Phosphate dysregulation via the XPR1–KIDINS220 protein complex is a therapeutic vulnerability in ovarian cancer

Abstract

Despite advances in precision medicine, the clinical prospects for patients with ovarian and uterine cancers have not substantially improved. Here, we analyzed genome-scale CRISPR/Cas9 loss-of-function screens across 851 human cancer cell lines and found that frequent overexpression of SLC34A2 – encoding a phosphate importer – is correlated to sensitivity to loss of the phosphate exporter XPR1 in vitro and in vivo. In patient-derived tumor samples, we observed frequent PAX8-dependent overexpression of SLC34A2 , XPR1 copy number amplifications, and XPR1 mRNA overexpression. Mechanistically, in SLC34A2 -high cancer cell lines, genetic or pharmacologic inhibition of XPR1-dependent phosphate efflux leads to the toxic accumulation of intracellular phosphate. Finally, we show that XPR1 requires the novel partner protein KIDINS220 for proper cellular localization and activity, and that disruption of this protein complex results in acidic vacuolar structures preceding cell death. These data point to the XPR1:KIDINS220 complex and phosphate dysregulation as a therapeutic vulnerability in ovarian cancer.

Systematic profiling of conditional degron tag technologies for target validation studies

“…We next performed similar experiments testing a total of 16 unique POIs, spanning different protein classes including ten cytoplasmic proteins (Green Fluorescent Protein (GFP), NanoLuciferase (NanoLuc), Red-shifted Firefly Luciferase (RFluc 18 ), Protein arginine methyltransferase 2 (PRMT5 19 ), WD Repeat and SOCS Box-Containing 2 (WSB2), induced myeloid leukemia cell differentiation protein (MCL1 20 ), Soc-2 Suppressor Of Clear Homolog (SHOC2 21,22 ), Methionine Adenosyltransferase 2 A (MAT2A 23 ), Vacuolar protein sortingassociated protein 4 (VPS4A 24 ), and Protein Activator of interferoninduced Protein Kinase EIF2AK2 (PRKRA 25 ); three nuclear proteins (Stromal Antigen 1 and 2 (STAG1 and STAG2 26 ), DNA (cytosine-5)methyltransferase 1 (DNMT3A 27 ); two multi-pass plasma membrane proteins (Xenotropic and Polytropic Receptor 1 (XPR1 28,29 ), and Kinase D interacting protein of 220 kDa (KIDINS220 30,31 ); and one single-pass transmembrane receptor tyrosine kinase (Fms-Related receptor tyrosine kinase 3 with the internal tandem duplication, FLT3-ITD 27 ).…”

“…4a and Supplementary Fig. 11b), possibly due to the important role of XPR1 in maintaining the viability of this cell line 30 , or to differences in protein homeostasis mechanisms across cellular contexts 34 . We also assessed the performance of each CDT in murine contexts using the NIH-3T3 cell line.…”

“…The activity of XPR1, the only annotated cellular phosphate exporter in the human genome 29,30 , can be assessed using 32 P-labeled phosphate pulse-chase experiments to quantify cellular phosphate export. XPR1 inactivation (XPR1-KO) significantly decreases cellular phosphate export (Fig.…”

“…We kindly thank Jean Luc Battini for providing the sequence for the XRBD-mFc construct published previously 29,30 . The plasmid encoding XRBD (strain NZB) was synthesized and cloned into pcDNA3.4 by Thermo Fisher Scientific GENEART GmbH.…”

Functional genomics of complex cancer genomes

“…Several cancer cell dependencies have successfully been identified using this approach. For example, Bondeson et al discovered how overexpression of the phosphate importer SLC34A2, frequently observed in ovarian carcinoma, associates with increased sensitivity to disruption of the XPR1- KIDINS220-dependent mechanism of phosphate efflux, which results in the toxic intracellular accumulation of phosphate and represents a previously unknown therapeutic vulnerability in ovarian carcinoma 19 . The Genomics of Drug Sensitivity in Cancer Project (GDSCP) seeks to identify optimal interventions for specific cancer genetic features by assessing the sensitivity profile of over 1000 genomically and transcriptionally characterized cancer cell lines to a large panel of chemotherapeutic agents and targeted therapies 20 .…”