动物造模,药效评价,转基因垂体瘤 z-bio 2024-07-18 564

　　1. FSH β - SV40T transgenic pituitary tumor mouse model

　　The T antigen oncogene of SV40 has strong cell transformation ability, causing an increase in cell dedifferentiation rate and a decrease in hormone synthesis. The expression of T antigen in pituitary gonadotropin cells leads to the transformation of gonadotropin cells and the formation of tumors.

　　[Modeling Method] The 4.7kb 5 'flanking sequence (containing exon 1, intron 1, and exon 2) of the 5.5kb sheep FsH β gene was cloned into a pBKCMV vector containing the large and small T coding regions of the SV40 T antigen at the transcription start site to form an FSHB-T antigen fusion gene fragment, which was used for microinjection to prepare a transgenic pituitary tumor mouse model in which the regulatory region of the sheep FSHB gene directly expressed the SV40T antigen oncogene.

　　[Model features] The 2/5 transgenic mouse line with this fusion gene rapidly develops pituitary tumors, with adenomatous follicles appearing at 6 weeks of age and male and female deaths at 12 weeks of age. Histological examination showed that the increase in cell proliferation accompanied by underdevelopment was due to a decrease in pituitary hormone synthesis, indicating that pituitary cells were in a dedifferentiated state without the expression of gonadotropins and other pituitary hormones. The origin of the tumor presents as multiple lesions, with highly transformed giant pale stained basophils and numerous polyploid nuclei, accompanied by neuronal like cell infiltration. These cells are abundant in the final stage of tumor development. The mitotic classification index is very high in genetically modified pituitary gland. The study of this model contributes to understanding the physiological and molecular mechanisms underlying the formation of pituitary tumors.

　　2. PyLT transgenic pituitary tumor mouse model

　　The early genes of the SV40 virus genome encode two types of tumor antigens, among which the poly large T antigen (PyLT) is essential for initiating cell transformation. Integrating the PyLT gene into the mouse genome can induce tumor formation in pituitary cells.

　　[Modeling Method] The early promoter gene of the multi tumor virus was connected to the PyLT cDNA to form an exogenous gene component. The transgenic animal model of Cushing's disease in mice was established by microinjection into the spermatogonia of mouse fertilized eggs.

　　[Model Features] The pituitary morphology of this model is normal at 4 months of age, and there is no significant morphology or microadenoma formation at 9 months of age. Transgenic mice with clinical manifestations show pituitary adenomas at 13-16 months of age. Up to 5mm in size. At 9 months of age, the weight of transgenic mice was significantly higher than that of the normal control group, but they began to lose weight at 12 months of age. These aged PyLT-1 mice showed increased adrenal gland weight and medullary hyperplasia. Subcutaneous transplantation of pituitary tumors from genetically modified mice onto non genetically modified mice with normal immune function resulted in tumors that were very similar in morphology to the primary tumor. In mice carrying genetically modified pituitary transplants, the effect of high corticosteroids is more enhanced than in transgenic mice themselves. Moreover, these mice transplanted with tumors showed weight gain, centripetal deposition, and enlarged adrenal cortex, similar to the symptoms of Cushing's disease in humans. The plasma ACTH level significantly increased in clinically affected transgenic mice.

　　This transgenic mouse is a good animal model for studying the pathogenesis of pituitary adrenocorticotropic cell tumor and Cushing's disease.

　　3. HMGA2 transgenic pituitary tumor mouse model

　　The HMGA2 protein belongs to the high mobility group A family. The expression of HMGA gene is very low in CD34 positive stem cells, and its expression can be ignored in normal adult tissues, mainly limited to embryonic development. However, HMGA can be overexpressed in some individuals and experimentally induced malignant tumors. Overexpression of HMGA2 in the pituitary gland can lead to growth hormone cell/PRL cell adenomas.

　　[Modeling Method] The CMV promoter was ligated with HMGA2 cDNA to form an exogenous gene component, which was then microinjected into B6C3F1 fertilized eggs to establish transgenic mice overexpressing HMGA2.

　　This transgenic mouse shows that the HMGA2 gene is highly expressed in all normal tissues. At 6 months of age, 85% of female HMGA2 mice developed pituitary adenomas that secrete PRL and growth hormone. However, only 40% of HMGA2 males have a late onset (about 18 months).

　　This model is used for the study of the pathogenesis and gene expression of pituitary PRL cell and growth hormone cell adenomas.

　　At present, the exogenous gene components used to prepare transgenic pituitary tumor mouse models are different, attempting to elucidate the pathogenesis of pituitary tumors from different perspectives. Each transgenic model has its own characteristics, for example, FSH β - SV40T transgenic pituitary tumor mice can quickly exhibit clinical manifestations of pituitary tumors, because the T antigen of SV40 has strong cell transformation ability, the tumor has malignant characteristics, and there is no functional hormone secretion. However, PyLT transgenic pituitary tumor mice developed later and showed elevated plasma ACTH levels, exhibiting clinical manifestations similar to human Cushing's disease.