Overexpression of bone morphogenetic protein 4 enhances the invasiveness of Smad4-deficient human colorectal cancer cells

• Published in: Cancer letters Vol. 281; no. 2; pp. 220 - 231
• Main Authors: Deng, Haiyun, Ravikumar, T.S, Yang, Weng-Lang
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 28-08-2009; Elsevier Limited
• Subjects: Adenocarcinoma; Blotting, Western; BMP-4; Bone cancer; Bone morphogenetic protein 4; Bone Morphogenetic Protein 4 - biosynthesis; Bone Morphogenetic Protein 4 - genetics; Cell adhesion; Cell Adhesion - physiology; Cell growth; Cell Line, Tumor; Cell migration; Cell Movement - physiology; Collagen; Colorectal cancer; Colorectal carcinoma; Colorectal Neoplasms - genetics; Colorectal Neoplasms - metabolism; Colorectal Neoplasms - pathology; Cytology; Fibronectin; Fluorescent Antibody Technique; Gene Expression; Gene Expression Regulation, Neoplastic; Growth rate; Hematology, Oncology and Palliative Medicine; Humans; Invasive phenotype; Invasiveness; Kinases; Mesenchyme; Metastases; Neoplasm Invasiveness - genetics; Oligonucleotide Array Sequence Analysis; Phenotypes; Reverse Transcriptase Polymerase Chain Reaction; RNA, Small Interfering; Rodents; Signal transduction; siRNA; Smad4; Smad4 protein; Smad4 Protein - deficiency; Vimentin; Vimentin - biosynthesis; BMP-4; Smad4; Gene expression; Invasive phenotype; Colorectal cancer
• ISSN: 0304-3835; 1872-7980
• DOI: 10.1016/j.canlet.2009.02.046

Abstract Bone morphogenetic proteins (BMP), a member of the TGF-β superfamily, have broad activities in regulating various kinds of cellular behaviors. Previously, we have demonstrated that BMP-4 is up-regulated in human colonic adenocarcinoma and promotes the invasive phenotypes of human colorectal cancer HCT116 cells. Smad4 is a central mediator in BMP signaling pathway and it is frequently mutated in metastatic colorectal cancers. To address whether Smad4 was required for enhancing metastatic potentials by BMP-4 in colorectal cancer, we generated BMP-4 overexpressing clones from Smad4-deficient SW480 cells. The growth rate of BMP-4 overexpressing cells was slightly higher than that of empty-vector controls. Overexpression of BMP-4 resulted in an increased expression of vimentin, a marker of epithelial–mesenchymal transition, and caused the changes of cell morphology, spreading and formation of focal adhesions. BMP-4 overexpressing cells increased cell adhesion on fibronectin and collagen, and augmented cell migration and invasion potentials in comparison to empty-vector controls. The induction of cell migration by BMP-4 overexpression was inhibited by BMP-4 siRNA. To further identify the target genes of the elevated BMP-4 signaling in SW480 cells, an oligonucleotide microarray was performed. Among 46,000 genes, 91 genes (65 up-regulated and 26 down-regulated) with 2-fold difference have been identified between BMP-4 overexpressing and empty-vector cells. This study demonstrates that Smad4 is dispensable for enhanced invasiveness of human colorectal cancer cells due to BMP-4 overexpression.