Chemo-sensitivity Of HEL Cells Are Reduced By Direct Contact With Stromal HS-5Cells

Objective: To investigate the effects of the HS-5human bone marrow stromalcell line on the co-cultured acute erythroleukemia HEL cell line chemo-sensitivity andelucidate the underlying mechanisms.Methods: HEL cells were cultured in direct contact with HS-5for6,12and24h.CCK-8analysis was performed to determine the sensitivity of HEL cell to cytarabine,methotrexate, VP16and daunorubicin. Flow cytometry assays were performed todetermine cell cycle distributions. Real-time reverse transcription polymerase chainreactions （RT-PCR） were performed to detect the transcription level of p19, p21, p27,MDR1, ABCG2and bcl-2. Western blot analysis was performed to determine theprotein levels of p-Akt^Ser473, p-GSK3β^Ser9, p-STAT3^Tyr705, Bcl-2, cleaved-Notch1^V1754and Hes1.Results: Chemo-sensitivity of HEL cells were remarkably reduced by directcontact with HS-5cells. Additionally, HEL cells were arrested in the G0/G1phaseafter co-cultured for24h. Significant up-regulation of the transcription level of p21was documented. But the expression of p19decreased when HEL cells wereco-cultured for12h, and the level recovered at24h. But there were no significantchanges in the mRNA expression of the other genes detected. Direct contact withHS-5remarkably up-regulated the expressions of p-Akt^Ser473, p-GSK3β^Ser9,cleaved-Notch1^V1754and Bcl-2protein in co-cultured HEL cells, and significantlydown-regulated the expression of Hes1protein. But there was no obvious change ofp-STAT3^Tyr705.Conclusion: Direct contact with HS-5could remarkably reduce the chemo-sensitivity of HEL cell through the up-regulation of p21and Bcl-2, theactivation of phosphatidylinositol3-kinase signaling and Notch signals.