Tiam1, overexpressed in most malignancies, is a novel tumor biomarker

T lymphoma invasion and metastasis 1 (Tiam 1) is a guanine nucleotide exchange factor (GNEF) family member, and is considered to be involved in many important cellular processes and oncogenesis. In this study, we investigated Tiam I expression differences between normal tissue and malignant tissue using tissue microarray (TMA), and further studied the Tiam1 mRNA and protein level in 9 hepatoma lines. Forty-nine tumor tissue and 47 normal tissue samples were detected via TMA by immunohistochemistry with polyclonal antibody. Tiam I expression in 9 human hepatoma cell lines, namely Huh-7, HepG2, Hep3B, SMMC-7721, QGy-7701, QGy-7703, BEL-7402, BEL-7404 and BEL-7405, and 1 normal primary human hepatocyte, HL-7702, was compared by means of fluorescence quantitative PCR, immunocytochemistry assay and Western blotting. We found that Tiam I was significantly expressed in various malignancies. Tiam I m RNA and protein levels were significantly elevated in the 9 human hepatoma cell lines compared to the normal primary human hepatocyte. Our results suggest that Tiam1 overexpression in malignant neoplasms could be a novel effective supplementary biomarker for tumors, including hepatocellular carcinoma.