Cloning of an isoform of integrin-linked kinase (ILK) that is upregulated in HT-144 melanoma cells following TGF-β1 stimulation

• Published in: Oncogene Vol. 19; no. 27; pp. 3069 - 3077
• Main Authors: JANJI, B, MELCHIOR, C, VALLAR, L, KIEFFER, N
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 22.06.2000; Nature Publishing Group
• Subjects: Biological and medical sciences; Cell growth; Cell physiology; Cell proliferation; Cellular signal transduction; Complementary DNA; Development and progression; Fibrosarcoma; Fundamental and applied biological sciences. Psychology; Gene expression; Genetic aspects; Health aspects; ILK protein; Insulin; Kinases; Melanoma; Metastases; Metastasis; Molecular and cellular biology; Myelin; Myelin basic protein; Nucleotide sequence; Physiological aspects; Platelet-derived growth factor; Polymerase chain reaction; Protein kinases; Proteins; RNA-directed DNA polymerase; Signal transduction; Transfection; Transforming growth factor-b1; Transforming growth factors; Tumor cell lines; Tumors; Luxembourg; Human; Cell proliferation; Molecular form; Phosphorylation; Nucleotide sequence; Enzyme; Transferases; Melanoma; Homology; Gene expression; Signal transduction; Regulation(control); Integrin; Cell line; Complementary DNA; Protein kinase; Transforming growth factor β1
• DOI: 10.1038/sj.onc.1203640
• ISSN: 0950-9232

We have shown previously that integrin-linked kinase (ILK) is upregulated in human HT-144 melanoma cells following TGF-β1 stimulation. Using mRNA from TGF-β1 stimulated HT-144 cells and reverse transcriptase polymerase chain reaction, we have isolated a cDNA encoding a protein highly homologous to ILK. Sequencing of the full-length 1359 base pair cDNA and polypeptide translation revealed that this protein, designated ILK-2, differs from the known ILK (hereafter called ILK-1) by only four amino acids, while the cDNA sequence diverges by 102 nucleotides, thus excluding that ILK-2 is an allelic variant of ILK-1. Expression of ILK-2 mRNA was observed in metastatic human HT-144 melanoma and HT-1080 fibrosarcoma cell lines, but not in normal human tissues. Moreover, stimulation of HT-144 cells with TGF-β1, but not with EGF, PDGF-AB or insulin, induced a selective overexpression of ILK-2 mRNA as compared to ILK-1 mRNA. Bacterially-expressed GST/ILK-2 autophosphorylated and labeled myelin basic protein as well as a recombinant GST/β3 integrin cytoplasmic tail peptide. Transfection of either ILK-2 or ILK-1 cDNA into the non-metastatic melanoma cell line SK-Mel-2, expressing exclusively ILK-1, induced anchorage independent cell growth and cell proliferation, as demonstrated by growth in soft agar. Our data provide evidence that ILK-2 is a new isoform of ILK-1 that is expressed in some highly invasive tumor cell lines but not in normal adult human tissues and whose expression is regulated by TGF-β1.