A novel p70 S6 kinase-microRNA biogenesis axis mediates multicellular spheroid formation in ovarian cancer progression

Hsa-miR-21-5p and Hsa-miR-145-5p Expression: From Normal Tissue to Malignant Changes-Context-Dependent Correlation with Estrogen- and Hypoxia-Vascularization-Related Pathways Genes: A Pilot Study

Ovarian cancer (OC) is a severe gynecological malignancy with a high mortality rate among women worldwide. It is often diagnosed at advanced stages due to the lack of effective screening methods. This study investigated the expression patterns of microRNAs (miRNAs) hsa-miR-21-5p and hsa-miR-145-5p as potential OC prognostic and diagnostic biomarkers and their correlation with estrogen-dependent (ESR1 & 2, PELP1 and c-SRC) and hypoxia-neovascularization-induced (HIF1A, EPAS1, and VEGFA) pathway genes. Tissue samples obtained from twenty patients with confirmed ovarian cancer and twenty controls were analyzed using quantitative polymerase chain reaction (qPCR) to examine miRNA and mRNA levels. The qPCR analysis revealed significantly higher hsa-miR-21-5p and lower hsa-miR-145-5p expression in OC tissues than controls. Moreover, a significant trend was observed in hsa-miR-21-5p and hsa-miR-145-5p expression levels across normal, non-cancerous changes and malignant ovarian tissues. The hsa-miR-21-5p showed better diagnostic potential than hsa-miR-145-5p. We also observed inconsistent correlations in hsa-miR-21-5p and hsa-mir-145-5p and estrogen-related and hypoxia-neovascularization-dependent genes in ovarian cancer across all groups. This suggests that the relationship between these miRNAs and the selected genes is context-specific. Our findings suggest that hsa-miR-21-5p and hsa-miR-145-5p expression levels may be prognostic or diagnostic markers for ovarian cancer patients.

Vertical inhibition of p110α/AKT and N-cadherin enhances treatment efficacy in PIK3CA-aberrated ovarian cancer cells

Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha [PIK3CA, encoding PI3Kalpha (also known as p110α)] is one of the most commonly aberrated genes in human cancers. In serous ovarian cancer, PIK3CA amplification is highly frequent but PIK3CA point mutation is rare. However, whether PIK3CA amplification and PIK3CA driver mutations have the same functional impact in the disease is unclear. Here, we report that both PIK3CA amplification and E545K mutation are tumorigenic. While the protein kinase B (AKT) signaling axis was activated in both E545K knock-in cells and PIK3CA-overexpressing cells, the mitogen-activated protein kinase 3/1 (ERK1/2) pathway was induced selectively by E545K mutation but not PIK3CA amplification. Intriguingly, AKT signaling in these PIK3CA-aberrated cells increased transcriptional coactivator YAP1 (YAP) Ser127 phosphorylation and thereby cytoplasmic YAP levels, which in turn increased cell migration through Ras-related C3 botulinum toxin substrate 1 (RAC1) activation. In addition to the altered YAP signaling, AKT upregulated N-cadherin expression, which also contributed to cell migration. Pharmacological inhibition of N-cadherin reduced cell migratory potential. Importantly, co-targeting N-cadherin and p110α/AKT caused additive reduction in cell migration in vitro and metastases formation in vivo. Together, this study reveals the molecular pathways driven by the PIK3CA aberrations and the exploitable vulnerabilities in PIK3CA-aberrated serous ovarian cancer cells.

P-cadherin mechanoactivates tumor-mesothelium metabolic coupling to promote ovarian cancer metastasis

Cancer adhesion to the mesothelium is critical for peritoneal metastasis, but how metastatic cells adapt to the biomechanical microenvironment remains unclear. Our study demonstrates that highly metastatic (HM), but not non-metastatic, ovarian cancer cells selectively activate the peritoneal mesothelium. HM cells exert a stronger adhesive force on mesothelial cells via P-cadherin, an adhesion molecule abundant in late-stage tumors. Mechanical activation of P-cadherin enhances lipogenic gene expression and lipid content in HM cells through SREBP1. P-cadherin also induces glycolysis in the interacting mesothelium without affecting lipogenic activity, with the resulting lactate serving as a substrate for lipogenesis in HM cells. Nanodelivery of small interfering RNA (siRNA) targeting P-cadherin or MCT1/4 transporters significantly suppresses metastasis in mice. Moreover, increased fatty acid synthase levels in metastatic patient samples correlate with high P-cadherin expression, supporting enhanced de novo lipogenesis in the metastatic niche. This study reveals P-cadherin-mediated mechano-metabolic coupling as a promising target to restrain metastasis.

Research progress of epithelial-mesenchymal transformation-related transcription factors in peritoneal metastases

Metastasis is the leading cause of mortality in patients with malignant tumors, particularly characterized by peritoneal metastases originating from gastric, ovarian, and colorectal cancers. Regarded as the terminal phase of tumor progression, peritoneal metastasis presents limited therapeutic avenues and is associated with a dismal prognosis for patients. The epithelial-mesenchymal transition (EMT) is a crucial phenomenon in which epithelial cells undergo significant changes in both morphology and functionality, transitioning to a mesenchymal-like phenotype. This transition plays a pivotal role in facilitating tumor metastasis, with transcription factors being key mediators of EMT's effects. Consequently, we provide a retrospective summary of the efforts to identify specific targets among EMT-related transcription factors, aimed at modulating the onset and progression of peritoneal metastatic cancer. This summary offers vital theoretical underpinnings for developing treatment strategies against peritoneal metastasis.

Does the miR-105-1-Kisspeptin Axis Promote Ovarian Cell Functions?

The objective of this study was to elucidate the intricate interplay among miR-105-1, kisspeptin, and their synergistic influence on basic ovarian granulosa cell functions. The effects of miR-105-1 mimics or miR-105-1 inhibitor, kisspeptin (0, 1, and 10 ng/ml), and its combinations with miR-105-1 mimics on porcine granulosa cells were assessed. The expression levels of miR-105-1, viability, proliferation (accumulation of PCNA, cyclin B1, XTT-, and BrdU-positive cells), apoptosis (accumulation of bcl-2, bax, caspase 3, p53, TUNEL-positive cells), proportion of kisspeptin-positive cells, and the release of steroid hormones and IGF-I were analyzed. Transfection of cells with miR-105-1 mimics promoted cell viability and proliferation, the occurrence of kisspeptin, and the release of progesterone and IGF-I; in contrast, miR-105-1 mimics inhibited apoptosis and estradiol output. MiR-105-1 inhibitor had the opposite effect. Kisspeptin amplified the expression of miR-105-1, cell viability, proliferation, steroid hormones, and IGF-I release and reduced apoptosis. Furthermore, the collaborative action of miR-105-1 mimics and kisspeptin revealed a synergistic relationship wherein miR-105-1 mimics predominantly supported the actions of kisspeptin, while kisspeptin exhibited a dual role in modulating the effects of miR-105-1 mimics. These findings not only affirm the pivotal role of kisspeptin in regulating basic ovarian cell functions but also represent the inaugural evidence underscoring the significance of miR-105-1 in this regulatory framework. Additionally, our results show the ability of kisspeptin to promote miR-105-1 expression and the ability of miR-105-1 to promote the occurrence and effects of kisspeptin and, therefore, indicate the existence of the self-stimulating kisspeptin-miR-105-1 axis.

miRNA on the Battlefield of Cancer: Significance in Cancer Stem Cells, WNT Pathway, and Treatment

Carcinogenesis is a complex process characterized by intricate changes in organ histology, biochemistry, epigenetics, and genetics. Within this intricate landscape, cancer stem cells (CSCs) have emerged as distinct cell types possessing unique attributes that significantly contribute to the pathogenesis of cancer. The WNT signaling pathway plays a critical role in maintaining somatic stem cell pluripotency. However, in cancer, overexpression of WNT mediators enhances the activity of β-catenin, resulting in phenomena such as recurrence and unfavorable survival outcomes. Notably, CSCs exhibit heightened WNT signaling compared to bulk cancer cells, providing intriguing insights into their functional characteristics. MicroRNAs (miRNAs), as post-transcriptional gene expression regulators, modulate various physiological processes in numerous diseases including cancer. Upregulation or downregulation of miRNAs can affect the production of pro-oncogenic or anti-oncogenic proteins, influencing cellular processes that maintain tissue homeostasis and promote either apoptosis or differentiation, even in cancer cells. In order to understand the dysregulation of miRNAs, it is essential to examine miRNA biogenesis and any possible alterations at each step. The potential of a miRNA as a biomarker in prognosis, diagnosis, and detection is being assessed using technologies such as next-generation sequencing. Extensive research has explored miRNA expression profiles in cancer, leading to their utilization as diagnostic tools and the development of personalized and targeted cancer therapies. This review delves into the role of miRNAs in carcinogenesis in relation to the WNT signaling pathway along with their potential as druggable compounds.

Mechanisms of Regulation of the Expression of miRNAs and lncRNAs by Metformin in Ovarian Cancer

Ovarian cancer (OC) is one of the most lethal gynecological malignancies. The use of biological compounds such as non-coding RNAs (ncRNAs) is being considered as a therapeutic option to improve or complement current treatments since the deregulation of ncRNAs has been implicated in the pathogenesis and progression of OC. Old drugs with antitumoral properties have also been studied in the context of cancer, although their antitumor mechanisms are not fully clear. For instance, the antidiabetic drug metformin has shown pleiotropic effects in several in vitro models of cancer, including OC. Interestingly, metformin has been reported to regulate ncRNAs, which could explain its diverse effects on tumor cells. In this review, we discuss the mechanism of epigenetic regulation described for metformin, with a focus on the evidence of metformin-dependent microRNA (miRNAs) and long non-coding RNA (lncRNAs) regulation in OC.

Genetic and Functional Modifications Associated with Ovarian Cancer Cell Aggregation and Limited Culture Conditions

The aggregation of cancer cells provides a survival signal for disseminating cancer cells; however, the underlying molecular mechanisms have yet to be elucidated. Using qPCR gene arrays, this study investigated the changes in cancer-specific genes as well as genes regulating mitochondrial quality control, metabolism, and oxidative stress in response to aggregation and hypoxia in our progressive ovarian cancer models representing slow- and fast-developing ovarian cancer. Aggregation increased the expression of anti-apoptotic, stemness, epithelial-mesenchymal transition (EMT), angiogenic, mitophagic, and reactive oxygen species (ROS) scavenging genes and functions, and decreased proliferation, apoptosis, metabolism, and mitochondrial content genes and functions. The incorporation of stromal vascular cells (SVF) from obese mice into the spheroids increased DNA repair and telomere regulatory genes that may represent a link between obesity and ovarian cancer risk. While glucose had no effect, glutamine was essential for aggregation and supported proliferation of the spheroid. In contrast, low glucose and hypoxic culture conditions delayed adhesion and outgrowth capacity of the spheroids independent of their phenotype, decreased mitochondrial mass and polarity, and induced a shift of mitochondrial dynamics towards mitophagy. However, these conditions did not reduce the appearance of polarized mitochondria at adhesion sites, suggesting that adhesion signals that either reversed mitochondrial fragmentation or induced mitobiogenesis can override the impact of low glucose and oxygen levels. Thus, the plasticity of the spheroids' phenotype supports viability during dissemination, allows for the adaptation to changing conditions such as oxygen and nutrient availability. This may be critical for the development of an aggressive cancer phenotype and, therefore, could represent druggable targets for clinical interventions.

PLK1 Regulates MicroRNA Biogenesis through Drosha Phosphorylation

Polo-Like Kinase 1 (PLK1), a key mediator of cell-cycle progression, is associated with poor prognosis and is a therapeutic target in a number of malignancies. Putative phosphorylation sites for PLK1 have been identified on Drosha, the main catalytic component of the microprocessor responsible for miR biogenesis. Several kinases, including GSK3β, p70 S6 kinase, ABL, PAK5, p38 MAPK, CSNK1A1 and ANKRD52-PPP6C, have been shown to phosphorylate components of the miR biogenesis machinery, altering their activity and/or localisation, and therefore the biogenesis of distinct miR subsets. We hypothesised that PLK1 regulates miR biogenesis through Drosha phosphorylation. In vitro kinase assays confirmed PLK1 phosphorylation of Drosha at S300 and/or S302. PLK1 inhibition reduced serine-phosphorylated levels of Drosha and its RNA-dependent association with DGCR8. In contrast, a "phospho-mimic" Drosha mutant showed increased association with DGCR8. PLK1 phosphorylation of Drosha alters Drosha Microprocessor complex subcellular localisation, since PLK1 inhibition increased cytosolic protein levels of both DGCR8 and Drosha, whilst nuclear levels were decreased. Importantly, the above effects are independent of PLK1's cell cycle-regulatory role, since altered Drosha:DGCR8 localisation upon PLK1 inhibition occurred prior to significant accumulation of cells in M-phase, and PLK1-regulated miRs were not increased in M-phase-arrested cells. Small RNA sequencing and qPCR validation were used to assess downstream consequences of PLK1 activity on miR biogenesis, identifying a set of ten miRs (miR-1248, miR-1306-5p, miR-2277-5p, miR-29c-5p, miR-93-3p, miR-152-3p, miR-509-3-5p, miR-511-5p, miR-891a-5p and miR-892a) whose expression levels were statistically significantly downregulated by two pharmacological PLK1 kinase domain inhibitors, RO-5203280 and GSK461364. Opposingly, increased levels of these miRs were observed upon transfection of wild-type or constitutively active PLK1. Importantly, pre-miR levels were reduced upon PLK1 inhibition, and pri-miR levels decreased upon PLK1 activation, and hence, PLK1 Drosha phosphorylation regulates MiR biogenesis at the level of pri-miR-to-pre-miR processing. In combination with prior studies, this work identifies Drosha S300 and S302 as major integration points for signalling by several kinases, whose relative activities will determine the relative biogenesis efficiency of different miR subsets. Identified kinase-regulated miRs have potential for use as kinase inhibitor response-predictive biomarkers, in cancer and other diseases.

Nanotechnology-integrated ovarian cancer metastasis therapy: Insights from the metastatic mechanisms into administration routes and therapy strategies

Ovarian cancer is a kind of malignant tumour which locates in the pelvic cavity without typical clinical symptoms in the early stages. Most patients are diagnosed in the late stage while about 60 % of them have suffered from the cancer cells spreading in the abdominal cavity. The high recurrence rate and mortality seriously damage the reproductive needs and health of women. Although recent advances in therapeutic regimes and other adjuvant therapies improved the overall survival of ovarian cancer, overcoming metastasis has still been a challenge and is necessary for achieving cure of ovarian cancer. To present potential targets and new strategies for curbing the occurrence of ovarian metastasis and the treatment of ovarian cancer after metastasis, the first section of this paper explained the metastatic mechanisms of ovarian cancer comprehensively. Nanomedicine, not limited to drug delivery, offers opportunities for metastatic ovarian cancer therapy. The second section of this paper emphasized the advantages of various administration routes of nanodrugs in metastatic ovarian cancer therapy. Furthermore, the third section of this paper focused on advances in nanotechnology-integrated strategies for targeting metastatic ovarian cancer based on the metastatic mechanisms of ovarian cancer. Finally, the challenges and prospects of nanotherapeutics for ovarian cancer metastasis therapy were evaluated. In general, the greatest emphasis on using nanotechnology-based strategies provides avenues for improving metastatic ovarian cancer outcomes in the future.

MicroRNAs, Tristetraprolin Family Members and HuR: A Complex Interplay Controlling Cancer-Related Processes

Simple Summary

AU-rich Element Binding Proteins (AUBPs) represent important post-transcriptional regulators of gene expression by regulating mRNA decay and/or translation. Importantly, AUBPs can interfere with microRNA-dependent regulation by (i) competing with the same binding sites on mRNA targets, (ii) sequestering miRNAs, thereby preventing their binding to their specific targets or (iii) promoting miRNA-dependent regulation. These data highlight a new paradigm where both miRNA and RNA binding proteins form a complex regulatory network involved in physiological and pathological processes. However, this interplay is still poorly considered, and our current models do not integrate this level of complexity, thus potentially giving misleading interpretations regarding the role of these regulators in human cancers. This review summarizes the current knowledge regarding the crosstalks existing between HuR, tristetraprolin family members and microRNA-dependent regulation.

Abstract

MicroRNAs represent the most characterized post-transcriptional regulators of gene expression. Their altered expression importantly contributes to the development of a wide range of metabolic and inflammatory diseases but also cancers. Accordingly, a myriad of studies has suggested novel therapeutic approaches aiming at inhibiting or restoring the expression of miRNAs in human diseases. However, the influence of other trans-acting factors, such as long-noncoding RNAs or RNA-Binding-Proteins, which compete, interfere, or cooperate with miRNAs-dependent functions, indicate that this regulatory mechanism is much more complex than initially thought, thus questioning the current models considering individuals regulators. In this review, we discuss the interplay existing between miRNAs and the AU-Rich Element Binding Proteins (AUBPs), HuR and tristetraprolin family members (TTP, BRF1 and BRF2), which importantly control the fate of mRNA and whose alterations have also been associated with the development of a wide range of chronic disorders and cancers. Deciphering the interplay between these proteins and miRNAs represents an important challenge to fully characterize the post-transcriptional regulation of pro-tumorigenic processes and design new and efficient therapeutic approaches.

p70 S6 kinase as a therapeutic target in cancers: More than just an mTOR effector

p70 S6 kinase (p70^S6K) is best-known for its regulatory roles in protein synthesis and cell growth by phosphorylating its primary substrate, ribosomal protein S6, upon mitogen stimulation. The enhanced expression/activation of p70^S6K has been correlated with poor prognosis in some cancer types, suggesting that it may serve as a biomarker for disease monitoring. p70^S6K is a critical downstream effector of the oncogenic PI3K/Akt/mTOR pathway and its activation is tightly regulated by an ordered cascade of Ser/Thr phosphorylation events. Nonetheless, it should be noted that other upstream mechanisms regulating p70^S6K at both the post-translational and post-transcriptional levels also exist. Activated p70^S6K could promote various aspects of cancer progression such as epithelial-mesenchymal transition, cancer stemness and drug resistance. Importantly, novel evidence showing that p70^S6K may also regulate different cellular components in the tumor microenvironment will be discussed. Therapeutic targeting of p70^S6K alone or in combination with traditional chemotherapies or other microenvironmental-based drugs such as immunotherapy may represent promising approaches against cancers with aberrant p70^S6K signaling. Currently, the only clinically available p70^S6K inhibitors are rapamycin analogs (rapalogs) which target mTOR. However, there are emerging p70^S6K-selective drugs which are going through active preclinical or clinical trial phases. Moreover, various screening strategies have been used for the discovery of novel p70^S6K inhibitors, hence bringing new insights for p70^S6K-targeted therapy.

SOX9: Advances in Gynecological Malignancies

Transcription factors of the SOX family were first discovered in mammals in 1990. The sex-determining region Y box 9 belongs to the SOX transcription factor family. It plays an important role in inducing tissue and cell morphogenesis, survival, and many developmental processes. Furthermore, it has been shown to be an oncogene in many tumors. Gynecological malignancies are tumors that occur in the female reproductive system and seriously threaten the lives of patients. Common gynecological malignancies include ovarian cancer, cervical cancer, and endometrial cancer. So far, the molecular mechanisms related to the incidence and development of gynecological malignancies remain unclear. This makes it particularly important to discover their common causative molecule and thus provide an effective therapeutic target. In recent years, studies have found that multiple mechanisms are involved in regulating the expression of the sex-determining region Y box 9, leading to the occurrence and development of gynecological malignancies. In this review, we discuss the prognostic value of SOX9 expression and the potential of targeting SOX9 for gynecological malignancy treatment. We also discuss progress regarding the role of SOX9 in gynecological malignancy pathogenesis through its mediation of important mechanisms, including tumor initiation and proliferation, apoptosis, migration, invasion, chemoresistance, and stem cell maintenance.

Crosstalk between oral squamous cell carcinoma cells and cancer-associated fibroblasts via the TGF-β/SOX9 axis in cancer progression

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TGF-β1 secreted from CAFs promote the migration and invasion of OSCC cells.

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CAFs upregulate SOX9 expression of OSCC cells, possibly through inducing EMT.

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The presence of CAFs is correlated with SOX9 expression in the invasive cancer nests.

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The TGF-β/SOX9 axis between CAFs and OSCC cells facilitates cancer progression.

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Targeting the TGF-β/SOX9 axis could be a potential novel target for OSCC.

Cancer-associated fibroblasts (CAFs) have important roles in promoting cancer development and progression. We previously reported that high expression of sex-determining region Y (SRY)-box9 (SOX9) in oral squamous cell carcinoma (OSCC) cells was positively correlated with poor prognosis. This study developed three-dimensional (3D) in vitro models co-cultured with OSCC cells and CAFs to examine CAF-mediated cancer migration and invasion in vitro and in vivo. Moreover, we performed an immunohistochemical analysis of alpha-smooth muscle actin and SOX9 expression in surgical specimens from 65 OSCC patients. The results indicated that CAFs promote cancer migration and invasion in migration assays and 3D in vitro models. The invading OSCC cells exhibited significant SOX9 expression and changes in the expression of epithelial–mesenchymal transition (EMT) markers, suggesting that SOX9 promotes EMT. TGF-β1 signalling inhibition reduced SOX9 expression and cancer invasion in vitro and in vivo, indicating that TGF-β1-mediated invasion is dependent on SOX9. In surgical specimens, the presence of CAFs was correlated with SOX9 expression in the invasive cancer nests and had a significant impact on regional recurrence. These findings demonstrate that CAFs promote cancer migration and invasion via the TGF-β/SOX9 axis.

Tristetraprolin, a Potential Safeguard Against Carcinoma: Role in the Tumor Microenvironment

Tristetraprolin (TTP), a well-known RNA-binding protein, primarily affects the expression of inflammation-related proteins by binding to the targeted AU-rich element in the 3' untranslated region after transcription and subsequently mediates messenger RNA decay. Recent studies have focused on the role of TTP in tumors and their related microenvironments, most of which have referred to TTP as a potential tumor suppressor involved in regulating cell proliferation, apoptosis, and metastasis of various cancers, as well as tumor immunity, inflammation, and metabolism of the microenvironment. Elevated TTP expression levels could aid the diagnosis and treatment of different cancers, improving the prognosis of patients. The aim of this review is to describe the role of TTP as a potential safeguard against carcinoma.

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.

Transcriptomic analysis reveals the oncogenic role of S6K1 in hepatocellular carcinoma

The p70 ribosomal protein S6 kinase 1 (S6K1), a serine/threonine kinase, is commonly overexpressed in a variety of cancers. However, its expression level and functional roles in hepatocellular carcinoma (HCC), which ranks as the third leading cause of cancer-related death worldwide, is still largely unknown. In the current report, we show the in vivo and in vitro overexpression of S6K1 in HCC. In the functional analysis, we demonstrate that S6K1 is required for the proliferation and colony formation abilities in HCC. By using comparative transcriptomic analysis followed by gene ontology enrichment analysis and Ingenuity Pathway Analysis, we find that the depletion of S6K1 can elevate the expression of a cluster of apoptotic genes, tumor suppressor genes and immune responsive genes. Moreover, the knockdown of S6K1 is predicted to reduce the tumorigenicity of HCC through the regulation of hubs of genes including STAT1, HDAC4, CEBPA and ONECUT1. In conclusion, we demonstrate the oncogenic role of S6K1 in HCC, suggesting the possible use of S6K1 as a therapeutic target for HCC treatment.

Deciphering the Molecular Basis of Melatonin Protective Effects on Breast Cells Treated with Doxorubicin: TWIST1 a Transcription Factor Involved in EMT and Metastasis, a Novel Target of Melatonin

Melatonin mitigates cancer initiation, progression and metastasis through inhibition of both the synthesis of estrogens and the transcriptional activity of the estradiol-ER (Estrogen receptor) complex in the estrogen-dependent breast cancer cell line MCF-7. Moreover, melatonin improves the sensitivity of MCF-7 to chemotherapeutic agents and protects against their side effects. It has been described that melatonin potentiates the anti-proliferative effects of doxorubicin; however, the molecular changes involving gene expression and the activation/inhibition of intracellular signaling pathways remain largely unknown. Here we found that melatonin enhanced the anti-proliferative effect of doxorubicin in MCF-7 but not in MDA-MB-231 cells. Strikingly, doxorubicin treatment induced cell migration and invasion, and melatonin effectively counteracted these effects in MCF-7 but not in estrogen-independent MDA-MB-231 cells. Importantly, we describe for the first time the ability of melatonin to downregulate TWIST1 (Twist-related protein 1) in estrogen-dependent but not in estrogen-independent breast cancer cells. Combined with doxorubicin, melatonin inhibited the activation of p70S6K and modulated the expression of breast cancer, angiogenesis and clock genes. Moreover, melatonin regulates the levels of TWIST1-related microRNAs, such as miR-10a, miR-10b and miR-34a. Since TWIST1 plays a pivotal role in the epithelial to mesenchymal transition, acquisition of metastatic phenotype and angiogenesis, our results suggest that inhibition of TWIST1 by melatonin might be a crucial mechanism of overcoming resistance and improving the oncostatic potential of doxorubicin in estrogen-dependent breast cancer cells.

miR-145 is a potential biomarker for predicting clinical outcome in glioblastomas

miR-145 has been found to be significantly downregulated in gliomas, and overexpression of miR-145 increases glioma cell apoptosis and enhances chemosensitivity or herpes simplex virus thymidine kinase gene therapy. However, the correlation between miR-145 and the clinical prognosis of glioblastomas has never been explored. In this study, a retrospective study was conducted in 86 cases of patients with glioblastoma after neurosurgery combined with chemoradiotherapy, and 36 cases with traumatic brain injury. Our results showed that miR-145 was significantly lower in glioblastoma tissues than that in normal brain tissue (P < 0.05). Furthermore, miR-145 was lower in patients with lower Karnofsky Performance Scale (KPS) scores than in patients with higher KPS scores ( P < 0.05). Cox Regression analysis showed that low miR-145 expression was associated with poor patient survival ( P < 0.05). These data suggested that patients with glioblastoma with lower miR-145 expression are prone to shorter overall survival.

siRNA-Conjugated Nanoparticles to Treat Ovarian Cancer

Ovarian cancer is the fifth-most lethal cancer among women due to a lack of early detection and late-stage treatment options, and it is responsible for more than 14,000 deaths each year in the United States. Recently, there have been advances in RNA interference therapy, specifically with small interfering RNA (siRNA), to reduce tumor burden for ovarian cancer via gene down-regulation. However, delivery of siRNA poses its own challenges, as siRNA is unstable in circulation, is unable to be effectively internalized by cells, and may cause toxicity in off-target sites. To address such challenges, nanoparticle carriers have emerged as delivery platforms for the biocompatible, targeted delivery of siRNA-based therapies. Several preclinical studies have shown the promising effects of siRNA therapy to reduce chemotherapy resistance and proliferation of ovarian cancer cells. This review evaluates the recent advances, clinical applications, and future potential of nanoparticle-mediated delivery of siRNA therapeutics to target genes implicated in ovarian cancer.

The Prognostic Value and Regulatory Mechanisms of microRNA-145 in Various Tumors: A Systematic Review and Meta-analysis of 50 Studies

Acting as an important tumor-related miRNA, the clinical significance and underlying mechanisms of miR-145 in various malignant tumors have been investigated by numerous studies. This study aimed to comprehensively estimate the prognostic value and systematically illustrate the regulatory mechanisms of miR-145 based on all eligible literature.Relevant studies were acquired from multiple online databases. Overall survival (OS) and progression-free survival (PFS) were used as primary endpoints. Detailed subgroup analyses were performed to decrease the heterogeneity among studies and recognize the prognostic value of miR-145. All statistical analyses were performed with RevMan software version 5.3 and STATA software version 14.1. A total of 48 articles containing 50 studies were included in the meta-analysis. For OS, the pooled results showed that low miR-145 expression in tumor tissues was significantly associated with worse OS in patients with various tumors [HR = 1.70; 95% confidence interval (CI), 1.46-1.99; P < 0.001). Subgroup analysis based on tumor type showed that the downregulation of miR-145 was associated with unfavorable OS in colorectal cancer (HR = 2.17; 95% CI, 1.52-3.08; P < 0.001), ovarian cancer (HR = 2.15; 95% CI, 1.29-3.59; P = 0.003), gastric cancer (HR = 1.78; 95% CI, 1.35-2.36; P < 0.001), glioma (HR = 1.65; 95% CI, 1.30-2.10; P < 0.001), and osteosarcoma (HR = 2.28; 95% CI, 1.50-3.47; P < 0.001). For PFS, the pooled results also showed that the downregulation of miR-145 was significantly associated with poor PFS in patients with multiple tumors (HR = 1.39; 95% CI, 1.16-1.67; P < 0.001), and the subgroup analyses further identified that the low miR-145 expression was associated with worse PFS in patients with lung cancer (HR = 1.97; 95% CI, 1.25-3.09; P = 0.003) and those of Asian descent (HR = 1.50; 95% CI, 1.23-1.82; P < 0.001). For the regulatory mechanisms, we observed that numerous tumor-related transcripts could be targeted by miR-145-5p or miR-145-3p, as well as the expression and function of miR-145-5p could be regulated by multiple molecules.This meta-analysis indicated that downregulated miR-145 in tumor tissues or peripheral blood predicted unfavorable prognostic outcomes for patients suffering from various malignant tumors. In addition, miR-145 was involved in multiple tumor-related pathways and the functioning of significant biological effects. miR-145 is a well-demonstrated tumor suppressor, and its expression level is significantly correlated with the prognosis of patients with multiple malignant tumors.

MicroRNA-138 inhibits SOX12 expression and the proliferation, invasion and migration of ovarian cancer cells

The aim of the present study was to investigate the expression and biological functions of microRNA (miR)-138 in ovarian cancer at the tissue and cellular levels, as well as its underlying mechanisms. A total of 47 patients with ovarian cancer were included in the present study. Ovarian cancer tissues were subjected to staging classification according to the FIGO 2000 criteria. Lymphatic metastasis was also examined. Ovarian cancer A2780 cells were transfected using liposomes. Reverse transcription-quantitative polymerase chain reaction was used to measure the expression of miR-138. A Cell-Counting Kit 8 assay was used to examine cell viability, while a Transwell assay was employed to study cell invasion and migration. The effects of miR-138 on SOX12 protein expression were examined by western blot analysis. A dual luciferase reporter assay was performed to identify the direct interaction between miR-138 and SOX12 gene. Expression of miR-138 was downregulated in ovarian cancer tissues. The level of miR-138 in patients with ovarian cancer with lymphatic metastasis was significantly lower compared with patients without lymphatic metastasis. However, expression of miR-138 was not associated with the stage of ovarian cancer. Upregulation of miR-138 inhibited the proliferation and suppressed the invasion and migration of A2780 cells. SOX12 promoted the proliferation, invasion and migration of A2780 cells. In addition, miR-138 downregulated the expression of SOX12 via binding with the 3′-UTR of SOX12 gene. The present study demonstrates that miR-138 expression is downregulated in ovarian cancer tissues and miR-138 acts as a tumor suppressor gene by inhibiting SOX12 expression and the proliferation, invasion and migration of ovarian cancer cells.

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.

Blocking Stemness and Metastatic Properties of Ovarian Cancer Cells by Targeting p70S6K with Dendrimer Nanovector-Based siRNA Delivery

Metastasis is the cause of most (>90%) cancer deaths and currently lacks effective treatments. Approaches to understanding the biological process, unraveling the most effective molecular target(s), and implementing nanotechnology to increase the therapeutic index are expected to facilitate cancer therapy against metastasis. Here, we demonstrate the potential advantages of bringing these three approaches together through the rational design of a small interfering RNA (siRNA) that targets p70^S6K in cancer stem cells (CSCs) in combination with dendrimer nanotechnology-based siRNA delivery. Our results demonstrated that the generation 6 (G₆) poly(amidoamine) dendrimer can be used as a nanovector to effectively deliver p70^S6K siRNA by forming uniform dendriplex nanoparticles that protect the siRNA from degradation. These nanoparticles were able to significantly knock down p70^S6K in ovarian CSCs, leading to a marked reduction in CSC proliferation and expansion without obvious toxicity toward normal ovarian surface epithelial cells. Furthermore, treatment with the p70^S6K siRNA/G₆ dendriplexes substantially decreased mesothelial interaction, migration and invasion of CSCs in vitro, as well as tumor growth and metastasis in vivo. Collectively, these results suggest that p70^S6K constitutes a promising therapeutic target, and the use of siRNA in combination with nanotechnology-based delivery may constitute a new approach for molecularly targeted cancer therapy to treat metastasis.

Molecular Mechanisms of Ovarian Carcinoma Metastasis: Key Genes and Regulatory MicroRNAs

Metastasis of primary tumors progresses stepwise - from change in biochemistry, morphology, and migratory patterns of tumor cells to the emergence of receptors on their surface that facilitate directional migration to target organs followed by the formation of a specific microenvironment in a target organ that helps attachment and survival of metastatic cells. A set of specific genes and signaling pathways mediate this process under control of microRNA. The molecular mechanisms underlying biological processes associated with tumor metastasis are reviewed in this publication using ovarian cancer, which exhibits high metastatic potential, as an example. Information and data on the genes and regulatory microRNAs involved in the formation of cancer stem cells, epithelial-mesenchymal transition, reducing focal adhesion, degradation of extracellular matrix, increasing migration activity of cancer cells, formation of spheroids, apoptosis, autophagy, angiogenesis, formation of metastases, and development of ascites are presented. Clusters of microRNAs (miR-145, miR-31, miR-506, miR-101) most essential for metastasis of ovarian cancer including the families of microRNAs (miR-200, miR-214, miR-25) with dual role, which is different in different histological types of ovarian cancer, are discussed in detail in a section of the review.

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

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