Silencing of CKIP-1 promotes tumor proliferation and cell adhesion-mediated drug resistance via regulating AKT activity in non-Hodgkin's lymphoma.

Casein kinase 2 interacting protein-1 (CKIP-1; also known as PLEKHO1) is involved in regulating many processes such as cell proliferation, differentiation and apoptosis. CKIP-1 also plays an important role in many types of cancer, such as colon, breast cancer and human osteosarcoma. In the present study, we found that CKIP-1 was reversely associated with the proliferation of non-Hodgkin's lymphoma (NHL) and cell adhesion mediated drug resistance (CAM-DR). We demonstrated that knockdown of CKIP-1 promoted the proliferation of NHL cells through interacting with Akt and suppressing Akt phosphorylation. In addition, adhesion of lymphoma cells to fibronectin or stroma cells (HS-5 cells) decreased CKIP-1 expression, which led to the upregulation of Akt phosphorylation. Importantly, we showed that the phosphorylation of Akt was correlated with CAM-DR phenotype in NHL cells. Taken together, the present study shed new light on the molecular mechanism of CAM-DR in NHL and targeting CKIP-1 may be a novel therapeutic target for NHL.