3927

LASP1

PURPOSE: The expression of LIM and SH3 protein 1 (LASP1) was upregulated in colorectal cancer cases, thereby contributing to the aggressive phenotypes of colorectal cancer cells. However, we still cannot decipher the underlying molecular mechanism associated with colorectal cancer metastasis. EXPERIMENTAL DESIGN: In this study, IHC was performed to investigate the expression of proteins in human colorectal cancer tissues. Western blot analysis was used to assess the LASP1-induced signal pathway. Two-dimensional difference gel electrophoresis was performed to screen LASP1-modulated proteins and uncover the molecular mechanism of LASP1. TGFbeta was used to induce an epithelial-mesenchymal transition (EMT). RESULTS: LASP1 expression was correlated with the mesenchymal marker vimentin and was inversely correlated with epithelial markers, namely, E-cadherin and beta-catenin, in clinical colorectal cancer samples. The gain- and loss-of-function assay showed that LASP1 induces EMT-like phenotypes in vitro and in vivo. S100A4, identified as a LASP1-modulated protein, was upregulated by LASP1. Moreover, it is frequently coexpressed with LASP1 in colorectal cancer. S100A4 was required for EMT, and an increased cell invasiveness of colorectal cancer cell is induced by LASP1. Furthermore, the stimulation of TGFbeta resulted in an activated Smad pathway that increased the expression of LASP1 and S100A4. The depletion of LASP1 or S100A4 expression inhibited the TGFbeta signaling pathway. Moreover, it significantly weakened the proinvasive effects of TGFbeta on colorectal cancer cells. CONCLUSION: These findings elucidate the central role of LASP1 in the TGFbeta-mediated EMT process and suggest a potential target for the clinical intervention in patients with advanced colorectal cancer.CI - (c)2014 American Association for cancer Research.

LIM and SH3 protein 1(LASP1) can promote colorectal cancer (CRC) progression and metastasis, but the mechanism remains unclear. Here, we show that LASP1 interacts with S100 calcium binding protein A11(S100A11) and enhances its expression in CRC. LASP1-S100A11 axis is essential for TGFbeta-mediated epithelial-mesenchymal transition (EMT) and cell aggressive phenotype. Clinically, S100A11 is overexpressed in CRC tissues and localized in both the cytoplasm and the nucleus of CRC cells. Overexpression of S100A11 in cytoplasmic and nuclear subcellular compartments is associated with tumor metastasis and poor prognosis of CRC patients. Introduction of cytoplasmic and nuclear S100A11 promotes aggressive phenotypes of CRC cells in vitro as well as growth and metastasis of CRC xenografts, whereas suppressing S100A11 abrogates these effects. Furthermore, we identify flotillin-1 (FLOT1) and histone H1 as downstream factors for cytoplasmic and nuclear pathway of S100A11, which are required for LASP1-S100A11 axis-mediated EMT and CRC progression. These findings indicate S100A11, combined with LASP1, plays a critical role in promoting CRC metastasis via its subcellular effectors, FLOT1 and histone H1.