[Show abstract][Hide abstract] ABSTRACT: MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression by either translational inhibition or mRNA degradation. miRNAs play pivotal roles in physiological functioning and pathological progression. The function of microRNA-99a (miR-99a) in oral squamous cell carcinoma (OSCC) remains unclear. In the present study, we investigated the roles of miR-99a in OSCC development and the underlying mechanisms in 25 cases of primary OSCC tissues and Tca-8113 cells. The cells were analyzed using FACS analysis and western blotting. Results showed that the expression levels of miR-99a were markedly decreased in OSCC tissues compared with the adjacent non-tumor tissues (n=25). The results of in vitro experiments showed that miR-99a mimics significantly inhibited the proliferation of Tca-8113 cells, a tongue squamous carcinoma cell line, and that miR-99a mimics markedly induced the apoptosis of Tca-8113 cells. Furthermore, we demonstrated that mammalian target of rapamycin (mTOR) was directly targeted by miR-99a, as the overexpression of miR-99a in Tca-8113 cells downregulated the protein expression level of mTOR. Thus, our findings suggest that the downregulation of miR-99a in OSCC tissues is associated with tumor development. miR-99a regulates the growth and survival of OSCC cells and may be exploited as a biomarker and therapeutic target for patients with OSCC.
Preview · Article · Jun 2012 · Molecular Medicine Reports
[Show abstract][Hide abstract] ABSTRACT: It has been reported that treatment with cyclophosphamide (CTX) as a chemotherapeutic drug in cancer patients or tumor-bearing mice can result in an increase in the proportion of myeloid derived suppressor cells (MDSCs) in blood and lymphoid organs. Here we sought to clarify the possible mechanism of this unwanted increase in proportion of MDSCs in tumor-bearing mice after CTX treatment. We found that both CD4(+) T cells and CD8(+) T cells underwent an expansion and activation before the increase of MDSCs in the early period of CTX treatment in 4T1 breast tumor-bearing mice. The proportion of MDSCs in nude mice lacking T cells after CTX therapy was comparable to that in nude mice without CTX treatment. T cell transfer to 4T1-bearing nude mice enhanced the proportion of MDSCs in tumor-bearing mice after CTX therapy. The co-culture of MDSCs and T cells in vitro also showed that CD4(+) T cells and CD8(+) T cells could facilitate the expansion and survival of MDSCs, and this effect was mediated by IFN-γ released by T cells. These results gave an explanation of the unwanted consequence resulted from CTX treatment in tumor-bearing mice. It also provided some insights into the strategies for eliminating the bad side of CTX treatment and to make it more effective in cancer therapy.
No preview · Article · Feb 2012 · International immunopharmacology