LOXL2-induced PEAR1 Ser891 phosphorylation suppresses CD44 degradation and promotes triple-negative breast cancer metastasis
Yingzhi Shen, … , Junling Liu, Xuemei Fan
Yingzhi Shen, … , Junling Liu, Xuemei Fan
Published August 15, 2024
Citation Information: J Clin Invest. 2024;134(16):e177357. https://doi.org/10.1172/JCI177357.
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Research Article Cell biology Oncology

LOXL2-induced PEAR1 Ser891 phosphorylation suppresses CD44 degradation and promotes triple-negative breast cancer metastasis

Abstract

CD44 is associated with a high risk of metastasis, recurrence, and drug resistance in various cancers. Here we report that platelet endothelial aggregation receptor 1 (PEAR1) is a CD44 chaperone protein that protected CD44 from endocytosis-mediated degradation and enhances cleavage of the CD44 intracellular domain (CD44-ICD). Furthermore, we found that lysyl oxidase–like protein 2 (LOXL2), an endogenous ligand of PEAR1, bound to the PEAR1-EMI domain and facilitated the interaction between PEAR1 and CD44 by inducing PEAR1 Ser891 phosphorylation in a manner that was independent of its enzyme activity. Levels of PEAR1 protein and PEAR1 phosphorylation at Ser891 were increased in patients with triple-negative breast cancer (TNBC), were positively correlated with expression of LOXL2 and CD44, and were negatively correlated with overall survival. The level of PEAR1 Ser891 phosphorylation was identified as the best independent prognostic factor in TNBC patients. The prognostic efficacy of the combination of PEAR1 phosphorylation at Ser891 and CD44 expression was superior to that of PEAR1 phosphorylation at Ser891 alone. Blocking the interaction between LOXL2 and PEAR1 with monoclonal antibodies significantly inhibited TNBC metastasis, representing a promising therapeutic strategy for TNBC.

Authors

Yingzhi Shen, Jie Yan, Lin Li, Huiyan Sun, Lin Zhang, Guoming Li, Xinxia Wang, Ruoyan Liu, Xuefeng Wu, Baosan Han, Xueqing Sun, Junling Liu, Xuemei Fan

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Figure 1

PEAR1 is a CD44-associated protein that is correlated with poor survival in TNBC patients.

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PEAR1 is a CD44-associated protein that is correlated with poor survival...
(A) Schematic of CD44-interacting proteins identified using IP-MS. CD44 and its interacting proteins were immunoprecipitated from whole-cell lysates of MDA-MB-231 cells using an anti-CD44 antibody and identified using MS. The IgG isotype served as a negative control. Specific proteins that interact with CD44 were screened. These proteins were detected in anti-CD44 IP samples but not in IgG IP samples; or the relative abundance ratio was greater than 200 in anti-CD44 IP samples compared to that in IgG-IP samples (area CD44/area IgG). (B) Bubble plots of the top 10 pathways obtained from KEGG enrichment analyses. (C) The top 20 effective proteins obtained from MS sorting according to the confidence score. (D) Co-IP of whole-cell lysates of MDA-MB-231 cells with anti-PEAR1 and anti-CD44 antibodies. The IgG isotype was used as a negative control. Results are representative of 3 independent experiments. (E) Representative IF staining of MDA-MB-231 cells with anti-PEAR1 (green) and anti-CD44 (red) antibodies and nuclei (blue). Scale bars: 20 μm (original image) and 10 μm (enlarged image). Quantitative analysis of the rate of PEAR1 and CD44 colocalization. (F) Representative IHC staining of the tissue microarray containing breast cancer and adjacent tissue samples with an anti-PEAR1 antibody. Scale bars: 50 μm. The PEAR1 staining scores were quantified as indicated (n = 86 for TATs, n = 126 for tumors; mean ± SEM). (G) Total overall survival of patients with breast cancer and with TNBC based on PEAR1 expression level (n values as indicated; log-rank test). KEGG pathway enrichment analyses were performed using the online tools DAVID and KOBAS (B); unpaired 2-tailed t tests were used for F; log-rank test was used for G. ****P < 0.0001.