Probiotic Escherichia coli Nissle inhibits IL-6 and MAPK-mediated cardiac hypertrophy during STZ-induced diabetes in rats

Escherichia coli Nissle (EcN), a probiotic bacterium protects against several disorders. Multiple reports have studied the pathways involved in cardiac hypertrophy. However, the effects of probiotic EcN against diabetes-induced cardiac hypertrophy remain to be understood. We administered five weeks old Wistar male (271±19.4 g body weight) streptozotocin-induced diabetic rats with 10⁹ cfu of EcN via oral gavage every day for 24 days followed by subjecting the rats to echocardiography to analyse the cardiac parameters. Overexpressed interleukin (IL)-6 induced the MEK5/ERK5, JAK2/STAT3, and MAPK signalling cascades in streptozotocin-induced diabetic rats. Further, the upregulation of calcineurin, NFATc3, and p-GATA4 led to the elevation of hypertrophy markers, such as atrial and B-type natriuretic peptides. In contrast, diabetic rats supplemented with probiotic EcN exhibited significant downregulated IL-6. Moreover, the MEK5/ERK5 and JAK2/STAT3 cascades involved during eccentric hypertrophy and MAPK signalling, including phosphorylated MEK, ERK, JNK, and p-38, were significantly attenuated in diabetic rats after supplementation of EcN. Western blotting and immunofluorescence revealed the significant downregulation of NFATc3 and downstream mediators, thereby resulting in the impairment of cardiac hypertrophy. Taken together, the findings demonstrate that supplementing probiotic EcN has the potential to show cardioprotective effects by inhibiting diabetes-induced cardiomyopathies.

MDM2 expression in areca quid chewing-associated oral squamous cell carcinomas in Taiwan

MDM2 (murine double minute gene 2) overexpression has been implicated in the pathogenesis of human tumors via inhibition of the p53 tumor suppressor protein. To investigate the potential involvement of MDM2 overexpression in the pathogenesis of oral squamous cell carcinomas (SCCs) in Taiwan, we examined the expression of MDM2 protein and its relationship to p53 protein levels in 52 oral SCCs using antibodies to MDM2 and p53. Of the 52 patients, 36 (69 %) had tumors with positive MDM2 nuclear staining and 32 (61%) had tumors with p53 nuclear staining. Co-expression of MDM2 protein and p53 was detected in 25 (48%) cases; and 9 (17%) tumors showed neither MDM2 protein nor p53 staining. A significant correlation was observed between MDM2 protein and p53 expression in 38 cases with an areca quid (AQ) chewing habit (P=0.032). No significant correlation was found between the degree of MDM2 protein staining and the patients' ages, sex, cancer location, clinical staging, primary tumor TNM status or histological differentiation of SCC at the time of initial presentation. Kaplan-Meier analysis showed that either MDM2 protein expression or co-expression of p53 and MDM2 protein did not relate significantly to patient overall survival. Nevertheless, the high prevalence of MDM2 protein overexpression found in this study suggest that MDM2 may also participate in the carcinogenesis of AQ chewing-associated oral SCCs in Taiwan.

Induction of the c-jun protooncogene expression by areca nut extract and arecoline on oral mucosal fibroblasts

To investigate the mechanisms of areca quid (AQ)-induced carcinogenesis, expression of c-fos and c-jun protooncogenes was examined in human oral mucosal fibroblasts after exposure to areca nut extracts (ANE) or arecoline. We found that treatment of cells with 200 microg/ml ANE or 10 microg/ml arecoline for 1 h induced about three-fold increase in c-jun mRNA levels. This increase was transient and the level of c-jun mRNAs returned rapidly to control levels thereafter. However, ANE and arecoline did not induce c-fos mRNA expression at detectable levels. During AQ chewing, oral mucosal cells are continuously stimulated by ANE and arecoline. Persistent induction of the c-jun protooncogene by ANE and arecoline may be one of the mechanisms in the carcinogenesis of oral squamous cell carcinoma in Taiwan. Furthermore, we observed that pre-incubation of cells with either N-acetyl-cysteine [a glutathione (GSH) precursor] or L-buthionine-S,R-sulfoximine (a specific inhibitor of GSH biosynthesis) had a minimal effect on arecoline-induced c-jun expression. Therefore, arecoline-induced c-jun expression is independent of GSH depletion.