Cluster microRNAs miR-194 and miR-215 suppress the tumorigenicity of intestinal tumor organoids.

Tumor stem cells with self-renewal and multipotent capacity play critical roles in the initiation and progression of cancer. Recently, a new 3-D culture system known as organoid culture has been developed, allowing Lgr5-positive stem cells to form organoids that resemble the properties of original tissues. Here we established organoids derived from intestinal tumors of Apcmin/+ mice and normal intestinal epithelia of C57BL/6J mice and investigated the roles of microRNA (miRNA) in intestinal tumor organoids. The results of microarray analyses revealed that expression of the cluster miRNAs, miR-194 and miR-215 was markedly suppressed in intestinal tumor organoids in comparison with organoids derived from normal intestinal epithelia. Enforced expression of miR-194 resulted in inhibition of E2f3, a positive regulator of the cell cycle and growth suppression of intestinal tumor organoids. In addition, enforced expression of miR-215 suppressed the cancer stem cell signature through downregulation of intestinal stem cell markers including Lgr5. These findings indicate that the miRNA cluster including miR-194 and miR-215 plays important roles in suppressing the growth and attenuating the stemness of intestinal tumor organoids.

Silencing of microRNA-122 is an early event during hepatocarcinogenesis from non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH) has emerged as a common cause of chronic liver disease and virus-independent hepatocellular carcinoma (HCC) in patients with obesity, diabetes, and metabolic syndrome. To reveal the molecular mechanism underlying hepatocarcinogenesis from NASH, microRNA (miRNA) expression profiles were analyzed in STAM mice, a NASH-HCC animal model. MicroRNA expression was also examined in 42 clinical samples of HCC tissue. Histopathological images of the liver of STAM mice at the ages of 6, 8, 12, and 18 weeks showed findings compatible with fatty liver, NASH, liver cirrhosis (LC), and HCC, respectively. Expression of miR-122 in non-tumor LC at the age of 18 weeks was significantly lower than that in LC at the age of 12 weeks. Expression of miR-122 was further decreased in HCCs relative to non-tumor LC at the age of 18 weeks. Expression of miR-122 was also decreased in clinical samples of liver tissue showing macrovesicular steatosis and HCC, being consistent with the findings in the NASH model mice. DNA methylation analysis revealed that silencing of miR-122 was not mediated by DNA hypermethylation of the promoter region. These results suggest that silencing of miR-122 is an early event during hepatocarcinogenesis from NASH, and that miR-122 could be a novel molecular marker for evaluating the risk of HCC in patients with NASH.

Suppressive effect of the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) on hepatitis C virus replication.

The histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) has a clinical promise for treatment of cancer including hepatocellular carcinoma (HCC). To investigate effect of SAHA on hepatitis C virus (HCV) replication, we treated the HCV replicon cell OR6 with SAHA. HCV replication was significantly inhibited by SAHA at concentrations below 1 µM with no cellular toxicity. Another HDAC inhibitor, tricostatin A, also showed reduction of HCV replication. The microarray analysis and quantitative RT-PCR demonstrated up-regulation of osteopontin (OPN) and down-regulation of apolipoprotein-A1 (Apo-A1) after SAHA treatment. Direct gene induction of OPN and knockdown of Apo-A1 also showed reduction of HCV replication. The liver specific microRNA-122, which is involved in HCV replication, was not affected by SAHA treatment. These results suggest that SAHA has suppressive effect on HCV replication through alterations of gene expression such as OPN and Apo-A1 in host cells. Epigenetic treatment with HDAC inhibitors may be a novel therapeutic approach for diseases associated with HCV infection such as chronic hepatitis, liver cirrhosis, and HCC.

Establishment and Long-Term Culture of Organoids Derived from Human Biliary Tract Carcinoma.

This protocol is a procedure for establishment and culture of cancer and non-cancer organoids using tissues from biliary tract carcinoma (BTC) patients. These BTC organoids can be used for various biological analyses and drug screening. One challenge in establishing and culturing BTC organoids is non-cancer cells contaminating surgically resected tumor tissues form organoids concurrently with cancer organoids. Careful validation that the established organoids are cancer-derived is important. For complete details on the use and generation of this protocol, please refer to Saito et al. (2019) in the journal Cell Reports.

Glucose Depletion Enhances the Stem Cell Phenotype and Gemcitabine Resistance of Cholangiocarcinoma Organoids through AKT Phosphorylation and Reactive Oxygen Species.

Cancer cells are strongly dependent on the glycolytic pathway for generation of energy even under aerobic condition through a phenomenon known as the Warburg effect. Rapid proliferation of cancer cells is often accompanied by high glucose consumption and abnormal angiogenesis, which may lead to glucose depletion. In the present study, we investigated how cholangiocarcinoma cells adapt to glucose depletion using a 3D organoid culture system. We cultured organoids derived from cholangiocarcinoma under glucose-free condition and investigated cell proliferation, expression of stem cell markers and resistance to gemcitabine. Cholangiocarcinoma organoids cultured under glucose-free condition showed reduced proliferation but were able to survive. We also observed an increase in the expression of stem cell markers including LGR5 and enhancement of stem cell phenotypic characteristics such as resistance to gemcitabine through AKT phosphorylation and reactive oxygen species. These findings indicate that cholangiocarcinoma cells are able to adapt to glucose depletion through enhancement of their stem cell phenotype in response to changes in microenvironmental conditions.

Epigenetic silencing of Lgr5 induces senescence of intestinal epithelial organoids during the process of aging.

To understand the molecular features underlying stem cell aging, we established intestinal epithelial organoids derived from both young and aged mice and investigated alterations in their senescence and epigenetic status. Senescence-related changes including accumulation of senescence-associated ß-galactosidase and up-regulation of Cdkn1a (p21) by DNA demethylation were observed in intestinal epithelial organoids derived from aged mice. We also demonstrated that the important stem cell marker Lgr5 was epigenetically silenced by trimethylation of histone H3 lysine 27, inducing suppression of Wnt signaling and a decrease of cell proliferation in organoids from aged mice. We further treated intestinal epithelial organoids from aged mice with nicotinamide mononucleotide (NMN), a key NAD+ intermediate. As a result, the organoids showed a higher NAD+ level, increased cell proliferative ability, activation of Lgr5 and suppression of senescence-associated genes, indicating that treatment with NMN could ameliorate senescence-related changes in intestinal epithelia. These findings suggest that organoids derived from aged animals could be a powerful research tool for investigating the molecular mechanisms underlying stem cell aging and for development of some form of anti-aging intervention, thus contributing to prolongation of healthy life expectancy.

Erratum: Publisher Correction: Epigenetic silencing of Lgr5 induces senescence of intestinal epithelial organoids during the process of aging.

[This corrects the article DOI: 10.1038/s41514-018-0031-5.].

Establishment of Patient-Derived Organoids and Drug Screening for Biliary Tract Carcinoma.

Biliary tract carcinomas (BTCs) are among the most aggressive malignancies and have a poor prognosis. Here, we successfully established organoid lines derived from intrahepatic cholangiocarcinoma, gallbladder cancer, and neuroendocrine carcinoma of the ampulla of Vater. These organoids derived from BTCs were cultured stably for >1 year and closely recapitulated the histopathology, gene expression, and genetic alterations evident in the primary tumors. Gene expression profiling of the organoids revealed that SOX2 could be a potential prognostic biomarker for patients with BTC. We screened a compound library consisting of drugs used clinically for their ability to suppress organoids derived from BTCs and found that the antifungal drugs amorolfine and fenticonazole significantly suppressed the growth of organoids derived from BTCs with minimal toxicity to normal biliary epithelial cells. Patient-derived organoids may be a powerful research tool for the clarification of molecular pathogenesis and the discovery of biomarkers and therapeutic drugs for refractory cancers.

Genomic Profiling of Biliary Tract Cancer Cell Lines Reveals Molecular Subtypes and Actionable Drug Targets.

Biliary tract cancers (BTCs) currently have no approved targeted therapies. Although genomic profiling of primary BTCs has identified multiple potential drug targets, accurate models are needed for their evaluation. Genomic profiling of 22 BTC cell lines revealed they harbor similar mutational signatures, recurrently mutated genes, and genomic alterations to primary tumors. Transcriptomic profiling identified two major subtypes, enriched for epithelial and mesenchymal genes, which were also evident in patient-derived organoids and primary tumors. Interrogating these models revealed multiple mechanisms of MAPK signaling activation in BTC, including co-occurrence of low-activity BRAF and MEK mutations with receptor tyrosine kinase overexpression. Finally, BTC cell lines with altered ERBB2 or FGFRs were exquisitely sensitive to specific targeted agents, whereas surprisingly, IDH1-mutant lines did not respond to IDH1 inhibitors in vitro. These findings establish BTC cell lines as robust models of primary disease, reveal specific molecular disease subsets, and highlight specific molecular vulnerabilities in these cancers.

Induction of differentiation of intrahepatic cholangiocarcinoma cells to functional hepatocytes using an organoid culture system.

Intrahepatic cholangiocarcinoma (IHCC) is a highly aggressive malignancy with a poor prognosis. It is thought to originate from cholangiocytes, which are the component cells of intrahepatic bile ducts. However, as patients with viral hepatitis often develop IHCC, it has been suggested that transformed hepatocytes may play a role in IHCC development. To investigate whether IHCC cells can be converted to functional hepatocytes, we established organoids derived from human IHCC and cultured them under conditions suitable for hepatocyte differentiation. IHCC organoids after hepatocyte differentiation acquired functions of mature hepatocytes such as albumin secretion, bile acid production and increased CYP3A4 activity. Studies using a mouse model of IHCC indicate that Wnt3a derived from macrophages recruited upon inflammation in the liver may promote the malignant transformation of hepatocytes to IHCC cells. The results of the present study support the recently proposed hypothesis that IHCC cells are derived from hepatocytes.

Inhibition of DNA Methylation Suppresses Intestinal Tumor Organoids by Inducing an Anti-Viral Response.

Recent studies have proposed that the major anti-tumor effect of DNA methylation inhibitors is induction of interferon-responsive genes via dsRNAs-containing endogenous retroviruses. Recently, a 3D culture system for stem cells known as organoid culture has been developed. Lgr5-positive stem cells form organoids that closely recapitulate the properties of original tissues. To investigate the effect of DNA demethylation on tumor organoids, we have established organoids from intestinal tumors of Apc(Min/+) (Min) mice and subjected them to 5-aza-2'-deoxycytidine (5-Aza-CdR) treatment and Dnmt1 knockdown. DNA demethylation induced by 5-Aza-CdR treatment and Dnmt1 knockdown significantly reduced the cell proliferation of the tumor organoids. Microarray analyses of the tumor organoids after 5-Aza-CdR treatment and Dnmt1 knockdown revealed that interferon-responsive genes were activated by DNA demethylation. Gene ontology and pathway analyses clearly demonstrated that these genes activated by DNA demethylation are involved in the anti-viral response. These findings indicate that DNA demethylation suppresses the proliferation of intestinal tumor organoids by inducing an anti-viral response including activation of interferon-responsive genes. Treatment with DNA methylation inhibitors to activate a growth-inhibiting immune response may be an effective therapeutic approach for colon cancers.