The E2F Transcription Factor 1 Transactives Stathmin 1 in Hepatocellular Carcinoma
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Through data mining the Stanford Microarray Database, the stathmin 1 (STMN1) transcript was found to be frequently upregulated in the hepatocellular carcinoma (HCC) with low alpha-fetoprotein level. The molecular mechanism of STMN1 upregulation in HCCs remained unclear.
Quantitative RT-PCR, immunoblotting, immunohistochemistry, and transfection of expression or small hairpin RNA interference plasmids, chromatin immunoprecipitation (ChIP), and quantitative ChIP assays were performed in HCC specimens or 2 distinct HCC-derived cell lines. Dual luciferase assay and site-directed mutagenesis were applied to analyze the activities of STMN1 proximal promoter region.
STMN1 mRNA and proteins were significantly associated with several clinicopathological features. High STMN1 or E2F1 immunoexpression was predictive of poor overall survival (OS) rate (P < .01). In HCC-derived cell lines, E2F1 was elevated before STMN1 mRNA during the cell cycle. Exogenous expression of E2F1 or both transcription factor DP-1 (TFDP1) and E2F1 genes induced E2F1 and STMN1 mRNA (P < .01). Knockdown of the E2F1 gene suppressed E2F1 and STMN1 mRNA and E2F1 and STMN1 protein levels (P < .05). The promoter activity of STMN1 gene increased with overexpression of both E2F1 and TFDP1 genes (P < .05); however, it decreased when mutations were introduced in the E2F1-binding sites (P < .05).
Upregulation of E2F1 and STMN1 proteins associate with worse outcomes in patients with HCC. E2F1 significantly correlates with STMN1 protein level in HCC lesions and in vitro transactivation assays, suggesting that STMN1 gene is transactivated by the E2F1 protein.
KeywordsE2F1 Gene E2F1 Protein Stanford Microarray Database Normal Peripheral Blood Lymphocyte E2F1 mRNA
The first 2 authors contributed equally. The authors thank Dr. Shu-Chun Teng (College of Medicine, National Taiwan University) for valuable discussions. This work was supported by the National Science Council, Taiwan (98-2311-B-110-001-MY3 to YL Shiue) and Chi-Mei Foundation Medical Center (CMFHR9658 to YH Uen).
- 2.Huang CW, Lin CY, Huang HY, Liu HW, Chen YJ, Shih DF, et al. CKS1B overexpression implicates clinical aggressiveness of hepatocellular carcinomas but not p27Kip1 protein turnover: an independent prognosticator with potential p27Kip1-independent oncogenic attributes? Ann Surg Oncol. 2010;17:907–22.PubMedCrossRefGoogle Scholar
- 16.Yuan RH, Jeng YM, Chen HL, Lai PL, Pan HW, Hsieh FJ, et al. Stathmin overexpression cooperates with p53 mutation and osteopontin overexpression, and is associated with tumour progression, early recurrence, and poor prognosis in hepatocellular carcinoma. J Pathol. 2006;209:549–58.PubMedCrossRefGoogle Scholar
- 35.INVESTIGATORS TCOTLIPC. Prospective validation of the CLIP score: a new prognostic system for patients with cirrhosis and hepatocellular carcinoma. The Cancer of the Liver Italian Program (CLIP) Investigators. Hepatology. 2000;31:840–5.Google Scholar
- 38.Fujita Y, Sakakura C, Shimomura K, Nakanishi M, Yasuoka R, Aragane H, et al. Chromosome arm 20q gains and other genomic alterations in esophageal squamous cell carcinoma, as analyzed by comparative genomic hybridization and fluorescence in situ hybridization. Hepatogastroenterology. 2003;50:1857–63.PubMedGoogle Scholar
- 49.DeGregori J, Johnson DG. Distinct and Overlapping Roles for E2F Family Members in Transcription, Proliferation and Apoptosis. Curr Mol Med. 2006;6:739–48.Google Scholar