BMC Cancer Research article KIAA0101 (OEACT-1), an expressionally down-regulated and growth-inhibitory gene in human hepatocellular carcinoma Minglei Guo1,2, Jinjun Li2,3, Dafang Wan2,3 and Jianren Gu*1,2,3 BioMed Central Open Access Address: 1Shanghai Medical College, Fudan University, Shanghai, China, 2National Laboratory for Oncogenes and Related Genes, Shanghai Cancer Institute, Shanghai, China and 3Medical School of Shanghai Jiao Tong University, Shanghai, China Email: Minglei Guo - guomingleicn@yahoo.com.cn; Jinjun Li - lijj64@hotmail.com; Dafang Wan - nlorg@sh163.net; Jianren Gu* - nlorg@sh163.net * Corresponding author Published: 29 April 2006 BMC Cancer 2006, 6:109 doi:10.1186/1471-2407-6-109 This article is available from: http://www.biomedcentral.com/1471-2407/6/109 Received: 21 December 2005 Accepted: 29 April 2006 © 2006 Guo et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: Our previous cDNA array results indicated KIAA0101 as one of the differentially expressed genes in human hepatocellular carcinoma (HCC) as compared with non-cancerous liver. However, it is necessary to study its expression at protein level in HCC and its biological function for HCC cell growth. Method: Western blot and tissue array were performed to compare KIAA0101 protein expression level in paired human HCC and non-cancerous liver tissues from the same patients. Investigation of its subcellular localization was done by using dual fluorescence image examination and enriched mitochondrial protein Western blot analysis. The in vitro cell growth curve was used for examing the effect of over-expression of KIAA0101 in HCC cells. FACS was used to analyze the cell cycle pattern in KIAA0101 expression positive (+) and negative (-) cell populations isolated by the pMACSKKII system after KIAA0101 cDNA transfection. Results: Western blot showed KIAA0101 protein expression was down-regulated in HCC tissues as compared with their counterpart non-cancerous liver tissues in 25 out of 30 cases. Tissue array also demonstrated the same pattern in 161 paired samples. KIAA0101 was predominantly localized in mitochondria and partially in nuclei. KIAA0101 cDNA transfection could inhibit the HCC cell growth in vitro. In cell cycle analysis, it could arrest cells at the G1 to S phase transition. Conclusion: KIAA0101 protein expression was down-regulated in HCC. This gene could inhibit the HCC cell growth in vitro and presumably by its blocking effect on cell cycle. Background Hepatocellular carcinoma (HCC) is one of the most prev- alent and lethal cancer in Asia and Africa. The develop- ment of HCC is a multi-factor in etiology, multi-step and multi-gene involvement in carcinogenesis and progres- sion. A broad spectrum of genes have been involved in HCC development related to their genetic or epigenetic alteration, including p53[1], p16, p21[2], p27[3], beta- catenin[4], PTEN[5] and Rb etc. Recent studies on func- tional genomics of HCC have further revealed that a number of genes with novel sequences and unclarified functions were involved in HCC development or progres- sion [6]. Based on cDNA array, we found KIAA0101, now designated as OEACT-1[7], as one of the genes with differ- ential expression in HCC. In recent years, several reports described that alteration of KIAA0101 expression Page 1 of 8 (page number not for citation purposes)