Figure 2.
Tumorigenicity of NXS2 cells after scIL-12 transduction. Syngeneic A/J mice (n = 6) were injected intravenously with 1 × 105 NXS2 cells from the low, intermediate, or high scIL-12 secreting clones and analyzed for liver (A) or bone marrow metastasis (B) 26 days after inoculation or kept for survival studies (C). (A) Tumor foci to the liver were counted after injection of low (•), intermediate (▴), and high (⧫) scIL-12-producing clones of NXS2 and compared with NXS2 cells carrying the empty vector (▪). Horizontal lines represent the mean value per experimental group. (B) Bone marrow metastases were analyzed by tyrosine hydroxylase RT-PCR and staged, as described in Materials and Methods after intravenous injection of low (•), intermediate (▴), and high (⧫) scIL-12-producing clones of NXS2 and compared with NXS2 cells carrying the empty vector (▪). The horizontal lines represent the mean value per experimental group. (C) The survival of mice was studied after intravenous injection of low (— · —), intermediate (⋯ ·), and high (———) scIL-12-producing clones of NXS2 and compared with that of mice injected with NXS2 cells carrying the empty vector (· — · —). Differences between all experimental groups and the control group were statistically significant (P < 0.005).