The leukocyte protein L‐plastin induces proliferation, invasion and loss of E‐cadherin expression in colon cancer cells

Abstract

L-plastin, a gene that codes for an actin-bundling protein, is upregulated in the metastatic colon cancer cell line SW620, when compared to its premetastatic counterpart SW480. The aim of our study was to characterise the effect of L-plastin overexpression on SW480 cells in the context of the acquisition of a metastatic phenotype. SW480 cell lines overexpressing L-plastin were established (SW480-LPL). Analysis of these cell lines revealed significantly higher rates of proliferation and invasion than the control cell line (SW480-Ctrl). In addition, the expression of E-cadherin was lost from SW480-LPL cells. Treatment of SW480-LPL cells with cytochalasin B, an inhibitor of endocytosis, attenuated the loss of Ecadherin expression in these cells. The association of L-plastin overexpression with an increased rate of proliferation and invasion, and loss of E-cadherin expression in the SW480 colon cancer cell line indicates that L-plastin plays an important mechanistic role in colorectal cancer metastasis (supplementary material for this article can be found on the International Journal of Cancer website at http://www.interscience.wiley.com/jpages/0020-7136/ suppmat/index.html). ' 2005 Wiley-Liss, Inc.Key words: colon cancer; metastasis; L-plastin; E-cadherin Colorectal cancer (CRC) is a leading cause of morbidity and mortality and accounted for 203,700 deaths in Europe in 2004. 1 A genetic model for colorectal tumourigenesis has previously been described, but the molecular mechanisms of metastasis are not well elucidated. Decrease in cell-cell adhesion, loss of contact inhibition, increase in proliferation and dedifferentiation are all observed in the progression of tumours to the invasive phenotype. In recent years, research into metastasis has focussed increasingly on the actin cytoskeleton and actin-associated proteins.L-plastin is an actin-bundling protein usually expressed only in cells of haemopoietic origin. However, the L-plastin gene is frequently activated in human cancers. Sixty-eight percent of carcinomas and 53 percent of other nonhaemopoietic cancers exhibit constitutive activation of the L-plastin gene, and L-plastin synthesis has been detected in a primary culture of ovarian carcinomas. 2,3 L-plastin is phosphorylated on Serine 5 in response to the activation of the integrin a(M) b(2) on polymorphonuclear neutrophils. 4 Additionally, the yeast homologue of L-plastin, Sac6, is involved in yeast fluid phase endocytosis, and L-plastin restores normal function in yeast with a null mutation for Sac6. 5 The colon carcinoma cell lines SW480 and SW620 represent a good model for the study of CRC progression in that they are derived from a single patient. SW480 was established from a primary colon adenocarcinoma and SW620 was established, 1 year later, from a lymph node metastasis. 6 More recently, the cell lines have been validated as showing appropriate phenotypic differences following long-term culture in vitro. 7 As such, these cell lines represent an interesting model for studying molecular events in the la...

Discovery and validation of colonic tumor-associated proteins via metabolic labeling and stable isotopic dilution

“…An associated drop in ␣-actinin also has been noted in tumors (35). The protein L-plastin also is associated with focal adhesions, and its elevation induces proliferation, tissue invasion, and loss of E-cadherin in colorectal tumors (36). In addition, because coronin inactivates the actin-related protein 2/3 complex, its increase promotes cell motility (37).…”

Nuclear lamins: key regulators of nuclear structure and activities

“…[198]. Lamins associated changes in pRb-dependent heterochromatin organization contribute to the permanent silencing of genes that promote proliferation, and might therefore be important for limiting the development of malignant tumours [182] [186,199] [200] can be explained on the basis of a rearranged p53 gene, as has been found in osteosarcoma cells [201]. Mutations in SMAD4 occur in 50% of human pancreatic cancers.…”

Actin-bundling proteins in cancer progression at a glance

“…L-plastin (Table 1, also known as L-fimbrin) is normally only present in haematopoietic cells; however, one study showed that it is expressed in more than half of epithelial carcinomas and non-epithelial mesenchymal tumours (Delanote et al, 2005). L-plastin expression further correlates with stage and severity of colorectal cancers and is considered a potential prognostic indicator (Foran et al, 2006;Yuan et al, 2010). Villin mediates bundling, nucleation (initiation of new filaments), capping and severing of actin filaments in a Ca 2+ -dependent manner (Friederich et al, 1990), and is highly expressed in adenocarcinomas originating from epithelial cells of the intestinal tract that bear brush border microvilli (Grone et al, 1986;Moll et al, 1987;Suh et al, 2005).…”