Figure 6.

5‐fluorouracil (5FU), cisplatin and etoposide significantly increase NK4 expression in subcutaneous tumors in mice. Subcutaneous tumors were established by injecting 5 × 10⁶ SUIT‐2 cells into back and both flanks of mice on day 0. At 7 days after the injection, six tumors were, respectively, treated with 5FU (10 mg/kg, i.p.), cisplatin (5 mg/kg, i.p.) or etoposide (10 mg/kg, i.p.), and five tumors were left untreated. At 24 h after intraperitoneal administration of chemotherapeutic agents, 5 × 10⁷ pfu of Ad‐NK4 (100 µL) was injected into each tumor. The mice were killed at 48 h after administration of Ad‐NK4, and protein lysates of the tumors were adjusted to 10 mg/mL with lysis buffer. The NK4 concentrations in the tumor extracts were analyzed by enzyme‐linked immunosorbent assay. The tumors treated with 5FU, cisplatin and etoposide express 5.4 ± 1.4‐fold (P = 0.006), 11.8 ± 2.6‐fold (P < 0.001) and 4.9 ± 1.8‐fold (P = 0.017) higher levels of NK4 than the untreated tumors, respectively. Each value represents the mean ± SD of the NK4 expression in the six treated and five untreated tumors, respectively. **P < 0.01. *P < 0.05, compared with control tumors.