Tetracycline Regulation Sv40tag Transgenic Mice To Medulloblastoma Model And Expression Analysis

Simian Virus40 (SV40) is double-strand polyoma virus and its early gene product SV40 large T antigen (SV40Tag) has proved to be participating in carcinogenesis. Epidemiology study has revealed that SV40Tag could be detected in most tumor tissue. Medulloblastoma is a neuroectoderm cerebel tumor, most frequently found in children central nerve system tumor. Accounts for 25 percent of children cerebral tumor, Medulloblastoma also has the highest mortality rate. Early research has shown that aberrance of the many A signal pathways including Shh., Wnt, erbB-2 and Igf were highly related to tumorigenesis of Medulloblastoma.The first chapter of the thesis described the generation a tetracycline-responsive SV40Tag transgenic mice model by pre-nuclear microinjection. SV40Tag expression has been detected in the offspring of one founder, transgenic line 123, through DOX inducing.Furthermore, the resulting mice of transgenic line 123 developed brain tumor after giving DOX. Through histopathology, molecular markers and immune-histochemistry, we identified this was medulloblastom, a tumor of the cerebellum. The result showed we have generated a transgenic medulloblastoma mice model.In the third part of the thesis, the animal model was analyzed through gene expression profile, real-time PCR, Western blotting and immnol-precipitation. Confirmed by real-time PCR and western-blotting, gene expression profile showed significant change in lgf and erbB-2 pathways while no such change was observed in Wnt or Shh pathway. Through further immune-histochemistry and immnol-precipitation experiments, we also found SV40Tag interacted with IRS-1 in igf pathway, which helped the latter enter the nucleus. Those results indicated that SV40Tag might change IGF pathway through this interaction and promoted the tumorigenesis.We also established the cell line of this transgenic mice model through primary cell culture to make use this model more efficiently. Drug sensitivity experiment isconducted on the cell line with a few anti-tumor drugs. The results showed that the cell was sensitive to receptor tyrosine kinase antagonist Gleeve.We concluded that this work has established the tetracycline-responsive SV40Tag transgenic mice model expression Medulloblastoma. Through micro-array and related techniques, we analyzed and screened the gene expression change of the tumor. The results strongly supported that expression of SV40 tag could activate Igf as well as erbB-2 pathway by unknown mechanism. We further developed the primary cell culture if the tumor cells which would lead to better use of this genetic model. This work provided a valuable in vivo tool for study SV40Tag induced tumorigenesis and could help the prevention, clinic diagnosis and cure of Medulloblastoma.