Proteomic analysis of oxidized proteins in the brain and liver of the Nile tilapia (Oreochromis niloticus) exposed to a water-accommodated fraction of Maya crude oil.

Crude oil (CO) is a super mixture of chemical compounds whose toxic effects are reported in fish species according to international guidelines. In the current study a proteomic analysis of oxidized proteins (ox) was performed on the brain and liver of Nile tilapia exposed to WAF obtained from relevant environmental loads (0.01, 0.1 and 1.0 g/L) of Maya CO. Results have shown that oxidation of specific proteins was a newly discovered organ-dependent process able to disrupt key functions in Nile tilapia. In control fish, enzymes involved on aerobic metabolism (liver aldehyde dehydrogenase and brain dihydrofolate reductase) and liver tryptophan--tRNA ligase were oxidized. In WAF-treated liver specimens, fructose-bisphosphate aldolase (FBA), ß-galactosidase (ß-GAL) and dipeptidyl peptidase 9 (DPP-9) were detected in oxidized form. oxDPP-9 could be favorable by reducing the risk associated with altered glucose metabolism, the opposite effects elicited by oxFBA and oxß-GAL. oxTrypsin showed a clear adverse effect by reducing probably the hepatocyte capacity to achieve proteolysis of oxidized proteins as well as for performing the proper digestive function. Additionally, enzyme implicated in purine metabolism adenosine (deaminase) was oxidized. Cerebral enzymes of mitochondrial respiratory chain complex (COX IV, COX5B), of glycosphingolipid biosynthesis (ß-N-acetylhexosaminidase), involved in catecholamines degradation (catechol O-methyltransferase), and microtubule cytoskeleton (stathmin) were oxidized in WAF-treated specimens. This response suggests, in the brain, an adverse scenario for the mitochondrial respiration process and for ATP provision as for ischemia/reoxygenation challenges. Proteomic analysis of oxidized proteins is a promising tool for monitoring environmental quality influenced by hydrocarbons dissolved in water.

Activation of an AKT/FOXM1/STMN1 pathway drives resistance to tyrosine kinase inhibitors in lung cancer.

BACKGROUND: Tyrosine kinase inhibitors (TKIs) have demonstrated clinical benefits in the treatment of several tumour types. However, the emergence of TKI resistance restricts the therapeutic effect. This study uses non-small cell lung cancer (NSCLC) to explore the mechanisms contributing to TKI resistance in tumours. METHODS: Biological phenotypes and RNA microarray expression data were analysed in NSCLC cells with and without TKI pretreatment. Specific inhibitors and siRNAs were used to validate the direct involvement of an AKT/FOXM1/STMN1 pathway in TKI resistance. Patients' tissues were analysed to explore the clinical importance of FOXM1 and STMN1. RESULTS: In vitro and in vivo studies showed that TKIs induced the enrichment of cancer stem cells (CSC), promoted epithelial to mesenchymal transition (EMT), and conferred multidrug resistance on NSCLC cells in a cell type- and TKI class-dependent manner. Mechanistically, TKIs activated an AKT/FOXM1/STMN1 pathway. The crucial role of this pathway in TKI-induced enrichment of CSC and drug resistance was verified by silencing FOXM1 and STMN1 or blocking the AKT pathway. Additionally, overexpression of STMN1 was associated with upregulation of FOXM1 in advanced NSCLC patients, and STMN1/FOXM1 upregulation predicted a poor outcome. CONCLUSIONS: Our findings elucidate an additional common mechanism for TKI resistance and provide a promising therapeutic target for reversing TKI resistance in NSCLC.

[Effect of gallnut extract on nasopharyngeal carcinoma 5-8F cells and its mechanism].

OBJECTIVE: To determine the biological activity of ellagic acid extracted from gallnut against nasopharyngeal carcinoma and its molecular mechanism. METHODS: Nasopharyngeal carcinoma 5-8F cells were treated with 2, 4, 6 µg/mL ellagic acid for 48 h in vitro. The cell proliferation and cell apoptosis were analyzed by MTT and Hoechst33258 stain. The cell cycle and protein expression were measured by flow cytometry and Western blot. RESULTS: Ellagic acid inhibited the proliferation of 5-8F cells. The inhibition rates were (29.35±4.95)%, (53.32 ±4.44)% and ( 61.75 + 6.93)%, respectively, with significant difference from the control group (P<0.01). S phase cells in the experimental groups were (25.47±0.74)%, (28.08±1.41)% and (35.49±0.66)%, respectively, with significant difference (P<0.01) from the control group (21.26±0.70)%. Cells in the experimental groups showed nuclear pyknosis, karyorrhexis and poptotic cell morphology. The expression of COX-2 and stathmin in 5-8F cells was down-regulated with increased drug concentration. CONCLUSION: Ellagic acid extracted from gallnut has activity against nasopharyngeal carcinoma cells, and its mechanism may be related to down-regulated expression of COX-2 and stathmin.

Proteomic analysis of the molecular response of Raji cells to maslinic acid treatment.

Maslinic acid, a natural pentacyclic triterpene has been shown to inhibit growth and induce apoptosis in some tumour cell lines. We studied the molecular response of Raji cells towards maslinic acid treatment. A proteomics approach was employed to identify the target proteins. Seventeen differentially expressed proteins including those involved in DNA replication, microtubule filament assembly, nucleo-cytoplasmic trafficking, cell signaling, energy metabolism and cytoskeletal organization were identified by MALDI TOF-TOF MS. The down-regulation of stathmin, Ran GTPase activating protein-1 (RanBP1), and microtubule associated protein RP/EB family member 1 (EB1) were confirmed by Western blotting. The study of the effect of maslinic acid on Raji cell cycle regulation showed that it induced a G1 cell cycle arrest. The differential proteomic changes in maslinic acid-treated Raji cells demonstrated that it also inhibited expression of dUTPase and stathmin which are known to induce early S and G2 cell cycle arrests. The mechanism of maslinic acid-induced cell cycle arrest may be mediated by inhibiting cyclin D1 expression and enhancing the levels of cell cycle-dependent kinase (CDK) inhibitor p21 protein. Maslinic acid suppressed nuclear factor-kappa B (NF-κB) activity which is known to stimulate expression of anti-apoptotic and cell cycle regulatory gene products. These results suggest that maslinic acid affects multiple signaling molecules and inhibits fundamental pathways regulating cell growth and survival in Raji cells.

Stathmin and tubulin expression and survival of ovarian cancer patients receiving platinum treatment with and without paclitaxel.

BACKGROUND: Paclitaxel interacts with microtubules to exert therapeutic effects. Molecules that affect microtubule activity, such as betaIII-tubulin and stathmin, may interfere with the treatment. In this study, the authors analyzed betaIII-tubulin and stathmin expression in ovarian tumors and examined their associations with treatment response and patient survival. METHODS: The study included 178 patients with epithelial ovarian cancer who underwent cytoreductive surgery followed by platinum-based chemotherapy; of these patients, 75 also received paclitaxel. Fresh tumor samples that were collected at surgery were analyzed for messenger RNA expression of betaIII-tubulin and stathmin using real-time polymerase chain reaction analysis. Associations of these molecules with treatment response, disease progression, and overall survival were evaluated. RESULTS: High stathmin expression was associated with worse disease progression-free and overall survival compared with low stathmin expression. This association was independent of patient age, disease stage, tumor grade, histology, and residual tumor size and was observed in patients who received platinum plus paclitaxel, but not in patients who received platinum without paclitaxel, suggesting that stathmin expression in tumor tissue may interfere with paclitaxel treatment. Similar effects were not observed for betaIII-tubulin, although high betaIII-tubulin expression was associated with disease progression among patients who received platinum without paclitaxel. No associations were observed between treatment response and tubulin or stathmin expression. Expression levels of betaIII-tubulin and stathmin were correlated significantly. CONCLUSIONS: High stathmin expression predicted an unfavorable prognosis in patients with ovarian cancer who received paclitaxel and platinum chemotherapy. This finding supports the possibility that stathmin may interfere with paclitaxel treatment, leading to a poor prognosis for patients with ovarian cancer.