miR-504 mediated down-regulation of nuclear respiratory factor 1 leads to radio-resistance in nasopharyngeal carcinoma

Precision medicine in nasopharyngeal carcinoma: comprehensive review of past, present, and future prospect

Nasopharyngeal carcinoma (NPC) is an aggressive malignancy with high propensity for lymphatic spread and distant metastasis. It is prominent as an endemic malignancy in Southern China and Southeast Asia regions. Studies on NPC pathogenesis mechanism in the past decades such as through Epstein Barr Virus (EBV) infection and oncogenic molecular aberrations have explored several potential targets for therapy and diagnosis. The EBV infection introduces oncoviral proteins that consequently hyperactivate many promitotic pathways and block cell-death inducers. EBV infection is so prevalent in NPC patients such that EBV serological tests were used to diagnose and screen NPC patients. On the other hand, as the downstream effectors of oncogenic mechanisms, the promitotic pathways can potentially be exploited therapeutically. With the apparent heterogeneity and distinct molecular aberrations of NPC tumor, the focus has turned into a more personalized treatment in NPC. Herein in this comprehensive review, we depict the current status of screening, diagnosis, treatment, and prevention in NPC. Subsequently, based on the limitations on those aspects, we look at their potential improvements in moving towards the path of precision medicine. The importance of recent advances on the key molecular aberration involved in pathogenesis of NPC for precision medicine progression has also been reported in the present review. Besides, the challenge and future outlook of NPC management will also be highlighted.

Cross-Regulation Between Redox and Epigenetic Systems in Tumorigenesis: Molecular Mechanisms and Clinical Applications

Significance: Redox and epigenetics are two important regulatory processes of cell physiological functions. The cross-regulation between these processes has critical effects on the occurrence and development of various types of tumors. Recent Advances: The core factor that influences redox balance is reactive oxygen species (ROS) generation. The ROS functions as a double-edged sword in tumors: Low levels of ROS promote tumors, whereas excessive ROS induces various forms of tumor cell death, including apoptosis and ferroptosis as well as necroptosis and pyroptosis. Many studies have shown that the redox balance is influenced by epigenetic mechanisms such as DNA methylation, histone modification, chromatin remodeling, non-coding RNAs (microRNA, long non-coding RNA, and circular RNA), and RNA N6-methyladenosine modification. Several oxidizing or reducing substances also affect the epigenetic state. Critical Issues: In this review, we summarize research on the cross-regulation between redox and epigenetics in cancer and discuss the relevant molecular mechanisms. We also discuss the current research on the clinical applications. Future Directions: Future research can use high-throughput methods to analyze the molecular mechanisms of the cross-regulation between redox and epigenetics using both in vitro and in vivo models in more detail, elucidate regulatory mechanisms, and provide guidance for clinical treatment. Antioxid. Redox Signal. 39, 445-471.

Pre-clinical and clinical importance of miR-21 in human cancers: Tumorigenesis, therapy response, delivery approaches and targeting agents

The field of non-coding RNA (ncRNA) has made significant progress in understanding the pathogenesis of diseases and has broadened our knowledge towards their targeting, especially in cancer therapy. ncRNAs are a large family of RNAs with microRNAs (miRNAs) being one kind of endogenous RNA which lack encoded proteins. By now, miRNAs have been well-coined in pathogenesis and development of cancer. The current review focuses on the role of miR-21 in cancers and its association with tumor progression. miR-21 has both oncogenic and onco-suppressor functions and most of the experiments are in agreement with the tumor-promoting function of this miRNA. miR-21 primarily decreases PTEN expression to induce PI3K/Akt signaling in cancer progression. Overexpression of miR-21 inhibits apoptosis and is vital for inducing pro-survival autophagy. miR-21 is vital for metabolic reprogramming and can induce glycolysis to enhance tumor progression. miR-21 stimulates EMT mechanisms and increases expression of MMP-2 and MMP-9 thereby elevating tumor metastasis. miR-21 is a target of anti-cancer agents such as curcumin and curcumol and its down-regulation impairs tumor progression. Upregulation of miR-21 results in cancer resistance to chemotherapy and radiotherapy. Increasing evidence has revealed the role of miR-21 as a biomarker as it is present in both the serum and exosomes making them beneficial biomarkers for non-invasive diagnosis of cancer.

LncRNA miR143HG inhibits the proliferation of glioblastoma cells by sponging miR-504

AIM

It is known that miR-504 can target p53 to promote cancer progression. Our bioinformatics analysis revealed that miR-504 could bind miR-143 host gene (miR143HG), suggesting that miR143HG might also have crosstalk with p53 in cancer progression. This study aimed to analyze the function of miR143HG in glioblastoma (GBM).

METHODS

This study selected 64 GBM patients. GBM and non-tumor tissues were obtained from the patients. RT-qPCR was used to analyze gene expression. Survival curve analysis was performed to analyze the prognostic values of miR143HG for GBM. The crosstalk between miR143HG and miR-504 was analyzed by overexpressing them in GBM cells, followed by RT-qPCRs to detect their expression. CCK-8 assay was used to detect the cell proliferation ability.

RESULTS

We found that miR143HG was downregulated in GBM and predicted poor survival. The mRNA expression levels of miR143HG and p53 were positively correlated in GBM tissues. Bioinformatics analysis suggested that miR143HG could form base paring with miR-504, which has been reported to target p53. Overexpression experiments revealed that miR143HG overexpression upregulated the expression of p53, while miR-504 overexpression inhibited the effect of miR143HG overexpression on the expression of p53. Moreover, overexpression of miR143HG and p53 decreased GBM cell proliferation, while overexpression of miR-504 increased GBM cell proliferation. In addition, overexpression of miR-504 attenuated the effect of miR143HG overexpression on GBM cell proliferation.

CONCLUSION

Therefore, miR143HG may decrease the proliferation of GBM cells by sponging miR-504 to upregulate p53.

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.

MicroRNAs as Biomarkers for Ionizing Radiation Injury

Accidental radiation exposures such as industrial accidents and nuclear catastrophes pose a threat to human health, and the potential or substantial injury caused by ionizing radiation (IR) from medical treatment that cannot be ignored. Although the mechanisms of IR-induced damage to various organs have been gradually investigated, medical treatment of irradiated individuals is still based on clinical symptoms. Hence, minimally invasive biomarkers that can predict radiation damage are urgently needed for appropriate medical management after radiation exposure. In the field of radiation biomarker, finding molecular biomarkers to assess different levels of radiation damage is an important direction. In recent years, microRNAs have been widely reported as several diseases’ biomarkers, such as cancer and cardiovascular diseases, and microRNAs are also of interest to the ionizing radiation field as radiation response molecules, thus researchers are turning attention to the potential of microRNAs as biomarkers in tumor radiation response and the radiation toxicity prediction of normal tissues. In this review, we summarize the distribution of microRNAs, the progress on research of microRNAs as markers of IR, and make a hypothesis about the origin and destination of microRNAs in vivo after IR.

Radiotherapy resistance: identifying universal biomarkers for various human cancers

Radiotherapy (RT) is considered as a standard in the treatment of most solid cancers, including glioblastoma, lung, breast, rectal, prostate, colorectal, cervical, esophageal, and head and neck cancers. The main challenge in RT is tumor cell radioresistance associated with a high risk of locoregional relapse and distant metastasis. Despite significant progress in understanding mechanisms of radioresistance, its prediction and overcoming remain unresolved. This review presents the state-of-the-art for the potential universal biomarkers correlated to the radioresistance and poor outcome in different cancers. We describe radioresistance biomarkers functionally attributed to DNA repair, signal transduction, hypoxia, and angiogenesis. We also focus on high throughput genetic and proteomic studies, which revealed a set of molecular biomarkers related to radioresistance. In conclusion, we discuss biomarkers which are overlapped in most several cancers.

Liver-specific over-expression of Cripto-1 in transgenic mice promotes hepatocyte proliferation and deregulated expression of hepatocarcinogenesis-related genes and signaling pathways

In this study, we investigated the role of embryonic gene Cripto-1 (CR-1) in hepatocellular carcinoma (HCC) using hepatocyte-specific CR-1-overexpressing transgenic mice. The expression of truncated 1.7-kb CR-1 transcript (SF-CR-1) was significantly higher than the full-length 2.0-kb CR-1 transcript (FL-CR-1) in a majority of HCC tissues and cell lines. Moreover, CR-1 mRNA and protein levels were significantly higher in HCC tissues than adjacent normal liver tissues. Hepatocyte-specific over-expression of CR-1 in transgenic mice enhanced hepatocyte proliferation after 2/3 partial hepatectomy (2/3 PHx). CR-1 over-expression significantly increased in vivo xenograft tumor growth of HCC cells in nude mice and in vitro HCC cell proliferation, migration, and invasion. CR-1 over-expression in the transgenic mouse livers deregulated HCC-related signaling pathways such as AKT, Wnt/β-catenin, Stat3, MAPK/ERK, JNK, TGF-β and Notch, as well as expression of HCC-related genes such as CD5L, S100A8, S100A9, Timd4, Orm2, Orm3, PDK4, DMBT1, G0S2, Plk2, Plk3, Gsta1 and Gsta2. However, histological signs of precancerous lesions, hepatocyte dysplasia or HCC formation were not observed in the livers of 3-, 6- or 8-month-old hepatocyte-specific CR-1-overexpressing transgenic mice. These findings demonstrate that liver-specific CR-1 overexpression in transgenic mice deregulates signaling pathways and genes associated with HCC.

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.

The emerging roles of exosomal miRNAs in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a unique subtype of head and neck cancer that is endemic to Southern China and Southeast Asia. Due to the concealed location and intrinsic invasiveness of this disease, majority of NPC patients are diagnosed with advanced stages (III and IV) and poor prognosis. Chemoradiotherapy resistance is a major problem for NPC patients, leading to incomplete local elimination, recurrence and metastasis. Therefore, it is of great significance to seek novel biomarkers and effective therapeutic regimen for clinical management of this deadly cancer. Exosomes are tiny membrane vesicles with a lipid bilayer secreted by most cells in the body, which are widely distributed in various body fluids. They are functionally active in different physiopathological process by carrying and transmitting important signal molecules such as miRNA, mRNA, protein, lipid, etc. Exosomal miRNAs play an important role in tumorigenesis and development of NPC. They are extensively involved in NPC cell proliferation, migration, invasion, neovascularization, radiotherapy resistance and the regulation of tumor immune microenvironment through intercellular communication and control of gene expression. Moreover, exosomal miRNAs can be used as valuable biomarkers for early diagnosis and therapeutic targets of NPC.

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.

Targeting the signaling in Epstein-Barr virus-associated diseases: mechanism, regulation, and clinical study

Epstein–Barr virus-associated diseases are important global health concerns. As a group I carcinogen, EBV accounts for 1.5% of human malignances, including both epithelial- and lymphatic-originated tumors. Moreover, EBV plays an etiological and pathogenic role in a number of non-neoplastic diseases, and is even involved in multiple autoimmune diseases (SADs). In this review, we summarize and discuss some recent exciting discoveries in EBV research area, which including DNA methylation alterations, metabolic reprogramming, the changes of mitochondria and ubiquitin-proteasome system (UPS), oxidative stress and EBV lytic reactivation, variations in non-coding RNA (ncRNA), radiochemotherapy and immunotherapy. Understanding and learning from this advancement will further confirm the far-reaching and future value of therapeutic strategies in EBV-associated diseases.

Targeting cancer-cell mitochondria and metabolism to improve radiotherapy response

Radiotherapy is a regimen that uses ionising radiation (IR) to treat cancer. Despite the availability of several therapeutic options, cancer remains difficult to treat and only a minor percentage of patients receiving radiotherapy show a complete response to the treatment due to development of resistance to IR (radioresistance). Therefore, radioresistance is a major clinical problem and is defined as an adaptive response of the tumour to radiation-induced damage by altering several cellular processes which sustain tumour growth including DNA damage repair, cell cycle arrest, alterations of oncogenes and tumour suppressor genes, autophagy, tumour metabolism and altered reactive oxygen species. Cellular organelles, in particular mitochondria, are key players in mediating the radiation response in tumour, as they regulate many of the cellular processes involved in radioresistance. In this article has been reviewed the recent findings describing the cellular and molecular mechanism by which cancer rewires the function of the mitochondria and cellular metabolism to enhance radioresistance, and the role that drugs targeting cellular bioenergetics have in enhancing radiation response in cancer patients.

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.

HPV16 E6 regulates the proliferation, invasion, and apoptosis of cervical cancer cells by downregulating miR-504

BACKGROUND

Human papillomavirus (HPV) 16 infection is a necessary condition for the pathogenesis and development of cervical cancer. The E6 protein is expressed by the HPV16 E6 gene and promotes malignant phenotype transformation, which is an important mechanism for the occurrence and development of cervical cancer. MicroRNA-504 (miR-504) has been reported as an oncogene or tumor suppressor gene; the expression of miR-504 in cervical cancer has been found to be negatively correlated with HPV infection. However, the relationship between HPV16 E6 and miR-504 and the role of miR-504 in cervical cancer are not clear. In the current study, we observed the effect of HPV16 E6 on the expression of miR-504 in cervical cancer cells, and analyzed whether HPV16 E6 affects proliferation, invasion, and apoptosis in cervical cancer cells by regulating the expression of miR-504.

METHODS

Cervical cancer cells (SiHa) were divided into four groups: the empty vector group, E6 overexpression group, E6 overexpression + miR-NC group, and E6 overexpression+miR-504 group. The expressions levels of HPV16 E6 mRNA and miR-504 were detected by real-time polymerase chain reaction (PCR), and the expression level of HPV16 E6 protein was detected by Western blot. Cell proliferation, invasion, and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Tastelessly, and flow cytometry, respectively.

RESULTS

The expression level of miR-504 was significantly decreased in E6 overexpression cells compared to the control cells (P<0.05); the overexpression of miR-504 with miR-504 mimic significantly reversed the downregulation of miR-504 in E6 overexpression SiHa cells (P<0.05). MTT and Transwell assays showed that the overexpression of E6 significantly increased proliferation and invasion of SiHa cells (P<0.05). The overexpression of miR-504 reversed the role of HPV16 E6 on the proliferation and invasion in E6 overexpression SiHa cells, and the difference was statistically significant (P<0.05). Further analysis showed that the overexpression of E6 significantly reduced apoptosis of SiHa cells (P<0.05). The overexpression of miR-504 reversed the role of HPV16 E6 on apoptosis in E6 overexpression SiHa cells, and the difference was statistically significant (P<0.05).

CONCLUSIONS

HPV16 E6 may promote the proliferation and invasion, and inhibit the apoptosis, of cervical cancer SiHa cells by downregulating miR-504 expression.

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.

Advances in targeted therapy mainly based on signal pathways for nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant epithelial carcinoma of the head and neck region which mainly distributes in southern China and Southeast Asia and has a crucial association with the Epstein-Barr virus. Based on epidemiological data, both incidence and mortality of NPC have significantly declined in recent decades grounded on the improvement of living standard and medical level in an endemic region, in particular, with the clinical use of individualized chemotherapy and intensity-modulated radiotherapy (IMRT) which profoundly contributes to the cure rate of NPC patients. To tackle the challenges including local recurrence and distant metastasis in the current NPC treatment, we discussed the implication of using targeted therapy against critical molecules in various signal pathways, and how they synergize with chemoradiotherapy in the NPC treatment. Combination treatment including targeted therapy and IMRT or concurrent chemoradiotherapy is presumably to be future options, which may reduce radiation or chemotherapy toxicities and open new avenues for the improvement of the expected functional outcome for patients with advanced NPC.

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.

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.

Regulation of DNA Damage Response and Homologous Recombination Repair by microRNA in Human Cells Exposed to Ionizing Radiation

Ionizing radiation may be of both artificial and natural origin and causes cellular damage in living organisms. Radioactive isotopes have been used significantly in cancer therapy for many years. The formation of DNA double-strand breaks (DSBs) is the most dangerous effect of ionizing radiation on the cellular level. After irradiation, cells activate a DNA damage response, the molecular path that determines the fate of the cell. As an important element of this, homologous recombination repair is a crucial pathway for the error-free repair of DNA lesions. All components of DNA damage response are regulated by specific microRNAs. MicroRNAs are single-stranded short noncoding RNAs of 20–25 nt in length. They are directly involved in the regulation of gene expression by repressing translation or by cleaving target mRNA. In the present review, we analyze the biological mechanisms by which miRNAs regulate cell response to ionizing radiation-induced double-stranded breaks with an emphasis on DNA repair by homologous recombination, and its main component, the RAD51 recombinase. On the other hand, we discuss the ability of DNA damage response proteins to launch particular miRNA expression and modulate the course of this process. A full understanding of cell response processes to radiation-induced DNA damage will allow us to develop new and more effective methods of ionizing radiation therapy for cancers, and may help to develop methods for preventing the harmful effects of ionizing radiation on healthy organisms.

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.

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.

Estrogenic control of mitochondrial function

Sex-based differences in human disease are caused in part by the levels of endogenous sex steroid hormones which regulate mitochondrial metabolism. This review updates a previous review on how estrogens regulate metabolism and mitochondrial function that was published in 2017. Estrogens are produced by ovaries and adrenals, and in lesser amounts by adipose, breast stromal, and brain tissues. At the cellular level, the mechanisms by which estrogens regulate diverse cellular functions including reproduction and behavior is by binding to estrogen receptors α, β (ERα and ERβ) and G-protein coupled ER (GPER1). ERα and ERβ are transcription factors that bind genomic and mitochondrial DNA to regulate gene transcription. A small proportion of ERα and ERβ interact with plasma membrane-associated signaling proteins to activate intracellular signaling cascades that ultimately alter transcriptional responses, including mitochondrial morphology and function. Although the mechanisms and targets by which estrogens act directly and indirectly to regulate mitochondrial function are not fully elucidated, it is clear that estradiol regulates mitochondrial metabolism and morphology via nuclear and mitochondrial-mediated events, including stimulation of nuclear respiratory factor-1 (NRF-1) transcription that will be reviewed here. NRF-1 is a transcription factor that interacts with coactivators including peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC-1α) to regulate nuclear-encoded mitochondrial genes. One NRF-1 target is TFAM that binds mtDNA to regulate its transcription. Nuclear-encoded miRNA and lncRNA regulate mtDNA-encoded and nuclear-encoded transcripts that regulate mitochondrial function, thus acting as anterograde signals. Other estrogen-regulated mitochondrial activities including bioenergetics, oxygen consumption rate (OCR), and extracellular acidification (ECAR), are reviewed.

Circulating microRNAs as Biomarkers of Radiation Exposure: A Systematic Review and Meta-Analysis

PURPOSE

MicroRNAs (miRNAs) were hypothesized to be robust and easily measured biomarkers of radiation exposure, which has led to multiple studies in various clinical and experimental scenarios. We sought to identify evolutionary conserved, radiation-induced circulating miRNAs through a multispecies, integrative systematic review and meta-analysis of miRNAs in radiation.

METHODS AND MATERIALS

The systematic review was registered in the PROSPERO database (ID: 81701). We downloaded a list of studies with the query: (circulating OR plasma OR serum) AND (miRNA or microRNA) AND (radiat* OR radiotherapy OR irradiati*) from MEDLINE (103 studies), EMBASE (364 studies), and Cochrane Database of Systematic Reviews (0 studies). After deleting 116 duplicates, the remaining 351 abstracts were reviewed. Inclusion criteria were experimental study; human, mice, rat or nonhuman primate study; and serum or plasma miRNA expression measured before and after radiation exposure.

RESULTS

The screening procedure yielded 62 research studies. After verification, 30 articles contained data on miRNA expression change after irradiation. Thus, we obtained a database of 131 miRNAs from 96 pairwise post-/preirradiation comparisons reporting 2508 fold changes (FCs) of circulating miRNAs. The meta-analysis showed 28 miRNAs with significant radiation-induced change of their expression in the serum. In metaregression analysis, 7 miRNAs-miR-150 (FC = 0.40; 95% confidence interval [CI], 0.35-0.45), miR-29a (FC = 0.87; 95% CI, 0.79-0.96), miR-29b (FC = 0.85; 95% CI, 0.76-0.96), miR-30c (FC = 1.19; 95% CI, 1.09-1.30), miR-200b (FC = 1.34; 95% CI, 1.21-1.48), miR-320a (FC = 1.13; 95% CI, 1.05-1.23), and miR-30a (FC = 1.18; 95% CI, 1.07-1.30)-significantly correlated with either total or fraction dose of radiation. Additionally, miR-150, miR-320a, miR-200b, and miR-30c correlated significantly with time elapsed since irradiation.

CONCLUSIONS

Circulating miRNAs reflect the impact of ionizing radiation irrespective of the studied species, often in a dose-dependent manner. This makes circulating miRNAs promising biomarkers of radiation exposure.

LNC00673 suppresses proliferation and metastasis of pancreatic cancer via target miR-504/ HNF1A

Pancreatic cancer is a highly invasive malignant tumor of the digestive system. To explore the mechanism of pancreatic cancer development, development, invasion and metastasis, in this study we focused on long non-coding RNA (LncRNA), which has been reported to be involved in tumorigenesis. We identified a LINC00673, which is highly correlated with the pancreatic cancer risk. LINC00673 Overexpression is associated with good survival in pancreatic cancer patients, Effects of LINC00673 on pancreatic cancer cell apoptosis, viability, migration. LINC00673 negatively correlated with miR-504 and MiR-504 overexpression promoted cancer progression in Pancreatic cancer. MiR-504 negatively correlated with HNF1A, which was highly expressed Pancreatic cancer. HNF1A inhibited cell progression in pancreatic cancer cells. LINC00673 overexpression inhibited caner progression in nude mice. Taken together, LINC00673 can through suppress miR-504/ HNF1A regulating invasion and migration in pancreatic cancer. Also, we identified miR-504 as a target of LINC00673 in pancreatic cancer and LINC00673 can be used as a novel therapeutic target for the pancreatic cancer.

MicroRNA‑504 targets AEG‑1 and inhibits cell proliferation and invasion in retinoblastoma

The dysregulation of microRNAs (miRNAs/miRs) has become increasingly recognized as a primary feature of retinoblastoma (RB). Furthermore, miRNAs have been demonstrated to be involved in the occurrence and development of RB. Therefore, it is crucial to investigate the expression profile and roles of miRNAs in RB in order to identify potential therapeutic targets to treat patients with RB. The expression profile and biological roles of miRNA‑504 (miR‑504) have been reported in numerous types of human cancer; however, the roles of miR‑504 in RB remain unknown. In the present study, it was demonstrated that miR‑504 expression was significantly decreased in RB tissues and cell lines. Functional analysis identified that resumption of miR‑504 expression suppressed cell proliferation and invasion in RB. Furthermore, astrocyte elevated gene‑1 (AEG‑1) was determined to be a direct target of miR‑504 in RB, and a negative correlation between miR‑504 and AEG‑1 mRNA expression levels was observed in RB tissues. Additionally, the tumor‑suppressing effects of miR‑504 overexpression in RB cells could be rescued by AEG‑1 upregulation. In conclusion, these results indicated a significant role of the miR‑504/AEG‑1 pathway in inhibiting the aggressiveness of RB, suggesting that this miRNA may be employed as a therapeutic target for the treatment of patients with this disease.

MicroRNA-mediated redox regulation modulates therapy resistance in cancer cells: clinical perspectives

BACKGROUND

Chemotherapy and radiation therapy are the most common types of cancer therapy. The development of chemo/radio-resistance remains, however, a major obstacle. Altered redox balances are among of the main factors mediating therapy resistance. Therefore, redox regulatory strategies are urgently needed to overcome this problem. Recently, microRNAs have been found to act as major redox regulatory factors affecting chemo/radio-resistance. MicroRNAs play critical roles in regulating therapeutic resistance through the regulation of antioxidant enzymes, redox-sensitive signaling pathways, cancer stem cells, DNA repair mechanisms and autophagy.

CONCLUSIONS

Here, we summarize current knowledge on microRNA-mediated redox regulatory mechanisms underlying chemo/radio-resistance. This knowledge may form a basis for a better clinical management of cancer patients.

The Radiosensitization of Sodium Glycididazole on Nasopharyngeal Carcinoma Cells via Enhancing DNA Damage and Promoting Apoptosis

Background: The radioresistance of nasopharyngeal carcinoma (NPC) was the main cause of radiotherapy failure and it was still a challenge in the treatment of advanced NPC patients. Previous clinical studies demonstrated that sodium glycididazole(CMNA) can enhance the radiosensitivity of NPC, but the corresponding cellular mechanisms or processes remains largely unclear. Methods: To clarify the radiosensitizing effects of CMNA on NPC cells and reveal its cellular mechanisms, its effect on cell survival of NPC cells was assessed by MTT and clonogenic assay, with or without radiation. The potential cellular mechanisms such as cell cycle distribution, apoptosis and DNA damage were assessed. A retrospective analysis of the outcome of patients with III-IV stage NPC who undergo same radiochemotherapy with or without concurrent CMNA treatment was performed to elucidate the role of CMNA in the improvement of the curative effects. Results: The treatment with CMNA at the concentration lower or close to the clinical dosage had little effect on cell survival, cell cycle distribution and a weak effect on DNA damage and cell apoptosis of NPC cells. The combination of CMNA and radiation significantly increased the DNA damage and enhanced the apoptosis of NPC cells, but did not significantly alter the cell cycle distribution as compared with the irradiation (IR) alone. A total of 99 patients who underwent radiochemotherapy were categorized into those with (treatment group, n=52) and without (control group, n=47) the treatment with CMNA. The complete response rates of patients in treatment group were significantly higher than in control group. Conclusions: Our results suggested that CMNA enhance the sensitivity of the NPC cells to radiation via enhancing DNA damage and promoting cell apoptosis. It provides clues for further investigation of the molecular mechanism of the radiosensitization of CMNA on NPC cells.

MicroRNA-504 functions as a tumor suppressor in hepatocellular carcinoma through inhibiting Frizzled-7-mediated-Wnt/β-catenin signaling

Accumulating evidence suggests that microRNAs (miRNAs) are critical regulators in the development and progression of various malignant tumors, including hepatocellular carcinoma (HCC). Multiple findings have indicated that miRNA-504 (miR-504) is dysregulated in several types of cancers, functioning as an oncogenic miRNA or a tumor suppressive miRNA. However, the role of miR-504 in HCC remains unknown. In this study, we aimed to detect the expression pattern of miR-504 in HCC tissues and cell lines and investigate the precise biological function in HCC cells. Our results showed that miR-504 expression levels were frequently downregulated in both HCC tissues and cell lines. Gain-of-function experiments demonstrated that miR-504 overexpression inhibited the proliferation and invasion in HCC cell lines. By contrast, miR-504 inhibition had the opposite effect. Interestingly, bioinformatics analysis predicted that Frizzled-7 (FZD7) was a potential target gene of miR-504. Dual-luciferase reporter assays confirmed that miR-504 directly targeted the 3'-untranslated region of FZD7 mRNA. In addition, our results showed that miR-504 negatively regulated the mRNA and protein expression of FZD7 in HCC cell lines. Moreover, miR-540 overexpression inhibited the cellular expression of β-catenin and blocked the activation of Wnt signaling in HCC cells. Notably, restoration of FZD7 expression significantly reversed the inhibitory effect of miR-504 on proliferation, invasion, and Wnt/β-catenin signaling in HCC cells. In conclusion, our results demonstrate that miR-504 functions as a tumor suppressive miRNA that inhibits the proliferation and invasion of HCC cells by targeting FZD7 and inhibiting Wnt/β-catenin signaling. Our study provides evidence that miR-504-meidated FZD7/Wnt/β-catenin signaling pathway plays an important role in HCC development and progression and suggests miR-504 as a novel future therapeutic target for treatment of HCC.

Targeting CPT1A-mediated fatty acid oxidation sensitizes nasopharyngeal carcinoma to radiation therapy

Nasopharyngeal carcinoma (NPC) has a particularly high prevalence in southern China, southeastern Asia and northern Africa. Radiation resistance remains a serious obstacle to successful treatment in NPC. This study aimed to explore the metabolic feature of radiation-resistant NPC cells and identify new molecular-targeted agents to improve the therapeutic effects of radiotherapy in NPC. Methods: Radiation-responsive and radiation-resistant NPC cells were used as the model system in vitro and in vivo. Metabolomics approach was used to illustrate the global metabolic changes. ¹³C isotopomer tracing experiment and Seahorse XF analysis were undertaken to determine the activity of fatty acid oxidation (FAO). qRT-PCR was performed to evaluate the expression of essential FAO genes including CPT1A. NPC tumor tissue microarray was used to investigate the prognostic role of CPT1A. Either RNA interference or pharmacological blockade by Etomoxir were used to inhibit CPT1A. Radiation resistance was evaluated by colony formation assay. Mitochondrial membrane potential, apoptosis and neutral lipid content were measured by flow cytometry analysis using JC-1, Annexin V and LipidTOX Red probe respectively. Molecular markers of mitochondrial apoptosis were detected by western blot. Xenografts were treated with Etomoxir, radiation, or a combination of Etomoxir and radiation. Mitochondrial apoptosis and lipid droplets content of tumor tissues were detected by cleaved caspase 9 and Oil Red O staining respectively. Liquid chromatography coupled with tandem mass spectrometry approach was used to identify CPT1A-binding proteins. The interaction of CPT1A and Rab14 were detected by immunoprecipitation, immunofluorescence and in situ proximity ligation analysis. Fragment docking and direct coupling combined computational protein-protein interaction prediction method were used to predict the binding interface. Fatty acid trafficking was measured by pulse-chase assay using BODIPY C16 and MitoTracker Red probe. Results: FAO was active in radiation-resistant NPC cells, and the rate-limiting enzyme of FAO, carnitine palmitoyl transferase 1 A (CPT1A), was consistently up-regulated in these cells. The protein level of CPT1A was significantly associated with poor overall survival of NPC patients following radiotherapy. Inhibition of CPT1A re-sensitized NPC cells to radiation therapy by activating mitochondrial apoptosis both in vitro and in vivo. In addition, we identified Rab14 as a novel CPT1A binding protein. The CPT1A-Rab14 interaction facilitated fatty acid trafficking from lipid droplets to mitochondria, which decreased radiation-induced lipid accumulation and maximized ATP production. Knockdown of Rab14 attenuated CPT1A-mediated fatty acid trafficking and radiation resistance. Conclusion: An active FAO is a vital signature of NPC radiation resistance. Targeting CPT1A could be a beneficial regimen to improve the therapeutic effects of radiotherapy in NPC patients. Importantly, the CPT1A-Rab14 interaction plays roles in CPT1A-mediated radiation resistance by facilitating fatty acid trafficking. This interaction could be an attractive interface for the discovery of novel CPT1A inhibitors.

Obesity-induced mitochondrial dysfunction in porcine adipose tissue-derived mesenchymal stem cells

Transplantation of autologous mesenchymal stem cells (MSCs) may be a viable option for treatment of several diseases. MSCs efficacy depends on adequate function of their mitochondria, which might be impaired in a noxious milieu. We hypothesized that obesity compromises MSCs mitochondrial structure and function, possibly via micro-RNA (miRNA)-based mechanisms. MSCs were collected from swine abdominal adipose tissue after 16 weeks of Lean or Obese diet (n = 7 each). Mitochondrial structure was assessed by electron microscopy and function by membrane potential and cytochrome-c oxidase (COX)-IV activity. Oxidative stress was assessed by Mito-SOX and dihydroethidium staining. Next-generation sequencing (RNA-seq) was performed to identify miRNAs expression in MSCs, and predicted mitochondrial target genes were then identified (MitoCarta). Compared to Lean-MSCs, mitochondria from Obese-MSCs were smaller and showed cristae remodeling and loss. Mitochondrial membrane potential and COX-IV activity decreased in Obese-MSCs, associated with increased mitochondrial oxidative stress. RNA-seq generated reads for 413 miRNAs, of which 5 miRNAs were upregulated in Obese-MSCs (fold change >2, p < 0.05) and found to target 43 specific mitochondrial genes. Obesity impairs MSC mitochondrial structure and function, possibly mediated partly through miRNA-induced mitochondrial gene regulation, leading to increased oxidative stress. Importantly, these alterations may limit the therapeutic use of autologous MSCs in subjects with obesity.

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.

HTLV-1 bZIP factor suppresses TDP1 expression through inhibition of NRF-1 in adult T-cell leukemia

Adult T-cell leukemia (ATL) is an aggressive T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1). We recently reported that abacavir, an anti-HIV-1 drug, potently and selectively kills ATL cells. This effect was attributed to the reduced expression of tyrosyl-DNA-phosphodiesterase 1 (TDP1), a DNA repair enzyme, in ATL cells. However, the molecular mechanism underlying the downregulation of TDP1 in ATL cells remains elusive. Here we identified the core promoter of the TDP1 gene, which contains a conserved nuclear respiratory factor 1 (NRF-1) binding site. Overexpression of NRF-1 increased TDP1-promoter activity, whereas the introduction of dominant-negative NRF-1 repressed such activity. Overexpression of NRF-1 also upregulated endogenous TDP-1 expression, while introduction of shNRF-1 suppressed TDP1 in Jurkat T cells, making them susceptible to abacavir. These results indicate that NRF-1 is a positive transcriptional regulator of TDP1-gene expression. Importantly, we revealed that HTLV-1 bZIP factor (HBZ) protein which is expressed in all ATL cases physically interacts with NRF-1 and inhibits the DNA-binding ability of NRF-1. Taken together, HBZ suppresses TDP1 expression by inhibiting NRF-1 function in ATL cells. The HBZ/NRF-1/TDP1 axis provides new therapeutic targets against ATL and might explain genomic instability leading to the pathogenesis of ATL.

The Transcriptional Network Structure of a Myeloid Cell: A Computational Approach

Understanding the general principles underlying genetic regulation in eukaryotes is an incomplete and challenging endeavor. The lack of experimental information regarding the regulation of the whole set of transcription factors and their targets in different cell types is one of the main reasons to this incompleteness. So far, there is a small set of curated known interactions between transcription factors and their downstream genes. Here, we built a transcription factor network for human monocytic THP-1 myeloid cells based on the experimentally curated FANTOM4 database where nodes are genes and the experimental interactions correspond to links. We present the topological parameters which define the network as well as some global structural features and introduce a relative inuence parameter to quantify the relevance of a transcription factor in the context of induction of a phenotype. Genes like ZHX2, ADNP, or SMAD6 seem to be highly regulated to avoid an avalanche transcription event. We compare these results with those of RegulonDB, a highly curated transcriptional network for the prokaryotic organism E. coli, finding similarities between general hallmarks on both transcriptional programs. We believe that an approach, such as the one shown here, could help to understand the one regulation of transcription in eukaryotic cells.

miR-504 promotes tumour growth and metastasis in human osteosarcoma by targeting TP53INP1

An increasing number of studies have demonstrated that microRNAs participate in the development of osteosarcoma by acting as tumour suppressor or tumour-promoting genes. We investigated the role of miR-504 in the growth and metastasis of osteosarcoma. The expression of miR-504 in clinical osteosarcoma samples was higher than that in the adjacent normal tissue and correlated with tumour size and clinical stage. Tumour protein p53-inducible nuclear protein 1 (TP53INP1) was downregulated in the clinical osteosarcoma samples compared with the adjacent normal tissues and was consistently correlated with the clinical stage. The results of dual-luciferase reporter assay and western blot analysis demonstrated that the TP53INP1 gene is a direct target of miR-504. Altogether, the Cell Counting Kit-8 (CCK-8), the colony formation, the flow cytometry and the Transwell assay results demonstrated that miR-504 promoted osteosarcoma cell growth and metastasis in vitro. P73, P21, Bax, cleaved-caspase-3 and secreted protein acidic and rich in cysteine (SPARC) were associated with the suppressive role of miR-504/TP53INP1. The overexpression of miR-504 in osteosarcoma xenografts enhanced the tumour growth and increased the metastatic burden. Collectively, these results revealed that TP53INP1 is a target gene of miR-504 and that miR-504 enhances osteosarcoma growth and promotes distant metastases by targeting TP53INP1. Thus, miR-504/TP53INP1 may be associated with osteosarcoma size and clinical stage.

Identification of evolutionarily conserved DNA damage response genes that alter sensitivity to cisplatin

Ovarian, head and neck, and other cancers are commonly treated with cisplatin and other DNA damaging cytotoxic agents. Altered DNA damage response (DDR) contributes to resistance of these tumors to chemotherapies, some targeted therapies, and radiation. DDR involves multiple protein complexes and signaling pathways, some of which are evolutionarily ancient and involve protein orthologs conserved from yeast to humans. To identify new regulators of cisplatin-resistance in human tumors, we integrated high throughput and curated datasets describing yeast genes that regulate sensitivity to cisplatin and/or ionizing radiation. Next, we clustered highly validated genes based on chemogenomic profiling, and then mapped orthologs of these genes in expanded genomic networks for multiple metazoans, including humans. This approach identified an enriched candidate set of genes involved in the regulation of resistance to radiation and/or cisplatin in humans. Direct functional assessment of selected candidate genes using RNA interference confirmed their activity in influencing cisplatin resistance, degree of γH2AX focus formation and ATR phosphorylation, in ovarian and head and neck cancer cell lines, suggesting impaired DDR signaling as the driving mechanism. This work enlarges the set of genes that may contribute to chemotherapy resistance and provides a new contextual resource for interpreting next generation sequencing (NGS) genomic profiling of tumors.

Roles of GSK-3 and microRNAs on epithelial mesenchymal transition and cancer stem cells

Various signaling pathways exert critical roles in the epithelial to mesenchymal transition (EMT) and cancer stem cells (CSCs). The Wnt/beta-catenin, PI3K/PTEN/Akt/mTORC, Ras/Raf/MEK/ERK, hedgehog (Hh), Notch and TP53 pathways elicit essential regulatory influences on cancer initiation, EMT and progression. A common kinase involved in all these pathways is moon-lighting kinase glycogen synthase kinase-3 (GSK-3). These pathways are also regulated by micro-RNAs (miRs). TP53 and components of these pathways can regulate the expression of miRs. Targeting members of these pathways may improve cancer therapy in those malignancies that display their abnormal regulation. This review will discuss the interactions of the multi-functional GSK-3 enzyme in the Wnt/beta-catenin, PI3K/PTEN/Akt/mTORC, Ras/Raf/MEK/ERK, Hh, Notch and TP53 pathways. The regulation of these pathways by miRs and their effects on CSC generation, EMT, invasion and metastasis will be discussed.

miR-19b promotes breast cancer metastasis through targeting MYLIP and its related cell adhesion molecules

miR-19b is a key molecule for cancer development, however its crucial roles in breast cancer metastasis are rarely studied right now. In this study, using several bioinformatics databases to predict the downstream targets for miR-19b, we verified that a novel target gene, myosin regulatory light chain interacting protein (MYLIP), could be directly down-regulated by miR-19b through its 3′-UTR region. MYLIP belongs to the cytoskeletal protein clusters and is involved in the regulation of cell movement and migration. We further explored that miR-19b was highly expressed and negatively correlated with MYLIP expression in breast cancer patient samples from the TCGA database. And the over-expression of miR-19b or inhibition of MYLIP facilitated the migration and metastasis of breast cancer cells, through conducting the wound healing assay and transwell invasion assay. Additionally, miR-19b could obviously promote breast tumor growth in mouse models and affect the expressions of cell adhesion molecules (including E-Cadherin, ICAM-1 and Integrin β1) by down-regulating E-Cadherin expression and up-regulating ICAM-1 and Integrin β1 expressions in vitro and in vivo. Meanwhile, miR-19b effectively activated the Integrin β downstream signaling pathways (such as the Ras-MAPK pathway and the PI3K-AKT pathway) and elevated the expression levels of essential genes in these two pathways. Taken together, these findings comprehensively illustrate the regulatory mechanisms ofmiR-19b in breast cancer metastasis, and provide us new insights for exploring MYLIP and its related cell adhesion molecules as promising therapeutic targets to interfere breast cancer development.

miR-206 enhances nasopharyngeal carcinoma radiosensitivity by targeting IGF1

Radioresistance remains a major problem in nasopharyngeal carcinoma (NPC) treatment. However, the underlying molecular mechanisms of NPC radioresistance remain poorly understood. The present study aimed to investigate the potential role and mechanism of miR-206 in NPC radioresistance. We observed that miR-206 was down-regulated in radioresistant NPC cells. Furthermore, restoration of miR-206 in CNE2-IR cells suppressed enhanced radiosensitivity of NPC cells. In contrast, inhibition of miR-206 in CNE2 cells reduced the radiosensitivity. We also found that miR-206 directly targeted IGF1 and inhibited the PI3K/AKT pathway. Our data demonstrate that miR-206 sensitizes NPC cell to irradiation by targeting IGF1, highlighting the therapeutic potential of miR-206 in NPC radiosensitization.

MicroRNA‑210 negatively regulates the radiosensitivity of nasopharyngeal carcinoma cells

Radiotherapy is one of the primary methods of treatment of malignant tumors, however, resistance to radiation is a major problem. The reasons for the radioresistance are still poorly understood. However, it is generally accepted that microRNAs (miRNAs or miRs) can regulate the radiosensitivity of tumors. The present study therefore aimed to identify specific miRNAs and their effects on radioresistant cells. More specifically, the aim was to investigate specific miRNAs and their effects on radioresistant tumor cells. The radioresistant tumor cells (CNE‑2R) were established using a dose gradient method, and the miRNA expression profiles of CNE‑2R cells and the parental cells (CNE‑2) were determined. The expression of miR‑210 in CNE‑2R cells was significantly higher than in CNE‑2 cells. CNE‑2R cells were transfected with LV‑hsa‑miR‑210‑inhibitor, and CNE‑2 cells were transfected with LV‑hsa‑miR‑210. The expression of miR‑210 was confirmed by reverse transcription quantitative‑polymerase chain reaction. The percentages of CNE‑2R‑miR‑210‑inhibitor and CNE‑2 cells in the G2/M phase were higher than in the CNE‑2R and CNE‑2‑miR‑210 cells, and the percentages of cells in S phase were lower than in the CNE‑2R and CNE‑2‑miR‑210 cells. Following 4 Gy of radiation, CNE‑2R‑miR‑210‑inhibitor and CNE‑2 cells, which express low levels of miR‑210, had a higher apoptosis rate than CNE‑2R and CNE‑2‑miR‑210 cells. Following 4, 8 and 12 Gy of radiation, cell viability and survival fraction of CNE‑2R‑miR‑210‑inhibitor cells were lower than those of CNE‑2R and CNE‑2‑miR‑210 cells, and similar to those of CNE‑2 cells. Together, these findings strongly suggest that miR‑210 negatively regulates the radiosensitivity of tumor cells, and may therefore have therapeutic potential for the treatment of radiation resistance.

EBV based cancer prevention and therapy in nasopharyngeal carcinoma

Epstein-Barr virus is an important cancer causing virus. Nasopharyngeal carcinoma is an infection-related cancer strongly driven by Epstein-Barr virus. In this cancer model, we identified the major host targets of latent membrane protein 1 which is a driving oncogene encoded by Epstein-Barr virus in latency infection. latent membrane protein 1 activates several oncogenic signaling axes causing multiple malignant phenotypes and therapeutic resistance. Also, Epstein-Barr virus up-regulates DNA methyltransferase 1 and mediates onco-epigenetic effects in the carcinogenesis. The collaborating pathways activated by latent membrane protein 1 constructs an oncogenic signaling network, which makes latent membrane protein 1 an important potential target for effective treatment or preventive intervention. In Epstein-Barr virus lytic phase, the plasma level of Epstein-Barr virus DNA is considered as a distinguishing marker for nasopharyngeal carcinoma in subjects from healthy high-risk populations and is also a novel prognostic marker in Epstein-Barr virus-positive nasopharyngeal carcinoma. Now the early detection and screening of the lytic proteins and Epstein-Barr virus DNA have been applied to clinical and high-risk population. The knowledge generated regarding Epstein-Barr virus can be used in Epstein-Barr virus based precision cancer prevention and therapy in the near future.

miR-16 targets fibroblast growth factor 2 to inhibit NPC cell proliferation and invasion via PI3K/AKT and MAPK signaling pathways

Dysregulation of miRNAs has been shown to contribute to the carcinogenesis and progression of nasopharyngeal carcinoma (NPC). Our previous microarray data showed that miR-16 expression is significantly decreased in archived NPC tissues. Here, we confirmed that miR-16 was reduced in NPC cell lines and freshly-frozen samples. Ectopic expression of miR-16 suppressed NPC cell proliferation, migration, and invasion in vitro and inhibited tumor growth and metastatic colonization in the lung in vivo. Furthermore, fibroblast growth factor 2 (FGF2) was identified as a direct target of miR-16, and both phosphoinositide-3- kinase/AKT (PI3K/AKT) and mitogen-activated protein kinase (MAPK) signaling pathways were repressed after miR-16 overexpression. In addition, the restoration of FGF2 reversed the suppressive effects of miR-16. Together, these results indicated that miR-16 suppresses NPC carcinogenesis and progression by targeting FGF2, thereby representing a potential target for miRNA-based therapy for NPC in the future.

MicroRNAs serve as a bridge between oxidative stress and gastric cancer (Review)

Gastric cancer (GC) remains one of the most prevalent tumors worldwide and affects human health due to its high morbidity and mortality. Mechanisms underlying occurrence and development of GC have been widely studied. Studies have revealed reactive oxygen species (ROS) generated by cells under oxidative stress (OS) are involved in gastric tumorigenesis, and modulate expression of microRNAs (miRs). As such, miRs have been shown to be associated with OS-related GC. Given the association of OS and miRs in development of GC, this review aims to summarize the relationship between miRs and OS and their role in GC development. Serving as a link between OS and GC, miRs may offer new approaches for gaining a more in-depth understanding of mechanisms of GC and may lead to the identification of new therapeutic approaches against GC.

Identification of miRNA/mRNA-Negative Regulation Pairs in Nasopharyngeal Carcinoma

Background

Nasopharyngeal carcinoma (NPC) is a common malignancy in South-East Asia. NPC is characterized by distant metastasis and poor prognosis. The pathophysiological mechanism of nasopharyngeal carcinoma is unknown. This study aimed to identify the crucial miRNAs in nasopharyngeal carcinoma and their target genes, and to discover the potential mechanism of nasopharyngeal carcinoma development.

Material/Methods

Microarray expression profiling of miRNA and mRNA from the Gene Expression Omnibus database was downloaded, and we performed a significance analysis of differential expression. An interaction network of miRNAs and target genes was constructed. The underlying function of differentially expressed genes was predicted through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. To validate the microarray analysis data, significantly different expression levels of miRNAs and target genes were validated by quantitative real-time polymerase chain reaction.

Results

We identified 27 differentially expressed miRNAs and 982 differentially expressed mRNAs between NPC and normal control tissues. 12 miRNAs and 547 mRNAs were up-regulated and 15 miRNAs and 435 mRNAs were down-regulated in NPC samples. We found a total of 1185 negative correlation pairs between miRNA and mRNA. Differentially expressed target genes were significantly enriched in pathways in cancer, cell cycle, and cytokine-cytokine receptor interaction signaling pathways. Significantly differentially expressed miRNAs and genes, such as hsa-miR-205, hsa-miR-18b, hsa-miR-632, hsa-miR-130a, hsa-miR-34b, PIGR, SMPD3, CD22, DTX4, and CDC6, may play essential roles in the development of nasopharyngeal carcinoma.

Conclusions

hsa-miR-205, hsa-miR-18b, hsa-miR-632, hsa-miR-130a, and hsa-miR-34b may be related to the development of nasopharyngeal carcinoma by regulating the genes involved in pathways in cancer and cell cycle signaling pathways.