miR-125b confers resistance of ovarian cancer cells to cisplatin by targeting pro-apoptotic Bcl-2 antagonist killer 1

Mechanisms of apoptosis-related non-coding RNAs in ovarian cancer: a narrative review

Ovarian cancer remains a major challenge in oncology due to its complex biology and late-stage diagnosis. Recent advances in molecular biology have highlighted the crucial role of non-coding RNAs (ncRNAs) in regulating apoptosis and cancer progression. NcRNAs, including microRNAs, long non-coding RNAs, and circular RNAs, have emerged as significant players in the molecular networks governing ovarian cancer. Despite these insights, the precise mechanisms by which ncRNAs influence ovarian cancer pathology are not fully understood. This complexity, combined with the heterogeneity of the disease and the development of treatment resistance, poses substantial obstacles to effective therapeutic development. Additionally, the lack of reliable early detection methods further complicates treatment strategies. This manuscript reviews the current state of research on ncRNAs in ovarian cancer, discusses the challenges in translating these findings into clinical applications, and outlines potential future directions. Emphasis is placed on the need for integrated approaches to unravel the intricate roles of ncRNAs, improve early detection, and develop personalized treatment strategies to address the diverse and evolving nature of ovarian cancer. While these findings provide valuable insights, it is crucial to recognize that many results are based on preclinical studies and require further validation to establish their clinical applicability.

Therapeutic Chemoresistance in Ovarian Cancer: Emerging Hallmarks, Signaling Mechanisms and Alternative Pathways

Ovarian cancer is the fifth leading cause of mortality and the most lethal gynecologic malignancy among females. It may arise from atypical borderline tumors (Type I) or serous tubal intraepithelial carcinoma (Type II). The diagnosis of cancer at its early stages is difficult because of non-specific symptoms, most patients are diagnosed at the advanced stage. Several drugs and therapeutic strategies are available to treat ovarian cancer such as surgery, chemotherapy, neoadjuvant therapy, and maintenance therapy. However, the cancer cells have developed resistance to a number of available therapies causing treatment failure. This emerging chemoresistance in ovarian cancer cells is becoming an obstacle due to alterations in multiple cellular processes. These processes involve altered drug target response, drug pumps, detoxification systems, lower sensitivity to apoptosis, and altered proliferation, and are responsible for developing resistance to anticancer medicines. Various research reports have evidenced that these altered processes might play a role in the emergence of resistance. This review addresses the recent advances in understanding the underlying mechanisms of ovarian cancer resistance and covers sophisticated alternative pathways to overcome these resistance mechanisms in patients.

Evolving landscape of detection and targeting miRNA/epigenetics for therapeutic strategies in ovarian cancer

Ovarian cancer (OC) accounts for the highest mortality rates among all gynecologic malignancies. The high mortality of OC is often associated with delayed detection, prolonged latency, enhanced metastatic potential, acquired drug resistance, and frequent recurrence. This review comprehensively explores key aspects of OC, including cancer diagnosis, mechanisms of disease resistance, and the pivotal role of epigenetic regulation, particularly by microRNAs (miRs) in cancer progression. We highlight the intricate regulatory mechanisms governing miR expression within the context of OC and the current status of epigenetic advancement in the therapeutic development and clinical trial progression. Through network analysis we elucidate the regulatory interactions between dysregulated miRs in OC and their targets which are involved in different signaling pathways. By exploring these interconnected facets and critical analysis, we endeavor to provide a nuanced understanding of the molecular dynamics underlying OC, its detection and shedding light on potential avenues for miRs and epigenetics-based therapeutic intervention and management strategies.

Novel players in the development of chemoresistance in ovarian cancer: ovarian cancer stem cells, non-coding RNA and nuclear receptors

Ovarian cancer (OC) ranks as the fifth leading factor for female mortality globally, with a substantial burden of new cases and mortality recorded annually. Survival rates vary significantly based on the stage of diagnosis, with advanced stages posing significant challenges to treatment. OC is primarily categorized as epithelial, constituting approximately 90% of cases, and correct staging is essential for tailored treatment. The debulking followed by chemotherapy is the prevailing treatment, involving platinum-based drugs in combination with taxanes. However, the efficacy of chemotherapy is hindered by the development of chemoresistance, both acquired during treatment (acquired chemoresistance) and intrinsic to the patient (intrinsic chemoresistance). The emergence of chemoresistance leads to increased mortality rates, with many advanced patients experiencing disease relapse shortly after initial treatment. This review delves into the multifactorial nature of chemoresistance in OC, addressing mechanisms involving transport systems, apoptosis, DNA repair, and ovarian cancer stem cells (OCSCs). While previous research has identified genes associated with these mechanisms, the regulatory roles of non-coding RNA (ncRNA) and nuclear receptors in modulating gene expression to confer chemoresistance have remained poorly understood and underexplored. This comprehensive review aims to shed light on the genes linked to different chemoresistance mechanisms in OC and their intricate regulation by ncRNA and nuclear receptors. Specifically, we examine how these molecular players influence the chemoresistance mechanism. By exploring the interplay between these factors and gene expression regulation, this review seeks to provide a comprehensive mechanism driving chemoresistance in OC.

miR-125b-5p, miR-155-3p, and miR-214-5p and Target E2F2 Gene in Oral Squamous Cell Carcinoma

It is known that E2F2 (E2F transcription factor 2) plays an important role as controller in the cell cycle. This study aimed to analyse the expression of the E2F2 gene and E2F2 protein and demonstrate E2F2 target microRNAs (miRNAs) candidates (miR-125b-5p, miR-155-3p, and miR-214-5p) in oral squamous cell carcinoma tumour and margin samples. The study group consisted 50 patients. The E2F2 gene and miRNAs expression levels were assessed by qPCR, while the E2F2 protein was assessed by ELISA. When analysing the effect of miRNAs expression on E2F2 gene expression and E2F2 protein level, we observed no statistically significant correlations. miR-125b-5p was downregulated, while miR-155-3p, and miR-214-5p were upregulated in tumour samples compared to margin. We observed a difference between the miR-125b-5p expression level in smokers and non-smokers in margin samples. Furthermore, HPV-positive individuals had a significantly higher miR-125b-5p and miR-214-5p expression level compared to HPV-negative patients in tumour samples. The study result showed that the E2F2 gene is not the target for analysed miRNAs in OSCC. Moreover, miR-155-3p and miR-125b-5p could play roles in the pathogenesis of OSCC. A differential expression of the analysed miRNAs was observed in response to tobacco smoke and HPV status.

CRISPR technology: A versatile tool to model, screen, and reverse drug resistance in cancer

BACKGROUND

Drug resistance is a serious challenge in cancer treatment that can render chemotherapy a failure. Understanding the mechanisms behind drug resistance and developing novel therapeutic approaches are cardinal steps in overcoming this issue. Clustered regularly interspaced short palindrome repeats (CRISPR) gene-editing technology has proven to be a useful tool to study cancer drug resistance mechanisms and target the responsible genes. In this review, we evaluated original research studies that used the CRISPR tool in three areas related to drug resistance, namely screening resistance-related genes, generating modified models of resistant cells and animals, and removing resistance by genetic manipulation. We reported the targeted genes, study models, and drug groups in these studies. In addition to discussing different applications of CRISPR technology in cancer drug resistance, we analyzed drug resistance mechanisms and provided examples of CRISPR's role in studying them. Although CRISPR is a powerful tool for examining drug resistance and sensitizing resistant cells to chemotherapy, more studies are required to overcome its disadvantages, such as off-target effects, immunotoxicity, and inefficient delivery of CRISPR/cas9 into the cells.

A comprehensive survey into the role of microRNAs in ovarian cancer chemoresistance; an updated overview

Ovarian cancer (OC), a frequent malignant tumor that affects women, is one of the leading causes of cancer-related death in this group of individuals. For the treatment of ovarian cancer, systemic chemotherapy with platinum-based drugs or taxanes is the first-line option. However, drug resistance developed over time during chemotherapy medications worsens the situation. Since uncertainty exists for the mechanism of chemotherapy resistance in ovarian cancer, there is a need to investigate and overcome this problem. miRNAs are engaged in various signaling pathways that contribute to the chemotherapeutic resistance of ovarian cancer. In the current study, we have tried to shed light on the mechanisms by which microRNAs contribute to the drug resistance of ovarian cancer and the use of some microRNAs to combat this chemoresistance, leading to the worse outcome of ovarian cancer patients treated with systemic chemotherapeutics.

Micro-RNAs in Response to Active Forms of Vitamin D3 in Human Leukemia and Lymphoma Cells

Non-coding micro-RNA (miRNAs) regulate the protein expression responsible for cell growth and proliferation. miRNAs also play a role in a cancer cells’ response to drug treatment. Knowing that leukemia and lymphoma cells show different responses to active forms of vitamin D₃, we decided to investigate the role of selected miRNA molecules and regulated proteins, analyzing if there is a correlation between the selected miRNAs and regulated proteins in response to two active forms of vitamin D₃, calcitriol and tacalcitol. A total of nine human cell lines were analyzed: five leukemias: MV-4-1, Thp-1, HL-60, K562, and KG-1; and four lymphomas: Raji, Daudi, Jurkat, and U2932. We selected five miRNA molecules—miR-27b, miR-32, miR-125b, miR-181a, and miR-181b—and the proteins regulated by these molecules, namely, CYP24A1, Bak1, Bim, p21, p27, p53, and NF-kB. The results showed that the level of selected miRNAs correlates with the level of proteins, especially p27, Bak1, NFκB, and CYP24A1, and miR-27b and miR-125b could be responsible for the anticancer activity of active forms of vitamin D₃ in human leukemia and lymphoma.

The Role of MiRNA in Cancer: Pathogenesis, Diagnosis, and Treatment

Cancer is also determined by the alterations of oncogenes and tumor suppressor genes. These gene expressions can be regulated by microRNAs (miRNA). At this point, researchers focus on addressing two main questions: "How are oncogenes and/or tumor suppressor genes regulated by miRNAs?" and "Which other mechanisms in cancer cells are regulated by miRNAs?" In this work we focus on gathering the publications answering these questions. The expression of miRNAs is affected by amplification, deletion or mutation. These processes are controlled by oncogenes and tumor suppressor genes, which regulate different mechanisms of cancer initiation and progression including cell proliferation, cell growth, apoptosis, DNA repair, invasion, angiogenesis, metastasis, drug resistance, metabolic regulation, and immune response regulation in cancer cells. In addition, profiling of miRNA is an important step in developing a new therapeutic approach for cancer.

Investigation of the efficacy of paclitaxel on some miRNAs profiles in breast cancer stem cells

Understanding of the functions of microRNAs in breast cancer and breast cancer stem cells have been a hope for the development of new molecular targeted therapies. Here, it is aimed to investigate the differences in the expression levels of let-7a, miR-10b, miR-21, miR-125b, miR-145, miR-155, miR-200c, miR-221, miR-222 and miR-335, which associated with gene and proteins in MCF-7 (parental) and MCF-7s (Mammosphere/stem cell-enriched population/CD44+/CD24-cells) cells treated with paclitaxel. MCF-7s were obtained from parental MCF-7 cells. Cytotoxic activity of paclitaxel was determined by ATP assay. Total RNA isolation and cDNA conversion were performed from the samples. Changes in expression levels of miRNAs were examined by RT-qPCR. Identified target genes and proteins of miRNAs were analyzed with RT-qPCR and western blot analysis, respectively. miR-125b was significantly expressed (2.0946-fold; p = 0.021) in MCF-7s cells compared to control after treatment with paclitaxel. Downregulation of SMO, STAT3, NANOG, OCT4, SOX2, ERBB2 and ERBB3 and upregulation of TP53 genes were significant after 48 h treatment in MCF-7s cells. Protein expressions of SOX2, OCT4, SMAD4, SOX2 and OCT4 also decreased. Paclitaxel induces miR-125b expression in MCF-7s cells. Upregulation of miR-125b may be used as a biomarker for the prediction of response to paclitaxel treatment in breast cancer.

MicroRNAs as the critical regulators of Cisplatin resistance in ovarian cancer cells

BACKGROUND

Ovarian cancer (OC) is one of the leading causes of cancer related deaths among women. Due to the asymptomatic tumor progression and lack of efficient screening methods, majority of OC patients are diagnosed in advanced tumor stages. A combination of surgical resection and platinum based-therapy is the common treatment option for advanced OC patients. However, tumor relapse is observed in about 70% of cases due to the treatment failure. Cisplatin is widely used as an efficient first-line treatment option for OC; however cisplatin resistance is observed in a noticeable ratio of cases. Regarding, the severe cisplatin side effects, it is required to clarify the molecular biology of cisplatin resistance to improve the clinical outcomes of OC patients. Cisplatin resistance in OC is associated with abnormal drug transportation, increased detoxification, abnormal apoptosis, and abnormal DNA repair ability. MicroRNAs (miRNAs) are critical factors involved in cell proliferation, apoptosis, and chemo resistance. MiRNAs as non-invasive and more stable factors compared with mRNAs, can be introduced as efficient markers of cisplatin response in OC patients.

MAIN BODY

In present review, we have summarized all of the miRNAs that have been associated with cisplatin resistance in OC. We also categorized the miRNAs based on their targets to clarify their probable molecular mechanisms during cisplatin resistance in ovarian tumor cells.

CONCLUSIONS

It was observed that miRNAs mainly exert their role in cisplatin response through regulation of apoptosis, signaling pathways, and transcription factors in OC cells. This review highlighted the miRNAs as important regulators of cisplatin response in ovarian tumor cells. Moreover, present review paves the way of suggesting a non-invasive panel of prediction markers for cisplatin response among OC patients.

The Non-Coding RNAs Inducing Drug Resistance in Ovarian Cancer: A New Perspective for Understanding Drug Resistance

Ovarian cancer, a common malignant tumor, is one of the primary causes of cancer-related deaths in women. Systemic chemotherapy with platinum-based compounds or taxanes is the first-line treatment for ovarian cancer. However, resistance to these chemotherapeutic drugs worsens the prognosis. The underlying mechanism of chemotherapeutic resistance in ovarian cancer remains unclear. Non-coding RNAs, including long non-coding RNAs, microRNAs, and circular RNAs, have been implicated in the development of drug resistance. Abnormally expressed non-coding RNAs can promote ovarian cancer resistance by inducing apoptosis inhibition, protective autophagy, abnormal tumor cell proliferation, epithelial-mesenchymal transition, abnormal glycolysis, drug efflux, and cancer cell stemness. This review summarizes the role of non-coding RNAs in the development of chemotherapeutic resistance in ovarian cancer, including their mechanisms, targets, and potential signaling pathways. This will facilitate the development of novel chemotherapeutic agents that can target these non-coding RNAs and improve ovarian cancer treatment.

The Ratio of Toxic-to-Nontoxic miRNAs Predicts Platinum Sensitivity in Ovarian Cancer

Ovarian cancer remains one of the deadliest gynecologic malignancies affecting women, and development of resistance to platinum remains a major barrier to achieving a cure. Multiple mechanisms have been identified to confer platinum resistance. Numerous miRNAs have been linked to platinum sensitivity and resistance in ovarian cancer. miRNA activity occurs mainly when the guide strand of the miRNA, with its seed sequence at position 2-7/8, is loaded into the RNA-induced silencing complex (RISC) and targets complementary short seed matches in the 3' untranslated region of mRNAs. Toxic 6mer seeds, which target genes critical for cancer cell survival, have been found in tumor-suppressive miRNAs. Many siRNAs and short hairpin RNAs (shRNA) can also kill cancer cells via toxic seeds, the most toxic of which carry G-rich 6mer seed sequences. We showed here that treatment of ovarian cancer cells with platinum led to increased RISC-bound miRNAs carrying toxic 6mer seeds and decreased miRNAs with nontoxic seeds. Platinum-tolerant cells did not exhibit this toxicity shift but retained sensitivity to cell death mediated by siRNAs carrying toxic 6mer seeds. Analysis of RISC-bound miRNAs in tumors from patients with ovarian cancer revealed that the ratio between miRNAs with toxic versus nontoxic seeds was predictive of treatment outcome. Application of the 6mer seed toxicity concept to cancer relevant miRNAs provides a new framework for understanding and predicting cancer therapy responses. SIGNIFICANCE: These findings demonstrate that the balance of miRNAs that carry toxic and nontoxic 6mer seeds contributes to platinum resistance in ovarian cancer.

Liquid biopsy for therapy monitoring in early-stage non-small cell lung cancer

Liquid biopsy is now considered a valuable diagnostic tool for advanced metastatic non-small cell lung cancer (NSCLC). In NSCLC, circulating tumor DNA (ctDNA) analysis has been shown to increase the chances of identifying the presence of targetable mutations and has been adopted by many clinicians owing to its low risk. Serial monitoring of ctDNA may also help assess the treatment response or for monitoring relapse. As the presence of detectable plasma ctDNA post-surgery likely indicates residual tumor burden, studies have been performed to quantify plasma ctDNA to assess minimal residual disease (MRD) in early-stage resected NSCLC. Most data on utilizing liquid biopsy for monitoring MRD in early-stage NSCLC are from small-scale studies using ctDNA. Here, we review the recent research on liquid biopsy in NSCLC, not limited to ctDNA, and focus on novel methods such as micro RNAs (miRNA) and long non-coding (lncRNA).

Double Insurance for OC: miRNA-Mediated Platinum Resistance and Immune Escape

Ovarian cancer (OC) is still the leading cause of death among all gynecological malignancies, despite the recent progress in cancer therapy. Immune escape and drug resistance, especially platinum-based chemotherapy, are significant factors causing disease progression, recurrence and poor prognosis in OC patients. MicroRNAs(miRNAs) are small noncoding RNAs, regulating gene expression at the transcriptional level. Accumulating evidence have indicated their crucial roles in platinum resistance. Importantly, they also act as mediators of tumor immune escape/evasion. In this review, we summarize the recent study of miRNAs involved in platinum resistance of OC and systematically analyses miRNAs involved in the regulation of OC immune escape. Further understanding of miRNAs roles and their possible mechanisms in platinum resistance and tumor escape may open new avenues for improving OC therapy.

Quercetin and MicroRNA Interplay in Apoptosis Regulation in Ovarian Cancer

The multifaceted nature of ovarian cancer has severely hampered the development of effective therapeutics over the years. The complicate nature of ovarian cancer makes it therapeutically challenging, therefore, there has been a renewed interest in phytochemistry. Phytochemicals have emerged as a potential therapeutic option due to less side effects. Moreover, the signaling inhibition properties have also been studied extensively in recent times. A growing number of data obtained via high-throughput technologies has started to delineate the complex oncogenic signaling networks, thus broadening the therapeutic opportunities. Within the network, microRNAs (miRNAs) have been shown to play a versatile role in the regulation of cancer. Quercetin has been in the spotlight over the years because of its high pharmacological values and substantial evidence has demonstrated its anti-proliferative effect against various types of cancers. Despite the versatility of quercetin, little is known about its anti-proliferative potential towards ovarian cancer. This review sheds some light on quercetin as an alternative therapeutic approach to cancer. Furthermore, we also addresss the interplay between miRNAs and quercetin in the regulation of apoptosis in ovarian cancer.

The Role of Non-Coding RNAs as Prognostic Factor, Predictor of Drug Response or Resistance and Pharmacological Targets, in the Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the most common keratinocyte-derived skin cancer in the Caucasian population. Exposure to UV radiations (UVRs) represents the main risk carcinogenesis, causing a considerable accumulation of DNA damage in epidermal keratinocytes with an uncontrolled hyperproliferation and tumor development. The limited and rarely durable response of CSCC to the current therapeutic options has led researchers to look for new therapeutic strategies. Recently, the multi-omics approaches have contributed to the identification and prediction of the key role of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), circularRNAs (circRNAs) and long non-coding RNAs (lncRNAs) in the regulation of several cellular processes in different tumor types, including CSCC. ncRNAs can modulate transcriptional and post-transcriptional events by interacting either with each other or with DNA and proteins, such as transcription factors and RNA-binding proteins. In this review, the implication of ncRNAs in tumorigenesis and their potential role as diagnostic biomarkers and therapeutic targets in human CSCC are reported.

Non-coding RNAs in drug resistance of head and neck cancers: A review

Head and neck cancer (HNC), which includes epithelial malignancies of the upper aerodigestive tract (oral cavity, oropharynx, pharynx, hypopharynx, larynx, and thyroid), are slowly but consistently increasing, while the overall survival rate remains unsatisfactory. Because of the multifunctional anatomical intricacies of the head and neck, disease progression and therapy-related side effects often severely affect the patient's appearance and self-image, as well as their ability to breathe, speak, and swallow. Patients with HNC require a multidisciplinary approach involving surgery, radiation therapy, and chemotherapeutics. Chemotherapy is an important part of the comprehensive treatment of tumors, especially advanced HNC, but drug resistance is the main cause of poor clinical efficacy. The most important determinant of this phenomenon is still largely unknown. Recent studies have shown that non-coding RNAs have a crucial role in HNC drug resistance. In addition, they can serve as biomarkers in the diagnosis, treatment, and prognosis of HNCs. In this review, we summarize the relationship between non-coding RNAs and drug resistance of HNC, and discuss their potential clinical application in overcoming HNC chemoresistance.

Insights from circulating microRNAs in cardiovascular entities in turner syndrome patients

Background

Turner syndrome (TS) is a chromosomal disorder, in which a female is partially or entirely missing one of the two X chromosomes, with a prevalence of 1:2500 live female births. The present study aims to identify a circulating microRNA (miRNA) signature for TS patients with and without congenital heart disease (CHD).

Methods

Microarray platform interrogating 2549 miRNAs were used to detect the miRNA abundance levels in the blood of 33 TS patients and 14 age-matched healthy volunteer controls (HVs). The differentially abundant miRNAs between the two groups were further validated by RT-qPCR.

Results

We identified 60 differentially abundant miRNA in the blood of TS patients compared to HVs, from which, 41 and 19 miRNAs showed a higher and a lower abundance levels in TS patients compared to HVs, respectively. RT-qPCR confirmed the significantly higher abundance levels of eight miRNAs namely miR-374b-5p, miR-199a-5p, miR-340-3p, miR-125b-5p, miR-30e-3p, miR-126-3p, miR-5695, and miR-26b-5p in TS patients as compared with the HVs. The abundance level of miR-5695 was higher in TS patients displaying CHD as compared to TS patients without CHD (p = 0.0265; log2-fold change 1.99); whereas, the abundance level of miR-126-3p was lower in TS patients with congenital aortic valve disease (AVD) compared to TS patients without BAV (p = 0.0139, log2-fold change 1.52). The clinical feature statistics revealed that miR-126-3p had a significant correlation with sinotubular junction Z-score (r = 0.42; p = 0.0154).

Conclusion

The identified circulating miRNAs signature for TS patients with manifestations associated with cardiovascular diseases provide new insights into the molecular mechanism of TS that may guide the development of novel diagnostic approaches.

Regulation of Fibroblast Apoptosis and Proliferation by MicroRNA-125b in Systemic Sclerosis

OBJECTIVE

To analyze the expression, regulation, and role of microRNA-125b (miR-125b) in systemic sclerosis (SSc).

METHODS

MiR-125b expression was assessed by quantitative polymerase chain reaction (qPCR) of RNA from dermal fibroblasts and whole skin biopsy specimens from healthy controls and SSc patients. To identify downstream effectors, RNA from healthy control fibroblasts was sequenced after miR-125b knockdown and further validated using qPCR and Western blotting. Fibrosis, apoptosis, and proliferation were assessed by Caspase-Glo 3/7 assay, Western blotting, immunofluorescence staining for cleaved caspase 3, and annexin V real-time assay in dermal fibroblasts.

RESULTS

Expression of miR-125b was significantly down-regulated in SSc skin biopsy specimens by 53% (median fold change 0.47 [interquartile range 0.35-0.69]; P < 0.001) and in SSc dermal fibroblasts by 47% (median fold change 0.53 [interquartile range 0.36-0.58]; P < 0.001) compared to healthy control skin biopsy specimens and fibroblasts, respectively (n = 10 samples per group). Treatment with the histone deacetylase inhibitors trichostatin A and tubastatin A significantly decreased the expression of miR-125b in dermal fibroblasts. MiR-125b knockdown significantly reduced cell proliferation and α-smooth muscle actin (α-SMA) expression at the messenger RNA (mRNA) and protein levels. RNA-Seq identified BAK1, BMF, and BBC3 as potential targets of miR-125b. Quantitative PCR confirmed that knockdown of miR-125b up-regulated these genes (P < 0.01; n = 12). Bcl-2 homologous antagonist killer 1 showed the strongest induction confirmed at the protein level (P < 0.01; n = 10). Consequently, miR-125b knockdown increased apoptosis compared to scrambled control. Accordingly, miR-125b overexpression decreased apoptosis.

CONCLUSION

Our findings indicate that miR-125b is down-regulated in SSc skin and primary dermal fibroblasts. MiR-125b down-regulation increases apoptosis and decreases proliferation and α-SMA expression in dermal fibroblasts, indicating that its compensatory, antifibrotic mechanism may be a potential novel therapeutic option.

Circulating non-coding RNAs in recurrent and metastatic ovarian cancer

Ovarian cancer has a poor outcome because it is usually detected at advanced tumor stages, and the majority of the patients develop disease relapse as a result of chemotherapy resistance. This most lethal gynecological malignancy metastasizes within the peritoneal fluid or ascites to pelvic and distal organs. In ovarian cancer progression and metastasis, small non-coding RNAs (ncRNAs), including long noncoding RNAs and microRNAs have been recognized as important regulators. Their dysregulation modulates gene expression and cellular signal pathways and can be detected in liquid biopsies. In this review, we provide an overview on circulating plasma and serum ncRNAs participating in tumor cell migration and invasion, and contributing to recurrence and metastasis of ovarian cancer. We will also discuss the development of potential, novel therapies using ncRNAs as target molecules or tumor markers for ovarian cancer.

Dysregulation of miR-125b predicts poor response to therapy in pediatric acute lymphoblastic leukemia

BACKGROUND

Acute lymphoblastic leukemia (ALL) is the most well-known sort of leukemia in children. In spite of favorable survival rates, some patients relapse and achieve a poor outcome.

METHODS

We analyzed miR-125b and Bcl-2 expressions in pediatric patients with ALL and evaluated their clinical utility as molecular markers for the prediction of disease outcomes.

RESULTS

Downregulation of miR-125b and increased Bcl-2 expression levels in pediatric patients with ALL were associated with poor prognosis at diagnosis. At day 28 of induction, miR-125b was significantly increased, whereas Bcl-2 was downregulated. Loss of miR-125b during diagnosis and its elevation after therapy are strongly correlated with short leukemia-free survival and worse survival. Moreover, the combination of miR-125b with Bcl-2 markers can clearly enhance the prediction of the disease outcome. Finally, a univariate analysis highlighted the independent prognostic value of miR-125 in a pediatric patient with ALL.

CONCLUSIONS

miR-125b and Bcl-2 together are potent predictors for the prognosis and, therefore, can be used as therapeutic targets in childhood ALL.

miR-125b suppresses oral oncogenicity by targeting the anti-oxidative gene PRXL2A

Oral squamous cell carcinoma (OSCC) is a globally prevalent malignancy. The molecular mechanisms of this cancer are not well understood and acquire elucidation. Peroxiredoxin like 2A (PRXL2A) has been reported to be an antioxidant protein that protects cells from oxidative stress. Our previous study identified an association between PRXL2A upregulation in OSCC and a worse patient prognosis. MicroRNAs (miRNAs) are small non-coding RNAs that are involved in the modulation of biological/pathological properties. The miR-125 family of genes drive pluripotent regulation across a wide variety of cancers. In this study, we identify the oncogenic eligibility of PRXL2A and clarify miR-125b as its upstream regulator. Downregulation of miR-125b can be observed in OSCC tumors. Lower miR-125b expression in tumors results in a worse patient prognosis at the relatively early stage. Reporter assays are able to validate that PRXL2A is a direct target of miR-125b. Exogenous miR-125b expression in OSCC cells results in increased oxidative stress, increased drug sensitivity, and suppressor activity that is paralleled by the knockout of PRXL2A gene. The suppressor activity of miR-125b is able to be rescued by PRXL2A, which suggests the existence of a miR-125b-PRXL2A regulatory axis that is part of OSCC pathogenesis. Nuclear factor-erythroid 2-related factor 2 (NRF2) was found to be a downstream effector of the miR-125b-PRXL2A cascade. As a whole, this study has pinpointed novel clues demonstrating that downregulation of miR-125b suppressor underlies upregulation of PRXL2A in OSCC, and this then protects the affected tumor cells from oxidative stress.

Steroid hormone calcitriol and its analog tacalcitol inhibit miR-125b expression in a human breast cancer MCF-7 cell line

MiR-125b belongs to the class of microRNAs, which are short endogenous non-coding RNAs that negatively regulate gene expression at the post-transcriptional level. Recently, it was reported that miR-125b was found to promote migration and invasion of MCF-7 cells and was involved in chemotherapeutic resistance. Decreasing miR-125b expression would have potential therapeutic significance in preventing dissemination of breast cancer cells. The objective of this study was to evaluate miR-125b expression levels in MCF-7 cells following treatment with 1,25-dihydroxyvitamin D₃ (calcitriol) and 1,24-dihydroxyvitamin D₃ (tacalcitol), active metabolite and synthetic analog of vitamin D₃, respectively. We found that treatment with both calcitriol and tacalcitol caused a decrease in miR-125b expression. In addition, treatment with calcitriol and tacalcitol resulted in an increase in the level of pro-apoptotic BAK1 protein encoded by the target gene of miR-125b. We are discussing the putative mechanism of inhibition of the miR-125b expression by vitamin D receptor (VDR) agonists and we suggest that calcitriol and tacalcitol may be used as a miR-125b inhibitor in breast cancer cells expressing VDR.

The potential role of miRNAs and exosomes in chemotherapy in ovarian cancer

Chemoresistance is one of the major obstacles in the treatment of cancer patients. It poses a fundamental challenge to the effectiveness of chemotherapy and is often linked to relapse in patients. Chemoresistant cells can be identified in different types of cancers; however, ovarian cancer has one of the highest rates of chemoresistance-related relapse (50% of patients within 5 years). Resistance in cells can either develop through prolonged cycles of treatment or through intrinsic pathways. Mechanistically, the problem of drug resistance is complex mainly because numerous factors are involved, such as overexpression of drug efflux pumps, drug inactivation, DNA repair mechanisms and alterations to and/or mutations in the drug target. Additionally, there is strong evidence that circulating miRNAs participate in the development of chemoresistance. Recently, miRNAs have been identified in exosomes, where they are encapsulated and hence protected from degradation. These miRNAs within exosomes (exo-miRNAs) can regulate the gene expression of target cells both locally and systemically. Exo-miRNAs play an important role in disease progression and can potentially facilitate chemoresistance in cancer cells. In addition, and from a diagnostic perspective, exo-miRNAs profiles may contribute to the development of predictive models to identify responder and non-responder chemotherapy. Such model may also be used for monitoring treatment response and disease progression. Exo-miRNAs may ultimately serve as both a predictive biomarker for cancer response to therapy and as a prognostic marker for the development of chemotherapy resistance. Therefore, this review examines the potential role of exo-miRNAs in chemotherapy in ovarian cancer.

Circulating immune biomarkers as predictors of the response to pembrolizumab and weekly low dose carboplatin and paclitaxel in NSCLC and poor PS: An interim analysis

The combination of standard-dose chemotherapy and immunotherapy has been shown to be beneficial for patients with non-small cell lung cancer (NSCLC) with good performance status (PS). However, treatment options for patients with poor PS are limited. In the present study, the feasibility and immunological effects of low-dose chemotherapy with carboplatin and paclitaxel combined with immunotherapy with pembrolizumab were examined in patients with metastatic NSCLC and a poor PS. Patients with advanced NSCLC and a PS of 2 were randomized to single-agent pembrolizumab at 200 mg every 3 weeks or pembrolizumab combined with weekly carboplatin area under the curve 1 and paclitaxel 25 mg/m². Blood for circulating immune cell phenotyping, soluble program death ligand 1 (sPD-L1) and immune-modulatory microRNAs (miRNAs) was collected prior to treatment and at weeks 4 and 7. Ten patients were randomized to the combination arm and 10 to the single-agent arm. Therapy was well tolerated. Four patients discontinued carboplatin due to hypersensitivity reactions but continued pembrolizumab and paclitaxel treatments. Increases in activated CD4⁺ T cells and in immune-regulatory miRNA, and decreases in myeloid derived suppressor cells were observed in the blood of patients in the combination arm and not in the single-agent arm. Changes in circulating regulatory T cells and sPD-L1 were not observed. Seven patients in the combination arm manifested a partial response compared with only two in the single-agent arm. Weekly low-dose chemotherapy carboplatin and paclitaxel was well tolerated and immunologically active when combined with pembrolizumab in patients with advanced NSCLC and a PS of 2. This combination merits further study in this patient population.

Molecular mechanisms of drug resistance in ovarian cancer

Ovarian cancer is the most lethal malignancy among the gynecological cancers, with a 5-year survival rate, mainly due to being diagnosed at advanced stages, recurrence and resistance to the current chemotherapeutic agents. Drug resistance is a complex phenomenon and the number of known involved genes and cross-talks between signaling pathways in this process is growing rapidly. Thus, discovering and understanding the underlying molecular mechanisms involved in chemo-resistance are crucial for management of treatment and identifying novel and effective drug targets as well as drug discovery to improve therapeutic outcomes. In this review, the major and recently identified molecular mechanisms of drug resistance in ovarian cancer from relevant literature have been investigated. In the final section of the paper, new approaches for studying detailed mechanisms of chemo-resistance have been briefly discussed.

The functional mechanism of miR-125b in gastric cancer and its effect on the chemosensitivity of cisplatin

Numerous studies have shown drug resistance of gastric cancer cells could be modulated by abnormal expression of microRNAs. Cisplatin (DDP) is one of the most commonly used drugs for chemotherapy of gastric cancer. In this study, the potential function of miR-125b on DDP resistance in gastric cancer cells was investigated. Sixteen miRNAs significantly differential expressed in gastric tumor tissues and adjacent tissues were characterized and their corresponding putative target genes were also screened. MiR-125b was selected as our focus for its evident down-regulated expression among candidate genes. Real-time polymerase chain reaction assay indicated that miR-125b was significantly down-regulated in gastric cancer tissues and various cell lines. HER2 was identified as a target gene of miR-125b by dual luciferase reporter assay and Western blot. Moreover, miR-125b overexpression inhibited not only the proliferation, migration, and invasion abilities of HGC-27 and MGC-803 cells, but also in vivo tumor growth of MGC-803 cells by an intratumoral delivery approach. Notably, we observed up-regulated miR-125b contributed to the chemosensitivity of DDP in HGC-27 and MGC-803 cells at different concentrations and also possessed sensibilization for DDP at different times. MiR-125b expression was found to be related to lymph node metastasis, HER2 expression and overall survival of patients through correlation analysis. Collectively, these results indicate miR-125b may regulate DDP resistance as a promising therapeutic target for gastric cancer treatment in future.

miR-199a modulates cisplatin resistance in ovarian cancer by targeting Hif1α

Resistance to chemotherapy is a primary problem for the effective treatment of ovarian cancer. Recently, increasing evidence has demonstrated that miRNAs modulate many important molecular pathways involved in chemotherapy. Previous studies demonstrated that miR-199a affected ovarian cancer cell resistance to cisplatin (DDP). However, the role of miR-199a and its target genes in determination of ovarian cancer sensitivity to DDP remains unclear. Quantitative reverse transcription polymerase chain reaction was used to detect the expression levels of miR-199a in ovarian cancer tissues and C13* and OV2008 cell lines. After transfection of miR-199a mimic or inhibitor, flow cytometry was used to detect cell apoptosis exposed to DDP. Enzyme-linked immunosorbent assay and Western blot assay were applied to detect tumor necrosis factor-α levels and protein expression levels of Bax, Fas, Fas-associated death domain, and caspase-8. The results indicated that the expression of miR-199a was downregulated and hypoxia-inducible factor 1α (Hif1α) upregulated in the ovarian tumors compared with those in the corresponding normal tissues. Besides, the expression levels of miR-199a were significantly higher in OV2008 cells compared with those in C13* cells. Moreover, suppression of Hif1α reversed the inhibiting function of miR-199a inhibitor on DDP-induced apoptosis in the OV2008 cells. However, overexpression of both miR-199a and Hif1α reduced DDP-induced apoptosis in C13* cells. In conclusion, miR-199a may change DDP resistance in ovarian cancer by regulating Hif1α.

A carvedilol-responsive microRNA, miR-125b-5p protects the heart from acute myocardial infarction by repressing pro-apoptotic bak1 and klf13 in cardiomyocytes

BACKGROUND

Cardiac injury is accompanied by dynamic changes in the expression of microRNAs (miRs), small non-coding RNAs that post-transcriptionally regulate target genes. MiR-125b-5p is downregulated in patients with end-stage dilated and ischemic cardiomyopathy, and has been proposed as a biomarker of heart failure. We previously reported that the β-blocker carvedilol promotes cardioprotection via β-arrestin-biased agonism of β₁-adrenergic receptor while stimulating miR-125b-5p processing in the mouse heart. We hypothesize that β₁-adrenergic receptor/β-arrestin1-responsive miR-125b-5p confers the improvement of cardiac function and structure after acute myocardial infarction.

METHODS AND RESULTS

Using cultured cardiomyocyte (CM) and in vivo approaches, we show that miR-125b-5p is an ischemic stress-responsive protector against CM apoptosis. CMs lacking miR-125b-5p exhibit increased susceptibility to stress-induced apoptosis, while CMs overexpressing miR-125b-5p have increased phospho-AKT pro-survival signaling. Moreover, we demonstrate that loss-of-function of miR-125b-5p in the mouse heart causes abnormalities in cardiac structure and function after acute myocardial infarction. Mechanistically, the improvement of cardiac function and structure elicited by miR-125b-5p is in part attributed to repression of the pro-apoptotic genes Bak1 and Klf13 in CMs.

CONCLUSIONS

In conclusion, these findings reveal a pivotal role for miR-125b-5p in regulating CM survival during acute myocardial infarction.

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-125b predicts childhood acute lymphoblastic leukaemia poor response to BFM chemotherapy treatment

BACKGROUND

Despite the favourable survival rates of childhood acute lymphoblastic leukaemia (ALL), a significant number of patients present resistance to antileukaemic agents and dismal prognosis. In this study, we analysed miR-125b expression in childhood ALL and evaluated its clinical utility for patients treated with Berlin-Frankfurt-Münster (BFM) protocol.

METHODS

The study included 272 bone marrow specimens obtained on diagnosis and on BFM day 33 from 125 patients and 64 healthy children. Following extraction, RNA was polyadenylated and reverse transcribed. miR-125b levels were quantified by quantitative PCR. Cytogenetics, immunohistotype and MRD were analysed according to international guidelines.

RESULTS

Downregulated miR-125b levels were detected in childhood ALL patients and correlated with adverse prognosis. Following BFM induction, miR-125b levels were significantly increased, however, elevated day 33/diagnosis miR-125b ratio was associated with unfavourable disease features. Loss of miR-125b during diagnosis and higher day 33/diagnosis ratio were correlated with stronger risk for disease short-term relapse and patients' worse survival. Moreover, multivariate regression models highlighted the independent prognostic value of miR-125b for childhood ALL. Finally, the combination of miR-125b with clinically used disease markers clearly enhanced the prediction of patients' resistance to BFM chemotherapy.

CONCLUSIONS

miR-125b significantly improves the prognosis of childhood ALL patients' outcome under BFM treatment.

MicroRNA-mediated drug resistance in ovarian cancer

The development of intrinsic or acquired resistance to chemotherapeutic agents used in the treatment of various human cancers is a major obstacle for the successful abolishment of cancer. The accumulated efforts in the understanding the exact mechanisms of development of multidrug resistance (MDR) have led to the introduction of several unique and common mechanisms. Recent studies demonstrate the regulatory role of small noncoding RNA or miRNA in the several parts of cancer biology. Practically all aspects of cell physiology under normal and disease conditions are reported to be controlled by miRNAs. In this review, we discuss how the miRNA profile is changed upon MDR development and the pivotal regulatory role played by miRNAs in overcoming resistance to chemotherapeutic agents. It is hoped that further studies will support the use of these differentially expressed miRNAs as prognostic and predictive markers, as well as novel therapeutic targets to overcome resistance in ovarian cancer.

Expression of miR-146a in patients with ovarian cancer and its clinical significance

The aim of the present retrospective study was to compare microRNA (miR)-146a expression levels in primary tumors and omental metastases of 48 patients, who had undergone surgery for advanced ovarian serous cancer. Possible correlations between miR-146a expression level and clinicopathological features were investigated, including chemosensitivity and survival. miR-146a was evaluated in formalin-fixed, paraffin-embedded samples. miR-146a expression level in primary tumors was demonstrated to be increased in comparison with normal ovary tissues (P=0.02) and metastases (P=0.01). A negative correlation was demonstrated between miR-146a expression in primary tumors and serum levels of cancer antigen 125 (R=-0.37; P=0.03) and Risk of Malignancy Algorithm index (R=-0.79; P=0.0007). Overall survival positively correlated with miR-146a expression in primary tumor tissue samples (R=0.38; P=0.01). Probability of survival was decreased in patients with low miR-146a expression levels in primary tumor tissues (hazard ratio=0.21; P=0.003). Lower levels of miR-146a in primary tumor tissue samples were correlated with a shorter progression-free survival (P=0.04) and platinum-resistance of metastases (P=0.006). In conclusion, miR-146a may be a prognostic marker for serous ovarian cancer.

Emerging diagnostic, prognostic and therapeutic biomarkers for ovarian cancer

BACKGROUND

In spite of various treatment options currently available, ovarian cancer (OC) still remains a leading cause of death in women world-wide. Diagnosis at an early stage is one of the most important factors that determines survival. Current clinical diagnostic tools have, however, a limited efficacy in early OC detection. Therefore, there is a critical need for new (early) diagnostic biomarkers and tools. Through advances in genomic, proteomic and metabolomic techniques, several novel molecular OC biomarkers have recently been identified. These biomarkers are currently subject to validation. In addition, integration of genomic, proteomic and metabolomic data, in conjunction with epidemiologic and clinical data, is considered essential for obtaining useful results. Interesting recent work has already shown that specific diagnostic biomarkers, such as BRCA mutations, may have profound therapeutic implications. Here, we review the current state of OC research through literature and database searches, with a focus on various recently identified biomarkers via different technologies for the (early) diagnosis, prognosis and treatment of OC.

CONCLUSIONS

Multi-biomarker panels accompanied by a meticulous determination of their sensitivity and specificity, as well their validation, using multivariate analyses will be critical for its clinical application, including early OC detection and tailor-made OC treatment.

microRNA-125b reverses the multidrug resistance of nasopharyngeal carcinoma cells via targeting of Bcl-2

Multidrug resistance (MDR) is a major clinical obstacle in the successful treatment of patients with metastatic nasopharyngeal carcinoma (NPC). Results from previous studies suggest that microRNAs (miRNA) may be involved in promoting MDR in multiple cancer types. However, the role of miR‑125b in modulating the MDR of NPC is elusive. In the present study, miR‑125b expression in cisplatin (DDP) ‑resistant CNE2 cells (CNE2/DDP) was compared with parental counterparts, using reverse transcription‑quantitative polymerase chain reaction. A >3‑fold reduction in miR‑125b expression levels was observed in CNE2/DDP cells compared with parental CNE2 cells. Ectopic expression of miR‑125b by transfecting CNE2/DDP cells with miR-125b mimics, increased DDP‑induced cytotoxicity, apoptosis and chemosensitivity. By contrast, suppression of miR-125b by transfecting CNE2 cells with miR‑125b inhibitors, reduced DDP‑induced cytotoxicity and apoptosis, and facilitated cisplatin resistance. The results suggest that miR‑125b may regulate the sensitivity of NPC cells to DDP by modulating the expression levels of antiapoptotic factor B-cell CLL/lymphoma 2. Collectively, the results of the present study highlight miR‑125b as a potential therapeutic target for reversing MDR in NPC.

Emerging diagnostic, prognostic and therapeutic biomarkers for ovarian cancer

BACKGROUND

In spite of various treatment options currently available, ovarian cancer (OC) still remains a leading cause of death in women world-wide. Diagnosis at an early stage is one of the most important factors that determines survival. Current clinical diagnostic tools have, however, a limited efficacy in early OC detection. Therefore, there is a critical need for new (early) diagnostic biomarkers and tools. Through advances in genomic, proteomic and metabolomic techniques, several novel molecular OC biomarkers have recently been identified. These biomarkers are currently subject to validation. In addition, integration of genomic, proteomic and metabolomic data, in conjunction with epidemiologic and clinical data, is considered essential for obtaining useful results. Interesting recent work has already shown that specific diagnostic biomarkers, such as BRCA mutations, may have profound therapeutic implications. Here, we review the current state of OC research through literature and database searches, with a focus on various recently identified biomarkers via different technologies for the (early) diagnosis, prognosis and treatment of OC.

CONCLUSIONS

Multi-biomarker panels accompanied by a meticulous determination of their sensitivity and specificity, as well their validation, using multivariate analyses will be critical for its clinical application, including early OC detection and tailor-made OC treatment.

Emerging diagnostic, prognostic and therapeutic biomarkers for ovarian cancer

BACKGROUND

In spite of various treatment options currently available, ovarian cancer (OC) still remains a leading cause of death in women world-wide. Diagnosis at an early stage is one of the most important factors that determines survival. Current clinical diagnostic tools have, however, a limited efficacy in early OC detection. Therefore, there is a critical need for new (early) diagnostic biomarkers and tools. Through advances in genomic, proteomic and metabolomic techniques, several novel molecular OC biomarkers have recently been identified. These biomarkers are currently subject to validation. In addition, integration of genomic, proteomic and metabolomic data, in conjunction with epidemiologic and clinical data, is considered essential for obtaining useful results. Interesting recent work has already shown that specific diagnostic biomarkers, such as BRCA mutations, may have profound therapeutic implications. Here, we review the current state of OC research through literature and database searches, with a focus on various recently identified biomarkers via different technologies for the (early) diagnosis, prognosis and treatment of OC.

CONCLUSIONS

Multi-biomarker panels accompanied by a meticulous determination of their sensitivity and specificity, as well their validation, using multivariate analyses will be critical for its clinical application, including early OC detection and tailor-made OC treatment.

A microRNA expression signature for clinical response in locally advanced cervical cancer

OBJECTIVE

Nearly 50% of patients who are diagnosed with locally advanced cervical cancer have an unfavorable pathological response to conventional treatment. MicroRNAs (miRNAs) are potential biomarkers in cervical cancer; however, their role in identifying patients who do not respond to conventional treatment remains poorly investigated. Here, we identify a set of miRNAs that can be used as molecular markers to predict the pathological response in locally advanced cervical cancer patients receiving radiation and chemotherapy treatment.

METHODS

Forty-one patients diagnosed with locally advanced cervical cancer were invited to participate in this study and enrolled after they signed an informed consent. Two patient cohorts were randomized for miRNA expression profiling, a discovery cohort (n=10) and a validation cohort (n=31); profiling was performed by means of a miScript miRNA PCR Array. After a median clinical follow-up of 45months, statistical analysis was performed to identify miRNAs that could discriminate non-responders from complete pathological responders to conventional treatment.

RESULTS

miRNA expression profiling identified 101 miRNAs that showed significant differences between non-responders and complete pathological responders (p<0.05). Seven differentially expressed miRNAs were selected, and their expression patterns were confirmed in the validation phase; thus, miR-31-3p, -3676, -125a-5p, -100-5p, -125b-5p, and -200a-5p and miR-342 were significantly associated with clinical response. Expression of this miRNA signature above the median level was a significant predictor of non-response to standard treatment (p<0.001).

CONCLUSIONS

These seven validated miRNA signatures could be used as molecular biomarkers of chemo- and radio-resistance in locally advanced cervical cancer patients.

Utility of Serum miR-125b as a Diagnostic and Prognostic Indicator and Its Alliance with a Panel of Tumor Suppressor Genes in Epithelial Ovarian Cancer

MicroRNAs (miRNAs) have been found to be dysregulated in epithelial ovarian cancer (EOC) and may function as either tumor suppressor genes (TSGs) or as oncogenes. Hypermethylation of miRNA silences the tumour suppressive function of a miRNA or hypermethylation of a TSG regulating that miRNA (or vice versa) leads to its loss of function. The present study aims to evaluate the impact of aberrant microRNA-125b (miR-125b) expression on various clinicopathological features in epithelial ovarian cancer and its association with anomalous methylation of several TSGs. We enrolled 70 newly diagnosed cases of epithelial ovarian cancer, recorded their clinical history and 70 healthy female volunteers. Serum miR-125b levels were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and the methylation status of various TSGs was investigated by methylation specific PCR. ROC curves were constructed to estimate the diagnostic and prognostic usefulness of miR-125b. The Kaplan-Meier method was applied to compare survival curves. Expression of miR-125b was found to be significantly upregulated (p<0.0001) in comparison with healthy controls. The expression level of miR-125b was found to be significantly associated with FIGO stage, lymph node and distant metastasis. ROC curve for diagnostic potential yielded significant AUC with an equitable sensitivity and specificity. ROC curves for prognosis yielded significant AUCs for histological grade, distal metastasis, lymph node status and survival. The expression of miR-125b also correlated significantly with the hypermethylation of TSGs. Our results indicate that DNA hypermethylation may be involved in the inactivation of miR-125b and miR-125b may function as a potential independent biomarker for clinical outcome in EOC.

MicroRNA-155 promotes apoptosis in SKOV3, A2780, and primary cultured ovarian cancer cells

MicroRNAs (miRNAs) are a large group of small non-coding RNAs that can negatively regulate gene expression at the post-transcriptional level. The deregulation of miRNAs has been associated with tumorigenesis, drug resistance, and prognosis in cancers. Deregulated miR-155 has been reported in numerous cancers; however, its function remains unclear. 4',6-Diamidino-2-phenylindole (DAPI) staining and terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) techniques were used to determine the effects of a miR-155 mimic or inhibitor on the apoptotic ratio of ovarian cancer cells induced by cisplatin. Bioinformatic predictions, the dual-luciferase reporter assay, and western blot analysis were used to detect how miR-155 regulates X-linked inhibitor of apoptosis protein (XIAP). We demonstrated that a miR-155 mimic could decrease the IC50 value of cisplatin in SKOV3 ovarian cancer cells. Subsequently, gain- and loss-of-function analyses with a miR-155 mimic and inhibitor showed that miR-155 sensitizes ovarian cancer cells to cisplatin. Furthermore, the results from the luciferase assays and western blot analysis identified XIAP as the direct target of miR-155. In addition, introducing XIAP cDNA without a three prime untranslated region (3'-UTR) rescued the miR-155 promotion of apoptosis. These results indicate that miR-155 mediates cisplatin-induced apoptosis by targeting XIAP in ovarian cancer cells and that miR-155 could be a potential therapeutic target to increase the efficiency of ovarian cancer interventions.

miRNAs and ovarian cancer: a miRiad of mechanisms to induce cisplatin drug resistance

Ovarian cancer is the most aggressive gynecological cancer. One reason for the low 5-year survival rate of under 40% is that ovarian tumors usually acquire resistance to the platinum-based compounds used to treat them. Resistance to one such compound, cisplatin, can arise via numerous mechanisms that can be categorized as pre-, post-, on- or off-target. Pre-target mechanisms prevent accumulation of cisplatin in the cell, on-target mechanisms allow DNA damage to be repaired more efficiently, post-target mechanisms prevent the damage from inducing apoptosis and off-target mechanisms increase resistance via unrelated compensatory mechanisms. miRNAs are short non-coding RNAs that influence cellular function by repressing gene expression. Here we describe how miRNAs can induce cisplatin resistance in ovarian cancer cells via pre-, post-, on- and off-target mechanisms. A better understanding of how miRNAs feed into the mechanisms of drug resistance will inform the rational design of combination therapies for ovarian cancer.

miRNAs as prognostic and therapeutic tools in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and is the fifth leading cause of cancer deaths in women. Developing adjuvant therapy to circumvent drug resistance represents an important aspect of current initiatives to improve survival in women with advanced EOC. A regulatory molecule that can act on multiple genes associated with a chemoresistant phenotype will be the ideal target for the development of therapeutics to overcome resistance and miRNAs constitute promising tools in this regard. In this review, we discuss the emerging role of miRNAs in regulating EOC phenotype with a focus on prognostic and therapeutic importance of miRNAs and the possibility of miRNA modulation as a tool to improve efficacy of chemotherapy in EOC.

NRP1 is targeted by miR-130a and miR-130b, and is associated with multidrug resistance in epithelial ovarian cancer based on integrated gene network analysis

Multidrug resistance (MDR) in epithelial ovarian cancer (EOC) remains a public health issue for women worldwide, and its molecular mechanisms remain to be fully elucidated. The present study aimed to predict the potential genes involved in MDR, and examine the mechanisms underlying MDR in EOC using bioinformatics techniques. In the present study, four public microarray datasets, including GSE41499, GSE33482, GSE15372 and GSE28739, available in Gene Expression Omnibus were downloaded, and 11 microRNAs (miRNA; miRs), including miR-130a, miR-214, let-7i, miR-125b, miR-376c, miR-199a, miR-93, miR-141, miR-130b, miR-193b^* and miR-200c, from previously published reports in PubMed were used to perform a comprehensive bioinformatics analysis through gene expression analysis, signaling pathway analysis, literature co-occurrence and miRNA-mRNA interaction networks. The results demonstrated that the expression of neuropilin 1 (NRP1) was upregulated, thereby acting as the most important hub gene in the integrated gene network. NRP1 was targeted by miR-130a and miR-130b at the binding site of chromosome 10: 33466864-3466870, which was involved in the axon guidance signaling pathway. These results suggested that alteration of the gene expression levels of NRP1 expression may contribute to MDR in EOC. These data provide important information for further experimental investigations of the drug resistance-associated functions of NRP1 in EOC.

Induction of Autophagic Death in Cancer Cells by Agonizing TR3 and Attenuating Akt2 Activity

Apoptotic resistance is becoming a significant obstacle for cancer therapy as the majority of treatment takes the route of apoptotic induction. It is of great importance to develop an alternative strategy to induce cancer cell death. We previously reported that autophagic cell death mediated by nuclear receptor TR3 and driven by a chemical agonist, 1-(3,4,5-trihydroxyphenyl)nonan-1-one (THPN), is highly effective in the therapy of melanoma but not any other cancer types. Here, we discovered that the insensitivity of cancer cells to THPN originated from a high cellular Akt2 activity. Akt2 phosphorylation interferes with TR3 export to cytoplasm and targeting to mitochondria, which lead to the autophagic induction. Therefore, the TR3-mediated autophagy could be effectively induced in the otherwise insensitive cells by downregulating Akt2 activity. Highly effective antineoplastic compounds are developed through optimizing the structure of THPN. This study implicates a general strategy for cancer therapy by the induction of autophagic cell death.

Hybrid-polymerase chain reaction to identify novel target genes of miR-134 in paclitaxel resistant human ovarian carcinoma cells

Increasing evidence has shown that miR-134 is involved in the promotion of tumorigenesis and chemoresistance. However, whether miR-134 participates in ovarian cancer chemoresistance and its functional targets still remains unclear. The objective of this study was to apply hybrid-polymerase chain reaction (PCR) to screen target genes of miR-134 in ovarian carcinoma paclitaxel resistant SKOV3-TR30 cells, and to provide a number of novel targets of miR-134 for further study of ovarian cancer paclitaxel resistance. The current study found that miR-134 was decreased in SKOV3-TR30 cells compared with the parental SKOV3 cell line. By applying hybrid-PCR, 8 putative target genes of miR-134 in SKOV3-TR30 cells were identified, including C16orf72, PNAS-105, SRM, VIM, F-box protein 2, GAPDH, PRPF6 and RPL41. Notably, the target sites of VIM and PRPF6 were not located in 3'untranslated region, but rather in the coding sequence region. By conducting a luciferase reporter assay, miR-134 was demonstrated to recognize the putative binding sites of these target genes including VIM and PRPF6. Transfecting SKOV3-TR30 cells with miR-134 mimic and performing reverse transcription-PCR in addition to western blot analysis confirmed that miR-134 regulates vimentin expression at a post transcriptional level. This finding provides a novel perspective for studying the mechanism of miR-134/mRNA interaction. In conclusion, this study was the first to apply an effective method of hybrid-PCR to screen putative target mRNAs of miR-134 in paclitaxel resistant SKOV3-TR30 cells and indicate that miR-134 may contribute to the induction of SKOV3-TR30 paclitaxel resistance by targeting these genes.

Epigenetic mechanisms and therapeutic targets of chemotherapy resistance in epithelial ovarian cancer

Epithelial ovarian cancer is the most lethal gynaecological cancer with the majority of patients succumbing to chemotherapy-resistant disease. Unravelling the mechanisms of drug resistance and how it can be prevented or reversed is a pivotal challenge in the treatment of cancer. Epigenetic mechanisms appear to play a crucial role in the development of inherent and acquired resistance in ovarian cancer. Aberrant epigenetic states can be reversed by drug therapy, and thus maintenance of epigenetic change is a potential target to halt or reverse chemotherapy resistance. This review explores the evidence that demonstrates that DNA methylation, histone modification, and microRNAs are associated with inherent and acquired chemotherapy resistance in ovarian cancer and the current challenges associated with this. We also explore current epigenetic therapies used in patients with drug-resistant ovarian cancer and future potential targets.