Trichostatin A and Tamoxifen inhibit breast cancer cell growth by miR-204 and ERα reducing AKT/mTOR pathway

The Impact of miRNAs on the Efficacy of Tamoxifen in Breast Cancer Treatment: A Systematic Review

Seventy percent of breast cancer patients have an active estrogen receptor. Tamoxifen interferes with estrogen's ability to bind to cancer cells. The most challenging aspect of tamoxifen, however, is that breast cancer cells become resistant to its effects. Some studies have shown that alterations in miRNA expression contribute significantly to drug resistance in breast cancer. Therefore, the present systematic review aims to investigate miRNAs that significantly influence the response to tamoxifen treatment. The present study follows the PRISMA instructions. The Web of Science, PubMed, and Scopus databases were searched to retrieve English articles. The searches were conducted up to September 11, 2022. The search strategy included the terms "Tamoxifen", "Breast Neoplasm", and "MicroRNA". The inclusion criteria of this study are English, original, and experimental studies investigating miRNAs that are effective in the treatment efficacy of tamoxifen. A total of 565 articles were retrieved. After screening, 75 studies met our inclusion criteria. This systematic review study examined 105 miRNAs, of which 44 have a positive effect, and 47 miRNAs inhibit tamoxifen function. Fourteen miRNAs have a controversial effect, ie, some studies show positive and negative effects. The study of miRNAs affecting tamoxifen function in breast cancer patients may facilitate the identification of individuals at higher risk of disease recurrence. Conversely, it can potentially utilize appropriate interventions to defeat drug resistance effectively.

Epigenetic Dysregulation and Its Correlation with the Steroidogenic Machinery Impacting Breast Pathogenesis: Data Mining and Molecular Insights into Therapeutics

Breast cancer (BC) is a heterogeneous condition and comprises molecularly distinct subtypes. An imbalance in the levels of epigenetic histone deacetylases (HDACs), modulating estrogen accumulation, especially 17β-estradiol (E2), promotes breast tumorigenesis. In the present study, analyses of The Cancer Genome Atlas (TCGA) pan-cancer normalized RNA-Seq datasets revealed the dysregulation of 16 epigenetic enzymes (among a total of 18 members) in luminal BC subtypes, in comparison to their non-cancerous counterparts. Explicitly, genomic profiling of these epigenetic enzymes displayed increases in HDAC1, 2, 8, 10, 11, and Sirtuins (SIRTs) 6 and 7, and decreases in HDAC4-7, -9, and SIRT1-4 levels, respectively, in TCGA breast tumors. Kaplan-Meier plot analyses showed that these HDACs, with the exception of HDAC2 and SIRT2, were not correlated with the overall survival of BC patients. Additionally, disruption of the epigenetic signaling in TCGA BC subtypes, as assessed using both heatmaps and boxplots, was associated with the genomic expression of factors that are instrumental for cholesterol trafficking/utilization for accelerating estrogen/E2 levels, in which steroidogenic acute regulatory protein (STAR) mediates the rate-limiting step in steroid biosynthesis. TCGA breast samples showed diverse expression patterns of a variety of key steroidogenic markers and hormone receptors, including LIPE, CYP27A1, STAR, STARD3, CYP11A1, CYP19A1, ER, PGR, and ERBB2. Moreover, regulation of STAR-governed steroidogenic machinery was found to be influenced by various transcription factors, i.e., CREB1, CREM, SF1, NR4A1, CEBPB, SREBF1, SREBF2, SP1, FOS, JUN, NR0B1, and YY1. Along these lines, ingenuity pathway analysis (IPA) recognized a number of new targets and downstream effectors influencing BCs. Of note, genomic, epigenomic, transcriptional, and hormonal anomalies observed in human primary breast tumors were qualitatively similar in pertinent BC cell lines. These findings identify the functional correlation between dysregulated epigenetic enzymes and estrogen/E2 accumulation in human breast tumors, providing the molecular insights into more targeted therapeutic approaches involving the inhibition of HDACs for combating this life-threatening disease.

The role of vulpinic acid as a natural compound in the regulation of breast cancer-associated miRNAs

Background

Breast cancer is the most frequently diagnosed cancer, and no effective treatment solution has yet been found. The number of studies based on the research of novel natural compounds in the treatment of breast cancer has been increasing in recent years. The anticancer properties of natural compounds are related to the regulation of microRNA (miRNA) expression. Therefore, changing the profile of miRNAs with the use of natural products is very important in cancer treatment. However, the role of vulpinic acid and related miRNAs in breast cancer progression remains unknown. Vulpinic acid, methyl (as2E)-2-(3-hydroxy-5-oxo-4-phenylfuran-2-ylidene)-2 phenylacetate, is a natural product extracted from the lichen species and shows an anticancer effect on different cancer cells.

Methods

This study examines the effects of vulpinic acid on the miRNA levels of breast cancer (MCF-7) cells and its relationship with cell proliferation and apoptosis levels. The antiproliferative effect of vulpinic acid was screened against MCF-7 breast cancer cells and MCF-12A breast epithelial cells using the xCELLigence real-time cell analysis system. We analyzed the altered miRNA expression profile in MCF-7 breast cancer cells versus MCF-12A cells following their response to vulpinic acid through microarray analysis. The microarray analysis results were confirmed through quantitative real-time PCR and bioinformatics analysis.

Results

The results of the miRNA array and bioinformatic analyses demonstrated that 12 miRNAs were specifically responsive to vulpinic acid in MCF-7 breast cancer cells. This is the first study to reveal that vulpinic acid inhibits the expression of 12 miRNAs and suppresses breast cancer cell proliferation. The study also revealed that vulpinic acid may downregulate the expression of 12 miRNAs by repressing the FOXO-3 gene. The miRNA targets were mainly found to play a role in the apoptosis, cell cycle and MAPK pathways. Moreover, Bcl-2, Bax, procaspase-3 and procaspase-9 protein levels were assessed by western blot analysis for validation of apoptosis at the protein level.

Conclusion

This study revealed the molecular mechanisms of vulpinic acid on breast cancer and showed that vulpinic acid regulates apoptosis signaling pathways by decreasing the expression of miRNAs. The miRNA expression patterns illuminate the underlying effect of vulpinic acid in breast cancer treatment.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-021-00360-4.

The regulatory role of pivotal microRNAs in the AKT signaling pathway in breast cancer

Breast cancer is the most prevalent type of cancer among women, and it remains the main challenge despite improved treatments. MicroRNAs (miRNAs) are a small non-coding family of RNAs that play an indispensable role in regulating major physiological processes, including differentiation, proliferation, invasion, migration, cell cycle regulation, stem cell maintenance, apoptosis, and organ development. The dysregulation of these tiny molecules is associated with various human malignancies. More than 50% of these non-coding RNA sequences estimated have been placed on genomic regions or fragile sites linked to cancer. Following the discovery of the first signatures of specific miRNA in breast cancer, numerous researches focused on involving these tiny RNAs in breast cancer physiopathology as a new therapeutic approach or as reliable prognostic biomarkers. In the current review, we focus on recent findings related to the involvement of miRNAs in breast cancer via the AKT signaling pathway and the related clinical implications.

Development of omics biomarkers for estrogen exposure using mRNA, miRNA and piRNAs

The number of chemicals requiring risk evaluation exceeds our capacity to provide the underlying data using traditional methodology. This has led to an increased focus on the development of novel approach methodologies. This work aimed to expand the panel of gene expression-based biomarkers to include responses to estrogens, to identify training strategies that maximize the range of applicable concentrations, and to evaluate the potential for two classes of small non-coding RNAs (sncRNAs), microRNA (miRNA) and piwi-interacting RNA (piRNA), as biomarkers. To this end larval Pimephales promelas (96 hpf +/- 1h) were exposed to 5 concentrations of 17α- ethinylestradiol (0.12, 1.25, 2.5, 5.0, 10.0 ng/L) for 48 h. For mRNA-based biomarker development, RNA-seq was conducted across all concentrations. For sncRNA biomarkers, small RNA libraries were prepared only for the control and 10.0 ng/L EE2 treatment. In order to develop an mRNA classifier that remained accurate over the range of exposure concentrations, three different training strategies were employed that focused on 10 ng/L, 2.5 ng/L or a combination of both. Classifiers were tested against an independent test set of individuals exposed to the same concentrations used in training and subsequently against concentrations not included in model training. Both random forest (RF) and logistic regression with elastic net regularizations (glmnet) models trained on 10 ng/L EE2 performed poorly when applied to lower concentrations. RF models trained with either the 2.5 ng/L or combination (2.5 + 10 ng/L) treatments were able to accurately discriminate exposed vs. non-exposed across all but the lowest concentrations. glmnet models were unable to accurately classify below 5 ng/L. With the exception of the 10 ng/L treatment, few mRNA differentially expressed genes (DEG) were observed, however, there was marked overlap of DEGs across treatments. Overlapping DEGs have well established linkages to estrogen and several of the 81 DEGs identified in the 10 ng/L treatment have been previously utilized as estrogenic biomarkers (vitellogenin, estrogen receptor-β). Following multiple test correction, no sncRNAs were found to be differentially expressed, however, both miRNA and piRNA classifiers were able to accurately discriminate control and 10 ng/L exposed organisms with AUCs of 0.83 and 1.0 respectively. We have developed a highly discriminative estrogenic mRNA biomarker that is accurate over a range of concentrations likely to be found in real-world exposures. We have demonstrated that both miRNA and piRNA are responsive to estrogenic exposure, suggesting the need to further investigate their regulatory roles in the estrogenic response.

Potential miRNAs for miRNA-Based Therapeutics in Breast Cancer

MicroRNAs (miRNAs) are small non-coding RNAs that can post-transcriptionally regulate the genes involved in critical cellular processes. The aberrant expressions of oncogenic or tumor suppressor miRNAs have been associated with cancer progression and malignancies. This resulted in the dysregulation of signaling pathways involved in cell proliferation, apoptosis and survival, metastasis, cancer recurrence and chemoresistance. In this review, we will first (i) provide an overview of the miRNA biogenesis pathways, and in vitro and in vivo models for research, (ii) summarize the most recent findings on the roles of microRNAs (miRNAs) that could potentially be used for miRNA-based therapy in the treatment of breast cancer and (iii) discuss the various therapeutic applications.

Breaking the paradigm: Dr Insight empowers signature-free, enhanced drug repurposing

Motivation

Transcriptome-based computational drug repurposing has attracted considerable interest by bringing about faster and more cost-effective drug discovery. Nevertheless, key limitations of the current drug connectivity-mapping paradigm have been long overlooked, including the lack of effective means to determine optimal query gene signatures.

Results

The novel approach Dr Insight implements a frame-breaking statistical model for the ‘hand-shake’ between disease and drug data. The genome-wide screening of concordantly expressed genes (CEGs) eliminates the need for subjective selection of query signatures, added to eliciting better proxy for potential disease-specific drug targets. Extensive comparisons on simulated and real cancer datasets have validated the superior performance of Dr Insight over several popular drug-repurposing methods to detect known cancer drugs and drug–target interactions. A proof-of-concept trial using the TCGA breast cancer dataset demonstrates the application of Dr Insight for a comprehensive analysis, from redirection of drug therapies, to a systematic construction of disease-specific drug-target networks.

Availability and implementation

Dr Insight R package is available at https://cran.r-project.org/web/packages/DrInsight/index.html.

Supplementary information

Supplementary data are available at Bioinformatics online.

Knockdown of the long noncoding RNA XIST suppresses glioma progression by upregulating miR-204-5p

Background: Gliomas are the most prevalent primary malignant tumors of the central nervous system. Our previous study showed that miR-204-5p is a tumor suppressor gene in glioma. Bioinformatic analyses suggest that long noncoding RNA (lncRNA) X-inactive specific transcript (XIST) is a potential target gene of miR-204-5p.

Methods: We analyzed the expression of XIST and miR-204-5p in glioma tissues and the correlation with glioma grade. A series of in vitro experiments were carried out to elucidate the role of XIST in glioma progression. A mouse xenograft model was established to detect whether knockdown of XIST can inhibit glioma growth. A luciferase assay was performed to determine whether XIST can bind to miR-204-5p and the binding specificity. Cells stably expressing shXIST or shNC were transfected with anti-miR-204-5p or anti-miR-204-5p-NC to evaluate whether XIST mediates the tumor-suppressive effects of miR-204-5p.

Results: XIST was upregulated in glioma tissues compared with normal brain tissues (NBTs), while miR-204-5p expression was significantly decreased in glioma tissues compared with NBTs. Both XIST and miR-204-5p expression levels were clearly related to glioma grade, and the expression of XIST was obviously negatively correlated with miR-204-5p expression. Knockdown of XIST inhibited glioma cell proliferation, migration, and invasion, promoted apoptosis of glioma cells, inhibited tumor growth and increased the survival time in nude mice. miR-204-5p could directly bind to XIST and negatively regulate XIST expression. XIST mediated glioma progression by targeting miR-204-5p in glioma cells. XIST crosstalk with miR-204-5p regulated Bcl-2 expression to promote apoptosis.

Conclusion: Our results provide evidence that XIST, miR-204-5p and Bcl-2 form a regulatory axis that controls glioma progression and can serve as a potential therapeutic target for glioma.

Comprehensive analysis of the lncRNA‑associated competing endogenous RNA network in breast cancer

Long noncoding RNAs (lncRNAs) have been confirmed to be potential prognostic markers in a variety of cancers and to interact with microRNAs (miRNAs) as competing endogenous RNAs (ceRNAs) to regulate target gene expression. However, the role of lncRNA‑mediated ceRNAs in breast cancer (BC) remains unclear. In the present study, a ceRNA network was generated to explore their role in BC. The expression profiles of mRNAs, miRNAs and lncRNAs in 1,109 BC tissues and 113 normal breast tissues were obtained from The Cancer Genome Atlas database (TCGA). A total of 3,198 differentially expressed (DE) mRNAs, 150 differentially DEmiRNAs and 1,043 DElncRNAs were identified between BC and normal tissues. A lncRNA‑miRNA‑mRNA network associated with BC was successfully constructed based on the combined data obtained from RNA databases, and comprised 97 lncRNA nodes, 24 miRNA nodes and 74 mRNA nodes. The biological functions of the 74 DEmRNAs were further investigated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The results demonstrated that the DEmRNAs were significantly enriched in two GO biological process categories; the main biological process enriched term was 'positive regulation of GTPase activity'. By KEGG analysis, four key enriched pathways were obtained, including the 'MAPK signaling pathway', the 'Ras signaling pathway', 'prostate cancer', and the 'FoxO signaling pathway'. Kaplan‑Meier survival analysis revealed that six DElncRNAs (INC AC112721.1, LINC00536, MIR7‑3HG, ADAMTS9‑AS1, AL356479.1 and LINC00466), nine DEmRNAs (KPNA2, RACGAP1, SHCBP1, ZNF367, NTRK2, ORS1, PTGS2, RASGRP1 and SFRP1) and two DEmiRNAs (hsa‑miR‑301b and hsa‑miR‑204) had significant effects on overall survival in BC. The present results demonstrated the aberrant expression of INC AC112721.1, AL356479.1, LINC00466 and MIR7‑3HG in BC, indicating their potential prognostic role in patients with BC.

Increased MDR1 Transporter Expression in Human Brain Endothelial Cells Through Enhanced Histone Acetylation and Activation of Aryl Hydrocarbon Receptor Signaling

Multidrug resistance protein 1 (MDR1, ABCB1, P-glycoprotein) is a critical efflux transporter that extrudes chemicals from the blood-brain barrier (BBB) and limits neuronal exposure to xenobiotics. Prior studies in malignant cells demonstrated that MDR1 expression can be altered by inhibition of histone deacetylases (HDAC), enzymes that modify histone structure and influence transcription factor binding to DNA. Here, we sought to identify the mechanisms responsible for the up-regulation of MDR1 by HDAC inhibitors in human BBB cells. Immortalized human brain capillary endothelial (hCMEC/D3) cells were treated with HDAC inhibitors and assessed for MDR1 expression and function. Of the HDAC inhibitors profiled, valproic acid (VPA), apicidin, and suberoylanilide hydroxamic acid (SAHA) increased MDR1 mRNA and protein levels by 30-200%, which corresponded with reduced intracellular accumulation of the MDR1 substrate rhodamine 123. Interestingly, induction of MDR1 mRNA by HDAC inhibitors mirrored increases in the expression of the aryl hydrocarbon receptor (AHR) and its target gene cytochrome P450 1A1. To explore the role of AHR in HDAC inhibitor-mediated regulation of MDR1, a pharmacological activator (β-naphthoflavone, βNF) and inhibitor (CH-223191, CH) of AHR were tested. The induction of MDR1 in cells treated with SAHA was amplified by βNF and attenuated by CH. Furthermore, SAHA increased the binding of acetylated histone H3K9/K14 and AHR proteins to regions of the MDR1 promoter that contain AHR response elements. In conclusion, HDAC inhibitors up-regulate the expression and activity of the MDR1 transporter in human brain endothelial cells by increasing histone acetylation and facilitating AHR binding at the MDR1 promoter.

miR-204-5p promotes diabetic retinopathy development via downregulation of microtubule-associated protein 1 light chain 3

Diabetic retinopathy (DR) is a chronic and progressive complication of diabetes mellitus. DR impairs sight due to neuronal and vascular dysfunction in the retina. It is critical to investigate the pathogenesis of DR to develop effective treatment. In the present study, a streptozotocin (STZ)-induced diabetic rat model was constructed and the expression of microRNA (miR)-204-5p and vascular endothelial growth factor (VEGF) were determined. Immunohistochemistry, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were employed to detect the effects of miR-204-5p on the expression of microtubule-associated protein 1 light chain 3 (LC3B). RT-qPCR analysis demonstrated that miR-204-5p and VEGF were significantly upregulated in the retina tissue of diabetic rats compared with the control group (P<0.01). Immunohistochemistry and western blotting revealed that the protein expression levels of LC3B-II and the ratio of LC3B-II/LC3B-I were significantly suppressed in the diabetes group compared with the control (P<0.01). In retinal tissues, anti-miR-204-5p treatment significantly enhanced the protein expression levels of LC3B-II and the ratio of LC3B-II/LC3B-I and these levels were significantly reduced in response to miR-204-5p mimic treatment compared with the negative miR control (P<0.01). In rat retinal endothelial cells isolated from diabetic rats, anti-miR-204-5p treatment increased the number of autophagic vacuoles, and significantly promoted LC3B-II expression and the LC3B-II/LC3B-I ratio compared with the negative control (P<0.01). The results of the present study revealed that miR-204-5p downregulated the expression of LC3B-II to inhibit autophagy in DR. Therefore, miR-204-5p may be considered as a novel effective therapeutic target during the development of DR.

DSCAM-AS1 promotes tumor growth of breast cancer by reducing miR-204-5p and up-regulating RRM2

Breast cancer (BC) is a common malignancy worldwide. More than 3 700 000 women die of BC every year. DSCAM-AS1 was overexpressed several kinds of cancer and miR-204-5p was lowly expressed, which indicated that miR-204-5p had anti-tumor activity and DSCAM-AS1 had pro-tumor activity. We intended to analyze DSCAM-AS1, miR-204-5p, and ribonucleotide reductase M2 (RRM2). Microarray analysis and quantitative Real Time fluorescence Polymerase Chain Reaction (qRT-PCR) were employed to determine DSCAM-AS1 and miR-204-5p expression. Luciferase reporter assay was applied to examine the target relationship between DSCAM-AS1, miR-204-5p, and RRM2. Cell Counting Kit-8 (CCK-8 assay), transwell assay, and flow cytometry were used to detect cell proliferation, invasion, and apoptosis. The expression of DSCAM-AS1, miR-204-5p, and RRM2 were confirmed by Western blot. We also conducted in vivo assay to verify the effect of DSCAM-AS1. DSCAM-AS1 was up-regulated, while miR-204-5p was down-regulated in BC tissues and cells. DSCAM-AS1 directly targeted miR-204-5p. DSCAM-AS1 promoted the proliferation and invasion of BC cells by reducing miR-204-5p and inhibiting miR-204-5p expression. DSCAM-AS1 expression was related to the expression of RRM2, and miR-204-5p could reverse the function of DSCAM-AS1. RRM2 was up-regulated in BC cells, and miR-204-5p inhibited RRM2 expression by targeting RRM2. Overexpression of RRM2 stimulated proliferation and cell invasion and impeded apoptosis. In vivo experiments showed that knockdown of DSCAM-AS1 decreased the tumorigenesis of BC cells, increased the expression of miR-204-5p. DSCAM-AS1 promoted proliferation and impaired apoptosis of BC cells by reducing miR-204-5p and enhancing RRM2 expression. DSCAM-AS1/miR-204-5p/RRM2 may serve as novel therapeutic targets for BC.

Expression and potential molecular mechanisms of miR‑204‑5p in breast cancer, based on bioinformatics and a meta‑analysis of 2,306 cases

Breast cancer (BC) is the most common cancer among women worldwide. However, there is insufficient research that focuses on the expression and molecular mechanisms of microRNA (miR)‑204‑5p in BC. In the current study, data were downloaded from the Cancer Genome Atlas (TCGA), the Gene Expression Omnibus (GEO) and the University of California Santa Cruz (UCSC) Xena databases. They were then used to undertake a meta‑analysis that leveraged the standard mean difference (SMD) and summarized receiver operating characteristic (sROC) to evaluate the expression of the precursor miR‑204 and mature miR‑204‑5p in BC. Additionally, an intersection of predicted genes, differentially expressed genes (DEGs) from the TCGA database and the GEO database were plotted to acquire desirable putative genes. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and protein‑protein interaction (PPI) network analyses were performed to assess the potential pathways and hub genes of miR‑204‑5p in BC. A decreased trend in precursor miR‑204 expression was detected in 1,077 BC tissue samples in comparison to 104 para‑carcinoma tissue samples in the TCGA database. Further, the expression of mature miR‑204‑5p was markedly downregulated in 756 BC tissue samples in comparison to 76 para‑carcinoma tissue samples in the UCSC Xena database. The outcome of the SMD from meta‑analysis also indicated that the expression of miR‑204‑5p was markedly reduced in 2,306 BC tissue samples in comparison to 367 para‑carcinoma tissue samples. Additionally, the ROC and sROC values indicated that miR‑204‑5p had a great discriminatory capacity for BC. In GO analysis, 'cell development', 'cell surface activity', and 'receptor agonist activity' were the most enriched terms; in KEGG analysis, 'endocytosis' was significantly enriched. Rac GTPase activating protein 1 (RACGAP1) was considered the hub gene in the PPI network. In conclusion, miR‑204‑5p may serve a suppressor role in the oncogenesis and advancement of BC, and miR‑204‑5p may have crucial functions in BC by targeting RACGAP1.

Trichostatin A induces p53-dependent endoplasmic reticulum stress in human colon cancer cells

Trichostatin A (TSA) has been demonstrated to exhibit various anticancer effects that influence cell cycle arrest, cell proliferation and apoptosis of cancer cells. A potential association between TSA and endoplasmic reticulum (ER) function has been suggested but its anticancer mechanism involving the induction of ER stress is unknown. p53 has previously been demonstrated to regulate ER function in response to stress but its role involving TSA and ER stress in cancer cells is poorly understood. The current study identified that TSA induced ER stress in wild type (WT) HCT116 human colon cancer cells. Following TSA treatment, the ER stress markers GRP78 and GRP94 significantly increased without hyperacetylation of their promoter regions. The inositol-requiring enzyme 1 α (IRE1α)/X-box binding protein 1 (XBP1) pathway was implicated due to an association of phosphorylated IRE1α and spliced XBP1 with ER stress. However, luciferase reporter assay indicated that splicing events were attenuated in HCT116 TP53(-/-) cells. Furthermore, cell viability and apoptosis were revealed to depend on p53 during TSA treatment. Cell viability increased and the apoptosis rate decreased in HCT116 TP53(-/-) cells compared with WT HCT116 cells undergoing TSA treatment. In conclusion, the current study revealed that TSA may induce ER stress via a p53-dependent mechanism in colon cancer cells. This provides information that may assist the development of treatments that exploit the anticancer function of TSA.

Oxibendazole inhibits prostate cancer cell growth

Prostate cancer (PCa) is one of the most common malignancies among men and is the second leading cause of cancer-associated mortality in the developed world. Androgen deprivation therapy (ADT) is the most common treatment for PCa. However, the majority of androgen-sensitive PCa patients will eventually develop resistance to ADT and the disease will become androgen-independent. There is, therefore, an immediate requirement to develop effective therapeutic techniques towards the treatment of recurrent PCa. Oxibendazole (OBZ) is an anthelmintic drug that has also shown promise in the treatment of malignancies. In the present study, the capability of OBZ to repress the growth of PCa cells was assessed in human androgen-independent PCa 22Rv1 and PC-3 cell lines. The growth of the 22Rv1 and PC-3 cell lines, as assessed with a trypan blue exclusion assay, was markedly inhibited by OBZ treatment in vitro, with half-maximal inhibitory concentration values of 0.25 and 0.64 µM, respectively. The mean size of 22Rv1 tumors in nude mice treated with OBZ (25 mg/kg/day) was 47.96% smaller than that of the control mice. Treatment with OBZ increased the expression of microRNA-204 (miR-204), as determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and the level of p53 as determined with western blotting, two well-characterized tumor suppressor genes. When miR-204 expression was knocked down by introduction of an miR-204 inhibitor, the inhibitory effect of OBZ was markedly reduced; however, when it was overexpressed, the inhibitory efficiency of OBZ was markedly higher, indicating that upregulation of miR-204 is key for the efficacy of OBZ. Additionally, OBZ was demonstrated with RT-qPCR to repress the expression of the androgen receptor, and by western blotting to reduce prostate-specific androgen in 22Rv1 cells. The results suggest that OBZ has potential for clinical use in the treatment of recurrent PCa.

TGF-β1 regulating miR-205/miR-195 expression affects the TGF-β signal pathway by respectively targeting SMAD2/SMAD7

Transforming growth factor-β (TGF-β) proteins are important cytokines in the occurrence and development of tumors. However, its neural functions in glioma are still not understood. In the present study, we evaluated the effects of TGF-β1 on glioma cell line U87. miR-205 and miR-195 were involved in TGF-β1 signaling pathway. Quantitative real-time PCR was used to detect miR-205 and miR-195 levels in human glioma tissue samples and U87 cells treated with different concentrations of TGF-β1. Enzyme-linked immunosorbent assay (ELISA) was performed to determine TGF-β1 in the glioma patients peripheral blood. In vitro, U87 cells were transfected with mimics or inhibitors of miR-205 and miR-195. SMAD proteins were assayed by western blotting. Luciferase assay and co-immunoprecipitation (Co-IP)were used to determine the relationships between miR-205 and SMAD2, miR-195 and SMAD7. Effects of miR-205 and miR-195 on glioma cell proliferation and invasion using colony forming and cell migration assays. It was shown that miR-205 was decreased in glioma tissue, but miR-195 and TGF-β1 was increased. In addition, TGF-β1 concentration was negatively correlated with miR-205 mRNA level, but positively correlated with miR-195 mRNA. In addition, miR-205 was downregulated and miR-195 was upregulated by TGF-β1 in a dose-dependent manner. miR-205 and miR-195 targeted and inhibited SMAD2 and SMAD7 expression, respectively, in U87. High expression of miR-205 but not miR-195 reduced SMAD2 and SMAD4 heteromer formation. In addition, it was also shown that miR-205 overexpression inhibited U87 proliferation and invasion efficiently. All the results suggested that miR-205 and miR-195 participated in the TGF-β1 signaling pathway and showed opposite effects in glioma. These findings contribute to the understanding of TGF-β1 function in glioma.

PU.1-Bim axis is involved in Trichostatin A-induced apoptosis in murine pro-B lymphoma FL5.12 cells

Trichostatin A (TSA) is a well-known histone deacetylases (HDACs) inhibitor that has been reported to show potent anti-tumor capabilities in some types of cancer cell lines. However, detailed mechanism of TSA action on lymphoma remains to be described. In the present study, anti-proliferative effects of TSA were investigated using a murine pro-B lymphoma cell line FL5.12. MTT assay revealed that TSA potently inhibited the proliferation of FL5.12 cells in a time- and dose-dependent manner. Bright-field microscopy of FL5.12 cells showed apoptotic morphology at 24 h after TSA treatment. Consistently, TSA treatment led to DNA fragmentation and increased the protein levels of cleaved caspase 3 and PARP as revealed by western blot analysis. To explore the underlying mechanism of TSA-induced apoptosis of FL5.12 cells, we further analyzed the hematopoietic transcription factor Purine Rich Box-1 (PU.1) by western blot analysis. TSA treatment resulted in the inhibition of PU.1 in FL5.12 cells. In contrast, apoptotic protein Bim was induced by TSA, which was inversely correlated with the survival of FL5.12 cells. These results suggest the possible mechanism of TSA-induced apoptosis in murine pro-B lymphoma FL5.12 cells via the PU.1-Bim axis.

The dual regulatory role of miR-204 in cancer

MicroRNAs (miRNAs) are a group of endogenous, small (about 22 nucleotides) non-coding RNAs which negatively regulate gene expressions. As one of them, miR-204 originates from the sixth intron of the transient receptor potential melastatin 3 (TRPM3) gene. Therefore, expression of miR-204 is under the control of the TRPM3 promoter and regulated by genetic and epigenetic mechanisms. miR-204 has been found to play the important roles in development of eyes and adipogenesis. Its pathological functions have been observed in a few diseases including pulmonary arterial hypertension, diabetes, and various types of cancers. It is believed that miR-204 acts as a tumor-suppressor via promoting apoptosis, conferring the resistance of cancer cells to chemotherapy, and suppressing the self-renewal of cancer stem cells (CSCs) and the epithelial to mesenchymal transition (EMT). Expression of miR-204 is repressed by its targets XRN1 and TRKB in prostate cancer and endometrial carcinoma, respectively; therefore, they establish an oncogenic feedback loops that play an important role promoting development of cancer. In this review, we summarize our current knowledge regarding miR-204, including its expression, regulation and biological functions, especially focusing our discussion on its role in tumor development and tumor progression.

Trichostatin A enhances estrogen receptor-alpha repression in MCF-7 breast cancer cells under hypoxia

Estrogen receptor (ER) is a crucial determinant of resistance to endocrine therapy, which may change during the progression of breast cancer. We previously showed that hypoxia induces ESR1 gene repression and ERα protein degradation via proteasome-mediated pathway in breast cancer cells. HDAC plays important roles in the regulation of histone and non-histone protein post-translational modification. HDAC inhibitors can induce epigenetic changes and have therapeutic potential for targeting various cancers. Trichostatin A exerts potent antitumor activities against breast cancer cells in vitro and in vivo. In this report, we show that TSA augments ESR1 gene repression at the transcriptional level and downregulates ERα protein expression under hypoxic conditions through a proteasome-mediated pathway. TSA-induced estrogen response element-driven reporter activity in the absence of estrogen was synergistically enhanced under hypoxia; however, TSA inhibited cell proliferation under both normoxia and hypoxia. Our data show that the hypoxia-induced repression of ESR1 and degradation of ERα are enhanced by concomitant treatment with TSA. These findings expand our understanding of hormone responsiveness in the tumor microenvironment; however, additional in-depth studies are required to elucidate the detailed mechanisms of TSA-induced ERα regulation under hypoxia.