Antitumor Immunity Is Controlled by Tetraspanin Proteins

Anti-tumor immunity is shaped by the different types of immune cells that are present in the tumor microenvironment. In particular, environmental signals (for instance soluble factors or cell-cell contact) transmitted through the plasma membrane determine whether immune cells are activated or inhibited. Tetraspanin proteins are emerging as central building blocks of the plasma membrane by their capacity to cluster immune receptors, enzymes and signaling molecules into the tetraspanin web. Whereas some tetraspanins (CD81, CD151, CD9) are widely and broadly expressed, others (CD53, CD37, Tssc6) have an expression pattern restricted to hematopoietic cells. Studies using genetic mouse models have identified important immunological functions of these tetraspanins on different leukocyte subsets, and as such may be involved in the immune response against tumors. While multiple studies have been performed with regards to deciphering the function of tetraspanins on cancer cells, the effect of tetraspanins on immune cells in the anti-tumor response remains understudied. In this review we will focus on tetraspanins expressed by immune cells and discuss their potential role in anti-tumor immunity. New insights in tetraspanin function in the tumor microenvironment and possible prognostic and therapeutic roles of tetraspanins will be discussed.