A Preliminary Study Of Hsa_circ₀006401 As A Diagnostic Biomarker Of Gastric Adenocarcinoma

Background:Gastric cancer（GC）incidence and mortality remain high in China.Nontheless,the five-year survival rate of GC patients could be around 90%under the circumstances that they get proper treatment.Despite existing methods such as gastroscope,CT and some laboratory diagnostic items have applied to diagnose GC,those are not appropriate for screening among populations in view of the invasive characteristic,high expenditure or lower sensitivity and specificity.Therefore,it is vital and imperative to identify new diagnostic methods that help to distinguish GC in early stage.With the progressing of molecular biology,it has been described by literature that abnormal expression of non-coding RNA,including circRNA（circular RNA）,is related to malignant tumors.Our research was to identify a circRNA as a diagnostic biomarker of gastric adenocarcinoma（GA）based on the result of high throughput chips.Methods:（1）Use high throughput chips to examine the expression level of circRNA in GA tissues.Select unreported and at least two-fold up-regulated or down-regulated circRNA expressed in GA as target molecules.（2）Use RT-qPCR to examine the expression level of the target circRNA in tissues（GA,para-carcinoma and chronic atrophic gastritis）.Analyze the relationship between the expression level of the target circRNA and clinicopathological characteristics and evaluate it as a diagnostic biomarker of GA.（3）Use RT-qPCR to examine the expression level of the target circRNA in plasma（GA,chronic atrophic gastritis,colorectal cancer and esophagus cancer patients and healthy population）.Analyze the relationship between the expression level of the target circRNA and clinicopathological characteristics and evaluate it as a diagnostic biomarker of GA.Results:（1）Having been screened by high throughput chips,there existed circRNAs that were associated with GA and at least 2-fold up-regulated or down-regulated in GA tissues than para-carcinoma tissues.Hsa_circ₀006401 is located in chr2:238242092-238245175（genomic length:3083nt）,up-regulating 4.99-fold in GA tissues than paired para-carcinoma tissues examined.There are 17 target miRNAs（microRNAs）of hsa_circ₀006401.（2）The expression level of hsa_circ₀006401 in GA tissues was significantly higher than that in paired para-carcinoma tissues（P<0.001）and chronic atrophic gastritis tissues（P=0.008）.There was no significant relationship（P>0.05）between the expression level of hsa_circ₀006401 and the clinicopathological characteristics.（3）The expression level of hsa_circ₀006401 in preoperative plasma of GA patients was significantly higher than that in their paired postoperative plasma（P=0.005）and in the plasma of both esophagus cancer patients（P=0.028）and healthy population（P=0.039）.Nevertheless,the difference of the expression level of hsa_circ₀006401 was not significant in the plasma of both colorectal cancer patients（P=0.450）and chronic atrophic gastritis patients（P=0.546）compared with that in GA patients.There was no significant relationship（P>0.05）between the expression level of hsa_circ₀006401 and the clinicopathological characteristics.For plasma examinations,the area under the ROC curve of hsa_circ₀006401 was 0.606（95%CI:[0.512,0.700]）.The cut-off value（ΔCt value）was 6.02.The sensitivity and specifity were 0.68 and 0.59,respectively.Conclusion:The expression level of hsa_circ₀006401 in GA tissues was significantly higher than its control groups.The expression level of hsa_circ₀006401 in preoperative plasma of GA patients was significantly higher than that in healthy population.Consequently,hsa_circ₀006401 would probably be a potential diagnostic biomarker of GA.