Abstract:

Zhao Yan*，Ye Yuhong, Wu Lixian, Fang Fang, Cheng Bo. *First Affiliated Hospital of Fujian Medical University, Fujian Provincial Institute of Dermatology，Fuzhou 350009，China Corresponding author: Cheng Bo, Email: chengbofj@gmail.com 【Abstract】 Objective To evaluate the effects of acitretin combined with clarithromycin on tumor growth in human oral epidermoid carcinoma xenografts in nude mice, and to investigate their antitumor mechanisms. Methods A cell line of human oral epidermoid carcinoma was subcutaneously inoculated into 31 Balb/c nude mice to establish a xenograft model of human skin tumor. Then, the nude mice were randomly classified into 6 groups according to a double blind protocol: control group （n = 6） remaining untreated, placebo group （n = 5） treated with wheat flour, acitretin group （n = 5） treated with acitretin 7.2 mg/kg per day, clarithromycin group （n = 5） treated with clarithromycin 100 mg/kg per day, acitretin + placebo group （n = 5） treated with both acitretin （7.2 mg/kg per day） and wheat flour, and acitretin + clarithromycin group （n = 5） treated with acitretin （7.2 mg/kg per day） and clarithromycin 100 mg/kg per day. All the drugs were intragastrically administrated once daily. After three weeks of treatment, mice were sacrificed and xenografts were removed. Then, the size and weight of xenografts were measured, and pathological analysis was conducted. Real time-PCR was performed to quantify the mRNA expressions of vascular endothelial growth factor （VEGF） and nuclear factor （NF）-κB, and immunohistochemistry was carried out to observe the expression of VEGF as well as to determine microvessel density （MVD） and Ki-67 proliferation index. By using the software SPSS 19.0, analysis of variance was performed for comparison of measurement data, and least significant difference （LSD） test for paired comparisons. Results Both the size and weight of xenografts in the acitretin + clarithromycin group were significantly lower than those in the other groups （all P < 0.05）. Real-time fluorescence-based PCR revealed weaker mRNA expressions of VEGF and NF-κB in the acitretin + clarithromycin group compared with the control group, clarithromycin group and acitretin group （all P < 0.05）. As immunohistochemistry showed, the acitretin + clarithromycin group displayed a decrease in the expression rate （all P < 0.01） and staining intensity of VEGF, MVD （all P < 0.01） with a sparse distribution of microvessels, Ki-67 proliferation index （all P < 0.05） and proliferative activity of tumor cells compared with the control group, clarithromycin group and acitretin group. Conclusion Acitretin combined with clarithromycin can synergistically inhibit the growth of human oral epidermoid carcinoma xenografts in nude mice, downregulate VEGF expression, and suppress angiogenesis and tumor proliferation.