Abstract 3889: The role of CXCL1 in crosstalk between breast cancer cells with ESR1 mutations and lymphatic endothelial cells

Abstract

Abstract Various endocrine therapies have been developed such as selective estrogen receptor modulation (SERM), selective estrogen receptor downregulator (SERD) and ligand deprivation using aromatase inhibitors (AI). Tamoxifen, fulvestrant, and AIs are the most used adjuvant treatment for pre- and postmenopausal women with early-stage estrogen receptor positive breast cancer. Tamoxifen and AIs have widespread anti-neoplastic and chemopreventive effects, yet despite this, many breast cancers that are initially receptive ultimately become resistant and recur. There are many known underlying molecular processes that result in resistance, but no overarching pattern has yet been identified. Our previous research demonstrates that the crucial molecular and cellular players secreted from a crosstalk between stromal cells and breast cancer cells can control the development of the tumor and the metastatic process in breast cancer. Breast cancer metastasis involves lymphatic dissemination in addition to hematogenous spreading. Although stromal lymphatic vessels (LVs) serve as initial metastatic routes, roles of organ-residing LVs are underinvestigated. In this report, we demonstrated that crosstalk between ESR1 mutant cells (Y537S and D538G), and lymphatic endothelial cells (LECs), a component of lymphatic vessels, promoted ESR mutant cell growth and migration. To identify a critical secreted factor in this crosstalk, we performed the cytokine array in secretome of crosstalk between ESR1 mutant cells and LECs, and found that CXCL1 is highly secreted from LECs. Knockdown of CXCR2 in ESR1 mutant cells attenuated ESR1 cell migration in the conditioned media of LECs crosstalked with ESR1 mutant cells. To investigate a potential impact given the current clinical landscape of endocrine resistant breast cancer with ESR1 mutations, we performed a cell viability assay and migration assay using reparixin, CXCR1/2 inhibitor in co-culture with ESR1 mutant cells and LECs. Significantly, reparixin decreased ESR1 mutant cell viability and migration compared to vehicle. We found that the combination treatment of reparixin and Palbociclib and ribociclib significantly inhibited ESR1 mutant cell growth and migration compared the single treatment. These findings implicate CXCL1-CXCR1/2 signaling as a critical event in the growth of breast cancer with ESR1 mutation and metastasis. Therefore, we have provided evidence that supports the hypothesis that functional inhibition of the CXCL1 and CDK4/6 signaling pathway has the potential to circumvent endocrine resistant tumor growth and metastasis. Citation Format: Daniel Galke, Kideok Jin. The role of CXCL1 in crosstalk between breast cancer cells with ESR1 mutations and lymphatic endothelial cells. [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 3889.