Fas and Fas ligand expression in pancreatic adenocarcinoma

Fas-threshold signalling in MSCs promotes pancreatic cancer progression and metastasis

Mesenchymal stem cells (MSCs) belong to the tumour microenvironment and have been implicated in tumour progression. We found that the number of MSCs significantly increased in tumour-burdened mice driven by Fas-threshold signalling. Consequently, MSCs lacking Fas lost their ability to induce metastasis development in a pancreatic cancer model. Mixing of MSCs with pancreatic cancer cells led to sustained production of the pro-metastatic cytokines CCL2 and IL6 by the stem cells. The levels of these cytokines were dependent on the number of MSCs, linking Fas-mediated MSC-proliferation to their capacity to promote tumour progression. Furthermore, we discovered that CCL2 and IL6 were induced by pancreatic cancer cell-derived IL1. Importantly, analysis of patient transcriptomic data revealed that high FasL expression correlates with high levels of MSC markers as well as increased IL6 and CCL2 levels in pancreatic tumours. Moreover, both FasL and CCL2 are linked to elevated levels of markers specific for monocytes known to possess further pro-metastatic activities. These results confirm our experimental findings of a FasL-MSC-IL1-CCL2/IL6 axis in pancreatic cancer and highlights the role of MSCs in tumour progression.

Obstacles Posed by the Tumor Microenvironment to T cell Activity: A Case for Synergistic Therapies

T cell dysfunction in solid tumors results from multiple mechanisms. Altered signaling pathways in tumor cells help produce a suppressive tumor microenvironment enriched for inhibitory cells, posing a major obstacle for cancer immunity. Metabolic constraints to cell function and survival shape tumor progression and immune cell function. In the face of persistent antigen, chronic T cell receptor signaling drives T lymphocytes to a functionally exhausted state. Here we discuss how the tumor and its microenvironment influences T cell trafficking and function with a focus on melanoma, and pancreatic and ovarian cancer, and discuss how scientific advances may help overcome these hurdles.

Effect of arsenic trioxide on pancreatic carcinoma cell line PC-3 in vitro

AIM: To explore the biological effect of arsenic trioxide (As₂O₃) on human pancreatic carcinoma cell line PC-3 and its mechanism.

METHODS: MTT assay was used to observe the inhibitory actions of As₂O₃ on PC-3 cells at various concentrations. The apoptotic rate and growth cycle of the cells were detected by flow cytometry. The changes of the cells ultrastructures were observed under electron microscope. The expression of apoptosis-related gene protein (Fas, Fas-L, Bcl-2, Bax) was detected by immunohistochemical staining.

RESULTS: As₂O₃ inhibited the proliferation of PC-3 cells in a concentration- and time-dependent manner. Marked apoptosis peak was observed and the cells were mainly blocked in S phase (14.86-63.66%). PC-3 cells showed obvious feature of apoptosis under electron microscope, such as intact cell membrane, pyknosis of chromatin, nuclear fragmentation and apoptotic body formation. Bcl-2 protein was weakly expressed (+++) in controls, but strongly expressed (+) in As₂O₃-treated cells. Fas-L protein were weakly (+) and negatively (-) expressed in controls respectively, but strongly expressed (+++) in As₂O₃-treated cells.

CONCLUSION: As₂O₃ can inhibit the proliferation and induce the apoptosis of human pancreatic carcinoma cell PC-3 and the mechanism is probably related to its effect on the regulation of Fas, Fas-L and Bcl-2 expression.

Expression of Fas and p53 in different stages of large intestinal malignant transformation and their association with apoptosis

AIM: To explore the expression of Fas and p53 in the large intestinal adenocarcinoma, malignantly transformed adenoma, tubulo-villous adenoma, and tubular adenoma, and to assess their influence on the pathogenesis of large intestinal carcinoma.

METHODS: Using in-situ hybridization, immunohistochemistry and TUNEL techniques, we examined a number of paraffin-embedded tissues including 37 cases of large intestinal adenocarcinomas, 26 cases of malignantly transformed adenomas, 30 cases of tubulo-villous adenomas, and 24 cases of tubular adenomas for Fas mRNA, p53 protein and DNA fregment. 6 cases of non-tumor mucosa were used as control group.

RESULTS: Fas mRNA positive cell density was: 39.60±6.51 in non-tumor mucosa, 50.93 21.64 in tubular adenoma, 45.91±24.15 in tubulo-villous adenoma, 25.47±14.76 in non-malignantly transformed area of adenoma, 11.92±9.47 in malignantly transformed area of adenoma, and 5.88±5.10 in adenocarcinoma, which was significantly lower in the malignant lesions than in adenomas (P <0.001). p53 protein positive cell density was: 8.40±2.67 in non-tumor mucosa, tubular adenoma 13.19±8.95, tubulo-villous adenoma 13.50±7.29, non-malignantly transformed area of adenoma 12.24±7.16, malignantly transformed area of adenoma 73.31±28.57, adenocarcinoma 80.99±44.54, among which it was the lowest in the non-tumor mucosa, slightly increased in adenoma, and significantly increased in malignant lesions (P <0.001). Apoptotic cell density was: non-tumor mucosa 15.02±11.14, tubular adenoma 46.31±18.86, tubulo-villous adenoma 29.43±16.66, non-malignantly transformed area of adenoma 68.42±19.61, malignantly transformed area of adenoma 22.01±12.07, adenocarcinoma 18.64±12.88, which was higher in adenomas, but lower in malignant lesions (P <0.001). The positively expressed cell density of p53 protein was reversely related with that of the apoptotic epithelial cells (r = -0.389, P <0.001). The positively expressed cell density of Fas mRNA was related with that of the apoptotic epithelial cells (r = 0.190, P <0.05).

CONCLUSION: The apoptotic cell death is inhibited via downregulation of Fas expression and upregulation of p53 expression in large intestinal adenocarcinoma, and a so-called "Fas resistance" mechanism is induced.

A comprehensive in vitro characterization of pancreatic ductal carcinoma cell line biological behavior and its correlation with the structural and genetic profile

There are a large number of stable pancreatic ductal carcinoma cell lines (PDCL) that are used by researchers worldwide. Detailed data about their differentiation status and genetic alterations are present in the literature, but a systematic correlation with cell biological behavior is often lacking. PDCL ( n=12) were clustered by source of tumor cell (ascites, primary tumor, metastasis), and the data of functional cell biology were correlated with the reported structural and genetic profiles. Major histocompatibility complex expression, chemosensitivity and aneuploidia appeared to be related to the source of PDCL, and proliferative capacity appeared to be related to the grade of differentiation. No correlation between genetic/structural features of PDCL and biological behavior was found. All the cell lines appeared generally insensitive to in vitro treatment with 5-fluorouracil and showed variable degrees of susceptibility to gemcitabine, raltitrexed and oxaliplatin. All the PDCL showed resistance to Fas-mediated apoptosis but were significantly sensitive to the pro-apoptotic effect of inflammatory cytokines [interleukin (IL)-1beta, tumor necrosis factor (TNF)alpha and interferon gamma]. PDCL were characterized for the secretion of several factors relevant to the tumor-immune cross talk. Vascular endothelial growth factor, CCL2, CCL5 and transforming growth factor beta were the factors most frequently released; less frequent was the secretion of CXCL8, CCL22, IL-6 and sporadically CXCL12, IL-10 and hepatocyte growth factor. The cytokines IL-1beta and TNFalpha were always undetectable. In conclusion, a clear correlation between structural/genetic features and function could not be detected, suggesting the weakness of a "morphological" classification for the in vitro studies of pancreatic cancer.

Development of immunotherapy for pancreatic cancer

: Human tumor antigens recognized by T cells have been recently identified in various cancers, including pancreatic cancer. With the identified antigens, new immunotherapies can be developed using more efficient immunologic intervention (due to sufficient amounts of antigens in a more immunogenic form), as well as more quantitative and qualitative immunomonitoring. Various immunotherapies for patients with various cancers, including pancreatic cancer, are currently under evaluation in clinical trials. These include adoptive transfer of tumor reactive T cells and LAK cells; nonmyeloablative stem cell transplantation; active immunization with the identified tumor antigens, various tumor-derived products, dendritic cells pulsed with tumor antigens, and gene-modified tumor cells. Although these efforts in the realm of pancreatic cancer are still limited, various groups in Japan continue to be actively involved in this field of research.