CD138, is a type I integral membrane proteoglycan that contains both chondroitin sulfate and heparan sulfate groups. CD138 is a specific marker for plasmacytic differentiation in hematologic disorders. This cell surface proteoglycan is also expressed in normal epithelial cells and tissues as well as various types of cancer tissues. The extracellular shed form of CD138 remains soluble or accumulates in the extracellular matrix where it binds growth factors, cytokines and other extracellular matrix proteins. This binding activates signaling of bound growth factors or cytokines, which results in enhanced tumor growth, dissemination, angiogenesis, and osteolysis.
