MicroRNA-195 inhibits the proliferation of human glioma cells by directly targeting cyclin D1 and cyclin E1.

Glioma proliferation is a multistep process during which a sequence of genetic and epigenetic alterations randomly occur to affect the genes controlling cell proliferation, cell death and genetic stability. microRNAs are emerging as important epigenetic modulators of multiple target genes, leading to abnormal cellular signaling involving cellular proliferation in cancers.In the present study, we found that expression of miR-195 was markedly downregulated in glioma cell lines and human primary glioma tissues, compared to normal human astrocytes and matched non-tumor associated tissues. Upregulation of miR-195 dramatically reduced the proliferation of glioma cells. Flow cytometry analysis showed that ectopic expression of miR-195 significantly decreased the percentage of S phase cells and increased the percentage of G1/G0 phase cells. Overexpression of miR-195 dramatically reduced the anchorage-independent growth ability of glioma cells. Furthermore, overexpression of miR-195 downregulated the levels of phosphorylated retinoblastoma (pRb) and proliferating cell nuclear antigen (PCNA) in glioma cells. Conversely, inhibition of miR-195 promoted cell proliferation, increased the percentage of S phase cells, reduced the percentage of G1/G0 phase cells, enhanced anchorage-independent growth ability, upregulated the phosphorylation of pRb and PCNA in glioma cells. Moreover, we show that miR-195 inhibited glioma cell proliferation by downregulating expression of cyclin D1 and cyclin E1, via directly targeting the 3'-untranslated regions (3'-UTR) of cyclin D1 and cyclin E1 mRNA. Taken together, our results suggest that miR-195 plays an important role to inhibit the proliferation of glioma cells, and present a novel mechanism for direct miRNA-mediated suppression of cyclin D1 and cyclin E1 in glioma.

Transgenic tobacco expressed HPV16-L1 and LT-B combined immunization induces strong mucosal and systemic immune responses in mice.

BACKGROUND: Although there are two HPV vaccines have been used to prevent cervical cancer, the cost limits their application in developing countries. The aim of this study was to evaluate the potential value of plant-based HPV16L1 and LTB proteins as a high-efficiency, low-cost and easy-to-use HPV16L1 oral vaccine. RESULTS: Transgenic plant-derived HPV16L1 and LTB were identified, which display potent immunogenicity and biologic activity. Higher levels of specific IgG and IgA levels of HPV16L1 were induced when mice were immunized with L1 combined with LTB by the oral route. The stimulation index (SI) of spleen cells from the L1/LTB-immunized group was significantly higher than that in the L1-immunized group (p < 0.05). The percentage of IFN-γ (+) /IL-4 (+) CD4 (+) T cells from the L1/LTB group was clearly increased compared with that in the L1 and control groups (p < 0.05). METHODS: Plant-expressed HPV16L1 and LTB proteins were extracted from transgenic tobacco leaves, and their biologic characteristics and activity were examined with electron microscopy and GM1-binding assays respectively. Mice were immunized orally with either HPV16L1 or LTB alone or in combination. Induced mucosal and systemic immune responses were detected by ELISA, Hemagglutination inhibition (HAI), lymphocyte proliferation assays and flow cytometry analysis. CONCLUSION: Strong mucosal and systemic immune responses were induced by transgenic tobacco derived HPV16-L1 and LTB combined immunization. This study will lay the foundation for the development of a new type of vaccine to decrease HPV16 infections, which may lead to the prevention of cervical cancer.