Genetic alteration regulated by microRNAs in biliary tract cancers

Identification of cell cycle as the critical pathway modulated by exosome-derived microRNAs in gallbladder carcinoma

Gallbladder cancer (GBC), the most common malignancy in the biliary tract, is highly lethal malignant due to seldomly specific symptoms in the early stage of GBC. This study aimed to identify exosome-derived miRNAs mediated competing endogenous RNAs (ceRNA) participant in GBC tumorigenesis. A total of 159 differentially expressed miRNAs (DEMs) was identified as exosome-derived miRNAs, contains 34 upregulated exo-DEMs and 125 downregulated exo-DEMs based on the expression profiles in GBC clinical samples downloaded from the Gene Expression Omnibus database with the R package. Among them, 2 up-regulated exo-DEMs, hsa-miR-125a-3p and hsa-miR-4647, and 5 down-regulated exo-DEMs, including hsa-miR-29c-5p, hsa-miR-145a-5p, hsa-miR-192-5p, hsa-miR-194-5p, and hsa-miR-338-3p, were associated with the survival of GBC patients. Results of the gene set enrichment analysis showed that the cell cycle-related pathways were activated in GBC tumor tissues, mainly including cell cycle, M phase, and cell cycle checkpoints. Furthermore, the dysregulated ceRNA network was constructed based on the lncRNA-miRNA-mRNA interactions using miRDB, TargetScan, miRTarBase, miRcode, and starBase v2.0., consisting of 27 lncRNAs, 6 prognostic exo-DEMs, and 176 mRNAs. Together with prognostic exo-DEMs, the STEAP3-AS1/hsa-miR-192-5p/MAD2L1 axis was identified, suggesting lncRNA STEAP3-AS1, might as a sponge of exosome-derived hsa-miR-192-5p, modulates cell cycle progression via affecting MAD2L1 expression in GBC tumorigenesis. In addition, the biological functions of genes in the ceRNA network were also annotated by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. Our study promotes exploration of the molecular mechanisms associated with tumorigenesis and provide potential targets for GBC diagnosis and treatment.

The microRNA cluster miR-30b/-30d prevents tumor cell switch from an epithelial to a mesenchymal-like phenotype in GBC

As a malignancy of the gastrointestinal tract, gallbladder cancer (GBC) continues to exhibit notable rates of mortality. The current study aimed at investigating the effects associated with miR-30b and miR-30d (miR-30b/-30d) patterns in tumor cells undergoing epithelial-to-mesenchymal transition (EMT) in GBC. It identified that miR-30b and miR-30d, composed as a miRNA cluster, exhibited lower levels in the cancerous tissues from 50 patients with GBC relative to the gallbladder tissues from 35 patients with chronic cholecystitis. As expected, elevated expression of miR-30b/-30d was found to inhibit the EMT process, as evidenced by enhanced E-cadherin and reduced N-cadherin and vimentin in human GBC cells treated with miR-30b mimic, miR-30d mimic, and miR-30b/-30d mimic. Semaphorin-6B (SEMA6B) was identified as a target gene of miR-30b/-30d. Silencing of SEMA6B by its specific small interfering RNA (siRNA) mimicked the effect of miR-30b/-30d upregulation on the GBC cell EMT. Consistently, SEMA6B overexpression promoted this phenotypic switch even in the presence of miR-30b/-30d mimic. The tumorigenicity assay data obtained from nude mice also further supported the notion that miR-30b/-30d inhibited EMT of GBC cells. Thus, based on the key findings of the current study, we concluded that the miR-30b/-30d cluster may provide a potential avenue for targeting mesenchymal-like, invasive tumor cells in GBC.

ARID1A alterations and their clinical significance in cholangiocarcinoma

Background

ARID1A is a member of the SWI/SNF chromatin remodeling complex. It functions as a tumor suppressor and several therapeutic targets in ARID1A-mutated cancers are currently under development, including EZH2. A synthetic lethal relationship between ARID1A and EZH2 has been revealed in several tumor entities. Although genomic alterations of ARID1A have been described in various cancers, no study has examined correlations between ARID1A gene mutation and protein expression with clinicopathologic parameters and prognosis, particularly in liver fluke-related cholangiocarcinoma (Ov-CCA). Here, we investigated the clinical significance of ARID1A mutations and protein expression in CCA tissues and determined whether there is a correlation with EZH2 protein expression.

Methods

We evaluated ARID1A and EZH2 immunoreactivity using immunohistochemistry in 98 Ov-CCA with a wide range of clinicopathological features. Somatic mutations of ARID1A were analyzed using the ICGC sequencing data in 489 of Ov and non Ov-CCA and assessed prognostic values.

Results

While detecting a loss or reduction of ARID1A expression in 54 cases (55%) in Ov-CCA, ARID1A expression was associated with ARID1A mutations (p < 0.001, adjusted p-value < 0.001). We observed that 12 of 13 tumors (92%) with loss of ARID1A expression had truncating mutations. There were nine of 13 tumors (69%) with loss of ARID1A expression and 25 of 41 tumors (61%) with low ARID1A expression exhibited distant metastasis (p = 0.028, adjusted p-value = 0.168). ARID1A was predominantly mutated in Ov-CCA compared to non Ov-CCA (24% and 14% in Ov-CCA and non Ov-CCA, respectively, p = 0.027). There were 36 of 72 (50%) and 52 of 79 (66%) tumors with ARID1A mutation showed tumor stage IV and T3/T4, respectively. The significant mutual exclusivity and co-occurrence between ARID1A and TP53/KRAS mutations were not found in ICGC cohort. In addition, high EZH2 expression, a potential synthetic lethal target in ARID1A-mutated tumors, was detected in 49 of 98 Ov-CCA (50%). Importantly, neither ARID1A expression nor ARID1A mutations correlated with EZH2 expression in this cohort.

Conclusion

We found that ARID1A inactivation, by somatic mutation or by loss of expression, frequently occurs in Ov-CCA. Reduction of ARID1A expression and/or somatic mutation was shown to be associated with CCA progression. These findings suggest that ARID1A may serve as a prognostic biomarker, and thus may be a promising therapeutic target for CCA.

miR-885-5p inhibits proliferation and metastasis by targeting IGF2BP1 and GALNT3 in human intrahepatic cholangiocarcinoma

The incidence of intrahepatic cholangiocarcinoma (iCCA) continues to increase worldwide, however its molecular pathogenesis remains poorly understood. Recent studies have implicated microRNAs in iCCA progression. In this study, we demonstrated that miR-885-5p was significantly decreased in iCCA tissues. Downregulation of miR-885-5p was correlated with vascular invasion, lymph node metastasis, unfavorable overall survival, and shorter disease-free survival. Silencing or overexpressing miR-885-5p by lentiviral approaches significantly influenced iCCA cell proliferation and metastasis in vitro and in vivo. Mechanistically, overexpression of miR-885-5p inhibited iCCA metastasis and proliferation by directly inhibiting GALNT3 as well as by indirectly promoting the downregulation of insulin-like growth factor-2 mRNA-binding protein 1 (IGF2BP1). Furthermore, miR-885-5p inhibited iCCA metastasis by downregulating the PI3K/AKT/MMPs signaling pathway via targeting GALNT3. Collectively, we demonstrated that miR-885-5p was an important mediator of iCCA proliferation and metastasis by regulating GALNT3 and IGF2BP1, thus offering a potential target for iCCA treatment.

The Emerging Role of MicroRNAs in Regulating the Drug Response of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is the most common biliary malignancy, and has a poor prognosis. The median overall survival with the standard-of-care chemotherapy (Gemcitabine and cisplatin) in patients with advanced-stage CCA is less than one year. The limited efficacy of chemotherapy or targeted therapy remains a major obstacle to improving survival. The mechanisms involved in drug resistance are complex. Research efforts focusing on the distinct molecular mechanisms underlying drug resistance should prompt the development of treatment strategies that overcome chemoresistance or targeted drug resistance. MicroRNAs (miRNAs) are a class of evolutionarily conserved, short noncoding RNAs regulating gene expression at the post-transcriptional level. Dysregulated miRNAs have been shown to participate in almost all CCA hallmarks, including cell proliferation, migration and invasion, apoptosis, and the epithelial-to-mesenchymal transition. Emerging evidence demonstrates that miRNAs play a role in regulating responses to chemotherapy and targeted therapy. Herein, we present an overview of the current knowledge on the miRNA-mediated regulatory mechanisms underlying drug resistance among CCA. We also discuss the application of miRNA-based therapeutics to CCA, providing the basis for innovative treatment approaches.

Cholangiocarcinoma: Classification, Histopathology and Molecular Carcinogenesis

Cholangiocarcinoma (CC) is the second most common tumor of the liver, originating from the biliary system with increasing incidence and mortality worldwide. Several new classifications review the significance of tumor localization, site of origin, proliferation and biomarkers in the intrahepatic, perihilar and distal forms of the lesion. Based on growth pattern mass-forming, periductal-infiltrating, intraductal, undefined and mixed types are differentiated. There are further subclassifications which are applied for the histological features, in particular for intrahepatic CC. Recognition of the precursors and early lesions of CC including biliary intraepithelial neoplasia (BilIN), intraductal papillary neoplasm of the bile ducts (IPNB), biliary mucinous cystic neoplasm (MCNB) and the candidate precursors, such as bile duct adenoma and von Meyenburg complex is of increasing significance. In addition to the previously used biliary markers detected by immunohistochemistry, several new markers have been added to the differentiation of both the benign and malignant lesions, which can be used to aid in the subclassification in association with the outcome of CC. Major aspects of biliary carcinogenesis have been revealed, yet, the exact way of this diverse process is still unclear. The factors contributing to molecular cholangiocarcinogenesis include various risk factors, different anatomical localizations, multiple cellular origins, genetic and epigenetic alterations, tumor microenvironment, heterogeneity and clonal evolution. Driver mutations have been identified, implying that they are optimal candidates for targeted therapy. The most promising therapeutic candidates have entered clinical trials.

MicroRNA (miR)-433 and miR-22 dysregulations induce histone-deacetylase-6 overexpression and ciliary loss in cholangiocarcinoma

Cholangiocytes normally express primary cilia, a multisensory organelle that detects signals from the cellular environment. Cilia are significantly reduced in cholangiocarcinoma (CCA) by a mechanism involving overexpression of histone deacetylase 6 (HDAC6). Despite HDAC6 overexpression in CCA, we found no differences in its mRNA level, suggesting a posttranscriptional regulation, possibly involving microRNAs (miRNAs). Here, we describe that at least two HDAC6-targeting miRNAs, miR-433 and miR-22, are down-regulated in CCA both in vitro and in vivo. Experimental restoration of these miRNAs in CCA cells reduced HDAC6 expression, induced ciliary restoration, and decreased the malignant phenotype. Furthermore, in contrast to the mature forms, levels of precursor forms of these miRNAs were higher in CCA compared to normal cholangiocytes and accumulated in the nuclei, suggesting a defective nuclear export. We assessed the expression of Exportin-5, the protein responsible for transporting miRNA precursors out of the nucleus, and found it to be reduced by 50% in CCA compared to normal cholangiocytes. Experimental overexpression of Exportin-5 in CCA cells restored precursor and mature forms of these miRNAs to normal levels, inducing a decrease in the expression of HDAC6 and a decrease in the malignant phenotype. Conversely, short hairpin RNA (shRNA) depletion of Exportin-5 in normal cholangiocytes resulted in increased nuclear retention of precursor miRNAs, decreased mature miRNAs, increased cell proliferation, and shorter cilia.

CONCLUSION

These data suggest that down-regulated Exportin-5 impairs the nuclear export of miR-433 and miR-22 precursor forms, causing a decrease in levels of mature miR-433 and miR-22 forms, and leading to overexpression of HDAC6 and ciliary loss in CCA. (Hepatology 2018).

Targeting of NT5E by miR-30b and miR-340 attenuates proliferation, invasion and migration of gallbladder carcinoma

MicroRNAs (miRNAs) have been closely associated with the proliferation, invasion and migration of various cancers, including gallbladder carcinoma (GBC). Previous studies have revealed dysregulation of miR-30b and miR-340 in many types of cancer. However, the role of miR-30b and miR-340 in the development and progression of GBC remains unclear. Moreover, epithelial-to-mesenchymal transition (EMT) has been gradually viewed as a significant contributor to tumor metastasis. In this study, the cell line GBC-SD was used and we explored that EMT promoted GBC cells invasion and migration and inhibited the expression level of miR-30b and miR-340 compared with the control. We showed that overexpression of miR-30b and miR-340 suppressed GBC cells proliferation, invasion and migration, as well as the expression of EMT-associated genes. In addition, we identified ecto-5'-nucleotidase (NT5E) as a common target of miR-30b and miR-340 using bioinformatics analysis and a luciferase assay. Further experiments found that exogenous expression of NT5E in GBC cells could partially reverse the inhibitory effect of miR-30b and miR-340 on cell proliferation, invasion and migration. Our findings suggest that NT5E-targeting miRNAs (miR-30b and miR-340) function as tumor suppressors and may represent promising therapeutic targets for GBC.

Down-regulation of miR-605 promotes the proliferation and invasion of prostate cancer cells by up-regulating EN2

AIMS

MicroRNA served as inhibitor for gene expression in various cancers. This study aimed to investigate the role of miR-605 and EN2 in prostate cancer (PCa).

MATERIALS AND METHODS

In this research, the expression of miR-605 and EN2 protein in PCa tissues and cells were determined by qRT-PCR and western blot, respectively. The cell proliferation was measured by Cell Counting Kit-8 (CCK-8) and the tumor cell invasion assay was accomplished with transwell system. Flow cytometry was used to analyze the cell cycle. The endogenous expression of miR-605 and EN2 was modulated by recombinant plasmids and cell transfection. Dual luciferase reporter assay was performed to determine the interaction between miR-605 and EN2 in PCa cells.

KEY FINDINGS

The expression of miR-605 was lower in PCa tissue and cells than that in normal tissues and cells, while the expression of EN2 was just the opposite. Down-regulation of the EN2 by siRNA inhibited the proliferation and invasion of PC3 cells, and the cell cycle was arrested in G0/G1 phase. EN2 regulated the expression of E-cadherin and Vimentin through Snail and EN2 regulated the cell cycle and cell proliferation via PI3K/AKT pathway. MiR-605 inhibited the proliferation and invasion of PCa cells through targeting EN2.

SIGNIFICANCE

EN2 is negatively regulated by miR-605, and down-regulation of miR-605 promotes the proliferation and invasion of PCa cells by up-regulating EN2, which leads to PCa development and progression.

Identification of microRNAs as biomarkers for cholangiocarcinoma detection: A diagnostic meta-analysis

BACKGROUND

Cholangiocarcinoma (CCA) is a common biliary malignancy that results in high mortality and poor survival rates. The diagnostic capacity of miRNAs in CCA detection is still controversial. Current meta-analysis evaluate the evidence on the capacity of miRNAs for CCA diagnosis.

METHODS

A systematic literature search for relevant articles in PubMed, Embase and Web of science database up to 10 April 2016 was conducted. The pooled sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR, respectively), diagnostic odds ratio (DOR) and area under the curve (AUC) were pooled to assess the overall diagnostic value of miRNA. Subgroup analysis was further applied to explore the between-study heterogeneity. Publication bias was assessed with Deeks' funnel plot. Statistical analysis was carried out using RevMan 5.2 and MetaDisc 1.4.

RESULTS

A total of 501 patients and 248 controls from 14 studies in 8 articles were included in this meta-analysis. The pooled sensitivity and specialty were 0.83 (0.80-0.86) and 0.79 (0.75-0.83), respectively. The pooled PLR was 3.96 (2.64-5.94), NLR was 0.25 (0.19-0.34), DOR was 18.1 (9.79-33.5) and pooled AUC was 0.88 (0.85-0.90). Subgroup analyses indicated that the serum miRNA assays showed highly accurate CCA diagnosis. The diagnostic capacity was more accurate in Caucasians than in Asians.

CONCLUSIONS

The miRNA assays are promising diagnostic tools for CCA detection with moderate accuracy. However, further prospective studies were needed to confirm this results before clinical application.

MicroRNA in pancreatic ductal adenocarcinoma and its precursor lesions

Pancreatic ductal adenocarcinoma (PDAC) is the 4^th deadliest cancer in the United States, due to its aggressive nature, late detection, and resistance to chemotherapy. The majority of PDAC develops from 3 precursor lesions, pancreatic intraepithelial lesions (PanIN), intraductual papillary mucinous neoplasm (IPMN), and mucinous cystic neoplasm. Early detection and surgical resection can increase PDAC 5-year survival rate from 6% for Stage IV to 50% for Stage I. To date, there are no reliable biomarkers that can detect PDAC. MicroRNAs (miRNA) are small noncoding RNAs (18-25 nucleotides) that regulate gene expression by affecting translation of messenger RNA (mRNA). A large body of evidence suggests that miRNAs are dysregulated in various types of cancers. MiRNA has been profiled as a potential biomarker in pancreatic tumor tissue, blood, cyst fluid, stool, and saliva. Four miRNA biomarkers (miR-21, miR-155, miR-196, and miR-210) have been consistently dysregulated in PDAC. MiR-21, miR-155, and miR-196 have also been dysregulated in IPMN and PanIN lesions suggesting their use as early biomarkers of this disease. In this review, we explore current knowledge of miRNA sampling, miRNA dysregulation in PDAC and its precursor lesions, and advances that have been made in using miRNA as a biomarker for PDAC and its precursor lesions.