EGF-receptor phosphorylation and downstream signaling are activated by genistein during subacute liver damage.

The epidermal growth factor receptor (EGFR) plays an important role on hepatic protection in acute and chronic liver injury. The aim of this study was to investigate the role of genistein on EGFR expression, phosphorylation and signaling pathways in experimental subacute liver damage induced by carbon tetrachloride (CCl4). We used male Wistar rats that were randomly divided into four groups: (1) Control; (2) Genistein 5 mg/kg per oral; (3) Subacute liver damage induced by CCl4 4 mg/kg subcutaneously; and (4) Animals received CCl4 and genistein at the dosage indicated. The effect of genistein on EGFR expression, phosphorylation and signaling pathways were investigated by western blot and densitometric analyses. Histological changes were evaluated on slices stained with Hematoxylin-Eosin and Masson´s trichromic, as well as an immunohistochemical analysis for proliferating cell nuclear antigen (PCNA). Additionally, pro-inflammatory cytokines and liver enzymes were quantified. Our study showed that genistein increased EGFR expression, EGFR-specific tyrosine residues phosphorylation (pY1068-EGFR and pY84-EGFR), signal transducer and activator of transcription phosphorylation (pSTAT5), protein kinase B phosphorylation (pAKT) and PCNA in animals with CCl4-induced subacute liver damage. It was found a significant reduction of pro-inflammatory cytokines in serum from animals with subacute liver damage treated with genistein. Those effects were reflected in an improvement in the architecture and liver function. In conclusion, genistein can induce a transactivation of EGFR leading to downstream cell signaling pathways as early events associated with regeneration and hepatoprotection following subacute liver damage.

Wnt/ß­catenin pathway activation and silencing of the APC gene in HPV­positive human cervical cancer­derived cells.

Although persistent infections with high­risk human papilloma virus (HPV) constitute the most significant cofactor for the development of cervical cancer, they are insufficient on their own. Mutations or epigenetic inactivation of the tumor suppressor adenomatous polyposis coli (APC), the two acting as prominent oncogenic mechanisms in a number of types of cancer, are frequently associated with aberrant activation of the Wnt/ß­catenin pathway. According to these observations, it was hypothesized that APC alteration may lead to ß­catenin deregulation and the abnormal expression of direct targets of the Wnt pathway in HPV­infected cervical cancer cells. The present study confirmed that the stabilization of ß­catenin correlates with enhanced transcriptional activity of the ß­catenin/T­cell factor complex in cervical cancer cell lines. Sequence analysis of the 'hot­spot' in the mutation cluster region did not exhibit genetic alterations that may be associated with APC gene inactivation. In addition, it was identified that there was a good correlation with the hypermethylation status of the APC promoter 1A and the abnormal accumulation of endogenous ß­catenin in cell lines and biopsies infected with HPV16, although not HPV18. Removal of the epigenetic markers led to an increase in APC levels and a reduction of ß­catenin expression in two transcriptional targets of the Wnt pathway: Matrix metalloproteinase­7 and vascular endothelial growth factor. The present study suggested that the increase in Wnt activity in certain cervical cancer­derived cells may be associated with an alteration in the methylation status of the APC gene promoter 1A.