Identification of a novel cell cycle regulated gene, HURP, overexpressed in human hepatocellular carcinoma

Abstract

An analytic strategy was followed to identify putative regulatory genes during the development of human hepatocellular carcinoma (HCC). This strategy employed a bioinformatics analysis that used a database search to identify genes, which are differentially expressed in human HCC and are also under cell cycle regulation. A novel cell cycle regulated gene (HURP) that is overexpressed in HCC was identified. Full-length cDNAs encoding the human and mouse HURP genes were isolated. They share 72 and 61% identity at the nucleotide level and aminoacid level, respectively. Endogenous levels of HURP mRNA were found to be tightly regulated during cell cycle progression as illustrated by its elevated expression in the G 2 /M phase of synchronized HeLa cells and in regenerating mouse liver after partial hepatectomy. Immunofluorescence studies revealed that hepatoma up-regulated protein (HURP) localizes to the spindle poles during mitosis. Overexpression of HURP in 293T cells resulted in an enhanced cell growth at low serum levels and at polyhema-based, anchorage-independent growth assay. Taken together, these results strongly suggest that HURP is a potential novel cell cycle regulator that may play a role in the carcinogenesis of human cancer cells.

Fbx7 Functions in the SCF Complex Regulating Cdk1-Cyclin B-phosphorylated Hepatoma Up-regulated Protein (HURP) Proteolysis by a Proline-rich Region

“…Cdk1-cyclin B and phosphatase were purchased from New England Biolabs. Anti-HURP polyclonal antibody was raised against whole molecular recombinant HURP protein (19). Anti-Cdk1 monoclonal antibody was purchased from CHEMICON.…”

“…Immunofluorescence studies reveal that HURP localizes to the spindle poles during mitosis. Overexpression of HURP in 293T cells results in an enhanced cell growth at low serum levels and at polyhema-based, anchorage-independent growth conditions (19). Furthermore, elevated gene expression of HURP and its related truncated form KIAA0008 is highly associated with human hepatocellular carcinoma, colon cancer, breast cancer and transitional cell carcinoma (19 -22), suggesting that HURP may have a role in carcinogenesis.…”

“…Hepatoma up-regulated protein (HURP) was initially identified through bioinformatics analysis that was performed to search for potentially important regulatory genes involved in growth control of human hepatocellular carcinoma (19). Empirical characterization in HeLa cells indicates that HURP is a cell cycle-regulated gene with an elevated expression in the G 2 /M phase, followed by a sharp decline in early to middle G 1 phase.…”

Aurora kinase inhibitors reveal mechanisms of HURP in nucleation of centrosomal and kinetochore microtubules

“…The formation of robust spindles relies on the cooperation between two assembly pathways: the kinetochore capture by microtubule spindles originating from centrosomes, and the ras-related nuclear GTP (RanGTP)-mediated microtubule nucleation and organization in the vicinity of chromosomes (8)(9)(10)(11)(12)(13). Human hepatoma upregulated protein (HURP) is an Aurora A substrate up-regulated in hepatomas (14,15). HURP stabilizes kinetochore fibers (Kfibers) and promotes nucleation and crosslinking of microtubules (16)(17)(18)(19).…”

Hurp Deficiency in Mice Leads to Female Infertility Caused by an Implantation Defect

“…First revealed in cancer studies, HURP (hepatoma up-regulated protein) is a cell cycle-associated gene with elevated expression in the G 2 /M phase (1)(2)(3). HURP is a microtubuleassociated protein and an essential component of the Ran-dependent complex involved in bipolar spindle assembly (4 -6).…”