Prognostic value of ISG15 mRNA level in drinkers with esophageal squamous cell cancers.

ISG15, the protein encoded by interferon (IFN)-stimulated gene 15, was the first identified ubiquitin-like protein, which could be strongly upregulated by type I interferons as a primary response to diverse microbial and cellular stress stimuli. Although the biological activities of ISG15 have yet to be fully elucidated, it is frequently overexpressed in various cancers. As the role of ISG15 in esophageal squamous cell cancer (ESCC) has not been well reported, the current study aimed to elucidate the role of ISG15 in predicting outcomes of ESCC patients. Samples were collected from 153 ESCC patients, including 54 pairs of tumor tissues and non-tumor tissues. Compared with the paired non-tumor tissues, higher expression of ISG15 mRNA were detected in ESCC tissues. The cut-off value 1.28 determined by ROC curve analysis divided the ESCC patients into high and low ISG15 mRNA expression group. High-ISG15 mRNA expression appeared with more frequency in ever-drinkers (P = 0.018). Kaplan-Meier analysis indicated that Low-ISG15 mRNA expression group had a longer cancer-specific survival (CSS) compared with High-ISG15 mRNA expression group. Multivariate analysis revealed that ISG15 mRNA (P = 0.024; hazard ratio, 2.759, 95% CI, 1.841-4.134) as well as Pathological staging (P < 0.001; hazard ratio, 1.634, 95% CI, 1.065-2.505) were independent prognostic factors. Subgroup analysis revealed that the discernibility of ISG15 mRNA level on ESCC outcomes was only pronounced in ever-drinkers (P = 0.026) not in never-drinkers (P = 0.138). ISG15 might serve as a novel prognostic biomarker in drinkers with ESCC.