Background: Nasopharyngeal carcinoma (NPC) is a common malignancy in China and Southeast Asia. Radiotherapy is the major treatment modality for patients with NPC, but does not always achieve fully satisfactory outcomes. Studies have shown that epidermal growth factor receptor (EGFR) is highly expressed in NPC, and EGFR-targeted treatment is expected to be a new strategy for NPC. Recently, clinical trials have shown that NPC patients have different responses to gefitinib. Thus, the identification of indicators that can regulate and predict the sensitivity of NPC to gefitinib is very valuable. MiRNAs (MicroRNAs) are closely related to cancer development. We studied miRNAs in NPC cell lines to identify those that can regulate and predict the effectiveness of gefitinib on NPC.
Methods: CCK8, Annexin V-FITC assays and animal models were carried out to evaluate the inhibitory effect of gefitinib on NPC cell lines HNE-1 and HK-1. MiRNA microarrays were used to detect and compare the miRNAs expression levels in the two cells with gefitinib or not, and qRT-PCR was used to evaluate miR-125a-5p expression in NPC cells and in serum of the tumor animal models. Loss-of-function and gain-of-function experiments were taken to evaluate the effect of miR-125a-5p on gefitinib effectiveness. Western blots were used to evaluate the effect of miR-125a-5p on p53 and Her2 in HNE-1 and HK-1 cells.
Results: Gefitinib inhibited two NPC cell lines proliferation in vitro and in vivo,and HNE-1 cells were less sensitive than HK-1 cells to gefitinib.MiR-125a-5p expression levels were increased by geftinib in the two cell lines and in the serum of NPC tumor bearing-mice. This phenomenon was weak in HNE-1 cells and strong in HK-1 cells. MiR-125a-5p over expression improved anti-proliferative and pro-apoptotic effects of gefitinib on the NPC cells and that miR-125a-5p down-regulation decreased those effects. MiR-125a-5p also increased p53 protein expression in HNE-1 cells, and decreased Her2 protein expression in HNE-1 and HK-1 cells.
Conclusions: Our results indicate that gefitinib sensitivity and some miRNAs expressions varied in NPC cell lines. The miR-125a-5p is a possible candidate that can regulate and predict the effect of gefitinib on NPC.