Bile acids inhibit ferroptosis sensitivity through activating farnesoid X receptor in gastric cancer cells

BACKGROUND

Gastric cancer (GC) is associated with high mortality rates. Bile acids (BAs) reflux is a well-known risk factor for GC, but the specific mechanism remains unclear. During GC development in both humans and animals, BAs serve as signaling molecules that induce metabolic reprogramming. This confers additional cancer phenotypes, including ferroptosis sensitivity. Ferroptosis is a novel mode of cell death characterized by lipid peroxidation that contributes universally to malignant progression. However, it is not fully defined if BAs can influence GC progression by modulating ferroptosis.

AIM

To reveal the mechanism of BAs regulation in ferroptosis of GC cells.

METHODS

In this study, we treated GC cells with various stimuli and evaluated the effect of BAs on the sensitivity to ferroptosis. We used gain and loss of function assays to examine the impacts of farnesoid X receptor (FXR) and BTB and CNC homology 1 (BACH1) overexpression and knockdown to obtain further insights into the molecular mechanism involved.

RESULTS

Our data suggested that BAs could reverse erastin-induced ferroptosis in GC cells. This effect correlated with increased glutathione (GSH) concentrations, a reduced GSH to oxidized GSH ratio, and higher GSH peroxidase 4 (GPX4) expression levels. Subsequently, we confirmed that BAs exerted these effects by activating FXR, which markedly increased the expression of GSH synthetase and GPX4. Notably, BACH1 was detected as an essential intermediate molecule in the promotion of GSH synthesis by BAs and FXR. Finally, our results suggested that FXR could significantly promote GC cell proliferation, which may be closely related to its anti-ferroptosis effect.

CONCLUSION

This study revealed for the first time that BAs could inhibit ferroptosis sensitivity through the FXR-BACH1-GSH-GPX4 axis in GC cells. This work provided new insights into the mechanism associated with BA-mediated promotion of GC and may help identify potential therapeutic targets for GC patients with BAs reflux.

[Quantitative evaluation of intravoxel incoherent motion diffusion-weighted imaging and three-dimensional arterial spin labeling in Ki-67 labeling index and grading of brain gliomas]

Objective: To investigate the value of multiple parameters derived from intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and three-dimensional arterial spin labeling (3D-ASL) in Ki-67 labeling index (Ki-67 LI) and grading of human brain gliomas. Methods: From December 2015 to May 2018, 45 patients of gliomas confirmed by surgical pathology in Li Huili Hospital, Ningbo Medical Center were divided into low-grade group (20 cases of WHO grade Ⅱ) and high-grade group (12 cases of WHO grade Ⅲ, 13 cases of WHO grade Ⅳ), and the Ki-67 LI of glioma was obtained by immunohistochemistry. All patients, 24 males and 21 females, aged 25-83 years, mean(53±12)years, underwent conventional magnetic resonance imaging (MRI), IVIM-DWI and 3D-ASL before operation, then measured the true water diffusion coefficient (D), microcirculation perfusion coefficient (D(*)), perfusion fraction (f) and cerebral blood flow (CBF) in the tumor solid area and the contralateral normal white matter area. Those parameters and the Ki-67 LI were compared between the low-and high-grade groups with Mann-Whitney U test. Spearman's correlation was used to analyze the correlation between the quantitative parameters and Ki-67 LI. The ROC curve was used to assess the diagnostic efficacy of parameters in the grading assessment of brain gliomas. Results: The D(0.791×10(-3)mm(2)/s) and f (0.261) of the high-grade group were lower than those of the low-grade group, whereas D(*) (4.153×10(-3) mm(2)/s), CBF(102.027 ml·min(-1)·100 g(-1)) and Ki-67 LI (0.25) were higher (P<0.05). There was a moderate negative correlation between D, f and Ki-67 LI(r=-0.513,-0.457, all P<0.05). There was no significant correlation between D(*) and Ki-67 LI (P=0.571). The area under the curve (AUC) for identifying high-and low-grade gliomas by D, D(*), f and CBF values was 0.965, 0.745, 0.842, and 0.830 respectively (all P<0.05). Conclusion: D and f can be used for quantitative prediction of Ki-67 LI. IVIM-DWI and 3D-ASL are helpful in the grading assessment of gliomas, and the diagnostic efficiency of D is the highest.