Dual targeting of retinoid X receptor and histone deacetylase with DW22 as a novel antitumor approach

Retinoid X receptor (RXR) and Histone deacetylase (HDAC) are considered important targets for cancer therapy due to their crucial roles in genetic or epigenetic regulations of cancer development and progression. Here, we evaluated the potential of dual targeting of RXR and HDAC using DW22 as a novel therapeutic approach to cancer treatment. We found that the co-expression of RXR-α and HDAC1 was frequently appeared in lung cancer and breast cancer tissues and cell lines. RXR was activated by DW22 in RXRα and HDAC1 overexpressed A549 and MDA-MB-435 cell lines. Meanwhile, DW22 inhibited the activity of HDAC by decreasing its expression in A549 and MDA-MB-435 cell lines, but not in RXRα and HDAC1 deficient cell lines. Moreover, DW22 suppressed cell growth, induced cell differentiation, prompted cell apoptosis and arrested cell cycle in A549, MDA-MB-435 or HL60 cell lines. Treatment human umbilical vascular endothelial cells (HUVECs) with DW22 suppressed migration, invasion and tube formation through decreasing VEGF expression. The up-regulation of Ac-H3 and p21, and down-regulation of VEGF caused by DW22 was markedly attenuated by silencing of HDAC1. Furthermore, knockdown of RXRα by siRNA completely blocked DW22-induced cell differentiation, but partially attenuated DW22-caused inhibition of cell proliferation, induction of cell apoptosis, and suppression of cell migration, invasion and tube formation. Moreover, intravenous administration of DW22 significantly retarded tumor growth of A549 and MDA-MB-435 xenograft mice models, and induced no substantial weight loss and gross toxicity. In addition, DW22 also reduced cell proliferation, angiogenesis, and induced cell apoptosis in vivo. Collectively, our data demonstrates that dual targeting of RXR and HDAC using DW22 possesses pleiotropic antitumor activities both in vitro and in vivo, providing a novel therapeutic approach for cancer treatment.