Experimental Study Of Glioma ABCG2 Gene To Promote Stem Cell Proliferation And Invasion

The present study showed that malignant gliomas(short for glioma) are the most common in primary central nervous system malignancies. The incidence of gliomas accounts for about 50% of all primary brain tumors. Generalized glioma contains all neuroepithelial tumors, while narrow definition includes only glial cell-derived intracranial tumors. Glioma cells have multiple sources, including astrocytoma, small branch glioma and ependymoma, and more than ten other types. Different sources show different biological behavior of tumors.Astrocytoma glioma is the most common type, accounting for about 31% of the incidence of central nervous system tumors, and about 78 percent of gliomas. The disease is more common in men with high incidence in age of 30 to 40 years old. The lesion on temporal lobe and frontal brain is more common. Astrocytoma is pleomorphic, and according to the World Health Organization(WHO) classification, astrocytoma of obese type is II ~ III, anaplastic astrocytoma is grade III, multiforme glioblastoma(GBM) is VI. The higher the grade, the more aggressive and invasive is. At present, the surgical treatment of glioma has been significantly improved, and with the appropriate role of radiotherapy and targeting chemotherapy drug, the prognosis of gliomas has improved significantly. But because of its highly invasive and invasive, the overall cure rate of glioma patients remains poor. Therefore, it is necessary to further the understanding of the molecular mechanisms of glioma cell malignancies related material behavior of the students lay a theoretical foundation for future targeted therapies.ATP-binding cassette sub-family G member 2, ABCG2,is also known as breast cancer resistance protein or palacental ABC protein / mitoxantrone resistance protein. ABCG2 protein belongs to the ATP-binding cassette family of transporters. The family is a member of the oldest and most transporters constituent units, with a high degree of evolutionary conservation and species homogeneity. It has now been confirmed that the expression of ABCG2 proteins are present within various tissues including pancreas, liver, small intestine and rectum. In addition, ABCG2 protein expression existed in glioma cells, breast cancer cells and lung cancer cell surface. Recent studies have reported that ABCG2 protein expression is observed in a variety of stem cell surface, and has a high degree of similarity. In addition, ABCG2 protein was also considered to be a key regulatory molecule in stem cells "side-population" behavior. Therefore, many researchers think that ABCG2 protein may be an effective cancer stem cell marker. It may be able to affect the biological behavior of tumor cells by regulating the expression of ABCG2 gene. Studies have shown that downregulation ABCG2 can inhibit the proliferation of colorectal cancer cells and Wilms tumor cell migration and invasion capacity. However, the relationship between malignant behavior ABCG2 gene regulation and gliomas has not yet been fully elucidated.Matrix metalloproteinases(Matrix metalloproteinases, MMPs) belong to a family of zinc-dependent endopeptidase. Currently, it has been confirmed the presence of 23 members in the human body. MMPs are enzymes promoting major extracellular matrix(ECM) and basement membrane degradation cells. ECM and basement membrane cells are regulated environment interactions with cells around individual cells, as well as an important intermediary between multicellular and multi-organization collaborative development. Therefore, MMPs have played an important role in a variety of cell biological processes, including tumor cell migration and invasion. It has now been confirmed that increased MMP9 activity is closely related to GBM cell migration and infiltration enhancement. More recently, one of MMP9 activity inhibitor, marimastat, in clinical research has been carried out in combination with chemotherapy in patients with GBM. Thus, reason to believe that further insights into the pathogenesis of MMPs promote and develop GBM for MMPs activity in targeted therapy, the treatment of which may be effective in improving the prognosis of GBM.Objective:1. To observe the effects of ABCG2 gene regulation on U251 cell proliferation, migration and invasion.2. To explore the relationship between ABCG2 protein expression and activity of MMPs, and to explore the molecular mechanisms of further down ABCG2 protein expression on the inhibition of the malignant behavior of GBM.Methods:1. Cultivate U251 cell lines, and separate CD133-positive cells by MACS method. ABCG2-si RNA and ABCG2 overexpressing plasmid were transfected into U251 cells, respectively. Construct low ABCG2 protein expression and overexpression models.2. After transfection of ABCG2-si RNA and overexpressing plasmid into CD133 positive U251 cells, the expression of ABCG2 protein was observed, and the changes of cell proliferation, invasion and migration rate were measured by MTT, Transell and cell scratch assay.3. After transfection of ABCG2-si RNA and overexpressing plasmid into CD133 positive U251 cells, the expression of ABCG2 protein was observed, the expression of MMP9 and the activity of ABCG2 were observed.Result:1. The expression of ABCG2 and m RNA was significantly decreased after CD133 positive U251 cells were treated with ABCG2-si RNA. The expression of ABCG2 protein and m RNA was significantly increased after transfection of ABCG2 overexpressing plasmid into CD133 positive U251 cells.2. After CD133 positive U251 cells were treated with ABCG2-si RNA, the expression of ABCG2 protein was decreased, the proliferation, invasion and migration of U251 cells were significantly inhibited. After CD133 positive U251 cells were transfected with ABCG2 overexpressing plasmid, the expression of ABCG2 protein was increased, and the proliferation, invasion and migration of U251 cells were significantly increased.3. After CD133 positive U251 cells were transfected with ABCG2-si RNA and ABCG2 cells, it could change the expression of ABCG2 protein, but it did not affect the synthesis of MMP9 protein and m RNA. After CD133 positive U251 cells were treated with ABCG2-si RNA, the expression of ABCG2 protein decreased, and the activity of MMP9 cells was significantly decreased in U251 cells. After CD133 positive U251 cells were treated with ABCG2 overexpressing plasmid, the expression of ABCG2 protein was increased, and the activity of MMP9 cells in U251 cells was significantly enhanced.Conclusion1. Downregulation of the expression of ABCG2 protein in U251 cells could inhibit the proliferation, invasion and migration of U251 cells.2. The molecular mechanism of ABCG2 gene expression to promote stem cell proliferation and invasion may be related to the activity of MMP9.