Novel circular RNA circSOBP governs amoeboid migration through the regulation of the miR-141-3p/MYPT1/p-MLC2 axis in prostate cancer

BACKGROUND

Metastatic prostate cancer is a fatal disease despite multiple new approvals in recent years. Recent studies revealed that circular RNAs (circRNAs) can be involved in cancer metastasis. Defining the role of circRNAs in prostate cancer metastasis and discovering therapeutic targets that block cancer metastasis is of great significance for the treatment of prostate cancer.

METHODS

The circSOBP levels in prostate cancer (PCa) were determined by qRT-PCR. We evaluated the function of circSOBP using a transwell assay and nude mice lung metastasis models. Immunofluorescence assay and electron microscopic assay were applied to determine the phenotypes of prostate cancer cells' migration. We used fluorescence in situ hybridization assay to determine the localization of RNAs. Dual luciferase and rescue assays were applied to verify the interactions between circSOBP, miR-141-3p, MYPT1, and phosphomyosin light chain (p-MLC2).

RESULTS

We observed that circSOBP level was significantly lower in PCa specimens compared with adjacent noncancerous prostate specimens, and was correlated with the grade group of PCa. Overexpression of circSOBP suppressed PCa migration and invasion in vitro and metastasis in vivo. CircSOBP depletion increased migration and invasion and induced amoeboid migration of PCa cells. Mechanistically, circSOBP bound miR-141-3p and regulated the MYPT1/p-MLC2 axis. Moreover, the depletion of MYPT1 reversed the inhibitory effect of circSOBP on the migration and invasion of PCa cells. Complementary intronic Alu elements induced but were not necessary for the formation of circSOBP. The nuclear export of circSOBP was mediated by URH49.

CONCLUSION

Our results suggest that circSOBP suppresses amoeboid migration of PCa cells and inhibits migration and invasion through sponging miR-141-3p and regulating the MYPT1/p-MLC2 axis.

circSOBP Inhibits Bladder Cancer Proliferation and Metastasis by Regulating the miR-200a-3p/PTEN Axis and Participating in the Immune Response

A growing body of evidence shows that circular RNAs (circRNAs) participate in tumor growth and metastasis and also play crucial roles in the treatment and prognosis of various cancers. In this article, we identified a novel circRNA, circSOBP (has_circ_0001633), based on the results of high-throughput RNA sequencing, and its expression was subsequently validated via quantitative reverse transcription polymerase chain reaction in bladder cancer (BCa) tissues and cell lines. The association between circSOBP expression and the clinicopathologic features and prognosis of 56 recruited BCa patients was then analyzed, and the biological roles of circSOBP were assessed by in vitro cloning formation, wound healing, transwell, CCK-8, and in vivo xenograft mouse models. Next, the competitive endogenous RNA mechanism was explored through fluorescence in situ hybridization, RNA pull-down, luciferase reporter, bioinformatics analysis, and rescue experiments. Western blot and immunohistochemistry detected the expression of downstream mRNA, and we were able to determine that circSOBP was downregulated in BCa tissues and cell lines and that lower circSOBP expression was associated with more advanced pathological stage, larger tumor size, and poorer overall survival with BCa patients. Overexpressed circSOBP suppressed cell proliferation, migration, and invasion both in vitro and in vivo. Mechanistically, competitive interactions between circSOBP and miR-200a-3p enhanced target gene PTEN expression. In addition, we found a significant correlation between higher expression of circSOBP in BCa patients after immunotherapy than before and a better treatment outcome, indicating that circSOBP might regulate the programmed death 1/programmed death ligand 1 pathway. Overall, circSOBP inhibits BCa tumorigenesis and metastasis by a novel miR-200a-3p/PTEN axis, which makes it an excellent biomarker and therapeutic target for treating BCa.

Potentials of circSOBP in the diagnosis and prognosis of gastric cancer

OBJECTIVES

Gastric cancer (GC) causes no symptoms at early stages. However, with the progression, GC causes symptoms mimicking normal gastrointestinal issues, such as irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), gastritis, or peptic ulcers (PU). CircRNA circSOBP has been characterized as a critical regulator in prostate cancer. The present study aimed to study its involvement in GC.

MATERIALS AND METHODS

Plasma samples were collected from GC patients (n = 64), IBS patients (n = 64), GERD patients (n = 64), gastritis patients (n = 64), PU patients (n = 64), and healthy controls (HCs, n = 64). Paired GC and non-tumor samples were from all GC patients (n = 64). Tissue and plasma samples were subjected to RT-qPCR to determine circSOBP expression. The role of circSOBP in distinguishing GC patients from other patients was analyzed by ROC curve. The 64 patients were followed up for 5 years to study the role of circSOBP in predicting the survival of GC patients.

RESULTS

Decreased circSOBP RNA accumulation was observed in GC tissues compared to normal tissue samples. Decreased plasma circSOBP accumulation was only observed in GC patients, but not other patients, compared to HCs. With plasma circSOBP as a biomarker, GC patients were separated from other patients and HCs. Patients with high plasma or tissue levels of circSOBP showed better survival conditions. In addition, plasma and tissue circSOBP levels were only closely correlated with GC patients' tumor metastasis, but not other clinical factors.

CONCLUSIONS

Decreased circSOBP accumulation may be applied in clinical practice to improve the diagnosis and prognosis of GC.