SP1 mediates the link between methylation of the tumour suppressor miR-149 and outcome in colorectal cancer

Epigenetically Regulating Non-coding RNAs in Colorectal Cancer: Promises and Potentials

Colorectal cancer (CRC) is a common malignancy with high mortality. Despite advancements in understanding its molecular causes and improved drug therapies, patient survival rates remain low. The main reasons for the high mortality rate are cancer metastasis and the emergence of drug-resistant cancer cell populations. While genetic changes are recognized as the main driver of CRC occurrence and progression, recent studies suggest that epigenetic regulation is a crucial marker in cancer, influencing the interplay between genetics and the environment. Research has shown the significant regulatory roles of non-coding RNAs (ncRNAs) in CRC development. This review explores epigenetically regulated ncRNAs and their functions, aiming to understand key regulatory mechanisms that impact CRC development. Additionally, it discusses the potential use of these ncRNAs in CRC diagnosis, prognosis, and targeted treatments.

miR-181a: regulatory roles, cancer-associated signaling pathway disruptions, and therapeutic potential

INTRODUCTION

microRNA-181a (miR-181a) is a crucial post-transcriptional regulator of many mRNA transcripts and noncoding-RNAs, influencing cell proliferation, cancer cell stemness, apoptosis, and immune responses. Its abnormal expression is well-characterized in numerous cancers, establishing it as a significant genomic vulnerability and biomarker in cancer research.

AREAS COVERED

Here, we summarize miR-181a's correlation with poor patient outcomes across numerous cancers and the mechanisms governing miR-181a's activity and processing. We comprehensively describe miR-181a's involvement in multiple regulatory cancer signaling pathways, cellular processes, and the tumor microenvironment. We also discuss current therapeutic approaches to targeting miR-181a, highlighting their limitations and future potential.

EXPERT OPINION

miR-181a is a clinically relevant pan-cancer biomarker with potential as a therapeutic target. Its regulatory control of tumorigenic signaling pathways and immune responses positions it as a promising candidate for personalized treatments. The success of miR-181a as a target relies on the development of specific therapeutics platforms. Future research on miR-181a's role in the tumor microenvironment and the RNA binding proteins that regulate its stability will help uncover new techniques to targeting miR-181a. Further research into miR-181a serum levels in patients undergoing therapy will help to better stratify patients and enhance therapeutic success.

SP4 Facilitates Esophageal Squamous Cell Carcinoma Progression by Activating PHF14 Transcription and Wnt/Β-Catenin Signaling

Specificity protein 4 transcription factor (SP4), a member of the Sp/Krüppel-like family (KLF), could bind to GT and GC box promoters, and plays an essential role in transcriptional activating. Despite SP4 having been detected to be highly expressed in a variety of human tumors, its biological effect and underlying molecular mechanism in esophageal squamous cell carcinoma (ESCC) remains unclear. Our research discovered that high SP4 expression is detected in primary ESCC specimens and cell lines and is strongly associated with the ESCC tumor grade and poor prognosis. In vitro, knockdown of SP4 suppressed cell proliferation and cell-cycle progression and promoted apoptosis, whereas overexpression of SP4 did the opposite. In vivo, inhibiting SP4 expression in ESCC cells suppresses tumor growth. Subsequently, we demonstrated that SP4 acts as the transcriptional upstream of PHF14, which binds to PHF14 promoter region, thus promoting PHF14 transcription. PHF14 was also significantly expressed in patient tissues and various ESCC cell lines and its expression promoted cell proliferation and inhibited apoptosis. Moreover, knockdown of SP4 inhibited the Wnt/β-catenin signaling pathway, whereas overexpression of PHF14 eliminated the effects of SP4 knockdown in ESCC cells. These results demonstrate that SP4 activates the Wnt/β-catenin signaling pathway by driving PHF14 transcription, thereby promoting ESCC progression, which indicates that SP4 might act as a prospective prognostic indicator or therapeutic target for patients with ESCC.

IMPLICATIONS

This study identified SP4/PH14 axis as a new mechanism to promote the progression of ESCC, which may serve as a novel therapeutic target for patients with ESCC.

17β-estradiol promotes extracellular vesicle release and selective miRNA loading in ERα-positive breast cancer

The causes and consequences of abnormal biogenesis of extracellular vesicles (EVs) are not yet well understood in malignancies, including in breast cancers (BCs). Given the hormonal signaling dependence of estrogen receptor-positive (ER+) BC, we hypothesized that 17β-estradiol (estrogen) might influence EV production and microRNA (miRNA) loading. We report that physiological doses of 17β-estradiol promote EV secretion specifically from ER+ BC cells via inhibition of miR-149-5p, hindering its regulatory activity on SP1, a transcription factor that regulates the EV biogenesis factor nSMase2. Additionally, miR-149-5p downregulation promotes hnRNPA1 expression, responsible for the loading of let-7's miRNAs into EVs. In multiple patient cohorts, we observed increased levels of let-7a-5p and let-7d-5p in EVs derived from the blood of premenopausal ER+ BC patients, and elevated EV levels in patients with high BMI, both conditions associated with higher levels of 17β-estradiol. In brief, we identified a unique estrogen-driven mechanism by which ER+ BC cells eliminate tumor suppressor miRNAs in EVs, with effects on modulating tumor-associated macrophages in the microenvironment.

Specificity Proteins (Sp) and Cancer

The specificity protein (Sp) transcription factors (TFs) Sp1, Sp2, Sp3 and Sp4 exhibit structural and functional similarities in cancer cells and extensive studies of Sp1 show that it is a negative prognostic factor for patients with multiple tumor types. In this review, the role of Sp1, Sp3 and Sp4 in the development of cancer and their regulation of pro-oncogenic factors and pathways is reviewed. In addition, interactions with non-coding RNAs and the development of agents that target Sp transcription factors are also discussed. Studies on normal cell transformation into cancer cell lines show that this transformation process is accompanied by increased levels of Sp1 in most cell models, and in the transformation of muscle cells into rhabdomyosarcoma, both Sp1 and Sp3, but not Sp4, are increased. The pro-oncogenic functions of Sp1, Sp3 and Sp4 in cancer cell lines were studied in knockdown studies where silencing of each individual Sp TF decreased cancer growth, invasion and induced apoptosis. Silencing of an individual Sp TF was not compensated for by the other two and it was concluded that Sp1, Sp3 and Sp4 are examples of non-oncogene addicted genes. This conclusion was strengthened by the results of Sp TF interactions with non-coding microRNAs and long non-coding RNAs where Sp1 contributed to pro-oncogenic functions of Sp/non-coding RNAs. There are now many examples of anticancer agents and pharmaceuticals that induce downregulation/degradation of Sp1, Sp3 and Sp4, yet clinical applications of drugs specifically targeting Sp TFs are not being used. The application of agents targeting Sp TFs in combination therapies should be considered for their potential to enhance treatment efficacy and decrease toxic side effects.

The complex network of transcription factors, immune checkpoint inhibitors and stemness features in colorectal cancer: A recent update

Cancer immunity is regulated by several mechanisms that include co-stimulatory and/or co-inhibitory molecules known as immune checkpoints expressed by the immune cells. In colorectal cancer (CRC), CTLA-4, LAG3, TIM-3 and PD-1 are the major co-inhibitory checkpoints involved in tumor development and progression. On the other hand, the deregulation of transcription factors and cancer stem cells activity plays a major role in the development of drug resistance and in the spread of metastatic disease in CRC. In this review, we describe how the modulation of such transcription factors affects the response of CRC to therapies. We also focus on the role of cancer stem cells in tumor metastasis and chemoresistance and discuss both preclinical and clinical approaches for targeting stem cells to prevent their tumorigenic effect. Finally, we provide an update on the clinical applications of immune checkpoint inhibitors in CRC and discuss the regulatory effects of transcription factors on the expression of the immune inhibitory checkpoints with specific focus on the PD-1 and PD-L1 molecules.

circBGN accelerates gastric cancer cell proliferation and invasion via activating IL6/STAT3 signaling pathway

Circular RNAs participate in the pathogenesis of various tumors, including gastric cancer (GC). In this study, we investigated the role of circBGN in regulating proliferation and invasion of GC cells and elucidated the mechanism. The expression of circBGN was assessed by quantitative reverse-transcription PCR and in situ hybridization. In addition, loss- and gain-of-function investigations in vitro and in vivo were performed to determine the biological functions of circBGN. Luciferase reporter assays and rescue experiments were applied to investigate the interaction between circBGN and miR-149-5p as well as the relationship between miR-149-5p and IL6. Our results showed that circBGN expression was significantly elevated in GC tissues and cells. Knockdown of circBGN dramatically suppressed GC cell proliferation and invasion in vitro. Xenograft experiments revealed that knockdown of circBGN delayed tumor growth in vivo. Furthermore, circBGN can directly bind to miR-149-5p, thereby preventing miR-149-5p from binding to its target mRNA [IL6 mRNA], thus activating IL6/STAT3 signaling pathway. Rescue assays indicated that circBGN regulates GC cell proliferation and invasion by upregulating miR-149-5p/IL6 axis output. Taken together, our investigation indicates that circBGN supports GC progression by activating IL6/STAT3 signaling pathway, thus pointing to a new possible therapeutic target in GC.

RETRACTED ARTICLE: Down-regulation of lncRNA FEZF1-AS1 mediates regulatory T cell differentiation and further blocks immune escape in colon cancer

Statement of RetractionWe, the Editors and Publisher of the journal Expert Review of Molecular Diagnostics, have retracted the following article:Sen Hong, Zhenkun Yan, YuMei Song, MiaoMiao Bi & Shiquan Li. Down-regulation of lncRNA FEZF1-AS1 mediates regulatory T cell differentiation and further blocks immune escape in colon cancer. Expert Review of Molecular Diagnostics. 2021. DOI: 10.1080/14737159.2022.2012157Since publication, significant concerns have been raised about the integrity of the data and reported results in the article. When approached for an explanation, the authors did not provide their original data or any necessary supporting information. As verifying the validity of published work is core to the integrity of the scholarly record, we are therefore retracting the article. The corresponding author listed in this publication has been informed.We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions.The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted'.

MicroRNA Methylome Signature and Their Functional Roles in Colorectal Cancer Diagnosis, Prognosis, and Chemoresistance

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Despite significant advances in the diagnostic services and patient care, several gaps remain to be addressed, from early detection, to identifying prognostic variables, effective treatment for the metastatic disease, and the implementation of tailored treatment strategies. MicroRNAs, the short non-coding RNA species, are deregulated in CRC and play a significant role in the occurrence and progression. Nevertheless, microRNA research has historically been based on expression levels to determine its biological significance. The exact mechanism underpinning microRNA deregulation in cancer has yet to be elucidated, but several studies have demonstrated that epigenetic mechanisms play important roles in the regulation of microRNA expression, particularly DNA methylation. However, the methylation profiles of microRNAs remain unknown in CRC patients. Methylation is the next major paradigm shift in cancer detection since large-scale epigenetic alterations are potentially better in identifying and classifying cancers at an earlier stage than somatic mutations. This review aims to provide insight into the current state of understanding of microRNA methylation in CRC. The new knowledge from this study can be utilized for personalized health diagnostics, disease prediction, and monitoring of treatment.

Stanniocalcin 2 (STC2): a universal tumour biomarker and a potential therapeutical target

Stanniocalcin 2 (STC2) is a glycoprotein which is expressed in a broad spectrum of tumour cells and tumour tissues derived from human breast, colorectum, stomach, esophagus, prostate, kidney, liver, bone, ovary, lung and so forth. The expression of STC2 is regulated at both transcriptional and post-transcriptional levels; particularly, STC2 is significantly stimulated under various stress conditions like ER stress, hypoxia and nutrient deprivation. Biologically, STC2 facilitates cells dealing with stress conditions and prevents apoptosis. Importantly, STC2 also promotes the development of acquired resistance to chemo- and radio- therapies. In addition, multiple groups have reported that STC2 overexpression promotes cell proliferation, migration and immune response. Therefore, the overexpression of STC2 is positively correlated with tumour growth, invasion, metastasis and patients' prognosis, highlighting its potential as a biomarker and a therapeutic target. This review focuses on discussing the regulation, biological functions and clinical importance of STC2 in human cancers. Future perspectives in this field will also be discussed.

Identification of prognostic long intergenic non-coding RNAs as competing endogenous RNAs with KRAS mutations in colorectal cancer

Colorectal cancer (CRC) is recognized as a common type of human cancer, and KRAS mutations are correlated with poor CRC survival outcomes. The evaluation and prediction of CRC results remain challenging. In the present study, RNA sequencing and clinical data from The Cancer Genome Atlas were used to identify KRAS mutation-related prognostic long intergenic non-coding RNAs (lincRNAs) in CRC. Significantly dysregulated lincRNAs and independent prognostic lincRNAs with KRAS mutations in CRC were identified. Two lincRNAs with KRAS mutations, LINC00265 and AL390719.2, were selected as key prognostic lincRNAs for both 10- and 5-year survival rates. In addition, competing endogenous (ce)RNA models were constructed to comprehensively assess the oncogenic performance of the two key lincRNAs. The ceRNA models suggested that LINC00265 and AL390719.2 are critical for the cell cycle and cancer pathways. Finally, reverse transcription-quantitative PCR was used to validate the ceRNA models in 12 pairs of CRC tissue samples. These prognostic lincRNAs may provide novel biomarkers for the prognostic prediction of CRC. The ceRNA model may also demonstrate the underlying mechanism of these lincRNAs in CRC.

Inhibitory effect of bound polyphenol from foxtail millet bran on miR-149 methylation increases the chemosensitivity of human colorectal cancer HCT-8/Fu cells

Nature polyphenols widely present in plants and foods are promising candidates in cancer chemotherapy. Emerging evidence has shown that plant polyphenols regulate the expression of miRNAs to exert the anti-Multidrug resistance (MDR) activity, which partly attributes to their regulation on miRNAs methylation. Our previous study found that bound polyphenol from foxtail millet bran (BPIS) had potential as an anti-MDR agent for colorectal cancer (CRC), but its mechanism remains unclear. The present findings demonstrated that BPIS upregulated the expression of miR-149 by reducing the methylation of its CpG islands, which subsequently induced the cell cycle arrest in G2/M phase, resulting in enhancing the chemo-sensitivity of HCT-8/Fu cells. Mechanically, BPIS and its active components (FA and p-CA) reduced miR-149 methylation by inhibiting the expression levels of DNA methyltransferases, promoting a remarkable increase of miR-149 expression. Further, the increased miR-149 induced cell cycle arrest in G2/M phase by inhibiting the expression of Akt, Cyclin B1 and CDK1, thus increasing the chemosensitivity of HCT-8/Fu cells. Additionally, a strong inducer of DNA de-methylation (5-aza-dc) treatment markedly increased the chemosensitivity of CRC through elevating miR-149 expression, which indicates the hypermethylation of miR-149 may be the key cause of drug resistance in CRC. The study indicates that the enhanced chemosensitivity of BPIS on CRC is mainly attributed to the increase of miR-149 expression induced by methylation inhibition.

SP1 Expression and the Clinicopathological Features of Tumors: A Meta-Analysis and Bioinformatics Analysis

Objective: Specificity protein 1 (SP1) plays a vital role to promote carcinogenesis in a variety of tumors, and its up-regulated expression is reported to be a hinter of poor prognosis of patients. We conducted this meta-analysis to elucidate the clinical significance and prognostic value of SP1 in malignant tumors. Methods: PubMed and Cochrane Library were searched for studies published between January 1, 2000 and June 1, 2020. The combined odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (95% CIs) were used to investigate the correlation of SP1 with clinical behaviors and prognosis in patients with solid tumors. UALCAN was used to conduct bioinformatics analysis. Results: A total of 24 documents involving 2,739 patients were enrolled in our review. The random-effect model was used to perform this analysis due to the high level of heterogeneity. SP1 low expression was not conducive to lymph node metastasis (OR = 0.42; 95% CI: 0.28-0.64; p < 0.05), progression of TNM stage (OR = 0.34; 95% CI: 0.20-0.57; p < 0.05) and tumor infiltration (OR = 0.33; 95% CI: 0.18-0.60; p < 0.05). Elevated SP1 expression was connected with shorter survival time of patients with hepatocellular carcinoma, pancreatic cancer, gastric cancer and esophageal cancer (HR = 1.95; 95% CI: 1.16-3.28; p < 0.05). According to UALCAN database, breast cancer, ovarian cancer, colon cancer and lung adenocarcinoma display an elevated SP1 expression in comparison with normal tissues. Kaplan-Meier survival plots indicate SP1 mRNA level has negative effects on prognosis of liver hepatocellular carcinoma and brain lower grade glioma. Conclusion: SP1 was associated with lymph node metastasis, TNM stage and depth of invasion, and indicated poor clinical outcome, which brought new insights on the potential candidacy of SP1 in clinical usage.

Circular RNA 100146 Promotes Colorectal Cancer Progression by the MicroRNA 149/HMGA2 Axis

Colorectal cancer (CRC) has developed into the third leading cause of cancer-associated death worldwide. Studies have confirmed that circular RNAs (circRNAs) absorb microRNAs (miRNAs) to regulate the function of downstream genes. This study aimed to explore the underlying mechanism of circRNA 100146 in CRC. The expression of circRNA 100146, miRNA 149 (miR-149), and high mobility group AT-Hook 2 (HMGA2) was detected by quantitative real-time PCR (RT-qPCR). A series of biofunctional effects (cell viability, apoptosis, migration/invasion) were evaluated by the use of methyl thiazolyl tetrazolium (MTT), flow cytometry, and transwell assays. Protein levels were measured by Western blot assay. A xenograft model was established for in vivo experiments. The interactions among circRNA 100146, miR-149, and HMGA2 were evaluated by dual-luciferase reporter assay, RNA immunoprecipitation assays, or RNA pulldown assay. circRNA 100146 was upregulated in CRC tissues and cells. circRNA 100146 knockdown inhibited cell proliferation, promoted apoptosis, and suppressed migration and invasion in vitro and impeded tumor growth in vivo Also, miR-149 was negatively regulated by circRNA 100146 and was targeted to HMGA2 and mediated its expression. Moreover, miR-149 interference abrogated the activities of silenced circRNA 100146 in proliferation, apoptosis, migration, and invasion. Furthermore, HMGA2 overexpression abated the effects described above caused by circRNA 100146 silencing, while the mutations on miR-149 binding sites in the 3' untranslated region (3'-UTR) of HMGA2 led to its loss of this ability. circRNA 100146 knockdown repressed proliferation, enhanced apoptosis, and hindered migration and invasion in SW620 and SW480 cells through targeting the miR-149/HMGA2 axis.

Dissecting miRNA signature in colorectal cancer progression and metastasis

Colorectal cancer (CRC) is the third most common cancer and leading cause of cancer related deaths worldwide. Despite recent advancements in surgical and molecular targeted therapies that improved the therapeutic efficacy in CRC, the 5 years survival rate of CRC patients still remains frustratingly poor. Accumulated evidences indicate that microRNAs (miRNAs) play a crucial role in the progression and metastasis of CRC. Dysregulated miRNAs are closely associated with cancerous phenotypes (e.g. enhanced proliferative and invasive ability, evasion of apoptosis, cell cycle aberration, and promotion of angiogenesis) by regulating their target genes. In this review, we provide an updated overview of tumor suppressive and oncogenic miRNAs, circulatory miRNAs, and the possible causes of dysregulated miRNAs in CRC. In addition, we discuss the important functions of miRNAs in drug resistance of CRC.

Transcription factors in colorectal cancer: molecular mechanism and therapeutic implications

Colorectal cancer (CRC) is a major cause of cancer mortality worldwide, however, the molecular mechanisms underlying the pathogenesis of CRC remain largely unclear. Recent studies have revealed crucial roles of transcription factors in CRC development. Transcription factors essential for the regulation of gene expression by interacting with transcription corepressor/enhancer complexes and they orchestrate downstream signal transduction. Deregulation of transcription factors is a frequent occurrence in CRC, and the accompanying drastic changes in gene expression profiles play fundamental roles in multistep process of tumorigenesis, from cellular transformation, disease progression to metastatic disease. Herein, we summarized current and emerging key transcription factors that participate in CRC tumorigenesis, and highlighted their oncogenic or tumor suppressive functions. Moreover, we presented critical transcription factors of CRC, emphasized the major molecular mechanisms underlying their effect on signal cascades associated with tumorigenesis, and summarized of their potential as molecular biomarkers for CRC prognosis therapeutic response, as well as drug targets for CRC treatment. A better understanding of transcription factors involved in the development of CRC will provide new insights into the pathological mechanisms and reveal novel prognostic biomarkers and therapeutic strategies for CRC.

MicroRNA-149: A review of its role in digestive system cancers

MicroRNAs (miRNAs) are a group of highly conserved, short (18-25 nucleotide long) non-coding RNAs which play important functional roles in cellular differentiation, biological development, pathogenesis and disease susceptibility and have been linked to both tumorigenesis and the malignant progression of various cancers. miRNAs primarily exert their function through the negative regulation of their target gene's transcription via the specific recognition of their 3' untranslated region. A single miRNA can regulate multiple target genes and most miRNAs are controlled by several factors. Recent studies have shown that microRNA-149 (miR-149) plays a pivotal role in the pathogenesis of digestive system cancers and may act as a potential diagnostic marker and therapeutic target. In this review, we summarize and discuss the most recent reports describing miR-149 in digestive system cancers, including its single nucleotide polymorphisms, expression levels, target genes, drug sensitivity and clinical significance.

Combined serum miR-29c and miR-149 expression analysis as diagnostic genetic markers for colorectal cancer

Circulating miRNAs gathered much interest in cancer research as noninvasive biomarkers. The aim of this study was to analyze the expression of miR-29c and miR-149 among colorectal cancer (CRC) patients and to explore their diagnostic and prognostic potentials in relation to the clinical and pathological features. The expression levels of miR-29c and miR-149 were evaluated in the sera of 80 CRC patients, 80 colorectal adenoma (CRA) patients, and 80 healthy controls using quantitative real time polymerase chain reaction (PCR). Carcinoembryonic antigen serum levels were assayed using enzyme-linked immunosorbent assay. miR-29c and miR-149 were significantly downregulated among CRC patients compared with CRA and controls (miR-29c, 0.54 ± 0.19 vs. 0.86 ± 0.12, 0.99 ± 0.07, P < 0.001, respectively; miR-149, 0.46 ± 0.19 vs. 0.74 ± 0.012, 1.0 ± 0.22, P < 0.001, respectively). miR-29c and miR-149 significantly associated with advanced stages of CRC, tumor size, and lymphatic metastasis. By using receiver operating characteristic curve analysis, combined miR-29c and miR-149 revealed the highest diagnostic potential for CRA (area under the curve [AUC] = 0.967) from healthy controls as well as the diagnosis of CRC (AUC = 0.98) from CRA. Moreover, combined miRNAs revealed high diagnostic potential for the earlier stages of CRC compared with advanced stages (AUC = 0.96). In conclusion, combined serum miR-29c and miR-149 expression analysis established novel noninvasive biomarker for early CRC diagnosis.

circ5615 functions as a ceRNA to promote colorectal cancer progression by upregulating TNKS

Circular RNAs (circRNAs), non-coding RNAs generated by precursor mRNA back-splicing of exons, have been reported to fulfill multiple roles in cancer. However, the role of quite a lot circRNAs in colorectal cancer (CRC) remains mostly unknown. Herein, we explored the expression profiles of circRNAs in 5 paired samples of CRC patients by microarray and noted a circRNA, hsa_circ_0005615 (circ5615), was significantly upregulated in CRC tissues. Circ5615 was derived from exon 2 of NFATC3 and its upregulation was tightly correlated with higher T stage and poor prognosis in CRC patients. Studies in vitro and in vivo demonstrated that knockdown of circ5615 in cancer cells inhibited proliferation and cell cycle acceleration, while overexpression promoted malignant phenotypes. Mechanistically, RNA immunoprecipitation, biotin-coupled probe pull-down and luciferase reporter assays revealed circ5615 effectively bound to miR-149-5p and might play a role like miR-149-5p sponge. Additionally, tankyrase (TNKS), regulator of β-catenin stabilization, was identified as circ5615 downstream and the potential miR-149-5p targets by RNA-seq and bioinformatics analysis. We further verified the upregulation of β-catenin and cyclin D1 induced by circ5615. Our results indicated that circ5615 exerted oncogenic function as competing endogenous RNA (ceRNA) of miR-149-5p to release TNKS and activated Wnt/β-catenin pathway.

Long non‑coding RNA BCYRN1 promotes glycolysis and tumor progression by regulating the miR‑149/PKM2 axis in non‑small‑cell lung cancer

Cancer cells use aerobic glycolysis to sustain their proliferation. Long non‑coding RNA brain cytoplasmic RNA 1 (BCYRN1) has been reported to act as an oncogene in non‑small‑cell lung cancer (NSCLC). The present study investigated the role of BCYRN1 in NSCLC glycolysis. BCYRN1 expression was detected in NSCLC cells and tissues using reverse transcription‑quantitative PCR. The effect of BCYRN1 on aerobic glycolysis was examined by measuring NSCLC cell glucose catabolism and lactate synthesis. The relationships between BCYRN1 and microRNA (miR)‑149, and between miR‑149 and pyruvate kinase M1/2 (PKM2) were measured using a dual‑luciferase reporter assay. Cell proliferation and invasion were analyzed by the Cell Counting kit‑8 assay and the Matrigel invasion assay, respectively. High BCYRN1 expression was observed in NSCLC tissues and cells compared with the corresponding controls. BCYRN1 induced glycolysis and upregulated the expression levels of PKM2 in NSCLC cells. In addition, BCYRN1 regulated miR‑149 expression levels, and miR‑149 inhibitor rescued the effects of si‑BCYRN1 on glucose consumption and lactate production. miR‑149 knockdown significantly enhanced the expression of PKM2. Furthermore, PKM2 inhibition significantly reversed the effects of miR‑149 inhibitor on glucose catabolism and lactate synthesis. Furthermore, PKM2 was involved in NSCLC cell proliferation and invasion, and BCYRN1 knockdown and miR‑149 overexpression inhibited both processes. The present study suggested that BCYRN1 was involved in cell glycolysis, proliferation and invasion during NSCLC via regulating miR‑149 and PKM2.

Selected microRNAs Increase Synaptic Resilience to the Damaging Binding of the Alzheimer's Disease Amyloid Beta Oligomers

Alzheimer’s disease (AD) is marked by synaptic loss (at early stages) and neuronal death (at late stages). Amyloid beta (Aβ) and tau oligomers can target and disrupt synapses thus driving cognitive decay. Non-demented individuals with Alzheimer’s neuropathology (NDAN) are capable of withstanding Aβ and tau toxicity, thus remaining cognitively intact despite presence of AD neuropathology. Understanding the involved mechanism(s) would lead to development of novel effective therapeutic strategies aimed at promoting synaptic resilience to amyloid toxicity. NDAN have a unique hippocampal post-synaptic proteome when compared with AD and control individuals. Potential upstream modulators of such unique proteomic profile are miRNA-485, miRNA-4723 and miRNA-149, which we found differentially expressed in AD and NDAN vs. control. We thus hypothesized that these miRNAs play an important role in promoting either synaptic resistance or sensitization to Aβ oligomer binding. Using an in vivo mouse model, we found that administration of these miRNAs affected key synaptic genes and significantly decreased Aβ binding to the synapses. Our findings suggest that miRNA regulation and homeostasis are crucial for Aβ interaction with synaptic terminals and support that a unique miRNA regulation could be driving synaptic resistance to Aβ toxicity in NDAN, thus contributing to their preserved cognitive abilities.

miR-149 Suppresses Breast Cancer Metastasis by Blocking Paracrine Interactions with Macrophages

Paracrine activation of cells contained in the tumor microenvironment promotes tumor progression and metastasis. In breast cancer, malignant cells recruit and educate macrophages into a M2 tumor-promoting phenotype that supports the metastatic spread of cancer cells. Here, we show that miR-149 functions as a metastasis-suppressing microRNA in breast cancer cells by limiting colony-stimulating factor-1 (CSF1)-dependent recruitment and M2 polarization of macrophages. In lymph node-positive, triple-negative breast cancer (TNBC) tissues, low miR-149 expression correlated with macrophage infiltration and reduced patient survival. By directly targeting CSF1, miR-149 expression in TNBC cell lines (MDA-MB-231 and BT-549) inhibited the recruitment of human monocytic THP-1 cells and primary human macrophages. Furthermore, in macrophages cocultured with MDA-MB-231 cells expressing miR-149, epidermal growth factor (EGF) and amphiregulin expression levels were strongly reduced, resulting in reduced EGF receptor activation in the cancer cells. In vivo, lung metastases developing from orthotopic MDA-MB-231 tumors were reduced by 75% by miR-149 expression, and this was associated with impaired M2 macrophage infiltration of the primary tumors. These data suggest that miR-149 downregulation functionally contributes to breast tumor progression by recruiting macrophages to the tumor and facilitating CSF1 and EGF receptor cross-talk between cancer cells and macrophages. SIGNIFICANCE: These findings contribute to the understanding of tumor-stroma interactions by showing that miR-149 downregulation in TNBC enhances reciprocal growth factor signaling between macrophages and cancer cells, which promotes tumor progression and metastasis. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/6/1330/F1.large.jpg.

Association between the miRNA-149 rs2292832 T>C polymorphism and Kawasaki disease susceptibility in a southern Chinese population

Background

Kawasaki disease (KD), which is characterized by vasculitis, is prone to occur in patients under 5 years of age, has an ambiguous etiology, and displays coronary artery lesions as the chief complication. Previous studies have linked miRNA‐149 to cancers, and rs2292832 T>C is related to allergic diseases and inflammatory bowel disease, which both show immune system disorders and coronary artery disease. Therefore, we performed a study concentrating on the association between the miRNA‐149 rs2292832 T>C polymorphism and KD susceptibility.

Methods

The subjects enrolled were 532 children with KD and 623 controls. We used TaqMan real‐time PCR to obtain the genotypes of the rs2292832 T>C polymorphism.

Results

Ultimately, no significant association was found between the miRNA‐149 rs2292832 T>C polymorphism and KD susceptibility, even in stratification analysis.

Conclusion

Our results indicated that in southern Chinese patients, the miRNA‐149 rs2292832 T>C polymorphism did not affect KD susceptibility, which needs to be further confirmed.

Sp1 Mediates the Constitutive Expression and Repression of the PDSS2 Gene in Lung Cancer Cells

Prenyl diphosphate synthase subunit 2 (PDSS2) is the first key enzyme in the CoQ10 biosynthesis pathway, and contributes to various metabolic and nephritic diseases. It has been reported that PDSS2 is downregulated in several types of tumors and acts as a potential tumor suppressor gene to inhibit the proliferation and migration of cancer cells. However, the regulatory mechanism of PDSS2 expression remains elusive. In the present study, we first identified and characterized the PDSS2 promoter region. We established four different luciferase reporter constructs which mainly cover the 2 kb region upstream of the PDSS2 gene transcription initiation site. Series luciferase reporter assay demonstrated that all four constructs have prominent promoter activity, and the core promoter of PDSS2 is mainly located within the 202 bp region near its transcription initiation site. Transcription factor binding site analysis revealed that the PDSS2 promoter contains binding sites for canonical transcription factors such as Sp1 and GATA-1. Overexpression of Sp1 significantly inhibited PDSS2 promoter activity, as well as its endogenous expression, at both mRNA and protein levels in lung cancer cells. Site-directed mutagenesis assay further confirmed that the Sp1 binding sites are essential for proximal prompter activity of PDSS2. Consistently, a selective Sp1 inhibitor, mithramycin A, treatment repressed the PDSS2 promoter activity, as well as its endogenous expression. Chromatin immunoprecipitation (ChIP) assay revealed that Sp1 binds to the PDSS2 promoter in vivo. Of note, the expression of Sp1 and PDSS2 are negatively correlated, and higher Sp1 expression with low PDSS2 expression is significantly associated with poor prognosis in lung cancer. Taken together, our results strongly suggest the essential role of Sp1 in maintaining the basic constitutive expression of PDSS2, and the pathogenic implication of Sp1-mediated PDSS2 transcriptional repression in lung cancer cells.

DNA-methylation-mediated silencing of miR-7-5p promotes gastric cancer stem cell invasion via increasing Smo and Hes1

Cancer stem cells are undifferentiated cancer cells that have self-renewal ability, a high tumorigenic activity, and a multilineage differentiation potential. MicroRNAs play a critical role in regulating gene expression during carcinogenesis. Here, we investigated the role of miR-7 and the mechanism by which it is dysregulated in gastric cancer stem cells (GCSCs). The stem cell marker, CD44, was used to sort GCSCs by fluorescence-activated cell sorting. We found that CD44 (+) cells have higher invasiveness and form more number of sphere colonies than CD44 (-) cells. Quantitative real-time polymerase chain reaction (PCR) revealed that the miR-7-5p expression was remarkably downregulated in GCSCs but was significantly increased in the methionine-deprived medium. The downregulation of miR-7-5p results from the increased DNA methylation in the promoter region using the methylation-specific PCR. Overexpression of miR-7-5p reduced the formation of colony and decreased the invasion of GCSCs through targeting Smo and Hes1 and subsequent repressing Notch and Hedgehog signaling pathways in vitro. Notably, upregulating miR-7-5p inhibited the growth of tumor in the xenograft model. Hence, these data demonstrated that miR-7-5p represses GCSC invasion through inhibition of Smo and Hes1, which provides a potential therapeutic target of gastric cancer treatment.

Direct and sensitive detection of circulating miRNA in human serum by ligase-mediated amplification

MicroRNAs (miRNA) involve in regulating different physiological processes whose dysregulation is associated with a wide range of diseases including cancers, diabetes and cardiovascular problems. Herein, we report a direct, sensitive and highly selective detection assay for circulating microRNA (miRNA). This detection strategy employs magnetic nanoparticles as the reaction platform which can not only allow online pre-concentration and selective separation but also integrates ligation reaction with amplification to enhance the sensitivity of the detection assay. With the presence of the target miRNA, the locked nucleic acid (LNA)-modified molecular beacon (MB) opens up, exposing the binding sites at two ends. The 3'- and 5'-end of the MB responsible for the attachment onto the magnetic nanoparticles, and reporting probe for the attachment of the pair of amplification probes respectively. The ligase ligate RNA to DNA enhance the amplification efficiency. Upon labelled with intercalating fluorophores (YOYO-1) on the hybrids, the quantification of the target miRNA was determined by measuring the fluorescence intensity. A detection limit of 314 fM was achieved with trace amount of sample consumption (~20 μL). As a proof of concept, miRNA-149 was chosen as the target miRNA. This assay is capable of discriminating single-base and reliably quantifying circulating miRNA-149 in both healthy and cancer patient's serums. The result obtained was comparable with that of quantitative reverse transcription polymerase chain reaction (qRT-PCR), suggesting that this direct and sensitive assay can be served as a promising, non-invasive tool for early diagnosis of breast cancer and colorectal cancer.

Association of SP1 rs1353058818 and STAT3 rs1053004 gene polymorphisms with human tongue squamous cell carcinoma

Objective: To study the association between SP1 rs1353058818 and STAT3 rs1053004 gene polymorphisms and risk of human tongue squamous cell carcinoma (TSCC).Methods: Sanger sequencing was used to determine the genotypes of SP1 rs1353058818 and STAT3 rs1053004 loci in 240 TSCC patients and 240 controls. Levels of hsa-miR-149-5p and hsa-miR-21-5p and expression levels of SP1 and STAT3 proteins in tumor tissues and adjacent normal tissues of TSCC patients were ascertained.Results: Carrying the SP1 rs1353058818 locus deletion allele was a high risk factor for TSCC (OR = 2.997, 95% CI: 1.389-6.466, P = 0.003). The STAT3 rs1053004 locus A allele was a protective factor for TSCC (OR = 0.604, 95% CI: 0.460-0.793, P < 0.001). There was a negative correlation between SP1 mRNA and hsa-miR-149-5p in tumor and adjacent normal tissues (r = -0.81, -0.77). The expression of SP1 protein in tumor tissues of the SP1 rs1353058818 locus DD genotype was significantly higher than in tissues of the ID type, and in tissues of type II it was the lowest. STAT3 mRNA was positively correlated with hsa-miR-21-5p in tumor and adjacent normal tissues (r = 0.75, 0.78). The expression level of STAT3 protein in tumor tissues of patients with STAT3 rs1053004 locus GG genotype was significantly higher than in patients with type GA, and it was the lowest in patients with type AA.Conclusion: Polymorphisms in the SP1 rs1353058818 and STAT3 rs1053004 loci are associated with the risk of human TSCC.

Ursolic Acid Reverses the Chemoresistance of Breast Cancer Cells to Paclitaxel by Targeting MiRNA-149-5p/MyD88

Paclitaxel (PTX) is widely used as a front-line chemotherapy for breast cancer treatment. However, its clinical applications are limited by the development of chemoresistance. The objective of this study was to investigate the reversal effects of ursolic acid (UA) on PTX resistance and the possible mechanisms in breast cancer. The role of miRNA-149-5p/MyD88 in the regulation of PTX resistance was investigated by the transfection of breast cancer cells with MDA-MB-231 (231) and MDA-MB-231/PTX-resistance (231/PTX) with lentiviruses carrying the MyD88 gene, shRNA specific for MyD88, the miR-149-5p gene, and shRNA specific for miR-149-5p. The PTX sensitivity was assessed by a CCK-8 assay. qRT-PCR and Western blot analyses were used to detect changes in the mRNA and protein levels. Flow cytometry was used to measure the rate of cell apoptosis. A luciferase activity assay was used to detect the binding site of miR-149-5p on the 3'UTR of MyD88. 231/PTX cells were injected into the flanks of female athymic nude mice, and the mice were randomly divided into the five following groups: PBS, PTX (low), PTX (high), UA, and PTX+UA. Our data show that UA reversed the resistance of breast cancer 231/PTX cells to PTX in vitro and in vivo. UA treatment significantly increased the expression of miR-149-5p, which was lower in 231/PTX cells than in 231 cells. Furthermore, the overexpression of miR-149-5p increased the sensitivity of 231/PTX cells to PTX treatment, whereas the knockdown of the miR-149-5p gene attenuated the effects of UA on the regulation of PTX sensitivity. A luciferase assay demonstrated that miR-149-5p could directly regulate the transcriptional activity of MyD88, a known PTX-resistance gene, by targeting the 3'UTR of MyD88. Meanwhile, the downregulation of MyD88 through the overexpression of miR-149-5p or UA treatment inhibited the activation of the Akt signaling pathway in 231/PTX cells. Thus, our data indicate that UA can reverse PTX resistance by targeting the miRNA-149-5p/MyD88 axis in breast cancer cells.

DNA methylation and chromatin modifiers in colorectal cancer

Colorectal carcinogenesis is a multistep process involving the accumulation of genetic alterations over time that ultimately leads to disease progression and metastasis. Binding of transcription factors to gene promoter regions alone cannot explain the complex regulation pattern of gene expression during this process. It is the chromatin structure that allows for a high grade of regulatory flexibility for gene expression. Posttranslational modifications on histone proteins such as acetylation, methylation, or phosphorylation determine the accessibility of transcription factors to DNA. DNA methylation, a chemical modification of DNA that modulates chromatin structure and gene transcription acts in concert with these chromatin conformation alterations. Another epigenetic mechanism regulating gene expression is represented by small non-coding RNAs. Only very recently epigenetic alterations have been included in molecular subtype classification of colorectal cancer (CRC). In this chapter, we will provide examples of the different epigenetic players, focus on their role for epithelial-mesenchymal transition and metastatic processes and discuss their prognostic value in CRC.

Reactive Oxygen Species (ROS)-Inducing Triterpenoid Inhibits Rhabdomyosarcoma Cell and Tumor Growth through Targeting Sp Transcription Factors

Methyl 2-trifluoromethyl-3,11-dioxo-18β-olean-1,12-dien-3-oate (CF3DODA-Me) is derived synthetically from glycyrrhetinic acid, a major component of licorice, and this compound induced reactive oxygen species (ROS) in RD and Rh30 rhabdomyosarcoma (RMS) cells. CF3DODA-Me also inhibited growth and invasion and induced apoptosis in RMS cells, and these responses were attenuated after cotreatment with the antioxidant glutathione, demonstrating the effective anticancer activity of ROS in RMS. CF3DODA-Me also downregulated expression of specificity protein (Sp) transcription factors Sp1, Sp3, and Sp4 and prooncogenic Sp-regulated genes including PAX3-FOXO1 (in Rh30 cells). The mechanism of CF3DODA-Me-induced Sp-downregulation involved ROS-dependent repression of c-Myc and cMyc-regulated miR-27a and miR-17/20a, and this resulted in induction of the miRNA-regulated Sp repressors ZBTB4, ZBTB10, and ZBTB34. The cell and tumor growth effects of CF3DODA-Me further emphasize the sensitivity of RMS cells to ROS inducers and their potential clinical applications for treating this deadly disease. IMPLICATIONS: CF3DODA-Me and HDAC inhibitors that induce ROS-dependent Sp downregulation could be developed for clinical applications in treating rhabdomyosarcoma.

Baicalin induces apoptosis in SW480 cells through downregulation of the SP1 transcription factor

Colorectal cancer occurs throughout the world but is most common in developed countries. Cancer progression is believed to be driven by genetic mutations in this complex condition. Risk factors for developing colorectal cancer include a genetic family history, long-term ulcerative colitis, and colonic polyps. The use of baicalin has been reported to be clinically efficacious against colon tumors in Asian countries despite an unclear mechanism of action. Several cancers have been found to be biologically dependent on the specificity protein 1 (sp1) transcription factor family. We hypothesized that baicalin may exert its chemotherapeutic effects by sp1 downregulation. Using the SW480 human colorectal cancer cell line, we investigated the physiological properties of baicalin. Our experiments were designed toward clarifying three goals: (a) to determine the mRNA expression profile of transcription factors in colorectal cancer patients using a microarray-based analysis; (b) to determine the effects of baicalin on the sp1 transcription factor with western blotting and reporter cell assays; and (c) to contrast the effects of mithramycin-A (an sp1 transcription factor inhibitor) and baicalin using western blotting and reporter cell assays. Both baicalin and mithramycin-A downregulated sp1 expression, attenuated SW480 cell proliferation, and increased cell apoptosis. Baicalin inhibited sp1 expression and led to SW480 apoptosis, thus clarifying the effect of this traditional Chinese medicine compound in the treatment of colon cancer.

SP1-SYNE1-AS1-miR-525-5p feedback loop regulates Ang-II-induced cardiac hypertrophy

Cardiac hypertrophy (CH) has become a huge threat to human health. Recent years, long noncoding RNAs (lncRNAs) have been studied in human diseases, including CH. According to bioinformatics analysis, 10 lncRNAs possibly involved in the progression of CH were screened out. Among which, lncRNA SYNE1 antisense RNA 1 (SYNE1-AS1) could be upregulated by Angiotensin II (Ang-II) in cardiomyocytes. Thus, we chose SYNE1-AS1 to do further study. To identify the biological function of SYNE1-AS1 in CH, SYNE1-AS1 was silenced in Ang-II-induced cardiomyocytes. Results of immunofluorescence staining demonstrated that increased cell surface area in Ang-II-induced cardiomyocytes was reduced by SYNE1-AS1 knockdown. Moreover, the hypertrophic responses were attenuated by SYNE1-AS1 knockdown. Mechanically, SYNE1-AS1 positively regulated Sp1 transcription factor (SP1) by sponging microRNA-525-5p (miR-525-5p). On the basis of previous reports, SP1 can transcriptionally activate lncRNAs. Therefore, we investigated the interaction between SP1 and SYNE1-AS1 promoter. Intriguingly, SYNE1-AS1 was activated by SP1. At last, rescue assays demonstrated the function of SP1-SYNE1-AS1 axis in CH. In conclusion, SP1-induced upregulation of lncRNA SYNE1-AS1 promoted CH via miR-525-5p/SP1 axis.

miR-149-5p inhibits cell growth by regulating TWEAK/Fn14/PI3K/AKT pathway and predicts favorable survival in human osteosarcoma

MicroRNAs (miRNAs) as small non-coding RNAs act as either tumor suppressors or oncogenes in human cancers, of which miR-149-5p (miR-149) is involved in tumor growth and metastasis, but its role and molecular mechanisms underlying osteosarcoma growth are poorly understood. The correlation of miR-149 expression with clinicopathological characteristics and prognosis in patients with sarcoma was analyzed by The Cancer Genome Atlas (TCGA) RNA-sequencing data. Osteosarcoma cell growth affected by miR-149 was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays. As a result, we found that the expression level of miR-149 was markedly downregulated in human sarcoma samples and were negatively associated with tumor size, acting as an independent prognostic factor for overall survival of the sarcoma patients. Restoration of miR-149 expression suppressed osteosarcoma cell growth, while its knockdown reversed these effects. Furthermore, we identified TNFRSF12A (TNF receptor superfamily member 12A), also called fibroblast growth factor–inducible 14 (Fn14) as a direct target of miR-149, and TNFRSF12A and its ligand TNFSF12 (TNF superfamily member 12), also called tumor necrosis factor–related weak inducer of apoptosis (TWEAK), were both negatively correlated with miR-149 expression in sarcoma samples. Knockdown of TNFRSF12A suppressed cell growth, but its overexpression weakened the antiproliferative effects of miR-149 via the PI3K/AKT (AKT serine/threonine kinase) signaling pathway. Altogether, our findings show that miR-149 functions as a tumor suppressor in osteosarcoma via inhibition of the TWEAK–Fn14 axis and represents a potential therapeutic target in patients with osteosarcoma.

DNA-methylation-mediated silencing of miR-486-5p promotes colorectal cancer proliferation and migration through activation of PLAGL2/IGF2/β-catenin signal pathways

As one of the most common cancers worldwide, colorectal cancer (CRC) causes a large number of mortality annually. Aberrant expression of microRNAs (miRNAs) is significantly associated with the initiation and development of CRC. Further investigations regarding the regulatory mechanism of miRNAs is warranted. In this study, we discovered that miR-486-5p was remarkably downregulated in CRC, which partially results from higher DNA methylation in the promoter region detected by using methylation-specific PCR, bisulfite sequencing PCR, and DNA demethylation treatment. Besides, decreased miR-486-5p was obviously associated with advanced TNM stage, larger tumor size, lymphatic metastasis, and poor prognosis in CRC. Upregulated miR-486-5p inhibited the proliferation and migration of CRC through targeting PLAGL2 expression and subsequent repressing IGF/β-catenin signal pathways both in vitro and in vivo. Notably, plasma miR-486-5p expression was significantly upregulated in CRC patients and we identified plasma miR-486-5p as a novel diagnostic biomarker of CRC using receiver operating characteristic (ROC) curve analysis. Moreover, exploration in GEO dataset revealed that circulating miR-486-5p is tumor derived through being packaged into secretory exosomes. Taken together, our data demonstrated that miR-486-5p promotes colorectal cancer proliferation and migration through activation of PLAGL2/IGF2/β-catenin signal pathway, which is a promising therapeutic target of CRC treatment.

MicroRNAs, long noncoding RNAs, and circular RNAs: potential tumor biomarkers and targets for colorectal cancer

Noncoding RNAs (ncRNAs) can be divided into microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), pRNAs, and tRNAs. Traditionally, miRNAs exert their biological function mainly through the inhibition of translation via the induction of target RNA transcript degradation. lncRNAs and circRNAs were once considered to have no potential to code proteins. Here, we will review the current knowledge on ncRNAs in relation to their origins, characteristics, and functions. We will also review how ncRNAs work as competitive endogenous RNA, gene transcription and expression regulators, and RNA-binding protein sponges in colorectal cancer (CRC). Notably, except for the abovementioned mechanisms, recent advances revealed that lncRNAs can also act as the precursor of miRNAs, and a small portion of lncRNAs and circRNAs was verified to have the potential to code proteins, providing new evidence for the significance of ncRNAs in CRC tumorigenesis and development.

Regulation and functions of MicroRNA-149 in human cancers

MicroRNAs are small non-coding RNAs that play critical roles in the regulatory mechanisms involving cell differentiation, proliferation, apoptosis and tumorigenesis. Recent research efforts have been conducted to apply these discoveries into clinical functions, including the early diagnosis and therapeutic outcome of patients with cancer. Previous studies have shown that microRNA-149 (miR-149) is dysregulated in various human cancers and exerts its effects on tumorigenesis and tumour progression. In this review, we summarized the potential roles of miR-149 dysregulation and its target genes during tumorigenesis and clinical treatment of human cancers.

7,12-Dimethylbenz[α]anthracene increases cell proliferation and invasion through induction of Wnt/β-catenin signaling and EMT process

7,12-Dimethylbenz[α]anthracene (DMBA) is a hazardous component present in polluted environments. DMBA has been used as an experimental tool for in vivo tumor formation owing to its carcinogenic effects, but the detailed molecular mechanism of DMBA has not been fully established. To comprehend the carcinogenic mechanism of DMBA, we explored its effects in the breast cancer cell lines, MCF-7 and MDA-MB-231, and the cervical cancer cell line, HeLa. Cell viability assay and measurement of a proliferation marker showed that DMBA markedly increased cancer cell proliferation. Furthermore, morphological observations and wound healing assays in nontumorigenic MCF-10A cells and trans-well invasion assays in cancer cells following DMBA treatment revealed that DMBA induced cell migration and invasion. To reveal the molecular mechanism of DMBA, we investigated the effects of DMBA on the epithelial-mesenchymal transition (EMT) process and Wnt/β-catenin signaling, a critical pathway for cell proliferation that was reported to correlate with the EMT process, by using quantitative RT-PCR (qPCR), western blot analysis, and confocal microscopy. Consequently, we found that DMBA increased cancer cell proliferation and invasion through the promotion of EMT-inducing factors and β-catenin. Especially, it was revealed in promoter activity assay using mutated luciferase vectors on transcription factor-binding sites that TWIST1 is promoted by DMBA through induction of STAT3-mediated promoter activation. To further elucidate the detailed mechanism of DMBA, we aimed to identify the key regulator of its carcinogenic action. DMBA was shown to significantly upregulate the expression of specificity protein 1 (Sp1), a transcription factor, and the carcinogenic effects of DMBA were blocked via the suppression or interruption of Sp1 activity. In conclusion, our data suggested that DMBA induced carcinogenic effects through activation of Wnt/β-catenin signaling and the EMT process by upregulating Sp1 activity.

Specificity Protein Transcription Factors and Cancer: Opportunities for Drug Development

Specificity protein (Sp) transcription factors (TFs) such as Sp1 are critical for early development but their expression decreases with age and there is evidence that transformation of normal cells to cancer cells is associated with upregulation of Sp1, Sp3, and Sp4, which are highly expressed in cancer cells and tumors. Sp1 is a negative prognostic factor for pancreatic, colon, glioma, gastric, breast, prostate, and lung cancer patients. Functional studies also demonstrate that Sp TFs regulate genes responsible for cancer cell growth, survival, migration/invasion, inflammation and drug resistance, and Sp1, Sp3 and Sp4 are also nononcogene addiction (NOA) genes and important drug targets. The mechanisms of drug-induced downregulation of Sp TFs and pro-oncogenic Sp-regulated genes are complex and include ROS-dependent epigenetic pathways that initially decrease expression of the oncogene cMyc. Many compounds such as curcumin, aspirin, and metformin that are active in cancer prevention also exhibit chemotherapeutic activity and these compounds downregulate Sp TFs in cancer cell lines and tumors. The effects of these compounds on downregulation of Sp TFs in normal cells and the contribution of this response to their chemopreventive activity have not yet been determined. Cancer Prev Res; 11(7); 371-82. ©2018 AACR.

Epigenetic silencing of miR-1271 enhances MEK1 and TEAD4 expression in gastric cancer

Epigenetic dysregulation is a major driver of tumorigenesis. To identify tumor-suppressive microRNAs repressed by DNA methylation in gastric cancer (GC), we analyzed the genome-wide DNA methylation and microRNA expression profiles of EpCAM+/CD44+ GC cells. Among the set of microRNAs screened, miR-1271 was identified as a microRNA repressed by DNA methylation in GC. Forced miR-1271 expression substantially suppressed the growth, migration, and invasion of GC cells. To identify candidate target genes and signaling pathways regulated by miR-1271, we performed RNA sequencing. Among the genes down-regulated by miR-1271, MAP2K1 (MEK1) was significantly repressed by miR-1271, and the associated ERK/MAPK signaling pathway was also inhibited. TEAD4 was also repressed by miR-1271, and the associated YAP1 signatures within genes regulated by miR-1271 were significantly enriched. These findings uncovered MEK1 and TEAD4 as novel miR-1271 targets and suggest that the epigenetic silencing of miR-1271 is crucial for GC development.

Prognostic value of microRNAs in colorectal cancer: a meta-analysis

Background

Numerous studies have shown that miRNA levels are closely related to the survival time of patients with colon, rectal, or colorectal cancer (CRC). However, the outcomes of different investigations have been inconsistent. Accordingly, a meta-analysis was conducted to study associations among the three types of cancers.

Materials and methods

Studies published in English that estimated the expression levels of miRNAs with survival curves in CRC were identified until May 20, 2017 by online searches in PubMed, Embase, Web of Science, and the Cochrane Library by two independent authors. Pooled HRs with 95% CIs were used to estimate the correlation between miRNA expression and overall survival.

Results

A total of 63 relevant articles regarding 13 different miRNAs, with 10,254 patients were ultimately included. CRC patients with high expression of blood miR141 (HR 2.52, 95% CI 1.68-3.77), tissue miR21 (HR 1.31, 95% CI 1.12-1.53), miR181a (HR 1.52, 95% CI 1.26-1.83), or miR224 (HR 2.12, 95% CI 1.04-4.34), or low expression of tissue miR126 (HR 1.55, 95% CI 1.24-1.93) had significantly poor overall survival (P<0.05).

Conclusion

In general, blood miR141 and tissue miR21, miR181a, miR224, and miR126 had significant prognostic value. Among these, blood miR141 and tissue miR224 were strong biomarkers of prognosis for CRC.

Formononetin inhibits colon carcinoma cell growth and invasion by microRNA‑149‑mediated EphB3 downregulation and inhibition of PI3K/AKT and STAT3 signaling pathways

Formononetin (Form), a phytoestrogen extracted from the roots of Astragalus membranaceus, is one of the fundamental herbs used in traditional Chinese medicine because of its protective effects against certain malignant tumors. However, its role in colon carcinoma cells and the underlying molecular mechanisms have not been completely elucidated. The present study aimed to demonstrate that Form significantly inhibited the proliferation and invasion of the colon carcinoma cell lines SW1116 and HCT116. Mechanistic studies have suggested that Form suppresses colon carcinoma cell growth by downregulating cell cycle-associated protein (cyclin D1) expression and arresting the cell cycle at the G₀-G₁ checkpoint. Further studies revealed that treatment with Form inhibits matrix metalloproteinase (MMP)2 and MMP9 expression. Aditionally, the results demonstrated that Form significantly increased microRNA (miR)-149 expression. Following miR-149 overexpression in SW1116 and HCT116 cells using an miR-149 mimic, cell viability and Ephrin type-B receptor 3 (EphB3) levels decreased. Furthermore, the inhibitory effects of Form were associated with phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and signal transducer and activator of transcription 3 (STAT3) signaling pathways. These results indicated the suppressive effect of Form on colon carcinoma cell proliferation and invasion, possibly via miR-149-induced EphB3 downregulation and the inhibition of the PI3K/AKT and STAT3 signaling pathways. Overall, Form may be used as a novel candidate for the clinical treatment of colorectal cancer in the future.

Interplay between regulation by methylation and noncoding RNAs in cancers

Cancer is one of the most important health problems today; therefore, many researchers are focusing on exploring the mechanisms underlying its development and treatment. The field of cancer epigenetics has flourished in recent decades, and studies have shown that different epigenetic events, such as DNA methylation, histone modification, and noncoding RNA regulation, work together to influence cancer development and progression. In this short review, we summarize the interactions between methylation and noncoding RNAs that affect cancer development.

Novel long noncoding RNA GACAT3 promotes colorectal cancer cell proliferation, invasion, and migration through miR-149

Aim

To explore the expression and clinical significance of long noncoding RNA (lncRNA) gastric cancer-associated transcript 3 (GACAT3) in human colorectal cancer (CRC).

Methods

Expression of GACAT3 in CRC tissues and cell lines was measured using quantitative real-time PCR. CCK-8 and colony formation assays were used to assess the effect of GACAT3 on CRC cell line proliferation. Transwell invasion and migration assays were performed to detect the effect of GACAT3 on CRC cell line invasion and migration. Bioinformatics prediction, luciferase reporter assay, and pull-down assay were used to determine if miR-149 was a target of GACAT3. In addition, we also conducted colony formation assays and invasion assays to verify that GACAT3 promotes tumor progression through miR-149. Finally, in vivo tumorigenesis studies were used to demonstrate subcutaneous tumor growth.

Results

In the present study, we found that GACAT3 was highly expressed in CRC tissues and cell lines. Si-GACAT3 significantly decreased cell proliferation, motility, and invasiveness both in vitro and in vivo. We confirmed that downregulated GACAT3 significantly increased the expression of miR-149, and miR-149 binds to GACAT3 in a sequence-specific manner using luciferase reporter assays and pull-down assay. Further functional experiments indicated that GACAT3 could directly upregulate SP1 and STAT3 expressions by functioning as a competing endogenous RNA for miR-149, and consequentially, promoting CRC cell proliferation and invasion in vitro.

Conclusion

This study demonstrated that GACAT3 promotes tumor progression through competitive binding to miR-149 and suggests a promising new strategy for anti-CRC therapy.

MicroRNA-33a downregulation is associated with tumorigenesis and poor prognosis in patients with hepatocellular carcinoma

In order to examine the prognostic significance of miR-33a in patients with hepatocellular carcinoma (HCC), total RNA was extracted from 149 HCC biopsies, 36 of which were paired with para-carcinoma tissues, and miR-33a expression was measured by reverse transcription-quantitative polymerase chain reaction. The results demonstrated that miR-33a expression was decreased in HCC biopsies compared with normal liver tissue samples. It was also demonstrated that miR-33a expression was significantly associated with tumor foci number. Furthermore, overall and progression-free survival time was decreased in patients expressing low miR-33a with multiple tumor foci. Taken together, the low expression of miR-33a may be a potential risk factor for HCC.

miR-149 in Human Cancer: A Systemic Review

MicroRNAs (miRNAs) are small noncoding RNAs that regulate post-transcriptional gene expression via binding to the 3'-untranslated region (3'-UTR) of targeted mRNAs. They are reported to play important roles in tumorigenesis and progression of various cancers. Among them, miR-149 was confirmed to be aberrantly regulated in various tumors. In this review, we provide a complex overview of miR-149, particularly summarize the critical roles of it in cancers and expect to lay the foundation for future works on this important microRNA.

Loss of TINCR expression promotes proliferation, metastasis through activating EpCAM cleavage in colorectal cancer

Long non-coding RNAs (lncRNAs) are involved in kinds of human diseases, including colorectal cancer (CRC). TINCR, a 3.7 kb long non coding RNA, was associated with cell differentiation in keratinocyte and gastric cancer cells. However, little is known about the role of TINCR in regulation CRC progression. Here, we showed that lncRNA TINCR was associated with CRC proliferation and metastasis. TINCR was statistically downregulated in CRC tissues and metastatic CRC cell lines compared with their counterparts. TINCR was reversely correlated with CRC progression and promoted tumor cells growth, metastasis in vivo and in vitro. While overexpression of TINCR had opposite effect. In addition, we also found that TINCR specifically bound to EpCAM through RNA IP and RNA pull down assays. Loss of TINCR promoted hydrolysis of EpCAM and then released EpICD, subsequently, activated the Wnt/β-catenin pathway. Further studies shown that c-Myc repressed the expression of TINCR through repressing sp1 transcriptive activity, which established a positive feedback loop controlling c-Myc and TINCR expression. These findings elucidate that loss of TINCR expression promotes proliferation and metastasis in CRC and it could be considered as a potential cancer suppressor gene.

miR-6883 Family miRNAs Target CDK4/6 to Induce G1 Phase Cell-Cycle Arrest in Colon Cancer Cells

CDK4/6 targeting is a promising therapeutic strategy under development for various tumor types. In this study, we used computational methods and The Cancer Genome Atlas dataset analysis to identify novel miRNAs that target CDK4/6 and exhibit potential for therapeutic development in colorectal cancer. The 3'UTR of CDK4/6 mRNAs are targeted by a family of miRNAs, which includes miR-6883-5p, miR-149*, miR-6785-5p, and miR-4728-5p. Ectopic expression of miR-6883-5p or miR-149* downregulated CDK4 and CDK6 levels in human colorectal cancer cells. RNA-seq analysis revealed an inverse relationship between the expression of CDK4/6 and miR-149* and intronic miRNA-6883-5p encoding the clock gene PER1 in colorectal cancer patient samples. Restoring expression of miR-6883-5p and miR-149* blocked cell growth leading to G₀-G₁ phase cell-cycle arrest and apoptosis in colorectal cancer cells. CDK4/6 targeting by miR-6883-5p and miR-149* could only partially explain the observed antiproliferative effects. Notably, both miRNAs synergized with the frontline colorectal cancer chemotherapy drug irinotecan. Further, they resensitized mutant p53-expressing cell lines resistant to 5-fluorouracil. Taken together, our results established the foundations of a candidate miRNA-based theranostic strategy to improve colorectal cancer management. Cancer Res; 77(24); 6902-13. ©2017 AACR.