Abstract 1634: Targeting L1 cell adhesion molecule using lentivirus-mediated short hairpin RNA interference reverses aggressiveness of oral squamous cell carcinoma

Abstract

Abstract Oral cancer consistently ranks as one of the ten most frequently diagnosed cancers in the world. Despite multidisciplinary treatment with surgery, chemotherapy, and radiation, more than 50% of patients with oral squamous cell carcinoma (OSCC) receiving therapy will eventually develop recurrent and metastatic disease, which carries a particularly poor prognosis. Characterization of the specific molecular alternations associated with OSCC cell growth, invasion, and metastasis can advance our understanding of the molecular mechanisms underlying cancer induction and progression as well provide a basis for the development of new and effective therapeutic treatments for cancer patients. The L1 cell adhesion molecule (L1CAM) has been implicated in tumor progression of many types of cancers, but its role in OSCC has not been investigated. In the present study, we demonstrated overexpression of L1CAM in OSCC cells, but not in normal keratinocytes, using both clinical specimens and cell lines. This overexpression demonstrated a strong correlation with less differentiation and a higher invasion potential of cancer cells, supporting the significance of L1CAM in human OSCC tumor progression. Targeting L1CAM gene expression in SCC4 cells overexpressing L1CAM using a lentivirusmediated small hairpin RNA (shRNA) led to a significant reduction in cell proliferation in vitro via retardation of cell cycle at the G1 phase. In addition, shRNA knockdown of L1CAM strongly attenuated the migration and invasion of SCC4 cells, and this was also observed to parallel increased E-cadherin levels and decreased levels vimentin, fibronectin, and Snail-family transcription factors, indicating that L1CAM expression was related to the epithelial-mesenchymal transition. Furthermore, while mice receiving orthotopically placed control SCC4 cells died within 40 days due to invasive tumor growth and regional lymph node metastasis, prolonged animal survival and complete suppression of tumor progression was observed in mice implanted with L1CAM-deficent SCC4 cells, further substantiating the fundamental importance of L1CAM in OSCC pathophysiology. Our findings suggested that L1CAM is a critical mediator of tumor progression in OSCC, and targeting L1CAM using lentivirus-mediated shRNA may be a useful molecular pharmaceutical approach for the treatment of advanced OSCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1634. doi:10.1158/1538-7445.AM2011-1634