Biological functions, mechanisms, and clinical significance of circular RNA in colorectal cancer

USP6 and circCYFIP2 target oncoprotein GOLPH3 for deubiquitination and induce platinum resistance in colon cancer

GOLPH3 has been identified as an oncoprotein, playing a crucial role on progression and chemoresistancein of colon adenocarcinoma (COAD). However, it is still unclear the regulation of GOLPH3 expression at protein level. We discovered ubiquitin-specific proteases 6 (USP6) directly regulated the deubiquitination of the GOLPH3 protein and enhanced its stability in COAD. Overexpression of USP6 promoted COAD cell viability, inhibited apoptosis, and accelerated the growth of transplanted tumors growth in vitro and in vivo by deubiquitinating GOLPH3. Additionally, circCYFIP2 showed high expression levels in DDP-resistant colon cancer cells, promoting the cell proliferation. Mechanically, circCYFIP2 binds to both GOLPH3 protein and USP6, strengthening the interaction between GOLPH3 and USP6, and consequently induced DDP resistance in vitro and in vivo. In conclusion, USP6 operates as a deubiquitinase, targeting the GOLPH3 protein in COAD and enhancing its stability. Meanwhile, circCYFIP2 is crucial for the deubiquitination of GOLPH3 protein mediated by USP6 and acts as a scaffold to confer platinum resistance. The discovery of circCYFIP2/USP6/GOLPH3 pathway offers a potential target for overcoming chemoresistance in COAD.

MicroRNA-183 cluster: a promising biomarker and therapeutic target in gastrointestinal malignancies

Small non-coding RNAs (microRNA, miR), powerful epigenetic regulators, were found involved in the regulation of most biological functions via post-translational inhibition of protein expression. Increased expression of pro-oncogenic miRs (known as miR cancer biomarkers) and inhibition of pro-apoptotic miR expression have been demonstrated in different tumors. The recently identified miR-183 was found implicated in gastrointestinal tumor metabolism regulation. Elevated miR-183 expression and cancer-promoting effects were reported in esophageal and colorectal cancers, which was partially contradicted by controversial data observed in gastric cancers. Anti-cancer effect of miR-183 in gastric cancer cells was associated with the Bim-1 and Ezrin genes regulation. Many studies indicated that miR-183 can inhibit tumor suppressor genes in most cell lines, promoting tumor cell proliferation and migration. Increased miR-183 level results in the downregulation of FOXO1, PDCD4, and other tumor suppressor genes in gastrointestinal tumor cells. MiR-183 also influences the signaling of PI3K/AKT/mTOR, Wnt/β-catenin, and Bcl-2/p53 signaling pathways. Mir-183 inhibits apoptosis and autophagy, and promotes epithelial-to-mesenchymal transition, cancer cell proliferation, and migration. Accordingly, gastrointestinal cancer occurrence, development of chemoradiotherapy resistance, recurrence/metastasis, and prognosis were associated with miR-183 expression. The current study assessed reported miR-183 functions and signaling, providing new insights for the diagnosis and treatment of gastrointestinal malignancies.

Effects of hsa_circ_0074854 on colorectal cancer progression, construction of a circRNA-miRNA-mRNA network, and analysis of immune infiltration

PURPOSE

Circular RNAs have been demonstrated to be closely associated with the onset and metastasis of colorectal cancer. However, the roles and clinical diagnostic value of most circRNAs in colorectal cancer remain unclear.

METHODS

We detected the differential expression of circRNAs in CRC tissues and cells and investigated their relationship in conjunction with clinical pathological features. Additionally, we performed cellular functional experiments in CRC cell lines to explore the functions of circRNAs. To further validate the potential ceRNA network, qPCR was performed to assess the expression of miRNA and mRNA in CRC cells after differential expression of circRNAs knockdown. Furthermore, database analysis was utilized to explore the relationship between the predicted mRNAs and immune infiltration in CRC.

RESULTS

Our research findings indicate a positive correlation between hsa_circ_0074854 expression and advanced clinical pathological features, as well as an unfavorable prognosis. Knockdown of hsa_circ_0074854 was observed to inhibit proliferation and migration capabilities of colorectal cancer cells, affecting the cell cycle progression, and simultaneously promoting apoptosis. A competing endogenous RNA mechanism may exist among circRNAs, miRNAs, and mRNAs. Furthermore, the expression of target genes displayed correlations with the abundance of certain immune cells.

CONCLUSION

We propose a novel ceRNA network and evaluate the interplay between target genes and immune cells, providing novel insights for the diagnosis and targeted therapy of CRC.