Antiproliferative Activity and Potential Mechanism of Marine-Sourced Streptoglutarimide H against Lung Cancer Cells

Structure and function of the highly homologous deubiquitinases ubiquitin specific peptidase 25 and 28: Insights into their pathophysiological and therapeutic roles

Deubiquitination is the reverse process of ubiquitination, an important protein post-translational modification. Deubiquitination is assisted by deubiquitinating enzymes (DUBs), which catalyze the hydrolysis and removal of ubiquitin chains from targeted proteins and play an important role in regulating protein stability, cell signaling transduction, and programmed cell death. Ubiquitin-specific peptidases 25 and 28 (USP25 and USP28), important members of the USP subfamily of DUBs, are highly homologous, strictly regulated, and closely associated with various diseases, such as cancer and neurodegenerative diseases. Recently, the development of inhibitors targeting USP25 and USP28 for disease treatment has garnered extreme attention. Several non-selective and selective inhibitors have shown potential inhibitory effects. However, the specificity, potency, and action mechanism of these inhibitors remain to be further improved and clarified. Herein, we summarize the structure, regulation, emerging physiological roles, and target inhibition of USP25 and USP28 to provide a basis for the development of highly potent and specific inhibitors for the treatment of diseases, such as colorectal cancer, breast cancer and so on.

Ubiquitin-specific protease 28: the decipherment of its dual roles in cancer development

As significant posttranslational modifications, ubiquitination and deubiquitination, whose balance is modulated by ubiquitin-conjugating enzymes and deubiquitinating enzymes (DUBs), can regulate many biological processes, such as controlling cell cycle progression, signal transduction and transcriptional regulation. Belonging to DUBs, ubiquitin-specific protease 28 (USP28) plays an essential role in turning over ubiquitination and then contributing to the stabilization of quantities of substrates, including several cancer-related proteins. In previous studies, USP28 has been demonstrated to participate in the progression of various cancers. Nevertheless, several reports have recently shown that in addition to promoting cancers, USP28 can also play an oncostatic role in some cancers. In this review, we summarize the correlation between USP28 and tumor behaviors. We initially give a brief introduction of the structure and related biological functions of USP28, and we then introduce some concrete substrates of USP28 and the underlying molecular mechanisms. In addition, the regulation of the actions and expression of USP28 is also discussed. Moreover, we concentrate on the impacts of USP28 on diverse hallmarks of cancer and discuss whether USP28 can accelerate or inhibit tumor progression. Furthermore, clinical relevance, including impacting clinical prognosis, influencing therapy resistance and being the therapy target in some cancers, is depicted systematically. Thus, assistance may be given to future experimental designs by the information provided here, and the potential of targeting USP28 for cancer therapy is emphasized.

New Hygrocins K-U and Streptophenylpropanamide A and Bioactive Compounds from the Marine-Associated Streptomyces sp. ZZ1956

Marine-derived Streptomyces actinomycetes are one of the most important sources for the discovery of novel bioactive natural products. This study characterized the isolation, structural elucidation and biological activity evaluation of thirty compounds, including twelve previously undescribed compounds, namely hygrocins K-U (5-13, 17 and 18) and streptophenylpropanamide A (23), from the marine-associated actinomycete Streptomyces sp. ZZ1956. Structures of the isolated compounds were determined by a combination of extensive NMR spectroscopic analyses, HRESIMS data, the Mosher's method, ECD calculations, single crystal X-ray diffraction and comparison with reported data. Hygrocins C (1), D (2), F (4), N (8), Q (11) and R (12), 2-acetamide-6-hydroxy-7-methyl-1,4-naphthoquinone (22), echoside C (27), echoside A (28) and 11,11'-O-dimethylelaiophylin (30) had antiproliferative activity (IC50: 0.16-19.39 μM) against both human glioma U87MG and U251 cells with hygrocin C as the strongest active compound (IC50: 0.16 and 0.35 μM, respectively). The analysis of the structure-activity relationship indicated that a small change in the structures of the naphthalenic ansamycins had significant influence on their antiglioma activities. Hygrocins N (8), O (9), R (12), T (17) and U (18), 2-amino-6-hydroxy-7-methyl-1,4-naphthoquinone (21), 2-acetamide-6-hydroxy-7-methyl-1,4-naphthoquinone (22), 3'-methoxy(1,1',4',1″-terphenyl)-2',6'-diol (26), echoside C (27) and echoside A (28) showed antibacterial activity against methicillin-resistant Staphylococcus aureus and Escherichia coli with MIC values of 3-48 μg/mL.

Cytotoxic metabolites from the marine-associated Streptomyces sp. ZZ1944

Marine-derived actinomycetes from the genus Streptomycete have a huge potential for the production of metabolites with structural and bioactive uniqueness and diversity. This study described the isolation and structural elucidation of twenty metabolites, including seven previously unreported compounds galbonolide H, galbonolide I, streptophenylpropionic acid A, treptophenylpropyl ester A, streptophenvaleramide A, seco-geldanamycin A and streptorapamycin A, from the marine-associated Streptomycete sp. ZZ1944. Structures of the isolated compounds were elucidated by a combination of extensive NMR spectroscopic analyses, HRESIMS data, optical rotation and ECD calculations. The structure of galbonolide H was also confirmed by a single crystal X-ray diffraction. Both autolytimycin and seco-geldanamycin A showed potent activity against the proliferation of glioma, lung cancer, colorectal cancer and breast cancer cells. Autolytimycin blocked cell cycle of glioma cells and seco-geldanamycin A induced apoptosis of glioma cells.