OBJECTIVETo observe the growth and metastasis effect of interferon alpha-1b (IFN-alpha-1b) on nasopharyngeal carcinoma cell line CNE-2 in xenografted model of mice liver. Comparing rAAV-mediated IFN-alpha-1b gene therapy with the IFN-alpha-1b protein therapy.

METHODSThe xenografted model of liver nasopharyngeal carcinoma was established by injecting the human nasopharyngeal carcinoma cell line CNE-2 under liver capsule of nude mice. Forty nude mice were randomly divided into four groups by means of random number table method, with ten mice in each one. (Group A: rAAV-IFN-alpha-1b, Group B: IFN-alpha-1b; Group C: rAAV-EGFP; Group D: PBS). After 24 hours, A, C and D group was injected with rAAV-IFN-alpha-1b encoding human IFN-alpha-1b, rAAV-EGFP and phosphate buffer saline via tail vein injection. After 5 days, mice in group B was injected with human IFN-alpha-1b protein once per two days. Three weeks later five nude mice were sacrificed and then observed their liver tumor formation and pulmonary metastasis. Tumor size was measured and tumor inhibition ratios was calculated, and apoptotic index (AI) was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL). The contents of human IFN-alpha contained in peripheral blood and mice IL-12 was determined by high performance liquid chromatography chip techniques. And another five mice were randomly chosen for the observation of surviving study.

RESULTSAfter human nasopharyngeal carcinoma implants in nude mice liver 3 weeks, the average volume of A group (0.114 +/- 0.116) cm3 and B group (0.422 +/- 0.137) cm3 were significantly lower than that of C group (2.476 +/- 0.637) cm3 and D group (2.677 +/- 0.704) cm3 (F = 38.536, P < 0.01). Compared with D group, the restrained percentage of tumor in group A was 95.74% and group B was 84.24%. The percentage of lung metastases in group A, B, C and D were 0.0%, 0.0%, 40.0%, 60.0% respectively. The apoptotic index increased significantly in group A (21. 88 +/- 3.29)% and group B (19.85 +/- 1.96)% versus group C (4.37 +/- 0.50)% and group D (3.40 +/- 1.05)% (F = 120.964, P < 0.01). The average content of human interferon-alpha in serum increased significantly in group A (101.50 +/- 11.33) pg/ml and group B (91.55 +/- 9.80) pg/ml versus group C (23.06 +/- 4.36) pg/ml and group D (16.93 +/- 9.96) pg/ml (F = 69.128, P < 0.01). The average content of IL-12 increased significantly in group A (80.36 +/- 13.35) pg/ml and group B (51.15 +/- 9.72) pg/ml versus group C (19.44 +/- 7.03) pg/ml and group D (14.49 +/- 4.21) pg/ml (F = 57.116, P < 0.01). The survival time of tumor bearing mice in group A (55.80 +/- 2.77) d and group B (48.20 +/- 2.39) d was significantly longer than group C (35.40 +/- 2.61) d and group D (36.80 +/- 1.92) d (chi2 = 25.623, P < 0.01).

CONCLUSIONSIFN-alpha-1b can inhibit the growth and metastasis of nasopharyngeal carcinoma cell line CNE-2 in xenografted model of mice liver. rAAV-mediated IFN-alpha-1b gene therapy indicated more effect than the IFN-alpha-1b protein therapy by comparing content of human IFN-alpha in serum and the survival time of tumor bearing mice.