Identification of circ_0000375 and circ_0011536 as novel diagnostic biomarkers of colorectal cancer

Abstract

BACKGROUND Colorectal cancer (CRC) imposes a tremendous burden on human health, with high morbidity and mortality. Circular ribonucleic acids (circRNAs), a new type of noncoding RNA, are considered to participate in cancer pathogenesis as microRNA (miRNA) sponges. However, the dysregulation and biological functions of circRNAs in CRC remain to be explored. AIM To identify potential circRNA biomarkers of CRC and explore their functions in CRC carcinogenesis. METHODS CircRNAs and miRNAs differentially expressed in CRC tissues were identified by analyzing expression profiles from the Gene Expression Omnibus (GEO) database. Circ_0000375 and circ_0011536 were selected as CRC biomarker candidates. Quantitative real-time polymerase chain reaction was utilized to evaluate the expression of these 2 circRNAs in CRC tissues, serums and cell lines. Receiver operating characteristic curves were generated to assess the diagnostic performances of these 2 circRNAs. Then, functional experiments, including cell counting kit-8, wound healing and Transwell invasion assays, were performed after the overexpression of circ_0000375 and circ_0011536 in CRC cell lines. Furthermore, candidate target miRNAs of circ_0000375 and circ_0011536 were predicted via bioinformatics analysis. The expression levels of these miRNAs were explored in CRC cell lines and tissues from GEO datasets. A luciferase reporter assay was developed to examine the interactions between circRNAs and miRNAs. Based on the target miRNAs and downstream genes, functional enrichment analyses were applied to reveal the critical signaling pathways involved in CRC carcinogenesis. RESULTS Downregulated circ_0000375 and circ_0011536 expression was observed in CRC tissues in GSE126095, clinical CRC tissue and serum samples and CRC cell lines. The areas under the curve for circ_0000375 and circ_0011536 were 0.911 and 0.885 in CRC tissue and 0.976 and 0.982 in CRC serum, respectively. Moreover, the serum levels of these 2 circRNAs were higher in patients at 30 d postsurgery than in patients before surgery, suggesting that the serum expression of circ_0000375 and circ_0011536 is related to CRC tumorigenesis. Circ_0000375 and circ_0011536 overexpression inhibited the proliferation, migration and invasion of CRC cells. Furthermore, miR-1182 and miR-1246, which were overexpressed in CRC tissues in GSE41655, GSE49246 and GSE115513, were verified as target miRNAs of circ_0000375 and circ_0011536, respectively, by luciferase reporter assays. The downstream genes of miR-1182 and miR-1246 were enriched in some CRC-associated pathways, such as the Wnt signaling pathway. CONCLUSION Circ_0000375 and circ_0011536 may function as tumor suppressors in CRC progression, serving as novel biomarkers for CRC diagnosis and as promising candidates for therapeutic exploration.

Zmym4 is required for early cranial gene expression and craniofacial cartilage formation

“…These include: 1) ZMYM4-AS1, a long non-coding RNA that can be used as a competitive endogenous RNA to regulate gene expression levels and affect cell function by competing with microRNAs ( Li et al, 2021 ), 2) a circular RNA form ( i.e. , circ_0011536) that may function as a microRNA sponge in colorectal and endometrial cancers ( Cheng et al, 2018 ; Yin et al, 2022 ), and 3) fusion with a rolling-circle transposon that generates an alternative transcript of ZMYM4 that contains a cryptic splice site, an initiation codon, and a few codons in the predicted ORF from the transposon donor ( Thomas et al, 2014 ). Therefore, the possible functions of Zmym4 during early cell fate decisions underlying the apportioning of the embryonic ectoderm into the various stem populations that contribute to craniofacial structures - the neural plate, neural crest, preplacodal ectoderm, and the non-neural ectoderm—remain to be determined by future in-depth studies.…”

Integrated whole transcriptome profiling of circRNAs reveals a convoluted crosstalk in competing endogenous RNAs regulatory network in Colorectal Cancer

“…In 2021, Yin et al, reported that hsa_circ_0007158 and hsa_circ_0000375 are involved in a circRNA/miRNA/mRNA regulatory network in CRC 26 . A year later, they exhibited that hsa_circ_0000375 may have a tumor suppressor role in CRC 27 . Based on our literature review there were no reports of the involvement of the rest of the selected circRNAs in CRC.…”