Genome-scale CRISPR-Cas9 screen reveals novel regulators of B7-H3 in tumor cells.

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.

• Authors: Shasha Zhao, Yuelong Wang, Nian Yang, Min Mu, Zhiguo Wu, Hexian Li, Xin Tang, Kunhong Zhong, Zongliang Zhang, Cheng Huang, Ting Cao, Meijun Zheng, Guoqing Wang, Chunlai Nie, Hui Yang, Gang Guo, Liangxue Zhou, Xi Zheng, Aiping Tong
• Journal: Journal for immunotherapy of cancer (J Immunother Cancer) Vol. 10 Issue 6 (06 2022) ISSN: 2051-1426 [Electronic] England
• PMID: 35768165 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Chemical References

• B7 Antigens
• CD276 protein, human
• Eukaryotic Initiation Factor-4E
• SUPT20H protein, human
• Transcription Factors
• p38 Mitogen-Activated Protein Kinases

Topics

• Animals
• B7 Antigens (biosynthesis, immunology)
• CRISPR-Cas Systems
• Eukaryotic Initiation Factor-4E (immunology, metabolism)
• Female
• Humans
• Mice
• Ovarian Neoplasms (drug therapy, immunology, metabolism)
• Transcription Factors (immunology, metabolism)
• Tumor Microenvironment
• p38 Mitogen-Activated Protein Kinases (immunology, metabolism)