Zinc-fingers And Homeoboxes 1 Research Articles

Characterization of circSEC11A as a novel regulator of Iodine-125 radioactive seed-induced anticancer effects in hepatocellular carcinoma via targeting ZHX2/GADD34 axis

Iodine-125 (I-125) radioactive seed implantation is used for the local treatment of hepatocellular carcinoma (HCC), but the molecular mechanisms regulating its anticancer effects remain incompletely understood. In this study, we report that hsa_circ_0000647 (circSEC11A) is highly expressed after I-125 treatment in HCC cell lines and tissues and is a key regulator of I-125-induced anticancer effects. CircSEC11A acts as a competing endogenous RNA (ceRNA) to sponge miR-3529-3p, promoting the expression of zinc fingers and homeoboxes 2 (ZHX2) and enhancing I-125-induced anticancer effects. Dual-luciferase reporter assay, RNA pull-down, RNA immunoprecipitation, and fluorescence in situ hybridization were thereafter performed to verify the interaction among the molecules. Anticancer effects were detected using CCK-8, flow cytometry, TUNEL, EdU, transwell, and wound healing assays. Furthermore, ZHX2 transcriptionally inhibits GADD34, a negative regulator of endoplasmic reticulum stress (ERS), to enhance I-125- induced anticancer effects in vivo and in vitro. In conclusion, we characterized circSEC11A as a novel regulator of I-125-induced anticancer effects in HCC via miR-3529-3p/ZHX2/GADD34 axis-mediated ERS. Thus, circSEC11A may act as a potential therapeutic target for I-125 implantation in the clinic.

Abstract P4-08-23: ZHX2 promotes HIF1α oncogenic signaling in triple-negative breast cancer

Abstract Background: Triple-negative breast cancer (TNBC) is an aggressive and highly lethal disease in women, while the oncogenic mechanisms which contribute to TNBC development, progression, and metastasis are poorly investigated and therefore warrant the critical need to identify novel oncogenic signalings and develop new therapeutic targets. Results: We show that Zinc Fingers and Homeoboxes 2 (ZHX2) is amplified or overexpressed in TNBC cell lines and patients. Functionally, depletion of ZHX2 inhibited TNBC cell growth and invasion in vitro, orthotopic tumor growth, and spontaneous lung metastasis in vivo. Mechanistically, ZHX2 bound with hypoxia-inducible factor (HIF) family members and positively regulated HIF1α protein level and activity in TNBC. Integrated ChIP-seq and gene expression profiling demonstrated that ZHX2 co-occupied with HIF1α on transcriptionally active promoters marked by H3K4me3 and H3K27ac, thereby promoting gene expression. Among the identified ZHX2 and HIF1α coregulated genes, overexpression of AP2B1, COX20, KDM3A, or PTGES3L could partially rescue TNBC cell growth defect by ZHX2 depletion, suggesting that these downstream targets contribute to the oncogenic role of ZHX2 in an accumulative fashion. Furthermore, multiple residues (R491, R581, and R674) on ZHX2 are important in regulating its phenotype, which correspond with their roles in controlling ZHX2 transcriptional activity in TNBC cells. These studies establish that ZHX2 activates oncogenic HIF1α signaling, therefore serving as a potential therapeutic target for TNBC. Conclusion: ZHX2 has been highlighted as one critical hypoxia-related factors regulator contributing to triple-negative breast cancer in this work, which has enriched the upstream regulatory network of HIF-1α signaling. Moreover, identification of key residuals determining biological function of ZHX2 provides novel approaches for treating TNBC via targeting the hypoxia pathway. Citation Format: Chengheng Liao, Wentong Fang, Rachel Shi, Jeremy Simon, Travis Ptacek, Giada Zurlo, Youqiong Ye, Leng Han, Cheng Fan, Lei Bao, Christopher Llynard Ortiz, Hong-Rui Lin, Ujjawal Manocha, Weibo Luo, Yan Peng, William Y Kim, Lee-Wei Yang, Qing Zhang. ZHX2 promotes HIF1α oncogenic signaling in triple-negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-08-23.

ZHX2 in health and disease.

As a transcriptional factor and the negative regulator of alpha fetal protein (AFP), Zinc fingers and homeoboxes 2 (ZHX2) has a well-established role in protection against hepatocellular carcinoma (HCC). However, recent studies have suggested ZHX2 as an oncogene in clear cell renal cell carcinoma (ccRCC) and triple-negative breast cancer (TNBC). Moreover, mounting evidence has illustrated a much broader role of ZHX2 in multiple cellular processes, including cell proliferation, cell differentiation, lipid metabolism, and immunoregulation. This comprehensive review emphasizes the role of ZHX2 in health and diseases which have been more recently uncovered.

Abstract PO023: Uncovering hepatitis B virus-induced signaling changes in hepatocellular carcinoma

Abstract Although precision medicine has revolutionized the treatment for other solid tumors, comprehensive genome profiling of hepatocellular carcinoma (HCC) has demonstrated that there are few oncogenic mutational drivers. HCC arises nearly universally in the context of co-morbid hepatitis, driven by hepatitis C virus or hepatitis B virus (HBV). Previous work has highlighted the effects of HBV protein X (HBx) on signaling and proliferation. However, it remains unclear how these signaling changes interact with the stress imposed by HBV replication. We hypothesize that HBV replication and maintenance of HBV proteins like HBx creates specific vulnerabilities that can be uncovered and exploited. We performed whole-genome clustered regularly interspaced short palindromic repeat interference (CRISPRi) screening in two engineered, patient-derived HBV+ cell models, Hep3B and SNU-368, with cellular proliferation as the readout. A conditional induction of HBx was used to overexpress HBx in each cell model for the whole genome CRISPRi screen. Genes where HBx expression was significantly associated with a more negative dependency score were classified as HBV differential dependencies. 37 genes were identified as shared HBV-induced dependencies across both cell lines. Of these, 16 were also differentially expressed in HCC specimens with ongoing HBV replication vs. non-HBV expressing tumors collected in The Cancer Genome Atlas (TCGA), suggesting in vivo selective pressure to alter the expression of these genes. We focused on Zinc Fingers and Homeoboxes 2 (ZHX2) and methionine adenosyltransferase 2A (MAT2A). ZHX2 was identified as an HCC tumor suppressor, and data from TCGA showed differential gene expression of ZHX2 in HBV+HCC. Validation of ZHX2 sgRNA knockdown confirmed that ZHX2 knockdown preferentially reduced cell proliferation in the presence of HBx, consistent with an HBV-induced dependency. ZHX2 also can activate the HIF pathway; we identified alterations of HIF targets with ZHX2 knockdown and HBx expression. Similarly, MAT2A knockdown in HBV+HCC cell lines showed decreased cell proliferation with HBx expression. MAT2A is an emerging therapeutic target, with sensitivity to MAT2A inhibitors conferred by deletions in methylthioadenosine phosphorylase (MTAP), seen in 3% of HCC. Ongoing investigations include alteration of splicing and cell cycle changes with depletion of MAT2A in the presence of HBx. With small molecule inhibitors of MAT2A in clinical development, this finding may be therapeutically actionable. Thus, using functional genomics to interrogate HBV-associated gene dependencies has illuminated the biology of HCC and identified candidate therapeutic targets for pre-clinical validation. Citation Format: Rigney E Turnham, Huat Chye Lim, Lucille Ferret, Katherine Lo, LeeAnn Wang, Alex Choi, John D Gordan. Uncovering hepatitis B virus-induced signaling changes in hepatocellular carcinoma [abstract]. In: Proceedings of the AACR Special Conference: Advances in the Pathogenesis and Molecular Therapies of Liver Cancer; 2022 May 5-8; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(17_Suppl):Abstract nr PO023.

USP13 promotes deubiquitination of ZHX2 and tumorigenesis in kidney cancer

Clear cell renal cell carcinoma (ccRCC) is characterized by the loss of tumor suppressor Von Hippel Lindau (VHL) function. VHL is the component of an E3 ligase complex that promotes the ubiquitination and degradation of hypoxia inducible factor α (HIF-α) (including HIF1α and HIF2α) and Zinc Fingers And Homeoboxes 2 (ZHX2). Our recent research showed that ZHX2 contributed to ccRCC tumorigenesis in a HIF-independent manner. However, it is still unknown whether ZHX2 could be modified through deubiquitination even in the absence of pVHL. Here, we performed a deubiquitinase (DUB) complementary DNA (cDNA) library binding screen and identified USP13 as a DUB that bound ZHX2 and promoted ZHX2 deubiquitination. As a result, USP13 promoted ZHX2 protein stability in an enzymatically dependent manner, and depletion of USP13 led to ZHX2 down-regulation in ccRCC. Functionally, USP13 depletion led to decreased cell proliferation measured by two-dimensional (2D) colony formation and three-dimensional (3D) anchorage-independent growth. Furthermore, USP13 was essential for ccRCC tumor growth invivo, and the effect was partially mediated by its regulation on ZHX2. Our findings support that USP13 may be a key effector in ccRCC tumorigenesis.

Novel regulation of the transcription factor ZHX2 by N-terminal methylation

ABSTRACT N-terminal methylation (Nα-methylation) by the methyltransferase NRMT1 is an important post-translational modification that regulates protein–DNA interactions. Accordingly, its loss impairs functions that are reliant on such interactions, including DNA repair and transcriptional regulation. The global loss of Nα-methylation results in severe developmental and premature aging phenotypes, but given over 300 predicted substrates, it is hard to discern which physiological substrates contribute to each phenotype. One of the most striking phenotypes in NRMT1 knockout (Nrmt1−/− ) mice is early liver degeneration. To identify the disrupted signaling pathways leading to this phenotype and the NRMT1 substrates involved, we performed RNA-sequencing analysis of control and Nrmt1−/− adult mouse livers. We found both a significant upregulation of transcripts in the cytochrome P450 (CYP) family and downregulation of transcripts in the major urinary protein (MUP) family. Interestingly, transcription of both families is inversely regulated by the transcription factor zinc fingers and homeoboxes 2 (ZHX2). ZHX2 contains a non-canonical NRMT1 consensus sequence, indicating that its function could be directly regulated by Nα-methylation. We confirmed misregulation of CYP and MUP mRNA and protein levels in Nrmt1−/− livers and verified NRMT1 can methylate ZHX2 in vitro. In addition, we used a mutant of ZHX2 that cannot be methylated to directly demonstrate Nα-methylation promotes ZHX2 transcription factor activity and target promoter occupancy. Finally, we show Nrmt1−/− mice also exhibit early postnatal de-repression of ZHX2 targets involved in fetal liver development. Taken together, these data implicate ZHX2 misregulation as a driving force behind the liver phenotype seen in Nrmt1−/− mice.

LINC01431 Promotes Histone H4R3 Methylation to Impede HBV Covalently Closed Circular DNA Transcription by Stabilizing PRMT1.

Covalently closed circular DNA (cccDNA) is the transcriptional template of hepatitis B virus (HBV), which interacts with both host and viral proteins to form minichromosome in the nucleus and is resistant to antiviral agents. Identification of host factors involved in cccDNA transcriptional regulation is expected to prove a new venue for HBV therapy. Recent evidence suggests the involvement of long noncoding RNAs (lncRNAs) in mediating the interaction of host factors with various viruses, however, lncRNAs that HBV targets and represses cccDNA transcription have not been fully elucidated. Here, the authors identified LINC01431 as a novel host restriction factor for HBV transcription. Mechanically, LINC01431 competitively bound with type I protein arginine methyltransferase (PRMT1) to block the HBx‐mediated PRMT1 ubiquitination and degradation. Consequently, LINC01431 increased the occupancy of PRMT1 on cccDNA, leading to enhanced H4R3me2a modification and reduced acetylation of cccDNA‐bound histones, thereby repressing cccDNA transcription. In turn, to facilitate viral replication, HBV transcriptionally repressed LINC01431 expression by HBx‐mediated repression of transcription factor Zinc fingers and homeoboxes 2 (ZHX2). Collectively, the study demonstrates LINC01431 as a novel epigenetic regulator of cccDNA minichromosome and highlights a feedback loop of HBx‐LINC01431‐PRMT1 in HBV replication, which provides potential therapeutic targets for HBV treatment.

The transcription factor zinc fingers and homeoboxes 2 alleviates NASH by transcriptional activation of phosphatase and tensin homolog.

NASH, which is a common clinical condition predisposing to advanced liver diseases, has become a worldwide epidemic. A large and growing unmet therapeutic need for this condition reflects incomplete understanding of its pathogenesis. In the current study, we identified a transcription factor, zinc fingers and homeoboxes 2 (ZHX2), in hepatocytes as a protective factor against steatohepatitis. We found that hepatic ZHX2 was significantly suppressed in NASH models and steatotic hepatic cells. Hepatocyte-specific ablation of ZHX2 exacerbated NASH-related phenotypes in mice, including lipid accumulation, enhanced inflammation, and hepatic fibrosis. Conversely, hepatocyte-specific overexpression of ZHX2 significantly alleviated the progression of NASH in an experimental setting. Integrated analysis of transcriptomic profiling and chromatin immunoprecipitation sequencing data demonstrated that the phosphatase and tensin homolog (PTEN) was a target gene of ZHX2 in hepatocyte. ZHX2 bound to the promoter of PTEN gene and subsequently promoted the transcription of PTEN, which mediated the beneficial role of ZHX2 against NASH. The current findings demonstrate a protective role of ZHX2 against NASH progression by transcriptionally activating PTEN. These findings shed light on the therapeutic potential of targeting ZHX2 for treating NASH and related metabolic disorders.

ZHX2 inhibits thyroid cancer metastasis through transcriptional inhibition of S100A14

BackgroundThyroid cancer is the most common malignant endocrine tumour, and metastasis has become the main reason for treatment failure. However, the underlying molecular mechanism of thyroid cancer metastasis remains poorly understood. We investigated the role of the tumour suppressor zinc fingers and homeoboxes 2 (ZHX2) in the metastasis of thyroid cancer.MethodsTo study the role of ZHX2 in thyroid cancer metastasis, we evaluated the EMT process using cell migration, wound healing and lung metastatic tumour formation in vitro and in vivo models.ResultsZHX2 expression was significantly decreased in thyroid cancer tissues, which correlated with poor prognosis of thyroid cancer patients. ZHX2 knockdown significantly promoted the migration of thyroid cancer cells. Mechanistically, ZHX2 associated with the S100 calcium binding protein A14 (S100A14) promoter to decrease the transcription of S100A14. Moreover, S100A14 was highly expressed in human thyroid cancer samples, and its expression negatively correlated with ZHX2 expression.ConclusionsInhibition of S100A14 attenuated the ZHX2 knockdown-induced enhanced metastasis of thyroid cancer cells both in vitro and in vivo. The evidence presented here suggests that ZHX2 inhibits the progression of thyroid cancer by blocking S100A14-mediated metastasis.

ZHX2 promotes HIF1α oncogenic signaling in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is an aggressive and highly lethal disease, which warrants the critical need to identify new therapeutic targets. We show that Zinc Fingers and Homeoboxes 2 (ZHX2) is amplified or overexpressed in TNBC cell lines and patients. Functionally, depletion of ZHX2 inhibited TNBC cell growth and invasion in vitro, orthotopic tumor growth, and spontaneous lung metastasis in vivo. Mechanistically, ZHX2 bound with hypoxia-inducible factor (HIF) family members and positively regulated HIF1α activity in TNBC. Integrated ChIP-seq and gene expression profiling demonstrated that ZHX2 co-occupied with HIF1α on transcriptionally active promoters marked by H3K4me3 and H3K27ac, thereby promoting gene expression. Among the identified ZHX2 and HIF1α coregulated genes, overexpression of AP2B1, COX20, KDM3A, or PTGES3L could partially rescue TNBC cell growth defect by ZHX2 depletion, suggested that these downstream targets contribute to the oncogenic role of ZHX2 in an accumulative fashion. Furthermore, multiple residues (R491, R581, and R674) on ZHX2 are important in regulating its phenotype, which correspond with their roles on controlling ZHX2 transcriptional activity in TNBC cells. These studies establish that ZHX2 activates oncogenic HIF1α signaling, therefore serving as a potential therapeutic target for TNBC.

Novel VHL substrate targets SFMBT1 and ZHX2 may be important prognostic predictors in patients with ccRCC.

Renal cell carcinoma is one of the most malignant cancers, with limited prognostic prediction system. The present study aimed to determine the prognostic value of novel von Hippel-Lindau (VHL) substrate targets in predicting the outcome of clear cell renal cell carcinoma (ccRCC). A total of 97 patients with ccRCC were enrolled in the present study, and the tissue microarray that was constructed using 97 ccRCC samples was used for immunohistochemical analysis. Univariate and multivariate Cox regression analyses were performed to determine the independent prognostic factors. Reverse transcription-quantitative PCR analysis demonstrated that the mRNA expression levels of scm-like with four malignant brain tumor domains (SFMBT1) and zinc fingers and homeoboxes 2 (ZHX2) were upregulated in cancer tissues compared with adjacent normal tissues. Among the 97 patients with ccRCC, SFMBT1 expression was upregulated in 61.9% (60/97), while ZHX2 expression was upregulated in 52.6% (51/97). Overall survival (OS) and disease-free survival (DFS) analyses indicated that SFMBT1 or ZHX2 alone were of limited predictive value; however, the combined expression of these two targets (high SFMBT1 and high ZHX2 expression, SHZH group) was significantly associated with OS (P=0.0350) and DFS (P=0.0434). In addition, multivariate analysis identified SHZH as an independent prognostic factor in patients with ccRCC. Taken together, these results suggest that SFMBT1 and ZHX2 act as novel substrate targets of VHL and, to the best of our knowledge, the present study was the first to provide insight on the co-expression of these two targets in representing a promising biomarker to predict the outcome of patients with ccRCC.

ZHX2 inhibits SREBP1c-mediated de novo lipogenesis in hepatocellular carcinoma via miR-24-3p.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Lipogenesis has been considered as a critical player in HCC initiation and progression. However, the underlying mechanism is still not fully understood. Here, we identified zinc fingers and homeoboxes 2 (ZHX2), an HCC-associated tumor suppressor, as an important repressor of de novo lipogenesis. Ectopic expression of ZHX2 significantly inhibited de novo lipogenesis in HCC cells and decreased expression of FASN, ACL, ACC1, and SCD1. In accordance with this, ZHX2 was negatively associated with SREBP1c, the master regulator of de novo lipogenesis, in HCC cell lines and human specimens. Results from silencing and overexpression demonstrated that ZHX2 inhibited de novo lipogenesis and consequent HCC progression via repression of SREBP1c. Furthermore, treatment with the SREBP1c inhibitor fatostatin dampened the spontaneous formation of tumors in liver-specific Zhx2 knockout mice. Mechanistically, ZHX2 increased expression of miR-24-3p transcriptionally, which targeted SREBP1c and led to its degradation. In conclusion, our data suggest a novel mechanism through which ZHX2 suppresses HCC progression, which may provide a new strategy for the treatment of HCC. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Long non-coding RNA SNHG17 promotes proliferation, migration and invasion of glioma cells by regulating the miR-23b-3p/ZHX1 axis.

Long non-coding RNA (lncRNA) small nucleolar RNA host gene 17 (SNHG17) is a carcinogenic lncRNA in diverse cancers. The expression pattern and mechanisms of SNHG17 in glioma still await verification. Paired glioma samples were enrolled. SNHG17, miR-23b-3p, and zinc-fingers and homeoboxes 1 (ZHX1) mRNA expression were examined by a quantitative real-time polymerase chain reaction (qRT-PCR). SNHG17 short hairpin RNA (shRNA) and miR-23b-3p mimics were transfected into LN229 and U251 cell lines to repress SNHG17 and up-regulate miR-23b-3p expression, respectively. Proliferation, migration and invasion of LN229 and U251 cells were probed by a cell counting kit-8 assay and a Transwell assay. Bioinformatics prediction, dual-luciferase reporter assay, RNA immunoprecipitation assay, qRT-PCR and western blotting were applied to determine the regulatory relationships among SNHG17, miR-23b-3p and ZHX1. SNHG17 expression was markedly raised in glioma tissues, which was positively correlated with ZHX1 expression and negatively associated with the expression of miR-23b-3p. After transfection of SNHG17 shRNAs into glioma cells, the proliferation, migration and invasion of cancer cells was markedly restrained. miR-23b-3p mimics the function of SHNG17 knockdown. Furthermore, miR-23b-3p was shown to be negatively modulated by SNHG17, and ZHX1 was identified as a target of miR-23b-3p. SNHG17 is a "competing endogenous RNA" with respect to modulating ZHX1 expression by adsorbing miR-23b-3p and thereby promoting glioma progression.

ZHX2 drives cell growth and migration via activating MEK/ERK signal and induces Sunitinib resistance by regulating the autophagy in clear cell Renal Cell Carcinoma

Zinc fingers and homeoboxes 2 (ZHX2) was found as a novel VHL substrate target, and acted as an oncogenic driver in ccRCC. However, the detailed mechanism of ZHX2 in ccRCC development remains elusive, and no research has focused on studying ZHX2 in drug resistance yet. A tissue microarray with 358 ccRCC samples was used to determine the expression of ZHX2 in ccRCC patients. VHL-deficient cell line 786-O and VHL-normal cell line CAKI-1 was used for lineage reprogramming by transfecting with lentivirus. The in vitro and in vivo experiments were performed with these new cell lines to determine the mechanism of ZHX2 in ccRCC development and drug resistance. Immunohistochemistry analysis showed that ZHX2 was not highly expressed in ccRCC tumor tissues, only 33.2% (119/358) patients have high ZHX2 expression. However, high ZHX2 was significantly associated with advanced Fuhrman grade (p = 0.004), and proved to be an independent prognosis factor for progression-free survival (p = 0.0003), while there is no significant correlation with overall survival. We further discovered that ZHX2 overexpression could increase VEGF secretion and transcriptional activate the MEK/ERK1/2 and promote its downstream targets. We also found ZHX2 overexpression induce Sunitinib resistance though activating autophagy and the combination treatment of Sunitinib and Chloroquine could significantly rescue the phenomenon. In summary, these results indicate that ZHX2 drivers cell growth, migration though increase VEGF expression, and transcriptional activate MEK/ERK1/2 signaling pathway, and could induce Sunitinib resistance by regulating self-protective autophagy, these may provide new insight in advanced ccRCC treatment.

ZHX2 restricts hepatocellular carcinoma by suppressing stem cell-like traits through KDM2A-mediated H3K36 demethylation.

BackgroundLiver cancer stem cells (CSCs) are critical determinants of HCC relapse and therapeutic resistance, but the mechanisms underlying the maintenance of CSCs are poorly understood. We aimed to explore the role of tumor repressor Zinc-fingers and homeoboxes 2 (ZHX2) in liver CSCs.MethodsCD133+ or EPCAM+ stem-like liver cancer cells were sorted from tumor tissues of HCC patients and HCC cell lines by flow cytometry. In addition, sorafenib-resistant cells, tumor-sphere forming cells and side population (SP) cells were respectively cultured and isolated as hepatic CSCs. The tumor-initiating and chemoresistance properties of ZHX2-overexpressing and ZHX2-knockdown cells were analyzed in vivo and in vitro. Microarray, luciferase reporter assay, chromatin immunoprecipitation (ChIP) and ChIP-on-chip analyses were performed to explore ZHX2 target genes. The expression of ZHX2 and its target gene were determined by quantitative RT-PCR, western blot, immunofluorescence and immunohistochemical staining in hepatoma cells and tumor and adjacent tissues from HCC patients.ResultsZHX2 expression was significantly reduced in liver CSCs from different origins. ZHX2 deficiency led to enhanced liver tumor progression and expansion of CSC populations in vitro and in vivo. Re-expression of ZHX2 restricted capabilities of hepatic CSCs in supporting tumor initiation, self-renewal and sorafenib-resistance. Mechanically, ZHX2 suppressed liver CSCs via inhibiting KDM2A-mediated demethylation of histone H3 lysine 36 (H3K36) at the promoter regions of stemness-associated transcription factors, such as NANOG, SOX4 and OCT4. Moreover, patients with lower expression of ZHX2 and higher expression of KDM2A in tumor tissues showed significantly poorer survival.ConclusionZHX2 counteracts stem cell traits through transcriptionally repressing KDM2A in HCC. Our data will aid in a better understanding of molecular mechanisms underlying HCC relapse and drug resistance.

Effect of miR-27b-5p on apoptosis of human vascular endothelial cells induced by simulated microgravity

Weightlessness-induced cardiovascular dysfunction can lead to physiological and pathological consequences. It has been shown that spaceflight or simulated microgravity can alter expression profiles of some microRNAs (miRNAs). Here, we attempt to identify the role of miRNAs in human umbilical vein endothelial cells (HUVECs) apoptosis under simulated microgravity. RNA-sequencing and quantitative real-time PCR (qRT-PCR) assays were used to identify differentially expressed miRNAs in HUVECs under simulated microgravity. Then we obtained the target genes of these miRNAs through target analysis software. Moreover, GO and KEGG enrichment analysis were performed. The effects of these miRNAs on HUVECs apoptosis were evaluated by flow cytometry, Western blot and Hoechst staining. Furthermore, we obtained the target gene of miR-27b-5p by luciferase assay, qRT-PCR and Western blot. Finally, we investigated the relationship between this target gene and miR-27b-5p in HUVECs apoptosis under normal gravity or simulated microgravity. We found 29 differentially expressed miRNAs in HUVECs under simulated microgravity. Of them, the expressions of 3 miRNAs were validated by qRT-PCR. We demonstrated that miR-27b-5p affected HUVECs apoptosis by inhibiting zinc fingers and homeoboxes 1 (ZHX1). Our results reported here demonstrate for the first time that simulated microgravity can alter the expression of some miRNAs in HUVECs and miR-27b-5p may protect HUVECs from apoptosis under simulated microgravity by targeting ZHX1.

Tumor suppressor ZHX2 inhibits NAFLD\u2013HCC progression via blocking LPL-mediated lipid uptake

Non-alcoholic fatty liver disease (NAFLD) leads to hepatocellular carcinoma (HCC). However, the underlying mechanism remains largely unclear. Here, we investigated the role of the tumor suppressor Zinc fingers and homeoboxes 2 (ZHX2) in the progression of NAFLD to HCC. ZHX2 expression was significantly decreased in fatty liver tissues, especially in the liver with NAFLD–HCC. ZHX2 overexpression disturbed lipid homeostasis of cultured HCC cells, and inhibited lipid deposition in hepatocytes both in vitro and in vivo. Moreover, ZHX2 inhibited uptake of exogenous lipids through transcriptional suppression of lipid lipase (LPL), leading to retarded proliferation of HCC cells. Importantly, LPL overexpression significantly reversed ZHX2-mediated inhibition of HCC cell proliferation, xenograft tumor growth, lipid deposition, and spontaneous liver tumor formation. Consistently, IHC staining demonstrated a negative correlation of ZHX2 with LPL in an HCC cohort. Collectively, ZHX2 protects hepatocytes from abnormal lipid deposition in NAFLD through transcriptional repression of LPL, which subsequently retards cell growth and NAFLD–HCC progression. These findings illustrate a novel mechanism of NAFLD progression into HCC.

Blocking lncRNA MALAT1/miR-199a/ZHX1 Axis Inhibits Glioblastoma Proliferation and Progression

Zinc fingers and homeoboxes 1 (ZHX1) is a transcription repressor that has been implicated in the tumorigenesis and progression of diverse tumors. The functional role and regulating mechanism of ZHX1 has not been elucidated in glioblastoma (GBM). Previous reports have suggested that a large number of non-coding RNAs play a vital role in glioma initiation and progression. This study aimed to investigate the functional role and co-regulatory mechanisms of the metastasis-associated lung adenocarcinoma transcript-1 (MALAT1)/ microRNA-199a (miR-199a)/ZHX1 axis in GBM. We analyzed the expression of the MALAT1/miR-199a/ZHX1 axis and its correlation with patients’ overall survival using two different glioma gene-expression datasets. A series of in vitro and in vivo studies including dual luciferase reporter assay, fluorescence in situ hybridization (FISH), RNA immunoprecipitation, and pull-down experiments were completed to elucidate the biological significance of the MALAT1/miR-199a/ZHX1 axis in promoting glioma proliferation and progression. Elevated ZHX1 expression correlated with poor prognosis in GBM patients, and in vitro studies demonstrated that ZHX1 attenuated GBM cell apoptosis by downregulation of pro-apoptotic protein (Bax) and upregulation of anti-apoptotic protein (Bcl-2). Furthermore, knockdown of MALAT1 inhibited GBM proliferation and progression in vitro and reduced tumor volume and prolonged survival in an orthotopic GBM murine model. Finally, we demonstrated that MALAT1 promoted ZHX1 expression via acting as a competing endogenous RNA by sponging miR-199a. The MALAT1/miR-199a/ZHX1 axis promotes GBM cell proliferation and progression in vitro and in vivo, and its expression negatively correlates with GBM patient survival. Blocking the MALAT1/miR-199a/ZHX1 axis can serve as a novel therapeutic strategy for treating GBM.

Role of ZHX2 in regulating dorsal root ganglion μ-opioid receptor expression in mice with peripheral nerve injuryinduced pain hypersensitivity

To investigate the role of zinc-fingers and homeoboxes 2 (ZHX2) in regulating μ-opioid receptor expression in the dorsal root ganglion (DRG) in mice with peripheral nerve injury-induced pain hypersensitivity. Forty-eight male adult C57BL6J mice were randomized into 4 groups and subjected to chronic constriction injury (CCI) of the sciatic nerve or sham operation followed by microinjection of a specific small interfering RNA (siRNA) of ZHX2 or a negative control siRNA sequence (siNC) into the DRG. Seven days later, the mice were examined for changes in the hind paw withdrawal frequency (PWF), after which the DRG tissue was collected for detecting the expressions of μ-opioid receptor at the mRNA and protein levels using RT-qPCR and Western blotting. In another experiment, the DRG tissues were collected from 6 mice (21-day-old) for primary culture of the DRG neurons, which were transfected with ZHX2 siRNA or the siNC to observe the changes in the expressions of ZHX2 and μ-pioid receptor. Microinjection of ZHX2 siRNA into the ipsilateral L3 and L4 DRGs significantly reversed CCI-induced μ-pioid receptor downregulation in the injured DRG and alleviated CCI-induced mechanical allodynia in the mice. In the cell experiment, ZHX2 knockdown obviously upregulated the mRNA and protein expressions of opioid receptor in the primary cultured DRG neurons. ZHX2 knockdown in the DRG reverses CCI-induced down-regulation of μ opioid receptor to alleviate periphery nerve injury-induced pain hypersensitivity in mice.

Targeting genes and signaling pathways of transcriptional suppressor ZHX2 in hepatocellular carcinoma: a Chromatin Immunoprecipitation-sequencing (ChIP-seq) investigation

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world. The unclear molecular mechanisms underlying could provide important theoretical basis for the prevention and control of HCC. This study performed chromatin immunoprecipitation-sequencing (ChIP-seq) to analyze the binding sites between zinc fingers and homeoboxes 2 (ZHX2) and its genome-wide target genes, and bioinformatics was used to analyze their gene transcription regulation network. Immunohistochemistry was used to detect the ZHX2 expression in HCC, and its association with the clinicopathological characteristics of HCC. Results of RT-PCR and western blot showed the expression of ZHX2 in HepG2 cells was obviously lower compared with normal liver cells. ZHX2 could be amplified in ChIP products, then ChIP-seq reveals there were 232 genes binding in promoter regions. GO analysis of functions revealed these genes were mainly associated with biological processes (BP), cellular components (CC), and molecular functions (MF). In addition, PTEN was found enriched in certain biological functions in BP analysis. Then, four pathways of these genes based on Kyoto Encyclopedia of Genes and Genomes (KEGG) were found P<0.05. Last analysis of immunohistochemistry showed the rates of ZHX2 expression and PTEN expression in paracancerous tissues both were significantly higher than that in HCC tissues (P=0.042; P<0.001), with negative correlations with AFP values (r=-0.246, P=0.040; r=-0.263, P=0.028). Further, PTEN expression was positively correlated with the differentiation level in HCC tissues (r=0.267, P=0.025). Spearman correlation analysis revealed that the expression profiles of ZHX2 and PTEN were positively correlated in HCC tissues (r=0.258, P=0.031). This study is the first to use ChIP-seq technology to analyze the specific regulatory mechanisms of the transcription suppressor ZHX2 in the context of HCC at the genome level.