NOX5 mediates the crosstalk between tumor cells and cancer‐associated fibroblasts via regulating cytokine network

Activation of cancer‐associated fibroblasts (CAFs) is a crucial feature for tumor malignancy. The reciprocal interplay between tumor cells and CAFs not only facilitates tumor progression and metastasis but also sustains the tumor‐promoting function of CAFs. Nevertheless, how tumor cells readily adapt to these functional CAFs is still unclear. NADPH oxidase 5 (NOX5) is a strong reactive oxygen species producer overexpressed in esophageal squamous cell carcinoma (ESCC) cells. In this study, we showed that NOX5‐positive ESCC cells induced normal fibroblasts (NFs) or adipose‐derived mesenchymal stem cells (MSCs) to express the marker of CAFs‐α smooth muscle actin. Moreover, these tumor cells reprogrammed the cytokine profile of the activated CAFs, which further stimulated NFs or MSCs to CAFs and induced lymphangiogenesis to facilitate ESCC malignancy. NOX5 activated intratumoral Src/nuclear factor‐κB signaling to stimulate secretion of tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), and lactate from tumor cells. Subsequently, TNF‐α, IL‐1β, and lactate activated CAFs, and facilitated the secretion of IL‐6, IL‐7, IL‐8, CCL5, and transforming growth factor‐β1 from CAFs. These CAFs‐derived cytokines reciprocally induced the progression of NOX5‐positive ESCC cells. Our findings together indicate that NOX5 serves as the driving oncoprotein to provide a niche that is beneficial for tumor malignant progression.