Investigation Of The Mechanism Of Breast Cancer By Using The Liver-specific Insulin-like Growth Factor Ⅰ Gene Deficient Mice

PartⅠConstruction and Comparison of Mammary Tumor Model in Micein different Serum Insulin-like Growth FactorⅠ(IGF-Ⅰ) LevelsObjective The aim of this study was to examine the difference of the occurence ofmammary tumor in low and normal serum insulin-like growth factorⅠ(IGF-Ⅰ) levels mice,using liver-specific IGF-Ⅰdeficient (LID) mice and control mice to set up primarymammary tumor model. To investigate the role of IGF-Ⅰin the development of mammarytumor and try some intervening treatment.Methods The liver-specific IGF-Ⅰdeficient mice and control mice were used. Induction ofmammary tumor was achieved by using the 7,12-dimethybenz(a)anthracene (DMBA).Ginsenoside Rg3 (Rg3) was used to interfering therapy treatment. The difference ofincidence, diameter, number and growth rate of mammary tumor was compared.Results The incidence of tumor in none Rg3 injected control mice was 66.67% which wassignificantly higher than any other group (P＜0.05). The incidence of tumor in Rg3injected LID mice was 12.00% which was significantly lower than any other group (P＜0.05). The average diameter of tumor in none Rg3 injected control mice was(0.79±0.20)cm which was significantly higher than any other group (P＜0.05). The averagediameter of tumor in Rg3 injected LID mice was (0.15±0.05)cm which was significantlylower than any other group (P＜0.05). Comparing to control mice, serum IGF-ⅠandIGFBP-3 levels were significantly decreased (about 75%) in LID mice. The levels woulddecline further after the treatment of ginsenoside Rg3. After the treatment of ginsenosideRg3, serum IGF-Ⅰlevel decreased significantly in LID mice and control mice (P＜0.05), while serum IGFBP-3 level decreased not significantly (P＞0.05).Conclusions IGF-Ⅰplays a role in the onset and development of mammary tumor.Degrading serum IGF-Ⅰlevel is able to inhibit the growth of mammary tumor. There is asynergistic effect with the application of ginsenoside Rg3. PartⅡThe Study of the Influence of IGF-Ⅰto the Development andAngiogenesis of Mammary TumorObjective A stable primary mammary tumor model in IGF-Ⅰdeficient (LID) mice andcontrol mice was established. Breast tumor tissues and normal breast tissues were collectedrespectively. Immunohistochemistry and gene chip technology were applied. Expressionsof IGF system and angiogenesis-related genes in the development of mammary tumor werecompared to investigate the possible mechanisms of tumorigenesis.Methods Breast tumor tissues and normal breast tissues were collected immediately aftertumor-bearing mice were executed. Expressions of VEGF and microvessel density (MVD)were detected by immunohistochemistry. Expressions of IGF system andangiogenesis-related genes were detected by gene chip.Results The average light density and positive rate of VEGF were the highest in none Rg3injected control mice (0.34±0.10 and 0.04±0.02, P＜0.05), and the lowest in Rg3 injectedLID mice (0.13±0.03 and 0.01±0.00, P＜0.05). The microvessel density was the highest innone Rg3 injected control mice (31.9±5.3, P＜0.05), and the lowest in Rg3 injected LIDmice (14.4±4.9, P＜0.05). The results of gene chip indicated that in contrast to LID mice,IGF-IR,IGF-IIR,IGFBP-2,IGFBP3 genes of IGF system and VEGFA,FGFR1,PDGFA,MMP2 genes of angiogenesis-related genes were up-regulated, IGF-Ⅰ,IGFBP-4 genes ofIGF system and IL12A,PECAM1 genes of angiogenesis-related genes weredown-regulated in the mammary tumor tissues of control mice. Application of ginsenosideRg3 therapy could change the expression of these genes.Conclusions Circulating IGF-Ⅰplays a role in the onset and development of mammarytumor and is closely related with angiogenesis. Degrade serum IGF-Ⅰlevel is able to affectthe expression of IGF system and a series of angiogenesis-related genes consequentlyinhibit the growth of mammary tumor. There is a synergistic effect with the application ofginsenoside Rg3. PartⅢCell Proliferation and Apoptosis Related Gene Expressions inDiverse Serum Insulin-like Growth Factor I Levels of Mammary TumorModelObjective A stable primary mammary tumor model in IGF-Ⅰdeficient (LID) mice andcontrol mice was established. Breast tumor tissues and normal breast tissues were collectedrespectively. Flow cytometry and gene chip technology were applied. Expressions of cellproliferation and apoptosis related genes in the development of mammary tumor werecompared to investigate the possible mechanisms of tumorigenesis.Methods Breast tumor tissues and normal breast tissues were collected immediately aftertumor-bearing mice were executed. The cell cycle and apoptotic ratio was compared byflow cytometry. Expressions of genes related to cell cycle and apoptosis were analyzed byGene Chip.Results The proportion of tumor cells in S phase was the highest in none Rg3 injectedcontrol mice (30.87%±6.95%, P＜0.05), and the lowest in Rg3 injected LID mice(2.27%±0.60%, P＜0.05). The apoptotic rate was the lowest in none Rg3 injected controlmice (2.74%±0.69%, P＜0.05), and the highest in Rg3 injected LID mice (14.00%±1.74%,P＜0.05). The results ofgene chip indicated that in contrast to LID mice, BRCA1,RPA3,LTA,TNF-α,TRAIL,TRANCE,BLK,CASP8,TRAF5 and APAF1 genes weredown-regulated, and CCND1,CCNE2,CDC7,CDK2,LTBR,TRAF4 and GADD45Agenes were up-regulated in the breast cancer tissues of control mice. Application ofginsenoside Rg3 therapy could change the expression of these genes.Conclusions Circulating IGF-Ⅰplays a role in the onset and development of mammarytumor. Degrade serum IGF-Ⅰlevel is able to inhibit cell proliferation and promote apoptosisby affecting the expression of a series of cell cycle and apoptosis related genesconsequently inhibit the growth of breast cancer. There is a synergistic effect with theapplication of ginsenoside Rg3.