Suppressor Of Variegation 3-9 Homolog 2 Research Articles

Histone Methyltransferase SUV39H2 Supports Nasopharyngeal Carcinoma Cell Metastasis by Regulation of SIRT1.

Nasopharyngeal carcinoma (NPC) is a malignant tumor with high metastatic features originating from the nasopharynx. However, the underlying mechanism of Suppressor of variegation 3-9 homolog 2 (SUV39H2) in NPC remains poorly understood. RT-qPCR was carried out to examine SUV39H2 and SIRT1 expression in NPC tissues and cells. Kaplan-Meier method was utilized to evaluate the association between SUV39H2 level and overall survival. The function of SUV39H2 and SIRT1 in NPC cell viability, metastasis, and apoptosis was tested through CCK-8, transwell, and flow cytometry experiments. Here, it was uncovered that SUV39H2 level was augmented in NPC tissues and cells. Moreover, SUV39H2 expedited NPC cell viability, metastasis, and inhibited apoptosis, while SIRT1 addition reversed these impacts. Besides, SUV39H2 induced H3K9me3 enhancement to repress SIRT1 transcription via binding to SIRT1 promoter. Collectively, our results demonstrated upregulated SUV39H2 aggravated NPC tumorigenesis through SIRT1, which may offer a potential therapeutic target for NPC.

Epigenetic Regulation of IL-23 by E3 Ligase FBXW7 in Dendritic Cells Is Critical for Psoriasis-like Inflammation.

Dendritic cells (DCs), a driver of psoriasis pathogenesis, produce IL-23 and trigger IL-23/IL-17 cytokine axis activation. However, the mechanisms regulating IL-23 induction remain unclear. In the current study, we found that mice with E3 ligase FBXW7 deficiency in DCs show reduced skin inflammation correlated with the reduction of IL-23/IL-17 axis cytokines in the imiquimod-induced psoriasis model. Fbxw7 deficiency results in decreased production of IL-23 in DCs. FBXW7 interacts with the lysine N-methyltransferase suppressor of variegation 39 homolog 2 (SUV39H2), which catalyzes the trimethylation of histone H3 Lys9 (H3K9) during transcription regulation. FBXW7 mediates the ubiquitination and degradation of SUV39H2, thus decreasing H3K9m3 deposition on the Il23a promoter. The Suv39h2 knockout mice displayed exacerbated skin inflammation with the IL-23/IL-17 axis overactivating in the psoriasis model. Taken together, our results indicate that FBXW7 increases IL-23 expression in DCs by degrading SUV39H2, thereby aggravating psoriasis-like inflammation. Inhibition of FBXW7 or the FBXW7/SUV39H2/IL-23 axis may represent a novel therapeutic approach to psoriasis.

A metabolism-related gene signature for predicting the prognosis and therapeutic responses in patients with hepatocellular carcinoma.

BackgroundHepatocellular carcinoma (HCC) often has an insidious onset and rapid progression. Often, when the disease is first diagnosed, the opportune time for surgical intervention has already lapsed. In addition, the effects of systemic treatment is relatively unsatisfactory. Metabolic reprogramming is one of the hallmarks of cancer. This study aimed to identify a set of genes related to metabolism to construct a predictive model for the prognosis of HCC.MethodsThe transcriptomic and clinical data of 352 HCC patients were obtained from The Cancer Genome Atlas (TCGA) Liver Hepatocellular Carcinoma (LIHC) dataset and divided into a training cohort (n=212) and a testing cohort (n=140) at a ratio of 6:4. Univariate Cox regression analysis and the LASSO Cox regression model were used to identify 5 genes to establish a risk score for predicting the prognosis of HCC patients. Subsequently, the molecular characteristics of the model were assessed and the ability of the model to predict the tumor immune microenvironment and patient response to immunotherapy and chemotherapy was also examined.ResultsThe risk score model was constructed based on the five genes, methyltransferase-like protein 6 (METTL6), RNA polymerase III subunit G (POLR3G), phosphoribosyl pyrophosphate amidotransferase (PPAT), SET Domain Bifurcated 2 (SETDB2), and suppressor of variegation 3-9 homolog 2 (SUV39H2). The Kaplan-Meier survival analysis and time-dependent receiver operating characteristic (ROC) curves demonstrated that high-risk patients had a poorer overall survival (OS) compared to low-risk patients. he nomogram score had a better predictive ability compared to the common factors. Our results finally showed that high-risk cases were associated with cell proliferation and cell cycle related gene sets, high tumor protein P53 (TP53) mutation rate, suppressive immunity and increased sensitivity to cisplatin, gemcitabine and docetaxel. Meanwhile, low-risk cases were associated with cell cycle and immune response related pathways, low TP53 mutation rate, active immunity and more benefit from immunotherapy.ConclusionsThis study provided novel insights into the role of metabolism-related genes in HCC, and demonstrated that our model could be a promising prognostic biomarker for distinguishing the molecular and immune characteristics and inferring the potential response to chemotherapy and immunotherapy.

Suppressor of Variegation 3-9 Homolog 2, a Novel Binding Protein of Translationally Controlled Tumor Protein, Regulates Cancer Cell Proliferation.

Suppressor of Variegation 3–9 Homolog 2 (SUV39H2) methylates the lysine 9 residue of histone H3 and induces heterochromatin formation, resulting in transcriptional repression or silencing of target genes. SUV39H1 and SUV39H2 have a role in embryonic development, and SUV39H1 was shown to suppress cell cycle progression associated with Rb. However, the function of human SUV39H2 has not been extensively studied. We observed that forced expression of SUV39H2 decreased cell proliferation by inducing G1 cell cycle arrest. In addition, SUV39H2 was degraded through the ubiquitin-proteasomal pathway. Using yeast two-hybrid screening to address the degradation mechanism and function of SUV39H2, we identified translationally controlled tumor protein (TCTP) as an SUV39H2-interacting molecule. Mapping of the interacting regions indicated that the N-terminal 60 amino acids (aa) of full-length SUV39H2 and the C-terminus of TCTP (120–172 aa) were critical for binding. The interaction of SUV39H2 and TCTP was further confirmed by co-immunoprecipitation and immunofluorescence staining for colocalization. Moreover, depletion of TCTP by RNAi led to up-regulation of SUV39H2 protein, while TCTP overexpression reduced SUV39H2 protein level. The half-life of SUV39H2 protein was significantly extended upon TCTP depletion. These results clearly indicate that TCTP negatively regulates the expression of SUV39H2 post-translationally. Furthermore, SUV39H2 induced apoptotic cell death in TCTP-knockdown cells. Taken together, we identified SUV39H2, as a novel target protein of TCTP and demonstrated that SUV39H2 regulates cell proliferation of lung cancer cells.

Abstract 4041: SUV39H2 inhibition enhances sensitivity of breast cancer cells to doxorubicin through downregulation of γ-H2AX production

Abstract Accumulating evidence has demonstrated the biological importance of protein methyltransferases in human tumorigenesis, and several small molecular inhibitors targeting these enzymes have been developed. Moreover, inhibiting pathways involved in DNA repair has been shown to enhance the cytotoxicity of DNA-damaging agents. Herein, we report the development of a potent SUV39H2 inhibitor (OTS193320) that decreases global histone H3 lysine 9 tri-methylation (H3K9me3) levels in cancer cells and attenuates cancer cell proliferation, and suppresses the tumor growth in mouse xenograft models. SUV39H2 (Suppressor of variegation 3-9 homolog 2), is a protein methyltransferase known to methylate histone H3 at lysine 9 (H3K9), and recently reported to methylate histone H2AX at lysine 134, which enhances the accumulation of phosphorylated H2AX (γ-H2AX) and regulates the DNA repair pathway in human cancer. SUV39H2 is highly expressed in many cancer types, including lung and breast cancers, while its expression levels are restricted to testis in normal adult tissues. Exposure of OTS193320 to two triple negative breast cancer cell lines attenuated H3K9me3 levels in a dose-dependent manner and triggered apoptotic cell death. Combination of OTS193320 and doxorubicin (DOX) resulted in reduction of γ-H2AX levels compared to single agent DOX, as visualized on western blot and immunocytochemical analysis. Furthermore, combination therapy attenuated the levels of p53-binding protein 1, which is reported to co-localize with γ-H2AX foci, compared to single agent DOX. Cell viability assays demonstrated a significant growth suppressive effect when OTS193320 was combined with DOX, compared to single agent treatment of either drug, suggesting chemosensitization to DOX. Importantly, in a mouse xenograft model of A549 lung cancer cells, we observed a tumor growth inhibition of 60.8% at day 14 with 25mg/kg intravenous administration of the inhibitor, without significant body weight loss or toxicity. Immunohistochemical staining of tumors treated with the inhibitor demonstrated a significantly lower number of Ki-67 positive cells and attenuated distribution patterns of H3K9me3 compared to the control tumors. Collectively, our results demonstrate that SUV39H2 inhibition may be a promising approach to develop a novel class of anti-cancer treatment. Citation Format: Theodore Vougiouklakis, Vassiliki Saloura, Yo Matsuo, Yusuke Nakamura. SUV39H2 inhibition enhances sensitivity of breast cancer cells to doxorubicin through downregulation of γ-H2AX production [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4041. doi:10.1158/1538-7445.AM2017-4041

Androgen receptor regulation by histone methyltransferase Suppressor of variegation 3-9 homolog 2 and Melanoma antigen-A11

Androgen receptor (AR) transcriptional activity depends on interactions between the AR NH2-terminal region and transcriptional coregulators. A yeast two-hybrid screen of a human testis library using predicted α-helical NH2-terminal fragment AR-(370-420) as bait identified suppressor of variegation 3-9 homolog 2 (SUV39H2) histone methyltransferase as an AR interacting protein. SUV39H2 interaction with AR and the AR coregulator, melanoma antigen-A11 (MAGE-A11), was verified in two-hybrid, in vitro glutathione S-transferase affinity matrix and coimmunoprecipitation assays. Fluorescent immunocytochemistry colocalized SUV39H2 and AR in the cytoplasm without androgen, in the nucleus with androgen, and with MAGE-A11 in the nucleus independent of androgen. Chromatin immunoprecipitation using antibodies raised against SUV39H2 demonstrated androgen-dependent recruitment of AR and SUV39H2 to the androgen-responsive upstream enhancer of the prostate-specific antigen gene. SUV39H2 functioned cooperatively with MAGE-A11 to increase androgen-dependent AR transcriptional activity. SUV39H2 histone methyltransferase is an AR coactivator that increases androgen-dependent transcriptional activity through interactions with AR and MAGE-A11.

Abstract 107: Critical role of lysine 134 methylation on histone H2AX for γ-H2AX production and DNA repair

Abstract γ-H2AX, the serine 139-phosphorylated form of the histone protein H2AX, is a marker of activation of the DNA damage machinery and is often overexpressed in many malignancies. Although γ-H2AX deregulation in cancer has previously been reported, the relevant molecular functions during carcinogenesis as well as its relationship with other histone modifications are still largely unknown. In the present study, we found that the histone methyltransferase Suppressor of Variegation 3-9 Homolog 2 (SUV39H2) methylated lysine 134 on histone H2AX, which is located in a unique portion of H2AX among the histone H2A family. When lysine 134 of histone H2AX was substituted to alanine, the amount of γ-H2AX production was significantly abolished. We also found lower γ-H2AX activity after introduction of the double-strand breakage in Suv39h2-double null cells or when SUV39H2 was knocked down. Concordantly, tissue microarray analysis of clinical lung tissues demonstrated a significantly positive correlation between K134-methylated H2AX and γ-H2AX levels. Furthermore, introduction of K134-substituted histone H2AX enhanced radio- and chemo-sensitivity of cancer cells, implying a critical role of methylation on the regulation of γ-H2AX production and the DNA repair pathways in cancer cells. This is the first report describing the functions of methylation on histone H2AX and its important role in the regulation of γ-H2AX production in cancer. Citation Format: Ryuji Hamamoto, Kenbun Sone, Yusuka Nakamura. Critical role of lysine 134 methylation on histone H2AX for γ-H2AX production and DNA repair. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 107. doi:10.1158/1538-7445.AM2015-107

Abstract 5159: The histone methyltransferase SUV39H2 is a novel target of anticancer therapy

Abstract Besides genetic disorders, dysregulation of epigenetic machinery has been proved to play a crucial role in human carcinogenesis, and the histone methylation/demethylation process has been considered as one of key regulators for this event. In this study, we demonstrate that one of the HMTs, suppressor of variegation 3-9 homolog 2 (SUV39H2), plays pivotal roles in human carcinogenesis. Quantitative real-time PCR revealed that SUV39H2 is aberrantly overexpressed in lung cancer, bladder cancer and multiple myeloma compared with their corresponding normal tissues, and immunohistochemical analysis revealed its positive staining in 251 out of 392 lung cancer cases and 16 of 29 bladder cancer cases, while no significant staining was observed in various normal tissues we examined. cDNA microarray analysis using a number of clinical tissues also confirms overexpression of SUV39H2 in various types of cancer. SUV39H2-specific small interfering RNAs significantly knocked down its expression, and caused the G1 arrest as well as suppression of cancer cell growth. Since SUV39H2 expression was undetectable in the normal tissues, SUV39H2 is considered to be an ideal target for development of tumor-specific therapeutics. Citation Format: Kembun Sone, Yusuke Nakamura, Ryuji Hamamoto. The histone methyltransferase SUV39H2 is a novel target of anticancer therapy. [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 5159. doi:10.1158/1538-7445.AM2014-5159

Novel polymorphisms in the SUV39H2 histone methyltransferase and the risk of lung cancer

Histone H3 lysine 9 (H3-K9) methylation and DNA methylation are important features of mammalian heterochromatin. Suppressor of variegation 3-9 homolog 2 (SUV39H2) is the histone methyltransferase that is required to methylate H3-K9, leading to transcriptional repression or silencing of target genes. In this study, we investigated the association of SUV39H2 polymorphisms and the risk of lung cancer. From the results of PCR direct sequencing, eight single nucleotide polymorphisms (SNPs) of SUV39H2 were identified in Korean population. In a hospital-based study of 346 lung cancer patients and 423 healthy controls, a novel SNP in the 3'-UTR of SUV39H2 (1624 G-->C) was associated with a statistically significant increase in lung cancer risk. Compared to the G/G genotype, genotypes with 1624C allele (G/C + C/C) significantly increased the susceptibility to lung cancer with adjusted odds ratio (AOR) of 2.63 (95% confidence interval (CI)= 1.10-6.29) for ever-smokers, especially in the older age group (age >or=55 years). Specifically, the variant genotype of 1624SNP was significantly associated with an increased risk of squamous cell carcinoma (AOR, 3.52; 95% CI = 1.13-9.45) in the older age group, while no significant association was found in patients with other histology. This study provided the first evidence that a novel SUV39H2 polymorphism may be an important predictive marker for lung cancer susceptibility for the smokers.