Aberrant Expression of the Long Non-coding RNA GHRLOS and Its Prognostic Significance in Patients with Colorectal Cancer

Long non-coding RNAs (lncRNAs), which have emerged as important regulatory RNA molecules that have been implicated in carcinogenesis and cancer progression, may also serve as novel potential biomarkers for cancer diagnosis and prognosis. Our previous analysis has identified the lncRNA GHRLOS, the ghrelin antisense strand non-coding RNA gene, as one of the hub genes in the co-expression network of differentially expressed lncRNAs/mRNAs in colorectal cancer (CRC). Here, we further evaluate the expression of GHRLOS in CRC and explore its clinical significance. The expression of GHRLOS in 366 pairs of CRC and adjacent non-cancerous tissues was detected by quantitative RT-PCR assays. The results showed that the expression level of GHRLOS was significantly lower in CRC tissues than in matched non-cancerous tissues (P < 0.001). Decreased GHRLOS expression was observed in 54.4% (199/366) of cases, and was significantly correlated with the occurrence of lymph node metastasis (P = 0.033) and distant metastasis (P = 0.005). A Kaplan-Meier analysis demonstrated that decreased GHRLOS expression contributed to poor disease-free survival (log-rank test, P < 0.001) and overall survival (log-rank test, P < 0.001). Moreover, a multivariate Cox regression analysis revealed the decreased expression of GHRLOS as an independent prognostic marker of poor outcomes [disease-free survival: hazard ratio (HR) = 2.02, 95% confidence interval (CI) = 1.42-3.88; overall survival: HR = 1.96, 95% CI = 1.34-2.86] in CRC patients. In conclusion, our data suggest that the lncRNA GHRLOS might serve as a candidate biomarker of tumor metastasis and a prognostic indicator in CRC.