PXD024672

PXD024672 is an original dataset announced via ProteomeXchange.

Title	Indentification of B7H3 WT/NQ N-Glycosites
Description	Most patients with triple negative breast cancer (TNBC) fail to respond to anti-PD1/PDL1 immunotherapy, indicating the necessity to explore immune checkpoint targets. B7H3 is a highly glycosylated protein. However, the mechanisms of B7H3 glycosylation regulation and whether the sugar moiety contributes to immunosuppression remain elusive. Here, we identify aberrant B7H3 glycosylation and found N-glycosylation of B7H3 at NXT motif sites are responsible for its protein stability and immunosuppression in TNBC tumors. Mechanistically, fucosyltransferase FUT8 catalyzes B7H3 core fucosylation at N-glycans to maintain its high expression. Knockdown of FUT8 rescues glycosylated B7H3-mediated immunosuppressive function in TNBC cells. Abnormal B7H3 glycosylation mediated by FUT8 overexpression could be physiologically significant and clinically relevant in TNBC patients. Notably, combination of core fucosylation inhibitor 2F-Fuc and anti-PDL1 results in enhanced therapeutic efficacy in B7H3-positive TNBC tumors. These suggest targeting FUT8-B7H3 axis can be a promising strategy for improving anti-tumor immune responses in TNBC patients. To obtain the direct evidence that B7H3 is N-glycosylated in TNBC cells, we analysed the peptides of purified human B7H3 protein from B7H3-WT re-expressed and B7H3-8NQ re-expressed MDA-MB-231 cell lines by Nanoscale liquid chromatography coupled to tandem MS (nano LC-MS/MS). The result showed that there were eight N-glycosylation sites (Asn positions 91, 104, 189, 215, 309, 322, 407, and 433) in B7H3-WT cells, but not in B7H3-8NQ cells, as determined by Asn to Asp conversion after PNGase F treatment. As B7H3 contains a nearly exact tandem duplication of the IgV-IgC domain, there were four pairs of N-glycosylation sites identified through identical peptide sequence, including N91 and N309, N104 and N322, N189 and N407, and N215 and N433, in each of the IgV-IgC domains. Together, the results indicate that B7H3 is exclusively N-glycosylated at these four pairs of glycosylation sites in TNBC cells.
HostingRepository	PRIDE
AnnounceDate	2021-03-15
AnnouncementXML	Submission_2021-03-14_23:40:41.661.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Kai Yu
SpeciesList	scientific name: Homo sapiens (Human); NCBI TaxID: 9606;
ModificationList	(18)O label at both C-terminal oxygens; deamidated residue
Instrument	Q Exactive HF

Revision	Datetime	Status	ChangeLog Entry
0	2021-03-11 02:20:43	ID requested
⏵ 1	2021-03-14 23:40:42	announced

Dataset with its publication pending

submitter keyword: breast cancer,Glycosites,B7H3

Rong Deng
contact affiliation	State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
contact email	dengrong@sysucc.org.cn
lab head
Kai Yu
contact affiliation	SYSUCC
contact email	yukai@sysucc.org.cn
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD024672
     1. Label: PRIDE project
     2. Name: Indentification of B7H3 WT/NQ N-Glycosites