The HER2-miR125a5p/miR125b loop in gastric and esophageal carcinogenesis

Regulatory role of miR-125a expression with respect to its target genes LIFR, ERBB2 and STAT3 in the pathogenesis of recurrent pregnancy losses

OBJECTIVES

Studies have investigated miR-125a for its predictable role in recurrent pregnancy loss (RPL) cases to regulate many biological events required for the maintenance of pregnancy by regulating its confirmed target genes LIFR, ERBB2 and STAT3.

METHODS

The present study included 40 cases of women with at least two RPLs in ≤20 weeks of gestation against 40 healthy multiparous women without a previous history of abortion. Expression analysis of ERBB2, LIFR, STAT3 and miR-125a was conducted by quantitative real-time PCR (qPCR).

RESULTS

The expression of miR-125a was significantly lower in the plasma of RPL cases (P = 0.0001) and showed a significantly increased mean expression level in product of conception (2.56-fold, P < 0.0001). Among the target gene of miR-125a, ERBB2 and STAT3 gene expression level was significantly increased (2.58-fold, P = 0.04; 1.87-fold, P = 0.025), respectively in RPL cases while the LIFR gene revealed comparable expression (P = 0.64). Furthermore, expression analysis of ERBB2 gene with respect to its regulatory miR-125a cases depicted a significant association (P = 0.0005). Kaplan-Meier survival analysis revealed cases with low miR-125a expression had significantly shorter time to miscarriages, (log-rank P = 0.02). Also, decreased expression of miR-125a significantly conferred >2-fold increased risk for RPL (HR = 2.34: P < 0.05).

CONCLUSION

The overall conclusion of the study was that altered miR-125a expression may cause deregulation in target genes LIFR, ERBB2 and STAT3 resulting in adverse consequence in the outcome of pregnancy.

Differentially expressed microRNA in prognosis of gastric cancer with Lauren classification

BACKGROUND

Gastric cancer (GC) is one of the most common tumors. There were several classifications of GC recently. The value of Lauren classification in evaluating the prognosis after radical gastrectomy was still unclear and the prognosis of gastric cancer remained relatively poor in the absence of prognostic biomarkers. This study aimed to explore microRNA (miRNA) in the prognosis of GC with different Lauren classification.

METHODS

A retrospective study of 1144 patients was performed in this study. Quantificational reverse transcription-PCR (qRT-PCR) was used to examine the expression of miRNAs. Univariate and multivariate analysis were performed to evaluate prognosis value of Lauren classification.

RESULTS

Total 1144 GC patients were recruited in this cohort, including 302 diffuse type (26.4%), 436 intestinal type (38.1%) and 406 mixed type (35.5%) GC. Multivariate analysis showed that Lauren classification, patients' age, tumor size, tumor infiltrating depth, vascular nerve infiltrating and metastatic lymph nodes ration were significantly correlated with GC patients' OS and DFS. The miR-141-3p, miR-200b-3p and miR-133a-5p were significantly down-regulated in diffuse type compared to intestinal type GC tissues, the miR-105-5p had significant lower expression in diffuse type compared with intestinal type and mixed type GC tissues. As a consequence of univariate analysis, low miR-141-3p in diffuse type GC showed significant worse OS and DFS than high miR-141-3p.

CONCLUSIONS

Lauren classification was an independent prognostic factor in GC. MiR-141-3p was an independent prognostic factor and a promising prognostic biomarker in Lauren classification GC.

Two-in-One Nanoparticle Formulation to Deliver a Tyrosine Kinase Inhibitor and microRNA for Targeting Metabolic Reprogramming and Mitochondrial Dysfunction in Gastric Cancer

Dysregulational EGFR, KRAS, and mTOR pathways cause metabolic reprogramming, leading to progression of gastric cancer. Afatinib (Afa) is a broad-spectrum tyrosine kinase inhibitor that reduces cancer growth by blocking the EGFR family. MicroRNA 125 (miR-125) reportedly diminishes EGFRs, glycolysis, and anti-apoptosis. Here, a one-shot formulation of miR-125 and Afa was presented for the first time. The formulation comprised solid lipid nanoparticles modified with mitochondrial targeting peptide and EGFR-directed ligand to suppress pan-ErbB-facilitated epithelial–mesenchymal transition and mTOR-mediated metabolism discoordination of glycolysis–glutaminolysis–lipids. Results showed that this cotreatment modulated numerous critical proteins, such as EGFR/HER2/HER3, Kras/ERK/Vimentin, and mTOR/HIF1-α/HK2/LDHA pathways of gastric adenocarcinoma AGS cells. The combinatorial therapy suppressed glutaminolysis, glycolysis, mitochondrial oxidative phosphorylation, and fatty acid synthesis. The cotreatment also notably decreased the levels of lactate, acetyl-CoA, and ATP. The active involvement of mitophagy supported the direction of promoting the apoptosis of AGS cells, which subsequently caused the breakdown of tumor-cell homeostasis and death. In vivo findings in AGS-bearing mice confirmed the superiority of the anti-tumor efficacy and safety of this combination nanomedicine over other formulations. This one-shot formulation disturbed the metabolic reprogramming; alleviated the “Warburg effect” of tumors; interrupted the supply of fatty acid, cholesterol, and triglyceride; and exacerbated the energy depletion in the tumor microenvironment, thereby inhibiting tumor proliferation and aggressiveness. Collectively, the results showed that the two-in-one nanoparticle formulation of miR-125 and Afa was a breakthrough in simplifying drug preparation and administration, as well as effectively inhibiting tumor progression through the versatile targeting of pan-ErbB- and mTOR-mediated mitochondrial dysfunction and dysregulated metabolism.

Methylation-mediated silencing of miR-125a-5p facilitates breast cancer progression by inducing autophagy

BACKGROUND

microRNA-125a-5p (miR-125a) is a tumor suppressor gene whose role in autophagy remains poorly understood. In the current study, we aimed to investigate the methylation status of miR-125a, its transfection into SK-BR3 cells, and its effects on autophagy.

METHODS

Sixty samples of tumor and non-tumor adjacent tissue were collected and the methylation status of miR-125a was evaluated by methylation-specific PCR (MSP). The effect of 5-Aza-dC on miR-125a expression was investigated in the SK-BR3 cells. Cells were also transfected with miR-125a mimic/antimiR. The expression of miR-125a and its target genes was evaluated by Real-Time PCR. Protein levels of ATG5 and LC3 were assessed by Western blotting. HER2 expression was investigated by immunocytochemistry (ICC).

RESULTS

The data showed that the miR-125a promoter CpG Island was significantly hypermethylated in breast cancer tissues (p < 0.01) and in SK-BR3 cells. The 5-Aza-dC could significantly increase miR-125a expression by decreasing its methylation (p < 0.05). In addition, Western blot analysis indicated the expression of ATG5 and LC3 II/ LC3I, as autophagy biomarkers, was significantly reduced in SK-BR3 cells transfected with miR-125a (p < 0.05).

CONCLUSIONS

Our data showed miR-125a expression was significantly decreased in tumor tissues due to its promoter hypermethylation. Overexpression of miR-125a was associated with a reduction in autophagy, which could provide a new therapeutic avenue for advanced-stage breast cancer treatment.

Implications of Decreased Expression of miR-125a with Respect to Its Variant Allele in the Pathogenesis of Recurrent Pregnancy Loss: A Study in a High Incidence Zone

Pregnancy is controlled by several types of genes and the regulation of their expression is tightly controlled by miRNAs. The present study was carried out to explore the association between miR-125a polymorphic sequence variation and its expression and recurrent pregnancy loss (RPL) compared to full-term healthy controls. A total of 150 women that had experienced two or more RPLs and 180 healthy controls (two or more full-term pregnancies) were recruited, along with 50 product of conception (POC) samples from the corresponding RPL patients, and evaluated for miR-125a SNPs by the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP), which was confirmed by high resolution melting (HRM)/DNA sequencing. Additionally, the expression of miR-125a was quantified with q−PCR in the maternal plasma of 40 corresponding RPL patients against healthy controls. The frequency of variant genotype CC was significantly higher in RPL cases (19.3%) than controls (10.5%), with an odds ratio of >2 (p = 0.025). The expression levels of miR-125a were markedly decreased in RPL cases compared to healthy controls (p < 0.05). Variant genotype CC was found significantly more often in RPL cases than controls (0.34 vs. 0.20; p < 0.05).In this study, miR-125a rs12976445 C/T revealed that the homozygous CC genotype and C allele were associated with the risk of RPL and significant expression indicates that miR-125a has an important role in RPL etiopathogenesis.

miR-1273h-5p suppresses CXCL12 expression and inhibits gastric cancer cell invasion and metastasis

The aim of this study was to verify the biological function of miR-1273h-5p in gastric cancer (GC) and its underlying mechanisms. The differential expression of microRNAs between GC and tumor-adjacent normal tissues was detected using microarrays, miR-1273h-5p, and chemokine (C-X-C motif) ligand 12 (CXCL12) mRNA, and protein levels were evaluated using polymerase chain reaction and Western blotting methods, cell proliferation, apoptosis, migration, and invasion were determined by CCK-8, flow cytometry, and transwell assay. Compared to tumor-adjacent normal tissue and gastric epithelial mucosa cell line cells, miR-1273h-5p was significantly downregulated in tissues and cells of GC. The overexpression of miR-1273h-5p could inhibit cell proliferation, migration, invasion, and promote cell apoptosis; in contrast, inhibition of miR-1273h-5p expression could reverse this process. Moreover, a significant upregulation of CXCL12 was observed when the miR-1273h-5p was downregulated in GC cells. Additionally, miR-1273h-5p significantly reduces tumor volume and weight. Thus, this study suggests that miR-1273h-5p regulates cell proliferation, migration, invasion, and apoptosis during GC progression by directly binding to CXCL12 mRNA 3′-untranslational regions, which may be a novel diagnostic and therapeutic target in GC.

miR-125a-5p promotes gastric cancer growth and invasion by regulating the Hippo pathway

OBJECTIVE

This study was carried out to explore the potential involvement of miR-125a-5p in the oncogenic effects of EphA2, TAZ, and TEAD2 and the activity of the Hippo signaling pathway in gastric cancer progression.

METHODS

In vitro transfection of miR-125a-5p mimics or inhibitors, qRT-PCR, colony formation assays, and cell invasion assays were used to assess the effect of miR-125a-5p on the growth and invasion in gastric cancer (GC). Male nude mice bearing tumors derived from human GC cells were used for evaluating the effects of miR-125a-5p on tumor growth. Luciferase reporter assay, immunofluorescence, immunohistochemistry, qRT-PCR, and immunoblotting were performed to explore the role of miR-125a-5p in the epithelial-mesenchymal transition (EMT) and association among miR-125a-5p, EphA2, TAZ, and TEAD2 in GC cells.

RESULTS

MiR-125a-5p enhanced GC cell viability and invasion in vitro, whereas inhibition of miR-125a-5p using a specific inhibitor and antagomir suppressed cancer cell invasion and tumor growth. Moreover, inhibition of miR-125a-5p reversed EMT in vitro. miR-125a-5p upregulated the expression of EphA2, TAZ, and TEAD2, promoted TAZ nuclear translocation, and induced changes in the activity of the Hippo pathway by enhancing the expression of TAZ target genes. Finally, miR-125a-5p was overexpressed in late-stage GCs, and positive correlations were observed with its targets EphA2, TAZ, and TEAD2.

CONCLUSION

miR-125a-5p can promote GC growth and invasion by upregulating the expression of EphA2, TAZ, and TEAD2.

Molecular Landscapes of Gastric Pre-Neoplastic and Pre-Invasive Lesions

Gastric carcinoma (GC) represents one of the most common and most lethal malignancies worldwide. The histopathological characterization of GC precursor lesions has provided great knowledge about gastric carcinogenesis, with the consequent introduction of effective strategies of primary and secondary prevention. In recent years, a large amount of data about the molecular events in GC development is emerging, flanking the histomorphological descriptions. In this review, we describe the landscape of molecular alterations in gastric pre-invasive lesions with a glance at their potential use in the diagnostic and therapeutic decision-making process.

Clinicopathologic features and treatment advances in cancers with HER2 alterations

HER2 is one of the most important proteins of the epidermal growth factor receptor (EGFR) family, whose alterations include amplification, overexpression and gene mutation. Growing attention has been given to HER2 as a biomarker for prognosis, an indicator for treatment response and a target for new drugs. Tumors with HER2 alterations have been well studied in multiple locations as distinct entities for treatment, especially breast cancer, gastric cancer, lung cancer and colorectal cancer. These four cancers are the leading causes of cancer incidence and cancer-related death worldwide. The present study details the landscape of HER2 amplification/overexpression and mutations and gives an up-to-date analysis of current clinical trials in the four cancers mentioned above. Different HER2-altered cancers not only respond differently to HER2-targeting therapies but also display diverse survival outcomes. Even in the same type of cancer, HER2 amplification/overexpression differs from HER2 mutation in terms of clinicopathologic features and treatment strategies. As an emerging strategy in cancer treatment, immune checkpoint inhibitors demonstrate distinct outcomes in HER2-altered breast cancer, gastric cancer and lung cancer.

Vitamin D modulation and microRNAs in gastric cancer: prognostic and therapeutic role

Gastric adenocarcinoma arises after a complex interaction between the host and environmental factors. Tumor location and TNM are the tools that currently guide treatment decisions. Surgery is the only curative treatment, but relapse is common. After relapse or advanced staged disease survival is poor and systemic treatment has modestly improved survival. An association between sun exposure, vitamin D status and gastric cancer (GC) incidence and mortality has been reported. The molecular differences of the histological subtypes and the new molecular classifications account for the great heterogeneity of this disease and are the basis for the discovery of new therapeutic targets. New prognostic and predictive factors are essential and microRNAs (miRNAs) are endogenous small non-coding RNA molecules with a great potential for diagnosis, prognosis and treatment of cancer. There are hundreds of miRNAs with altered expression in tumor gastric tissue when compared to normal gastric tissue. Many of these miRNAs are associated with clinicopathological variables and survival in patients with GC. Furthermore, the expression of some of these miRNAs with prognostic importance in CG is influenced by vitamin D and others are mediators of some of the actions of this vitamin. This review aims to update the evidence on several miRNAs with prognostic value and therapeutic potential in GC, whose expression may be influenced by vitamin D or may regulate vitamin D signaling.

miRNAs Involved in Esophageal Carcinogenesis and miRNA-Related Therapeutic Perspectives in Esophageal Carcinoma

MicroRNAs (miRNAs) are small non-coding RNAs that play a pivotal role in many aspects of cell biology, including cancer development. Within esophageal cancer, miRNAs have been proved to be involved in all phases of carcinogenesis, from initiation to metastatic spread. Several miRNAs have been found to be dysregulated in esophageal premalignant lesions, namely Barrett’s esophagus, Barrett’s dysplasia, and squamous dysplasia. Furthermore, numerous studies have investigated the alteration in the expression levels of many oncomiRNAs and tumor suppressor miRNAs in esophageal squamous cell carcinoma and esophageal adenocarcinoma, thus proving how miRNAs are able modulate crucial regulatory pathways of cancer development. Considering these findings, miRNAs may have a role not only as a diagnostic and prognostic tool, but also as predictive biomarker of response to anti-cancer therapies and as potential therapeutic targets. This review aims to summarize several studies on the matter, focusing on the possible diagnostic–therapeutic implications.

HER2 Heterogeneity in Personalized Therapy of Gastro-Oesophageal Malignancies: An Overview by Different Methodologies

Human epidermal growth factor receptor-2 (HER2)-expression gastro-oesophageal adenocarcinomas (GEA) gained interest as an important target for therapy with trastuzumab. In the current review, we focused the current knowledge on HER2 status in dysplastic and neoplastic gastric conditions, analyzing the methodological procedures to identify HER2 expression/amplification, as well as the proposed scoring recommendations. One of the most relevant questions to evaluate the useful impact of HER2 status on therapeutic choice in GEAs is represented by the significant heterogeneity of HER2 protein and gene expression that may affect the targeted treatment selection. Future development of biotechnology will continue to evolve in order to offer more powerful detection systems for the assessment of HER2 status. Finally, liquid biopsy as well as mutation/amplification of several additional genes may furnish an early detection of secondary HER2 resistance mechanisms in GEAs with a better monitoring of the treatment response.

Pathological Tumor Regression Grade Classifications in Gastrointestinal Cancers: Role on Patients' Prognosis

Preoperative chemotherapy or combined radiotherapy and chemotherapy (CRT), followed by surgery, represents the standard approach for locally advanced esophageal, gastric, and rectal carcinomas. To adequately evaluate the effects of neoadjuvant CRT in the resection specimens, several histopathologic tumor regression grade (TRG) scoring systems have been introduced into clinical practice. The primary goal of these TRG systems relies on a correct prognostic stratification of patients in the attempt to help clinical decision-making and influence surgical strategies, postoperative adjuvant therapies, and surveillance intensity. However, most TRG systems suffer from poor reproducibility and low interobserver concordance rates. Many efforts have been made in the identification of alternative, robust, simple, and universally accepted TRG scoring systems, which would help in the comparison of different treatment strategies and in the standardization of multimodal therapies. The aim of this review is to analyze the most commonly used TRG systems in gastrointestinal cancers highlighting their pitfalls and usefulness, depending on the tumor type.

HER2 Regulates Cancer Stem Cell Activities via the Wnt Signaling Pathway in Gastric Cancer Cells

INTRODUCTION

Human epidermal growth factor 2 (HER2) gene overexpression in breast carcinoma cell lines has been shown to drive mammary carcinogenesis and tumor growth and invasion through its effects on mammary stem cells.

OBJECTIVE

Therefore, we investigated the mechanism by which HER2 regulates cancer stem cell (CSC) activity in gastric cancer cells.

METHODS

HER2 was transfected into MKN28 gastric cancer cells, and its role in regulating CSC activity was determined by characterizing the HER2-overexpressing cells.

RESULTS

The sphere formation assay revealed that the sphere sizes and frequency of sphere formation were significantly greater for the HER2-overexpressing cells than for the MKN28 control cells. The CSC markers Oct-4 and BMI1 were more highly expressed in the HER2-overexpressing cells, as were the EMT markers. This was accompanied by a significant enhancement in cellular invasion of the Matrigel and migration. The E-cadherin level was significantly downregulated, and the mesenchymal marker Snail upregulated, in the HER2-transfected cells. HER2 overexpression activated the well-characterized CSC-associated Wnt/β-catenin signaling pathway, as shown by the luciferase assay. After treatment of these cells with the Wnt signal inhibitor PRI-724, the BMI1 and Oct-4 levels were decreased for 24 h and Snail was also downregulated. Immunofluorescence staining revealed the significant restoration of E-cadherin levels in the HER2-transfected cells after PRI-724 treatment.

CONCLUSIONS

These results established a role for HER2 in regulating gastric CSC activity, with Wnt/β-catenin signaling being mediated via a HER2-dependent pathway. In summary, HER2-overexpressing gastric cancer cells exhibited increased stemness and invasiveness and were regulated by Wnt/β-catenin signaling.

Identification of microRNAs as novel biomarkers for esophageal squamous cell carcinoma: a study based on The Cancer Genome Atlas (TCGA) and bioinformatics

BACKGROUND

MicroRNAs (miRNAs) have played important roles in the regulation of gene expression in many cancers, but their roles in esophageal squamous cell carcinoma (ESCC) are still unclear. The aim of this study was to determine the potential ESCC-specific key miRNAs from a large sample dataset in The Cancer Genome Atlas (TCGA).

METHODS

Integrative bioinformatics analysis was used to identify key ESCC-specific miRNAs related to the ESCC patients' tumor histological grade and lymphatic metastasis from TCGA. Next, these key miRNA potential gene regulatory functions and relationships with ESCC patients' clinical characteristics and overall survival were analyzed. Finally, three key miRNAs were selected randomly and quantificational real-time polymerase chain reaction (qRT-PCR) was used to validate in 51 newly diagnosed ESCC patients' tissues samples (collected from Nov. 2017 to Feb. 2019, in Wuwei, China) whether the bioinformatics analyses results were reliable and valid. Two-tailed Student's t test, Pearson Chi-squared test and Kaplan-Meier survival analysis were used in this study.

RESULTS

Thirty-five ESCC-specific miRNAs from TCGA database were investigated (fold-change > 2.0, P < 0.05), and 28 participated in the miRNAs-mRNAs co-expression network construction, while 17 were related with ESCC patients' tumor histological grade, TNM stage, and lymphatic metastasis (P < 0.05). Meanwhile, six miRNAs (including miR-200b-3p, miR-31-5p, miR-15b-5p, miR-141-3p, miR-135b-5p, and miR-195-5p) were correlated with overall survival of ESCC patients (log-rank, P < 0.05). MiR-135b-5p, miR-15b-5p, and miR-195-5p were selected for verification of the expression levels in 51 ESCC patients' tissue samples by using qRT-PCR. We found that the fold-changes between qRT-PCR and TCGA were completely consistent. The results also suggested that miR-135b-5p, miR-15b-5p, and miR-195-5p were significantly correlated with tumor differentiation degrees (P < 0.05), miR-195-5p was significantly correlated with tumor TNM stage (P < 0.05), and miR-135b-5p was significantly correlated with lymph-node metastasis (P < 0.05). MiR-135b-5p, miR-15b-5p, and miR-195-5p expression levels, ESCC patient clinical features association analysis results and the aforementioned TCGA bioinformatics analyses were similar.

CONCLUSION

This study identified key ESCC-related miRNAs. The key miRNAs are worthy of further investigation as potential novel biomarkers for diagnosis, classification, and prognosis of ESCC.

Low expression of miR-125a-5p is associated with poor prognosis in patients with gastric cancer

microRNAs (miRs) serve critical roles in tumor progression. Low expression of miR-125a in gastric carcinoma (GC) may promote tumor development. In the present study, low expression of miR-125a was confirmed in cancer tissues using The Cancer Genome Atlas database. Additionally, the expression and clinical significance of miR-125a-5p was investigated using reverse transcription-quantitative PCR in 150 cases of GC. The results of the present study demonstrated that the level of miR-125a-5p expression was decreased in GC biopsies compared with that in matched adjacent normal tissues. Low expression of miR-125a-5p was associated with increased tumor diameter, high Ki67 expression and poor overall survival of patients with GC. Multivariate survival analysis demonstrated that low miR-125a-5p expression may be used as an independent prognostic factor for patients with GC. However, no effects on the cell viability in a Cell Counting kit-8 assay, and cell migration and invasion in Transwell assays were detected in response to treatment using miR-125a-5p mimics or inhibitors in vitro. Therefore, the results of the present study provide evidence that low expression of miR-125a-5p may be associated with a poor prognosis, suggesting its value as a tumor biomarker for patients with GC.

The functional mechanism of miR-125b in gastric cancer and its effect on the chemosensitivity of cisplatin

Numerous studies have shown drug resistance of gastric cancer cells could be modulated by abnormal expression of microRNAs. Cisplatin (DDP) is one of the most commonly used drugs for chemotherapy of gastric cancer. In this study, the potential function of miR-125b on DDP resistance in gastric cancer cells was investigated. Sixteen miRNAs significantly differential expressed in gastric tumor tissues and adjacent tissues were characterized and their corresponding putative target genes were also screened. MiR-125b was selected as our focus for its evident down-regulated expression among candidate genes. Real-time polymerase chain reaction assay indicated that miR-125b was significantly down-regulated in gastric cancer tissues and various cell lines. HER2 was identified as a target gene of miR-125b by dual luciferase reporter assay and Western blot. Moreover, miR-125b overexpression inhibited not only the proliferation, migration, and invasion abilities of HGC-27 and MGC-803 cells, but also in vivo tumor growth of MGC-803 cells by an intratumoral delivery approach. Notably, we observed up-regulated miR-125b contributed to the chemosensitivity of DDP in HGC-27 and MGC-803 cells at different concentrations and also possessed sensibilization for DDP at different times. MiR-125b expression was found to be related to lymph node metastasis, HER2 expression and overall survival of patients through correlation analysis. Collectively, these results indicate miR-125b may regulate DDP resistance as a promising therapeutic target for gastric cancer treatment in future.

HDAC2 and HDAC5 Up-Regulations Modulate Survivin and miR-125a-5p Expressions and Promote Hormone Therapy Resistance in Estrogen Receptor Positive Breast Cancer Cells

Intrinsic or acquired resistance to hormone therapy is frequently reported in estrogen receptor positive (ER⁺) breast cancer patients. Even though dysregulations of histone deacetylases (HDACs) are known to promote cancer cells survival, the role of different HDACs in the induction of hormone therapy resistance in ER⁺ breast cancer remains unclear. Survivin is a well-known pro-tumor survival molecule and miR-125a-5p is a recently discovered tumor suppressor. In this study, we found that ER⁺, hormone-independent, tamoxifen-resistant MCF7-TamC3 cells exhibit increased expression of HDAC2, HDAC5, and survivin, but show decreased expression of miR-125a-5p, as compared to the parental tamoxifen-sensitive MCF7 breast cancer cells. Molecular down-regulations of HDAC2, HDAC5, and survivin, and ectopic over-expression of miR-125a-5p, increased the sensitivity of MCF7-TamC3 cells to estrogen deprivation and restored the sensitivity to tamoxifen. The same treatments also further increased the sensitivity to estrogen-deprivation in the ER⁺ hormone-dependent ZR-75-1 breast cancer cells in vitro. Kaplan-Meier analysis and receiver operating characteristic curve analysis of expression cohorts of breast tumor showed that high HDAC2 and survivin, and low miR-125a-5p, expression levels correlate with poor relapse-free survival in endocrine therapy and tamoxifen-treated ER⁺ breast cancer patients. Further molecular analysis revealed that HDAC2 and HDAC5 positively modulates the expression of survivin, and negatively regulates the expression miR-125a-5p, in ER⁺ MCF7, MCF7-TamC3, and ZR-75-1 breast cancer cells. These findings indicate that dysregulations of HDAC2 and HDAC5 promote the development of hormone independency and tamoxifen resistance in ERC breast cancer cells in part through expression regulation of survivin and miR-125a-5p.

Fibroblast growth factor receptor 2 expression, but not its genetic amplification, is associated with tumor growth and worse survival in esophagogastric junction adenocarcinoma

Background

Fibroblast growth factor receptor 2 (FGFR2) genetic alterations lead to tumor cell proliferation in various types of cancer. We hypothesized that FGFR2 amplification is associated with FGFR2 expression, resulting in tumor growth and poorer outcome in esophagogastric junction (EGJ) adenocarcinoma.

Patients and Methods

A total of 176 consecutive chemo-naive patients with EGJ adenocarcinoma were enrolled from two academic institutions. FGFR2 amplification was examined by real-time PCR (N = 140) and FGFR2 expression with immunohistochemical staining (N = 176), and compared against clinicopathological factors and patient outcomes. The effects of FGFR2 inhibition or overexpression on cell proliferation, cell cycle, and apoptosis assays were investigated in EGJ adenocarcinoma cell lines. Downstream FGFR2, AKT and ERK were also examined.

Results

Based on the correlation between FGFR2 levels and FGFR2 overexpression in vitro, FGFR2 amplification was defined as copy number > 3.0. In clinical samples, FGFR2 amplification and FGFR2 IHC expression were 15% and 61%, respectively. Although these two statuses were significantly correlated (P < 0.05), only FGFR2 IHC expression was significantly associated with tumor depth (multivariate P < 0.001) and overall survival of patients (univariate P = 0.007). Supporting these findings, FGFR2 overexpression was associated with tumor cell proliferation, cell cycle progression, and anti-apoptosis. Selective inhibition of FGFR2 sufficiently suppressed tumor cell proliferation through de-phosphorylation of AKT and ERK.

Conclusions

FGFR2 amplification was significantly associated with FGFR2 expression. FGFR2 expression (but not FGFR2 amplification) was associated with tumor growth and patient outcomes. Our findings support FGFR2 as a novel therapeutic target for EGJ adenocarcinoma.

miR-125b-5p functions as a tumor suppressor gene partially by regulating HMGA2 in esophageal squamous cell carcinoma

MicroRNAs (miRNAs) play important roles in the progression of human cancer including esophageal squamous cell carcinoma (ESCC). Although previous reports showed that miR-125b-5p was down-regulated in ESCC, the roles and mechanisms of loss of function of miR-125b-5p in ESCC were still unknown. Using microRNA microarray and GEO datasets, we found and confirmed that miR-125b-5p was down-regulated in ESCC tissues. In-vitro assays showed that ectopic miR-125b-5p expression repressed cell proliferation, migration and invasion, and induced cell senescence. We also found that miR-125b-5p reduced the expressions of cell cycle regulatory genes including CCNA2, CCND1 and CCNE1, and regulated the markers of epithelial to mesenchymal transition (EMT) including E-cadherin, N-cadherin and EMT associated transcription factor Slug, and also decreased the MMPs including MMP2, MMP7 and MMP13. Furthermore, the candidate target gene HMGA2 was negatively regulated by miR-125b-5p both in mRNA and protein levels. Importantly, knockdown of HMGA2 partially phenocopied the effects of miR-125b-5p overexpression on cell cycle regulators and EMT markers. In conclusion, our results suggested that overexpression of miR-125b-5p inhibited cell proliferation, migration and invasion partially by down-regulating HMGA2 in ESCC.

Oncogenic long noncoding RNA landscape in breast cancer

Background

Few long noncoding RNAs (lncRNAs) that act as oncogenic genes in breast cancer have been identified.

Methods

Oncogenic lncRNAs associated with tumourigenesis and worse survival outcomes were examined and validated in Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA), respectively. Then, the potential biological functions and expression regulation of these lncRNAs were studied via bioinformatics and genome data analysis. Moreover, progressive breast cancer subtype-specific lncRNAs were investigated via high-throughput sequencing in our cohort and TCGA validation. To elucidate the mechanisms of the regulation of these lncRNAs, genomic alterations from the TCGA, Broad, Sanger and BCCRC data, as well as epigenetic modifications from GEO data, were then applied and examined to meet this objective. Finally, cell proliferation assays, flow cytometry analyses and TUNEL assays were applied to validate the oncogenic roles of these lncRNAs in vitro.

Results

A cluster of oncogenic lncRNAs that was upregulated in breast cancer tissue and was associated with worse survival outcomes was identified. These oncogenic lncRNAs are involved in regulating immune system activation and the TGF-beta and Jak-STAT signalling pathways. Moreover, TINCR, LINC00511, and PPP1R26-AS1 were identified as subtype-specific lncRNAs associated with HER-2, triple-negative and luminal B subtypes of breast cancer, respectively. The up-regulation of these oncogenic lncRNAs is mainly caused by gene amplification in the genome in breast cancer and other solid tumours. Finally, the knockdown of TINCR, DSCAM-AS1 or HOTAIR inhibited breast cancer cell proliferation, increased apoptosis and inhibited cell cycle progression in vitro.

Conclusions

These findings enhance the landscape of known oncogenic lncRNAs in breast cancer and provide insights into their roles. This understanding may potentially aid in the comprehensive management of breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0696-6) contains supplementary material, which is available to authorized users.

Upregulation of miR-125b is associated with poor prognosis and trastuzumab resistance in HER2-positive gastric cancer

Gastric cancer is one of the most common types of human cancer associated with a poor prognosis. MicroRNAs (miRs), a class of non-coding RNAs that are 18–25 nucleotides in length, act as key regulators in gene expression, and have been implicated in various human cancer types. miR-125b has been implicated in the malignant progression of gastric cancer. However, the association between miR-125b expression, clinicopathological characteristics and trastuzumab resistance in human epidermal growth factor receptor 2 (HER2)-positive gastric cancer remains unclear. In the current study, in situ hybridization data demonstrated that 81.8% (108/132) of gastric cancer tissues exhibited positive expression of miR-125b, while only 26.3% (10/38) of non-tumor gastric tissues were miR-125b-positive. Reverse transcription-quantitative polymerase chain reaction data indicated that the expression level of miR-125b was markedly increased in gastric cancer tissues compared with non-cancerous gastric tissues. Furthermore, the miR-125b level was significantly associated with tumor (T) stage, lymph node metastasis, distant metastasis and TNM stage of gastric cancer (P<0.05). Increased miR-125b expression predicated poor prognosis in patients with gastric cancer. For HER2-positive gastric cancer, the upregulation of miR-125b expression was significantly associated with advanced malignant progression, as well as a poor prognosis (P<0.05). Furthermore, data from the present study indicated that the increased miR-125b level was significantly associated with trastuzumab resistance in HER2-positive gastric cancer (P<0.05). Therefore, the current study suggests that miR-125b may become a potential biomarker for predicting prognoses and clinical outcomes in patients with HER2-positive gastric cancer that receive trastuzumab treatment.

Elevated microRNA-125b levels predict a worse prognosis in HER2-positive breast cancer patients

Breast cancer, the second most common cancer worldwide, is the leading cause of cancer-associated mortality in women, accounting for ~15% of all cancer-associated mortalities in women. The development, local invasion and metastasis of breast cancer are associated with the dysregulation and mutation of numerous genes and epigenetic mechanisms, including coding RNA and non-coding RNA, such as microRNAs (miRs/miRNAs). Previous studies have shown a dual-faced role of miR-125b in breast cancer. In the present study, a total of 221 paraffin-embedded breast cancer and 49 paraffin-embedded non-cancerous breast tissue samples were collected. In situ hybridization was used to analyze the expression of miR-125b in the breast cancer tissues. Spearman's rank correlation analysis was used to analyze the expression correlation between miR-125b and human epidermal growth factor 2 (HER2). The overall survival estimates over time were calculated using the Kaplan-Meier method with log-rank test. It was found that miR-125b expression was significantly increased in the breast cancer tissues compared with that in the non-cancerous tissues, and high miR-125b expression indicated a poor prognosis in the breast cancer patients. In addition, miR-125b expression was positively correlated with HER2, but not with progesterone receptor and estrogen receptor. Notably, high miR-125b expression was significantly correlated with tumor size and Tumor-Node-Metastasis stage in the HER2-positive breast cancer patients, along with a poor prognosis. The present study provides clinical data to confirm the oncogenic potential of miR-125b, particularly in HER2-positive human breast cancer. Thus, identification of miR-125b may be a potential molecular biomarker for the prediction of clinical outcomes in breast cancer patients, particularly HER2-positive cases that will receive paclitaxel-based neoadjuvant chemotherapy.

How interacting pathways are regulated by miRNAs in breast cancer subtypes

BACKGROUND

An important challenge in cancer biology is to understand the complex aspects of the disease. It is increasingly evident that genes are not isolated from each other and the comprehension of how different genes are related to each other could explain biological mechanisms causing diseases. Biological pathways are important tools to reveal gene interaction and reduce the large number of genes to be studied by partitioning it into smaller paths. Furthermore, recent scientific evidence has proven that a combination of pathways, instead than a single element of the pathway or a single pathway, could be responsible for pathological changes in a cell.

RESULTS

In this paper we develop a new method that can reveal miRNAs able to regulate, in a coordinated way, networks of gene pathways. We applied the method to subtypes of breast cancer. The basic idea is the identification of pathways significantly enriched with differentially expressed genes among the different breast cancer subtypes and normal tissue. Looking at the pairs of pathways that were found to be functionally related, we created a network of dependent pathways and we focused on identifying miRNAs that could act as miRNA drivers in a coordinated regulation process.

CONCLUSIONS

Our approach enables miRNAs identification that could have an important role in the development of breast cancer.

Integrated miRNA profiling and bioinformatics analyses reveal potential causative miRNAs in gastric adenocarcinoma

Gastric cancer (GC) is one of the leading causes of cancer-related deaths throughout China and worldwide. The discovery of microRNAs (miRNAs) has provided a new opportunity for developing diagnostic biomarkers and effective therapeutic targets in GC. By performing microarray analyses of benign and malignant gastric epithelial cell lines (HFE145, NCI-N87, MKN28, RF1, KATO III and RF48), 16 significantly dysregulated miRNAs were found. 11 of these were validated by real-time qRT-PCR. Based on miRWalk online database scans, 703 potential mRNA targets of the 16 miRNAs were identified. Bioinformatic analyses suggested that these dysregulated miRNAs and their predicted targets were principally involved in tumor pathogenesis, MAPK signaling, and apoptosis. Finally, miRNA-gene network analyses identified miRNA-125b as a crucial miRNA in GC development. Taken together, these results develop a comprehensive expression and functional profile of differentially expressed miRNAs related to gastric oncogenesis. This profile may serve as a potential tool for biomarker and therapeutic target identification in GC patients.

HER2 heterogeneity in gastric/gastroesophageal cancers: From benchside to practice

HER2 is overexpressed in approximately 10%-20% of gastric and gastroesophageal junction carcinomas. In these types of cancer, accurate assessment of HER2 status is mandatory, for selecting patients who may benefit from targeted therapies with anti-HER2 drugs such as Trastuzumab. This manuscript focuses on HER2 in gastric carcinogenesis, on optimal evaluation of HER2 and on the possible causes which may contribute to inaccurate HER2 evaluation. Similarly to breast cancer HER2 evaluation, standardization of HER2 testing in gastric cancer is necessary in diagnostic practice. The three principle aspects which require consideration are: (1) the choice of sample with regards to cancer morphology - intestinal vs diffuse areas; (2) the choice of scoring criteria - use of HER2 scoring criteria specific for gastric cancer; and (3) the choice of HER2 evaluation methods - use of an algorithm in which both immunohistochemistry and in situ hybridization play a role. Problematic issues include: (1) pre-analytic variables with particular emphasis on fixation; (2) recommended methodology for HER2 assessment (immunohistochemistry vs in situ hybridization); (3) HER2 heterogeneity both within the primary tumor and between primary tumor and metastases; (4) reliability of biopsies in HER 2 evaluation; and (5) quantity of sample (FFPE blocks from surgical specimens or endoscopic biopsies) necessary for an adequate assessment.

Preclinical evidence of multiple mechanisms underlying trastuzumab resistance in gastric cancer

HER2-positive advanced gastric cancer patients frequently develop resistance to trastuzumab through mechanisms still poorly understood. In breast cancer, other members of the HER-family are known to be involved in trastuzumab-resistance, as is overexpression of the scaffold protein IQGAP1. In the present work, we investigated acquired resistance to trastuzumab in gastric cancer experimental models. Trastuzumab-resistant (HR) subclones derived from 3 HER2-overexpressing gastric cancer cells were generated and characterized for alterations in HER2-signaling mechanisms by next-generation sequencing, immunohistochemical, western blot and qRT-PCR techniques, and molecular modeling analysis. All subclones showed a reduced growth rate with respect to parental cell lines but each had a different resistance mechanism. In NCI N87 HR cells, characterized by a marked increase in HER2-signaling pathways with respect to the parental cell line, trastuzumab sensitivity was restored when IQGAP1 expression was silenced. AKG HR subclone showed higher HER3 protein expression than the parental line. High nuclear HER4 levels were observed in KKP HR cells. In conclusion, our study revealed that high IQGAP1 expression leads to resistance to trastuzumab in gastric cancer. Furthermore, 2 new mutations of the HER2 gene that may be involved in acquired resistance were identified in AKG HR and KKP HR subclones.

MiR-125a promotes paclitaxel sensitivity in cervical cancer through altering STAT3 expression

Cervical cancer (CC) is one of the most common malignancies in women. Paclitaxel is the front-line chemotherapeutic agent for treating CC. However, its therapeutic efficacy is limited because of chemoresistance, the mechanism of which remains poorly understood. Here, we used microRNA (miRNA) arrays to compare miRNA expression levels in the CC cell lines, HeLa and CaSki, with their paclitaxel resistance counterparts, HeLa/PR and CaSki/PR. We demonstrate that miR-125a was one of most significantly downregulated miRNAs in paclitaxel-resistant cells, which also acquired cisplatin resistance. And that the upregulation of miR-125a sensitized HeLa/PR and CaSki/PR cells to paclitaxel both in vitro and in vivo and to cisplatin in vitro. Moreover, we determined that miR-125a increased paclitaxel and cisplatin sensitivity by downregulating STAT3. MiR-125a enhanced paclitaxel and cisplatin sensitivity by promoting chemotherapy-induced apoptosis. Clinically, miR-125a expression was associated with an increased responsiveness to paclitaxel combined with cisplatin and a more favorable outcome. These data indicate that miR-125a may be a useful method to enable treatment of chemoresistant CC and may also provide a biomarker for predicting paclitaxel and cisplatin responsiveness in CC.

Let-7c down-regulation in Helicobacter pylori-related gastric carcinogenesis

Aberrant let-7c microRNA (miRNA) expression has been observed in Helicobacter pylori-related gastric cancer (GC) but fragmentary information is available on the let-7c dysregulation occurring with each phenotypic change involved in gastric carcinogenesis. Let-7c expression was assessed (qRT-PCR) in a series of 175 gastric biopsy samples representative of the whole spectrum of phenotypic changes involved in H. pylori-related gastric oncogenesis including: i) normal gastric mucosa, as obtained from dyspeptic controls (40 biopsy samples); ii) non-atrophic gastritis (40 samples); iii) atrophic-metaplastic gastritis (35 samples); iv) intra-epithelial neoplasia (30 samples); v) GC (30 samples). Let-7c expression was also tested in 20 biopsy samples obtained from 10 patients before and after H. pylori eradication therapy (median follow-up: 10 weeks; range: 7-14). The results obtained were further validated by in situ hybridization on multiple tissue specimens obtained from 5 surgically treated H. pylori-related GCs. The study also included 40 oxyntic biopsy samples obtained from serologically/histologically confirmed autoimmune gastritis (AIG: 20 corpus-restricted, non-atrophic; 20 corpus-restricted, atrophic-metaplastic). Let-7c expression dropped from non-atrophic gastritis to atrophic-metaplastic gastritis, intra-epithelial neoplasia, and invasive GC (p<0.001). It rose again significantly following H. pylori eradication (p=0.009). As in the H. pylori model, AIG also featured a significant let-7c down-regulation (p<0.001). The earliest phases of the two pathways to gastric oncogenesis (H. pylori-environmental and autoimmune host-related) are characterized by similar let-7c dysregulations. In H. pylori infection, let-7c down-regulation regresses after the bacterium's eradication, while it progresses significantly with the increasing severity of the histological lesions.

A Zbtb7a proto-oncogene as a novel target for miR-125a

In our previous study, we showed that miR-125a directly targeted a WT1 oncogene, which was overexpressed in leukemia and various kinds of solid tumors including lung, breast, gastric, and colon cancers, and brain tumors and was deeply involved in leukemogenesis and tumorigenesis and that miR-125a knockout mice overexpressed WT1 and developed myeloproliferative disease. It had been also reported that miR-125a is downregulated in leukemia and various types of solid tumors such as lung cancers, suggesting its tumor suppressor function. Therefore, it is important to elucidate what is target(s) of miR-125a for understandings of such functions although few target genes for it are known. In the present study, Zbtb7a oncogene was identified as a potential target for miR-125a by gene expression profiling in miR-125a knockout mice combined with bioinformatics target prediction. EGFP-3'UTR reporter assay showed that miR-125a suppressed Zbtb7a expression through its direct binding to the Zbtb7a-3'UTR. Zbtb7a knockdown by siRNA suppressed cell proliferation and induced G1 cell cycle arrest and apoptosis in lung cancer cells. Furthermore, miR-125a expression showed a negative correlation with Zbtb7a expression in non-small cell lung cancer tissues. The present study showed for the first time that Zbtb7a was a direct target for miR-125a and was involved in cell cycle progression and apoptosis of lung cancer cells. These results also demonstrated that deregulation of miR-125a-Zbtb7a signaling was associated with the development and progression of lung cancer. © 2015 Wiley Periodicals, Inc.

miR-125b Suppresses Proliferation and Invasion by Targeting MCL1 in Gastric Cancer

Understanding the molecular mechanisms underlying gastric cancer progression contributes to the development of novel targeted therapies. In this study, we found that the expression levels of miR-125b were strongly downregulated in gastric cancer and associated with clinical stage and the presence of lymph node metastases. Additionally, miR-125b could independently predict OS and DFS in gastric cancer. We further found that upregulation of miR-125b inhibited the proliferation and metastasis of gastric cancer cells in vitro and in vivo. miR-125b elicits these responses by directly targeting MCL1 (myeloid cell leukemia 1), which results in a marked reduction in MCL1 expression. Transfection of miR-125b sensitizes gastric cancer cells to 5-FU-induced apoptosis. By understanding the function and molecular mechanisms of miR-125b in gastric cancer, we may learn that miR-125b has the therapeutic potential to suppress gastric cancer progression and increase drug sensitivity to gastric cancer.

HER2 Status in Premalignant, Early, and Advanced Neoplastic Lesions of the Stomach

Objectives. HER2 expression in gastric cancer (GC) has received attention as a potential target for therapy with Trastuzumab. We reviewed the current knowledge on HER2 status in premalignant gastric lesions and in early (EGC) and advanced (AGC) GC to discuss the possible pathogenetic and prognostic roles of HER2 overexpression in GC. Results. HER2 overexpression was documented in gastric low-grade (LG) and high-grade intraepithelial neoplasia (HG-IEN), with higher frequency in gastric type dysplasia. HER2 overexpression was significantly associated with disease recurrence and poor prognosis in EGC representing an independent risk factor for lymph node metastases. HER2 overexpression was more frequent in AGC characterized by high grade, advanced stage, and high Ki-67 labeling index. The discordance in HER2 status was evidenced between primitive GC and synchronous or metachronous metastases. Conclusions. HER2 overexpression in premalignant gastric lesions suggests its potential involvement in the early steps of gastric carcinogenesis. The assessment of HER2 status in EGC may be helpful for the identification of patients who are at low risk for developing nodal metastases. Finally, the possible discordance in HER2 status between primary GC and its synchronous metastases support routine assessment of HER2 both in the primary GC and in its metastatic lesions.

MicroRNAs: New Biomarkers for Diagnosis, Prognosis, Therapy Prediction and Therapeutic Tools for Breast Cancer

Dysregulation of microRNAs (miRNAs) is involved in the initiation and progression of several human cancers, including breast cancer (BC), as strong evidence has been found that miRNAs can act as oncogenes or tumor suppressor genes. This review presents the state of the art on the role of miRNAs in the diagnosis, prognosis, and therapy of BC. Based on the results obtained in the last decade, some miRNAs are emerging as biomarkers of BC for diagnosis (i.e., miR-9, miR-10b, and miR-17-5p), prognosis (i.e., miR-148a and miR-335), and prediction of therapeutic outcomes (i.e., miR-30c, miR-187, and miR-339-5p) and have important roles in the control of BC hallmark functions such as invasion, metastasis, proliferation, resting death, apoptosis, and genomic instability. Other miRNAs are of interest as new, easily accessible, affordable, non-invasive tools for the personalized management of patients with BC because they are circulating in body fluids (e.g., miR-155 and miR-210). In particular, circulating multiple miRNA profiles are showing better diagnostic and prognostic performance as well as better sensitivity than individual miRNAs in BC. New miRNA-based drugs are also promising therapy for BC (e.g., miR-9, miR-21, miR34a, miR145, and miR150), and other miRNAs are showing a fundamental role in modulation of the response to other non-miRNA treatments, being able to increase their efficacy (e.g., miR-21, miR34a, miR195, miR200c, and miR203 in combination with chemotherapy).

Minimum biopsy set for HER2 evaluation in gastric and gastro-esophageal junction cancer

BACKGROUND AND STUDY AIMS

The HER2 status of small endoscopic biopsies is important for predicting the eligibility of patients with metastatic HER2-positive gastric cancer or gastro-esophageal junction (GEJ) cancer for anti-HER2 therapy approved by the U.S. Food and Drug Administration. The aim of this study was to identify the minimum biopsy set required to evaluate the HER2 status with confidence.

PATIENTS AND METHODS

A total of 103 consecutive patients with resected gastric cancer or GEJ cancer were retrospectively selected; 2 formalin-fixed, paraffin-embedded samples of each surgical specimen and all paired endoscopic biopsies were analyzed for HER2 status with both immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) methods. A total of 10 virtual biopsies were constructed by selecting areas 2.6 mm in diameter on the luminal side of digitalized slides obtained from the surgical specimens. The results of evaluating HER2 status in virtual biopsies, slides containing complete surgical specimens, and endoscopic biopsies were compared. The resulting minimum biopsy set was applied to the endoscopic biopsy series for validation.

RESULTS

A biopsy set containing a minimum of 5 samples was identified as the most accurate in predicting HER2 status (sensitivity, 92 %; specificity, 97 %). In only 3 of the 103 cases (2.9 %) did a comparison of the HER2 evaluation of virtual biopsies and that of entire slides show inconsistent results. Overall agreement between the endoscopic biopsies and surgical samples for HER2 IHC status increased from 78.4 % to 92.3 % when biopsy sets containing 4 or fewer samples were compared with biopsy sets containing 5 or more samples.

CONCLUSIONS

Although the recommendations suggest that 8 to 10 biopsies are necessary, the results show that a minimum set of 5 biopsies may be sufficient for reliable HER2 assessment in gastric cancer and GEJ cancer. However, endoscopists should be aware that a smaller sample size may be less accurate in selecting patients eligible for anti-HER2 therapy.

Current perspectives of mi-RNA in oesophageal adenocarcinoma: Roles in predicting carcinogenesis, progression and values in clinical management

Aberrant expressions of micro-ribonucleic acids (miRs) are closely associated with the pathogenesis in many human cancers. In oesophageal adenocarcinomas, altered expressions of different sets of miRs are noted to be associated with the development of adenocarcinoma from Barrett's oesophagus. In different studies, miRs such as miR-192, miR-196 and miR-21 were frequently noted to up-regulated whereas miR-203, miR-205 and miR-let-7 were commonly down-regulated during the development of Barrett's oesophagus to oesophageal adenocarcinoma. In addition, changes in the expression of miRs are associated with the predication of metastasis, prognosis and response to chemo-radiation in the patients with oesophageal adenocarcinoma. Experimental studies in manipulating the miRs in cancer cell lines could provide hints for therapeutics for the cancer. However, the number of studies reported on these aspects of oesophageal adenocarcinoma was limited and the miRs noted needed to be confirmed by additional studies. Overall, the mechanisms of involvements of miRs in pathogenesis and progression of oesophageal adenocarcinoma are complex. Although miRs have the potential to act as prognostic and clinical biomarkers for cancer therapy in oesophageal adenocarcinoma, more works in larger populations and clinical trials are needed to validate these clinical implications.

The p53/microRNA connection in gastrointestinal cancer

The protein encoded by the TP53 gene is one of the most important suppressors of tumor formation, which is also frequently inactivated in gastrointestinal cancer. MicroRNAs (miRNAs) are small noncoding RNAs that inhibit translation and/or promote degradation of their target messenger RNAs. In recent years, several miRNAs have been identified as mediators and regulators of p53’s tumor suppressing functions. p53 induces expression and/or maturation of several miRNAs, which leads to the repression of critical effector proteins. Furthermore, certain miRNAs regulate the expression and activity of p53 through direct repression of p53 or its regulators. Experimental findings indicate that miRNAs are important components of the p53 network. In addition, the frequent genetic and epigenetic alterations of p53-regulated miRNAs in tumors indicate that they play an important role in cancer initiation and/or progression. Therefore, p53-regulated miRNAs may represent attractive diagnostic and/or prognostic biomarkers. Moreover, restoration of p53-induced miRNAs results in suppression of tumor growth and metastasis in mouse models of cancer. Thus, miRNA-based therapeutics may represent a feasible strategy for future cancer treatment. Here we summarize the current published state-of-the-art on the role of the p53-miRNA connection in gastrointestinal cancer.

Reduced miR-125a-5p expression is associated with gastric carcinogenesis through the targeting of E2F3

Emerging evidence suggests that altered expression of microRNAs (miRNAs) is involved in cancer progression. However, the role of miR-125a-5p in gastric carcinogenesis remains unknown. Quantitative real-time PCR analysis revealed that the expression of miR-125a-5p was significantly decreased in >80% of gastric cancer tissues compared with their adjacent non-tumor tissues, and was markedly reduced in ~95% of intestinal-type gastric cancer tissues. The downregulated miR-125a-5p was significantly associated with gastric cancer metastasis. Ectopic expression of miR-125a-5p substantially inhibited the proliferation, migration and invasion activities of gastric cancer cells. Furthermore, forced expression of miR-125a-5p repressed the activity of a luciferase reporter carrying the 3'-untranslated (3'-UTR) region of E2F3, which was eliminated by mutation of the predicted miR-125a-binding site, indicating that E2F3 may be a potential target gene of miR-125a-5p. These data suggest that by targeting E2F3, miR-125a-5p may be important as a potential tumor suppressor gene in gastric carcinogenesis.

Molecular mechanisms underlying the role of microRNAs in the chemoresistance of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an extremely severe disease where the mortality and incidence rates are almost identical. This is mainly due to late diagnosis and limited response to current treatments. The tumor macroenvironment/microenvironment have been frequently reported as the major contributors to chemoresistance in PDAC, preventing the drugs from reaching their intended site of action (i.e., the malignant duct cells). However, the recent discovery of microRNAs (miRNAs) has provided new directions for research on mechanisms underlying response to chemotherapy. Due to their tissue-/disease-specific expression and high stability in tissues and biofluids, miRNAs represent new promising diagnostic and prognostic/predictive biomarkers and therapeutic targets. Furthermore, several studies have documented that selected miRNAs, such as miR-21 and miR-34a, may influence response to chemotherapy in several tumor types, including PDAC. In this review, we summarize the current knowledge on the role of miRNAs in PDAC and recent advances in understanding their role in chemoresistance through multiple molecular mechanisms.

Lin28 promotes Her2 expression and Lin28/Her2 predicts poorer survival in gastric cancer

The main purpose of this study is to investigate the interactions between Lin28 and Her2 in gastric cancer. Lin28 and Her2 expression were evaluated in surgically resected samples of 298 gastric cancer patients using immunohistochemical staining. The correlations between Lin28/Her2 expression and clinical variables were retrospectively analyzed. The mRNA level of LIN28 and HER2 was detected by reverse-transcriptase polymerase chain reaction. Among all gastric cancer patients, 33.9% (101/298) were determined as Her2-positive, and 43.0% (128/298) were defined as Lin28-positive. Lin28 was significantly associated with Her2, advanced tumor stage, lesion size, and Ki67 level (p<0.05 for each). Kaplan-Meier analysis illustrated that both Lin28 and Her2 are poor prognostic factors in gastric cancer; Lin28(+)/Her2(+) patients have the poorest survival (median survival = 17 months, p<0.01). Multivariate Cox analysis showed that Lin28 is a significant prognostic factor (hazard ratio (HR) = 1.79, 95% confidence interval (CI) 1.23-2.62). Further stratification analysis indicated that Lin28 may be a prognostic factor in chemotherapy. In vitro data on MKN-28 and MKN-45 cells showed that Lin28 can upregulate Her2 expression at translational level. Both Lin28 and Her2 are poor prognostic factors in gastric cancer. Lin28 may regulate Her2 post-transcriptionally in gastric cancer cells, which indicates it might be a potential target in the treatment of gastric cancer.

Integrated microRNA network analyses identify a poor-prognosis subtype of gastric cancer characterized by the miR-200 family

PURPOSE

Our aim was to investigate whether microRNAs can predict the clinical outcome of patients with gastric cancer. We used integrated analysis of microRNA and mRNA expression profiles to identify gastric cancer microRNA subtypes and their underlying regulatory scenarios.

EXPERIMENTAL DESIGN

MicroRNA-based gastric cancer subtypes were identified by consensus clustering analysis of microRNA profiles of 90 gastric cancer tissues. Activated pathways in the subtypes were identified by gene expression profiles. Further integrated analysis was conducted to model a microRNA regulatory network for each subtype. RNA and protein expression were analyzed by RT-PCR and tissue microarray, respectively, in a cohort of 385 gastric cancer cases (including the 90 cases for profiling) to validate the key microRNAs and targets in the network. Both in vitro and in vivo experiments were carried out to further validate the findings.

RESULTS

MicroRNA profiles of 90 gastric cancer cases identified two microRNA subtypes significantly associated with survival. The poor-prognosis gastric cancer microRNA subtype was characterized by overexpression of epithelial-to-mesenchymal transition (EMT) markers. This gastric cancer "mesenchymal subtype" was further validated in a patient cohort comprising 385 cases. Integrated analysis identified a key microRNA regulatory network likely driving the gastric cancer mesenchymal subtype. Three of the microRNAs (miR-200c, miR-200b, and miR-125b) targeting the most genes in the network were significantly associated with survival. Functional experiments demonstrated that miR-200b suppressed ZEB1, augmented E-cadherin, inhibited cell migration, and suppressed tumor growth in a mouse model.

CONCLUSIONS

We have uncovered a key microRNA regulatory network that defines the mesenchymal gastric cancer subtype significantly associated with poor overall survival in gastric cancer.

Prognostic role of microRNA polymorphisms in patients with advanced esophageal squamous cell carcinoma receiving platinum-based chemotherapy

PURPOSE

MicroRNA (miRNA) polymorphisms contribute to cancer susceptibility and prognosis. The aim of this study was to evaluate the effects of miRNA polymorphisms on clinical outcomes in patients with advanced esophageal squamous cell carcinoma (ESCC) treated with platinum-based chemotherapy.

METHODS

Five polymorphisms (miR-146a rs2910164, miR-196a2 rs11614913, miR-100 rs1834306, miR-125a rs12976445 and miR-26a1 rs7372209) were genotyped in 378 patients with advanced ESCC recruited at Zhongshan Hospital. The associations between genotypes and drug response, toxicity, and overall survival were analyzed.

RESULTS

miR-146a rs2910164 was significantly associated with an increased risk of severe hematological toxicity [odds ratio = 0.374, 95 % confidence interval (CI) 0.171-0.819, P = 0.014]. The TT genotypes of both miR-196a2 rs11614913 and miR-125a rs12976445 were associated with worse survival [hazard ratio (HR) = 1.552, 95 % CI 1.112-2.165, P = 0.010; HR = 2.171, 95 % CI 1.173-4.017, P = 0.014, respectively]. Combined analysis revealed a 4.073-fold increased risk of death in patients carrying two unfavorable genotypes (P = 0.002).

CONCLUSIONS

Taken together, these findings indicate that miRNA polymorphisms may predict prognosis in advanced ESCC patients receiving platinum-based chemotherapy.

Novel inhibitory function of miR-125b in melanogenesis

MicroRNAs are known to be the important regulators of skin physiology and considered as new therapeutic targets to treat skin diseases. In this study, miR-125b was identified as a potent regulator of steady-state melanogenesis. We found that the expression of miR-125b was inversely related to pigment levels. A miR-125b mimic decreased the expression of pigmentation-related gene and melanin content, implying that miR-125b functions to decrease pigmentation. Moreover, we observed that the reduction in miR-125b expression in pigmented cells was at least partially due to the hypermethylation of the MIR125B-1 promoter, and miR-125b expression was regulated by intracellular cAMP levels.