The Interaction Between Long Noncoding RNA SLC7A11-AS1 And RSL1D1 In Pancreatic Cancer Cells

Pancreatic cancer is a highly advanced digestive system tumor with a 5-year survival rate of less than 9%.According to the database statistics of the 2018 Global Cancer Observatory website,pancreatic cancer ranks seventh among cancer-related deaths worldwide.Gemcitabine is a first-line chemotherapy drug for the treatment of pancreatic cancer,but long-term use of drugs causes chemotherapy-resistant gemcitabine in patients with pancreatic cancer.In tumor cells,lncRNAs can function through various molecular interactions,such as regulation of chromatin structure by binding to chromatin conformation proteins,regulation of epigenetic modification state by binding to epigenetic enzymes,regulation of signal transduction by binding to signal proteins,and influence on RNA activity by binding to mRNA and other molecules.LncRNAs interact with proteins in a variety of forms,acting as protein bait,protein scaffold,guiding protein targeting and intracellular signal,and participating in various processes of tumor occurrence,evolution and metastasis.Our research group has found that SLC7A11-AS1 is mainly located in the nucleus,which is highly expressed in gemcitabine-resistant cells of pancreatic cancer,and positively regulates the drug resistance.Moreover,NRF2 expression was down-regulated and intracellular ROS levels were elevated after knocking down SLC7A11-AS1.However,the mechanism involved in the regulation of SLC7A11-AS1 in pancreatic cancer is still unclear.Therefore,this paper focus on the interaction protein RSL1D1 and regulatory mechanisms of SLC7A11-AS1 expression in pancreatic cancer.In this paper,RNA pull-down assay and mass spectrometry were used to screen out the binding protein RSL1D1 of SLC7A11-AS1 in pancreatic cancer cells.RNA pull-down analysis using in vitro-transcribed biotinylated SLC7A11-AS1 was designed to analyze the binding sites of SLC7A11-AS1 and RSL1D1.The results showed the Exon 3 of SLC7A11-AS1 could bind to the RSL1D1 protein.The analysis of the regulation between SLC7A11-AS1 and RSL1D1 revealed that knockdown of SLC7A11-AS1 did not affect the expression of RSL1D1,but the expression of SLC7A11-AS1 was significantly up-regulated after overexpression of RSL1D1.Actinomycin D treatment of pancreatic cancer cells after overexpressing RSL1D1 found that overexpression of RSL1D1 had no significant effect on the stability of SLC7A11-AS1.It indicates that RSL1D1 does not play a regulatory role by affecting RNA stability.Furthermore,it was found that RSL1D1 was highly expressed in pancreatic gemcitabine-resistant cancer cell lines,and the drug resistance of pancreatic cancer cells was enhanced after overexpression of RSL1D1.Meanwhile,the level of ROS in pancreatic cancer cells was significantly inhibited after overexpressing RSL1D1,indicating that RSL1D1 may affect oxidative stress levels thus involved in pancreatic cancer resistance.TCGA on-line database analysis found that patients with high expression of RSL1D1 had shorter survival.In summary,we found that RSL1D1 binds to the exon 3 region of SLC7A11-AS1,thus positively regulates the expression level of SLC7A11-AS1.Moreover,RSL1D1 is highly expressed in gemcitabine-resistant cell lines and can promote gemcitabine resistance in pancreatic cancer,which may function by inhibiting ROS levels in pancreatic cancer cells.This paper provides a new perspective for mechanism of gemcitabine resistance in pancreatic cancer.