Targeting c-MET/HGF signaling pathway in upper gastrointestinal cancers: rationale and progress

Aberrant activation of receptor-tyrosine kinase c-Met/HGF pathway is shown to be associated with cell proliferation, invasion, metastasis and poor-prognosis in several tumor types, including upper gastrointestinal-malignancies. The interaction of c-Met with multiple signalling-pathways involved in tumorigenic-properties and invasive-phenotype has gained substantial attention, suggesting its role as an intriguing-target for cancer-therapy. In recent years, there have been considerable efforts in the development of effective c-Met inhibitors with potential clinical-applications and one of them, crizotinib (dual c-Met/ALK inhibitor), has recently been approved for lung-cancers with ALKrearrangement. However several important questions remain to be answered on the molecular mechanisms underlying the antitumor effects of crizotinib, as well as on its possible role in the treatment of different tumor types, including uppergastrointestinal- cancers. The aim of this review is to give an overview on critical role of the c-Met/HGF pathway in cancer, and the preclinical/clinical studies on c-Met inhibitors. There are accumulating evidences on therapeutic potential of c-Met inhibitors for the treatment of other malignancies, such as gastric and pancreatic cancers. However, further investigations are needed to identify determinants of the activity of c-Met inhibitors, through the analysis of genetic/ environmental alterations affecting c-Met and parallel pro-cancer pathways; mechanisms result in developing resistance to anti-c-Met agents; and selection of patients that might benefit from therapy. These studies will be essential to improve the selectivity/efficacy of future anticancer strategies of c-Met targeted-therapies in the treatment of upper gastrointestinal- cancers.