Vimentin is an intermediate filament protein, with a key role in the epithelial to mesenchymal transition as well as cell invasion, and it is often upregulated during cancer progression. However, relatively little is known about its regulation in cancer cells. Here, we performed an RNA interference screen followed by protein lysate microarray analysis in bone metastatic MDA-MB-231(SA) breast cancer cells to identify novel regulators of vimentin expression. Out of the 596 genes investigated, three novel vimentin regulators EPHB4, WIPF2 and MTHFD2 were identified. The reduced vimentin expression in response to EPHB4, WIPF2 and MTHFD2 silencing was observed at mRNA and protein levels. Bioinformatic analysis of gene expression data across cancers indicated overexpression of EPHB4 and MTHFD2 in breast cancer and high expression associated with poor clinical characteristics. Analysis of 96 cDNA samples derived from both normal and malignant human tissues suggested putative association with metastatic disease. MTHFD2 knockdown resulted in impaired cell migration and invasion into extracellular matrix as well as decreased the fraction of cells with a high CD44 expression, a marker of cancer stem cells. Furthermore, MTHFD2 expression was induced in response to TGF-β stimulation in breast cancer cells. Our results show that MTHFD2 is overexpressed in breast cancer, associates with poor clinical characteristics and promotes cellular features connected with metastatic disease, thus implicating MTHFD2 as a potential drug target to block breast cancer cell migration and invasion.

Purpose: As foremost regulators of cancer-related inflammation and immunotherapeutic resistance, tumor-associated macrophages have garnered major interest as immunotherapeutic drug targets. However, depletory strategies have yielded little benefit in clinical studies to date. An alternative approach is to exploit macrophage plasticity and "reeducate" tumorigenic macrophages toward an immunostimulatory phenotype to activate the host's antitumor immunity.Experimental Design: We investigated the role of the macrophage scavenger receptor common lymphatic endothelial and vascular endothelial receptor-1 (Clever-1) on tumor growth in multiple mouse cancer models with inflammatory and noninflammatory characteristics by using conditional knockouts, bone marrow chimeras, and cell depletion experiments. In addition, the efficacy of immunotherapeutic Clever-1 blockade as monotherapy or in combination with anti-PD-1 was tested.Results: Genetic deficiency of macrophage Clever-1 markedly impaired solid tumor growth. This effect was mediated by macrophages that became immunostimulatory in the absence of Clever-1, skewing the suppressive tumor microenvironment toward inflammation and activating endogenous antitumor CD8 þ T cells. Comparable effects were achieved with immunotherapeutic blockade of Clever-1. Notably, these effects were similar to those achieved by PD-1 checkpoint inhibition. Moreover, combining anti-Clever-1 with anti-PD-1 provided synergistic benefit in aggressive, nonresponsive tumors.Conclusions: These findings demonstrate the importance of macrophages in mediating antitumor immune responses and support the clinical evaluation of immunotherapeutic Clever-1 blockade as a novel cancer treatment strategy.

Early regulators of disease may increase understanding disease mechanisms, and serve as markers for pre-symptomatic diagnosis and treatment. However, early regulators are difficult to identify because patients generally present after they are symptomatic. We hypothesized that early regulators of T-cell associated diseases could be found by identifying upstream transcription factors (TFs) in T-cell differentiation, and by prioritizing hub TFs that were enriched for disease associated This analytical strategy to identify early regulators of disease by combining gene regulatory networks with GWAS may be generally applicable for functional and clinical studies of early disease development.