OBJECTIVETo investigate the inhibitory effects of a novel histone deacetylases inhibitor FK228 on human colon cancer HCT-116 cells in vitro and in vivo, and evaluate its toxicity and side effects.

METHODSThe in vitro growth inhibitions of HCT-116 cells by different concentrations of FK228 and 5-Fu for 24, 48 and 72 h were assessed by CCK-8 assay. BALB/c nude mouse models of tumor xenografts were prepared by subcutaneous implantation of tumor tissue, and 4 mg/kg FK228 and 50 mg/kg 5-Fu were i.p. injected, respectively. The inhibitory effects on tumor growth, hematology, and liver and kidney function were evaluated.

RESULTSCCK-8 assay indicated that FK228 had an obvious growth inhibitory effect on HCT-116 cells in a dose- and time-dependent manner. The IC50 of FK228 in HCT-116 cells was 12.05 ng/ml for 48 h, while the IC50 of 5-Fu was 18.92 µg/ml. At 20 days after FK228 and 5-Fu treatment, the tumor volume of the FK228 group was (139.71 ± 44.54)mm(3), significantly lower than that of the 5-Fu group [(282.28 ± 58.81)mm(3)] and that of the model group [(520.65 ± 39.73)mm(3), P < 0.01 for both]. The average tumor weight was (0.07 ± 0.02)g in the FK228 group, significantly lower than that of the 5-Fu group [(0.20 ± 0.08)g, P < 0.01]. The tumor growth inhibition rate of the FK228 group was 73.2%, significantly higher than that of the 5-Fu group (45.8%, P < 0.01). The ALT levels of the FK228 and 5-Fu groups were significantly higher than that of the model group (P < 0.01). The BUN of 5-Fu group was significantly higher than that of the model group (P < 0.01), but the BUN of FK228 group was not significantly different from that of the blank and control groups (P > 0.05 for both). Routine blood test showed that WBC, RBC, Hb and PLT of the 5-Fu group were significantly lower than those of the model group (P < 0.05 for all), but only WBC of the FK228 group was significantly lower than that of the model group (P < 0.05). The pathological examination using HE staining revealed that in the FK228 group, there were fibrosis and inflammatory cell infiltration in the liver tissue, and mild edema of the renal tubules in the kidney. However, in the 5-Fu group there were extensive hepatocyte edema and necrosis in the liver, and evident deformation and necrosis of glomeruli and tubules, and tubular wall thinning in the kidney.

CONCLUSIONSThe results of this study indicate that FK228 can more effectively than 5-Fu inhibit the growth of HCT-116 cells in vitro and vivo, and without obvious toxic effect on the kidney and hematology. Its clinical value in colon cancer treatment deserves further investigation.