Histone deacetylase 3 inhibits new tumor suppressor gene DTWD1 in gastric cancer

Cancer epigenetics plays an important role in the pathogenesis of many cancers including gastric cancer. Histone deacetylases (HDACs) emerge as exciting therapeutic targets for cancer treatment and prevention. In this study, we identified DTWD1 as one of the 122 genes upregulated after treatment of trichostatin A (TSA) in two gastric cancer cell lines. Moreover, DTWD1 was downregulated in gastric cancer cell lines and primary gastric carcinoma tissues. It was further identified as the new target of p53. Then we revealed that HDAC3 downregulated DTWD1 by disrupting the interaction of p53 with DTWD1 promoter. Furthermore, DTWD1 functioned as a tumor suppressor by downregulating cyclin B1 expression to inhibit proliferation. In summary, as the new p53 target gene, DTWD1 was downregulated in gastric cancer by HDAC3 and acted as a novel tumor suppressor gene. Specific inhibitors of HDAC3 might be a new approach for gastric cancer treatment by activating DTWD1 expression.     

Histone deacetylase inhibitors in cancer therapy

Histone deacetylase inhibitors (HDAC inhibitors) represent a novel class of antineoplastic agents that act by promoting acetylation of histones, leading in turn to uncoiling of chromatin and activation of a variety of genes implicated in the regulation of cell surivival, proliferation, differentiation, and apoptosis. The major classes of HDIs include shortchain fatty acids, hydroxamic acid derivatives, synthetic benzamide derivatives, and cyclic tetrapeptides. Members of each of these classes have now entered clinical trials in humans. Despite their shared capacity to trigger histone deacetylation, individual HDIs exert diverse actions on cell cycle regulatory, signal transduction, and survival-related proteins which in all probability accounts for their disparate actions. Major areas of investigation surrounding HDIs include elucidating the mechanisms by which they induce apoptosis in neoplastic cells, and characterizing the factors responsible for the decision of such cells to undergo maturation versus cell death in the response to these agents. In this context, attention has recently focused on the ability of HDIs to induce perturbations in cell cycle regulatory proteins (e.g., p21(CIP1)), downregulation of survival signaling pathways (e.g., Raf/MEK/ERK), and disruption of cellular redox state (e.g., induction of reactive oxygen species; ROS). Aside from efforts to combine HDIs with established cytotoxic drugs, attempts are underway to establish a rational basis for combining HDIs with differentiation- inducing agents (e.g., ATRA, hypomethylating agents such as 5'-deoxyazacytine) with the goal of triggering re-expression of turn or suppressor and/or differentiation-associated genes. Finally, the results of recent preclinical studies provide a strong rationale for combining HDIs with other novel, molecularly targeted agents, including inhibitors of survival signaling pathways or cell cycle progression. Collectively, these findings should provide a fertile environment for the development of novel HDI-containing regimens in the treatment of cancer for many years to come.     

组蛋白脱乙酰基酶抑制剂在肿瘤治疗中的应用

组蛋白的乙酰化状态调控DNA转录从而影响基因的表达水平.组蛋白脱乙酰基酶(HDAC)可降低组蛋白乙酰化,引起DNA-组蛋白复合物压缩.这种压缩可以阻碍基因转录,抑制细胞分化.HDAC抑制剂可以解除DNA-组蛋白复合物压缩,从而促进肿瘤细胞生长停滞、分化及凋亡.在此过程中,HDAC抑制剂也影响非组蛋白的乙酰化状态和功能....     

Histone deacetylase 2 expression predicts poorer prognosis in oral cancer patients

Histone deacetylase 2 (HDAC2) has been implicated in the development and progression of several human tumors. We immunohistochemically examined the expression of HDAC2 protein in 20 cases of oral epithelial dysplasia (OED) and 93 cases of oral squamous cell carcinoma (OSCC). Positive HDAC2 nuclear staining was observed in 80 of the 93 (86.02%) cases of SCC and 11 of the 20 (55%) cases of ED. The labeling index (LI) for HDAC2 nuclear staining increased significantly from ED (25.8+/-26.5%) to SCCs (59.8+/-28.5%) (p<0.001). No significant correlation was found between the HDAC2 expression level and patient's age, sex, oral habits in oral SCC patients. However, cancer with advanced stage, larger tumor size, or positive lymph node metastasis had higher level of HDAC2 protein expression. Kaplan-Meier curves showed oral SCC patients with high HDAC2 expression (LI>50%), advanced stage, larger tumor size, or positive lymph node metastasis had significantly shorter overall survival (p=0.0158, 0.0267, 0.0029 and 0.02514, respectively by log-rank test) than others. The results of this study show for the first time that overexpression of the HDAC protein is a frequent event in oral cancer and could be used as a prognostic factor in oral SCC.     

Histone deacetylase inhibitors induce thymidine phosphorylase expression in cultured breast cancer cell lines

Thymidine phosphorylase (TP) is an enzyme involved in thymidine synthesis and degradation. The expression of this enzyme has been proposed as a predictive factor for the therapeutic benefit of capecitabine, which is a precursor of the drug 5'-fluorouracil. In fact, TP is the rate-limiting enzyme in the activation of capecitabine. Therefore, higher levels of TP are expected to sensitize cancer cells to capecitabine treatment. In the present study, using breast cancer cell lines, we found a correlation between TP mRNA and protein levels, suggesting that compounds able to increase TP gene expression also increase protein levels. Accordingly, we demonstrated that treatment of breast cancer MCF7 and MDA231 cell lines with histone deacetylase inhibitors, tricostatin A and suberoylanilide hydroxamic acid, increased TP both at the mRNA and protein level. The effects of histone deacetylase inhibitors were not found to occur via the cytokine TNFα, a known inducer of TP expression. Our findings suggest a strategy to sensitize breast cancer cells to capecitabine treatment.     

Histone deacetylase 1 facilitates aerobic glycolysis and growth of endometrial cancer

The deregulation of histone deacetylase 1 (HDAC1) is reportedly involved in the progression of several cancer types. However, its function in endometrial cancer remains unknown. The aim of the present study was to clarify the role of HDAC1 in aerobic glycolysis and the progression of endometrial cancer. Lentiviral vector transfection was used to up- and downregulate HDAC1 expression in HEC-1-A endometrial cancer cells. The effects of HDAC1 on cellular proliferation, apoptosis, migration, invasiveness and tumorigenesis were determined by CCK-8, flow cytometry, wound-healing, transwell chamber and in vivo tumor formation experiments, respectively. HDAC1 level was significantly increased in endometrial cancer tissues and cells, and its high expression was associated with advanced clinicopathological progression. HEC-1-A cell proliferation, invasiveness, migration and tumorigenesis were enhanced, and apoptosis was inhibited when HDAC1 was overexpressed. Moreover, upregulation of HDAC1 significantly promoted the epithelial-mesenchymal transition of HEC-1-A cells, and increased glucose consumption, lactate secretion and ATP levels. Collectively, the present study revealed that HDAC1 promoted the aerobic glycolysis and progression of endometrial cancer, which may provide a potential target for endometrial cancer treatment.     

Histone deacetylase inhibitors activate p21(WAF1) expression via ATM

Histone deacetylase (HDAC) inhibitors are known to induce expression of genes such as p21(WAF1), thereby, leading to cell cycle arrest. In this work, we show that p21(WAF1) induction by HDAC inhibitors (depsipeptide and trichostatin A) is defective in Ataxia telangiectasia (AT) cells but normal in matched wild-type (WT) cells (human diploid fibroblasts). To verify the role of ATM in this effect, we show that ectopic expression of the WT ATM gene in an AT cell line fully restores p21(WAF1) induction by the HDAC inhibitors. Furthermore, because caffeine and wortmannin attenuate p21(WAF1) induction in WT cells, it is probable that the phosphatidylinositol 3'-kinase activity is essential for this process. Besides the p21(WAF1) promoter, activation of topoisomerase IIIalpha and SV40 promoters by the HDAC inhibitors are also decreased in the AT cell lines relative to WT cells; thus, these findings pertain to other promoters. Finally, despite the obvious induction deficiency of gene expression, the overall levels of H3 and H4 histone acetylation appear to be the same between AT and normal cells in response to HDAC inhibitor treatments. Taken together, the data indicate that ATM is involved in histone acetylation-mediated gene regulation.     

Histone deacetylase 1 is required for exocrine pancreatic epithelial proliferation in development and cancer

Histone deacetylases (HDACs) play important roles in the epigenetic control of development, and aberrant expression of HDACs has been implicated in human diseases including cancer. Among the mammalian HDACs, HDAC1 has been extensively studied, but its role in exocrine pancreatic morphogenesis and cancer is still poorly understood. The goal of this study is to determine the functional role of HDAC1 in normal development of exocrine pancreas using zebrafish as the model organism as well as in human pancreatic adenocarcinoma. The zebrafish germline loss-of-function mutation hdac1(hi1618) caused impaired cell cycle progression in pancreatic epithelia, resulting in growth arrest and dysmorphogenesis of exocrine pancreas. In human pancreatic adenocarcinoma tissues and cell lines, HDAC1 was expressed at variably elevated levels. RNA interference-induced silencing of HDAC1 diminished proliferation of the cancer cells and cell cycle progression. The proliferative arrest in the developing exocrine pancreas and pancreatic cancer cells was associated with up-regulated expression of the cyclin-dependent kinase inhibitors and the sonic hedgehog signaling components. This study indicates that HDAC1 is required for pancreatic epithelial proliferation in development and cancer. We hypothesize that aberrant expression of HDAC1 modulates the developmental and signaling pathways in exocrine pancreatic epithelia and consequently the genes required for cellular proliferation during development and progression of pancreatic neoplasia.     

Expression profile of histone deacetylase 1 in gastric cancer tissues.

Although histone deacetylases (HDACs) appear to play a crucial role in carcinogenesis, the expression status of HDACs in primary human cancer tissues has not yet been reported. In this study, we investigated the expression level of HDAC1 in 25 paired primary human gastric cancer (GC) tissues and corresponding normal tissues through semi-quantitative RT-PCR and immunoblot analysis. The HDAC1 expression pattern was also topologically examined through immunohistochemistry. Overexpression of HDAC1 mRNA was detected in 68% of GC tissues (17 of 25), and the relative density of HDAC1 mRNA in GC tissue was increased 1.8-fold versus the normal counterpart (P < 0.01). Elevated expression of HDAC1 protein was also detected in 61% of GC samples (11 of 18), which also showed an increased mRNA level of HDAC. Immunohistochemically, overexpression of HDAC1 was predominantly localized in the nuclei of most neoplastic cells, including embolic tumor cells, whereas normal glandular epithelial cells revealed only weak HDAC1 expression that was focal in distribution. Thus, the present study clearly demonstrates that HDAC1 is overexpressed in GC and probably plays a significant role in gastric carcinogenesis.     

Histone deacetylase as a new target for cancer chemotherapy

Trichostatin A (TSA) and trapoxin (TPX), inhibitors of the eukaryotic cell cycle and inducers of morphological reversion of transformed cells, inhibit histone deacetylase (HDAC) at nanomolar concentrations. Recently, FK228 (also known as FR901228 and depsipeptide) and MS-275. antitumor agents structurally unrelated to TSA, have been shown to be potent HDAC inhibitors. These inhibitors activate the expression of p21Waf1 in a p53-independent manner. Changes in the expression of regulators of the cell cycle, differentiation, and apoptosis with increased histone acetylation may be responsible for the cell cycle arrest and antitumor activity of HDAC inhibitors. TSA has been suggested to block the catalytic reaction by chelating a zinc ion in the active site pocket through its hydroxamic acid group. On the other hand, an epoxyketone has been suggested to be the functional group of TPX capable of alkylating the enzyme. We synthesized a novel TPX analogue containing a hydroxamic acid instead of the epoxyketone. The hybrid compound, called cyclic hydroxamic-acid-containing peptide 1 (CHAP1) inhibited HDAC at low nanomolar concentrations. The HDAC1 inhibition by CHAPI was reversible, as is that by TSA, in contrast to irreversible inhibition by TPX. Interestingly, HDAC6, but not HDAC1 or HDAC4, was resistant to TPX and CHAP1, while TSA inhibited these HDACs to a similar degree. CHAP31, the strongest HDAC inhibitor obtained from a variety of CHAP derivatives, exhibited antitumor activity in BDF1 mice bearing B16/BL6 tumor cells. These results suggest that CHAP31 is promising as a novel therapeutic agent for cancer treatment, and that CHAP may serve as a basis for new HDAC inhibitors and be useful for combinatorial synthesis and high-throughput screening.     

HDAC抑制剂下调乳腺癌细胞系HER-2的表达及miRNA表达谱的变化

  目的  探讨组蛋白去乙酰化酶（histone deacetylase,HDAC）抑制剂下调乳腺癌HER-2的表达机制,为乳腺癌抗HER-2治疗提供新的实验依据。  方法  利用HDAC抑制剂处理HER-2阳性乳腺细胞,qPCR和Western检测HER-2基因和蛋白水平的变化,同时采用miRNA芯片筛选HDAC抑制剂相关的miRNA谱,qPCR验证miRNA表达变化。  结果  体外细胞实验证实HDAC抑制剂TSA和SAHA可下调乳腺癌细胞系HER-2的表达,TSA可下调BT474的HER-2基因表达,浓度为100 nmol时下调10.7%,浓度为200 nmol时下调38.9%（P < 0.05）。TSA对原代细胞HER-2基因表达无明显下调（P > 0.05）。SAHA对BT474中HER-2基因表达的影响,浓度5 μmol/L组下调93.9%（P < 0.05）,而1 μmol/L组无明显下调。SAHA对原代细胞HER-2基因表达下调较为明显,浓度1 μmol/L时下调92.7%,浓度5 μmol/L时下调87.1%。通过miRNA芯片筛选出7条miRNA,qPCR监测SAHA、TSA处理后,miR-762基因表达上调2.11倍。  结论  HDAC抑制剂可能通过miRNA表达谱改变介导下调乳腺癌HER-2的表达。