Correlation Of MGMT And HMSH2 Expressions In Astrocytomas And Temozolomide-Experimental In Vitro Drug Sensitivity

Objective: To study the correlation between a DNA repair enzyme O6-methylguanine-DNA-methyltransferase (MGMT) and human mismatch repair protein-2 (hMSH2) expressions in astrocytomas and temozolomide in-vitro drug sensitivity, and the relevance of MGMT and hMSH2 expressions in astrocytomas, explore the role of the resistance of chemotherapy in astrocytomas by temozolomide , so as to guidance for clinical application of temozolomide, and provide laboratory's drug research data to clinical work that avoiding administering patients ineffectively.Materials and Methods: At first,We collected 16 fresh astrocytic tumor specimens from Department of Neurosurgery,First Affiliated Hospital Shanxi Medical University from June 2007 to January 2008 . By immunohistochemical technology, We detected the expression of hMSH2 and MGMT protein in each patient's tumor tissue, then tested the integral optical density (IOD) values of each patient's section on hMSH2 and MGMT protein by computer image analysis system (The five high-power fields IOD value of each patient's slice was tested randomly,then calculated the average and the standard deviation of each slice of the IOD value, and exoressed using mean±standard deviation.),at the same time , the same patient's tumor tissue was used to Cultured primary tumor cell, after success, and through the pathology and immunocytochemical detection signs Glial fibrillary acidic protein (GFAP) were used to identified as astrocytoma cells.Under the temozolomide-peak plasma concentration, drug sensitivity experiment was implemented, inhibitiory rates were calculated on the MTT assay,and then analyzed correlation of MGMT and hMSH2 expressions in astrocytomas and inhibition rates,and the correlation between MGMT and hMSH2 expressions in astrocytomas, to provide relevant information on mechanism of resistance of MGMT and hMSH2 to further study .Results: Integral optical density (IOD) values of 16 cases of astrocytoma specimens MGMT expression are218.0±2.788 , 198.7±6.253 , 120.4±5.089 , 147.5±5.788 , 152.3±10.963 ,84.3±4.735, 75.3±6.090,158.6±3.945,215.6±5.470,65.4±5.165,114.7±11.955,90.6±4.398,123.6±12.753,158.4±5.267,148.3±4.501,220.5±12.964,the range is 65.40 ~ 220.5, the average is 143.2625,and the standard deviation is 51.05765; Integral optical density (IOD) values of 16 cases of astrocytoma specimens hMSH2 expression are 89.4±7.632,98.5±7.489,175.5±7.865,189.4±8.970,178.6±11.123,87.4±3.576,123.4±5.002,56.4±5.231,68.4±5.517,150.4±7.596,143.6±7.001,179.4±6.315,100.5±5.822 ,147.5±7.665,98.6±4.588,174.5±6.772, the rang is 56.40 to 189.40, the average is 128.8438, and the standard deviation is 48.84352.16 inhibitiory rates of astrocytoma cells cultured in vitro are 0.130±0.014306 , 0.321±0.003162 ,0.811±0.009557,0.715±0.006880,0.654±0.008832,0.853±0.016793,0.694±0.008907,0.352±0.025677,0.152±0.016310,0.894±0.006218,0.722±0.030033,0.725±0.013832,0.723±0.020704,0.614±0.011916,0.614±0.011916,0.871±0.018276,the range is 13% to 89.4%, the average is 57%, and the standard deviation is 0.27293. The experimental data was analyzed statistically, found there was a negative correlation between the MGMT protein expression in astrocytomas and sensitivity of the temozolomide , with a correlation coefficient r = -0.895, P <0.05; and found there was a positive correlation between the hMSH2 protein expression in astrocytomas and sensitivity for the temozolomide , with a correlation coefficient r = 0.722, P <0.05; There was no correlation between the expression of hMSH2 and MGMT protein in astrocytomas.Conclusion: There is a close relationship between the expression of MGMT and hMSH2 in astrocytic tumors and the resistance of temozolomide.The expression level of hMSH2 and MGMT in astrocytomas was detected by the immunohistochemical technique, the expression level may reflect the sensitivity of patients with astrocytoma for temozolomide , and therefore guid the application of temozolomide in the clinical, increase the purpose of clinical chemotherapy, avoid ineffective treatment and reduce unnecessary burden on patients.