RT Journal Article SR Electronic T1 Implication of IL6-positive Cancer-associated Fibroblasts in Merkel Cell Carcinoma Pathogenesis: A Possible Modulator of Immune Microenvironment JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 4359 OP 4369 DO 10.21873/anticanres.15936 VO 42 IS 9 A1 ZHENG, ZHENLONG A1 YOO, DAE SAN A1 LI, SHANSHAN A1 PEI, MEILING A1 LEE, SANG GYUN A1 KIM, JI YOUNG A1 CHUNG, KEE YANG A1 ROH, MI RYUNG YR 2022 UL http://ar.iiarjournals.org/content/42/9/4359.abstract AB Background/Aim: The role of cancer-associated fibroblasts (CAFs) in the pathogenesis of Merkel cell carcinoma (MCC) remains unknown. This study aimed to investigate the clinicopathological significance of CAF subpopulations and their association with tumor-infiltrating lymphocytes (TILs) in patients with MCC. Materials and Methods: Clinicopathological features and the status of microenvironment fibrosis (MF) around tumor masses were evaluated in 20 MCC patient and tissue sections. Alpha-smooth muscle actin (α-SMA)-positive CAFs (α-SMA+CAFs), interleukin-6-positive CAFs (IL6+CAFs), CD4-positive TILs (CD4+TILs), and CD8-positive TILs (CD8+TILs) in MCC tissue samples were investigated using immunohistochemistry. Results: In a total of 20 MCC patients, high-MF was detected in 12 (60%) patients which was significantly associated with worse progression-free survival (p=0.048), but not with overall survival. CD4+/CD8+ TILs were frequently detected in MCC tissues. High-intra-tumoral CD8+TIL was significantly associated with better overall and progression-free survival (p=0.04 and p=0.015) in our cohort. High-αSMA+ CAFs were detected in 11 (55.0%) patients and high-IL6+CAFs in 10 (50.0%) patients. A negative association was found between high-IL6+CAF and high-intra-tumoral CD8+TILs (p=0.005). Patients with high IL6+CAFs showed worse overall/progression-free survival than patients with low-IL6+CAFs (p=0.022 and p=0.035). Conclusion: IL6+CAFs may largely influence the tumor immune microenvironment of MCC by modulating distinct T-cell populations and functions. This study provides a possible therapeutic target to overcome resistance to immune therapies in MCC.