Abstract 2732: NLRP12 suppresses colorectal cancer progression and invasion via downregulation of the Wnt/b-catenin pathway

Metastatic CRC is associated with increased mortality, underscoring the importance of understanding the molecular mechanism of CRC invasion and metastasis. We recently demonstrated that mice deficient in NLRP12, an innate immune sensor, are susceptible to CRC with increased incidence of invasive adenocarcinoma. Here, we investigated the molecular mechanism of NLRP12-mediated suppression of cancer progression and invasion using mouse models and in vitro biochemical studies. Nlrp12−/− mice treated with azoxymethane plus dextran sodium sulfate developed higher tumor burden and invasive adenocarcinoma compared to WT mice. RNA-seq analysis showed significantly higher levels of protooncogenes, matrix metalloproteinases (Mmp 3, 7,8, 10, 12), and epithelial to mesenchymal transition (EMT) markers (Vim, Fn1, Foxc2, Zeb2, Ezh2) in Nlrp12−/− tumors. To understand the underlying mechanism of increased expression of cancer promoting genes in Nlrp12−/− tumors, we analyzed activation of various cell signaling pathways. To our surprise, there was no major difference in the activation NF-κB, ERK, JNK, and STAT3, which have previously been shown to be downregulated by NLRP12, between WT and Nlrp12−/- tumors. However, we observed strikingly higher levels of β-catenin and expression of Wnt target genes (Ctnnb1, Axin2, Yap1, Tcf3, Lgr5, etc.) in Nlrp12−/− tumors. Consistently, deletion of NLRP12 in APCmin/+ mice led to higher polyp development and activation of the Wnt/β-catenin pathway. Notably, hyperactivation of the Wnt/β-catenin pathway is a hallmark of CRC and about 80% of CRC patients carry mutations in the Wnt/β-catenin pathway. To further explore the link between NLRP12 and the Wnt/β-catenin pathway, we overexpressed NLRP12 in HEK293T cells and CRC cell line MC38. NLRP12-overexpressed cells showed reduced activation of β-catenin and expression of Wnt target genes following stimulation with Wnt3a. An opposite result was observed when NLRP12 was knocked out from these cell lines. Consistently, Nlrp12-KO MC38 cells exhibited increased proliferation, colony formation, and migration. These data for the first time demonstrate that NLRP12 is an intrinsic negative regulator of the Wnt/β-catenin pathway. Overall, these findings reveal a novel CRC suppression pathway involving NLRP12 and suggest that the NLRP12/β-catenin signaling axis could be therapeutically targeted for the treatment of CRC invasion and metastasis. Citation Format: Shahanshah Khan, Hasan Zaki. NLRP12 suppresses colorectal cancer progression and invasion via downregulation of the Wnt/b-catenin pathway [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2732.