The antiarrhythmic drugs amiodarone and dronedarone inhibit intoxication of cells with pertussis toxin.

Pertussis toxin (PT) is a virulent factor produced by Bordetella pertussis, the causative agent of whooping cough. PT exerts its pathogenic effects by ADP-ribosylating heterotrimeric G proteins, disrupting cellular signaling pathways. Here, we investigate the potential of two antiarrhythmic drugs, amiodarone and dronedarone, in mitigating PT-induced cellular intoxication. After binding to cells, PT is endocytosed, transported from the Golgi to the endoplasmic reticulum where the enzyme subunit PTS1 is released from the transport subunit of PT. PTS1 is translocated into the cytosol where it ADP-ribosylates inhibitory α-subunit of G-protein coupled receptors (Gαi). We showed that amiodarone and dronedarone protected CHO cells and human A549 cells from PT-intoxication by analyzing the ADP-ribosylation status of Gαi. Amiodarone had no effect on PT binding to cells or in vitro enzyme activity of PTS1 but reduced the signal of PTS1 in the cell suggesting that amiodarone interferes with intracellular transport of PTS1. Moreover, dronedarone mitigated the PT-mediated effect on cAMP signaling in a cell-based bioassay. Taken together, our findings underscore the inhibitory effects of amiodarone and dronedarone on PT-induced cellular intoxication, providing valuable insights into drug repurposing for infectious disease management.

The Chaperonin TRiC/CCT Inhibitor HSF1A Protects Cells from Intoxication with Pertussis Toxin.

Pertussis toxin (PT) is a bacterial AB5-toxin produced by Bordetella pertussis and a major molecular determinant of pertussis, also known as whooping cough, a highly contagious respiratory disease. In this study, we investigate the protective effects of the chaperonin TRiC/CCT inhibitor, HSF1A, against PT-induced cell intoxication. TRiC/CCT is a chaperonin complex that facilitates the correct folding of proteins, preventing misfolding and aggregation, and maintaining cellular protein homeostasis. Previous research has demonstrated the significance of TRiC/CCT in the functionality of the Clostridioides difficile TcdB AB-toxin. Our findings reveal that HSF1A effectively reduces the levels of ADP-ribosylated Gαi, the specific substrate of PT, in PT-treated cells, without interfering with enzyme activity in vitro or the cellular binding of PT. Additionally, our study uncovers a novel interaction between PTS1 and the chaperonin complex subunit CCT5, which correlates with reduced PTS1 signaling in cells upon HSF1A treatment. Importantly, HSF1A mitigates the adverse effects of PT on cAMP signaling in cellular systems. These results provide valuable insights into the mechanisms of PT uptake and suggest a promising starting point for the development of innovative therapeutic strategies to counteract pertussis toxin-mediated pathogenicity.

Domperidone Inhibits Clostridium botulinum C2 Toxin and Bordetella pertussis Toxin.

Bordetella pertussis toxin (PT) and Clostridium botulinum C2 toxin are ADP-ribosylating toxins causing severe diseases in humans and animals. They share a common translocation mechanism requiring the cellular chaperones Hsp90 and Hsp70, cyclophilins, and FK506-binding proteins to transport the toxins' enzyme subunits into the cytosol. Inhibitors of chaperone activities have been shown to reduce the amount of transported enzyme subunits into the cytosol of cells, thus protecting cells from intoxication by these toxins. Recently, domperidone, an approved dopamine receptor antagonist drug, was found to inhibit Hsp70 activity. Since Hsp70 is required for cellular toxin uptake, we hypothesized that domperidone also protects cells from intoxication with PT and C2. The inhibition of intoxication by domperidone was demonstrated by analyzing the ADP-ribosylation status of the toxins' specific substrates. Domperidone had no inhibitory effect on the receptor-binding or enzyme activity of the toxins, but it inhibited the pH-driven membrane translocation of the enzyme subunit of the C2 toxin and reduced the amount of PTS1 in cells. Taken together, our results indicate that domperidone is a potent inhibitor of PT and C2 toxins in cells and therefore might have therapeutic potential by repurposing domperidone to treat diseases caused by bacterial toxins that require Hsp70 for their cellular uptake.

Domperidone Protects Cells from Intoxication with Clostridioides difficile Toxins by Inhibiting Hsp70-Assisted Membrane Translocation.

Clostridioides difficile infections cause severe symptoms ranging from diarrhea to pseudomembranous colitis due to the secretion of AB-toxins, TcdA and TcdB. Both toxins are taken up into cells through receptor-mediated endocytosis, autoproteolytic processing and translocation of their enzyme domains from acidified endosomes into the cytosol. The enzyme domains glucosylate small GTPases such as Rac1, thereby inhibiting processes such as actin cytoskeleton regulation. Here, we demonstrate that specific pharmacological inhibition of Hsp70 activity protected cells from TcdB intoxication. In particular, the established inhibitor VER-155008 and the antiemetic drug domperidone, which was found to be an Hsp70 inhibitor, reduced the number of cells with TcdB-induced intoxication morphology in HeLa, Vero and intestinal CaCo-2 cells. These drugs also decreased the intracellular glucosylation of Rac1 by TcdB. Domperidone did not inhibit TcdB binding to cells or enzymatic activity but did prevent membrane translocation of TcdB's glucosyltransferase domain into the cytosol. Domperidone also protected cells from intoxication with TcdA as well as CDT toxin produced by hypervirulent strains of Clostridioides difficile. Our results reveal Hsp70 requirement as a new aspect of the cellular uptake mechanism of TcdB and identified Hsp70 as a novel drug target for potential therapeutic strategies required to combat severe Clostridioides difficile infections.

Risk factors for brain metastases in patients with non-small cell lung cancer: a meta-analysis of 43 studies.

BACKGROUND: Lung cancer is a leading cause of cancer-related mortality worldwide. The purpose of our meta-analysis was to assess the risk factors for brain metastases (BM) in patients with non-small cell lung cancer (NSCLC). METHODS: Multiple databases, including PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), and Wanfang, were systematically searched to recruit relevant studies investigating the risk factors for BM in NSCLC patients. The Newcastle-Ottawa Scale was used to evaluate literature quality, and the meta-analysis was performed using the Review Manager 5.3. Evidence quality evaluation was carried out according to the Grading of Recommendation Assessment, Development and Evaluation (GRADE) standard. The estimated odds ratio (OR) and 95% confidence intervals (CIs) were set as effect measures. Funnel plots and sensitivity analyses were used to assess publication bias and the robustness and reliability of the combined results, respectively. RESULTS: A total of 43 studies with 11,415 participants were included in this meta-analysis. The results indicated that the following factors were significantly associated with an increased risk of BM in NSCLC patients (P<0.05): (I) gender (female) (OR =1.32, 95% CI: 1.17-1.49, P<0.00001); (II) adenocarcinoma (OR =2.34, 95% CI: 1.76-3.11, P<0.00001) or non-squamous cell carcinoma (OR =0.63, 95% CI: 0.42-0.94, P=0.02); (III) advanced tumor stage (OR =1.48, 95% CI: 1.01-2.17, P=0.04); (IV) node stage (OR =2.19, 95% CI: 1.39-3.45, P=0.0007); (V) lymphatic metastasis (OR =2.43, 95% CI: 1.76-3.36, P<0.00001); (VI) epidermal growth factor receptor (EGFR) gene mutation (OR =1.88, 95% CI: 1.26-2.80, P=0.002); (VII) kirsten rat sarcoma viral oncogene (KRAS) gene mutation (OR =2.99, 95% CI: 1.82-4.91, P<0.00001); (VIII) higher levels of carcinoembryonic antigen (P<0.00001), carbohydrate antigen 199 (P<0.0001), cytokeratin-19 fragment (P=0.04), neuron-specific enolase (P<0.00001), and carbohydrate antigen 125 (P=0.0005). CONCLUSIONS: This meta-analysis demonstrated that NSCLC patients with BM have more aggressive clinical features.

Roles of S100 family members in drug resistance in tumors: Status and prospects.

Chemotherapy and targeted therapy can significantly improve survival rates in cancer, but multiple drug resistance (MDR) limits the efficacy of these approaches. Understanding the molecular mechanisms underlying MDR is crucial for improving drug efficacy and clinical outcomes of patients with cancer. S100 proteins belong to a family of calcium-binding proteins and have various functions in tumor development. Increasing evidence demonstrates that the dysregulation of various S100 proteins contributes to the development of drug resistance in tumors, providing a basis for the development of predictive and prognostic biomarkers in cancer. Therefore, a combination of biological inhibitors or sensitizers of dysregulated S100 proteins could enhance therapeutic responses. In this review, we provide a detailed overview of the mechanisms by which S100 family members influence resistance of tumors to cancer treatment, with a focus on the development of effective strategies for overcoming MDR.

Gambogenic acid inhibits the proliferation of small­cell lung cancer cells by arresting the cell cycle and inducing apoptosis.

Gambogenic acid (GNA), which is an important active compound present in gamboge, exerts anticancer activity in various types of tumor cells. However, the effect of GNA on small­cell lung cancer (SCLC) cell lines and the underlying mechanism involved still remain unclear. In the present study, GNA inhibited the proliferation and cell cycle progression of SCLC cells. GNA also promoted the apoptosis of SCLC cells in a dose­dependent manner, which is associated with modulating the levels of proteins involved in apoptosis pathways in NCI­H446 and NCI­H1688 cells. The results demonstrated that GNA increased the level of cleaved caspase­3, ­8 and ­9, and Bax but decreased the expression of anti­apoptotic protein, Bcl­2. Furthermore, similar results were obtained in a mouse tumor xenograft model. Additionally, GNA exhibit low toxicity in tissues when administered to mice in the SCLC xenograft models. Collectively, our findings demonstrated that GNA significantly inhibited the proliferation of SCLC cells and promoted cell apoptosis via cell cycle arrest and induction of apoptosis.