Fig. 6.
Bcl-XL overexpression does not delay tumor clearance in vivo. U87 cells transfected with a plasmid expressing Bcl-XL (U87 ZsG XL) or luciferase (U87 ZsG Lux) were injected subcutaneously into the hind flanks of female nude (nu/nu) mice. Palpable tumors were allowed to develop for 7 days, and mice were then inoculated intravenously with either M51R VSV or PBS. Mice were inoculated again 3 days later. (A)Tumors from the PBS treatment group were harvested 7 days after the initial inoculation, by which time the tumors had reached the predetermined maximum size limit. The levels of expression of Bcl-XL were determined by immunoblotting. Shown are data comparing the original cell lines with two tumors derived from each. (B)Tumor size was determined daily. Arrows indicate days of inoculation. All PBS-treated animals developed tumors that grew to the upper size limit and were subsequently sacrificed. Treatment with M51R VSV reduced both luciferase- and Bcl-XL-expressing tumors to undetectable levels. There was no significant difference between luciferase- and Bcl-XL-expressing tumors in either the M51R VSV or PBS treatment groups as determined by repeated-measures analysis of variance. The differences between the M51R VSV and PBS treatment groups were statistically significant (P < 0.05) beginning on day 4 for luciferase-expressing tumors and on day 5 for Bcl-XL-expressing tumors. Error bars indicate standard errors of the means.