MicroRNA-613 Enhances Nasopharyngeal Carcinoma Cell Radiosensitivity via the DNA Methyltransferase 3B/Tissue Inhibitor of Matrix Metalloproteinase-3/Signal Transducer and Activator of Transcription-1/Forkhead Box O-1 Axis

Abstract

Nasopharyngeal carcinoma (NPC) is a common malignancy of the nasopharynx, and radioresistant represents the main obstacle in NPC treatment. Malignant transformation of normal cells is driven by genetic and epigenetic changes, which are primarily manifested as changes in miRNA levels and DNA methylation status. microRNA (miR)-613 plays an inhibitory role in several types of cancer. Herein, the current study sought to explore the roles of miR-613 in NPC cell radiosensitivity. miR-613 expression patterns in NPC tissues were detected, and its correlation with clinical indexes was analyzed. NP-69 and C666-1 cell lines were selected for cellular experimentation. Radioresistant cell line C666-1R was obtained by fractionated radiation. Cell viability, survival fraction, and apoptosis were detected by CCK-8, colony formation assay, and flow cytometry. The binding relation between miR-613 and DNMT3B was verified by dual-luciferase and RIP assays. miR-613 was lowly expressed in NPC tissues and cells, with lower expression levels in C666-1R than C666-1, and further correlated with lymph node metastasis, tumor size, and tumor metastasis. miR-613 overexpression reduced C666-1R cell viability and survival fraction and increased apoptosis, while C666-1 cells with silencing miR-613 presented the opposite trends. miR-613 targeted DNMT3B. miR-613 and DNMT3B overexpression led to enhanced C666-1R cell viability and survival fraction and decreased apoptosis. miR-613 reduced TIMP3 methylation and elevated TIMP3 protein level by inhibiting DNMT3B. miR-613 enhanced NPC radiosensitivity by inhibiting the DNMT3B/TIMP3/STAT1/FOXO1 pathway. Collectively, miR-613 inhibited DNMT3B, reduced TIMP3 methylation, and increased TIMP3 protein level, thus inhibiting the STAT1/FOXO1 pathway and enhancing the radiosensitivity of NPC cells.

The promising role of miRNAs in radioresistance and chemoresistance of nasopharyngeal carcinoma

“…Research has shown a trend toward the expression of approximately fifty new miRNAs, such as miR-150, miR-483-5p and miR-454-3p, in radiation-resistant NPC ( 19 , 32 , 33 ). Furthermore, more than thirty miRNAs, including miR-31-5p, miR-613 and miR-340-3p, have been shown to modulate the radiosensitivity of NPC ( 34 – 36 ).…”

“…demonstrated that miR-613 can decrease TIMP3 methylation and improve the expression of TIMP3 proteins by suppressing DNMT3B. As a result, the STAT1/FOXO1 signaling pathway was suppressed, and NPC cell sensitivity to radiation was enhanced ( 36 ). Notably, miR-124, which targets JAMA, can suppress stemness and increase NPC cells sensitivity to radiation both in vivo and in vitro ( 76 ).…”

Homeobox B2 promotes malignant behavior and contributes to the radioresistance of nasopharyngeal carcinoma by regulating forkhead box protein O1

“…Deng et al found that miR-613 enhances the radiosensitivity of NPC cells by inhibiting the downstream signal transducer and activator of transcription 1 (STAT1)/FOXO1 pathway 33 . In our study, western blotting results showed that FOXO1 levels were markedly decreased in NPC cells after HOXB2 overexpression.…”

“…The authors observed that FOXO1 not only controlled tumor stemness and metastasis, but also sensitized NPC cells to cisplatin in vitro and in vivo [32] . Deng et al found that miR-613 enhances the radiosensitivity of NPC cells by inhibiting the downstream signal transducer and activator of transcription 1 (STAT1)/FOXO1 pathway [33] . In our study, western blotting results showed that FOXO1 levels were markedly decreased in NPC cells after HOXB2 overexpression.…”