Targeting c-Jun is a potential therapy of luminal breast cancer bone metastasis

Luminal breast cancer has the highest bone metastasis frequency among all breast cancer subtypes, but its metastatic mechanism has not been elucidated because of the lack of appropriate metastatic cell lines. The study aim was to characterize high-osteolytic bone metastatic MCF7-BM cell lines and extract c-Jun, a novel bone metastasis marker. We found that c-Jun was upregulated in MCF7-BM cells, and its deficiency was associated with suppression of the cell migration, transformation, and stemness of BM cells. In vivo, c-Jun-deficient MCF7-TAM67 cells exhibited weaker bone metastatic ability. Additionally, c-Jun overexpression in MCF7-BM cells led to a tumor-migration promotion cycle in the bone microenvironment possibly by enhancing calcium-induced migration and releasing the osteoclast activator BMP5. Inhibition of c-Jun by JNK-IN-8, a JNK inhibitor, effectively reduced tumorigenesis activities and bone metastatic tumors. Our results indicate the potential benefits of a therapy that targets c-Jun to prevent or minimize luminal breast cancer bone metastasis.