Effect of high-fat diet on 1,2-dimethylhydrazine-induced colon tumors / 中华临床营养杂志

ABSTRACT

Objective To explore the effect of fat on 1,2-dimethylhydrazine (DMH)-induced colon tumors.Methods A total of 50 7-week-old male Wistar rats were further divided into four groupsstandard diet feed control group (n =10),standard diet feed plus DMH-induced tumor group (SDT,n =15),high-fat diet feed control group (n =10) and high-fat diet feed plus DMH-induced tumor group (HFDT,n =15).Rats were killed 18 weeks later,and enzyme-linked immunosorbent assay was used to detect serum triglyeeride,tumor necrosis factor (TNF-α),and colonic TNF-α,interleukin-6.After the intestinal tracts were removed,the location,amount,and size of the tumors were observed.The pathological changes of the tissue sections were observed,and the distributions of TNF-α and Ki-67 in the normal tissues and tumors were detected by immunohistochemistry.Results Upon the completion of the study,the mortality rate of rats was 20.00％ in the SDT group and 26.67％ in the HFDT group,the tumor formation rate was 75.00％ in the SDT group and 81.82％ in the HFDT group,and the tumor-bearing rate was 117％ in the SDT group and 191％ in the HFDT group.No statistical significance difference between the two groups in mortality rate,tumor formation rate (P =0.545) and tumor bearing rate (x2 =1.343,P =0.247).The average tumor volume was significantly different between the standard diet feed control group and high-fat diet feed control group (28.57％ vs 66.67％,P =0.030).Also,the serum triglyceride and TNF-α levels significantly differed between the SDT group and HFDT group [TG (1.39 ± 0.31) mmol/L and TNF-α (124.80 ± 21.69) ng/L in the HFDT group and TG (0.46 ±0.20) mmol/L and TNF-α (85.83 ± 17.45) ng/L in the SDT group] (P =0.000).The expressions of TNF-α,IL-6,and Ki-67 in colonic mucosa were significantly higher in the high-fat diet feed control group than in the standard diet feed control group [TNF-α(6.22 ± 0.63) ng/g vs (2.33 ± 0.44) ng/g,P=0.020; IL-6(13.50±0.67) ng/gvs (7.31 ±0.41) ng/g,P=0.000; and Ki-6740％ vs 10％,P =0.028].The Ki-67 expression rate was 90.48％ in the HFDT group,compared to 50％ in the SDT group (P =0.015).Conclusions High-fat diet can increase the serum triglyceride and TNF-α levels in rats,upregulate the expressions of TNF-α,IL-6 and Ki-67,and thus promote inflammation and cell proliferation,and ultimately affect the tumor formation and development.However,the effect of fat on DMH-induced colon tumors warrants further studies.