A new IRES-mediated truncated Cx32 isoform inhibits global mRNA translation to suppress glioblastoma.

Glioblastoma (GBM) is the most lethal malignant primary brain tumor. Although multimodal therapy has been applied for GBM, the median survival time remains less than 16 months. Thus, better therapeutic targets in GBM are urgently needed. Herein, we first identified five new N-terminal-truncated Cx32 isoforms (GJB1-28k, GJB1-22k, GJB1-20k, GJB1-15k, and GJB1-13k) and further demonstrated that they were generated via cap-independent internal translation through internal ribosome entry sites (IRESs) in the coding sequence of GJB1 mRNA. Among these isoforms, GJB1-13k inhibited proliferation, promoted apoptosis, and limited cell cycle progression in GBM cells by inhibiting global mRNA translation. In vivo experiments further confirmed the antitumor activity of GJB1-13k against GBM cells. In addition, TSR3, a ribosomal maturation factor, was demonstrated to directly interact with GJB1-13k. Moreover, GBM cells with high TSR3 expression exhibited low sensitivity to GJB1-13k treatment, while GJB1-13k sensitivity was restored by TSR3 knockdown. Our work identifies a new IRES-mediated protein, GJB1-13k, and suggests that overexpression of GJB1-13k in GBM cells with low TSR3 expression or combined targeting of GJB1-13k and TSR3 in GBM cells with high TSR3 expression constitutes a potential therapeutic strategy for GBM.

Upregulated FKBP1A Suppresses Glioblastoma Cell Growth via Apoptosis Pathway.

Glioblastoma (GBM), the most deadly primary brain tumor, presents a major medical difficulty. The need for better therapeutic targets in GBM is therefore urgent. A growing body of evidence suggests that the gene FKBP1A plays an important role in tumor progression and may be therapeutically useful. However, the role of FKBP1A in glioblastoma and the underlying biologic mechanism remain unclear. The purpose of this study was to identify the role of FKBP1A in GBM and its molecular mechanism. We demonstrated that FKBP1A was the hub gene in GBM via a weighted correlation network analysis (WGCNA) and differentially expressed genes (DEGs) analysis based on the bulk RNA-seq data from TCGA and GTEx. Afterwards, we proved that the upregulated FKBP1A protein could promote GBM cell death by CCK-8 assays in U87MG and t98g GBM cell lines. We further demonstrated two key pathways of FKBP1A in GBM by bioinformatics methods: 'Apoptosis' and 'mTOR signaling pathway'. Subsequently, the key pathways were verified by flow cytometry and Western blot. We identified that upregulated FKBP1A could inhibit GBM growth via the apoptosis pathway. Together, these findings may contribute to future GBM treatment.

Cx32 promotes autophagy and produces resistance to SN­induced apoptosis via activation of AMPK signalling in cervical cancer.

The roles of gap junctions (GJs) and its components, connexins, in the autophagy of cervical cancer cells have been rarely investigated. Our previous study demonstrated that connexin 32 (Cx32) exerted an anti­apoptotic effect on cervical cancer. However, as an important regulator of apoptosis, whether the autophagy is involved in the function of Cx32 on cervical cancer cells is not well defined. The present study aimed to investigate the role of Cx32 on autophagy and apoptosis inhibition in cervical cancer cells. The expression levels of Cx32 and the autophagy­associated protein LC3­â…¡ in paracancerous cervical tissues (n=30) and cervical cancer (n=50) tissues were determined via western blotting. In total, 45 cervical cancer specimens were used to evaluate the clinical relevance of Cx32 and LC3­â…¡. It was found that both Cx32 and LC3­â…¡ were upregulated in cervical cancer tissues compared with those in paracancerous cervical tissues. The effect of Cx32 on autophagy was examined by detecting the change of LC3­â…¡ using western blotting, transfection with enhanced green fluorescent protein­LC3 plasmid and transmission electron microscopy analysis. Overexpression of Cx32 significantly enhanced autophagy in HeLa­Cx32 cells, whereas knockdown of Cx32 suppressed autophagy in C­33A cells. The flow cytometry results demonstrated that Cx32 inhibited the apoptosis of cervical cancer cells by promoting autophagy. Moreover, Cx32 triggered autophagy via the activation of the AMP­activated protein kinase (AMPK) signalling, regardless of the presence or absence of GJs. Collectively, it was identified that Cx32 exerted its anti­apoptotic effect by activating autophagy via the AMPK pathway in cervical cancer, which demonstrates a novel mechanism for Cx32 in human cervical cancer progression.

Connexin32 activates necroptosis through Src-mediated inhibition of caspase 8 in hepatocellular carcinoma.

Necroptosis is an alternative form of programmed cell death that generally occurs under apoptosis-deficient conditions. Our previous work showed that connexin32 (Cx32) promotes the malignant progress of hepatocellular carcinoma (HCC) by enhancing the ability of resisting apoptosis in vivo and in vitro. Whether triggering necroptosis is a promising strategy to eliminate the apoptosis-resistant HCC cells with high Cx32 expression remains unknown. In this study, we found that Cx32 expression was positively correlated with the expression of necroptosis protein biomarkers in human HCC specimens, cell lines, and a xenograft model. Treatment with shikonin, a well-used necroptosis inducer, markedly caused necroptosis in HCC cells. Interestingly, overexpressed Cx32 exacerbated shikonin-induced necroptosis, but downregulation of Cx32 alleviated necroptosis in vitro and in vivo. Mechanistically, Cx32 was found to bind to Src and promote Src-mediated caspase 8 phosphorylation and inactivation, which ultimately reduced the activated caspase 8-mediated proteolysis of receptor-interacting serine-threonine protein kinase 1/3, the key molecule for necroptosis activation. In conclusion, we showed that Cx32 contributed to the activation of necroptosis in HCC cells through binding to Src and then mediating the inactivation of caspase 8. The present study suggested that necroptosis inducers could be more favorable than apoptosis inducers to eliminate HCC cells with high expression of Cx32.

GJA1-20k attenuates Ang II-induced pathological cardiac hypertrophy by regulating gap junction formation and mitochondrial function.

Cardiac hypertrophy (CH) is characterized by an increase in cardiomyocyte size, and is the most common cause of cardiac-related sudden death. A decrease in gap junction (GJ) coupling and mitochondrial dysfunction are important features of CH, but the mechanisms of decreased coupling and energy impairment are poorly understood. It has been reported that GJA1-20k has a strong tropism for mitochondria and is required for the trafficking of connexin 43 (Cx43) to cell-cell borders. In this study, we investigated the effects of GJA1-20k on Cx43 GJ coupling and mitochondrial function in the pathogenesis of CH. We performed hematoxylin-eosin (HE) and Masson staining, and observed significant CH in 18-week-old male spontaneously hypertensive rats (SHRs) compared to age-matched normotensive Wistar-Kyoto (WKY) rats. In cardiomyocytes from SHRs, the levels of Cx43 at the intercalated disc (ID) and the expression of GJA1-20k were significantly reduced, whereas JAK-STAT signaling was activated. Furthermore, the SHR rats displayed suppressed mitochondrial GJA1-20k and mitochondrial biogenesis. Administration of valsartan (10 mg· [Formula: see text] d-1, i.g., for 8 weeks) prevented all of these changes. In neonatal rat cardiomyocytes (NRCMs), overexpression of GJA1-20k attenuated Ang II-induced cardiomyocyte hypertrophy and caused elevated levels of GJ coupling at the cell-cell borders. Pretreatment of NRCMs with the Jak2 inhibitor AG490 (10 µM) blocked Ang II-induced reduction in GJA1-20k expression and Cx43 gap junction formation; knockdown of Jak2 in NRCMs significantly lessened Ang II-induced cardiomyocyte hypertrophy and normalized GJA1-20k expression and Cx43 gap junction formation. Overexpression of GJA1-20k improved mitochondrial membrane potential and respiration and lowered ROS production in Ang II-induced cardiomyocyte hypertrophy. These results demonstrate the importance of GJA1-20k in regulating gap junction formation and mitochondrial function in Ang II-induced cardiomyocyte hypertrophy, thus providing a novel therapeutic strategy for patients with cardiomyocyte hypertrophy.

Nitric oxide affects cisplatin cytotoxicity oppositely in A2780 and A2780-CDDP cells via the connexin32/gap junction.

Chemoresistance is a main obstacle in ovarian cancer therapy and new treatment strategies and further information regarding the mechanism of the medication cisplatin are urgently needed. Nitric oxide has a critical role in modulating the activity of chemotherapeutic drugs. Our previous work showed that connexin32 contributed to cisplatin resistance. However, whether nitric oxide is involved in connexin32-mediated cisplatin resistance remains unknown. In this study, using A2780 and A2780 cisplatin-resistant cells, we found that S-nitroso-N-acetyl-penicillamine, a nitric oxide donor, attenuated cisplatin toxicity by decreasing gap junctions in A2780 cells. Enhancement of gap junctions using retinoic acid reversed the effects of S-nitroso-N-acetyl-penicillamine on cisplatin toxicity. In A2780 cisplatin-resistant cells, however, S-nitroso-N-acetyl-penicillamine enhanced cisplatin toxicity by decreasing connexin32 expression. Downregulation of connexin32 expression by small interfering RNA exacerbated the effects of S-nitroso-N-acetyl-penicillamine on cisplatin cytotoxicity and upregulation of connexin32 expression by pcDNA transfection reversed the effects of S-nitroso-N-acetyl-penicillamine on cisplatin cytotoxicity. Our study suggests for the first time that combining cisplatin with nitric oxide in clinical therapies for ovarian cancer should be avoided before cisplatin resistance emerges. The present study provides a productive area of further study for increasing the efficacy of cisplatin by combining cisplatin with the specific inhibitors or enhancers of nitric oxide in clinical treatment.

Detailed Molecular Mechanism and Potential Drugs for COL1A1 in Carboplatin-Resistant Ovarian Cancer.

Carboplatin resistance in ovarian cancer (OV) is a major medical problem. Thus, there is an urgent need to find novel therapeutic targets to improve the prognosis of patients with carboplatin-resistant OV. Accumulating evidence indicates that the gene COL1A1 (collagen type I alpha 1 chain) has an important role in chemoresistance and could be a therapeutic target. However, there have been no reports about the role of COL1A1 in carboplatin-resistant OV. This study aimed to establish the detailed molecular mechanism of COL1A1 and predict potential drugs for its treatment. We found that COL1A1 had a pivotal role in carboplatin resistance in OV by weighted gene correlation network analysis and survival analysis. Moreover, we constructed a competing endogenous RNA network (LINC00052/SMCR5-miR-98-COL1A1) based on multi-omics data and experiments to explore the upstream regulatory mechanisms of COL1A1. Two key pathways involving COL1A1 in carboplatin resistance were identified by co-expression analysis and pathway enrichment: the "ECM-receptor interaction" and "focal adhesion" Kyoto Encyclopedia of Genes and Genomes pathways. Furthermore, combining these results with those of cell viability assays, we proposed that ZINC000085537017 and quercetin were potential drugs for COL1A1 based on virtual screening and the TCMSP database, respectively. These results might help to improve the outcome of OV in the future.

Identification of a Five-Gene Prognostic Model and Its Potential Drug Repurposing in Colorectal Cancer Based on TCGA, GTEx and GEO Databases.

Colorectal cancer (CRC) is a major cause of cancer deaths worldwide. Unfortunately, many CRC patients are still being diagnosed at an advanced stage of the cancer, and the 5-year survival rate is only ~30%. Effective prognostic markers of CRC are therefore urgently needed. To address this issue, we performed a detailed bioinformatics analysis based on the Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Gene Expression Omnibus (GEO) databases to identify prognostic biomarkers for CRC, which in turn help in exploring potential drug-repurposing. We identified five hub genes (PGM2, PODXL, RHNO1, SCD, and SEPHS1), which had good performance in survival prediction and might be involved in CRC through three key pathways ("Cell cycle," "Purine metabolism," and "Spliceosome" KEGG pathways) identified by a KEGG pathway enrichment analysis. What is more, we performed a co-expression analysis between five hub genes and transcription factors to explore the upstream regulatory region. Furthermore, we screened the potential drug-repurposing for the five hub genes in CRC according to the Binding DB and ZINC15 databases. Taking together, we constructed a five-gene signature to predict overall survival of CRC and found the potential drug-repurposing, which may improve the outcome of CRC in the future.

Synthesis, structure-activity relationships and preliminary mechanism study of N-benzylideneaniline derivatives as potential TLR2 inhibitors.

Toll-like receptor 2 (TLR2) can recognize pathogen-associated molecular patterns to defense against invading organisms and has been represents an attractive therapeutic target. Until today, none TLR2 small molecule antagonist have been developed in clinical trial. Herein, we designed and synthesized 50 N-benzylideneaniline compounds with the help of CADD. And subsequent in vitro studies leading to the optimized compound SMU-A0B13 with most potent inhibitory activity to TLR2 (IC50=18.21 ±â€¯0.87 µM). Preliminary mechanism studies indicated that this TLR2 inhibitor can work through the NF-κB signaling pathway with high specificity and low toxicity, and can also efficiently downregulate inflammatory cytokines, such as SEAP, TNF-α and NO in HEK-Blue hTLR2, human PBMC and Raw 264.7 cell lines. Additionally, the docking situation also indicate SMU-A0B13 can well bind to the TLR2-TIR (PDB: 1FYW) active domain, which probably explains the bioactivity.