Fig. 1

Methylation levels increased 24 h after cisplatin administration in A549 cells or in tumor-bearing nude mice. a MTT assay showed that A549 cells were sensitive to 5 mg/ml cisplatin. Error bars mean ± SD (n = 3). b The peak methylation level of APC in A549 cells was at 24 h after cisplatin treatment. c The peak methylation level of RASSF1A in A549 cells was at 24 h after cisplatin treatment. Methylation rates of d APC and e RASSF1A were highest at 24 h after cisplatin injection in tumor-bearing nude mice injected with NS and cisplatin (group 1). f Pathological biopsy of tumor tissues for tumor-bearing nude mice injected with NS (group 2). Most tumor cells in the tissues were alive at 72 h after injection (×200). g Biopsy of tumor tissues for mice of group 1. Tumor cells in the tissues had nearly all died at 72 h after injection (×200)