Burns, M. R. | Search bioRxiv

bioRxiv2024

The polyamine transporter ATP13A3 mediates DFMO-induced polyamine uptake in neuroblastoma

High-risk neuroblastomas, often associated with MYCN oncogene amplification, are addicted to polyamines, small polycations vital for cellular functioning. We have shown that neuroblastoma cells increase polyamine uptake when exposed to the polyamine biosynthesis inhibitor DFMO, currently in clinical trial, and that this mechanism limits the efficacy of the drug. While this finding resulted in the clinical development of polyamine transport inhibitors including AMXT 1501, presently under clinical investigation in combination with DFMO, the mechanisms and transporters involved in DFMO-induced polyamine uptake are unknown. Knockdown of ATP13A3, a member of the P5B-ATPase family, limited basal and DFMO-induced polyamine uptake, attenuated MYCN-amplified and non-MYCN-amplified neuroblastoma cell growth and potentiated the inhibitory effects of DFMO. Overexpression of ATP13A3 in neuroblastoma cells increased polyamine uptake, which was inhibited by AMXT 1501, highlighting ATP13A3 as a key target of the drug. The association between high ATP13A3 expression and poorer survival in neuroblastoma further supports a role of this transporter in neuroblastoma progression. Thus, this study identified ATP13A3 as a critical regulator of basal and DFMO-induced polyamine uptake and a novel therapeutic target for neuroblastoma. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=186 SRC="FIGDIR/small/581161v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@11bef78org.highwire.dtl.DTLVardef@106c250org.highwire.dtl.DTLVardef@bf39b1org.highwire.dtl.DTLVardef@64d05f_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

Polyamine transport inhibition and cisplatin synergistically enhance tumor control through oxidative stress in murine head and neck cancer models

BackgroundSurgery and/or platinum-based chemoradiation remain standard of care for patients with head and neck squamous cell carcinoma (HNSCC). While these therapies are effective in a subset of patients, a substantial proportion experience recurrence or treatment resistance. As cisplatin mediates cytotoxicity through oxidative stress while polyamines play a role in redox regulation, we posited that combining cisplatin with polyamine transport inhibitor, AMXT-1501, would increase oxidative stress and tumor cell death in HNSCC cells. MethodsCell proliferation was measured in syngeneic mouse HNSCC cell lines treated with cisplatin {+/-} AMXT-1501. Synergy was determined by administering cisplatin and AMXT-1501 at a ratio of 1:10 to cancer cells in vitro. Cancer cells were transferred onto mouse flanks to test the efficacy of treatments in vivo. Reactive oxygen species (ROS) were measured. Cellular apoptosis was measured with flow cytometry using Annexin V/PI staining. High-performance liquid chromatography (HPLC) was used to quantify polyamines in cell lines. Cell viability and ROS were measured in the presence of exogenous cationic amino acids. ResultsThe combination of cisplatin and AMXT-1501 synergize in vitro on HNSCC cell lines. In vivo combination treatment resulted in tumor growth inhibition greater than either treatment individually. The combination treatment increased ROS production and induced apoptotic cell death. HPLC revealed the synergistic mechanism was independent of intracellular polyamine levels. Supplementation of cationic amino acids partially rescued cancer cell viability and reduced ROS. ConclusionAMXT-1501 enhances the cytotoxic effects of cisplatin in vitro and in vivo in aggressive HNSCC cell lines through a polyamine-independent mechanism.

cancer biology↗