MicroRNA let-7a: a potential marker for selection of paclitaxel in ovarian cancer management

The microRNA Let-7 and its exosomal form: Epigenetic regulators of gynecological cancers

Many types of gynecological cancer (GC) are often silent until they reach an advanced stage, and are therefore often diagnosed too late for effective treatment. Hence, there is a real need for more efficient diagnosis and treatment for patients with GC. During recent years, researchers have increasingly studied the impact of microRNAs cancer development, leading to a number of applications in detection and treatment. MicroRNAs are a particular group of tiny RNA molecules that regulate regular gene expression by affecting the translation process. The downregulation of numerous miRNAs has been observed in human malignancies. Let-7 is an example of a miRNA that controls cellular processes as well as signaling cascades to affect post-transcriptional gene expression. Recent research supports the hypothesis that enhancing let-7 expression in those cancers where it is downregulated may be a potential treatment option. Exosomes are tiny vesicles that move through body fluids and can include components like miRNAs (including let-7) that are important for communication between cells. Studies proved that exosomes are able to enhance tumor growth, angiogenesis, chemoresistance, metastasis, and immune evasion, thus suggesting their importance in GC management.

Detection of intracellular microRNA-21 for cancer diagnosis by a nanosystem containing a ZnO@polydopamine and DNAzyme probe

MicroRNAs (miRNAs) are a series of single-stranded non-coding ribonucleic acid (RNA) molecules which associated closely with various human diseases. Efficient strategies for detecting miRNAs are of great significance to cancer diagnosis and prognosis. Here we provide a novel nanosystem that can be applied for the detection of miRNAs. The nanosystem consists of a single-stranded deoxyribonucleic acid (DNA) probe and a probe carrier. The DNA probe was designed based on a deoxyribozyme (DNAzyme) with several necessary functional sequences and two fluorescent dyes labeled at proper sites. The ZnO@polydopamine (ZnO@PDA) nanomaterial serves not only as a probe carrier, but also as a supplier of Zn2+ that can activate the DNAzyme. The DNA probe will undergo a conformation alteration induced by miRNA-21, which then trigger the DNAzyme catalyzed self-cleavage reaction with the assist of Zn2+ provided by ZnO decomposition under weak acid environment. A change of fluorescent color will occur due to the interruption of fluorescence resonance energy transfer between the two fluorescent dyes, and the dissociated miRNA-21 can repeatedly induce the above responses to amplify the fluorescence signal. The feasibility of the whole procedure was demonstrated by various experiments. This nanosystem showed a good selectivity towards miRNA-21, and under the optimal incubation time of 2 hours, a good linear relationship was obtained in a concentration range of 0.01-2.0 nM with a detection limit of 3.8 pM. In in vivo detection, an obvious fluorescence color change from red to green can be observed in the presence of miRNA-21. The results proved that this miRNA detection strategy has a broad application prospect in tumor diagnosis and miRNA related biological studies.

Current strategies for early epithelial ovarian cancer detection using miRNA as a potential tool

Ovarian cancer is one of the most aggressive and significant malignant tumor forms in the female reproductive system. It is the leading cause of death among gynecological cancers owing to its metastasis. Since its preliminary disease symptoms are lacking, it is imperative to develop early diagnostic biomarkers to aid in treatment optimization and personalization. In this vein, microRNAs, which are short sequence non-coding molecules, displayed great potential as highly specific and sensitive biomarker. miRNAs have been extensively advocated and proven to serve an instrumental part in the clinical management of cancer, especially ovarian cancer, by promoting the cancer cell progression, invasion, delayed apoptosis, epithelial-mesenchymal transition, metastasis of cancer cells, chemosensitivity and resistance and disease therapy. Here, we cover our present comprehension of the most up-to-date microRNA-based approaches to detect ovarian cancer, as well as current diagnostic and treatment strategies, the role of microRNAs as oncogenes or tumor suppressor genes, and their significance in ovarian cancer progression, prognosis, and therapy.

MiRNAs related in signaling pathways of women's reproductive diseases: an overview

BACKGROUND

One of the main health issues that can affect women's health is reproductive diseases, such as polycystic ovary syndrome (PCOS), endometriosis (EMs), uterine leiomyomas (ULs), and ovarian cancer (OC). Although these diseases are very common, we do not have a complete understanding of their underlying cellular and molecular mechanisms. It is important to mention that the majority of patients are diagnosed with these diseases at later stages because of the absence of early diagnostic techniques and dependable molecular indicators. Hence, it is crucial to discover novel and non-invasive biomarkers that have prognostic, diagnostic and therapeutic capabilities. MiRNAs, also known as microRNAs, are small non-coding RNAs that play a crucial role in regulating gene expression at the post-transcriptional level. They are short in length, typically consisting of around 22 nucleotides, and are highly conserved across species. Numerous studies have shown that miRNAs are expressed differently in various diseases and can act as either oncogenes or tumor suppressors.

METHODS

The author conducted a comprehensive review of all the pertinent papers available in web of science, PubMed, Google Scholar, and Scopus databases.

RESULTS

We achieved three goals: providing readers with better information, enhancing search results, and making peer review easier.

CONCLUSIONS

This review focuses on the investigation of miRNAs and their involvement in various reproductive disorders in women, including their molecular targets. Additionally, it explores the role of miRNAs in the development and progression of these disorders.

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.

Noncoding RNome as Enabling Biomarkers for Precision Health

Noncoding RNAs (ncRNAs), in the form of structural, catalytic or regulatory RNAs, have emerged to be critical effectors of many biological processes. With the advent of new technologies, we have begun to appreciate how intracellular and circulatory ncRNAs elegantly choreograph the regulation of gene expression and protein function(s) in the cell. Armed with this knowledge, the clinical utility of ncRNAs as biomarkers has been recently tested in a wide range of human diseases. In this review, we examine how critical factors govern the success of interrogating ncRNA biomarker expression in liquid biopsies and tissues to enhance our current clinical management of human diseases, particularly in the context of cancer. We also discuss strategies to overcome key challenges that preclude ncRNAs from becoming standard-of-care clinical biomarkers, including sample pre-analytics standardization, data cross-validation with closer attention to discordant findings, as well as correlation with clinical outcomes. Although harnessing multi-modal information from disease-associated noncoding RNome (ncRNome) in biofluids or in tissues using artificial intelligence or machine learning is at the nascent stage, it will undoubtedly fuel the community adoption of precision population health.

Gene Therapy for Malignant and Benign Gynaecological Disorders: A Systematic Review of an Emerging Success Story

Simple Summary

This review discusses all the major advances in gene therapy of gynaecological disorders, highlighting the novel and potentially therapeutic perspectives associated with such an approach. It specifically focuses on the gene therapy strategies against major gynaecological malignant disorders, such as ovarian, cervical, and endometrial cancer, as well as benign disorders, such as uterine leiomyomas, endometriosis, placental, and embryo implantation disorders. The above therapeutic strategies, which employ both viral and non-viral systems for mutation compensation, suicide gene therapy, oncolytic virotherapy, antiangiogenesis and immunopotentiation approaches, have yielded promising results over the last decade, setting the grounds for successful clinical trials.

Abstract

Despite the major advances in screening and therapeutic approaches, gynaecological malignancies still present as a leading cause of death among women of reproductive age. Cervical cancer, although largely preventable through vaccination and regular screening, remains the fourth most common and most lethal cancer type in women, while the available treatment schemes still pose a fertility threat. Ovarian cancer is associated with high morbidity rates, primarily due to lack of symptoms and high relapse rates following treatment, whereas endometrial cancer, although usually curable by surgery, it still represents a therapeutic problem. On the other hand, benign abnormalities, such as fibroids, endometriosis, placental, and embryo implantation disorders, although not life-threatening, significantly affect women’s life and fertility and have high socio-economic impacts. In the last decade, targeted gene therapy approaches toward both malignant and benign gynaecological abnormalities have led to promising results, setting the ground for successful clinical trials. The above therapeutic strategies employ both viral and non-viral systems for mutation compensation, suicide gene therapy, oncolytic virotherapy, antiangiogenesis and immunopotentiation. This review discusses all the major advances in gene therapy of gynaecological disorders and highlights the novel and potentially therapeutic perspectives associated with such an approach.

The Role of microRNA Let-7d in Female Malignancies and Diseases of the Female Reproductive Tract

microRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level. Let-7d is a microRNA of the conserved let-7 family that is dysregulated in female malignancies including breast cancer, ovarian cancer, endometrial cancer, and cervical cancer. Moreover, a dysregulation is observed in endometriosis and pregnancy-associated diseases such as preeclampsia and fetal growth restriction. Let-7d expression is regulated by cytokines and steroids, involving transcriptional regulation by OCT4, MYC and p53, as well as posttranscriptional regulation via LIN28 and ADAR. By downregulating a wide range of relevant mRNA targets, let-7d affects cellular processes that drive disease progression such as cell proliferation, apoptosis (resistance), angiogenesis and immune cell function. In an oncological context, let-7d has a tumor-suppressive function, although some of its functions are context-dependent. Notably, its expression is associated with improved therapeutic responses to chemotherapy in breast and ovarian cancer. Studies in mouse models have furthermore revealed important roles in uterine development and function, with implications for obstetric diseases. Apart from a possible utility as a diagnostic blood-based biomarker, pharmacological modulation of let-7d emerges as a promising therapeutic concept in a variety of female disease conditions.

Clinical significance of microRNA-200 and let-7 families expression assessment in patients with ovarian cancer

Ovarian cancer (OC) represents the most lethal malignancy in gynaecologic oncology practice and shows a high recurrence rate due to its early chemoresistance to first-line chemotherapy. Yet, timely selection of the correct treatment strategy is likely to prolong a patient's survival. MicroRNAs (miRNAs) are a class of short non-coding RNAs responsible for the expression of 30%-60% of human genes. In numerous studies, miRNAs have been used to provide the overall prognosis for patients and analyse the process's prevalence and responses to chemotherapy. In particular, miRNAs as markers for predicting the sensitivity of OC to platinum- and taxane-based chemotherapeutics can significantly improve the treatment efficacy. This article highlights two families of miRNAs: miR-200 and let-7, which are promising for further research on OC and its chemosensitivity.

The Sonic Hedgehog signaling pathway regulates autophagy and migration in ovarian cancer

Background

The Sonic Hedgehog (SHH) signaling pathway plays an important role in various types of human cancers including ovarian cancer; however, its function and underlying mechanism in ovarian cancer are still not entirely understood.

Methods

We detected the expressions of SHH and SQSTM1 in borderline ovarian tumor tissues, epithelial ovarian cancer (EOC) tissues and benign ovarian tumor tissues. Cyclopamine (Cyp, a well‐known inhibitor of SHH signaling pathway) and chloroquine (CQ, the pharmaceutical inhibitor of autophagy) were used in vivo and in vitro (autophagic flux, CCK‐8 assay, wound healing assay, transwell assay, tumor xenograft model). The mechanism of action was explored through Quantitative RT‐PCR and Western Blot.

Results

We found up‐regulation of SHH and accumulation of SQSTM1/P62 in epithelial ovarian cancer. Cyp induced autophagy through the PI3K/AKT signaling pathway. Moreover, low‐dose Cyp and chloroquine (CQ) significantly promoted the migratory ability of SKOV3 cells.

Conclusions

Our findings suggest that inhibition of the SHH pathway and autophagy may be a potential and effective therapy for the treatment of ovarian cancer.

Current Implications of microRNAs in Genome Stability and Stress Responses of Ovarian Cancer

Genomic alterations and aberrant DNA damage signaling are hallmarks of ovarian cancer (OC), the leading cause of mortality among gynecological cancers worldwide. Owing to the lack of specific symptoms and late-stage diagnosis, survival chances of patients are significantly reduced. Poly (ADP-ribose) polymerase (PARP) inhibitors and replication stress response inhibitors present attractive therapeutic strategies for OC. Recent research has focused on ovarian cancer-associated microRNAs (miRNAs) that play significant regulatory roles in various cellular processes. While miRNAs have been shown to participate in regulation of tumorigenesis and drug responses through modulating the DNA damage response (DDR), little is known about their potential influence on sensitivity to chemotherapy. The main objective of this review is to summarize recent findings on the utility of miRNAs as cancer biomarkers, in particular, ovarian cancer, and their regulation of DDR or modified replication stress response proteins. We further discuss the suppressive and promotional effects of various miRNAs on ovarian cancer and their participation in cell cycle disturbance, response to DNA damage, and therapeutic functions in multiple cancer types, with particular focus on ovarian cancer. Improved understanding of the mechanisms by which miRNAs regulate drug resistance should facilitate the development of effective combination therapies for ovarian cancer.

Astragalus polysaccharides inhibit ovarian cancer cell growth via microRNA-27a/FBXW7 signaling pathway

Astragalus polysaccharide (APS), a natural antioxidant found in Astragalus membranaceus emerging as a novel anticancer agent, exerts antiproliferative and pro-apoptotic activity in various cancer cell types, but its effect on ovarian cancer (OC) remains unknown. In the present study, we tried to elucidate the role and mechanism of APS in OC cells. Our results showed that APS treatment suppressed the proliferation and induced apoptosis in OC cells. Afterward, the microRNA (miRNA) profiles in APS-treated cells were determined by a microarray assay, and whether APS affected OV-90 cells through regulation of miRNA was determined. Among these aberrant miRNAs, miR-27a was selected for further study as its oncogenic roles in various human cancers. Moreover, we found overexpression of miR-27a reversed the antiproliferation and pro-apoptotic effects of APS on OC cells. F-box and WD-40 domain protein 7 (FBXW7), a classical tumor suppressor, was found directly targeted by miR-27a and its translation was suppressed by miR-27a in OC cells. Finally, it was also observed that knockdown of FBXW7 by si-FBXW7 reversed the tumor suppressive activity of APS in OC cells, which is similar to the effects of miR-27a overexpression. Our findings demonstrate that APS can suppress OC cell growth in vitro via miR-27a/FBXW7 axis, and this observation reveals the therapeutic potential of APS for treatment of OC.

miR-361-5p regulates ovarian cancer cell proliferation and apoptosis by targeting TRAF3

An increasing body of evidence has demonstrated that the abnormal expression of microRNAs (miRNAs) participate in the development and progression of ovarian cancer. miR-361-5p has been reported to serve as a tumor suppressor or oncogene in a number of different human cancer types. In the current study, it was indicated that miR-361-5p was highly expressed in ovarian cancer tissues. Compared with human ovarian epithelial cells HOSEpiC, miR-361-5p was upregulated in ovarian cancer cell lines, including in ES-2 and SKOV3 cells. The binding sites between TNF receptor-associated factor 3 (TRAF3; a member of the TRAF family of cytoplasmic adaptor proteins) and miR-361-5p were predicted using TargetScan, and a dual luciferase reporter gene assay verified the result. Subsequently, a reverse transcription-quantitative PCR assay and western blot assay indicated that TRAF3 was downregulated in ovarian cancer tissues and cell lines. It was demonstrated that miR-361-5p inhibitor significantly reduced the viability of SKOV3 cells and induced apoptosis. However, all changes were reversed by TRAF3 silencing. Furthermore, it was demonstrated that miR-361-5p inhibitor decreased the expression of p-p65 in SKOV3 cells, indicating the inhibition of the NF-kB signaling pathway. In conclusion, miR-361-5p may regulate the proliferation and apoptosis of ovarian cancer cells by targeting TRAF3. Therefore, targeting miR-361-5p may exhibit therapeutic potential in the treatment of ovarian cancer.

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.

Prognostic impact of Dynamin related protein 1 (Drp1) in epithelial ovarian cancer

BACKGROUND

The mitochondrial fission protein, Dynamin related protein 1 (Drp1), and its upstream protein calcium/calmodulin-dependent protein kinase I (CaMKI) play a critical role in chemoresistance in ovarian cancer (OVCA). Thus, we examined the expression of Drp1, CaMKI and their phosphorylated forms and their prognostic impact in epithelial OVCA patients.

METHODS

Expression analysis was performed by immunohistochemistry (IHC) of paraffin-embedded tumor samples from 49 patients with epithelial OVCA. Staining intensity and the percentage of positively stained tumor cells were used to calculate an immunoreactive score (IRS) of 0-12. The expression scores calculated were correlated with clinicopathological parameters and patient survival.

RESULTS

High immunoreactivity of phospho-Drp1Ser637 was significantly correlated with high-grade serous carcinoma (HGSC) (p = 0.034), residual postoperative tumor of > 1 cm (p = 0.006), and non-responders to adjuvant chemotherapy (p = 0.007), whereas high expression of CaMKI was significantly correlated with stage III/IV [International Federation of Gynecologists and Obstetricians (FIGO)] (p = 0.011) and platinum-resistant recurrence (p = 0.030). ROC curve analysis showed that Drp1, phospho-Drp1Ser637 and CaMKI could significantly detect tumor progression with 0.710, 0.779, and 0.686 of area under the curve (AUC), respectively. The Kaplan-Meier survival curve showed that patients with high Drp1, phospho-Drp1Ser637 and CaMKI levels had significantly poorer progression free survival (PFS) (p = 0.003, p < 0.001 and p = 0.017, respectively). Using multivariate analyses, phospho-Drp1Ser637 was significantly associated with PFS [p = 0.043, hazard ratio (HR) 3.151, 95% confidence interval (CI) 1.039-9.561].

CONCLUSIONS

Drp1 and CaMKI are novel potential candidates for the detection and prognosis of epithelial OVCA and as such further studies should be performed to exploit their therapeutic significance.

miRNAs as Biomarkers in Disease: Latest Findings Regarding Their Role in Diagnosis and Prognosis

MicroRNAs (miRNAs) represent a class of small, non-coding RNAs with the main roles of regulating mRNA through its degradation and adjusting protein levels. In recent years, extraordinary progress has been made in terms of identifying the origin and exact functions of miRNA, focusing on their potential use in both the research and the clinical field. This review aims at improving the current understanding of these molecules and their applicability in the medical field. A thorough analysis of the literature consulting resources available in online databases such as NCBI, PubMed, Medline, ScienceDirect, and UpToDate was performed. There is promising evidence that in spite of the lack of standardized protocols regarding the use of miRNAs in current clinical practice, they constitute a reliable tool for future use. These molecules meet most of the required criteria for being an ideal biomarker, such as accessibility, high specificity, and sensitivity. Despite present limitations, miRNAs as biomarkers for various conditions remain an impressive research field. As current techniques evolve, we anticipate that miRNAs will become a routine approach in the development of personalized patient profiles, thus permitting more specific therapeutic interventions.

Pharmacokinetic evaluation and antitumor potency of liposomal nanoparticle encapsulated cisplatin targeted to CD24-positive cells in ovarian cancer

CD24, which is upregulated in several human malignancies, is related to Epithelial-mesenchymal-transition (EMT) and has characteristics of cancer stem-like cells, especially in cisplatin-resistant ovarian carcinoma cells. Drug delivery systems represent a promising therapeutic approach for diseases with treatment resistance, and the present study investigated a novel CD24-targeted drug delivery system for advanced ovarian carcinoma. We produced liposomal cisplatin with a red fluorescent substance - cyanine 5.5 (GL-CDDP-Cy5.5). In order to target CD24-positive cells, an anti-CD24 monoclonal antibody was modified to the above drug (CD24-GL-CDDP-Cy5.5). Specific uptake of CD24-GL-CDDP-Cy5.5 was confirmed using a therapeutically resistant ovarian cancer cell line, Caov-3 cells. Antitumor effects of CD24-GL-CDDP-Cy5.5 were then evaluated in Caov-3 ×enograft mice. CD24-GL-CDDP-Cy5.5 showed more specific uptake by flow cytometry than GL-CDDP-Cy5.5. In xenograft mice, GL-CDDP-Cy5.5 and CD24-GL-CDDP-Cy5.5 treatment had significantly higher platinum concentration in disseminated tumor cells than cisplatin (P<0.05). Moreover, CD24-GL-CDDP-Cy5.5 suppressed tumor growth and prolonged survival time compared with other treatments. Median survival times of the control, cisplatin, GL-CDDP-Cy5.5 and CD24-GL-CDDP-Cy5.5 groups were 37, 36, 46 and 54 days after inoculation, respectively. Immunohistochemical analysis showed that CD24-GL-CDDP-Cy5.5 treatment, compared with GL-CDDP-Cy5.5, decreased the number of CD24-positive cells and suppressed the EMT phenomenon significantly (P<0.05). The present study demonstrated that CD24-GL-CDDP-Cy5.5, compared with other treatments, improved therapeutic efficacy. The present results suggested the potential for targeting anticancer therapeutics for CD24-positive cells to prevent disease progression.

Circulating non‑coding RNA‑biomarker potential in neoadjuvant chemotherapy of triple negative breast cancer?

Due to the positive association between neoadjuvant chemotherapy (NACT) and the promising early response rates of patients with triple negative breast cancer (TNBC), including probabilities of pathological complete response, NACT is increasingly used in TNBC management. Liquid biopsy-based biomarkers with the power to diagnose the early response to NACT may support established monitoring tools, which are to a certain extent imprecise and costly. Simple serum- or urine-based analyses of non-coding RNA (ncRNA) expression may allow for fast, minimally-invasive testing and timely adjustment of the therapy regimen. The present study investigated breast cancer-related ncRNAs [microRNA (miR)-7, -9, -15a, -17, -18a, -19b, -21, -30b, -222 and -320c, PIWI-interacting RNA-36743 and GlyCCC2] in triple positive BT-474 cells and three TNBC cell lines (BT-20, HS-578T and MDA-MB-231) treated with various chemotherapeutic agents using reverse transcription-quantitative PCR. Intracellular and secreted microvesicular ncRNA expression levels were analysed using a multivariable statistical regression analysis. Chemotherapy-driven effects were investigated by analysing cell cycle determinants at the mRNA and protein levels. Serum and urine specimens from 8 patients with TNBC were compared with 10 healthy females using two-sample t-tests. Samples from the patients with TNBC were compared at two time points. Chemotherapeutic treatments induced distinct changes in ncRNA expression in TNBC cell lines and the BT-474 cell line in intra- and extracellular compartments. Serum and urine-based ncRNA expression analysis was able to discriminate between patients with TNBC and controls. Time point comparisons in the urine samples of patients with TNBC revealed a general rise in the level of ncRNA. Serum data suggested a potential association between piR-36743, miR-17, -19b and -30b expression levels and an NACT-driven complete clinical response. The present study highlighted the potential of ncRNAs as liquid biopsy-based biomarkers in TNBC chemotherapy treatment. The ncRNAs tested in the present study have been previously investigated for their involvement in BC or TNBC chemotherapy responses; however, these previous studies were restricted to patient tissue or in vitro models. The data from the present study offer novel insight into ncRNA expression in liquid samples from patients with TNBC, and the study serves as an initial step in the evaluation of ncRNAs as diagnostic biomarkers in the monitoring of TNBC therapy.

Systematic Identification of Characteristic Genes of Ovarian Clear Cell Carcinoma Compared with High-Grade Serous Carcinoma Based on RNA-Sequencing

Objective: Ovarian cancer has the highest mortality among gynecological cancers. High-grade serous carcinoma (HGSC) is the most common histotype of ovarian cancer regardless of ethnicity, whereas clear cell carcinoma (CCC) is more common in East Asians than Caucasians. The elucidation of predominant signaling pathways in these cancers is the first step towards understanding their molecular mechanisms and developing their clinical management. Methods: RNA sequencing was performed for 27 clinical ovarian specimens from Japanese women. Principal component analysis (PCA) was conducted on the sequence data mapped on RefSeq with normalized read counts, and functional annotation analysis was performed on genes with substantial weights in PCA. Knockdown experiments were conducted on the selected genes on the basis of PCA. Results: Functional annotation analysis of PCA-defined genes showed predominant pathways, such as cell growth regulators and blood coagulators in CCC and transcription regulators in HGSC. Knockdown experiments showed that the inhibition of the calcium-dependent protein copine 8 (CPNE8) and the transcription factor basic helix-loop-helix family member e 41 (BHLHE41) repressed the proliferation of CCC- and HGSC-derived cells, respectively. Conclusions: This study identified CPNE8 and BHLHE41 as characteristic genes for CCC and HGSC, respectively. The systemic identification of differentially expressed genes in CCC and HGSC will provide useful information to understand transcriptomic differences in these ovarian cancers and to further develop potential diagnostic and therapeutic options for advanced disease.

MicroRNA let-7a inhibits proliferation of breast cancer cell by downregulating USP32 expression

Background

The present study aimed to investigate the effect of microRNA (miR) let-7a on ubiquitin specific protease 32 (USP32) expression and its potential function in MCF-7 breast cancer (BCa) cell line.

Methods

BCa MCF-7 cells were transfected with hsa-miR let-7a mimics or inhibitors, then the USP32 expression was evaluated using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis in the transfected cells. USP32 as a target regulated by miR let-7a was confirmed via Dual-luciferase reporter assay. The effects of miR let-7a on the viability were determined using MTT assay and colony formation analysis.

Results

Western blot analysis revealed that miR let-7a mimics dramatically decreased the USP32 protein expression, whereas miR let-7a inhibitors increased the protein expression of USP32 compared with their controls in the MCF-7 cells. Dual-luciferase reporter assay showed that miR let-7a mimics could directly target the 3'-untranslated region (UTR) of USP32. Further, MTT assay and colony formation analysis showed that miR let-7a significantly inhibited cell proliferation of MCF-7 cells. However, overexpression of USP32 could reverse the effect of miR let-7a on MCF-7 cells proliferation.

Conclusions

Collectively, the results suggested that miR let-7a functions as a tumor suppressor to reduce proliferation by targeting USP32 in BCa cells.

Let-7 as biomarker, prognostic indicator, and therapy for precision medicine in cancer

Abnormal regulation and expression of microRNAs (miRNAs) has been documented in various diseases including cancer. The miRNA let-7 (MIRLET7) family controls developmental timing and differentiation. Let-7 loss contributes to carcinogenesis via an increase in its target oncogenes and stemness factors. Let-7 targets include genes regulating the cell cycle, cell signaling, and maintenance of differentiation. It is categorized as a tumor suppressor because it reduces cancer aggressiveness, chemoresistance, and radioresistance. However, in rare situations let-7 acts as an oncogene, increasing cancer migration, invasion, chemoresistance, and expression of genes associated with progression and metastasis. Here, we review let-7 function as tumor suppressor and oncogene, considering let-7 as a potential diagnostic and prognostic marker, and a therapeutic target for cancer treatment. We explain the complex regulation and function of different let-7 family members, pointing to abnormal processes involved in carcinogenesis. Let-7 is a promising option to complement conventional cancer therapy, but requires a tumor specific delivery method to avoid toxicity. While let-7 therapy is not yet established, we make the case that assessing its tumor presence is crucial when choosing therapy. Clinical data demonstrate that let-7 can be used as a biomarker for rational precision medicine decisions, resulting in improved patient survival.

LncRNA ANRIL affects the sensitivity of ovarian cancer to cisplatin via regulation of let-7a/HMGA2 axis

This paper tried to explore ANRIL expression in ovarian cancer and how it affects cisplatin-sensitivity of ovarian cancer cells via regulation of let-7a/high-mobility group protein A2 (HMGA2) axis. qRT-PCR was used to detect ANRIL and let-7a levels in ovarian cancer tissues and cell lines (SKOV3 and SKOV3/DDP). Then cells were randomly assigned into Blank, negative control siRNA, ANRIL siRNA, let-7a inhibitor, and ANRIL siRNA+let-7a-inhibitor groups. CCK-8 assay was applied for assessing cell viability of cells treated with different concentrations of cisplatin. Flow cytometry was employed to test cell apoptosis rate. qRT-PCR and Western blot were performed for related molecules detection. Nude mice transplanted with SKOV3/DDP cells were used to confirm the effects of ANRIL siRNA on the cisplatin-sensitivity. Ovarian cancer tissues and cisplatin-resistant cells had increased ANRIL expression and decreased let-7a expression, and those patients with higher clinical stage and pathological grade showed higher ANRIL and lower let-7a. Dual-luciferase reporter-gene assay confirmed the targeting relationship between ANRIL and let-7a, and between let-7a and HMGA2. The cell viability and cisplatin IC50 were decreased in ANRIL siRNA group exposed to different concentrations of cisplatin, with enhanced apoptosis, as well as elevated let-7a and declined HMGA2, which would be reversed by let-7a inhibitor. Meanwhile, ANRIL down-regulation enhanced the inhibitory effect of cisplatin on tumor growth of nude mice and reduced tumor weight. Silencing ANRIL expression reduced HMGA2 expression to promote the apoptosis and improve cisplatin-sensitivity of ovarian cancer cells via up-regulating let-7a expression.

MicroRNA in Ovarian Cancer: Biology, Pathogenesis, and Therapeutic Opportunities

Ovarian cancer comprises one of the three major malignant tumor types in the female reproductive system. The mortality rate of this cancer is the highest among all gynecological tumors, with ovarian cancer metastasis constituting an important cause of death. Therefore, markers for disease prediction and prognosis are highly desirable for early diagnosis as well as for helping optimize and personalize treatment. Recently, microRNAs (miRNAs), which consist of short-sequence RNAs that do not encode a protein, have emerged as new biomarkers in the clinical diagnosis and treatment of ovarian cancer. By pairing with bases specific to the target messenger RNA (mRNA), miRNAs cause degradation of the target mRNA or inhibit its translation, thereby regulating various cellular processes including cell proliferation and adhesion. Increasing numbers of studies have shown that miRNA expression abnormality plays an important role in the development of ovarian cancer. In this review, we discuss the mechanisms of miRNA action, current research regarding their role in the suppression or promotion of ovarian cancer, and their use as markers for diagnosis of prognosis or as therapeutic targets for this disease. Finally, we present future perspectives regarding the clinical management of ovarian cancer and the role for miRNAs therein.

MicroRNA-663 facilitates the growth, migration and invasion of ovarian cancer cell by inhibiting TUSC2

Background

MicroRNAs (miRNAs) have emerged as the critical modulators of the tumorigenesis and tumor progression.

Methods

The levels of miR-663 in ovarian cancer cell lines and clinical tissues were detected using qRT-PCR assays. The Transwell invasion and wound healing assay were conducted to assess the roles of miR-663 in the migration and invasion of ovarian cancer cell in vitro. Rescue assays were carried out to confirm the contribution of tumor suppressor candidate 2 (TUSC2) in the aggressiveness of cancer cell which was regulated by miR-663.

Results

The levels of miR-663 were up-regulated in ovarian cancer tissues in comparison with the corresponding normal tissues. Up-regulation of miR-663 increased the proliferation, colony formation, migration and invasion of ovarian cancer SKOV3 cell. Additional, over-expression of miR-663 increased the tumor growth of SKOV3 in xenograft model. Bioinformatics analysis and luciferase reporter assay identified that miR-663 decreased the level of TUSC2 via binding to the 3′-UTR of TUSC2 gene. Finally, the expression of TUSC2 was inversely associated with the level of miR-663 in ovarian carcinoma tissue and over-expression of TUSC2 inhibited the migration and invasion abilities of SKOV3 that was promoted by miR-663.

Conclusion

Altogether, these results indicate that miR-663 acts as a potential tumor-promoting miRNA through targeting TUSC2 in ovarian cancer.

Electronic supplementary material

The online version of this article (10.1186/s40659-019-0219-6) contains supplementary material, which is available to authorized users.

A four-miRNA signature as a novel biomarker for predicting survival in endometrial cancer

BACKGROUND

The microRNAs (miRNAs) have been validated as prognostic markers in many cancers. The aim of this study was to identify new miRNA prognostic biomarkers in endometrial cancer (EC) and to develop an expression-based miRNA signature to provide survival risk prediction for EC patients.

METHODS

From TCGA database, the miRNA datasets of EC and clinical information were downloaded in April 2018. Using univariate and multivariate Cox regression analyses identify prognostic factors. Using area under the curve (AUC) of receiver operating characteristic (ROC) curve assess the sensitivity and specificity of prognostic model.

RESULTS

530 patients were randomly divided into training set and testing set. Among 561 differentially expressed miRNAs, 4 miRNAs (miR-4758, miR-876, miR-142, miR-190b) were demonstrated to be predictive biomarkers of overall survival (OS) for EC patients in training set. Based on the risk score of 4-miRNA model, patients in the training set were divided into high-risk and low-risk groups with significantly different OS. This 4-miRNA model was validated in testing and entire set. The AUC for the ROC curves in the entire set was 0.704. Meanwhile, multivariate Cox regression combined with other traditional clinical parameters indicated that the 4-miRNA model can be used as an independent OS prognostic factor. Functional enrichment analysis revealed that these miRNAs are involved in biological processes and pathways that are closely related to cancer.

CONCLUSION

A robust 4-miRNA signature as an independent prognostic factor for OS in EC patients was established.

Quantification of distinct let-7 microRNA family members by a modified stem-loop RT-qPCR

Lethal-7 (let-7) microRNA (miRNA) serves a pivotal role in a number of physiological processes and is associated with the occurrence and development of multiple disorders such as cancer. The present study aimed to use a newly developed stem-loop strategy for reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to distinguish let-7 miRNA family members that differ by as little as a single nucleotide. For the miRNAs comprising 16 identical nucleotides at the 5′-end, different stem-loop RT primers were designed and used in RT-qPCR to assess the expression profiles of a panel of let-7 family member miRNAs in human glioblastoma U87 cells. Amplification efficiency was evaluated through correlation analysis between total RNA input and the quantification threshold values. Melting curve profiles were measured to estimate the amplification specificity of the improved stem-loop RT-qPCR compared with those of the poly(A)-tailing method. In addition, the discrimination ability of the modified stem-loop method was examined. Compared with poly(A) tailing, the modified stem-loop RT method was able to specifically reverse transcribe the diverse let-7 miRNA family members followed by accurate quantification, with a theoretical amplification efficiency of ~100%. This modified stem-loop method was able to distinguish miRNAs with a single base difference. This innovative method may be used in the clinical detection of let-7 expression levels in a variety of tumour samples, and may provide valuable data for disease diagnosis and prognostic evaluation. In addition, this method may offer a new avenue for developing particular stem-loop approaches in measuring other miRNAs with little discrepancy.

The Diagnostic and Prognostic Potential of microRNAs in Epithelial Ovarian Carcinoma

Ovarian cancer causes more than 100,000 deaths globally per year. Despite intensive research efforts, there has been little improvement in the overall survival of patients over the past three decades. Most patients are not diagnosed until the cancer is at an advanced stage, by which time their chances of still being alive after 5 years are appallingly low. Attempts to extend life in these patients have been, for the most part, unsuccessful. This owes partly to the lack of suitable biomarkers for stratifying patients at the molecular level, into responders and non-responders. This would lead to more drugs being shown to have a clinical benefit and being approved for use in subgroups of patients. There is also a desperate need for improved biomarkers for earlier detection of ovarian cancer; if the disease is detected sooner there is a significantly improved outlook. In this review, we outline the evidence that microRNAs are deregulated in ovarian cancer, what this can tell us about tumour progression and how it could be used to improve patient stratification in clinical trials. We also describe the potential for circulating microRNAs, both associated with proteins or carried in vesicles, to be used as diagnostics for earlier detection or as biomarkers for informing clinicians on the prognosis and best treatment of ovarian cancer.

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.

Expression of ERCC1, Bcl-2, Lin28a, and Ki-67 as biomarkers of response to first-line platinum-based chemotherapy in patients with high-grade extrapulmonary neuroendocrine carcinomas or small cell lung cancer

Background

Small cell lung cancer (SCLC) and high-grade extrapulmonary neuroendocrine carcinomas (EPNEC) share similar histopathological features and treatment, but outcomes may differ. We evaluated in our study the expression of biomarkers associated with response rate (RR) to chemotherapy and overall survival (OS) for these entities.

Materials and Methods

This is a multicentre retrospective analysis of advanced EPNEC and SCLC patients treated with platinum-based chemotherapy. Paraffin-embedded tumour samples were reviewed by a single pathologist and tested for immunohistochemistry (IHC) expression of Ki-67, ERCC1, Bcl-2, and Lin28a. All images were evaluated by the same radiologist and RR was determined by RECIST 1.1.

Results

From July, 2006 to July, 2014, 142 patients were identified, being 82 (57.7%) SCLC and 60 (42.3%) EPNEC. Clinical characteristics and median Ki-67 (SCLC: 60%; EPNEC: 50%; p = 0.86) were similar between the groups. RR was higher for SCLC patients (86.8% versus 44.6%; p<0.001), but median OS was similar (10.3 months in SCLC and 11.1 months in EPNEC; HR 0.69, p = 0.07). Bcl-2 expression was higher in SCLC patients (46.3% versus 28.3%, p = 0.03) and was associated with worse prognosis in EPNEC (median OS 8.0 months versus 14.7 months; HR 0.47, p = 0.02).

Conclusion

EPNEC patients presented inferior RR to platinum-based chemotherapy than SCLC but tended to live longer. Neither ERCC1, Lin28, or Ki-67 were prognostic or predictive for RR in EPNEC or SCLC. High Bcl-2 expression was associated with poor prognosis in EPNEC patients.

Prediction of therapy response in ovarian cancer: Where are we now?

Therapy resistance is a major challenge in the management of ovarian cancer (OC). Advances in detection and new technology validation have led to the emergence of biomarkers that can predict responses to available therapies. It is important to identify predictive biomarkers to select resistant and sensitive patients in order to reduce important toxicities, to reduce costs and to increase survival. The discovery of predictive and prognostic biomarkers for monitoring therapy is a developing field and provides promising perspectives in the era of personalized medicine. This review article will discuss the biology of OC with a focus on targetable pathways; current therapies; mechanisms of resistance; predictive biomarkers for chemotherapy, antiangiogenic and DNA-targeted therapies, and optimal cytoreductive surgery; and the emergence of liquid biopsy using recent studies from the Medline database and ClinicalTrials.gov.

Interactions between anticancer active platinum complexes and non-coding RNAs/microRNAs

Platinum(II) complexes such as cisplatin, carboplatin and oxaliplatin are clinically approved for the therapy of various solid tumors. Challenging pathogenic properties of cancer cells and the response of cancers towards platinum-based drugs are strongly influenced by non-coding small RNA molecules, the microRNAs (miRNAs). Both increased platinum activity and formation of tumor resistance towards platinum drugs are controlled by miRNAs. This review gives an overview of the interactions between platinum-based drugs and miRNAs, and their influence on platinum activity in various cancer types is discussed.

Differential role of microRNAs in prognosis, diagnosis, and therapy of ovarian cancer

Ovarian cancer (OC) is the most lethal of malignant gynecological cancers, and has a very poor prognosis, frequently, attributable to late diagnosis and responsiveness to chemotherapy. In spite of the technological and medical approaches over the past four decades, involving the progression of several biological markers (mRNA and proteins biomarkers), the mortality rate of OC remains a challenge due to its late diagnosis, which is expressly ascribed to low specificities and sensitivities. Consequently, there is a crucial need for novel diagnostic and prognostic markers that can advance and initiate more individualized treatment, finally increasing survival of the patients. MiRNAs are non-coding RNAs that control target genes post transcriptionally. They are included in tumorigenesis, apoptosis, proliferation, invasion, metastasis, and chemoresistance. Several studies have within the last decade demonstrated that miRNAs are dysregulated in OC and have possibilities as diagnostic and prognostic biomarkers for OC. Additionally; recent studies have also focused on miRNAs as predictors of chemotherapy sensitivities and their potential as therapeutic targets. In this review, we discuss the current data involving the accumulating evidence of the altered expression of miRNAs in OC, their role in diagnosis, prognosis, and forecast of response to therapy. Given the heterogeneity of this disease, it is likely that advances in long-term survival might be also attained by translating the recent insights of miRNAs participation in OC into new targeted therapies that will have a crucial effect on the management of ovarian cancer.

MicroRNA and Long Non-Coding RNA in Ovarian Carcinoma: Translational Insights and Potential Clinical Applications

Reliable biomarkers for the detection of early ovarian carcinoma are currently unavailable. MicroRNA and long non-coding RNA may be important in cancer initiation and progression by regulating gene expression through post-transcriptional mechanisms. MicroRNAs, such as miR-26a and miR-132, have been investigated as novel biomarkers for diagnosis, prognosis, monitoring of therapeutic response, and therapeutic targets in ovarian carcinomas. Some long non-coding RNAs, such as H19 and UCA1, may be involved in the pathogenesis of ovarian carcinomas. MicroRNA and long non-coding RNA have potential clinical utility in the diagnosis of ovarian cancer and predicting prognosis, metastasis, recurrence, and response to therapy.

Current status on microRNAs as biomarkers for ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological malignancy in the Western world, and has a very poor prognosis, often due to late diagnosis and emergence of chemotherapy resistance. Therefore, there is an essential need for new diagnostic and prognostic markers that can improve and initiate more personalized treatment, eventually improving survival of the patients. MicroRNAs are small, non-coding RNA molecules, that post-transcriptionally regulate gene expression. Several studies have within the last decade shown that microRNAs are deregulated in OC and have potential as diagnostic and prognostic biomarkers for OC. Recently studies have also focused on microRNAs as predictors of chemotherapy responses and their potential as therapeutic targets. However, many of the published studies are difficult to interpret as a whole due to various methods of analysis. Future focus should be aimed at developing a general standardized analytical method, which can limit differences between studies thus allowing easier comparison across them. In addition, validation of studies in independent series that ideally should be histotype-specific is essential to determine the clinical role of microRNAs in different types of OC. In this review we summarize the current knowledge of microRNAs as potential biomarkers for OC, with focus on their clinical relevance.

Circulating microRNAs and long non-coding RNAs in gastric cancer diagnosis: An update and review

Gastric cancer (GC) is the fourth most common cancer and the third leading cause of cancer mortality worldwide. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are the most popular non-coding RNAs in cancer research. To date, the roles of miRNAs and lncRNAs have been extensively studied in GC, suggesting that miRNAs and lncRNAs represent a vital component of tumor biology. Furthermore, circulating miRNAs and lncRNAs are found to be dysregulated in patients with GC compared with healthy individuals. Circulating miRNAs and lncRNAs may function as promising biomarkers to improve the early detection of GC. Multiple possibilities for miRNA secretion have been elucidated, including active secretion by microvesicles, exosomes, apoptotic bodies, high-density lipoproteins and protein complexes as well as passive leakage from cells. However, the mechanism underlying lncRNA secretion and the functions of circulating miRNAs and lncRNAs have not been fully illuminated. Concurrently, to standardize results of global investigations of circulating miRNAs and lncRNAs biomarker studies, several recommendations for pre-analytic considerations are put forward. In this review, we summarize the known circulating miRNAs and lncRNAs for GC diagnosis. The possible mechanism of miRNA and lncRNA secretion as well as methodologies for identification of circulating miRNAs and lncRNAs are also discussed. The topics covered here highlight new insights into GC diagnosis and screening.

The effects of lanthanum chloride on proliferation and apoptosis of cervical cancer cells: involvement of let-7a and miR-34a microRNAs

Lanthanide elements have been documented to possess various biologic effects, and their compounds have been studied intensely for their anti-cancer potential. However, the underlying mechanisms remain largely unknown. In the present study, we propose that the levels of proliferation and apoptosis related microRNAs (miRNAs), let-7a and miR-34a, which mediate the apoptosis of cervical cancer cells, can be affected by the lanthanum ion. Our data showed that LaCl3 inhibited the proliferation and induced the apoptosis of cervical cancer cells both in vivo and in vitro by regulating let-7a, miR-34a and their downstream genes. This study provides novel evidence demonstrating that the anticancer mechanism of lanthanum chloride is partially attributed to miRNAs regulation and establishes an experimental basis for the clinical application of lanthanum chloride as an anti-cancer drug.

MDM4 regulation by the let-7 miRNA family in the DNA damage response of glioma cells

Despite extensive investigation into the role of let-7 miRNAs in pathological tumor processes, their involvement in the DNA damage response remains unclear. Here we show that most let-7 family members down-regulate MDM4 expression via binding to MDM4 mRNA at a conserved DNA sequence. Expression of exogenous let-7 miRNA mimics decreased MDM4 protein but not mRNA levels. Several DNA damage reagents increased let-7 expression, thereby decreasing MDM4 protein levels in glioma cells. Inhibition of endogenous let-7 with antisense RNAs rescued MDM4 protein levels with or without MG132, a proteasome-dependent degradation inhibitor. An MDM4 mutation identified in a glioma patient was associated with loss of the putative MDM4 target site. Therefore, let-7 binding to MDM4 is implicated in the DNA damage response.

MicroRNA let-7a modifies the effect of self-renewal gene HIWI on patient survival of epithelial ovarian cancer

Aberrant expressions of self-renewal gene HIWI and microRNA (miRNA) let-7a are observed in epithelial ovarian cancer (EOC). A U-shape association between HIWI expression and overall survival is seen in several human cancers but unknown in EOC. HIWI directly and/or indirectly interacts with let-7a, but the clinical relevance of this interaction is yet to be addressed. Here, we analyzed HIWI and let-7a expressions in 211 primary EOC tissues using quantitative reverse-transcription PCR to investigate HIWI and its interaction with let-7a in the prognostic significance of EOC. Associations of HIWI and its interaction with miRNA let-7a with patient survival were analyzed using the Kaplan-Meier survival curves and Cox proportional hazard regression models. Kaplan-Meier survival curves showed that patients with medium HIWI had poorer overall survival than those with low or high HIWI. An 89% increased death risk (HR = 1.89, 95% CI: 1.29-2.98) was observed in the medium HIWI group in multivariate Cox proportional hazard regression analyses. Among patients with high let-7a expression, those with medium HIWI had an increased risk of death compared to those with low HIWI (HR = 2.62, 95% CI: 1.30-5.30), whereas among those with low let-7a, no significant association between HIWI expression and overall survival was observed (HR = 1.63, 95% CI: 0.86-3.08). Moreover, HIWI expression also affected chemotherapy response. The results suggested that miRNA let-7a could modify the effect of HIWI expression on patient survival of EOC, expanding our understanding of the clinical relevance of HIWI and let-7a interaction in EOC prognosis. © 2015 Wiley Periodicals, Inc.

Role of microRNAs in cancers of the female reproductive tract: insights from recent clinical and experimental discovery studies

microRNAs (miRNAs) are small RNA molecules that represent the top of the pyramid of many tumorigenesis cascade pathways as they have the ability to affect multiple, intricate, and still undiscovered downstream targets. Understanding how miRNA molecules serve as master regulators in these important networks involved in cancer initiation and progression open up significant innovative areas for therapy and diagnosis that have been sadly lacking for deadly female reproductive tract cancers. This review will highlight the recent advances in the field of miRNAs in epithelial ovarian cancer, endometrioid endometrial cancer and squamous-cell cervical carcinoma focusing on studies associated with actual clinical information in humans. Importantly, recent miRNA profiling studies have included well-characterized clinical specimens of female reproductive tract cancers, allowing for studies correlating miRNA expression with clinical outcomes. This review will summarize the current thoughts on the role of miRNA processing in unique miRNA species present in these cancers. In addition, this review will focus on current data regarding miRNA molecules as unique biomarkers associated with clinically significant outcomes such as overall survival and chemotherapy resistance. We will also discuss why specific miRNA molecules are not recapitulated across multiple studies of the same cancer type. Although the mechanistic contributions of miRNA molecules to these clinical phenomena have been confirmed using in vitro and pre-clinical mouse model systems, these studies are truly only the beginning of our understanding of the roles miRNAs play in cancers of the female reproductive tract. This review will also highlight useful areas for future research regarding miRNAs as therapeutic targets in cancers of the female reproductive tract.

The mystery of let-7d - a small RNA with great power

miRNAs belong to a class of small non-coding RNAs which can modulate gene expression. Disturbances in their expression and function may cause cancer formation, progression and cell response to various types of stress. The let-7 family is one of the most studied groups of miRNAs. The family contains 13 members with similar sequences and a wide spectrum of target genes. In this paper, we mostly focus on one member of the family – let-7d. This miRNA is dysregulated in many types of cancers. It can be over- or down-expressed, and it acts as a tumor suppressor or oncogene. It regulates various genes such as LIN28, C-MYC, K-RAS, HMGA2 and IMP-1. Moreover, let-7d has a significant impact on epithelial-to-mesenchymal transition (EMT) and formation of cancer initiating cells which are resistant to irradiation and chemical exposure and responsible for cancer metastasis. Let-7d can serve as a prognostic and predictive marker for personalization of the treatment. Let-7d is a small RNA with great power, but in different cell genetic backgrounds it acts in different ways, which makes this molecule still mysterious.

Effects of HMGA2 on malignant degree, invasion, metastasis, proliferation and cellular morphology of ovarian cancer cells

OBJECTIVE

To analyze effects of high mobility group AT-hook 2 (HMGA2) on malignant degree, invasion, metastasis, proliferation and cellular morphology of ovarian cancer cells.

METHODS

Three methods were applied to observe the effect on HMGA2 expression in ovarian cancer cells and ovarian epithelial cells.

RESULTS

After the application of siRNA-HMGA2, number of T29A2-cell clones was decreased, there was significant difference compared with the negative control Block-iT. After application of let-7c, number of T29A2+ cell clones was decreased significantly, however, after the application of Anti-let-7, the number of clones restored, and there was no significant difference compared with the negative control group. After interference, the number of T29A2- cells which passed through Matrigel polycarbonate membrane were significantly lower than the negative control group. After the treatment of siRNA-HMGA2, let-7c and sh-HMGA2 respectively, growth and proliferation of T29A2-, T29A2+ and SKOV3 were slower, and the phenomenon was most obvious in SKOV3. Stable interference of HMGA2 induced mesenchymal-epithelial changes in the morphology of SKOV3-sh-HMGA2.

CONCLUSIONS

HMGA2 can promote malignant transformation of ovarian cancer cells, enhance cell invasion and metastasis, and promote cell growth and proliferation of ovarian cancer cells, which can cause ovarian cancer to progress rapidly and affect the quality of life.

MicroRNAs as prognostic markers in ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological malignancy among women. Over 70% of women with OC are diagnosed in advanced stages and most of these cases are incurable. Although most patients respond well to primary chemotherapy, tumors become resistant to treatment. Mechanisms of chemoresistance in cancer cells may be associated with mutational events and/or alterations of gene expression through epigenetic events. Although focusing on known genes has already yielded new information, previously unknown non-coding RNAs, such as microRNAs (miRNAs), also lead insight into the biology of chemoresistance. In this review we summarize the current evidence examining the role of miRNAs as biomarkers of response and survival to therapy in OC. Beside their clinical implications, we also discuss important differences between studies that may have limited their use as clinical biomarkers and suggest new approaches.

Application of microRNA in diagnosis and treatment of ovarian cancer

Ovarian cancer has a poor prognosis because early detection is difficult and recurrent ovarian cancer is usually drug-resistant. The morbidity and mortality of ovarian cancer are high worldwide and new methods of diagnosis and therapy are needed. MicroRNAs (miRNAs) are posttranscriptional regulators of gene expression that are involved in carcinogenesis, metastasis, and invasion. Thus, miRNAs are likely to be useful as diagnostic and prognostic biomarkers and for cancer therapy. Many miRNAs have altered expression in ovarian cancer compared to normal ovarian tissues and these changes may be useful for diagnosis and treatment. For example, deficiencies of enzymes including Dicer and Drosha that are required for miRNA biogenesis may be adverse prognostic factors; miRNAs such as miR-214 and miR-31, which are involved in drug resistance, and the miR-200 family, which is implicated in metastasis, may serve as biomarkers; and transfection of downregulated miRNAs and inhibition of upregulated miRNAs may be effective for treatment of ovarian cancer. Chemotherapy targeting epigenetic mechanisms associated with miRNAs may also be effective to reverse gene silencing.

Molecular epigenetics in the management of ovarian cancer: are we investigating a rational clinical promise?

Epigenetics is essentially a phenotypical change in gene expression without any alteration of the DNA sequence; the emergence of epigenetics in cancer research and mainstream oncology is fueling new hope. However, it is not yet known whether this knowledge will translate to improved clinical management of ovarian cancer. In this malignancy, women are still undergoing chemotherapy similar to what was approved in 1978, which to this day represents one of the biggest breakthroughs for treating ovarian cancer. Although liquid tumors are benefiting from epigenetically related therapies, solid tumors like ovarian cancer are not (yet?). Herein, we will review the science of molecular epigenetics, especially DNA methylation, histone modifications and microRNA, but also include transcription factors since they, too, are important in ovarian cancer. Pre-clinical and clinical research on the role of epigenetic modifications is also summarized. Unfortunately, ovarian cancer remains an idiopathic disease, for the most part, and there are many areas of patient management, which could benefit from improved technology. This review will also highlight the evidence suggesting that epigenetics may have pre-clinical utility in pharmacology and clinical applications for prognosis and diagnosis. Finally, drugs currently in clinical trials (i.e., histone deacetylase inhibitors) are discussed along with the promise for epigenetics in the exploitation of chemoresistance. Whether epigenetics will ultimately be the answer to better management in ovarian cancer is currently unknown; but we hope so in the future.