The Potential Mechanism of HDAC1-Catalyzed Histone Crotonylation of Caspase-1 in Nonsmall Cell Lung Cancer

A glimpse into novel acylations and their emerging role in regulating cancer metastasis

Metastatic cancer is a major cause of cancer-related mortality; however, the complex regulation process remains to be further elucidated. A large amount of preliminary investigations focus on the role of epigenetic mechanisms in cancer metastasis. Notably, the posttranslational modifications were found to be critically involved in malignancy, thus attracting considerable attention. Beyond acetylation, novel forms of acylation have been recently identified following advances in mass spectrometry, proteomics technologies, and bioinformatics, such as propionylation, butyrylation, malonylation, succinylation, crotonylation, 2-hydroxyisobutyrylation, lactylation, among others. These novel acylations play pivotal roles in regulating different aspects of energy mechanism and mediating signal transduction by covalently modifying histone or nonhistone proteins. Furthermore, these acylations and their modifying enzymes show promise regarding the diagnosis and treatment of tumors, especially tumor metastasis. Here, we comprehensively review the identification and characterization of 11 novel acylations, and the corresponding modifying enzymes, highlighting their significance for tumor metastasis. We also focus on their potential application as clinical therapeutic targets and diagnostic predictors, discussing the current obstacles and future research prospects.

HDAC1 inhibits beige adipocyte-mediated thermogenesis through histone crotonylation of Pgc1a/Ucp1

Obesity, one of the most serious public health issues, is caused by the imbalance of energy intake and energy expenditure. Increasing energy expenditure via induction of adipose tissue browning has become an appealing strategy to treat obesity and associated metabolic complications. Although histone modifications have been confirmed to regulate cellular energy metabolism, the involved biochemical mechanism of thermogenesis in adipose tissue is not completely understood. Herein, we report that class I histone deacetylases (HDAC) inhibitor MS275 increased PGC1α/UCP1 protein levels in inguinal white adipose tissue (iWAT) concomitant with elevated energy expenditure, reduced obesity and ameliorated glucose tolerance compared to control littermates. H3K18cr and H3K18ac levels were elevated after MS275 treatment. MS275 also promoted the transcription of Pgc1α and Ucp1 by enhancing the enrichment of H3K18cr and H3K18ac in the Pgc1α/Ucp1 enhancer and promoter, with a notable increase in H3K18cr. Mechanistically, the deletion of Hdac1 in beige adipocyte increases H3K18cr levels in enhancers and promoters of Pgc1α and Ucp1 genes, regulated the chromosomal state, thereby affecting the transcription of Pgc1α/Ucp1. Taken together, HDAC1 inhibits beige adipocyte-mediated thermogenesis through histone crotonylation of Pgc1a/Ucp1. This finding may provide a therapeutic strategy through increasing energy expenditure in obesity and related metabolic disorders.

Chemoresistance Mechanisms in Non-Small Cell Lung Cancer-Opportunities for Drug Repurposing

Globally, lung cancer contributes significantly to the public health burden-associated mortality. As this form of cancer is insidious in nature, there is an inevitable diagnostic delay leading to chronic tumor development. Non-small cell lung cancer (NSCLC) constitutes 80-85% of all lung cancer cases, making this neoplasia form a prevalent subset of lung carcinoma. One of the most vital aspects for proper diagnosis, prognosis, and adequate therapy is the precise classification of non-small cell lung cancer based on biomarker expression profiling. This form of biomarker profiling has provided opportunities for improvements in patient stratification, mechanistic insights, and probable druggable targets. However, numerous patients have exhibited numerous toxic side effects, tumor relapse, and development of therapy-based chemoresistance. As a result of these exacting situations, there is a dire need for efficient and effective new cancer therapeutics. De novo drug development approach is a costly and tedious endeavor, with an increased attrition rate, attributed, in part, to toxicity-related issues. Drug repurposing, on the other hand, when combined with computer-assisted systems biology approach, provides alternatives to the discovery of new, efficacious, and safe drugs. Therefore, in this review, we focus on a comparison of the conventional therapy-based chemoresistance mechanisms with the repurposed anti-cancer drugs from three different classes-anti-parasitic, anti-depressants, and anti-psychotics for cancer treatment with a primary focus on NSCLC therapeutics. Certainly, amalgamating these novel therapeutic approaches with that of the conventional drug regimen in NSCLC-affected patients will possibly complement/synergize the existing therapeutic modalities. This approach has tremendous translational significance, since it can combat drug resistance and cytotoxicity-based side effects and provides a relatively new strategy for possible application in therapy of individuals with NSCLC.

Crotonylation and disease: Current progress and future perspectives

Histone lysine crotonylation was first identified as a new type of post-translational modification in 2011. In recent years, prominent progress has been made in the study of histone and nonhistone crotonylation in reproduction, development, and disease. Although the regulatory enzyme systems and targets of crotonylation partially overlap with those of acetylation, the peculiar CC bond structure of crotonylation suggests that crotonylation may have specific biological functions. In this review, we summarize the latest research progress regarding crotonylation, especially its regulatory factors and relationship with diseases, which suggest further research directions for crotonylation and provide new ideas for developing disease intervention and treatment regimens.

HDAC-an important target for improving tumor radiotherapy resistance

Radiotherapy is an important means of tumor treatment, but radiotherapy resistance has been a difficult problem in the comprehensive treatment of clinical tumors. The mechanisms of radiotherapy resistance include the repair of sublethal damage and potentially lethal damage of tumor cells, cell repopulation, cell cycle redistribution, and reoxygenation. These processes are closely related to the regulation of epigenetic modifications. Histone deacetylases (HDACs), as important regulators of the epigenetic structure of cancer, are widely involved in the formation of tumor radiotherapy resistance by participating in DNA damage repair, cell cycle regulation, cell apoptosis, and other mechanisms. Although the important role of HDACs and their related inhibitors in tumor therapy has been reviewed, the relationship between HDACs and radiotherapy has not been systematically studied. This article systematically expounds for the first time the specific mechanism by which HDACs promote tumor radiotherapy resistance in vivo and in vitro and the clinical application prospects of HDAC inhibitors, aiming to provide a reference for HDAC-related drug development and guide the future research direction of HDAC inhibitors that improve tumor radiotherapy resistance.