Recent studies have demonstrated that cancer stem cells play an important role in the pathobiology of head and neck squamous cell carcinomas (HNSCC). However, little is known about functional interactions between head and neck cancer stem-like cells (CSC) and surrounding stromal cells. Here, we used aldehyde dehydrogenase activity and CD44 expression to sort putative stem cells from primary human HNSCC. Implantation of 1,000 CSC (ALDHþCD44þLinÀ) led to tumors in 13 (out of 15) mice, whereas 10,000 noncancer stem cells (ALDHÀCD44ÀLinÀ) resulted in 2 tumors in 15 mice. These data demonstrated that ALDH and CD44 select a subpopulation of cells that are highly tumorigenic. The ability to self-renew was confirmed by the observation that ALDHþCD44þLinÀ cells sorted from human HNSCC formed more spheroids (orospheres) in 3-D agarose matrices or ultra-low attachment plates than controls and were serially passaged in vivo. We observed that approximately 80% of the CSC were located in close proximity (within 100-mm radius) of blood vessels in human tumors, suggesting the existence of perivascular niches in HNSCC. In vitro studies demonstrated that endothelial cell-secreted factors promoted self-renewal of CSC, as demonstrated by the upregulation of Bmi-1 expression and the increase in the number of orospheres as compared with controls. Notably, selective ablation of tumorassociated endothelial cells stably transduced with a caspase-based artificial death switch (iCaspase-9) caused a marked reduction in the fraction of CSC in xenograft tumors. Collectively, these findings indicate that endothelial cell-initiated signaling can enhance the survival and self-renewal of head and neck CSC. Cancer Res; 70(23); 9969-78. Ó2010 AACR.

Caries-induced pulpitis is typically accompanied by an increase in dental pulp microvascular density. However, the mechanisms by which dental pulp cells recognize lipopolysaccharides (LPSs) remain unclear. We hypothesized that Porphyromonas endodontalis and Escherichia coli LPSs induce vascular endothelial growth factor (VEGF) expression in dental pulp stem cells (DPSC) and human dental pulp fibroblasts (HDPF) through mitogen-activated protein kinase (MAPK) signaling. ELISA, semi-quantitative RT-PCR, immunofluorescence, and Western blots were used. Here, we observed that LPSs induced VEGF expression in DPSC and HDPF cells, and both cell types express Toll-like receptor 4 (TLR- 4). Notably, LPS-induced VEGF is associated with phosphorylation of protein kinase C (PKC zeta) and extracellular signal-regulator kinase (ERK1/2) and is dependent upon MAPK activation. Analysis of these data, collectively, unveils a signaling pathway responsible for synthesis of VEGF by pulp cells and suggests a novel therapeutic target for the management of vascular responses in teeth with pulpitis.

Marita R. Inglehart, Dr. phil. habil.Abstract: The objectives of this study were to explore 1) how students across the four years of a dental curriculum differed in attitudes towards underserved patients and community service at the beginning and end of each school year; 2) how these attitudes changed as a function of participating in required vs. voluntary community-based activities; and 3) what attitudes faculty members held about the effects of community service-learning on students. Surveys were distributed to 440 students at one dental school at the beginning and end of the school year. The overall response rate for those surveys was 75 percent, with variations among classes: irst year, 94 percent; second year, 92 percent; third year, 69 percent; and fourth year, 43 percent. Survey data were also collected from twenty-two students (out of a possible forty-seven) who participated in voluntary service-learning and from ifty-four faculty members (out of approximately 150). The results showed that, at the beginning of the year, the irst-year students' attitudes were more positive than the responses of students in all other cohorts. However, at the end of the year, their attitudes were less positive. Participating in voluntary service-learning improved students' attitudes towards treating underserved patients only in the short run, and experiencing ten weeks of community-based dental education did not improve their attitudes. The faculty respondents' attitudes, however, were quite positive. The decrease in students' positive attitudes towards treating underserved patients and participating in community service should raise questions about why this loss of idealism occurred.Ms.

Supplementary Methods, Figures 1-7 from Endothelial Cell-Initiated Signaling Promotes the Survival and Self-Renewal of Cancer Stem Cells

Supplementary Methods, Figures 1-7 from Endothelial Cell-Initiated Signaling Promotes the Survival and Self-Renewal of Cancer Stem Cells

<div>Abstract<p>Recent studies have demonstrated that cancer stem cells play an important role in the pathobiology of head and neck squamous cell carcinomas (HNSCC). However, little is known about functional interactions between head and neck cancer stem-like cells (CSC) and surrounding stromal cells. Here, we used aldehyde dehydrogenase activity and CD44 expression to sort putative stem cells from primary human HNSCC. Implantation of 1,000 CSC (ALDH+CD44+Lin−) led to tumors in 13 (out of 15) mice, whereas 10,000 noncancer stem cells (ALDH−CD44−Lin−) resulted in 2 tumors in 15 mice. These data demonstrated that ALDH and CD44 select a subpopulation of cells that are highly tumorigenic. The ability to self-renew was confirmed by the observation that ALDH+CD44+Lin− cells sorted from human HNSCC formed more spheroids (orospheres) in 3-D agarose matrices or ultra-low attachment plates than controls and were serially passaged <i>in vivo</i>. We observed that approximately 80% of the CSC were located in close proximity (within 100-μm radius) of blood vessels in human tumors, suggesting the existence of perivascular niches in HNSCC. <i>In vitro</i> studies demonstrated that endothelial cell-secreted factors promoted self-renewal of CSC, as demonstrated by the upregulation of Bmi-1 expression and the increase in the number of orospheres as compared with controls. Notably, selective ablation of tumor-associated endothelial cells stably transduced with a caspase-based artificial death switch (iCaspase-9) caused a marked reduction in the fraction of CSC in xenograft tumors. Collectively, these findings indicate that endothelial cell-initiated signaling can enhance the survival and self-renewal of head and neck CSC. <i>Cancer Res; 70(23); 9969–78. ©2010 AACR</i>.</p></div>