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Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with Kaposi's sarcoma (KS), the most common AIDS-related malignancy. KSHV vIL-6 promotes KS development, but the exact mechanisms remain unclear. Here, we reported that KSHV vIL-6 enhanced the expression of DNA methyltransferase 1 (DNMT1) in endothelial cells,increased the global genomic DNA methylation, and promoted cell proliferation and migration. And this effect could be blocked by the DNA methyltransferase inhibitor, 5-azadeoxycytidine. We also showed that vIL-6 induced up-regulation of DNMT1 was dependent on STAT3 activation. Therefore, the present study suggests that vIL-6 plays a role in KS tumorigenesis partly by activating DNMT1 and inducing aberrant DNA methylation, and it might be a potential target for KS therapy.

Tumor survival is significantly correlated with the immune response of patients. IFNG plays an important role in the tumor host response and decreased IFNG expression is often observed in lung cancer. Studies have shown that CpG island hypermethylation plays a critical role in transcriptional silencing of IFNG gene expression. However, there is limited understanding regarding the molecular mechanisms of altered methylation, and whether the tumor microenvironment has any effect on DNA methylation and IFNG production. In the current study, we demonstrate that plasma and intra-cellular IFNG levels are significantly lower in lung cancer patients. Hypermethylation of the IFNG promoter in CD4(+) T cells and plasma IFNG was negatively correlated. CD4(+) T cells from healthy individuals co-cultured with SPC-A1 cells generated lower levels of IFNG after activation, elevated expression of DNA methyltransferases (DNMTs), and exhibited hypermethylation of the IFNG promoter. In conclusion, decreased IFNG expression of CD4(+) T cells co-cultured with lung cancer cell is associated with IFNG promoter hypermethylation. Our study suggests that interaction between lung cancer cells and CD4(+) T cells induces DNMT expression and IFNG promoter hypermethylation in CD4(+) T cell, which may serve as an important mechanism of tumor-induced immunosuppression.

Monoclonal antibody (McAb) is the key tool for cancer immunodiagnosis and immunotherapy. McAb-based immunotherapy that targets tumor antigens has had great achivement. In this study, a cell clone which kept secreting high-titer IgG1-type McAb named NJ001 against human non-small cell lung cancer (NSCLC) cells was obtained. The titer of purified NJ001 was 2×10(6). The antigen named SP70 of NSCLC specifically identified by NJ001 was proved to be a protein with the relative molecular mass (Mr) of 70 kDa. The results of immunohistochemical staining indicated that NJ001 could positively react to NSCLC, but weak positively or negatively react to human small-cell lung cancer (SCLC), pulmonary pseudotumor and other epithelial tumors. In soft agar assay, the colony formation efficiency in NJ001 groups decreased in a dose-dependent manner. For the concentration of 100 µg/ml, 200 µg/ml and 400 µg/ml, the inhibition ratio of colony formation was 23.4%, 62.5% and 100% respectively. Meanwhile, NJ001 caused significant reduction in tumor volume and tumor weight compared to control mice in lung cancer xenograft model. The tumor growth inhibition ratio in 200 µg, 400 µg and 800 µg NJ001 groups was 10.44%, 37.29% and 44.04%, respectively. NJ001 also led to cytomorphological changes and induced the apoptosis of human lung adenocarcinoma cell line SPC-A1 significantly. The newly developed NJ001 selectively reacted to NSCLC and exhibited anti-tumor activity both in vitro and in vivo. NJ001 is of great value concerning immunodiagnostics and immunotherapy for NSCLC and holds promise for further research regarding the mechanism underlying tumor progression of NSCLC.