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Genome-wide CRISPR screening identifies tyrosylprotein sulfotransferase-2 as a target for augmenting anti-PD1
Yumi Oh1, Sujeong Kim2, Yunjae Kim2
1Medical Research Center, Genomic Medicine Institute, Seoul National University College of Medicine, Seoul, 03080, Korea.
Background:
Immune checkpoint therapy (ICT) provides durable responses in select cancer patients, yet resistance remains a significant challenge, prompting the exploration of underlying molecular mechanisms. Tyrosylprotein sulfotransferase-2 (TPST2), known for its role in protein tyrosine O-sulfation, has been suggested to modulate the extracellular protein-protein interactions, but its specific role in cancer immunity remains largely unexplored.
Methods:
To explore tumor cell-intrinsic factors influencing anti-PD1 responsiveness, we conducted a pooled loss-of-function genetic screen in humanized mice engrafted with human immune cells. The responsiveness of cancer cells to interferon-γ (IFNγ) was estimated by evaluating IFNγ-mediated induction of target genes, STAT1 phosphorylation, HLA expression, and cell growth suppression. The sulfotyrosine-modified target gene of TPST2 was identified by co-immunoprecipitation and mass spectrometry. The in vivo effects of TPST2 inhibition were evaluated using mouse syngeneic tumor models and corroborated by bulk and single-cell RNA sequencing analyses.
Results:
Through in vivo genome-wide CRISPR screening, TPST2 loss-of-function emerged as a potential enhancer of anti-PD1 treatment efficacy. TPST2 suppressed IFNγ signaling by sulfating IFNγ receptor 1 at Y397 residue, while its downregulation boosted IFNγ-mediated signaling and antigen presentation. Depletion of TPST2 in cancer cells augmented anti-PD1 antibody efficacy in syngeneic mouse tumor models by enhancing tumor-infiltrating lymphocytes. RNA sequencing data revealed TPST2's inverse correlation with antigen presentation, and increased TPST2 expression is associated with poor prognosis and altered cancer immunity across cancer types.
Conclusions:
We propose TPST2's novel role as a suppressor of cancer immunity and advocate for its consideration as a therapeutic target in ICT-based treatments.
Insights
Tyrosylprotein sulfotransferase-2 (TPST2) suppresses cancer immunity by inhibiting interferon-gamma (IFNγ) signaling. Its inhibition enhances anti-PD1 therapy efficacy by boosting immune cell infiltration and antigen presentation, suggesting TPST2 as a therapeutic target.
Area of Science:
- Cancer immunology
- Molecular oncology
- Protein sulfation
Background:
- Immune checkpoint therapy (ICT) offers durable responses but faces resistance challenges, necessitating investigation into underlying molecular mechanisms.
- Tyrosylprotein sulfotransferase-2 (TPST2) is implicated in protein tyrosine O-sulfation and extracellular interactions, but its role in cancer immunity is largely unknown.
Purpose of the Study:
- To identify tumor cell-intrinsic factors influencing responsiveness to anti-PD1 therapy.
- To elucidate the specific role of TPST2 in modulating cancer immunity and anti-PD1 treatment efficacy.
Main Methods:
- Conducted a pooled loss-of-function CRISPR screen in humanized mice engrafted with human immune cells to identify factors affecting anti-PD1 response.
- Assessed cancer cell responsiveness to interferon-gamma (IFNγ) by measuring gene induction, STAT1 phosphorylation, HLA expression, and growth suppression.
- Utilized co-immunoprecipitation, mass spectrometry, mouse syngeneic tumor models, and bulk/single-cell RNA sequencing to analyze TPST2 function and effects.
Main Results:
- Loss of TPST2 enhanced anti-PD1 treatment efficacy by suppressing IFNγ signaling through sulfation of IFNγ receptor 1 (Y397).
- TPST2 depletion boosted IFNγ-mediated signaling, antigen presentation, and tumor-infiltrating lymphocytes, augmenting anti-PD1 antibody efficacy in vivo.
- TPST2 expression inversely correlated with antigen presentation and was associated with poor prognosis and altered cancer immunity across various cancer types.
Conclusions:
- TPST2 acts as a novel suppressor of cancer immunity.
- Targeting TPST2 represents a potential therapeutic strategy to enhance immune checkpoint therapy outcomes.
