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

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.

ARHGAP24 represses β-catenin transactivation-induced invasiveness in hepatocellular carcinoma mainly by acting as a GTPase-independent scaffold

“…For instance, Feng et al found that RASAL2 promoted small GTPase Rac1 signaling, which could bind and antagonize the Rac1-GAP protein ARHGAP24 in breast cancer 14 . Interestingly, the highly metastatic HCCLM3 HCC cell line was reported to show high RhoGEF expression (DOCK1, IQGAP1) 34 - 35 , which might activate Rac1 and maintain GTP-bound Rac1 at a high level regardless of ARHGAP24 overexpression. On the other hand, modulation of ARHGAP24 expression might break the intracellular balance among RhoGEF, RhoGAP and RhoGDIs in Huh7 and Li-7 cells, resulting in alteration of Rac1 activity.…”

The biological essence of synthetic lethality: Bringing new opportunities for cancer therapy

“…In this condition-dependent SL interaction, genetic factors alone may not necessarily result in a synthetic lethal effect. [166][167][168] For example, some SL-based therapies have modest effects on viability in cell culture in vitro, but exhibit antiproliferative activity in mouse and zebrafish models. Among these external factors, TEM, which includes other immune cells, hormones, nutrients, hypoxia, high ROS, pH, and osmolality, may influence the strength of synthetic lethal therapeutic effects.…”

“…In addition to the genetic background mentioned above, certain external conditions, such as the heterogeneity of the tumor cells, the microenvironment, and other external interferences, are required to eventually realize SL. In this condition‐dependent SL interaction, genetic factors alone may not necessarily result in a synthetic lethal effect 166–168 . For example, some SL‐based therapies have modest effects on viability in cell culture in vitro, but exhibit antiproliferative activity in mouse and zebrafish models.…”

Neoantigen cancer vaccines: a new star on the horizon

“…A PDO model with immunocompetent microenvironments was established to conduct T cell cytotoxicity assays for neoantigen vaccines with the aim of improving the precision in identifying neoantigen vaccines that elicit an immune response ( Figure 2 ). This framework provides a robust platform for screening and validating neoantigen candidates, ultimately leading to the development of personalized vaccines with high immunogenicity and potent tumor-killing capabilities for clinical applications ( Figure 2 ) 184 , 192 .…”