The Innate Immune Receptor NLRX1 Functions as a Tumor Suppressor by Reducing Colon Tumorigenesis and Key Tumor-Promoting Signals
2016
A. Alicia Koblansky | Agnieszka D. Truax | Rongrong Liu | Stephanie A. Montgomery | Shengli Ding | Justin E. Wilson | W. June Brickey | Marcus Mühlbauer | Rita-Marie T. McFadden | Peizhen Hu | Zengshan Li | Christian Jobin | Pauline Kay Lund | Jenny P.-Y. Ting
NOD-like receptor (NLR) proteins are intracellular innate immune sensors/receptors that regulate immunity. This work shows that NLRX1 serves as a tumor suppressor in colitis-associated cancer (CAC) and sporadic colon cancer by keeping key tumor promoting pathways in check. Nlrx1−/− mice were highly susceptible to CAC, showing increases in key cancer-promoting pathways including nuclear factor κB (NF-κB), mitogen-activated protein kinase (MAPK), signal transducer and activator of transcription 3 (STAT3), and interleukin 6 (IL-6). The tumor-suppressive function of NLRX1 originated primarily from the non-hematopoietic compartment. This prompted an analysis of NLRX1 function in the Apcmin/+ genetic model of sporadic gastrointestinal cancer. NLRX1 attenuated Apcmin/+ colon tumorigenesis, cellular proliferation, NF-κB, MAPK, STAT3 activation, and IL-6 levels. Application of anti-interleukin 6 receptor (IL6R) antibody therapy reduced tumor burden, increased survival, and reduced STAT3 activation in Nlrx1−/−Apcmin/+ mice. As an important clinical correlate, human colon cancer samples expressed lower levels of NLRX1 than healthy controls in multiple patient cohorts. These data implicate anti-IL6R as a potential personalized therapy for colon cancers with reduced NLRX1.
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