MiR-218 increases sensitivity to cisplatin in esophageal cancer cells via targeting survivin expression

Biological and therapeutic viewpoints towards role of miR-218 in human cancers: Revisiting molecular interactions and future clinical translations

Understanding the exact pathogenesis of cancer is difficult due to heterogenous nature of tumor cells and multiple factors that cause its initiation and development. Treatment of cancer is mainly based on surgical resection, chemotherapy, radiotherapy and their combination, while gene therapy has been emerged as a new kind of therapy for cancer. Post-transcriptional regulation of genes has been of interest in recent years and among various types of epigenetic factors that can modulate gene expression, short non-coding RNAs known as microRNAs (miRNAs) have obtained much attention. The stability of mRNA decreases by miRNAs to repress gene expression. miRNAs can regulate tumor malignancy and biological behavior of cancer cells and understanding their function in tumorigenesis can pave the way towards developing new therapeutics in future. One of the new emerging miRNAs in cancer therapy is miR-218 that increasing evidence highlights its anti-cancer activity, while a few studies demonstrate its oncogenic function. The miR-218 transfection is promising in reducing progression of tumor cells. miR-218 shows interactions with molecular mechanisms including apoptosis, autophagy, glycolysis and EMT, and the interaction is different. miR-218 induces apoptosis, while it suppresses glycolysis, cytoprotective autophagy and EMT. Low expression of miR-218 can result in development of chemoresistance and radio-resistance in tumor cells and direct targeting of miR-218 as a key player is promising in cancer therapy. LncRNAs and circRNAs are nonprotein coding transcripts that can regulate miR-218 expression in human cancers. Moreover, low expression level of miR-218 can be observed in human cancers such as brain, gastrointestinal and urological cancers that mediate poor prognosis and low survival rate.

NGS-based profiling identifies miRNAs and pathways dysregulated in cisplatin-resistant esophageal cancer cells

Esophageal cancer (EC) incidence remains to be on a global rise supported by an unchanged recurrence and 5-year survival rate owing to the development of chemoresistance. Resistance to cisplatin, one of the majorly used chemotherapeutic drugs in EC, is a major nuisance. This study sheds light on miRNA dysregulation and its inverse relation with dysregulated mRNAs to guide pathways into the manifestation of cisplatin resistance in EC. A cisplatin-resistant version of an EC cell line was established and comparative profiling by NGS with the parental cell line was employed to identify dysregulation in miRNA and mRNA levels. Protein-protein interaction network analysis was done using Cytoscape, followed by Funrich pathway analysis. Furthermore, selective significant miRNAs were validated using qRT-PCR. miRNA-mRNA integrated analysis was carried out using the Ingenuity Pathway Analysis (IPA) tool. Expression of various established resistance markers supported the successful establishment of cisplatin-resistant cell line. Whole-cell small RNA sequencing and transcriptome sequencing identified 261 miRNAs and 1892 genes to be significantly differentially expressed (DE), respectively. Pathway analysis indicated enrichment of EMT signaling, supported by NOTCH, mTOR, TNF receptor, and PI3K-mediated AKT signaling pathways, in chemoresistant cells. Validation by qRT-PCR confirmed upregulation of miR-10a-5p, miR-618, miR-99a-5p, and miR-935 and downregulation of miR-335-3p, miR-205-5p, miR-944, miR-130a-3p, and miR-429 in resistant cells. Pathway analysis that followed IPA analysis indicated that the dysregulation of these miRNAs and their target genes may be instrumental in the development and regulation of chemoresistance via p53 signaling, xenobiotic metabolism, and NRF2-mediated oxidative stress. This study concludes the interplay between miRNA and mRNA as an important aspect and occurrence in guiding the regulation, acquisition, and maintenance of chemoresistance in esophageal cancer in vitro.

Noncoding RNAs in esophageal cancer: A glimpse into implications for therapy resistance

Esophageal cancer (EC) is one of the most common malignancies of the digestive system and has a high morbidity and mortality worldwide. Chemotherapy in combination with radiotherapy is one of the most important treatment modalities for EC. Chemoradiotherapy is currently acknowledged worldwide as being the standard treatment for locally advanced or unresectable disease. Unfortunately, due to the existence of therapy resistance, a number of EC patients fail to benefit from drug or irradiation treatment, which ultimately leads to poor outcomes. Considerable efforts have been made to explore the mechanisms underlying the therapy resistance of EC. Notably, noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), are current research areas for the modulation of therapy responses and may serve as new targets to overcome treatment resistance in EC. Herein, we summarized the mechanisms by which ncRNAs are involved in drug and radiation resistance in EC and highlighted their role in promoting or repressing treatment resistance. Additionally, we discussed the clinical relevance of ncRNAs, which may serve as potential therapeutic targets and predictive biomarkers for EC.

Molecular mechanisms associated with chemoresistance in esophageal cancer

Esophageal cancer (EC) is one of the most incident and lethal tumors worldwide. Although surgical resection is an important approach in EC treatment, late diagnosis, metastasis and recurrence after surgery have led to the management of adjuvant and neoadjuvant therapies over the past few decades. In this scenario, 5-fluorouracil (5-FU) and cisplatin (CISP), and more recently paclitaxel (PTX) and carboplatin (CBP), have been traditionally used in EC treatment. However, chemoresistance to these agents along EC therapeutic management represents the main obstacle to successfully treat this malignancy. In this sense, despite the fact that most of chemotherapy drugs were discovered several decades ago, in many cases, including EC, they still represent the most affordable and widely employed treatment approach for these tumors. Therefore, this review summarizes the main mechanisms through which the response to the most widely chemotherapeutic agents used in EC treatment is impaired, such as drug metabolism, apoptosis resistance, cancer stem cells (CSCs), cell cycle, autophagy, energetic metabolism deregulation, tumor microenvironment and epigenetic modifications.

Novel Implications of MicroRNAs, Long Non-coding RNAs and Circular RNAs in Drug Resistance of Esophageal Cancer

Esophageal cancer is the eighth most common malignancy and the sixth leading cause of cancer-related deaths worldwide. Chemotherapy based on platinum drugs, 5-fluorouracil, adriamycin, paclitaxel, gemcitabine, and vinorelbine, as well as targeted treatment and immunotherapy with immune checkpoint inhibitors improved the prognosis in a portion of patients with advanced esophageal cancer. Unfortunately, a number of esophageal cancer patients develop drug resistance, resulting in poor outcomes. Multiple mechanisms contributing to drug resistance of esophageal cancer have been reported. Notably, non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), have been identified to play crucial roles in modulating esophageal cancer drug resistance. In the present review, we highlight the underlying mechanisms how miRNAs, lncRNAs, and circRNAs impact the drug resistance of esophageal cancer. Several miRNAs, lncRNAs, and circRNAs may have potential clinical implications as novel biomarkers and therapeutic targets for esophageal cancer.

miRNAs Involved in Esophageal Carcinogenesis and miRNA-Related Therapeutic Perspectives in Esophageal Carcinoma

MicroRNAs (miRNAs) are small non-coding RNAs that play a pivotal role in many aspects of cell biology, including cancer development. Within esophageal cancer, miRNAs have been proved to be involved in all phases of carcinogenesis, from initiation to metastatic spread. Several miRNAs have been found to be dysregulated in esophageal premalignant lesions, namely Barrett’s esophagus, Barrett’s dysplasia, and squamous dysplasia. Furthermore, numerous studies have investigated the alteration in the expression levels of many oncomiRNAs and tumor suppressor miRNAs in esophageal squamous cell carcinoma and esophageal adenocarcinoma, thus proving how miRNAs are able modulate crucial regulatory pathways of cancer development. Considering these findings, miRNAs may have a role not only as a diagnostic and prognostic tool, but also as predictive biomarker of response to anti-cancer therapies and as potential therapeutic targets. This review aims to summarize several studies on the matter, focusing on the possible diagnostic–therapeutic implications.

MicroRNA-218 regulates the chemo-sensitivity of cervical cancer cells through targeting survivin

Background: Cervical cancer is one of the most lethal malignancies among women in the world. Every year about 311,365 women die because of cervical cancer. Chemo-resistance is the main reason of the lethal malignancies, and the mechanism of chemo-resistance in cervical cancer still remains largely elusive. Purpose: Previous studies reported that microRNAs played important biological roles in the chemo-resistance in many types of cancers, in the present study we tried to investigate the biological roles of microRNA-218 in chemo-resistance in cervical cancer cells. Results: Real-time PCR results indicated microRNA-218 was downregulated in cisplatin-resistant HeLa/DDP and SiHa/DDP cells compared with the mock HeLa and SiHa cells. CCK-8 assay results showed upregulation of microRNA-218 enhanced the cisplatin sensitivity of cervical cancer cells; while downregulation of microRNA-218 decreased the cisplatin sensitivity of cervical cancer cells. Dual-luciferase assay indicated survivin was a direct target of microRNA-218. Western blotting and PCR results indicated the expression of survivin in HeLa/DDP and SiHa/DDP cells was significantly increased compared with HeLa and SiHa cells. Further study indicated induction of microRNA-218 decreased the expression of survivin while inhibition of microRNA-218 increased the expression of survivin in cervical cancer cells. Cell apoptosis results indicated induction of microRNA-218 induced the cell apoptosis in cervical cancer cells. Conclusion: Our data revealed microRNA-218 enhanced the cisplatin sensitivity in cervical cancer cells through regulation of cell growth and cell apoptosis, which could potentially benefit to the cervical cancer treatment in the future.

Diagnostic biomarker and therapeutic target applications of miR-326 in cancers: A systematic review

MicroRNAs (miRNAs) are endogenous mediators of RNA interference and have key roles in the modulation of gene expression under healthy, inflamed, stimulated, carcinogenic, or other cells, and tissues of a pathological state. Many studies have proved the association between miRNAs and cancer. The role of miR-326 as a tumor suppressor miRNA in much human cancer confirmed. We will explain the history and the role of miRNAs changes, especially miR-326 in cancers and other pathological conditions. Attuned with these facts, this review highlights recent preclinical and clinical research performed on miRNAs as novel promising diagnostic biomarkers of patients at early stages, prediction of prognosis, and monitoring of the patients in response to treatment. All related publications retrieved from the PubMed database, with keywords such as epigenetic, miRNA, microRNA, miR-326, cancer, diagnostic biomarker, and therapeutic target similar terms from 1899 to 2018 with limitations in the English language. Recently, researchers have focused on the impacts of miRNAs and their association in inflammatory, autoinflammatory, and cancerous conditions. Recent studies have suggested a major pathogenic role in cancers and autoinflammatory diseases. Investigations have explained the role of miRNAs in cancers, autoimmunity, and autoinflammatory diseases, and so on. The miRNA-326 expression has an important role in cancer conditions and other diseases.

Survivin is a prognostic indicator in glioblastoma and may be a target of microRNA-218

Accumulating evidence has revealed that survivin expression is associated with a malignant phenotype and poor prognosis in glioma. Survivin is also a potential target of microRNA (miRNA/miR)-218. The aim of the present study was to investigate the expression and function of survivin in glioblastoma, and to examine the association between survivin and miR-218. For that purpose, survivin mRNA levels were analyzed in 144 frozen samples of glioblastoma using whole-genome RNA sequencing. In vitro cell proliferation, migration, invasion and apoptosis assays were performed, and survivin expression was detected by western blotting. The results revealed that the mRNA expression levels of survivin were negatively and significantly associated with overall survival in glioblastoma. Further in vitro analyses suggested that miR-218 may inhibit the expression of survivin. Expression of miR-218 in the LN229 cell line was significantly lower than that in the immortalized human gliocyte HEB cell line. miR-218 markedly inhibited tumor cell proliferation, migration and invasion capacities, and decreased apoptosis. miR-218 also inhibited the expression of survivin. These results indicated that survivin may be a target of miR-218 and could serve as a predictive biomarker.

Smac combined with DDP can inhibit drug resistance of ovarian cancer through regulation of Survivin expression

Ovarian cancer has the highest mortality rate among gynecological malignancies, presenting a major threat to women's life and health. It is essential to study the mechanisms of drug resistance to chemotherapy to identify ways to enhance drug-sensitivity. In recent years, many studies have shown that Smac/DIABLO is closely related to tumor drug resistance. Smac/DIABLO expression is markedly different between drug-resistant and chemo sensitive tumor cells. Up-regulation of Smac/DIABLO has been shown to increase tumor cell chemotherapy sensitivity. We found that Smac, combined with DDP greatly inhibited proliferation of subcutaneous xenografts of ovarian cancer cell line SKOV3/DDP without side effects. Mechanistic studies showed that Smac can inhibit the expression of Survivin, promote cell apoptosis of drug-resistant ovarian cancer cells and reverse the drug resistance.

Morin inhibits proliferation and self-renewal of CD133+ melanoma cells by upregulating miR-216a

Melanoma is one of the most malignant skin tumors with high mortality rate. Morin has been reported to treat several cancers. However, whether or how Morin affects melanoma progression is still poorly understood. Either Morin treatment or miR-216a overexpression reduced cell viability, sphere formation ability and expressions of stem cell marker genes CD20, CD44, CD133 and Wnt-3A. MiR-216a was induced by Morin treatment in CD133⁺ melanoma cells. Melanoma xenograft model treated by Morin showed reduced tumor size, weight as well as expressions of stemness markers and Wnt-3A. Inhibition of the stemness marker gene expressions in CD133⁺ melanoma cells is mediated by downregulating Wnt-3A through miR-216a. MiR-216a and Wnt-3A may potentially serve as clinical biomarkers of melanoma, and Morin may contribute to the treatment of melanoma.

Pharmacoepigenetics and pharmacoepigenomics of gastrointestinal cancers

Our understanding of the epigenetic changes occurring in gastrointestinal cancers has gained tremendous advancements in recent years, and some epigenetic biomarkers are already translated into the clinics for cancer diagnostics. In parallel, pharmacoepigenetics and pharmacoepigenomics of solid tumors are relevant novel, but emerging and promising fields. Areas covered: A comprehensive review of the literature to summarize and update the emerging field of pharmacoepigenetics and pharmacoepigenomics of gastrointestinal cancers. Expert commentary: Several epigenetic modifications have been proposed to account for interindividual variations in drug response in gastrointestinal cancers. Similarly, single-agent or combined strategies with high doses of drugs that target epigenetic modifications (epi-drugs) were scarcely tolerated by the patients, and current research has moved to their combination with standard therapies to achieve chemosensitization, radiosensitization, and immune modulation of cancerous cells. In parallel, recent genome-wide technologies are revealing the pathways that are epigenetically deregulated during cancer-acquired resistance, including those targeted by non-coding RNAs. Indeed, novel, less toxic, and more specific molecules are under investigation to specifically target those pathways. The field is rapidly expanding and gathering together information coming from these investigations has the potential to lead to clinical applications in the coming new years.