Neck Cancer Stem Cells Research Articles

Photobiomodulation therapy: Ushering in a new era in personalized supportive cancer care

Abstract The human body can utilize light for a broad range of pathophysiological responses, such as circadian rhythm, Vitamin D metabolism, and vision, among others. The therapeutic use of light has spanned many ancient health practices. Recent advances in using low-dose light therapy, termed photobiomodulation (PBM), have made tremendous progress in unravelling precise biological mechanisms and clinical dosimetry, enabling this treatment modality’s clinical safety and effectiveness. The evidence for PBM has received its strongest endorsement via recent systematic reviews and meta-analyses recommending its routine use to address various acute and chronic side effects associated with cancer treatment. Carefully done studies have noted unequivocal evidence demonstrating its effectiveness in managing oral mucositis in patients undergoing radiotherapy for head and neck cancer, chemotherapy, or hematopoietic stem cell transplantation. This brief narrative review will explore the therapeutic benefits of PBM therapy, supported by recent research findings, to provide a comprehensive understanding of its potential in clinical settings. Additionally, the review will highlight our current understanding of molecular mechanisms underlying PBM and the importance of novel harmonized dosing that enables its optimal clinical implementation and utilization.

Exploring the Roles of Mitochondrial-Associated MicroRNAs of Head and Neck Cancer Stem Cells in Drug Resistance and Tumor Recurrence

Exploring the Roles of Mitochondrial-Associated MicroRNAs of Head and Neck Cancer Stem Cells in Drug Resistance and Tumor Recurrence

Recent Advances in the Targeting of Head and Neck Cancer Stem Cells

Head and neck squamous cell carcinoma (HNSCC) is a very heterogeneous cancer with a poor overall response to therapy. One of the reasons for this therapy resistance could be cancer stem cells (CSCs), a small population of cancer cells with self-renewal and tumor-initiating abilities. Tumor cell heterogeneity represents hurdles for therapeutic elimination of CSCs. Different signaling pathway activations, such as Wnt, Notch, and Sonic-Hedgehog (SHh) pathways, lead to the expression of several cancer stem factors that enable the maintenance of CSC features. Identification and isolation of CSCs are based either on markers (CD133, CD44, and aldehyde dehydrogenase (ALDH)), side populations, or their sphere-forming ability. A key challenge in cancer therapy targeting CSCs is overcoming chemotherapy and radiotherapy resistance. However, in novel therapies, various approaches are being employed to address this hurdle such as targeting cell surface markers, other stem cell markers, and different signaling or metabolic pathways, but also, introducing checkpoint inhibitors and natural compounds into the therapy can be beneficial.

Head and neck cancer stem cell maintenance relies on mTOR signaling, specifically involving the mechanistic target of rapamycin complexes 1 and 2 (mTORC1 and mTORC2)

ObjectiveEmerging evidence suggests that the modest response of head and neck squamous cell carcinoma (HNSCC) to treatment is associated with cancer stem cells (CSC). However, the signaling pathways that play a role in HNSCC CSC maintenance and therapy response are not well-understood. In this study, we investigate the response of CSCs to phosphatase and tensin homolog (PTEN) modulation and its potential dependency on the mammalian target of rapamycin (mTOR) signaling. DesignPTEN deficiency was stably induced using short hairpin RNA (shRNA). Downregulation of RPTOR/mTORC1 and RICTOR/mTORC2 was achieved using small interfering RNA (siRNA). CSCs were evaluated through tumorsphere formation and were classified into various subtypes: parasphere, merosphere, and holosphere. We investigated the effect of rapamycin on CSC properties in both control and PTEN-deficient HNSCC cells. ResultsPTEN deficiency led to an accumulation of CSCs and enhanced a favorable response to rapamycin treatment. The viability of HNSCC CSCs was dependent on mTOR signaling. Deficiencies in both mTORC1 and mTORC2 reduced the number of CSCs. However, CSCs with PTEN deficiency had a greater reliance on mTORC1 signaling. Interestingly, when considering CSC subtypes, a deficiency in mTORC2 led to an increased number of paraspheres in both the control and PTEN-deficient groups. ConclusionsLoss of PTEN signaling increased the HNSCC CSC population, which can be targeted by rapamycin. However, the mTORC2 deficiency can induce a problematic selection of paraspheres CSCs subtype.

KEAP1/NRF2 Mutations in Stem Cells Define an Aggressive Subset of Head and Neck Cancer Patients Who Have a Poor Prognosis, Lung Metastasis, and Therapeutic Failure.

Mutations in Keap1/Nrf2 in head and neck cancer result in abnormal cell growth. Progenitor cells, bulk tumor cells, and head and neck cancer stem cells (HN-CSCs) may all harbor these mutations. Nevertheless, whether Keap1/Nrf2 mutations in HN-CSCs have an impact on clinical outcomes is unknown. Cancerous HN-CSCs and benign stem cells were obtained from freshly resected head and neck cancer patients (n = 50) via flow cytometry cell sorting and tested for Keap1/Nrf2 mutations. The existence of Keap1/Nrf2 mutations in HN-CSCs, as well as their correlations with tumor mutations, pathologic tumor stage, tumor histologic grades, lung metastasis, treatment outcomes, and the patient's age and conditions, are assessed at the last follow-up visit. Thirteen tumors were found to have Keap1/Nrf2 mutations in their HN-CSCs. More than half of the lung metastases and disease progression occurred in HN-CSCs with mutations. Patients whose tumors carried Keap1/Nrf2 mutations in their HN-CSCs had significantly shorter progression-free survival, overall survival, and time of treatment failure than their non-HN-CSC counterparts. These associations were partly driven by HN-CSCs, in which Keap1/Nrf2 mutations were overrepresented in fast progressors and associated with an increased risk of disease progression. Our findings suggest that molecular genotyping of HN-CSCs may facilitate personalized treatment strategies and assist in identifying patients who are likely to benefit from chemotherapy.

Mechanisms of immune evasion by head and neck cancer stem cells.

Different mechanisms are involved in immune escape surveillance driven by Oral and Head and Neck Cancer Stem Cells (HNCSCs). The purpose of this review is to show the most current knowledge regarding the main impact of HNCSCs on tumor evasion through immunosuppression, CSCs phenotypes and environmental signals, highlighting strategies to overcome immune evasion. The main results drive the participation of cell surface receptors and secreted products and ligands, the crosstalk between cells, and genetic regulation. The reduction in CD8+ T cell recruitment and decreased effector of anti-PD-1 therapy by cells expressing BMI1 is a key event; Natural Killer cell ligands and cytokines needed for its activation and expansion are crucial to control tumor growth and to target CSCs by immunotherapy; CSCs expressing ALDH1 are related to increased expression of PD-L1, with a positive link between DNMT3b expression; CD276 expression in CSCs can act as a checkpoint inhibitor and together with Activator Protein 1 (AP-1) activation, they create continuous positive feedback that enables immune evasion by suppressing CD8+ T cells and prevent immune cell infiltration in head and neck cancer. These data demonstrate the relevance of the better understanding of the interaction between HNCSCs and immune cells in the tumor microenvironment. The ultimate clinical implication is to ground the choice of optimized targets and improve immune recognition for ongoing treatments as well as the response to approved immunotherapies.

Advancement in Cancer Stem Cell Biology and Precision Medicine-Review Article Head and Neck Cancer Stem Cell Plasticity and the Tumor Microenvironment.

Head and Neck cancer survival has continued to remain around 50% despite treatment advances. It is thought that cancer stem cells play a key role in promoting tumor heterogeneity, treatment resistance, metastasis, and recurrence in solid malignancies including head and neck cancer. Initial studies identified cancer stem cell markers including CD44 and ALDH in head and neck malignancies and found that these cells show aggressive features in both in vitro and in vivo studies. Recent evidence has now revealed a key role of the tumor microenvironment in maintaining a cancer stem cell niche and promoting cancer stem cell plasticity. There is an increasing focus on identifying and targeting the crosstalk between cancer stem cells and surrounding cells within the tumor microenvironment (TME) as new therapeutic potential, however understanding how CSC maintain a stem-like state is critical to understanding how to therapeutically alter their function. Here we review the current evidence for cancer stem cell plasticity and discuss how interactions with the TME promote the cancer stem cell niche, increase tumor heterogeneity, and play a role in treatment resistance.

Heterogeneity of Cancer Stem Cells in Tumorigenesis, Metastasis, and Resistance to Antineoplastic Treatment of Head and Neck Tumours.

The discovery of a small subset of cancer cells with self-renewal properties that can give rise to phenotypically diverse tumour populations has shifted our understanding of cancer biology. Targeting cancer stem cells (CSCs) is becoming a promising therapeutic strategy in various malignancies, including head and neck squamous cell carcinoma (HNSCC). Diverse sub-populations of head and neck cancer stem cells (HNCSCs) have been identified previously using CSC specific markers, the most common being CD44, Aldehyde Dehydrogenase 1 (ALDH1), and CD133, or by side population assays. Interestingly, distinct HNCSC subsets play different roles in the generation and progression of tumours. This article aims to review the evidence for a role of specific CSCs in HNSCC tumorigenesis, invasion, and metastasis, together with resistance to treatment.

The IL-6R and Bmi-1 axis controls self-renewal and chemoresistance of head and neck cancer stem cells

Despite major progress in elucidating the pathobiology of head and neck squamous cell carcinoma (HNSCC), the high frequency of disease relapse correlates with unacceptably deficient patient survival. We previously showed that cancer stem-like cells (CSCs) drive tumorigenesis and progression of HNSCC. Although CSCs constitute only 2–5% of total tumor cells, CSCs contribute to tumor progression by virtue of their high tumorigenic potential and their resistance to chemo-, radio-, and immunotherapy. Not only are CSCs resistant to therapy, but cytotoxic agents actually enhance cancer stemness by activating transcription of pluripotency factors and by inducing expression of Bmi-1, a master regulator of stem cell self-renewal. We hypothesized therapeutic inhibition of interleukin-6 receptor (IL-6R) suppresses Bmi-1 to overcome intrinsic chemoresistance of CSCs. We observed that high Bmi-1 expression correlates with decreased (p = 0.04) recurrence-free survival time in HNSCC patients (n = 216). Blockade of IL-6R by lentiviral knockdown or pharmacologic inhibition with a humanized monoclonal antibody (Tocilizumab) is sufficient to inhibit Bmi-1 expression, secondary sphere formation, and to decrease the CSC fraction even in Cisplatin-resistant HNSCC cells. IL-6R inhibition with Tocilizumab abrogates Cisplatin-mediated increase in CSC fraction and induction of Bmi-1 in patient-derived xenograft (PDX) models of HNSCC. Notably, Tocilizumab inhibits Bmi-1 and suppresses growth of xenograft tumors generated with Cisplatin-resistant HNSCC cells. Altogether, these studies demonstrate that therapeutic blockade of IL-6R suppresses Bmi-1 function and inhibits cancer stemness. These results suggest therapeutic inhibition of IL-6R might be a viable strategy to overcome the CSC-mediated chemoresistance typically observed in HNSCC patients.

Oral Cancer Stem Cells: Therapeutic Implications and Challenges.

Head and neck squamous cell carcinoma (HNSCC) is currently one of the 10 most common malignancies worldwide, characterized by a biologically highly diverse group of tumors with non-specific biomarkers and poor prognosis. The incidence rate of HNSCC varies widely throughout the world, with an evident prevalence in developing countries such as those in Southeast Asia and Southern Africa. Tumor relapse and metastasis following traditional treatment remain major clinical problems in oral cancer management. Current evidence suggests that therapeutic resistance and metastasis of cancer are mainly driven by a unique subpopulation of tumor cells, termed cancer stem cells (CSCs), or cancer-initiating cells (CICs), which are characterized by their capacity for self-renewal, maintenance of stemness and increased tumorigenicity. Thus, more understanding of the molecular mechanisms of CSCs and their behavior may help in developing effective therapeutic interventions that inhibit tumor growth and progression. This review provides an overview of the main signaling cascades in CSCs that drive tumor repropagation and metastasis in oral cancer, with a focus on squamous cell carcinoma. Other oral non-SCC tumors, including melanoma and malignant salivary gland tumors, will also be considered. In addition, this review discusses some of the CSC-targeted therapeutic strategies that have been employed to combat disease progression, and the challenges of targeting CSCs, with the aim of improving the clinical outcomes for patients with oral malignancies. Targeting of CSCs in head and neck cancer (HNC) represents a promising approach to improve disease outcome. Some CSC-targeted therapies have already been proven to be successful in pre-clinical studies and they are now being tested in clinical trials, mainly in combination with conventional treatment regimens. However, some studies revealed that CSCs may not be the only players that control disease relapse and progression of HNC. Further, clinical research studying a combination of therapies targeted against head and neck CSCs may provide significant advances.

Abstract 2583: Effects of garlic compound diallyl trisulfide on head and neck cancer cells and cancer stem cells in vitro and in vivo

Abstract Head and neck cancer (HNC) is the seventh most prevalent cancer worldwide. The five-year survival rate is less than fifty percent despite significant advances in therapeutic approaches. Early diagnosis and treatment can help in prevention and disease management. Studies have reported that dietary intake of Allium vegetables or processed garlic that contains diallyl trisulfide (DATS) lowered the risk of various cancers. However, it has not been investigated for its efficacy and molecular mechanisms against HNC. Herein, we investigated the effect of DATS on HNC UMSCC-22A, UMSCC-22B, and Cal33 cells in vitro. DATS treatment significantly reduced the cell viability of HNC cells. DATS induced significant G2/M phase cell cycle arrest, which resulted in the accumulation of cyclin B1 and induced levels of p21. DATS-induced M phase arrest was attenuated by N-acetyl cysteine (NAC) treatment, which suggested that DATS mediates growth-suppressive effects by reactive oxygen species (ROS) generation. DATS treatment induced mitochondrial dysfunction. DATS induced ROS production led to apoptosis, which was attenuated by NAC treatment. DATS increased proapoptotic protein cleaved caspase-3, cleaved PARP, and Bax/Bcl2 ratio and decreased the levels of antiapoptotic protein XIAP. DATS induced ROS mediated DNA damage which was attenuated by NAC treatment. Further, DATS mediated increase in level of cleaved PARP, accumulation of Cyclin B1 and decrease in XIAP was attenuated by NAC treatment. DATS (1-10 μM) treatment resulted in inhibition of self renewal of HNC cancer stem cells (HNC CSCs) sphere formation. DATS reduced aldehyde dehydrogenase 1 (ALDH1) activity and CD133high/CD44high HNC CSC fraction. DATS-treated SCID mice tumor xenograft also revealed it's in vivo efficacy on HNC CSCs. Further, DATS treatment reduced the tumor weight, volume and reduced the levels of Ki67 cell proliferation marker in UMSCC22B head and neck cancer CD1 nude mice tumor xenograft. DATS treatment decreased tumor incidence and inhibited tumor promotion and progression in twenty two week C57BL6 4-Nitroquinoline 1-oxide (4-NQO)-induced mouse oral carcinogenesis model. DATS treatment reduced the cell proliferation marker Ki67 and increased TUNEL positive apoptotic cells in treatment groups compared to control group. Collectively, DATS inhibited cell proliferation, induced cell cycle arrest, and cell death via apoptosis involving DNA damage, mitochondrial dysfunction, and ROS generation. DATS treatment also reduced the HNC CSC fraction, sphere formation and ALDH1 activity. More importantly, DATS inhibited cancer incidence and progression in 4-NQO oral carcinogenesis study. Further, DATS inhibited HNC tumor growth and HNC CSC fraction in vivo. Thus, DATS could be a potential chemopreventive and chemotherapeutic agent against head and neck cancer. Citation Format: Sivapar V. Mathan, Su-Hyeong Kim, Shivendra V. Singh, Rana P. Singh. Effects of garlic compound diallyl trisulfide on head and neck cancer cells and cancer stem cells in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2583.

Propolis reduces the stemness of head and neck squamous cell carcinoma

ObjectiveTo evaluate the effect of Brazilian propolis on head and neck cancer stem cells in vitro. MethodsHead and neck squamous cell carcinoma (HNSCC) cell lines (UM-SCC-17B and UM-SCC-74A), human keratinocytes (HK), and primary human dermal microvascular endothelial cells (HDMEC) were treated with 0.5, 5.0, or 50 μg/mL green, brown or red Brazilian propolis or vehicle control for 24, 36, and 72 h. Cell viability was evaluated by Sulforhodamine B assay. Western blots evaluated expression of cancer stem cell (CSC) markers (i.e. ALDH, CD44, Oct-4, Bmi-1) and flow cytometry was performed to determine the impact of propolis in the fraction of CSC, defined as ALDHhighCD44high cells. Resultspropolis significantly reduced cell viability of HNSCC and HDMEC cells, but not HK. Notably, red propolis caused a significant reduction in the percentage of CSC, reduced the number of orospheres, and downregulated the expression of stem cell markers. ConclusionsCollectively, our data demonstrate an anti-CSC effect of propolis, and suggest that propolis (i.e. red propolis) might be beneficial for patients with head and neck cancer.

Abstract PO-006: Single cell transcriptomic analysis of primary head and neck cancer stem cells

Abstract Despite advances in treatment modalities for head and neck squamous cell carcinoma (HNSCC) survival rates remain unchanged. Tumor heterogeneity within HNSCC as well as within the tumor microenvironment (TME) has been shown to be a major driver of treatment failure and poor outcomes. A key component of the TME and a potential key to deciphering tumor heterogeneity are cancer stem cells. While numerous studies have demonstrated the tumorigenicity and malignant potential of these cells, few studies have investigated their expression profiles. The aim of this study is to leverage single cell technology to investigate the expression profile of primary HNSCC cancer stem cells. We performed single cell sequencing of five primary HPV-negative head and neck cancers and two HNSCC cell lines that were presorted into the CSC (CD44high/ALDH+) and non-CSC (CD44low/ALDH-) phenotype. We are able to characterize an expression profile of the CSC TME niche and a novel CSC expression profile (DCN, C110rf96, KLF4, MEG3 and NR4A1) relative to non-CSC. We confirm this CSC profile is conserved across all five primary tumors. Together these data provide some of the first insights into CSC transcriptome, further define the CSC-TME niche, and identify conserved targets within HNSCC CSC as a means to decipher the challenges inherent to tumor heterogeneity. Citation Format: Molly E. Heft Neal, Stephanie The, John Henry J. Owen, Clifford Chang, Mark E.P. Prince, Arvind Rao, Steven B. Chinn. Single cell transcriptomic analysis of primary head and neck cancer stem cells [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-006.

Cancer Cell CD44 Mediates Macrophage/Monocyte-Driven Regulation of Head and Neck Cancer Stem Cells.

Tumor-associated macrophages (TAM) in the tumor microenvironment (TME) cooperate with cancer stem cells (CSC) to maintain stemness. We recently identified cluster of differentiation 44 (CD44) as a surface marker defining head and neck squamous cell carcinoma (HNSCC) CSC. PI3K-4EBP1-SOX2 activation and signaling regulate CSC properties, yet the upstream molecular control of this pathway and the mechanisms underlying cross-talk between TAM and CSC in HNSCC remain largely unknown. Because CD44 is a molecular mediator in the TME, we propose here that TAM-influenced CD44 signaling could mediate stemness via the PI3K-4EBP1-SOX2 pathway, possibly by modulating availability of hyaluronic acid (HA), the main CD44 ligand. HNSCC IHC was used to identify TAM/CSC relationships, and in vitro coculture spheroid models and in vivo mouse models were used to identify the influence of TAMs on CSC function via CD44. Patient HNSCC-derived TAMs were positively and negatively associated with CSC marker expression at noninvasive and invasive edge regions, respectively. TAMs increased availability of HA and increased cancer cell invasion. HA binding to CD44 increased PI3K-4EBP1-SOX2 signaling and the CSC fraction, whereas CD44-VCAM-1 binding promoted invasive signaling by ezrin/PI3K. In vivo, targeting CD44 decreased PI3K-4EBP1-SOX2 signaling, tumor growth, and CSC. TAM depletion in syngeneic and humanized mouse models also diminished growth and CSC numbers. Finally, a CD44 isoform switch regulated epithelial-to-mesenchymal plasticity as standard form of CD44 and CD44v8-10 determined invasive and tumorigenic phenotypes, respectively. We have established a mechanistic link between TAMs and CSCs in HNSCC that is mediated by CD44 intracellular signaling in response to extracellular signals. SIGNIFICANCE: These findings establish a mechanistic link between tumor cell CD44, TAM, and CSC properties at the tumor-stroma interface that can serve as a vital area of focus for target and drug discovery.

Abstract B32: Impact of cancer-associated fibroblasts on head and neck cancer stem cells

Abstract Background: The tumor microenvironment (TME) is made up of epithelial cancer cells and mesenchymal stromal cells including tumor-infiltrating lymphocytes, cancer-associated fibroblasts (CAFs) and endothelial cells. Within the cancer cell population are cancer stem cells (CSC), a subpopulation of cells defined as having the capacity for self-renewal, tumorigenesis, and the ability to recapitulate a heterogeneous tumor. The interaction of the TME with cancer cells remains of interest. The focus of this study is to investigate the effect of patient-derived CAFs on head and neck CSC and tumor activity. Methods: Patient-derived head and neck cancer cell lines and patient-derived fibroblasts lines have previously been established by our group. Tumor cells were grown alone or in combination with patient-matched fibroblasts in a coculture chamber system, allowing for mixture of media but not cells. Scratch tests were performed and closure rates were compared between the two conditions (tumor cells alone and coculture). Tumor cells were then grown alone or in direct contact with matched fibroblasts for one week. Cancer cells were selected for based on epithelial cell adhesion molecule (EpCAM) status and in vitro tumor growth and stem cells percentages (defined as proportion of CD44-high and ALDH-positive cells) were calculated. Results: Patient-derived cancer cells cocultured with matched fibroblasts showed a significant increase in closure rates compared with tumor cells alone at three defined time points (p=0.03-0.002). Coculture conditions resulted in greater in vitro tumor growth after one week (6.4-fold vs. 3.7-fold increase) and an increased proportion of CD44-high tumor cells (9% vs. 5%). The effect of coculture on ALDH-positive percentages was variable. Conclusion: CAFs have previously been shown to potentiate tumorigenesis and metastases. We validated these findings with matched patient derived tumor cells and CAFs. We were then able to demonstrate that CAFs increase the proportion of head and neck CSC, suggesting the mechanism for CAF-associated increased tumor activity may be mediated through CSC. Further studies investigating the relationship between CAFs and CSC are warranted. Citation Format: Molly E. Heft Neal, John Henry J. Owen, Matthew E. Spector, Thomas E. Carey, Mark E.P. Prince, Steven B. Chinn. Impact of cancer-associated fibroblasts on head and neck cancer stem cells [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr B32.

HEAD AND NECK CANCER STEM CELL PROTEOMICS

It is critical to identify the cell of origin of cancer and the genes/proteins/transcriptional/epigenetic factors of that cell. Here, we review studies on head and neck cancer stem cells (CSC) in the hope of developing better understanding of their role highlighting their importance as novel drug targets. CSC model has introduced a hierarchical conceptual framework for the interpretation of intratumour heterogeneity within tumour. This, in turn, has culminated in a major paradigm shift in terms of how different types of cancers can be targeted for treatment. Several malignancies conform to the CSC model of tumour growth yet identification of CSC markers remains a profound challenge.Key words: Chemo- and radio-resistance, head and neck cancer stem cells, proteomics, treatment modalities

The effect of ICRT-3 on Wnt signaling pathway in head and neck cancer.

The effect of Wnt pathway in head and neck cancer could not be elucidated, even though the aberrant Wnt signaling plays a key role in the development of many types of cancer. The inhibitor of β-catenin responsive transcription (ICRT-3) blocks the Wnt signaling pathway by binding toβ-catenin, which is a coactivator of the Wnt signaling pathway anda promising agent for inhibiting aberrant signaling. In our study, we aimed to evaluate the effect of ICRT-3 on the cytotoxicity, apoptosis, cell cycle progression, migration, and gene expressions in head and neck cancer stem cell (HNCSC) and hypopharynx cancer. The effect of this compound on cytotoxicity and cell viability in FaDu and HNCSC line was assessed by using the water-soluble tetrazolium salt-1 method. The effect of ICRT-3 on apoptosis was detected by using Annexin V and caspase-3, caspase-9 kit, on cell cycle progression by cycle test plus DNA reagent kit, on gene expression by dual luciferase reporter assay, and on migration activity by wound healing assay in bothcell lines. ICRT-3 was determined to have cytotoxic and apoptotic effect in bothcell lines. In addition, it was also found that the administration of ICRT-3 caused cell cycle arrest and significant decrease in gene expression level and migration ability of the cells.

Abstract 925: In silico models accurately predict in vivo response for IL-6 blockade in head and neck cancer

Abstract The purpose of this study is to create and validate a mathematical model describing the effect of interleukin-6 (IL-6) on head and neck cancer growth and cancer stem cell fraction. Head and Neck Squamous Cell Carcinoma (HNSCC) is the seventh most-common solid tumor with about 55,000 new cases diagnosed every year. Malignant features of HNSCC cells are derived from a shift towards more stem-like features, as postulated by the cancer stem cell (CSC) hypothesis. CSCs encompass a unique cellular subpopulation characterized by multipotency, uniquely high tumorigenic potential, and self-renewal. These cells function as putative drivers of tumor initiation, therapeutic evasion, metastasis, and recurrence. Though they are an appealing conceptual target, CSC directed cancer therapies remain scarce. High levels of both serum IL-6 and tumor IL-6 receptor (IL-6R) expression are strongly correlated with poor patient survival. Endothelial cell-secreted IL-6 enhances the tumorigenic potential and self-renewal of head and neck CSCs. Furthermore, interruption of the IL-6 pathway results in a decreased fraction of HNSCC CSCs. Efficacy and optimal administration of the FDA approved rheumatoid arthritis IL-6R antibody Tocilizumab in HNSCC is not known. Here we used a multi-scale mathematical model that operates at the intracellular, molecular, and tissue level to investigate the impacts of endothelial cell-secreted IL-6 signaling on the crosstalk between tumor cells and ECs during tumor growth. This endothelial cell - tumor cell (EC-TC) model was used to study the effect of tocilizumab treatment on HNSCC, and particularly the CSC fraction. Our ordinary differential equation model is the first of its kind to include full occupancy dynamics between endothelial-cell produced IL-6, IL-6R, and the competitive IL-6R inhibitor Tocilizumab. In order to biologically validate the utility of our mathematical model, we performed a series of in-vivo experiments using HNSCC cell lines and human endothelial cells co-embedded in a porous scaffold and implanted in SCID mice flank. Tumor volumes were measured serially. CSC fraction was determined in HNSCC cell lines using flow cytometry for aldehyde dehydrogenase (ALDH) high/CD44 high proportion. Without artificial tuning to the laboratory data, our model provided superb predictive agreement to the decrease in tumor volumes observed in TCZ treated mice (r = 0.947, p < 0.0001), as well as a decrease in CSC fraction. This predictive in-silico framework can serve to rapidly evaluate dosing strategies for IL-6 pathway modulation, as well as providing the basis for proposing combination treatments with IL-6 blockade and cytotoxic or other targeted therapies. Citation Format: Fereshteh Nazari, Alexandra E. Oklejas, Jacques E. Nör, Alexander T. Pearson, Trachette L. Jackson. In silico models accurately predict in vivo response for IL-6 blockade in head and neck cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 925.

FGFR signaling regulates resistance of head and neck cancer stem cells to cisplatin.

Patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) have poor prognosis with less than 1-year median survival. Platinum-based chemotherapy remains the first-line treatment for HNSCC. The cancer stem cell (CSC) hypothesis postulates that tumors are maintained by a self-renewing CSC population that is also capable of differentiating into non-self renewing cell populations that constitute the bulk of the tumor. A small population of CSC exists within HNSCC that are relatively resistant to chemotherapy and clinically predicted to contribute to tumor recurrence. These head and neck CSCs (HNCSC) are identified by high cell-surface expression of CD44 and high intracellular activity of aldehyde dehydrogenase (ALDH) and termed ALDHhighCD44high. Here, we performed microarray analysis in two HNSCC cell lines (UM-SCC-1, UM-SCC-22B) to investigate molecular pathways active in untreated and cisplatin-resistant ALDHhighCD44high cells. Gene set enrichment analysis and iPathway analysis identified signaling pathways with major implications to the pathobiology of cancer (e.g. TNFα, IFN, IL6/STAT, NF-κB) that are enriched in cisplatin-resistant ALDHhighCD44high cells, when compared to control cells. FGF2 was also enriched in cisplatin-resistant ALDHhighCD44high, which was confirmed by ELISA analysis. Inhibition of FGF signaling using BGJ398, a pan-FGF receptor (FGFR) small-molecule inhibitor, decreased ALDHhighCD44high alone in UM-SCC-1 and preferentially targeted cisplatin-resistant ALDHhighCD44high cells in UM-SCC-22B. These findings suggest that FGFR signaling might play an important role in the resistance of head and neck CSC to cisplatin. Collectively, this work suggests that some head and neck cancer patients might benefit from the combination of cisplatin and a FGFR inhibitor.

EP-2289: ABT-199 and cetuximab in combination with photon radiation in head and neck cancer stem cells

EP-2289: ABT-199 and cetuximab in combination with photon radiation in head and neck cancer stem cells