Disrupted phosphatidylinositol 3-kinase (PI3K) activity and its effect on the downstream target AKT plays an important role in malignant diseases. Gain and/or amplification of PIK3CA gene, encoding the catalytic subunit of phosphatidylinositol 3-kinase (p110 alpha) and its increased expression are associated with enhanced PI3K activity in ovarian cancer cell lines. In this study, ovarian carcinomas with documented clinical outcome were assessed for genetic aberrations at the 3q26.3 locus, including PIK3CA, by fluorescence in situ hybridization. PIK3CA amplification was evaluated by quantitative real-time PCR with respect to a control gene situated at 3q13. The expression of p110 alpha, phosphorylated AKT (pAKT) and the proliferation marker Ki-67 were immunohistochemically investigated. PIK3CA amplification and Ki-67 index were strong predictors for an early tumour-associated death. p110 alpha expression correlated with 3q26.3 gain and Ki-67 index but not with the patient outcome. No relationship could be observed between p110 alpha and pAKT or between pAKT and disease outcome. It is interesting to note that cases with a nuclear pAKT immunoreactivity showed a trend of improved overall survival. Our results underline the prognostic significance of PIK3CA in ovarian carcinoma and argue against a simple linear model of PIK3CA gain/amplification followed by PI3K activation and consecutive AKT phosphorylation in ovarian carcinoma.

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Abstract. Expression of the imprinted genes insulin-like growth factor 2 (IGF2) and H19 depends on the methylation pattern of their common imprinting control region (ICR) located on chromosome 11p15. As the somatic imprinting pattern may be lost during tumorigenesis due to epigenetic alterations, in the present study, we analyzed the DNA methylation and histone modifications in the differentially methylated region (DMR) of IGF2/H19 in benign prostate hyperplasia (BPH) and prostate carcinoma (PCa). Sodium bisulfite sequencing was performed on frozen tissue collected after radical prostatectomy. Thirty tumors and 17 noncancerous tissue samples were analyzed. Histological diagnosis was, in addition, confirmed by amplification of the epithelial tumor marker ·-methylacyl coenzyme-A racemase. Chromatin immunoprecipitation assay (ChIP) was carried out on sonificated chromatin from fresh tissue samples from 10 PCa, 10 BPH using antibodies against trimethyl histone H3K9, dimethyl histone H3K9, trimethyl H3K27 and acetyl H3K9. The methylation pattern of 17 CpGs within 227 bp of the H19 fragment was characterized from each DNA sample. All (BPH) samples demonstrated >80% methylation of CpGs. In contrast, we found 41% of CpGs methylated in 9 out of 30 PCa specimens. We observed statistically significant differences in the methylation state between PCa and BPH groups, especially in the DMR of H19 (p<0.0001) and in the ICR (p=0.0034), which corresponds to CTCF binding domain. ChIP assay revealed that dimethyl H3K9 is associated with the ICR of IGF2/H19 in BPH, but not in PCa (p<0.0001). Our data demonstrate that DNA methylation and histone methylation analysis of the ICR within the DMR of IGF2/H19 provides important insights into early steps of carcinogenesis and, therefore, may contribute to improving diagnosis of PCa.

Our data suggest that 14-3-3 beta expression is essential for normal spermatogenesis by interacting with vimentin in Sertoli cells. Additionally, 14-3-3 beta expression in malignant transformed cells in IGCN and classical seminoma may lead to tumourigenesis and cell survival.