WNT5A promotes stemness characteristics in nasopharyngeal carcinoma cells leading to metastasis and tumorigenesis

Nasopharyngeal carcinoma (NPC) has the highest metastasis rate among head and neck cancers with unclear mechanism. WNT5A belongs to the WNT family of cysteine-rich secreted glycoproteins. Our previous high-throughput gene expression profiling revealed that WNT5A was up-regulated in highly metastatic cells. In the present study, we first confirmed the elevated expression of WNT5A in metastatic NPC tissues at both the mRNA and protein levels. We then found that WNT5A promoted epithelial-mesenchymal transition (EMT) in NPC cells, induced the accumulation of CD24-CD44+ cells and side population, which are believed to be cancer stem cell characteristics. Moreover, WNT5A promoted the migration and invasion of NPC cells in vitro, while in vivo treatment with recombinant WNT5A promoted lung metastasis. Knocking down WNT5A diminished NPC tumorigenesis in vivo. When elevated expression of WNT5A coincided with the elevated expression of vimentin in the primary NPC, the patients had a poorer prognosis. Among major signaling pathways, protein kinase C (PKC) signaling was activated by WNT5A in NPC cells. A positive feedback loop between WNT5A and phospho-PKC to promote EMT was also revealed. Taken together, these data suggest that WNT5A is an important molecule in promoting stem cell characteristics in NPC, leading to tumorigenesis and metastasis.

Urokinase-type plasminogen activator receptor signaling is critical in nasopharyngeal carcinoma cell growth and metastasis

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies in southern China and Southeast Asia, with the highest metastasis rate among head and neck cancers. The mechanisms underlying NPC progression remain poorly understood. Genome-wide expression profiling on 18 NPC vs. 18 noncancerous nasopharyngeal tissues together with GeneGo pathway analysis and expression verification in NPC cells and tissues revealed a potential role of urokinase-type plasminogen activator receptor (uPAR) in NPC progression, which has not been investigated in NPC. We then observed that uPAR expression is increased in poorly differentiated, highly metastatic NPC cells compared with lowly metastatic cells or differentiated NPC cells. In vitro studies demonstrated that uPAR regulates NPC cell growth, colony formation, migration, and invasion and promotes the epithelial-mesenchymal transition (EMT). Additional tumor xenograft and spontaneous metastasis experiments revealed that uPAR promotes NPC cell growth and metastasis in vivo. The JAK-STAT pathway is involved in uPAR-regulated signaling in NPC cells as determined by immunoblotting. Moreover, uPAR-mediated growth and motility is partially abolished upon treatment with the Jak1/Jak2 inhibitor INCB018424. We suppressed uPA expression in uPAR-overexpressing NPC cells and found that uPAR-mediated cellular growth and motility is not exclusively dependent on uPA. In summary, uPAR is a significant regulator of NPC progression and could serve as a promising therapeutic target.

Repressing malic enzyme 1 redirects glucose metabolism, unbalances the redox state, and attenuates migratory and invasive abilities in nasopharyngeal carcinoma cell lines

A large amount of nicotinamide adenine dinucleotide phosphate (NADPH) is required for fatty acid synthesis and maintenance of the redox state in cancer cells. Malic enzyme 1(ME1)-dependent NADPH production is one of the three pathways that contribute to the formation of the cytosolic NADPH pool. ME1 is generally considered to be overexpressed in cancer cells to meet the high demand for increased de novo fatty acid synthesis. In the present study, we found that glucose induced higher ME1 activity and that repressing ME1 had a profound impact on glucose metabolism of nasopharyngeal carcinoma(NPC) cells. High incorporation of glucose and an enhancement of the pentose phosphate pathway were observed in ME1-repressed cells. However, there were no obvious changes in the other two pathways for glucose metabolism: glycolysis and oxidative phosphorylation. Interestingly, NADPH was decreased under low-glucose condition in ME1-repressed cells relative to wild-type cells, whereas no significant difference was observed under high-glucose condition. ME1-repressed cells had significantly decreased tolerance to low-glucose condition. Moreover, NADPH produced by ME1 was not only important for fatty acid synthesis but also essential for maintenance of the intracellular redox state and the protection of cells from oxidative stress. Furthermore, diminished migration and invasion were observed in ME1-repressed cells due to a reduced level of Snail protein. Collectively, these results suggest an essential role for ME1 in the production of cytosolic NADPH and maintenance of migratory and invasive abilities of NPC cells.

As an independent unfavorable prognostic factor, IL-8 promotes metastasis of nasopharyngeal carcinoma through induction of epithelial-mesenchymal transition and activation of AKT signaling

Nasopharyngeal carcinoma (NPC) has the highest metastatic potential among head and neck cancers. Distant metastasis is the major cause of treatment failure. The role of interleukin-8 (IL-8) in NPC progression remains unknown. Our multivariate survival analyses of 255 patients with NPC revealed that higher IL-8 expression in primary NPC tissue was an independent prognostic factor for overall survival, disease-free survival, and distant metastasis-free survival of the patients. In vitro study revealed that IL-8 was highly expressed in the established high-metastasis NPC clone S18 relative to the low-metastasis cells. Suppression of IL-8 by short-hairpin RNA reduced the expression of IL-8 in S18 cells and subsequently inhibited migration, invasion, and hepatic metastasis of the cells without influencing cellular growth. Overexpression of IL-8 in S26 cells resulted in increased migration, invasion, and metastasis capabilities of the cells without affecting cellular growth. Exogenous IL-8 enhanced the migration and invasion of low-metastasis CNE-2 cells in a dose-dependent manner. An epithelial–mesenchymal transition (EMT) could be induced by IL-8 in various NPC cell lines. The high level of phosphorylated AKT in S18 cells could be suppressed by knocking down IL-8 expression. Further, IL-8-promoted migration and invasion could be abolished by either the application of the phosphoinositide-3-kinase inhibitor LY294002 or the knock down of AKT expression by using small-interfering RNA. In summary, IL-8 serves as an independent prognostic indicator of overall survival, disease-free survival, and metastasis-free survival for patients with NPC. IL-8 promotes NPC metastasis via autocrine and paracrine means, involving activation of AKT signaling and inducing EMT in NPC cells.

Abstract 1476: Serglycin in nasopharyngeal carcinoma: A metastasis regulator and prognostic indicator

Serglycin is a proteoglycan consisting of a core protein to which negatively charged glycoaminoglycan (GAG) chains of either chondroitin sulfate or heparin are attached.

Serglycin was first shown to be essential for the maturation of mast cell secretory granules, but it has recently been shown to be present within multiple other cell types. In this study we describe for the first time the role of serglycin as a potential metastasis regulator in nasopharyngeal carcinoma (NPC), a tumor that has the highest incidence of metastasis among head and neck cancers. The recognition that serglycin plays an important role in NPC comes from our earlier genomic expression profiles comparing clones derived from the NPC cell line CNE-2, where serglycin (SRGN) was identified as one of the most up-regulated genes in the high-metastasis Clone 18. The genomic expression profiling was performed on samples collected in cultured cells and in xenograft tumors generated from Clone-18, as well as low-metastasis clones (Clone-22, Clone-26) and their parental line, CNE-2. A popliteal lymph node model was used to evaluate the metastasis ability of different cellular populations. A tissue microarray was constructed from 330 NPC tissues and a total of 263 cases were informative for assessing the patients’ survival duration. A deglycosylation assay, lentiviral transduction, quantitative PCR, proliferation assay, Transwell assay, and wound-healing assay were used for the functional studies. The serglycin protein was shown to be secreted by the high-metastasis clone, but not by any of the low-metastasis clones. Suppression of serglycin by shRNA diminished serglycin secretion and subsequently inhibited migration and invasion by the high-metastasis clone, and also significantly reduced its metastasis rate in vivo. Overexpression of serglycin in low-metastasis cells resulted in a significantly increased metastasis rate in vivo. Moreover, secreted serglycin promoted cellular motility in the wild-type low-metastasis cells. Interestingly, suppression of serglycin reduced the protein level of vimentin but did not influence the level of E-cadherin in the high-metastasis clone. Proliferation was not influenced by serglycin in either the high- or low-metastasis clones. Importantly, in direct tumor samples, serglycin expression was significantly elevated in liver metastases from NPC relative to its expression in primary tumors. In conclusion, serglycin appears to play a potentially pivotal role in regulating NPC metastasis by way of enhancing cellular migration, cellular invasiveness, vimentin expression level, and the in vivo spread of cancer cells. Moreover, a high level of serglycin expression can potentially be used to predict shorter disease-free survival and shorter metastasis-free survival of NPC patients. Targeting serglycin could be a novel option for the prevention of NPC metastasis.

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 1476. doi:10.1158/1538-7445.AM2011-1476

Abstract 494: Stemness characteristics contribute to metastasis and shorter patient survival in nasopharyngeal carcinoma

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

Abstract 57: Integrating transcriptome profiling and in silico pathway analysis toward reduction of therapeutic dimensionality in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has its highest incidence in southern China and Southeast Asia. In order to obtain deeper insights into the molecular mechanism of NPC tumorigenesis, we performed genome expression profiling combined with computerized pathway analyses on 18 NPC tissues and 18 age-matched tissues of non-cancerous nasopharyngeal mucosa from individuals in the endemic area, Guangdong province, China, between Dec 2007 and Oct 2010. Gene expression profiling was performed using an Agilent gene expression kit and Agilent 4×44K microarray gene chips. One-way analysis of variance was used to identify the genes differentially expressed between cancer and non-cancerous tissues. Genes with a false discovery rate of less than 0.001 and a fold-change larger than 2 or less than 0.5 were selected for in silico network mapping combined with pathway analysis using GeneGo software. Pathways were prioritized based on the gene enrichment analysis. The genes’ connectivity was also integrated to identify the regulatory hotspots in the key pathways. Genes within or surrounding these hotspots constitute potential therapeutic targets. Genes previously known to be up-regulated in NPC that were detected in our study included CCND1, CDKN1A, STAT1, BCL2A1, SGK1, RAI14, FOXM1, EPHB2, PMAIP1, COL1A1, GADD45A, ICAM1, FANC1, ZWINT, LAMB3, CKAP4, ISG15, and MMP3; known down-regulated genes included ATM and INPP5D. However, what was of interest was the identification of a series of previously unrecognized genes: those up-regulated more than 10-fold included MMP1, HOXC8, KREMEN2, and HOXA1, and those down-regulated more than 10-fold included LTF, C7, SHISA3, SKLC26A7, and C16orf89. Although the deregulated pathways in NPC encompass many cytological functions, pathway analysis has been helpful in ranking a series of the most significant deregulated pathways, which include ECM remodeling pathways; alternative complement pathway; plasmin signaling pathway; the TGF, WNT, and cytoskeletal remodeling pathways; leukocyte chemotaxis pathway; and the BAFF and PLAU signaling pathways. Results will be presented on key genetic changes within these pathways that have been verified by biologically. In conclusion, we are beginning to recognize key genes and pathways, prioritized by pathway analysis, that appear likely to identify possible novel mechanisms of NPC tumorigenesis.

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 57. doi:10.1158/1538-7445.AM2011-57

Serglycin is a theranostic target in nasopharyngeal carcinoma that promotes metastasis

Nasopharyngeal carcinoma (NPC) is known for its high-metastatic potential. Here we report the identification of the proteoglycan serglycin as a functionally significant regulator of metastasis in this setting. Comparative genomic expression profiling of NPC cell line clones with high- and low-metastatic potential revealed the serglycin gene (SRGN) as one of the most upregulated genes in highly metastatic cells. RNAi-mediated inhibition of serglycin expression blocked serglycin secretion and the invasive motility of highly metastatic cells, reducing metastatic capacity in vivo. Conversely, serglycin overexpression in poorly metastatic cells increased their motile behavior and metastatic capacity in vivo. Growth rate was not influenced by serglycin in either highly or poorly metastatic cells. Secreted but not bacterial recombinant serglycin promoted motile behavior, suggesting a critical role for glycosylation in serglycin activity. Serglycin inhibition was associated with reduced expression of vimentin but not other epithelial-mesenchymal transition proteins. In clinical specimens, serglycin expression was elevated significantly in liver metastases from NPC relative to primary NPC tumors. We evaluated the prognostic value of serglycin by immunohistochemical staining of tissue microarrays from 263 NPC patients followed by multivariate analyses. High serglycin expression in primary NPC was found to be an unfavorable independent indicator of distant metastasis-free and disease-free survival. Our findings establish that glycosylated serglycin regulates NPC metastasis via autocrine and paracrine routes, and that it serves as an independent prognostic indicator of metastasis-free survival and disease-free survival in NPC patients.