Purpose: Oral squamous cell carcinoma (OSCC), like many solid tumors, contains a heterogeneous population of cancer cells. Recent data suggest that a rare subpopulation of cancer cells, termed cancer stem cells (CSC), is capable of initiating, maintaining, and expanding the growth of tumor. Identification and characterization of CSC from OSCC facilitates the monitoring, therapy, or prevention of OSCC. Experimental Design: We enriched oral cancer stem-like cells (OC-SLC) through sphere formation by cultivating OSCC cells from established OSCC cell lines or primary cultures of OSCC patients within defined serum-free medium. Differential expression profile of stemness genes between enriched OC-SLC and parental OSCC was elucidated. Furthermore, immunohistochemical staining of stemness markers on OSCC patient tissues was examined to evaluate the association between stemness genes and prognosis of OSCC. Results: Enriched OC-SLC highly expressed the stem/progenitor cell markers and ABC transporter gene (Oct-4, Nanog, CD117, Nestin, CD133, and ABCG2) and also displayed induced differentiation abilities and enhanced migration/invasion/malignancy capabilities in vitro and in vivo. Elevated expression of CD133 was shown in the enriched OC-SLC from OSCC patients' tumors. Positive correlations of Oct-4, Nanog, or CD133 expression on tumor stage were shown on 52 OSCC patient tissues. Kaplan-Meier analyses exhibited that Nanog/Oct-4/CD133 triple-positive patients predicted the worst survival prognosis of OSCC patients. Conclusion: We enriched a subpopulation of cancer stem-like cell from OSCC by sphere formation. The enriched OC-SLC possesses the characteristics of both stem cells and malignant tumors. Additionally, expression of stemness markers (Nanog/Oct-4/CD133) contradicts the survival prognosis of OSCC patients.

Here we report the genetic and proposed molecular basis for silver resistance in pathogenic microorganisms. The silver resistance determinant from a hospital burn ward Salmonella plasmid contains nine open reading frames, arranged in three measured and divergently transcribed RNAs. The resistance determinant encodes a periplasmic silver-specific binding protein (SilE) plus apparently two parallel efflux pumps: one, a P-type ATPase (SilP); the other, a membrane potential-dependent three-polypeptide cation/proton antiporter (SilCBA). The sil determinant is governed by a two-component membrane sensor and transcriptional responder comprising silS and silR, which are co-transcribed. The availability of the sil silver-resistance determinant will be the basis for mechanistic molecular and biochemical studies as well as molecular epidemiology of silver resistance in clinical settings in which silver is used as a biocide.

BackgroundHead and neck squamous cell carcinoma (HNSCC) is a highly lethal cancer that contains cellular and functional heterogeneity. Previously, we enriched a subpopulation of highly tumorigenic head and neck cancer initiating cells (HN-CICs) from HNSCC. However, the molecular mechanisms by which to govern the characteristics of HN-CICs remain unclear. GRP78, a stress-inducible endoplasmic reticulum chaperone, has been reported to play a crucial role in the maintenance of embryonic stem cells, but the role of GRP78 in CICs has not been elucidated.ResultsInitially, we recognized GRP78 as a putative candidate on mediating the stemness and tumorigenic properties of HN-CICs by differential systemic analyses. Subsequently, cells with GRP78 anchored at the plasma membrane (memGRP78+) exerted cancer stemness properties of self-renewal, differentiation and radioresistance. Of note, xenotransplantation assay indicated merely 100 memGRP78+ HNSCCs resulted in tumor growth. Moreover, knockdown of GRP78 significantly reduced the self-renewal ability, side population cells and expression of stemness genes, but inversely promoted cell differentiation and apoptosis in HN-CICs. Targeting GRP78 also lessened tumorigenicity of HN-CICs both in vitro and in vivo. Clinically, co-expression of GRP78 and Nanog predicted the worse survival prognosis of HNSCC patients by immunohistochemical analyses. Finally, depletion of GRP78 in HN-CICs induced the expression of Bax, Caspase 3, and PTEN.ConclusionsIn summary, memGRP78 should be a novel surface marker for isolation of HN-CICs, and targeting GRP78 signaling might be a potential therapeutic strategy for HNSCC through eliminating HN-CICs.

Cancer-initiating cells (CIC) comprise a rare subpopulation of cells in tumors that are proposed to be responsible for tumor growth. Starting from CICs identified in head and neck squamous cell carcinomas (HNSCC), termed head and neck cancer-initiating cells (HN-CIC), we determined as a candidate stemnessmaintaining molecule for HN-CICs the proinflammatory mediator S100A4, which is also known to be an inducer of epithelial-mesenchymal transition. S100A4 knockdown in HN-CICs reduced their self-renewal capability and their stemness and tumorigenic properties, both in vitro and in vivo. Conversely, S100A4 overexpression in HNSCC cells enhanced their stem cell properties. Mechanistic investigations indicated that attenuation of endogenous S100A4 levels in HNSCC cells caused downregulation of Notch2 and PI3K (phosphoinositide 3-kinase)/pAKT along with upregulation of PTEN, consistent with biological findings. Immunohistochemical analysis of HNSCC clinical specimens showed that S100A4 expression was positively correlated with clinical grading, stemness markers, and poorer patient survival. Together, our findings reveal a crucial role for S100A4 signaling pathways in maintaining the stemness properties and tumorigenicity of HN-CICs. Furthermore, our findings suggest that targeting S100A4 signaling may offer a new targeted strategy for HNSCC treatment by eliminating HN-CICs. Cancer Res; 71(5); 1912-23. Ó2010 AACR.