Down-Regulation of the Human PRL-3 Gene Is Associated with the Metastasis of Primary Non-Small Cell Lung Cancer

Shin-ichi Yamashita, MD,1,2 Yoshiko Masuda, MD,1 Katsutaka Matsumoto, MD,1 Yasuhiro Okumura, MD,1 Hosei Matsuzaki, MD,1 Takashi Kurizaki, MD,1 Yoshio Haga, MD,1 Shigeru Katafuchi, MD,1 Toshihiko Murayama, MD,3 Satoshi Ikei, MD,1 and Katsunobu Kawahara, MD2

Background: Phosphatase of the regenerating liver (PRL)-3 protein tyrosine phosphatase gene is expressed in colon cancer metastasis. To investigate the role of this gene in metastatic lung cancer, we compared PRL-3 gene expression between primary cancers, metastatic lung cancer, and normal lung tissue.
Materials and Methods: Five metastatic tumor and normal samples from non-small cell lung cancer patients were obtained at the National Hospital Organization Kumamoto Medical Center (Kumamoto, Japan). For a quantitative evaluation of RNA expression by PCR, we used Taqman PCR methods.
Results: Although PRL-3 gene expression levels in the primary lesions were slightly decreased compared with those in the normal tissues, those in the metastatic lesions were extremely down-regulated in the synchronous metastatic case. In 2 of these 3 cases, the metastatic tumors showed down-regulated PRL-3 gene expression at 10 times less than that of the normal tissue, and the other tumor showed a slightly weaker expression.
Conclusion: These data suggest that a down-regulation of the PRL-3 gene is important in lung cancer metastasis and provide a new hypothesis of lung cancer metastases. (Ann Thorac Cardiovasc Surg 2007; 13: 236-239)

Key words: phosphatase of the regenerating liver, metastasis, lung cancer

Departments of 1Surgery and 3Pathology, National Hospital Organization Kumamoto Medical Center, Kumamoto, and 2Department of Surgery II, Faculty of Medicine, Oita University, Yufu, Japan

Received August 28, 2006; accepted for publication November 6, 2006
Address reprint requests to Shin-ichi Yamashita, MD: Department of Surgery II, Faculty of Medicine, Oita University, 1–1 Idaigaoka, Yufu, Oita 879–5593, Japan.