Restoring miR122 in human stem-like hepatocarcinoma cells, prompts tumor dormancy through Smad-independent TGF-β pathway

The Multifunctional Nature of the MicroRNA/AKT3 Regulatory Axis in Human Cancers

Serine/threonine kinase (AKT) signaling regulates diverse cellular processes and is one of the most important aberrant cell survival mechanisms associated with tumorigenesis, metastasis, and chemoresistance. Targeting AKT has become an effective therapeutic strategy for the treatment of many cancers. AKT3 (PKBγ), the least studied isoform of the AKT family, has emerged as a major contributor to malignancy. AKT3 is frequently overexpressed in human cancers, and many regulatory oncogenic or tumor suppressor small non-coding RNAs (ncRNAs), including microRNAs (miRNAs), have recently been identified to be involved in regulating AKT3 expression. Therefore, a better understanding of regulatory miRNA/AKT3 networks may reveal novel biomarkers for the diagnosis of patients with cancer and may provide invaluable information for developing more effective therapeutic strategies. The aim of this review was to summarize current research progress in the isoform-specific functions of AKT3 in human cancers and the roles of dysregulated miRNA/AKT3 in specific types of human cancers.

MiR-17-5p and MKL-1 modulate stem cell characteristics of gastric cancer cells

Effectively targeting cancer stem cells to treat cancer has great therapeutic prospects. However, the effect of microRNA miR-17/MKL-1 on gastric cancer stem cells has not been studied yet. This study preliminarily explored the mechanism of miR-17/MKL-1 in gastric cancer stem cells. Many previous reports have indicated that microRNA and EMT regulated cancer stem cell characteristics, and miR-17 and MKL-1 were involved as a critical gene in migration and invasion in the EMT pathway. Through RT-PCR, Western Blot, flow cytometry, immunofluorescence, sphere formation xenograft tumor assays and drug resistance, the role of miR-17-5p and MKL-1 on promoting stem cell-like properties of gastric cancer were verified in vivo and vitro. Next, MKL-1 targets CD44, EpCAM, and miR -17-5p promoter verified by luciferase assay and ChIP. Besides, the TCGA database analysis found that both miR-17-5p and MKL-1 increased in gastric cancer, and the prognostic survival of the MKL-1 high expression group was reduced. It is found that MKL-1 promotes expression by targeting miR-17, CD44 and EpCAM promoters. Besides, the TCGA database analysis found that both miR-17-5p and MKL-1 increased in gastric cancer, and the prognostic survival of the MKL-1 high expression group was reduced. These findings reveal new regulatory signaling pathways for gastric cancer stem cells, thus it give new insights on potential early diagnosis and/or molecular therapy for gastric cancer.

Autophagy and Cancer Dormancy

Metastasis and relapse account for the great majority of cancer-related deaths. Most metastatic lesions are micro metastases that have the capacity to remain in a non-dividing state called “dormancy” for months or even years. Commonly used anticancer drugs generally target actively dividing cancer cells. Therefore, cancer cells that remain in a dormant state evade conventional therapies and contribute to cancer recurrence. Cellular and molecular mechanisms of cancer dormancy are not fully understood. Recent studies indicate that a major cellular stress response mechanism, autophagy, plays an important role in the adaptation, survival and reactivation of dormant cells. In this review article, we will summarize accumulating knowledge about cellular and molecular mechanisms of cancer dormancy, and discuss the role and importance of autophagy in this context.

LncRNA influence sequential steps of hepatocellular carcinoma metastasis

As a class of new and crucial molecules involved in the regulation of biological function, long noncoding RNA (lncRNA) have obtained widespread attention in recent days. While it was thought that lncRNA would be redundant in the past, it is proved that lncRNA identify a class of molecular that regulate the homeostasis including hepatocellular carcinoma in the present. All kinds of lncRNA have been implicated in a various of diseases, particularly in tumorigenesis and metastasis. But the mechanisms how they act is still not entirely clear. Metastasis is a major factor affecting long-term survival in hepatocellular carcinoma (HCC) patients. Recently, growing numbers of experiments demonstrate that there is close connection between lncRNA and HCC metastasis. Here, we will briefly introduce a series of steps (primary tumor growth, angiogenesis, epithelial-to-mesenchymal transition, invasion, intravasation, survival in circulatory system, extravasation, dormancy and subsequent secondary tumor growth) of tumor metastasis, its classical but promising theories, the role of lncRNA in metastasis and the possible mechanisms involved. LncRNA, as potentially new and important tumor diagnostic and therapeutic molecules, has attracted much attention in recent years.

Targeting transforming growth factor-β signaling for enhanced cancer chemotherapy

During the past decades, drugs targeting transforming growth factor-β (TGFβ) signaling have received tremendous attention for late-stage cancer treatment since TGFβ signaling has been recognized as a prime driver for tumor progression and metastasis. Nonetheless, in healthy and pre-malignant tissues, TGFβ functions as a potent tumor suppressor. Furthermore, TGFβ signaling plays a key role in normal development and homeostasis by regulating cell proliferation, differentiation, migration, apoptosis, and immune evasion, and by suppressing tumor-associated inflammation. Therefore, targeting TGFβ signaling for cancer therapy is challenging. Recently, we and others showed that blocking TGFβ signaling increased chemotherapy efficacy, particularly for nanomedicines. In this review, we briefly introduce the TGFβ signaling pathway, and the multifaceted functions of TGFβ signaling in cancer, including regulating the tumor microenvironment (TME) and the behavior of cancer cells. We also summarize TGFβ targeting agents. Then, we highlight TGFβ inhibition strategies to restore the extracellular matrix (ECM), regulate the tumor vasculature, reverse epithelial-mesenchymal transition (EMT), and impair the stemness of cancer stem-like cells (CSCs) to enhance cancer chemotherapy efficacy. Finally, the current challenges and future opportunities in targeting TGFβ signaling for cancer therapy are discussed.

Dysregulated microRNAs in Hepatitis B Virus-Related Hepatocellular Carcinoma: Potential as Biomarkers and Therapeutic Targets

MicroRNAs (miRNAs) are non-coding small RNAs that can function as gene regulators and are involved in tumorigenesis. We review the commonly dysregulated miRNAs in liver tumor tissues and plasma/serum of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) patients. The frequently reported up-regulated miRNAs in liver tumor tissues include miR-18a, miR-21, miR-221, miR-222, and miR-224, whereas down-regulated miRNAs include miR-26a, miR-101, miR-122, miR-125b, miR-145, miR-199a, miR-199b, miR-200a, and miR-223. For a subset of these miRNAs (up-regulated miR-222 and miR-224, down-regulated miR-26a and miR-125b), the pattern of dysregulated circulating miRNAs in plasma/serum is mirrored in tumor tissue based on multiple independent studies. Dysregulated miRNAs target oncogenes or tumor suppressor genes involved in hepatocarcinogenesis. Normalization of dysregulated miRNAs by up- or down-regulation has been shown to inhibit HCC cell proliferation or sensitize liver cancer cells to chemotherapeutic treatment. miRNAs hold as yet unrealized potential as biomarkers for early detection of HCC and as precision therapeutic targets, but further studies in diverse populations and across all stages of HCC are needed.

Tumor dormancy in bone

Background

Bone marrow is a common site of metastasis for a number of tumor types, including breast, prostate, and lung cancer, but the mechanisms controlling tumor dormancy in bone are poorly understood. In breast cancer, while advances in drug development, screening practices, and surgical techniques have dramatically improved survival rates in recent decades, metastatic recurrence in the bone remains common and can develop years or decades after elimination of the primary tumor.

Recent Findings

It is now understood that tumor cells disseminate to distant metastatic sites at early stages of tumor progression, leaving cancer survivors at a high risk of recurrence. This review will discuss mechanisms of bone lesion development and current theories of how dormant cancer cells behave in bone, as well as a number of processes suspected to be involved in the maintenance of and exit from dormancy in the bone microenvironment.

Conclusions

The bone is a complex microenvironment with a multitude of cell types and processes. Many of these factors, including angiogenesis, immune surveillance, and hypoxia, are thought to regulate tumor cell entry and exit from dormancy in different bone marrow niches.

miR-4666-3p and miR-329 Synergistically Suppress the Stemness of Colorectal Cancer Cells via Targeting TGF-β/Smad Pathway

Quiescent caner stem cells are identified as a subpopulation of colon cancer cells in dormant state and possess strong stem-cell like characteristics. Previously, we have identified this subpopulation in colorectal cancer (quiescent colon cancer stem cells, QCCSCs), and find QCCSCs are sensitive to the apoptotic effect of IFN-γ, which is attributed to their high IFN-γR expression levels. Microarray and bioinformatic analysis indicate miR-4666-3p is low expressed in QCCSCs and target IFN-γR1/2, which is proved by luciferase assay and western-blot. Furthermore, we find miR-4666-3p could also target TGF-βR1 to block the activation of TGF-β1/Smad pathway, therefore function as a tumor suppressor gene to inhibit the stemness of colon cancer cells. Besides, compared with QCCSCs, we find the TGF-β1 expression also decreased with the weakening of stemness properties. In terms of mechanism, our result reveal TGF-β1 is the target gene of miR-329, which is also high expressed in non-QCCSCs. Thereafter, we perform gain- and loss- function experiments to confirm the synergistic effect between miR-4666-3p and miR-329 in blocking the activation of TGF-β/Smad pathway. Finally, we evaluate the expression of both miR-4666-3p and miR-329 in 73 tumor specimens and paired normal tissue, and find both two miRNAs are related to unfavorable prognosis and advanced tumor stage in colorectal cancer. Our study revealed a novel epigenetic regulation mechanism in colon cancer stem cells, which could be exploited as a novel therapeutic strategy for cancer treatment.

Biomarkers Associated With Response to Regorafenib in Patients With Hepatocellular Carcinoma

BACKGROUND & AIMS

In a phase 3 trial (RESORCE), regorafenib increased overall survival compared with placebo in patients with hepatocellular carcinoma (HCC) previously treated with sorafenib. In an exploratory study, we analyzed plasma and tumor samples from study participants to identify genetic, microRNA (miRNA), and protein biomarkers associated with response to regorafenib.

METHODS

We obtained archived tumor tissues and baseline plasma samples from patients with HCC given regorafenib in the RESORCE trial. Baseline plasma samples from 499 patients were analyzed for expression of 294 proteins (DiscoveryMAP) and plasma samples from 349 patients were analyzed for levels of 750 miRNAs (miRCURY miRNA PCR). Tumor tissues from 7 responders and 10 patients who did not respond (progressors) were analyzed by next-generation sequencing (FoundationOne). Forty-six tumor tissues were analyzed for expression patterns of 770 genes involved in oncogenic and inflammatory pathways (PanCancer Immune Profiling). Associations between plasma levels of proteins and miRNAs and response to treatment (overall survival and time to progression) were evaluated using a Cox proportional hazards model.

RESULTS

Decreased baseline plasma concentrations of 5 of 266 evaluable proteins (angiopoietin 1, cystatin B, the latency-associated peptide of transforming growth factor beta 1, oxidized low-density lipoprotein receptor 1, and C-C motif chemokine ligand 3; adjusted P ≤ .05) were significantly associated with increased overall survival time after regorafenib treatment. Levels of these 5 proteins, which have roles in inflammation and/or HCC pathogenesis, were not associated with survival independently of treatment. Only 20 of 499 patients had high levels and a reduced survival time. Plasma levels of α-fetoprotein and c-MET were associated with poor outcome (overall survival) independently of regorafenib treatment only. We identified 9 plasma miRNAs (MIR30A, MIR122, MIR125B, MIR200A, MIR374B, MIR15B, MIR107, MIR320, and MIR645) whose levels significantly associated with overall survival time with regorafenib (adjusted P ≤ .05). Functional analyses of these miRNAs indicated that their expression level associated with increased overall survival of patients with tumors of the Hoshida S3 subtype. Next-generation sequencing analyses of tumor tissues revealed 49 variants in 27 oncogenes or tumor suppressor genes. Mutations in CTNNB1 were detected in 3 of 10 progressors and VEGFA amplification in 1 of 7 responders.

CONCLUSION

We identified expression patterns of plasma proteins and miRNAs that associated with increased overall survival times of patients with HCC following treatment with regorafenib in the RESORCE trial. Levels of these circulating biomarkers and genetic features of tumors might be used to identify patients with HCC most likely to respond to regorafenib. ClinicalTrials.gov number NCT01774344. NCBI GEO accession numbers: mRNA data (NanoString): GSE119220; miRNA data (Exiqon): GSE119221.

PRRX1 Regulates Cellular Phenotype Plasticity and Dormancy of Head and Neck Squamous Cell Carcinoma Through miR-642b-3p

BACKGROUND: Dormancy is one characteristic of cancer cells to make patients remain asymptomatic before metastasis and relapse, which is closely related to the survival rate of cancer patients, including head and neck squamous cell carcinoma (HNSCC). PRRX1 has previously been implicated in the invasion and metastasis of the epithelial-mesenchymal transition (EMT) process in different types of human carcinoma. However, whether PRRX1 can regulate cancer dormancy and its reactivation, leading to the migration and invasion of HNSCC cells, remains elusive. The aim of this study was to determine the role of PRRX1 in cellular phenotype plasticity and cancer dormancy of HNSCC cells and its association with miRNAs in HNSCC. METHODS: The expression of PRRX1 was detected by immunohistochemical staining in primary HNSCC samples and the metastatic lymph nodes. Meanwhile, the role of PRRX1 and its relationship with miR-642b-3p and EMT in cellular phenotype plasticity and cancer dormancy of HNSCC were investigated in vitro and in vivo. RESULTS: PRRX1 was significantly higher at the invasive front of HNSCC samples compared with the metastatic lymph nodes, and such switch process was accompanied by the cellular phenotype plasticity and cell dormancy activation. In HNSCC cell lines, PRRX1 positively promoted the expression of known EMT inducers and cooperated with activated TGF-β1 to contribute to EMT and migration and invasion of HNSCC cells. Then, we found that overexpression of miR-642b-3p, one of the most significantly downregulated miRNAs in PRRX1-overexpressed cells, significantly reduced the migration and invasion, and increased cell proliferation and apoptosis. And miR-642b-3p restoration reversed PRRX1-induced cell dormancy and EMT of HNSCC cells through TGF-β2 and p38. Finally, we demonstrated that overexpressed PRRX1 was closely correlated with miR-642b-3p downregulation and the upregulation of TGF-β2 and p38 in a xenograft model of HNSCC. CONCLUSIONS: Our findings showed that PRRX1 may be one of the main driving forces for the cellular phenotype plasticity and tumor dormancy of HNSCC. Therefore, we can raise the possibility that EMT may help to keep cancer cell in dormant state and mesenchymal-epithelial transition may resurge dormancy in HNSCC.

TGF-β Family Signaling Pathways in Cellular Dormancy

Individual cancer cells can switch, reversibly, to a non-proliferative dormant state, a process characterized by two principal stages: (i) establishment and maintenance, and (ii) the breaking of dormancy. This phenomenon is of clinical importance because dormant cells resist chemotherapy, and this can result in cancer relapse following years, if not decades, of clinical remission. Although the molecular mechanisms governing tumor cell dormancy have not been clearly delineated, accumulating evidence suggests that members of the transforming growth factor-β (TGF-β) family are integral. We summarize here recent findings which support the view that TGF-β family signaling pathways play a pivotal role in cellular dormancy, and discuss how affected cells could be therapeutically targeted to prevent cancer relapse.

MicroRNA regulation of liver cancer stem cells

MicroRNAs (miRNAs), a class of emerging small non-coding RNAs, serve as vital players in modulating multiple biological processes via the post-transcriptional regulation of gene expression. Dysregulated expression of miRNAs in liver cancer is well documented, and the involvement of miRNAs in liver cancer initiation and progression has also been described. Cancer stem cells (CSCs) are a subset of cells known to be at the root of cancer recurrence and resistance to therapy. In this review, we highlight recent reports indicating that miRNAs participate in the regulation of liver cancer stem cells (LCSCs). The Wnt signaling pathway, TGF-beta signaling pathway, JAK/STAT signaling pathway and epithelial-mesenchymal transition (EMT) are all closely correlated with the miRNA modulation of LCSCs. In addition, several miRNAs have been demonstrated to be involved in the regulation of LCSCs in response to therapy sensitivity. Targeting LCSCs by regulating the expression of these miRNAs represents a potential therapeutic strategy for treating cancer drug resistance, metastasis and recurrence in the near future.

The Diverse Mechanisms of miRNAs and lncRNAs in the Maintenance of Liver Cancer Stem Cells

Liver cancer is the second leading cause of cancer-related death worldwide. The high frequency of recurrence and metastasis is the main reason for poor prognosis. Liver cancer stem cells (CSCs) have unlimited self-renewal, differentiation, and tumor-regenerating capacities. The maintenance of CSCs may account for the refractory features of liver cancer. Despite extensive investigations, the underlying regulatory mechanisms of liver CSCs remain elusive. miRNA and lncRNA, two major classes of the ncRNA family, can exert important roles in various biological processes, and their diverse regulatory mechanisms in CSC maintenance have acquired increasing attention. However, to the best of our knowledge, there is a lack of reviews summarizing these findings. Therefore, we systematically recapitulated the latest studies on miRNAs and lncRNAs in sustaining liver CSCs. Moreover, we highlighted the potential clinical application of these dysregulated ncRNAs as novel diagnostic and prognostic biomarkers and therapeutic targets. This review not only sheds new light to fully understand liver CSCs but also provides valuable clues on targeting ncRNAs to block or eradicate CSCs in cancer treatment.

Antiapoptotic BCL-2 proteins determine sorafenib/regorafenib resistance and BH3-mimetic efficacy in hepatocellular carcinoma

Sorafenib, systemic treatment for advanced hepatocellular carcinoma (HCC), and regorafenib, novel second line treatment after sorafenib failure, have efficacy limited by evasive mechanisms of acquired-drug resistance. BCL-2 proteins participate in the response to tyrosine kinase inhibitors; however, their role in HCC therapy with sorafenib/regorafenib remains uncertain. BH3-mimetic ABT-263 (navitoclax) enhanced sorafenib activity, inducing cell death via a mitochondrial caspase-dependent mechanism, after BCL-xL/BCL-2 inhibition. Sorafenib-resistant hepatoma cells (HepG2R and Hep3BR) exhibited altered mRNA expression of BCL-2 and other anti-apoptotic family members, such as MCL-1, priming drug-resistant cancer cells to death by BH3-mimetics. ABT-263 restored sorafenib efficacy in sorafenib-resistant cell lines and HCC mouse models. Moreover, in mice xenografts from patient-derived BCLC9 cells, better tumor response to sorafenib was associated to higher changes in the BCL-2 mRNA pattern. HCC non-treated patients displayed altered BCL-2, MCL-1 and BCL-xL mRNA levels respect to adjacent non-tumoral biopsies and an increased BCL-2/MCL-1 ratio, predictive of navitoclax efficacy. Moreover, regorafenib administration also modified the BCL-2/MCL-1 ratio and navitoclax sensitized hepatoma cells to regorafenib by a mitochondrial caspase-dependent mechanism. In conclusion, sorafenib/regorafenib response is determined by BCL-2 proteins, while increased BCL-2/MCL-1 ratio in HCC sensitizes drug resistant-tumors against ABT-263 co-administration. Thus, changes in the BCL-2 profile, altered in HCC patients, could help to follow-up sorafenib efficacy, allowing patient selection for combined therapy with BH3-mimetics or early switch them to second line therapy.

MiR-122 and other microRNAs as potential circulating biomarkers of drug-induced liver injury

INTRODUCTION

Drug-induced liver injury (DILI) is a severe adverse drug reaction which is of major concern to patients, clinicians and the pharmaceutical industry. Accurate and rapid detection of DILI is important for patient stratification and treatment in the clinic and benefits preclinical drug design and risk assessment. MicroRNAs (miRNAs) offer a potential new and improved class of circulating biomarkers of DILI over the current gold standard biomarkers. Areas covered: This review highlights the shortcomings of the currently used panel of biomarkers and how miRNAs, primarily miR-122, show an improved level of specificity and sensitivity in the prediction of DILI. Furthermore, the use of miRNAs as potential markers of progression of DILI and specific zonated damage within the liver is discussed. Expert commentary: MiRNAs offer more sensitive and specific markers over the current biomarkers for DILI. Combinations of different miRNAs may be able to relay the location of DILI and the progression of disease. More studies using different hepatotoxins apart from acetaminophen will ultimately strengthen the case for the clinical introduction of miRNAs as biomarkers of DILI.

Non-coding RNA in hepatocellular carcinoma: Mechanisms, biomarkers and therapeutic targets

The majority of the human genome is not translated into proteins but can be transcribed into RNA. Even though the resulting non-coding RNAs (ncRNAs) do not encode for proteins, they contribute to diseases such as cancer. Here, we review examples of the functions of ncRNAs in liver cancer and their potential use for the detection and treatment of liver cancer.

Expression of OTUB1 in hepatocellular carcinoma and its effects on HCC cell migration and invasion

OTUB1 (OTU domain-containing ubiquitin aldehyde binding protein 1) is a deubiquitinating enzyme (DUB) that belongs to the ovarian tumor (OTU) domain protease superfamily. Although it has been demonstrated to play important roles in the development of many kinds of cancer, the mechanism of OTUB1 in hepatocellular carcinoma (HCC) is not clear. The aim of this study was to explore the roles of OTUB1 in HCC progression using cell lines and 115 archived HCC samples. In addition, the clinical outcomes were also analyzed with a special focus on OTUB1 expression in HCC samples. In the immunohistochemical study, OTUB1 showed high expression in 60 of the 115 cases (52.2%). The OTUB1 expression level was significantly correlated with many clinicopathological parameters, including TNM stage (P = 0.002), histology stage (P = 0.002), and metastasis/recurrence (P = 0.016). Survival analysis showed that the group with OTUB1 overexpression had significantly shorter overall survival time than the group with OTUB1 downregulation (hazard ratio [HR] = 0.482; confidence interval [CI]: 0.311-0.748; P = 0.001). Multivariate analysis indicated that OTUB1 expression was a significant and independent prognostic parameter (HR = 0.214; CI: 0.126-0.364; P < 0.001) for HCC patients. The ability of HCC cells to undergo proliferation, migration, and invasion was suppressed by disruption of endogenous OTUB1 using short hairpin RNA (shRNA). OTUB1 expression appears to be a new and independent predictor for the prognosis of HCC patients. Overexpression of OTUB1 in HCC could be a novel, effective, and supplementary biomarker for HCC because it plays a vital role in the progression of HCC.

Permissiveness of human hepatocellular carcinoma cell lines for hepatitis C virus entry and replication

Hepatitis C virus (HCV) is a globally prevalent pathogen and is associated with high death rates and morbidity. Since its discovery in 1989, HCV research has been impeded by the lack of a robust infectious cell culture system and thus in vitro studies on diverse genetic backgrounds are hampered because of the limited number of hepatoma cell lines which are able to support different aspects of the HCV life cycle. In the current study, we sought to expand the limited number of permissive cells capable of supporting the diverse phases of the HCV life cycle. Initially, we screened a panel of new hepatoma-derived cell lines, designated BCLC-1, -2, -3, -4, -5, -6, -9 and -10 cells, for their ability to express essential HCV receptors and subsequently to support HCV entry by using the well-characterized HCV pseudoparticle system (HCVpp). Apart from BCLC-9, all BCLC cell lines were permissive for HCVpp infection. Next, BCLC cells were subjected to short- and long-term HCV RNA replication studies using HCV subgenomic replicons. Interestingly, only BCLC-1, -5 and -9 cells, supported short-term HCV RNA replication, but the latter were excluded from further studies since they were refractory for HCV entry. BCLC-1, -5 were able to support long-term HCV replication too; yet BCLC-5 cells supported the highest long-term HCV RNA replication levels. Furthermore, cured BCLC-5 clones from HCV subgenomic replicon, showed increased permissiveness for HCV RNA replication. Strikingly, we were unable to detect endogenous BCLC-5 miR122 expression - an important HCV host factor- and as expected, the exogenous expression of miR122 in BCLC-5 cells increased their permissiveness for HCV RNA replication. However, this cell line was unable to produce HCV infectious particles despite ectopic expression of apolipoprotein E, which in other hepatoma cell lines has been shown to be sufficient to enable the HCV secretion process, suggesting a lack of other host cellular factor(s) and/or the presence of inhibitory factor(s). In conclusion, the establishment of these new permissive cell lines for HCV entry and replication, which possess a different genetic background compared to the well-established models, expands the current repertoire of hepatoma cell lines susceptible to the study of the HCV life cycle and also will aid to further elucidate the cellular determinants that modulate HCV replication, assembly and egress.

Diagnostic and therapeutic potentials of microRNAs in cholangiopathies

Cholangiopathies are a group of rare, devastating diseases that arise from damaged cholangiocytes, the cells that line the intra- and extra-hepatic bile ducts of the biliary epithelium. Cholangiopathies result in significant morbidity and mortality and are a major cause of liver transplantation. A better understanding of the underlying pathogenesis that influences cholangiocyte dysregulation and cholangiopathy progression is necessary, considering the dismal prognosis associated with these diseases. MicroRNAs are a class of small, non-coding RNAs that regulate post-transcriptional mRNA expression of specific genes. The role of microRNAs has expanded to include the initiation and development of many diseases, including cholangiopathies. Understanding microRNA regulation of cholangiopathies may provide diagnostic and therapeutic benefit for these diseases. In this review, the authors primarily focus on studies published within the last five years that help determine the diagnostic and therapeutic potential of microRNAs in cholangiopathies.