CD49d and CD49e induce cell adhesion-mediated drug resistance through the nuclear factor-κB pathway in Burkitt lymphoma.

Burkitt lymphoma (BL) is a highly aggressive form of non-Hodgkin's B-cell lymphoma. Currently, multi-agent chemotherapy regimens are being used to significantly improve cure rates and achieve complete remissions in BL patients. However, drug resistance can often occur within 6 months in BL patients, contributing to poor prognosis. Mounting evidence suggests that cell adhesion-mediated drug resistance (CAM-DR), caused by the interaction between the bone marrow microenvironment and tumour cells may play an important role in drug resistance to chemotherapy. However, the molecular mechanism underlying CAM-DR in BL has not been identified yet. In this study, we investigated the molecular mechanism responsible for CAM-DR in BL cells. We also examined the therapeutic targets of CAM-DR in BL cells and found CD49d and CD49e to be the important adhesion molecules involved. However, CD49a, CD49b, CD11a, CD29, CD18, and CD61 were not found to be associated with CAM-DR in BL cells. Furthermore, we clarified that CD49d- and CD49e-mediated CAM-DR could be attributed to an increase in the expression of B cell leukemia-xL (Bcl-xL) and survivin proteins, and a decrease in the expression of Bcl-2 associated X (Bax), Bcl-2 interacting mediator (Bim) and p53 upregulated modulator of apoptosis (PUMA) proteins via nuclear factor kappaB (NF-κB) activation. In addition, bortezomib was found to overcome CAM-DR in BL cells by inhibiting NF-κB. Thus, bortezomib may have potential clinical applications in the treatment of CD49d- and CD49e-mediated CAM-DR in BL patients.