A recent preprint reports that receptor endocytosis of the receptor tyrosine kinase ALK enhances cellular glucose uptake in neuroblastoma cell lines with ALK amplification. The authors build on prior observations that RTK‑containing endocytic vesicles can deliver extracellular glucose to hexokinases on the outer mitochondrial membrane and ask whether this noncanonical mechanism contributes to cancer cell metabolism.
The study compared neuroblastoma cell lines harboring different ALK alterations and measured the consequences of inhibiting ALK activity or blocking receptor endocytosis on glucose uptake. The findings indicate that receptor internalization of ALK is a major regulatory mechanism of glucose import specifically in ALK‑amplified neuroblastoma cells.
The authors report a clear distinction between neuroblastoma cells with ALK amplification and those with ALK activating mutations. Inhibition of ALK or of receptor endocytosis produced an approximately 40–50% decrease in glucose uptake in ALK‑amplified cells. By contrast, ALK‑mutant neuroblastoma cells did not show a comparable reduction in glucose import under the same perturbations. These results suggest that the endocytic mechanism described is particularly relevant to tumor cells driven by ALK gene amplification rather than by point mutations in ALK.
The reduction in glucose uptake following ALK or endocytosis inhibition occurred independently of the canonical downstream signaling pathways typically associated with RTKs. Specifically, the effect did not require the ERK MAPK or the PI3K‑AKT pathways, indicating that the mechanism linking ALK endocytosis to glucose uptake is distinct from these well‑characterized signaling cascades.
Mechanistic dissection identified several required components for ALK‑dependent glucose uptake. The process depended on dynamin‑dependent endocytosis, implicating classical scission machinery in the internalization step. Cytoplasmic dynein, a microtubule motor implicated in retrograde vesicle transport, was also required, consistent with vesicular movement toward perinuclear regions or mitochondria. Finally, the glucose transporter GLUT1 was necessary for this pathway, linking receptor endocytosis to the actual import of extracellular glucose into cells.
The authors observed that overexpressed ALK constitutively co‑endocytosed with GLUT1 into intracellular vesicles that are transported toward mitochondria. This supports a model in which ALK‑containing endocytic vesicles carry extracellular glucose in close proximity to mitochondrial outer‑membrane hexokinases, facilitating glucose phosphorylation and retention. The report emphasizes trafficking of these vesicles rather than canonical cytoplasmic signaling as the driver of increased glucose uptake.
Pharmacologic or genetic inhibition studies indicated that blockade of ALK kinase activity and blockage of receptor endocytosis both suppressed glucose uptake, but their combined inhibition did not produce an additive effect. The lack of additivity is interpreted by the authors as evidence that ALK activity and endocytosis operate within the same functional pathway to promote glucose uptake in ALK‑amplified cells.
Beyond effects on glucose import, disruption of the endocytic machinery selectively impaired growth of ALK‑amplified neuroblastoma cell lines. This selective growth defect links the metabolic role of ALK endocytosis to a cellular fitness phenotype and suggests that components of the endocytic pathway may represent a metabolic vulnerability in tumors driven by RTK amplification.
These results are reported in a bioRxiv preprint and have not been peer reviewed. The authors declare no competing interests. Funding sources reported in the manuscript include the Japan Society for the Promotion of Science, the Sumitomo Foundation, and the Uehara Memorial Foundation. The report should be interpreted with the caveat that it has not undergone formal peer‑review, and additional validation may be required.
The data identify ALK endocytosis as a regulator of glucose uptake and link receptor trafficking to tumor metabolism in the context of ALK‑amplified neuroblastoma. By distinguishing amplification from mutation, the study suggests that molecular context influences whether RTK endocytosis supports metabolic phenotypes. The selective growth impairment following endocytic disruption highlights a potential vulnerability that could inform future preclinical work exploring whether inhibition of receptor trafficking or associated transport machinery is therapeutically exploitable in RTK‑driven cancers.
Note: All points in this summary are drawn directly from the cited preprint. Details of experimental methods, full datasets, and additional controls are reported in the source manuscript and its supplementary material; readers should consult the original preprint for full experimental detail.