Abstract 1599: Genes subject to changes in heterogeneity can function as regulators of metastasis

Abstract

Abstract Tumor cell heterogeneity has been strongly implicated in metastatic progression of solid tumors such as triple-negative breast cancer (TNBC), leading to resistance and recurrence. Raf Kinase Inhibitory Protein (RKIP or PEBP1) effectively suppresses metastasis in TNBC but is lost in many patients. We hypothesize that RKIP works in part by reducing the variability of gene expression in TNBC cells. To test whether RKIP reduces overall transcriptional heterogeneity, we compared the variation in gene expression between individual cells in metastatic (low RKIP) versus non-metastatic (high RKIP) TNBC tumors. Single-cell RNA-sequencing revealed transcriptional heterogeneity was decreased with RKIP overexpression. Many cancer regulatory genes were more homogeneous and up-regulated in the RKIP-expressing cells. Among these enriched and homogenously expressed genes is KMT5C, a histone methyltransferase that facilitates epigenetic transcriptional repression. Cell, mouse, and clinical studies suggest KMT5C expression blocks invasion, extravasation, and colonization of tumor cells, consistent with a role as a novel suppressor of metastasis. These studies reveal the importance of genes involved in heterogeneity as potential regulators of metastatic progression in cancer. Citation Format: Dongbo Yang, Christopher Dann, Andrea Valdespino, Lydia Robinson-Mailman, Mengjie Chen, Sebastian Pott, Marsha Rosner. Genes subject to changes in heterogeneity can function as regulators of metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1599.