Abstract P2-21-06: The relationship between the gene expression difference of fibroblasts in the tumor microenvironment and metastasis of triple-negative breast cancer

Abstract

Abstract Background Triple negative breast cancer (TNBC) is a breast cancer subtype with increased risk of distant metastasis, especially to lung and liver. In addition to the intrinsic characteristics of tumor cells, the molecular features of the tumor microenvironment cells can also regulate the metastasis process of TNBC. In this study, we tried to characterize the transcriptomic features of microenvironment fibroblasts associated with the distant metastasis of TNBC. Method We established PDX models by obtaining tumor tissues from 26 triple-negative breast cancer patients and transplanting them into the mammary fat pads of immunodeficient mice. When the PDX tumors grew sufficiently in the fat pads, we excised them and saved the mice to assess whether each PDX tumor was capable of developing spontaneous distant metastasis. We used bulk RNA sequencing and single cell RNA sequencing to determine the transcriptomic features associated with the distant metastasis. Results We classified the 26 TNBC PDX models based on their in vivo metastasis capacity and the clinical outcomes of the corresponding patients. Non-metastatic PDX models were defined as the lack of developing distant metastasis in either mouse experiment or clinical follow-up data (n=5). PDX models were defined as metastatic models when they developed distant metastasis in both mouse and human (n=4). We performed single cell RNA sequencing using the nine PDX tumors and observed a substantial gene expression differences of fibroblasts in the tumor microenvironment between the metastatic and non-metastatic PDX models. The fibroblasts of the metastatic PDX models showed up-regulation of genes involved in the response to hypoxia, inflammatory response, neutrophil chemotaxis, cellular response to IL-1, positive regulation of cell proliferation, and negative regulation of apoptotic process. Moreover, this difference of gene expression between metastatic and non-metastatic TNBC PDX models were not identified by the bulk RNA sequencing data. Conclusion By using the single cell RNA sequencing using the TNBC PDX models, we identified key features of fibroblasts in the tumor microenvironment that contributes to the metastasis capacity of TNBC. Further studies are on-going to elucidate the underlying mechanisms. Citation Format: Woo Hang Heo, Woochan Lee, SONGBIN LI, Jong-Il Kim, Hyeong-Gon Moon. The relationship between the gene expression difference of fibroblasts in the tumor microenvironment and metastasis of triple-negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-21-06.