We established a high-performance anti-tumor vaccine of DCs loaded with LV@ HPA/PEI nanoparticles and tumor-associated antigens in autophagosomes (DRibbles), which could serve as a therapeutic strategy in cancer immunotherapy.

Fas and Fas ligand expression in pancreatic adenocarcinoma

INTRODUCTION

Fas and Fas ligand (FasL) mediate apoptosis of tumor cells in immune surveillance, and expression of FasL by tumors may mediate their counterattack on cytotoxic lymphocytes. Both proteins are expressed in most if not all pancreatic carcinoma cell lines, but their study in primary human tumors has been limited.

AIM

We performed Fas and FasL immunohistochemical staining on 81 primary pancreaticobiliary or ampullary ductal adenocarcinomas of patients in our institutional database to determine the extent and strength of staining.

METHODOLOGY

The expression of Fas and FasL was compared with regard to clinicopathologic variables, K- mutations, and immunoexpression of HER2, p21, p27, and p53.

RESULTS AND CONCLUSION

Fas was expressed in 19% of patients with strong or intermediate intensity but with variable percentages of tumor cell staining. FasL was expressed in 49% of patients, usually with diffuse expression but variable intensity. Fas expression was more common in women than men, as women had 93% of Fas-positive tumors but only 55% of Fas-negative tumors ( = 0.007), and was associated with strong HER2 expression (67% of Fas-positive versus 18% of Fas-negative patients; = 0.04). Fas expression tended to be less common in blacks (4% had Fas-positive tumors) than whites (22% had Fas-positive tumors; = 0.052). FasL expression tended to be associated with stage 4 disease at diagnosis (24% versus 0%; = 0.07). Neither Fas expression nor FasL expression was associated with survival, a circumstance suggesting that their role, if any, in contributing to the aggressiveness of these tumors is complex.