Phenotypic profiling of solute carriers characterizes serine transport in cancer

Abstract

Serine is a vital amino acid in tumorigenesis. While cells can perform de novo serine synthesis, most transformed cells rely on serine uptake to meet their increased biosynthetic requirements. Solute carriers (SLCs), a family of transmembrane nutrient transport proteins, are the gatekeepers of amino acid acquisition and exchange in mammalian cells and are emerging as anticancer therapeutic targets; however, the SLCs that mediate serine transport in cancer cells remain unknown. Here we perform an arrayed RNAi screen of SLC-encoding genes while monitoring amino acid consumption and cell proliferation in colorectal cancer cells using metabolomics and high-throughput imaging. We identify SLC6A14 and SLC25A15 as major cytoplasmic and mitochondrial serine transporters, respectively. We also observe that SLC12A4 facilitates serine uptake. Dual targeting of SLC6A14 and either SLC25A15 or SLC12A4 diminishes serine uptake and growth of colorectal cancer cells in vitro and in vivo, particularly in cells with compromised de novo serine biosynthesis. Our results provide insight into the mechanisms that contribute to serine uptake and intracellular handling.

Comparative genomics of macaques and integrated insights into genetic variation and population history

“…SLC25A15 was unannotated due to a gap in the Mmul_10 assembly. SLC25A15 encodes the mitochondrial ornithine transporter 1 (ORNT1 or ORC1) and plays a role in serine transportation 57 . Pathogenic mutations in SLC25A15 are associated with Hyperornithinemia-Hyperammonemia-Homocitrullinuria syndrome in humans 58,59 .…”

A rapid and simple non-radioactive assay for measuring uptake by solute carrier transporters

“…The existence of these advantages raised the intriguing question of whether using stable isotope labeled substrate as SLC substrate and LC-MS/MS as the detection method could develop an alternative to radioligand uptake assay for SLC. Although several uptake assays using stable isotope labeled substrates have been applied to study SLC functions, none has reported both the optimization of assay and the comparison to the radioactive method ( Gauthier-Coles et al, 2021 ; Bay et al, 2022 ; Papalazarou et al, 2023 ).…”