Autocrine/Paracrine Human Growth Hormone-stimulated MicroRNA 96-182-183 Cluster Promotes Epithelial-Mesenchymal Transition and Invasion in Breast Cancer

Dysregulation and functional roles of miR-183-96-182 cluster in cancer cell proliferation, invasion and metastasis

Previous studies have reported aberrant expression of the miR-183-96-182 cluster in a variety of tumors, which indicates its' diagnostic or prognostic value. However, a key characteristic of the miR-183-96-182 cluster is its varied expression levels, and pleomorphic functional roles in different tumors or under different conditions. In most tumor types, the cluster is highly expressed and promotes tumorigenesis, cancer progression and metastasis; yet tumor suppressive effects have also been reported in some tumors. In the present study, we discuss the upstream regulators and the downstream target genes of miR-183-96-182 cluster, and highlight the dysregulation and functional roles of this cluster in various tumor cells. Newer insights summarized in this review will help readers understand the different facets of the miR-183-96-182 cluster in cancer development and progression.

miR‑96 inhibits EMT by targeting AEG‑1 in glioblastoma cancer cells

The induction of epithelial to mesenchymal transition (EMT) is important for carcinogenesis and cancer progression. Previous studies have estimated that microRNA (miRNA/miR) expression is associated with EMT via the regulation of the expression of target genes. miR-96 has been reported to exhibit a correlation with the EMT process. However, the functional role of miR-96 and its mechanism in glioblastoma multiforme (GBM) remains to be completely elucidated. The objective of the present study was to investigate the functional role and mechanism of miR-96 in the migration and invasion, in addition to proliferation, apoptosis and cell cycle distribution, of GBM. In the present study, the results suggested that the introduction of miR-96 significantly inhibited the migration and invasion, in addition to proliferation and cell cycle progression, of GBM cells and promoted their apoptosis in vitro, leading to the hypothesis that miR-96 may be a potential tumor suppressor. It was subsequently confirmed that astrocyte elevated gene-1 (AEG-1) was a direct target gene of miR-96, using a luciferase assay and reverse transcription-quantitative polymerase chain reaction analysis, in addition to western blotting. miR-96 was observed to downregulate the expression of AEG-1 at the mRNA and protein levels. Notably, AEG-1 may suppress EMT by increasing the expression levels of E-cadherin, an epithelial marker, and decreasing the expression levels of vimentin, a mesenchymal marker. Therefore, it was concluded that miR-96 may impede the EMT process by downregulating AEG-1 in GBM. Additionally, it was observed that inhibition of AEG-1 led to a similar effect compared with overexpression of miR-96 in GBM. In conclusion, the results of the present study demonstrated that miR-96 may act as a tumor suppressor by regulating EMT via targeting of AEG-1, suggesting that miR-96 may be a potential biomarker and anticancer therapeutic target for GBM in the future.

Autocrine hGH stimulates oncogenicity, epithelial-mesenchymal transition and cancer stem cell-like behavior in human colorectal carcinoma

Tumor derived human growth hormone (hGH) has been implicated in cancer development and progression. However, the specific functional role of autocrine/paracrine hGH in colorectal cancer (CRC) remains largely to be determined. Herein, we demonstrated a crucial oncogenic role of autocrine hGH in CRC progression. Elevated hGH expression was detected in CRC compared to normal colorectal tissue, and hGH expression in CRC was positively associated with tumor size and lymph node metastasis. Forced expression of hGH stimulated cell proliferation, survival, oncogenicity and epithelial to mesenchymal transition (EMT) of CRC cells, and promoted xenograft growth and local invasion in vivo. Autocrine hGH expression in CRC cells stimulated the activation of the ERK1/2 pathway, which in turn resulted in increased transcription of the mesenchymal marker FIBRONECTIN 1 and transcriptional repression of the epithelial marker E-CADHERIN. The autocrine hGH-stimulated increase in CRC cell proliferation, cell survival and EMT was abrogated upon ERK1/2 inhibition. Furthermore, autocrine hGH-stimulated CRC cell migration and invasion was dependent on the ERK1/2-mediated increase in FIBRONECTIN 1 expression and decrease in E-CADHERIN expression. Forced expression of hGH also enhanced CSC-like behavior of CRC cells, as characterized by increased colonosphere formation, ALDH-positive population and CSC marker expression. Autocrine hGH-enhanced cancer stem cell (CSC)-like behavior in CRC cells was also observed to be E-CADHERIN-dependent. Thus, autocrine hGH plays a critical role in CRC progression, and inhibition of hGH could be a promising targeted therapeutic approach to limit disease progression in metastatic CRC patients.

Growth Hormone and the Epithelial-to-Mesenchymal Transition

CONTEXT

Previous studies have implicated growth hormone (GH) in the progression of several cancers, including breast, colorectal, and pancreatic. A mechanism by which GH may play this role in cancer is through the induction of the epithelial-to-mesenchymal transition (EMT). During the EMT process, epithelial cells lose their defining phenotypes, causing loss of cellular adhesion and increased cell migration. This review aims to carefully summarize the previous two decades of research that points to GH as an initiator of EMT, in both cancerous and noncancerous tissues.

EVIDENCE ACQUISITION

Sources were collected using PubMed and Google Scholar search engines by using specific GH- and/or EMT-related terms. Identified manuscripts were selected for further analysis based on presentation of GH-induced molecular markers of the EMT process in vivo or in vitro.

EVIDENCE SYNTHESIS

Cellular mechanisms involved in GH-induced EMT are the focus of this review, both in cancerous and noncancerous epithelial cells.

CONCLUSIONS

Our findings suggest that a myriad of molecular mechanisms are induced by GH that cause EMT and may point to potential therapeutic use of GH antagonists or any downregulator of GH action in EMT-related disease.

MicroRNA-182 promotes proliferation and metastasis by targeting FOXF2 in triple-negative breast cancer

Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer (BC), is characterized as high proliferation, young age and poor prognosis. MicroRNA-182 (miR-182) was reported to have oncogenic potential in many cancers. We aimed to elucidate pathobiological effects of miR-182 expression by targeting forkhead-box F2 (FOXF2) in TNBC. In this study, we explored the functional role of miR-182 expression in TNBC. Quantitative real-time PCR (qRT-PCR) was applied to evaluate the expression of miR-182 in cell lines and tissues. A series of in vitro and in vivo assays were performed in the MCF-7 and MDA-MB-231 cell lines with miR-182 overexpression. Luciferase reporter assays and western blot analysis were used to identify FOXF2 as the direct and functional target of miR-182. In TNBC tissues and cell lines, we found that miR-182 was significantly upregulated. Transwell assay showed that re-expression of miR-182 increased cell migration and invasion abilities and MTT assay showed that it promoted cell growth in vitro. In vivo assay, re-expression of miR-182 significantly increase tumor volume and enhanced instant metastasis in the lungs of mice. Besides, FOXF2 was identified as a direct and functional target of miR-182. These results indicated that miR-182 plays an important role in the initiation and progression of TNBC by targeting FOXF2 and the miR-182/FOXF2 axis may present a new therapeutic strategy for TNBC in the future.

Tumour-Derived Human Growth Hormone As a Therapeutic Target in Oncology

The growth hormone (GH) and insulin-like growth factor-1 (IGF1) axis is the key regulator of longitudinal growth, promoting postnatal bone and muscle growth. The available data suggest that GH expression by tumour cells is associated with the aetiology and progression of various cancers such as endometrial, breast, liver, prostate, and colon cancer. Accordingly there has been increased interest in targeting GH-mediated signal transduction in a therapeutic setting. Because GH has endocrine, autocrine, and paracrine actions, therapeutic strategies will need to take into account systemic and local functions. Activation of related hormone receptors and crosstalk with other signalling pathways are also key considerations.

Novel Actions of Growth Hormone in Podocytes: Implications for Diabetic Nephropathy

The kidney regulates water, electrolyte, and acid-base balance and thus maintains body homeostasis. The kidney’s potential to ensure ultrafiltered and almost protein-free urine is compromised in various metabolic and hormonal disorders such as diabetes mellitus (DM). Diabetic nephropathy (DN) accounts for ~20–40% of mortality in DM. Proteinuria, a hallmark of renal glomerular diseases, indicates injury to the glomerular filtration barrier (GFB). The GFB is composed of glomerular endothelium, basement membrane, and podocytes. Podocytes are terminally differentiated epithelial cells with limited ability to replicate. Podocyte shape and number are both critical for the integrity and function of the GFB. Podocytes are vulnerable to various noxious stimuli prevalent in a diabetic milieu that could provoke podocytes to undergo changes to their unique architecture and function. Effacement of podocyte foot process is a typical morphological alteration associated with proteinuria. The dedifferentiation of podocytes from epithelial-to-mesenchymal phenotype and consequential loss results in proteinuria. Poorly controlled type 1 DM is associated with elevated levels of circulating growth hormone (GH), which is implicated in the pathophysiology of various diabetic complications including DN. Recent studies demonstrate that functional GH receptors are expressed in podocytes and that GH may exert detrimental effects on the podocyte. In this review, we summarize recent advances that shed light on actions of GH on the podocyte that could play a role in the pathogenesis of DN.

Secreted molecules inducing epithelial-to-mesenchymal transition in cancer development

The epithelial-mesenchymal transition (EMT) is a biologic process that allows a polarized epithelial cell to undergo multiple biochemical changes that enable it to assume a mesenchymal cell phenotype. EMT is involved in embryo development, wound healing, tissue regeneration, organ fibrosis and has also been proposed as the critical mechanism for the acquisition of malignant phenotypes by epithelial cancer cells. These cells have been shown to acquire a mesenchymal phenotype when localized at the invasive front of primary tumours increasing aggressiveness, invasiveness, metastatic potential and resistance to chemotherapy. There is now increasing evidence demonstrating that a crucial role in the development of this process is played by factors secreted by cells of the tumour microenvironment or by the tumour cells themselves. This review summarises the current knowledge of EMT induction in cancer by paracrine or autocrine mechanisms, by exosomes or free proteins and miRNAs.

Autocrine Human Growth Hormone Promotes Invasive and Cancer Stem Cell-Like Behavior of Hepatocellular Carcinoma Cells by STAT3 Dependent Inhibition of CLAUDIN-1 Expression

Despite progress in diagnosis and treatment of hepatocellular carcinoma (HCC), the clinical outcome is still unsatisfactory. Increased expression of human growth hormone (hGH) in HCC has been reported and is associated with poor survival outcome in HCC patients. Herein, we investigated the mechanism of the oncogenic effects of hGH in HCC cell lines. In vitro functional assays demonstrated that forced expression of hGH in these HCC cell lines promoted cell proliferation, cell survival, anchorage-independent growth, cell migration, and invasion, as previously reported. In addition, forced expression of hGH promoted cancer stem cell (CSC)-like properties of HCC cells. The increased invasive and CSC-like properties of HCC cells with forced expression of hGH were mediated by inhibition of the expression of the tight junction component CLAUDIN-1. Consistently, depletion of CLAUDIN-1 expression increased the invasive and CSC-like properties of HCC cell lines. Moreover, forced expression of CLAUDIN-1 abrogated the acquired invasive and CSC-like properties of HCC cell lines with forced expression of hGH. We further demonstrated that forced expression of hGH inhibited CLAUDIN-1 expression in HCC cell lines via signal transducer and activator of transcription 3 (STAT3) mediated inhibition of CLAUDIN-1 transcription. Hence, we have elucidated a novel hGH-STAT3-CLAUDIN-1 axis responsible for invasive and CSC-like properties in HCC. Inhibition of hGH should be considered as a therapeutic option to hinder progression and relapse of HCC.

Growth Hormone Receptor Knockdown Sensitizes Human Melanoma Cells to Chemotherapy by Attenuating Expression of ABC Drug Efflux Pumps

Melanoma remains one of the most therapy-resistant forms of human cancer despite recent introductions of highly efficacious targeted therapies. The intrinsic therapy resistance of human melanoma is largely due to abundant expression of a repertoire of xenobiotic efflux pumps of the ATP-binding cassette (ABC) transporter family. Here, we report that GH action is a key mediator of chemotherapeutic resistance in human melanoma cells. We investigated multiple ABC efflux pumps (ABCB1, ABCB5, ABCB8, ABCC1, ABCC2, ABCG1, and ABCG2) reportedly associated with melanoma drug resistance in different human melanoma cells and tested the efficacy of five different anti-cancer compounds (cisplatin, doxorubicin, oridonin, paclitaxel, vemurafenib) with decreased GH action. We found that GH treatment of human melanoma cells upregulates expression of multiple ABC transporters and increases the EC50 of melanoma drug vemurafenib. Also, vemurafenib-resistant melanoma cells had upregulated levels of GH receptor (GHR) expression as well as ABC efflux pumps. GHR knockdown (KD) using siRNA in human melanoma cells treated with sub-EC50 doses of anti-tumor compounds resulted in significantly increased drug retention, decreased cell proliferation and increased drug efficacy, compared to mock-transfected controls. Our set of findings identify an unknown mechanism of GH regulation in mediating melanoma drug resistance and validates GHR as a unique therapeutic target for sensitizing highly therapy-resistant human melanoma cells to lower doses of anti-cancer drugs.

Role of Growth Hormone in Breast Cancer

Breast cancer is one of the most common cancers diagnosed in women. Approximately two-thirds of all breast cancers diagnosed are classified as hormone dependent, which indicates that hormones are the key factors that drive the growth of these breast cancers. Ovarian and pituitary hormones play a major role in the growth and development of normal mammary glands and breast cancer. In particular, the effect of the ovarian hormone estrogen has received much attention in regard to breast cancer. Pituitary hormones prolactin and growth hormone have also been associated with breast cancer. Although the role of these pituitary hormones in breast cancers has been studied, it has not been investigated extensively. In this review, we attempt to compile basic information from most of the currently available literature to understand and demonstrate the significance of growth hormone in breast cancer. Based on the available literature, it is clear that growth hormone plays a significant role in the development, progression, and metastasis of breast cancer by influencing tumor angiogenesis, stemness, and chemoresistance.

SMAD4 Loss Is Associated with Cetuximab Resistance and Induction of MAPK/JNK Activation in Head and Neck Cancer Cells

Purpose: We previously demonstrated an association between decreased SMAD4 expression and cetuximab resistance in head and neck squamous cell carcinoma (HNSCC). The purpose of this study was to further elucidate the clinical relevance of SMAD4 loss in HNSCC.Experimental Design: SMAD4 expression was assessed by IHC in 130 newly diagnosed and 43 patients with recurrent HNSCC. Correlative statistical analysis with clinicopathologic data was also performed. OncoFinder, a bioinformatics tool, was used to analyze molecular signaling in TCGA tumors with low or high SMAD4 mRNA levels. The role of SMAD4 was investigated by shRNA knockdown and gene reconstitution of HPV-negative HNSCC cell lines in vitro and in vivoResults: Our analysis revealed that SMAD4 loss was associated with an aggressive, HPV-negative, cetuximab-resistant phenotype. We found a signature of prosurvival and antiapoptotic pathways that were commonly dysregulated in SMAD4-low cases derived from TCGA-HNSCC dataset and an independent oral cavity squamous cell carcinoma (OSCC) cohort obtained from GEO. We show that SMAD4 depletion in an HNSCC cell line induces cetuximab resistance and results in worse survival in an orthotopic mouse model in vivo We implicate JNK and MAPK activation as mediators of cetuximab resistance and provide the foundation for the concomitant EGFR and JNK/MAPK inhibition as a potential strategy for overcoming cetuximab resistance in HNSCCs with SMAD4 loss.Conclusions: Our study demonstrates that loss of SMAD4 expression is a signature characterizing the cetuximab-resistant phenotype and suggests that SMAD4 expression may be a determinant of sensitivity/resistance to EGFR/MAPK or EGFR/JNK inhibition in HPV-negative HNSCC tumors. Clin Cancer Res; 23(17); 5162-75. ©2017 AACR.

Targeting growth hormone receptor in human melanoma cells attenuates tumor progression and epithelial mesenchymal transition via suppression of multiple oncogenic pathways

Recent reports have confirmed highest levels of growth hormone (GH) receptor (GHR) transcripts in melanoma, one of the most aggressive forms of human cancer. Yet the mechanism of GH action in melanoma remains mostly unknown. Here, using human malignant melanoma cells, we examined the effects of GH excess or siRNA mediated GHR knock-down (GHRKD) on tumor proliferation, migration and invasion. GH promoted melanoma progression while GHRKD attenuated the same. Western blot analysis revealed drastic modulation of multiple oncogenic signaling pathways (JAK2, STAT1, STAT3, STAT5, AKT, mTOR, SRC and ERK1/2) following addition of GH or GHRKD. Further, we show that GH excess upregulates expression of markers of epithelial mesenchymal transition in human melanoma, while the effects were reversed by GHRKD. Interestingly, we observed consistent expression of GH transcript in the melanoma cells as well as marked modulation of the IGF receptors and binding proteins (IGF1R, IGF2R, IR, IGFBP2, IGFBP3) and the oncogenic HGF-MET mRNA, in response to excess GH or GHRKD. Our study thus identifies the mechanistic model of GH-GHR action in human melanoma and validates it as an important pharmacological target of intervention.

MicroRNAs regulate the epithelial-mesenchymal transition and influence breast cancer invasion and metastasis

MicroRNAs are small RNA molecules that play a major role in the post-transcriptional regulation of genes and influence the development, differentiation, proliferation, and apoptosis of cells and the development and progression of tumors. The epithelial-mesenchymal transition is a process by which epithelial cells morphologically transform into cells with a mesenchymal phenotype. The epithelial-mesenchymal transition plays a highly important role in tumor invasion and metastasis. Increasing evidence indicates that microRNAs are tightly associated with epithelial-mesenchymal transition regulation in tumor cells. In breast cancer, various microRNA molecules have been identified as epithelial-mesenchymal transition inducers or inhibitors, which, through different mechanisms and signaling pathways, participate in the regulation of breast cancer invasion and metastasis among various biological behaviors. The epithelial-mesenchymal transition-related microRNAs in breast cancer provide valuable molecules for researching cell invasion and metastasis, and they also provide candidate targets that may be significant for the targeted therapy of breast cancer.

Emerging Role of MicroRNAs in mTOR Signaling

Mechanistic target of rapamycin (mTOR) is a conserved serine/threonine kinase that plays a critical role in the control of cellular growth and metabolism. Hyperactivation of mTOR pathway is common in human cancers, driving uncontrolled proliferation. MicroRNA (miRNA) is a class of short noncoding RNAs that regulate the expression of a wide variety of genes. Deregulation of miRNAs is a hallmark of cancer. Recent studies have revealed interplays between miRNAs and the mTOR pathway during cancer development. Such interactions appear to provide a fine-tuning of various cellular functions and contribute qualitatively to the behavior of cancer. Here we provide an overview of current knowledge regarding the reciprocal relationship between miRNAs and mTOR pathway: regulation of mTOR signaling by miRNAs and control of miRNA biogenesis by mTOR. Further research in this area may prove important for the diagnosis and therapy of human cancer.

MicroRNA-182 prevents vascular smooth muscle cell dedifferentiation via FGF9/PDGFRβ signaling

The abnormal phenotypic transformation of vascular smooth muscle cells (SMCs) causes various proliferative vascular diseases. MicroRNAs (miRNAs or miRs) have been established to play important roles in SMC biology and phenotypic modulation. This study revealed that the expression of miR‑182 was markedly altered during rat vascular SMC phenotypic transformation in vitro. We aimed to investigate the role of miR‑182 in the vascular SMC phenotypic switch and to determine the potential molecular mechanisms involved. The expression of miR‑182 gene was significantly downregulated in cultured SMCs during dedifferentiation from a contractile to a synthetic phenotype. Conversely, the upregulation of miR‑182 increased the expression of SMC-specific contractile genes, such as α-smooth muscle actin, smooth muscle 22α and calponin. Additionally, miR‑182 overexpression potently inhibited SMC proliferation and migration under both basal conditions and under platelet-derived growth factor-BB stimulation. Furthermore, we identified fibroblast growth factor 9 (FGF9) as the target gene of miR‑182 for the phenotypic modulation of SMCs mediated through platelet-derived growth factor receptor β (PDGFRβ) signaling. These data suggest that miR‑182 may be a novel SMC phenotypic marker and a modulator that may be used to prevent SMC dedifferentiation via FGF9/PDGFRβ signaling.

MiR-182 promotes cancer invasion by linking RET oncogene activated NF-κB to loss of the HES1/Notch1 regulatory circuit

Background

Dominant-activating mutations in the RET proto-oncogene, a receptor tyrosine kinase, are responsible for the development of medullary thyroid carcinoma (MTC) and causative for multiple endocrine neoplasia (MEN) type 2A and 2B. These tumors are highly aggressive with a high propensity for early metastasis and chemoresistance. This attribute makes this neoplasia an excellent model for probing mechanisms underlying cancer progression.

Methods

The expression level of miR-182 was measured in MTC tumor specimens and in TT cells by real-time RT-PCR. TT cells and modified NThy-ori 3.1 that stably express RETM918T were used to investigate RET-dependent regulation of miR-182. Identification and validation of miR-182 targets and pathways was accomplished with luciferase assays, qRT-PCR, Western blotting and immunofluorescence. In vitro, overexpression and knockdown experiments were carried out to examine the impact of miR-182 and HES1 on invasion and migration.

Results

We found that miR-182 expression is significantly upregulated in MTC patient samples and tumor-derived cell lines harboring mutated RET. Inhibition of RET oncogenic signaling through a dominant-negative RET∆TK mutant in TT cells reduces miR-182, whereas overexpression of RETM918T in NThy-ori 3.1 cells increases miR-182 levels. We further show that overexpression of this miRNA in NThy.miR-182 cells promotes the invasive and migratory properties without affecting cell proliferation. MiR-182 is upregulated after RET induced NF-κB translocation into the nucleus via binding of NF-κB to the miR-182 promoter. Database analysis revealed that HES1, a repressor of the Notch pathway, is a target of miR-182, whose upregulation correlates with loss of HES1 transcription in MTC tissue samples and mutant RET cell lines. Moreover, we demonstrated that the 3′UTR of the HES1 mRNA bearing the targeting sequence for miR-182 clearly reduced luciferase reporter activity in cells expressing miR-182. Decreased expression of HES1 promotes migration by upregulating Notch1 inhibitor Deltex1 and consequent repression of Notch1.

Conclusion

We demonstrate a novel mechanism for MTC aggressiveness in which mutated RET/NF-κB-driven expression of miR-182 impedes HES1 activation in a negative feedback loop. This observation might open new possibilities to treat RET oncogene associated metastatic cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0563-x) contains supplementary material, which is available to authorized users.

miR-96 promotes cell proliferation, migration and invasion by targeting PTPN9 in breast cancer

microRNAs (miRNAs) have emerged as major regulators of the initiation and progression of human cancers, including breast cancer. The aim of this study is to determine the expression pattern of miR-96 in breast cancer and to investigate its biological role during tumorigenesis. We showed that miR-96 was significantly upregulated in breast cancer. We then investigated its function and found that miR-96 significantly promoted cell proliferation, migration and invasion in vitro and enhanced tumor growth in vivo. Furthermore, we explored the molecular mechanisms by which miR-96 contributes to breast cancer progression and identified PTPN9 (protein tyrosine phosphatase, non-receptor type 9) as a direct target gene of miR-96. Finally, we showed that PTPN9 had opposite effects to those of miR-96 on breast cancer cells, suggesting that miR-96 may promote breast tumorigenesis by silencing PTPN9. Taken together, this study highlights an important role for miR-96 in the regulation of PTPN9 in breast cancer cells and may provide insight into the molecular mechanisms of breast carcinogenesis.

Evaluation of the Tobacco Heating System 2.2 (THS2.2). Part 5: microRNA expression from a 90-day rat inhalation study indicates that exposure to THS2.2 aerosol causes reduced effects on lung tissue compared with cigarette smoke

Modified-risk tobacco products (MRTP) are designed to reduce the individual risk of tobacco-related disease as well as population harm compared to smoking cigarettes. Experimental proof of their benefit needs to be provided at multiple levels in research fields. Here, we examined microRNA (miRNA) levels in the lungs of rats exposed to a candidate modified-risk tobacco product, the Tobacco Heating System 2.2 (THS2.2) in a 90-day OECD TG-413 inhalation study. Our aim was to assess the miRNA response to THS2.2 aerosol compared with the response to combustible cigarettes (CC) smoke from the reference cigarette 3R4F. CC smoke exposure, but not THS2.2 aerosol exposure, caused global miRNA downregulation, which may be explained by the interference of CC smoke constituents with the miRNA processing machinery. Upregulation of specific miRNA species, such as miR-146a/b and miR-182, indicated that they are causal elements in the inflammatory response in CC-exposed lungs, but they were reduced after THS2.2 aerosol exposure. Transforming transcriptomic data into protein activity based on corresponding downstream gene expression, we identified potential mechanisms for miR-146a/b and miR-182 that were activated by CC smoke but not by THS2.2 aerosol and possibly involved in the regulation of those miRNAs. The inclusion of miRNA profiling in systems toxicology approaches increases the mechanistic understanding of the complex exposure responses.

Bioinformatic Studies to Predict MicroRNAs with the Potential of Uncoupling RECK Expression from Epithelial-Mesenchymal Transition in Cancer Cells

RECK is downregulated in many tumors, and forced RECK expression in tumor cells often results in suppression of malignant phenotypes. Recent findings suggest that RECK is upregulated after epithelial-mesenchymal transition (EMT) in normal epithelium-derived cells but not in cancer cells. Since several microRNAs (miRs) are known to target RECK mRNA, we hypothesized that certain miR(s) may be involved in this suppression of RECK upregulation after EMT in cancer cells. To test this hypothesis, we used three approaches: (1) text mining to find miRs relevant to EMT in cancer cells, (2) predicting miR targets using four algorithms, and (3) comparing miR-seq data and RECK mRNA data using a novel non-parametric method. These approaches identified the miR-183-96-182 cluster as a strong candidate. We also looked for transcription factors and signaling molecules that may promote cancer EMT, miR-183-96-182 upregulation, and RECK downregulation. Here we describe our methods, findings, and a testable hypothesis on how RECK expression could be regulated in cancer cells after EMT.

Breast Cancer Metastasis Suppressor 1 (BRMS1): Robust Biological and Pathological Data, But Still Enigmatic Mechanism of Action

Metastasis requires coordinated expression of multiple genetic cassettes, often via epigenetic regulation of gene transcription. BRMS1 blocks metastasis, but not orthotopic tumor growth in multiple tumor types, presumably via SIN3 chromatin remodeling complexes. Although there is an abundance of strong data supporting BRMS1 as a metastasis suppressor, the mechanistic data directly connecting molecular pathways with inhibition of particular steps in metastasis are not well defined. In this review, the data for BRMS1-mediated metastasis suppression in multiple tumor types are discussed along with the steps in metastasis that are inhibited.

MicroRNA-96 promotes myocardial hypertrophy by targeting mTOR

As a main cause of cardiac hypertrophy, myocardial hypertrophy includes the proliferation and enlongation of myocardial cell, resulting in abnormally cardiac enlargement. However, the pathogenesis and the molecular mechanism that regulate gene expression of myocardial hypertrophy remain incompletely understood. MiRNAs were deemed as an important molecules involved in a variety of pathological processes. MiR-96 has been reported being associated with the tumor proliferation, but whether miR-96 is involved in cardiac hypertrophy remains uncertain. In this study, we have confirmed that, as the myocardial hypertrophy gene, mTOR was a target gene of miR-96, who would promote the occurrence of myocardial hypertrophy. Thus, we got the conclusion that miR-96 could promote myocardial hypertrophy by inhibiting mTOR, miR-96 and mTOR were negatively correlated.