| Glioma is the most common tumor in the central nervous system. Glioblastoma, the most malignant form of glioma, usually leaded to a poor prognosis because of its drug resistance and other malignant characteristics. Recent studies have indicated that tumor stem cells are the source of tumor recurrence, invasion and treatment resistance. Therefore, the research on the "stemness" maintenance of glioma stem cells and the relationship with the mechanism of drug resistance will provide new ideas and methods for the clin ical treatment of glioma.HOX family is a kind of gene that regulates the formation of organism. HOXA5 gene is located on chromosome 7. It is mainly expressed in the head and neck tissue, and plays an important role in the development of human embryonic development and the differentiation of adult stem cells. The abnormal expression of HOXA5 has been found in breast cancer, lung cancer, lymphoma and some other tumors. However, the role of HOXA5 in the development of glioma remains unknown.In this study, we analysed the relationship between HOXA5 and stemness of glioma by changing HOXA5 expression. The mechanism of HOXA5 in regulating the stemness of glioma was studied by observation of PTPRZ1 expression change which is the downstream molecule of HOXA5. Then, the correlation, collocation between HOXA5 and the stemness marker of glioma was analyzed.The relationship between HOXA5 expression and the prognosis of glioma patients was also analyzed. Meanwhile, the relationship between HOXA5 and TMZ resistance of glioma cells was analyzed by observation change of P65 expression which is key molecule in NF-kB pathway and IC50 of TMZ. Finally, the function of MGMT in molecular typing and prognosis prediction of glioblastoma were analyzed by using a large scale clinical sample.The main results and conclusions are as follows:1. HOXA5 was highly expressed in glioma stem cells, and had a positive correlation with tumor grade.(1) HOXA5 expression was detected by immunohistochemistry in 209 cases of gliomas. We found that the expression of HOXA5 was increased with the increase of tumorgrade. This result was also verified by detecting HOXA5 expression in different glioma cell line U87, U251, CHG5, HEB, and the primary cell line 091214, 090116.(2) Tumor stem cells and non tumor stem cells were isolated from human glioma cell line U87 and Primary glioma cells 091214. We found that the protein and m RNA levels of HOXA5 in tumor stem cells were higher than in the non tumor stem cells. By using double immunofluorescence staining, we found that HOXA5 was colocalized with stemness markers, which was valiated in TCGA database.2. HOXA5 induced the "stemness" of human glioma stem cells by regulating PTPRZ1 expression.(1) We found that the expression of stemness markers CD133, SOX2 were increased by overexpression of HOXA5. Meanwile, the ability of the tumorsphere formation and cloning formation was also increased.(2) HOXA5 knock down decresed the expression of stemness markers CD133, SOX2, and suppressed the ability of self-renewal and cloning formation.(3) In our previous research, we found that PTPRZ1 is a key molecule in regulating the stemness of gioma stem cells. Here, we found that there were two possible binding sites of HOXA5 in the PTPRZ1 promoter region by database analysis. The binding site 1 was confirmed by by Chi P and Luciference experiments. The results were also verified by the same changing trend of HOXA5 and PTPRZ1.3. HOXA5 regulated TMZ resistance of glioma cells through NF-kB pathway and predicted poor prognosis of glioma patients(1) The TMZ IC50 value of glioma cells shares a consistent change trends with the expression change of HOXA5.(2) The expression change of HOXA5 was positively related with the P65 expression through the NF-k B pathway.(3) HOXA5 expression was negatively correlated with the prognosis of glioma patients in both specimens from Sourthwest hosptial and the TCGA database.(4) The expression of HOXA5 was negatively correlated with the survival rate of nude mice in the orthotopic transplantation model.4. MGMT, the key molecules of TMZ resistance, plays an important role in molecular typing and diagnosis of glioblastoma(1) The expression of MGMT was lower in proneural-like subtype GBM.(2) MGMT was negatively correlated with P53 expression.(3) Lower MGMT expression predicts better prognosis in proneural-like GBM.(4) The expression of MGMT in proneural subtype was lower and the prognosis was better in TCGA database.In conclusion, HOXA5 can induce the stemness of glioma cells by regulating the expression of PTPRZ1, and can influence the TMZ resistance of glioma cells through NF-kB pathway. Meanwhile, HOXA5 combined with MGMT plays an important role in molecular typing and prognosis prediction of glioblastom. Therefore, targeting HOXA5 may provide new ideas and new targets for the treatment of glioma. |
PDF Full Text Request