Physcion blocks cell cycle and induces apoptosis in human B cell precursor acute lymphoblastic leukemia cells by downregulating HOXA5.

Acute lymphoblastic leukemia (ALL) presents the most common type of malignancy in children and ranks the third most common cancer in adults. This study is aimed to investigate the anti-leukemia activity of physcion in ALL. Our results have showed that physcion could significantly suppress cell growth, induce apoptosis and blocked cell cycle progression in vitro. Mechanistically, we found that physcion downregulated the expression of HOXA5, which is responsible for the anti-leukemia activity of physcion. To verify this finding, siRNA targeting HOXA5 and overexpressing plasmid were used to repress HOXA5 expression and introduce ectopic overexpression of HOXA5 in ALL cell lines, respectively. Our results showed that overexpression of HOXA5 significantly abrogated the inducing effect of physcion on apoptosis and cell cycle blockasde. In contrast, knockdown of HOXA5 by siRNA enhanced the anti-tumor effect of physcion on ALL cell lines. Our results provided experimental base for the use of physcion in the treatment of ALL.