Melatonin induces apoptosis of colorectal cancer cells through HDAC4 nuclear import mediated by CaMKII inactivation

Melatonin induces apoptosis in many different cancer cell lines, including colorectal cancer. However, the precise mechanisms involved remain largely unresolved. In this study, we provide evidence to reveal a new mechanism by which melatonin induces apoptosis of colorectal cancer LoVo cells. Melatonin at pharmacological concentrations significantly suppressed cell proliferation and induced apoptosis in a dose‐dependent manner. The observed apoptosis was accompanied by the melatonin‐induced dephosphorylation and nuclear import of histone deacetylase 4 (HDAC4). Pretreatment with a HDAC4‐specific siRNA effectively attenuated the melatonin‐induced apoptosis, indicating that nuclear localization of HDAC4 is required for melatonin‐induced apoptosis. Moreover, constitutively active Ca²⁺/calmodulin‐dependent protein kinase II alpha (CaMKIIα) abrogated the melatonin‐induced HDAC4 nuclear import and apoptosis of LoVo cells. Furthermore, melatonin decreased H3 acetylation on bcl‐2 promoter, leading to a reduction of bcl‐2 expression, whereas constitutively active CaMKIIα(T286D) or HDAC4‐specific siRNA abrogated the effect of melatonin. In conclusion, the present study provides evidence that melatonin‐induced apoptosis in colorectal cancer LoVo cells largely depends on the nuclear import of HDAC4 and subsequent H3 deacetylation via the inactivation of CaMKIIα.     

Genotype and phenotype correlation in 103 individuals with 2q37 deletion syndrome reveals incomplete penetrance and supports HDAC4 as the primary genetic contributor

The 2q37 deletion syndrome, also described in the literature as brachydactyly‐mental retardation syndrome (MIM 600430), is caused by deletion or haploinsufficiency of the HDAC4 gene, which encodes the histone deacetylase 4 protein. Although the most commonly described hallmark features of the 2q37 deletion syndrome include brachydactyly type E, developmental delay, obesity, autistic features, and craniofacial or skeletal dysmorphism, a literature review of 101 published cases plus two newly reported individuals indicates that there is a high degree of variability in the presence of some of the features that are considered the most characteristic of the syndrome: overweight and obesity (34%), cognitive‐behavioral issues (79%), dysmorphic craniofacial features (86%), and type E brachydactyly (48%). These features overlap with other neurodevelopmental conditions, including Smith‐Magenis syndrome (SMS), and may be incompletely penetrant or demonstrate variable expressivity, depending on the specific chromosomal anomaly. With the advent of fluorescence in situ hybridization (FISH), array‐based comparative genomic hybridization, and next‐generation DNA sequencing, more detailed molecular diagnoses are possible than in years past, enabling refined characterization of the genotype–phenotype correlation for subjects with 2q37 deletions. In addition, investigations into molecular and gene expression networks are expanding in neurodevelopmental conditions, and we surveyed HDAC4 downstream gene expression by quantitative real‐time polymerase chain reaction, further implicating HDAC4 in its role in the regulation of RAI1. Correlation of clinical data defining the impact on downstream gene expression and the potential clinical associations across neurodevelopment will improve our understanding of these complex conditions and potentially lead to common therapeutic approaches.     

新型抗肿瘤组蛋白去乙酰化酶抑制剂西达本胺的合成

目的:合成西达本胺{N-(2-氨基-5-氟苯基)4-[N-(吡啶-3-丙烯酰)氨甲基]苯甲酰胺}.方法:以吡啶甲醛为起始原料,通过Knoevenagel反应,制得吡啶丙烯酸,然后以N,N′-碳酰二咪唑(CDI)为催化剂,通过2步酰化反应,合成目标产物.结果:目标产物的产率为29%.结论:本法条件温和,操作简便,适合工业化生产.     

MiR-206 inhibits Head and neck squamous cell carcinoma cell progression by targeting HDAC6 via PTEN/AKT/mTOR pathway

As a kind of endogenous noncoding small RNA, microRNA (miRNA) plays important roles of regulation to various physiological functions, while its affections on senescence of human Head and neck squamous cell carcinoma (HNSCC) are still unknown. The objective of this study was to investigate the effect of miR-206 in HNSCC tissues, adjacent normal tissues and cell lines, and explore its biological functions in HNSCC.In our study, the level of miR-206 in HNSCC tissues and adjacent normal tissues was detected via real-time qPCR. The effect of miR-206 on cell proliferation was tested by MTT assay, colony formation and cell cycle assays. In order to explore the effect of miR-206 on HNSCC cell migration and invasion, we performed wound healing assays and transwell assays. Luciferase reporter assays were designed to identify the interaction between 3′UTR of HDAC6 and miR-206. The level of signaling pathway-related proteins was determined by western blot. The expression of miR-206 was found to be observably decreased in HNSCC tissues and cell lines through real time-PCR. Restoration of miR-206 weaked cell proliferation, invasion and migration in HNSCC cells and the cell cycle was arrest in S phase. Further explores have shown that miR-206 could inhibit HNSCC cells proliferation by targeting the HDAC6 via PTEN/AKT/mTOR pathway. Taken together, our results demonstrated that miR-206 plays a critical role in HNSCC progression by targeting HDAC6 via PTEN/AKT/mTOR pathway, which might be a potential target for diagnostic and therapeutic in HNSCC.     

Antidepressant-Like Properties of Novel HDAC6-Selective Inhibitors with Improved Brain Bioavailability

HDAC inhibitors have been reported to produce antidepressant and pro-cognitive effects in animal models, however, poor brain bioavailability or lack of isoform selectivity of current probes has limited our understanding of their mode of action. We report the characterization of novel pyrimidine hydroxyl amide small molecule inhibitors of HDAC6, brain bioavailable upon systemic administration. We show that two compounds in this family, ACY-738 and ACY-775, inhibit HDAC6 with low nanomolar potency and a selectivity of 60- to 1500-fold over class I HDACs. In contrast to tubastatin A, a reference HDAC6 inhibitor with similar potency and peripheral activity, but more limited brain bioavailability, ACY-738 and ACY-775 induce dramatic increases in α-tubulin acetylation in brain and stimulate mouse exploratory behaviors in novel, but not familiar environments. Interestingly, despite a lack of detectable effect on histone acetylation, we show that ACY-738 and ACY-775 share the antidepressant-like properties of other HDAC inhibitors, such as SAHA and MS-275, in the tail suspension test and social defeat paradigm. These effects of ACY-738 and ACY-775 are directly attributable to the inhibition of HDAC6 expressed centrally, as they are fully abrogated in mice with a neural-specific loss of function of HDAC6. Furthermore, administered in combination, a behaviorally inactive dose of ACY-738 markedly potentiates the anti-immobility activity of a subactive dose of the selective serotonin reuptake inhibitor citalopram. Our results validate new isoform-selective probes for in vivo pharmacological studies of HDAC6 in the CNS and reinforce the viability of this HDAC isoform as a potential target for antidepressant development.     

Limited efficacy of specific HDAC6 inhibition in urothelial cancer cells

Epigenetic modifiers such as histone deacetylases (HDACs) have come into focus as novel drug targets for cancer therapy due to their functional role in tumor progression. Since common pan-HDAC inhibitors have adverse side effects and minor anti-cancer activity against solid tumors, enzyme-specific inhibitors were developed. HDAC6 is especially well-suited for specific inhibition due to its unique domain structure and mode of action and has been suggested to provide an exceptionally suitable target for cancer therapy. However, expression and function of HDACs have been insufficiently studied in urothelial cancers (UC), a disease urgently requiring new therapeutic approaches. The present study sought to evaluate HDAC6 as a target for treatment of urothelial cancers with enzyme-specific inhibitors. We observed moderate HDAC6 overexpression in urothelial cancer tissues and a broad range of expression in urothelial cancer cell lines. In the cell lines Tubacin was the most potent inhibitor, compared with Tubastatin and ST-80, but still active only at high micromolar concentrations. HDAC6 expression levels correlated poorly with sensitivity to enzyme inhibition. Combined treatments with heat shock, HSP90 inhibition by 17-AAG, proteasome inhibition by bortezomib, or DNA-damaging agents did not result in significant synergistic effects. Experiments with siRNA-mediated knockdown further underlined that urothelial cancer cells do not critically depend on HDAC6 expression for survival.     

The safety profile of vorinostat (suberoylanilide hydroxamic acid) in hematologic malignancies: A review of clinical studies

Histone acetyltransferases and histone deacetylases (HDACs) are multifunctional enzymes that posttranslationally modify both histone and nonhistone acetylation sites, affecting a broad range of cellular processes (e.g., cell cycle, apoptosis, and protein folding) often dysregulated in cancer. HDAC inhibitors are small molecules that directly interact with HDAC catalytic sites preventing the removal of acetyl groups, thereby counteracting the effects of HDACs. Since the first HDAC inhibitor, valproic acid, was investigated as a potential antitumor agent, there have been a number of other HDAC inhibitors developed to improve efficacy and safety. Despite significant progress in the management of patients with hematologic malignancies, overall survival is still poor. The discovery that HDACs may play a role in hematologic malignancies and preclinical studies showing promising activity with HDAC inhibitors in various tumor types, led to clinical evaluation of HDAC inhibitors as potential treatment options for patients with advanced hematologic malignancies. The Food and Drug Administration has approved two HDAC inhibitors, vorinostat (2006) and romidepsin (2009), for the treatment of cutaneous T-cell lymphoma. This review highlights the safety of HDAC inhibitors currently approved or being investigated for the treatment of hematologic malignancies, with a specific focus on the safety experience with vorinostat in cutaneous T-cell lymphoma.