Wnt5a induces ROR1 dependent NF-κB activation to enhance MMP-9 expression and invasiveness in chronic lymphocytic leukemia

Matrix metalloproteinase-9 (MMP-9) facilitates the extravasation and lymphoid-tissue infiltration of chronic lymphocytic leukemia (CLL) cells. Prior studies found that high level expression of MMP-9 in CLL associates more aggressive disease. We find that circulating CLL cells that express high levels the onco-embryonic protein ROR1 express significantly higher levels of MMP-9. Stimulation of CLL cells with Wnt5a could enhance expression and the release of MMP-9 into the culture media and increase the capacity of CLL cells to invade Matrigel in a Boyden-Chamber Assay. Such effects of Wnt5a could not be inhibited by BTK inhibitors such as ibrutinib or zanubrutinib, but could be blocked by zilovertamab, a humanized mAb specific for ROR1. We found that siRNA silencing of NF-κB-p65 or use of an NF-κB inhibitor (CAS 545380-34-5) blocked the capacity of Wnt5a to induce MMP-9 or enhance the invasive capacity of treated CLL cells. Moreover, siRNA directed silencing of MMP9 or treatment with an MMP-9 inhibitor (CAS 1177749-58-4) also blocked the invasive capability of CLL cells induced by Wnt5a. We conclude that Wnt5a-induced ROR1-signaling can induce expression of MMP-9 on CLL cells through activation of NF-κB, thereby enhancing the extravasation and lymphoid-tissue infiltration required for CLL cell trafficking.