A genome-wide screen in mice to identify cell-extrinsic regulators of pulmonary metastatic colonisation

Abstract

Metastatic colonisation, whereby a disseminated tumour cell is able to survive and proliferate at a secondary site, involves both tumour cell-intrinsic and -extrinsic factors. To identify tumour cell-extrinsic (microenvironmental) factors that regulate the ability of metastatic tumour cells to effectively colonise a tissue, we performed a genome-wide screen utilising the experimental metastasis assay on mutant mice. Mutant and wildtype (control) mice were tail vein-dosed with murine metastatic melanoma B16-F10 cells and 10 days later the number of pulmonary metastatic colonies were counted. Of the 1,300 genes/genetic locations (1,344 alleles) assessed in the screen 34 genes were determined to significantly regulate pulmonary metastatic colonisation (15 increased and 19 decreased; P<0.005 and genotype effect <-60 or >+60). Whilst several of these genes have known roles in immune system regulation (Bach2, Cyba, Cybb, Cybc1, Id2, Igh-6, Irf1, Irf7, Ncf1, Ncf2, Ncf4 and Pik3cg) most are involved in a disparate range of biological processes, ranging from ubiquitination (Herc1) to diphthamide synthesis (Dph6) to Rho GTPase-activation (Arhgap30 and Fgd4), with no previous reports of a role in the regulation of metastasis. Thus, we have identified numerous novel regulators of pulmonary metastatic colonisation, which may represent potential therapeutic targets.