Chloroquine inhibits tumor growth and angiogenesis in malignant pleural effusion.

Malignant pleural effusion (MPE) is associated with a poor prognosis in lung cancer. Currently, no effective cure exists for MPE. Chloroquine (CQ) has been demonstrated to induce vascular normalization and inhibit tumor growth. The aim of this study was to assess whether CQ affects MPE. The xenografts mice were divided into normal saline (NS), CQ, or bevacizumab (BE) group. Tumor growth and microvascular density (MVD) were monitored. We explored the effect of CQ on the proliferation, survival, and proangiogenic signaling of tumor cells in vitro. We further evaluated the effects of CQ on the viability, migration, and tube formation of human umbilical vein endothelial cells (HUVECs). A chicken chorioallantoic membrane (CAM) model was used to elucidate the effects of CQ on angiogenesis. Finally, an MPE mouse model were treated by CQ, BE, or NS. The volume of pleural effusion, tumor foci, and MVD was evaluated. CQ therapy group exhibited decreased tumor volume, tumor weight, and MVD in the mouse xenografts. CQ inhibited the proliferation of the tumor cells. However, the expression of vascular endothelial growth factor was not affected. Additionally, CQ inhibited the proliferation, migration, and tube formation of HUVECs and also restrained angiogenesis in the CAM. Western blot showed that CQ might suppress angiogenesis by downregulating p-Akt, Jagged1, and Ang2 in HUVECs. In MPE mice, the volume of the pleural effusion, the number of pleural tumor foci, and the MVD were significantly reduced in the CQ group. Our work demonstrated that CQ played the role of an efficient treatment for MPE.