Qi-Boosting Toxin-Resolving Formula Inhibits NPC Stem Cells Through Up-regulating MiR-200b Expression

[Background]Qi-Boosting Toxin-Resolving Formula (QBTRF) holds a strong inhibititory effect on implanted tumor of NPC (nasopharyngeal carcinoma) cells in nude mice. When used in a combined way with cisplatin, this kind of effect can be further enhanced to show a higher inhibition rate and improved quality of life following treatment on nude mice. It improves DC’s secretion of IL-12and increase the cytotoxic activity of CTL on NPC CNE2cells. More recently, cancer stem cell (CSC) has become associated with the operational detection of cells with CSC properties. In this case, the term refers to cells shown to have been capable of generating and propagating a malignant cell population, usually identified and characterized in an experimental setting. As so far, the report about cancer stem cells in NPC cell lines is rare.To explore the network associated with miRNA regulating and the effect of QBTRF as a drug in the treatment of NPC cells and NPC stem cells, miRNA microarray was applied to investigate the differentially expressed miRNAs in CNE2-SC/QBTRF treating system contrasting with CNE2-SC/control cells. [The expression analysis of CD133and CD44in NPC progression]More and more evidences have demonstrated that overacticated CD133and CD44were implicated in carcinogenesis of diverse tumors and as marker of CSCs. Thus, we selected CD133and CD44for further identification in the follwing experiments. In the immunohistochemical analysis using extended clinical samples, we detected the expression of the main members of CD133and CD44. The results showed that CD133and CD44expression increased in tumor tissues, and was associated with NPC progression. Then, we use flow cytometry and stem cells mammosphere assay detected the expression of CD133、CD44as well as the the cytotoxic effect on NPC stem cell CNE2-sc cells by QBTRF. The results showed that the ability into mammosphere of the NPC stem cell CNE2-sc was significantly inhibited and reduced the expression of CD133, while, have rare effect on the expression of CD44[The expressions of miRNAs regulated significantly by QBTRF in NPC stem cell]In the resultd of miRNA microarray, there were4upregulated miRNAs following the treatmrnt of QBTRF, with more than2-fold of expressive activity shown, which was subsequently identified by qRT-PCR. Data indicated that miR-200b was overexpressed in NPC tissues and cell lines. [miR-200b inhibited NPC stem cell growth though targeting CD133as a potential therapeutic marker and played important role in the pathogenesis of NPC]miRNA may be involved in the process of tumor development as a tumor suppressor gene. Overexpression of miR-200b reduced mammosphere number and size of NPC stem cells. It’s certified that miR-200b could inhibit NPC cell growth and invasion identified by MTT transwell test in vivo and in vitro. Some relative assays were performed to demonstrate that miR-200b could inhibit CD133. Therefore, they were considered to be potential therapeutic biomarker in NPC. qRT-PCR was applied to detect the expression of up-regulated miRNAs in CNP cell by QBTRF contrasting with normal epithelia cell NP-69/control. The results showed that the expression of miR-200b was striking reduced in CNE2, CNE1,6-10B and5-8F cell lines. Moreover, miR-200b was hardly expression in CNP stem cell CNE2-SC. So, we selected miR-200b for further identification in53NPC samples. qRT-PCR showed that the expression of miR-200b was significantly down-regulated and was associated with advanced clinical staging. These suggested that miR-200b might be a tumor suppressor involved in the development of NPC. Meanwhile, in vivo experiment confirmed that the expression of miR-200b was singnifcantly up-regurated in implanted tumor of NPC cells in nude mice following the treatment of QBTRF. Thus, QBTRF showed an inhibitory effect on the potentiality of growth, proliferation and invasion of CNP cells, which might depend on up-regulate the level of miR-200b.In conclusion, development of NPC is a pathological process associated with abnormal changes in multiple genes and developing status via multi-stages. Genes, miRNAs and CSC all play an important role in NPC formation. They may support or antagonize each other and construct a complicated network in the pathological processing of NPC. It has been clarified that the mechanism of QBTRF inhibiting the NPC stem cells may be through up-regulating miR-200b expression, thus providing potential diagnostic and prognostic evaluating markers, as well as therapeutic targets for NPC.