SCCA1/SERPINB3 suppresses antitumor immunity and blunts therapy-induced T cell responses via STAT-dependent chemokine production
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
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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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 8

Elevated serum SCCA levels and high tumor p-STAT3 are associated with CD11b expression and poor cancer-specific survival after CRT.

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Elevated serum SCCA levels and high tumor p-STAT3 are associated with CD...
(A and B) Quantification of immunostaining for p-STAT3 and CD11b expression in mouse tumors treated with siNC or siB3. Box plots show p-STAT3 staining scores and the percentage of CD11b+ staining from 8–12 representative fields each for 6–7 mice per group. Box plot whiskers span the minimum and maximum values; lines represent the median. (C) Kaplan-Meier plot shows overall survival for patients with serum SCCA levels below 9.16 ng/mL and a p-STAT3 histoscore below 100 (n = 30) or of 100 or higher (n = 21), compared with patients with serum SCCA levels of 9.16 ng/mL or higher with a p-STAT3 histoscore below 100 (n = 6) or of 100 or higher (n = 15). The average pretreatment serum SCCA value of 9.16 ng/mL from 72 patients with cancer was used as a cutoff. L, low; H, high. (D) Representative images of p-STAT3 and CD11b staining for patients with SCCA levels below 9.16 ng/mL or of 9.16 ng/mL or higher. Scale bars: 100 μm, 200 μm, and 500 μm. (E) p-STAT3 staining score (histoscore) for patients with serum SCCA levels below 9.16 ng/mL versus those with SCCA levels of 9.16 ng/mL or higher. (F) Percentage of the myeloid cell marker CD11b staining in patients with serum SCCA levels below 9.16 ng/mL or of 9.16 ng/mL or higher and a p-STAT3 histoscore below 100 (low) or of 100 or higher (high). Each dot represents an individual patient. Data are shown as the mean ± SEM. A Mann-Whitney U test was used to determine statistical significance.