Regulation of tumor metastasis and CD8+ T cells infiltration by circRNF216/miR-576-5p/ZC3H12C axis in colorectal cancer.

BACKGROUND: The tumor immune microenvironment (TIME) is an important regulator of tumor progression, growth and metastasis. In addition, tumor metastasis is one of the principal obstacles to the treatment of colorectal cancer (CRC). Circular RNAs (circRNAs) have been recognized as important regulators in the development of malignancies. However, their specific roles and mechanisms in both CRC metastasis and TIME have not been thoroughly investigated. METHODS: High-throughput next-generation sequencing technology and real-time fluorescence quantitative PCR technology were performed to identify differential circRNAs in CRC. Functional assays including transwell assay, wound healing assay, and metastasis models were conducted to assess the effect of circRNF216 on CRC metastasis. In addition, luciferase reporter, western blot, RNA immunoprecipitation (RIP), and fluorescent in situ hybridization (FISH) were performed to explore the underlying mechanism of circRNF216. The level of immune infiltration was assessed by bioinformatics analysis and flow cytometry in CRC model. Furthermore, rescue and mutation experiments were used for verification. RESULTS: circRNF216 was identified as a putative tumor suppressor that is downregulated in CRC tissues and cells. Overexpression of circRNF216 inhibits metastasis in vitro and vivo. Mechanistically, circRNF216 acts as a competitive endogenous RNA (ceRNA) for miR-576-5p, alleviating miR-576-5p repression on its target ZC3H12C, which in turn downregulated N-cadherin. Additionally, circRNF216 could enhance the infiltration level of CD8+ T cells by upregulating ZC3H12C, ultimately inhibiting the development of CRC, which suggests that circRNF216 is a potential biomarker for the treatment of CRC. CONCLUSIONS: Here, we provide novel mechanistic insight revealing how circRNF216 functioned in CRC metastasis and TIME via the circRNF216/miR-576-5p/ZC3H12C pathway. Therefore, circRNF216 holds promise as a potential therapeutic target and novel diagnostic marker for CRC.

GSDMA at the crossroads between pyroptosis and tumor immune evasion in glioma.

Pyroptosis, an inflammatory and programmed cell death process, has been controversial in its role in tumor immunity. However, as the first molecule in the gasdermin family, the mechanism of GSDMA in glioma growth is not well understood. We identified the differentially expressed gene GSDMA from Treg cells-related genes using the TCGA database. The biological functions of GSDMA and the relationship between GSDMA expression and tumor immune cell infiltration and cancer patient survival were investigated using open-source databases and platforms. Additionally, flow cytometry analysis was used to examine the effect of GSDMA on tumor immune cell infiltration. Our study showed that GSDMA expression played an important role in immune evasion in glioma. Patients with high GSDMA expression had a worse prognosis. In vivo studies demonstrated that GSDMA knockdown could enhance the infiltration level of CD8+ T cells. High GSDMA expression was also positively correlated with poor anti-PD-L1 treatment outcomes in GBM patients, suggesting that GSDMA may be a potential biomarker that should be considered in combination with anti-PD-L1 therapy for glioma patients. In conclusion, our study demonstrates that high GSDMA expression in gliomas is associated with immune-infiltrating cells CD8+ T cells and Treg cells, and indicates a worse prognosis in glioma. Therefore, GSDMA may serve as a therapeutic target for glioma progression and should be applied in immunotherapy for glioma patients.

Identification of a lipid metabolism-related gene for cancer immunotherapy.

Background: Tumors frequently evade immune surveillance through multiple pathways to escape T cell recognition and destruction. Previous studies indicated that lipid metabolism alteration could affect the anti-tumor immunity of cancer cells. Nonetheless, the studies that investigated lipid metabolism-related gene for cancer immunotherapy are still few. Materials and methods: By mining the TCGA database, we screened out carnitine palmitoyltransferase-2 (CPT2), a key enzyme in the fatty acid ß-oxidation (FAO) process associated with anti-tumor immunity. We then analyzed the gene expression and clinicopathological features of CPT2 using open-source platforms and databases. Molecular proteins interacting with CPT2 were also identified using web interaction tools. Subsequently, the relationship between CPT2 and survival was analyzed in cancer patients. Results: Our study revealed that CPT2 played a vital role in tumor microenvironment and immune response signaling pathways. We have also demonstrated that increased CPT2 gene expression could enhance the level of tumor immune cell infiltration. Furthermore, high CPT2 expression positively related with overall survival associated with immunotherapy. CPT2 expression was also associated with the prognosis of human cancers, suggesting that CPT2 may be a potential biomarker for predicting the efficacy of cancer immunotherapy. Conclusion: To the best of our knowledge, the relationship between CPT2 and tumor immune microenvironment was first proposed in this study. Therefore, further studies on CPT2 may provide new insights into the development of effective cancer immunotherapy.

Sorafenib induces ferroptosis by promoting TRIM54-mediated FSP1 ubiquitination and degradation in hepatocellular carcinoma.

BACKGROUND: Ferroptosis is a unique form of regulated cell death that provided a new opportunity for cancer therapy. Ferroptosis suppressor protein 1 (FSP1) is a key regulator in the NAD(P)H/FSP1/CoQ10 antioxidant system, which sever as an oxide redox enzyme to scavenge harmful lipid hydroperoxides and escape from ferroptosis in cells. This study aimed to investigate the role of FSP1 on sorafenib-induced ferroptosis and disclosed the underlying mechanisms. METHODS: Cell viability, malondialdehyde (MDA), glutathione (GSH), and lipid reactive oxygen species levels were assessed using indicated assay kits. The levels of FSP1 and glutathione peroxidase 4 (GPX4) in the patients with HCC were analyzed based on the database. Western blot and quantitative real-time PCR were performed to detect the protein and mRNA expression. Co-immunoprecipitation was applied to detect the interaction between proteins. Tumor xenograft experiments were used to evaluate whether overexpression of FSP1-inhibited sorafenib-induced ferroptosis in vivo. RESULTS: We verified that sorafenib-induced ferroptosis in HCC. Furthermore, we found that sorafenib decreased the protein level of FSP1, and knockdown FSP1 rendered HCC cells susceptible to sorafenib-induced ferroptosis. Co-immunoprecipitation and ubiquitination assays showed that sorafenib accelerated the TRIM54-mediated FSP1 ubiquitination and degradation. Sorafenib-induced ferroptosis was abrogated by TRIM54 suppression. Mechanically, sorafenib-promoted TRIM54 ubiquitinated and degraded FSP1 by means of the ERK pathway. Moreover, FSP1 enhanced tumor development and decreased HCC cellular susceptibility to sorafenib in vivo. CONCLUSIONS: Sorafenib facilitated the TRIM54-mediated FSP1 ubiquitination through the ERK pathway, thereby inducing ferroptosis in HCC cells.