Clinical significance of Src expression and activity in human neoplasia

Src, a 60 kDa non-receptor tyrosine kinase, is the product of normal c-src of the human genome and member of the Src protein tyrosine kinases family (SFK). As described by Martin and Rous, a genetic recombination between c-src and the RSV oncogene of Rous sarcoma virus results in a modified Src protein, with increased intrinsic activity and transforming potential in animal and human tissues. Several in vitro and in vivo studies supported this theory providing insight in the signalling pathways involved. Accumulating evidence from studies on clinical samples supported the role of Src in the process of carcinogenesis and disease progression in several human malignancies. Some studies have further reinforced the significance of the kinase in malignacy by correlating its expression and/or activity with important clinicopathological parameters, such as tumour stage, histopathological grade, proliferative capacity and most importantly patient's survival. This review is a comprehensive report of the published evidence on the expression and clinical significance of Src in human malignancy, which constitutes the background of the current studies and clinical trials on the use of Src inhibitors as novel potent antineoplastic strategy.