[Study of apoptosis gene expression in U937 cells induced by adhesion culture with mesenchymal stem cell]

To compare apoptosis gene expression profiling of U937 cells in suspension culture with that cultivated with mesenchymal stem cells (MSCs), and find out the relationship between drug resistance of leukemia cells and hemopoietic microenvironment.

U937 cells were cultivated in adhesion culture with MSCs and in suspension culture for 48 hours. Cell cycle was determined by flow cytometry and gene expression profiling by cDNA microarray.

Compared with that in suspension, G(0)/G(1) fraction of U937 cells increased in adhesion culture (45.3 +/- 3.1)% vs (32.6 +/- 2.1)%, respectively (P < 0.05), whereas G(2)/M fraction and apoptosis rate were decreased. After 48 h twenty-eight differential expression genes were screened out in 487 apoptosis-related genes, among which 27 were up-regulated and were mainly apoptosis-suppressor genes, apoptosis-promoter genes, cell cycle positive control genes and cell cycle negative control genes. But Bcl-XL was up-regulated most obviously. The only one gene down-regulated was an apoptosis promoter gene.

Adhesion culture with MSCs can lead to growth suppression and decrease natural apoptosis of U937 cells. The mechanism was multiple gene effects, but Bcl-XL may be of the most importance.