Fibroblast regulates angiogenesis in assembled oral cancer organoid: A possible role of NNMT

Abstract Objective Tumour angiogenesis is affected by various cell types in the tumour microenvironment (TME), including cancer cells and cancer‐associated fibroblasts (CAFs). Here, an assembled organoid model was generated to investigate the mechanism by which the TME regulates angiogenesis in oral squamous cell carcinoma (OSCC). Materials and Methods Secretion of vascular endothelial growth factor‐A (VEGFA) was analysed to compare the proangiogenic properties of OSCC cells and corresponding CAFs. Cell aggregates consisting of endothelial cells (ECs), CAFs and cancer cells were generated to construct assembled organoids. Nicotinamide N‐methyltransferase (NNMT) was pharmacologically or genetically inhibited to block the activation of CAFs. ATAC‐seq was employed to test the transcriptional network of fibroblasts overexpressing NNMT. Results Compared with cancer cells, CAFs secreted more VEGFA. Coculture with CAFs more effectively promoted the sprouting of ECs. Blockade of CAF activation via inhibition of NNMT drastically reduced the expression of CD31 in the assembled organoids. Overexpression of NNMT enhanced the transcription of genes related to angiogenesis in fibroblasts. Specifically, NNMT orchestrated the enrichment of the transcription factor JUNB at the promoter of VEGFA . Conclusions We clarify that stromal NNMT enables the steady reproduction of angiogenesis in assembled oral cancer organoids, providing a novel target for exploiting antiangiogenic therapy.