Expression Patterns of Circular RNAs from Primary Kinase Transcripts in the Mammary Glands of Lactating Rats

Abstract

PurposeCircular RNAs (circRNAs), a novel class of RNAs, perform important functions in biological processes. However, the role of circRNAs in the mammary gland remains unknown. The present study is aimed at identifying and characterizing the circRNAs expressed in the mammary gland of lactating rats.MethodsDeep sequencing of RNase R-enriched rat lactating mammary gland samples was performed and circRNAs were predicted using a previously reported computational pipeline. Gene ontology terms of circRNA-producing genes were also analyzed.ResultsA total of 6,824 and 4,523 circRNAs were identified from rat mammary glands at two different lactation stages. Numerous circRNAs were specifically expressed at different lactation stages, and only 1,314 circRNAs were detected at both lactation stages. The majority of the candidate circRNAs map to noncoding intronic and intergenic regions. The results demonstrate a circular preference or specificity of some genes. DAVID analysis revealed an enrichment of protein kinases and related proteins among the set of genes encoding circRNAs. Interestingly, four protein-coding genes (Rev3l, IGSF11, MAML2, and LPP) that also transcribe high levels of circRNAs have been reported to be involved in cancer.ConclusionOur findings provide the basis for comparison between breast cancer profiles and for selecting representative circRNA candidates for future functional characterization in breast development and breast cancer.

Circular RNA; a new biomarker for breast cancer: A systematic review

“…Investigators also declared the presence of protein kinases and their associated proteins among the specific genes encoding circRNAs. Interestingly, it is reported that four protein‐coding genomic regions as Rev3l, IGSF11, MAML2, and LPP that also transcribe elevated levels of circRNAs are involved in cancer (Zhang et al, 2015).…”

Circular RNA hsa_circ_0068033 inhibits proliferation and invasion of breast cancer cells through sponging miR-659

“…Studies based on circRNA microarray analysis have shown that multiple circRNAs are abnormally expressed in BC [20,21]. For example, a study performed by Tang et al has shown that 1,155 abnormally expressed circRNAs (715 down-regulated and 440 up-regulated) are present in BC tissues [20].…”

“…For example, a study performed by Tang et al has shown that 1,155 abnormally expressed circRNAs (715 down-regulated and 440 up-regulated) are present in BC tissues [20]. A chip analysis conducted by Zhang et al has identified 1,314 abnormally expressed circRNAs, the majority of which are derived from coding genes Rev3l, IGSF11, MAML2, and LPP [21]. In this study, qRT-PCR and ISH confirmed that the expression of hsa_circ_0068033 was decreased in BC tissues and four BC cell lines, and this expression was associated with the clinical staging of patients.…”

“…Studies have shown that certain types of circRNAs, such as hsa_circ_0001982 [20], circGFRA1 [23], circ-ABCB10 [24], circ-Foxo3 [25], and circRNA_1093 [21], may function as a miRNA sponge in BC cells. Our qRT-PCR analysis found that hsa_circ_0068033 was mainly distributed in the cytoplasm of MDA-MB-231 and MCF-7 cells, suggesting that it may play the role of a miRNA sponge.…”

Prolactin-Responsive Circular RNA circHIPK3 Promotes Proliferation of Mammary Epithelial Cells from Dairy Cow

“…We previously detected the expression of thousands of circular RNAs in the mammary glands of a cow and a rat, with circHIPK3 present at a high abundance [14,15]. Interestingly, circHIPK3 has been reported to promote the proliferation of tumor cells, such as HuH-7, HCT-116, HeLa, PC-3, and DU145 cells [16][17][18].…”