The Journal of Clinical Investigation (Jul 2023)

Inhibition of DPAGT1 suppresses HER2 shedding and trastuzumab resistance in human breast cancer

  • Muwen Yang,
  • Yue Li,
  • Lingzhi Kong,
  • Shumei Huang,
  • Lixin He,
  • Pian Liu,
  • Shuang Mo,
  • Xiuqing Lu,
  • Xi Lin,
  • Yunyun Xiao,
  • Dongni Shi,
  • Xinjian Huang,
  • Boyu Chen,
  • Xiangfu Chen,
  • Ying Ouyang,
  • Jun Li,
  • Chuyong Lin,
  • Libing Song

Journal volume & issue
Vol. 133, no. 14

Abstract

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Human epidermal growth factor receptor 2–targeted (HER2-targeted) therapy is the mainstay of treatment for HER2+ breast cancer. However, the proteolytic cleavage of HER2, or HER2 shedding, induces the release of the target epitope at the ectodomain (ECD) and the generation of a constitutively active intracellular fragment (p95HER2), impeding the effectiveness of anti-HER2 therapy. Therefore, identifying key regulators in HER2 shedding might provide promising targetable vulnerabilities against resistance. In the current study, we found that upregulation of dolichyl-phosphate N-acetylglucosaminyltransferase (DPAGT1) sustained high-level HER2 shedding to confer trastuzumab resistance, which was associated with poor clinical outcomes. Upon trastuzumab treatment, the membrane-bound DPAGT1 protein was endocytosed via the caveolae pathway and retrogradely transported to the ER, where DPAGT1 induced N-glycosylation of the sheddase — ADAM metallopeptidase domain 10 (ADAM10) — to ensure its expression, maturation, and activation. N-glycosylation of ADAM10 at N267 protected itself from ER-associated protein degradation and was essential for DPAGT1-mediated HER2 shedding and trastuzumab resistance. Importantly, inhibition of DPAGT1 with tunicamycin acted synergistically with trastuzumab treatment to block HER2 signaling and reverse resistance. These findings reveal a prominent mechanism for HER2 shedding and suggest that targeting DPAGT1 might be a promising strategy against trastuzumab-resistant breast cancer.

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