Non-alcoholic fatty liver disease promotes liver metastasis of colorectal cancer via fatty acid synthase dependent EGFR palmitoylation.

Liver metastasis is the major reason for most of colorectal cancer (CRC) related deaths. Accumulating evidence indicates that CRC patients with non-alcoholic fatty liver disease (NAFLD) are at a greater risk of developing liver metastasis. With the growing prevalence of NAFLD, a better understanding of the molecular mechanism in NAFLD-driven CRC liver metastasis is needed. In this study, we demonstrated that NAFLD facilitated CRC liver metastasis as a metabolic disorder and promoted the stemness of metastatic CRC cells for their colonization and outgrowth in hepatic niches. Metabolically, the lipid-rich microenvironment in NAFLD activated de novo palmitate biosynthesis in metastatic CRC cells via upregulating fatty acid synthase (FASN). Moreover, increased intracellular palmitate bioavailability promoted EGFR palmitoylation to enhance its protein stability and plasma membrane localization. Furthermore, we demonstrated that the FDA-approved FASN inhibitor orlistat could reduce NAFLD-activated endogenous palmitate production, thus inhibiting palmitoylation of EGFR to suppress CRC cell stemness and restrict liver metastasis in synergy with conventional chemotherapy. These findings reveal that the NAFLD metabolic microenvironment boosts endogenous palmitate biosynthesis in metastatic CRC cells and promotes cell stemness via EGFR palmitoylation, and FASN inhibitor orlistat could be a candidate adjuvant drug to suppress liver metastasis in CRC patients with NAFLD.

Deubiquitinase OTUB2 promotes intrahepatic cholangiocarcinoma progression by stabilizing the CTNNB1-ZEB1 axis.

Aberrant regulation of ubiquitination is an essential fundamental process in tumors, especially intrahepatic cholangiocarcinoma (iCCA). We reported that OTUB2, an OTU deubiquitinase, is upregulated in iCCA and stabilizes the CTNNB1-ZEB1 axis, resulting in epithelial-mesenchymal transition (EMT) and iCCA metastasis. Mechanistically, OTUB2 promotes CTNNB1 expression by interacting with the E3 ligase TRAF6. OTUB2 inhibits the lysosomal degradation of CTNNB1 by interacting with TRAF6 and thus regulates the progression of iCCA through ZEB1. Clinically, high OTUB2 expression is related to increased ZEB1 expression and activity and reduced overall survival in iCCA patients. Therefore, advanced iCCA patients may benefit from drugs targeting OTUB2 and its pathway.

Ultrasound combined with nanobubbles promotes systemic anticancer immunity and augments anti-PD1 efficacy.

BACKGROUND: The poor immunogenicity of solid tumors limits the efficacy ofanti-programmed cell death protein 1 (anti-PD1)-based immune checkpoint blockade (ICB); thus, less than 30% of patients with cancer exhibit a response. Currently, there is still a lack of effective strategies for improving tumor immunogenicity. METHODS: The antitumor effect of ultrasound-stimulated nanobubbles (USNBs) alone and in combination with an anti-PD1 antibody was evaluated in RM1 (prostate cancer), MC38 (colon cancer) and B16 (melanoma) xenograft mouse models. The phenotypes of antigen-presenting cells and CD8+ T cells were evaluated by flow cytometry. Damage-associated molecular pattern (DAMP) release, antigen release and tumor cell necrosis were assessed via western blot, flow cytometry, transmission electron microscopy and confocal microscopy. RESULTS: USNB promoted the infiltration and antitumor activity of CD8+ T cells. The combination of USNB and anti-PD1 blockade improved systemic antitumor immunity and resulted in an abscopal effect and long-term immune memory protection after complete tumor remission. Mechanistically, tumor-targeting USNB induced tumor cell necrosis through an ultrasound-mediated cavitation effect, which significantly increased DAMP release and tumor antigen presentation, consequently sensitizing tumors to ICB treatment. CONCLUSION: The administration of USNB increased tumor immunogenicity by remodeling the tumor-immune microenvironment, providing a promising strategy for sensitizing poorly immunogenic solid tumors to immunotherapy in the clinic.