Expression analysis of MIR182 and its associated target genes in advanced ovarian carcinoma

Caloric Restriction Attenuated Nerve Damages Mediated Through SIRT-1-a Study Using Nerve Crush Injury Model in Rats

Activation of Sirtuin 1 (SIRT-1) is vital for axonogenesis and nerve regeneration. Caloric restriction (CR) has health benefits and protects against neurodegenerative disorders, largely through SIRT-1 regulation. This study investigates how diet control impacts peripheral nerve injury, focusing on SIRT-1 expression. We prepared nerve tissue cultures for a pharmacological analysis of SIRT-1's effects on nerve degeneration. After two weeks of 70% caloric restriction, we crushed the left sciatic nerve of Sprague-Dawley rats with a vessel clamp. We then administered SIRT-1 agonists or antagonists intraperitoneally. Nerve explant cultures showed increased SIRT-1 expression with SRT-1720, which was reduced by EX527, indicating enhanced regeneration. In the animal study, diet control led to notable SIRT-1 expression in plasma. This expression increased with SIRT-1 agonists and decreased with antagonists. SIRT-1 levels in paw skin were strongly correlated with PGP 9.5 and collagen deposition, while nerve fiber size and regeneration markers (S-100 and NF) also correlated with SIRT-1 expression. Inflammatory markers showed an inverse relationship with SIRT-1. TNF-α and NGF in the dorsal root ganglion responded reciprocally to SIRT-1 expression. Increased acetylcholine receptors and desmin in denervated muscle were parallel to SIRT-1 levels, with similar trends observed in muscle weight and diameter. Neurobehavioral and electrophysiological results aligned with these measurements. Caloric restriction has a preventative effect on nerve damage, mainly through SIRT-1 modulation. From a health perspective, promoting caloric restriction is important for mitigating nerve injury severity.

ROS and miRNA Dysregulation in Ovarian Cancer Development, Angiogenesis and Therapeutic Resistance

The diverse repertoires of cellular mechanisms that progress certain cancer types are being uncovered by recent research and leading to more effective treatment options. Ovarian cancer (OC) is among the most difficult cancers to treat. OC has limited treatment options, especially for patients diagnosed with late-stage OC. The dysregulation of miRNAs in OC plays a significant role in tumorigenesis through the alteration of a multitude of molecular processes. The development of OC can also be due to the utilization of endogenously derived reactive oxygen species (ROS) by activating signaling pathways such as PI3K/AKT and MAPK. Both miRNAs and ROS are involved in regulating OC angiogenesis through mediating multiple angiogenic factors such as hypoxia-induced factor (HIF-1) and vascular endothelial growth factor (VEGF). The NAPDH oxidase subunit NOX4 plays an important role in inducing endogenous ROS production in OC. This review will discuss several important miRNAs, NOX4, and ROS, which contribute to therapeutic resistance in OC, highlighting the effective therapeutic potential of OC through these mechanisms.

Interactions between miRNAs and Double-Strand Breaks DNA Repair Genes, Pursuing a Fine-Tuning of Repair

The repair of DNA damage is a crucial process for the correct maintenance of genetic information, thus, allowing the proper functioning of cells. Among the different types of lesions occurring in DNA, double-strand breaks (DSBs) are considered the most harmful type of lesion, which can result in significant loss of genetic information, leading to diseases, such as cancer. DSB repair occurs through two main mechanisms, called non-homologous end joining (NHEJ) and homologous recombination repair (HRR). There is evidence showing that miRNAs play an important role in the regulation of genes acting in NHEJ and HRR mechanisms, either through direct complementary binding to mRNA targets, thus, repressing translation, or by targeting other genes involved in the transcription and activity of DSB repair genes. Therefore, alteration of miRNA expression has an impact on the ability of cells to repair DSBs, which, in turn, affects cancer therapy sensitivity. This latter gives account of the importance of miRNAs as regulators of NHEJ and HRR and places them as a promising target to improve cancer therapy. Here, we review recent reports demonstrating an association between miRNAs and genes involved in NHEJ and HRR. We employed the Web of Science search query TS (“gene official symbol/gene aliases*” AND “miRNA/microRNA/miR-”) and focused on articles published in the last decade, between 2010 and 2021. We also performed a data analysis to represent miRNA–mRNA validated interactions from TarBase v.8, in order to offer an updated overview about the role of miRNAs as regulators of DSB repair.

miR-182 targeting reprograms tumor-associated macrophages and limits breast cancer progression

The protumor roles of alternatively activated (M2) tumor-associated macrophages (TAMs) have been well established, and macrophage reprogramming is an important therapeutic goal. However, the mechanisms of TAM polarization remain incompletely understood, and effective strategies for macrophage targeting are lacking. Here, we show that miR-182 in macrophages mediates tumor-induced M2 polarization and can be targeted for therapeutic macrophage reprogramming. Constitutive miR-182 knockout in host mice and conditional knockout in macrophages impair M2-like TAMs and breast tumor development. Targeted depletion of macrophages in mice blocks the effect of miR-182 deficiency in tumor progression while reconstitution of miR-182-expressing macrophages promotes tumor growth. Mechanistically, cancer cells induce miR-182 expression in macrophages by TGFβ signaling, and miR-182 directly suppresses TLR4, leading to NFκb inactivation and M2 polarization of TAMs. Importantly, therapeutic delivery of antagomiR-182 with cationized mannan-modified extracellular vesicles effectively targets macrophages, leading to miR-182 inhibition, macrophage reprogramming, and tumor suppression in multiple breast cancer models of mice. Overall, our findings reveal a crucial TGFβ/miR-182/TLR4 axis for TAM polarization and provide rationale for RNA-based therapeutics of TAM targeting in cancer.

HMGA2: A Biomarker in Gynecologic Neoplasia

High Mobility Group A2 gene (HMGA2), an oncofetal protein, is normally expressed in fetal development and completely shuts down in almost all organs and tissue types during adulthood. It is upregulated or overexpressed again in certain mesenchymal neoplasms due to chromosomal translocations and in malignant epithelial tumors through transcription regulation. HMGA2 overexpression can either drive tumor development or promote the aggressiveness of tumor growth. Many gynecologic neoplasms, including uterine smooth muscle tumors and ovarian cancer, are associated with HMGA2 overexpression. In this article, we review recent developments in the study of HMGA2 and its expression as a potential biomarker for gynecologic neoplasms and clinic application.

OCaMIR-A Noninvasive, Diagnostic Signature for Early-Stage Ovarian Cancer: A Multi-cohort Retrospective and Prospective Study

PURPOSE

Due to the lack of effective screening approaches and early detection biomarkers, ovarian cancer has the highest mortality rates among gynecologic cancers. Herein, we undertook a systematic biomarker discovery and validation approach to identify microRNA (miRNA) biomarkers for the early detection of ovarian cancer.

EXPERIMENTAL DESIGN

During the discovery phase, we performed small RNA sequencing in stage I high-grade serous ovarian cancer (n = 31), which was subsequently validated in multiple, independent data sets (TCGA, n = 543; GSE65819, n = 87). Subsequently, we performed multivariate logistic regression-based training in a serum data set (GSE106817, n = 640), followed by its independent validation in three retrospective data sets (GSE31568, n = 85; GSE113486, n = 140; Czech Republic cohort, n = 192) and one prospective serum cohort (n = 95). In addition, we evaluated the specificity of OCaMIR, by comparing its performance in several other cancers (GSE31568 cohort, n = 369).

RESULTS

The OCaMIR demonstrated a robust diagnostic accuracy in the stage I high-grade serous ovarian cancer patients in the discovery cohort (AUC = 0.99), which was consistently reproducible in both stage I (AUC = 0.96) and all stage patients (AUC = 0.89) in the TCGA cohort. Logistic regression-based training and validation of OCaMIR achieved AUC values of 0.89 (GSE106817), 0.85 (GSE31568), 0.86 (GSE113486), and 0.82 (Czech Republic cohort) in the retrospective serum validation cohorts, as well as prospective validation cohort (AUC = 0.92). More importantly, OCaMIR demonstrated a significantly superior diagnostic performance compared with CA125 levels, even in stage I patients, and was more cost-effective, highlighting its potential role for screening and early detection of ovarian cancer.

CONCLUSIONS

Small RNA sequencing identified a robust noninvasive miRNA signature for early-stage serous ovarian cancer detection.

Splicing factor USP39 promotes ovarian cancer malignancy through maintaining efficient splicing of oncogenic HMGA2

Aberrant expression of splicing factors was found to promote tumorigenesis and the development of human malignant tumors. Nevertheless, the underlying mechanisms and functional relevance remain elusive. We here show that USP39, a component of the spliceosome, is frequently overexpressed in high-grade serous ovarian carcinoma (HGSOC) and that an elevated level of USP39 is associated with a poor prognosis. USP39 promotes proliferation/invasion in vitro and tumor growth in vivo. Importantly, USP39 was transcriptionally activated by the oncogene protein c-MYC in ovarian cancer cells. We further demonstrated that USP39 colocalizes with spliceosome components in nuclear speckles. Transcriptomic analysis revealed that USP39 deletion led to globally impaired splicing that is characterized by skipped exons and overrepresentation of introns and intergenic regions. Furthermore, RNA immunoprecipitation sequencing showed that USP39 preferentially binds to exon-intron regions near 5' and 3' splicing sites. In particular, USP39 facilitates efficient splicing of HMGA2 and thereby increases the malignancy of ovarian cancer cells. Taken together, our results indicate that USP39 functions as an oncogenic splicing factor in ovarian cancer and represents a potential target for ovarian cancer therapy.

BRCA1 Expression by Immunohistochemistry and Prognosis in Ovarian Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Homologous recombination deficiencies are associated with increased platinum sensitivity and potential response to poly (ADP-ribose) polymerase inhibitors in epithelial ovarian cancer. As an alternative to germline testing or somatic tumor sequencing, BRCA1 deficiency can be detected by immunohistochemistry and might predict homologous recombination deficiencies.

OBJECTIVE

This study aimed to assess the association between BRCA1 expression by immunohistochemistry and the prognosis of patients with epithelial ovarian cancer.

METHODS

We conducted a systematic review and meta-analysis following the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement. We searched PubMed, EMBASE, Web of Science, and Scopus databases through July 2019. Reference lists of selected articles were screened for further studies. We conducted qualitative synthesis and meta-analyses of hazard ratios for overall survival and progression-free survival.

RESULTS

Of 41 studies of BRCA1 expression using immunohistochemistry, 18 evaluated the association of BRCA1 expression with patient survival (2738 cases). The loss of BRCA1 expression was associated with improved overall survival (hazard ratio = 0.67, 95% confidence interval 0.57-0.77) and progression-free survival (hazard ratio = 0.70, 95% confidence interval 0.58-0.84).

CONCLUSIONS

Negative BRCA1 expression assessed by immunohistochemistry was associated with a better prognosis in epithelial ovarian cancer.

Frizzled-7 Identifies Platinum-Tolerant Ovarian Cancer Cells Susceptible to Ferroptosis

Defining traits of platinum-tolerant cancer cells could expose new treatment vulnerabilities. Here, new markers associated with platinum-tolerant cells and tumors were identified using in vitro and in vivo ovarian cancer models treated repetitively with carboplatin and validated in human specimens. Platinum-tolerant cells and tumors were enriched in ALDH+ cells, formed more spheroids, and expressed increased levels of stemness-related transcription factors compared with parental cells. Additionally, platinum-tolerant cells and tumors exhibited expression of the Wnt receptor Frizzled-7 (FZD7). Knockdown of FZD7 improved sensitivity to platinum, decreased spheroid formation, and delayed tumor initiation. The molecular signature distinguishing FZD7+ from FZD7- cells included epithelial-to-mesenchymal (EMT), stemness, and oxidative phosphorylation-enriched gene sets. Overexpression of FZD7 activated the oncogenic factor Tp63, driving upregulation of glutathione metabolism pathways, including glutathione peroxidase 4 (GPX4), which protected cells from chemotherapy-induced oxidative stress. FZD7+ platinum-tolerant ovarian cancer cells were more sensitive and underwent ferroptosis after treatment with GPX4 inhibitors. FZD7, Tp63, and glutathione metabolism gene sets were strongly correlated in the ovarian cancer Tumor Cancer Genome Atlas (TCGA) database and in residual human ovarian cancer specimens after chemotherapy. These results support the existence of a platinum-tolerant cell population with partial cancer stem cell features, characterized by FZD7 expression and dependent on the FZD7-β-catenin-Tp63-GPX4 pathway for survival. The findings reveal a novel therapeutic vulnerability of platinum-tolerant cancer cells and provide new insight into a potential "persister cancer cell" phenotype. SIGNIFICANCE: Frizzled-7 marks platinum-tolerant cancer cells harboring stemness features and altered glutathione metabolism that depend on GPX4 for survival and are highly susceptible to ferroptosis.

The Role of microRNAs in Epithelial Ovarian Cancer Metastasis

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and the major cause of death is mainly attributed to metastasis. MicroRNAs (miRNAs) are a group of small non-coding RNAs that exert important regulatory functions in many biological processes through their effects on regulating gene expression. In most cases, miRNAs interact with the 3′ UTRs of target mRNAs to induce their degradation and suppress their translation. Aberrant expression of miRNAs has been detected in EOC tumors and/or the biological fluids of EOC patients. Such dysregulation occurs as the result of alterations in DNA copy numbers, epigenetic regulation, and miRNA biogenesis. Many studies have demonstrated that miRNAs can promote or suppress events related to EOC metastasis, such as cell migration, invasion, epithelial-to-mesenchymal transition, and interaction with the tumor microenvironment. In this review, we provide a brief overview of miRNA biogenesis and highlight some key events and regulations related to EOC metastasis. We summarize current knowledge on how miRNAs are dysregulated, focusing on those that have been reported to regulate metastasis. Furthermore, we discuss the role of miRNAs in promoting and inhibiting EOC metastasis. Finally, we point out some limitations of current findings and suggest future research directions in the field.

MYC-regulated pseudogene HMGA1P6 promotes ovarian cancer malignancy via augmenting the oncogenic HMGA1/2

Pseudogenes have long been considered as nonfunctional genomic sequences. Recent studies have shown that they can potentially regulate the expression of protein-coding genes and are dysregulated in diseases including cancer. However, the potential roles of pseudogenes in ovarian cancer have not been well studied. Here we characterized the pseudogene expression profile in HGSOC (high-grade serous ovarian carcinoma) by microarray. We identified 577 dysregulated pseudogenes and most of them were up-regulated (538 of 577). HMGA1P6 (High mobility group AT-hook 1 pseudogene 6) was one of the overexpressed pseudogenes and its expression was inversely correlated with patient survival. Mechanistically, HMGA1P6 promoted ovarian cancer cell malignancy by acting as a ceRNA (competitive endogenous RNA) that led to enhanced HMGA1 and HMGA2 expression. Importantly, HMGA1P6 was transcriptionally activated by oncogene MYC in ovarian cancer. Our findings reveal that MYC may contribute to oncogenesis through transcriptional regulation of pseudogene HMGA1P6 in ovarian cancer.

HMGA2 is regulated by LIN28 and BRCA1 in human placental cells

The chromatin associated transcription factor HMGA2 is a downstream target of let-7 miRNAs and binds to chromatin to regulate gene expression. Inhibition of let-7 miRNAs by RNA-binding proteins LIN28A and LIN28B is necessary during early embryogenesis to ensure stable expression of HMGA2. In addition to LIN28, HMGA2 is regulated by a BRCA1/ZNF350/CtIP repressor complex. In normal tissues, the BRCA1/ZNF350/CtIP complex binds to the HMGA2 promoter to prevent transcription. However, in many cancers the oncomiR miR-182 targets BRCA1, preventing BRCA1 translation and allowing for increased HMGA2. Little is known about the regulation of HMGA2 during early placental development; therefore, we hypothesized that both LIN28 and BRCA1 can regulate HMGA2 in placental cells. Using siRNA and CRISPR gene editing techniques, we found that knockdowns of both LIN28A and LIN28B increase HMGA2 levels in ACH-3P cells. These cells also demonstrated deficiencies in cell differentiation, seemingly differentiating solely towards the syncytiotrophoblast sublineage, secreting higher amounts of hCG, and displaying upregulated ERVW-1. Additionally, we found that a knockout of both LIN28A and LIN28B caused a significant increase of miR-182 and a decrease in BRCA1 allowing HMGA2 mRNA levels to increase and protein levels to remain the same. Using chromatin immunoprecipitation, we saw binding of the BRCA1 repressor complex to HMGA2. We also saw a decrease in binding to HMGA2's promoter in the LIN28A/B knockout cells. These findings suggest a novel role for BRCA1 during early human placental development.

Immunohistochemistry for the detection of BRCA1 and BRCA2 proteins in patients with ovarian cancer: a systematic review

BACKGROUND

Loss of function in either breast cancer type 1 susceptibility protein (BRCA1) or breast cancer type 2 susceptibility protein (BRCA2) is a major risk factor for epithelial ovarian cancer (EOC) development. BRCA1 or BRCA2 deficiencies are associated with short-term prognosis and might have importance for the treatment of women with the disease. However, the screening of all possible mechanisms of dysfunction is expensive, time-consuming and difficult to apply in clinical practice. On the other hand, immunohistochemistry (IHC) is a simple and reliable method to access the expression of several proteins in tumour tissues.

MATERIALS AND METHODS

This systematic review aims to evaluate the current usage of IHC to detect BRCA1 and BRCA2 deficiencies in EOC. We searched and evaluated all primary literature on the use of IHC for evaluating BRCA1 and BRCA2 proteins expression in EOC. The main concepts for the search were: ovarian neoplasms, IHC, BRCA1 and BRCA2.

RESULTS

Forty-four studies from 925 unique titles were included. A total of 4206 tumour samples were evaluated for BRCA1 and 1041 for BRCA2 expression. Twelve BRCA1 primary antibodies were used in 41 studies, and the most common was the MS110 clone (75.6%). Seven BRCA2 primary antibodies were used in ten studies. Using the cut-off of 10%, 47.0% of EOCs are associated with loss of BRCA1 and 34.5% with the loss of BRCA2 expression.

CONCLUSION

IHC was effective to detect loss of BRCA1 protein expression in EOC; however, data on BRCA2 expression were heterogeneous and difficult to interpret.

Prognostic values and prospective pathway signaling of MicroRNA-182 in ovarian cancer: a study based on gene expression omnibus (GEO) and bioinformatics analysis

BACKGROUND

Ovarian carcinoma (OC) is a common cause of death among women with gynecological cancer. MicroRNAs (miRNAs) are believed to have vital roles in tumorigenesis of OC. Although miRNAs are broadly recognized in OC, the role of has-miR-182-5p (miR-182) in OC is still not fully elucidated.

METHODS

We evaluated the significance of miR-182 expression in OC by using analysis of a public dataset from the Gene Expression Omnibus (GEO) database and a literature review. Furthermore, we downloaded three mRNA datasets of OC and normal ovarian tissues (NOTs), GSE14407, GSE18520 and GSE36668, from GEO to identify differentially expressed genes (DEGs). Then the targeted genes of hsa-miR-182-5p (TG_miRNA-182-5p) were predicted using miRWALK3.0. Subsequently, we analyzed the gene overlaps integrated between DEGs in OC and predicted target genes of miR-182 by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. STRING and Cytoscape were used to construct a protein-protein interaction (PPI) network and the prognostic effects of the hub genes were analyzed.

RESULTS

A common pattern of up-regulation for miR-182 in OC was found in our review of the literature. A total of 268 DEGs, both OC-related and miR-182-related, were identified, of which 133 genes were discovered from the PPI network. A number of DEGs were enriched in extracellular matrix organization, pathways in cancer, focal adhesion, and ECM-receptor interaction. Two hub genes, MCM3 and GINS2, were significantly associated with worse overall survival of patients with OC. Furthermore, we identified covert miR-182-related genes that might participate in OC by network analysis, such as DCN, AKT3, and TIMP2. The expressions of these genes were all down-regulated and negatively correlated with miR-182 in OC.

CONCLUSIONS

Our study suggests that miR-182 is essential for the biological progression of OC.

Improved Motor Nerve Regeneration by SIRT1/Hif1a-Mediated Autophagy

Complete restoring of functional connectivity between neurons or target tissue after traumatic lesions is still an unmet medical need. Using models of nerve axotomy and compression, we investigated the effect of autophagy induction by genetic and pharmacological manipulation on motor nerve regeneration. ATG5 or NAD⁺-dependent deacetylase sirtuin-1 (SIRT1) overexpression on spinal motoneurons stimulates mTOR-independent autophagy and facilitates a growth-competent state improving motor axonal regeneration with better electromyographic records after nerve transection and suture. In agreement with this, using organotypic spinal cord cultures and the human cell line SH-SY5Y, we observed that the activation of SIRT1 and autophagy by NeuroHeal increased neurite outgrowth and length extension and that this was mediated by downstream HIF1a. To conclude, SIRT1/Hifα-dependent autophagy confers a more pro-regenerative phenotype to motoneurons after peripheral nerve injury. Altogether, we provide evidence showing that autophagy induction by SIRT1/Hifα activation or NeuroHeal treatment is a novel therapeutic option for improving motor nerve regeneration and functional recovery after injury.

BRCA1 regulates HMGA2 levels in the Swan71 trophoblast cell line

During early placental development, tumor suppressors and oncogenes work synergistically to regulate cell proliferation and differentiation in a restrained manner compared with the uncontrollable growth in cancer. One example of this partnership is the regulation of the oncofetal protein HMGA2 by BRCA1. BRCA1 forms a repressor complex with ZNF350 and CtIP to bind to the promoter of HMGA2, preventing transcription. Chromatin immunoprecipitation determined BRCA1 forms this repressor complex in human trophoblast cells, suggesting a role in the placenta. Furthermore, miR-182 has been shown to target BRCA1 mRNA in ovarian cancer cells, blocking the formation of the BRCA1 repressor complex and allowing increased transcription of HMGA2. miR-182 was one of the first miRNAs described as elevated in the serum and placentas of preeclamptic women. Therefore, we hypothesized that BRCA1 is essential for normal trophoblast cell development. We used CRISPR-Cas9 genome editing and miR-182 overexpression to decrease BRCA1 protein in the Swan71 cell line. HMGA2 was significantly increased in the BRCA1 KO and miR-182 overexpressing cells compared to controls. We also determined that BRCA1 repressor complex binding to HMGA2 was significantly reduced in BRCA1 KO and miR-182 overexpressing cells compared with controls, leading us to conclude that increased HMGA2 was because of decreased binding of the BRCA1 repressor complex. Finally, we found that the caspase activity was significantly higher in BRCA1 KO and miR-182 overexpressing cells suggesting an increased amount of apoptosis. These data suggest that BRCA1 is an important regulator of the oncofetal protein HMGA2 and promotes cell survival in human placental cells.

Alteration of BRCA-1 tumor suppressor gene expression in serous and mucinous ovarian neoplasms in the benign-borderline-malignant pathway

Alteration of expression of the tumor suppressor gene BRCA-1 has been widely studied in breast and ovarian carcinoma. However, pattern of this alteration in the benign-borderline-carcinoma sequence in serous and mucinous ovarian neoplasms have not yet fully described. Tissue sections from 214 formalin-fixed paraffin-embedded ovarian specimens were stained immunohistochemically with BRCA-1 antibody. Specimens were 10 normal ovarian surface epithelium, 10 fallopian tube epithelium, 70 benign adenoma (50 serous and 20 mucinous), 28 borderline (13 serous and 15 mucinous), 78 carcinoma (58 serous and 20 mucinous), and 18 metastatic deposit (13 serous and 5 mucinous). Expression was evaluated into 0, +1, +2, and +3. Score +3 staining similar to normal tissues was considered normal and other scores were considered altered expression. Strong expression was seen in all normal epithelium specimens. Altered expression was seen in 34 serous neoplasms; 17 of 50 (34%) of benign cystadenomas, 6 of 13 (46%) of borderline tumors, 43 of 58 (74%) of primary carcinoma, and in 8 of 13 (62%) of metastatic carcinoma. This alteration was significantly associated with higher histopathologic grade (P = 0.049), presence of necrosis (P = 0.0001), and higher proliferation rate (P = 0.001). In mucinous neoplasms; altered BRCA-1 was detected in 25 specimens; 7 of 20 (41%) of benign cystadenomas, 5 of 15 (33%) of borderline neoplasms, 9 of 20 (45%) of primary carcinoma, and 4 of 5 (80%) of the metastatic deposits. This alteration was not associated with any of the clinicopathologic tumor characteristics. In conclusion, alteration of BRCA-1 expression is more frequent in serous than in mucinous carcinomas and is associated with tumors of higher grades and high proliferation rate.

The effects of BRCA1 expression on the chemosensitivity of gastric cancer cells to platinum agents

Breast cancer type 1 susceptibility protein (BRCA1) is a tumor suppressor gene that encodes a nuclear phosphoprotein, which is involved in homologous recombination to repair DNA double strand breaks and maintain genome stability. When BRCA1 is mutated or altered, DNA damage may not be effectively repaired, which leads to DNA replication errors and cancer growth. Accordingly, people carrying a mutation in the BRCA1 gene possess an increased risk of several types of cancer, including breast and ovarian cancer. Previous clinical studies have reported an association between BRCA1 expression level and the incidence of gastric cancer; however, to the best of our knowledge, an in vitro study has not been performed to support these clinical observations. Therefore, the present study evaluated BRCA1 expression levels in gastric cancer cell lines. In addition, the IC₅₀ values of cisplatin and oxaliplatin in each cell line were determined to investigate a potential correlation between BRCA1 expression level and chemosensitivity to platinum agents. The present results revealed that the BRCA1 expression level in gastric cancer is variable and associated with the treatment response to platinum-based chemotherapy. This suggests that BRCA1 may serve as a therapeutic marker for platinum-based chemotherapy in gastric cancer.

Application of ex-vivo spheroid model system for the analysis of senescence and senolytic phenotypes in uterine leiomyoma

Cellular senecence is an important biologic endpoint. Naturally occuring (aging) senescence is common in uterine leiomyoma (ULM). AKT is one of major pathways in promoting ULM growth and survival. Inactivation of AKT by MK2206 in ULM resulted in stress-induced senescence in vitro. Study of the senescent phenotypes and molecular changes in ULM may greatly facilitate the understanding of the tumor biology and potential clinical therapy for this common disease associated with high morbidity. To study senescence in a model system that closely resembles primary ULM in vivo, we applied an ex vivo model of three-dimensional (3D) spheroid culture system which maintained the molecular and cellular characteristics of primary ULM and matched myometrium as seen in vivo. Gene expression profiling done on ULM induced to undergo replication (passaging) or stress-induced (MK2206) senescence revealed that ROS and hypoxic-related genes were upregulated in the two types of senescences. Overexpression of two selected genes, WIPI1 and SLITKR4, induced cellular senescence in ULM spheroids. Additionally, administration of ABT263 (a BH3 mimetic) effectively reduced the senescent cells induced in ULM spheroids. This study identified novel genes associated with senescence in ULM and demonstrated a BH3 mimetic to act as a senolytic to remove senescent cells.

MicroRNA-595 sensitizes ovarian cancer cells to cisplatin by targeting ABCB1

Ovarian cancer is among the leading cause of cancer-related deaths in females. In this study, we demonstrated that miR-595 expression was downregulated in the ovarian cancer tissues and cell lines. miR-595 expression was lower in the lymph node metastases tissues than in the primary ovarian cancer tissues and normal tissues. Furthermore, miR-595 overexpression suppressed the ovarian cancer cell proliferation, colony formation and invasion and promoted the sensitivity of ovarian cancer cell to cisplatin. We identified ABCB1 as a direct target gene of miR-595 in the ovarian cancer cell. ABCB1 expression was upregulated in the ovarian cancer tissues and cell lines. Morevoer, the expression level of ABCB1 was inversely correlated with miR-595 in the ovarian cancer tissues. In addition, overexpression of ABCB1 decreased the miR-595-overexpressing HO8910PM and SKOV-3 cell sensitivity to cisplatin. Ectopic expression of ABCB1 promoted the miR-595-overexpressing HO8910PM and SKOV-3 cell proliferation, colony formation and invasion. These data suggested that miR-595 acted a tumor suppressor role in ovarian cancer development and increased the sensitivity of ovarian cancer to cisplatin.

Potential microRNA-related Targets for Therapeutic Intervention with Ovarian Cancer Metastasis

Treatment of disseminated epithelial ovarian cancer (EOC) is an unmet medical need. Therefore, the identification along with preclinical and clinical validation of new targets is an issue of high importance. In this review we focus on microRNAs that mediate metastasis of EOC. We summarize up-regulated metastasis-promoting and down-regulated metastasis-suppressing microRNAs. We focus on preclinical in vitro and in vivo functions as well as their metastasis-related clinical correlations. Finally, we outline modalities for therapeutic intervention and critical issues of microRNA-based therapeutics in the context of metastatic EOC.

Targeting mitotic pathways for endocrine-related cancer therapeutics

A colossal amount of basic research over the past few decades has provided unprecedented insights into the highly complex process of cell division. There is an ever-expanding catalog of proteins that orchestrate, participate and coordinate in the exquisite processes of spindle formation, chromosome dynamics and the formation and regulation of kinetochore microtubule attachments. Use of classical microtubule poisons has still been widely and often successfully used to combat a variety of cancers, but their non-selective interference in other crucial physiologic processes necessitate the identification of novel druggable components specific to the cell cycle/division pathway. Considering cell cycle deregulation, unscheduled proliferation, genomic instability and chromosomal instability as a hallmark of tumor cells, there lies an enormous untapped terrain that needs to be unearthed before a drug can pave its way from bench to bedside. This review attempts to systematically summarize the advances made in this context so far with an emphasis on endocrine-related cancers and the avenues for future progress to target mitotic mechanisms in an effort to combat these dreadful cancers.

miRNA Regulation in Gliomas: Usual Suspects in Glial Tumorigenesis and Evolving Clinical Applications

In recent years, an increasing role for noncoding small RNAs (miRNA) has been uncovered in carcinogenesis. These oligonucleotides can promote degradation and/or inhibit translation of key mRNAs. Recent studies have also highlighted a possible role for miRNAs in adult and pediatric brain tumors, including high- and low-grade gliomas, medulloblastoma, ependymoma, and neoplasms associated with neurofibromatosis type 1. Gliomas represent the most common category of primary intraparenchymal brain tumors, and, for example, manipulation of signaling pathways, through inhibition of PTEN transcription appears to be an important function of miRNA dysregulation through miR-21, miR-106b, and miR-26a. Moreover, altered miRNA expression in gliomas play roles in the regulation of common tumorigenic processes, including receptor tyrosine kinase signaling, angiogenesis, invasion, suppression of differentiation, cell cycle enhancement, and inhibition of apoptosis. Suppression of differentiation requires the downregulation of a number of miRNAs that are both enriched in the brain and required for terminal glial differentiation, including miR-219 and miR-338. Our evolving understanding about the biology of gliomas make them attractive for miRNA study, given that recent evidence suggests that epigenetic and subtle genetic changes may contribute to their pathogenesis. Identification of key miRNAs also provides a rationale for developing robust biomarkers and inhibitory RNA strategies for therapeutic purposes in glioma patients.

Posttranscriptional regulation of FOXO expression: microRNAs and beyond

Forkhead box, class O (FOXO) transcription factors are major regulators of diverse cellular processes, including fuel metabolism, oxidative stress response and redox signalling, cell cycle progression and apoptosis. Their activities are controlled by multiple posttranslational modifications and nuclear-cytoplasmic shuttling. Recently, post-transcriptional regulation of FOXO synthesis has emerged as a new regulatory level of their functions. Accumulating evidence suggests that this post-transcriptional mode of regulation of FOXO activity operates in response to stressful stimuli, including oxidative stress. Here, we give a brief overview on post-transcriptional regulation of FOXO synthesis by microRNAs (miRNAs) and by RNA-binding regulatory proteins, human antigen R (HuR) and quaking (QKI). Aberrant post-transcriptional regulation of FOXOs is frequently connected with various disease states. We therefore discuss characteristic examples of FOXO regulation at the post-transcriptional level under various physiological and pathophysiological conditions, including oxidative stress and cancer. The picture emerging from this summary points to a diversity of interactions between miRNAs/miRNA-induced silencing complexes and RNA-binding regulatory proteins. Better insight into these complexities of post-transcriptional regulatory interactions will add to our understanding of the mechanisms of pathological processes and the role of FOXO proteins.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

miR-21 Is Overexpressed in Hydatidiform Mole Tissues and Promotes Proliferation, Migration, and Invasion in Choriocarcinoma Cells

OBJECTIVE

The aims of this study were to make clear whether miR-21 was dysregulated in hydatidiform mole (HM) tissues and choriocarcinoma (CCA) cells, to elucidate whether aberrant miR-21 expression would affect the function of CCA cells, and to find out whether there was a relationship between miR-21 and AKT, PDCD4, and PTEN in CCA cells.

METHODS

Fresh and formalin-fixed, paraffin-embedded trophoblastic tissues (normal first trimester placentas and HMs) were retrieved from the biobank in the International Peace Maternity and Child Health Hospital, Shanghai Jiao Tong University. Choriocarcinoma JAR and JEG-3 cells were cultured. Expression of miR-21 in trophoblast cells and tissues was examined by quantitative real-time polymerase chain reaction. Location and distribution of miR-21 in trophoblast tissues were determinated by in situ hybridization and fluorescent in situ hybridization. The effect of miR-21 on JAR and JEG-3 cells was tested by miR-21 mimics and inhibitor transfection, followed by cell viability assay, flow cytometric analysis, and Transwell analysis. Interaction between miR-21 and its target genes in CCA cells was verified by quantitative real-time polymerase chain reaction, Western blot, and luciferase report system.

RESULTS

We originally found miR-21 was markedly upregulated in HM tissues compared with normal first trimester placentas. The expression of miR-21 was exclusively confined in trophoblastic layers. Furthermore, we discovered miR-21 was significantly increased in JAR and JEG-3 cells compared with normal primary human trophoblastic cells. Moreover, we demonstrated miR-21 could promote proliferation, migration, and invasion of CCA cells. We furthermore proved miR-21 negatively regulated PDCD4 and PTEN in CCA cells and targeted to PDCD4 3'UTR directly. In addition, we confirmed that miR-21 could activate Akt pathway by phosphorylating Akt at Ser 473.

CONCLUSIONS

Our results suggested miR-21 was responsible for aggressive phenotype of gestational trophoblastic disease and had the potential diagnostic and therapeutic values for gestational trophoblastic neoplasm.

Role of miR-182 in response to oxidative stress in the cell fate of human fallopian tube epithelial cells

High grade serous ovarian carcinoma (HGSC) is a DNA instable tumor and its precursor is commonly found originating from the fimbriated end of the fallopian tube secretory epithelial (FTSE) cells. The local stresses via ovulation and related inflammation are risks for HGSC. In this study, we examined the cellular and molecular responses of FTSE cells to stress. We found that excess intracellular reactive oxygen species (ROS) in normal FTSE cells upregulated a subset of microRNA expression (defined as ROSmiRs). Most ROSmiRs' expression and function were influenced and regulated by p53, and together they drove the cells into stress-induced premature senescence (SIPS). However, ROS-induced miR-182 is regulated by β-catenin, not by p53. In normal FTSE cells, miR-182 overexpression triggers cellular senescence by p53-mediated upregulation of p21. Conversely, in cells with p53 mutations, miR-182 overexpression no longer enhances p21 but functions as an “Onco-miR”. p53 dysfunction is a prerequisite for miR-182-mediated tumorigenesis. In addition, we found that human follicular fluid could significantly induce intracellular ROS in normal FTSE cells. These findings suggest that ROS and p53 mutations may trigger a series of events, beginning with overexpressing miR-182 by ROS and β-catenin, impairing the DNA damage response, promoting DNA instability, bypassing senescence and eventually leading to DNA instable tumors in FTSE cells.

Nogo-C regulates cardiomyocyte apoptosis during mouse myocardial infarction

Myocardial infarction is caused by insufficient coronary blood supply, which leads to myocardial damage and eventually the heart failure. Molecular mechanisms associated with the loss of cardiomyocytes during myocardial infarction (MI) and ischemia-related cardiac diseases are not yet fully understood. Nogo-C is an endoplasmic reticulum protein ubiquitously expressed in tissues including in the heart, however, the cardiac function of Nogo-C is still unknown. In the present study, we found that Nogo-C was upregulated in mouse hearts after MI, and hypoxic treatments also increased Nogo-C protein level in cardiomyocytes. Adenovirus mediated overexpression of Nogo-C led to cardiomyocyte apoptosis, whereas knockdown of Nogo-c by shRNA protected cardiomyocytes from hypoxia-induced cell apoptosis. Importantly, Nogo-C knockout mice displayed improved cardiac function, smaller infarct area, and less apoptotic cells after MI. Moreover, we found that miR-182 negatively regulated Nogo-C expression and was downregulated during MI, expressing miR-182 in cardiomyocytes protected hypoxia- and Nogo-C-mediated cell apoptosis. Our results indicate that increased cardiac Nogo-C expression is both sufficient and necessary for ischemia-induced cardiomyocyte apoptosis and cardiac dysfunction, suggesting that deregulation of Nogo-C by miRNA may be a potential therapeutic target for ischemia-related heart diseases.

STC2 overexpression mediated by HMGA2 is a biomarker for aggressiveness of high-grade serous ovarian cancer

High-grade serous cancer (HGSC) is a lethal form of ovarian cancer due to invasion and early metastasis. Gain of epithelial-mesenchymal transition (EMT) contributes to the aggressiveness of HGSC. High-mobility gene group A2 (HMGA2), an architectural transcription factor, plays a major role in HGSC through the regulation of EMT gene expression. Based on the gene profiling analysis, we found that the potent EMT gene, stanniocalcin 2 (STC2), was highly correlated with HMGA2 expression. In the present study, we demonstrated that STC2 was directly regulated by HMGA2 at the transcriptional level. Overexpressing STC2 in vitro directly enhanced cell migration and invasion. To investigate the correlation of STC2 and HMGA2 expression and the potential biomarker for ovarian cancer, three independent large cohorts of ovarian cancer (cohort 1=278, cohort 2=150 and cohort 3=95 cases) were examined in the present study. The results showed that the expression of HMGA2 and STC2 was positively correlated. Furthermore, STC2 expression was significantly associated with tumor grade and histotype. HGSC had significantly higher levels of STC2 expression and was inversely correlated with patient survival. These findings suggested that STC2 is an important new biomarker that can be used for HGSC.

MicroRNAs in Ovarian Cancer

Ovarian cancer, consisting predominantly of ovarian carcinoma, is the eighth most common cancer in women and the most lethal gynecologic malignancy. Efforts focus on identifying biomarkers which may aid in early diagnosis and reduce mortality, as well as on characterizing therapeutic targets with the aim of circumventing chemoresistance and prolonging survival at advanced-stage disease. MicroRNAs (miRNAs) are small, non-coding RNAs that post-transcriptionally regulate gene expression, and have been found to play an important role in ovarian carcinoma. Recent research has identified multiple miRNAs involved in the biology and progression of the disease, and supports a role for miRNAs as potential biomarkers, predictive markers and prognostic factors. Many of the studies published to date nevertheless suffer from critical weaknesses which affect data quality and reproducibility, including the comparison of normal ovaries to tumor tissue without compensation for the highly discrepant target cell fraction in these two specimen types and the inclusion of carcinomas of different histotypes, non-epithelial tumors or tumors of non-specified histology. These shortcomings highlight the critical role of pathologists as part of the team in the setting of such research. This review summarizes current knowledge in this area and discusses the potential clinical relevance of miRNAs in ovarian carcinoma, with focus on studies of clinical specimens in which tissue selection has been deemed adequate.

Prognostic Value of MicroRNA-182 in Cancers: A Meta-Analysis

OBJECTIVE

MicroRNA-182 (miR-182) exhibits altered expression in various cancers. The aim of this study was to investigate the predictive value of miR-182 expression for cancer patient survival.

METHODS

Eligible studies were identified through multiple search strategies, and the hazard ratios (HRs) for patient outcomes were extracted and estimated. A meta-analysis was performed to evaluate the prognostic value of miR-182.

RESULTS

In total, 14 studies were included. A high miR-182 expression level predicted a worse outcome with a pooled HR of 2.18 (95% CI: 1.53-3.11) in ten studies related to overall survival (OS), especially in Chinese populations. The results of seven studies evaluating disease-free survival/relapse-free survival/recurrence-free interval/disease-specific survival (DFS/RFS/RFI/DSS) produced a pooled HR of 1.77 (95% CI: 0.91-3.43), which was not statistically significant; however, the trend was positive. When disregarding the DSS from one study, the expression of miR-182 was significantly correlated with DFS/RFS/RFI (pooled HR = 2.52, 95% CI: 1.67-3.79).

CONCLUSIONS

High miR-182 expression is associated with poor OS and DFS/RFS/RFI in some types of cancers, and miR-182 may be a useful prognostic biomarker for predicting cancer prognosis. However, given the current insufficient relevant data, further clinical studies are needed.

MicroRNAs expression in triple negative vs non triple negative breast cancer in Tunisia: interaction with clinical outcome

Introduction

MicroRNAs are small, non coding regulatory molecules containing approximately 21 to 25 nucleotides. They function as controllers of expression at post transcriptional levels of most human protein-coding genes and play an essential role in cell signaling pathways. The objective of the present study is to evaluate the expression profile of the following micro-RNAs: miR-10b, miR-17, miR-21, miR-34a, miR-146a, miR-148a and miR-182, and to determine their possible interaction in triple-negative and non triple-negative primary breast cancers based on clinical outcome.

Methods

60 triple-negative and non triple-negative breast cancer cases, along with their corresponding normal samples were investigated in relation to the expression of the seven studied miRNAs using qPCR Syber Green.

Results

We observed that miR-21, miR-146a and miR-182 were significantly over expressed in triple negative breast cancer. Moreover, miR-10b, miR-21 and miR-182 were significantly associated to lymph node metastases occurrence in triple negative breast carcinoma while only miR-10b was associated with grade III in non triple negative breast cancer cases. Almost all the analyzed microRNAs were strongly associated with patients’ genico-obstetric history in non triple negative breast cancer cases except for miR-34a. All the studied microRNAs were strongly correlated with the use of the contraceptive pills in non triple negative breast cancer groups. The additive effect of hormonal factors in triple negative breast cancer cases showed an association with all the studied miRs except for miR-34 and miR-146a.

Conclusion

The studied microRNAs are strongly influenced by environmental factors especially with hormonal patients’ history. Moreover, miR-10b, miR-21 and miR-182 could be defined as biomarkers in breast cancer to predict both lymph node metastases and grade III occurrence.

Anti-miR182 reduces ovarian cancer burden, invasion, and metastasis: an in vivo study in orthotopic xenografts of nude mice

High-grade serous ovarian carcinoma (HGSOC) is a fatal disease, and its grave outcome is largely because of widespread metastasis at the time of diagnosis. Current chemotherapies reduce tumor burden, but they do not provide long-term benefits for patients with cancer. The aggressive tumor growth and metastatic behavior characteristic of these tumors demand novel treatment options such as anti-microRNA treatment, which is emerging as a potential modality for cancer therapy. MicroRNA-182 (miR182) overexpression contributes to aggressive ovarian cancer, largely by its negative regulation of multiple tumor suppressor genes involved in tumor growth, invasion, metastasis, and DNA instability. In this study, we examined the therapeutic potential of anti-miR182 utilizing the animal orthotopic model to mimic human ovarian cancer using ovarian cancer cells SKOV3 (intrabursal xenografts) and OVCAR3 (intraperitoneal injection). These models provide a valuable model system for the investigation of ovarian cancer therapy in vivo. Through a combination of imaging, histological, and molecular analyses, we found that anti-miR182 treatment can significantly reduce tumor burden (size), local invasion, and distant metastasis compared with its control in both models. The bases of anti-miR182 treatment are mainly through the restoration of miR182 target expression, including but not limited to BRCA1, FOXO3a, HMGA2, and MTSS1. Overall, our results strongly suggest that anti-miR182 can potentially be used as a therapeutic modality in treating HGSOC.

Polarity gene alterations in pure invasive micropapillary carcinomas of the breast

INTRODUCTION

Pure invasive micropapillary carcinoma (IMPC) is a special type of breast carcinoma characterised by clusters of cells presenting polarity abnormalities. The biological alterations underlying this pattern remain unknown.

METHODS

Pangenomic analysis (n=39), TP53 (n=43) and PIK3CA (n=41) sequencing in a series of IMPCs were performed. A subset of cases was also analysed with whole-exome sequencing (n=4) and RNA sequencing (n=6). Copy number variation profiles were compared with those of oestrogen receptors and grade-matched invasive ductal carcinomas (IDCs) of no special type.

RESULTS

Unsupervised analysis of genomic data distinguished two IMPC subsets: one (Sawtooth/8/16) exhibited a significant increase in 16p gains (71%), and the other (Firestorm/Amplifier) was characterised by a high frequency of 8q (35%), 17q (20% to 46%) and 20q (23% to 30%) amplifications and 17p loss (74%). TP53 mutations (10%) were more frequently identified in the amplifier subset, and PIK3CA mutations (4%) were detected in both subsets. Compared to IDC, IMPC exhibited specific loss of the 6q16-q22 region (45%), which is associated with downregulation of FOXO3 and SEC63 gene expression. SEC63 and FOXO3 missense mutations were identified in one case each (2%). Whole-exome sequencing combined with RNA sequencing of IMPC allowed us to identify somatic mutations in genes involved in polarity, DNAH9 and FMN2 (8% and 2%, respectively) or ciliogenesis, BBS12 and BBS9 (2% each) or genes coding for endoplasmic reticulum protein, HSP90B1 and SPTLC3 (2% each) and cytoskeleton, UBR4 and PTPN21 (2% each), regardless of the genomic subset. The intracellular biological function of the mutated genes identified by gene ontology analysis suggests a driving role in the clinicopathological characteristics of IMPC.

CONCLUSION

In our comprehensive molecular analysis of IMPC, we identified numerous genomic alterations without any recurrent fusion genes. Recurrent somatic mutations of genes participating in cellular polarity and shape suggest that they, together with other biological alterations (such as epigenetic modifications and stromal alterations), could contribute to the morphological pattern of IMPC. Though none of the individual abnormalities demonstrated specificity for IMPC, whether their combination in IMPC may have a cumulative effect that drives the abnormal polarity of IMPC needs to be examined further with in vitro experiments.

HMGA2 and high-grade serous ovarian carcinoma

HMGA2, the High Mobility Group A2 gene, plays a very important role in fetal development and carcinogenesis. As an oncofetal gene, it is upregulated in tumors of both epithelial and mesenchymal tissue origin. Chromosomal translocations of HMGA2 are common in mesenchymal tumors, whereas the regulatory mechanisms of HMGA2 in malignant epithelial tumors are much more complex. As an architectural transcription factor, it is involved in multiple biological pathways by targeting different downstream genes in different cancers. HMGA2 is upregulated in both the early and late stages of high-grade serous ovarian carcinoma (HGSOC) and, according to The Cancer Genomic Atlas, is among a signature of genes overexpressed in ovarian cancer. Recent identification of miR-182 as a mediator of BRCA1 and HMGA2 deregulation in ovarian cancer cells may guide us toward a better understanding of the roles of HMGA2 in ovarian carcinogenesis. In this article, we will review recent developments and findings related to HMGA2, including its regulation, oncogenic properties, major functional pathways associated with the tumorigenesis of HGSOC, and its potential role as a biomarker for clinical application.

Microenvironmental regulation of BRCA1 gene expression by c-Jun and Fra2 in premalignant human ovarian surface epithelial cells

Reduced BRCA1 gene expression is common in the sporadic form of ovarian carcinoma. The spread of this highly lethal cancer often begins when tumor cell clusters are shed into the fluid of the abdominopelvic cavity such that they can float freely before seeding distant sites on the peritoneal walls and organs. Thus, the microenvironment that tumor cells find themselves in changes dramatically during these early shedding and floating stages of transperitoneal metastasis. To mimic this microenvironmental change in vitro, we released premalignant human ovarian surface epithelial cells from the substratum and forced them to cluster in suspension. Under these conditions, steady state levels of BRCA1 mRNA and protein fell significantly and the transcriptional activation state of the BRCA1 promoter was suppressed. Analysis of the promoter indicated that the previously identified "CRE" element located within the "positive regulatory region" (PRR) contributed to this suppression. More specifically, we show that the suppression was mediated, at least in part, by a suspension culture-driven decrease in the levels of two members of the AP1 transcription factor complex, c-Jun and Fra2, that bind to the CRE element. Therefore, a microenvironmental change that is manifested during the initial stages of ovarian carcinoma dissemination may, potentially, help suppress BRCA1 expression in sporadic tumors and thus promote their progression.

The upregulation of signal transducer and activator of transcription 5-dependent microRNA-182 and microRNA-96 promotes ovarian cancer cell proliferation by targeting forkhead box O3 upon leptin stimulation

Leptin overexpression contributes to the tumorigenesis of ovarian cancer. However, the functional mechanism and effects remain unclear. The aberrant expression of tumor-related microRNAs may play an important role in the development of cancer. In this report, we demonstrate that crosstalk between leptin and microRNA-182 and microRNA-96 affects the transformation and proliferation of ovarian cancer cells. Our results showed that leptin enhanced the colony formation of ovarian cancer cells in soft agar. A water-soluble tetrazolium salts assay revealed that leptin promoted ovarian cancer cell (SKOV3 and A2780 cells) proliferation in a time- and dose-dependent manner. The growth effects of leptin on ovarian cancer cells were mediated via the reduced expression of forkhead box O3 and its downstream targets p27 and Bim. We demonstrated that leptin upregulated miRNAs that target forkhead box O3 via luciferase reporter assay. Further examination indicated that only the inhibition of microRNA-182 and/or microRNA-96 rescued the expression of forkhead box O3 inhibited by leptin, and their mimics promoted the proliferation of ovarian cancer cells. Moreover, the signal transducer and activator of transcription 5 pathway, but not the signal transducer and activator of transcription 3 pathway, was implicated in the leptin-mediated expression of microRNA-182 and microRNA-96. In conclusion, our findings suggest that the upregulation of microRNA-182 and microRNA-96 targeting forkhead box O3 plays a significant role in the pro-proliferation effect of leptin on ovarian cancer cells, which might provide preliminary experimental clues for the development of new therapies against ovarian cancer.