Circ_0087851 suppresses colorectal cancer malignant progression through triggering miR-593-3p/BAP1-mediated ferroptosis.

BACKGROUND: Emerging research has validated that circular RNAs (circRNAs) have indispensable regulatory functions in tumorigenesis, including colorectal cancer (CRC). Ferroptosis is a specific cell death form and implicates in the malignant progression of tumors. Here, this study aimed to investigate the biofunction of circ_0087851 in tumor progression and ferroptosis of CRC, as well as its underlying molecular mechanism. METHODS: The expression pattern of circ_0087851 in CRC was validated by qRT-PCR. The biological characteristics of circ_0087851 in CRC were assessed through CCK-8, colony formation and transwell assays in vitro. The ferroptosis was measured using ferroptosis-related reagents on iron, Fe2+, and lipid ROS detection. Bioinformatics, luciferase reporter, and RNA pulldown assays were employed to reveal the circ_0087851-mediated regulatory network. In addition, the effect of circ_0087851 on tumor growth in vivo was detected using a xenograft model. RESULTS: Circ_0087851 was notably diminished in CRC tissues and cells. Functionally, overexpression of circ_0087851 suppressed CRC cell growth, migration, invasion, and facilitated ferroptosis in vitro. Meanwhile, circ_0087851 upregulation impeded CRC growth in vivo. Mechanistically, circ_0087851 functioned as a molecular sponge for miR-593-3p, and BRCA1 associated protein 1 (BAP1) was identified as a downstream target of miR-593-3p. Besides, rescue experiments revealed that miR-593-3p overexpression or silencing of BAP1 reversed circ_0087851-mediated CRC progression. CONCLUSION: Circ_0087851 performed as a tumor suppressor and ferroptosis promoter by the miR-593-3p/BAP1 axis, providing novel biomarker and therapeutic target for the clinical management of CRC.

YB1 associates with oncogenetic roles and poor prognosis in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is the malignant tumor arising from the nasopharynx epithelium with ethnic and geographical distribution preference. Y-box binding protein-1 (YB1) is the highly expressed DNA/RNA-binding protein with cold shock domain, and enhanced YB1 expression was proved to be associated with many kinds of malignant tumors. There is no systematic study about the regulation of YB1 and cell proliferation, migration, invasion and stress granules (SGs) in NPC, and the relationship between YB1 expression and clinical characteristics and prognosis of NPC patients. We analyzed the mRNA expression of YBX1 in head and neck squamous carcinoma (HNSC) and NPC in databases, investigated the functions of YB1 in cell proliferation, migration and invasion and SGs formation of NPC cells, and detected expression of YB1 protein in a large scale of NPC samples and analyzed their association with clinicopathological features and prognostic significance of NPC patients. YBX1 mRNA was significantly high expression in HNSC and NPC by bioinformatic analysis, and higher expression of YBX1 mRNA indicated poorer prognosis of HNSC patients. Clinically, the expression of YB1 in NPC tissues was significantly higher than these in the control nasopharyngeal epithelial tissues. We further found that the expression of YB1 had an evidently positive relation with advanced clinical stages of patients with NPC. The overall survival rates (OS) were significantly lower for NPC patients with positive expression of YB1. Multivariate analysis confirmed that positive expression of YB1 was the independent poorer prognostic factor for patients with NPC. Moreover, compared with the immortalized nasopharyngeal epithelial cell line (NP69), the basal level of YB1 in NPC cell lines was significantly higher. Knocking down YB1 may inhibit Akt/mTOR pathway in NPC cells. Knocking down YB1 by small interfering RNAs can reduce the ability of proliferation, migration, invasion and SGs formation of NPC cells. The expression of YB1 in NPC cell lines or patients with NPC was significantly higher. The high expression of YB1 protein may act as one valuable independent biomarker to predict poor prognosis for patients with NPC. Knocking down YB1 may release the malignant phenotype of NPC cells.

Expression of cancer cell-intrinsic PD-1 associates with PD-L1 and p-S6 and predicts a good prognosis in nasopharyngeal carcinoma.

Aims: Programmed cell death ligand 1 (PD-L1) is the ligand of programmed death 1 (PD-1), which is a host immunity inhibitory receptor. Expression of PD-L1 in diverse tumor types has been widely discussed, while there is little research about tumor intrinsic-PD-1. Phospho-S6 (p-S6) is an important downstream effector in the PI3K/AKT/mTOR pathway. Our study was focused on investigating expression of cancer cell-intrinsic PD-1, PD-L1 and p-S6 proteins and aimed to illustrate their relationship and clinical significances in nasopharyngeal carcinoma (NPC). Methods: The expression of PD-1, PD-L1 and p-S6 proteins in tissues of NPC, non-cancerous nasopharyngeal epithelia, primary cancer and matching metastatic lesion was detected by immunohistochemistry. Results: Expression of PD-1, PD-L1 and p-S6 proteins and co-expression of PD-1 and PD-L1 were significantly higher in NPC (all P<0.05). The expression of PD-1 and co-expression of PD-1 and PD-L1 in paired metastatic NPC were significantly increased (all P<0.01). NPC patients with positive expression of PD-L1 showed significantly higher overall survival rate (P =0.035). However, NPC patients with positive expression PD-1 and p-S6 showed significantly lower overall survival rate (P =0.031, P=0.044, respectively). Interestingly, NPC patients with co-expression of PD-1 and PD-L1 had lower overall survival rate (P=0.042). Multivariate Cox proportional hazard regression analysis confirmed that positive expression of PD-L1 and p-S6 were independent prognostic factors for NPC patients. Conclusions: Expression of cancer cell-intrinsic PD-1 associates with PD-L1 and p-S6 proteins, PD-L1 might serve as a good prognostic biomarker, while p-S6 could be an independent poor prognostic biomarker for NPC patients.

[Shikimic acid inhibits the degranulation and histamine release in RBL-2H3 cells].

Objective To study the effects of shikimic acid on the proliferation of rat RBL-2H3 cells and the degranulation of the cells induced by C48/80 and its mechanism. Methods MTT assay was performed to measure the proliferation of RBL-2H3 cells treated with 3, 10, 30 µg/mL shikimic acid. Toluidine blue staining was used to observe the degranulation of RBL-2H3 cells. The release of ß-hexosaminidase from RBL-2H3 cells treated with 0, 12.5, 25, 50, 80, 100 µg/mL C48/80 was determined by substrate assay. ELISA was used to detect the histamine content in the supernatant of each treated group. Results Shikimic acid at 3, 10, 300 µg/mL had no obvious inhibitory effect on the proliferation of RBL-2H3 cells. There was a dose-effect relationship between the degranulation of RBL-2H3 cells and C48/80 concentration. Shikimic acid inhibited the degranulation of RBL-2H3 cells compared with the positive control group, the ß-hexosaminidase release rate and histamine release were significantly reduced in RBL-2H3 cells treated with shikimic acid and C48/80. Conclusion Shikimic acid can inhibit the degranulation of RBL-2H3 cells and reduce histamine release.

[Tryptase inhibits cell apoptosis through upregulating PAR-2 and Rho kinase in rheumatoid arthritis synovial fibroblasts].

Objective To investigate the regulatory effects of tryptase on protease-activated receptors 2 (PAR-2), Rho signal pathway and apoptosis of MH7A rheumatoid arthritis synovial fibroblasts. Methods In MH7A cells, the expression of PAR-2 was measured by flow cytometry; cell apoptosis was examined by annexin V- FITC/PI staining combined with flow cytometry; the expression of Rho kinase was detected by Pull-down assay and Western botting. Results Tryptase upregulated the expression of PAR-2 in MH7A cells, and suppressed Fas-mediated apoptosis of MH7A cells in a dose-dependent manner. Meanwhile, PAR-2 inhibitor, FSLLRY-NH2 significantly reduced anti-apoptotic effects of tryptase in MH7A cells, which was related with the increase of activated Rho kinase expression. Conclusion Tryptase plays a role in resistance to the apoptosis of MH7A cells through raising PAR-2 and activating Rho kinase.