Chemokines in Homeostasis and Cancers

Chemokines are a small group of related chemoattractant peptides that play an essential role in the development and homeostatic maintenance of the immune system. They control the recruitment of cells needed for the induction and activation of innate and adaptive immune responses. Stromal cell-derived factor 1(SDF-1) and its receptor (CXCR4) have role in regulation of trafficking of normal hematopoietic stem cells (HSCs) in their homing/ retention in bone marrow, also they control lymphocyte trafficking, angiogenesis, cell adherent or migration. In addition, chemokines and their receptors involved in several auto- immune diseases such as inflammation, HIV. In fact, chemokines are involved directly or indirectly in almost every aspect of tumorigenesis. They mediate survival and metastatic spread of tumors, promote new blood vessel formation (neovascularization). SDF- 1/ CXCR4 axis for migration, enhanced resistance to apoptosis and an increased capacity for drug resistance. .A number of therapeutic strategies have been proposed to target almost every step of the chemokine or chemokine receptor involvement in tumors. Yet, despite occasional success stories, most of them appear to be ineffective or impractical,. The strategy would only be effective if it also promoted antitumor activity and more study is needed to clear the tumor relapse mechanism.