MiR-24 enhances radiosensitivity in nasopharyngeal carcinoma by targeting SP1

MiRNA signatures in nasopharyngeal carcinoma: molecular mechanisms and therapeutic perspectives

Nasopharyngeal carcinoma (NPC) is a prevalent cancerous tumor that affects the head and neck region. Recent studies have provided compelling evidence indicating the significant involvement of microRNAs (miRNAs) in the development and progression of NPC. This review aims to present a comprehensive summary of the current knowledge regarding miRNA signatures in NPC, encompassing their expression patterns, molecular mechanisms, and potential therapeutic implications. Initially, the article outlines the aberrant expression of miRNAs in NPC and elucidates their roles in tumor initiation, invasion, and metastasis. Subsequently, the underlying molecular mechanisms of miRNA-mediated regulation of NPC-associated signaling pathways are discussed. Additionally, the review highlights the potential clinical applications of miRNAs as diagnostic and prognostic biomarkers, as well as their therapeutic potential in NPC treatment. In conclusion, this review underscores the critical involvement of miRNAs in NPC pathogenesis and underscores their promise as novel therapeutic targets for combating this devastating disease.

Genome-scale CRISPR-Cas9 knockout screening in nasopharyngeal carcinoma for radiosensitive and radioresistant genes

BACKGROUND

Genome-scale CRISPR-Cas9 knockout screening may provide new insights into the mechanism underlying clinical radioresistance in nasopharyngeal carcinoma (NPC), which is remain largely unknown. Our objective was to screen the functional genes associated with radiosensitivity and radioresistance in NPC, laying a foundation for further research on its functional mechanismand.

METHODS

CRISPR-Cas9 library lentivirus screening in radiation-treated NPC cells was combined with second-generation sequence technology to identify functional genes, which were further validated in radioresistant NPC cells and patient tissues.

RESULTS

Eleven radiosensitive and radioresistant genes were screened. Among these genes, the expression of FBLN5, FAM3C, MUS81, and DNAJC17 were significantly lower and TOMM20, CDKN2AIP, SNX22, and SP1 were higher in the radioresistant NPC cells (C666-1R, 5-8FR) (p < 0.05). CALD1 was highly expressed in C666-1R. Furthermore, we found knockout of FBLN5, FAM3C, MUS81 and DNAJC17 promoted the proliferation of NPC cells, while CDKN2AIP and SP1 had the opposed results (p < 0.05). This result was verified in NPC patient tissues. Meanwhile, KEGG analysis showed that the Fanconi anemia pathway and the TGF-β signaling pathway possibly contributed to radiosensitivity or radioresistance in NPC.

CONCLUSIONS

Nine genes involved in the radiosensitivity or radioresistance of NPC: four genes for radiosensitivity (FBLN5, FAM3C, MUS81, and DNAJC17), two genes for radioresistance (CDKN2AIP, SP1), two potential radioresistant genes (TOMM20, SNX22), and a potential radiosensitive gene (CALD1). Genome-scale CRISPR-Cas9 knockout screening for radiosensitive and radioresistant genes in NPC may provide new insights into the mechanisms underlying clinical radioresistance to improve the efficacy of radiotherapy for NPC.

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

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.

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.

MicroRNA-195-3p inhibits cyclin dependent kinase 1 to induce radiosensitivity in nasopharyngeal carcinoma

MicroRNAs (miRNAs) are revealed to participate in the progression of multiple malignancies, including nasopharyngeal carcinoma (NPC). This work is intended to decipher the function of microRNA-195-3p (miR-195-3p) in regulating the radiosensitivity of NPC cells and its mechanism. MiR-195-3p and cyclin-dependent kinase 1 (CDK1) expressions were detected in NPC tissues and cells using qRT-PCR and Western blot, respectively. Moreover, radiation-resistant cell lines were induced by continuous irradiation with different doses. Furthermore, the CCK-8 experiment, colony formation assay and flow cytometry were utilized to examine the growth, apoptosis and cell cycle of radioresistant cells. Bioinformatics prediction and dual-luciferase reporter gene assay were applied to prove the targeting relationship between miR-195-3p and CDK1 mRNA 3ʹUTR. The data showed that miR-195-3p was remarkably down-modulated in NPC tissues and was associated with increased tumor grade, lymph node metastasis and clinical stage of the patients. MiR-195-3p expression was significantly down-modulated in radiation-resistant NPC tissues and NPC cell lines relative to radiation-sensitive NPC tissues and human nasopharyngeal epithelial cells, while CDK1 expression was notably up-modulated. MiR-195-3p overexpression inhibited the growth of NPC cells, decreased radioresistance, promoted apoptosis, and impeded the cell cycle progression. CDK1 was a target gene of miR-195-3p, and CDK1 overexpression counteracted the effects of miR-195-3p on NPC cell growth, apoptosis, cell cycle progression and radiosensitivity. In summary, miR-195-3p improves the radiosensitivity of NPC cells by targeting and regulating CDK1.

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.

PLAC8 gene knockout increases the radio-sensitivity of xenograft tumors in nude mice with nasopharyngeal carcinoma by promoting apoptosis

In vitro cell experiments showed that knocking out the placenta-specific protein 8 (PLAC8) gene significantly increased the sensitivity of tumor cells to radiation. This study used two nude mouse models of nasopharyngeal carcinoma (NPC) to investigate the radio-sensitization and molecular mechanism of PLAC8 knockout in vivo. The expression of PLAC8 in 120 NPC tissues and 30 nasopharyngitis (NPG) tissues was detected by immunohistochemistry (IHC) to analyze the relationship between PLAC8 and neck lymph node metastasis and prognosis in NPC patients. The mRNA expression level of PLAC8 in several NPC cell lines was detected by semi-quantitative RT-PCR. The PLAC8 gene was knocked out in CNE-2 cells using CRISPR/Cas9. The effect of PLAC8 gene knockout on the radiotherapy sensitivity of NPC cells was analyzed by establishing model 1 and model 2 tumor-bearing nude mouse models with two different irradiation methods. The expression of γH2AX, Bax, Bcl-2, Caspase-3 and cleaved Caspase-3 was detected by immunofluorescence (IF), IHC and western blot analysis. PLAC8 expression was significantly increased in NPC tissue samples and NPC cell lines compared with NPG tissue samples and normal cell lines (P<0.01). PLAC8 upregulation was associated with lymph node metastasis and a poor prognosis in patients with NPC (P<0.01). Both animal models showed that radiotherapy after PLAC8 knockout significantly slowed tumor growth and reduced tumor volume, with tumor inhibition rates of 100% and 66.04%, respectively. In model 2, PLAC8 knockout with radiotherapy increased the expressions of γH2AX, Bax, Caspase-3 and cleaved Caspase-3 but decreased the expression of Bcl-2 (P<0.01). In model 1, there was no tumor formation at the site where the cancer cells were injected. The expression levels of γH2AX, Bax, Caspase-3 and cleaved Caspase-3 in skin tissues taken at the injection site were lower than those in NPC tissues treated with radiotherapy, while the expression level of Bcl-2 was higher (P<0.01). PLAC8 expression is closely related to neck metastasis and the prognosis of NPC. PLAC8 gene knockout significantly increases the radio-sensitivity of NPC cells in vivo by promoting apoptosis, which is an effective strategy for the radiotherapy sensitization of NPC.

Advances in research on microRNAs related to the invasion and metastasis of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC), which is associated with latent Epstein-Barr virus infection in most cases, is a unique epithelial malignancy arising from the nasopharyngeal mucosal lining. Accumulating evidence provides insights into the genetic and molecular aberrations that likely drive nasopharyngeal tumor development and progression. We review recent analyses of microRNAs (miRNAs), including Epstein-Barr virus-encoded miRNAs (EBV-encoded miRNAs) and dysregulated cellular miRNAs, that may be related to the metastasis of nasopharyngeal carcinoma. The studies summarized herein have greatly expanded our knowledge of the molecular biology of NPC involving miRNAs, and they may provide new biological targets for clinical diagnosis and reveal the potential of microRNA therapeutics. However, much information remains to be uncovered.

The Overexpression of NMHC IIA Promoted Invasion and Metastasis of Nasopharyngeal Carcinoma Cells

Background: Nasopharyngeal carcinoma (NPC) is a kind of head and neck squamous cell carcinoma (HNSCC) with a strong tendency for metastasis and recurrence. Non-muscle myosin heavy chain IIA (NMHC IIA) plays important roles in recurrence and metastasis of cancers. However, the function and mechanism of NMHC IIA expression in NPC remain unclear. Methods: A receiver operating characteristic (ROC) curve was constructed for 141 specimens of HNSCC tissues and 44 control samples from The Cancer Genome Atlas (TCGA) database. Co-expressed genes with MYH9 were identified using LinkedOmics. Transcription factors (TFs) and miRNA regulation network were constructed using Networkanalyst. The migration and invasion ability of nasopharyngeal carcinoma cells were evaluated by in vitro migration and matrigel invasion assays, respectively. Results: The public microarray results showed that MYH9 expression levels were upregulated in HNSCC tissues compared with the matched adjacent normal tissues in this study (p<0.0001). The AUC of MYH9 reached up to 0.8303 at a cutoff value of 175.2, with a sensitivity and specificity of 70.21% and 86.36%, respectively. MYH9 expression was increased in lymph node metastasis HNSCC tumors compared with that in tumors without lymph node metastasis (p<0.05) and showed a strong positive association with expression of FLNA. High MYH9 and FLNA expression were related with poorer overall survival in HNSCC. MYH9 with positively associated genes regulated focal adhesion, cell-substrate junction assembly and cell morphogenesis were involved in differentiation using GO and KEGG analysis. MYH9 was correlated with a network of TFs including SP1, SRF, JUN and FOS in HNSCC. The suppression of endogenous NMHC IIA decreased cellular migration and invasion in HNE1 cells and reduced the expression of phosphorylation of EGFR, AKT and ERK. The over-expression of NMHC IIA increased cellular migration and invasion in COS-7 cells and increased the expression of phosphorylation of EGFR, AKT and ERK. Conclusion: Expression of NMHC IIA mRNA was higher in HNSCC than in the adjacent normal tissues. NMHC IIA expression was increased in lymph node metastasis HNSCC tumors compared with tumors without lymph node metastasis. High MYH9 was association with poorer overall survival in HNSCC. NMHC IIA expression increased the invasion and metastasis abilities of the nasopharyngeal cancer cell line in vitro by augmenting the expression of phosphorylation of EGFR, AKT and ERK. These findings will be beneficial for providing an effectively therapeutic strategy for NPC.

FOXD1, negatively regulated by miR-186, promotes the proliferation, metastasis and radioresistance of nasopharyngeal carcinoma cells

BACKGROUND

Foxhead box D1 (FOXD1) is validated to be over-expressed in a variety of human malignancies and promotes cancer progression. Nevertheless, the role of FOXD1 and the associated mechanism in nasopharyngeal carcinoma (NPC) remain largely unknown.

METHODS

A total of seventy-five cases of NPC tissue samples were collected. FOXD1 expression in NPC tissues and cells (SUNE1, CNE1, CNE2, and HONE1) was detected using immunohistochemistry and Western blot, respectively. The relationship between FOXD1 expression and clinicopathological parameters of NPC patients was analyzed. FOXD1 mRNA and miR-186 expression in NPC tissues and cells was detected using quantitative polymerase chain reaction (qPCR). The cell viability of NPC cells was detected using CCK-8 assay. Colony survival of NPC cells exposed to different doses of radiation was detected using colony formation assay. Transwell assay was used to evaluate the migration and invasion of NPC cells. The dual-luciferase reporter gene assay was employed to verify the targeting relationship between miR-186 and FOXD1.

RESULTS

FOXD1 was over-expressed in NPC tissues (average fold change on mRNA level = 4.72), and its high expression was correlated to NPC positive lymph node metastasis and tissue differentiation. The over-expression of FOXD1 promoted the proliferation, migration, invasion and radio-resistance of NPC cells. On the contrary, the knock-down of FOXD1 inhibited the malignant phenotypes of the above cells. It was verified that FOXD1 was one of the downstream targets of miR-186 and was negatively regulated by it.

CONCLUSION

FOXD1, which is negatively regulated by miR-186, acts as a novel oncogene in NPC and serves as potential biomarker and therapeutic target for NPC. The research will provide great theoretical basis for further clinical diagnosis and therapy.

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.

Inhibition of cell proliferation and radioresistance by miR-383-5p through targeting RNA binding protein motif (RBM3) in nasopharyngeal carcinoma

Background

RNA binding protein motif (RBM3) is associated with radioresistance in nasopharyngeal carcinoma (NPC), and miR-383-5p was predicted to target the 3'-untranslated region (3'UTR) of RBM3 messenger RNA (mRNA). Our study aimed to investigate the role and the mechanisms of miR-383-5p targeting RBM3 in NPC cell proliferation and radioresistance (RR).

Methods

The expression of miR-383-5p was detected by Real-time quantitative PCR (qRT-PCR) between RS (Radiosensitivity) and RR (Radioresistance) NPC patient- tissue specimens and cell lines. Cell Counting Kit-8 (CCK-8) and Clonogenic survival assay were applied to analyze the effect of miR-383-5p on NPC cell proliferation and radioresistance. Possible downstream target of miR-383-5p in NPC cells, RBM3was evaluated by luciferase assay and qRT-PCR. miR-383-5p inhibited NPC cell proliferation and radioresistance through RBM3 by rescue experiments. The effect of miR-383-5p on radiation-induced apoptosis was explored through Flow cytometric analysis and Western blotting. Western blotting was analyzed the molecular of RBM3-mediated Jun N-terminal kinase (JNK) and extracellular signal-related kinase (ERK) signaling pathways

Results

The expression of miR-383-5p was decreased in radioresistant NPC tissues and cells. miR-383-5p inhibited cell proliferation and radioresistance in CNE1/IR cells. We also observed that therapeutic administration of a miR-383-5p agomir dramatically sensitized NPC xenografts to radiation in a mouse model. Conversely, in the same xenograft model, administration of a miR-383-5p antagomir dramatically increased NPC resistance to radiation. miR-383-5p targeted the 3'UTR of RBM3. miR-383-5p inhibited NPC cell proliferation and radioresistance through RBM3. Finally, we found that miR-383-5p increased radiation-induced apoptosis, activated JNK signaling, and inhibited ERK signaling.

Conclusions

Our study revealed that miR-383-5p targeted the 3'UTR of RBM3 and contributed to the efficacy of NPC radiation therapy by altering the RBM3-mediated JNK and ERK signaling pathways.

miR-4270 Modulates the Irradiation-Sensitivity of Nasopharyngeal Carcinoma Cells through Modulation of p53 in Vivo

The lowered sensitivity to irradiation considerably impacted on the prognosis of nasopharyngeal carcinoma treatments. This study aimed to explore the functions of miR-4270 in nasopharyngeal carcinoma. Bioinformatic analysis was performed online accessing GSE139164 dataset to screen the top 30 differential microRNAs in nasopharyngeal carcinoma patients with radio-sensitivity. Cancer cell lines, 6-10B and 5-8F, were cultured and measured for expression of miR-4270 and TP53 (the gene of the tumor suppressor protein p53) with the normal nasopharyngeal epithelial cells as a control. The miR-4270 expression was regulated in cells via the introduction of miR-4270 inhibitor or mimic in different concentrations (25, 50, 100 nmol/L). Targetscan predicted the target of miR-4270 and the bindings while luciferase was used to confirm this. CCK8 methods were used to evaluate the irradiation sensitivity of the cells after exposure to increasing X-Ray irradiation. RT-PCR detected the RNA expression and Western blot examined the protein expression of p53. Flow cytometry detected the cell apoptosis rates respectively. miR-4270 is among the top differential microRNAs between the radio-sensitive and -resistant patients. In vivo, miR-4270 expression was lower in cancer cell lines. The inhibition of miR-4270 raised the cell sensitivity to irradiation. miR-4270 negatively mediated TP53 and targeted TP53. Additionally, p53 increased cell sensitivity to irradiation and modulated by miR-4270 in nasopharyngeal carcinoma cells. In conclusion, this study first reports that miR-4270 is lower in the radio-sensitive patients and modulated the irradiation-sensitivity of nasopharyngeal carcinoma cells through modulation of p53 in vivo.

Emerging role of non-coding RNAs in response of cancer cells to radiotherapy

Radiotherapy is an effective method for treatment of a large proportion of human cancers. Yet, the efficacy of this method is precluded by the induction of radioresistance in tumor cells and the radiation-associated injury of normal cells surrounding the field of radiation. These restrictions necessitate the introduction of modalities for either radiosensitization of cancer cells or protection of normal cells against adverse effects of radiation. Non-coding RNAs (ncRNAs) have essential roles in the determination of radiosensitivity. Moreover, ncRNAs can modulate radiation-induced side effects in normal cells. Several microRNAs (miRNAs) such as miR-620, miR-21 and miR-96-5p confer radioresistance, while other miRNAs including miR-340/ 429 confer radiosensitivity. The expression levels of a number of miRNAs are associated with radiation-induced complications such as lung fibrosis or oral mucositis. The expression patterns of several long non-coding RNAs (lncRNAs) such as MALAT1, LINC00630, HOTAIR, UCA1 and TINCR are associated with response to radiotherapy. Taken together, lncRNAs and miRNAs contribute both in modulation of response of cancer cells to radiotherapy and in protection of normal cells from the associated side effects. The current review provides an overview of the roles of these transcripts in these aspects.

Human Papillomavirus Infection in Head and Neck Squamous Cell Carcinomas: Transcriptional Triggers and Changed Disease Patterns

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of cancers. Collectively, HNSCC ranks sixth in incidence rate worldwide. Apart from classical risk factors like tobacco and alcohol, infection of human papillomavirus (HPV) is emerging as a discrete risk factor for HNSCC. HPV-positive HNSCC represent a distinct group of diseases that differ in their clinical presentation. These lesions are well-differentiated, occur at an early age, and have better prognosis. Epidemiological studies have demonstrated a specific increase in the proportions of the HPV-positive HNSCC. HPV-positive and HPV-negative HNSCC lesions display different disease progression and clinical response. For tumorigenic-transformation, HPV essentially requires a permissive cellular environment and host cell factors for induction of viral transcription. As the spectrum of host factors is independent of HPV infection at the time of viral entry, presumably entry of HPV only selects host cells that are permissive to establishment of HPV infection. Growing evidence suggest that HPV plays a more active role in a subset of HNSCC, where they are transcriptionally-active. A variety of factors provide a favorable environment for HPV to become transcriptionally-active. The most notable are the set of transcription factors that have direct binding sites on the viral genome. As HPV does not have its own transcription machinery, it is fully dependent on host transcription factors to complete the life cycle. Here, we review and evaluate the current evidence on level of a subset of host transcription factors that influence viral genome, directly or indirectly, in HNSCC. Since many of these transcription factors can independently promote carcinogenesis, the composition of HPV permissive transcription factors in a tumor can serve as a surrogate marker of a separate molecularly-distinct class of HNSCC lesions including those cases, where HPV could not get a chance to infect but may manifest better prognosis.

Effects of Dicer1 targeted by EBV-miR-BART6-5p on biological properties and radiosensitivity of nasopharyngeal carcinoma

OBJECTIVE

To discuss the effects of Epstein-Barr virus (EBV)-encoded BamHI A rightward transcript (BART) microRNA (miR-BART6-5p) by targeting Dicer1 on biological properties and radiosensitivity of nasopharyngeal carcinoma (NPC).

METHODS

NPC patients (n = 96) treated with radiotherapy were collected from Jan 2010 to Jan 2011. Real-time quantitative PCR (qRT-PCR) and western blot were carried out to measure the expression of miR-BART6-5p and Dicer1. Dual luciferase reporter gene assay verified that miR-BART6-5p targeted Dicer1. CCK8, wound-healing, Transwell and Annexin-FITC/PI were employed to evaluate the effects of Dicer1 mediated by miR-BART6-5p on biological characteristics of NPC cells. The radiosensitivity of miR-BART6-5p targeting Dicer1 was assessed in vitro and in vivo.

RESULTS

Increased miR-BART6-5p and decreased Dicer1 were discovered in NPC patients, displaying a close association with T-stage, clinical stage, as well as Pre-DNA of NPC. While elevated Dicer1 and miR-BART6-5p down-regulation in NPC patients were found after effective radiotherapy. Both miR-BART6-5p and Dicer1 were prognostic factors of NPC. Down-regulation of miR-BART6-5p could enhance Dicer1 expression and inhibit NPC cell proliferation, invasion and migration with promoted apoptosis. Clone formation assay also showed miR-BART6-5p down-regulation reduced planting efficiency (PE), which further decreased with the increased dose of irradiation. Injection with miR-BART6-5p inhibitors in nude mice after 6-Gy irradiation contributed to the overexpression of Dicer1 and the inhibition of tumor growth.

CONCLUSIONS

EBV-miR-BART6-5p may target Dicer1 to facilitate proliferation and metastasis of NPC cells and suppress apoptosis, thus being a new target for NPC therapy.

miR‑7/SP1/TP53BP1 axis may play a pivotal role in NSCLC radiosensitivity

MicroRNA‑7 (miR‑7) has been identified as a tumor suppressor in non‑small cell lung cancer (NSCLC) and a radiosensitivity regulator. Numerous studies have revealed that specific protein 1 (SP1) plays a critical role in the tumorigenesis of various types of cancers and regulates radiosensitivity and tumor suppressor p53‑binding protein 1 (TP53BP1), which plays an essential role in DNA repair. However, it is not clear whether miR‑7 has a regulatory effect on SP1 and TP53BP1 in NSCLC. In the present study it was revealed that miR‑7 directly binds to the 3'UTR of SP1, thereby suppressing SP1 expression to regulate radiosensitivity. Overexpression of miR‑7 and SP1 and knockdown of miR‑7 and SP1 were performed using lentiviral transfection. Protein and mRNA abundance of SP1 and TP53BP1 were determined using western blotting and RT‑qPCR, respectively, while miR‑7 binding to SP1 was validated using a luciferase reporter assay. Biological function analysis indicated that miR‑7 negatively regulated SP1 and inhibited cell proliferation, migration, and invasion when combined with radiation. It was also revealed that the expression of TP53BP1 was positively regulated by SP1 or negatively regulated by miR‑7. In conclusion, SP1 was a target of miR‑7, and the decreased expression of SP1 resulting from miR‑7 overexpression in NSCLC was vital for improving radiosensitivity in NSCLC cells. Moreover, SP1 expression was detected in 95 paired NSCLC and adjacent normal tissues, and it was determined that SP1 was significantly upregulated in NSCLC tissues and that its upregulation was correlated with the degree of tissue differentiation. Thus, SP1 and/or miR‑7 may be potential molecular targets in NSCLC radiotherapy.

lncRNA CASC2 Enhances 131I Sensitivity in Papillary Thyroid Cancer by Sponging miR-155

Long noncoding RNA cancer susceptibility candidate 2 (CASC2) has been reported to play an anticancer role in papillary thyroid cancer (PTC). Radioiodine (¹³¹I) is a common option for the treatment of PTC. However, the role and mechanism of CASC2 in ¹³¹I sensitivity remain unclear. In this study, ¹³¹I-resistant cells were constructed through continuous treatment of ¹³¹I. The expression levels of CASC2 and miR-155 were measured by qRT-PCR. The IC50 of ¹³¹I was analyzed by cell viability using MTT assay. Flow cytometry was conducted to determine cell apoptosis induced by ¹³¹I. The association between CASC2 and miR-155 was evaluated by luciferase assay and RNA immunoprecipitation. A mouse xenograft model was built to explore the effect of CASC2 on the growth of ¹³¹I-resistant PTC cells in vivo. Results showed that CASC2 expression was decreased in PTC tissues and cells, and low expression of CASC2 was associated with poor outcome of patients. CASC2 level was reduced in ¹³¹I-resistant cells. Knockdown of CASC2 inhibited ¹³¹I sensitivity in thyroid cancer cells. Overexpression of CASC2 enhanced ¹³¹I sensitivity in constructed resistant PTC cells. CASC2 was a decoy of miR-155, and CASC2-mediated promotion of ¹³¹I sensitivity was weakened by decreasing miR-155. Abundance of CASC2 inhibited the growth of ¹³¹I-resistant cells in vivo. As a conclusion, CASC2 increases ¹³¹I sensitivity in PTC by sponging miR-155, providing a novel target for the treatment of thyroid cancer patients with ¹³¹I resistance.

MicroRNA-24 in Cancer: A Double Side Medal With Opposite Properties

MicroRNA-24 (miR-24) has been widely studied in a variety of human cancers, which plays different roles in specific type of cancers. In the present review, we summarized the recent surveys regarding the role of miR-24 in different human cancers. On the one hand, miR-24 was reported to be down-regulated in some types of cancer, indicating its role as a tumor suppressor. On the other hand, it has shown that miR-24 was up-regulated in some other types of cancer, even in the same type of cancer, suggesting the role of miR-24 being as an oncogene. Firstly, miR-24 was dysregualted in human cancers, which is related to the clinical performance of cancer patients. Thus miR-24 could be used as a potential non-invasive diagnostic marker in human cancers. Secondly, miR-24 was associated with the tumor initiation and progression, being as a promoter or inhibitor. Therefore, miR-24 might be an effective prognostic biomarker in different type of cancers. Lastly, the abnormal expression of miR-24 was involved in the chemo- and radio- therapies of cancer patients, indicating the role of miR-24 being as a predictive biomarker to cancer treatment. Totally, miR-24 contributes to tumorigenesis, tumor progression, and tumor therapy, which closely related to clinic. The present review shows that miR-24 plays a double role in human cancers and provides plenty of evidences to apply miR-24 as a potential novel therapeutic target in treating human cancers.

MicroRNAs: Biogenesis, Functions and Potential Biomarkers for Early Screening, Prognosis and Therapeutic Molecular Monitoring of Nasopharyngeal Carcinoma

According to reports published, the aberrant expression of microRNAs (miRNAs), a class of 19–25 nucleotide-long small non-coding RNAs, is responsible for human cancers, including nasopharyngeal cancer (NPC). The dysregulation of miRNAs that act either as a tumor suppressor or oncogene, leading to a wide range of NPC pathogenesis pathways, includes the proliferation, invasion, migration as well as the metastasis of NPC cells. This article reviews and highlights recent advances in the studies of miRNAs in NPC, with a specific demonstration of the functions of miRNA, especially circulating miRNAs, in the pathway of NPC pathogenesis. Additionally, the possible use of miRNAs as early screening and prognostic biomarkers and for therapeutic molecular monitoring has been extensively studied.

Metformin enhances radiosensitivity in hepatocellular carcinoma by inhibition of specificity protein 1 and epithelial-to-mesenchymal transition

Objective

Radiotherapy becomes more and more important in hepatocellular carcinoma (HCC) due to the development of technology, especially in unresectable cases. Metformin has a synergistic benefit with radiotherapy in some cancers, but remains unclear in HCC. This study aims to investigate the effect of metformin on radiosensitivity of HCC cells and the roles of specificity protein 1 (Sp1) as a target of metformin.

Methods

The SMMC-7721 cell line was exposed to various doses of γ-ray irradiation (0, 2, 4, 6, and 8 Gy) and with or without different concentrations of metformin (0, 1, 5, 10, and 20 mM) to measure the radiosensitivity using MTT assay. Flow cytometry was used to determine cell cycle by propidium iodide (PI) staining and apoptosis by Hoechst 33342/PI staining and Annexin V-FITC/PI staining. Real-time polymerase chain reaction and Western blotting were performed to analyze the Sp1 mRNA and protein expressions of Sp1 and epithelial-to-mesenchymal transition (EMT) marker E-cadherin and Vimentin. The invasion capability was measured by the Boyden chamber assay.

Results

In SMMC-7721 cells exposed to irradiation, metformin reduced proliferation and survival cells at various concentrations (0, 1, 5, 10, and 20 mM) and induced cell cycle arrest, apoptosis, and inhibited invasion. In SMMC-7721 cells with irradiation, the mRNA and protein expressions of Sp1 were significantly decreased by metformin as well as a selective Sp1 inhibitor. Metformin attenuated transforming growth factor-β1 induced decrease of E-cadherin and increase of Vimentin proteins.

Conclusion

Metformin demonstrated enhanced radiosensitivity and inhibition of EMT in HCC cells. Sp1 might be a target of metformin in radiosensitization.

Multiple Mechanisms Involving in Radioresistance of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is the malignant tumor with ethnic and geographical distribution preference. Although intensity-modulated radiotherapy (IMRT)-based radiotherapy combined with chemotherapy and targeted therapy has dramatically improved the overall survival of NPC patients, there are still some patients suffering from recurrent tumors and the prognosis is poor. Multiple mechanisms may be responsible for radioresistance of NPC, such as cancer stem cells (CSCs) existence, gene mutation or aberrant expression of genes, epigenetic modification of genes, abnormal activation of certain signaling pathways, alteration of tumor microenvironment, stress granules (SGs) formation, etc. We conduct a comprehensive review of the published literatures focusing on the causes of radioresistance, retrospect the regulation mechanisms following radiation, and discuss future directions of overcoming the resistance to radiation.

MiRNAs in Radiotherapy Resistance of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors of the head and neck in Southeast Asia and southern China. Although the comprehensive treatment based on intensity-modulated radiation therapy improves outcomes, the five-year survival rate of NPC patients is low, and the recurrence remains high. Radiotherapy resistance is the main cause of poor prognosis in NPC patients. MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs regulating various biological functions in eukaryotes. These miRNAs can regulate the development and progression of nasopharyngeal carcinoma by affecting the proliferation, apoptosis, movement, invasion and metastasis of NPC cells. The abnormal expression of miRNAs is closely related to radiotherapy sensitivity and prognosis of NPC patients, which can affect the transmission of related signaling pathways by regulating the expression of tumor suppressor genes and / or oncogenes, and therefore participate in radiotherapy resistance in nasopharyngeal carcinoma. Here, we review the mechanisms by which miRNAs may be involved in the radiotherapy resistance of nasopharyngeal carcinoma.

Role of non-coding RNAs and RNA modifiers in cancer therapy resistance

As the standard treatments for cancer, chemotherapy and radiotherapy have been widely applied to clinical practice worldwide. However, the resistance to cancer therapies is a major challenge in clinics and scientific research, resulting in tumor recurrence and metastasis. The mechanisms of therapy resistance are complicated and result from multiple factors. Among them, non-coding RNAs (ncRNAs), along with their modifiers, have been investigated to play key roles in regulating tumor development and mediating therapy resistance within various cancers, such as hepatocellular carcinoma, breast cancer, lung cancer, gastric cancer, etc. In this review, we attempt to elucidate the mechanisms underlying ncRNA/modifier-modulated resistance to chemotherapy and radiotherapy, providing some therapeutic potential points for future cancer treatment.

Human Papillomavirus Infection in Head and Neck Squamous Cell Carcinomas: Transcriptional Triggers and Changed Disease Patterns

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of cancers. Collectively, HNSCC ranks sixth in incidence rate worldwide. Apart from classical risk factors like tobacco and alcohol, infection of human papillomavirus (HPV) is emerging as a discrete risk factor for HNSCC. HPV-positive HNSCC represent a distinct group of diseases that differ in their clinical presentation. These lesions are well-differentiated, occur at an early age, and have better prognosis. Epidemiological studies have demonstrated a specific increase in the proportions of the HPV-positive HNSCC. HPV-positive and HPV-negative HNSCC lesions display different disease progression and clinical response. For tumorigenic-transformation, HPV essentially requires a permissive cellular environment and host cell factors for induction of viral transcription. As the spectrum of host factors is independent of HPV infection at the time of viral entry, presumably entry of HPV only selects host cells that are permissive to establishment of HPV infection. Growing evidence suggest that HPV plays a more active role in a subset of HNSCC, where they are transcriptionally-active. A variety of factors provide a favorable environment for HPV to become transcriptionally-active. The most notable are the set of transcription factors that have direct binding sites on the viral genome. As HPV does not have its own transcription machinery, it is fully dependent on host transcription factors to complete the life cycle. Here, we review and evaluate the current evidence on level of a subset of host transcription factors that influence viral genome, directly or indirectly, in HNSCC. Since many of these transcription factors can independently promote carcinogenesis, the composition of HPV permissive transcription factors in a tumor can serve as a surrogate marker of a separate molecularly-distinct class of HNSCC lesions including those cases, where HPV could not get a chance to infect but may manifest better prognosis.

MicroRNA-449b-5p suppresses cell proliferation, migration and invasion by targeting TPD52 in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an important type of head and neck malignant cancer with geographical distribution. MicroRNA-449b-5p (miR-449b-5p) is related to the development of various cancers, while its function in NPC remains unknown. The present study aimed to investigate the role and target gene of miR-449b-5p in NPC. Expressions of miR-449b-5p in NPC cell lines and clinical tissues were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was determined by MTT and colony formation assays. Migration and invasion abilities after different treatment were evaluated by wound healing and Transwell assays, respectively. Dual-luciferase reporter assay was performed to explore the relationship between miR-449b-5p and tumour protein D52 (TPD52). TPD52 expression was determined by qRT-PCR and western blot assay. miR-449b-5p was significantly downregulated in NPC cell lines and clinical tissues than the matched control. Overexpression of miR-449b-5p inhibited proliferation, migration and invasion of NPC cells. Dual-luciferase reporter assay indicated that miR-449b-5p directly targeted TPD52. Furthermore, shRNA-mediated downregulation of TPD52 rectified the promotion of cell migration and invasion by miR-449b-5p inhibition. In conclusion, the present study suggests that miR-449b-5p, as a novel tumour-suppressive miRNA against NPC, inhibits proliferation, migration and invasion of NPC cells via inhibiting TPD52 expression.

Comprehensive analysis of key genes and microRNAs in radioresistant nasopharyngeal carcinoma

Background

Radioresistance is one of the main obstacle limiting the therapeutic efficacy and prognosis of patients, the molecular mechanisms of radioresistance is still unclear. The purpose of this study was to identify the key genes and miRNAs and to explore their potential molecular mechanisms in radioresistant nasopharyngeal carcinoma.

Methods

In this study, we analysis the differentially expressed genes and microRNA based on the database of GSE48501 and GSE48502, and then employed bioinformatics to analyze the pathways and GO terms in which DEGs and DEMS target genes are involved. Moreover, Construction of protein-protein interaction network and identification of hub genes. Finally, analyzed the biological networks for validated target gene of hub miRNAs.

Results

A total of 373 differentially expressed genes (DEGs) and 14 differentially expressed microRNAs (DEMs) were screened out. The up-regulated gene JUN was overlap both in DEGs and publicly available studies, which was potentially targeted by three miRNAs, including hsa-miR-203, hsa-miR-24 and hsa-miR-31. Moreover, Pathway analysis showed that both up-regulated gene and DEMs target genes were enriched in TGF-beta signaling pathway, Hepatitis B, Pathways in cancer and p53 signaling pathway. Finally, we further constructed protein-protein interaction network (PPI) of DEGs and analyzed the biological networks for above mentioned common miRNAs, the result indicated that JUN was a core hub gene in PPI network, hsa-miR-24 and its target gene were significantly enriched in P53 signaling pathway.

Conclusions

These results might provide new clues to improve the radiosensitivity of Nasopharyngeal Carcinoma.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0507-6) contains supplementary material, which is available to authorized users.

Improved Radiotherapy Sensitivity of Nasopharyngeal Carcinoma Cells by miR-29-3p Targeting COL1A1 3'-UTR

Background

Radio-resistance is an obstacle to the treatment of human nasopharyngeal carcinoma (NPC). However, how microRNAs (miRNA) are involved in this process remains unclear. In the present study we explored the role and possible molecular mechanism of miR-29a-3p, formerly known as tumor suppressors, in radio-sensitivity of NPC cells.

Material/Methods

A radio-resistant sub-cell line, CNE-2R, was established to detect the expression of miR-29a/b/c-3p using qRT-PCR. CCK-8 assay, colony formation assay, and single-cell gel electrophoresis (SCGE) assay were carried out to analyze the radio-sensitivity of NPC cells. qRT-PCR, luciferase reporter, and Western blot experiments were performed to validate the targeting of COL1A1 by miR-29a. Short interference RNAs (siRNAs) were used to investigate whether COL1A1 mediates the radio-sensitizer role of miR-29a. Expression of miR-29a and COL1A1 in radio-resistant NPC tissues was finally determined.

Results

miR-29a was decreased in the radio-resistant CNE-2R cells. Following a time-course irradiation (IR) exposure, miR-29a exhibited a time-dependent decrease. Cellular experiments confirmed that miR-29a induced radio-sensitivity of CNE-2R cells via suppressing cell viability and enhancing cell apoptosis after IR. We confirmed that COL1A1 is a direct target of miR-29a and can exert radio-resistance effects in NPC cells. We also found that knockdown of COL1A1 inhibits NPC cell viability and sensitivity to IR. Finally, we observed a downregulation of miR-29a in radio-resistant NPC tissues and its decrease was associated with upregulation of COL1A1.

Conclusions

miR-29a is a critical determinant of NPC radio-response for NPC patients, and its induction provides a promising therapeutic choice to elevate NPC radio-sensitivity.

MicroRNA-372 enhances radiosensitivity while inhibiting cell invasion and metastasis in nasopharyngeal carcinoma through activating the PBK-dependent p53 signaling pathway

Nasopharyngeal carcinoma (NPC) is a common cancer found in the nasopharynx, which plagues countless NPC patients. MicroRNA‐372 (miR‐372) has been reported to be involved in various tumors. Here, we explored the important role of miR‐372 in radiosensitivity, invasion, and metastasis of NPC. Microarray analysis was conducted to search the NPC‐related differentially expressed genes (DEGs) and predict the miRs regulating PBK, which suggested that miR‐372 could influence the development of NPC via PBK and the p53 signaling pathway. Importantly, miR‐372 was observed to target PBK, thus down‐regulating its expression. Then, NPC 5‐8F and C666‐1 cells were selected, and treated with ionization radiation and alteration of miR‐372 and PBK expression to explore the functional role of miR‐372 in NPC. The expression of miR‐372, PBK, Bcl‐2, p53, and Bax as well as the extent of Akt phosphorylation were measured. In addition, cell colony formation, cell cycle, proliferation, apoptosis, migration, and invasion were detected. At last, tumor growth and the effect of miR‐372 on radiosensitivity of NPC were evaluated. Besides, over‐expressed miR‐372 down‐regulated Bcl‐2 and PBK expression and the extent of Akt phosphorylation while up‐regulated the expression of p53 and Bax. Additionally, miR‐372 over‐expression and radiotherapy inhibited cell clone formation, proliferation, tumor growth, migration, invasion, and cell cycle entry, but promoted cell apoptosis. However, the restoration of PBK in NPC cells expressing miR‐372 reversed the anti‐tumor effect of miR‐372 and activation of the p53 signaling pathway. In conclusion, the study shows that up‐regulated miR‐372 promotes radiosensitivity by activating the p53 signaling pathway via inhibition of PBK.

miRNA-17 promotes nasopharyngeal carcinoma radioresistance by targeting PTEN/AKT

Radioresistance remains a challenge during nasopharyngeal carcinoma (NPC) radiotherapy. Numerous studies suggest that the miRNAs may play important roles in the regulation of radioresistance. miRNA-17-5p, which is located within the miR-17-92a cluster, could modulate tumor progression in different tissues by targeting multiple tumor associated genes. However, whether it is correlated with the radioresistance of tumor cells has not yet been elucidated. In our study, we have observed increasing miR-17-5p expression in radioresistant NPC tissues. The functional experiments suggested that miR-17-5p could clearly promote NPC cell proliferation and the cell cycle even after X-ray irradiation. Irradiation leads to tumor cell damage and death via ROS generation. The overexpression of miR-17-5p could protect NPC cells from apoptosis induced by irradiation. In addition, an in vivo experiment indicated that miR-17-5p promoted tumor growth with radiotherapy using the xenograft tumor model. A bioinformatics analysis and reporter assay were carried out to demonstrate that PTEN, which is a key regulator of AKT phosphorylation, is a target of miR-17-5p. The overexpression of miR-17-5p directly suppresses the mRNA and protein expression of PTEN. In addition, the rescue experiments showed that the AKT inhibitor can diminish the proliferation, promotion, and apoptosis inhibition effects on radioresistant NPC cells mediated by miR-17-5p. In conclusion, our findings demonstrated that miR-17-5p can enhance the radioresistance of NPC through the PTEN/AKT pathway, which is a biomarker of radioresistant NPC and a potential target for new therapeutic strategies.

MicroRNA-744 promotes cell apoptosis via targeting B cell lymphoma-2 in gastric cancer cell line SGC-7901

Gastric cancer (GC) affects the health of 1,000,000 people per year worldwide; however, the biological basis of GC remains largely unknown. The current study aimed to investigate the aberrant expression of miR-744 in GC for the effective treatment of patients with GC. Tumor and adjacent tissues were obtained from 30 patients who underwent tumor resection surgery at Dongying People's Hospital. The results of reverse transcription-quantitative polymerase chain reaction indicated that the expression of miR-744 was significantly decreased in tumor tissues compared with the levels in adjacent tissues. Human gastric cancer cell line SGC-7901 was then randomly divided into three different groups, including the control, miR-negative control (NC) and miR-744 mimic groups. A Cell Counting Kit-8 assay demonstrated that there was a significant decrease in the proliferation rate of SGC-7901 cells in the miR-744 mimics group compared with that observed in the control and miR-NC mimics groups. In addition, flow cytometry demonstrated that apoptosis was significantly increased in the miR-744 mimics group compared with that observed in the control and miR-NC mimics groups. Western blotting indicated that the expression of B cell lymphoma 2 (Bcl-2), B cell lymphoma-2-associated X protein and caspase-3 protein was significantly increased, while the expression of Bcl-2 was significantly decreased in the miR-744 mimics group compared with the levels observed in the control and miR-NC mimics groups. A dual-luciferase assay verified that miR-744 directly targeted the 3'-untranslated region of Bcl-2. Taken together, the present study suggested that miR-744 serves a tumor suppressive role in GC by targeting Bcl-2.

microRNA-222 promotes tumor growth and confers radioresistance in nasopharyngeal carcinoma by targeting PTEN

MicroRNA-222 (miR‑222) has been reported to be involved in the initiation, development and metastasis of tumors, as well as conferring resistance to chemotherapeutic drugs or radiotherapy in various types of cancer. However, the role and the underlying molecular mechanism of miR‑222 specifically in nasopharyngeal carcinoma (NPC) remains unclear. Thus, the biological function and underlying mechanism of in miR‑222 was investigated in NPC tissue specimens and cell lines. miR‑222 was upregulated in NPC tissues and malignant cell lines compared with adjacent normal samples and cell lines. miR‑222 upregulation significantly increased NPC cell proliferation, colony formation and cell apoptosis. Furthermore, miR‑222 upregulation conferred radioresistance. It was also confirmed that phosphatase and tensin homolog (PTEN) was a direct target for miR‑222 in NPC cells. Alteration of miR‑222 expression was demonstrated to regulate the phosphoinositide 3‑kinase/protein kinase B pathway in NPC cells. These results suggest that miR‑222 may act as an oncomir in NPC by targeting PTEN, and has potential as a therapeutic target in NPC.

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.

MiR-130a-3p inhibits the viability, proliferation, invasion, and cell cycle, and promotes apoptosis of nasopharyngeal carcinoma cells by suppressing BACH2 expression

The aim of the present study was to explore the mechanism through which miR-130a-3p affects the viability, proliferation, migration, and invasion of nasopharyngeal carcinoma (NPC). Tissue samples were collected from the hospital department. NPC cell lines were purchased to conduct the in vitro and in vivo assays. A series of biological assays including MTT, Transwell, and wound healing assays were conducted to investigate the effects of miR-130a-3p and BACH2 on NPC cells. MiR-130a-3p was down-regulated in both NPC tissues and cell lines, whereas BACH2 was up-regulated in both tissues and cell lines. MiR-130a-3p overexpression inhibited NPC cell viability, proliferation, migration, and invasion but promoted cell apoptosis. The converse was true of BACH2, the down-regulation of which could inhibit the corresponding cell abilities and promote apoptosis of NPC cells. The target relationship between miR-130a-3p and BACH2 was confirmed. The epithelial-mesenchymal transition (EMT) pathway was also influenced by miR-130a-3p down-regulation. In conclusion, miR-130a-3p could bind to BACH2, inhibit NPC cell abilities, and promote cell apoptosis.

MicroRNA-15a Inhibits Proliferation and Induces Apoptosis in CNE1 Nasopharyngeal Carcinoma Cells

Nasopharyngeal carcinoma (NPC) is a highly metastatic cancer, frequently occurring in Southeast Asia and Southern China. Several microRNAs (miRNAs) have been shown to have an inhibitive effect on NPC, while the effect of miR-15a on NPC remains unclear. Thus, our study aimed to investigate the potential effect of miR-15a on NPC cell proliferation, apoptosis, and possible functional mechanism. Human NPC CNE1 cells were transfected with miR-15a mimics, miR-15a inhibitors, or a control. Afterward, cell viability and apoptosis were assayed by using CCK-8, BrdU assay, and flow cytometry. Moreover, Western blot was used to detect the expression changes of proliferation and apoptosis of related proteins. As a result, miR-15a overexpression significantly reduced cell proliferation (p < 0.01 or p < 0.001) and induced cell apoptosis (p < 0.001), while miR-15a suppression got the opposite result for cell proliferation and apoptosis. In addition, miR-15a overexpression upregulated the protein levels of p27, GSK-3β, Bax, procaspase 3, and active caspase 3, whereas miR-15a suppression downregulated these proteins. The protein level of p21 was not significantly regulated by miR-15a overexpression or suppression. These results indicated that miR-15a played a role for inhibition of proliferation and induction of apoptosis in CNE1 cells.

MicroRNA-190b confers radio-sensitivity through negative regulation of Bcl-2 in gastric cancer cells

OBJECTIVES

To determine the role of miR-190b in radio-sensitivity of gastric cancer (GC).

RESULTS

In radio-resistant GC cells, down-regulation of miR-190b and up-regulation of Bcl-2 were observed. The protein expression of Bcl-2 was negatively regulated by miR-190b. Overexpression of miR-190b significantly decreased cell viability and enhanced radio-sensitivity of GC cells. Of note, these effects of miR-190b on GC cells radio-sensitivity were abolished by Bcl-2.

CONCLUSION

miR-190b confers radio-sensitivity of GC cells, possibly via negative regulation of Bcl-2.

miRNA-411 acts as a potential tumor suppressor miRNA via the downregulation of specificity protein 1 in breast cancer

The expression and functions of microRNA (miR)-411 have been investigated in several types of cancer. However, until now, miR-411 in human breast cancer has not been examined. The present study investigated the expression, biological functions and molecular mechanisms of miR‑411 in human breast cancer, discussing whether it offers potential as a therapeutic biomarker for breast cancer in the future. The expression levels of miR‑411 in human breast cancer tissues and cells were measured using reverse transcription‑quantitative polymerase chain reaction analysis. Following transfection with miR‑411 mimics, an MTT assay, cell migration and invasion assay, western blot analysis and luciferase assay were performed in human breast cancer cell lines. According to the results, it was found that miR‑411 was significantly downregulated in breast cancer, and associated with lymph node metastasis and histological grade. Additionally, it was observed that miR‑411 suppressed cell growth, migration and invasion in the breast cancer cells. The present study also provided the first evidence, to the best of our knowledge, that miR‑411 was likely to directly target specificity protein 1 in breast cancer. These findings indicated that miR‑411 may be used a therapeutic biomarker for the treatment of breast cancer in the future.

Increased Serum Level of MicroRNA-663 Is Correlated with Poor Prognosis of Patients with Nasopharyngeal Carcinoma

MicroRNAs (miRs) play crucial roles in the carcinogenesis and malignant progression of human cancers including nasopharyngeal carcinoma (NPC). In this study, we aimed to investigate the association of serum miR-663 levels with the clinical factors and prognosis of NPC patients. Real-time PCR was performed to examine the amount of miR-663 in serum in NPC patients and healthy controls. Our data showed that the amount of miR-663 in serum was significantly higher in NPC patients than in healthy controls. Moreover, the serum levels of miR-663 were significantly correlated with the grade, lymph node metastasis, and clinical stage of NPC. Furthermore, higher serum miR-663 levels were closely associated with worse 5-year overall survival (OS) and relapse-free survival (RFS) of patients with NPC, and the serum level of miR-663 was found to be an independent predicator for the prognosis of NPC. In addition, after receiving chemoradiotherapy, the serum levels of miR-663 were significantly reduced in NPC patients. In summary, miR-663 was upregulated in the serum of NPC patients, which was downregulated after chemoradiotherapy, and its increased levels were closely associated with malignant progression and poor prognosis in NPC patients. Therefore, the amount of miR-663 in serum may become a potential predicator for the clinical outcome of NPC patients.

MicroRNA-137 suppresses tongue squamous carcinoma cell proliferation, migration and invasion

OBJECTIVES

Tongue squamous cell carcinoma (TSCC) is the most frequent type of oral malignancy. Increasing evidence has shown that miRNAs play key roles in many biological processes such as cell development, invasion, proliferation, differentiation, metabolism, apoptosis and migration.

MATERIALS AND METHODS

qRT-PCR analysis was performed to measure miR-137 expression. CCK-8 analysis, cell colony formation, wound-healing analysis and invasion were performed to detect resultant cell functions. The direct target of miR-137 was labelled and measured by luciferase assay and Western blotting.

RESULTS

We demonstrated that expression of miR-137 was downregulated in TSCC tissues compared to matched normal ones. miR-137 expression was downregulated in TSCC lines (SCC4, SCC1, UM1 and Cal27) compared to the immortalized NOK16B cell line and normal oral keratinocytes in culture (NHOK). In addition, we have shown that miR-137 expression was epigenetically regulated in TSCCs. Overexpression of miR-137 suppressed TSCC proliferation and colony formation. Ectopic expression of miR-137 promoted expression of the epithelial biomarker, E-cadherin, and inhibited the mesenchymal biomarker, N-cadherin, as well as vimentin and Snail expression, indicating that miR-137 suppressed TSCC epithelial-mesenchymal transition (EMT). We also showed that ectopic expression of miR-137 inhibited TSCC invasion and migration. In addition, we identified SP1 as a direct target gene of miR-137 in SCC1 cells. SP1 overexpression rescued inhibitory effects exerted by miR-137 on cell proliferation and EMT.

CONCLUSIONS

These results indicate that miR-137 acted as a tumour suppressor in TSCC by targeting SP1.

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.