Abstract B013: Investigating the role of LINE-1 ORF1 protein in a syngeneic mouse melanoma model

Abstract

Abstract Long interspersed element type 1 (LINE-1) is a class of transposable elements that make up 17% of human genome. Somatic LINE-1 insertions promote genomic instability and have been implicated in the evolution of various human cancer types. A full-length LINE-1 has two open reading frames (ORF1 and ORF2) that encode proteins essential for its replication in the genome. It has been well documented that LINE-1 ORF1 protein (ORF1p) is overexpressed in tumor tissues as compared to non-tumor tissues. However, whether ORF1p itself is oncogenic remains controversial. Downregulation of ORF1p has been shown to reduce cancer cell proliferation and metastasis. ORF1p has also been associated with the modulation of tumor microenvironment and activation of oncogenic pathways by interacting with cellular proteins. We are interested in the role of LINE-1 ORF1p in a syngeneic mouse melanoma model. B16-F10 is a mouse melanoma cell line derived from a C57BL/6 mouse. It had an undetectable level of ORF1p by Western blot. To investigate the effect of ORF1p overexpression in vitro and in vivo, we started with establishing ORF1p expression in B16-F10 cells. We utilized the Sleeping Beauty gene delivery system to make single-cell clones expressing the protein. Cell proliferation and migration assays give insight into the effect of ORF1p overexpression in vitro. Growth of the parental and ORF1p-expressing B16-F10 cells in C57BL/6 mice informs the effect of ORF1p overexpression in vivo. This study represents an important first step to establishing the role of ORF1p in melanoma, a common cancer worldwide. Citation Format: Raj Nandani, Wenfeng An. Investigating the role of LINE-1 ORF1 protein in a syngeneic mouse melanoma model [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B013.