Shoichiro Tange

MEG3 Long Noncoding RNA Contributes to the Epigenetic Regulation of Epithelial-Mesenchymal Transition in Lung Cancer Cell Lines.

Histone methylation is implicated in a number of biological and pathological processes, including cancer development. In this study, we investigated the molecular mechanism for the recruitment of Polycomb repressive complex-2 (PRC2) and its accessory component, JARID2, to chromatin, which regulates methylation of lysine 27 of histone H3 (H3K27), during epithelial-mesenchymal transition (EMT) of cancer cells. The expression of MEG3 long noncoding RNA (lncRNA), which could interact with JARID2, was clearly increased during transforming growth factor-β (TGF-β)-induced EMT of human lung cancer cell lines. Knockdown of MEG3 inhibited TGF-β-mediated changes in cell morphology and cell motility characteristic of EMT and counteracted TGF-β-dependent changes in the expression of EMT-related genes such as CDH1, ZEB family, and the microRNA-200 family. Overexpression of MEG3 influenced the expression of these genes and enhanced the effects of TGF-β in their expressions. Chromatin immunoprecipitation (ChIP) revealed that MEG3 regulated the recruitment of JARID2 and EZH2 and histone H3 methylation on the regulatory regions of CDH1 and microRNA-200 family genes for transcriptional repression. RNA immunoprecipitation and chromatin isolation by RNA purification assays indicated that MEG3 could associate with JARID2 and the regulatory regions of target genes to recruit the complex. This study demonstrated a crucial role of MEG3 lncRNA in the epigenetic regulation of the EMT process in lung cancer cells.

KDM5B histone demethylase controls epithelial-mesenchymal transition of cancer cells by regulating the expression of the microRNA-200 family.

Histone methylation is implicated in various biological and pathological processes including cancer development. In this study, we discovered that ectopic expression of KDM5B, a histone H3 lysine 4 (H3K4) demethylase, promoted epithelial-mesenchymal transition (EMT) of cancer cells. KDM5B increased the expression of transcription factors, ZEB1 and ZEB2, followed by downregulation of E-cadherin and upregulation of mesenchymal marker genes. The expression of the microRNA-200 (miR-200) family, which specifically targets ZEB1 and ZEB2, was reduced in the cells with KDM5B overexpression. We found that KDM5B repressed the expression of the miR-200 family by changing histone H3 methylation status of their regulatory regions. The introduction of miR-200 precursor in the cells inhibited EMT induction by KDM5B, suggesting that miR-200 family was a critical downstream mediator of KDM5B-promoted EMT. Furthermore, knockdown of KDM5B was shown to affect the expression of EMT-related genes, indicating the involvement of endogenous KDM5B. Our study demonstrated a novel role of KDM5B histone lysine demethylase in EMT, which may contribute to malignant progression of cancer.

JARID2 is involved in transforming growth factor-beta-induced epithelial-mesenchymal transition of lung and colon cancer cell lines.

Histone methylation plays a crucial role in various biological and pathological processes including cancer development. In this study, we discovered that JARID2, an interacting component of Polycomb repressive complex-2 (PRC2) that catalyzes methylation of lysine 27 of histone H3 (H3K27), was involved in Transforming Growth Factor-beta (TGF-ß)-induced epithelial-mesenchymal transition (EMT) of A549 lung cancer cell line and HT29 colon cancer cell line. The expression of JARID2 was increased during TGF-ß-induced EMT of these cell lines and knockdown of JARID2 inhibited TGF-ß-induced morphological conversion of the cells associated with EMT. JARID2 knockdown itself had no effect in the expression of EMT-related genes but antagonized TGF-ß-dependent expression changes of EMT-related genes such as CDH1, ZEB family and microRNA-200 family. Chromatin immunoprecipitation assays showed that JARID2 was implicated in TGF-ß-induced transcriptional repression of CDH1 and microRNA-200 family genes through the regulation of histone H3 methylation and EZH2 occupancies on their regulatory regions. Our study demonstrated a novel role of JARID2 protein, which may control PRC2 recruitment and histone methylation during TGF-ß-induced EMT of lung and colon cancer cell lines.

EED regulates epithelial-mesenchymal transition of cancer cells induced by TGF-β.

Histone methylation is involved in various biological and pathological processes including cancer development. In this study, we found that EED, a component of Polycomb repressive complex-2 (PRC2) that catalyzes methylation of lysine 27 of histone H3 (H3K27), was involved in epithelial-mesenchymal transition (EMT) of cancer cells induced by Transforming Growth Factor-beta (TGF-β). The expression of EED was increased during TGF-β-induced EMT and knockdown of EED inhibited TGF-β-induced morphological conversion of the cells associated with EMT. EED knockdown antagonized TGF-β-dependent expression changes of EMT-related genes such as CDH1, ZEB1, ZEB2 and microRNA-200 (miR-200) family. Chromatin immunoprecipitation assays showed that EED was implicated in TGF-β-induced transcriptional repression of CDH1 and miR-200 family genes through the regulation of histone H3 methylation and EZH2 occupancies on their regulatory regions. Our study demonstrated a novel role of EED, which regulates PRC2 activity and histone methylation during TGF-β-induced EMT of cancer cells.

Roles of histone methyl‐modifying enzymes in development and progression of cancer

Retroviral insertional mutagenesis in mice is considered a powerful forward genetic strategy to identify disease genes involved in cancer. Our high‐throughput screens led to frequent identification of the genes encoding the enzymes engaged in histone lysine methylation. Histone methylation can positively or negatively impact on gene transcription, and then fulfill important roles in developmental control and cell‐fate decisions. A tremendous amount of progress has accelerated the characterization of histone methylations and the enzymes that regulate them. Deregulation of these histone methyl‐modifying enzymes has been increasingly recognized as a hallmark of cancer in the last few years. However, in most cases, we have only limited understanding for the molecular mechanisms by which these enzymes contribute to cancer development and progression. In this review, we summarize the current knowledge regarding some of the best‐validated examples of histone lysine methyltransferases and demethylases associated with oncogenesis and discuss their potential mechanisms of action.

DOT1L histone methyltransferase regulates the expression of BCAT1 and is involved in sphere formation and cell migration of breast cancer cell lines

DOT1L is a histone H3 lysine 79 (H3K79) methyltransferase mainly implicated in leukemia. Here we analyzed the function of DOT1L in breast cancer cells. The expression of DOT1L was up-regulated in malignant breast cancer tissues. Over-expression of DOT1L significantly increased the sphere formation and the cell migration activities of MCF7 breast cancer cell line. In contrast, knockdown of DOT1L reduced the cell migration activity of MDA-MB-231 breast cancer cell line. BCAT1, which encodes a branched-chain amino acid transaminase, was identified as one of the target genes controlled by DOT1L through the regulation of H3K79 methylation. Mechanistic investigation revealed that BCAT1 might be an important regulator responsible for DOT1L-mediated sphere formation and cell migration in breast cancer cells.

Jmjd5 functions as a regulator of p53 signaling during mouse embryogenesis

Genetic studies have shown that aberrant activation of p53 signaling leads to embryonic lethality. Maintenance of a fine balance of the p53 protein level is critical for normal development. Previously, we have reported that Jmjd5, a member of the Jumonji C (JmjC) family, regulates embryonic cell proliferation through the control of Cdkn1a expression. Since Cdkn1a is the representative p53-regulated gene, we have examined whether the expression of other p53 target genes is coincidentally upregulated with Cdkn1a in Jmjd5-deficient embryos. The expression of a subset of p53-regulated genes was increased in both Jmjd5 hypomorphic mouse embryonic fibroblasts (MEFs) and Jmjd5-deficient embryos at embryonic day 8.25 without the induced expression of Trp53. Intercrossing of Jmjd5-deficient mice with Trp53 knockout mice showed that the growth defect of Jmjd5 mutant cells was significantly recovered under a Trp53 null genetic background. Chromatin immunoprecipitation analysis in Jmjd5 hypomorphic MEFs indicated the increased recruitment of p53 at several p53 target gene loci, such as Cdkn1a, Pmaip1, and Mdm2. These results suggest that Jmjd5 is involved in the transcriptional regulation of a subset of p53-regulated genes, possibly through the control of p53 recruitment at the gene loci. In Jmjd5-deficient embryos, the enhanced recruitment of p53 might result in the abnormal activation of p53 signaling leading to embryonic lethality.

Foretinib Overcomes Entrectinib Resistance Associated with the NTRK1 G667C Mutation in NTRK1 Fusion–Positive Tumor Cells in a Brain Metastasis Model

Purpose: Rearrangement of the neurotrophic tropomyosin receptor kinase 1 (NTRK1) gene, which encodes tyrosine receptor kinase A (TRK-A), occurs in various cancers, including colon cancer. Although entrectinib is effective in the treatment of central nervous system (CNS) metastases that express NTRK1 fusion proteins, acquired resistance inevitably results in recurrence. The CNS is a sanctuary for targeted drugs; however, the mechanism by which CNS metastases become entrectinib-resistant remains elusive and must be clarified to develop better therapeutics. Experimental Design: The entrectinib-resistant cell line KM12SM-ER was developed by continuous treatment with entrectinib in the brain metastasis–mimicking model inoculated with the entrectinib-sensitive human colon cancer cell line KM12SM, which harbors the TPM3-NTRK1 gene fusion. The mechanism of entrectinib resistance in KM12SM-ER cells was examined by next-generation sequencing. Compounds that overcame entrectinib resistance were screened from a library of 122 kinase inhibitors. Results: KM12SM-ER cells, which showed moderate resistance to entrectinib in vitro, had acquired the G667C mutation in NTRK1. The kinase inhibitor foretinib inhibited TRK-A phosphorylation and the viability of KM12SM-ER cells bearing the NTRK1-G667C mutation in vitro. Moreover, foretinib markedly inhibited the progression of entrectinib-refractory KM12SM-ER–derived liver metastases and brain tumors in animal models, predominantly through inhibition of TRK-A phosphorylation. Conclusions: These results suggest that foretinib may be effective in overcoming entrectinib resistance associated with the NTRK1-G667C mutation in NTRK1 fusion–positive tumors in various organs, including the brain, and provide a rationale for clinical trials of foretinib in cancer patients with entrectinib-resistant tumors harboring the NTRK1-G667C mutation, including patients with brain metastases. Clin Cancer Res; 24(10); 2357–69. ©2018 AACR.

In vivo imaging xenograft models for the evaluation of anti-brain tumor efficacy of targeted drugs

Molecular‐targeted drugs are generally effective against tumors containing driver oncogenes, such as EGFR, ALK, and NTRK1. However, patients harboring these oncogenes frequently experience a progression of brain metastases during treatment. Here, we present an in vivo imaging model for brain tumors using human cancer cell lines, including the EGFR‐L858R/T790M‐positive H1975 lung adenocarcinoma cells, the NUGC4 hepatocyte growth factor (HGF)‐dependent gastric cancer cells, and the KM12SM colorectal cancer cells containing the TPM3‐NTRK1 gene fusion. We investigated the efficacy of targeted drugs by comparison with their effect in extracranial models. In vitro, H1975 cells were sensitive to the third‐generation epidermal growth factor receptor inhibitor osimertinib. Moreover, HGF stimulated the proliferation of NUGC4 cells, that was inhibited by crizotinib, which has anti‐MET activity. KM12SM cells were sensitive to the tropomyosin‐related kinase‐A inhibitors crizotinib and entrectinib. In in vivo H1975 cell models, osimertinib inhibited the progression of both brain and subcutaneous tumors. Furthermore, in in vivo NUGC4 cell models, crizotinib remarkably delayed the progression of brain tumors, and that of peritoneal carcinomatosis. Interestingly, in in vivo KM12SM cell models, treatment with crizotinib delayed the progression of liver metastases, but not that of brain tumors. Conversely, treatment with entrectinib discernibly delayed the progression of both tumor types. Thus, the effect of targeted drugs against brain tumors can differ from the one reported in extracranial tumors. Moreover, the same multikinase inhibitory drug can display different efficacies in brain tumor models containing different drivers. Therefore, our in vivo imaging model for brain tumors may prove useful for preclinical drug screening against brain metastases.