Validating the role of PTGIS gene in colorectal cancer by bioinformatics analysis and in vitro experiments.

Prostaglandin I2 synthase (PTGIS) is a member of the cytochrome P450 family. Studies have revealed that differential expression of the PTGIS gene is closely related to the pathological and physiological processes of many diseases, including breast cancer, oral squamous cell carcinoma, and head and neck cancer. However, the mechanism of action of the PTGIS gene in colorectal cancer is not fully understood. This study explored the role of PTGIS in colorectal cancer through comprehensive bioinformatics analysis and in vitro experiments, and found that the expression of PTGIS gene in colorectal cancer tissue was significantly lower than that in normal colorectal tissue (P < 0.05), and high expression of PTGIS gene was associated with poor prognosis in patients (P < 0.05). The KEGG results showed that PTGIS-related genes were mainly enriched in metabolic pathways, arachidonic acid metabolism, steroid biosynthesis, and cancer pathways. The expression of PTGIS may be related to immune infiltration. Cell experiments showed that PTGIS was expressed at a lower level in cancer. Overexpression of PTGIS inhibited apoptosis and promoted proliferation, invasion, and migration ability of SW480 colorectal cancer cells. Analysis of the PTGIS gene in this study provides a theoretical basis for further exploring the pathogenesis of colorectal cancer and finding more accurate new targets for early screening and treatment of the cancer.

CTLA4-Ig-modified dendritic cells inhibit lymphocyte-mediated alloimmune responses and prolong the islet graft survival in mice.

The induction of antigen specific tolerance is critical for prevention and treatment of allograft rejection. In this study, we transfected CTLA4-Ig gene into dendritic cells (DCs), and investigated their effect on inhibition of lymphocyte activity in vitro and induction of immune tolerance on pancreatic islet allograft in mice. An IDDM C57BL/6 murine model induced by streptozotocin is as model mouse. The model mice were transplanted of the islet cells isolated from the BALB/c mice to their kidney capsules, and injected of CTLA4-Ig modified DCs (mDCs). The results showed that mDCs could significantly inhibit T lymphocyte proliferation and induce its apoptosis; whereas, unmodified DCs (umDCs) promoted the murine lymphocyte proliferation. Compared with injection of umDCs and IgG1 modified DCs, the injection of mDCs prolonged IDDM mice's allograft survival, and normalized their plasma glucose (PG) levels within 3 days and maintained over 2 weeks. The level of IFN-gamma was lower and the level of IL-4 was higher in mDCs treated recipient mice than that in control mice, it indicated that mDCs led to Th1/Th2 deviation. After 7 days of islet transplantation, HE stain of the renal specimens showed that the islets and kidneys were intact in structure, and islet cells numbers are increased in mDCs treated mice. Our studies suggest that DCs expressing CTLA4-Ig fusion protein can induce the immune tolerance to islet graft and prolong the allograft survival through the inhibition of T cell proliferation in allogeneic mice.

[The effect of CTLA4Ig-modified dendritic cells on proliferation and cytotoxicity of lymphocytes in-vitro].

AIM: To study the effect of dendritic cells (DCs) modified by CTLA4Ig on T-cell proliferation and the cytotoxic T lymphocyte killer activity. METHODS: The expressing vector pG/CTLA4Ig was transfected into DCs via lipofectamine reagent mediation. CTLA4Ig fusion protein secreted by DCs in the culture supernatant was confirmed by sandwich ELISA and SDS-PAGE. Peripheral blood mononuclear cells (PBMC) from C57BL/6 mice (as reaction cells) and DCs modified or unmodified by CTLA4Ig (as stimulation cells) were co-cultured for 6 days. MTT colorimetry was used to detect lymphocyte proliferation. Lactate dehydrogenase release method and sandwich ELISA assay was used to examine the cytotoxic activity and T-cell apoptosis. RESULTS: CTLA4Ig fusion protein and DCs modified by CTLA4Ig could significantly inhibit lymphocyte proliferation response and cytotoxic activity of specific cytotoxic T lymphocytes, and induce T-cell apoptosis, while unmodified-DCs could markedly induce lymphocyte proliferation response. CONCLUSION: The DCs of stably expressing CTLA4Ig fusion protein could not only markedly inhibit T-cell proliferation and cytotoxic activity of CTL, but also induce T-cell apoptosis.

The immunotherapeutic effect of dendritic cells vaccine modified with interleukin-18 gene and tumor cell lysate on mice with pancreatic carcinoma.

AIM: To estimate the effect of a therapeutic vaccine against pancreatic carcinoma based on dendritic cell (DC) vaccine modified with tumor lysate and Interleukin-18 gene. METHODS: The BALB/C mice model of pancreatic carcinoma was induced with DMBA. DC vaccine was constructed through pulsed with tumor lysate and transfected by the recombinant adenoviral vector encoding IL-18 gene. The immunotherapeutic effects of DC vaccine on mice with pancreatic carcinoma were assessed (divided into DC-IL18-Lysate group, DC-Lysate group, DC-IL18 group, DC group, PBS group). RESULTS: After vaccination of the DC vaccine, the concentration of IL-18 and IFN-gamma were 2161+/-439 ng x L(-1) and 435+/-72 ng x L(-1) in DC-IL18-Lysate group and there was significant difference compared with other groups (P<0.01). After vaccination of the DC vaccine, the transplanted tumors were observed on 30 days in DC-Lysate groups, on 16 days in DC-IL18 groups, on 3 days in control group, but mice remained tumor-free for at least 50 days in DC-IL18-Lysate group and there was significant difference between DC-IL18-Lysate group and other groups (P<0.01). The median survival exceeds 62 days in DC-IL18-Lysate group. But the median survival was 48.6 days in DC-Lysate group, 33 days in DC-IL18 group, 17 days in PBS group. The survival period was obviously prolonged in DC-IL18-Lysate group than in other groups (P<0.05, P<0.01). The weight of pancreatic tumor was 0.22+/-0.083 g in DC-IL18-Lysate group, 1.45+/-0.74 g in DC-Lysate group, 1.89+/-1.34 g in DC-IL18 group, 3.0+/-1.6 g in DC group, 2.9+/-2.0 g in PBS group and the weight of tumor obviously reduced in DC-IL18-Lysate group than in other groups (P<0.05, P<0.01). CONCLUSION: DC vaccine modified with tumor lysate and Interleukin-18 gene can induce a specific and effective immune response against pancreatic carcinoma cell.