Abstract 636: An orthotopic xenograft animal model for functional analysis of podoplanin in oral squamous cell carcinoma

Abstract

Podoplanin (PDPN) is a marker for poor prognosis in human oral squamous cell carcinoma (OSCC). Subcutaneous or intravenous injection of OSCC cells has been used in a number of studies as the animal models to investigate the function of PDPN in OSCC cancer progression. However, these models usually overlook the potential interactions between cancer cells and the microenvironment of oral cavity. In this study, we aimed to establish an animal model for functional and mechanistic study of PDPN in OSCC by taking into account the influence of the microenvironment of oral cavity. Profiling of nine human OSCC cell lines revealed that PDPN was highly expressed in five of the cell lines, including OECM-1, OC2, TW2.6, HSC-3 and CAL27. Notably, OECM-1 cells were shown by immunofluorescence staining to compose of two different cell populations with highly expression (P+) or absence (P-) of PDPN. To preclude the potential artifacts associated with gene overexpression study, the P+ cells were isolated by fluorescence-activated cell sorting followed by establishing the sublines shLacZ or shPDPN that co-expressed luciferase and the short-hairpin RNA targeting on β-galactosidase or pdpn. In vitro analysis revealed no difference for the cell growth of shLacZ and shPDPN cells on day 5 (p = 0.79). Orthotopic xenograft animal model for functional analysis of PDPN in OSCC was established by inoculating shLacZ or shPDPN cells into the anterior neck region of athymic nude mice. Consistent with the in vitro assays, there is no difference in the growth of the tumors derived from shLacZ and shPDPN cells (p > 0.05). Notably, the survival of the mice bearing tumors derived from shPDPN cells was significantly prolonged when compared with the mice bearing shLacZ cells-derived tumors (p < 0.001). At day 50 after orthotopic inoculation of cancer cells, 10% (n = 10, 1/10) and 90% (n = 10, 9 /10) of the mice bearing tumors derived from shLacZ and shPDPN cells was alive, respectively. These results were consistent with the notion that PDPN is a poor prognosis factor for the patients with OSCC. In contrast to the orthotopic xenograft model, subcutaneous injection of shLacZ and shPDPN cells into the athymic nude mice did not result in a significant increase in tumor growth and tumor size. These data further demonstrate that the microenvironment of the oral cavity has significant effect on promoting the survival and growth of OSCC cells. The orthotopic xenograft mouse model we established in this study represents a useful model for functional and mechanistic study of PDPN in the cancer progression of OSCC. Citation Format: Hsing-Ying Lee, Yao-Wen Chang, Ju-Chien Cheng, Ching-Ping Tseng. An orthotopic xenograft animal model for functional analysis of podoplanin in oral squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 636.