Abstract: Objective To investigate the expression of Sp100 in ATRA-treated NB4 cellsandits effect on proliferation in NB4 cells.Methods Q-PCR was employed to measure the expression of Sp100 mRNA;Western blot was used to detectthe expression of Sp100 protein; Immunofluorescence was adopted to determine the location of Sp100;Cell viability was analyzed by CCK8;Flow cytometry was used for cell cycle analysis. Results ATRA could induce obviously the expression of mRNA and protein of Sp100. ATRA changed the location of Sp100 from a micro-punctate pattern into a punctate nuclear patternin NB4 cells. Sp100-shRNA promoted the proliferation of NB4 cells and increased the cells in G2/M phase.Conclusions The expression of Sp100 was significantly increased in ATRA-treated NB4 cells, and Sp100 may be involved in the regulation of proliferation activity of NB4 cells.

Key words: acute promyelocytic leukemia, Sp100-shRNA, NB4 cells, proliferation