The Study On Effect And Mechanism Of Green Tea Extractive EGCG On HepG2 Transplanted Tumor In Nude Mice

Abstract:Objective:The effect and its potential mechanism of EGCG on the histological structure, ultrastructure and angiogenesis of human hepatocellular carcinoma cell strain HepG2 transplanted tumors in nude mice were investigated, in order to provide experimental evidence and new mode for green tea extractive EGCG in primary hepatic carcinoma clinical treatment.Methods:1.BALB/C (n/n) nude mice were used to replicate HepG2 transplanted tumor model, and they were randomly divided into experimental and control groups when their transplanted tumors growed to 6mm in diameter. Each nude mouse of experimental group was treated with EGCG (20mg/kg/d) by intraperitoneal injection, and the control group mice were treated with aqua pro injectione by the same way. After 3 weeks, nude mice were humanely killed, the volume and weight of transplanted tumors were measured, the tumor inhibition ratio (IR) was calculated by the formulation:IR=(1-transplanted tumor weight of experimental group/transplanted tumor weight of control group)×100%. The heart, liver, spleen, lung and kidney of nude mice were preserved.2.The histological structure of HepG2 transplanted tumors and other organs of nude mice were observed by light microscope.3.The ultrastructure of HepG2 transplanted tumors were observed by transmission electron microscope (TEM).4.The mRNA expressions of HIF-1αand VEGF in HepG2 transplanted tumors were analyzed through reverse transcription-polymerase chain reaction (RT-PCR).5.The protein expressions of HIF-1αand VEGF in HepG2 transplanted tumors were detected through immunohistochemistry (IHC), and the microvessel density (MVD) was marked by CD34.6.All the experimental results were analyzed by statistical software SPSS 16.0. Results:1.Both the volume and weight of HepG2 transplanted tumors in the experimental group were significantly decreased than that in the control group (P<0.05), the tumor inhibition ratio was 31.63%±4.09%.2.The histological structure of HepG2 transplanted tumors were contrasted by light microscope, a number of necrosis, pyknosis, karyorrhexis and karyolysis were showed in the experimental group, and tumor vessel was scarce; while in the control group, the HepG2 transplanted tumor cells were arranged in nests and showed significant heteromorphism, the necrosis was limited and tumor vessels proliferated actively. The histological structure of other organs of nude mice had no significant difference between experimental and control groups.3.The ultrastructure of HepG2 transplanted tumors were contrasted by TEM, apoptosis and necrosis were showed in the experimental group, apoptosis body was appeared and chromatin was broken into pieces in the stroma; while in the control group, paramorphia of cells, significant nuclear atypia and karyokinesis were showed, lipid droplet and swelling mitochondrion were appeared in the cytoplasm.4.The mRNA expressions of HIF-1αand VEGF in HepG2 transplanted tumors of experimental group were significantly down-regulated compared with the control group (P<0.05).5.Both the protein expressions of HIF-1α, VEGF and the MVD in HepG2 transplanted tumors of experimental group were significantly decreased versus the control group (P<0.05).Conclusions:1.The green tea extractive EGCG may inhibit the growth of HepG2 transplanted tumors in nude mice.2.The green tea extractive EGCG may inhibit the angiogenesis of HepG2 transplanted tumors in nude mice. 3.The green tea extractive EGCG may induce apoptosis of HepG2 transplanted tumor cells.4. Through down-regulating the expressions of HIF-1αand VEGF, EGCG has inhibition effect on tumor angiogenesis, which may be one of the potential mechanism of EGCG acted on the HepG2 transplanted tumors.5.The green tea extractive EGCG has little adverse reaction to the nude mice with HepG2 transplanted tumors.