Abstract A153: ALK proximitome reveal SLC3A2, part of the polyamine transporter, as a membrane interaction partner with growth promoting ability

Abstract

Solute Carrier Family 3, Member 2 (SLC3A2 or 4F2hc) was identified as a potential ALK interacting partner in a BioID-proximity labeling screen in neuroblastoma cells. SLC3A2 is a multifunctional glycoprotein that mediates integrin-dependent signaling, acts as a trafficking chaperone for amino acid transporters, and regulates polyamine transportation. However, the functional consequences of an interaction between SLC3A2 and ALK are unclear. In this work we confirm that endogenous SLC3A2 and ALK interact in NB cells. This SLC3A2:ALK interaction is abrogated upon treatment with the ALK inhibitor lorlatinib. In agreement, stimulation of ALK with ALKAL2 ligand, resulted in SLC3A2 protein levels, which was decreased upon lorlatinib treatment. We show here that loss of ALK activity leads to suppressed SLC3A2 expression and reduced SLC3A2 protein stability in a panel of neuroblastoma cells. Solute Carrier Family 7 Member 3 (SLC7A5, also known as LAT1) is an amino acid transporter that forms a stable complex with SLC3A2 for localization at the plasma membrane, where they function. This complex is lost upon knockdown of SLC3A2, with concomitant inhibition of NB cell growth. To investigate the therapeutic potential of SLC3A2/SLC7A5 complex targeting, we performed monotreatment of NB cells with AMXT-1501 (a polyamine transport inhibitor) only showed a moderate effect in NB cells. In contrast, a combined  lorlatinib/AMXT-1501 treatment resulted in synergistic inhibition of cell growth in ALK-driven primary-cultured mouse neuroblastoma cell lines. Taken together, our results show that SLC3A2 protein stability and its interaction with ALK depend on ALK signaling in ALK-driven neuroblastoma. The synergistic effect of combined ALK and polyamine transport inhibitors suggests a potential therapeutic option for ALK-driven neuroblastoma.

Citation Format: Bengt Hallberg, Wei-Yun Lai, Tzu-Po Chuang, Ruth Palmer. ALK proximitome reveal SLC3A2, part of the polyamine transporter, as a membrane interaction partner with growth promoting ability [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A153.