High NHLRC2 expression is associated with shortened survival in lung adenocarcinoma

BACKGROUND: Certain variants of NHL repeat (named after NCL-1, HT2A and LIN-41)-containing protein 2 (NHLRC2) gene have been linked to severe fibrotic interstitial lung disease in children. The aim of the current study was to evaluate the expression of NHLRC2 in lung cell and tissue samples from patients with lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC). METHODS: The expression of NHLRC2 in lung tissue samples was studied by immunohistochemistry (102 ADC, 111 SCC), mRNA in situ hybridization (4 ADC, 3 SCC), and Western blot analysis (3 ADC, 2 SCC). The immunohistochemical NHLRC2 expression was measured by image analysis software and the percentage of NHLRC2-positive cancer cells was evaluated by semiquantitative analysis. The immunohistochemical results of NHLRC2 were compared with the clinical and histological characteristics of the patients. NHLRC2 protein levels in primary stromal and epithelial lung cancer cell lines were measured by Western blot analysis. RESULTS: NHLRC2 was mainly expressed in cancer cells and inflammatory cells within the tumor. The NHLRC2 expression evaluated by image analysis method was significantly higher in ADC compared with that in SCC (P<0.001). High NHLRC2 expression was associated with reduced disease specific survival (P=0.002), overall survival (P=0.001), and high mitotic activity (P=0.042) in ADC. Additionally, the proportion of NHLRC2-positive cancer cells analyzed by the semiquantitative method was significantly higher in ADC than in SCC (P<0.001). CONCLUSIONS: NHLRC2 expression was higher in lung ADC than in SCC and its expression was associated with poor survival in ADC patients. Further studies are required to clarify the pathogenetic role of NHLRC2 in lung cancer.