The role of interleukin-2 receptor alpha in cancer.

Interleukin-2 (IL-2) is the major growth factor for activated T-lymphocytes and stimulates clonal expansion and maturation of these lymphocytes. IL-2 binds to its receptor complex, IL-2Ralpha, beta, and gamma chains, and exerts its effect via second messengers, mainly tyrosine kinases, which ultimately stimulate gene expression. The heterotrimerization of the receptor chains leads to high affinity binding for IL-2. The functional importance of IL-2Ralpha in hematopoietic cell systems is well known. However, the potential role that IL-2Ralpha plays in tumorigenesis is still not fully elucidated. Il-2Ralpha expression has been found in many types of cancers, including leukemia, lymphoma, lung, breast, head-and-neck and prostate. Recent evidence shows that high expression of IL-2Ralpha in tumors correlates with a poor prognosis for the patient. This review details the current known functions of IL-2Ralpha in cancer cells and some of the therapies used to combat IL-2Ralpha-mediated cell signaling.