The High Mobility Group A proteins contribute to thyroid cell transformation by regulating miR-603 and miR-10b expression

In silico analysis reveals hypoxia-induced miR-210-3p specifically targets SARS-CoV-2 RNA

Human coronaviruses (HCoVs) until the emergence of SARS in 2003 were associated with mild cold and upper respiratory tract infections. The ongoing pandemic caused by SARS-CoV-2 has enhanced the potential for infection and transmission as compared to other known members of this family. MicroRNAs (miRNA) are 21-25 nucleotides long non-coding RNA that bind to 3' UTR of genes and regulate almost every aspect of cellular function. Several human miRNAs have been known to target viral genomes, mostly to downregulate their expression and sometimes to upregulate also. In some cases, host miRNAs could be sequestered by the viral genome to create a condition for favourable virus existence. The ongoing SARS CoV-2 pandemic is unique based on its transmissibility and severity and we hypothesised that there could be a unique mechanism for its pathogenesis. In this study, we exploited in silico approach to identify human respiratory system-specific miRNAs targeting the viral genome of three highly pathogenic HCoVs (SARS-CoV-2 Wuhan strain, SARS-CoV, and MERS-CoV) and three low pathogenic HCoVs (OC43, NL63, and HKU1). We identified ten common microRNAs that target all HCoVs studied here. In addition, we identified unique miRNAs which targeted specifically one particular HCoV. miR-210-3p was the single unique lung-specific miRNA, which was found to target the NSP3, NSP4, and NSP13 genes of SARS-CoV-2. Further miR-210-NSP3, miR-210-NSP4, and miR-210-NSP13 SARS-CoV-2 duplexes were docked with the hAGO2 protein (PDB ID 4F3T) which showed Z-score values of -1.9, -1.7, and -1.6, respectively. The role of miR-210-3p as master hypoxia regulator and inflammation regulation may be important for SARS-CoV-2 pathogenesis. Overall, this analysis advocates that miR-210-3p be investigated experimentally in SARS-CoV-2 infection.Communicated by Ramaswamy H. Sarma.

Downregulation of DNMT3A Attenuates the Warburg Effect, Proliferation, and Invasion via Promoting the Inhibition of miR-603 on HK2 in Ovarian Cancer

Background: Ovarian cancer is a highly malignant gynecological cancer. Aerobic glycolysis is one of the features of cancer cell metabolism. Studying the molecular modulation of the Warburg effect in ovarian cancer is significantly valuable for understanding the progression mechanism of ovarian cancer. Materials and Methods: The expression level and prognostic significance of DNMT3A were analyzed using public databases. DNMT3A was overexpressed by plasmid transfection, and DNMT3A was interfered with specific siRNAs transfection. miR-603 was overexpressed by mimic transfection or inhibited by inhibitor transfection. The expression of the molecules was detected by qPCR or western blotting. CCK-8 and transwell assays were used to determine the cell proliferation, migration, and invasion abilities of ovarian cancer. Results: We found that the DNMT3A protein level was higher in ovarian cancer tissues than in normal ovary tissues, but the mRNA level had no significant difference in ovarian cancer tissues and normal ovary tissues. The higher the RNA level of DNMT3A, the poorer prognosis of patients. DNMT3A knocking down impeded the Warburg effect, cell proliferation, migration, and invasion of ovarian cancer cells. Further investigations discovered that DNMT3A promoted ovarian cancer cell malignancy via silencing miR-603. Conclusion: We found that patients who overexpressed DNMT3A showed a poor prognosis. DNMT3A was found to promote the Warburg effect, cell proliferation, migration, and invasion of ovarian cancer by inhibiting the expression of miR-603. As a result, the research revealed that DNMT3A/miR-603/HK2 axis contributed to the Warburg effect of ovarian cancer and DNMT3A may be a potential therapeutic target for ovarian cancer.

A Novel Therapeutic Mechanism of Imipridones ONC201/ONC206 in MYCN-Amplified Neuroblastoma Cells via Differential Expression of Tumorigenic Proteins

Neuroblastoma is the most common extracranial nervous system tumor in children. It presents with a spectrum of clinical prognostic measures ranging from benign growths that regress spontaneously to highly malignant, treatment evasive tumors affiliated with increased mortality rates. MYCN amplification is commonly seen in high-risk neuroblastoma, rendering it highly malignant and recurrence prone. In our current study, we investigated the therapeutic potential of small molecule inducers of TRAIL, ONC201, and ONC206 in MYCN-amplified IMR-32 and non-MYCN-amplified SK-N-SH human neuroblastoma cell lines. Our results exhibit potent antitumor activity of ONC201 and ONC206 via a novel inhibition of EGF-induced L1CAM and PDGFRβ phosphorylation in both cell lines. Drug treatment significantly reduced cellular proliferation, viability, migration, invasion, tumorsphere formation potential, and increased apoptosis in both cell lines. The protein expression of tumorigenic NMYC, Sox-2, Oct-4, FABP5, and HMGA1 significantly decreased 48 h post-drug treatment, whereas cleaved PARP1/caspase-3 and γH2AX increased 72 h post-drug treatment, compared with vehicle-treated cells in the MYCN-amplified IMR-32 cell line. We are the first to report this novel differential protein expression after ONC201 or ONC206 treatment in human neuroblastoma cells, demonstrating an important multitarget effect which may yield added therapeutic benefits in treating this devastating childhood cancer.

Genome-wide meta-analysis of variant-by-diuretic interactions as modulators of lipid traits in persons of European and African ancestry

Hypertension (HTN) is a significant risk factor for cardiovascular morbidity and mortality. Metabolic abnormalities, including adverse cholesterol and triglycerides (TG) profiles, are frequent comorbid findings with HTN and contribute to cardiovascular disease. Diuretics, which are used to treat HTN and heart failure, have been associated with worsening of fasting lipid concentrations. Genome-wide meta-analyses with 39,710 European-ancestry (EA) individuals and 9925 African-ancestry (AA) individuals were performed to identify genetic variants that modify the effect of loop or thiazide diuretic use on blood lipid concentrations. Both longitudinal and cross sectional data were used to compute cohort-specific interaction results, which were then combined through meta-analysis in each ancestry. These ancestry-specific results were further combined through trans-ancestry meta-analysis. Analysis of EA data identified two genome-wide significant (p < 5 × 10-8) loci with single nucleotide variant (SNV)-loop diuretic interaction on TG concentrations (including COL11A1). Analysis of AA data identified one genome-wide significant locus adjacent to BMP2 with SNV-loop diuretic interaction on TG concentrations. Trans-ancestry analysis strengthened evidence of association for SNV-loop diuretic interaction at two loci (KIAA1217 and BAALC). There were few significant SNV-thiazide diuretic interaction associations on TG concentrations and for either diuretic on cholesterol concentrations. Several promising loci were identified that may implicate biologic pathways that contribute to adverse metabolic side effects from diuretic therapy.

Ionizing Radiation Deregulates the MicroRNA Expression Profile in Differentiated Thyroid Cells

BACKGROUND

Ionizing radiation (IR) is a well-known risk factor for papillary thyroid cancer, and it has been reported to deregulate microRNA expression, which is important to thyroid carcinogenesis. Therefore, this study investigated the impact of IR on microRNA expression profile of the normal thyroid cell line (FRTL-5 CL2), as well as its effect on radiosensitivity of thyroid cancer cell lines, especially the human anaplastic thyroid carcinoma cell line (8505c).

METHODS

The global microRNA expression profile of irradiated FRTL-5 CL2 cells (5 Gy X-ray) was characterized, and data were confirmed by quantitative real-time polymerase chain reaction evaluating the expression of rno-miR-10b-5p, rno-miR-33-5p, rno-miR-128-1-5p, rno-miR-199a-3p, rno-miR-296-5p, rno-miR-328a-3p, and rno-miR-541-5p in irradiated cells. The miR-199a-3p and miR-10b-5p targets were validated by quantitative real-time polymerase chain reaction, Western blot, and luciferase target assays. The effects of miR-199a-3p and miR-10b-5p on DNA repair were determined by evaluating the activation of the protein kinases ataxia-telangiectasia mutated, ataxia telangiectasia, and Rad3-related and the serine 39 phosphorylation of variant histone H2AX as an indirect measure of double-strand DNA breaks in irradiated FRTL-5 CL2 cells. The impact of miR-10b-5p on radiosensitivity was analyzed by cell counting and MTT assays in FRTL-5 CL2, Kras-transformed FRTL-5 CL2 (FRTL KiKi), and 8505c cell lines.

RESULTS

The results reveal that miR-10b-5p and miR-199a-3p display the most pronounced alterations in expression in irradiated FRTL-5 CL2 cells. Dicer1 and Lin28b were validated as targets of miR-10b-5p and miR-199a-3p, respectively. Functional studies demonstrate that miR-10b-5p increases the growth rate of FRTL-5 CL2 cells, while miR-199a-3p inhibits their proliferation. Moreover, both of these microRNAs negatively affect homologous recombination repair, reducing activated ataxia-telangiectasia mutated and Rad3-related protein levels, consequently leading to an accumulation of the serine 39 phosphorylation of variant histone H2AX. Interestingly, the overexpression of miR-10b-5p decreases the viability of the irradiated FRTL5-CL2 and 8505c cell lines. Consistent with this observation, its inhibition in FRTL KiKi cells, which display high basal expression levels of miR-10b-5p, leads to the opposite effect.

CONCLUSIONS

These results demonstrate that IR deregulates microRNA expression, affecting the double-strand DNA breaks repair efficiency of irradiated thyroid cells, and suggest that miR-10b-5p overexpression may be an innovative approach for anaplastic thyroid cancer therapy by increasing cancer cell radiosensitivity.

Type 2 Diabetes Mellitus and Cardiovascular Disease: Genetic and Epigenetic Links

Type 2 diabetes mellitus (DM) is a common metabolic disorder predisposing to diabetic cardiomyopathy and atherosclerotic cardiovascular disease (CVD), which could lead to heart failure through a variety of mechanisms, including myocardial infarction and chronic pressure overload. Pathogenetic mechanisms, mainly linked to hyperglycemia and chronic sustained hyperinsulinemia, include changes in metabolic profiles, intracellular signaling pathways, energy production, redox status, increased susceptibility to ischemia, and extracellular matrix remodeling. The close relationship between type 2 DM and CVD has led to the common soil hypothesis, postulating that both conditions share common genetic and environmental factors influencing this association. However, although the common risk factors of both CVD and type 2 DM, such as obesity, insulin resistance, dyslipidemia, inflammation, and thrombophilia, can be identified in the majority of affected patients, less is known about how these factors influence both conditions, so that efforts are still needed for a more comprehensive understanding of this relationship. The genetic, epigenetic, and environmental backgrounds of both type 2 DM and CVD have been more recently studied and updated. However, the underlying pathogenetic mechanisms have seldom been investigated within the broader shared background, but rather studied in the specific context of type 2 DM or CVD, separately. As the precise pathophysiological links between type 2 DM and CVD are not entirely understood and many aspects still require elucidation, an integrated description of the genetic, epigenetic, and environmental influences involved in the concomitant development of both diseases is of paramount importance to shed new light on the interlinks between type 2 DM and CVD. This review addresses the current knowledge of overlapping genetic and epigenetic aspects in type 2 DM and CVD, including microRNAs and long non-coding RNAs, whose abnormal regulation has been implicated in both disease conditions, either etiologically or as cause for their progression. Understanding the links between these disorders may help to drive future research toward an integrated pathophysiological approach and to provide future directions in the field.

Retrospective Proteomic Analysis of a Novel, Cancer Metastasis-Promoting RGD-Containing Peptide

Patients who undergo surgical extirpation of a primary liver carcinoma followed by radiotherapy and chemotherapy leading to complete remission are nevertheless known to develop cancerous metastases 3-10 years later. We retrospectively examined the blood sera collected over 8 years from 30 patients who developed bone metastases after the complete remission of liver cancer to identify serum proteins showing differential expression compared to patients without remission. We detected a novel RGD (Arg-Gly-Asp)-containing peptide derived from the C-terminal portion of fibrinogen in the sera of metastatic patients that appeared to control the EMT (epithelial-mesenchymal transition) of cancer cells, in a process associated with miR-199a-3p. The RGD peptide enhanced new blood vessel growth and increased vascular endothelial growth factor levels when introduced into fertilized chicken eggs. The purpose of this study was to enable early detection of metastatic cancer cells using the novel RGD peptide as a biomarker, and thereby develop new drugs for the treatment of metastatic cancer.

MicroRNA 603 acts as a tumor suppressor and inhibits triple-negative breast cancer tumorigenesis by targeting elongation factor 2 kinase

Triple negative breast cancer (TNBC) is an aggressive type of breast cancer characterized by the absence of defined molecular targets, including estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and is associated with high rates of relapse and distant metastasis despite surgery and adjuvant chemotherapy. The lack of effective targeted therapies for TNBC represents an unmet therapeutic challenge. Eukaryotic elongation factor 2 kinase (eEF2K) is an atypical calcium/calmodulin-dependent serine/threonine kinase that promotes TNBC tumorigenesis, progression, and drug resistance, representing a potential novel molecular target. However, the mechanisms regulating eEF2K expression are unknown. Here, we report that eEF2K protein expression is highly up-regulated in TNBC cells and patient tumors and it is associated with poor patient survival and clinical outcome. We found that loss/reduced expression of miR-603 leads to eEF2K overexpression in TNBC cell lines. Its expression results in inhibition of eEF2K by directly targeting the 3-UTR and the inhibition of tumor cell growth, migration and invasion in TNBC. In vivo therapeutic gene delivery of miR-603 into TNBC xenograft mouse models by systemic administration of miR-603-nanoparticles led to a significant inhibition of eEF2K expression and tumor growth, which was associated with decreased activity of the downstream targets of eEF2K, including Src, Akt, cyclin D1 and c-myc. Our findings suggest that miR-603 functions as a tumor suppressor and loss of miR-603 expression leads to increase in eEF2K expression and contributes to the growth, invasion, and progression of TNBC. Taken together, our data suggest that miR-603-based gene therapy is a potential strategy against TNBC.

High mobility group A1 protein modulates autophagy in cancer cells

High Mobility Group A1 (HMGA1) is an architectural chromatin protein whose overexpression is a feature of malignant neoplasias with a causal role in cancer initiation and progression. HMGA1 promotes tumor growth by several mechanisms, including increase of cell proliferation and survival, impairment of DNA repair and induction of chromosome instability. Autophagy is a self-degradative process that, by providing energy sources and removing damaged organelles and misfolded proteins, allows cell survival under stress conditions. On the other hand, hyper-activated autophagy can lead to non-apoptotic programmed cell death. Autophagy deregulation is a common feature of cancer cells in which has a complex role, showing either an oncogenic or tumor suppressor activity, depending on cellular context and tumor stage. Here, we report that depletion of HMGA1 perturbs autophagy by different mechanisms. HMGA1-knockdown increases autophagosome formation by constraining the activity of the mTOR pathway, a major regulator of autophagy, and transcriptionally upregulating the autophagy-initiating kinase Unc-51-like kinase 1 (ULK1). Consistently, functional experiments demonstrate that HMGA1 binds ULK1 promoter region and negatively regulates its transcription. On the other hand, the increase in autophagosomes is not associated to a proportionate increase in their maturation. Overall, the effects of HMGA1 depletion on autophagy are associated to a decrease in cell proliferation and ultimately impact on cancer cells viability. Importantly, silencing of ULK1 prevents the effects of HMGA1-knockdown on cellular proliferation, viability and autophagic activity, highlighting how these effects are, at least in part, mediated by ULK1. Interestingly, this phenomenon is not restricted to skin cancer cells, as similar results have been observed also in HeLa cells silenced for HMGA1. Taken together, these results clearly indicate HMGA1 as a key regulator of the autophagic pathway in cancer cells, thus suggesting a novel mechanism through which HMGA1 can contribute to cancer progression.

MicroRNA-10b mediates TGF-β1-regulated glioblastoma proliferation, migration and epithelial-mesenchymal transition

Although it is well known that exaggerated proliferation, metastasis and the mesenchymal subtype is related with worst prognoses in glioblastoma (GBM) and that transforming growth factor-β1 (TGF-β1) is a potent factor in regulating the proliferation, migration and epithelial-mesenchymal transition (EMT) phenotype of GBM, the detailed mechanisms are still far from elucidated. MicroRNAs (miRNAs) are small non-coding RNAs which play critical roles in various diseases by regulating target gene expression. We report that miR-10b, a molecule downstream of TGF-β1, is involved in TGF-β1-regulated GBM cell proliferation, migration and EMT. We found that exposure of GBM cells to TGF-β1 significantly upregulated miR-10b expression. Overexpression of miR-10b promotes GBM cell proliferation, migration and EMT, whereas depletion of miR-10b obtained reverse effects. Further studies uncovered that some tumor-associated genes including epithelial cadherin (E-cadherin), apoptotic protease activating factor 1 (Apaf-1) and phosphatase and tensin homolog (PTEN) are target genes of miR-10b. In human GBM xenografts, antagomiR directed against miR-10b markedly suppressed tumor growth, and the tumor volume shrunk from 1252.5±285 to 873.4±205 mm3 after antagomiR‑10b treatment for 3 weeks compared with the control group (P<0.01). Taken together, our data collectively demonstrate that the proliferation, migration and EMT features of GBM cells can be regulated by TGF-β1 stimulation through controlling miR-10b. Thus, our findings provide a rationale for targeting TGF-β1 or miR-10b for the treatment of GBM.

Critical role of HMGA proteins in cancer cell chemoresistance

The high-mobility group A (HMGA) proteins are frequently overexpressed in human malignancies and correlate with the presence of metastases and reduced patient survival. Here, we highlight the main studies evidencing a critical role of HMGA in chemoresistance, mainly by activating Akt signaling, impairing p53 activity, and regulating the expression of microRNAs that target genes involved in the susceptibility of cancer cells to antineoplastic agents. Therefore, these studies account for the association of HMGA overexpression with patient poor outcome, indicating the impairment of HMGA as a fascinating perspective for effectively improving cancer therapy.

miR-155 is positively regulated by CBX7 in mouse embryonic fibroblasts and colon carcinomas, and targets the KRAS oncogene

Background

Loss of CBX7 expression has been described in several malignant neoplasias, including human colon and thyroid carcinomas proposing CBX7 as a tumor suppressor gene with a key role in cancer progression. This role is supported from the development of benign and malignant neoplasias in Cbx7 null mice.

The aim of our work has been to investigate the mechanisms underlying the CBX7 oncosuppressor activity by analyzing the microRNAs (miRNAs) regulated by CBX7.

Methods

The miRNA expression profiles of the mouse embryonic fibroblasts (MEFs) null for Cbx7 and the wild-type counterpart were analyzed by the miRNACHIP microarray and then validated by qRT-PCR. To asses KRAS as target of miR-155 we evaluated the protein levels after transfection of the synthetic miR-155. Human colon carcinoma samples have been investigated for the expression of CBX7 and miR-155.

Results

Twenty miRNAs were found upregulated and nine, including miR-155, downregulated in cbx7-null MEFS in comparison with the wild-type ones. Then, we focused on miR-155 since several studies have shown its deregulated expression in several human malignancies and, moreover, was the most downregulated miRNA. Subsequently, we searched for miR-155 target genes demonstrating that KRAS protein levels are directly modulated by miR-155. A direct significant correlation (r = 0.6779) between CBX7 and miR-155 expression levels was found in a set of human colon carcinoma tissue samples.

Conclusion

miR-155 is positively regulated by CBX7 in MEFs and colon carcinomas, and has KRAS as one of the target genes likely accounting for the anti-apoptotic activity ascribed to miR-155 in some tissue contexts.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3158-z) contains supplementary material, which is available to authorized users.

Therapeutic potential of targeting microRNA-10b in established intracranial glioblastoma: first steps toward the clinic

MicroRNA-10b (miR-10b) is a unique oncogenic miRNA that is highly expressed in all GBM subtypes, while absent in normal neuroglial cells of the brain. miR-10b inhibition strongly impairs proliferation and survival of cultured glioma cells, including glioma-initiating stem-like cells (GSC). Although several miR-10b targets have been identified previously, the common mechanism conferring the miR-10b-sustained viability of GSC is unknown. Here, we demonstrate that in heterogeneous GSC, miR-10b regulates cell cycle and alternative splicing, often through the non-canonical targeting via 5'UTRs of its target genes, including MBNL1-3, SART3, and RSRC1. We have further assessed the inhibition of miR-10b in intracranial human GSC-derived xenograft and murine GL261 allograft models in athymic and immunocompetent mice. Three delivery routes for the miR-10b antisense oligonucleotide inhibitors (ASO), direct intratumoral injections, continuous osmotic delivery, and systemic intravenous injections, have been explored. In all cases, the treatment with miR-10b ASO led to targets' derepression, and attenuated growth and progression of established intracranial GBM. No significant systemic toxicity was observed upon ASO administration by local or systemic routes. Our results indicate that miR-10b is a promising candidate for the development of targeted therapies against all GBM subtypes.

Ablation of miR-10b Suppresses Oncogene-Induced Mammary Tumorigenesis and Metastasis and Reactivates Tumor-Suppressive Pathways

The invasive and metastatic properties of many human tumors have been associated with upregulation of the miRNA miR-10b, but its functional contributions in this setting have not been fully unraveled. Here, we report the generation of miR-10b-deficient mice, in which miR-10b is shown to be largely dispensable for normal development but critical to tumorigenesis. Loss of miR-10b delays oncogene-induced mammary tumorigenesis and suppresses epithelial-mesenchymal transition, intravasation, and metastasis in a mouse model of metastatic breast cancer. Among the target genes of miR-10b, the tumor suppressor genes Tbx5 and Pten and the metastasis suppressor gene Hoxd10 are significantly upregulated by miR-10b deletion. Mechanistically, miR-10b promotes breast cancer cell proliferation, migration, and invasion through inhibition of the expression of the transcription factor TBX5, leading to repression of the tumor suppressor genes DYRK1A and PTEN In clinical specimens of breast cancer, the expression of TBX5, HOXD10, and DYRK1A correlates with relapse-free survival and overall survival outcomes in patients. Our results establish miR-10b as an oncomiR that drives metastasis, termed a metastamiR, and define the set of critical tumor suppressor mechanisms it overcomes to drive breast cancer progression. Cancer Res; 76(21); 6424-35. ©2016 AACR.

Potential role of microRNA-10b down-regulation in cardiomyocyte apoptosis in aortic stenosis patients

Myocardial miR-10b down-regulation may be involved in the increase in cardiomyocyte apoptosis in AS patients, probably through apoptosis protease-activating factor-1 (Apaf-1) regulation. In turn, increased cardiomyocyte apoptosis contributes to cardiomyocyte damage and heart failure (HF) development.

Differences in Circulating microRNAs between Grazing and Grain-Fed Wagyu Cattle Are Associated with Altered Expression of Intramuscular microRNA, the Potential Target PTEN, and Lipogenic Genes

We aimed to understand the roles of miRNAs in the muscle tissue maturation and those of circulating microRNAs (c-miRNAs) in beef production of Japanese Black (JB) cattle (Wagyu), a breed with genetically background of superior intermuscular fat depot, by comparing different feeding conditions (indoor grain-feeding vs. grazing on pasture). The cattle at 18 months old were assigned to pasture feeding or conventional indoor grain feeding conditions for 5 months. Microarray analysis of c-miRNAs from the plasma extracellular vesicles led to the detection of a total of 202 bovine miRNAs in the plasma, including 15 miRNAs that differed between the feeding conditions. Validation of the microarray results by qPCR showed that the circulating miR-10b level in the grazing cattle was upregulated compared to that of the grain-fed cattle. In contrast, the levels of miR-17-5p, miR-19b, miR-29b, miR-30b-5p, miR-98, miR-142-5p, miR-301a, miR-374b, miR-425-5p, and miR-652 were lower in the grazing cattle than in the grain-fed cattle. Bioinformatic analysis indicated that the predicted target genes of those c-miRNAs were enriched in gene ontology terms associated with blood vessel morphogenesis, plasma membrane, focal adhesion, endocytosis, collagen, ECM-receptor interaction, and phosphorylation. In the grazing cattle, the elevation of miR-10b expression in the plasma was coincident with its elevation in the longissimus lumborum (LL) muscle. Expression of bovine-specific miR-2478, the most plasma-enriched miRNA, tended to be also upregulated in the muscle but not in the plasma. Furthermore, grazing caused the downregulated mRNA expression of predicted miR-10b and/or miR-2478 target genes, such as DNAJB2, PTEN, and SCD1. Thus, the feeding system used for JB cattle affected the c-miRNAs that could be indicators of grain feeding. Among these, miR-10b expression was especially associated with feeding-induced changes and with the expression of the potential target genes responsible for glucose homeostasis and intramuscular fat depot in the LL muscle of JB cattle.

HMGA1 silencing reduces stemness and temozolomide resistance in glioblastoma stem cells

OBJECTIVE

Glioblastoma multiforme (GBM) develops from a small subpopulation of stem-like cells, which are endowed with the ability to self-renew, proliferate and give rise to progeny of multiple neuroepithelial lineages. These cells are resistant to conventional chemo- and radiotherapy and are hence also responsible for tumor recurrence. HMGA1 overexpression has been shown to correlate with proliferation, invasion, and angiogenesis of GBMs and to affect self-renewal of cancer stem cells from colon cancer. The role of HMGA1 in GBM tumor stem cells is not completely understood.

RESEARCH DESIGN AND METHODS

We have investigated the role of HMGA1 in brain tumor stem cell (BTSC) self-renewal, stemness and resistance to temozolomide by shRNA- mediated HMGA1 silencing.

RESULTS

We first report that HMGA1 is overexpressed in a subset of BTSC lines from human GBMs. Then, we show that HMGA1 knockdown reduces self-renewal, sphere forming efficiency and stemness, and sensitizes BTSCs to temozolomide. Interestingly, HMGA1 silencing also leads to reduced tumor initiation ability in vivo.

CONCLUSIONS

These results demonstrate a pivotal role of HMGA1 in cancer stem cell gliomagenesis and endorse HMGA1 as a suitable target for CSC-specific GBM therapy.

Deregulation of HMGA1 expression induces chromosome instability through regulation of spindle assembly checkpoint genes

The mitotic spindle assembly checkpoint (SAC) is an essential control system of the cell cycle that contributes to mantain the genomic stability of eukaryotic cells. SAC genes expression is often deregulated in cancer cells, leading to checkpoint impairment and chromosome instability. The mechanisms responsible for the transcriptional regulation and deregulation of these genes are still largely unknown. Herein we identify the nonhistone architectural nuclear proteins High Mobility Group A1 (HMGA1), whose overexpression is a feature of several human malignancies and has a key role in cancer progression, as transcriptional regulators of SAC genes expression. In particular, we show that HMGA1 proteins are able to increase the expression of the SAC genes Ttk, Mad2l1, Bub1 and Bub1b, binding to their promoter regions. Consistently, HMGA1-depletion induces SAC genes downregulation associated to several mitotic defects. In particular, we observed a high number of unaligned chromosomes in metaphase, a reduction of prometaphase time, a delay of anaphase, a higher cytokinesis time and a higher percentage of cytokinesis failure by using live-cell microscopy. Finally, a significant direct correlation between HMGA1 and SAC genes expression was detected in human colon carcinomas indicating a novel mechanism by which HMGA1 contributes to cancer progression.

Secreted uPAR isoform 2 (uPAR7b) is a novel direct target of miR-221

miR-221/-222 and components of the urokinase-type plasminogen activator system (uPAS) are associated with metastasis and poor prognosis in breast cancer, including the triple-negative subtype (TNBC). Modification of components of uPAS and involved miRNAs may contribute to targeted therapy for breast cancer patients. miR-221−/−222-overexpressing or miR-221-depleted cells were employed for qRT-PCR and Western blots to show associations of uPAR with miR-221/-222. To substantiate direct targeting of miR-221/-222 within 3′ UTR of the uPAR isoform 2, in silico analysesand in vitro assays were conducted. Significant associations between miR-221 and uPAR isoform 2 expressions were observed at the mRNA and protein levels in breast cancer cells representing TNBC. For the first time, the uPAR isoform 2 was demonstrated as direct target for miR-221/-222. Inhibition of miR-221 reduced uPAR protein expression and expression of the tumor cell invasion markers vimentin and RHOC. These results demonstrate a direct and positive regulation of the secreted uPAR isoform 2 by miR-221, increasing its protein expression, a prerequisite for malignancy, while the other uPAR isoforms (1, 3 and 4) are indirectly regulated through miR-10b and miR-221/-222. By targeting uPAR isoforms and/or miRNA-221/-222, the diagnosis and therapy of breast cancer, in particular in TNBC, could be significantly improved.

MicroRNA-603 functions as an oncogene by suppressing BRCC2 protein translation in osteosarcoma

The present study was conducted to investigate the expression of miR-603 in osteosarcoma cells, and the effect of miR-603 on the biological behavior and expression of breast cancer cell 2 (BRCC2) in osteosarcoma cells. In the present study, qRT-PCR was used to measure the levels of miRNA and mRNA. The results showed that miR-603 was significantly upregulated in human osteosarcoma tissues and cell lines. MTT and colony formation assays were employed to evaluate the role of miR-603 in the regulation of osteosarcoma cell proliferation. The results showed that overexpression of miR-603 promoted the proliferation of MG-63 and U2OS cells. Furthermore, a nude mouse subcutaneous tumor model indicated that miR-603 promoted osteosarcoma growth in vivo. Moreover, miR-603 expression levels were increased in patients with distant metastasis in comparison with levels in patients without distant metastasis. We discovered that BRCC2 may be a target of miR-603. Our results demonstrated that overexpression of miR-603 suppressed BRCC2 protein expression, and an miR-603 inhibitor enhanced BRCC2 protein expression as determined by western blot assay and immunohistochemical analysis. Luciferase reporter assays confirmed that BRCC2 is a direct target of miR-603 in osteosarcoma cells, and the results suggest that miR-603 downregulates BRCC2 expression in osteosarcoma via translational inhibition. Finally, we found that the reduction in BRCC2 expression induced by miR-603 was responsible for the enhanced colony formation and proliferative ability noted in the MG-63 and U2OS cells. In conclusion, miR-603 enhanced osteosarcoma growth by downregulation of BRCC2 expression via translational inhibition.

RNA-Mediated Regulation of HMGA1 Function

The high mobility group protein A1 (HMGA1) is a master regulator of chromatin structure mediating its major gene regulatory activity by direct interactions with A/T-rich DNA sequences located in the promoter and enhancer regions of a large variety of genes. HMGA1 DNA-binding through three AT-hook motifs results in an open chromatin structure and subsequently leads to changes in gene expression. Apart from its significant expression during development, HMGA1 is over-expressed in virtually every cancer, where HMGA1 expression levels correlate with tumor malignancy. The exogenous overexpression of HMGA1 can lead to malignant cell transformation, assigning the protein a key role during cancerogenesis. Recent studies have unveiled highly specific competitive interactions of HMGA1 with cellular and viral RNAs also through an AT-hook domain of the protein, significantly impacting the HMGA1-dependent gene expression. In this review, we discuss the structure and function of HMGA1-RNA complexes during transcription and epigenomic regulation and their implications in HMGA1-related diseases.

MicroRNA-10b inhibition reduces E2F1-mediated transcription and miR-15/16 activity in glioblastoma

MicroRNA-10b (miR-10b) is commonly elevated in glioblastoma (GBM), while not expressed in normal brain tissues. Targeted inhibition of miR-10b has pleiotropic effects on GBM derived cell lines, it reduces GBM growth in animal models, but does not affect normal neurons and astrocytes. This data raises the possibility of developing miR-10b-targeting GBM therapy. However, the mechanisms contributing to miR-10b-mediated glioma cell survival and proliferation are unexplored. We found that inhibition of miR-10b has distinct effects on specific glioma cell lines. In cells expressing high levels of tumor suppressor p21WAF1/Cip1, it represses E2F1-mediated transcription, leading to down-regulation of multiple E2F1 target genes encoding for S-phase specific proteins, epigenetic modulators, and miRNAs (e.g. miR-15/16), and thereby stalling progression through the S-phase of cell cycle. Subsequently, miR-15/16 activities are reduced and many of their direct targets are de-repressed, including ubiquitin ligase FBXW7 that destabilizes Cyclin E. Conversely, GBM cells expressing low p21 level, or after p21 knock-down, exhibit weaker or no E2F1 response to miR-10b inhibition. Comparative analysis of The Cancer Genome Atlas revealed a strong correlation between miR-10b and multiple E2F target genes in GBM and low-grade glioma. Taken together, these findings indicate that miR-10b regulates E2F1-mediated transcription in GBM, in a p21-dependent fashion.

miR-198 Represses the Proliferation of HaCaT Cells by Targeting Cyclin D2

Background: MiR-198 has been considered as an inhibitor of cell proliferation, invasion, migration and a promoter of apoptosis in most cancer cells, while its effect on non-cancer cells is poorly understood. Methods: The effect of miR-198 transfection on HaCaT cell proliferation was firstly detected using Cell Count Kit-8 and the cell cycle progression was analyzed by flow cytometry. Using bioinformatics analyses and luciferase assay, a new target of miR-198 was searched and identified. Then, the effect of the new target gene of miR-198 on cell proliferation and cell cycle was also detected. Results: Here we showed that miR-198 directly bound to the 3′-UTR of CCND2 mRNA, which was a key regulator in cell cycle progression. Overexpressed miR-198 repressed CCND2 expression at mRNA and protein levels and subsequently led to cell proliferation inhibition and cell cycle arrest in the G1 phase. Transfection ofSiCCND2 in HaCaT cells showed similar inhibitory effects on cell proliferation and cell cycle progression. Conclusion: In conclusion, we have identified that miR-198 inhibited HaCaT cell proliferation by directly targeting CCND2.

miR-603 promotes glioma cell growth via Wnt/β-catenin pathway by inhibiting WIF1 and CTNNBIP1

Gliomas are the most common and deadly type of brain tumor. In spite of progressive treatments, patient prognosis has not improved significantly. MicroRNAs are considered promising candidates for glioma therapy. MiR-603 was found overexpressed in both glioma tissues and cell lines. MiR-603 promoted cell proliferation, cell cycle progression and neurosphere formation. Conversely, inhibition of miR-603 remarkably reduced these effects. We confirmed that WIF1 and CTNNBIP1 are bona fide targets of miR-603. The negative correlation between miR-603 and these molecules' expression was shown by Pearson correlation in 50 primary glioma tissue samples. Furthermore, overexpression of miR-603 promoted nuclear β-catenin levels and TOPflash luciferase activity, indicating that miR-603 activates the Wnt/β-catenin signaling pathway. Our in vivo results confirmed the positive role of miR-603 in glioma development. We demonstrate that miR-603 regulates glioma development via its WIF1 and CTNNBIP1 targets, which suggests that miR-603 may be a promising candidate for therapeutic applications in glioma treatment.

Hitting the bull's eye: targeting HMGA1 in cancer stem cells

Emerging evidence suggests that when cancer cells hijack normal stem cell properties, they acquire the ability to invade, metastasize to distant sites and evade therapy. Thus, eliminating cancer cells with stem cell properties, or cancer stem cells, is of prime importance for the successful treatment of cancer, regardless of the tissue of origin. Previous efforts to target cancer stem cells (CSCs), however, have been largely unsuccessful. Recent studies led to the discovery of a novel role for the high mobility group A1 (HMGA1) protein as a master regulator in both CSCs and normal embryonic stem cells. Here, we present exciting new work unveiling HMGA1 as a promising target for therapies directed at eradicating CSCs.

Aberrant microRNA expression likely controls RAS oncogene activation during malignant transformation of human prostate epithelial and stem cells by arsenic

Inorganic arsenic (iAs), a human carcinogen, potentially targets the prostate. iAs malignantly transforms the RWPE-1 human prostate epithelial line to CAsE-PE cells, and a derivative normal stem cell (SC) line, WPE-stem, to As-Cancer SC (As-CSC) line. MicroRNAs (miRNA) are noncoding but exert negative control on expression by degradation or translational repression of target mRNAs. Aberrant miRNA expression is important in carcinogenesis. A miRNA array of CAsE-PE and As-CSC revealed common altered expression in both for pathways concerning oncogenesis, miRNA biogenesis, cell signaling, proliferation, and tumor metastasis and invasion. The KRAS oncogene is overexpressed in CAsE-PE cells but not by mutation or promoter hypomethylation, and is intensely overexpressed in As-CSC cells. In both transformants, decreased miRNAs targeting KRAS and RAS superfamily members occurred. Reduced miR-134, miR-373, miR-155, miR-138, miR-205, miR-181d, miR-181c, and let-7 in CAsE-PE cells correlated with increased target RAS oncogenes, RAN, RAB27A, RAB22A mRNAs, and KRAS protein. Reduced miR-143, miR-34c-5p, and miR-205 in As-CSC correlated with increased target RAN mRNA, and KRAS, NRAS, and RRAS proteins. The RAS/ERK and PI3K/PTEN/AKT pathways control cell survival, differentiation, and proliferation, and when dysregulated promote a cancer phenotype. iAs transformation increased expression of activated ERK kinase in both transformants and altered components of the PI3K/PTEN/AKT pathway including decreased PTEN and increases in BCL2, BCL-XL, and VEGF in the absence of AKT activation. Thus, dysregulated miRNA expression may be linked to RAS activation in both transformants.

The high mobility group A1 molecular switch: turning on cancer - can we turn it off?

INTRODUCTION

Emerging evidence demonstrates that the high mobility group A1 (HMGA1) chromatin remodeling protein is a key molecular switch required by cancer cells for tumor progression and a poorly differentiated, stem-like state. Because the HMGA1 gene and proteins are expressed at high levels in all aggressive tumors studied to date, research is needed to determine how to 'turn off' this master regulatory switch in cancer.

AREAS COVERED

In this review, we describe prior studies that underscore the central role of HMGA1 in refractory cancers and we discuss approaches to target HMGA1 in cancer therapy.

EXPERT OPINION

Given the widespread overexpression of HMGA1 in diverse, aggressive tumors, further research to develop technology to target HMGA1 holds immense promise as potent anticancer therapy. Previous work in preclinical models indicates that delivery of short hairpin RNA or interfering RNA molecules to 'switch off' HMGA1 expression dramatically impairs cancer cell growth and tumor progression. The advent of nanoparticle technology to systemically deliver DNA or RNA molecules to tumors brings this approach even closer to clinical applications, although further efforts are needed to translate these advances into therapies for cancer patients.

Correlated expression of HMGA2 and PLAG1 in thyroid tumors, uterine leiomyomas and experimental models

In pleomorphic adenomas of the salivary glands (PASG) recurrent chromosomal rearrangements affecting either 8q12 or 12q14∼15 lead to an overexpression of the genes of the genuine transcription factor PLAG1 or the architectural transcription factor HMGA2, respectively. Both genes are also affected by recurrent chromosomal rearrangements in benign adipocytic tumors as e. g. lipomas and lipoblastomas. Herein, we observed a strong correlation between the expression of HMGA2 and PLAG1 in 14 benign and 23 malignant thyroid tumors. To address the question if PLAG1 can be activated by HMGA2, the expression of both genes was quantified in 32 uterine leiomyomas 17 of which exhibited an overexpression of HMGA2. All leiomyomas with HMGA2 overexpression also revealed an activation of PLAG1 in the absence of detectable chromosome 8 abnormalities affecting the PLAG1 locus. To further investigate if the overexpression of PLAG1 is inducible by HMGA2 alone, HMGA2 was transiently overexpressed in MCF-7 cells. An increased PLAG1 expression was observed 24 and 48 h after transfection. Likewise, stimulation of HMGA2 by FGF1 in adipose tissue-derived stem cells led to a simultaneous increase of PLAG1 mRNA. Altogether, these data suggest that HMGA2 is an upstream activator of PLAG1. Accordingly, this may explain the formation of tumors as similar as lipomas and lipoblastomas resulting from an activation of either of both genes by chromosomal rearrangements.

MicroRNA-10b promotes nucleus pulposus cell proliferation through RhoC-Akt pathway by targeting HOXD10 in intervetebral disc degeneration

Aberrant proliferation of nucleus pulposus cell is implicated in the pathogenesis of intervertebral disc degeneration. Recent findings revealed that microRNAs, a class of small noncoding RNAs, could regulate cell proliferation in many pathological conditions. Here, we showed that miR-10b was dramatically upregulated in degenerative nucleus pulposus tissues when compared with nucleus pulposus tissues isolated from patients with idiopathic scoliosis. Moreover, miR-10b levels were associated with disc degeneration grade and downregulation of HOXD10. In cultured nucleus pulposus cells, miR-10b overexpression stimulated cell proliferation with concomitant translational inhibition of HOXD10 whereas restored expression of HOXD10 reversed the mitogenic effect of miR-10b. MiR-10b-mediated downregulation of HOXD10 led to increased RhoC expression and Akt phosphorylation. Either knockdown of RhoC or inhibition of Akt abolished the effect of miR-10b on nucleus pulposus cell proliferation. Taken together, aberrant miR-10b upregulation in intervertebral disc degeneration could contribute to abnormal nucleus pulposus cell proliferation through derepressing the RhoC-Akt pathway by targeting HOXD10. Our study also underscores the potential of miR-10b and the RhoC-Akt pathway as novel therapeutic targets in intervertebral disc degeneration.

The High Mobility Group A proteins contribute to thyroid cell transformation by regulating miR-603 and miR-10b expression

The overexpression of the HMGA1 proteins is a feature of human malignant neoplasias and has a causal role in cell transformation. The aim of our study has been to investigate the microRNAs (miRNAs or miRs) regulated by the HMGA1 proteins in the process of cell transformation analyzing the miRNA expression profile of v-ras-Ki oncogene-transformed thyroid cells expressing or not HMGA1 proteins. We demonstrate that, among the miRNAs regulated by cell transformation, there are miR-10b, miR-21, miR-125b, miR-221 and miR-222 that are positively and miR-34a and miR-603 that are negatively regulated by HMGA1 expression. Then, we focused our attention on the miR-10b and miR-603 whose expression was dependent on the presence of HMGA1 also in other cell systems. We found that miR-10b is able to target the PTEN gene, whereas miR-603 targets the CCND1 and CCND2 genes coding for the cyclin D1 and cyclin D2 proteins, respectively. Moreover, functional studies showed that miR-10b and miR-603 regulate positively and negatively, respectively, cell proliferation and migration suggesting a role of their dysregulation in thyroid cell transformation.