BACKGROUND:WIF-1 is a tumor suppressor gene. Promoter hypermethylation causes WIF-1 down-regulationin most tumors. DNA methylation inhibitor can lead to gene demethylation and restore its expression. OBJECTIVE:To observe the differences of tumor pathology and, WIF-1 mRNAand proteinchanges using WIF-1 or 5-aza-2'-deoxycytidine demethylation in animalmodels of osteosarcoma.
METHODS:Murine osteosarcoma models were established and divided into three groups. In the control group, no treatment was given. In the 5-aza-2'-deoxycytidine group, an appropriate amount of 5-aza-2'-deoxycytidine was injected ineach mouse daily. In the WIF-1 group, an appropriate amount of Wnt/β-catenin signal transduction pathway inhibitor WIF-1 was injected in each mouse daily. Seven days after medication, the weight of nude mouse was weighed every 7 days. Short tumor diameter (a) and the long diameter (b) were measured. Therelative tumor volume was calculated. The relative growth rate of tumor was calculated at 7, 14, 21, 28 and 56 days. Four nude mice from ach group were sacrificed by puling the neck at 7, 14, 21, 28 and 56 days after medication. Tumor tissues were stripped and the weight of them was weighed. Pathological analysis of the tumor was conducted. The expression of WIF-1protein and WIF-1 mRNA was detected in osteosarcoma at 56 days after medication in the three groups.
RESULTS AND CONCLUSION:(1) Compared withthe medication and control groups, the weight of nude mice was increased at 7, 14, 21, 28 and 56 days in the treatment group. No significant difference was found between the medication and control groups. (2) The tumor size was significantly smaler in themedication group than in the control group. WIF-1 mRNA and WIF-1 protein expression was increased in the medication group compared with the control group to different degrees. (3) Results suggested that WIF-1 gene promoter methylation is one of the mechanisms of the development of osteosarcoma. Use of WIF-1 or 5-aza-2'-deoxycytidine demethylation can inhibit tumor growth in animal models of osteosarcoma.