Overexpression of phosphorylated p27 Kip1 at threonine 187 may predict outcome in aggressive B-cell lymphomas

Analysis of RANK-c interaction partners identifies TRAF3 as a critical regulator of breast cancer aggressiveness

Breast cancer is a highly heterogeneous disease both at the histological and molecular levels. We have previously shown that RANK-c is a regulator of NF-κB signaling and exerts a suppressive effect on aggressive properties of ER negative breast cancer cells, while there is an opposite effect on ER positive cell lines. In order to identify molecular determinants that govern the opposing function of RANK-c in breast cancer cells we employed the two cell lines with the highest degree of phenotypic divergence upon RANK-c-expression (SKBR3 and BT474) and identified proteins that interact with RANK-c by affinity-enrichment mass spectrometry (AE-MS) analysis. Annotating enriched proteins with NF-κB signaling pathway revealed TRAF3 as an interacting partner of RANK-c in SKBR3 cell protein lysates, but not in BT474 breast cancer cells in which RANK-c induces cell aggressiveness. To determine the role of TRAF3 in the phenotype of BT474-RANK-c cells, we reconstructed the TRAF3/RANK-c interaction both in parental BT474 and RANK-c expressing cells and tested for aggressive properties through colony formation, migration and invasion assays. TRAF3 forced expression was able to reverse BT474 phenotypic changes imposed by RANK-c, rendering cells less aggressive. Finally, TRAF3 gene expression data and TRAF3 immunohistochemical (IHC) analysis on breast cancer samples indicated that TRAF3 expression correlates with Overall Survival (OS), Recurrence Free Survival (RFS) and several clinicopathological parameters (histological grade, proliferation index) of breast cancer disease.

Expression of Spy1 protein in human non-Hodgkin's lymphomas is correlated with phosphorylation of p27 Kip1 on Thr187 and cell proliferation

Aberrations in cell cycle control are often observed in tumors and might even be necessary in tumor development. Spy1, a novel cell cycle regulatory protein, can control cell progression and survival through the atypical activation of cyclin-dependent kinases (CDKs). In this progression, the phosphorylation of p27(Kip1) at Thr187 by CDK2 was shown to be a chief role. In this study, we studied 183 human specimens including reactive lymphoid and Non-Hodgkin's Lymphomas (NHLs) tissues. Immunohistochemistry (IHC) analysis suggested that Spy1 and pThr187-p27 were overexpressed in NHLs. The expression of Spy1 was positively related to pThr187-p27 and proliferation marker Ki-67 expression. In a multivariate analysis, high Spy1 and pThr187-p27 expressions were showed to be associated with poor prognosis in NHLs. While in vitro, following release of Jurkat cells from serum starvation, the expression of Spy1 was upregulated, as well as pThr187-p27 and CDK2. And an increased interaction between Spy1 and pThr187-p27 was demonstrated at 4 h after serum stimulation. Additionally, transfecting cells with Spy1-siRNA could diminish the expression of pThr187-p27 and arrest cell growth. Our results suggest that Spy1 may be a possible prognostic indicator in NHLs, and it was correlated with phosphorylation of p27(Kip1) on Thr187. These findings provide a rational framework for further development of Spy1 inhibitors as a novel class of anti-tumor agents.