URGCP/URG4 is essential for HCC cell proliferation.

<p>Representative micrographs (left panel) and quantification (right panel) of crystal violet-stained cells (A). Silencing endogenous URGCP/URG4 inhibited cell growth, as determined by MTT assay (B). Silencing endogenous URGCP inhibited cell growth, as determined by anchorage-independent growth assay (C). Soft agar colony formation by indicated cells after 10 days of culture (left panel); colonies larger than 0.1 mm in diameter (middle panel) or those contained more than 50 cells/colony (right panel) were scored. Each bar represents the mean ± SD of three independent experiments. Xenograft model in NOD/SCID mice (D). QGY-7703/vector cells and QGY-7703/URGCP/URG4 RNAi#1 cells were injected into the groin of athymic mice and excised at experimental endpoint (upper panel). Tumor volumes were measured on the indicated days. Representative graph of tumor growth and mean tumor weights 5 weeks after inoculation are shown (lower panel). All data are shown as mean ± SD. IHC staining of URGCP/URG4 and Ki-67 in mouse HCC specimens (E). IHC analyses were performed for two independent times on each of the samples (upper panel); a significant correlation between URGCP/URG4 and Ki-67 levels was observed (<i>r</i> = 0.734; <i>P</i><0.005; lower panel).