Protein kinase c-β-dependent activation of NF-κB in stromal cells is indispensable for the survival of chronic lymphocytic leukemia B cells in vivo

Tumor cell survival critically depends on heterotypic communication with benign cells in the microenvironrnent. Here, we describe a survival signaling pathway activated in stromal cells by contact to B cells from patients with chronic lymphocytic leukemia (CLL). The expression of protein kinase C (PKC)-beta II and the subsequent activation of NF-kappa B in bone marrow stromal cells are prerequisites to support the survival of malignant B cells. PKC-beta knockout mice are insusceptible to CLL transplantations, underscoring the in vivo significance of the PKC-beta II-NF-kappa B signaling pathway in the tumor microenvironment. Upregulated stromal PKG-beta II in biopsies from patients with CLL, acute lymphoblastic leukemia, and mantle cell lymphoma suggests that this pathway may commonly be activated in a variety of hematological malignancies