Expression and prognostic impact of alpha thalassemia/mental retardation X-linked and death domain-associated protein in human lung cancer

Molecular characterization of lung cancer specimens after radical surgery offers additional prognostic information and may help to guide adjuvant therapeutic procedures. The transcriptional regulators alpha thalassemia/mental retardation X-linked (ATRX) and death domain-associated protein (DAXX) have recently been described in different cancer entities as a useful prognostic biomarker. This study was initiated to explore their protein expression patterns and prognostic value in patients with operable lung cancer disease. The protein abundance (in the following text also named protein expression) of ATRX and DAXX were analyzed by immunohistochemistry in 194 samples of squamous cell lung carcinoma (SQCLC), 111 samples of pulmonary adenocarcinoma (AC) and 40 samples of small cell lung cancer (SCLC). The protein levels of ATRX and DAXX were correlated with clinicopathological characteristics and patient outcome. ATRX showed strong protein expression in 16.2% of AC, 11.9% of SQCLC, and 42.5% of SCLC. DAXX was highly expressed in 54.9% of AC, 76.2% of SQCLC, and 82.5% of SCLC. Immunostaining of both ATRX and DAXX were seen in 14.4% of AC, 11.3% of SQCLC, and 42.5% of SCLC. High protein expression of ATRX was a favorable prognostic marker for patients with AC (hazard ratio 0.38, P = .02). Sub-group analyses showed a significant correlation between ATRX and the clinical stage of SQCLC and SCLC. Histological grading and ATRX were also significantly associated in cases of SQCLC. The presence of ATRX and DAXX are correlated with lung cancer histology. Strong ATRX protein expression is associated with a significantly longer overall survival in patients with AC.