C4.4A is associated with tumor budding and epithelial–mesenchymal transition of colorectal cancer

Abstract

C4.4 A is a glycolipid‐anchored membrane protein expressed in several human malignancies. The aim of this study was to explore the association between C4.4 A expression at the invasion front of colorectal cancer ( CRC) and tumor budding, a putative hallmark of cell invasion of CRC. Advanced CRCs ( T2–4, n = 126) had a budding count of 3.66 ± 5.66, which was significantly higher than that of T1 early CRCs (1.75 ± 2.78, n = 87). C4.4 A‐positive CRC specimens showed a larger budding cell number than C4.4 A‐negative CRC specimens in T1 CRCs, and especially advanced CRCs (9.45 ± 5.83 vs 1.60 ± 3.93). Furthermore, we found a correlation between the percentage of C4.4 A‐positive cases and budding count in advanced CRC. Multivariate analysis for patients' survival showed that C4.4 A was superior to tumor budding as a prognostic factor. With si RNA treatment, C4.4 A levels were associated with cell invasion, but not with proliferation, in HCT116 and DLD1 cell lines. An immunohistochemical study in a subset of CRCs showed no relationship between C4.4 A and Ki‐67 proliferation marker. In vitro assays using HCT116 indicated that C4.4 A levels correlated well with epithelial–mesenchymal transition ( EMT) with regard to cell morphology and alterations of EMT markers including E‐cadherin, vimentin, and partially N‐cadherin. We also found that C4.4 A expression was significantly associated with loss of E‐cadherin and gain of β‐catenin in clinical CRC tissue samples. These findings suggest that a tight association between C4.4 A and tumor budding may, in part, be due to C4.4 A promoting EMT at the invasive front of CRC. ( Cancer Sci 2012; 103: 1155–1164)