Hsa＿circ＿0079557 Promotes The Proliferation Of Colorectal Cancer Through Hsa＿circ＿0079557/miR-502-5p/CCND1 Aixs

BackgroundThe human genome is mostly transcribed into non coding RNA,except for a small number of folds which are transcribed into coding RNA.These non coding RNAs are divided into different categories.Micro RNA(miRNA),long chain non coding RNA(lncRNA),circular RNA(circRNA),and RNA interacting with Piwi protein(piRNA)are four main types of non coding RNA,which play an important role in cancer.MiRNA is a small RNA with a length of about 22 nucleotides.MiRNA binds to complementary sequences in targeted mRNA and causes RNA induced silencing complex(RISC)to degrade targeted mRNA.The length of piRNA is 24-30 nucleotides.It mainly exists in germ line cells and participates in epigenetic regulation of chromatin.The length of lncRNA and circRNA exceeds 200 nucleotides.lncRNA is linear and circRNA is circular.LncRNA and circRNA regulate gene expression through a variety of mechanisms.They can adsorb downstream miRNAs,thus preventing the degradation of miRNA targeted mRNA.They can regulate the binding of transcription factors and promoters,thereby regulating the expression of targeted genes.They can also serve as scaffolds for regulating protein protein interactions and related downstream signaling pathways.CircRNA is a unique class of RNA molecule discovered more than 40 years ago,which is produced by covalent connection through reverse splicing of linear RNA.Recent advances in sequencing technology and bio-informatics tools have directly motivated the expansion of circRNA types and biological functions.Recent studies have shown that circRNA play an important role in the occurrence and development of cancer.Up-regulated circRNA is associated with the development of cancer.However,many regulatory mechanisms of circRNA have not been fully understood.Exploring the role of circRNA in tumorigenesis may help to discover new diagnostic markers and therapeutic targets.Colorectal cancer is the third most common malignant tumor.Because of late diagnosis,distant metastasis and chemotherapy resistance,the prognosis of colorectal cancer patients is still poor.Here,we studied hsa＿circ＿0079557’s role and regulatory mechanism in colorectal cancer(CRC).MethodsWe downloaded the datasets of circular RNA gene expression profiles from the gene expression comprehensive database(GEO),removed the batch effect between these datasets and combined them into a new dataset.We found that some circRNAs were highly expressed in colorectal cancer.In these circular RNAs,we experimentally verified the expression of hsa＿circ＿0079557 was relatively high in colorectal cancer tissues and cells.Quantitative real-time polymerase chain reaction(qRT-PCR),flow cytometry,cell colony formation,cell count test(CCK-8),cell migration test,cell scratch test,nude mouse subcutaneous tumorigenesis test and immunohistochemical staining(IHC)were performed to evaluate their effects in vitro and in vivo.Fluorescence in situ hybridization(FISH)and double luciferase reporter assay were performed to confirm the location and association between hsa＿circ＿0079557 and the identified miRNA.The network tool "TargetScan" was used to predict the downstream target protein,and its expression was determined by Western Blot(WB).ResultHsa＿circ＿0079557 was found to be relatively upregulated in CRC tissues and cell lines.Suppression of hsa＿circ＿0079557 expression inhibited the proliferation in vitro and vivo.Furthermore,hsa＿circ＿0079557 was found to act as a "molecular sponge" for miR-502-5p and upregulated the expression of CCND1.ConclusionWe identified a relatively high expression circRNA in colorectal cancer cells,and proposed a theory:hsa＿circ＿0079557 promotes the proliferation of colorectal cancer through hsa＿circ＿0079557/miR-502-5p/CCND1 aix...