| Objective: The present study was to explore the mRNA and protein expression level of TGF-β1 and Smad7 in human glioma cell, and the influce of over-expression of Smad7 on infiltration and proliferation in U251 glioblastoma cell line, aiming to discuss the proliferation, infiltration and recurring causes of glioblastoma, especially to find effectively curative target and strategy.Method and result: Using the immunohistochemical method, the present study detected the expression of smad7 and TGF-β1 in human glioma, and found that in the normal astrocytes the TGF-β1 did not express or hypo-expressed, oppositely it hyper-expressed in the glioma, furthermore, the expression level increased correspondingly with the histological grade. The expression level of TGF-β1 is 5.75±3.28%,15.23±5.63% and 40.02±10.35% in nomal astrocytes, low-grade glioma cells and high-grade glioma cells respectively. The expression level positively correlated with malignant grade (P<0.01). TGF-β1 can use as a marker of invasive capability and malignant grade. Smad7 expressed correlatively to TGF-β1. Smad7 did not express or hypo-expressed in the normal astrocytes and it also hypo-expressed in the glioma cells. The expression level of Smad7 showed increasing tendency with the histopathological grade increased, but there were not statistical significance between each group. This means that as the inhibitory factor of, TGF-β1 Smad7 could prevent the growing inhibition effects induced by TGF-β1, but it did not affect the development of glioma. The expression level of Smad7 showed increasing tendency among low-grade glioma, high-grade and glioblastoma. This means that as the inhibitory factor of, TGF-β1 Smad7 might take some effect in glioma malignant development.Smad7 plasmid was constructed and transfected to U251 cells. RT-PCR, Western blot and immunofluorescence methods were used to examine Smad7 mRNA and protein levels. Results showed that Smad7 was transfected to U251 cells successfully and it expressed stably in cytoplasm. The proliferation and invasion effects of Smad7 to U251 cells were detected.MTT method was used to measure cell proliferation rate and cell proliferative curve was draw to detect the effects of Smad7 to U251 cell proliferation. The results showed that those U251 cells that hyper-expressed Smad7 grew slowly and apoptosis percentage increased. That means over-expressed Smad7 blocked mitosis signal and inhibited cell proliferation and facilitated cell apoptosis by preventing the activation of TGF-β1 to ERK1/2 MAPK path.The relation between invasive behavior of glioblastoma cell and Smad7 was detected by Boyden chamber. Results showed that the invasive cell numbers of U251 group, pcDNA3.0 group and Smad7 group were 277±58, 237±54 and 66±27 respectively. The invasive behavior of those U251 cells that hyper-expressed Smad7 was definitely inhibited in the Boyden chamber. The hyper-expressed Smad7 could suppress the invasive ability and malignant transformation of glioblastoma cell. Gelatinase spectrum analysis result showed that MMP2 enzymolysis quantity of Smad7 group, pcDNA3.0 group and U251 were 1.67±0.57,4.03±1.42 and 4.15±1.65. The MMP2 activity of Smad7 group was obviously lower than that of U251 group and pcDNA3.0 group (P<0.05). This means that the over-expressed Smad7 could inhibited the invasive ability of glioma by stopping expressing of MMP2.Conclusion1. The protein expression of transforming growth factorβ1 (TGF-β1) correlated closely with proliferation capability and histopathological grade of glioma cell. It can be used as a marker to estimating invasive capability, histopathological grade and prognosis of glioma. The expression level of Smad7 showed increasing tendency with that of TGF-β1, although it did not have significant deviation in nomal astrocytes and every grand of glioma. TGF-β1 can stimulate the expression of Smad7 which have no relation with the histopathological grand of glioma. Smad7 take part in the malignant progression of human glioma by regulating the expression of TGF-β1. TGF-β1 and Smad7 might take synergistic effect in the proliferation and invasion of human glioma.2. By analysising the effect of Smad7 to signal pathway and glioma cell, the effection of Smad7 in the progression of glioblastoma was estimated again. The previous study showed that Smad7 play a role of oncogene by stopping the cell inhibition of TGF-β1, and its effection in the malignant progression and recurrence of glioma was still unknown. Our study showed that the U251 glioblatoma cell transfected with Smad7 could over-express Smad7 which inhibited the invasion of glioma cell. The result showed that over-expression of Smad7 in glioblastoma could take active effect in preventing the malignant progress and recurrence of glioblatoma, the Smad7 could be an adjunctive therapy target to the glioblastoma. By analysising the study of Smad7 nowadays, we believe that Smad7 play a different role in different progression of glioma, the role shoud be treat differently, especially the chronergy of role should be paid attention.
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