BACKGROUND: The detection of differential gene expression in brain is possible by cDNA microarray technology, and the screening of differentially expressed genes might provide a biological basis for gene-targeted therapy for tumors. OBJECTIVE: To detect the differential expression of genes among astrocytoma SHG-44 (WHO grade IV), CHG-5 (WHO grade II), and ATRA-treated SHG-44 cell lines by cDNA microarray. DESIGN: Laboratory experiments in vitro. SETTING: Department of Neurobiology, the Third Military Medical University. MATERIALS: The experiment was performed at the Department of Neurobiology in the Third Military Medical University of the Chinese PLA from January to October 2007. The SHG-44 cell line (WHO grade Ⅳ) was established by Prof. Ziwei Du, and the CHG-5 cell line (WHO grade II) was set up by Prof. Xiuwu Bian from the Third Military Medical University of the Chinese PLA. The cDNA microarray containing 9182 known genes was prepared and provided by Dr. Yang Zhong at the City University of Hong Kong. METHODS: To screen differentially expressed genes from the gene expression profiles detected by cDNA microarray comparisons were made between CHG-5 and SHG-44 cells and between SHG-44 cells with or without treatment with 10 μmol/L ATRA. Some differentially expressed genes were selected randomly for Northern Blot analysis to confirm the results of the microarray. The determination criteria for differential gene expression were as follows. ① The ratio of Cy5 signal to Cy3 was greater than 2.0 or less than 0.5. ② The results of the triplicate microarray hybridizations showed the same trend in three experiments. ③ A gene appeared at least two times on the triplicate microarray hybridizations, and the 3rd value did not show a contradictory trend. A normalized ratio of Cy5 intensity to Cy3 greater than 2.0 or less than 0.5 was considered to represent up-regulated or down-regulated gene expression, respectively. MAIN OUTCOME MEASURES: The identification of genes that were similarly regulated (overlapping) during tumor progression and differentiation, by comparison of gene expression profiles between CHG-5 and SHG-44 cells, and between SHG-44 cells with or without treatment with ATRA. RESULTS: Thirty-one overlapping genes were found to have similar regulatory effects on astrocytomas; among them, twenty genes were up-regulated and eleven were down-regulated in both comparisons between CHG-5 and SHG-44 cells, and between SHG-44 cells with or without treatment with ATRA. The four reported genes, SERPINF1, MAPK11, HIF1A and SOD2, were up-regulated in this study. CONCLUSION: The differentially expressed genes in different grade astrocytoma cell lines were revealed primarily by cDNA microarray; among them, five identified overlapping genes, SERPINF1, MAPK11, DCTN2, HIF1A and SOD2, were related to the malignant progression of astrocytoma cells. BACKGROUND: The detection of differential gene expression in the brain is possible by cDNA microarray technology, and the screening of differentially expressed genes might provide a biological basis for gene-targeted therapy for tumors. OBJECTIVE: To detect the differential expression of genes among astrocytoma SHG- 44 (WHO grade IV), CHG-5 (WHO grade II), and ATRA-treated SHG-44 cell lines by cDNA microarray. DESIGN: Laboratory experiments in vitro. SETTING: Department of Neurobiology, the Third Military Medical University. MATERIALS: The experiment was performed at the Department of Neurobiology in the Third Military Medical University of the Chinese PLA from January to October 2007. The SHG-44 cell line (WHO grade IV) was established by Prof. Ziwei Du, and the CHG-5 cell line (WHO grade II) was set up by Prof. Xiuwu Bian from the Third Military Medical University of the Chinese PLA. The cDNA microarray containing 9182 known genes was prepared and provided by Dr. Yang Zhong at the City U niversity of Hong Kong. METHODS: To screen differentially expressed genes from the gene expression profiles detected by cDNA microarray comparisons were made between CHG-5 and SHG-44 cells with or without treatment with 10 μmol / L ATRA. Some Difally expressed genes were selected randomly for Northern Blot analysis to confirm the results of the microarray. The determination criteria for differential gene expression were as follows. ① The ratio of Cy5 signal to Cy3 was greater than 2.0 or less than 0.5. ② The results of the triplicate microarray hybridizations showed the same trend in three experiments. ③ A normalized at least two times on the triplicate microarray hybridizations, and the 3rd value did not show a contradictory trend. A normalized ratio of Cy5 intensity to Cy3 greater than 2.0 or less than 0.5 was considered to represent up-regulated or down-regulated gene expression, respectively. MAIN OUTCOME MEASURES: The identification of genes that werEATED regulated (overlapping) during tumor progression and differentiation, by comparison of gene expression profiles between CHG-5 and SHG-44 cells, and between SHG-44 cells with or without treatment with ATRA. RESULTS: Thirty-one overlapping genes were found to have similar regulatory effects on astrocytomas; among them, twenty genes were up-regulated and eleven were down-regulated in both comparisons between CHG-5 and SHG-44 cells, and between SHG-44 cells with or without treatment with ATRA. CONCLUSION: The differentially expressed genes in different grade astrocytoma cell lines are cDNA microarray; among them, five identified overlapping genes, SERPINF1, MAPK11 , DCTN2, HIF1A and SOD2, were related to the malignant progression of astrocytoma cells.