MiR-489 modulates cisplatin resistance in human ovarian cancer cells by targeting Akt3

The Multifunctional Nature of the MicroRNA/AKT3 Regulatory Axis in Human Cancers

Serine/threonine kinase (AKT) signaling regulates diverse cellular processes and is one of the most important aberrant cell survival mechanisms associated with tumorigenesis, metastasis, and chemoresistance. Targeting AKT has become an effective therapeutic strategy for the treatment of many cancers. AKT3 (PKBγ), the least studied isoform of the AKT family, has emerged as a major contributor to malignancy. AKT3 is frequently overexpressed in human cancers, and many regulatory oncogenic or tumor suppressor small non-coding RNAs (ncRNAs), including microRNAs (miRNAs), have recently been identified to be involved in regulating AKT3 expression. Therefore, a better understanding of regulatory miRNA/AKT3 networks may reveal novel biomarkers for the diagnosis of patients with cancer and may provide invaluable information for developing more effective therapeutic strategies. The aim of this review was to summarize current research progress in the isoform-specific functions of AKT3 in human cancers and the roles of dysregulated miRNA/AKT3 in specific types of human cancers.

MicroRNAs, long non-coding RNAs, and circular RNAs and gynecological cancers: focus on metastasis

Gynecologic cancer is a significant cause of death in women worldwide, with cervical cancer, ovarian cancer, and endometrial cancer being among the most well-known types. The initiation and progression of gynecologic cancers involve a variety of biological functions, including angiogenesis and metastasis-given that death mostly occurs from metastatic tumors that have invaded the surrounding tissues. Therefore, understanding the molecular pathways underlying gynecologic cancer metastasis is critical for enhancing patient survival and outcomes. Recent research has revealed the contribution of numerous non-coding RNAs (ncRNAs) to metastasis and invasion of gynecologic cancer by affecting specific cellular pathways. This review focuses on three types of gynecologic cancer (ovarian, endometrial, and cervical) and three kinds of ncRNAs (long non-coding RNAs, microRNAs, and circular RNAs). We summarize the detailed role of non-coding RNAs in the different pathways and molecular interactions involved in the invasion and metastasis of these cancers.

Double-edged sword role of miRNA-633 and miRNA-181 in human cancers

Understanding the function and mode of operation of microRNAs (miRNAs) in cancer is of growing interest. The short non-coding RNAs known as miRNAs, which target mRNA in multicellular organisms, are described as controlling essential cellular processes. The miR-181 family and miR-633 are well-known miRNAs that play a key role in the development and metastasis of tumor cells. They may facilitate either tumor-suppressive or oncogenic function in malignant cells, according to mounting evidence. Metastatic cells that are closely linked to cancer cell migration, invasion, and angiogenesis can be identified by abnormal levels of miR-181 and miR-633. Numerous studies have demonstrated their capacity to control drug resistance, cell growth, apoptosis, and the epithelial-mesenchymal transition (EMT) and metastasis process. Interestingly, the levels of miR-181 and miR-633 and their potential target genes in the basic cellular process can vary depending on the type of cancer cells and their gene expression profile. Such miRNAs' interactions with other non-coding RNAs such as long non-coding RNAs and circular RNAs can influence tumor behaviors. Herein, we concentrated on the multifaceted roles of miR-181 and miR-633 and potential targets in human tumorigenesis, ranging from cell growth and metastasis to drug resistance.

Research progress on anti-ovarian cancer mechanism of miRNA regulating tumor microenvironment

Ovarian cancer is the most deadly malignancy among women, but its complex pathogenesis is unknown. Most patients with ovarian cancer have a poor prognosis due to high recurrence rates and chemotherapy resistance as well as the lack of effective early diagnostic methods. The tumor microenvironment mainly includes extracellular matrix, CAFs, tumor angiogenesis and immune-associated cells. The interaction between tumor cells and TME plays a key role in tumorigenesis, progression, metastasis and treatment, affecting tumor progression. Therefore, it is significant to find new tumor biomarkers and therapeutic targets. MicroRNAs are non-coding RNAs that post-transcriptionally regulate the expression of target genes and affect a variety of biological processes. Studies have shown that miRNAs regulate tumor development by affecting TME. In this review, we summarize the mechanisms by which miRNAs affect ovarian cancer by regulating TME and highlight the key role of miRNAs in TME, which provides new targets and theoretical basis for ovarian cancer treatment.

6 ′ -O-Galloylpaeoniflorin Exerts Inhibitory Bioactivities in Human Neuroblastoma Cells via Modulating AMPK/miR-489/XIAP Pathway

Although therapies against neuroblastoma (NBM) have advanced, the patients still suffer from poor prognoses due to distal metastasis or the occurrence of multidrug resistance. Accumulating evidence has proved that chemicals derived from natural products possess potent anti-NBM properties or can be used as adjuvants for chemotherapy. In the present study, we demonstrated that 6′-O-galloylpaeoniflorin (GPF), a galloylated derivative of paeoniflorin isolated from the roots of Paeonia lactiflora Pall, exerted significant inhibitory effects on proliferation and invasion of SH-SY5Y cells (an NBM cell line) and enhanced the sensitivity of SH-SY5Y cells to cisplatin in vitro. Further studies showed that GPF treatment upregulated miR-489 in NBM cells via activating AMP-activated protein kinase (AMPK). We also demonstrated that similar to GPF treatment, miR-489 exhibited a significant anti-NBM capacity. Further studies showed that miR-489 directly targeted the X-linked inhibitor of apoptosis protein (XIAP). Overall, our results indicated that GPF possessed an evident anti-NBM capacity dependent on AMPK/miR-489/XIAP pathway, providing an emerging strategy for clinical treatment of NBM.

MicroRNA and Alternative mRNA Splicing Events in Cancer Drug Response/Resistance: Potent Therapeutic Targets

Cancer is a multifaceted disease that involves several molecular mechanisms including changes in gene expression. Two important processes altered in cancer that lead to changes in gene expression include altered microRNA (miRNA) expression and aberrant splicing events. MiRNAs are short non-coding RNAs that play a central role in regulating RNA silencing and gene expression. Alternative splicing increases the diversity of the proteome by producing several different spliced mRNAs from a single gene for translation. MiRNA expression and alternative splicing events are rigorously regulated processes. Dysregulation of miRNA and splicing events promote carcinogenesis and drug resistance in cancers including breast, cervical, prostate, colorectal, ovarian and leukemia. Alternative splicing may change the target mRNA 3'UTR binding site. This alteration can affect the produced protein and may ultimately affect the drug affinity of target proteins, eventually leading to drug resistance. Drug resistance can be caused by intrinsic and extrinsic factors. The interplay between miRNA and alternative splicing is largely due to splicing resulting in altered 3'UTR targeted binding of miRNAs. This can result in the altered targeting of these isoforms and altered drug targets and drug resistance. Furthermore, the increasing prevalence of cancer drug resistance poses a substantial challenge in the management of the disease. Henceforth, molecular alterations have become highly attractive drug targets to reverse the aberrant effects of miRNAs and splicing events that promote malignancy and drug resistance. While the miRNA-mRNA splicing interplay in cancer drug resistance remains largely to be elucidated, this review focuses on miRNA and alternative mRNA splicing (AS) events in breast, cervical, prostate, colorectal and ovarian cancer, as well as leukemia, and the role these events play in drug resistance. MiRNA induced cancer drug resistance; alternative mRNA splicing (AS) in cancer drug resistance; the interplay between AS and miRNA in chemoresistance will be discussed. Despite this great potential, the interplay between aberrant splicing events and miRNA is understudied but holds great potential in deciphering miRNA-mediated drug resistance.

Revealing the role of miRNA-489 as a new onco-suppressor factor in different cancers based on pre-clinical and clinical evidence

Recently, microRNAs (miRNAs) have shown to be potential therapeutic, diagnostic and prognostic targets in disease therapy. These endogenous non-coding RNAs contribute to regulation of different cellular events that are necessary for maintaining physiological condition. Dysregulation of miRNAs is correlated with development of various pathological events such as neurological disorders, cardiovascular diseases, and cancer. miRNA-489 is a new emerging miRNA and studies are extensively investigating its role in pathological conditions. Herein, potential function of miRNA-489 as tumor-suppressor in various cancers is described. miRNA-489 is able to sensitize cancer cells into chemotherapy by disrupting molecular pathways involved in cancer growth such as PI3K/Akt, and induction of apoptosis. The PROX1 and SUZ12 as oncogenic pathways, are affected by miRNA-489 in suppressing metastasis of cancer cells. Wnt/β-catenin as an oncogenic factor ensuring growth and malignancy of tumors is inhibited via miRNA-489 function. For enhancing drug sensitivity of tumors, restoring miRNA-489 expression is a promising strategy. The lncRNAs can modulate miRNA-489 expression in tumors and studies about circRNA role in miRNA-489 modulation should be performed. The expression level of miRNA-489 is a diagnostic tool for tumor detection. Besides, down-regulation of miRNA-489 in tumors provides unfavorable prognosis.

Non-coding RNAs related to angiogenesis in gynecological cancer

Gynecological cancer affects the female reproductive system, including ovarian, uterine, endometrial, cervical, vulvar, and vaginal tumors. Non-coding RNAs (ncRNAs), and in particular microRNAs, function as regulatory molecules, which can control gene expression in a post-transcriptional manner. Normal physiological processes like cellular proliferation, differentiation, and apoptosis, and pathological processes such as oncogenesis and metastasis are regulated by microRNAs. Numerous reports have shown a direct role of microRNAs in the modulation of angiogenesis in gynecological cancer, via targeting pro-angiogenic factors and signaling pathways. Understanding the molecular mechanism involved in the regulation of angiogenesis by microRNAs may lead to new treatment options. Recently the regulatory role of some long non-coding RNAs in gynecological cancer has also been explored, but the information on this function is more limited. The aim of this article is to explore the pathways responsible for angiogenesis, and to what extent ncRNAs may be employed as biomarkers or therapeutic targets in gynecological cancer.

Flavonoid display ability to target microRNAs in cancer pathogenesis

MicroRNAs (miRNAs) are non-coding, conserved, single-stranded nucleotide sequences involved in physiological and developmental processes. Recent evidence suggests an association between miRNAs' deregulation with initiation, promotion, progression, and drug resistance in cancer cells. Besides, miRNAs are known to regulate the epithelial-mesenchymal transition, angiogenesis, autophagy, and senescence in different cancer types. Previous reports proposed that apart from the antioxidant potential, flavonoids play an essential role in miRNAs modulation associated with changes in cancer-related proteins, tumor suppressor genes, and oncogenes. Thus, flavonoids can suppress proliferation, help in the development of drug sensitivity, suppress metastasis and angiogenesis by modulating miRNAs expression. In the present review, we summarize the role of miRNAs in cancer, drug resistance, and the chemopreventive potential of flavonoids mediated by miRNAs. The potential of flavonoids to modulate miRNAs expression in different cancer types demonstrate their selectivity and importance as regulators of carcinogenesis. Flavonoids as chemopreventive agents targeting miRNAs are extensively studied in vitro, in vivo, and pre-clinical studies, but their efficiency in targeting miRNAs in clinical studies is less investigated. The evidence presented in this review highlights the potential of flavonoids in cancer prevention/treatment by regulating miRNAs, although further investigations are required to validate and establish their clinical usefulness.

miR-489-3p inhibits proliferation and migration of bladder cancer cells through downregulation of histone deacetylase 2

Since human bladder cancer (BC) is a common malignancy of the urinary system with poor prognosis, it is crucial to clarify the molecular mechanisms of BC development and progression. To the best of our knowledge, the current study demonstrated for the first time that miR-489-3p suppressed BC cell-derived tumor growth in vivo via the downregulation of histone deacetylase 2 (HDAC2). According to the results, expression levels of miR-489-3p were lower in BC tissues compared with corresponding normal tissues. Expression of miR-489-3p mimics in BC-derived T24 and 5637 cells resulted in a significant reduction in proliferation and migration rates. Furthermore, bioinformatics analyses indicated that HDAC2 may be a potential downstream target of miR-489-3p. In contrast to miR-489-3p, HDAC2 was expressed at higher levels in BC tissues compared with corresponding normal tissues. Additionally, small interfering RNA-mediated knockdown of HDAC2 caused a marked decrease in the proliferation and migration rates of T24 and 5637 cells. Consistent with these observations, expression of miR-489-3p mimics attenuated the growth of xenograft tumors arising from T24 cells and resulted in HDAC2 downregulation. In conclusion, the results of the current study indicated that the miR-489-3p/HDAC2 axis serves a role in the development and/or the progression of BC and may be a potential molecular target for the development of a novel strategy to treat patients with BC.

LncRNA SNHG1 contributes to the regulation of acute myeloid leukemia cell growth by modulating miR-489-3p/SOX12/Wnt/β-catenin signaling

The long noncoding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) is a critical regulator for the development and progression of multiple tumors. Yet, the role of SNHG1 in acute myeloid leukemia (AML) is unknown. The present study demonstrated that SNHG1 expression was upregulated in AML. SNHG1 silencing markedly repressed AML cell growth, whereas SNHG1 overexpression had the opposite effect. MicroRNA-489-3p (miR-489-3p) was identified as a SNHG1-targeting miRNA. SNHG1 knockdown increased miR-489-3p expression. Low expression of miR-489-3p was correlated with high expression of SNHG1 in AML tissues. miR-489-3p overexpression restricted AML cell growth, and SRY-related high-mobility-group box 12 (SOX12) was identified as a miR-489-3p-targeting gene. SNHG1 inhibition or miR-489-3p overexpression inactivated Wnt/β-catenin signaling through downregulation of SOX12. SOX12 overexpression partially reversed the SNHG1 knockdown- or miR-489-3p overexpression-mediated effects. Taken together, these data indicate that suppression of SNHG1 downregulates AML cell growth by inactivating SOX12/Wnt/β-catenin signaling via upregulating miR-489-3p.

miRNA profile in ovarian cancer

Ovarian cancer is a gynecological cancer with high mortality and a heterogeneous nature which complicates its early detection and primary prevention. Numerous studies have evaluated expression profile microRNAs (miRNAs) in tissue and serum samples of ovarian cancer patients to find appropriate biomarkers for this malignancy. Functional experiments also verified the oncogenic or suppressor effects of a number of miRNAs. miRNAs exert their role through degradation or inhibition of translation of the target mRNA. Through this regulatory function, they modulate numerous cellular processes which are ultimately associated with carcinogenesis. A number of miRNAs including miR-135a-3p, miR-200c, miR-216a and miR-340 regulate epithelial-mesenchymal transition program thus modulate invasiveness of ovarian cancer cell. Others have been shown to regulate some fundamental pathways in carcinogenesis such as mTOR and PI3K/AKT pathways. Such vast area of function of miRNAs in ovarian cancer has suggested them as putative therapeutic options for future years. In this review, we summarize the recent findings regarding the role of miRNAs in ovarian cancer pathogenesis, their application as biomarkers and the future perspectives of this research area.

miR-29c-3p inhibits autophagy and cisplatin resistance in ovarian cancer by regulating FOXP1/ATG14 pathway

Autophagy, characterized by the elevator of autophagy-related gene 14 (ATG14) and the dysregulation of autophagy-related proteins, contributes to the cisplatin (DDP) resistance in ovarian cancer. Forkhead box protein P1 (FOXP1), which is a well-defined transcription factor, is reported to have the oncogenic effect on ovarian cancer. This study aims to identify the effect of miR-29c-3p/FOXP1/ATG14 pathway in regulating autophagy and DDP resistance in ovarian cancer. The expressions of miR-29c-3p, FOXP1, ATG14 and autophagy-related proteins were detected in DDP-sensitive ovarian cancer cell lines (SKOV3 and A2780) and DDP-resistant cell lines (SKOV3/DDP and A2780/DDP). Cell viability was detected using the MTT assay. The therapeutic effect of miR-29c-3p overexpression was observed in the xenograft model of nude mice.Compared with DDP-sensitive cells, miR-29c-3p was decreased in DDP-resistant cells, and an enhancement of FOXP1, ATG14, autophagy, and drug resistance was shown in DDP-resistant cells. The anti-resistant effect of miR-29c-3p was observed as overexpressing miR-29c-3p inhibited cell viability of DDP-resistant cells. Moreover, FOXP1 was a target of miR-29c-3p, which was confirmed by the luciferase reporter assay, and ATG14 was transactivated by FOXP1, which was confirmed by the ChIP assay. Overexpression of miR-29c-3p increased DDP sensitivity by downregulating FOXP1/ATG14 in vitro. The tumor volume was reduced after the injection of miR-29c-3p-overexpressing SKOV3/DDP cells in vivo. Overexpression of miR-29c-3p inhibited autophagy and DDP resistance partly via downregulating FOXP1/ATG14 pathway, suggesting miR-29c-3p as a novel target in overcoming DDP resistance in ovarian cancer.

Transcriptome profiling of cervical cancer cells acquired resistance to cisplatin by deep sequencing

Cervical cancer is one of the most fatal malignancies in females. Acquired resistance to chemotherapeutic agent is one reason behind this lethality. In this study, we developed cisplatin resistance cell line, subsequently examined the molecular mechanisms linked. Transcriptome sequencing technology was utilized to compare the various expression models between the cisplatin-resistant cell line (Hela/DDP) and its parental cell line human cervical adenocarcinoma Hela. The present study has identified 2,312 differentially expressed genes (DEGs). Results showed there were 1,437 up-regulated genes and 875 down-regulated ones. Databases analysis including Gene ontology (GO), Cluster of Orthologous Groups of proteins (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were performed to reveal potential molecular mechanisms. We studied AKT3, a crucial gene in the PI3K/AKT pathway which clustered the most DEGs. Silencing AKT3 in Hela/DDP could enhance its sensibility to cisplatin. Quantitative real-time reverse transcription PCR (qRT-PCR) and western blot experiments were showed that expression of AKT3 was decreased after siRNA interference and inhibitor treatment. CCK-8 experiments showed that low expression of Akt3/pAkt enhanced the sensitivity of drug-resistant cells to cisplatin. Apoptotic analysis demonstrated that inhibition of AKT3 increased the rate of Hela/DDP apoptosis. Our results suggest a novel mechanism by which upregulated expression of AKT3 in cervical cancer may lead to resistance to cisplatin.

miR‑489 promotes apoptosis and inhibits invasiveness of glioma cells by targeting PAK5/RAF1 signaling pathways

Glioma patients receiving therapy are at a high risk of relapse and rapid progression and, thus, more effective treatments are required. The aim of the present study was to determine the suppressive role of miR-489 as an alternative therapeutic target for preventing glioma progression. The results of the present study demonstrated that patients with relatively lower levels of expression of miR-489 had more favorable clinical outcomes. Furthermore, miR-489 expression was inversely correlated with p21-activated kinase 5 (PAK5) mRNA expression levels in glioma specimens. A dual luciferase reporter assay revealed that miR-489 suppressed PAK5 expression by directly targeting the PAK5 3′-untranslated region. The effects of miR-489 on cell viability were measured using MTT and Cell Counting Kit-8 assays. The results demonstrated that ectopic expression of miR-489 mimic decreased cell viability by interfering with cyclin D1 and c-Myc signaling. Additionally, the effect of miR-489 on apoptosis was determined using Hoechst 33258 staining and flow cytometry. The results demonstrated that miR-489 decreased the activity of RAF1, reduced Bcl-2 and promoted Bax expression, resulting in increased cell apoptosis. Furthermore, the effect of miR-489 mimic on cellular motility was assessed using migration and invasion assays. miR-489 was shown to abolish the PAK5/RAF1/MMP2 pathway, resulting in decreased cell invasion ability. These results indicated that miR-489 may be involved in PAK5-mediated regulation of glioma progression, demonstrating the potential therapeutic benefits of targeting miR-489 in glioma.

miR-489-3p Regulates the Oxidative Stress Response in the Liver and Gill Tissues of Hybrid Yellow Catfish (Pelteobagrus fulvidraco♀ × P. vachelli♂) Under Cu2+ Exposure by Targeting Cu/Zn-SOD

Copper/zinc superoxide dismutase (Cu/Zn-SOD) plays critical roles in protecting cells and tissues against oxidative damage. Excessive copper ions (Cu2+) in water can damage the cells of aquatic organisms, leading to impaired growth and development and reduced antioxidant defenses. Many regulatory factors control the response to excess Cu2+. Among them, microRNAs (miRNAs) are important small RNAs that regulate the expression of their target genes and participate in the oxidative stress response. In the present study, we used bioinformatics and dual luciferase reporter gene analyses to demonstrate that the miR-489-3p of hybrid yellow catfish (Pelteobagrus fulvidraco♀ × P. vachelli♂) binds to the 3'-untranslated region (UTR) of its target gene, which encodes a Cu/Zn-SOD. The regulatory relationship between this miRNA and its target gene Cu/Zn-SOD was analyzed using qRT-PCR and luciferase activity assays. We also investigated the effect of the loss of miR-489-3p expression on the oxidative stress response of hybrid yellow catfish exposed to Cu2+. The Cu/Zn-SOD 3'UTR region was found to be fully complementary to positions 2-9 of the 5'-end seed region of miR-489-3p. The miR-489-3p expression levels were negatively related to Cu/Zn-SOD expression. Silencing of miR-489-3p up-regulated Cu/Zn-SOD expression in the liver and gill tissues, increased activities of SOD and catalase, and reduced the malondialdehyde content. This study is the first to demonstrate that miR-489-3p targets Cu/Zn-SOD to mediate the oxidative response to metal stress. These findings provide a theoretical basis for further studies on the response to oxidative stress caused by metals in cultured fish, and provide an experimental basis for the management of the culture environment.

Overexpression of microRNA-195-5p reduces cisplatin resistance and angiogenesis in ovarian cancer by inhibiting the PSAT1-dependent GSK3β/β-catenin signaling pathway

Background

Ovarian cancer (OC) is one of the leading causes for cancer-related deaths among women. MicroRNAs (miRs) have been proved to be vital to the development and progression of OC. Hence, the study aims to evaluate the ability of miR-195-5p affecting cisplatin (DDP) resistance and angiogenesis in OC and the underlying mechanism.

Methods

MiRs that could target phosphoserine aminotransferase 1 (PSAT1), a differentially expressed gene in OC, were predicted by miRNA-mRNA prediction websites. The expression patterns of miR-195-5p in the OC tissues and cells were determined using RNA quantification assay. The role of miR-195-5p in OC was evaluated by determining DDP resistance, apoptosis and angiogenesis of OC cells after up-regulating or down-regulating miR-195-5p or PSAT1, or blocking the glycogen synthase kinase-3β (GSK3β)/β-catenin signaling pathway. Animal experiment was conducted to explore the effect of miR-195-5p on resistance to DDP and angiogenesis.

Result

MiR-195-5p directly targeted PSAT1 and down-regulated its expression. The expression of miR-195-5p was lower while that of PSAT1 was higher in OC tissues than in adjacent normal tissues. When miR-195-5p was over-expressed or PSAT1 was silenced, the expression of HIF-1α, VEGF, PSAT1, β-catenin as well as the extent of GSK3β phosphorylation was reduced, the angiogenesis and resistance to DDP was diminished and apoptosis was promoted both in vitro and in vivo. The inhibition of GSK3β/β-catenin signaling pathway was involved in the regulation process.

Conclusion

Over-expression of miR-195-5p reduced angiogenesis and DDP resistance in OC, which provides a potential therapeutic target for the treatment of OC.

The role and mechanisms of action of microRNAs in cancer drug resistance

MicroRNAs (miRNAs) are small non-coding RNAs with a length of about 19–25 nt, which can regulate various target genes and are thus involved in the regulation of a variety of biological and pathological processes, including the formation and development of cancer. Drug resistance in cancer chemotherapy is one of the main obstacles to curing this malignant disease. Statistical data indicate that over 90% of the mortality of patients with cancer is related to drug resistance. Drug resistance of cancer chemotherapy can be caused by many mechanisms, such as decreased antitumor drug uptake, modified drug targets, altered cell cycle checkpoints, or increased DNA damage repair, among others. In recent years, many studies have shown that miRNAs are involved in the drug resistance of tumor cells by targeting drug-resistance-related genes or influencing genes related to cell proliferation, cell cycle, and apoptosis. A single miRNA often targets a number of genes, and its regulatory effect is tissue-specific. In this review, we emphasize the miRNAs that are involved in the regulation of drug resistance among different cancers and probe the mechanisms of the deregulated expression of miRNAs. The molecular targets of miRNAs and their underlying signaling pathways are also explored comprehensively. A holistic understanding of the functions of miRNAs in drug resistance will help us develop better strategies to regulate them efficiently and will finally pave the way toward better translation of miRNAs into clinics, developing them into a promising approach in cancer therapy.

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.

miR‑381 and miR‑489 suppress cell proliferation and invasion by targeting CUL4B via the Wnt/β‑catenin pathway in gastric cancer

Accumulating evidence has highlighted the critical role of cullin 4B (CUL4B) in driving tumourigenesis in several malignancies, including gastric cancer (GC); however, the mechanisms underlying CUL4B upregulation remain unclear. The dysregulation of microRNAs (miRNAs or miRs) is known to be involved in tumourigenesis. In this study, we report that the expression of miR‑381 and miR‑489 is downregulated and is negatively correlated with that of CUL4B in GC tissues and cell lines. Further analysis verified that miR‑381 and miR‑489 directly targeted CUL4B. CUL4B silencing inhibited cell proliferation, migration and invasion by inactivating the Wnt/β‑catenin pathway. miR‑381/miR‑489 overexpression recapitulated the effects of CUL4B silencing, while CUL4B restoration negated the suppressive effects induced by the ectopic expression of miR‑381/miR‑489. Furthermore, miR‑381/miR‑489 exerted tumour suppressive functions by inactivating the Wnt/β‑catenin pathway through the targeting of CUL4B. Taken together, the findings of this study suggest that the miR‑381/miR‑489‑mediated expression of CUL4B modulates the proliferation and invasion of GC cells via the Wnt/β‑catenin pathway, which indicates that the miR‑381/miR‑489‑CUL4B axis is critical in the control of GC tumourigenesis.

Autophagy, Cell Viability, and Chemoresistance Are Regulated By miR-489 in Breast Cancer

It is postulated that the complexity and heterogeneity in cancer may hinder most efforts that target a single pathway. Thus, discovery of novel therapeutic agents targeting multiple pathways, such as miRNAs, holds promise for future cancer therapy. One such miRNA, miR-489, is downregulated in a majority of breast cancer cells and several drug-resistant breast cancer cell lines, but its role and underlying mechanism for tumor suppression and drug resistance needs further investigation. The current study identifies autophagy as a novel pathway targeted by miR-489 and reports Unc-51 like autophagy activating kinase 1 (ULK1) and lysosomal protein transmembrane 4 beta (LAPTM4B) to be direct targets of miR-489. Furthermore, the data demonstrate autophagy inhibition and LAPTM4B downregulation as a major mechanism responsible for miR-489-mediated doxorubicin sensitization. Finally, miR-489 and LAPTM4B levels were inversely correlated in human tumor clinical specimens, and more importantly, miR-489 expression levels predict overall survival in patients with 8q22 amplification (the region in which LAPTM4B resides).Implications: These findings expand the understanding of miR-489-mediated tumor suppression and chemosensitization in and suggest a strategy for using miR-489 as a therapeutic sensitizer in a defined subgroup of resistant breast cancer patients. Mol Cancer Res; 16(9); 1348-60. ©2018 AACR.

LncRNA CHRF-induced miR-489 loss promotes metastasis of colorectal cancer via TWIST1/EMT signaling pathway

microRNA-489 (miR-489) is a novel cancer-related miRNAs and functions as a tumor suppressor in human cancers. While, the clinical significance of miR-489 and its role in colorectal cancer (CRC) remain rarely known. Here, we found that the levels of miR-489 in CRC tissues were significantly lower than those in matched tumor-adjacent tissues. Furthermore, decreased levels of miR-489 also observed in CRC cell lines compared to HIEC cells. Clinicopathological analysis revealed that miR-489 underexpression was positively correlated with advanced pT stage, pN stage and AJCC stage. Moreover, miR-489 low expressing CRC patients showed a obvious shorter survival. Functionally, miR-489 restoration inhibited cell migration and invasion as well as epithelial-mesenchymal transition (EMT) in HCT116 cells, while miR-489 loss facilitated these cellular processes in SW480 cells. In vivo experiments revealed that miR-489 overexpression reduced the number of metastatic nodules in nude mice liver. Notably, TWIST1 was recognized as a direct downstream target of miR-489 in CRC cells. Interestingly, TWIST1 restoration abrogated the effects of miR-489 on CRC cells with enhanced cell migration, invasion and EMT process. Furthermore, overexpression of long noncoding RNA cardiac hypertrophy-related factor (lncRNA CHRF) was inversely correlated with miR-489 expression in CRC tissues. CHRF knockdown increased the expression of miR-489 and suppressed EMT events of HCT116 cells, while CHRF overexpression showed opposite effects on miR-489 expression and EMT in SW480 cells. Taken together, this work support the first evidence that lncRNA CHRF-induced miR-489 loss facilitates metastasis and EMT process of CRC cells probably via TWIST1/EMT signaling pathway.

miRNAs as potential regulators of mTOR pathway in renal cell carcinoma

Renal cell carcinoma (RCC) is the most commonly occurring solid cancer of the adult kidney with the majority of RCC cases being detected accidentally. The most aggressive subtype is clear cell RCC (ccRCC). miRNAs, a family of small noncoding RNAs regulating gene expression have been identified as key biological modulators. The von Hippel-Lindau pathway is one of the signaling pathways involved in the pathophysiology of ccRCC. Another oncogenic mechanism involves the activation of PI3K/AKT/mTOR signaling and serves as a central regulator of cell metabolism, proliferation and survival. Several studies have described the involvement of miRNA dysregulation in the pathogenesis and progression of ccRCC. These molecules can be considered as potential diagnostic and prognostic biomarkers, allowing response to therapy to be monitored.

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-489 inhibits proliferation, cell cycle progression and induces apoptosis of glioma cells via targeting SPIN1-mediated PI3K/AKT pathway

microRNA-489 (miR-489), a newly identified tumor-related miRNA, functions as an oncogene or tumor suppressor via regulating growth and metastasis of human cancers. But, the clinical significance, biological function and underlying mechanisms of miR-489 in glioma remain rarely known. Here, we showed that the levels of miR-489 in glioma tissues were notably underexpressed compared to corresponding non-tumor tissues. In accordance, the relative levels of miR-489 were decreased in glioma cell lines compared with NHA cells. Kaplan-Meier plots indicated that miR-489 low expressing glioma patients showed a prominent shorter overall survival. In addition, miR-489 overexpression prohibited proliferation and cell cycle progression, and promoted apoptosis in U251 cells. While, miR-489 knockdown showed opposite effects on these cellular processes of U87 cells. In vivo experiments demonstrated that miR-489 restoration reduced the tumor volume and weight of subcutaneous glioma xenografts in nude mice. Notably, Spindlin 1 (SPIN1) was inversely and directly regulated by miR-489 in glioma cells. A negative correlation between the expression of miR-489 and SPIN1 mRNA was confirmed in glioma tissues. Interestingly, miR-489 inversely modulated activation of PI3K/AKT pathway and expression of downstream targets including p-mTOR, Cyclin D1 and BCL-XL. SPIN1 re-expression abolished the effects of miR-489 on U251 cells with enhanced activation of PI3K/AKT pathway and malignant phenotype. Meanwhile, AKT inhibitor MK-2206 blocked activation of PI3K/AKT pathway and resulted in reduced proliferation, cell cycle arrest and increased apoptosis in miR-489 down-regulating U87 cells. Altogether, our data support that miR-489 loss facilitates malignant phenotype of glioma cells probably via SPIN1-mediated PI3K/AKT pathway.

Significantly altered expression of miR-511-3p and its target AKT3 has negative prognostic value in human prostate cancer

PURPOSE

In this study, we assessed the expression and functions of microRNA-511-3p (miR-511-3p) in human prostate cancer (CaP).

METHODS

Gene expressions of miR-511-3p in CaP cells and human CaP tumors were assessed by qPCR. In VCaP and PC3 cells, miR-511-3p was overexpressed by lentivirus. The functions of miR-511-3p upregulation in regulating in vitro cancer proliferation, migration and in vivo cancer growth were assessed by MTT, transwell and transplantation assays, respectively. Downstream target gene of miR-511-3p, AKT3, was verified by dual-luciferase activity and qPCR assays. AKT3 was then overexpressed in miR-511-3p-upregulated CaP cells to assess its functions in miR-511-3p-mediated cancer regulation.

RESULTS

MiR-511-3p is significantly downregulated in CaP cell lines, and human CaP tumors. MiR-511-3p was further downregulated in T3/T4-staged CaP tumors and closely correlated with shorter overall survival among CaP patients. In VCaP and PC3 cells, lentiviral-induced miR-511-3p upregulation was acting as a tumor suppressor by inhibiting in vitro cancer proliferation, migration and in vivo transplantation. Human AKT3 gene was confirmed to be the downstream target of miR-511-3p in CaP. In miR-511-3p-upregulated VCaP and PC3 cells, forced-overexpression of AKT3 reversed the tumor suppressive effects of miR-511-3p in CaP.

CONCLUSION

MiR-511-3p may serve as a prognostic factor and tumor suppressor in CaP, very likely through inverse regulation of its downstream target gene of AKT3.

MiR-183 overexpression inhibits tumorigenesis and enhances DDP-induced cytotoxicity by targeting MTA1 in nasopharyngeal carcinoma

MicroRNA 183 (miR-183) was identified to be downregulated in nasopharyngeal carcinoma spheroids and served as a tumor suppressor in nasopharyngeal carcinoma. However, the regulatory mechanism of miR-183 and its role in cisplatin (DDP) resistance in nasopharyngeal carcinoma cells are still unclear. The expression of miR-183 and metastasis-associated protein 1 at messenger RNA and protein levels in nasopharyngeal carcinoma tissues and cells was evaluated using quantitative reverse transcription real-time polymerase chain reaction and western blotting, respectively. CNE1 and CNE2 cells were transfected with miR-183 mimic, miR-183 inhibitor, pcDNA-metastasis-associated protein 1, or respective controls. The effects of miR-183 and metastasis-associated protein 1 overexpression on cell proliferation, invasion, and DDP-induced apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, Transwell invasion assay, and flow cytometry analysis, respectively. Luciferase reporter assay was performed to explore whether miR-183 directly targeted metastasis-associated protein 1. Xenograft tumor experiment was applied to confirm the biological function of miR-183 in vivo. MiR-183 was downregulated in nasopharyngeal carcinoma tissues and cells and negatively correlated with metastasis-associated protein 1 expression. Ectopic expression of miR-183 markedly suppressed cell proliferation and invasion and strikingly enhanced DDP-induced apoptosis in nasopharyngeal carcinoma cells, whereas metastasis-associated protein 1 overexpression partially reversed these effects. Luciferase reporter assay demonstrated that metastasis-associated protein 1 was a direct target of miR-183. MiR-183 negatively regulated the expression of metastasis-associated protein 1 at both the messenger RNA and protein levels. Xenograft tumor experiment indicated that miR-183 overexpression repressed tumor growth and improved DDP-induced cytotoxicity in nasopharyngeal carcinoma cells in vivo. MiR-183 overexpression inhibited tumorigenesis and enhanced DDP-induced cytotoxicity by targeting metastasis-associated protein 1 in nasopharyngeal carcinoma, contributing to the development of novel therapeutic approaches for the treatment of clinical nasopharyngeal carcinoma patients.

Novel RNA biomarkers of prostate cancer revealed by RNA-seq analysis of formalin-fixed samples obtained from Russian patients

Due to heterogeneous multifocal nature of prostate cancer (PCa), there is currently a lack of biomarkers that stably distinguish it from benign prostatic hyperplasia (BPH), predict clinical outcome and guide the choice of optimal treatment. In this study RNA-seq analysis was applied to formalin-fixed paraffin-embedded (FFPE) tumor and matched normal tissue samples collected from Russian patients with PCa and BPH. We identified 3384 genes differentially expressed (DE) (FDR < 0.05) between tumor tissue of PCa patients and adjacent normal tissue as well as both tissue types from BPH patients. Overexpression of four of the discovered genes (ANKRD34B, NEK5, KCNG3, and PTPRT) was validated by RT-qPCR. Furthermore, the enrichment analysis of overrepresented microRNA and transcription factor (TF) recognition sites within DE genes revealed common regulatory elements of which 13 microRNAs and 53 TFs were thus linked to PCa for the first time. Moreover, 8 of these TFs (FOXJ2, GATA6, NFE2L1, NFIL3, PRRX2, TEF, EBF2 and ZBTB18) were found to be differentially expressed in this study making them not only candidate biomarkers of prostate cancer but also potential therapeutic targets.

microRNA-489 Plays an Anti-Metastatic Role in Human Hepatocellular Carcinoma by Targeting Matrix Metalloproteinase-7

Dysregulation of microRNAs (miRNAs) is actively involved in the pathogenesis and tumorigenicity of hepatocellular carcinoma (HCC). miR-489 was found to play either oncogenic or tumor suppressive roles in human cancers. Recent study reported that the levels of miR-489 in late recurrent HCC patients were evidently higher than that in early recurrent cases, suggesting that miR-489 may function as a tumor suppressive miRNA in HCC. Yet, the clinical value and biological function of miR-489 remain rarely known in HCC. Here, we presented that miR-489 level in HCC tissues was notably reduced compared to matched non-cancerous specimens. Its decreased level was evidently correlated with adverse clinical parameters and poor prognosis of HCC patients. Accordingly, the levels of miR-489 were obviously down-regulated in HCC cells. Ectopic expression of miR-489 in HCCLM3 and MHCC97H cells prominently inhibits the migration and invasion of tumor cells and reduced lung metastases in vivo, while miR-489 knockdown increased these behaviors of HepG2 and MHCC97L cells. Mechanically, miR-489 negatively regulated matrix metalloproteinase-7 (MMP7) abundance in HCC cells. Herein, MMP7 was found to be a downstream molecule of miR-489 in HCC. An inversely correlation between miR-489 and MMP7 was confirmed in HCC specimens. MMP7 knockdown prohibited cell migration and invasion while MMP7 overexpression showed opposite effects on HCC cells. Furthermore, restoration of MMP7 expression could abrogate the anti-metastatic effects of miR-489 on HCCLM3 cells with enhanced cell migration and invasion. Altogether, miR-489 potentially acts as a prognostic predictor and a drug-target for HCC patients.

A novel double-negative feedback loop between miR-489 and the HER2-SHP2-MAPK signaling axis regulates breast cancer cell proliferation and tumor growth

Human epidermal growth factor receptor 2 (HER2 or ErBb2) is a receptor tyrosine kinase overexpressed in 20-30% of breast cancers and associated with poor prognosis and outcome. Dysregulation of several microRNAs (miRNAs) plays a key role in breast cancer progression and metastasis. In this study, we screened and identified miRNAs dysregualted in HER2-positive breast cancer cells. Our molecular study demonstrated that miR-489 was specifically downregulated by the HER2-downstream signaling, especially through the MAPK pathway. Restoration or overexpression of miR-489 in HER2-positive breast cancer cells significantly inhibited cell growth in vitro and decreased the tumorigenecity and tumor growth in xenograft mice. Mechanistically, we found that overexpression of miR-489 led to the decreased levels of HER2 and SHP2 and thus attenuated HER2-downstream signaling. Furthermore, we for the first time demonstrated that HER2 is a direct target of miR-489 and therefore HER2-SHP2-MAPK and miR-489 signaling pathways form a mutually inhibitory loop. Using quantitative real-time PCR analysis and Fluorescent in situ hybridization technique (FISH), we found that miR-489 was expressed at significantly lower level in tumor tissues compared to the adjacent normal tissues. Downregulation of miR-489 in breast cancers was associated with aggressive tumor phenotypes. Overall, our results define a double-negative feedback loop involving miR-489 and the HER2-SHP2-MAPK signaling axis that can regulate breast cancer cell proliferation and tumor progression and might have therapeutic relevance for HER2-positive breast cancer.

KRAS/NF-κB/YY1/miR-489 Signaling Axis Controls Pancreatic Cancer Metastasis

KRAS activation occurring in more than 90% of pancreatic ductal adenocarcinomas (PDAC) drives progression and metastasis, but the underlying mechanisms involved in these processes are still poorly understood. Here, we show how KRAS acts through inflammatory NF-κB signaling to activate the transcription factor YY1, which represses expression of the tumor suppressor gene miR-489. In PDAC cells, repression of miR-489 by KRAS signaling inhibited migration and metastasis by targeting the extracellular matrix factors ADAM9 and MMP7. miR-489 downregulation elevated levels of ADAM9 and MMP7, thereby enhancing the migration and metastasis of PDAC cells. Together, our results establish a pivotal mechanism of PDAC metastasis and suggest miR-489 as a candidate therapeutic target for their attack. Cancer Res; 77(1); 100-11. ©2016 AACR.

miR-489 Suppresses Proliferation and Invasion of Human Bladder Cancer Cells

MicroRNAs (miRNAs) have been shown to be involved in bladder cancer progression. miR-489 (also known as miR-489-3p) was recently reported to be a tumor suppressor in several cancers. However, its exact role and mechanism in the progression of bladder cancer are largely unknown. In this study, we explore the role of miR-489 in the proliferation and invasion of human bladder cancer cells. The miR-489 expression levels were detected in bladder cancer and normal adjacent tissues, as well as in human normal bladder epithelial cells and bladder cancer cell lines. The results showed that miR-489 was sharply reduced in bladder cancer tissues and cell lines. Then the miR-489 mimic or oligo anta-miR-489 was transfected into T24 and UMUC3 bladder cancer cell lines. The results showed that the miR-489 mimic greatly increased the miR-489 level and significantly decreased the proliferation and invasion of T24 and UMUC3 cells. In contrast, the anta-miR-489 had a completely opposite effect on miR-489 expression, cell proliferation, and cell invasion. Moreover, bioinformatics and luciferase reporter gene assays confirmed that miR-489 targeted the mRNA 3'-untranslated region (3'-UTR) region of Jagged1 (JAG1), a Notch ligand. In conclusion, miR-489 suppressed proliferation and invasion of human bladder cancer cells.

HE4 promotes collateral resistance to cisplatin and paclitaxel in ovarian cancer cells

Background

Chemotherapy resistance presents a difficult challenge in treating epithelial ovarian cancer patients, particularly when tumors exhibit resistance to multiple chemotherapeutic agents. A few studies have shown that elevated serum levels of the ovarian cancer biomarker HE4 correlate with tumor chemoresistance, response to treatment, and survival. Here, we sought to confirm our previous results that HE4 contributes to collateral resistance to cisplatin and paclitaxel in vitro and uncover factors that may contribute to HE4-mediated chemoresistance.

Methods

MTS assays and western blots for cleaved PARP were used to assess resistance of HE4-overexpressing SKOV3 and OVCAR8 clones to cisplatin and paclitaxel. CRISPR/Cas technology was used to knockdown HE4 in HE4-overexpressing SKOV3 cells. A microarray was conducted to determine differential gene expression between SKOV3 null vector-transfected and HE4-overexpressing clones upon cisplatin exposure, and results were validated by quantitative RT-PCR. Regulation of mitogen activated protein kinases (MAPKs) and tubulins were assessed by western blot.

Results

HE4-overexpressing SKOV3 and OVCAR8 clones displayed increased resistance to cisplatin and paclitaxel. Knockdown of HE4 in HE4-overexpressing SKOV3 cells partially reversed chemoresistance. Microarray analysis revealed that HE4 overexpression resulted in suppression of cisplatin-mediated upregulation of EGR1, a MAPK-regulated gene involved in promoting apoptosis. Upregulation of p38, a MAPK activated in response to cisplatin, was suppressed in HE4-overexpressing clones. No differences in extracellular signal-regulated kinase (ERK) activation were noted in HE4-overexpressing clones treated with 25 μM cisplatin, but ERK activation was partially suppressed in HE4-overexpressing clones treated with 80 μM cisplatin. Furthermore, treatment of cells with recombinant HE4 dramatically affected ERK activation in SKOV3 and OVCAR8 wild type cells. Recombinant HE4 also upregulated α-tubulin and β-tubulin levels in SKOV3 and OVCAR8 cells, and microtubule associated protein tau (MAPT) gene expression was increased in SKOV3 HE4-overexpressing clones.

Conclusions

Overexpression of HE4 promotes collateral resistance to cisplatin and paclitaxel, and downregulation of HE4 partially reverses this chemoresistance. Multiple factors could be involved in HE4-mediated chemoresistance, including deregulation of MAPK signaling, as well as alterations in tubulin levels or stability.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-016-0240-0) contains supplementary material, which is available to authorized users.

High-Throughput Sequencing Identifies MicroRNAs from Posterior Intestine of Loach (Misgurnus anguillicaudatus) and Their Response to Intestinal Air-Breathing Inhibition

MicroRNAs (miRNAs) exert important roles in animal growth, immunity, and development, and regulate gene expression at the post-transcriptional level. Knowledges about the diversities of miRNAs and their roles in accessory air-breathing organs (ABOs) of fish remain unknown. In this work, we used high-throughput sequencing to identify known and novel miRNAs from the posterior intestine, an important ABO, in loach (Misgurnus anguillicaudatus) under normal and intestinal air-breathing inhibited conditions. A total of 204 known and 84 novel miRNAs were identified, while 47 miRNAs were differentially expressed between the two small RNA libraries (i.e. between the normal and intestinal air-breathing inhibited group). Potential miRNA target genes were predicted by combining our transcriptome data of the posterior intestine of the loach under the same conditions, and then annotated using COG, GO, KEGG, Swissprot and Nr databases. The regulatory networks of miRNAs and their target genes were analyzed. The abundances of nine known miRNAs were validated by qRT-PCR. The relative expression profiles of six known miRNAs and their eight corresponding target genes, and two novel potential miRNAs were also detected. Histological characteristics of the posterior intestines in both normal and air-breathing inhibited group were further analyzed. This study contributes to our understanding on the functions and molecular regulatory mechanisms of miRNAs in accessory air-breathing organs of fish.

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.

MicroRNA-449a reduces cell survival and enhances cisplatin-induced cytotoxicity via downregulation of NOTCH1 in ovarian cancer cells

Epithelial ovarian cancer (EOC) is the leading cause of death from gynecologic malignancies. Platinum-based chemotherapy is the first-line treatment for the advanced ovarian cancer, but resistance to cisplatin remains a major obstacle to successful treatment. MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in disease processes, including the development of drug resistance. In this study, we found miR-449a were significantly downregulated in the cisplatin-resistant ovarian cell lines SKOV3/DDP and A2780/DDP, compared with their sensitive parent line SKOV3 and A2780, respectively. The overexpression of miR-449a increased cisplatin sensitivity of SKOV3/DDP and A2780/DDP cells by inhibiting proliferation and promoting apoptosis. The luciferase assay confirmed that miR-449a functioned through suppressing NOTCH1 directly. Concordantly, BALB/c nude mice that were injected intraperitoneally with SKOV3/DDP cells transfected with miR-449a mimics exhibited enhanced cisplatin sensitivity in vivo. Taken together, these results suggest that the ectopic expression of miR-449a may be a promising therapeutic strategy for the management of cisplatin resistance in ovarian cancer.

The potential of microRNAs in personalized medicine against cancers

MicroRNAs orchestrate the expression of the genome and impact many, if not all, cellular processes. Their deregulation is thus often causative of human malignancies, including cancers. Numerous studies have implicated microRNAs in the different steps of tumorigenesis including initiation, progression, metastasis, and resistance to chemo/radiotherapies. Thus, microRNAs constitute appealing targets for novel anticancer therapeutic strategies aimed at restoring their expression or function. As microRNAs are present in a variety of human cancer types, microRNA profiles can be used as tumor-specific signatures to detect various cancers (diagnosis), to predict their outcome (prognosis), and to monitor their treatment (theranosis). In this review, we present the different aspects of microRNA biology that make them remarkable molecules in the emerging field of personalized medicine against cancers and provide several examples of their industrial exploitation.