BACKGROUND: Although several genetic aberrations and gene expressional changes have been shown to exist in tumors and different grades of astrocytomas, as well as in normal tissues, the gene profiling and genetic pathways associated with malignant transformation and progression remain unclear. OBJECTIVE: To identity differentially expressed genes related to tumor invasion from various grades and all-trans retinoic acid (ATRA)-treated astrocytoma cell lines by cDNA microarray. DESIGN, TIME AND SETTING: In vitro gene experiment was performed at the Department of Neurobiology, Third Military Medical University of Chinese PLA from January to October 2007. MATERIALS: Two different grades of astrocytoma cell lines CHG-5 (WHO grade Ⅱ) and SHG-44 (WHOgrade Ⅳ) were developed by our laboratory; a cell differentiation-inducing agent ATRA and a human cDNA microarray technology were used to determine differentially expressed genes (City University of Hong Kong). METHODS: Total RNA was extracted using the Trizol test kit. Reverse transcription was performed using Superscript Ⅱ reverse transcriptase. The eDNA product (target DNA) was marked with fluorochromes Cy3 (normal SHG-44) and Cy5 (CHG-5 or ATRA-treated SHG-44), followed by chip hybridization. MAIN OUTCOME MEASURES: Gene expression profiles of CHG-5 vs. SttG-44 and ATRA-treated vs. Normal SHG-44 were performed to identify differentially expressed genes. Several of these genes were randomly selected for North Blot analysis. The identification of genes that were similarly regulated (overlapping) was performed by comparing gene expression profiles between CHG-5 and SHG-44 cells, and between SHG-44 cells with or without treatment with ATRA. RESULTS: No significant differences were observed between CHG5 and SHG-44 cell line morphology. Under confocal microscopy. GFAP staining intensity of CHG5 cells was greater than SHG-44 cells (t = 6.078, P = 0.004). Growth curve analysis demonstrated that the speed of SHG-44 cell growth was greater than CHG5 cells. Fh,w eytometry analysis showed that the number of ATRA-treated SHG-44 cells at G0/G1 stage increased by 15%, compared with normal SHG-44 cells (P < 0.05). A total of 31 known genes with altered expression were identified in this study. Among them, 20 genes were upregulated and 11 were downregulated in CHG-5 compared with SHG-44 cells, and ATRA-treated SHG-44 compared with untreated SHG-44 cells. Four of these reported genes (CD151, G3BP, UGB, and CSTB) were shown to he involved in tumor invasion. Validation of a selection of differentially expressed genes was performed by North blot. CONCLUSION: A total of 31 known genes were demonstrated by cDNA microarray to relate to the malignant progression of astrocytomas, and four differentially expressed genes (CD151, G3BP, UGB, and CSTB) were shown to relate to tumor invasion.