Abstract 1728: Senescent cancer-associated fibroblast drives colorectal cancer progression in a METTL1-dependent manner
Authors: Weng Jingrong , Wang Xiaolin , Liu Xiaoxia , Luo Yanxin , Yu Huichuan 
Published: March 2024

Abstract
Background: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. More comprehensive studies of key molecular alterations were urgent. Cancer-associated fibroblasts (CAFs) exhibit the senescence-associated secretory phenotype (SASP) which contributes to the progression of cancer through the transcriptomic reprogramming at their senescent states. N7-methylguanosine (m7G), one of the most common RNA modifications, is catalyzed by Methyltransferase-like 1 (METTL1) in human RNA. We therefore investigated the role of METTL1-mediated transcriptomic reprogramming in the crosstalk between senescent CAFs (s-CAFs) and cancer cells.
Methods: The SA-β-gal staining and immunofluorescence assays were conducted to characterize the senescent cells. The transwell, wound scratch and organoids assays were preformed to test the abilities of viability, migration and invasion. The concentrations of cytokines and chemokines were determined by Luminex liquid suspension chip. The methylated RNA immunoprecipitation and dot blot assays were performed to characterize the RNA m7G levels in the transcriptome.
Results: Through the activation of mTOR signaling, the expression of P16 gene was significantly up-regulated in s-CAFs which was treated by H2O2, accompanied by an increased proportion of SA-β-gal+ cells and altered expression level of METTL1 protein. Luminex liquid suspension chip analysis revealed a significant increase in SASP cytokines such as TNF-α and PDGF-BB in the conditioned media of s-CAFs. Co-culturing CRC cell and organoids with s-CAFs resulted in down-regulation of METTL1 expression and significantly enhanced its invasion and migration abilities, while organoids exhibited increased activity and proliferated more rapidly. TNF-α and PDGF-BB down-regulated the METTL1 expression in CRC cell, while inhibitors targeting TNF-α and PDGF-BB rescued this trend. Interestingly, the regulatory effect on METTL1 of CRC cell by s-CAFs which treated by rapamycin was disappeared. These results indicated that METTL1 modulates RNA m7G modifications influenced by SASP cytokines for promoting CRC metastasis flow.
Conclusions: In summary, our findings illustrated that METTL1 plays a role in relaying tumor-promoting signals from s-CAFs in response to SASP cytokines. This ultimately contributes to the tumor-promoting signal flow from s-CAFs. This highlights the importance of understanding the molecular mechanisms underlying the communication between different cell types in the tumor microenvironment. In addition, it also provides a novel strategy for clinical treatment in advanced CRC.
Keywords: METTL1, Epigenetic regulation, Senescent CAFs, Tumor microenvironment
Citation Format: Jingrong Weng, Xiaolin Wang, Xiaoxia Liu, Yanxin Luo, Huichuan Yu. Senescent cancer-associated fibroblast drives colorectal cancer progression in a METTL1-dependent manner [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 1728.