Expression of PTTG (pituitary tumor transforming gene) in esophageal cancer

Recently, a vertebrate securin [pituitary tumor transforming gene (PTTG) in humans] has been identified that inhibits sister chromatid separation and is involved in malignant transformation and tumorigenesis. Abundance of this protein would disrupt cell division, generate chromosomal instability and thereby increase cell susceptibility to acquisition of further mutations during subsequent division. Esophageal cancer is a disease with poor prognosis with early local invasion and lymph node metastasis. It is important to identify factors that influence the aggressiveness of esophageal cancer.

Expression of PTTG messenger ribonucleic acid (mRNA) was evaluated by real-time reverse transcription polymerase chain reaction in 48 esophageal cancer specimens and matched normal esophageal mucosa. The data were analyzed with reference to clinicopathological factors.

Tumor tissue expressed a significantly higher level of PTTG1 mRNA than the corresponding normal tissue (P < 0.0001). PTTG1 mRNA expression was significantly higher in tumors with higher pathological stage (IV vs 0-III, P = 0.0442) or more extensive lymph node metastasis (pathological N factor; N4 vs N0-3, P = 0.003). The median survival for patients with high PTTG1 expression (8.5 months) was less than that for patients with low PTTG1 expression (14.0 months, P = 0.039). PTTG1 expression was one of the significant predictors of survival on univariate analysis (hazard ratio 2.225; 95% confidence interval 1.007-4.915).

Detection of high PTTG1 expression in surgically excised esophagus tumor tissues might help to identify patients with aggressive disease who require adjuvant therapy and provide prognostic information.