Comparative Proteomics Analysis Reveals the Reversal Effect of Cryptotanshinone on Gefitinib-Resistant Cells in Epidermal Growth Factor Receptor-Mutant Lung Cancer.

Cryptotanshinone (CTS) is a lipophilic constituent of Salvia miltiorrhiza, with a broad-spectrum anticancer activity. We have observed that CTS enhances the efficacy of gefitinib in human lung cancer H1975 cells, yet little is known about its molecular mechanism. To explore how CTS enhances H1975 cell sensitivity to gefitinib, we figured out differential proteins of H1975 cells treated by gefitinib alone or in combination with CTS using label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) bioinformatic analyses of the differential proteins were performed. CTS enhanced H1975 cell sensitivity to gefitinib in vitro and in vivo, with 115 and 128 differential proteins identified, respectively. GO enrichment, KEGG analysis, and PPI network comprehensively demonstrated that CTS mainly impacted the redox process and fatty acid metabolism in H1975 cells. Moreover, three differential proteins, namely, catalase (CAT), heme oxygenase 1 (HMOX1), and stearoyl-CoA desaturase (SCD) were validated by RT-qPCR and Western blot. In conclusion, we used a proteomic method to study the mechanism of CTS enhancing gefitinib sensitivity in H1975 cells. Our finding reveals the potential protein targets of CTS in overcoming gefitinib resistance, which may be therapeutical targets in lung cancer.

Cryptotanshinone strengthens the effect of gefitinib against non-small cell lung cancer through inhibiting transketolase.

Lung cancer is the leading cause of cancer-related mortality and causes more than a million deaths per year. Gefitinib is the first-line agent of advanced lung cancer, however, resistance to gefitinib becomes a major problem in clinical application. Transketolase (TKT) is a key enzyme functioning between the oxidative arm and the non-oxidative arm of the pentose phosphate pathway. In this study, we firstly found that the expression of TKT was remarkably up-regulated in NSCLC cells, while the knockdown of TKT could inhibit cell proliferation and enhance the effect of gefitinib on NSCLC cells, which indicated the role of TKT in treating advanced lung cancer. Cryptotanshinone (CTS) is a natural active compound possessing anti-cancer effect. Here we demonstrated that CTS could strengthen the effect of gefitinib on NSCLC cells via inhibition of TKT in vitro and in vivo. Moreover, Nrf2 was involved in the repression of CTS on TKT expression. Collectively, these findings indicated the role of TKT in lung cancer progression and may provide novel therapeutic strategies to overcome resistance to gefitinib. Furthermore, CTS may serve as a new candidate in adjuvant treatment of advanced lung cancer.

Sesamin Enhances Nrf2-Mediated Protective Defense against Oxidative Stress and Inflammation in Colitis via AKT and ERK Activation.

Ulcerative colitis (UC) is a major form of inflammatory bowel disease (IBD) with high incidence and prevalence in many countries. Patients with UC usually suffer from a lifetime of debilitating physical symptoms. Therefore, developing effective therapeutic strategy that can manage this disease better and improve patients' life quality is in urgent need. Sesamin (SSM) is a lignan derived from sesame seeds. In this study, the protective effect of SSM against UC and the underlying mechanism were investigated in vitro and in vivo. Our data showed that SSM protected Caco-2 cells from H2O2-induced oxidative stress injury via GSH-mediated scavenging of reactive oxygen species (ROS). Dual luciferase reporter assay showed that the transcriptional activity of nuclear factor erythroid-related factor 2 (Nrf2) was significantly increased by SSM, and the ability of SSM to activate Nrf2-targeted genes was further confirmed in Caco-2 cells using western blot and quantitative real-time PCR (qRT-PCR). In contrast, Nrf2 knockdown abolished the protective effect of SSM. Additionally, we found that SSM also activated advanced protein kinase B (AKT) and extracellular signal-regulated kinase (ERK) in Caco-2 cells, while either AKT or ERK inhibition can prevent SSM-mediated nuclear translocation of Nrf2. Furthermore, SSM displayed a better protective effect against dextran sulfate sodium- (DSS-) induced UC compared with 5-aminosalicylic acid (5-ASA) in C57BL/6 mice. The enhanced Nrf2 signaling and activated AKT/ERK were also observed in the colon of mice after SSM administration. These results first demonstrate the protective effect of SSM against UC and indicate that the effect is associated with AKT/ERK activation and subsequent Nrf2 signaling enhancement. This study provides a new insight into the medicinal value of SSM and proposes it as a new natural nutrition for better managing the symptoms of UC.

Inhibition of Glucose-6-Phosphate Dehydrogenase Reverses Cisplatin Resistance in Lung Cancer Cells via the Redox System.

The pentose phosphate pathway (PPP), which branches from glycolysis, is correlated with cancer cell proliferation, survival and senescence. In this study, differences in the metabolic profile of the PPP and the redox status of human lung carcinoma A549 cells and cisplatin-induced multidrug-resistant A549/DDP cells were analyzed and evaluated. The results showed that A549/DDP cells exhibited differential PPP-derived metabolic features and redox-related molecules. A549/DDP cells exhibited increased expression and enzymatic activity of PPP enzyme glucose-6-phosphate dehydrogenase (G6PD). Furthermore, as demonstrated by the apoptotic rate, cell viability, and colony formation, inhibition of G6PD by siRNA or an inhibitor sensitized A549/DDP cells to cisplatin. Additionally, inhibition of G6PD restored the cisplatin sensitivity of A549/DDP cells by influencing redox homeostasis. In conclusion, overcoming cisplatin resistance through inhibition of G6PD could improve the understanding of the mechanisms underlying cisplatin-induced resistance in human lung cancer and may provide insights into the therapeutic potential of this treatment to combat resistance.

Valproate induced hepatic steatosis by enhanced fatty acid uptake and triglyceride synthesis.

Steatosis is the characteristic type of VPA-induced hepatotoxicity and may result in life-threatening hepatic lesion. Approximately 61% of patients treated with VPA have been diagnosed with hepatic steatosis through ultrasound examination. However, the mechanisms underlying VPA-induced intracellular fat accumulation are not yet fully understood. Here we demonstrated the involvement of fatty acid uptake and lipogenesis in VPA-induced hepatic steatosis in vitro and in vivo by using quantitative real-time PCR (qRT-PCR) analysis, western blotting analysis, fatty acid uptake assays, Nile Red staining assays, and Oil Red O staining assays. Specifically, we found that the expression of cluster of differentiation 36 (CD36), an important fatty acid transport, and diacylglycerol acyltransferase 2 (DGAT2) were significantly up-regulated in HepG2 cells and livers of C57B/6J mice after treatment with VPA. Furthermore, VPA treatment remarkably enhanced the efficiency of fatty acid uptake mediated by CD36, while this effect was abolished by the interference with CD36-specific siRNA. Also, VPA treatment significantly increased DGAT2 expression as a result of the inhibition of mitogen-activated protein kinase kinase (MEK) - extracellular regulated kinase (ERK) pathway; however, DGAT2 knockdown significantly alleviated VPA-induced intracellular lipid accumulation. Additionally, we also found that sterol regulatory element binding protein-1c (SREBP-1c)-mediated fatty acid synthesis may be not involved in VPA-induced hepatic steatosis. Overall, VPA-triggered over-regulation of CD36 and DGAT2 could be helpful for a better understanding of the mechanisms underlying VPA-induced hepatic steatosis and may offer novel therapeutic strategies to combat VPA-induced hepatotoxicity.