# ASF1B promotes gastric cancer liver metastasis through inhibiting ZDHHC9/PCBP1/ SLC7A11 signaling axis mediated ferroptosis

## TL;DR

This study identifies a molecular pathway involving ASF1B and other proteins that promotes liver metastasis in gastric cancer by preventing a type of cell death called ferroptosis.

## Contribution

The study reveals a novel signaling axis (ASF1B/ZDHHC9/PCBP1/SLC7A11) that inhibits ferroptosis and promotes gastric cancer liver metastasis.

## Key findings

- ASF1B promotes liver metastasis by inhibiting SLC7A11-mediated ferroptosis.
- ZDHHC9 palmitoylates PCBP1 at C109, suppressing its ubiquitination and ferroptosis.
- The signaling axis is clinically correlated with PD-L1 expression in gastric cancer.

## Abstract

Identifying potential molecular targets for GC liver metastasis (GCLM) may provide new treatment avenues. Initially, using label-free proteomics to screen clinical samples from GCLM patients suggested ASF1B as a possible promoter of GCLM. We further validated this finding with in vitro experiments and spleen injection liver metastasis model, subsequent transcriptome sequencing after ASF1B knockdown revealed SLC7A11-mediated ferroptosis is critical for GCLM progression. Mechanistically, ASF1B recruits and binds to the transcription factor HOXB3, thereby promoting ZDHHC9’s transcriptional level. Additionally, ZDHHC9 regulates SLC7A11-mediated ferroptosis in GC cells. Further tumor metastasis assays showed ZDHHC9 promotes peritoneal, pulmonary, and hepatic metastases in GC. Subsequently, immunoprecipitation and LC-MS analyses revealed the molecular interaction between ZDHHC9 and PCBP1. ZDHHC9, a palmitoyltransferase, inhibits ferroptosis by palmitoylating PCBP1. Mechanistically, ZDHHC9 palmitoylates PCBP1 at residue C109, inhibiting PCBP1 ubiquitination and thereby suppressing SLC7A11-mediated ferroptosis. In line with this, further experiments showed PCBP1 regulates ferroptosis by modulating SLC7A11 RNA stability. Finally, IHC and immunofluorescence revealed significant clinical correlations among ASF1B, ZDHHC9, PCBP1, and SLC7A11. Additionally, this signaling axis is strongly associated with PD-L1 expression. In conclusion, this study demonstrates ASF1B promotes GC liver metastasis by inhibiting ferroptosis via the ZDHHC9/PCBP1/SLC7A11 axis, providing a potential immunotherapeutic target for GCLM.