Figure 6. Systemic GSI-I decreases growth of NB xenografts and is associated with mitotic catastrophe, decreased proliferation and reduced tumor angiogenesis A.
Treatment schedule of orthotopically transplanted U-NB1 tumors. 2 × 105 U-NB1 cells expressing luciferase were transplanted into the left adrenal gland of immunodeficient mice. Growth of tumors was monitored by luminescence imaging starting 4 days post transplantation. Treatment was started when tumors were detected in two consecutive measurements. Mice in control and treatment groups (n=8 for each group) were paired for similar tumor size and treated with 5 mg/kg GSI-I or vehicle only by daily i.p. injections for 14 days. B. GSI-I reduces growth of orthotopic U-NB1 xenotransplants. Shown is the course of one representative pair of tumors. For imaging, mice were injected with luciferin. C. Prolonged survival of NB-bearing mice treated with GSI-I. Shown is a Kaplan-Meier survival analysis. Mice were killed when they became moribund. Statistical analysis was performed by log rank test. D. GSI-I-treated NB show signs of mitotic catastrophe, decreased proliferation and reduced vascularisation compared to vehicle control. Mice received GSI-I (n=5) or vehicle only (n=4) 5 days a week by i.p. injections for 4 weeks. At different time points, one mouse per group was sacrificed. Tumor tissue sections were stained by HE, for Ki67, for CD31 and for cleaved caspase 3 (CC3). Shown are the results for 12 and 31 days after therapy (i.e. 44 and 63 days after tumor cell transplantation). Bars equal 100 μm and 50 μm (inserts). Statistical analysis was performed by unpaired one-sided t-test; *p<0.05, **p<0.01, ***p<0.001. Arrows point to giant multinucleated tumor cells.