OTUB1/NDUFS2 axis promotes pancreatic tumorigenesis through protecting against mitochondrial cell death.

Pancreatic cancer is one of the most fatal cancers in the world. A growing number of studies have begun to demonstrate that mitochondria play a key role in tumorigenesis. Our previous study reveals that NDUFS2 (NADH: ubiquinone oxidoreductase core subunit S2), a core subunit of the mitochondrial respiratory chain complex I, is upregulated in Pancreatic adenocarcinoma (PAAD). However, its role in the development of PAAD remains unknown. Here, we showed that NDUFS2 played a critical role in the survival, proliferation and migration of pancreatic cancer cells by inhibiting mitochondrial cell death. Additionally, protein mass spectrometry indicated that the NDUFS2 was interacted with a deubiquitinase, OTUB1. Overexpression of OTUB1 increased NDUFS2 expression at the protein level, while knockdown of OTUB1 restored the effects in vitro. Accordingly, overexpression and knockdown of OTUB1 phenocopied those of NDUFS2 in pancreatic cancer cells, respectively. Mechanically, NDUFS2 was deubiquitinated by OTUB1 via K48-linked polyubiquitin chains, resulted in an elevated protein stability of NDUFS2. Moreover, the growth of OTUB1-overexpressed pancreatic cancer xenograft tumor was promoted in vivo, while the OTUB1-silenced pancreatic cancer xenograft tumor was inhibited in vivo. In conclusion, we revealed that OTUB1 increased the stability of NDUFS2 in PAAD by deubiquitylation and this axis plays a pivotal role in pancreatic cancer tumorigenesis and development.

NUDT21 interacts with NDUFS2 to activate the PI3K/AKT pathway and promotes pancreatic cancer pathogenesis.

BACKGROUND: NUDT21 (Nudix Hydrolase 21) has been shown to play an essential role in multiple biological processes. Pancreatic adenocarcinoma (PAAD) is one of the most fatal cancers in the world. However, the biological function of NUDT21 in PAAD remains rarely understood. The aim of this research was to identify the prediction value of NUDT21 in diagnosis, prognosis, immune infiltration, and signal pathway in PAAD. METHODS: Combined with the data in online databases, we analyzed the expression, immune infiltration, function enrichment, signal pathway, diagnosis, and prognosis of NUDT21 in PAAD. Then, the biological function of NUDT21 and its interacted protein in PAAD was identified through plasmid transduction system and protein mass spectrometry. Expression of NUDT21 was further verified in clinical specimens by immunofluorescence. RESULTS: We found that NUDT21 was upregulated in PAAD tissues and was significantly associated with the diagnosis and prognosis of pancreatic cancer through bioinformatic data analysis. We also found that overexpression of NUDT21 enhanced PAAD cells proliferation and migration, whereas knockdown NUDT21 restored the effects through in vitro experiment. Moreover, NDUFS2 was recognized as a potential target of NUDT21.We further verified that the expression of NDUFS2 was positively correlated with NUDT21 in PAAD clinical specimens. Mechanically, we found that NUDT21 stabilizes NDUFS2 and activates the PI3K-AKT signaling pathway. CONCLUSION: Our investigation reveals that NUDT21 is a previously unrecognized oncogenic factor in the diagnosis, prognosis, and treatment target of PAAD, and we suggest that NUDT21 might be a novel therapeutic target in PAAD.

PTPMT1 regulates mitochondrial death through the SLC25A6-NDUFS2 axis in pancreatic cancer cells.

Pancreatic ductal adenocarcinoma is a highly malignant cancer with poor prognosis, for which effective therapeutic strategies are urgently needed. The dual-specificity phosphatase PTPMT1 is localized in mitochondria and highly expressed in various cancers. Here, we investigated the function of PTPMT1 in pancreatic ductal adenocarcinoma. We inhibited its expression in pancreatic cancer cell lines using siRNAs or the specific PTPMT1 inhibitor alexidine dihydrochloride and observed that PTPMT1 silencing in pancreatic cancer cell lines drastically reduced cell viability, caused mitochondrial damage, and impaired mitochondrial function. Co-immunoprecipitation analysis demonstrated that PTPMT1 could interact with SLC25A6 and NDUFS2, indicating that it may modulate mitochondrial function via the SLC25A6-NDUFS2 axis. Collecively, our data highlight PTPMT1 as an important factor in pancreatic ductal adenocarcinoma and a potential therapeutic target.

Chemical constituents from Bletilla striata and their NO production suppression in RAW 264.7 macrophage cells.

A novel glucoside bletilloside A (1) was isolated from the tubers of Bletilla striata, together with seven known compounds (2-8). Their structures were determined on the basis of extensive spectroscopic analyses. All compounds were evaluated for the inhibition on NO production effects in RAW 264.7 macrophage cells, while militarine (4) and dactylorhin A (5) exhibited moderate inhibitory effects.

Structure of a polysaccharide from Urtica fissa determined by NMR spectra.

A polysaccharide, isolated and purified from the aqueous extract of nettle plant Urtica fissa, was found to consist of D-glucose and D-arabinose. Molecular weight was determined to be Mn 4140. The NMR experiments (¹H, ¹³C, ¹H--¹H COSY, TOCSY, HSQC, NOESY, and HMBC) revealed the structure as the following repeating unit: -->6)-α-D-Glcp-(1-->6)-α-D-Glcp-(1-->6)-ß-D-Glcp--(1-->5)-ß-D-Araf-(1-->3)-ß-D-Glcp-(1-->

Microbial transformation of epothilone A by Aspergillus niger AS 3.739.

The microbiological transformation of epothilone A (1) by Aspergillus niger AS 3.739 afforded four main metabolites. Their structures were elucidated by (1)H, (13)C NMR and HSQC, COSY, HMBC, and NOESY spectra as trans-12,13-hydroxylated epothilone A (2), cis-12,13-hydroxylated epothilone A (3), trans-12,15-epoxidated epothilone A (4), and cis-12,15-epoxidated epothilone A (5). All four compounds were firstly found based on their stereochemistry. These new compounds displayed cytotoxicity against human breast carcinoma cells MCF-7 with IC(50) 9.88 microg/ml of 2, 2.52 microg/ml of 3, 9.88 microg/ml of 4, and 5.68 microg/ml of 5.

Structural characterization of polysaccharides from the roots of Urtica fissa.

Three polysaccharides were isolated from the roots of Urtica fissa by extraction, ultrafiltration, anion-exchange, and gel-filtration chromatography. The structures were characterized using acetylation, methylation, and spectral methods (GCMS, NMR). All three polysaccharides are mainly composed of D-arabinofuranosyl, D-galactopyranosyl, D-glucopyranosyl residues with different structural characteristics. Polysaccharide A of MW 5.2 x 10(3) contained a linear chain of 1-linked beta-D-glucopyranosyl, 1,6-linked beta-D-glucopyranosyl, 1,6-linked alpha-galactopyranosyl, and 1,5-linked beta-arabinofuranosyl moieties. Polysaccharide B of MW 7.7 x 10(4) possessed a chain consisting of 1,5-linked alpha-D-arabinofuranosyl, 1,3-linked beta-D-mannopyranosyl, 1,6-linked beta-D-glucopyranosyl, and 1,6-linked alpha-D-galactopyranosyl residues, but 4-O of alpha-D-galactopyranosyl residues were branched by terminal beta-D-glucopyranosyl residues. Polysaccharide C of MW 5.3 x 10(4) composed of a chain of 1,5-linked alpha-D-arabinofuranosyl, 1,4-linked beta-D-galactopyranosyl, 1,5-linked beta-D-xylopyranosyl, 1,4-linked beta-D-mannopyranosyl, 1-linked beta-D-glucopyranosyl residues, and the terminal beta-D-glucopyranosyl residues are attached to 3-O positions of 1,6-linked alpha-D-glucopyranosyl residues.