ERK1/2 controlled genes ANGPT2 and CXCR4 mediate liver metastasis from colon cancer

Carcinoma development in colorectal cancer (CRC) is driven by genetic alterations in numerous signaling pathways. Alterations in the RAS-ERK1/2 pathway are associated with the shortest overall survival for patients after diagnosis of CRC metastatic disease, but how RAS-ERK signaling regulates CRC metastasis is still unknown. An unbiased screening approach based on selection of highly liver metastatic CRC cells in vivo was used to determine genes associated with metastasis and a ERK1/2-controlled metastatic gene set (EMGS) defined. The ANGPT2 and CXCR4, two genes within the gene set, were subjected to gain and loss of function validation in CRC cells (SW620, SW480, Colo26, HCT116), its downstream mechanism validated, and tested in clinical samples. Here, we identified an EMGS that is associated with increased recurrence and reduced survival for patients with CRC tumors. Higher levels of EMGS expression were detected in the CRC subsets Consensus Molecular Subtype (CMS)1 and CMS4. We show that the RAS-ERK1/2 axis controls the expression of the cytokine ANGPT2 and the cytokine receptor CXCR4 in CRC cells, and that this facilitates the development of liver but not lung metastases, suggesting that ANGPT2 and CXCR4 are essential for metastatic outgrowth in the liver. We also show that CXCR4 also controls the expression of the cytokines IL10 and CXCL1, and provide evidence for a causal role of IL10 in supporting liver colonization. In summary, we demonstrate that amplification of ERK1/2 signaling in KRAS-mutated CRC cells affects the cytokine milieu of the tumors, thus possibly affecting tumor?stroma interactions and favoring liver metastasis formation. In total 9 samples were analysed, 4 replicates of SW620_Parental cell line, 4 replicates of SW620_LiM2 cell line and 1 replicate of SW620_LiM2 treated with 10uM U0126 inhibitor. Out of them, 7 correspond to reanalyses of samples from the GSE33350 series: GSM824901, GSM824898, GSM824899 and GSM824900 (SW620_Parental cell line); GSM824902, GSM824903 and GSM824904 (untreated SW620_LiM2 cell line). These samples were re-processed together with the rest of cel files as described in the protocols section.