CXCL12/CXCR4 axis confers adriamycin resistance to human chronic myelogenous leukemia and oroxylin A improves the sensitivity of K562/ADM cells

This study was aimed at investigating the reversal effect of oroxylin A, a naturally bioactive monoflavonoid separated and purified from Scutellaria baicalensis Georgi, in human chronic myeloid leukemia (CML) and the underlying mechanisms. The results showed that CXCL12 could enhance the resistance of K562 cells to adriamycin (ADM) by increasing the expression of CXCR4, up-regulating the downstream PI3K/Akt pathway, and promoting translocation of NF-κB dimers into nucleus and subsequently decreasing the expression of apoptosis-related proteins in K562 cells. And we found that ADM resistance was partially reversed by CXCR4 siRNA transfection. Moreover, the sensitivity enhancement of oroxylin A was demonstrated by decreasing the expression of CXCR4 at both protein and mRNA levels, via PI3K/Akt/NF-κB pathway and triggering the apoptosis pathway in vitro. In addition, the in vivo study showed that oroxylin A increased apoptosis of leukemic cells with low systemic toxicity, and the mechanism was the same as in vitro study. In conclusion, all these results showed that oroxylin A improved the sensitivity of K562/ADM cells by increasing apoptosis in leukemic cells and decreasing the expression of CXCR4 and PI3K/Akt/NF-κB pathway, and probably served as a most promising agent for CML treatment.