Identification And Clinical Significance Of Long Noncoding RNAs As Plasma Biomarkers For Colorectal Cancer

Colorectal cancer(CRC)is one of the most common malignant tumors in the world.In spite of the continuous improvement of surgical and chemoradiotherapy techniques,the morbidity and mortality of CRC in China are still at a high level.Improving the level of early diagnosis of CRC and finding reliable therapeutic indicators are the key to the treatment of CRC.Long non-coding RNA(Lnc RNA)is a class of RNA molecules with transcripts of more than 200 nt in length,which can be detected in tissue,serum and urine.It has been a hotspot in molecular targeting research to explore the characteristic expression of serum or plasma lnc RNA in malignant tumor.Objective: The aim of this study was to select lnc RNAs with characteristic expression in plasma of patients with colorectal cancer and precancerosis,and to verify whether these lnc RNAs could be used as a potential molecular marker for early diagnosis and therapeutic evaluation of CRC,which would provide accurate and reliable laboratory diagnostic indicators for early diagnosis and prognosis of CRC.Methods: This study was divided into four phases:(1)marker discovery by analysis of bioinformatics database;(2)marker selection by real-time quantitative PCR on a small set of plasma from the training group including 16 healthy controls,13 adenoma patients and 24 CRC patients;(3)independent validation on a large set of plasma from the validation group including 42 healthy controls,14 polyp patients,30 adenoma patients and 90 CRC patients(40 in TNM Ⅰ/Ⅱ,50 in TNM Ⅲ/Ⅳ).(4)evaluation of the diagnostic performance of the plasma candidate lnc RNAs for CRC by the receiver operating characteristics curve(ROC curve);Comparison of expression level of characteristic candidate lnc RNAs in plasma of 29 CRC patients between before and after operation;analysis of the correlation between plasma lnc RNAs expression and clinicopathological parameters of CRC.Results: 1.Through the above experiments,four characteristic plasma candidate lnc RNA ZFAS1,SNHG11,LINC00909 and LINC00654 were screened out.The circulating levels of ZFAS1,SNHG11,LINC00909 and LINC00654 were capable of distinguishing cancer patients from the non-malignant group of patients(All P <0.05);The expressions of ZFAS1 and SNHG11 were significantly increased in adenoma samples compared to the healthy controls(All P <0.05);SNHG11 was also differentially expressed in polyp samples compared to the healthy controls(P <0.05).2.The AUCs of plasma ZFAS1,SNHG11 and LINC00909 were 0.850,0.868 and 0.886,which were higher than those of traditional tumor marker CEA(AUC=0.797)and CA19-9(AUC=0.603),respectively.The AUC of plasma LINC00654 was 0.734,which was slightly lower than that of the traditional tumor marker CEA,but higher than that of CA19-9.3.The combination of these four lnc RNAs showed a higher diagnostic performance for CRC comparising with that of single lnc RNA or any other combination,especially in patients with CRC at relatively early stage.4.The combination of the four plasma lnc RNAs with the traditional tumor marker CEA and CA19-9 can further improve the diagnostic efficacy for CRC.5.The expression of four characteristic candidate lnc RNA in patients with CRC after operation was significantly lower than that before operation,and the difference was statistically significant.(All P <0.05).6.No significant correlations were observed between circulating lnc RNA levels and clinicopathological parameters including age,gender,tumor location,tumor size,tumor differentiation,TNM stage,the extent of lymph node metastasis and distant metastasis.Conclusions: Our present study indicates that plasma lnc RNA ZFAS1,SNHG11,LINC00909 and LINC00654 could be used as potential circulatory markers for clinical diagnosis and postoperative monitoring of CRC,especially for the detection of plasma ZFAS1 and SNHG11,which may contribute to the early detection of precancerous lesions and reducing the incidence of CRC.