Dendritic cells activated by IFN-γ/STAT1 express IL-31 receptor and release proinflammatory mediators upon IL-31 treatment.

IL-31 is a T cell-derived cytokine that signals via a heterodimeric receptor composed of IL-31Rα and oncostatin M receptor ß. Although several studies have aimed to investigate IL-31-mediated effects, the biological functions of this cytokine are currently not well understood. IL-31 expression correlates with the expression of IL-4 and IL-13 and is associated with atopic dermatitis in humans, indicating that IL-31 is involved in Th2-mediated skin inflammation. Because dendritic cells are the main activators of Th cell responses, we posed the question of whether dendritic cells express the IL-31R complex and govern immune responses triggered by IL-31. In the current study, we report that primary human CD1c(+) as well as monocyte-derived dendritic cells significantly upregulate the IL-31Rα receptor chain upon stimulation with IFN-γ. EMSAs, chromatin immunoprecipitation assays, and small interfering RNA-based silencing assays revealed that STAT1 is the main transcription factor involved in IFN-γ-dependent IL-31Rα expression. Subsequent IL-31 stimulation resulted in a dose-dependent release of proinflammatory mediators, including TNF-α, IL-6, CXCL8, CCL2, CCL5, and CCL22. Because these cytokines are crucially involved in skin inflammation, we hypothesize that IL-31-specific activation of dendritic cells may be part of a positive feedback loop driving the progression of inflammatory skin diseases.

PBX3 Is Part of an EMT Regulatory Network and Indicates Poor Outcome in Colorectal Cancer.

Purpose: Colorectal cancers are composed of phenotypically different tumor cell subpopulations within the same core genetic background. Here, we identify high expression of the TALE transcription factor PBX3 in tumor cells undergoing epithelial-mesenchymal transition (EMT), analyze PBX3 regulation, and determine clinical associations in colorectal cancer.Experimental design: We used transcriptomic and in situ analyses to identify PBX3 expression in colorectal cancer and cell biology approaches to determine its regulation and function. Clinical associations were analyzed in independent tissue collections and gene expression datasets of colorectal cancers with recorded follow-up data.Results: PBX3 was expressed in tumor cells with high WNT activity undergoing EMT at the leading tumor edge of colorectal cancers, whereas stromal cells were PBX3 negative. PBX3 expression was induced by WNT activation and by the EMT transcription factors SNAIL and ZEB1, whereas these effects were mediated indirectly through microRNA miR-200. PBX3 was required for a full EMT phenotype in colon cancer cells. On the protein level, PBX3 expression indicated poor cancer-specific and disease-free survival in a cohort of 244 UICC stage II colorectal cancers, and was associated with metastasis in a case-control collection consisting of 90 cases with or without distant metastasis. On the mRNA level, high PBX3 expression was strongly linked to poor disease-free survival.Conclusions: PBX3 is a novel indicator of EMT in colorectal cancer, part of an EMT regulatory network, and a promising prognostic predictor that may aid in therapeutic decision making for patients with colorectal cancer. Clin Cancer Res; 24(8); 1974-86. ©2018 AACR.

Targeting tumor cell plasticity by combined inhibition of NOTCH and MAPK signaling in colon cancer.

In colorectal cancer, signaling pathways driving tumor progression are promising targets for systemic therapy. Besides WNT and MAPK signaling, activation of NOTCH signaling is found in most tumors. Here, we demonstrate that high NOTCH activity marks a distinct colon cancer cell subpopulation with low levels of WNT and MAPK activity and with a pronounced epithelial phenotype. Therapeutic targeting of MAPK signaling had limited effects on tumor growth and caused expansion of tumor cells with high NOTCH activity, whereas upon targeting NOTCH signaling, tumor cells with high MAPK activity prevailed. Lineage-tracing experiments indicated high plasticity between both tumor cell subpopulations as a mechanism for treatment resistance. Combined targeting of NOTCH and MAPK had superior therapeutic effects on colon cancer growth in vivo. These data demonstrate that tumor cells may evade systemic therapy through tumor cell plasticity and provide a new rationale for simultaneous targeting of different colon cancer cell subpopulations.

Oncogenic Effects of High MAPK Activity in Colorectal Cancer Mark Progenitor Cells and Persist Irrespective of RAS Mutations.

About 40% of colorectal cancers have mutations in KRAS accompanied by downstream activation of MAPK signaling, which promotes tumor invasion and progression. Here, we report that MAPK signaling shows strong intratumoral heterogeneity and unexpectedly remains regulated in colorectal cancer irrespective of KRAS mutation status. Using primary colorectal cancer tissues, xenograft models, and MAPK reporter constructs, we showed that tumor cells with high MAPK activity resided specifically at the leading tumor edge, ceased to proliferate, underwent epithelial-mesenchymal transition (EMT), and expressed markers related to colon cancer stem cells. In KRAS-mutant colon cancer, regulation of MAPK signaling was preserved through remaining wild-type RAS isoforms. Moreover, using a lineage tracing strategy, we provide evidence that high MAPK activity marked a progenitor cell compartment of growth-fueling colon cancer cells in vivo Our results imply that differential MAPK signaling balances EMT, cancer stem cell potential, and tumor growth in colorectal cancer. Cancer Res; 77(7); 1763-74. ©2017 AACR.

Multicolor lineage tracing reveals clonal architecture and dynamics in colon cancer.

Colon cancers are composed of phenotypically heterogeneous tumor cell subpopulations with variable expression of putative stem cell and differentiation antigens. While in normal colonic mucosa, clonal repopulation occurs along differentiation gradients from crypt base toward crypt apex, the clonal architecture of colon cancer and the relevance of tumor cell subpopulations for clonal outgrowth are poorly understood. Using a multicolor lineage tracing approach in colon cancer xenografts that reflect primary colon cancer architecture, we here demonstrate that clonal outgrowth is mainly driven by tumor cells located at the leading tumor edge with clonal axis formation toward the tumor center. While our findings are compatible with lineage outgrowth in a cancer stem cell model, they suggest that in colorectal cancer tumor cell position may be more important for clonal outgrowth than tumor cell phenotype.

ADNP Is a Therapeutically Inducible Repressor of WNT Signaling in Colorectal Cancer.

Purpose: Constitutively active WNT signaling is a hallmark of colorectal cancers and a driver of malignant tumor progression. Therapeutic targeting of WNT signaling is difficult due to high pathway complexity and its role in tissue homeostasis. Here, we identify the transcription factor ADNP as a pharmacologically inducible repressor of WNT signaling in colon cancer.Experimental Design: We used transcriptomic, proteomic, and in situ analyses to identify ADNP expression in colorectal cancer and cell biology approaches to determine its function. We induced ADNP expression in colon cancer xenografts by low-dose ketamine in vivo Clinical associations were determined in a cohort of 221 human colorectal cancer cases.Results: ADNP was overexpressed in colon cancer cells with high WNT activity, where it acted as a WNT repressor. Silencing ADNP expression increased migration, invasion, and proliferation of colon cancer cells and accelerated tumor growth in xenografts in vivo Treatment with subnarcotic doses of ketamine induced ADNP expression, significantly inhibited tumor growth, and prolonged survival of tumor-bearing animals. In human patients with colon cancer, high ADNP expression was linked to good prognosis.Conclusions: Our findings indicate that ADNP is a tumor suppressor and promising prognostic marker, and that ketamine treatment with ADNP induction is a potential therapeutic approach that may add benefit to current treatment protocols for patients with colorectal cancer. Clin Cancer Res; 23(11); 2769-80. ©2016 AACR.

CYB5R1 links epithelial-mesenchymal transition and poor prognosis in colorectal cancer.

Colorectal cancers show significant tumor cell heterogeneity within the same core genetic background. Epithelial-mesenchymal transition (EMT) is an important functional aspect of this heterogeneity and hallmark of colorectal cancer progression. Here, we identify CYB5R1, an enzyme involved in oxidative stress protection and drug metabolism, as an indicator of EMT in colon cancer. We demonstrate high CYB5R1 expression in colorectal cancer cells undergoing EMT at the infiltrative tumor edge and reveal an extraordinarily strong association of CYB5R1 expression with two core EMT gene expression signatures in a large independent colon cancer data set from The Cancer Genome Atlas (TCGA). Furthermore, we demonstrate that CYB5R1 is required for an infiltrative tumor cell phenotype, and robustly linked with poor prognosis in colorectal cancer. Our findings have important implications for colon cancer cells undergoing EMT and may be exploited for diagnostic and therapeutic purposes.