Head And Neck Cancer Initiating Cells Research Articles

Combinatorial Low Dose Arsenic Trioxide and Cisplatin Exacerbates Autophagy via AMPK/STAT3 Signaling on Targeting Head and Neck Cancer Initiating Cells.

Head and neck squamous cell carcinoma (HNSCC) is a highly lethal disease with high-level of epidemic both in the world and Taiwan. Previous studies support that head and neck cancer-initiating cells (HN-CICs), a subpopulation of cancer cells with enhanced stemness properties, contribute to therapy resistance and tumor recurrence. Arsenic trioxide (As2O3; ATO) has shown to be an effective anti-cancer drug targeting acute promyelocytic leukemia (APL). Combinatorial treatment with high dose of ATO and cisplatin (CDDP) exert synergistic apoptotic effects in cancer cell lines of various solid tumors, however, it may cause of significant side effect to the patients. Nevertheless, none has reported the anti-cancerous effect of ATO/CDDP targeting HN-CICs. In this study, we aim to evaluate the low dose combination of ATO with conventional chemo-drugs CDDP treatment on targeting HN-CICs. We first analyzed the inhibitory tumorigenicity of co-treatment with ATO and chemo-drugs on HN-CICs which are enriched from HNSCC cells. We observed that ATO/CDDP therapeutic regimen successfully synergized the cell death on HN-CICs with a Combination Index (CI) <1 by Chou-Talalay's analysis in vitro. Interestingly, the ATO/CDDP regimen also induced exaggerated autophagy on HN-CICs. Additionally, this drug combination strategy also empowered both preventive and therapeutic effect by in vivo xenograft assays. Finally, we provide the underlying molecular mechanisms of ATO-based therapeutic regimen on HN-CICs. Together, low dose of combinatorial ATO/CDDP regimen induced cell death as well as exacerbated autophagy via AMPK-STAT3 mediated pathway in HN-CICs.

Attenuation of cancer-initiating cells stemness properties by abrogating S100A4 calcium binding ability in head and neck cancers.

S100A4 is a calcium-binding protein capable of promoting epithelial-mesenchymal transition. Previously, we have demonstrated that S100A4 is required to sustain the head and neck cancer-initiating cells (HN-CICs) subpopulation. In this study, to further investigate the molecular mechanism, we established the head and neck squamous cell carcinoma (HNSCC) cell lines stably expressing mutant S100A4 proteins with defective calcium-binding sites on either N-terminal (NM) or C-terminal (CM), or a deletion of the last 15 amino-acid residues (CD). We showed that the NM, CM and CD harboring sphere cells that were enriched with HN-CICs population exhibited impaired stemness and malignant properties in vitro, as well as reduced tumor growth ability in vivo. Mechanistically, we demonstrated that mutant S100A4 proteins decreased the promoter activity of Nanog, likely through inhibition of p53. Moreover, the biophysical analyses of purified recombinant mutant S100A4 proteins suggest that both NM and CM mutant S100A4 were very similar to the WT S100A4 with subtle difference on the secondary structure, and that the CD mutant protein displayed the unexpected monomeric form in the solution phase.Taken together, our results suggest that both the calcium-binding ability and the C-terminal region of S100A4 are important for HN-CICs to sustain its stemness property and malignancy, and that the mechanism could be mediated by repressing p53 and subsequently activating the Nanog expression.

Abstract 2067: Tid1 mediating cancer initiating properties of head and neck squamous cell carcinoma

Abstract Background: Accumulating studies suggest that the existence of cancer initiating cells (CICs) may explain the results of chemoresistant and radioresistant from cancer treatment and the incidence of metastasis and recurrence. Previously, we demonstrate that Tid1 plays a crucial role as a tumor suppressor during head and neck cancer tumorigenesis. In addition, the protein level of Tid1 is negatively correlated to the overall stage, survival and recurrence of both head and neck cancer and breast cancer patients. Moreover, we also observe that glucose regulatory protein 78 (GRP78), one of the Tid1-interacting protein, mediates the stemness properties of head and neck cancer-initiating cells (HN-CICs) in our recent studies. Nevertheless, the role of Tid1 in CICs properties remains elusive. Methods: We have identified the HN-CICs from head and neck squamous cell carcinoma (HNSCC) and established HNSCC xenograft-derived cell lines by sphere formation assay. To further investigate whether Tid1 mediates the stemness properties of HN-CICs, we will overexpress or knockdown the Tid1 expression to determine the sphere formation ability and the expression of stemness markers, GRP78, Oct-4 and Nanog, of HN-CICs. The oncogenic ability of the HN-CICs mediated by Tid1 expression will also be examined by both in vitro and in vivo assays. Further, we have successfully established mice with epithelial specific ablation of Tid1 by crossing Tid1flx/flx mice with transgenic K5-Cre mice. Consequently, the mutant and control mice have been subject to carcinogen 4-NQO (4-Nitroquinoline 1-oxide) treatment within drinking water for monitoring head and neck cancer progression. Immunohistochemistry staining was applied to examine the expression profile of stemness/differentiation markers within tumors formed in mutant and wild type mice. Results: Up to date, we discovered that mutant mice treated with 4-NQO displayed faster incident of neoplasia in oral cavity and reduction of body weight in comparison to control mice under same administration. In addition, the histopathological analyses showed that the tumors formed in mutant mice were squamous cell carcinoma whereas tumors formed in wild type mice were benign squamous papilloma. Further, we observed that the expression of Tid1 protein was down regulated in the HN-CICs and SAS xenograft-derived cell lines comparing to the HNSCCs by microarray gene expression analysis and immunoblotting assay. Conclusion: Deficient of Tid1 can accelerate the incident of tumorigenesis and tumor progression mediated by 4-NQO treated mice model. We also found that Tid1 expression was negative correlated to the stemness properties. Therefore, Tid1 may play an important role of controlling stemness properties. However, the molecular mechanisms mediated by Tid1 to regulate the progression of HNSCC remain elusive. Further research effort is needed in this area. Citation Format: Li-Hao Cheng, Jeng-Fan Lo. Tid1 mediating cancer initiating properties of head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2067. doi:10.1158/1538-7445.AM2015-2067

Abstract 4217: Targeting head and neck cancer-initiating cells with combinatorial therapeutics through pharmacological inhibition of ROS scavenger and conventional chemotherapy

Abstract Background: Cancer-initiating cells (CICs) contribute to tumor initiation, progression and therapy resistance through critical physiology mechanisms. Redox homeostasis plays an important role in the regulation of cancer stemness. We recently have reported that cancer cells containing differential level of ROS display distinct physiological properties of stemness, proliferative activity, chemoresistance and tumorigenicity. Therefore, to uncover the regulatory physiological mechanisms by which to sustain the low lever of ROS in CICs warrants an important study for future therapy development. Results: In this study, we demonstrated that lower ROS levels in head and neck CICs (HN-CIC) enriched population are associated with increased expression of ROS scavenger such as catalase and SOD2. Pharmacological and genetic inhibition of SOD2 or catalase caused the increased expression of differentiation marker, cytokeratin 18, but the decreased expression of CIC marker in HN-CICs. In addition, the sphere formation abilities of HN-CICs under genetic inhibition of SOD2 or catalase were also significantly abolished. Notably, combinatorial treatment with ROS scavenger inhibitors and conventional anticancer drugs synergistically reduced the stemness properties and tumorigenicity both in vitro and in vivo. Using the Oncomine database, we found associations between SOD2 and catalase expression and increasing head and neck cancer recurrence, tumor invasion and resistance to Gemcitabine treatment. Conclusion: Together, these data demonstrate the importance of antioxidant defense to maintain the low ROS level, cell viability and chemosensitivity of HN-CICs. Pharmacological inhibition of ROS scavenger (SOD2 and catalase) might be a future alternative HNSCC treatment in combination with conventional chemotherapy Citation Format: Ching-Wen Chang, Jeng-Fan Lo. Targeting head and neck cancer-initiating cells with combinatorial therapeutics through pharmacological inhibition of ROS scavenger and conventional chemotherapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4217. doi:10.1158/1538-7445.AM2015-4217

Abstract 1705: Combinatorial therapeutics with targeting head and neck cancer initiating cells using active components from antrodia cinnamomea and conventional chemotherapy

Abstract Background: Cancer initiating cells (CICs), also termed as Cancer stem cells (CSCs), represent a rare subpopulation of cells, which are responsible for tumor growth. CICs such as head and neck cancer initiating cells (HN-CICs), are often resistant to either radio- or chemotherapy. Therefore, development for drug candidates that target HN-CICs specifically will be effective for future oral cancer therapy. Methods: In this study, we used the in vitro cell-based aldehyde dehydrogenase (ALDH) activity assay system, which has been demonstrated as a CICs marker, to screen for the active purified components from Antrodia Camphorata Mycelia extract (ACME), which can target HN-CICs. Next, the antitumorigenicity of combinatorial treatment with active components from ACME and conventional chemotherapy on HNSCC will be examined in vitro and in vivo. Results: Herein, we first screened for the active components from natural products of ACM significantly down regulate the ALDH activity and CD44 positivity of Head and neck squamous cell carcinoma (HNSCC). Consequently, treatment of YMGKI-2 (analogue of ergosterol), a single and active compound purified from ACME, not only inhibited the ALDH activity but also reduced self-renewal property and expression of stemness genes (Oct-4 and Nanog) in enriched HN-CICs. Moreover, the repressive HN-CICs properties by YMGKI-2 treatment were caused by promoting cell differentiation. Additionally, treatment of YMGKI-2 results in down-regulation of Cox-2 and Src molecular mechanisms which both play important role in CICs. Further, the tumorigenic properties of HNSCC cells were attenuated by YMGKI-2 treatment in vivo. Lastly, combinatorial treatments with YMGKI-2 and standard chemotherapeutic drugs reveal synergistic effects on killing both HN-CICs and non-HN-CICs in vitro and in vivo. Conclusion: Together, our results indicate that YMGKI-2 treatment significantly and selectively abolished the stemness properties and tumorigenicity of HN-CICs. These findings provide a new drug candidate from purified components of ACM as an alternative therapy in combination with conventional chemotherapy treatment modalities for head and neck cancer in the future. Citation Format: Ching-Wen Chang, Jeng-Fan Lo. Combinatorial therapeutics with targeting head and neck cancer initiating cells using active components from antrodia cinnamomea and conventional chemotherapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1705. doi:10.1158/1538-7445.AM2014-1705

Abstract 216: Attenuation of cancer-initiating cells stemness properties by abrogating S100A4 calcium binding ability in head and neck cancers

Abstract Background: Epithelial-mesenchymal transition (EMT) is a process that epithelial cells acquire a migratory mesenchymal phenotype or stem cell (SC) properties. Further, up regulation of Vimentin and Nanog is closely related to EMT and stemness properties, respectively. S100A4, a member of calcium-binding proteins, is competent to induce EMT and directly controlled by Wnt/β-catenin signaling pathway. Calcium binding activity of S100A4 has been highly associated with the regulation of downstream targets and development of a metastatic phenotype. In addition, we recently demonstrate that S100A4 plays a crucial role in the maintenance of head and neck cancer-initiating cells (HN-CIC) population. Moreover, inhibition of S100A4 decreased the HN-CICs stemness and self-renewal property, both in vitro and in vivo. However, the regulation of S100A4 and the molecular targets to control HN-CICs stemness capability are remained unclear. Methods: In this study, we establish the stable cells harboring the mutations with calcium-binding sites or a deletion of the last 15 amino-acid residues of S100A4 in head and neck squamous cell carcinomas (HNSCC) to investigate the mechanism of S100A4 enhances stemness properties of CICs through in vitro and in vivo assays. Results: We found that cells expressing the mutant S100A4 result in decreasing of anchorage independent growth ability when it compare to the cells harboring wild-type S100A4 in HNSCC. The immunoblot analyses showed that wild-type S100A4 not only increased the protein level of Vimentin and Nanog but also decreased the expression of E-cadherin. Inversely, the mutant S100A4 reduced the protein level of Vimentin and Naong and increased the expression E-cadherin in HNSCCs. To further investigate the connection between S100A4 and stemness determinants, we enriched the HN-CICs from wild-type S100A4 and mutants S100A4 HNSCC cells, respectively, by sphere formation. The results showed that the mutants S100A4 sphere cells displayed much less stemness markers, the cell surface CD133 and GRP78. Finally, the tumorigenic ability of wild-type S100A4 and mutants S100A4 HNSCC cells, which would be enhanced by acquisition of stemness properties, is further under examination by xenotransplantation. Conclusion: Our study provides a hint that Ca2+ binding ability of S100A4 plays an important role in the maintenance of self-renewal and stemness properties of HN-CICs. The study of how modulators of Ca2+ dependent processes operate the stem-like properties and the tumorigenicity of HN-CICs are needed for further elucidation. Citation Format: Li-Hao Cheng, Jeng-Fan Lo. Attenuation of cancer-initiating cells stemness properties by abrogating S100A4 calcium binding ability in head and neck cancers. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 216. doi:10.1158/1538-7445.AM2014-216

Active Component ofAntrodia cinnamomeaMycelia Targeting Head and Neck Cancer Initiating Cells through Exaggerated Autophagic Cell Death

Head and neck squamous cell carcinoma (HNSCC) is a highly lethal cancer. Previously, we identify head and neck cancer initiating cells (HN-CICs), which are highly tumorigenic and resistant to conventional therapy. Therefore, development of drug candidates that effectively target HN-CICs would benefit future head and neck cancer therapy. In this study, we first successfully screened for an active component, named YMGKI-1, from natural products of Antrodia cinnamomea Mycelia (ACM), which can target the stemness properties of HNSCC. Treatment of YMGKI-1 significantly downregulated the aldehyde dehydrogenase (ALDH) activity, one of the characteristics of CIC in HNSCC cells. Additionally, the tumorigenic properties of HNSCC cells were attenuated by YMGKI-1 treatment in vivo. Further, the stemness properties of HN-CICs, which are responsible for the malignancy of HNSCC, were also diminished by YMGKI-1 treatment. Strikingly, YMGKI-1 also effectively suppressed the cell viability of HN-CICs but not normal stem cells. Finally, YMGKI-1 induces the cell death of HN-CICs by dysregulating the exaggerated autophagic signaling pathways. Together, our results indicate that YMGKI-1 successfully lessens stemness properties and tumorigenicity of HN-CICs. These findings provide a new drug candidate from purified components of ACM as an alternative therapy for head and neck cancer in the future.

Abstract 3338: Characterization of glucose transporter 3 in head and neck cancer initiating cells

Abstract Background: Head and Neck squamous cell carcinoma (HNSCC) is a lethal cancer with clinical, pathological, phenotypical and biological heterogeneity. Cancer initiating cells (CICs) exhibit self-renewal and promote tumor progression capacity. We have also identified the subpopulation of head and neck cancer initiating cells (HN-CICs), and observed the upregulation of Glucose Transporter 3(Glut3) in HN-CICs by differential systemic analyses. However, the role of Glut3 in HN-CICs metabolism alternation remains unclear. Herein we determined the critical role of Glut3, a novel CICs marker, in the maintenance of stemness characteristics and tumorigenic phenotype of HN-CICs. Methods: Stable overexpression and knockdown of Glut3 expression in HNSCCs and HN-CICs was achieved by lentiviral-mediated system. Consequently, we elucidated the stemness properties and tumorigenicity of HNSCCs and HN-CICs with Glut3 down-regulation. Consequently, we investigated the role of Glut3 in metabolism regulation of cancer initiation cells. Results: Lentiviral knockdown of Glut3 significantly reduced the self-renewal ability and cancer initiation cell marker Grp78 expression in HN-CICs. Additionally, down-regulation of Glut3 enhanced the differentiation capability but inversely diminished “stemness” gene expression of HN-CICs. Of note, knockdown of Glut3 lessened tumorigenicity of HN-CICs both in vitro. Conclusion: We showed that Glut3 contributes to the maintenance of stemness and tumorigenicity of HN-CICs. In addition, the expression of Glut3 was involved in HN-CICs metabolism. Overall, silencing Glut3 might be a potential therapeutic target for HNSCC by eliminating CICs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3338. doi:1538-7445.AM2012-3338

CD133/Src Axis Mediates Tumor Initiating Property and Epithelial-Mesenchymal Transition of Head and Neck Cancer

BackgroundHead and Neck squamous cell carcinoma (HNSCC) is a human lethal cancer with clinical, pathological, phenotypical and biological heterogeneity. Caner initiating cells (CICs), which are responsible for tumor growth and coupled with gain of epithelial-mesenchymal transition (EMT), have been identified. Previously, we enriched a subpopulation of head and neck cancer initiating cells (HN-CICs) with up-regulation of CD133 and enhancement of EMT. Others demonstrate that Src kinase interacts with and phosphorylates the cytoplasmic domain of CD133. However, the physiological function of CD133/Src signaling in HNSCCs has not been uncovered.Methodology/Principal FindingHerein, we determined the critical role of CD133/Src axis modulating stemness, EMT and tumorigenicity of HNSCC and HN-CICs. Initially, down-regulation of CD133 significantly reduced the self-renewal ability and expression of stemness genes, and promoted the differentiation and apoptotic capability of HN-CICs. Additionally, knockdown of CD133 in HN-CICs also lessened both in vitro malignant properties including cell migration/cell invasiveness/anchorage independent growth, and in vivo tumor growth by nude mice xenotransplantation assay. In opposite, overexpression of CD133 enhanced the stemness properties and tumorigenic ability of HNSCCs. Lastly, up-regulation of CD133 increased phosphorylation of Src coupled with EMT transformation in HNSCCs, on the contrary, silence of CD133 or treatment of Src inhibitor inversely abrogated above phenotypic effects, which were induced by CD133 up-regulation in HNSCCs or HN-CICs.Conclusion/SignificanceOur results suggested that CD133/Src signaling is a regulatory switch to gain of EMT and of stemness properties in HNSCC. Finally, CD133/Src axis might be a potential therapeutic target for HNSCC by eliminating HN-CICs.

The Epithelial-Mesenchymal Transition Mediator S100A4 Maintains Cancer-Initiating Cells in Head and Neck Cancers

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 stemness-maintaining 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.

Elimination of head and neck cancer initiating cells through targeting glucose regulated protein78 signaling

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.

Abstract 3359: Glucose regulated protein78, a putative head and neck cancer initiating cells marker

Abstract Background: Head 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 cells (HNSCCs) using tumor sphere formation approach. GRP78, a stress-inducible endoplasmic reticulum (ER) chaperone, has been reported to play a role in the maintenance of embryonic stem cells and was up-regulated in enriched HN-CICs. However, the molecular mechanisms mediated by GRP78 to operate the physiological characteristics in HN-CICs remain unclear. Herein, we determined the critical role of GRP78 in the maintenance of stemness characteristics and tumorigenic phenotype in HNSCCs. Methods: First, Affymatrix microarray and two-dimensional differential gel electrophoresis (2-D DIGE) proteomic analyses were applied to identify GRP78 and membrane associated GRP78 (memGRP78) as a putative marker of HN-CICs. Flow cytometry cell sorting was used to isolate memGRP78+ cells and memGRP78− cells for evaluating CICs properties. Down-regulation of GRP78 expression in HNSCCs and HN-CICs were achieved by lentiviral-mediated small hairpin RNA interference (shRNAi), and the stemness characteristics in GRP78-knockdown HN-CICs were elucidated. In addition, in vitro tumorigenic properties between GRP78-knockdown and control HN-CICs were determined. The in vivo tumorigenicity of GRP78-knockdown HN-CICs was evaluated by xenotransplantation assay. Finally, we examined the correlation on expression of GRP78 and stemness genes in HNSCC patient tissues by immunohistochemical staining. Results: We identified that GRP78/memGRP78 was significantly up-regulated in enriched HN-CICs. Subsequently, memGRP78+ HNSCCs displayed CICs properties. Lentiviral mediated knockdown of GRP78 significantly reduced expression of stemness genes in HN-CICs and HNSCCs, but enhanced the differentiation capability of HN-CICs. Overall, down-regulation of GRP78 lessened tumorigenicity of HN-CICs both in vitro and in vivo. Conclusion: Our studies first elucidated the crucial role of GRP78 in the maintenance of stemness and tumorigenicity of HN-CICs. Notably, targeting GRP78 signaling might be a potential therapeutic target for HNSCC by eliminating CICs and memGRP78 could be a novel surface biomarker for isolation HN-CICs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3359.

Abstract 4263: Epithelial-mesenchymal transition mediator, S100A4, in maintenance of head and neck cancer initiating cells

Abstract Background: Cancer initiating cells (CICs) represent a rare subpopulation of cells, which are responsible for tumor growth. Previously, we have identified and characterized the CICs from head and neck squamous cell carcinomas (HNSCCs), termed head and neck cancer initiating cells (HN-CICs). HN-CICs possess both the hallmarks of stem cells and malignant tumor cells. Herein, we determined the critical role of S100A4, a common mediator of epithelial-mesenchymal transition (EMT), in maintenance of stemness properties and cancerous phenotypes in HN-CICs. Methods: Affymetrix microarray analysis was performed to identify S100A4 as a putative candidate on mediating the stemness properties of HN-CICs. Consequently, we elucidated the stemness properties and tumorigenicity of HN-CICs with S100A4 down-regulation or overexpression, respectively. Finally, immunohistochemical staining of S100A4 on HNSCC tumor tissues was examined. Results: S100A4 transcripts and protein level were found significantly up regulated in the enriched HN-CICs. Down-regulation of S100A4 significantly reduced the self-renewal ability and stemness properties in HNSCCs. In addition, knockdown of S100A4 lessened tumorigenicity of HNSCCs both in vitro and in vivo. Conversely, over-expression of S100A4 enhanced the CSC properties in HNSCCs. Furthermore, expression of S100A4 was positively correlated with clinical grading, and survivals and recurrence, respectively (p&amp;lt;0.001, 0.05 and 0.01) according to the immunohistochemical staining. Finally, depletion of endogenous S100A4 resulted in down-regulation of Notch2 and PI3K/pAKT and up-regulation of PTEN in HNSCCs. Conclusion: Our study reveals the crucial role of S100A4 signaling pathways in the maintenance of stemness properties and tumorigenicity of HN-CICs, and S100A4 might be a potential therapeutic target for HNSCC by eliminating HN-CICs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4263.