Abstract 3156: C1orf116, an uncharacterized gene with unknown function, restricts movement capacity of would-be metastatic cells through modulation of tight junctions

Abstract

Abstract Lethal metastases are the end-result of a cancer cell that escapes the primary tumor and eventually invades a secondary site. Thus, in order for a cancer cell to metastasize from the primary tumor, it must move. In a critical early event of metastasis, a stationary epithelial cell undergoes a dramatic transmogrification event to gain mesenchymal-like features, most notably, ability to move. The full repertoire of genes regulating this switching event and inducing potential metastatic cell movement in the primary tumor remains incomplete. Using a multi-study discovery analysis (doi: 10.1186/s12885-017-3413-3), we identified C1orf116 as a novel candidate driver of an epithelial phenotype. C1orf116 is a highly conserved unnamed gene of unknown function. It is highly expressed in proliferative tissues (e.g. skin, lung, esophagus; GTeX) and is associated with an epithelial gene expression signature in cancer cell lines (CCLE). To determine if C1orf116 is a driver of epithelial phenotype, we overexpressed C1orf116 in C1orf116low PC3 cells (PC3-oe). PC3-oe demonstrated distinctive cobblestone epithelial cellular morphology and increased epithelial marker expression (e.g. OVOL1, CDH1, ESRP). Knockdown of C1orf116 expression in C1orf116high C42b cells (C42b-kd) resulted in decreased expression of classical epithelial markers. This data indicates that C1orf116 was sufficient to induce an epithelial transition. The essential characteristic of a lethal emigrant cell that may give rise to a clinical metastasis is gaining the capacity to move. We found that PC3-oe cultures had significantly reduced motility compared to control, suggesting that C1orf116 restricts motility. Cellular motility is influenced by many factors, including cell-cell adhesion. We observed that PC-oe established cell-cell contacts more rapidly than control cells and hypothesized that C1orf116 promoted cell-cell adhesion. PC3-oe cells had dramatically increased expression of tight junction complex proteins (e.g. ZO-1, ZO2, CLDN1). In contrast, C42b-kd cells had reduced expression of these tight junction components. These data demonstrate that C1orf116 promotes tight junctions and inhibits cell movement, thereby restricting the active emigrant phenotype of potentially metastatic cells. The putative metastasis suppressor role of C1orf116 is further substantiated by clinical data. C1orf116 expression is reduced in radical prostatectomy specimens from patients who progress with a biochemical recurrence compared to those who do not recur. Similarly, C1orf116 expression is decreased in prostate cancer metastatic lesions compared to primary tumor. This work shows the critical role of the overlooked gene and protein C1orf116. Further knowledge of how movement is restricted in the primary tumor provides valuable insight into the lethal metastatic process. Citation Format: Sarah R. Amend, Kenneth J. Pienta. C1orf116, an uncharacterized gene with unknown function, restricts movement capacity of would-be metastatic cells through modulation of tight junctions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3156.