Toll-Like Receptors in Human Multiple Myeloma: New Insight into Inflammation-Related Pathogenesis
Multiple myeloma (MM) is a clonal neoplasm characterized by expansion of malignant plasma cells
in the bone marrow causing various complications including osteolytic lesions and impaired immune function. It
has recently been reported that human myeloma cells express multiple Toll-like receptors (TLRs), and their
activation-induced functional responses show heterogeneity among cell lines and patient samples. TLRs are
critical germ-line encoded molecules expressed in immune cells as well as in a variety of cancer cells. In
multiple myeloma, they may induce cell growth and proliferation or promote cell death. In fact, our current
knowledge of Toll-like receptor function has gone beyond their main function as triggers of innate and adaptive
immune responses. Considering the essential role of bone marrow microenvironment components in myeloma
tumor expansion, survival, invasion and drug resistance, TLR triggering may contribute to adhesion-induced or
de novo drug resistance of MM cells. Future preclinical and clinical studies are needed to address if TLRs can
be exploited as novel therapeutic targets for MM.
Keywords: Bone marrow, drug resistance, inflammation, multiple myeloma, toll like receptors.
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