Expression of PH Domain Leucine-rich Repeat Protein Phosphatase, Forkhead Homeobox Type 0 3a and RAD51, and their Relationships with Clinicopathologic Features and Prognosis in Ovarian Serous Adenocarcinoma

Background： Ovarian serous adenocarcinoma can be divided into low- and high-grade tumors, which exhibit substantial differences in pathogenesis, clinicopathology, and prognosis. This study aimed to investigate the difl＇erences in the PH domain leucine-rich repeat protein phosphatase （PHLPP）, tbrkhead llomeobox type O3a （FoxO3a）, and RAD51 protein expressions, and their associations with prognosis in patients with low- and high-grade ovarian serous adenocarcinomas. Methods： The PH LPP, FoxO3a, and RA D51 protein expressions were examined in 94 high- and 26 low-grade ovarian serous adenocarcinomas by immunohistochemistry. The differences in expression and their relationships with pathological features and prognosis were analyzed. Results： In high-grade serous adenocarcinomas, the positive rates of PHLPP and goxO3a were 24.5% and 26.6%, while in low-grade tumors, they were 23.1% and 26.9%, respectively （P 〈 0.05 vs. the control specimens; low- vs. high-grade： P 〉 0.（15）. The positive rates of RAD51 were 70.2% and 65.4% in high- and low-grade serous adenocarcinomas, respectively （P 〈 0.（15 vs. the control specimens; low- vs. high-grade： P 〉 0.05）. Meanwhile, in high-grade tumors, Stage Ⅲ/Ⅳ tumors and lymph node and omental metastases were significantly associated with lower PHLPP and FoxO3a and higher RAD51 expression. The 5-year survival rates of patients with PHLPP- and FoxO3a-positive high-grade tumors （43.5% and 36.0%） were significantly higher than in patients with PHLPP-negative tumors （5.6% and 7.2%, respectively; P 〈 0.05）. Similarly, the 5-year survival rate of RAD5 l-positive patients （3.0%） was significantly lower than in negative patients （42.9%： P〈 0.05）. In low-grade tumors, the PHLPP, FoxO3a, and RAD51 expressions were not significantly correlated with lymph node metastasis, omental metastasis, Federation of Gynecology and Obstetrics stage, or prognosis. Conclusions： Abnormal PHLPP, FoxO3a, and RAD51 protein expressions may be involved in the development of high- and low-grade ovarian serous adenocarcinomas, suggesting conlmon molecular pathways. Decreased PH LPP and FoxO3a and increased RAD51 protein expression may be important molecular markers for poor prognosis, and RAD51 may be an independent prognosis factor, of high-grade, but not low-grade, ovarian serous adenocarcinomas.

RNAi screen to identify protein phosphatases that regulate the NF-kappaB signaling

NF-kappaB plays a critical role in cell survival,apoptosis,and inflammatory responses.Serine/threoninespecific phosphatases(PPs)represent the second major class of enzymes that catalyze the dephosphorylation of proteins.The roles of PPs regulating NF-kappaB activities are poorly understood.Here we describe an RNAi-based screen to identify the PPs that involve in regulating NFkappaB signaling.Thirty-four candidate PPs siRNAs were synthesized and primarily screened by NF-kappaB reporter gene assay in HeLa cells.PHLPP,one of the protein phosphatase type 2C family members(PP2C),was identified as a positive regulator of NF-kappaB signaling.Knock-down of PHLPP dramatically attenuated TNFα-stimulated NF-kappaB transcriptional activation.Knockdown of PHLPP led to enhancement of NF-kappaB/p65 nuclear import and retention,but decreased TNFα-induced phosphorylation at Ser276 on p65.This critical phosphorylation was also drastically reduced by knock-down of PKCalpha and Akt1,two important serine/threonine kinases dephosphorylated by PHLPP.The results together suggest that PHLPP-Akt-PKC may represent an important signaling loop that activates NF-kappaB/p65 signaling through critical serine phosphorylation.