A Novel Drug Resistance Mechanism: Genetic Loss of Xeroderma Pigmentosum Complementation Group C (XPC) Enhances Glycolysis-Mediated Drug Resistance in DLD-1 Colon Cancer Cells.

The pro-apoptotic proteins BAX and BAK are critical regulatory factors constituting the apoptosis machinery. Downregulated expression of BAX and BAK in human colorectal cancer lead to chemotherapeutic failure and poor survival rate in patients. In this study, isogenic DLD-1 colon cancer cells and the BAX and BAK double knockout counterpart were used as the cellular model to investigate the role of BAX/BAK-associated signaling network and the corresponding downstream effects in the development of drug resistance. Our data suggested that DLD-1 colon cancer cells with BAX/BAK double-knockout were selectively resistant to a panel of FDA-approved drugs (27 out of 66), including etoposide. PCR array analysis for the transcriptional profiling of genes related to human cancer drug resistance validated the altered level of 12 genes (3 upregulated and 9 downregulated) in DLD-1 colon cancer cells lack of BAX and BAK expression. Amongst these genes, XPC responsible for DNA repairment and cellular respiration demonstrated the highest tolerance towards etoposide treatment accompanying upregulated glycolysis as revealed by metabolic stress assay in DLD-1 colon cancer cells deficient with XPC. Collectively, our findings provide insight into the search of novel therapeutic strategies and pharmacological targets to against cancer drug resistance genetically associated with BAX, BAK, and XPC, for improving the therapy of colorectal cancer via the glycolytic pathway.

2-Aminoethoxydiphenylborane sensitizes anti-tumor effect of bortezomib via suppression of calcium-mediated autophagy.

Non-small-cell lung cancer (NSCLC) accounts for most lung cancer cases. Therapeutic interventions integrating the use of different agents that focus on different targets are needed to overcome this set of diseases. The proteasome system has been demonstrated clinically as a potent therapeutic target for haematological cancers. However, promising preclinical data in solid tumors are yet to be confirmed in clinics. Herein, the combinational use of Bortezomib (BZM) and 2-aminoethoxydiphenylborane (2-APB) toward NSCLC cells was studied. We confirmed that BZM-triggered cytoprotective autophagy that may counteract with the cytotoxic effects of the drug per se. 2-APB was selected from screening of a commercial natural compounds library, which potentiated BZM-induced cytotoxicity. Such an enhancement effect was associated with 2-APB-mediated autophagy inhibition. In addition, we revealed that 2-APB suppressed calcium-induced autophagy in H1975 and A549 NSCLC cells. Interestingly, BZM [0.3 mg/kg/3 days] combined with 2-APB [2 mg/kg/day] significantly inhibited both primary (around 47% tumor growth) and metastatic Lewis lung carcinoma after a 20-day treatment. Our results suggested that BZM and 2-APB combination therapy can potentially be developed as a novel formulation for lung cancer treatment.

Irisin Alleviates Advanced Glycation End Products-Induced Inflammation and Endothelial Dysfunction via Inhibiting ROS-NLRP3 Inflammasome Signaling.

The activation of NLR family pyrin domain containing 3 (NLRP3) inflammasome have been implicated in the initiation or progression of atherosclerosis. Recent research showed that irisin, a newly discovered adipomiokine, alleviates endothelial dysfunction in type 2 diabetes partially via reducing oxidative/nitrative stresses, suggesting that irisin may be a promising candidate for the treatment of vascular complications of diabetes. However, the association between irisin and NLRP3 inflammasome in the pathogenesis of atherosclerosis remains unclear. In the present study, we cultured human umbilical vein endothelial cells (HUVECs) in advanced glycation end products (AGEs) medium; exogenous irisin (0.01, 0.1, 1 µg/ml) were used as an intervention reagent. siRNA and adenoviral vector were constructed to realize silencing and over-expression of NLRP3 gene. Our data showed that irisin significantly reversed AGEs-induced oxidative stress and NLRP3 inflammasome signaling activation (p < 0.05), and increased the endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) production in a dose-dependent manner (p < 0.05). siRNA-mediated knockdown NLRP3 facilitated the irisin-mediated anti-inflammatory and antiatherogenic effects (p < 0.05). However, these irisin-mediated effects were reversed by over-expression NLRP3 (p < 0.05). Taken together, our results reveal that irisin alleviates AGEs-induced inflammation and endothelial dysfunction via inhibiting ROS-NLRP3 inflammasome signaling, suggest a likely mechanism for irisin-induced therapeutic effect in vascular complications of diabetes.

Advanced glycation endproducts regulate smooth muscle cells calcification in cultured HSMCs.

OBJECTIVE: To investigate the mechanism of Advanced glycation end products (AGEs) promoting the calcification of smooth muscle cells. METHODS: The successfully cultured smooth muscle cells were divided into three groups: normal culture group (group A), calcified culture group (group B), calcification + AGEs group (group C); the concentration of intracellular calcium ion was detected in each group; the promotion of AGEs on the calcification of HSMCs was confirmed by VON KOSSA staining; and the expressions of ß-catenin, RAGE, ß-catenin, OPG and E-cadherin protein were detected by immunofluorescence and western blot. RESULTS: The morphology of the cells in each group showed that the amount of calcified plaques in calcification + AGES group were significantly higher than the calcification group. VON KOSSA staining showed that with increasing concentrations of AGE-BSA, the amount of its calcification gradually increased. Calcium concentration in Calcification + 20 mg/L AGEs group was significantly higher, followed by 40 mg/L AGEs group. The expression of ß-catenin increased with the increasing concentrations of AGEs. CONCLUSION: AGEs can promote the calcification of human femoral artery smooth muscle cells, with a concentration gradient effect. With increasing concentrations of AGEs, the expression of RAGE increased, indicating that AGEs-induced HSMCs proliferation was correlated with RAGE expression.