Figure 1.

Both HAUSP up and downregulation stabilize and activate p53 and induce growth suppression in the absence of stress. (A) Both HAUSP up and downregulation by Doxycycline stabilize p53 levels. Immunoblot analysis as indicated. PCNA as loading control. (B) HAUSP upregulation and especially downregulation suppress cell proliferation in vitro compared to parental cells. All cells were induced with Doxycycline for 48 hrs before seeding and kept under Dox. Each data point represents the average cell count of triplicate wells; whiskers indicate standard error. (C) Both HAUSP up and downregulation suppress tumor growth in vivo. Cells were induced for 72 hrs with Doxycycline and then injected subcutaneously into nude mice (10⁶ cells per tumor; 6 paravertebral tumors per mouse). All mice received Doxycycline with their drinking water (2 mg/ml) ad libitum. Tumor size was measured every other day. Data from two independent experiments were pooled (a total of 24 tumors from 4 mice per time point per cell line). Growth curves represent the average tumor volume at the indicated time points. (D) Average weight of non-irradiated front tumors at endpoint day 20 (n = 2 per treatment). Consistently, front tumors in all mice were bigger than tumors located in the mid and lower back, due to uncontrollable extraneous factors in the latter areas. Thus, to exclude extraneous limitations, front tumors were chosen to determine differences in the actual growth properties in response to HAUSP modulation. Bars represent mean +/− standard error. The middle and posterior tumors showed the same trend.