LAUSR

Introduction: Cancer-associated fibroblasts (CAFs) play an important role in cancer progression and malignant transformation by interacting with cancer cells in the tumor microenvironment. Pleural dissemination of non-small cell lung cancer (NSCLC) is a condition in which cancer cells directly spread from the primary tumor site into the extrapulmonary thoracic cavity and colonize the pleura. However, not all free detached cancer cells can survive under anchorage-independent conditions in thoracic cavity, and some important factors are assumed to be involved in the formation of pleural dissemination. In this study, we investigated the role of CAFs in the formation of pleural dissemination in NSCLC. Methods: Using in vitro co-culture models, conditioned medium, and in vivo xenograft models, we investigated CAF-induced phenotypic changes in lung cancer cell: proliferative ability, invasive ability, anchorage-independent growth ability, cell adhesion to extracellular matrix, and tumorigenicity in thoracic cavity. Next, we performed RNA sequencing analysis using 3D co-culture models of cancer cells and CAFs to explore a molecule that contributes to the formation of pleural dissemination, and then verified it using in vitro and in vivo mice models of pleural dissemination. Results: Cancer cells showed enhanced migration, anchorage-independent growth, adhesion, and invasion ability by co-culture with CAFs. In 3D co-culture model of cancer cells and CAFs, even cancer cells which did not form spheroid by themselves acquired the ability of spheroid formation surrounding the CAF core, suggesting that the interactions with CAFs promote spheroid formation. Inoculation of cancer cells together with CAFs into mouse thoracic cavity developed pleural dissemination more efficiently than inoculation of cancer cells alone. RNA sequencing analysis revealed that co-culture with CAFs upregulated the expression of Cellular Communication Network Factor 1 (CCN1), a matricellular protein, in cancer cells. We then verified that ectopically CCN1-overexpressing lung cancer cell lines increased migration and adhesion ability in vitro, and tumorigenicity in thoracic cavity in mouse pleural dissemination model. Conclusions: CAFs promote development of pleural dissemination via driving spheroid formation and upregulating CCN1 expression in NSCLC. Citation Format: Masayoshi Ohki, Naoki Matsuda, Ken Suzawa, Tomohiro Habu, Mao Yoshikawa, Kazuma Iwata, Yin Min Thu, Kazuhiko Shien, Hiromasa Yamamoto, Shinichi Toyooka. Cancer-associated fibroblasts drive spheroid formation and pleural dissemination in non-small cell lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5838.