Therapeutic evaluation of microRNA-15a and microRNA-16 in ovarian cancer

Deciphering the Molecular Mechanisms behind Drug Resistance in Ovarian Cancer to Unlock Efficient Treatment Options

Ovarian cancer is a highly lethal form of gynecological cancer. This disease often goes undetected until advanced stages, resulting in high morbidity and mortality rates. Unfortunately, many patients experience relapse and succumb to the disease due to the emergence of drug resistance that significantly limits the effectiveness of currently available oncological treatments. Here, we discuss the molecular mechanisms responsible for resistance to carboplatin, paclitaxel, polyadenosine diphosphate ribose polymerase inhibitors, and bevacizumab in ovarian cancer. We present a detailed analysis of the most extensively investigated resistance mechanisms, including drug inactivation, drug target alterations, enhanced drug efflux pumps, increased DNA damage repair capacity, and reduced drug absorption/accumulation. The in-depth understanding of the molecular mechanisms associated with drug resistance is crucial to unveil new biomarkers capable of predicting and monitoring the kinetics during disease progression and discovering new therapeutic targets.

Next generation sequencing uncovers multiple miRNAs associated molecular targets in gallbladder cancer patients

Gallbladder cancer (GBC) is a lethal disease with surgical resection as the only curative treatment. However, many patients are ineligible for surgery, and current adjuvant treatments exhibit limited effectiveness. Next-generation sequencing has improved our understanding of molecular pathways in cancer, sparking interest in microRNA-based gene regulation. The aim of the study is to identify dysregulated miRNAs in GBC and investigate their potential as therapeutic tools for effective and targeted treatment strategies. GBC and control tissue samples were sequenced for miRNA expression using the Illumina HiSeq platform. Biological processes and related pathways were determined using the Panther and Gene Ontology databases. 439 significantly differentially expressed miRNAs were identified; 19 of them were upregulated and 29 were downregulated. Key enriched biological processes included immune cell apoptosis, endoplasmic reticulum (ER) overload response, and negative regulation of the androgen receptor (AR) signaling pathway. Panther analysis revealed the insulin-like growth factor (IGF)-mitogen activated protein kinases (MAPK) cascade, p38 MAPK pathway, p53 pathway, and FAS (a subgroup of the tumor necrosis factor receptor) signaling pathway as highly enriched among dysregulated miRNAs. Kirsten rat sarcoma virus (KRAS), AR, and interferon gamma (IFN-γ) pathways were identified among the key pathways potentially amenable to targeted therapy. We concluded that a combination approach involving miRNA-based interventions could enhance therapeutic outcomes. Our research emphasizes the importance of precision medicine, targeting pathways using sense and anti-sense miRNAs as potential therapies in GBC.

Ovarian Cancer—Insights into Platinum Resistance and Overcoming It

Ovarian cancer is the most lethal gynecologic malignancy. Platinum-based chemotherapy is the backbone of treatment for ovarian cancer, and although the majority of patients initially have a platinum-sensitive disease, through multiple recurrences, they will acquire resistance. Platinum-resistant recurrent ovarian cancer has a poor prognosis and few treatment options with limited efficacy. Resistance to platinum compounds is a complex process involving multiple mechanisms pertaining not only to the tumoral cell but also to the tumoral microenvironment. In this review, we discuss the molecular mechanism involved in ovarian cancer cells’ resistance to platinum-based chemotherapy, focusing on the alteration of drug influx and efflux pathways, DNA repair, the dysregulation of epigenetic modulation, and the involvement of the tumoral microenvironment in the acquisition of the platinum-resistant phenotype. Furthermore, we review promising alternative treatment approaches that may improve these patients’ poor prognosis, discussing current strategies, novel combinations, and therapeutic agents.

Insight on Non-Coding RNAs from Biofluids in Ovarian Tumors

Ovarian tumors are the most frequent adnexal mass, raising diagnostic and therapeutic issues linked to a large spectrum of tumors, with a continuum from benign to malignant. Thus far, none of the available diagnostic tools have proven efficient in deciding strategy, and no consensus exists on the best strategy between "single test", "dual testing", "sequential testing", "multiple testing options" and "no testing". In addition, there is a need for prognostic tools such as biological markers of recurrence and theragnostic tools to detect women not responding to chemotherapy in order to adapt therapies. Non-coding RNAs are classified as small or long based on their nucleotide count. Non-coding RNAs have multiple biological functions such as a role in tumorigenesis, gene regulation and genome protection. These ncRNAs emerge as new potential tools to differentiate benign from malignant tumors and to evaluate prognostic and theragnostic factors. In the specific setting of ovarian tumors, the goal of the present work is to offer an insight into the contribution of biofluid non-coding RNAs (ncRNA) expression.

Epigenetic changes induced by pathogenic Chlamydia spp

Chlamydia trachomatis, C. pneumoniae, and C. psittaci, the three Chlamydia species known to cause human disease, have been collectively linked to several pathologies, including conjunctivitis, trachoma, respiratory disease, acute and chronic urogenital infections and their complications, and psittacosis. In vitro, animal, and human studies also established additional correlations, such as between C. pneumoniae and atherosclerosis and between C. trachomatis and ovarian cancer. As part of their survival and pathogenesis strategies as obligate intracellular bacteria, Chlamydia spp. modulate all three major types of epigenetic changes, which include deoxyribonucleic acid (DNA) methylation, histone post-translational modifications, and microRNA-mediated gene silencing. Some of these epigenetic changes may be implicated in key aspects of pathogenesis, such as the ability of the Chlamydia spp. to induce epithelial-to-mesenchymal transition, interfere with DNA damage repair, suppress cholesterol efflux from infected macrophages, act as a co-factor in human papillomavirus (HPV)-mediated cervical cancer, prevent apoptosis, and preserve the integrity of mitochondrial networks in infected host cells. A better understanding of the individual and collective contribution of epigenetic changes to pathogenesis will enhance our knowledge about the biology of Chlamydia spp. and facilitate the development of novel therapies and biomarkers. Pathogenic Chlamydia spp. contribute to epigenetically-mediated gene expression changes in host cells by multiple mechanisms.

Recent advances of non-coding RNAs in ovarian cancer prognosis and therapeutics

Ovarian cancer (OC) is the third most common gynecological malignancy with the highest mortality worldwide. OC is usually diagnosed at an advanced stage, and the standard treatment is surgery combined with platinum or paclitaxel chemotherapy. However, chemoresistance inevitably appears coupled with the easy recurrence and poor prognosis. Thus, early diagnosis, predicting prognosis, and reducing chemoresistance are of great significance for controlling the progression and improving treatment effects of OC. Recently, much insight has been gained into the non-coding RNA (ncRNA) that is employed for RNAs but does not encode a protein, and many types of ncRNAs have been characterized including long-chain non-coding RNAs, microRNAs, and circular RNAs. Accumulating evidence indicates these ncRNAs play very active roles in OC progression and metastasis. In this review, we briefly discuss the ncRNAs as biomarkers for OC prognosis. We focus on the recent advances of ncRNAs as therapeutic targets in preventing OC metastasis, chemoresistance, immune escape, and metabolism. The novel strategies for ncRNAs-targeted therapy are also exploited for improving the survival of OC patients.

The Prospective Application of Melatonin in Treating Epigenetic Dysfunctional Diseases

In the past, different human disorders were described by scientists from the perspective of either environmental factors or just by genetically related mechanisms. The rise in epigenetic studies and its modifications, i.e., heritable alterations in gene expression without changes in DNA sequences, have now been confirmed in diseases. Modifications namely, DNA methylation, posttranslational histone modifications, and non-coding RNAs have led to a better understanding of the coaction between epigenetic alterations and human pathologies. Melatonin is a widely-produced indoleamine regulator molecule that influences numerous biological functions within many cell types. Concerning its broad spectrum of actions, melatonin should be investigated much more for its contribution to the upstream and downstream mechanistic regulation of epigenetic modifications in diseases. It is, therefore, necessary to fill the existing gaps concerning corresponding processes associated with melatonin with the physiological abnormalities brought by epigenetic modifications. This review outlines the findings on melatonin’s action on epigenetic regulation in human diseases including neurodegenerative diseases, diabetes, cancer, and cardiovascular diseases. It summarizes the ability of melatonin to act on molecules such as proteins and RNAs which affect the development and progression of diseases.

The role of miRNAs as a big master regulator of signaling pathways involved in lymphoblastic leukemia

MicroRNAs (miRNAs) belong to small noncoding RNAs, which have long attracted researchers' attention because of their potency in acting either as oncogenes or tumor-suppressors in cancers. acute lymphocytic leukemia (ALL) and chronic lymphocytic leukemia (CLL) are two known types of leukemia with high mortality rates in adults and children. On a molecular basis, various signaling pathways are active in both types, making researchers consider the potential role of miRNAs in activating or suppressing these pathways to further hinder cancer development. In this review, we summarized the potential miRNAs, especially circulating ones, involved in essential signaling pathways in the ALL and CLL patients which serve as biomarkers and valuable targets in the treatment fields.

Cancer Stem Cells in Ovarian Cancer-A Source of Tumor Success and a Challenging Target for Novel Therapies

Ovarian cancer is the most lethal neoplasm of the female genital organs. Despite indisputable progress in the treatment of ovarian cancer, the problems of chemo-resistance and recurrent disease are the main obstacles for successful therapy. One of the main reasons for this is the presence of a specific cell population of cancer stem cells. The aim of this review is to show the most contemporary knowledge concerning the biology of ovarian cancer stem cells (OCSCs) and their impact on chemo-resistance and prognosis in ovarian cancer patients, as well as to present the treatment options targeted exclusively on the OCSCs. The review presents data concerning the role of cancer stem cells in general and then concentrates on OCSCs. The surface and intracellular OCSCs markers and their meaning both for cancer biology and clinical prognosis, signaling pathways specifically activated in OCSCs, the genetic and epigenetic regulation of OCSCs function including the recent studies on the non-coding RNA regulation, cooperation between OCSCs and the tumor microenvironment (ovarian cancer niche) including very specific environment such as ascites fluid, the role of shear stress, autophagy and metabolic changes for the function of OCSCs, and finally mechanisms of OCSCs escape from immune surveillance, are described and discussed extensively. The possibilities of anti-OCSCs therapy both in experimental settings and in clinical trials are presented, including the recent II phase clinical trials and immunotherapy. OCSCs are a unique population of cancer cells showing a great plasticity, self-renewal potential and resistance against anti-cancer treatment. They are responsible for the progression and recurrence of the tumor. Several completed and ongoing clinical trials have tested different anti-OCSCs drugs which, however, have shown unsatisfactory efficacy in most cases. We propose a novel approach to ovarian cancer diagnosis and therapy.

Epigenetic Mechanisms and Therapeutic Targets in Chemoresistant High-Grade Serous Ovarian Cancer

High-grade serous ovarian cancer (HGSOC) is the most common ovarian cancer subtype, and the overall survival rate has not improved in the last three decades. Currently, most patients develop recurrent disease within 3 years and succumb to the disease within 5 years. This is an important area of research, as the major obstacle to the treatment of HGSOC is the development of resistance to platinum chemotherapy. The cause of chemoresistance is still largely unknown and may be due to epigenetics modifications that are driving HGSOC metastasis and treatment resistance. The identification of epigenetic changes in chemoresistant HGSOC enables the development of epigenetic modulating drugs that may be used to improve outcomes. Several epigenetic modulating drugs have displayed promise as drug targets for HGSOC, such as demethylating agents azacitidine and decitabine. Others, such as histone deacetylase inhibitors and miRNA-targeting therapies, demonstrated promising preclinical results but resulted in off-target side effects in clinical trials. This article reviews the epigenetic modifications identified in chemoresistant HGSOC and clinical trials utilizing epigenetic therapies in HGSOC.

Comparative expression analysis of tRF-3001a and tRF-1003 with corresponding miRNAs (miR-1260a and miR-4521) and their network analysis with breast cancer biomarkers

BACKGROUND

MicroRNAs and tRFs (tRNA-derived fragments) are small non-coding RNAs that are promising breast cancer (BC) biomarkers. miRNA sequences are found within tRFs. For example, miR-1260a and miR-4521 sequences are found within tRF-3001a and tRF-1003, respectively. No study has addressed the biomarker potential of these tRF-miRNA pairs in BC or their association with other BC miRNA biomarkers.

METHODS AND RESULTS

Real-time PCR was performed to examine the expression of miR-1260a-tRF-3001a and miR-4521-tRF-1003 pairs in plasma of BC patients. miR-4521 and miR-1260a showed no change in plasma of breast cancer patients (n = 19). On the contrary, both the corresponding tRFs (tRF-1003 and tRF-3001a) were down-regulated. Also, we performed miRNA/mRNA network analysis for miR-1260a and miR-4521 with top degree BC biomarkers miR-16-5p and miR-93-5p. We found that they shared nine target genes. Moreover, miR-16-5p was down-regulated, and miR-93-5p was up-regulated in the same sample set. Survival analysis plotted using clinical data from Kaplan-Meier Plotter showed that all four miRNAs and 8/9 target gene expressions could predict the survival of BC patients.

CONCLUSIONS

Our cohort analyses suggest that tRF-3001a and tRF-1003 serve as better biomarkers than their miRNA counterparts in addition to miR-93-5p and miR-16-5p. Also, they form a significant miRNA/mRNA biomarker cluster.

Common miRNAs, candidate genes and their interaction network across four subtypes of epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is categorized into four major histological subtypes such as clear cell carcinoma (CCC), endometrioid carcinoma (EC), mucinous carcinoma (MC), and serous carcinoma (SC). Heterogeneity of the EOC leads to different clinical outcomes of the disease, although all the subtypes are originated from the same layer of tissue. Therefore, it is of interest to identify the common candidate genes, miRNA and their interaction network in four the subtypes of EOC. A comparative gene expression analysis identified 248 common differentially expressed genes (DEGs) in the four subtypes of EOC. Identified common DEGs were found to be enriched in cancer specific pathways. A protein-protein interaction (PPI) network of the common DEGs were constructed, and subsequent module and survival analyses identified seven key candidate genes (CCNB1, CENPM, CEP55, RACGAP1, TPX2, UBE2C, and ZWINT). We also documented 10 key candidate miRNAs (hsa-mir-16-5p, hsa-mir-23b-3p, hsa-mir-34a-5p, hsa-mir-103a-3p, hsa-mir-107, hsa-mir-124-3p, hsa-mir-129-2-3p, hsa-mir-147a, hsa-mir-205-5p, and hsa-mir-195-5p) linked to the candidate genes. These derived data find application in the understanding of EOC.

[Development and functional validation of a nano-delivery system of miR-16/polypeptide targeting ovarian cancer cells]

OBJECTIVE

To develop a nano-delivery system for targeted delivery of miR-16/polypeptide for enhancing cisplatin sensitivity of ovarian cancer.

OBJECTIVE

R9-SS-R9 and cRGD-R9-SS-R9 peptides were synthesized and self-assembled with miR-16 molecules to form a nano-delivery system. The stability, particle size, potential and morphology of the nanoparticles were determined by agarose gel electrophoresis, particle size potentiometer and transmission electron microscopy. CCK-8 assay was used to assess the toxicity of the polypeptides in ovarian cancer cells. Stem loop qRT-PCR and living cell imaging were used to verify the uptake efficiency and intracellular distribution of the nanoparticles. Flow cytometry and Western blotting were performed to verify the effect of the nanoparticles for enhancing cisplatin sensitivity of ovarian cancer cells and explore the possible mechanism.

OBJECTIVE

R9-SS-R9/miR-16 and cRGD-R9-SS-R9/miR-16 nanoparticles were successfully prepared. The nanoparticles, with a particle size below 150 nm, a dispersity index less than 0.1 and a potential of about 40 mV, showed a good serum stability. The polypeptide material had no obvious cytotoxicity. The miR-16/polypeptide nanoparticles could be efficiently absorbed by human ovarian cancer cells and were distributed in the cytoplasm. The nanoparticles significantly increased the intracellular expression level of miR-16 (P < 0.001) and decreased the expression of Bcl-2 and Chk-1 proteins in ovarian cancer cells, thus enabling miR-16 to promote apoptosis and enhance cisplatin sensitivity of the cells.

OBJECTIVE

We successfully prepared a miR-16/polypeptide nano-delivery system for targeted delivery of miR-16 to ovarian cancer cells for enhancing cisplatin sensitivity of the cancer cells.

MicroRNA Therapeutics in Cancer: Current Advances and Challenges

Simple Summary

Cancer is a complex disease associated with deregulation of numerous genes. In addition, redundant cellular pathways limit efficiency of monotarget drugs in cancer therapy. MicroRNAs are a class of gene expression regulators, which often function by targeting multiple genes. This feature makes them a double-edged sword (a) as attractive targets for anti-tumor therapy and concomitantly (b) as risky targets due to their potential side effects on healthy tissues. As for conventional antitumor drugs, nanocarriers have been developed to circumvent the problems associated with miRNA delivery to tumors. In this review, we highlight studies that have established the pre-clinical proof-of concept of miRNAs as relevant therapeutic targets in oncology. Particular attention was brought to new strategies based on nanovectorization of miRNAs as well as to the perspectives for their applications.

Abstract

The discovery of microRNAs (miRNAs) in 1993 has challenged the dogma of gene expression regulation. MiRNAs affect most of cellular processes from metabolism, through cell proliferation and differentiation, to cell death. In cancer, deregulated miRNA expression leads to tumor development and progression by promoting acquisition of cancer hallmark traits. The multi-target action of miRNAs, which enable regulation of entire signaling networks, makes them attractive tools for the development of anti-cancer therapies. Hence, supplementing downregulated miRNA by synthetic oligonucleotides or silencing overexpressed miRNAs through artificial antagonists became a common strategy in cancer research. However, the ultimate success of miRNA therapeutics will depend on solving pharmacokinetic and targeted delivery issues. The development of a number of nanocarrier-based platforms holds significant promises to enhance the cell specific controlled delivery and safety profile of miRNA-based therapies. In this review, we provide among the most comprehensive assessments to date of promising nanomedicine platforms that have been tested preclinically, pertaining to the treatment of selected solid tumors including lung, liver, breast, and glioblastoma tumors as well as endocrine malignancies. The future challenges and potential applications in clinical oncology are discussed.

Oncogenesis and Tumor Inhibition by MicroRNAs and its Potential Therapeutic Applications: A Systematic Review

MicroRNAs appear as small molecule modifiers, which improve many new findings and mechanical illustrations for critically important biological phenomena and pathologic events. The best-characterized non-coding RNA family consists of about 2600 human microRNAs. Rich evidence has revealed their crucial importance in maintaining normal development, differentiation, growth control, aging, modulation of cell survival or apoptosis, as well as migration and metastasis as microRNAs dysregulation leads to cancer incidence and progression. By far, microRNAs have recently emerged as attractive targets for therapeutic intervention. The rationale for developing microRNA therapeutics is based on the premise that aberrantly expressed microRNAs play a significant role in the emergence of a variety of human diseases ranging from cardiovascular defects to cancer, and that repairing these microRNA deficiencies by either antagonizing or restoring microRNA function may yield a therapeutic benefit. Although microRNA antagonists are conceptually similar to other inhibitory therapies, improving the performance of microRNAs by microRNA replacement or inhibition that is a less well- described attitude. In this assay, we have condensed the last global knowledge and concepts regarding the involvement of microRNAs in cancer emergence, which has been achieved from the previous studies, consisting of the regulation of key cancer-related pathways, such as cell cycle control and the DNA damage response and the disruption of profile expression in human cancer. Here, we have reviewed the special characteristics of microRNA replacement and inhibition therapies and discussed explorations linked with the delivery of microRNA mimics in turmeric cells. Besides, the achievement of biomarkers based on microRNAs in clinics is considered as novel non-invasive biomarkers in diagnostic and prognostic assessments.

Oleuropein reduces cisplatin resistance in ovarian cancer by targeting apoptotic pathway regulators

AIMS

Despite many attempts to treat ovarian cancer, 13,940 individuals perish annually due to this disease worldwide. Chemotherapy is the main approach to ovarian cancer treatment, but the development of drug resistance is a major obstacle to the successful treatment. Oleuropein is a phenolic ingredient with anticancer characteristics. This study was aimed at investigating the effect of oleuropein on cell viability, cisplatin resistance, and apoptosis, as well as the expression levels of miR-34a, miR-125b, miR16, miR-21, and some of their potential target genes in ovarian cancer cells.

MAIN METHODS

A2780S and A2780/CP cell lines were exposed to different concentrations of oleuropein alone or in combination with cisplatin for 48 h and 72 h. After that, the cell viability and apoptosis were evaluated using MTT assay and flow cytometry, respectively. Bioinformatics analyses were conducted using STRING database and Cytoscape software. The effect of oleuropein and/or cisplatin on the expression of miRNAs and target genes was assessed via Real-time PCR.

KEY FINDINGS

Upon treatment with oleuropein, the expression of P21, P53, and TNFRSF10B increased while that of Bcl-2 and Mcl1 decreased. Moreover, this is the 1st report of a significant decrease in the expression of miR-21 and increase in the expression of miR-34a, miR-125b, and miR16 by oleuropein and/or cisplatin in ovarian cancer cells.

SIGNIFICANCE

Altogether, these data revealed that oleuropein regulated the expression of the above-mentioned miRNAs in ovarian cancer cells, which potentially resulted in apoptosis induction, cell proliferation inhibition, and cisplatin resistance decline in ovarian cancer cells. To confirm the results of this study, it is suggested that similar experiments be performed in animal models of ovarian cancer.

Small Non-Coding-RNA in Gynecological Malignancies

Gynecologic malignancies, which include cancers of the cervix, ovary, uterus, vulva, vagina, and fallopian tube, are among the leading causes of female mortality worldwide, with the most prevalent being endometrial, ovarian, and cervical cancer. Gynecologic malignancies are complex, heterogeneous diseases, and despite extensive research efforts, the molecular mechanisms underlying their development and pathology remain largely unclear. Currently, mechanistic and therapeutic research in cancer is largely focused on protein targets that are encoded by about 1% of the human genome. Our current understanding of 99% of the genome, which includes noncoding RNA, is limited. The discovery of tens of thousands of noncoding RNAs (ncRNAs), possessing either structural or regulatory functions, has fundamentally altered our understanding of genetics, physiology, pathophysiology, and disease treatment as they relate to gynecologic malignancies. In recent years, it has become clear that ncRNAs are relatively stable, and can serve as biomarkers for cancer diagnosis and prognosis, as well as guide therapy choices. Here we discuss the role of small non-coding RNAs, i.e., microRNAs (miRs), P-Element induced wimpy testis interacting (PIWI) RNAs (piRNAs), and tRNA-derived small RNAs in gynecological malignancies, specifically focusing on ovarian, endometrial, and cervical cancer.

Potential Role of miRNAs in the Acquisition of Chemoresistance in Neuroblastoma

Neuroblastoma (NB) accounts for about 8–10% of pediatric cancers, and the main causes of death are the presence of metastases and the acquisition of chemoresistance. Metastatic NB is characterized by MYCN amplification that correlates with changes in the expression of miRNAs, which are small non-coding RNA sequences, playing a crucial role in NB development and chemoresistance. In the present study, miRNA expression was analyzed in two human MYCN-amplified NB cell lines, one sensitive (HTLA-230) and one resistant to Etoposide (ER-HTLA), by microarray and RT-qPCR techniques. These analyses showed that miRNA-15a, -16-1, -19b, -218, and -338 were down-regulated in ER-HTLA cells. In order to validate the presence of this down-regulation in vivo, the expression of these miRNAs was analyzed in primary tumors, metastases, and bone marrow of therapy responder and non-responder pediatric patients. Principal component analysis data showed that the expression of miRNA-19b, -218, and -338 influenced metastases, and that the expression levels of all miRNAs analyzed were higher in therapy responders in respect to non-responders. Collectively, these findings suggest that these miRNAs might be involved in the regulation of the drug response, and could be employed for therapeutic purposes.

MicroRNA-497-5p Functions as a Modulator of Apoptosis by Regulating Metadherin in Ovarian Cancer

Ovarian cancer (OC) has a high mortality rate among women worldwide. However, even with the advances in detection and therapeutics, the number of cases is increasing worldwide. Increasingly, microRNAs (miRNAs), including miR-497-5p, have been implicated in the progression of many cancers, but the role of miR-497-5p in OC remains unknown. The purpose of this study was to investigate the underlying molecular mechanism of miR-497-5p in OC. Herein, we find that miR-497-5p is down-regulated in OC tissues, and overexpression of miR-497-5p enhances apoptosis in OC cells. The increased apoptosis was correlated with enhanced expression of apoptosis-related proteins. MiR-497-5p directly bound the 3'-untranslated region of metadherin (MTDH), leading to the reduction of MTDH in mRNA and protein levels. Moreover, MTDH knockout promoted the apoptosis of OC cells. Taken together, we conclude that miR-497-5p contributes to cell apoptosis in OC by regulating MTDH.

MicroRNA-195 controls MICU1 expression and tumor growth in ovarian cancer

MICU1 is a mitochondrial inner membrane protein that inhibits mitochondrial calcium entry; elevated MICU1 expression is characteristic of many cancers, including ovarian cancer. MICU1 induces both glycolysis and chemoresistance and is associated with poor clinical outcomes. However, there are currently no available interventions to normalize aberrant MICU1 expression. Here, we demonstrate that microRNA-195-5p (miR-195) directly targets the 3' UTR of the MICU1 mRNA and represses MICU1 expression. Additionally, miR-195 is under-expressed in ovarian cancer cell lines, and restoring miR-195 expression reestablishes native MICU1 levels and the associated phenotypes. Stable expression of miR-195 in a human xenograft model of ovarian cancer significantly reduces tumor growth, increases tumor doubling times, and enhances overall survival. In conclusion, miR-195 controls MICU1 levels in ovarian cancer and could be exploited to normalize aberrant MICU1 expression, thus reversing both glycolysis and chemoresistance and consequently improving patient outcomes.

MicroRNA-302 represses epithelial-mesenchymal transition and cisplatin resistance by regulating ATAD2 in ovarian carcinoma

Epithelial-mesenchymal transition (EMT) is an important contributor to drug resistance in ovarian cancer. The aims of this study were to explore the potential role of the miR-302 cluster in modulating EMT and cisplatin resistance in ovarian cancer. We used qRT-PCR and western blotting to show that miR-302 expression was lower in chemoresistant than in chemosensitive cells, and miR-302 was upregulated in chemosensitive, but not chemoresistant ovarian cancer cells in response to cisplatin treatment. We identified ATAD2 as a target of miR-302 and showed that ectopic expression of miR-302 increased cisplatin sensitivity and inhibited EMT and the invasiveness of cisplatin-resistant cells in vitro by targeting ATAD2. Knockdown of ATAD2 restored cisplatin sensitivity and reversed EMT/metastasis in cisplatin-resistant cells, as shown by western blotting and invasion/migration assays. The effect of miR-302 overexpression on EMT and invasiveness was mediated by the modulation of β-catenin nuclear expression. Immunofluorescence analysis showed that ATAD2 overexpression reversed the miR-302-induced downregulation of nuclear β-catenin in cisplatin resistant cells. A xenograft tumor model was used to show that miR-302 increases the antitumor effect of cisplatin in vivo. Taken together, these results identify a potential regulatory axis involving miR-302 and ATAD2 with a role in chemoresistance, indicating that activation of miR-302 or inactivation of ATAD2 could serve as a novel approach to reverse cisplatin resistance in ovarian cancer.

Association of the Expression Level of miR-16 with Prognosis of Solid Cancer Patients: A Meta-Analysis and Bioinformatic Analysis

Objective

To assess the association between the expression level of miR-16 and prognosis of solid cancer patients by meta-analysis and bioinformatic analysis.

Methods

PubMed, Web of Science, and Embase databases were searched until October 31, 2019, to identify eligible studies reporting the association of the miR-16 status with the prognosis of solid cancer patients. Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled, and a heterogeneity test was conducted. Sensitivity analysis and a publication bias test were also carried out. Furthermore, the miRpower database was used to validate the association.

Results

Thirteen articles with 2303 solid cancer patients were included in the meta-analysis. Solid cancer patients with low expression level of miR-16 had shorter survival time (I² = 84.0%, HR = 1.47, 95% CI: 1.13-1.91, P = 0.004). In the subgroup analyses of cancer sites, low miR-16 expression level was associated with poor prognosis in the reproductive system cancers (I² = 33.3%, HR = 1.24, 95% CI: 1.06-1.45, P = 0.008). Sensitivity analysis suggested that the pooled HR was stable and omitting a single study did not change the significance of the pooled HR. Begg's test and Egger's test revealed no publication bias in the meta-analysis. In bioinformatic analysis, the significant association between miR-16 level and prognosis of patients with reproductive system cancers was further confirmed (HR = 1.21, 95% CI: 1.03-1.42, P = 0.017).

Conclusion

Low expression level of miR-16 is an indicator for poor prognosis of solid cancer patients, particularly in reproductive system cancers.

Roles of microRNAs in Ovarian Cancer Tumorigenesis: Two Decades Later, What Have We Learned?

Ovarian cancer is one of the top gynecological malignancies that cause deaths among females in the United States. At the molecular level, significant progress has been made in our understanding of ovarian cancer development and progression. MicroRNAs (miRNAs) are short, single-stranded, highly conserved non-coding RNA molecules (19–25 nucleotides) that negatively regulate target genes post-transcriptionally. Over the last two decades, mounting evidence has demonstrated the aberrant expression of miRNAs in different human malignancies, including ovarian carcinomas. Deregulated miRNAs can have profound impacts on various cancer hallmarks by repressing tumor suppressor genes. This review will discuss up-to-date knowledge of how the aberrant expression of miRNAs and their targeted genes drives ovarian cancer initiation, proliferation, survival, and resistance to chemotherapies. Understanding the mechanisms by which these miRNAs affect these hallmarks should allow the development of novel therapeutic strategies to treat these lethal malignancies.

Therapeutic effects of oligo-single-stranded DNA mimicking of hsa-miR-15a-5p on multiple myeloma

Despite the fact that a few novel agents improve the outcome of patients, MM remains incurable. Hence, developing a novel treatment strategy may prove to be promising for the clinical management of MM. Noncoding small RNAs, a cluster of RNAs that do not encode functional proteins, have been underlined that play a pivotal role in the pathogenesis of MM. Our previous study indicated that miR-15a acted as a tumor suppressor, which inhibited the cell proliferation and promoted the apoptosis of MM cells. The level of miR-15a was downregulated in MM cells and correlated with inferior outcome of MM patients. In the present study, we first developed an oligo-single-stranded DNA mimicking the sequence of hsa-miR-15a-5p (OMM-15a) and modified with locked nucleic acid (LNA-15a) to evaluate its anti-MM effects. Our results indicated that the LNA-15a presented an exciting anti-MM effect that showed notable cell growth suppression and apoptosis promotion in MM and other cancer cell lines through downregulating the expression level of target genes BCL-2, VEGF-A, and PHF19. Moreover, LNA-15a treatment significantly improved the anti-MM activity of bortezomib with the synergism effect in OCI-My5 MM cells. In our in vivo study, LNA-15a treatment significantly suppressed the tumor growth, and prolonged the survival of mice compared with the control group. However, our results indicated that the native form of oligo-single-stranded DNA mimic of hsa-miR-15a-5p (OMM-15a) without any modification had no effective inhibition on cell growth, even after increasing the dosage of OMM-15a in the treatment. Altogether, our finding provides the preclinical rationale to support the oligo-single-stranded DNA mimic of hsa-miR-15a with LNA modification, which is a promising tool for the therapy of both MM and other tumors with miR-15a downregulation.

KRCC1: A potential therapeutic target in ovarian cancer

Using a systems biology approach to prioritize potential points of intervention in ovarian cancer, we identified the lysine rich coiled-coil 1 (KRCC1), as a potential target. High-grade serous ovarian cancer patient tumors and cells express significantly higher levels of KRCC1 which correlates with poor overall survival and chemoresistance. We demonstrate that KRCC1 is predominantly present in the chromatin-bound nuclear fraction, interacts with HDAC1, HDAC2, and with the serine-threonine phosphatase PP1CC. Silencing KRCC1 inhibits cellular plasticity, invasive properties, and potentiates apoptosis resulting in reduced tumor growth. These phenotypes are associated with increased acetylation of histones and with increased phosphorylation of H2AX and CHK1, suggesting the modulation of transcription and DNA damage that may be mediated by the action of HDAC and PP1CC, respectively. Hence, we address an urgent need to develop new targets in cancer.

The Role of Epithelial-to-Mesenchymal Plasticity in Ovarian Cancer Progression and Therapy Resistance

Ovarian cancer is the most lethal of all gynecologic malignancies and the eighth leading cause of cancer-related deaths among women worldwide. The main reasons for this poor prognosis are late diagnosis; when the disease is already in an advanced stage, and the frequent development of resistance to current chemotherapeutic regimens. Growing evidence demonstrates that apart from its role in ovarian cancer progression, epithelial-to-mesenchymal transition (EMT) can promote chemotherapy resistance. In this review, we will highlight the contribution of EMT to the distinct steps of ovarian cancer progression. In addition, we will review the different types of ovarian cancer resistance to therapy with particular attention to EMT-mediated mechanisms such as cell fate transitions, enhancement of cancer cell survival, and upregulation of genes related to drug resistance. Preclinical studies of anti-EMT therapies have yielded promising results. However, before anti-EMT therapies can be effectively implemented in clinical trials, more research is needed to elucidate the mechanisms leading to EMT-induced therapy resistance.

Non-coding RNAs derailed: The many influences on the fatty acid reprogramming of cancer

Non-coding RNAs (NcRNAs), a family of functional RNA molecules that cannot translate into proteins but control specific gene expression programs, have been shown to be implicated in various biological processes, including fatty acid metabolism. Fast-growing tumor cells rewire their fatty acid metabolic circuitry in order to meet the needs of energy storage, membrane proliferation, and the generation of signaling molecules, which is achieved by regulating a variety of key enzymes along with related signaling pathways in fatty acid metabolism. This review presents an update of our knowledge about the regulatory network of ncRNAs-specifically, microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs)-in this metabolic shift and discusses the possibility of ncRNA-based therapeutics being applied to the restoration of cancer-related fatty acid metabolism.

Translational Multi-Disciplinary Approach for the Drug and Gene Delivery Systems for Cancer Treatment

Over the last several decades, nanoparticulate delivery systems have emerged as advanced drug and gene delivery tools for cancer therapy. However, their translation into clinical use still poses major challenges. Even though many innovative nanoparticulate approaches have shown very positive results both in vitro and in vivo, few of them have found a place in clinical practice. Possible factors responsible for the existing gap in the translation of nanomedicine to clinical practice may include oversimplification of enhanced permeability and retention effect, lack of correlation between the in vivo animal data vs their translation in human, and challenging multiple biological steps experienced during systemic delivery of nanomedicine. Understanding these challenges and coming up with solutions to overcome them is an important step in effective translation of nanomedicine into clinical practice. This review focuses on advancements in the field of nanomedicine used for anti-cancer therapy, including passive targeting, active targeting, and stimuli-controlled delivery. The review further reveals some of the challenges that are currently faced by pharmaceutical scientists in translation of nanomedicine; these include lack of adequate models for preclinical testing that can predict efficacy in humans, absence of appropriate regulatory guidelines for their approval processes, and difficulty in scale-up of the manufacturing of nanodrug delivery systems. A better understanding of these challenges will help us in filling the gap between the bench and bedside in cancer therapy.

AngiomiRs: MicroRNAs driving angiogenesis in cancer (Review)

Angiogenesis is an important hallmark of cancer serving a key role in tumor growth and metastasis. Therefore, tumor angiogenesis has become an attractive target for development of novel drug therapies. An increased amount of anti‑angiogenic compounds is currently in preclinical and clinical development for personalized therapies. However, resistance to current angiogenesis inhibitors is emerging, indicating that there is a need to identify novel anti‑angiogenic agents. In the last decade, the field of microRNA biology has exploded revealing unsuspected functions in tumor angiogenesis. These small non‑coding RNAs, which have been dubbed as angiomiRs, may target regulatory molecules driving angiogenesis, such as cytokines, metalloproteinases and growth factors, including vascular endothelial growth factor, platelet‑derived growth factor, fibroblast growth factor, epidermal growth factor, hypoxia inducible factor‑1, as well as mitogen‑activated protein kinase, phosphoinositide 3‑kinase and transforming growth factor signaling pathways. The present review discusses the current progress towards understanding the functions of miRNAs in tumor angiogenesis regulation in diverse types of human cancer. Furthermore, the potential clinical application of angiomiRs towards anti‑angiogenic tumor therapy was explored.

MircroRNA-139 sensitizes ovarian cancer cell to cisplatin-based chemotherapy through regulation of ATP7A/B

PURPOSE

Ovarian cancer remains a most malignant female cancer nowadays. The acquisition of chemoresistance to common-used cisplatin-based chemotherapy results in a decreased overall patient survival. The present study is aimed to investigate the role and mechanism by which miR-139/ ATPases7A/B axis modulates the chemoresistance of ovarian cancer to cisplatin-based chemotherapy.

METHODS

The expression of miR-139 in cisplatin-sensitive (n = 23) and cisplatin-resistant (n = 14) ovarian cancer tissues and cell lines (CAOV-3 and SNU119) was determined using real-time PCR assays; its effect on ovarian cancer cell chemoresistance to different concentrations of cisplatin was then assessed by measuring the cell viability using MTT assays. Next, miR-139 binding to the 3'UTR of ATP7A/B was confirmed using luciferase reporter gene assays. Finally, the combined effect of miR-139 and ATP7A/B on the chemoresistance of ovarian cancer cell was assessed.

RESULTS

miR-139 expression was down-regulated in cisplatin-resistant ovarian cancer tissues (**P < 0.01) and reduced by cisplatin treatment in ovarian cell lines (*P < 0.05, **P < 0.01); miR-139 could enhance cisplatin-induced suppression on ovarian cancer cell viability, shown as reduced lC50 values; ATP7A and ATP7B protein levesincreased approximately 2 ~ fold-changein cisplatin-resistant cell lines. MiR-139 directly bound to the 3'UTR of ATP7A/B, respectively; miR-139 inhibition increased lC50 values whereas ATP7A/B knockdown reduced lC50 values of CAOV-3 and SNU119 cell lines under cisplatin treatment; the effect of miR-139 inhibition could be partially attenuated by ATP7A/B knockdown.

CONCLUSIONS

MiR-139/ATP7A/B axis can be a reliable biomarker for ovarian cancer diagnosis, and may affect the chemoresistance of ovarian cancer to cisplatin-based chemotherapy; rescuing miR-139 expression thus to inhibit ATP7A/B might contribute to dealing with the chemoresistance of ovarian cancer.

Ovarian Cancers: Genetic Abnormalities, Tumor Heterogeneity and Progression, Clonal Evolution and Cancer Stem Cells

Four main histological subtypes of ovarian cancer exist: serous (the most frequent), endometrioid, mucinous and clear cell; in each subtype, low and high grade. The large majority of ovarian cancers are diagnosed as high-grade serous ovarian cancers (HGS-OvCas). TP53 is the most frequently mutated gene in HGS-OvCas; about 50% of these tumors displayed defective homologous recombination due to germline and somatic BRCA mutations, epigenetic inactivation of BRCA and abnormalities of DNA repair genes; somatic copy number alterations are frequent in these tumors and some of them are associated with prognosis; defective NOTCH, RAS/MEK, PI3K and FOXM1 pathway signaling is frequent. Other histological subtypes were characterized by a different mutational spectrum: LGS-OvCas have increased frequency of BRAF and RAS mutations; mucinous cancers have mutation in ARID1A, PIK3CA, PTEN, CTNNB1 and RAS. Intensive research was focused to characterize ovarian cancer stem cells, based on positivity for some markers, including CD133, CD44, CD117, CD24, EpCAM, LY6A, ALDH1. Ovarian cancer cells have an intrinsic plasticity, thus explaining that in a single tumor more than one cell subpopulation, may exhibit tumor-initiating capacity. The improvements in our understanding of the molecular and cellular basis of ovarian cancers should lead to more efficacious treatments.

Unraveling the human protein atlas of metastatic melanoma in the course of ultraviolet radiation-derived photo-therapy

To explore the photo-therapeutic capacity of UV radiation in solid tumors, we herein employed an nLC-MS/MS technology to profile the proteomic landscape of irradiated WM-266-4 human metastatic-melanoma cells. Obtained data resulted in proteomic catalogues of 5982 and 7280 proteins for UVB- and UVC-radiation conditions, respectively, and indicated the ability of UVB/C-radiation forms to eliminate metastatic-melanoma cells through induction of synergistically operating programs of apoptosis and necroptosis. However, it seems that one or more WM-266-4 cell sub-populations may escape from UV-radiation's photo-damaging activity, acquiring, besides apoptosis tolerance, an EMT phenotype that likely offers them the advantage of developing resistance to certain chemotherapeutic drugs. Low levels of autophagy may also critically contribute to the selective survival and growth of UV-irradiated melanoma-cell escapers. These are the cells that must be systemically targeted with novel therapeutic schemes, like the one of UV radiation and Irinotecan herein suggested to be holding strong promise for the effective treatment of metastatic-melanoma patients. Given the dual nature of UV radiation to serve as both anti-tumorigenic and tumorigenic agent, all individuals being subjected to risk factors for melanoma development have to be appropriately informed and educated, in order to integrate the innovative PPPM concept in their healthcare-sector management.

SIGNIFICANCE

This study reports the application of nLC-MS/MS technology to deeply map the proteomic landscape of UV-irradiated human metastatic-melanoma cells. Data bioinformatics processing led to molecular-network reconstructions that unearthed the dual nature of UV radiation to serve as both anti-tumorigenic and tumorigenic factor in metastatic-melanoma cellular environments. Our UV radiation-derived "photo-proteomic" atlas may prove valuable for the identification of new biomarkers and development of novel therapies for the disease. Given that UV radiation represents a major risk factor causing melanoma, a PPPM-based life style and clinical practice must be embraced by all individuals being prone to disease's appearance and expansion.

The role of microRNAs in the pathophysiology of adrenal tumors

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression in a sequence-specific manner. Due to its association with an assortment of diseases, miRNAs have been extensively studied in the last decade. In this review, the current understanding of the role of miRNAs in the pathophysiology of adrenal tumors is discussed. The recent contributions of high-throughput miRNA profiling studies have identified miRNAs that have functional and molecular roles in adrenal tumorigenesis. With respect to the biological heterogeneity of adrenal tumors and the limitations of the current treatments, an improved understanding of miRNAs may hold potential diagnostic and therapeutic value to facilitate better clinical management.

TGF-β1 gene silencing can enhances the sensitivity of breast cancer to cisplatin partially by restraining the occurrence of EMT

Breast cancer is one of the most common gynecological malignant tumors, the main reason of treatment failure is distant metastasis and local recurrence. TGF-β1 as a versatile polypeptide molecule plays an important role in inducing EMT to promote tumor invasion and metastasis. This study aims to investigate the effect of TGF-β1 on cisplatin (DDP) inhibiting the proliferation, migration and invasion of breast cancer and its correlation with EMT. TGF-β1 siRNA were transfected into MCF-7 cells. The cell morphology, proliferation, migration and invasion ability changes were detected by inverted microscope, clone formation assay, cell adhesion assay and Transwell Chamber Invasion. The expression of E-cadherin, vimentin, α-SMA were detected by Western blot. The results showed that TGF-β1 siRNA were transfected into MCF-7 cells successfully (P<0.05). The inhibitory activity of cisplatin on cell proliferation, migration and invasion of breast cancer were significantly enhanced after TGF-β1 siRNA transfection (P<0.05). The expression of E-cadherin was up-regulated, and vimentin and α-SMA were down-regulated with TGF-β1 siRNA transfection (P<0.05). Therefore, we concluded that TGF-β1 gene silencing can enhance the sensitivity of breast cancer to cisplatin on proliferation, migration and invasion partially by restraining the occurrence of EMT.

MicroRNAs in gynecological cancers: Small molecules with big implications

Gynecological cancers (GCs) are often diagnosed at advanced stages, limiting the efficacy of available therapeutic options. Thus, there remains an urgent and unmet need for innovative research for the efficient clinical management of GC patients. Research over past several years has revealed the enormous promise of miRNAs. These small non-coding RNAs can aid in the diagnosis, prognosis and therapy of all major GCs, viz., ovarian cancers, cervical cancers and endometrial cancers. Mechanistic details of the miRNAs-mediated regulation of multiple biological functions are under constant investigation, and a number of miRNAs are now believed to influence growth, proliferation, invasion, metastasis, chemoresistance and the relapse of different GCs. Modulation of tumor microenvironment by miRNAs can possibly explain some of their reported biological effects. miRNA signatures have been proposed as biomarkers for the early detection of GCs, even the various subtypes of individual GCs. miRNA signatures are also being pursued as predictors of response to therapies. This review catalogs the knowledge gained from collective studies, so as to assess the progress made so far. It is time to ponder over the knowledge gained, so that more meaningful pre-clinical and translational studies can be designed to better realize the potential that miRNAs have to offer.

MiR-124 inhibits invasion and induces apoptosis of ovarian cancer cells by targeting programmed cell death 6

Epithelial ovarian cancer remains the most common type of malignant tumor of the female reproductive system worldwide. Routine surgery and chemotherapy are the best treatments available for patients with ovarian cancer; however, almost 40% of ovarian cancer cases are intractable, with poor 5-year survival rates. MicroRNAs (miRNA) are endogenous small non-coding RNA molecules that function in transcriptional and post-transcriptional regulation of gene expression in various cellular processes. Recent studies demonstrated that microRNA (miR)-124 was downregulated in numerous types of tumors; however, the function and mechanism underlying miR-124 in epithelial ovarian cancer remain unclear. The present study revealed that miR-124 may be significantly downregulated in epithelial ovarian cancer. Using prediction algorithms and luciferase reporter gene assays, the present study identified and confirmed programmed cell death 6 (PDCD6) as a novel, direct target of miR-124. Overexpression of miR-124 suppressed PDCD6 expression, inhibited cell proliferation, migration and invasion, and induced apoptosis in SKOV3 and OCVAR3 cells in vitro. In the present study, overexpression of PDCD6 in epithelial ovarian cancer cells co-transfected with miR-124 effectively reversed the miR-124-induced apoptosis. Therefore, the results of the present study suggested that miR-124 is a tumor suppressor miRNA and a potential target for future treatment of ovarian malignant neoplasms.

Multiomics Analysis of Tumor Microenvironment Reveals Gata2 and miRNA-124-3p as Potential Novel Biomarkers in Ovarian Cancer

Ovarian cancer is a common and, yet, one of the most deadly human cancers due to its insidious onset and the current lack of robust early diagnostic tests. Tumors are complex tissues comprised of not only malignant cells but also genetically stable stromal cells. Understanding the molecular mechanisms behind epithelial-stromal crosstalk in ovarian cancer is a great challenge in particular. In the present study, we performed comparative analyses of transcriptome data from laser microdissected epithelial, stromal, and ovarian tumor tissues, and identified common and tissue-specific reporter biomolecules-genes, receptors, membrane proteins, transcription factors (TFs), microRNAs (miRNAs), and metabolites-by integration of transcriptome data with genome-scale biomolecular networks. Tissue-specific response maps included common differentially expressed genes (DEGs) and reporter biomolecules were reconstructed and topological analyses were performed. We found that CDK2, EP300, and SRC as receptor-related functions or membrane proteins; Ets1, Ar, Gata2, and Foxp3 as TFs; and miR-16-5p and miR-124-3p as putative biomarkers and warrant further validation research. In addition, we report in this study that Gata2 and miR-124-3p are potential novel reporter biomolecules for ovarian cancer. The study of tissue-specific reporter biomolecules in epithelial cells, stroma, and tumor tissues as exemplified in the present study offers promise in biomarker discovery and diagnostics innovation for common complex human diseases such as ovarian cancer.

miRNAs and ovarian cancer: An overview

Ovarian cancer (OC) is the sixth most common cancer in women globally. However, even with the advances in detection and therapeutics it still represents the most dangerous gynecologic malignancy in women of the industrialized countries. The discovery of micro-RNAs (miRNA), a small noncoding RNA molecule targeting multiple mRNAs and regulation of gene expression by triggering translation repression and/or RNA degradation, has revealed the existence of a new array for regulation of genes involved in cancer. This review summarizes the current knowledge regarding the role of miRNAs expression in OC. It also provides information about potential clinical relevance of circulating miRNAs for OC diagnosis, prognosis, and therapeutics. The identification of functional targets for miRNAs represents a major obstacle in our understanding of microRNA function in OC, but significant progress is being made. The better understanding of the role of microRNA expression in ovarian cancer may provide new array for the detection, diagnosis, and therapy of the OC.

MicroRNA‑139 suppressed tumor cell proliferation, migration and invasion by directly targeting HDGF in epithelial ovarian cancer

The current study investigated the expression and functional roles of microRNA‑139 (miR‑139) on human epithelial ovarian cancer (EOC). Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was performed to measure miR‑139 expression in EOC tissues and cell lines. The effects of miR‑139 on EOC cell proliferation, migration and invasion were assessed using MTT, cell migration and invasion assays, respectively. Subsequently, the molecular mechanism underlying the tumor suppressive roles of miR‑139 on EOC was determined by bioinformatics analysis, RT‑qPCR, western blotting and the luciferase reporter assay. According to the results, it was identified that miR‑139 was significantly downregulated in EOC tissues and cell lines. In addition, restoration of miR‑139 suppressed tumor cell proliferation, migration and invasion in EOC. Furthermore, hepatoma‑derived growth factor (HDGF) was identified as a target of miR‑139 in EOC. Upregulation of HDGF could rescue the inhibitory effects exerted by miR‑139 overexpression on EOC cell proliferation, migration and invasion. Collectively, the results indicated that miR‑139 was downregulated in EOC, and acted as a tumor suppressor by directly targeting HDGF. To the best of our knowledge, this was the first study to identify that miR‑139 contributes to the growth and metastasis of EOC.

MiR-646 inhibited cell proliferation and EMT-induced metastasis by targeting FOXK1 in gastric cancer

Background:

MiR-646 has been reported to be aberrantly expressed in human cancers. However, the underlying molecular mechanisms of action of miR-646 in gastric cancer (GC) have not yet been investigated.

Methods:

In vitro function of miR-646 in GC was evaluated using EdU assay, plate colony formation assay, and matrigel invasion assay. Real-time PCR or western blotting was performed to detect miR-646 and FOXK1 expressions. In vivo tumour growth and metastasis were conducted in nude mice.

Results:

MiR-646 expression was downregulated in GC tissues compared with adjacent normal tissues. Low miR-646 expression is associated with malignant progression. Transient transfection of GC cells with miR-646 inhibited their growth and migration. Moreover, miR-646 influenced the expression of epithelial–mesenchymal transition (EMT)-associated proteins. TGF-β1 treatment significantly suppressed the expression of miR-646 and overexpression of this microRNA counteracted the influence of the TGF-β1-induced EMT phenotype. In terms of the underlying mechanism, miR-646 directly targeted FOXK1. In vivo, it inhibited the FOXK1-mediated proliferation and EMT-induced metastasis. Consistently, inverse correlations were also observed between the expression of miR-646 and FOXK1 in human GC tissue samples. Furthermore, miR-646 regulated Akt/mTOR signalling after FOXK1.

Conclusions:

miR-646 inhibited GC cell proliferation and the EMT progression in GC cells by targeting FOXK1.

Resistance to cancer chemotherapeutic drugs is determined by pivotal microRNA regulators

Chemo-resistance, which is the main obstacle in cancer therapy, is caused by the onset of drug-resistant cells in the heterogeneous cell population in cancer tissues. MicroRNAs regulate gene expression at the post-transcriptional level, and they are involved in many different biological processes, including cell proliferation, differentiation, metabolism, stress response, and apoptosis. The aberrant expression of microRNAs plays a major pathogenic role from the early stages of the carcinogenesis process. Recently, microRNAs have been reported to play an important role in inducing resistance to anti-cancer drugs. Specific microRNA alterations occur selectively in cancer cells, rendering these cells resistant to various chemotherapeutic agents. For example, resistance to 5-fluorouracil is mediated by alterations in miR-21, miR-27a/b, and miR-155; the sensitivity to Docetaxel is influenced by miR-98, miR-192, miR-194, miR-200b, miR-212, and miR-424; and the resistance to Cisplatin is mediated by miR-let-7, miR-15, miR-16 miR-21 and miR-214. Chemo-resistant cancer cells are characterized by altered functions in enzymes that are involved in microRNA maturation, primarily including Dicer, as demonstrated in ovarian cancer, oral squamous cell carcinoma, breast cancer and cervical cancer. Based on the evidence reviewed in this paper, various strategies have been developed to artificially re-establish microRNA expression in resistant cells, thus restoring chemo-sensitivity. These strategies employ synthetic analogs, anti-microRNA oligonucleotides, locked nucleic acid, microRNA sponges, drugs that inhibit DNA methylation or histone deacetylation, and the introduction of microRNA mimics. The ability to modulate microRNA expression is a promising strategy for overcoming the problem of drug resistance in cancer treatment.