MiR-181a And MiR-27b Regulate Angiogenesis And Chemoresistance In Colorectal Cancer,respectively

Colorectal cancer(colorectal cancer,CRC)is a kind of digestive tract malignant tumor with high morbidity and mortality.It is a serious problem to explore the pathogenic factors behind colorectal cancer and improve the prevention,diagnosis,treatment and prognosis of colorectal cancer.MicroRNAs(miRNAs)is a kind of single-stranded non-coding small 19-23 nt,which is conserved in many species.MiRNA mainly inhibits the translation of mRNA or causes the degradation of mRNA by binding mRNA of the target gene,thus inhibiting the expression of the target gene and affecting a variety of physiological and pathological activities.When cancer occurs,the expression of a variety of miRNAs in cancer cells will change,resulting in ectopic expression of target genes,thus affecting the occurrence and development of cancer.It is of great significance to study the tumor-related miRNA and reveal the mechanism of miRNA involved in the regulation of cancer process.In this study,we investigated two important miRNAs(proto-cancer miRNA miR-181 a and tumor suppressor miRNA miR-27b),which participate in promoting angiogenesis and inhibiting chemoresistance by targeting SRCIN1 and ATG10 in colorectal cancer,respectively.Our research aimed to find new therapies for inhibiting angiogenesis and oxaliplatin resistance in colorectal cancer.The research content was mainly divided into two parts.In the first part of this paper,we investigated that miR-181 a could promote angiogenesis in colorectal cancer.Firstly,via performing a microarray survey,we found that miR-181 a was up-regulated in cancer tissues,and qPCR further confirmed the result.There was a significant negative correlation between miR-181 a and the prognosis of colorectal cancer.After overexpressing or knocking down miR-181 a levels,we monitored angiogenesis in vitro and matrigel plug assay in vivo.It showed that miR-181 a could promote angiogenesis.Bioinformatics prediction and luciferase report experiment showd that miR-181 a can bind to SRCIN1 directly.We further found a significant negative correlation between miR-181 a and SRCIN1 in colorectal cancer tissues.Next,we proved that miR-181 a could inhibit SRCIN1 expression.In addition,we found that the inhibition of SRCIN1 by miR-181 a constituted the core of miR-181a/SRCIN1/SRC/VEGF regulatory axis.The recovery experiment showed that miR-181 a inhibited angiogenesis by inhibiting SRCIN1.Finally,we concluded that miR-181 a could inhibit the expression of SRCIN1,which in turn activated the SRC/VEGF pathway,and increased the secretion of VEGF in colorectal cancer cells,leading to angiogenesis.In the second part,we studied that miR-27 b could promote the sensitivity of colorectal cancer to oxaliplatin by down-regulating ATG10.Firstly,we successfully constructed colon cancer cells resistant to oxaliplatin by gradient induction.Next,we screened the dysregulated miRNA between drug-sensitive cell lines and drug-resistant cells.Furthermore,functional experiments showed that miR-27 b could significantly reverse the drug resistance of colorectal cancer,and promote cell apoptosis.Next,we demonstrated that autophagy could promote drug resistance in colorectal cancer,what's more,miR-27 b could regulate autophagy.By bioinformatics prediction,we predicted that miR-27 b may regulate autophagy-associated genes(ATG10,ATG4 C,ATG2A and ATG2B).After further screening by Luciferase reporter assay,we found that ATG10 was significantly down-regulated when ectopic miR-27 b was expressed.We found that the expression level of miR-27 b was lower in colorectal cancer tissue,which was significantly negatively correlated with ATG10 protein level.Next,we demonstrated that miR-27 b can inhibit the expression of ATG10.Through the recovery experiment,we proved that miR-27 b can reverse chemotherapy resistance by directly inhibiting the expression of ATG10,inhibiting autophagy.In addition,we found that the inhibition of ATG10 by miR-27 b constituted the core of c-Myc/miR-27b/ATG10 regulatory axis.In summary,our study found that important regulatory axes(miR-181a/SRCIN1/SRC/VEGF and c-Myc/miR-27b/ATG10),which played an important role in the progression of colorectal cancer.Our results revealed the important function of miRNA in angiogenesis and chemotherapy resistance of colorectal cancer,which provided new targets for the treatment of colorectal cancer.