The G protein–coupled bile acid receptor (GPBAR) is the membrane receptor for bile acids and a driving force of the liver–bile acid–microbiota–organ axis to regulate metabolism and other pathophysiological processes. Although GPBAR is an important therapeutic target for a spectrum of metabolic and neurodegenerative diseases, its activation has also been found to be linked to carcinogenesis, leading to potential side effects. Here, via functional screening, we found that two specific GPBAR agonists, R399 and INT-777, demonstrated strikingly different regulatory effects on the growth and apoptosis of non–small cell lung cancer (NSCLC) cells both in vitro and in vivo. Further mechanistic investigation showed that R399-induced GPBAR activation displayed an obvious bias for β-arrestin 1 signaling, thus promoting YAP signaling activation to stimulate cell proliferation. Conversely, INT-777 preferentially activated GPBAR-Gs signaling, thus inactivating YAP to inhibit cell proliferation and induce apoptosis. Phosphorylation of GPBAR by GRK2 at S310/S321/S323/S324 sites contributed to R399-induced GPBAR–β-arrestin 1 association. The cryoelectron microscopy (cryo-EM) structure of the R399-bound GPBAR-Gs complex enabled us to identify key interaction residues and pivotal conformational changes in GPBAR responsible for the arrestin signaling bias and cancer cell proliferation. In summary, we demonstrate that different agonists can regulate distinct functions of cell growth and apoptosis through biased GPBAR signaling and control of YAP activity in a NSCLC cell model. The delineated mechanism and structural basis may facilitate the rational design of GPBAR-targeting drugs with both metabolic and anticancer benefits.

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Ubiquitin-specific-processing proteases 35 (USP35) is an under-characterized deubiquitinase and its role in colorectal cancer (CRC) remains unclear. Here, we focus on delineating the impact of USP35 on CRC cell proliferation and chemo-resistance, as well as the possible regulatory mechanism. By examining the genomic database and clinical samples, we found that USP35 was overexpressed in CRC. Further functional studies showed that enhanced USP35 expression promoted CRC cell proliferation and resistance to oxaliplatin (OXA) and 5-fluorouracil (5-FU), whereas USP35 depletion impeded cell proliferation and sensitized cells to OXA and 5-FU treatments. Then, to explore the possible mechanism underlying USP35-triggered cellular responses, we performed co-immunoprecipitation (co-IP) followed by mass spectrometry (MS) analysis and identified α-L-fucosidase 1 (FUCA1) as a direct deubiquitiation target of USP35. Importantly, we demonstrated that FUCA1 was an essential mediator for USP35-induced cell proliferation and chemo-resistance in vitro and in vivo. Finally, we observed that nucleotide excision repair (NER) components (e.g., XPC, XPA, ERCC1) were up-regulated by USP35-FUCA1 axis, indicating a potential mechanism for USP35-FUCA1-mediated platinum resistance in CRC. Together, our results for the first time explored the role and important mechanism of USP35 in CRC cell proliferation and chemotherapeutic response, providing a rationale for USP35-FUCA1-targeted therapy in CRC.

Ubiquitin-specific-processing proteases 35 (USP35) is an under-characterized deubiquitinase and its role in colorectal cancer (CRC) remains unclear. Here, we focus on delineating the impact of USP35 on CRC cell proliferation and chemo-resistance, as well as the possible regulatory mechanism. By examining the genomic database and clinical samples, we found that USP35 was overexpressed in CRC. Further functional studies showed that enhanced USP35 expression promoted CRC cell proliferation and resistance to oxaliplatin (OXA) and 5-fluorouracil (5-FU), whereas USP35 depletion impeded cell proliferation and sensitized cells to OXA and 5-FU treatments. Then, to explore the possible mechanism underlying USP35-triggered cellular responses, we performed co-immunoprecipitation (co-IP) followed by mass spectrometry (MS) analysis and identified α-L-fucosidase 1 (FUCA1) as a direct deubiquitiation target of USP35. Importantly, we demonstrated that FUCA1 was an essential mediator for USP35-induced cell proliferation and chemo-resistance in vitro and in vivo. Finally, we observed that nucleotide excision repair (NER) components (e.g., XPC, XPA, ERCC1) were up-regulated by USP35-FUCA1 axis, indicating a potential mechanism for USP35-FUCA1-mediated platinum resistance in CRC. Together, our results for the first time explored the role and important mechanism of USP35 in CRC cell proliferation and chemotherapeutic response, providing a rationale for USP35-FUCA1-targeted therapy in CRC.

Background: G Protein Subunit Gamma 7 (GNG7), an important regulator of cell proliferation and cell apoptosis, has been reported to be downregulated in a variety of tumors including lung adenocarcinoma (LUAD). However, the correlation between low expression of GNG7 and prognosis of LUAD as well as the immune infiltrates of LUAD remains unclear.Methods: The samples were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). R software was performed for statistical analysis. GNG7 expression and its prognostic value in LUAD were assessed through statistically analyzing the data from different databases. A nomogram was constructed to predict the impact of GNG7 on prognosis. Gene set enrichment analysis (GSEA) and single-sample gene set enrichment analyses GSEA (ssGSEA) were employed to determine the potential signal pathways and evaluated the immune cell infiltration regulated by GNG7. The prognostic significance of GNG7 expression associated with immune cell infiltration was investigated using the Tumor Immune Estimation Resource 2.0 (TIMER2.0) and the Kaplan-Meier plotter database. The UALCAN, cBio Cancer Genomics Portal (cBioPortal) and MethSurv database were used to analyze the correlation between the methylation of GNG7 and its mRNA expression as well as prognostic significance.Results: GNG7 was demonstrated to be down-regulated in LUAD and its low expression was associated with poor prognosis. A clinical reliable prognostic-predictive model was constructed. Pathway enrichment showed that GNG7 was highly related to the B cell receptor signaling pathway. Further analysis showed that GNG7 was positively associated with B cell infiltration and low levels of B cell infiltration tended to associate with worse prognosis in patients with low GNG7 expression. Moreover, methylation analysis suggested hypermethylation may contribute to the low expression of GNG7 in LUAD.Conclusion: Decreased expression of GNG7 at least partly caused by hypermethylation of the GNG7 promoter is closely associated with poor prognosis and tumor immune cell infiltration (especially B cells) in LUAD. These results suggest that GNG7 may be a promising prognostic biomarker and a potential immunotherapeutic target for LUAD, which provides new insights into immunotherapy for LUAD.