Identification of CDK6 and RHOU in Serum Exosome as Biomarkers for the Invasiveness of Non-functioning Pituitary Adenoma

Objective To explore circulating biomarkers for screening the invasiveness of non-functioning pituitary adenomas(NF-PAs).Methods The exosomal RNAs were extracted from serum of patients with invasive NF-PA(INF-PA)or noninvasive NF-PA(NNF-PA).Droplet digital PCR was adapted to detect the mRNA expression of candidate genes related to tumor progression or invasion,such as cyclin dependent kinase 6(CDK6),ras homolog family member U(RHOU),and spire type actin nucleation factor 2(SPIRE2).Student’s t-test was used to analyze the statistical difference in the mRNA expression of candidate genes between the two groups.Receiver operating characteristic(ROC)curve was used to establish a model for predicting the invasiveness of NF-PAs.The accuracy,sensitivity,specificity and precision of the model were then obtained to evaluate the diagnostic performance.Results CDK6(0.2600±0.0912 vs.0.1789±0.0628,t=3.431,P=0.0013)and RHOU mRNA expressions(0.2696±0.1118 vs.0.1788±0.0857,t=2.946,P=0.0052)were upregulated in INF-PAs patients’serum exosomes as compared to NNF-PAs.For CDK6,the area under the ROC curve(AUC)was 0.772(95%CI:0.600-0.943,P=0.005),the accuracy,sensitivity,specificity and precision were 77.27%,83.33%,75.00%and 55.56%to predict the invasiveness of NF-PAs.For RHOU,the AUC was 0.757(95%CI:0.599-0.915,P=0.007),the accuracy,sensitivity,specificity and precision were 72.73%,83.33%,68.75%and 50.00%.In addition,the mRNA levels of CDK6 and RHOU in serum exosomes were significantly positively correlated(r=0.935,P<0.001).After combination of the cut-off scores of the two genes,the accuracy,sensitivity,specificity and precision were 81.82%,83.33%,81.25%and 62.50%.Conclusions CDK6 and RHOU mRNA in serum exosomes can be used as markers for predicting invasiveness of NF-PAs.Combination of the two genes performs better in distinguishing INF-PAs from NNF-PAs.These results indicate CDK6 and RHOU play important roles in the invasiveness of NF-PAs,and the established diagnostic method is valuable for directing the clinical screening and postoperative treatment.