Abstract 3305: Markers of epithelial-mesenchymal transition as indicators of prognosis in lymph node aspirates from lung cancer patients

Abstract

Abstract Lung cancer accounts for the largest number of cancer-related deaths worldwide. Despite a new more discriminatory staging system for predicting survival, great variation in outcome within stage persists. Gene expression arrays and microRNA signatures from surgically resected primary tumors can predict survival and drug sensitivity within stage I disease better than standard staging protocols. Genes associated with epithelial mesenchymal transition (EMT) contribute to the malignant phase of tumor cell growth by controlling the switch to a metastatic phenotype. We hypothesize that the analysis of expression of EMT markers in thoracic lymph nodes may predict survival outcomes and drug responses in lung cancer patients. Endobronchial ultrasound fine needle aspiration (EBUS-FNA) of lymph nodes was performed on patients with known or suspected lung cancer to diagnose and/or stage disease. Total RNA was isolated from the FNA specimens, reverse transcribed, and analyzed for expression of a panel of genes associated with EMT using a probe-based real-time quantitative polymerase chain reaction (pqRT-PCR). Samples were analyzed for the expression of the epithelial markers cytokeratin 17 (CK17) and cytokeratin 19 (CK19) and the EMT markers Ecadherin (ECAD), Ncadherin (NCAD), and transcription factors snail, slug, ZEB1 and ZEB2. Samples from thirty-seven patients were processed for the study. Patients with metastatic disease had higher levels of snail and NCAD and lower levels of slug and ZEB2 compared to node negative and node positive patients, while patients with node negative disease had higher slug and lower levels of NCAD compared to node positive patients. ECAD did not vary by node positivity or presence of metastasis. The patients with adenocarcinoma on cytology showed higher levels of ECAD and snail, while patients diagnosed with squamous cell carcinoma had higher levels of ZEB1. In contrast, two patients with benign disease had low levels of all markers. Four patients with cytopathologically negative nodes expressed the epithelial markers CK17 and CK19, which are not typically present in lymph nodes. In limited follow-up, two patients with cytopathologically negative lymph nodes but high levels of ZEB1 had progression of disease. From this pilot study we have shown that EBUS-FNA consistently provides adequate samples from which RNA can be isolated and that genes associated with EMT can be used to identify cancer cells that have migrated to adjacent lymph nodes. We plan to enroll a total of 100 patients and follow them for 2 years to determine if this technique can identify patients at higher risk of metastatic disease. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3305.