Epstein-Barr virus (EBV) encoded microRNA BART8-3p drives radioresistance-associated metastasis in nasopharyngeal carcinoma.

Radiotherapy plays an important role in the treatment of nasopharyngeal carcinoma (NPC), however, 20% of patients with NPC exhibit unusual radioresistance. Patients with radioresistance are at risk of recurrence, so it is imperative to explore the mechanism of resistance to radiotherapy. In the past, studies on the mechanism of radioresistance have been restricted to DNA damage and related cell cycle remodeling or apoptosis. So far, no studies have explored the relationship between radioresistance and metastasis. Through the analysis of clinical samples, we observed that the metastasis rate of recurrent NPC was much higher than that of primary patients. In vitro and in vivo experiments showed that NPC cells with acquired radioresistance exhibited a stronger ability for invasion and metastasis. Mechanistically, we found that the Epstein-Barr virus (EBV)-encoded miRNA BART8-3p was increased in patients with NPC, and its expression was positively correlated with adverse prognostic factors, such as radioresistance. Besides this, miR-BART8-3p promoted the epithelial-mesenchymal transition, invasion, and metastasis of radioresistant NPC cells by targeting and inhibiting their PAG1 host gene. These findings suggested a novel role for EBV-miR-BART8-3p in promoting NPC radioresistance-associated metastasis and highlighted its potential value as a prognostic indicator or therapeutic target.

Zhou X ，Lin Y ，Chen Y ，Wang L ，Peng X ，Liao J ，Zeng H ，Luo W ，Wu D ，Cai L ... -  《-》

EBV-miR-BART8-3p induces epithelial-mesenchymal transition and promotes metastasis of nasopharyngeal carcinoma cells through activating NF-κB and Erk1/2 pathways.

Lin C ，Zong J ，Lin W ，Wang M ，Xu Y ，Zhou R ，Lin S ，Guo Q ，Chen H ，Ye Y ，Zhang B ，Pan J ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

EBV encoded miRNA BART8-3p promotes radioresistance in nasopharyngeal carcinoma by regulating ATM/ATR signaling pathway.

Resistance to radiotherapy is one of the main causes of treatment failure in patients with nasopharyngeal carcinoma (NPC). Epstein-Barr virus (EBV) infection is an important factor in the pathogenesis of NPC, and EBV-encoded microRNAs (miRNAs) promote NPC progression. However, the role of EBV-encoded miRNAs in the radiosensitivity of NPC remains unclear. Here, we investigated the effects of EBV-miR-BART8-3p on radiotherapy resistance in NPC cells in vitro and in vivo, and explored the underlying molecular mechanisms. Inhibitors of ataxia telangiectasia mutated (ATM)/ataxia telangiectasia mutated and Rad3-related (ATR) (KU60019 and AZD6738, respectively) were used to examine radiotherapy resistance. We proved that EBV-miR-BART8-3p promoted NPC cell proliferation in response to irradiation in vitro and associated with the induction of cell cycle arrest at the G2/M phase, which was a positive factor for the DNA repair after radiation treatment. Besides, EBV-miR-BART8-3p could increase the size of xenograft tumors significantly in nude mice. Treatment with KU60019 or AZD6738 increased the radiosensitivity of NPC by suppressing the expression of p-ATM and p-ATR. The present results indicate that EBV-miR-BART8-3p promotes radioresistance in NPC by modulating the activity of ATM/ATR signaling pathway.

Zhou X ，Zheng J ，Tang Y ，Lin Y ，Wang L ，Li Y ，Liu C ，Wu D ，Cai L ... -  《-》

Plasma Epstein-Barr Virus MicroRNA BART8-3p as a Diagnostic and Prognostic Biomarker in Nasopharyngeal Carcinoma.

Nasopharyngeal carcinoma is an Epstein-Barr virus (EBV)-associated tumor that is highly common in southern China. Our previous sequencing data demonstrated that the EBV-encoded microRNA BART8-3p was most upregulated in nasopharyngeal carcinoma (NPC) and was closely associated with the metastasis of NPC. However, the values of plasma BART8-3p in NPC patients have not yet been well characterized. We quantified plasma BART8-3p expression by quantitative real-time PCR in 205 newly diagnosed NPC patients. Kaplan-Meier analysis was used to compare overall survival (OS), distant metastasis-free survival (DMFS), and locoregional relapse-free survival (LRRFS) between the groups. Plasma pretreatment BART8-3p was highly expressed in NPC patients compared with healthy controls. Pretreatment BART8-3p yielded a 92% predictive value for detecting NPC. Importantly, BART8-3p decreased dramatically after therapy relative to pretreatment levels. High levels of pretreatment or post-treatment BART8-3p were associated with worse OS, DMFS, and LRRFS. Multivariate analysis showed that high pretreatment or post-treatment BART8-3p was an independent unfavorable prognostic marker for OS (HR 3.82, 95% CI 1.77-8.24, P = .001 or HR 2.74, 95% CI 1.27-5.91, P = .010), DMFS (HR 2.82, 95% CI 1.36-5.85, P = .005 or HR 3.27, 95% CI 1.57-6.81, P = .002), and LRRFS (HR 1.94, 95% CI 1.12-3.35, P = .018 or HR 2.03, 95% CI 1.14-3.62, P = .016) in NPC. Subgroup analysis revealed that for patients with locally advanced NPC with high levels of pretreatment BART8-3p (n = 58), more cycles of chemotherapy (≥6 cycles) tended to prolong OS (P = .070). Over 50% (6/11) patients with high levels of post-treatment BART8-3p presented distant metastasis. Plasma BART8-3p is a promising biomarker for the detection and prognosis of NPC.

Lin C ，Lin K ，Zhang B ，Su Y ，Guo Q ，Lu T ，Xu Y ，Lin S ，Zong J ，Pan J ... -  《-》

Plasma Epstein-Barr virus microRNA BART8-3p as a potential biomarker for detection and prognostic prediction in early nasopharyngeal carcinoma.

Epstein-Barr virus (EBV) encoded microRNA BART8-3p (miR-BART8-3p) was significantly associated with the metastasis in nasopharyngeal carcinoma (NPC). To explore the clinical values of plasma miR-BART8-3p in patients with early NPC. We retrospectively analyzed 126 patients with stage I and II NPC. A receiver operating characteristic curve was used to examine the diagnostic performance. Kaplan‒Meier analysis was applied to determine survival differences. Cox regression was used for univariate and multivariate analyses. Compared to healthy subjects, plasma EBV miR-BART8-3p was highly expressed in early NPC patients. The sensitivity, specificity, and area under the curve value of plasma miR-BART8-3p combined with plasma EBV DNA was up to 88.9%, 94.4%, and 0.931. Compared to patients with low expression of miR-BART8-3p, patients with high expression of miR-BART8-3p had poorer 5-year overall survival (OS) (98.9% vs. 91.1%, P = 0.025), locoregional recurrence-free survival (LRRFS) (100% vs. 83.9%, P < 0.001) and distant metastasis-free survival (DMFS) (98.9% vs. 88.0%, P = 0.006). Risk stratification analysis revealed that high-risk patients (with high levels of EBV DNA and miR-BART8-3p) had inferior OS, LRRFS, and DMFS than low-risk patients (without high levels of EBV DNA and miR-BART8-3p). Multivariate analysis verified that the high-risk group was an unfavorable factor for OS, LRRFS, and DMFS. A combination of plasma EBV miR-BART8-3p and EBV DNA could be a potential biomarker for the diagnosis and prognosis in early NPC.

Lin C ，Chen Y ，Lin X ，Peng H ，Huang J ，Lin S ，Pan J ，Li M ，Zong J ... -  《Scientific Reports》