Genome-scale CRISPR–Cas9 screen reveals novel regulators of B7-H3 in tumor cells. Issue 6 (29th June 2022)

• Record Type: Journal Article
• Authors: Zhao, Shasha; Wang, Yuelong; Yang, Nian; Mu, Min; Wu, Zhiguo; Li, Hexian; Tang, Xin; Zhong, Kunhong; Zhang, Zongliang; Huang, Cheng; Cao, Ting; Zheng, Meijun; Wang, Guoqing; Nie, Chunlai; Yang, Hui; Guo, Gang; Zhou, Liangxue; Zheng, Xi; Tong, Aiping
• Is Part Of: Journal for immunotherapy of cancer. Volume 10:Issue 6(2022)
• Publication Date: 2022-06-29
• Subjects: immunotherapy -- antigenic modulation -- tumor biomarkers; Cancer -- Immunotherapy -- Periodicals; Cancer -- Immunological aspects -- Periodicals; Tumors -- Immunological aspects -- Periodicals; Immunotherapy -- Periodicals; 616.99406105
• DOI: 10.1136/jitc-2022-004875
• Languages: English
• ISSNs: 2051-1426

Abstract

Abstract : Background: Despite advances in B7 homolog 3 protein (B7-H3) based immunotherapy, the development of drug resistance remains a major clinical concern. The heterogeneity and emerging loss of B7-H3 expression are the main causes of drug resistance and treatment failure in targeted therapies, which reveals an urgent need to elucidate the mechanism underlying the regulation of B7-H3 expression. In this study, we identified and explored the crucial role of the transcription factor SPT20 homolog (SP20H) in B7-H3 expression and tumor progression. Methods: Here, we performed CRISPR/Cas9-based genome scale loss-of-function screening to identify regulators of B7-H3 in human ovarian cancer cells. Signaling pathways altered by SP20H knockout were revealed by RNA sequencing. The regulatory role and mechanism of SP20H in B7-H3 expression were validated using loss-of-function and gain-of-function assays in vitro. The effects of inhibiting SP20H on tumor growth and efficacy of anti-B7-H3 treatment were evaluated in tumor-bearing mice. Results: We identified SUPT20H (SP20H) as negative and eIF4E as positive regulators of B7-H3 expression in various cancer cells. Furthermore, we provided evidence that either SP20H loss or TNF-α stimulation in tumor cells constitutively activates p38 MAPK-eIF4E signaling, thereby upregulating B7-H3 expression. Loss of SP20H upregulated B7-H3 expression both in vitro and in vivo. Additionally, deletion of SP20H significantly suppressed tumor growth and increased immune cells infiltration in tumor microenvironment. More importantly, antibody–drug conjugates targeting B7-H3 exhibited superior antitumor performance against SP20H-deficient tumors relative to control groups. Conclusions: Activation of p38 MAPK-eIF4E signaling serves as a key event in the transcription initiation and B7-H3 protein expression in tumor cells. Genetically targeting SP20H upregulates target antigen expression and sensitizes tumors to anti-B7-H3 treatment. Collectively, our findings provide new insight into the mechanisms underlying B7-H3 expression and introduce a potential synergistic target for existing antibody-based targeted therapy against B7-H3.