Abstract LB283: ARC2-001 inhibits cancer-associated fibroblast-dependent cancer stem cell populations by disrupting cancer-stroma interactions
Authors: Lee Keun-Woo , Yeo So-Young , Sohn InSuk , Kim Seok-Hyung 
Published: April 2023

Abstract
ARC2-001, a natural product and FDA-approved anti-leukemic drug, has shown anticancer effects in hematological malignancies. This study investigates the inhibitory effect of ARC2-001 on cancer-associated fibroblasts (CAFs). CAFs promote cancer progression and directly stimulate cancer cell proliferation. In addition, CAFs act as therapeutic barriers to prevent the penetration of anticancer drugs and immune cells in the treatment of solid tumors such as colorectal cancer. In our previous study, we found a master transcription factor PRRX1 of stromal fibroblasts for myofibroblastic lineage progression in the cancer microenvironment. After deleting the expression of PRRX1 in various CAFs using the CRISPR-CAS9-sgRNA system, we confirmed changes in gene expression patterns and performed in silico screening to derive drugs showing similar gene expression patterns. These drugs were investigated through a gel contraction assay and indirect co-culture/direct 3D spheroid co-culture systems using various cancer cells and CAFs. Among them, ARC2-001 treatment not only significantly reduced the ECM remodeling ability of CAFs but also showed strong anticancer effects in the co-culture systems. In addition, the response to ARC2-001 was much more sensitive in CAFs than in cancer cells: the IC50 values in cancer cells were30-50nM, and the IC50 values in CAFs were 10-20nM. We produced HCT116 (colon cancer cell)-Colon CAFs spheroids, treated them with ARC2-001at low concentrations that could only affect CAFs, and analyzed RNA transcriptome changes by RNA-SEQ. We confirmed that HCT116 cells underwent EMT as well as observed an increase in the cancer stem cell (CSC) population by CAFs through co-culture of HCT116-CAFs spheroids. Interestingly, treatment with a concentration of ARC2-001 sufficient to inhibit only CAFs had no significant effect on HCT116-only spheroids, and little change occurred in gene expression patterns, but in HCT116 cells in spheroid co-culture with CAFs, the aforementioned changes (EMT and CSC population increase) all collapsed. This indicates that ARC2-001 interferes with the interactions between cancer cells and CAFs. ARC2-001 damages the cancer stem cell population of HCT116 through CAFs inhibition, indicating that the CSC subpopulation of HCT116 cells is dependent on CAFs. We further hypothesized that co-administration of ARC2-001 and commonly used anticancer drugs could be a very effective strategy, considering the ineffectiveness of commonly used anticancer drugs on the CSC subpopulation. Thus, we transplanted colon CAFs together with HCT116 cells into NOD/SCID mice and then administered 5FU, an existing anticancer drug, together with ARC2-001. For the combined treatment in the in vivo experiment, we treated ARC2-001 and 5FU at half of the commonly used concentrations. Surprisingly, we observed that both tumor growth and cancer metastasis were suppressed in the combination treatment group. This indicates that ARC2-001 dramatically increases the effectiveness of existing anticancer drugs and can be used as an additional combination therapy for colorectal cancer chemotherapy.
Citation Format: Keun-Woo Lee, So-Young Yeo, InSuk Sohn, Seok-Hyung Kim. ARC2-001 inhibits cancer-associated fibroblast-dependent cancer stem cell populations by disrupting cancer-stroma interactions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB283.