Genome-wide CRISPR screen identifies synthetic lethality between DOCK1 inhibition and metformin in liver cancer

Junru Feng,Hongying Yang,Weidong Jia,Jiaqian Feng,Zhuan Lu,Hui Lu,Kun Qu,Jiazhong Deng,Yuchen Sun,Ping Gao,Ying Shu,Yongping Cai,Huafeng Zhang,Zilong Zhou,Wenhao Ma,Wenjing Tian,Pengfei Cai

doi:10.1007/s13238-022-00906-6

Abstract

Metformin is currently a strong candidate anti-tumor agent in multiple cancers. However, its anti-tumor effectiveness varies among different cancers or subpopulations, potentially due to tumor heterogeneity. It thus remains unclear which hepatocellular carcinoma (HCC) patient subpopulation(s) can benefit from metformin treatment. Here, through a genome-wide CRISPR-Cas9-based knockout screen, we find that DOCK1 levels determine the anti-tumor effects of metformin and that DOCK1 is a synthetic lethal target of metformin in HCC. Mechanistically, metformin promotes DOCK1 phosphorylation, which activates RAC1 to facilitate cell survival, leading to metformin resistance. The DOCK1-selective inhibitor, TBOPP, potentiates anti-tumor activity by metformin in vitro in liver cancer cell lines and patient-derived HCC organoids, and in vivo in xenografted liver cancer cells and immunocompetent mouse liver cancer models. Notably, metformin improves overall survival of HCC patients with low DOCK1 levels but not among patients with high DOCK1 expression. This study shows that metformin effectiveness depends on DOCK1 levels and that combining metformin with DOCK1 inhibition may provide a promising personalized therapeutic strategy for metformin-resistant HCC patients.

Highlights

Liver cancer represents a fourth common cause of cancerrelated deaths worldwide (Bray et al 2018)
The results indicated that most genes, as well as non-targeting control sgRNAs, showed similar scores between the control and metformin treatment groups (Fig. S1A)
Considering that dedicator of cytokinesis 1 (DOCK1) is a canonical guanine nucleotide exchange factor (GEF) for RAC family small GTPases which can promote the activation of RAC (Kiyokawa et al 1998; Brugnera et al 2002), we focused on the RAC family small GTPase signal transduction pathway

Summary

Introduction

Liver cancer represents a fourth common cause of cancerrelated deaths worldwide (Bray et al 2018). Each data point represents a liver cancer cell line. (I) Colony formation assay in the indicated Huh cell lines with or without 2 mmol/L metformin treatment (Top). Cell number were quantified and DOCK1 levels were determined by Western blot (Bottom). For (D), (G), (H), (I), data are presented as mean ± SD

Methods

Results

Conclusion