Abstract 2798: Oral fungal infection tweaks the innate immune tumor microenvironment promoting

Abstract It is yet unknown how a fungus and tumor interplay impairs innate immunity, modulating tumorigenesis. Here, we found that oral infection with Cladosporium cladosporioides of mice with Ikka deficiency in epithelial stem cells enhanced STAT3-dependent oral squamous cell carcinoma (SCC) development and fungal colonization. In wild-type mice infection was cleared up, suggesting a synergic tumor-fungus loop involved in the accelerated carcinogenesis. C. cladosporioides-mediated EGFR activation stimulated intratumor STAT3-led pathways to generate an acidic oral milieu, which disrupted bacterial compositions and suppressed neutrophil’s ROS but increased Il1b expression, dampening neutrophil’s fungitoxicity and allowing oral fungal and bacterial overgrowth. In addition, fungus-induced IL-1β/IL-17A augmented STAT3 activity in SCC cells, contributing to local and distal carcinogenesis. Significantly, fungal signals were greater in human head and neck SCCs (HNSCCs) and SCC-adjacent tissues than in healthy controls and were co-localized with IL1B-expressing neutrophils in HNSCCs. These similar traits of oncogenic pathways, microbiota dysbiosis, and defective neutrophils in HNSCC patients with poor survival highlight the importance of increased fungal infection for human malignant development and therapy. Citation Format: Xin Li, Na-Young Song, Amit Kumar Singh, Jonathan Badger, Chengfei Jiang, Feng Zhu, Debra Tross, Yongmei Zhao, Bao Tran, Yinling Hu. Oral fungal infection tweaks the innate immune tumor microenvironment promoting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2798.