Figure 3.

TNFα-expanded MRD cells acquire the recurrence-competent phenotype. A, A total of 5 × 10⁴ B16 cells or MRD B16 cells (expanded from a site of tumor injection for 72 hours in TNFα) were plated in triplicate. Twenty-four hours later, cDNA was analyzed by qRT-PCR for expression of YB-1 or TOPO-IIα. Relative quantities of mRNA were determined. *, P < 0.05; mean of the triplicate is shown. Representative of two separate experiments with two different B16 MRD recurrences. B–E, Skin explant from theB16tk cell injection site from mice treated with ganciclovir was plated with TNFα (B; 100 ng/mL), TNFα plus doxorubicin (C; 0.1 mg/mL), or cocultured with VEGF and 10⁵ splenocytes and lymph node cells from C57BL/6 mice cleared of B16tk tumors after ganciclovir treatment without (D) or with doxorubicin (E). Seven days later, wells were inspected for actively growing tumor cells. Representative of three B16 MRD explants. F, A total of 10³ B16 cells or MRD B16 cells (expanded from a site of tumor injection for 72 hours in TNFα) were plated in triplicate. Cells were infected with reovirus (MOI 1.0) in the presence or absence of IFNα (100 U) for 48 hours and titers of reovirus determined. Mean and SD of triplicates are shown, **, P < 0.001 (ANOVA).