Abstract 4062: Nestin regulates proliferation, migration, invasion and stemness of lung adenocarcinoma

Abstract

Abstract Lung cancer is the most common cancer and the most common cause of cancer-related death in the world. Despite of the therapeutic advances in the treatment of non-small cell lung cancer (NSCLC) including molecular targeted therapy for lung adenocarcinoma (AD), the prognosis of the patients with NSCLC is dismal. Therefore, new treatment strategies are needed. Nestin, a class VI intermediate filament, is known to be a cancer stem cell (CSC) marker as well as a neuroepithelial stem cell marker. High expression levels of nestin are reported in various malignant tumors including lung, pancreas, cervical and prostate cancers, malignant melanomas and glioblastomas. Nestin is thought to regulate tumor cell proliferation, migration, invasion and CSC properties. Here we confirmed nestin expression in NSCLC: Immunohistochemical analysis in surgical specimens detected nestin protein expression in the cytoplasm of 20 of 48 AD cases (41.7%) and 25 of 47 squamous cell carcinoma cases (53.2%). Nestin immunoreactivity significantly correlated with not only tumor size and lymph node metastasis in NSCLC (p = 0.02, for both), but also poor survival in surgical patients with AD (p = 0.02). High and moderate expression levels of nestin were confirmed in several lung AD cell lines including H1975 and PC-3. Nestin inhibition by short hairpin RNA (shRNA) decreased proliferation, migration, invasion, and sphere formation in AD cell lines. Correspondingly, nestin upregulation by nestin gene transfection in these cells resulted in the opposite changes. Moreover, we performed screening analysis to clarify the upstream molecule that regulates nestin expression, using 95 chemical compounds that each inhibited a specific molecular target. Akt inhibitor IV led to a 72% reduction of nestin expression compared to in the DMSO-treated negative control in PC-3 cells. Akt is located downstream of the EGFR pathway, and Akt is reported to regulate SRY-box containing protein 2 (Sox2) expression and the self-renewal of CSC-like cells in NSCLC. Sox2 is also known to be a transcriptional factor for nestin. Immunohistochemically, we also confirmed co-expression of nestin, Akt, phosphorylated Akt, and Sox2 in serial tissue sections from AD cases. Thus, we performed further experiments using Akt inhibitor IV to clarify the relationship between Akt, Sox2, and nestin in AD cells. Akt inhibitor IV effectively decreased nestin expression via Sox2 downregulation and overcame the enhanced sphere formation induced by nestin upregulation. These findings suggest that nestin correlates to the aggressiveness and stemness of AD. Inhibition of nestin via Akt/Sox2 is thus a novel therapeutic approaches to eradicate lung AD and CSCs. Citation Format: Kosuke Narita, Yoko Matsuda, Masahiro Seike, Zenya Naito, Akihiko Gemma, Toshiyuki Ishiwata. Nestin regulates proliferation, migration, invasion and stemness of lung adenocarcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4062. doi:10.1158/1538-7445.AM2014-4062