Autotaxin (ATX) as a Marker for Breast Cancer

Breast cancer is the most common malignancy in females in Egypt. It accounts for 32 % of cancer in women . Breast cancer in Egypt carries an unfavorable prognosis with 29% mortality and 3.7:1 incidence to mortality ratio . Despite the rising incidence of breast cancer, the survival rates have improved in recent years due to the deep research in biological behavior of breast cancer . Although the current 5-year survival for primary breast cancer is relatively high (ranging from 80% to 92% in different populations) survival rates decrease to less than 25% when the disease becomes metastatic .These data support the need to develop more efficient strategies for preventive, intervention, evaluation of therapy, and prediction of prognosis . Autotaxin (ATX) is a glycoprotein encoded by the ENPP2 (Ectonucleotide Pyrophosphatase/Phosphodiesterase 2) gene located on chromosome 8. Identical to lysophospholipase D, ATX plays a role in the synthesis of the bioactive lipid mediator lysophosphatidate (LPA) from lysophosphatidylcholine (LPC) . LPA acts through specific G protein-coupled receptors (GPCRs) to promote cellular proliferation, migration, and survival . ATX expression was also reported higher in poorly differentiated tumors and, in independent studies, is correlated with invasiveness of cancer cells suggesting a higher metastatic potential of ATX-expressing tumors . ATX is generated from platelets, endothelial cells, fibroblasts, and adipocytes and specifically, ATX from adipocytes has an impact on plasma LPA level . Thus, adipocytes could be an important origin of ATX in tumors. Breast cancer is a human cancer that has adipocyte-rich stroma. Adipose tissue comprises 56% of non-lactating breast tissue, and 35% of lactating breast tissue . ATX-LPA signaling has been reported to be involved in angiogenesis, tumor cell invasion, and migration in breast cancer . Increased ATX expression has also been reported in various forms of cancer, such as glioblastoma, hepatocellular and thyroid carcinomas, pancreatic and hematological cancers. A large number of evidence indicate that ATX-LPA is associated with chemotherapy resistance of cancer, and in breast cancer, ATX can reverse cell apoptosis. In a mouse model, α-bromomethylene phosphonate LPA (BrP-LPA), a dual ATX and pan-LPAR( Lysophosphatidic acid receptor ) inhibitor, inhibited migration and invasion of breast cancer cell lines and suppressed primary tumor and angiogenesis in a mouse xenograft study . Since tumor and stromal cells in breast cancer express ATX-LPA signaling-related proteins, inhibition of the ATX-LPA axis could be of therapeutic importance .Therefore, further study ATX as a tumor marker in breast cancer is required.