MicroRNA-29c enhances the sensitivities of human nasopharyngeal carcinoma to cisplatin-based chemotherapy and radiotherapy

Nasopharyngeal carcinoma: current views on the tumor microenvironment's impact on drug resistance and clinical outcomes

The incidence of nasopharyngeal carcinoma (NPC) exhibits significant variations across different ethnic groups and geographical regions, with Southeast Asia and North Africa being endemic areas. Of note, Epstein-Barr virus (EBV) infection is closely associated with almost all of the undifferentiated NPC cases. Over the past three decades, radiation therapy and chemotherapy have formed the cornerstone of NPC treatment. However, recent advancements in immunotherapy have introduced a range of promising approaches for managing NPC. In light of these developments, it has become evident that a deeper understanding of the tumor microenvironment (TME) is crucial. The TME serves a dual function, acting as a promoter of tumorigenesis while also orchestrating immunosuppression, thereby facilitating cancer progression and enabling immune evasion. Consequently, a comprehensive comprehension of the TME and its intricate involvement in the initiation, progression, and metastasis of NPC is imperative for the development of effective anticancer drugs. Moreover, given the complexity of TME and the inter-patient heterogeneity, personalized treatment should be designed to maximize therapeutic efficacy and circumvent drug resistance. This review aims to provide an in-depth exploration of the TME within the context of EBV-induced NPC, with a particular emphasis on its pivotal role in regulating intercellular communication and shaping treatment responses. Additionally, the review offers a concise summary of drug resistance mechanisms and potential strategies for their reversal, specifically in relation to chemoradiation therapy, targeted therapy, and immunotherapy. Furthermore, recent advances in clinical trials pertaining to NPC are also discussed.

The role of microRNA-induced apoptosis in diverse radioresistant cancers

Resistance to cancer radiotherapy is one of the biggest concerns for success in treating and preventing recurrent disease. Malignant tumors may develop when they block genetic mutations associated with apoptosis or abnormal expression of apoptosis; Tumor treatment may induce the expression of apoptosis-related genes to promote tumor cell apoptosis. MicroRNAs have been shown to contribute to forecasting prognosis, distinguishing between cancer subtypes, and affecting treatment outcomes in cancer. Constraining these miRNAs may be an attractive treatment strategy to help overcome radiation resistance. The delivery of these future treatments is still challenging due to the excess downstream targets that each miRNA can control. Understanding the role of miRNAs brings us one step closer to attaining patient treatment and improving patient outcomes. This review summarized the current information on the role of microRNA-induced apoptosis in determining the radiosensitivity of various cancers.

Circulation microRNA expression profiles in patients with complete responses to chemoradiotherapy in nasopharyngeal carcinoma

Background

Aims

Methods

Results

Conclusion

Involvement of Non-Coding RNAs in Chemo- and Radioresistance of Nasopharyngeal Carcinoma

The crucial treatment for nasopharyngeal carcinoma (NPC) is radiation therapy supplemented by chemotherapy. However, long-term radiation therapy can cause some genetic and proteomic changes to produce radiation resistance, leading to tumour recurrence and poor prognosis. Therefore, the search for new markers that can overcome the resistance of tumor cells to drugs and radiotherapy and improve the sensitivity of tumor cells to drugs and radiotherapy is one of the most important goals of pharmacogenomics and cancer research, which is important for predicting treatment response and prognosis. Non-coding RNAs (ncRNAs), such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), may play important roles in regulating chemo- and radiation resistance in nasopharyngeal carcinoma by controlling the cell cycle, proliferation, apoptosis, and DNA damage repair, as well as other signalling pathways. Recent research has suggested that selective modulation of ncRNA activity can improve the response to chemotherapy and radiotherapy, providing an innovative antitumour approach based on ncRNA-related gene therapy. Therefore, ncRNAs can serve as biomarkers for tumour prediction and prognosis, play a role in overcoming drug resistance and radiation resistance in NPC, and can also serve as targets for developing new therapeutic strategies. In this review, we discuss the involvement of ncRNAs in chemotherapy and radiation resistance in NPC. The effects of these molecules on predicting therapeutic cancer are highlighted.

A Five-MicroRNA Signature Predicts the Prognosis in Nasopharyngeal Carcinoma

Background

There is no effective prognostic signature that could predict the prognosis of nasopharyngeal carcinoma (NPC).

Methods

We constructed a prognostic signature based on five microRNAs using random forest and Least Absolute Shrinkage And Selection Operator (LASSO) algorithm on the GSE32960 cohort (N = 213). We verified its prognostic value using three independent external validation cohorts (GSE36682, N = 62; GSE70970, N = 246; and TCGA-HNSC, N = 523). Through principal component analysis, receiver operating characteristic curve analysis, and C-index calculation, we confirmed the predictive accuracy of this prognostic signature.

Results

We calculated the risk score based on the LASSO algorithm and divided the patients into high- and low-risk groups according to the calculated optimal cutoff value. The patients in the high-risk group tended to have a worse prognosis outcome and chemotherapy response. The time-dependent receiver operating characteristic curve showed that the 1-year overall survival rate of the five-microRNA signature had an area under the curve of more than 0.83. A functional annotation analysis of the five-microRNA signature showed that the patients in the high-risk group were usually accompanied by activation of DNA repair and MYC-target pathways, while the patients in the low-risk group had higher immune-related pathway signals.

Conclusions

We constructed a five-microRNA prognostic signature, which could accurately predict the prognosis of nasopharyngeal carcinoma, and constructed a nomogram that could conveniently predict the overall survival of patients.

Radio-Susceptibility of Nasopharyngeal Carcinoma: Focus on Epstein- Barr Virus, MicroRNAs, Long Non-Coding RNAs and Circular RNAs

Nasopharyngeal carcinoma (NPC) is a type of head and neck cancer. As a neoplastic disorder, NPC is a highly malignant squamous cell carcinoma that is derived from the nasopharyngeal epithelium. NPC is radiosensitive; radiotherapy or radiotherapy combining with chemotherapy are the main treatment strategies. However, both modalities are usually accompanied by complications and acquired resistance to radiotherapy is a significant impediment to effective NPC therapy. Therefore, there is an urgent need to discover effective radio-sensitization and radio-resistance biomarkers for NPC. Recent studies have shown that Epstein-Barr virus (EBV)-encoded products, microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), which share several common signaling pathways, can function in radio-related NPC cells or tissues. Understanding these interconnected regulatory networks will reveal the details of NPC radiation sensitivity and resistance. In this review, we discuss and summarize the specific molecular mechanisms of NPC radio-sensitization and radio-resistance, focusing on EBV-encoded products, miRNAs, lncRNAs and circRNAs. This will provide a foundation for the discovery of more accurate, effective and specific markers related to NPC radiotherapy. EBVencoded products, miRNAs, lncRNAs and circRNAs have emerged as crucial molecules mediating the radio-susceptibility of NPC. This understanding will improve the clinical application of markers and inform the development of novel therapeutics for NPC.

A Comprehensive RNA Study to Identify circRNA and miRNA Biomarkers for Docetaxel Resistance in Breast Cancer

To investigate the relationship between non-coding RNAs [especially circular RNAs (circRNAs)] and docetaxel resistance in breast cancer, and to find potential predictive biomarkers for taxane-containing therapies, we have performed transcriptome and microRNA (miRNA) sequencing for two established docetaxel-resistant breast cancer (DRBC) cell lines and their docetaxel-sensitive parental cell lines. Our analyses revealed differences between circRNA signatures in the docetaxel-resistant and -sensitive breast cancer cells, and discovered circRNAs generated by multidrug-resistance genes in taxane-resistant cancer cells. In DRBC cells, circABCB1 was identified and validated as a circRNA that is strongly up-regulated, whereas circEPHA3.1 and circEPHA3.2 are strongly down-regulated. Furthermore, we investigated the potential functions of these circRNAs by bioinformatics analysis, and miRNA analysis was performed to uncover potential interactions between circRNAs and miRNAs. Our data showed that circABCB1, circEPHA3.1 and circEPHA3.2 may sponge up eight significantly differentially expressed miRNAs that are associated with chemotherapy and contribute to docetaxel resistance via the PI3K-Akt and AGE-RAGE signaling pathways. We also integrated differential expression data of mRNA, long non-coding RNA, circRNA, and miRNA to gain a global profile of multi-level RNA changes in DRBC cells, and compared them with changes in DNA copy numbers in the same cell lines. We found that Chromosome 7 q21.12-q21.2 was a common region dominated by multi-level RNA overexpression and DNA amplification, indicating that overexpression of the RNA molecules transcribed from this region may result from DNA amplification during stepwise exposure to docetaxel. These findings may help to further our understanding of the mechanisms underlying docetaxel resistance in breast cancer.

Oncolytic virotherapy promotes radiosensitivity in soft tissue sarcoma by suppressing anti-apoptotic MCL1 expression

Soft tissue sarcoma (STS) is a rare cancer that develops from soft tissues in any part of the body. Despite major advances in the treatment of STS, patients are often refractory to conventional radiotherapy, leading to poor prognosis. Enhancement of sensitivity to radiotherapy would therefore improve the clinical outcome of STS patients. We previously revealed that the tumor-specific, replication-competent oncolytic adenovirus OBP-301 kills human sarcoma cells. In this study, we investigated the radiosensitizing effect of OBP-301 in human STS cells. The in vitro antitumor effect of OBP-301 and ionizing radiation in monotherapy or combination therapy was assessed using highly radiosensitive (RD-ES and SK-ES-1) and moderately radiosensitive (HT1080 and NMS-2) STS cell lines. The expression of markers for apoptosis and DNA damage were evaluated in STS cells after treatment. The therapeutic potential of combination therapy was further analyzed using SK-ES-1 and HT1080 cells in subcutaneous xenograft tumor models. The combination of OBP-301 and ionizing radiation showed a synergistic antitumor effect in all human STS cell lines tested, including those that show different radiosensitivity. OBP-301 was found to enhance irradiation-induced apoptosis and DNA damage via suppression of anti-apoptotic myeloid cell leukemia 1 (MCL1), which was expressed at higher levels in moderately radiosensitive cell lines. The combination of OBP-301 and ionizing radiation showed a more profound antitumor effect compared to monotherapy in SK-ES-1 (highly radiosensitive) and HT1080 (moderately radiosensitive) subcutaneous xenograft tumors. OBP-301 is a promising antitumor reagent to improve the therapeutic potential of radiotherapy by increasing radiation-induced apoptosis in STS.

Impact of the weekday of the first intensity-modulated radiotherapy treatment on the survival outcomes of patients with nasopharyngeal carcinoma: A multicenter cohort study

BACKGROUND

This study's purpose was to assess whether the weekday on which intensity-modulated radiotherapy (IMRT) is initiated influences survival outcomes in patients with nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

A total of 1440 patients with NPC who received IMRT were enrolled in this study between January 2010 and June 2016. The patients were divided into five groups according to the weekday of their first radiotherapy treatment. Group 1 (n = 322), Group 2 (n = 322), Group 3 (n = 286), Group 4 (n = 292) and Group 5 (n = 218) received first radiotherapy on Monday, Tuesday, Wednesday, Thursday and Friday respectively. Differences in the rates of overall survival (OS), disease-free survival (DFS), loco-regional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS) were compared among the five groups using the Kaplan-Meier method and Cox regression models.

RESULTS

No significant differences were found in OS, DFS, LRRFS or DMFS among the five groups. The Cox regression analysis showed that the weekday on which the radiotherapy was initiated was not an independent predictor of OS (Hazard Ratio [HR], 1.056; 95%CI: 0.959-1.164, P = 0.268), DFS (HR, 1.067; 95% CI: 0.980-1.161, P = 0.137), LRRFS (HR, 1.069; 95% CI: 0.914-1.249, P = 0.404) and DMFS (HR, 1.027; 95% CI: 0.929-1.134, P = 0.607). The subgroup analysis showed no significant differences among the five groups.

CONCLUSIONS

This study showed that the day of the week that patients with nasopharyngeal carcinoma begin radiotherapy has no effect on their survival outcomes.

The Regulatory Cross-Talk between microRNAs and Novel Members of the B7 Family in Human Diseases: A Scoping Review

The members of the B7 family, as immune checkpoint molecules, can substantially regulate immune responses. Since microRNAs (miRs) can regulate gene expression post-transcriptionally, we conducted a scoping review to summarize and discuss the regulatory cross-talk between miRs and new B7 family immune checkpoint molecules, i.e., B7-H3, B7-H4, B7-H5, butyrophilin like 2 (BTNL2), B7-H6, B7-H7, and immunoglobulin like domain containing receptor 2 (ILDR2). The current study was performed using a six-stage methodology structure and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. PubMed, Embase, Scopus, Cochrane, ProQuest, and Google Scholar were systematically searched to obtain the relevant records to 5 November 2020. Two authors independently reviewed the obtained records and extracted the desired data. After quantitative and qualitative analyses, we used bioinformatics approaches to extend our knowledge about the regulatory cross-talk between miRs and the abovementioned B7 family members. Twenty-seven articles were identified that fulfilled the inclusion criteria. Studies with different designs reported gene–miR regulatory axes in various cancer and non-cancer diseases. The regulatory cross-talk between the aforementioned B7 family molecules and miRs might provide valuable insights into the pathogenesis of various human diseases.

Role of Non-coding RNAs on the Radiotherapy Sensitivity and Resistance of Head and Neck Cancer: From Basic Research to Clinical Application

Head and neck cancers (HNCs) rank as the sixth common and the seventh leading cause of cancer-related death worldwide, with an estimated incidence of 600,000 cases and 40-50% mortality rate every year. Radiotherapy is a common local therapeutic modality for HNC mainly through the function of ionizing radiation, with approximately 60% of patients treated with radiotherapy or chemoradiotherapy. Although radiotherapy is more advanced and widely used in clinical practice, the 5-year overall survival rates of locally advanced HNCs are still less than 40%. HNC cell resistance to radiotherapy remains one of the major challenges to improve the overall survival in HNC patients. Non-coding RNAs (ncRNAs) are newly discovered functional small RNA molecules that are different from messenger RNAs, which can be translated into a protein. Many previous studies have reported the dysregulation and function of ncRNAs in HNC. Importantly, researchers reported that several ncRNAs were also dysregulated in radiotherapy-sensitive or radiotherapy-resistant HNC tissues compared with the normal cancer tissues. They found that ectopically elevating or knocking down expression of some ncRNAs could significantly influence the response of HNC cancer cells to radiotherapy, indicating that ncRNAs could regulate the sensitivity of cancer cells to radiotherapy. The implying mechanism for ncRNAs in regulating radiotherapy sensitivity may be due to its roles on affecting DNA damage sensation, inducing cell cycle arrest, regulating DNA damage repair, modulating cell apoptosis, etc. Additionally, clinical studies reported that in situ ncRNA expression in HNC tissues may predict the response of radiotherapy, and circulating ncRNA from body liquid serves as minimally invasive therapy-responsive and prognostic biomarkers in HNC. In this review, we aimed to summarize the current function and mechanism of ncRNAs in regulating the sensitivity of HNC cancer cells to radiotherapy and comprehensively described the state of the art on the role of ncRNAs in the prognosis prediction, therapy monitoring, and prediction of response to radiotherapy in HNC.

miRNA as promising theragnostic biomarkers for predicting radioresistance in cancer: A systematic review and meta-analysis

Radioresistance remains as an obstacle in cancer treatment. This systematic review and meta-analysis aimed to evaluate the association between the expression of miRNAs and responses to radiotherapy and the prognosis of different tumors. In total, 77 miRNAs in 19 cancer types were studied, in which 24 miRNAs were upregulated and 58 miRNAs were downregulated in cancer patients. Five miRNAs were differentially expressed. Moreover, 75 miRNAs were found to be related to radioresistance, while 5 were observed to be related to radiosensitivity. The pooled HR and 95 % confidence interval for the combined studies was 1.135 (0.819-1.574; P-value = 0.4). The HR values of the subgroup analysis for miR-21 (HR = 2.344; 95 % CI: 1.927-2.850; P-value = 0.000), nasopharyngeal carcinoma (HR = 0.448; 95 % CI: 0.265-0.760; P = 0.003) and breast cancer (HR = 1.131; 95 % CI: 0.311-4.109; P = .85) were obtained. Our results highlighted that across the published literature, miRNAs can modulate tumor radioresistance or sensitivity by affecting radiation-related signaling pathways. It seems that miRNAs could be considered as a theragnostic biomarker to predict and monitor clinical response to radiotherapy. Thus, the prediction of radioresistance in malignant patients will improve radiotherapy outcomes and radiotherapeutic resistance.

A novel microRNA-based signature predicts prognosis among nasopharyngeal cancer patients

IMPACT STATEMENT

Nasopharyngeal cancer is one of the most common malignant tumors in the head and neck. Identification of promising miRNA biomarkers might benefit a lot to the detection of nasopharyngeal carcinoma. A three-miRNA signature (has-miR-142-3p, has-miR-29c, and has-miR-30e) was obviously associated with the overall survival of nasopharyngeal carcinoma patients. The model has better clinical independence and has better clinical prediction effect when combined with clinical characteristics. Our results revealed that a three-miRNA signature was a potential novel prognostic biomarker for nasopharyngeal carcinoma.

Diagnostic and Prognostic Indications of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a disease that is highly associated with the latent infection of Epstein–Barr virus. The absence of obvious clinical signs at the early stage of the disease has made early diagnosis practically impossible, thereby promoting the establishment and progression of the disease. To enhance the stride for a reliable and less invasive tool for the diagnosis and prognosis of NPC, we synopsize biomarkers belonging to the two most implicated biological domains (oncogenes and tumor suppressors) in NPC disease. Since no single biomarker is sufficient for diagnosis and prognosis, coupled with the fact that the known established methods such as methylation-specific polymerase chain reaction (PCR), multiplex methylation-specific PCR, microarray assays, etc., can only accommodate a few biomarkers, we propose a 10-biomarker panel (KIT, LMP1, PIKC3A, miR-141, and miR-18a/b (oncogenic) and p16, RASSF1A, DAP-kinase, miR-9, and miR-26a (tumor suppressors)) based on their diagnostic and prognostic values. This marker set could be explored in a multilevel or single unified assay for the diagnosis and prognosis of NPC. If carefully harnessed and standardized, it is hoped that the proposed marker set would help transform the diagnostic and prognostic realm of NPC, and ultimately, help prevent the life-threatening late-stage NPC disease.

The role of microRNA in cisplatin resistance or sensitivity

INTRODUCTION

Cisplatin is a chemotherapy drug that has been used to treat a number of cancers for decades, and is still one of the most commonly used anti-cancer agents. However, some patients do not respond to cisplatin while other patients who were originally sensitive to cisplatin eventually develop chemoresistance, leading to treatment failure or/and tumor recurrence.

AREAS COVERED

Different mechanisms contribute to cisplatin resistance or sensitivity, involving multiple pathways or/and processes such as DNA repair, DNA damage response, drug transport, and apoptosis. Among the various mechanisms, it appears that microRNAs play an important role in determining the resistance or sensitivity. In this article, we analyzed and summarized recent findings in this area, with the aim that these data can aid further research and understanding, leading to the eventual reduction of cisplatin resistance.

EXPERT COMMENTARY

microRNAs can positively or negatively regulate cisplatin resistance by acting on molecules or/and pathways related to apoptosis, autophagy, hypoxia, cancer stem cells, NF-κB, and Notch1. It appears that the modulation of relevant microRNAs can effectively re-sensitize cancer cells to cisplatin regimen in certain types of cancers including breast, colorectal, gastric, liver, lung, ovarian, prostate, testicular, and thyroid cancers.

The potential of circulating exosomal RNA biomarkers in cancer

INTRODUCTION

There are great potentials of using exosomal RNAs (exoRNA) as biomarkers in cancers. The isolation of exoRNA requires the use of ultracentrifugation to isolate cell-free RNA followed by detection using real-time PCR, microarray, next-generation sequencing, or Nanostring nCounter system. The use of exoRNA enrichment panels has largely increased the detection sensitivity and specificity when compared to traditional diagnostic tests. Moreover, using exoRNA as biomarkers can assist the early detection of chemo and radioresistance cancer, and in turn opens up the possibility of personalized treatment to patients. Finally, exoRNA can be detected at an early stage of cancer recurrence to improve the survival rate.

AREAS COVERED

In this review, the authors summarized the detection methods of exoRNA as well as its potential as a biomarker in cancer diagnosis and chemo and radioresistance.

EXPERT OPINION

The application of exoRNAs in clinical diagnosis is still in its infancy. Further researches on extracellular vesicles isolation, detection protocols, exoRNA classes and subclasses, and the regulatory biological pathways have to be performed before exoRNA can be applied translationally.

Riluzole Enhances the Response of Human Nasopharyngeal Carcinoma Cells to Ionizing Radiation via ATM/P53 Signalling Pathway

Riluzole is approved by the FDA as an amyotrophic lateral sclerosis (ALS) drug. Previous studies showed that treatment with riluzole suppressed the proliferation of many cancer cells. However, little is known about its effects on nasopharyngeal carcinoma (NPC) and its molecular mode of action. In this study, we determined the effect of riluzole on apoptosis, cell cycle, migration, and invasion in NPC cell lines and investigated its mechanism at the molecular level. By using the human NPC cell lines CNE1, CNE2, and HNE1, we revealed that riluzole effectively inhibited viability of the NPC cell lines in dose- and time-dependent manners. Furthermore, riluzole dose-dependently induced apoptosis and G2/M cell cycle arrest in the NPC cell lines. After combination with radiotherapy (RT), greater cytotoxicity was achieved than with riluzole or RT alone in vitro and vivo. This was associated with the activation of ataxia telangiectasia mutated (ATM) and phosphoinositide p53 pathways. P53 silencing reduced cell reactiveness to riluzole therapy. These observations demonstrate that the riluzole-activated ATM/P53 pathway is directly involved in radiation-induced apoptosis of NPC cells. Given the acceptable side effect, combining of riluzole and radiotherapy is promising in NPC treatment.

CSB affected on the sensitivity of lung cancer cells to platinum-based drugs through the global decrease of let-7 and miR-29

Background

Transcription-coupled nucleotide excision repair (TC-NER) plays a prominent role in the removal of DNA adducts induced by platinum-based chemotherapy reagents. Cockayne syndrome protein B (CSB), the master sensor of TCR, is also involved in the platinum resistant. Let-7 and miR-29 binding sites are highly conserved in the proximal 3′UTR of CSB.

Methods

We conducted immunohistochemisty to examine the expression of CSB in NSCLC. To determine whether let-7 family and miR-29 family directly interact with the putative target sites in the 3′UTR of CSB, we used luciferase reporter gene analysis. To detect the sensitivity of non-small cell lung cancer (NSCLC) cells to platinum-based drugs, CCK analysis and apoptosis analysis were performed.

Results

We found that let-7 and miR-29 negatively regulate the expression of CSB by directly targeting to the 3′UTR of CSB. The endogenous CSB expression could be suppressed by let-7 and miR-29 in lung cancer cells. The suppression of CSB activity by endogenous let-7 and miR-29 can be robustly reversed by their sponges. Down-regulation of CSB induced apoptosis and increased the sensitivity of NSCLC cells to cisplatin and carboplatin drugs. Let-7 and miR-29 directly effect on cisplatin and carboplatin sensitivity in NSCLC.

Conclusions

In conclusion, the platinum-based drug resistant of lung cancer cells may involve in the regulation of let-7 and miR-29 to CSB.

MicroRNAs as Therapeutic Targets in Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a malignancy of epithelial origin that is prone to local invasion and early distant metastasis. Although concurrent chemotherapy and radiotherapy improves the 5-year survival outcomes, persistent or recurrent disease still occurs. Therefore, novel therapeutic targets are needed for NPC patients. MicroRNAs (miRNAs) play important roles in normal cell homeostasis, and dysregulations of miRNA expression have been implicated in human cancers. In NPC, studies have revealed that miRNAs are dysregulated and involved in tumorigenesis, metastasis, invasion, resistance to chemo- and radiotherapy, and other disease- and treatment-related processes. The advantage of miRNA-based treatment approaches is that miRNAs can concurrently target multiple effectors of pathways involved in tumor cell differentiation and proliferation. Thus, miRNA-based cancer treatments, alone or combined with standard chemotherapy and/or radiotherapy, hold promise to improve treatment response and cure rates. In this review, we will summarize the dysregulation of miRNAs in NPC initiation, progression, and treatment as well as NPC-related signaling pathways, and we will discuss the potential applications of miRNAs as biomarkers and therapeutic targets in NPC patients. We conclude that miRNAs might be potential promising therapeutic targets in nasopharyngeal carcinoma.

Research Progress on Long Non-Coding RNA and Radiotherapy

Long non-coding RNAs (lncRNAs), a group of non-protein-coding RNAs longer than 200 nucleotides, are involved in multiple biological and pathological processes, such as proliferation, apoptosis, migration, invasion, angiogenesis, and immune escape. Many studies have shown that lncRNAs participate in the complex network of cancer and play vital roles as oncogenes or tumor-suppressor genes in a variety of cancers. Moreover, recent research has shown that abnormal expression of lncRNAs in malignant tumor cells before and after radiotherapy may participate in the progression of cancers and affect the radiation sensitivity of malignant tumor cells mediated by specific signaling pathways or cell cycle regulation. In this review, we summarize the published studies on lncRNAs in radiotherapy regarding the biological function and mechanism of human cancers, including esophageal cancer, pancreatic cancers, nasopharyngeal carcinoma, hepatocellular carcinoma, cervical cancer, colorectal cancer, and gastric cancer.

miR-143 inhibits proliferation and metastasis of nasopharyngeal carcinoma cells via targeting FMNL1 based on clinical and radiologic findings

Mounting evidence has reported that microRNA-143 (miR-143) is involved in the development of multiple cancers. To investigate the underlying mechanisms of miR-143 regulating proliferation and metastasis in nasopharyngeal carcinoma (NPC) cells, we evaluated the levels of miR-143 and formin-like protein 1 (FMNL1) in NPC tissues. The results of qRT-PCR and Western blot analysis showed that the expression of miR-143 was decreased, while FMNL1 was increased in NPC tissues. The expression of miR-143 was significantly elevated in NPC cells compared with that of human nasopharyngeal epithelial cells. The results of MiRcode prediction, dual-luciferase reporter, and Western blot analysis assays indicated that miR-143 negatively regulated the expression of FMNL1 (r²  = 0.4365P = 0.0001). Overexperssion of miR-143 or FMNL1 knockdown inhibited cell proliferation, migration, and invasion in NPC cells (P < 0.05). Ectopic expression of FMNL1 undermined the inhibition effect of miR-143 on proliferation, migration, and invasion in NPC cells. The findings of this study revealed that miR-143 functioned as a tumor suppressor and inhibited the NPC progression by targeting FMNL1.

PPARβ/δ Agonist GW501516 Inhibits Tumorigenesis and Promotes Apoptosis of the Undifferentiated Nasopharyngeal Carcinoma C666-1 Cells by Regulating miR-206

In previous investigations, we reported that peroxisome proliferator-activated receptor β/δ (PPARβ/δ) activation by GW501516 inhibits proliferation and promotes apoptosis in the undifferentiated C666-1 nasopharyngeal carcinoma (NPC) cells by modulating caspase-dependent apoptotic pathway. In the present study, the mechanism by which GW501516 induces apoptosis was explored from the perspective of microRNA (miRNA) expression. Among the assayed miRNAs that were involved in regulating the expression of antiapoptotic protein Bcl-2, miR-206 was increased significantly and specifically by GW501516 in C666-1 cells at both the in vitro level and at the in vivo xenograft samples. The induction on miR-206 expression caused by GW501516 was capable of being antagonized by the PPARβ/δ antagonist GSK3787 and AMPK antagonist dorsomorphin in C666-1 cells. GW501516's suppression on the growth and apoptosis of C666-1 cells was found to be dependent on the presence of miR-206. miR-206 overexpression resulted in suppressed proliferation and colony formation ability, and further triggered increased apoptosis in C666-1 cells in a caspase-dependent manner. The expression of cleaved caspase 3 and caspase 9, and the ratio of Bax to Bcl-2 were elevated remarkably by miR-206. Consistent with the in vitro result, miR-206 was corroborated to suppress the ectopic NPC xenograft tumorigenesis that derived from the C666-1 cells in BALB/c nu/nu mice. Taken together, the current data demonstrated that miR-206 plays a critical role in the direct apoptosis-promoting effect induced by GW501516 in C666-1 cells. Furthermore, the emphasized tumor-suppressive role of miR-206 in the C666-1 cells indicates that it has the potential to provide a new therapeutic approach for the undifferentiated NPC.

Identification of COL4A1 as a potential gene conferring trastuzumab resistance in gastric cancer based on bioinformatics analysis

Trastuzumab, the first targeted antibody against human epidermal growth factor receptor 2 (HER2), has been used to treat gastric cancer patients with HER2 overexpression. However, trastuzumab resistance often occurs following an initial period of benefits, and the underlying mechanisms remain largely unclear. The present study revealed that collagen type IV α1 chain (COL4A1), whose expression is upregulated in gastric cancer tissues and trastuzumab-resistant gastric cancer cells, may potentially confer trastuzumab resistance in gastric cancer. By performing bioinformatics analysis of 2 microarray datasets, the present study initially identified COL4A1, overexpressed in gastric cancer tissues and trastuzumab-resistant gastric cancer cells, as a potential candidate for inducing trastuzumab resistance. The drug resistance function of COL4A1 in gastric cancer was then validated by performing protein/gene interactions and biological process annotation analyses, and further validated by analyzing the functionality of microRNAs that target COL4A1 mRNA. Collectively, these data indicated that COL4A1 may confer trastuzumab resistance in gastric cancer.

MicroRNA-150 enhances radiosensitivity by inhibiting the AKT pathway in NK/T cell lymphoma

Background

Radioresistance is a major challenge during the treatment of NK/T cell lymphoma. This study aimed to investigate the potential role of MicroRNA-150 (miR-150) in increase the sensitivities of NK/T cell lymphoma to ionizing radiation.

Results

In this study, we found that miR-150 was significantly decreased in NK/T cell lymphoma tissues and cell lines. Low expression of miR-150 was positively associated with therapeutic resistance in 36 NK/T cell lymphoma cases. Our further in vitro and in vivo studies illustrated that overexpression of miR-150 substantially enhanced the sensitivity of NK/T cell lymphoma cells to ionizing radiation treatment. Furthermore, luciferase reporter assays in NK/T cell lymphoma cells transfected with the AKT2 or AKT3 three prime untranslated region reporter constructs established AKT2 and AKT3 as direct targets of miR-150. The phosphatidylinositol 3-kinase inhibitor LY294002 was used to inhibit Akt to verify miR-150 increase NK/T cell lymphoma cell radiorsensitivity through suppress the PI3K/AKT/mTOR pathway.

Conclusions

Taken together, this study demonstrates that miR-150 might serve as a potential therapeutic sensitizer through inhibition of the AKT pathway in NK/T cell lymphoma treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0639-5) contains supplementary material, which is available to authorized users.

Knockdown of GRP78 enhances cell death by cisplatin and radiotherapy in nasopharyngeal cells

Radiotherapy and adjuvant cisplatin chemotherapy are the mainstream approaches in the treatment of nasopharyngeal carcinoma (NPC). These have been shown to effectively improve the outcome and reduce tumor recurrence. However, radiotherapy and chemotherapy resistance during the course of treatment has become more common recently, resulting in the failure of NPC therapy. Therefore, new therapeutic strategies or adjuvant drugs are urgently needed. The current study was designed to look for new treatment strategies or auxiliary drugs in the treatment of NPC. Two human NPC cell lines, HNE1 and HNE1/DDP, were used to examine the relationship between endoplasmic reticulum stress and cell resistance to ionizing radiation (IR) and cisplatin (DDP). Cell proliferation was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Meanwhile, propidium iodide (PI) staining and PI/Annexin V staining were used to observe cell apoptosis. Finally, western blot was used to detect the endogenous expression of glucose-regulated protein 78 (GRP78) and other apoptosis-related proteins. GRP78 small interference RNA was transfected using Lipofectamine 2000. Compared with HNE1/DDP, IR and DDP increased the cell apoptosis and inhibited the cell proliferation of HNE1. Inhibition of GRP78 can reverse IR and DDP resistance in NPC cells by PI/Annexin V staining. Knockdown of GRP78 upregulates the expression of pro-apoptotic proteins and downregulates the expression of antiapoptotic proteins. These results indicate that HNE1 is more sensitive to DDP and IR than HNE1/DDP. Knockdown GRP78 can reverse IR and DDP resistance in NPC cells. Inhibition of GRP78 gives us a new target to overcome resistance to radiotherapy and chemotherapy of NPC cells. Thus, this study should be further explored in vivo and assessed for possible clinical applications.

Downregulation of lncRNA X Inactive Specific Transcript (XIST) Suppresses Cell Proliferation and Enhances Radiosensitivity by Upregulating mir-29c in Nasopharyngeal Carcinoma Cells

Background

LncRNA X inactive specific transcript (XIST) was reported to function as an oncogene in nasopharyngeal carcinoma cells (NPC) by sponging miR-34a-5p. However, the role of XIST in modulating the radiosensitivity of NPC cells and its mechanism still remain undefined.

Material/Methods

The expressions of XIST and miR-29c in NPC cells were evaluated by qRT-PCR. CNE1 and CNE2 cells were transfected with si-XIST, pcDNA-XIST, miR-29c mimics, anti-miR-29c, or respective controls by Lipofectamine 2000. The effects of XIST knockdown and miR-29c overexpression on cell proliferation, survival fraction, and γ-H2AX expression were investigated by CCK-8 assay, colony formation assay, immunofluorescence, and Western blot, respectively. Luciferase reporter assay and qRT-PCR analysis were performed to confirm whether XIST interacts with miR-29c and regulates its expression.

Results

XIST was upregulated and miR-29c was downregulated in NPC cells. The expressions of XIST and miR-29c changed reversely in response to irradiation. Knockdown of XIST and miR-29c overexpression both resulted in a dramatic suppression of cell proliferation, a marked enhancement of radiosensitivity, and an obvious increase of γ-H2AX foci formation in NPC cells. Luciferase reporter assay and qRT-PCR analysis demonstrated that XIST interacts with miR-29c and negatively regulates its expression. Moreover, miR-29c inhibition abrogated XIST knockdown-induced cell proliferation inhibition and radiosensitivity increase in NPC cells.

Conclusions

XIST knockdown suppressed cell proliferation and enhanced radiosensitivity of NPC cells by upregulating miR-29c, providing a novel therapeutic target to improve radiotherapy efficiency for patients with NPC.

MicroRNA-148b suppresses proliferation, migration, and invasion of nasopharyngeal carcinoma cells by targeting metastasis-associated gene 2

PURPOSE

MicroRNAs (miRNAs) play important roles in tumorigenesis and metastasis by regulating genes expression. MiRNA-148b (miR-148b) had been reported to inhibit tumor progression in some kinds of cancers, but the functions of miR-148b in nasopharyngeal carcinoma (NPC) remain largely unknown. The aim of this study was to investigate the functional role of miR-148b in NPC.

METHODS

Expression of miR-148b in NPC tissues and cell lines was detected by quantitative reverse transcription polymerase chain reaction. MiR-148b was overexpressed in CNE2 and C666-1 cells by miR-148b mimic transfection. The effects of miR-148b on cell proliferation, migration, and invasion were determined by colony formation assays, cell viability assays, and transwell assays. The target gene of miR-148b was investigated by luciferase assays, and the rescue experiment was performed.

RESULTS

MiR-148b was downregulated in NPC tissues and cell lines. Ectopic miR-148b expression significantly inhibited proliferation, migration, and invasion of CNE2 and C666-1 cells. We identified that metastasis-associated gene 2 (MTA2) is a direct target of miR-148b. Rescue experiment demonstrated that the tumor-suppressive effects of miR-148b on C666-1 cell were partly reversed by restoration of MTA2 expression. Moreover, miR-148b expression was negatively related to mRNA level of MTA2 in NPC tissues.

CONCLUSION

Our findings elucidate that miR-148b negatively regulates the growth, migration, and invasion of NPC cells, at least in part, by targeting MTA2. The present study indicates that miR-148b is a potential therapeutic agent for NPC.

Tumor suppressor miR-29c regulates radioresistance in lung cancer cells

Radiotherapy is an important treatment option for non-small cell lung carcinoma patients. Despite the appropriate use of radiotherapy, radioresistance is a biological behavior of cancer cells that limits the efficacy of this treatment. Deregulation of microRNAs contributes to the molecular mechanism underlying resistance to radiotherapy in cancer cells. Although the functional roles of microRNAs have been well described in lung cancer, their functional roles in radioresistance are largely unclear. In this study, we established a non-small cell lung carcinoma Calu-1 radioresistant cell line by continuous exposure to therapeutic doses of ionizing radiation as a model to investigate radioresistance-associated microRNAs. Our data show that 50 microRNAs were differentially expressed in Calu-1 radioresistant cells (16 upregulated and 34 downregulated); furthermore, well-known and novel microRNAs associated with resistance to radiotherapy were identified. Gene ontology and enrichment analysis indicated that modulated microRNAs might regulate signal transduction, cell survival, and apoptosis. Accordingly, Calu-1 radioresistant cells were refractory to radiation by increasing cell survival and reducing the apoptotic response. Among deregulated microRNAs, miR-29c was significantly suppressed. Reestablishment of miR-29c expression in Calu-1 radioresistant cells overcomes the radioresistance through the activation of apoptosis and downregulation of Bcl-2 and Mcl-1 target genes. Analysis of The Cancer Genome Atlas revealed that miR-29c is also suppressed in tumor samples of non-small cell lung carcinoma patients. Notably, we found that low miR-29c levels correlated with shorter relapse-free survival of non-small cell lung carcinoma patients treated with radiotherapy. Together, these results indicate a new role of miR-29c in radioresistance, highlighting their potential as a novel biomarker for outcomes of radiotherapy in lung cancer.

Decreased expression of miR-939 contributes to chemoresistance and metastasis of gastric cancer via dysregulation of SLC34A2 and Raf/MEK/ERK pathway

BACKGROUND

The development of chemoresistance and metastasis are the leading causes of death for gastric cancer (GC) patients, however, the molecular mechanisms involved remain unclear. Dysregulation of miRNAs is associated with a variety of disease, including GC. Recently, microarray profiling analysis revealed that miR-939 was dysregulated in human GC samples, but the role of miR-939 in GC has not been intensively investigated.

METHODS

In the present study, we firstly examined the expression pattern of miR-939 in two independent cohorts of clinical GC samples: one cohort of 112 GC patients with stage I-III disease who underwent surgery followed by adjuvant chemotherapy; and another cohort of 110 GC patients with stage IV disease who received palliative chemotherapy. A series of in vivo and in vitro assays were then performed to investigate the function of miR-939 in GC.

RESULTS

We detected that reduced expression of miR-939 was associated with chemoresistance and increased risk of tumor recurrence in GC patients. Further function study demonstrated that overexpression of miR-939 suppressed GC cell growth, and enhanced 5-fluorouracil-induced chemosensitivity by compromising cellular growth and inducing apoptosis in vitro and in vivo. Moreover, miR-939 repressed the migration and invasion of GC cells in vitro, and diminished the occurrence of lung metastasis in vivo. We further identified solute carrier family 34 member 2 (SLC34A2) was a novel target of miR-939. Mechanistically, we elucidated that miR-939 exerted its function mainly through inhibiting SLC34A2/Raf/MEK/ERK pathway, which is activated in GC. Multivariate analysis identified miR-939, SLC34A2, and their combination as independent indicators for poor prognosis and tumor recurrence in GC patients.

CONCLUSION

Our data indicate that miR-939 acts as a tumor suppressor miRNA in GC, and miR-939/SLC34A2 axis represents a novel therapeutic strategy for future GC treatment.

MicroRNA-19b-3p regulates nasopharyngeal carcinoma radiosensitivity by targeting TNFAIP3/NF-κB axis

Background

Nasopharyngeal carcinoma (NPC) is among the most common squamous cell carcinoma in South China and Southeast Asia. Radiotherapy is the primary treatment for NPC. However, radioresistance acts as a significant factor that limits the efficacy of radiotherapy for NPC patients. Growing evidence supports that microRNAs (miRNAs) play an important role in radiation response.

Methods

Real-time quantitative PCR was used to analyze the expression of miR-19b-3p in NPC cell lines and NP69. miR-19b-3p expression profiles in NPC tissues were obtained from the Gene Expression Omnibus database. The effect of miR-19b-3p on radiosensitivity was evaluated by cell viability assays, colony formation assays and in vivo experiment. Apoptosis and cell cycle were examined by flow cytometry. Luciferase reporter assay was used to assess the target genes of miR-19b-3p. Expression of target proteins and downstream molecules were analyzed by Western blot.

Results

miR-19b-3p was upregulated in NPC and served as an independent predictor for reduced patient survival. Radioresponse assays showed that miR-19b-3p overexpression resulted in decreased sensitivity to irradiation, whereas miR-19b-3p downregulation resulted in increased sensitivity to irradiation in vitro. Moreover, miR-19b-3p decreased the sensitivity of NPC cells to irradiation in vivo. Luciferase reporter assay confirmed that TNFAIP3 was a direct target gene of miR-19b-3p. Knockdown of TNFAIP3 reduced sensitivity to irradiation, whereas upregulation of TNFAIP3 expression reversed the inhibitory effects of miR-19b-3p on NPC cell radiosensitivity. Mechanistically, we found that miR-19b-3p increased NPC cell radioresistance by activating the TNFAIP3/ NF-κB axis.

Conclusions

miR-19b-3p contributes to the radioresistance of NPC by activating the TNFAIP3/ NF-κB axis. miR-19b-3p is a determinant of NPC radioresponse and may serve as a potential therapeutic target in NPC treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0465-1) contains supplementary material, which is available to authorized users.

Down-regulation of miR-26b induces cisplatin resistance in nasopharyngeal carcinoma by repressing JAG1

Therapy against nasopharyngeal carcinoma (NPC) is hurdled by chemoresistance. Recent studies found that microRNA (miRNA) are important regulators of cancer resistance. In this study, we aimed to explore the role and mechanism of miR‐26b in regulating NPC cisplatin (CDDP) resistance. Real‐time PCR was used to evaluate miR‐26b levels in CDDP‐resistant and CDDP‐sensitive NPC cells, as well as human NPC tissues. MiR‐26b was ectopically overexpressed in CDDP‐resistant cells, followed by monitoring changes in cell viability and apoptosis. Interaction between JAG1 and miR‐26b was characterized by dual‐luciferase reporter assay. Furthermore, we investigated whether ectopic JAG1 expression reversed CDDP sensitivity induced by miR‐26b overexpression. The effect of FOXD3 down‐regulation on miR‐26b was also evaluated. Our results indicate that miR‐26b was lower in the CDDP‐resistant NPC cells, human NPC tissue, particularly in secondary metastases. Ectopic expression of miR‐26b sensitized NPC cells to CDDP. JAG1 is a target of miR‐26b, and its expression is inversely correlated with miR‐26b. Overexpression of JAG1 reversed the CDDP sensitivity induced by miR‐26b overexpression. FOXD3 expression was also down‐regulated in CDDP‐resistant NPC. FOXD3 promoted miR‐26b expression and down‐regulation of FOXD3 suppressed miR‐26b expression. Down‐regulation of miR‐26b is closely correlated with the CDDP resistance in NPC.

RBM24 suppresses cancer progression by upregulating miR-25 to target MALAT1 in nasopharyngeal carcinoma

Abnormal interaction between non-coding RNAs has been demonstrated to be a common molecular event in various human cancers, but its significance and underlying mechanisms have not been well documented. RNA-binding proteins (RBPs) are key regulators of RNA transcription and post-transcriptional processing. In this study, we found that RNA-binding protein 24 (RBM24) was frequently downregulated in nasopharyngeal carcinoma (NPC). The restoration of RBM24 expression suppressed NPC cellular proliferation, migration and invasion and impeded metastatic colonization in mouse models. Microarray analyses revealed that miR-25 expression was upregulated by RBM24 expression in NPC cells. Similarly, ectopic miR-25 expression suppressed NPC cellular growth and motility by targeting the pro-oncogenic lncRNA MALAT1, and the knockdown of MALAT1 expression exhibited similar effects as RBM24 restoration in NPC cells. Overall, these findings suggest a novel role of RBM24 as a tumor suppressor. Mechanistically, RBM24 acts at least in part through upregulating the expression of miR-25, which in turn targets MALAT1 for degradation.

Distinctive pattern of let-7 family microRNAs in aggressive carcinoma of the oral tongue in young patients

Oral cavity squamous cell carcinoma may be more aggressive at presentation and recurrence in young patients compared with older patients. Dysregulation of microRNAs (miRNAs or miRs) has been associated with the development and prognosis of oral cavity cancer. The present study investigated miRNA expression in carcinoma of the oral tongue in young patients. miRNA expression profiles were evaluated in formalin-fixed, paraffin-embedded samples of tumor and normal mucosa from 12 patients aged <30 years old with squamous cell carcinoma of the tongue. The levels of let-7f-5p, miR-30b-5p and let-7e-5p were upregulated in tumors (P<0.05). The expression of let-7f-5p was upregulated in non-aggressive tumors, while the expression of let-7e-5p was upregulated in aggressive tumors, compared with the corresponding normal tissue. Aggressive tumors had higher levels of let-7c, miR-130a-3p, miR-361-5p, miR-99a-5p, miR-29c-3p and let-7d-5p than non-aggressive tumors (P<0.05). The findings remained significant for let-7c upon false-discovery rate correction. An excellent correlation was noticed on validation of NanoString counts by quantitative polymerase chain reaction. The comparison with published findings in adults demonstrated a unique miRNA signature in young patients with aggressive disease. Aggressive oral cavity cancer in patients <30 years old is associated with a distinctive expression pattern of the let-7 family. Larger studies including direct comparison with older patients are warranted.

MicroRNA-101 inhibits cell progression and increases paclitaxel sensitivity by suppressing MCL-1 expression in human triple-negative breast cancer

Triple-negative breast cancer is the most aggressive breast cancer subtype. The aim of our study was to investigate the functional role of both miR-101 and MCL-1 in the sensitivity of human triple-negative breast cancer (TNBC) to paclitaxel. We found that the expression of miR-101 was strongly decreased in triple-negative breast cancer tissues and cell lines. The expression of miR-101 was not associated with clinical stage or lymph node infiltration in TNBC. Ectopic overexpression of miR-101 inhibit growth and induced apoptosis in vitro and suppressed tumorigenicity in vivo. MCL-1 was significantly overexpressed in most of the TNBC tissues and cell lines. Luciferase assay results confirmed MCL-1 as a direct target gene of miR-101. MiR-101 inhibited MCL-1 expression in TNBC cells and transplanted tumors. There was a negative correlation between the level of expression of miR-101 and MCL-1 in TNBC tissues. Suppression of MCL-1 enhanced the sensitivity of MDA-MB-435 cells to paclitaxel. Furthermore, miR-101 increased paclitaxel sensitivity by inhibiting MCL-1 expression. Our findings provide significant insight into the molecular mechanisms of TNBC carcinogenesis and may have clinical relevance for the development of novel, targeted therapies for TNBC.

MicroRNAs serving as potential biomarkers and therapeutic targets in nasopharyngeal carcinoma: A critical review

Despite significant medical advancement, nasopharyngeal carcinoma (NPC) remains one of the most difficult cancers to detect and treat where it continues to prevail especially among the Asian population. miRNAs could act as tumour suppressor genes or oncogenes in NPC. They play important roles in the pathogenesis of NPC by regulating specific target genes which are involved in various cellular processes and pathways. In particular, studies on miRNAs related to the Epstein Barr virus (EBV)-encoded latent membrane protein one (LMP1) and EBVmiRNA- BART miRNA confirmed the link between EBV and NPC. Both miRNA and its target genes could potentially be exploited for prognostic and therapeutic strategies. They are also important in predicting the sensitivity of NPC to radiotherapy and chemotherapy. The detection of stable circulating miRNAs in plasma of NPC patients has raised the potential of miRNAs as novel diagnostic markers. To conclude, understanding the roles of miRNA in NPC will identify ways to improve the management of patients with NPC.

A suppressive role of ionizing radiation-responsive miR-29c in the development of liver carcinoma via targeting WIP1

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related deaths worldwide, and it has been linked to radiation exposure. As a well-defined oncogene, wild-type p53-induced phosphatase 1 (WIP1) plays an inhibitory role in several tumor suppressor pathways, including p53. WIP1 is amplified and overexpressed in many malignancies, including HCC. However, the underlying mechanisms remain largely unknown. Here, we show that low-dose ionizing radiation (IR) induces miR-29c expression in female mouse liver, while inhibiting its expression in HepG2, a human hepatocellular carcinoma cell line which is used as a model system in this study. miR-29c expression is downregulated in human hepatocellular carcinoma cells, which is inversely correlated with WIP1 expression. miR-29c attenuates luciferase activity of a reporter harboring the 3'UTR binding motif of WIP1 mRNA. Ectopic expression of miR-29c significantly represses cell proliferation and induces apoptosis and G1 arrest in HepG2. In contrast, the knockdown of miR-29c greatly enhances HepG2 cell proliferation and suppresses apoptosis. The biological effects of miR-29c may be mediated by its target WIP1 which regulates p53 activity via dephosphorylation at Ser-15. Finally, fluorescence in situ hybridization (FISH) and immunohistochemical analyses indicate that miR-29c is downregulated in 50.6% of liver carcinoma tissues examined, whereas WIP1 is upregulated in 45.4% of these tissues. The expression of miR-29c inversely correlates with that of WIP1 in HCC. Our results suggest that the IR-responsive miR-29c may function as a tumor suppressor that plays a crucial role in the development of liver carcinoma via targeting WIP1, therefore possibly representing a target molecule for therapeutic intervention for this disease.

MiR-29c regulates the expression of miR-34c and miR-449a by targeting DNA methyltransferase 3a and 3b in nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is prevalent in South East Asia and Southern China particularly, despite the reported 5-year survival ratio is relative higher than other deadly cancers such as liver, renal, pancreas cancer, the lethality is characterized by high metastatic potential in the early stage and high recurrence rate after radiation treatment. MicroRNA-29c was found to be down-regulated in the serum as well as in the tissue of nasopharyngeal carcinoma tissue.

METHODS

In this study, we found accidentally that the transfection of pre-miR-29c or miR-29c mimics significantly increases the expression level of miR-34c and miR-449a but doesn't affect that of miR-222 using real-time quantitative PCR in nasopharyngeal carcinoma cell lines. To explore the molecular mechanism of the regulatory role, the cells are treated with 5-Aza-2-deoxycytidine (5-Aza-CdR) treatment and the level of miR-34c and miR-449a but not miR-222 accumulated by the treatment. DNA methyltransferase 3a, 3b were down-regulated by the 5-Aza-CdR treatment with western blot and real-time quantitative PCR.

RESULTS

We found that pre-miR-29c or miR-29c mimics significantly increases the expression level of miR-34c and miR-449a. We further found DNA methyltransferase 3a and 3b are the target gene of miR-29c. Restoration of miR-29c in NPC cells down-regulated DNA methyltransferase 3a, 3b, but not DNA methyltransferase T1.

CONCLUSIONS

The regulation of miR-29c/DNMTs/miR-34c\449a is an important molecular axis of NPC development and targeting DNMTs or restoring of miR-29c might be a promising therapy strategy for the prevention of NPC.

MiR-24 enhances radiosensitivity in nasopharyngeal carcinoma by targeting SP1

Radioresistance remains a major problem in the treatment of patients suffering from nasopharyngeal carcinoma (NPC). A better understanding of the mechanisms of radioresistance may generate new strategies to improve NPC patients' responses to therapy. This study was designed to investigate the effect of microRNA on the radiosensitivity of NPC cells. A microRNA microarray indicated that miR‐24 was downregulated in NPC cell lines and tissues. Furthermore, cell proliferation was suppressed and radiosensitivity increased when miR‐24 was ectopically expressed in NPC cells. Specificity protein 1 (SP1) was additionally verified as a direct functional target of miR‐24, which was found to be involved in cell viability as well as the radiosensitivity of NPC cells. In conclusion, the results of this study suggest that the miR‐24/SP1 pathway contributed to the reduction in radioresistance in human NPC and that it may thus represent a therapeutic target.

Circulating microRNA-125b and microRNA-130a expression profiles predict chemoresistance to R-CHOP in diffuse large B-cell lymphoma patients

Numerous studies have reported the aberrant expression profiles of microRNAs (miRNAs) in diffuse large B-cell lymphoma (DLBCL), although very few of these studies were concerned with chemoresistance to R-CHOP in DLBCL patients. This study was designed to assess the correlation between circulating miRNA expression and chemoresistance and prognosis in DLBCL patients. At the start of the study, we demonstrated that miRNA expression levels in serum were significantly associated with those in formalin-fixed, paraffin-embedded tissues, which indicated that circulating miRNAs may be powerful, non-invasive biomarkers reflecting miRNAs levels isolated from tumor tissue. Then from eight potential drug-resistant miRNAs which were deregulated in DLBCL and which had been reported to be associated with drug resistance in other carcinomas, we screened out the circulating miR-125b and miR-130a, which may related to R-CHOP resistance. Dynamic monitoring of the levels of circulating miR-125b and miR-130a further demonstrated that they were involved in recurrence, progression and chemoresistance in DLBCL patients. Finally, we demonstrated that high miR-125b indicated poor prognosis, as patients with higher miR-125b levels had a shorter overall survival. To our knowledge, this is the first study demonstrating that miR-125b and miR-130a are associated with the risk of chemoresistance in DLBCL patients, and that dynamic monitoring of the levels of circulating miR-125b and miR-130a predicts the therapeutic response and disease status of DLBCL patients.

c-Myc-miR-29c-REV3L signalling pathway drives the acquisition of temozolomide resistance in glioblastoma

Resistance to temozolomide poses a major clinical challenge in glioblastoma multiforme treatment, and the mechanisms underlying the development of temozolomide resistance remain poorly understood. Enhanced DNA repair and mutagenesis can allow tumour cells to survive, contributing to resistance and tumour recurrence. Here, using recurrent temozolomide-refractory glioblastoma specimens, temozolomide-resistant cells, and resistant-xenograft models, we report that loss of miR-29c via c-Myc drives the acquisition of temozolomide resistance through enhancement of REV3L-mediated DNA repair and mutagenesis in glioblastoma. Importantly, disruption of c-Myc/miR-29c/REV3L signalling may have dual anticancer effects, sensitizing the resistant tumours to therapy as well as preventing the emergence of acquired temozolomide resistance. Our findings suggest a rationale for targeting the c-Myc/miR-29c/REV3L signalling pathway as a promising therapeutic approach for glioblastoma, even in recurrent, treatment-refractory settings.

MicroRNAs in nasopharyngeal carcinoma

MicroRNAs (miRNAs) provide insight into both the biology and clinical behavior of many human cancers, including nasopharyngeal carcinoma (NPC). The dysregulation of miRNAs in NPC results in a variety of tumor-promoting effects. Furthermore, several miRNAs are prognostic markers for NPC. In addition to cellular miRNAs, NPC samples also often contain miRNAs encoded by Epstein-Barr virus, and these miRNAs may impact NPC biology by targeting both cellular and viral genes. Given their numerous putative roles in NPC development and progression, a thorough understanding of the impact of miRNA dysregulation in NPC is expected to shed light on useful biomarkers and therapeutic targets for the clinical management of this disease. In this review, we describe the efforts to date to identify and characterize such miRNAs in the context of NPC.

MicroRNA-338 inhibits migration and proliferation by targeting hypoxia-induced factor 1α in nasopharyngeal carcinoma

Nasopharyngeal cancer (NPC) is an endemic type of head and neck cancer with a high rate of cervical lymph node metastasis. An increasing number of studies have shown that microRNAs (miRNAs) play a key role in the development and progression of NPC. miR-338-3p has been demonstrated as an anti-oncogene in different solid tumors. The aim of the present study was to investigate the potential role of miR‑338-3p in the development and progression of NPC. Compared with normal samples, our data showed that miR-338-3p were downregulated in NPC tissues and cells. The luciferase assay demonstrated that HIF-1α was a direct target of miR-338-3p. We also found that miR-338-3p regulated the expression levels of HIF-1α, respectively. Overexpression of miR-338-3p in NPC cells significantly inhibited cell proliferation, and migration. Conversely, miR-338-3p knockdown in cells with lower endogenous expression levels significantly reduced antitumor behavior. Furthermore, enforced expression of miR-338-3p led to a decline in ERK phosphorylation as well as inhibited the hypoxia induced epithelial to mesenchymal transition. Cells pre-transfected with miR-338-3p can overcome hypoxia-mediated cisplatin resistance. Taken together, we found that miR-338-3p directly targeted HIF-1α, and we provide insight into NPC initiation and progression, possibly representing a novel therapeutic target.

MicroRNA-4649-3p inhibits cell proliferation by targeting protein tyrosine phosphatase SHP-1 in nasopharyngeal carcinoma cells

The present study aimed to investigate the influence of microRNA-4649-3p on nasopharyngeal carcinoma (NPC) cell proliferation and how it regulated SHP-1 expression. The online software TargetScan was used to predict the microRNAs targeting SHP-1 and identified that miR-4649-3p was one of the possible miRNAs targeting SHP-1. Subsequently, quantitative polymerase chain reaction (PCR) was used to detect the expression level of miR-4649-3p and SHP-1 mRNA in different NPC cell lines. The miR-4649-3p mimics and inhibitors were transfected into NPC cells and cell proliferation was examined by the MTT assay. The SHP-1 expression level was determined by PCR and western blot analysis. Lentivirus containing the SHP-1 gene and miR-4649-3p mimics was co-transfected into the NPC cells and cell proliferation was detected by the MTT assay. The expression level of miR-4649-3p and SHP-1 mRNA was negatively correlated in the NPC cell lines. miR-4649-3p mimics suppressed NPC cell proliferation whereas miR-4649-3p inhibitors promoted NPC cell proliferation. The SHP-1 expression level was suppressed when transfected with miR-4649-3p mimics in NPC cells. The miR-4649-3p inhibitors increased SHP-1 expression. The luciferase reporter assay showed that miR-4649-3p directly targeted SHP-1 by binding to the 3'-untranslated region of SHP-1 mRNA. Overexpression of SHP-1 inversed the inhibited effect of miR-4649-3p mimics on cell proliferation. In conclusion, miR-4649-3p inhibits cell proliferation by targeting SHP-1 in NPC cells.

Involvement of EBV-encoded BART-miRNAs and dysregulated cellular miRNAs in nasopharyngeal carcinoma genesis

The definite molecular mechanisms underlying the genesis of nasopharyngeal carcinomas (NPCs) remain to be completely elucidated. miRNAs are small non-coding RNAs which are implicated in cell proliferation, apoptosis, and even carcinogenesis through negatively regulating gene expression post-transcriptionally. EBV was the first human virus found to express miRNAs. EBV-encoded BART-miRNAs and dysregulated cellular miRNAs are involved in carcinogenesis of NPC by interfering in the expression of viral and host cell genes related to immune responses and perturbing signal pathways of proliferation, apoptosis, invasion, metastasis and even radio-chemo-therapy sensitivity. Additional studies on the roles of EBV-encoded miRNAs and cellular miRNAs will provide new insights concerning the complicated gene regulated network and shed light on novel strategies for the diagnosis, therapy and prognosis of NPC.

MiR-101 sensitizes human nasopharyngeal carcinoma cells to radiation by targeting stathmin 1

Radioresistance remains a major problem in the treatment of patients suffering from nasopharyngeal carcinoma (NPC). A better understanding of the mechanisms involved in the induction of radioresistance may provide strategies to improve NPC patients' response to therapy. The present study aimed to investigate the effect of microRNA (miR)-101 on the radioresistance of NPC cells. Analysis of miR-101 expression levels indicated that miR-101 was downregulated in NPC cell lines. Furthermore, ectopic expression of miR-101 suppressed cell proliferation and enhanced radiosensitivity of NPC cells. Stathmin 1 (STMN1) was additionally verified as a direct functional target of miR-101, which was found to be involved in cell viability, radioresistance and radiation-induced autophagy of NPC cells. In conclusions, the results of the present study suggested that the identified miR-101/STMN1 pathway contributed to the elucidation of the mechanisms of radioresistance in human NPC and that it may represent a potential therapeutic target.