Huntingtin-Interacting Protein-1 Is an Early-Stage Prognostic Biomarker of Lung Adenocarcinoma and Suppresses Metastasis via Akt-mediated Epithelial-Mesenchymal Transition.

RATIONALE: Non-small cell lung cancer (NSCLC) carries a poor survival rate mainly because of metastasis. However, the molecular mechanisms that govern NSCLC metastasis have not been described. Because huntingtin-interacting protein-1 (HIP1) is known to play a role in tumorigenesis, we tested the involvement of HIP1 in NSCLC progression and metastasis.
OBJECTIVES: HIP1 expression was measured in human NSCLC tumors, and correlation with survival outcome was evaluated. Furthermore, we investigated the ability of HIP1 to suppress metastasis. The molecular mechanism by which HIP1 contributes to suppress metastasis was investigated.
METHODS: We used tissue arrays containing samples from 121 patients with NSCLC to analyze HIP1 expression by immunohistochemistry. To investigate the role of HIP1 expression on metastasis, we evaluated cellular mobility, migration, and invasion using lung adenocarcinoma (AdCA) cells with modified HIP1 expression levels. The human disease mouse models with the same cells were applied to evaluate the HIP1 suppressing metastasis and its mechanism in vivo.
MEASUREMENTS AND MAIN RESULTS: HIP1 expression in AdCA progression was found to be an early-stage prognostic biomarker, with low expression correlated to poor prognosis. We also found HIP1 to be a metastatic suppressor in AdCA. HIP1 significantly repressed the mobility of lung cancer cells in vitro and in vivo and regulated the epithelial-mesenchymal transition by repressing AKT/glycogen synthase kinase-3β/β-catenin signaling.
CONCLUSIONS: HIP1 serves as an early-stage prognostic biomarker and a metastatic suppressor. Reduced expression during AdCA progression can relieve HIP1 suppression of Akt-mediated epithelial-mesenchymal transition and thereby lead to development of late metastases and poor prognosis.