SCCA1/SERPINB3 suppresses antitumor immunity and blunts therapy-induced T cell responses via STAT-dependent chemokine production
Liyun Chen, … , Julie K. Schwarz, Stephanie Markovina
Liyun Chen, … , Julie K. Schwarz, Stephanie Markovina
Published June 6, 2023
Citation Information: J Clin Invest. 2023;133(15):e163841. https://doi.org/10.1172/JCI163841.
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Research Article Oncology

SCCA1/SERPINB3 suppresses antitumor immunity and blunts therapy-induced T cell responses via STAT-dependent chemokine production

Abstract

Patients with cancer who have high serum levels of squamous cell carcinoma antigen 1 (SCCA1, now referred to as SERPINB3) commonly experience treatment resistance and have a poor prognosis. Despite being a clinical biomarker, the modulation of SERPINB3 in tumor immunity is poorly understood. We found positive correlations of SERPINB3 with CXCL1, CXCL8 (CXCL8/9), S100A8, and S100A9 (S100A8/A9) myeloid cell infiltration through RNA-Seq analysis of human primary cervical tumors. Induction of SERPINB3 resulted in increased CXCL1/8 and S100A8/A9 expression, which promoted monocyte and myeloid-derived suppressor cell (MDSC) migration in vitro. In mouse models, Serpinb3a tumors showed increased MDSC and tumor-associated macrophage (TAM) infiltration, contributing to T cell inhibition, and this was further augmented upon radiation. Intratumoral knockdown (KD) of Serpinb3a resulted in tumor growth inhibition and reduced CXCL1 and S100A8/A expression and MDSC and M2 macrophage infiltration. These changes led to enhanced cytotoxic T cell function and sensitized tumors to radiotherapy (RT). We further revealed that SERPINB3 promoted STAT-dependent expression of chemokines, whereby inhibition of STAT activation by ruxolitinib or siRNA abrogated CXCL1/8 and S100A8/ A9 expression in SERPINB3 cells. Patients with elevated pretreatment SCCA levels and high phosphorylated STAT3 (p-STAT3) had increased intratumoral CD11b+ myeloid cells compared with patients with low SCCA levels and p-STAT3, who had improved overall survival after RT. These findings provide a preclinical rationale for targeting SERPINB3 in tumors to counteract immunosuppression and improve the response to RT.

Authors

Liyun Chen, Victoria Shi, Songyan Wang, Lulu Sun, Rebecca Freeman, Jasmine Yang, Matthew J. Inkman, Subhajit Ghosh, Fiona Ruiz, Kay Jayachandran, Yi Huang, Jingqin Luo, Jin Zhang, Pippa Cosper, Clifford J. Luke, Catherine S. Spina, Perry W. Grigsby, Julie K. Schwarz, Stephanie Markovina

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Figure 4

Cytotoxic T cells from SERPINB3 tumors display impaired proliferation and exhausted phenotypes.

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Cytotoxic T cells from SERPINB3 tumors display impaired proliferation an...
Cumulative data from FACS analysis of (A) CD3+CD8+ T cells and (B) CD3+CD4+ T cells in tumors. (C) The ratio of CD8+ T cells/Tregs represented the infiltrating percentage of CD8+ T cells relative to CD4+CD25+FoxP3+ Tregs. (D) Frequencies of Ki-67+CD8+ T cells in the total infiltrating CD8+ T cell population were analyzed by flow cytometry. (E and F) Intratumoral T cells were stimulated with phorbol 12-myristate 13-acetate (PMA)/ionomycin for 5 hours, and the expression of IFN-γ and TNF-α was assessed by intracellular staining via flow cytometry. The protein transport inhibitor brefeldin A was used to block the protein transport processes and cytokine release. Positive expression was normalized to cells without PMA/ionomycin stimulation (basal levels). Box plot whiskers span the minimum and maximum values, and lines represent the median. (G) CellTrace-labeled intratumoral T cells were stimulated with anti-CD3/anti-CD28 antibody for 4 days, and cell proliferation was determined by the dilution of CellTrace. (H) PD-1 and CTLA-4 expression was examined by flow cytometry and is shown as MFI. Data are shown as the mean ± SEM, and each dot represents a biologically independent sample. Asterisks indicate comparisons between LL2/Ctrl and LL2/B3a; cross symbols indicate comparisons between sham- and RT-treated animals. *,†P < 0.05, **,††P < 0.01, and ***P < 0.001, by 1-way ANOVA with Tukey’s post hoc test.