Significance of PELP1/HDAC2/miR-200 regulatory network in EMT and metastasis of breast cancer

PELP1 Is a Novel Therapeutic Target in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths in the United States, with a median survival period of approximately 10 months. There is an urgent need for the development of effective targeted therapies for the treatment of HCC. Proline-, glutamic acid-, and leucine-rich protein 1 (PELP1) signaling is implicated in the progression of many cancers, although its specific contribution to the progression of HCC is not yet well understood. Analysis of The Cancer Genome Atlas HCC gene expression data sets and IHC analysis of HCC tissue microarray revealed that HCC tumors had elevated expression of PELP1 compared with normal tissues, and high expression of PELP1 is associated with unfavorable survival outcomes. Suppression of PELP1 expression using short hairpin RNA significantly reduced the cell viability, clonogenicity, and invasion of HCC cells. Importantly, SMIP34, a first-in-class small-molecule inhibitor targeting PELP1, effectively decreased the cell viability, clonogenic survival, and invasiveness of HCC cells. Gene expression analysis using RNA sequencing revealed that PELP1 knockdown cells exhibited a decrease in c-Myc, E2F, and other oncogenic pathways related to HCC. Mechanistic studies showed that SMIP34 treatment impaired the Rix complex, a critical component of ribosomal biogenesis, in HCC cells. Furthermore, the knockdown or pharmacologic inhibition of PELP1 significantly decelerated the HCC tumor growth in xenograft models. In summary, our study findings indicate that PELP1 could serve as a promising target for therapeutic intervention in HCC.

SIGNIFICANCE

HCC is one of the leading causes of cancer fatalities in the United States. Effective targeted therapeutics for HCC are urgently needed. In this study, we show that PELP1 proto-oncogene is crucial to HCC progression and that PELP1 inhibition reduced HCC cell proliferation in vitro and in vivo. Our results imply that PELP1-targeted drugs like SMIP34 may be useful as new therapeutic agents for HCC treatment.

PELP1 inhibition by SMIP34 reduces endometrial cancer progression via attenuation of ribosomal biogenesis

Endometrial carcinoma (ECa) is the fourth most common cancer among women. The oncogene PELP1 is frequently overexpressed in a variety of cancers, including ECa. We recently generated SMIP34, a small-molecule inhibitor of PELP1 that suppresses PELP1 oncogenic signaling. In this study, we assessed the effectiveness of SMIP34 in treating ECa. Treatment of established and primary patient-derived ECa cells with SMIP34 resulted in a significant reduction of cell viability, colony formation ability, and induction of apoptosis. RNA-seq analyses showed that SMIP34-regulated genes were negatively correlated with ribosome biogenesis and eukaryotic translation pathways. Mechanistic studies showed that the Rix complex, which is essential for ribosomal biogenesis, is disrupted upon SMIP34 binding to PELP1. Biochemical assays confirmed that SMIP34 reduced ribosomal biogenesis and new protein synthesis. Further, SMIP34 enhanced the efficacy of mTOR inhibitors in reducing viability of ECa cells. SMIP34 is also effective in reducing cell viability in ECa organoids in vitro and explants ex vivo. Importantly, SMIP34 treatment resulted in a significant reduction of the growth of ECa xenografts. Collectively, these findings underscore the potential of SMIP34 in treating ECa.

An update on existing therapeutic options and status of novel anti-metastatic agents in breast cancer: Elucidating the molecular mechanisms underlying the pleiotropic action of Withania somnifera (Indian ginseng) in breast cancer attenuation

Major significant advancements in pharmacology and drug technology have been made to heighten the impact of cancer therapies, improving the life expectancy of subjects diagnosed with malignancy. Statistically, 99% of breast cancers occur in women while 0.5-1% occur in men, the female gender being the strongest breast cancer risk factor. Despite several breakthroughs, breast cancer continues to have a worldwide impact and is one of the leading causes of mortality. Additionally, resistance to therapy is a crucial factor enabling cancer cell persistence and resurgence. As a result, the search and discovery of novel modulatory agents and effective therapies capable of controlling tumor progression and cancer cell proliferation is critical. Withania somnifera (L.) Dunal (WS), commonly known as Indian ginseng, has long been used traditionally for the treatment of several ailments in the Indian context. Recently, WS and its phytoconstituents have shown promising anti-breast cancer properties and, as such, can be employed as prophylactic as well as therapeutic adjuncts to the main line of breast cancer treatment. The present review is an attempt to explore and provide experimental evidences in support of the prophylactic and therapeutic potential of WS in breast cancer, along with a deeper insight into the multiple molecular mechanisms and novel targets through which it acts against breast and other hormonally-induced cancers viz. ovarian, uterine and cervical. This exploration might prove crucial in providing better understanding of breast cancer progression and metastasis and its use as an adjunct in improving disease prognosis and therapeutic outcome.

Short-chain fatty acids abrogate Japanese encephalitis virus-induced inflammation in microglial cells via miR-200a-3p/ZBTB20/IKβα axis

Japanese encephalitis virus (JEV), a member of the Flaviviridae family, is a leading cause of viral encephalitis in humans. Survivors of this infection often develop lifelong neurological sequelae. Short-chain fatty acids (SCFAs) produced in the gut are vital mediators of the gut-brain axis. We aimed to study microRNA-based mechanisms of SCFAs in an in vitro model of JEV infection. N9 microglial cells were pretreated with SCFA cocktail before JEV infection. Cytokine bead analysis, immunoblotting, and PCR were performed to analyze relevant inflammatory markers. microRNA sequencing was performed using Illumina Hiseq, and bioinformatics tools were used for differentially expressed (DE) miRNAs and weighted gene co-expression network analysis (WGCNA). microRNA mimic/inhibitor experiments and luciferase assay were performed to study miRNA-target interaction. A significant reduction in monocyte chemoattractant protein (MCP1) and tumor necrosis factor alpha (TNFα) along with reduced expression of phospho-nuclear factor kappa B (phospho-NF-κB) was observed in SCFA conditions. Significant attenuation of histone deacetylase activity and protein expression was recorded. miRNA sequencing revealed 160 DE miRNAs in SCFA + JEV-treated cells at 6 h post-infection. WGCNA revealed miR-200a-3p, a hub miRNA significantly upregulated in SCFA conditions. Transcription factor ZBTB20 was bioinformatically predicted and validated as a gene target for miR-200a-3p. Further miRNA mimic/inhibitor assay demonstrated that miR-200-3p regulated ZBTB20 along with Iκβα that possibly dampened NF-κB signal activation downstream.

IMPORTANCE

The gut-brain axis plays a pivotal role in the physiological state of an organism. Gut microbiota-derived metabolites are known to play a role in brain disorders including neuroviral infections. Short-chain fatty acids (SCFAs) appear to quench inflammatory markers in Japanese encephalitis virus-infected microglial cells in vitro. Mechanistically, we demonstrate the interaction between miR-200a-3p and ZBTB20 in regulating the canonical nuclear factor kappa B (NF-κB) signaling pathway via transcriptional regulation of Iκβα. Findings of this study pave the way to a better understanding of SCFA mechanisms that can be used to develop strategies against viral neuroinflammation.

Searching for Essential Genes and Targeted Drugs Common to Breast Cancer and Osteoarthritis

BACKGROUND

It is documented that osteoarthritis can promote the progression of breast cancer (BC).

OBJECTIVE

This study aims to search for the essential genes associated with breast cancer (BC) and osteoarthritis (OA), explore the relationship between epithelial-mesenchymal transition (EMT)- related genes and the two diseases, and identify the candidate drugs.

METHODS

The genes related to both BC and OA were determined by text mining. Protein-protein Interaction (PPI) analysis was carried out, and as a result, the exported genes were found to be related to EMT. PPI and the correlation of mRNA of these genes were also analyzed. Different kinds of enrichment analyses were performed on these genes. A prognostic analysis was performed on these genes for examining their expression levels at different pathological stages, in different tissues, and in different immune cells. Drug-gene interaction database was employed for potential drug discovery.

RESULTS

A total number of 1422 genes were identified as common to BC and OA and 58 genes were found to be related to EMT. We found that HDAC2 and TGFBR1 were significantly poor in overall survival. High expression of HDAC2 plays a vital role in the increase of pathological stages. Four immune cells might play a role in this process. Fifty-seven drugs were identified that could potentially have therapeutic effects.

CONCLUSION

EMT may be one of the mechanisms by which OA affects BC. Using the drugs can have potential therapeutic effects, which may benefit patients with both diseases and broaden the indications for drug use.

Interactions between circRNAs and miR-141 in Cancer: From Pathogenesis to Diagnosis and Therapy

The function of non-coding RNAs (ncRNAs) in the pathogenesis and development of cancer is indisputable. Molecular mechanisms underlying carcinogenesis involve the aberrant expression of ncRNAs, including circular RNAs (circRNAs), and microRNAs (miRNAs). CircRNAs are a class of single-stranded, covalently closed RNAs responsible for maintaining cellular homeostasis through their diverse functions. As a part of the competing endogenous RNA (ceRNAs) network, they play a central role in the regulation of accessibility of miRNAs to their mRNA targets. The interplay between these molecular players is based on the primary role of circRNAs that act as miRNAs sponges, and the circRNA/miRNA imbalance plays a central role in different pathologies including cancer. Herein, we present the latest state of knowledge about interactions between circRNAs and miR-141, a well-known member of the miR-200 family, in malignant transformation, with emphasis on the biological role of circRNA/miR-141/mRNA networks as a future target for novel anti-cancer therapies.

Targeting PELP1 oncogenic signaling in TNBC with the small molecule inhibitor SMIP34

PURPOSE

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. Oncogenic PELP1 is frequently overexpressed in TNBC, and it has been demonstrated that PELP1 signaling is essential for TNBC progression. The therapeutic utility of targeting PELP1 in TNBC, however, remains unknown. In this study, we investigated the effectiveness of SMIP34, a recently developed PELP1 inhibitor for the treatment of TNBC.

METHODS

To ascertain the impact of SMIP34 treatment, we used seven different TNBC models for testing cell viability, colony formation, invasion, apoptosis, and cell cycle analysis. Western blotting and RT-qPCR were used to determine the mechanistic insights of SMIP34 action. Using xenograft and PDX tumors, the ability of SMIP34 in suppressing proliferation was examined both ex vivo and in vivo.

RESULTS

TNBC cells' viability, colony formation, and invasiveness were all decreased by SMIP34 in in vitro cell-based assays, while apoptosis was increased. SMIP34 treatment promoted the degradation of PELP1 through the proteasome pathway. RT-qPCR analyses confirmed that SMIP34 treatment downregulated PELP1 target genes. Further, SMIP34 treatment substantially downregulated PELP1 mediated extranuclear signaling including ERK, mTOR, S6 and 4EBP1. Mechanistic studies confirmed downregulation of PELP1 mediated ribosomal biogenesis functions including downregulation of cMyc and Rix complex proteins LAS1L, TEX-10, and SENP3. The proliferation of TNBC tumor tissues was decreased in explant experiments by SMIP34. Additionally, SMIP34 treatment markedly decreased tumor progression in both TNBC xenograft and PDX models.

CONCLUSIONS

Together, these findings from in vitro, ex vivo, and in vivo models show that SMIP34 may be a useful therapeutic agent for inhibiting PELP1 signaling in TNBC.

NONHSAT021545/miR-330-3p/EREG: A Cooperative Axis in Breast Cancer Prognosis and Treatment

Lymphatic metastasis is the most common form in breast cancer (BC) progression. Previously, we observed that lnc045874, a most conservative homology of Homo Sapiens NONHSAT021545 (lnc021545), miR-330-3p, and EREG may have some effects in mouse hepatocarcinoma cell lines with different lymphatic metastasis potentials. Through data from TCGA and GEO database analysis, we speculated that miR-330-3p might be a tumor promoter, while EREG could be a tumor suppressor in BC. MiR-330-3p was upregulated, while lnc021545 and EREG were downregulated in 50 BC tissues. MiR-330-3p advanced the metastatic behaviors of BC cells, whereas lnc021545 and EREG resulted in the opposite effects. The three molecules' expressions were correlated respectively and showed that miR-330-3p targeted lnc021545 and EREG to affect their expressions. Lnc021545/miR-330-3p axis affected BC metastasis by regulating EREG in epithelial-to-mesenchymal transition. In 50 BC patients, these three molecules and their cooperation are associated with aggressive tumor phenotypes, patient outcomes, and trastuzumab therapy. We finally discovered that lnc021545, miR-330-3p, and EREG formed a multi-gene co-regulation system that affected the metastasis of BC and the cooperation reflects the synergistic effects of the three molecules, recommending that their cooperation may provide a more accurate index for anti-metastasis therapeutic and prognostic evaluation of BC.

HDAC2 as a Target for developing Anti-cancer Drugs

Histone deacetylases (HDACs) deacetylate histones H3 and H4. An imbalance between histone acetylation and deacetylation can lead to various diseases. HDAC2 is present in the nucleus. It plays a critical role in modifying chromatin structures and regulates the expression of various genes by functioning as a transcriptional regulator. The roles of HDAC2 in tumorigenesis and anti-cancer drug resistance are discussed in this review. Several reports suggested that HDAC2 is a prognostic marker of various cancers. The roles of microRNAs (miRNAs) that directly regulate the expression of HDAC2 in tumorigenesis are also discussed in this review. This review also presents HDAC2 as a valuable target for developing anti-cancer drugs.

High-Throughput Cellular Heterogeneity Analysis in Cell Migration at the Single-Cell Level

Cancer cell migration represents an essential step toward metastasis and cancer deaths. However, conventional drug discovery focuses on cytotoxic and growth-inhibiting compounds rather than inhibitors of migration. Drug screening assays generally measure the average response of many cells, masking distinct cell populations that drive metastasis and resist treatments. Here, this work presents a high-throughput microfluidic cell migration platform that coordinates robotic liquid handling and computer vision for rapidly quantifying individual cellular motility. Using this innovative technology, 172 compounds were tested and a surprisingly low correlation between migration and growth inhibition was found. Notably, many compounds were found to inhibit migration of most cells while leaving fast-moving subpopulations unaffected. This work further pinpoints synergistic drug combinations, including Bortezomib and Danirixin, to stop fast-moving cells. To explain the observed cell behaviors, single-cell morphological and molecular analysis were performed. These studies establish a novel technology to identify promising migration inhibitors for cancer treatment and relevant applications.

AR-regulated ZIC5 contributes to the aggressiveness of prostate cancer

The mechanisms by which prostate cancer (PCa) progresses to the aggressive castration-resistant stage remain uncertain. Zinc finger of the cerebellum 5 (ZIC5), a transcription factor belonging to the ZIC family, is involved in the pathology of various cancers. However, the potential effect of ZIC5 on PCa malignant progression has not been fully defined. Here, we show that ZIC5 is upregulated in PCa, particularly in metastatic lesions, in positive association with poor prognosis. Genetic inhibition of ZIC5 in PCa cells obviously attenuated invasion and metastasis and blunted the oncogenic properties of colony formation. Mechanistically, ZIC5 functioned as a transcription factor to promote TWIST1-mediated EMT progression or as a cofactor to strengthen the β-catenin-TCF4 association and stimulate Wnt/β-catenin signaling. Importantly, ZIC5 and the androgen receptor (AR) form a positive feed-forward loop to mutually stimulate each other’s expression. AR, in cooperation with its steroid receptor coactivator 3 (SRC-3), increased ZIC5 expression through binding to the miR-27b-3p promoter and repressing miR-27b-3p transcription. In turn, ZIC5 potentiated AR, AR-V7, and AR targets’ expression. Besides, ZIC5 inhibition reduced AR and AR-V7 protein expression and enhanced the sensitivity of PCa to enzalutamide (Enz) treatment, both in vitro and in vivo. These findings indicate that the reciprocal activation between AR and ZIC5 promotes metastasis and Enz resistance of PCa and suggest the therapeutic value of cotargeting ZIC5 and AR for the treatment of advanced PCa.

Epigenetics and environment in breast cancer: New paradigms for anti-cancer therapies

Breast cancer remains the most frequently diagnosed cancer in women worldwide. Delayed presentation of the disease, late stage at diagnosis, limited therapeutic options, metastasis, and relapse are the major factors contributing to breast cancer mortality. The development and progression of breast cancer is a complex and multi-step process that incorporates an accumulation of several genetic and epigenetic alterations. External environmental factors and internal cellular microenvironmental cues influence the occurrence of these alterations that drives tumorigenesis. Here, we discuss state-of-the-art information on the epigenetics of breast cancer and how environmental risk factors orchestrate major epigenetic events, emphasizing the necessity for a multidisciplinary approach toward a better understanding of the gene-environment interactions implicated in breast cancer. Since epigenetic modifications are reversible and are susceptible to extrinsic and intrinsic stimuli, they offer potential avenues that can be targeted for designing robust breast cancer therapies.

Global alteration of colonic microRNAome landscape associated with inflammatory bowel disease

Inflammatory Bowel Disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract that associates with, among others, increased risk of colorectal cancer. There is a growing evidence that miRNAs have important roles in pathological processes, such as inflammation or carcinogenesis. Understanding the molecular mechanisms such as alterations in microRNAome upon chronic intestinal inflammation is critical for understanding the exact pathomechanism of IBD. Hence, we conducted a genome wide microRNAome analysis by applying miRNA-Seq in a rat model of experimental colitis, validated the data by QPCR, examined the expression of a selection of precursor and mature miRNAs, performed in depth biological interpretation using Ingenuity Pathway Analysis and tested the obtained results on samples derived from human patients. We identified specific, interdependent expression pattern of activator/repressor transcription factors, miRNAs and their direct targets in the inflamed colon samples. Particularly, decreased expression of the miR-200 family members (miR-200a/b/c,-141, and -429) and miR-27b correlates with the reduced level of their enhancers (HNF1B, E2F1), elevated expression of their repressors (ZEB2, NFKB1) and increased expression of their target genes (ZEB2, RUNX1). Moreover, the marked upregulation of six miR-27b target genes (IFI16, GCA, CYP1B1, RUNX1, MEF2C and MMP13) in the inflamed colon tissues is a possible direct consequence of the lack of repression due to the downregulated miRNA-27b expression. Our data indicate that changes in microRNAome are associated with the pathophysiology of IBD, consequently, microRNAs offer potential targets for the diagnosis, prognosis and treatment of IBD.

Differential molecular mechanistic behavior of HDACs in cancer progression

Genetic aberration including mutation in oncogenes and tumor suppressor genes transforms normal cells into tumor cells. Epigenetic modifications work concertedly with genetic factors in controlling cancer development. Histone acetyltransferases (HATs), histone deacetylases (HDACs), DNA methyltransferases (DNMTs) and chromatin structure modifier are prospective epigenetic regulators. Specifically, HDACs are histone modifiers regulating the expression of genes implicated in cell survival, growth, apoptosis, and metabolism. The majority of HDACs are highly upregulated in cancer, whereas some have a varied function and expression in cancer progression. Distinct HDACs have a positive and negative role in controlling cancer progression. HDACs are also significantly involved in tumor cells acquiring metastatic and angiogenic potential in order to withstand the anti-tumor microenvironment. HDACs' role in modulating metabolic genes has also been associated with tumor development and survival. This review highlights and discusses the molecular mechanisms of HDACs by which they regulate cell survival, apoptosis, metastasis, invasion, stemness potential, angiogenesis, and epithelial to mesenchymal transitions (EMT) in tumor cells. HDACs are the potential target for anti-cancer drug development and various inhibitors have been developed and FDA approved for a variety of cancers. The primary HDAC inhibitors with proven anti-cancer efficacy have also been highlighted in this review.

Metabolomics and EMT Markers of Breast Cancer: A Crosstalk and Future Perspective

Cancer cells undergo transient EMT and MET phenomena or vice versa, along with the parallel interplay of various markers, often correlated as the determining factor in decoding metabolic profiling of breast cancers. Moreover, various cancer signaling pathways and metabolic changes occurring in breast cancer cells modulate the expression of such markers to varying extents. The existing research completed so far considers the expression of such markers as determinants regulating the invasiveness and survival of breast cancer cells. Therefore, this manuscript is crosstalk among the expression levels of such markers and their correlation in regulating the aggressiveness and invasiveness of breast cancer. We also attempted to cover the possible EMT-based metabolic targets to retard migration and invasion of breast cancer.

Potential of the miR-200 Family as a Target for Developing Anti-Cancer Therapeutics

MicroRNAs (miRNAs) are small non-coding RNAs (18–24 nucleotides) that play significant roles in cell proliferation, development, invasion, cancer development, cancer progression, and anti-cancer drug resistance. miRNAs target multiple genes and play diverse roles. miRNAs can bind to the 3′UTR of target genes and inhibit translation or promote the degradation of target genes. miR-200 family miRNAs mostly act as tumor suppressors and are commonly decreased in cancer. The miR-200 family has been reported as a valuable diagnostic and prognostic marker. This review discusses the clinical value of the miR-200 family, focusing on the role of the miR-200 family in the development of cancer and anti-cancer drug resistance. This review also provides an overview of the factors that regulate the expression of the miR-200 family, targets of miR-200 family miRNAs, and the mechanism of anti-cancer drug resistance regulated by the miR-200 family.

Identification of potent HDAC 2 inhibitors using E-pharmacophore modelling, structure-based virtual screening and molecular dynamic simulation

Histone deacetylase 2 (HDAC 2) of class I HDACs plays a major role in embryonic and neural developments. However, HDAC 2 overexpression triggers cell proliferation by diverse mechanisms in cancer. Over the decades, many pan and class-specific inhibitors of HDAC were discovered. Limitations such as toxicity and differential cell localization of each isoform led researchers to hypothesize that isoform selective inhibitors may be relevant to bring about desired effects. In this study, we have employed the PHASE module to develop an e-pharmacophore model and virtually screened four focused libraries of around 300,000 compounds to identify isoform selective HDAC 2 inhibitors. The compounds with phase fitness score greater than or equal to 2.4 were subjected to structure-based virtual screening with HDAC 2. Ten molecules with docking score greater than  -12 kcal/mol were chosen for selectivity study, QikProp module (ADME prediction) and dG/bind energy identification. Compound 1A with the best dock score of  -13.3 kcal/mol and compound 1I with highest free binding energy,  -70.93 kcal/mol, were selected for molecular dynamic simulation studies (40 ns simulation). The results indicated that compound 1I may be a potent and selective HDAC 2 inhibitor. Further, in vitro and in vivo studies are necessary to validate the potency of selected lead molecule and its derivatives.

Identification of Key Transcription Factors and Immune Infiltration Patterns Associated With Breast Cancer Prognosis Using WGCNA and Cox Regression Analysis

Breast cancer is the most frequently diagnosed cancer and the second leading cause of cancer death among women worldwide. Therefore, the need for effective breast cancer treatment is urgent. Transcription factors (TFs) directly participate in gene transcription, and their dysregulation plays a key role in breast cancer. Our study identified 459 differentially expressed TFs between tumor and normal samples from The Cancer Genome Atlas database. Based on gene expression analysis and weighted gene co-expression network analysis, the co-expression yellow module was found to be integral for breast cancer progression. A total of 121 genes in the yellow module were used for function enrichment. To further confirm prognosis-related TFs, COX regression and LASSO analyses were performed; consequently, a prognostic risk model was constructed, and its validity was verified. Ten prognosis-related TFs were identified according to their expression profile, survival probability, and target genes. COPS5, HDAC2, and NONO were recognized as hub TFs in breast cancer. These TFs were highly expressed in human breast cancer cell lines and clinical breast cancer samples; this result was consistent with the information from multiple databases. Immune infiltration analysis revealed that the proportions of resting dendritic and mast cells were greater in the low-risk group than those in the high-risk group. Thus, in this study, we identified three hub biomarkers related to breast cancer prognosis. The results provide a framework for the co-expression of TF modules and immune infiltration in breast cancer.

Inhibition of HDACs Suppresses Cell Proliferation and Cell Migration of Gastric Cancer by Regulating E2F5 Targeting BCL2

(1) Background: Gastric cancer (GC) is the most common high death-rate cancer type worldwide, with an enhanced prevalence and increased rate of mortality. Although significant evidence on surgery strategy has been generated for the treatment of GC, conclusions are still uncertain regarding profound metastatic or persevering gastric cancer. Therefore, it is essential to develop novel and effective biomarkers or therapeutic targets for the diagnosis of GC. Histone deacetylations (HDACs) are important epigenetic regulators that control the aberrant transcription of critical genes that are mainly involved in cell proliferation, cell migration, regulation of the cell cycle, and different signal pathways. (2) Methods: Expression analysis of HDACs family members and E2F5 in gastric cancer cell lines was determined by RT-PCR and Western blotting. The cell proliferation was determined through an MTT assay. Cell migration was determined using a wound-healing assay. Flow cytometry experiments were used to determine cell-cycle analysis. The statistical software OriginPro 2015 (OriginLab, Northampton, MA, USA) was used to analyze data. A p value of < 0.05 was regarded as significant. (3) Results: The present study shows that E2F5 expression is upregulated in GC cancer cell lines compared to normal cell lines, and is positively associated with the level of HDACs and BCL2. HDACi and knocking down of E2F5 as tumor suppressors inhibited cell proliferation, migration invasion, and blocked the cell cycle in gastric cancer cells by suppressing BCL2. The results conclude that the anticancer mechanism of HDACi was determined by regulating E2F5 via targeting BCL2. (4) Conclusions: Our results suggest that the HDAC–E2F5–BCL2 signaling axis might be a novel potential biomarker in gastric cancer.

The miR-200 Family of microRNAs: Fine Tuners of Epithelial-Mesenchymal Transition and Circulating Cancer Biomarkers

The miR-200 family of microRNAs (miRNAs) includes miR-200a, miR-200b, miR-200c, miR-141 and miR-429, five evolutionarily conserved miRNAs that are encoded in two clusters of hairpin precursors located on human chromosome 1 (miR-200b, miR-200a and miR-429) and chromosome 12 (miR-200c and miR-141). The mature -3p products of the precursors are abundantly expressed in epithelial cells, where they contribute to maintaining the epithelial phenotype by repressing expression of factors that favor the process of epithelial-to-mesenchymal transition (EMT), a key hallmark of oncogenic transformation. Extensive studies of the expression and interactions of these miRNAs with cell signaling pathways indicate that they can exert both tumor suppressor- and pro-metastatic functions, and may serve as biomarkers of epithelial cancers. This review provides a summary of the role of miR-200 family members in EMT, factors that regulate their expression, and important targets for miR-200-mediated repression that are involved in EMT. The second part of the review discusses the potential utility of circulating miR-200 family members as diagnostic/prognostic biomarkers for breast, colorectal, lung, ovarian, prostate and bladder cancers.

DACH1 inhibits breast cancer cell invasion and metastasis by down-regulating the transcription of matrix metalloproteinase 9

Human Dachshund homolog 1 (DACH1) is usually defined as a tumor suppressor, which plays an influential role in tumor growth and metastasis in a variety of cancer cells. However, the underlying mechanisms in these process are not yet fully clarified. In this study, DACH1 inhibited the invasion and metastasis of breast cancer cells by decreasing MMP9 expression. Mechanistically, DACH1 represses the transcriptional level of MMP9 by interacting with p65 and c-Jun at the NF-κB and AP-1 binding sites in MMP9 promoter respectively, and the association of DACH1 and p65 promote the recruitment of HDAC1 to the NF-κB binding site in MMP9 promoter, resulting in the reduction of the acetylation level and the transcriptional activity of p65. Accordingly, the level of MMP9 was decreased. In conclusion, we found a new mechanism that DACH1 could inhibit the metastasis of breast cancer cells by inhibiting the expression of MMP9.

Targeting Histone Modifications in Breast Cancer: A Precise Weapon on the Way

Histone modifications (HMs) contribute to maintaining genomic stability, transcription, DNA repair, and modulating chromatin in cancer cells. Furthermore, HMs are dynamic and reversible processes that involve interactions between numerous enzymes and molecular components. Aberrant HMs are strongly associated with tumorigenesis and progression of breast cancer (BC), although the specific mechanisms are not completely understood. Moreover, there is no comprehensive overview of abnormal HMs in BC, and BC therapies that target HMs are still in their infancy. Therefore, this review summarizes the existing evidence regarding HMs that are involved in BC and the potential mechanisms that are related to aberrant HMs. Moreover, this review examines the currently available agents and approved drugs that have been tested in pre-clinical and clinical studies to evaluate their effects on HMs. Finally, this review covers the barriers to the clinical application of therapies that target HMs, and possible strategies that could help overcome these barriers and accelerate the use of these therapies to cure patients.

Role of estrogen receptor coregulators in endocrine resistant breast cancer

Breast cancer (BC) is the most ubiquitous cancer in women. Approximately 70–80% of BC diagnoses are positive for estrogen receptor (ER) alpha (ERα). The steroid hormone estrogen [17β-estradiol (E2)] plays a vital role both in the initiation and progression of BC. The E2-ERα mediated actions involve genomic signaling and non-genomic signaling. The specificity and magnitude of ERα signaling are mediated by interactions between ERα and several coregulator proteins called coactivators or corepressors. Alterations in the levels of coregulators are common during BC progression and they enhance ligand-dependent and ligand-independent ERα signaling which drives BC growth, progression, and endocrine therapy resistance. Many ERα coregulator proteins function as scaffolding proteins and some have intrinsic or associated enzymatic activities, thus the targeting of coregulators for blocking BC progression is a challenging task. Emerging data from in vitro and in vivo studies suggest that targeting coregulators to inhibit BC progression to therapy resistance is feasible. This review explores the current state of ERα coregulator signaling and the utility of targeting the ERα coregulator axis in treating advanced BC.

Histone deacetylase 2 selective inhibitors: A versatile therapeutic strategy as next generation drug target in cancer therapy

Acetylation and deacetylation of histone and several non-histone proteins are the two important processes amongst the different modes of epigenetic modulation that are involved in regulating cancer initiation and development. Abnormal expression of histone deacetylases (HDACs) is often reported in various types of cancers. Few pan HDAC inhibitors have been approved for use as therapeutic interventions for cancer treatment including vorinostat, belinostat and panobinostat. However, not all the HDAC isoforms are abnormally expressed in certain cancers, such as in the case of, ovarian cancer where overexpression of HDAC1-3, lung cancer where overexpression of HDAC 1 and 3 and gastric cancer where overexpression of HDAC2 is seen. Therefore, pan-inhibition of HDAC is not an efficient way to combat cancer via HDAC inhibition. Hence, isoform-selective HDAC inhibition can be one of the best therapeutic strategies in the treatment of cancer. In this context since aberrant expression of HDAC2 largely contributes to cancer progression by silencing pro-apoptotic protein expressions such as NOXA and APAF1 (caspase 9-activating proteins) and inactivation of tumor suppressor p53, HDAC2 specific inhibitors may help to develop not only the direct targets but also indirect targets that are crucial for tumor development. However, to develop a HDAC2 specific and potent inhibitor, extensive knowledge of its structure and specific functions is essential. The present review updates details on the structural features, physiological functions, and roles of HDAC2 in different types of cancer, emphasizing the challenges and status of the development of HDAC2 selective inhibitors against various types of cancer.

Long non-coding RNA H19 regulates proliferation and doxorubicin resistance in MCF-7 cells by targeting PARP1

Chemoresistance is a major obstacle to effective breast cancer chemotherapy. However, the underlying molecular mechanisms remain unclear. The long noncoding RNA H19 (H19) is involved in various stages of tumorigenesis, however, its role in doxorubicin resistance remains unknown. The goal of this study was to evaluate the role of H19 in the development of doxorubicin-resistant breast cancer. Quantitative real-time PCR (qRT-PCR) analyzed H19 expression in chemotherapy-resistant and sensitive breast cancer tissues. Both knockdown and overexpression of H19 were used to assess the sensitivity to doxorubicin in breast cancer cells in vitro and in vivo. qRT-PCR and Western blot were used to explore the doxorubicin resistance mechanism of H19. We observed that the H19 expression was significantly upregulated in chemotherapy-resistant breast cancer tissues and doxorubicin-resistant breast cancer cell lines. Knockdown of H19 enhanced the sensitivity to doxorubicin both in vitro and in vivo. While H19 overexpression developed doxorubicin-resistant in breast cancer cells both in vitro and in vivo. Furthermore, it was revealed that H19 negatively regulated PARP1 expression in breast cancer cells following doxorubicin treatment. Knockdown of H19 sensitized breast cancer cells to doxorubicin by promoting PARP1 upregulation. H19 overexpression could recapitulate doxorubicin resistance by PARP1 downregulation. Our findings revealed that H19 plays a leading role in breast cancer chemoresistance development, mediated mainly through a H19-PARP1 pathway.

Overexpression of PELP1 in Lung Adenocarcinoma Promoted E2 Induced Proliferation, Migration and Invasion of the Tumor Cells and Predicted a Worse Outcome of the Patients

The expression of Proline-, glutamic acid-, and leucine-rich protein 1 (PELP1) has been reported to be dysregulated in non-small cell lung carcinoma, especially in lung adenocarcinoma (LUAD). Therefore, we aimed to investigate the functional and prognostic roles of PELP1 in LUAD in this study. We first immunolocalized PELP1 in 76 cases of LUAD and 17 non-pathological or tumorous lung (NTL) tissue specimens and correlated the findings with the clinicopathological parameters of the patients. We then performed in vitro analysis including MTT, flow cytometry, wound healing, and transwell assays in order to further explore the biological roles of PELP1 in 17-β-estradiol (E₂) induced cell proliferation, migration, and invasion of LUAD cells. We subsequently evaluated the prognostic significance of PELP1 in LUAD patients using the online survival analysis tool Kaplan-Meier Plotter. The status of PELP1 immunoreactivity in LUAD was significantly higher than that in the NTL tissues and significantly positively correlated with less differentiated features of carcinoma cells, positive lymph node metastasis, higher clinical stage as well as the status of ERα, ERβ, and PCNA. In vitro study did reveal that E₂ promoted cell proliferation and migration and elevated PELP1 protein level in PELP1-high A549 and H1975 cells but not in PELP1-low H-1299 cells. Knock down of PELP1 significantly attenuated E₂ induced cell proliferation, colony formation, cell cycle progress as well as migration and invasion of A549 and H1975 cells. Kaplan-Meier Plotter revealed that LUAD cases harboring higher PELP1 expression had significantly shorter overall survival. In summary, PELP1 played a pivotal role in the estrogen-induced aggressive transformation of LUAD and could represent adverse clinical outcome of the LUAD patients.

Interaction of transcription factor AP-2 gamma with proto-oncogene PELP1 promotes tumorigenesis by enhancing RET signaling

A significant proportion of estrogen receptor-positive (ER+) breast cancer (BC) initially responds to endocrine therapy but eventually evolves into therapy-resistant BC. Transcription factor AP-2 gamma (TFAP2C) is a known regulator of ER activity, and high expression of TFAP2C is associated with a decreased response to endocrine therapies. PELP1 is a nuclear receptor coregulator, commonly overexpressed in BC, and its levels are correlated with poorer survival. In this study, we identified PELP1 as a novel interacting protein of TFAP2C. RNA-seq analysis of PELP1 knockdown BC cells followed by transcription factor motif prediction pointed to TFAP2C being enriched in PELP1-regulated genes. Gene set enrichment analysis (GSEA) revealed that the TFAP2C-PELP1 axis induced a subset of common genes. Reporter gene assays confirmed PELP1 functions as a coactivator of TFAP2C. Mechanistic studies showed that PELP1-mediated changes in histone methylation contributed to increased expression of the TFAP2C target gene RET. Furthermore, the TFAP2C-PELP1 axis promoted the activation of the RET signaling pathway, which contributed to downstream activation of AKT and ERK pathways in ER+ BC cells. Concomitantly, knockdown of PELP1 attenuated these effects mediated by TFAP2C. Overexpression of TFAP2C contributed to increased cell proliferation and therapy resistance in ER+ BC models, while knockdown of PELP1 mitigated these effects. Utilizing ZR75-TFAP2C xenografts with or without PELP1 knockdown, we provided genetic evidence that endogenous PELP1 is essential for TFAP2C-driven BC progression in vivo. Collectively, our studies demonstrated that PELP1 plays a critical role in TFAP2C transcriptional and tumorigenic functions in BC and blocking the PELP1-TFAP2C axis could have utility for treating therapy resistance.

Epigenetic Regulation of MicroRNA Clusters and Families during Tumor Development

MicroRNAs are small non-coding single-stranded RNA molecules regulating gene expression on a post-transcriptional level based on the seed sequence similarity. They are frequently clustered; thus, they are either simultaneously transcribed into a single polycistronic transcript or they may be transcribed independently. Importantly, microRNA families that contain the same seed region and thus target related signaling proteins, may be localized in one or more clusters, which are in a close relationship. MicroRNAs are involved in basic physiological processes, and their deregulation is associated with the origin of various pathologies, including solid tumors or hematologic malignancies. Recently, the interplay between the expression of microRNA clusters and families and epigenetic machinery was described, indicating aberrant DNA methylation or histone modifications as major mechanisms responsible for microRNA deregulation during cancerogenesis. In this review, the most studied microRNA clusters and families affected by hyper- or hypomethylation as well as by histone modifications are presented with the focus on particular mechanisms. Finally, the diagnostic and prognostic potential of microRNA clusters and families is discussed together with technologies currently used for epigenetic-based cancer therapies.

Fragile Gene WWOX Guides TFAP2A/TFAP2C-Dependent Actions Against Tumor Progression in Grade II Bladder Cancer

INTRODUCTION

The presence of common fragile sites is associated with no-accidental chromosomal instability which occurs prior to carcinogenesis. The WWOX gene spans the second most active fragile site: FRA16D. Chromosomal breakage at this site is more common in bladder cancer patients who are tobacco smokers which suggests the importance of WWOX gene loss regarding bladder carcinogenesis. Tryptophan domains of WWOX are known to recognize motifs of other proteins such as AP-2α and AP-2γ allowing protein-protein interactions. While the roles of both AP-2 transcription factors are important for bladder carcinogenesis, their nature is different. Based on the literature, AP-2γ appears to be oncogenic, whereas AP-2α mainly exhibits tumor suppressor character. Presumably, the interaction between WWOX and both transcription factors regulates thousands of genes, hence the aim of the present study was to determine WWOX, AP-2α, and AP-2γ function in modulating biological processes of bladder cancer.

METHODS

RT-112 cell line (grade II bladder cancer) was subjected to two stable lentiviral transductions. Overall, this resulted in six variants to investigate distinct WWOX, AP-2α, or AP-2γ function as well as WWOX in collaboration with a particular transcription factor. Cellular models were examined with immunocytochemical staining and in terms of differences in biological processes using assays investigating cell viability, proliferation, apoptosis, adhesion, clonogenicity, migration, activity of metalloproteinases and 3D culture growth.

RESULTS

WWOX overexpression increased apoptosis but decreased cell viability, migration and large spatial colonies. AP-2α overexpression decreased tumor cell viability, migratory potential, matrix metalloproteinase-2 activity and clonogenicity. AP-2γ overexpression decreased matrix metalloproteinase-2 activity but increased wound healing, adhesion, clonogenicity and spatial colony formation. WWOX and AP-2α overexpression induced apoptosis but decreased cell viability, adhesion, matrix metalloproteinase-2 activity, overall number of cultured colonies and migration rate. WWOX and AP-2γ overexpression decreased tumor cell viability, proliferation potential, adhesion, clonogenicity and the ability to create spatial structures, but also increased apoptosis or migration rate.

CONCLUSION

Co-overexpression of WWOX with AP-2α or WWOX with AP-2γ resulted in a net anti-tumor effect. However, considering this research findings and the difference between AP-2α and AP-2γ, we suggest that this similarity is due to a divergent behavior of WWOX.

Glycogen synthase kinase-3 inhibition overcomes epithelial-mesenchymal transition-associated resistance to osimertinib in EGFR-mutant lung cancer

A novel epidermal growth factor receptor (EGFR)‐tyrosine kinase inhibitor, osimertinib, has marked efficacy in patients with EGFR‐mutant lung cancer. While epithelial‐mesenchymal transition (EMT) plays a role in the resistance to various targeted drugs, its involvement in EGFR‐inhibitor resistance remains largely unknown. Preclinical experiments with osimertinib‐resistant lung cancer cells showed that EMT was associated with decreased microRNA‐200c and increased ZEB1 expression. In several resistant clone cells, pretreatment with the histone deacetylase inhibitor quisinostat helped overcome the resistance by reverting EMT. Furthermore, drug screening from a library of 100 kinase inhibitors indicated that Glycogen synthase kinase‐3 (GSK‐3) inhibitors, such as LY2090314, markedly inhibited the growth and induced apoptosis of resistant cells, specifically those with a mesenchymal phenotype. These results suggest that GSK‐3 inhibition could be useful to circumvent EMT‐associated resistance to osimertinib in EGFR‐mutant lung cancer.

PELP1 is a novel oncogene in gastric tumorigenesis and negatively regulated by miR-15 family microRNAs

BACKGROUD

Gastric cancer (GC) is one of the leading causes of cancer-related death in East Asia and some South American countries, but its mechanism has not been clarified clearly. Proline-, glutamic acid-, and leucine-rich protein-1 (PELP1), a co-regulatory molecule of estrogen receptor α (ER α), is up-regulated in series of cancers such as endometrial carcinoma, ovarian cancer, colorectal cancer, breast cancer, and non-small cell lung cancer. However, PELP1's role in GC is still obscure, and its aberrant expression in cancers also remains to be explained.

METHODS

Immunohistochemical staining and Real-time PCR were used to compare the expression level of PELP1 in GC tissues and adjacent tissues. Western blot was used to detect the expression of PELP1 in cell lines. Kaplan-meier analysis and chi-square test were applied to evaluate the potential of PELP1 to function as a cancer biomarker. RNA interference was used to inhibit PELP1 expression in GC cells, followed by detecting cell proliferation, apoptosis, migration and invasion. Luciferase assay was conducted to validate whether miR-15 family members can directly target PELP1.

RESULTS

In this study, we validated that PELP1 was significantly up-regulated in GC samples and cell lines. It was also demonstrated that the up-regulation of PELP1 was associated with several clinicopathologic features such as tumor diameter (P< 0.001), serum CEA level (P= 0.034), and lymphatic metastasis (P= 0.0009) of GC patients, and its high expression was correlated with shorter disease-free survival and overall survival of the patients. Knockdown of PELP1 remarkably arrested the proliferationï¼ migration and invasion, while promoted apoptosis. We also confirmed that miR-15 family microRNAs, most of which were down-regulated and tumor suppressor in cancers, were posttranscriptional regulators of PELP1.

CONCLUSION

In conclusion, we demonstrated that PELP1 was an oncogene of GC associated with patients' prognosis and miR-15 family members contributed to its aberrant expression in cancers.

PELP1 Suppression Inhibits Gastric Cancer Through Downregulation of c-Src-PI3K-ERK Pathway

Background: Proline-, glutamic acid-, and leucine-rich protein 1 (PELP1), a co-activator of estrogen receptors alpha, was confirmed to be directly associated with the oncogenic process of multiple cancers, especially hormone-dependent cancers. The purpose of our research was to explore the biological function, clinical significance, and therapeutic targeted value of PELP1 in gastric cancer (GC).

Methods: The expression status of PELP1 in GC cell lines or tissues was analyzed through bioinformatics data mining. Thirty-six GC tissue chip was applied to demonstrate the results of bioinformatics data mining assayed by immunohistochemical method. The expression status of PELP1 in GC cell lines was also analyzed using western blot. Correlation analysis between PELP1 expression and clinicopathological parameter was performed. Kaplan-Meier survival analysis was applied to analyze the relationship between PELP1 expression and total survival time. Three pairs of siRNA were designed to silence the expression of PELP1 in GC. After PELP1 was silenced by siRNA or activated by saRNA, the growth, plate colony formation, migration and invasion ability of the GC cell or normal gastric epithelium cell line was tested in vitro. Cell cycle was tested by flow cytometry. Nude mice xenograft experiment was performed after PELP1 was silenced. The downstream molecular pathway regulated by PELP1 was explored. Molecular docking tool was applied to combine chlorpromazine with PELP1. The inhibitory effect of chlorpromazine in GC was assayed, then it was tested whether PELP1 was a therapeutic target of chlorpromazine in GC.

Results: PELP1 expression was elevated in GC cell lines and clinical GC tissue samples. PELP1 silence by siRNA compromised the malignant traits of GC. PELP1 expression positively correlated with tumor invasion depth, lymph node metastasis, tissue grade, TNM stage, but had no correlation with patient age, sex, tumor size, and tumor numbers. Kaplan-Meier survival analysis revealed high PELP1 expression had a shorter survival period in GC patients after follow-up. Q-PCR and western blot revealed PELP1 suppression in GC decreased expression of the c-Src-PI3K-ERK pathway. It was also implied that chlorpromazine (CPZ) can inhibit the malignant traits of GC and downregulate the expression of PELP1.

Conclusions: In a word, PELP1 is an oncogene in gastric cancer and c-Src-PI3K-ERK pathway activation may be responsible for its tumorigenesis, PELP1 may be a potential therapeutic target of chlorpromazine in GC.

Targeting epigenetic regulators for cancer therapy: mechanisms and advances in clinical trials

Epigenetic alternations concern heritable yet reversible changes in histone or DNA modifications that regulate gene activity beyond the underlying sequence. Epigenetic dysregulation is often linked to human disease, notably cancer. With the development of various drugs targeting epigenetic regulators, epigenetic-targeted therapy has been applied in the treatment of hematological malignancies and has exhibited viable therapeutic potential for solid tumors in preclinical and clinical trials. In this review, we summarize the aberrant functions of enzymes in DNA methylation, histone acetylation and histone methylation during tumor progression and highlight the development of inhibitors of or drugs targeted at epigenetic enzymes.

PELP1 promotes glioblastoma progression by enhancing Wnt/β-catenin signaling

Background

Glioblastoma (GBM) is a deadly neoplasm of the central nervous system. The molecular mechanisms and players that contribute to GBM development is incompletely understood.

Methods

The expression of PELP1 in different grades of glioma and normal brain tissues was analyzed using immunohistochemistry on a tumor tissue array. PELP1 expression in established and primary GBM cell lines was analyzed by Western blotting. The effect of PELP1 knockdown was studied using cell proliferation, colony formation, migration, and invasion assays. Mechanistic studies were conducted using RNA-seq, RT-qPCR, immunoprecipitation, reporter gene assays, and signaling analysis. Mouse orthotopic models were used for preclinical evaluation of PELP1 knock down.

Results

Nuclear receptor coregulator PELP1 is highly expressed in gliomas compared to normal brain tissues, with the highest expression in GBM. PELP1 expression was elevated in established and patient-derived GBM cell lines compared to normal astrocytes. Knockdown of PELP1 resulted in a significant decrease in cell viability, survival, migration, and invasion. Global RNA-sequencing studies demonstrated that PELP1 knockdown significantly reduced the expression of genes involved in the Wnt/β-catenin pathway. Mechanistic studies demonstrated that PELP1 interacts with and functions as a coactivator of β-catenin. Knockdown of PELP1 resulted in a significant increase in survival of mice implanted with U87 and GBM PDX models.

Conclusions

PELP1 expression is upregulated in GBM and PELP1 signaling via β-catenin axis contributes to GBM progression. Thus, PELP1 could be a potential target for the development of therapeutic intervention in GBM.

MicroRNA-455-3p mediates GATA3 tumor suppression in mammary epithelial cells by inhibiting TGF-β signaling

GATA3 is a basic and essential transcription factor that regulates many pathophysiological processes and is required for the development of mammary luminal epithelial cells. Loss-of-function GATA3 alterations in breast cancer are associated with poor prognosis. Here, we sought to understand the tumor-suppressive functions GATA3 normally performs. We discovered a role for GATA3 in suppressing epithelial-to-mesenchymal transition (EMT) in breast cancer by activating miR-455-3p expression. Enforced expression of miR-455-3p alone partially prevented EMT induced by transforming growth factor β (TGF-β) both in cells and tumor xenografts by directly inhibiting key components of TGF-β signaling. Pathway and biochemical analyses showed that one miRNA-455-3p target, the TGF-β-induced protein ZEB1, recruits the Mi-2/nucleosome remodeling and deacetylase (NuRD) complex to the promotor region of miR-455 to strictly repress the GATA3-induced transcription of this microRNA. Considering that ZEB1 enhances TGF-β signaling, we delineated a double-feedback interaction between ZEB1 and miR-455-3p, in addition to the repressive effect of miR-455-3p on TGF-β signaling. Our study revealed that a feedback loop between these two axes, specifically GATA3-induced miR-455-3p expression, could repress ZEB1 and its recruitment of NuRD (MTA1) to suppress miR-455, which ultimately regulates TGF-β signaling. In conclusion, we identified that miR-455-3p plays a pivotal role in inhibiting the EMT and TGF-β signaling pathway and maintaining cell differentiation. This forms the basis of that miR-455-3p might be a promising therapeutic intervention for breast cancer.

Modulation of all-trans retinoic acid-induced MiRNA expression in neoplastic cell lines: a systematic review

Background

Cancer is a genetic and epigenetic disease that involves inactivation of tumor suppressor genes and activation of proto-oncogenes. All-trans retinoic acid (ATRA) is an isomer of retinoic acid involved in the onset of differentiation and apoptosis of a number of normal and cancer cells, functioning as an anti-cancer agent in several neoplasms. Ectopic changes in the expression of certain microRNAs (miRNAs) occur in response to ATRA, leading to phenotypic alterations in neoplastic cell lines. Moreover, the modulation of miRNA patterns upon ATRA-treatment may represent an effective chemopreventive and anti-cancer therapy strategy. The present systematic review was performed to provide an overview of the modulation of ATRA-induced miRNA expression in different types of neoplastic cells and identify the efficacy of intervention factors (i.e., concentration and duration of treatment) and how they influence expression profiles of oncogenesis-targeting miRNAs.

Methods

A systematic search was conducted according to the PRISMA statement via the US National Library of Medicine MEDLINE/PubMed bibliographic search engine.

Results

The search identified 31 experimental studies involving human cell lines from nine different cancer types (neuroblastoma, acute myeloid leukemia, breast cancer, lung cancer, pancreatic cancer, glioma, glioblastoma, embryonal carcinoma, and colorectal cancer) treated with ATRA at concentrations ranging from 10^− 3 μmol/L to 10² μmol mol/L for 24 h to 21 days.

Conclusion

The concentrations used and the duration of treatment of cancer cells with ATRA varied widely. The presence of ATRA in the culture medium of cancer cells was able to modulate the expression of more than 300 miRNAs, and inhibit invasive behavior and deregulated growth of cancer cells, resulting in total tumor remission in some cases. ATRA may thus be broadly effective for neoplasm treatment and prevention, although these studies may not accurately represent in vivo conditions. Additional studies are required to elucidate ATRA-induced miRNA modulation during neoplasm treatment.

Tac2-N acts as a novel oncogene and promotes tumor metastasis via activation of NF-κB signaling in lung cancer

BACKGROUND

High rates of recurrence and metastasis are the major cause of the poor outcomes for patients with lung cancer. In previous research, we have demonstrated that Tac2-N promotes tumor growth by suppressing p53 signaling in lung cancer. Beyond that, other biological functions and clinical significance of Tac2-N in lung cancer progression are still unknown.

METHODS

Tissue microarrays of 272 lung cancer patients were constructed to assess the association of Tac2-N expression and prognosis of lung cancer patients with different clinical stages. The protein expression of Tac2-N in metastatic and non-metastatic specimens were detected by IHC. In vitro migration and invasion and in vivo nude mice metastasis model were used to evaluate the effect of Tac2-N ectopic expression on metastasis capability of lung cancer cells. The downstream signaling pathway of Tac2-N was explored using luciferase reporter assays and WB.

RESULTS

The expression of Tac2-N was associated with advanced stages, but not with early stages (P = 0.513). Tac2-N expression is sharply overexpressed in metastatic tumors compared with non-metastatic tumors. In vitro and in vivo assays suggested that Tac2-N facilitated migration and invasion of lung cancer cells in vitro and promoted tumor metastasis in vivo. Mechanistically, Tac2-N increased the degradation of IκB by promoting its phosphorylation, and subsequently activated NF-κB activity by facilitating the nuclear translocation of NF-κB and stimulating the transcription of targets, MMP7 and MMP9. Notably, the C2B domain of Tac2-N was crucial for Tac2-N to activate NF-κB signal. Blockage of NF-κB by shRNA or inhibitor attenuates the function of Tac2-N in the promotion of metastasis.

CONCLUSIONS

Our study provided proof of principle to show that Tac2-N serves as a novel oncogene gene and plays an important role in the progression and metastasis of lung cancer.

Amplification of the CD24 Gene Is an Independent Predictor for Poor Prognosis of Breast Cancer

CD24 is a glycosyl-phosphatidyl-inositol linked glycoprotein expressed in a broad range of cell types including cancer cells. Although it is overexpressed in nearly 70% of human cancers, copy number variation of the CD24 locus has not been reported for any cancer. Here, we analyzed the genomics, transcriptomics, and clinical data of 1082 breast cancer (BRCA) samples and other cancer samples from the clinically annotated genomic database, The Cancer Genome Atlas (TCGA). The GISTIC2 method was applied to stratify the CD24 copy number, and Cox regression was performed to compare hazard ratio (HR) of CD24 overexpression, amplification and other traditional prognosis features for overall survival (OS). Our data demonstrated that CD24 amplification strongly correlated with its mRNA overexpression as well as TP53 mutant, cancer proliferation and metastasis features. In particular, CD24 amplification was enriched in basal-like subtype samples and associated with poor clinical outcome. Surprisingly, based on the univariate Cox regression analysis, CD24 overexpression (HR = 1.62, P = 0.010) and copy number amplification (HR = 1.79, P = 0.022) was more relevant to OS than TP53 mutant, mutation counts, diagnosis age, and BRCA subtypes. And based on multivariate survival analysis, CD24 amplification remained the most significant and independent predictor for worse OS (HR = 1.88, P = 0.015).

EC359: A First-in-Class Small-Molecule Inhibitor for Targeting Oncogenic LIFR Signaling in Triple-Negative Breast Cancer

Leukemia inhibitory factor receptor (LIFR) and its ligand LIF play a critical role in cancer progression, metastasis, stem cell maintenance, and therapy resistance. Here, we describe a rationally designed first-in-class inhibitor of LIFR, EC359, which directly interacts with LIFR to effectively block LIF/LIFR interactions. EC359 treatment exhibits antiproliferative effects, reduces invasiveness and stemness, and promotes apoptosis in triple-negative breast cancer (TNBC) cell lines. The activity of EC359 is dependent on LIF and LIFR expression, and treatment with EC359 attenuated the activation of LIF/LIFR-driven pathways, including STAT3, mTOR, and AKT. Concomitantly, EC359 was also effective in blocking signaling by other LIFR ligands (CTF1, CNTF, and OSM) that interact at LIF/LIFR interface. EC359 significantly reduced tumor progression in TNBC xenografts and patient-derived xenografts (PDX), and reduced proliferation in patient-derived primary TNBC explants. EC359 exhibits distinct pharmacologic advantages, including oral bioavailability, and in vivo stability. Collectively, these data support EC359 as a novel targeted therapeutic that inhibits LIFR oncogenic signaling.See related commentary by Shi et al., p. 1337.

Epithelial-to-Mesenchymal Transition Is a Mechanism of ALK Inhibitor Resistance in Lung Cancer Independent of ALK Mutation Status

Mutations in the ALK gene are detectable in approximately 40% of ALK-rearranged lung cancers resistant to ALK inhibitors. Although epithelial-to-mesenchymal transition (EMT) is a mechanism of resistance to various targeted drugs, its involvement in ALK inhibitor resistance is largely unknown. In this study, we report that both ALK-mutant L1196M and EMT were concomitantly detected in a single crizotinib-resistant lesion in a patient with ALK-rearranged lung cancer. Digital PCR analyses combined with microdissection after IHC staining for EMT markers revealed that ALK L1196M was predominantly detected in epithelial-type tumor cells, indicating that mesenchymal phenotype and ALK mutation can coexist as independent mechanisms underlying ALK inhibitor-resistant cancers. Preclinical experiments with crizotinib-resistant lung cancer cells showed that EMT associated with decreased expression of miR-200c and increased expression of ZEB1 caused cross-resistance to new-generation ALK inhibitors alectinib, ceritinib, and lorlatinib. Pretreatment with the histone deacetylase (HDAC) inhibitor quisinostat overcame this resistance by reverting EMT in vitro and in vivo. These findings indicate that HDAC inhibitor pretreatment followed by a new ALK inhibitor may be useful to circumvent resistance constituted by coexistence of resistance mutations and EMT in the heterogeneous tumor. SIGNIFICANCE: These findings show that dual inhibition of HDAC and ALK receptor tyrosine kinase activities provides a means to circumvent crizotinib resistance in lung cancer.

Downregulation of HDAC2 and HDAC3 via oleuropein as a potent prevention and therapeutic agent in MCF-7 breast cancer cells

Breast cancer is the most common malignancy in the world with the highest rate of morbidity and mortality. Due to the several side effects of chemotherapy and radiotherapy, recent studies have focused on the use of herbal medicines. Epidemiological reports have shown the inverse relationship between breast cancer risk and intake of olive. Oleuropein (OLE) is a polyphenolic compound in virgin olive oil with antineoplastic properties and it is well tolerated by humans. Recent reports have shown that OLE has effects on the control of cancer by modulating epigenetics, such as histone deacetylase (HDAC) inhibition. However, the epigenetic mechanisms of OLE anticancer properties are yet to be properly investigated. Therefore, this study aimed to determine the therapeutic effects of OLE through the modulation of histone deacetylase 2 (HDAC2) and histone deacetylase 3 (HDAC3) expression in breast cancer cell line. MCF-7 cells were tested with and without OLE, and also the cell viability, apoptosis, and migration were examined. HDAC2 and HDAC3 expression genes were assessed by quantitative real-time polymerase chain reaction. It was found that OLE decreased the expression of both HDAC2 and HDAC3 (P < 0.05), induced apoptosis and retarded cell migration and cell invasion in a dose-dependent manner (P < 0.05). These results showed that OLE is a potential therapeutic and preventive agent for breast cancer.

Screening of Recurrence Related MicroRNA in Ductal Carcinoma In Situ and Functional Study of MicroRNA-654-5p

Purpose

Ductal carcinoma in situ (DCIS) contributes to 20%–30% of newly diagnosed cases of breast cancer in China. Although the breast cancer-specific mortality of DCIS is extremely low, a small proportion of DCIS patients still show relapse or metastasis, leading to poor prognosis. Little is known about the molecular mechanism for DCIS metastasis, partly due to the limited number of poor prognosis patients. This study analyzed the clinicopathological features and screened key microRNAs (miRNAs) contributing to local or distant recurrence.

Methods

The clinicopathological features of DCIS were evaluated and survival analysis were performed to clarify risk factors associated with poor prognosis. Using miRNA arrays and real-time quantitative polymerase chain reaction (RT-qPCR) on DCIS formalin-fixed and paraffin-embedded samples with or without microinvasion with different clinical outcomes, potential DCIS metastasis-related miRNAs were screened out and further validated. The influence of one identified miRNA, miRNA-654-5p, on DCIS progression was analyzed.

Results

Poor prognosis was significantly associated with larger tumor size and higher lymph node metastasis rate (both p < 0.05). Both were independent prognostic factors for DCIS. According to RT-qPCR results, distinct miRNA expression profiles were identified between DCIS and DCIS with microinvasion (DCIS-Mi) patients. In the DCIS panel, miRNA-654-5p was significantly upregulated in the patients with poor prognosis. In vitro, miRNA-654-5p promoted MDA-MB-231 cell mobility in healing tests and metastasis in the Transwell study.

Conclusion

The panel of high-risk miRNAs in DCIS and DCIS-Mi differs markedly. miRNA-654-5p is significantly upregulated DCIS patients having poor prognosis and may be essential for local and distant recurrence in DCIS.

Heterogeneity and Plasticity of Breast Cancer Stem Cells

In the last 20 years, the conventional view of breast cancer as a homogeneous collection of highly proliferating malignant cells was totally replaced by a model of increased complexity, which points out that breast carcinomas are tissues composed of multiple populations of transformed cells. A large diversity of host cells and structural components of the extracellular matrix constitute the mammary tumour microenvironment, which supports its growth and progression, where individual cancer cells evolve with cumulative phenotypic and genetic heterogeneity. Moreover, contributing to this heterogeneity, it has been demonstrated that breast cancers can exhibit a hierarchical organization composed of tumour cells displaying divergent lineage biomarkers and where, at the apex of this hierarchy, some neoplastic cells are able to self-renew and to aberrantly differentiate. Breast cancer stem cells (BCSCs), as they were entitled, not only drive tumourigenesis, but also mediate metastasis and contribute to therapy resistance.Recently, adding more complexity to the system, it has been demonstrated that BCSCs maintain high levels of plasticity, being able to change between mesenchymal-like and epithelial-like states in a process regulated by the tumour microenvironment. These stem cell state transitions play a fundamental role in the process of tumour metastasis, as well as in the resistance to putative therapeutic strategies to target these cells. In this chapter, it will be mainly discussed the emerging knowledge regarding the contribution of BCSCs to tumour heterogeneity, their plasticity, and the role that this plasticity can play in the establishment of distant metastasis. A major focus will also be given to potential clinical implications of these discoveries in breast cancer recurrence and to possible BCSC targeted therapeutics by the use of specific biomarkers.

miR-506 attenuates methylation of lncRNA MEG3 to inhibit migration and invasion of breast cancer cell lines via targeting SP1 and SP3

Background

Breast cancer has been the first death cause of cancer in women all over the world. Metastasis is believed to be the most important process for treating breast cancer. There is evidence that lncRNA MEG3 functions as a tumor suppressor in breast cancer metastasis. However, upstream regulation of MEG3 in breast cancer remain elusive. Therefore, it is critical to elucidate the underlying mechanism upstream MEG3 to regulate breast cancer metastasis.

Methods

We employed RT-qPCR and Western blot to examine expression level of miR-506, DNMT1, SP1, SP3 and MEG3. Besides, methylation-specific PCR was used to determine the methylation level of MEG3 promoter. Wound healing assay and transwell invasion assay were utilized to measure migration and invasion ability of breast cancer cells, respectively.

Results

SP was upregulated while miR-506 and MEG3 were downregulated in breast tumor tissue compared to adjacent normal breast tissues. In addition, we found that miR-506 regulated DNMT1 expression in an SP1/SP3-dependent manner, which reduced methylation level of MEG3 promoter and upregulated MEG3 expression. SP3 knockdown or miR-506 mimic suppressed migration and invasion of MCF-7 and MDA-MB-231 cells whereas overexpression of SP3 compromised miR-506-inhibited migration and invasion.

Conclusions

Our data reveal a novel axis of miR-506/SP3/SP1/DNMT1/MEG3 in regulating migration and invasion of breast cancer cell lines, which provide rationales for developing effective therapies to treating metastatic breast cancers.

Epithelial-to-mesenchymal transition and cancer stem cells contribute to breast cancer heterogeneity

Breast cancer is the most common cancer in women, and accounts for ~30% of new cancer cases and 15% of cancer-related deaths. Tumor relapse and metastasis are primary factors contributing to breast cancer-related deaths. Therefore, the challenge for breast cancer treatment is to sustain remission. A driving force behind tumor relapse is breast cancer heterogeneity (both intertumor, between different patients, and intratumor, within the same tumor). Understanding breast cancer heterogeneity is necessary to develop preventive interventions and targeted therapies. A recently emerging concept is that intratumor heterogeneity is driven by cancer stem cells (CSCs) that are capable of giving rise to a multitude of different cells within a tumor. Studies have highlighted linkage of CSC formation with epithelial-to-mesenchymal transition (EMT). In this review, we summarize the current understanding of breast cancer heterogeneity, links between EMT and CSCs, regulation of EMT by Runx transcription factors, and potential therapeutic strategies targeting these processes.

MicroRNA-708-3p mediates metastasis and chemoresistance through inhibition of epithelial-to-mesenchymal transition in breast cancer

Metastasis and chemoresistance remain major challenges in the clinical treatment of breast cancer. Recent studies show that dysregulated microRNAs (miRNAs) play an important role in metastasis and chemoresistance development in breast cancer. Herein, we identified downregulated expression of miR-708-3p in breast cancers. In particular, miR-708-3p expression was significantly decreased in specimens from breast cancer patients with metastasis compared to that in specimens from patients with no metastasis. Consistent with clinical data, our in vitro data show that miR-708-3p was more significantly decreased in invasive breast cancer cell lines. In addition, our data show that inhibition of miR-708-3p significantly stimulated breast cancer cell metastasis and induced chemoresistance both in vitro and in vivo. In contrast, overexpression of miR-708-3p dramatically inhibited breast cancer cell metastasis and enhanced the sensitivity of breast cancer cells to chemotherapy both in vitro and in vivo. Furthermore, we identified that miR-708-3p inhibits breast cancer cell epithelial-to-mesenchymal transition (EMT) by directly targeting EMT activators, including ZEB1, CDH2 and vimentin. Taken together, our findings suggest that miR-708-3p acts as a cancer suppressor miRNA and carries out its anticancer function by inhibiting EMT in breast cancer. In addition, our findings suggest that restoration of miR-708-3p may be a novel strategy for inhibiting breast cancer metastasis and overcoming the chemoresistance of breast cancer cells.

The miR-200b/200a/429 cluster prevents metastasis and induces dormancy in a murine claudin-low mammary tumor cell line

The miR-200 family of microRNAs consisting of miR-141, miR-200a, miR-200b, miR-200c and miR-429 are emerging as important regulators of breast cancer progression. This family of microRNAs maintain mammary epithelial identity and downregulation of miR-200 expression has been associated with epithelial-to-mesenchymal transition in mammary tumors. Therefore, re-expression of one or more miR-200 family members in mammary tumor cells with mesenchymal characteristics may restore an epithelial phenotype including growth and metastasis suppression. To test this hypothesis, the miR-200b/200a/429 cluster was re-expressed in a murine claudin-low cell line, RJ423. Re-expression of the miR-200b/200a/429 cluster in RJ423 cells significantly suppressed the expression of Vim, Snai1, Twist1, Twist2 and Zeb1, reverted RJ423 cells to a more epithelial morphology and significantly inhibited proliferation in vitro. Moreover, the miR-200b/200a/429 cluster prevented lung metastasis in an experimental metastasis model and although tumor initiation was not prevented, re-expression of the miR-200b/200a/429 cluster induced a dormancy-like state where mammary tumors failed to grow beyond ~150 mm³ or grew extremely slowly following intra-mammary injection. These dormant tumors contained elevated levels of collagen and were highly vascularized. Therefore, re-expression of the miR-200b/200a/429 cluster in the claudin-low mammary tumor cell line, RJ423, is sufficient to alter cell morphology, impair metastasis and induce tumor dormancy.