Stat1 and Stat3 in hepatocellular carcinomas and colorectal cancers

Stat3 is considered to act oncogenic in most (if not all) tumors. Three important tumor-promoting functions have been attributed to Stat3-signaling: i) a cell-autonomous activity of Stat3 that promotes cell survival and proliferation; ii) a non-cell-autonomous activity of Stat3 that regulates the composition of the tumor microenvironment; iii) a function of Stat3 in tumor invasiveness and metastasis. Moreover, Stat1 and Stat3 have been considered as molecular links between inflammation and cancer development which is currently investigated. In particular, human cancers such as hepatocellular carcinoma (HCC) and colorectal cancer (CRC) are promoted by inflammatory conditions. We are currently employing mice with conditional inactivation of Stat3 to identify functions in liver- and intestinal tumors (for reference see: Musteanu et al., Gastroenterology 2011).