Background
The development of drug resistance leads many NPC patients to experience disease relapse following the completion of chemotherapy. It is thus essential that the mechanistic basis for such chemoresistance be clarified in an effort to identify approaches to sensitizing NPC tumors to treatment with cisplatin and related agents.
Methods
A qRT-PCR approach was used to measure the expression of circNRIP1 in NPC, while luciferase assays were used to identify interactions with downstream targets of circNRIP1 activity including miR-515-5p and IL-25. CCK8 assays were also utilized to detect IC50 values for cisplatin and 5-Fu.
Results
The expression of circNRIP1 was significantly increased in the serum of chemoresistant NPC patients. At a functional level, we determined that circNRIP1 is able to sequester miR-515-5p, thereby inhibiting its ability to post-transcriptionally suppress IL-25 expression. We observed a significant negative correlation between the expression of miR-515-5p and circNRIP1 in serum samples from chemoresistant NPC patients, consistent with a functional interaction between these two factors. We further found that 5-Fu and CDDP IC50 values in NPC cells in which circNRIP1 had been knocked down were restored following miR-515-5p inhibitor transfection. Similarly, changes in these IC50 values were reversed in NPC cells transfected with miR-515-5p mimics following the overexpression of IL-25 in these same cells.
Conclusion
These data highlight the circNRIP1/miR-515-5p/IL-25 as a novel regulator of 5-Fu and cisplatin resistance in NPC, suggesting that this pathway may be amenable to therapeutic targeting as an approach to treating this cancer type.
BackgroundRenal cell carcinoma accounts for 2–3% of all cancers and metastasis increased the malignancy of renal cancer. However, the role of methylation in metastasis of renal cancer is poorly understood.MethodsWe performed targeted gene array to compare the differential expressions of methylation regulated genes in metastatic and primary renal cancer tissues. Quantitative methylation specific PCR was performed to examine the CpG methylation levels of Runt related transcription factor 3 (RUNX3) and transforming growth factor (TGF)-β. Western blot was performed to detect the expression of target genes. Murine xenograft renal cancer model was established to assay gene expression, methylation level, tumor growth and animal survival in vivo.ResultsRUNX3 and TGF-β levels were decreased in metastatic renal cancer tissues as a result of their CpG methylation. Metastatic xenograft model displayed decreased expression levels of RUNX3 and TGF-β and higher CpG methylation levels, bigger tumor size and shorter survival time, all which were restored by treatment with a methylation inhibitor.ConclusionsHypermethylation in CpG islands promotes metastasis of renal cancer and is associated with TGF-β and RUNX3 inhibition.Electronic supplementary materialThe online version of this article (10.1186/s12935-018-0554-7) contains supplementary material, which is available to authorized users.
Small cell lung cancer (SCLC) has been a devastating actuality in clinic and the molecular mechanisms underlying this disease remain unclear. The epigenetic alterations located in the promoter region of human telomerase reverse transcriptase (hTERT) have been demonstrated as one of the most prevalent non-coding genomic modifications in multiple cancers. However, alteration of hTERT promoter methylation in SCLC and the subsequently induced change in tumor cell behavior remains unclear. In this research, we hypothesized that abnormal methylation of hTERT promotor enhanced the progression of SCLC and the outcome of radiotherapy resistance. Quantitative real-time PCR and western blot assays were performed to evaluate the RNA and protein levels of hTERT and enhancer of zeste homolog 2 (EZH2), respectively. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to estimate the viability and X-ray sensitivity of H20 and H446 cell lines. Functionally, upregulation of hTERT promoted the proliferation and migration of H20 and H446 cells, and the high-level of methylation in the promoter region of hTERT induced by radiation caused radio-resistance in SCLC. Mechanically, methylation of hTERT promoter enhanced the progression and radio-resistance of SCLC through upregulating the expression of its downstream effector EZH2.
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