These data demonstrate that different repertoires of downstream signaling proteins, particularly those of the MEK6-p38 MAPK-CK2 pathway and the PI3K pathway, are correlated with phenotypic manifestations of a cell culture model of OSE at progressive stages in the development of ovarian cancer.
The resultant activation of the PI3K pathway in both breast and ovarian cancers contributes to cell-cycle progression, decreased apoptosis, and increased metastatic capabilities.
The gene of phosphatidylinositol 3-kinase catalytic subunit alpha (PIK3CA) has been implicated as an oncogene in ovarian cancer [L. Shayesteh et al., Nat.Genet., 21: 99-102, 1999].
Recently, it has been reported that somatic mutations within the PI3K catalytic subunit, PIK3CA, are common (25-40%) among colorectal, gastric, breast, ovarian cancers, and high-grade brain tumors.
Taken together, these data suggest that PTEN over-expression may represent a novel therapeutic approach for chemoresistant human ovarian cancer and that this may involve a p53-mediated apoptotic cascade independent of the PI3K/Akt pathway.
Sequence mutations and gene amplifications lead to activation of the PIK3CA-AKT2 signaling pathway and have been reported in several types of neoplasms including ovarian cancer.
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.
The demonstration that p53 binds directly to the PIK3CA promoter and inhibits its activity identifies a novel mechanism whereby these two mediators regulate cellular functions, and whereby inactivation of p53 and subsequent upregulation of PIK3CA might contribute to the pathophysiology of ovarian cancer.
We found no evidence of disease association for SNPs in BRAF, KRAS, ERBB2 and PIK3CA when OC was considered as a single disease phenotype; but after stratification by histological subtype, we found borderline evidence of association for SNPs in KRAS and BRAF with mucinous OC and in ERBB2 and PIK3CA with endometrioid OC.
High prevalence of genetic alterations in PI3K/AKT pathway in a Middle Eastern ovarian carcinoma provides genetic evidence supporting the notion that dysregulated PI3K/AKT pathways play an important role in the pathogenesis of ovarian cancers.
In this study, we have investigated the expression profile of 22 genes involved in the PI3K-AKT pathway in 26 high-grade ovarian carcinomas (19 serous and 7 clear cell carcinomas).
To confirm these findings at the protein level, immunohistochemistry (IHC) for PIK3CA product p110α and p-Akt was performed on tissue microarrays from 522 independent serous ovarian cancers.