Overexpression of FMNL2 is closely related to metastasis of colorectal cancer

Abstract

Formin-like 2 (FMNL2) is a member of diaphanous-related formins which can control the actin-dependent processes such as cell motility and invasion. In this study, we investigated the expression of FMNL2 in colorectal cancer (CRC) and its correlation with CRC metastasis. Paraffin-embedded specimens of CRC (including 75 primary CRC tumors and 45 corresponding metastatic lymph nodes) and normal colorectal mucosa (30 samples) were immunostained with a FMNL2 antibody. Thirty-two paired snap-frozen tumor tissues and adjacent normal colorectal mucosa were subjected to real-time reverse-transcription polymerase chain reaction (RT-PCR). Six CRC cell lines (SW480, SW620, SW480/M5, LoVo, LS174T, and HT29) were assayed for FMNL2 expression by Western blotting and real-time RT-PCR. Their invasive abilities in vitro were determined by Boyden chamber assay. The immunohistochemical analysis showed FMNL2 expression was considerably higher in CRC tumors and corresponding metastatic lymph nodes than in normal colorectal mucosa (P < 0.05, respectively). Elevated FMNL2 expression was significantly correlated with lymphatic metastasis of CRC (P < 0.05). Real-time RT-PCR analysis confirmed the results obtained by immunohistochemistry. At mRNA and protein levels, FMNL2 expression was substantially upregulated in cell lines derived from CRC metastases (SW620, SW480/M5, and LoVo) compared to ones derived from primary CRC (HT29, LS174T, and SW480; P < 0.05). In vitro cell invasive assay demonstrated that the former three cell lines had higher invasive ability than the latter cell lines. FMNL2 may play an important role in the metastasis of CRC and may be a useful marker for metastasis of CRC.