β1-integrin: A potential therapeutic target in the battle against cancer recurrence

Primary cancer treatment, involving both local and often systemic adjuvant therapy, is often successful, especially if the cancer is detected at an early stage of progression. However, for some patients, the cancer may recur either locally or as distant metastases, in some cases many years after apparently successful primary treatment. Significant tumor dormancy has been documented in several cancers, such as breast, melanoma, and renal cancer. Tumor dormancy has long been recognized as an important problem in management of cancer patients. Recent work has clarified biologic aspects of tumor dormancy and has shown that dormant tumor cells may be resistant to cytotoxic chemotherapy and radiation. This work has led to recognition of a key role for β1-integrin in regulating the switch from a dormant state to active proliferation and metastasis. Here we discuss the role of β1-integrin and its signaling partners in regulating the dormant phenotype. We also consider possible therapeutic approaches, such as small molecules or antibodies (ATN-161, volociximab, and JSM6427), directed against β1-integrin signaling to target dormant cancer cells and to prevent metastatic recurrence.