MicroRNA-145 inhibits the activation of the mTOR signaling pathway to suppress the proliferation and invasion of invasive pituitary adenoma cells by targeting AKT3 in vivo and in vitro

The microRNA-cell surface proteoglycan axis in cancer progression

Proteoglycans consist one of the major extracellular matrix class of biomolecules that demonstrate nodal roles in cancer progression. Μodern diagnostic and therapeutic approaches include proteoglycan detection and pharmacological targeting in various cancers. Proteoglycans orchestrate critical signaling pathways for cancer development and progression through dynamic interactions with matrix components. It is well established that the epigenetic signatures of cancer cells play critical role in guiding their functional properties and metastatic potential. Secreted microRNAs (miRNAs) reside in a complex network with matrix proteoglycans, thus affecting cell-cell and cell-matrix communication. This mini-review aims to highlight current knowledge on the proteoglycan-mediated signaling cascades that regulate miRNA biogenesis in cancer. Moreover, the miRNA-mediated proteoglycan regulation during cancer progression and mechanistic aspects on the way that proteoglycans affect miRNA expression are presented. Recent advances on the role of cell surface proteoglycans in exosome biogenesis and miRNA packaging and expression are also discussed.

Novel Insights into Pituitary Tumorigenesis: Genetic and Epigenetic Mechanisms

Substantial advances have been made recently in the pathobiology of pituitary tumors. Similar to many other endocrine tumors, over the last few years we have recognized the role of germline and somatic mutations in a number of syndromic or nonsyndromic conditions with pituitary tumor predisposition. These include the identification of novel germline variants in patients with familial or simplex pituitary tumors and establishment of novel somatic variants identified through next generation sequencing. Advanced techniques have allowed the exploration of epigenetic mechanisms mediated through DNA methylation, histone modifications and noncoding RNAs, such as microRNA, long noncoding RNAs and circular RNAs. These mechanisms can influence tumor formation, growth, and invasion. While genetic and epigenetic mechanisms often disrupt similar pathways, such as cell cycle regulation, in pituitary tumors there is little overlap between genes altered by germline, somatic, and epigenetic mechanisms. The interplay between these complex mechanisms driving tumorigenesis are best studied in the emerging multiomics studies. Here, we summarize insights from the recent developments in the regulation of pituitary tumorigenesis.

MiRNAs as Noninvasive Biomarkers and Therapeutic Agents of Pituitary Adenomas

Pituitary adenoma (PA) accounts for 10-15% of all intracranial neoplasms. Even though most pituitary adenomas are benign, it is known that almost 35% of them exhibit an aggressive clinical course, including rapid proliferative activity and invasion of neighboring tissues. MicroRNAs (miRNAs) are short single-stranded RNA molecules that can influence post-transcriptional regulation by controlling target genes. Based on research data on miRNAs over the past 20 years, more than 60% of genes encoding human proteins are regulated by miRNAs, which ultimately control basic cellular mechanisms, including cell proliferation, differentiation, and apoptosis. Dysregulation of miRNAs has been observed in a number of diseases, especially tumors like PA. A majority of miRNAs are expressed within the cells themselves. However, the circulating miRNAs can be detected in several biological fluids of the human body. The identification of circulating miRNAs as new molecular markers may increase the ability to detect a tumor, predict the course of a disease, plan to choose suitable treatment, and diagnose at the earliest signs of impending neoplastic transformation. Therapy of PAs with aggressive behavior is a complex task. When surgery and chemotherapy fail, radiotherapy becomes the treatment of choice against PAs. Therefore, the possibility of implementing circulating miRNAs as innovative diagnostic and therapeutic agents for PA is one of the main exciting ideas.

miR-34a is upregulated in AIP-mutated somatotropinomas and promotes octreotide resistance

Pituitary adenomas (PAs) are intracranial tumors associated with significant morbidity due to hormonal dysregulation, mass effects and have a heavy treatment burden. Growth hormone (GH)-secreting PAs (somatotropinomas) cause acromegaly-gigantism. Genetic forms of somatotropinomas due to germline AIP mutations (AIPmut+) have an early onset and are aggressive and resistant to treatment with somatostatin analogs (SSAs), including octreotide. The molecular underpinnings of these clinical features remain unclear. We investigated the role of miRNA dysregulation in AIPmut+ vs AIPmut- PA samples by array analysis. miR-34a and miR-145 were highly expressed in AIPmut+ vs AIPmut- somatotropinomas. Ectopic expression of AIPmut (p.R271W) in Aip^-/- mouse embryonic fibroblasts (MEFs) upregulated miR-34a and miR-145, establishing a causal link between AIPmut and miRNA expression. In PA cells (GH3), miR-34a overexpression promoted proliferation, clonogenicity, migration and suppressed apoptosis, whereas miR-145 moderately affected proliferation and apoptosis. Moreover, high miR-34a expression increased intracellular cAMP, a critical mitogenic factor in PAs. Crucially, high miR-34a expression significantly blunted octreotide-mediated GH inhibition and antiproliferative effects. miR-34a directly targets Gnai2 encoding Gαi2, a G protein subunit inhibiting cAMP production. Accordingly, Gαi2 levels were significantly lower in AIPmut+ vs AIPmut- PA. Taken together, somatotropinomas with AIP mutations overexpress miR-34a, which in turn downregulates Gαi2 expression, increases cAMP concentration and ultimately promotes cell growth. Upregulation of miR-34a also impairs the hormonal and antiproliferative response of PA cells to octreotide. Thus, miR-34a is a novel downstream target of mutant AIP that promotes a cellular phenotype mirroring the aggressive clinical features of AIPmut+ acromegaly.

miR‑320‑3p is involved in morphine pre‑conditioning to protect rat cardiomyocytes from ischemia/reperfusion injury through targeting Akt3

Morphine pre-conditioning (MPC) can significantly reduce myocardial ischemic injury and inhibit cardiomyocyte apoptosis, but the underlying mechanism still remains unclear. The aim of the present study was to investigate the protective mechanism of MPC in myocardial hypoxia/reoxygenation (H/R) injury at the microRNA (miR) level. H9c2 cells were used as a model of H/R and subjected to morphine pre-treatment. The protective effects of MPC on H/R injury in cardiomyocytes were evaluated using MTT and colorimetric assay, as well as flow cytometry. In addition, reverse transcription-quantitative PCR, western blotting and dual-luciferase reporter assay experiments were performed to determine the relationship between MPC, miR-320-3p and Akt3, and their effects on H/R injury. The present study demonstrated that MPC enhanced cell activity, decreased LDH content, and reduced apoptosis in rat cardiomyocytes, suggesting that MPC could protect these cells from H/R injury. Moreover, MPC partially reversed the increase in miR-320-3p expression and the decrease in Akt3 levels caused by H/R injury. Inhibition of miR-320-3p expression also attenuated the effects of H/R on cardiomyocyte activity, LDH content and apoptosis. Furthermore, Akt3 was predicted to be a target gene of miR-320-3p, and overexpression of miR-320-3p inhibited the expression of Akt3, blocking the protective effects of MPC on the cells. The current findings revealed that MPC could protect cardiomyocytes from H/R damage through targeting miR-320-3p to regulate the PI3K/Akt3 signaling pathway.

Multiomics-Based Signaling Pathway Network Alterations in Human Non-functional Pituitary Adenomas

Non-functional pituitary adenoma (NFPA) seriously affects hypothanamus-pituitary-target organ axis system, with a series of molecule alterations in the multiple levels of genome, transcriptome, proteome, and post-translational modifications, and those molecules mutually interact in a molecular-network system. Meta analysis coupled with IPA pathway-network program was used to comprehensively analyze nine sets of documented NFPA omics data, including NFPA quantitative transcriptomics data [280 differentially expressed genes (DEGs)], NFPA quantitative proteomics data [50 differentially expressed proteins (DEPs)], NFPA mapping protein data (218 proteins), NFPA mapping protein nitration data (9 nitroproteins and 3 non-nitrated proteins), invasive NFPA quantitative transriptomics data (346 DEGs), invasive NFPA quantitative proteomics data (57 DEPs), control mapping protein data (1469 proteins), control mapping protein nitration data (8 nitroproteins), and control mapping phosphorylation data (28 phosphoproteins). A total of 62 molecular-networks with 861 hub-molecules and 519 canonical-pathways including 54 cancer-related canonical pathways were revealed. A total of 42 hub-molecule panels and 9 canonical-pathway panels were identified to significantly associate with tumorigenesis. Four important molecular-network systems, including PI3K/AKT, mTOR, Wnt, and ERK/MAPK pathway-systems, were confirmed in NFPAs by PTMScan experiments with altered expression-patterns and phosphorylations. Nineteen high-frequency hub-molecules were also validated in NFPAs with PTMScan experiment with at least 2.5-fold changes in expression or phosphorylation, including ERK, ERK1/2, Jnk, MAPK, Mek, p38 MAPK, AKT, PI3K complex, p85, PKC, FAK, Rac, Shc, HSP90, NFκB Complex, histone H3, AP1, calmodulin, and PLC. Furthermore, mTOR and Wnt pathway-systems were confirmed in NFPAs by immunoaffinity Western blot analysis, with significantly decreased expression of PRAS40 and increased phosphorylation levels of p-PRAS40 (Thr246) in mTOR pathway in NFPAs compared to controls, and with the decreased protein expressions of GSK-3β and GSK-3β, significantly increased phosphorylation levels of p-GSK3α (Ser21) and p-GSK3β (Ser9), and increased expression level of β-catenin in Wnt pathway in NFPAs compared to controls. Those findings provided a comphrensive and large-scale pathway network data for NFPAs, and offer the scientific evidence for insights into the accurate molecular mechanisms of NFPA and discovery of the effective biomarkers for diagnosis, prognosis, and determination of therapeutic targets.

COL6A6 interacted with P4HA3 to suppress the growth and metastasis of pituitary adenoma via blocking PI3K-Akt pathway

The role and mechanism of collagen type VI alpha 6 (COL6A6) on tumor growth and metastasis in pituitary adenoma (PA) was determined. COL6A6 was downregulated in PA tissues and cell lines, which was negatively associated with the expression of prolyl-4-hydroxylase alpha polypeptide III (P4HA3) in the progression of PA. Overexpression of COL6A6 significantly suppressed tumor growth and metastasis capacity in PA. In addition, P4HA3 worked as the upstream of the PI3K-Akt pathway to alleviate the antitumor activity of COL6A6 on the growth and metastasis of both AtT-20 and HP75 cells. Furthermore, the inhibitory effect of COL6A6 on cell proliferation, migration and invasion, and epithelial-mesenchymal transition (EMT) was reversed by P4HA3 overexpression or activation of the PI3K-Akt pathway induced by IGF-1 addition, which provided a new biomarker for clinical PA treatment.

Emerging roles of microRNAs in regulating the mTOR signaling pathway during tumorigenesis

The mammalian target of rapamycin (mTOR) is a large Ser/Thr protein kinase that belongs to the phosphoinositide 3-kinase (PI3K) family and mediates various physiological and pathological processes, especially cell proliferation, protein synthesis, autophagy, and cancer development. The mTOR expression is transient and tightly regulated in normal cells, but it is overactivated in cancer cells. Recently, several studies have indicated that microRNAs (miRNAs) play a critical role in the regulation of mTOR and mTOR-associated processes, some acting as inhibitors and the others as activators. Although it is still in infancy, the strategy of combining both miRNAs and mTOR inhibitors might provide an approach to selectively sensitizing tumor cells to chemotherapy-induced DNA damage and subsequently attenuating the tumor cell growth and apoptosis.

A novel lncRNA n384546 promotes thyroid papillary cancer progression and metastasis by acting as a competing endogenous RNA of miR-145-5p to regulate AKT3

Long noncoding RNAs (lncRNAs) are emerging as important regulators in the development of cancer cells. However, the role and mechanisms of most lncRNAs in papillary thyroid carcinoma (PTC) remain unknown. In this study, we investigated lncRNA expression profiles of PTC using RNA-seq in two groups of PTC tissues and adjacent normal tissues, and validated by real-time PCR analysis in another 53 pairs of tissues. We identified a novel lncRNA, n384546, which is highly expressed in PTC tissues and cell lines. n384546 expression was associated with clinicopathological features of PTC patients, such as tumor size, lymph node metastasis, and TNM stage. Functionally, knockdown of n384546 inhibited PTC cell proliferation, invasion, and migration both in vitro and in vivo. In addition, we identified miR-145-5p as a key miRNA target of n384546 using online bioinformatics tools. Anti-miR-145 could partially reverse the effects of n384546 knockdown. Furthermore, we found that n384546 could regulate the expression of AKT3 by sponging miR-145-5p, which was confirmed using an in vitro luciferase assay. In conclusion, we validated n384546 as a novel oncogenic lncRNA in PTC and determined that the n384546/miR-145-5p/AKT3 pathway contributes to PTC progression, which might be used as potential therapeutic targets for PTC patients.

Differential circular RNA expression profiles of invasive and non-invasive non-functioning pituitary adenomas: A microarray analysis

Non-functioning pituitary adenomas (NFPAs) are the most common pituitary tumors, and some exhibit locally invasive or even clinically aggressive behavior. Circular RNAs (circRNAs) are a reinvented class of non-coding RNAs that play important roles in tumor initiation and progression.CircRNA microarray assays were performed in 4 invasive and 4 non-invasive NFPAs, and 4 typically differential expression circRNAs were selected for validation using quantitative reverse transcription-polymerase chain reaction. The diagnostic and prognostic values of tested cirRNAs were further evaluated. Bioinformatics analysis and a literature review of potential miRNAs targets involved in pituitary tumor invasion were performed.A specific circRNA expression profile was detected between invasive and non-invasive NFPAs, including 91 upregulated and 61 downregulated circRNAs in invasive tumors. The dysregulation of the 4 circRNAs has been confirmed. The expression of hsa_circRNA_102597, a downregulated circRNA, was significantly correlated with tumor diameter (P < .05) and Knosp grade (P < .01). Hsa_circRNA_102597 alone or in combined with Ki-67 index was able to accurately differentiate invasive from non-invasive NFPAs as well as predict tumor progression/recurrence. Fourteen aberrantly expressed circRNAs might be involved in the invasiveness of pituitary adenomas via seven predicted potential miRNA targets.CircRNAs are participated in pituitary tumor invasion, and may be used as novel diagnostic and prognostic biomarkers in NFPAs.

circOMA1-Mediated miR-145-5p Suppresses Tumor Growth of Nonfunctioning Pituitary Adenomas by Targeting TPT1

CONTEXT

Nonfunctioning pituitary adenomas (NFPAs) are the major cause of hypopituitarism and infertility. However, the pathogenesis of NFPAs remains largely unknown. Previous studies have demonstrated the crucial role of miRNAs in the progression of pituitary adenomas. Increasing evidence has indicated that circular RNAs (circRNAs) might mediate miRNA transcriptional activity, providing new insights to study the pathogenesis of NFPAs.

OBJECTIVES

To explore the regulation and activity of the circRNA-miRNA-mRNA axis in the tumorigenesis of NFPAs.

DESIGN

The function of miR-145-5p in NFPAs was investigated invitro and invivo. The mechanical details were explored and potential targets of miR-145-5p were identified. Finally, miR-145-5p-associated circRNAs were functionally recognized and confirmed.

RESULTS

miR-145-5p was markedly decreased in NFPA samples and correlated negatively with NFPA invasiveness. Overexpression of miR-145-5p suppressed NFPA cell proliferation and invasiveness and promoted apoptosis. Further results confirmed that translationally controlled tumor protein (TPT1) is a target of miR-145-5p and mediated the effect of miR-145-5p. TPT1 and its downstream factors Mcl-1 and Bcl-xL were downregulated, and Bax was upregulated by miR-145-5p. Moreover, circOMA1 (hsa_circRNA_0002316) was demonstrated to sponge miR-145-5p, whose suppression on NFPA cells was abrogated by circOMA1 overexpression. circOMA1 silencing exhibited a similar inhibitory effect with miR-145-5p overexpression by downregulating TPT1. We found that circOMA1 could further upregulate Mcl-1 and Bcl-xL and downregulate Bax.

CONCLUSIONS

circOMA1 promotes NFPA progression by acting as the sponge of tumor suppressor miR-145-5p to regulate the TPT1 signaling pathway, revealing a therapeutic target in preventing the tumorigenesis of NFPAs.

GNG7 silencing promotes the proliferation and differentiation of placental cytotrophoblasts in preeclampsia rats through activation of the mTOR signaling pathway

Preeclampsia (PE) is a pathological condition that manifests during pregnancy as the occurrence of an abnormal urine protein level and increased blood pressure due to inadequate cytotrophoblast invasion. To elucidate the mechanism underlying PE, the present study primarily focused on the regulatory effects and mechanism of the G protein γ 7 (GNG7) on placental cytotrophoblasts in a rat PE model. Initially, the PE model was established with 45 specific pathogen‑free Sprague‑Dawley rats (30 females and 15 males). The expression patterns of GNG7, 4E‑binding protein 1 (4E‑BP1), phosphoprotein 70 ribosomal protein S6 kinase (p70S6K) and mammalian target of rapamycin (mTOR) were examined in the PE rats. Placental cytotrophoblasts isolated from normal and PE rats were treated with a small interfering RNA against GNG7, mTOR signaling pathway activator (HIV‑1 Tat) or inhibitor (rapamycin). Following treatment, cell proliferation, differentiation and apoptosis were evaluated, and mTOR signaling pathway‑related factors (4E‑BP1, p70S6K and mTOR), cell proliferation‑related factors (vascular endothelial growth factor and transforming growth factor‑β1), differentiation‑related factors [activator protein‑2 (AP‑2)α and AP‑2γ], and apoptosis‑related factors [B‑cell lymphoma 2 (Bcl‑2) and Bcl‑2‑associated X protein] were determined. Finally, soluble fms‑like tyrosine kinase 1 (sFlt‑1) and soluble endoglin (sEng) levels were measured via enzyme‑linked immunosorbent assay. Initially, the mTOR signaling pathway was inactivated in the placental tissues and cytotrophoblasts in the PE rats. Silencing GNG7 reduced the levels of sFlt‑1 and sEng and activated the mTOR signaling pathway. Silencing of GNG7 or activation of the mTOR signaling pathway enhanced cell proliferation and differentiation, but inhibited the apoptosis of placental cytotrophoblasts in the PE rats. Taken together, the results showed that GNG7 silencing repressed apoptosis and enhanced the proliferation and differentiation of placental cytotrophoblasts in PE rats through activation of the mTOR signaling pathway.

MicroRNAs in Female Malignancies

MicroRNAs (miRNAs) are endogenous 22-nucleotide RNAs that can play a fundamental regulatory role in the gene expression of various organisms. Current research suggests that miRNAs can assume pivotal roles in carcinogenesis. In this article, through bioinformatics mining and computational analysis, we determine a single miRNA commonly involved in the development of breast, cervical, endometrial, ovarian, and vulvar cancer, whereas we underline the existence of 7 more miRNAs common in all examined malignancies with the exception of vulvar cancer. Furthermore, we identify their target genes and encoded biological functions. We also analyze common biological processes on which all of the identified miRNAs act and we suggest a potential mechanism of action. In addition, we analyze exclusive miRNAs among the examined malignancies and bioinformatically explore their functionality. Collectively, our data can be employed in in vitro assays as a stepping stone in the identification of a universal machinery that is derailed in female malignancies, whereas exclusive miRNAs may be employed as putative targets for future chemotherapeutic agents or cancer-specific biomarkers.

miRNA‑145 inhibits myocardial infarction‑induced apoptosis through autophagy via Akt3/mTOR signaling pathway in vitro and in vivo

The present study investigated the effects of micro (mi)RNA‑145 on acute myocardial infarction (AMI) and the potential underlying mechanism. A total of 6 AMI and 6 normal rat tissues were investigated for the present study. It was demonstrated that miRNA‑145 expression was downregulated in the AMI rat model, compared with the control group. Downregulation of miRNA‑145 increased cardiac cell apoptosis, suppressed phosphorylated (p)‑RAC‑γ serine/threonine‑protein kinase (Akt3) and p‑mechanistic target of rapamycin (mTOR) protein expression levels and suppressed autophagy in an in vitro model of AMI. However, overexpression of miRNA‑145 decreased cardiac cell apoptosis, induced p‑Akt3 and p‑mTOR protein expression and promoted autophagy in the in vitro model of AMI. The inhibition of Akt3 (GSK2110183, 1 nM) decreased the effect of the miRNA‑145 upregulation on cell apoptosis in the in vitro model of AMI. Chloroquine diphosphate (5 µM) inhibited the regulatory effect of miRNA‑145 upregulation on autophagy to adjust cell apoptosis, in the in vitro model of AMI. The results of the present study demonstrate that miRNA‑145 inhibits myocardial infarction‑induced apoptosis via autophagy associated with the Akt3/mTOR signaling pathway in vivo and in vitro.

miR-499 Ameliorates Podocyte Injury by Targeting Calcineurin in Minimal Change Disease

BACKGROUND

Podocyte injury is a hallmark of minimal change disease (MCD). Calcineurin inhibitors have been widely used in the current treatment of MCD, and miR-499 may target calcineurin. We aimed to study the function of miR-499 in MCD and test whether miR-499 delivery can improve MCD.

METHODS

An MCD mouse model was generated using puromycin aminonucleoside (PAN). MiR-499 was delivered using lentiviruses. Biochemical indicators including serum albumin, triglyceride, cholesterol, and 24-h urine protein were determined. Targets of miR-499 were confirmed using reporter gene activity assays. The ultrastructure of podocytes was analyzed using transmission electron microscopy.

RESULTS

MiR-499 significantly improved MCD-related symptoms and signs. Foot-process effacement was caused by PAN and partially reversed by miR-499. We identified that both CnAα and CnAβ were targets of miR-499, and were overexpressed in the presence of PAN. However, miR-499 reduced the expression of CnAα and CnAβ, leading to a decreased activity of calcineurin signaling in mouse podocytes in vitro and in vivo. In addition, miR-499 recovered PAN-induced reduction of cell viability.

CONCLUSIONS

MiR-499 ameliorated podocyte injury by targeting CnAα and CnAβ in a PAN-induced MCD mouse model. Delivery of miR-499 can be a novel strategy for MCD treatment.

Caveolin-1 promotes pituitary adenoma cells migration and invasion by regulating the interaction between EGR1 and KLF5

Caveolin-1 (Cav-1) is a principal structural protein of caveolae. Cav-1 has been implicated in cancer progression, but its precise functional roles in pituitary adenoma cells remain largely unclear. In this study, we evidenced that the level of cav-1 was elevated in the invasive pituitary adenoma. Cav-1 knockdown restrained the migration and invasion of pituitary adenoma cells. In cav-1-depleting cells, the expression of miR-145, miR-124 and miR-183 were up-regulated. Further investigation showed that cav-1 knockdown inhibited the nuclear translocation of EGR1, reducing the interaction between EGR1 and KLF5. The resulting free KLF5 promoted the expression of miR-145, miR-124 and miR-183 by binding to their promoters, which was blocked by EGR1. Luciferase reporter assay indicated that miR-145 targeted FSCN1, miR-124 targeted PTTG1IP, and miR-183 targeted EZR in pituitary adenoma cells, respectively. Knockdown of FSCN1, PTTG1IP or EZR suppressed the migration and invasion of pituitary adenoma cells. In conclusion, our data suggested that the elevated cav-1 promoted pituitary adenoma cells migration and invasion by regulating the interaction between EGR1 and KLF5.

MiR-145 ameliorates neuropathic pain via inhibiting inflammatory responses and mTOR signaling pathway by targeting Akt3 in a rat model

Neuropathic pain perplexes a large population of patients with various diseases. Inflammation plays a key role in the physiopathology of neuropathic pain. Anti-inflammatory can be a promising strategy to treat neuropathic pain. We generated a chronic constriction injury rat model to mimic neuropathic pain by ligating the left ischiadic nerves of rats. Then we performed intrathecal injection of miR-145 mimics to treat these rats for seven consecutive days. Pain behavior tests including mechanical allodynia and thermal hyperalgesia, pro-inflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were analyzed. Quantitative polymerase chain reaction and immunoblotting were performed to detect the changes of signaling pathway after miR-145 mimic treatment. Targeting of Akt3 by miR-145 was studied by dual-luciferase reporter gene assays. MiR-145 mimics injection significantly mollified both mechanical allodynia and thermal hyperalgesia in rats, and down-regulated secretion of TNF-α, IL-1β and IL-6. We confirmed that miR-145 directly targeted Akt3, inhibiting NF-κB and mTOR downstream genes in rat dorsal root ganglia. MiR-145 can mollify neuropathic pain in a chronic constriction injury rat model by reducing inflammation and ion channel overexpression through Akt3/mTOR and Akt3/NF-κB signaling pathways.