Immunotherapy can elicit robust anticancer responses in the clinic. However, a large proportion of patients with colorectal cancer do not benefit from treatment. Although previous studies have shown that hydrogen sulfide (H2S) is involved in colorectal cancer development and immune escape, further insights into the mechanisms and related molecules are needed to identify approaches to reverse the tumor-supportive functions of H2S. Here, we observed significantly increased H2S levels in colorectal cancer tissues. Decreasing H2S levels by using CBS+/− mice or feeding mice a sulfur amino acid-restricted diet (SARD) led to a marked decrease in differentiated CD4+CD25+Foxp3+ Tregs and an increase in the CD8+ T-cell/Treg ratio. Endogenous or exogenous H2S depletion enhanced the efficacy of anti–PD-L1 and anti–CTLA4 treatment. H2S promoted Treg activation through the persulfidation of ENO1 at cysteine 119. Furthermore, H2S inhibited the migration of CD8+ T cells by increasing the expression of AAK-1 via ELK4 persulfidation at cysteine 25. Overall, reducing H2S levels engenders a favorable immune microenvironment in colorectal cancer by decreasing the persulfidation of ENO1 in Tregs and ELK4 in CD8+ T cells. SARD represents a potential dietary approach to promote responses to immunotherapies in colorectal cancer. Significance: H2S depletion increases the CD8+ T-cell/Treg ratio and enhances the efficacy of anti–PD-L1 and anti–CTLA4 treatment in colon cancer, identifying H2S as an anticancer immunotherapy target.

Increased xCT and transsulfuration pathway has been associated with metabolic reprogramming of colorectal cancer. However, the correlation between these 2 events and the underlying molecular mechanism remains obscure. xCT expression was determined in tissue microarrays of colorectal cancer. RNA sequencing and functional assays in vitro was adopted to delineate the involvement of transsulfuration pathway in the proper function of xCT in maintaining the chemoresistant phenotype. The synthetic lethality of blocking xCT and the transsulfuration pathway was investigated both in vitro and in vivo. The up-regulation of the transsulfuration pathway after inhibiting xCT in colon cancer cells was evident and exogenous H2S partially reversed the loss of chemoresistance phenotype after inhibiting xCT. Mechanistically, CTH derived H2S increased the stability of xCT through persulfidation of OTU domain-containing ubiquitin aldehyde-binding protein 1 at cysteine 91. AOAA and Erastin resulted in synthetic lethality both in vitro and in vivo, which was mediated through increased ferroptosis and apoptosis. Our findings suggest that a reciprocal regulation exists between xCT and the transsulfuration pathway, which is a targetable metabolic vulnerability. Mechanistically, CTH derived H2S increased the stability of xCT through persulfidation of OTU domain-containing ubiquitin aldehyde-binding protein 1 at cysteine 91.

Cancer-associated fibroblasts (CAFs) play important roles in tumor progression. However, the behaviors of activated CAFs in gastric cancer remain to be determined. The aim of the present study was to investigate the correlations between activated gastric CAFs and the prognosis of patients with gastric cancer, and to determine the effects of activated CAFs on the malignant phenotype and 5-fluorouracil resistance in this cancer. Ninety-five patients with primary gastric cancer were enrolled in this study. Activation states of gastric CAFs were evaluated by immunohistochemistry. A modified method for the primary culture of gastric CAFs was employed. Types of CAFs and activation states were identified by immunocytochemical and immunofluorescent staining. Cell co-culture and gastric CAF conditioned medium transfer models were established to investigate the paracrine effects of activated CAFs on the migration and invasion of gastric cell lines. The half maximal inhibitory concentration of 5-fluorouracil and levels of cell apoptosis were examined using cell viability assay and flow cytometry, respectively. Protein expression levels of associated molecules were measured by Western blotting. Kaplan–Meier survival curves showed that activated gastric CAFs identified via fibroblast activation protein were significantly related to poorer cumulative survival in gastric cancer patients. Five strains of CAFs were successfully cultured via the modified culture method, and three gastric CAFs strains were identified as activated gastric CAFs. The migration and invasion abilities of gastric cells were significantly enhanced in both the co-culture group and the conditioned medium group. The half maximal inhibitory concentration for 5-fluorouracil in BGC-823 cells was elevated after treatment with conditioned medium, and early apoptosis was inhibited. Additionally, an obvious elevation of epithelial–mesenchymal transition level was observed in the conditioned medium group. Activated gastric CAFs correlate with a poor prognosis of cancer patients and may contribute to the malignant phenotype and the development of resistance to 5-fluorouracil via paracrine action in gastric cancer. Gastric CAFs with a specific activation state might be used as a tumor biomarker within the microenvironment for prognosis and as a new therapeutic target for chemoresistant gastric cancer.

The aim of the present study was to clarify the correlations between SPARC expression in gastric cancer-associated fibroblasts (GCAFs) and the prognosis of patients with gastric cancer and to elucidate the role of GCAF-derived SPARC in stemness transformation and 5-fluorouracil resistance in gastric cancer. One hundred ninety-two patients were enrolled in the present study. SPARC expression levels were evaluated by immunohistochemical staining. Primary GCAFs were obtained and cultured from cancer patients for in vitro study, and a lentivirus infection method was employed to knock down SPARC expression in GCAFs. The stemness phenotype and 5-fluorouracil (5-FU) response of gastric cancer cells were assessed via a 3D co-culture model. The apoptotic status and stemness alterations were monitored by flow cytometry and western blotting. Additionally, label-free quantification proteomics was used to identify the differentially expressed proteins and potential pathways in gastric cancer cells treated with GCAF-derived SPARC. Low expression of GCAF-derived SPARC was associated with decreased differentiation and reduced 5-year overall survival and was an independent predictive factor for prognosis in gastric cancer. The 3D tumour growth and 5-FU resistance abilities of gastric cancer cells were elevated after treatment with GCAFs with SPARC knockdown relative to these abilities in negative control cells. Additionally, suppressing SPARC expression in GCAFs facilitated the phenotypic alteration of gastric cancer cells towards CD44+/CD24− cancer stem cell (CSC)-like cells. Quantification proteomics analysis revealed that the differentially expressed proteins in gastric cancer cells were mainly involved in the AKT/mTOR and MEK/ERK signalling pathways. SPARC expression in GCAFs is a useful prognostic factor in patients with gastric cancer. Low expression of GCAF-derived SPARC can lead to CSC transformation and 5-FU resistance. Additionally, the AKT/mTOR and MEK/ERK signalling pathways may participate in the malignant process.

We assessed the rapid on-line evaluation (ROLE) protocol as a modification to the conventional rapid on-site evaluation (ROSE) in the diagnostic performance improvement in endoscopic ultrasound-guided tissue acquisition (EUS-TA) for solid pancreatic lesions. This single-center, retrospective study involved consecutive patients with solid pancreatic lesions undergoing EUS-TA at Peking University First Hospital between October 2017 and March 2021. Among 137 patients enrolled, 75 were in the ROLE group and 62 were in the non-ROSE group. The diagnostic yield (97.3% vs. 85.5%, p = 0.023), accuracy (94.7% vs. 82.3%, p = 0.027), and sensitivity (95.7% vs. 81.1%, p = 0.011) were significantly higher in the ROLE group compared to the non-ROSE group. However, specificity, positive predictive value, negative predictive value, and area under the curve (AUC) showed no significant differences (all p-values > 0.05). Additionally, there was a noteworthy reduction in the number of needle passes required in the ROLE group compared to the non-ROSE group (two vs. three, p < 0.001). In a subgroup analysis, fine needle biopsy (FNB) combined with ROLE demonstrated superior diagnostic accuracy compared to FNB with non-ROSE (100% vs. 93.1%, p = 0.025). Compared with the non-ROSE protocol, the ROLE protocol might improve the diagnostic performance of EUS-TA for solid pancreatic lesions, and potentially reduce the number of needle passes requirement.

Background. Colorectal cancer (CRC) is the second most common cause of cancer death in the United States and the third most common cancer globally. The incidence of CRC tends to be younger, and we urgently need a reliable prognostic assessment strategy. Methods. Protein expression profile and clinical information of 390 CRC patients/samples were downloaded from the TCPA and TCGA database, respectively. The Kaplan‐Meier, Cox regression, and Pearson correlation analysis were applied in this study. Results. Based on the TCPA and TCGA database, we screened 6 hub proteins and first constructed protein risk signature, all of which were significantly associated with CRC patients’ overall survival (OS). The risk score was an independent prognostic factor and significantly related with the size of the tumor in situ (T). 6 hub proteins were differentially expressed in cancer and normal tissues and in different CRC stages, which were validated at the ONCOMINE database. Next, 40 coexpressed proteins of 6 hub proteins were extracted from the TCPA database. In the protein‐protein interaction (PPI) network, HER1, HER2, and CTNNB1 were at the center. Function enrichment analysis illustrated that 46 proteins were mainly involved in the EGFR (HER1) tyrosine kinase inhibitor resistance pathway. Conclusion. Studies indicated that 6 hub proteins might be considered as new targets for CRC therapies, and the protein risk signature can be used to predict the OS of CRC patients.