Search

Epigenetic regulation is important for cancer tumor metastasis and progression, including lung and liver cancer. However, the mechanism of epigenetic regulation in liver cancer leaves much to be discussed. According to a previous study, p300/CBP‐associated factor (PCAF) mediated epithelial–mesenchymal transition (EMT) and promotes cancer metastasis by recruiting intestine‐specific homeobox (ISX) and bromodomain‐containing protein 4 (BRD4) in lung cancer. To figure out whether the three genes are also expressed in patients with hepatocellular carcinoma (HCC) or not, and their correlation with patients’ outcome, BRD4, PCAF, and ISX messenger RNA (mRNA) expression levels in 377 patients with HCC were investigated using quantitative polymerase chain reaction and confocal fluorescence imaging. The correlation of the gene expression (PCAF, ISX, and BRD4) in liver cancer is also being investigated. Here, we show that the mRNA expression of PCAF, BRD4, and ISX in 377 paired specimens from patients with HCC, and the adjacent normal tissues exhibited a tumor‐specific expression pattern, highly correlated with disease pathogenesis, patient survival time, progression stage, and poor prognosis. The results show that ISX and BRD4 can potentially be a target for improving the survival rate., ISX and BRD4 can potentially be a target for improving the survival rate.

The aryl hydrocarbon receptor (AHR), a major chemical sensor, is thought to play a role in various biological contexts, including cell cycle regulation and tumorigenesis. However, its regulatory mechanisms remain unclear. We propose herein a novel mechanism through which AHR promotes tumorigenesis by targeting expression of the oncogene intestine-specific homeobox (ISX) in hepatocellular carcinoma (HCC). Compared to paired tumor-adjacent tissues and non-HCC tumors, HCCs exhibited an increased and hierarchical pattern of AHR expression. Patients exhibiting high AHR expression had a significantly shorter survival duration, compared to those with low and medium expression. Functionally, AHR was found to target the newly discovered proto-oncogene, ISX, resulting in the increased expression of this gene and its downstream targets, CCND1 and E2F1. Ablation of AHR or ISX in hepatoma cells suppressed cell growth, whereas overexpression promoted cell proliferation and led to enhanced tumorigenic activity in vitro and in vivo. These results provide evidence to support a critical role for the AHR/ISX axis in HCC tumorigenesis and suggest its potential utility as a new therapeutic and prognostic target for HCC.

Introduction The intestine-specific homeobox transcription factor intestine specific homeobox (ISX) is an IL6-inducible protooncogene implicated in the development of hepatocellular carcinoma, but its mechanistic contributions to this process are undefined. Material and methods In this study, we provide evidence that ISX mediates a positive feedback loop integrating inflammation, tryptophan catabolism,and immune suppression. Results and discussions We found that ISX-mediated IL6-induced expression of the tryptophan catabolic enzymes Indoleamine2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenasein hepatocellular carcinoma cells, resulting in an ISX dependent increase in the tryptophan catabolite kynurenine and its receptor aryl hydrocarbon receptor (AHR). Activation of this kynurenine/AHR signaling axis acted through a positive feedback mechanism to increase ISX expression and enhance cellular proliferation and tumorigenic potential. RNAi-mediated attenuation of ISX or AHR reversed these effects. In an IDO1-dependent manner, ectopic expression of ISX induced expression of genes encoding the critical immune modulators CD86 (B7-2)and programmed death ligand-1 (PD-L1), through which ISX conferred a significant suppressive effect on the CD8+ T-cell response. In hepatocellular carcinoma specimens, expression of IDO1, kynurenine, AHR, and PD-L1 correlated negatively with survival. Conclusion Overall, our results identified a feed-forward mechanism of immune suppression in hepatocellular carcinoma organized by ISX, which involves kynurenine-AHR signaling and PD-L1, offering insights into immune escape by hepatocellular carcinoma, which may improve its therapeutic management

Introduction The epithelial–mesenchymal transition (EMT) is an important process in the progression of cancer, but its occurrence and the regulatory mechanism are not fully understood. Material and methods In this study, Intestine specific homeobox (ISX) acted both as an proto-oncogene and upstream regulator of EMT markers, by which modulates tumorigenic initiation and progression in lung cancer cells. Results and discussions Mechanistically, ISX acetylated by p300/CBP- associated factor (PCAF) recruits chromatin reader, bromodomain- containing protein 4 (BRD4), to initiate chromatin remodelling, and upregulated EMT downstream regulators in tumours cells. Ectopic expression of ISX were shown to enhance TWIST1, Snail1, vascular endothelial growth factor (VEGF) expression by recruiting BRD4 to enhance Pol II-dependent transcription, leading to remodelling of the tumour microenvironment. Neutralising VEGF by avastin effectively abrogates metastasis induced by the ISX-BRD4 complex. In NSCLC carcinoma samples, significantly increased ISX expression was noted, correlating with distinct clinical metastatic features and poor prognosis. Conclusion These results suggest that the ISX-BRD4 axis mediates EMT signalling and exerts significant regulatory effects on tumour initiation and metastasis.

The epithelial-mesenchymal transition is an important process in the cancer progression, but its occurrence and the regulatory mechanism are not fully understood. Intestine specific homeobox acted both as a proto-oncogene and upstream regulator of EMT markers, by which modulates tumorigenic initiation and progression in lung cancer cells. ISX acetylated by PCAF recruits bromodomain-containing protein 4, to initiate chromatin remodeling, and up-regulated EMT downstream regulators in tumors cells. Ectopic expression of ISX was shown to enhance TWIST1, Snail1 expression by recruiting BRD4 to enhance Pol II dependent transcription, lead in to remodeling of the tumor microenvironment. In NSCLC carcinoma, increased ISX expression was noted correlating with distinct clinical metastatic features and poor prognosis. These results suggest that theISX-BRD4 axis mediates EMT signaling and exerts significant regulatory effects on tumor initiation and metastasis. Citation Format: Li-Ting Wang, Shyh-Shin Chiou, Shih-Hsien Hsu. Intestine-specific homeobox recruits p300/CBP-associated factor and bromodomain-containing protein 4 to promote epithelial-mesenchymal transition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1108.

// Shen-Nien Wang 1, 2, * , Li-Ting Wang 2, * , Ding-Ping Sun 3, 4, * , Chee-Yin Chai 5 , Edward Hsi 6 , Hsing-Tao Kuo 7, 8 , Kazunari K. Yokoyama 2, 9, 10, 11, 12, 13 , Shih-Hsien Hsu 2, 13 1 Division of Hepatobiliary Surgery, Department of Surgery, Faculty of Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan 2 Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan 3 Division of General Surgery, Department of Surgery, Chi-Mei Medical Center, Tainan, Taiwan 4 Department of Food Science and Technology, Chia Nan University of Pharmacy and Science, Tainan, Taiwan 5 Department of Pathology, Faculty of Medicine, College of Medicine, Kaohsiung, Taiwan 6 Department of Genome Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan 7 Department of Internal Medicine, Division of Hepatogastroenterology, Chi-Mei Medical Center, Tainan, Taiwan 8 Department of Senior Citizen Service Management, Chia Nan University of Pharmacy & Science, Tainan, Taiwan 9 Research Center for Stem Cell Research, Kaohsiung Medical University, Kaohsiung, Taiwan 10 Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan 11 Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan 12 Faculty of Science and Engineering, Tokushima Bunri University, Sanuki, Japan 13 Center of Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan * These authors have contributed equally to this work Correspondence to: Shih-Hsien Hsu, e-mail: jackhsu@kmu.edu.tw Kazunari K. Yokoyama, e-mail: kazu@kmu.edu.tw Hsing-Tao Kuo, e-mail: kuohsu2003@yahoo.com.tw Keywords: cyclin D1 , DP1, E2F1 , hepatocellular carcinoma (HCC), ISX Received: October 05, 2015 Accepted: April 16, 2016 Published: May 09, 2016 ABSTRACT Intestine-specific homeobox ( ISX ), a newly identified proto-oncogene, is involved in cell proliferation and progression of hepatocellular carcinoma (HCC). However, the underlying mechanisms linking gene expression and tumor formation remain unclear. In this study, we found that ISX transcriptionally activated E2F transcription factor 1 ( E2F1 ) and associated oncogenic activity by directly binding to the E2 site of its promoter. Forced expression of ISX increased the expression of and phosphorylated the serine residue at position 332 of E2F1 , which may be translocated into the nucleus to form the E2F1 –DP-1 complex, suggesting that the promotion of oncogenic activities of the ISX–E2F1 axis plays a critical role in hepatoma cells. Coexpression of ISX and E2F1 significantly promoted p53 and RB-mediated cell proliferation and anti-apoptosis, and repressed apoptosis and autophagy. In contrast, short hairpin RNAi-mediated attenuation of ISX and E2F1 decreased cell proliferation and malignant transformation, respectively, in hepatoma cells in vitro and in vivo . The mRNA expression of E2F1 and ISX in 238 paired specimens from human HCC patients, and the adjacent, normal tissues exhibited a tumor-specific expression pattern which was highly correlated with disease pathogenesis, patient survival time, progression stage, and poor prognosis. Therefore, our results indicate that E2F1 is an important downstream gene of ISX in hepatoma progression.

Helicobacter pylori induces chronic inflammation and intestinal metaplasia (IM) through genetic and epigenetic changes and activation of intracellular signaling pathways that contribute to gastric carcinogenesis. However, the precise mechanism of IM in gastric carcinogenesis has not been fully elucidated. We previously found that intestine-specific homeobox (ISX) mRNA expression increased in organoids cultured from Helicobacter-infected mouse mucosa. In this study, we elucidate the role of ISX in the development of IM and gastric carcinogenesis. ISX expression was assessed in Helicobacter-infected mouse and human gastric mucosa. MKN45 gastric cancer cells were co-cultured with H. pylori to determine whether Helicobacter infection induced ISX expression. We established stable MKN45 transfected cells expressing ISX (Stable-ISX MKN45) and performed a spheroid colony formation assay and a xenograft model. We performed ISX immunohistochemistry in cancer and adjacent gastric tissues. ISX expression was increased in mouse and human gastric mucosa infected with Helicobacter. The presence of IM and H. pylori infection in human stomach was correlated with ISX expression. H. pylori induced ISX mRNA and protein expression. CDX1/2, cyclinD1, and MUC2 were upregulated in Stable-ISX MKN45, whereas MUC5AC was downregulated. Stable-ISX MKN45 cells formed more spheroid colonies, and had high tumorigenic ability. ISX expression in gastric cancer and adjacent mucosa were correlated. ISX expression induced by H. pylori infection may lead to IM and hyperproliferation of gastric mucosa through CDX1/2 and cyclinD1 expression, contributing to gastric carcinogenesis.

Intestine-specific homeobox (ISX), a newly identified proto-oncogene, is known to regulate cell proliferation and drive hepatocellular carcinoma (HCC) formation; however, the underlying mechanisms linking gene expression and tumor formation remain obscure. In this study, we showed that ISX transcriptionally activates E2F1 expression and related oncogenic activity by directly binding to its promoter region. Mechanistically, forced ISX expression upregulated the expression and nucleus translocation of the E2F1-DP1 complex phosphorylated by the cyclin D1-CDKs complex, which promoted oncogenic activities of ISX-E2F1 axis in hepatoma cells. In addition, co-expression of both ISX and E2F1 significantly promoted cell proliferation and anti-apoptotic signals instead of apoptosis and autophagy induced by the tumor suppressors p53 and RB1. In contrast, short hairpin RNA-mediated attenuation of ISX and E2F1, respectively, in hepatoma cells decreased cell proliferation and malignant transformation in vitro and in vivo. The mRNA expression was compared in 238 paired specimens of HCC and adjacent normal tissues, and E2F1, as an expression of ISX, pathologically exhibited a tumor-specific expression pattern and was highly correlated with ISX expression, patient survival time, progression stage, and poor prognosis. Taken together, our results highlight that E2F1 is an important downstream gene of ISX in hepatoma progression. Citation Format: Shen-Nien Wang, Li-Ting Wang, Shih-Hsien Hsu. Intestine-specific homeobox (ISX) upregulates E2F1 expression and related oncogenic activities in HCC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2275.

Environmental pollutants often cause diseases. Aryl hydrocarbon receptor (AHR), a major transcriptional factor in the xenobiotic response, regulates cellular signaling and metabolism, thereby influencing disease progression. The detailed regulatory mechanisms, however, remain unclear. Here we demonstrate that AHR expression promotes tumorigenesis and is associated with shorter survival time in HCC patients. These phenomena appear to be mediated by activation of a target proto-oncogene, intestine-specific homeobox (ISX), in vitro and in vivo. The strong correlation of expression and cellular transcriptional regulation between AHR and ISX (in tumor and hepatoma cells) underscore the significant role of this duo in HCC tumorigenesis and prognosis. Our experiments with the ablation of ISX expression in AHR-mutant mice and hepatoma cells further support the essential roles of AHR and ISX in liver and tumor development. These results advance the understanding of the cellular function of AHR and of its downstream gene, ISX, in HCC progression. Our data may help to develop a new therapeutic approach to HCC. Citation Format: Li-Ting Wang, Shen-Nien Wang, Shih-Hsien Hsu. Aryl hydrocarbon receptor, a receptor for environmental pollutants, promotes tumorigenesis via intestine-specific homeobox expression in hepatocellular carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5603. doi:10.1158/1538-7445.AM2014-5603