NDP52 SUMOylation contributes to low-dose X-rays-induced cardiac hypertrophy through PINK1/Parkin-mediated mitophagy via MUL1/SUMO2 signalling.

Radiation-induced heart damage caused by low-dose X-rays has a significant impact on tumour patients' prognosis, with cardiac hypertrophy being the most severe noncarcinogenic adverse effect. Our previous study demonstrated that mitophagy activation promoted cardiac hypertrophy, but the underlying mechanisms remained unclear. In the present study, PARL-IN-1 enhanced excessive hypertrophy of cardiomyocytes and exacerbated mitochondrial damage. Isobaric tags for relative and absolute quantification-based quantitative proteomics identified NDP52 as a crucial target mediating cardiac hypertrophy induced by low-dose X-rays. SUMOylation proteomics revealed that the SUMO E3 ligase MUL1 facilitated NDP52 SUMOylation through SUMO2. Co-IP coupled with LC-MS/MS identified a critical lysine residue at position 262 of NDP52 as the key site for SUMO2-mediated SUMOylation of NDP52. The point mutation plasmid NDP52K262R inhibited mitophagy under MUL1 overexpression, as evidenced by inhibition of LC3 interaction with NDP52, PINK1 and LAMP2A. A mitochondrial dissociation study revealed that NDP52K262R inhibited PINK1 targeting to endosomes early endosomal marker (EEA1), late/lysosome endosomal marker (LAMP2A) and recycling endosomal marker (RAB11), and laser confocal microscopy confirmed that NDP52K262R impaired the recruitment of mitochondria to the autophagic pathway through EEA1/RAB11 and ATG3, ATG5, ATG16L1 and STX17, but did not affect mitochondrial delivery to lysosomes via LAMP2A for degradation. In conclusion, our findings suggest that MUL1-mediated SUMOylation of NDP52 plays a crucial role in regulating mitophagy in the context of low-dose X-ray-induced cardiac hypertrophy. Two hundred sixty-second lysine of NDP52 is identified as a key SUMOylation site for low-dose X-ray promoting mitophagy activation and cardiac hypertrophy. Collectively, this study provides novel implications for the development of therapeutic strategies aimed at preventing the progression of cardiac hypertrophy induced by low-dose X-rays.

ANGPTL4 accelerates ovarian serous cystadenocarcinoma carcinogenesis and angiogenesis in the tumor microenvironment by activating the JAK2/STAT3 pathway and interacting with ESM1.

BACKGROUND: Ovarian cancer (OC) is a malignant neoplasm that displays increased vascularization. Angiopoietin-like 4 (ANGPTL4) is a secreted glycoprotein that functions as a regulator of cell metabolism and angiogenesis and plays a critical role in tumorigenesis. However, the precise role of ANGPTL4 in the OC microenvironment, particularly its involvement in angiogenesis, has not been fully elucidated. METHODS: The expression of ANGPTL4 was confirmed by bioinformatics and IHC in OC. The potential molecular mechanism of ANGPTL4 was measured by RNA-sequence. We used a series of molecular biological experiments to measure the ANGPTL4-JAK2-STAT3 and ANGPTL4-ESM1 axis in OC progression, including MTT, EdU, wound healing, transwell, xenograft model, oil red O staining, chick chorioallantoic membrane assay and zebrafish model. Moreover, the molecular mechanisms were confirmed by Western blot, Co-IP and molecular docking. RESULTS: Our study demonstrates a significant upregulation of ANGPTL4 in OC specimens and its strong association with unfavorable prognosis. RNA-seq analysis affirms that ANGPTL4 facilitates OC development by driving JAK2-STAT3 signaling pathway activation. The interaction between ANGPTL4 and ESM1 promotes ANGPTL4 binding to lipoprotein lipase (LPL), thereby resulting in reprogrammed lipid metabolism and the promotion of OC cell proliferation, migration, and invasion. In the OC microenvironment, ESM1 may interfere with the binding of ANGPTL4 to integrin and vascular-endothelial cadherin (VE-Cad), which leads to stabilization of vascular integrity and ultimately promotes angiogenesis. CONCLUSION: Our findings underscore that ANGPTL4 promotes OC development via JAK signaling and induces angiogenesis in the tumor microenvironment through its interaction with ESM1.

Photo-Induced Difluoromethylation-Cyclization and Domino Amination-Defluorination to 4-(Aminomethyl)-3-fluoro-quinolinones.

Herein, we report a visible light-induced difluoromethylation cyclization and subsequent amination-defluorination reaction. This protocol allows efficient to valuable 3-fluoro-quinolinones in moderate to excellent yields. A sequential difluoromethylation-cyclization-amination-defluorination mechanism was proposed based on a mechanism study. Further density functional theory (DFT) calculations revealed that the base K2HPO4 could lower the energy due to the C═O···K+ electrostatic interaction to assist the elimination process, while the six-membered transition state located in situ was essential for the cleavage of N-H and C-F bonds during this SN2'-type process.

ANGPTL4 plays a paradoxical role in gastric cancer through the LGALS7 and Hedgehog pathways.

Gastric cancer (GC) is a malignant disease worldwide. Angiopoietin-like protein 4 (ANGPTL4) plays a role in pathophysiological processes, including metabolic reprogramming, angiogenesis, proliferation, and metastasis. Current evidence shows conflicting findings regarding the role of ANGPTL4 in the progression of GC. ANGPTL4 in GC was confirmed through bioinformatic analysis and immunofluorescence staining. The impact of ANGPTL4 was subsequently validated in GC cell lines using various assays, including 5-ethynyl-2-deoxyuridine (EdU), 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Flow Cytometry (FCM), wound healing, transwell, tube formation, chorioallantoic membrane model, and nude mouse model assays. RNA-seq analysis, polymerase chain reaction (PCR), western blotting (WB), immunofluorescence (IF) and coimmunoprecipitation (co-IP) were conducted to determine the potential downstream mechanism of ANGPTL4. In SNU5 and MKN7 cells, ANGPTL4 was found to augment proliferation, migration, invasion, evasion of apoptosis, and angiogenesis. Conversely, in the AGS cell line, ANGPTL4 was observed to suppress these processes. Notably, the overexpression of ANGPTL4 in AGS cells led to the upregulation of LGALS7, which has emerged as a pivotal factor contributing to the manifestation of an anticancer phenotype induced by ANGPTL4. LGALS7, which is involved in the regulation of the hedgehog pathway and subsequent promotion of GC progression through various processes, such as proliferation, migration, apoptosis evasion, angiogenesis, and lymphangiogenesis, was found to contribute to the contradictory effects of ANGPTL4.

Three-Component Photochemical Cyclization/Dithiocarbamate Formation of gem-Difluoro Quinolin-2(1H)-ones.

Herein, a novel visible-light-induced 6-exo-trig difluoromethylation cyclization and subsequent carbo-thioesterification reaction is described. This protocol allows efficient access to valuable gem-difluoro quinolin-2(1H)-ones in moderate to excellent yields under mild conditions. Broad amino sources compatibility, including cyclic morpholine, thiazolidine, thiomorpholine, pyrrolidine, 1,4-oxazepane, 2,6-dimethylmorpholine, tert-butyl piperazine-1-carboxylate and noncyclic diethylamine, N-ethylpropan-1-amine, N-benzylethanamine, N-benzyl-trimethylsilanamine, dibenzylamine, and N-(4-methoxybenzyl)ethanamine, demonstrated the practicability of this strategy. A radical-radical crossover route was proposed on the basis of radical inhibition experiments, visible light irradiation on-off test, apparent quantum efficiency (AQE) calculation, and fluorescence quenching studies.

Deoxypodophyllotoxin Mediates Autophagy Death through Inhibition of GRP78 in Human Osteosarcoma.

BACKGROUND: Glucose-regulated protein 78 (GRP78), as a chaperone protein, can protect the endoplasmic reticulum of cells and is expressed to influence chemoresistance and prognosis in cancer. Deoxypodophyllotoxin (DPT) is a compound with antitumor effects on cancers. DPT inhibits the proliferation of osteosarcoma by inducing apoptosis, necrosis, or cell cycle arrest. OBJECT: This study was performed to demonstrate the molecular mechanism by which DPT attenuates osteosarcoma progression through GRP78. METHODS: Natural compound libraries and western blot (WB) were used to screen the inhibitors of osteosarcoma GRP78. The expression of mitochondria-related genes in cancer cells of the treatment group was detected by quantitative real-time PCR (qPCR) and WB. 3-(4,5)- Dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) and 5-ethynyl-2'- deoxyuridine (EDU) were used to discover the activity and proliferation of osteosarcoma cells treated with DPT. We constructed an in vivo mouse model of DPT drug therapy and carried out immunohistochemical detection of xenografts. The treated osteosarcoma cells were analyzed using bioinformatics and electron microscopy. The data were analyzed finally. RESULTS: DPT inhibited osteosarcoma cell survival and the growth of tumor xenografts. It promoted up-regulation of BCL2-associated X protein (Bax) and B-cell CLL/lymphoma 2 (Bcl-2), which serves to mediate and attenuate, respectively, the killing activities of DPT through mitochondria dysfunction. The effect of DPT against cancer cells could be attenuated by the overexpression of GRP78, characterized by the inactivation of the caspase cascade. The loss of GRP78 in osteosarcoma cells negatively mediated the basal level of autophagyassociated genes. DPT stimulated autophagy via the phosphoinositide 3-kinase (PI3K)-v-akt murine thymoma viral oncogene homolog (AKT), a mechanistic target of rapamycin (mTOR) axis. The autophagy caused by DPT played an active role in the osteosarcoma of humans and blocked the apoptotic cascade. CONCLUSION: Combination treatment with the GRP78 inhibitor DPT and pharmacological autophagy inhibitors will be a meaningful method of obviating osteosarcoma cells.