Abstract 494: Stemness characteristics contribute to metastasis and shorter patient survival in nasopharyngeal carcinoma
Authors: Zheng Fang-Jing , Qin Li , Liang Yi , Li Xin-Jian , Peng Li-Xi , Lu Wen-Hua , Bao Ying-Na , Kang Tie-Bang , Zeng Yi-Xin , Trent Jeffrey M. , Qian Chao-Nan 
Published: June 2012

Nasopharyngeal carcinoma (NPC) has the highest incidence of metastasis among head and neck cancers. The involvement of cancer stem cells (CSCs) in tumorigenesis has been studied in several malignancies, but their presence in NPC has not been extensively evaluated. The range of general characteristics of “stemness” includes increased side-population (SP) fraction, limited functional differentiation or dedifferentiation under the influence of the microenvironment, and expression of putative stem cell markers. We previously isolated a highly metastatic clone (Clone-18) from the NPC cell line CNE-2. Using this clone, we have sought to explore the influence of the stemness characteristics of NPC cells on tumor metastasis. Human tissue samples were collected under informed consent at the Sun Yat-sen University Cancer Center. SP cells were evaluated by flow cytometry. A Transwell assay and a wound-healing assay were used to evaluate the migratory and invasive abilities of the cells. Lung metastasis was evaluated by injecting tumor cells into the tail vein of BALB/c nude mice. Real-time PCR and western blotting were used for a protein kinase C (PKC) pathway study. Tissue microarrays and immunohistochemical staining were used to evaluate the correlation between vimentin and the survival time of patients with nasopharyngeal carcinoma. Clone-18 cells possessed a very high percentage of SP cells (62.1 ± 1.39%) relative to low-metastasis clones (Clone-22, 7.2 ± 1%; Clone-26, 3.9 ± 0.9%) or the parental CNE-2 cells (27.9 ± 2.02%), implying that there were more stem-like cells in the high-metastasis clones. Two stem cell markers, WNT5A and vimentin, were also highly expressed in the high-metastasis clone cells. To confirm the clinical relevance of these findings, human tissue samples were used. The mRNA level for WNT5A was significantly higher in regional metastatic NPC tissues (n = 4) than in primary tumors (n = 20), and it was much higher in liver metastatic NPC (n = 5) than in regional metastatic tissues. In the cohort of 282 NPC patients, a higher vimentin level in the primary tumor, as detected by IHC staining, correlated with shorter overall survival. Suppression of WNT5A by siRNA significantly reduced the migratory and invasive abilities of Clone-18 cells, and this effect was shown to be regulated by activating protein kinase C (PKC). The activated PKC further regulated the expressions of Snail and E-cadherin, which subsequently induced an EMT in NPC cells. In vivo experiments showed that the administration of recombinant WNT5A protein could promote lung metastasis by the low-metastasis Clone-26 cells in the lung metastasis mouse model. In conclusion, the stemness characteristics of NPC cells have been shown to contribute to the migratory, invasive, and metastatic phenotype of this important malignancy, with WNT5A directly regulating these properties and being a critical candidate marker of CSCs.

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 494. doi:10.1158/1538-7445.AM2011-494