CD98hc promotes drug resistance in extranodal natural killer/T cell lymphoma through tumor cell-derived small extracellular vesicles.

Extranodal natural killer/T cell lymphoma (ENKTL) shows a high rate of recurrence after chemoradiotherapy. Drug resistance can be mediated by the cargo of small extracellular vesicles (sEVs). Here, we show that high abundance of the transmembrane glycoprotein CD98hc in tumor cells and serum sEVs was associated with ENKTL progression and drug resistance. Mechanistically, PEGylated-asparaginase (PEG-asp) treatment, a common therapy against ENKTL, promoted the translocation of the transcription factor ATF4 to the nucleus, where it was stabilized by USP1 and subsequently increased CD98hc expression. CD98hc delivered in tumor cell-derived sEVs increased tumor cell proliferation and drug resistance in a cultured human NK lymphoma cell line, animal models, and samples from patients with refractory/relapse ENKTL. Moreover, inhibiting both USP1 and EV secretion synergistically enhanced the cytotoxicity of PEG-asp. These data suggest that targeting CD98hc in the treatment of ENKTL may be beneficial in overcoming drug resistance.