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MicroRNA (miR)-9 has been demonstrated to regulate the radiosensitivity of tumor cells. In the present study, the mechanism by which miR-9 modulates the sensitivity of nasopharyngeal carcinoma (NPC) cells to ultraviolet (UV) radiation was investigated. The results demonstrated that exposure of NPC cells to UV light resulted in a significant increase in the expression of miR-9, and that CNE2 cells overexpressing miR-9 exhibited reduced levels of DNA damage and increased levels of total glutathione upon UV exposure. Accordingly, the inhibition of the expression of miR-9 promoted UV-induced DNA damage and apoptosis. Although miR-9 inhibited the expression of E-cadherin in the CNE2 cells and increased their resistance to UV radiation, the use of small interfering RNA to inhibit the expression of E-cadherin was not sufficient to decrease the radiosensitivity of the NPC cells. These data demonstrated that miR-9 did not modulate the sensitivity of the CNE2 cells to UV radiation through E-cadherin, but suggested that miR-9 regulated radiosensitivity through its effects on glutathione. These findings suggest that miR-9 may be a potential target for modulating the radiosensitivity of NPC cells.

Endogenous soluble vascular endothelial growth factor receptor-2 (esVEGFR-2), a new splicing variant of VEGFR-2, was shown to be the first endogenous specific inhibitor of lymphatic vessel growth. The expression of esVEGFR-2 and its clinicopathological roles in esophageal squamous cell carcinoma (ESCC) are unclear. In this article, quantitative RT-PCR was employed to detect the mRNA levels of esVEGFR-2 and VEGF-C in 90 paired primary ESCC tissues, along with immunohistochemical staining to measure esVEGFR-2 protein in 182 ESCC primary tissues. Correlations between esVEGFR-2 expression and clinicopathological features were also analyzed. Compared with the corresponding non-neoplastic esophageal mucosa tissues, the mRNA level of esVEGFR-2 was decreased, whereas the mRNA level of VEGF-C was increased in ESCCs. Downregulation of esVEGFR-2 mRNA level was significantly correlated with pTNM stages (χ(2) = 7.790, p=0.02). Immunohistochemical staining of esVEGFR-2 was inclined to be reduced in ESCC tissues; lower esVEGFR-2 protein expression was related to better prognosis (χ(2) = 6.366, p=0.012), whereas higher esVEGFR-2 protein accumulation in ESCC tissues was an independent prognostic factor for poor survival of patients (hazard ratio, 1.606; 95% confidence interval, 1.042-2.476; p=0.032). Taken together, altered expression of esVEGFR-2 is correlated with progression of ESCC. esVEGFR-2 might serve as a new independent prognostic marker for ESCC patients.