ERK1/2 regulation of CD44 modulates oral cancer aggressiveness

The biology and role of CD44 in cancer progression: therapeutic implications

CD44, a non-kinase transmembrane glycoprotein, is overexpressed in several cell types including cancer stem cells and frequently shows alternative spliced variants that are thought to play a role in cancer development and progression. Hyaluronan, the main ligand for CD44, binds to and activates CD44 resulting in activation of cell signaling pathways that induces cell proliferation, increases cell survival, modulates cytoskeletal changes, and enhances cellular motility. The different functional roles of CD44 standard (CD44s) and specific CD44 variant (CD44v) isoforms are not fully understood. CD44v contain additional peptide motifs that can interact with and sequester growth factors and cytokines at the cell surface thereby functioning as coreceptors to facilitate cell signaling. Moreover, CD44v were expressed in metastasized tumors, whereas switching between CD44v and CD44s may play a role in regulating epithelial to mesenchymal transition (EMT) and in the adaptive plasticity of cancer cells. Here, we review current data on the structural and functional properties of CD44, the known roles for CD44 in tumorigencity, the regulation of CD44 expression, and the potential for targeting CD44 for cancer therapy.

STINGel: Controlled release of a cyclic dinucleotide for enhanced cancer immunotherapy

Recent advancements in the field of immunotherapy have yielded encouraging results for the treatment of advanced cancers. Cyclic dinucleotides (CDNs) are a powerful new class of immunotherapy drugs known as STING (Stimulator of Interferon Genes) agonists, currently in clinical trials. However, previous studies of CDNs in murine cancer models have required multiple injections, and improve survival only in relatively nonaggressive tumor models. Therefore, we sought to improve the efficacy of CDN immunotherapy by developing a novel biomaterial we call "STINGel." STINGel is an injectable peptide hydrogel that localizes and provides controlled release of CDN delivery, showing an 8-fold slower release rate compared to a standard collagen hydrogel. The carrier hydrogel is a positively charged, MultiDomain Peptide (MDP) which self-assembles to form a nanofibrous matrix and is easily delivered by syringe. The highly localized delivery of CDN from this nanostructured biomaterial affects the local histological response in a subcutaneous model, and dramatically improves overall survival in a challenging murine model of head and neck cancer compared to CDN alone or CDN delivered from a collagen hydrogel. This study demonstrates the feasibility of biomaterial-based immunotherapy platforms like STINGel as strategies for increasing the efficacy of CDN immunotherapies.

Salivary extracellular vesicle-associated miRNAs as potential biomarkers in oral squamous cell carcinoma

BACKGROUND

Several studies in the past have investigated the expression of micro RNAs (miRNAs) in saliva as potential biomarkers. Since miRNAs associated with extracellular vesicles (EVs) are known to be protected from enzymatic degradation, we evaluated whether salivary EVs from patients with oral squamous cell carcinoma (OSCC) were enriched with specific subsets of miRNAs.

METHODS

OSCC patients and controls were matched with regards to age, gender and risk factors. Total RNA was extracted from salivary EVs and the differential expression of miRNAs was evaluated by qRT-PCR array and qRT-PCR. The discrimination power of up-regulated miRNAs as biomarkers in OSCC patients versus controls was evaluated by the Receiver Operating Characteristic (ROC) curves.

RESULTS

A preliminary qRT-PCR array was performed on samples from 5 OSCC patients and 5 healthy controls whereby a subset of miRNAs were identified that were differentially expressed. On the basis of these results, a cohort of additional 16 patients and 6 controls were analyzed to further confirm the miRNAs that were up-regulated or selectively expressed in the previous pilot study. The following miRNAs: miR-302b-3p and miR-517b-3p were expressed only in EVs from OSCC patients and miR-512-3p and miR-412-3p were up-regulated in salivary EVs from OSCC patients compared to controls with the ROC curve showing a good discrimination power for OSCC diagnosis. The Kyoto Encyclopedia of Gene and Genomes (KEGG) pathway analysis suggested the possible involvement of the miRNAs identified in pathways activated in OSCC.

CONCLUSIONS

In this work, we suggest that salivary EVs isolated by a simple charge-based precipitation technique can be exploited as a non-invasive source of miRNAs for OSCC diagnosis. Moreover, we have identified a subset of miRNAs selectively enriched in EVs of OSCC patients that could be potential biomarkers.

Combined overexpression of cadherin 6, cadherin 11 and cluster of differentiation 44 is associated with lymph node metastasis and poor prognosis in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a highly invasive lesion that frequently metastasizes to the cervical lymph nodes and is associated with a poor prognosis. Several adhesion factors, including cadherin 6 (CDH6), cadherin 11 (CDH11) and cluster of differentiation 44 (CD44), have been reported to be involved in the invasion and metastasis of multiple types of cancer. Therefore, the aim of the present study was to determine the expression of CDH6, CDH11 and CD44 in tumor tissues from patients with OSCC, and whether this was associated with the metastasis and survival of OSCC. The mRNA expression of the human tumor metastasis-related cytokines was examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in OSCC tumors with or without lymph node metastasis (n=10/group). The expression of CDH6, CDH11 and CD44 in 101 OSCC and 10 normal oral mucosa samples was examined by immunohistochemical staining. The association between overall and disease-specific survival times of patients with OSCC and the expression of these three proteins was evaluated using Kaplan-Meier curves and the log-rank test. RT-qPCR results indicated that the mRNA expression of CDH6, CDH11 and CD44 was increased in OSCC patients with lymph node metastasis (2.93-, 2.01- and 1.92-fold; P<0.05). Overexpression of CDH6, CDH11 and CD44 was observed in 31/35 (89%), 25/35 (71%) and 31/35 (89%) patients, respectively. The number of OSCC patients with lymph node metastasis exhibiting CDH6, CDH11 and CD44 overexpression was significantly higher than the number of patients without lymph node metastasis exhibiting overexpression of these proteins (P=0.017, P=0.038 and P=0.007, respectively). OSCC patients with high co-expression of CDH6, CDH11 and CD44 exhibited lower disease-specific survival times (P=0.047; χ²=3.933) when compared with OSCC patients with low co-expression of these adhesion factors. CDH6, CDH11 and CD44 serve important roles in OSCC metastasis and the combined use of these factors as biomarkers may improve the accuracy of the prediction of cancer metastases and prognosis.

Role of protein kinase N2 (PKN2) in cigarette smoke-mediated oncogenic transformation of oral cells

Smoking is the leading cause of preventable death worldwide. Though cigarette smoke is an established cause of head and neck cancer (including oral cancer), molecular alterations associated with chronic cigarette smoke exposure are poorly studied. To understand the signaling alterations induced by chronic exposure to cigarette smoke, we developed a cell line model by exposing normal oral keratinocytes to cigarette smoke for a period of 12 months. Chronic exposure to cigarette smoke resulted in increased cellular proliferation and invasive ability of oral keratinocytes. Proteomic and phosphoproteomic analyses showed dysregulation of several proteins involved in cellular movement and cytoskeletal reorganization in smoke exposed cells. We observed overexpression and hyperphosphorylation of protein kinase N2 (PKN2) in smoke exposed cells as well as in a panel of head and neck cancer cell lines established from smokers. Silencing of PKN2 resulted in decreased colony formation, invasion and migration in both smoke exposed cells and head and neck cancer cell lines. Our results indicate that PKN2 plays an important role in oncogenic transformation of oral keratinocytes in response to cigarette smoke. The current study provides evidence that PKN2 can act as a potential therapeutic target in head and neck squamous cell carcinoma, especially in patients with a history of smoking.

ESM1 mediates NGFR-induced invasion and metastasis in murine oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a highly invasive and metastatic malignancy. The nerve growth factor receptor (NGFR) has been observed to be expressed on a subset of cells in OSCC, and NGFR⁺ cells have greater tumor-initiating capacity in vivo. Further, inhibition of NGFR reduces tumor growth, indicating a functional role of this receptor; however, the mechanisms by which NGFR confers enhanced tumor formation are not known. Here, we used an established murine model of OSCC and gene expression array analysis to identify ESM1 as a downstream target gene of NGFR, critical for tumor invasion and metastasis. ESM1 encodes a protein called endocan, which has the property of regulating proliferation, differentiation, migration, and adhesion of different cell types. Incubation of NGFR⁺ murine OSCC cells with nerve growth factor resulted in increased expression of ESM1. Importantly, ESM1 overexpression conferred an enhanced migratory, invasive, and metastatic phenotype, similar to what has been correlated with NGFR expression. Conversely, shRNA knockdown of ESM1 in NGFR overexpressing OSCC cells abrogated the tumor growth kinetics and the invasive and metastatic properties associated with NGFR. Together, our data indicate that NGFR plays an important role in the pathogenesis and progression of OSCC via regulation of ESM1.

Mouse model of postsurgical primary tumor recurrence and regional lymph node metastasis progression in HPV-related head and neck cancer

HPV-positive head and neck squamous cell carcinoma (HNSCC) is increasingly frequent. Management is particularly debated in the case of postsurgical high-risk features, that is, positive surgical margins and extracapsular spread (ECS). In this increasingly complex emerging framework of HNSCC treatment, representative preclinical models are needed to support future clinical trials and advances in personalized medicine. Here, we present an immunocompetent mouse model based on the implantation of mouse tonsil epithelial HPV16-E6/E7-expressing cancer cells into the submental region of the floor-of-the-mouth. Primary tumors were found to replicate the patterns of human HNSCC local invasion and lymphatic dissemination. To study disease progression after surgery, tumors were removed likely leaving behind residual disease. Surgical resection of tumors was followed by a high rate of local recurrences (>90%) within the first 2-3 weeks. While only 50% of mice had lymph node metastases (LNM) at time of primary tumor excision, all mice with recurrent tumors showed evidence of LNM. To study the consecutive steps of LNM progression and distant metastasis development, LNs from tumor-bearing mice were transplanted into naïve recipient mice. Using this approach, transplanted LNs were found to recapitulate all stages and relevant histological features of regional metastasis progression, including ECS and metastatic spread to the lungs. Altogether, we have developed an immunocompetent HPV-positive HNSCC mouse model of postsurgical local recurrence and regional and distant metastasis progression suitable for preclinical studies.

Cancer immunogenomic approach to neoantigen discovery in a checkpoint blockade responsive murine model of oral cavity squamous cell carcinoma

Head and neck squamous cell carcinomas (HNSCC) are an ideal immunotherapy target due to their high mutation burden and frequent infiltration with lymphocytes. Preclinical models to investigate targeted and combination therapies as well as defining biomarkers to guide treatment represent an important need in the field. Immunogenomics approaches have illuminated the role of mutation-derived tumor neoantigens as potential biomarkers of response to checkpoint blockade as well as representing therapeutic vaccines. Here, we aimed to define a platform for checkpoint and other immunotherapy studies using syngeneic HNSCC cell line models (MOC2 and MOC22), and evaluated the association between mutation burden, predicted neoantigen landscape, infiltrating T cell populations and responsiveness of tumors to anti-PD1 therapy. We defined dramatic hematopoietic cell transcriptomic alterations in the MOC22 anti-PD1 responsive model in both tumor and draining lymph nodes. Using a cancer immunogenomics pipeline and validation with ELISPOT and tetramer analysis, we identified the H-2Kb-restricted ICAM1_P315L (mICAM1) as a neoantigen in MOC22. Finally, we demonstrated that mICAM1 vaccination was able to protect against MOC22 tumor development defining mICAM1 as a bona fide neoantigen. Together these data define a pre-clinical HNSCC model system that provides a foundation for future investigations into combination and novel therapeutics.

CD271 Confers an Invasive and Metastatic Phenotype of Head and Neck Squamous Cell Carcinoma through the Upregulation of Slug

Purpose: Head and neck squamous cell carcinoma (HNSCC) is comprised of heterogeneous populations of cells, and CD271 (NGFR; p75NTR) has been associated with a tumor-initiating cell subpopulation. This study assessed the role of CD271 in modulating metastatic behavior in HNSCC.Experimental Design: CD271 was overexpressed in murine and human oral squamous cell carcinoma cells to assess the impact of CD271 activation on the invasive and metastatic phenotype of these cells, using in vitro and orthotopic in vivo modeling. Treatment with human nerve growth factor (NGF) to activate CD271, as well as shRNA knockdown of the CD271-upregulated Snai2 expression, was used to assess the mechanism of the CD271-induced invasive phenotype. Relevance of CD271 expression in human HNSCC was evaluated in patient-derived xenografts (PDX) and primary human oral cancers, annotated with clinical behavior characteristics and survival data.Results: Forced expression of CD271 resulted in a more invasive and metastatic phenotype. Slug, an epithelial-to-mesenchymal transition (EMT)-related transcription factor, encoded by Snai2, was highly expressed in MOC2-CD271 and HSC3-CD271, compared with respective parental cells. CD271 activation by NGF conferred enhanced invasiveness in CD271-overexpressing cells, which was abrogated by Snai2 knockdown. In PDXs and primary human HNSCC, CD271 expression correlated with higher Snai2 expression, greater nodal metastasis, and shorter disease-free survival.Conclusions: Activation of CD271 results in upregulation of Snai2/Slug, which, in turn, results in a more invasive phenotype and an enhanced capacity for metastasis to regional lymph nodes. These findings point to CD271 as a promising, therapeutic target for oral cancer metastasis. Clin Cancer Res; 24(3); 674-83. ©2017 AACR.

PD-1 blockade reverses adaptive immune resistance induced by high-dose hypofractionated but not low-dose daily fractionated radiation

Preclinical evidence suggests that high-dose hypofractionated ionizing radiation (IR) can enhance anti-tumor immunity and result in significant tumor control when combined with immune checkpoint blockade (ICB). However, low-dose daily fractioned IR used for many tumor types including head and neck squamous cell carcinoma results in lymphopenia and may be immunosuppressive. We compared immune correlates, primary tumor and abscopal tumor control rates following the addition of PD-1 mAb to either high-dose hypofractioned (8Gyx2) or low-dose daily fractionated (2Gyx10) IR in syngeneic models of cancer. When compared to 2Gyx10 IR, 8Gyx2 IR preserved peripheral and tumor-infiltrating CD8+ T-lymphocyte accumulation and activation and reduced peripheral and tumor gMDSC accumulation. Regulatory T-lymphocytes were largely unaltered. Type I and I IFN levels and expression of IFN-responsive MHC class I and PD-L1 was enhanced in tumors treated with 8Gyx2 compared to 2Gyx10 IR. Functionally, tumor-specific CD8+ T-lymphocyte IFN responses within tumor draining lymph nodes were enhanced following 8Gyx2 IR but suppressed following 2Gyx10 IR. When combined with PD-1 mAb, reversal of adaptive immune resistance and subsequent enhancement of CD8+ cell dependent primary and abscopal tumor control was observed following 8Gyx2 but not 2Gyx10 IR. These data strongly support that compared to daily fractionated low-dose IR, high-dose hypofractionated IR preserves or enhances anti-tumor immunity and, when combined with PD-1 mAb to reverse adaptive immune resistance, promotes anti-tumor immunity to control primary and distant tumors. These data critically inform the rational design of trials combining IR and ICB.

Trends in Surgical Research in Head and Neck Cancer

OPINION STATEMENT

The task of surgical research is to improve the efficacy of available surgical therapeutic modalities, develop new ones, and balance this well with favorable functional outcome. Therefore, surgical research is composed of a translational and a clinical component. In translational surgical research, animal models are used to better understand the biology of head and neck cancers, but even more importantly, the biology of changes to the disease and the microenvironment created by surgical interventions. Animal models additionally allow for the development of image-guided surgery systems, novel strategies of intraoperative adjuvant treatment, and patient "avatars" to test innovative anticancer drug combinations. In clinical surgical research, surgical techniques are validated in clinical trials for effectiveness of tumor control and improvement of functional recovery of the patient. In conclusion, surgical research for head and neck cancer is an active field spanning across the entire breadth of basic and clinical science devoted to a better understanding of what surgery does to the disease and to the patient.

Combination immunotherapy with TLR agonists and checkpoint inhibitors suppresses head and neck cancer

Checkpoint inhibitors have demonstrated efficacy in patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). However, the majority of patients do not benefit from these agents. To improve the efficacy of checkpoint inhibitors, intratumoral (i.t.) injection with innate immune activators, TLR7 and TLR9 agonists, were tested along with programmed death-1 receptor (PD-1) blockade. The combination therapy suppressed tumor growth at the primary injected and distant sites in human papillomavirus-negative (HPV-negative) SCC7 and MOC1, and HPV-positive MEER syngeneic mouse models. Abscopal effects and suppression of secondary challenged tumor suggest that local treatment with TLR agonists in combination with anti-PD-1 provided systemic adaptive immunity. I.t. treatment with a TLR7 agonist increased the ratio of M1 to M2 tumor-associated macrophages (TAMs) and promoted the infiltration of tumor-specific IFNγ-producing CD8+ T cells. Anti-PD-1 treatment increased T cell receptor (TCR) clonality of CD8+ T cells in tumors and spleens of treated mice. Collectively, these experiments demonstrate that combination therapy with i.t. delivery of TLR agonists and PD-1 blockade activates TAMs and induces tumor-specific adaptive immune responses, leading to suppression of primary tumor growth and prevention of metastasis in HNSCC models.

Syngeneic Mouse Models of Oral Cancer Are Effectively Targeted by Anti-CD44-Based NIR-PIT

Oral cavity squamous cell carcinoma (OSCC) is considered one of the most aggressive subtypes of cancer. Anti-CD44 monoclonal antibodies (mAb) are a potential therapy against CD44 expressing OSCC; however, to date the therapeutic effects have been disappointing. Here, a new cancer treatment is described, near-infrared photoimmunotherapy (NIR-PIT), that uses anti-CD44 mAbs conjugated to the photoabsorber IR700DX. This conjugate is injected into mice harboring one of three CD44 expressing syngeneic murine oral cancer cell (MOC) lines, MOC1 (immunogenic), MOC2 mKate2 (moderately immunogenic), and MOC2-luc (poorly immunogenic). Binding of the anti-CD44-IR700 conjugate was shown to be specific and cell-specific cytotoxicity was observed after exposure of the cells to NIR light in vitro The anti-CD44-IR700 conjugate, when assessed in vivo, demonstrated deposition within the tumor with a high tumor-to-background ratio. Tumor-bearing mice were separated into four cohorts: no treatment; 100 μg of anti-CD44-IR700 i.v. only; NIR light exposure only; and 100 μg of anti-CD44-IR700 i.v. with NIR light exposure. NIR-PIT therapy, compared with the other groups, significantly inhibited tumor growth and prolonged survival in all three cell model systems. In conclusion, these data reveal that anti-CD44 antibodies are suitable as mAb-photoabsorber conjugates for NIR-PIT in MOC cells.Implications: This study using syngeneic mouse models, which better model the disease in humans than conventional xenografts, suggests that NIR-PIT with anti-CD44-IR700 is a potential candidate for the treatment of OSCC. Mol Cancer Res; 15(12); 1667-77. ©2017 AACR.

Rationale for neoadjuvant immunotherapy in head and neck squamous cell carcinoma

The clinical benefit of immunotherapy in recurrent, metastatic head and neck squamous cell carcinoma has fueled interest in revisiting neoadjuvant approaches to complement definitive treatment. Neoadjuvant strategies incorporating immune checkpoint inhibitors and other novel immune-based therapies in head and neck cancer are reviewed here, with particular attention paid to the rationale for these approaches from both a clinical and biologic discovery standpoint. The potential benefits of neoadjuvant immunotherapy include reduction of extent of surgery and the intensity of adjuvant therapy by tumor downstaging, reduction of the risk of distant metastatic spread by early introduction of systemic therapy, conversion of unresectable to resectable disease, and early evaluation of biomarkers of tumor response. We await early trial results utilizing these approaches to confirm both safety and initial efficacy in head and neck cancer.

Dose-dependent enhancement of T-lymphocyte priming and CTL lysis following ionizing radiation in an engineered model of oral cancer

OBJECTIVES

Determine if direct tumor cell cytotoxicity, antigen release, and susceptibility to T-lymphocyte killing following radiation treatment is dose-dependent.

MATERIALS AND METHODS

Mouse oral cancer cells were engineered to express full-length ovalbumin as a model antigen. Tumor antigen release with uptake and cross presentation of antigen by antigen presenting cells with subsequent priming and expansion of antigen-specific T-lymphocytes following radiation was modeled in vitro and in vivo. T-lymphocyte mediated killing was measured following radiation treatment using a novel impedance-based cytotoxicity assay.

RESULTS

Radiation treatment induced dose-dependent induction of executioner caspase activity and apoptosis in MOC1 cells. In vitro modeling of antigen release and T-lymphocyte priming demonstrated enhanced proliferation of OT-1 T-lymphocytes with 8Gy treatment of MOC1ova cells compared to 2Gy. This was validated in vivo following treatment of established MOC1ova tumors and adoptive transfer of antigen-specific T-lymphocytes. Using a novel impedance-based cytotoxicity assay, 8Gy enhanced tumor cell susceptibility to T-lymphocyte killing to a greater degree than 2Gy.

CONCLUSION

In the context of using clinically-relevant doses of radiation treatment as an adjuvant for immunotherapy, 8Gy is superior to 2Gy for induction of antigen-specific immune responses and enhancing tumor cell susceptibility to T-lymphocyte killing. These findings have significant implications for the design of trials combining radiation and immunotherapy.

Sorafenib controls the epithelial‑mesenchymal transition of ovarian cancer cells via EGF and the CD44‑HA signaling pathway in a cell type‑dependent manner

Cluster of differentiation (CD) 44 and epidermal growth factor (EGF) are closely involved in cellular migration and have been used as stem cell markers. Although the hyaluronan (HA)‑binding CD44 is responsible for enhanced cellular motility, the mechanism underlying its actions in various cell types and clinical conditions have yet to be elucidated. In the present study, the multikinase inhibitor sorafenib was used to investigate the diverse effects of EGF stimulation on epithelial‑mesenchymal transition (EMT) in ovarian cancer cells using immunoblotting and reverse transcription‑polymerase chain reaction. In addition, the association between EGF and CD44/HA signaling pathways in the control of mesenchymal phenotype was determined by gene silencing with small interfering RNA transfection. EGF stimulation of ovarian cancer cells increased cellular migration, mesenchymal transition, CD44 expression and the activation of matrix metalloproteinase (MMP)‑2 and MMP‑9. Sorafenib effectively suppressed the loss of epithelial characteristics in EGF‑treated SK‑OV‑3 ovarian cancer cells, via targeting the mitogen‑activated protein kinase (MAPK)/extracellular signal‑regulated kinase (ERK) pathway. Although treatment of Caov‑3 ovarian cancer cells with sorafenib blocked the expression of mesenchymal phenotypes following EGF stimulation, EGF‑activated Caov‑3 cells exhibited reduced MAPK/ERK signaling. Furthermore, EGF‑activated Caov‑3 cells increased the expression of hyaluronan synthase 2 and HA‑CD44 ligation in EGF‑exposed Caov‑3 cells, which resulted in the activation of the Ras/Raf/MEK signaling pathway, amplification of migratory activity and the expression of mesenchymal markers, including N‑cadherin and vimentin. Furthermore, silencing EGFR in SK‑OV‑3 cells and CD44 in Caov‑3 cells suppressed their migratory activity, through inhibition of the MAPK/ERK pathway. The present results suggested that EGF‑mediated signaling may regulate metastasis and invasion of ovarian cancer cells, in a cancer cell type‑dependent manner.

Resistance to CTLA-4 checkpoint inhibition reversed through selective elimination of granulocytic myeloid cells

Purpose

Local immunosuppression remains a critical problem that limits clinically meaningful response to checkpoint inhibition in patients with head and neck cancer. Here, we assessed the impact of MDSC elimination on responses to CTLA-4 checkpoint inhibition.

Experimental Design

Murine syngeneic carcinoma immune infiltrates were characterized by flow cytometry. Granulocytic MDSCs (gMDSCs) were depleted and T-lymphocyte antigen-specific responses were measured. Tumor-bearing mice were treated with MDSC depletion and CTLA-4 checkpoint blockade. Immune signatures within the human HNSCC datasets from The Cancer Genome Atlas (TCGA) were analyzed and differentially expressed genes from sorted human peripheral MDSCs were examined.

Results

gMDSCs accumulated with tumor progression and correlated with depletion of effector immune cells. Selective depletion of gMDSC restored tumor and draining lymph node antigen-specific T-lymphocyte responses lost with tumor progression. A subset of T-cell inflamed tumors responded to CTLA-4 mAb alone, but the addition of gMDSC depletion induced CD8 T-lymphocyte-dependent rejection of established tumors in all treated mice that resulted in immunologic memory. MDSCs differentially expressed chemokine receptors. Analysis of the head and neck cancer TCGA cohort revealed high CTLA-4 and MDSC-related chemokine and an MDSC-rich gene expression profile with a T-cell inflamed phenotype in > 60% of patients. CXCR2 and CSF1R expression was validated on sorted peripheral blood MDSCs from HNSCC patients.

Conclusions

MDSCs are a major contributor to local immunosuppression that limits responses to checkpoint inhibition in head and neck cancer. Limitation of MDSC recruitment or function represents a rational strategy to enhance responses to CTLA-4-based checkpoint inhibition in these patients.

Anti-PD-L1 Efficacy Can Be Enhanced by Inhibition of Myeloid-Derived Suppressor Cells with a Selective Inhibitor of PI3Kδ/γ

Checkpoint inhibitors are relatively inefficacious in head and neck cancers, despite an abundance of genetic alterations and a T-cell-inflamed phenotype. One significant barrier to efficacy may be the recruitment of myeloid-derived suppressor cells (MDSC) into the tumor microenvironment. Here we demonstrate functional inhibition of MDSC with IPI-145, an inhibitor of PI3Kδ and PI3Kγ isoforms, which enhances responses to PD-L1 blockade. Combination therapy induced CD8+ T lymphocyte-dependent primary tumor growth delay and prolonged survival only in T-cell-inflamed tumor models of head and neck cancers. However, higher doses of IPI-145 reversed the observed enhancement of anti-PD-L1 efficacy due to off-target suppression of the activity of tumor-infiltrating T lymphocytes. Together, our results offer a preclinical proof of concept for the low-dose use of isoform-specific PI3Kδ/γ inhibitors to suppress MDSC to enhance responses to immune checkpoint blockade. Cancer Res; 77(10); 2607-19. ©2017 AACR.

Identification of stem-like cells and clinical significance of candidate stem cell markers in gastric cancer

The existence of gastric cancer stem cells (CSCs) has not been definitively proven and specific cell surface markers for identifying gastric CSCs have largely not been identified. Our research aimed to isolate potential gastric CSCs and clarify their clinical significance, while defining markers for GCSC identification and verification. Here, we report that spheroid cells possess stem cell-like properties, and overexpress certain stem cell markers. CD133 or CD44-positive cells also exhibit properties of CSCs. The expression of Oct4, Sox2, Gli1, CD44, CD133, p-AKT, and p-ERK was significantly higher in metastatic lesions compared to that in primary lesions. Elevated expression of some of these proteins was correlated with a more aggressive phenotype and poorer prognosis, including Oct4, Sox2, Gli1, CD44, and p-ERK. Multivariate Cox proportional hazards model analysis showed that only CD44 is an independent factor. Knockdown of CD44 down-regulated the stem cell-like properties, which was accompanied by the down-regulation of p-ERK and Oct4. Oct4 overexpression could reverse the decreased CSCs properties induced by CD44 knockdown. Taken together, our research revealed that spheroid cell culture, and CD133 or CD44-labeled FACS methods can be used to isolate gastric CSCs. Some CSC markers have clinical significance in predicting the prognosis. CD44 is an independent prognostic factor and maintains the properties of CSCs in CD44-p-ERK-Oct4 positive feedback loop.

Established T Cell-Inflamed Tumors Rejected after Adaptive Resistance Was Reversed by Combination STING Activation and PD-1 Pathway Blockade

Patients with head and neck squamous cell carcinoma harbor T cell-inflamed and non-T cell-inflamed tumors. Despite this, only 20% of patients respond to checkpoint inhibitor immunotherapy. Lack of induction of innate immunity through pattern-recognition receptors, such as the stimulator of interferon (IFN) genes (STING) receptor, may represent a significant barrier to the development of effective antitumor immunity. Here, we demonstrate robust control of a T cell-inflamed (MOC1), but not non-T cell-inflamed (MOC2), model of head and neck cancer by activation of the STING pathway with the synthetic cyclic dinucleotide RP,RP dithio-c-di-GMP. Rejection or durable tumor control of MOC1 tumors was dependent upon a functional STING receptor and CD8 T lymphocytes. STING activation resulted in increased tumor microenvironment type 1 and type 2 IFN and greater expression of PD-1 pathway components in vivo Established MOC1 tumors were rejected and distant tumors abscopally controlled, after adaptive immune resistance had been reversed by the addition of PD-L1 mAb. These findings suggest that PD-1 pathway blockade may reverse adaptive immune resistance following cyclic dinucleotide treatment, enhancing both local and systemic antitumor immunity. Cancer Immunol Res; 4(12); 1061-71. ©2016 AACR.

Trametinib plus 4-Methylumbelliferone Exhibits Antitumor Effects by ERK Blockade and CD44 Downregulation and Affects PD-1 and PD-L1 in Malignant Pleural Mesothelioma

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a highly aggressive malignancy in which the mitogen-activated protein kinase pathway plays a critical role in the regulation of tumorigenesis. Hyaluronic acid (HA) is a major component of the extracellular matrix, and elevated HA levels with a concurrent increase in malignant properties are associated with MPM.

METHODS

We evaluated the effects of trametinib, a mitogen-activated protein kinase (MEK) inhibitor, and 4-methylumbelliferone (4-MU), an HA synthesis inhibitor, alone and in combination on MPM cells in vitro and in vivo. We studied the effects of trametinib, 4-MU, and their combination on MPM cells by using cell viability assays, Western blot analysis, and a mouse xenograft model.

RESULTS

Trametinib and 4-MU exhibited antiproliferative activity in MPM cells. Trametinib blocked MEK-dependent extracellular signal-regulated kinase (ERK) phosphorylation and decreased CD44 expression in a concentration-dependent manner. Trametinib inhibited the expression of Fra-1 (the activator protein 1 [AP1] component), inhibited ERK phosphorylation, and decreased CD44 expression. 4-MU inhibited ERK phosphorylation but not CD44 expression. In a mouse xenograft model, trametinib and 4-MU alone suppressed tumor growth compared with a control. The combination had a greater inhibitory effect than either monotherapy. Immunohistochemical analysis showed that trametinib treatment alone significantly reduced expression of programmed cell death 1 ligand 1. Furthermore, the combination of trametinib and 4-MU resulted in higher expression of programmed cell death 1 and programmed cell death 1 ligand 1 than did the 4-MU treatment alone.

CONCLUSIONS

Our results suggest that trametinib and 4-MU are promising therapeutic agents in MPM and that further study of the combination is warranted.

Avoiding phagocytosis-related artifact in myeloid derived suppressor cell T-lymphocyte suppression assays

Myeloid-derived suppressor cells (MDSCs) have garnered much attention in recent years as a potential target for altering the immunosuppressive tumor microenvironment in a variety of solid tumor types. The ability to accurately assess the immunosuppressive capacity of MDSCs is fundamental to the development of therapeutic approaches aimed at disabling these immunosuppressive functions. In this article we provide evidence that the use of CD3/28 coated microbeads leads to artefactual T-lymphocyte suppression due to sequestration of beads by MDSCs isolated from the spleens of wild-type mice bearing subcutaneous syngeneic, carcinogen-induced oral cavity carcinomas. Mechanisms of this finding may include early MDSC death and acquisition of phagocytic capacity. These artefactual findings were avoided by eliminating the use of microbeads and instead using plate bound CD3/28 antibody as the T-lymphocyte stimulus. We propose model-specific validation of microbead-based MDSC assays, or use of an alternative stimulation approach such as plate bound CD3/28 antibodies.

Biomarker and Tumor Responses of Oral Cavity Squamous Cell Carcinoma to Trametinib: A Phase II Neoadjuvant Window-of-Opportunity Clinical Trial

Purpose: Ras/MEK/ERK pathway activation is common in oral cavity squamous cell carcinoma (OCSCC). We performed a neoadjuvant (preoperative) trial to determine the biomarker and tumor response of OCSCC to MEK inhibition with trametinib.Experimental Design: Patients with stage II-IV OCSCC received trametinib (2 mg/day, minimum 7 days) prior to surgery. Primary tumor specimens were obtained before and after trametinib to evaluate immunohistochemical staining for p-ERK1/2 and CD44, the primary endpoint. Secondary endpoints included changes in clinical tumor measurements and metabolic activity [maximum standardized uptake values (SUV_max) by F-18 fluorodeoxyglucose positron emission tomography/CT), and in tumor downstaging. Drug-related adverse events (AE) and surgical/wound complications were evaluated.Results: Of 20 enrolled patients, 17 (85%) completed the study. Three patients withdrew because of either trametinib-related (n = 2: nausea, duodenal perforation) or unrelated (n = 1: constipation) AEs. The most common AE was rash (9/20 patients, 45%). Seventeen patients underwent surgery. No unexpected surgical/wound complications occurred. Evaluable matched pre- and posttrametinib specimens were available in 15 (88%) of these patients. Reduction in p-ERK1/2 and CD44 expression occurred in 5 (33%) and 2 (13%) patients, respectively. Clinical tumor response by modified World Health Organization criteria was observed in 11 of 17 (65%) evaluable patients (median 46% decrease, range 14%-74%). Partial metabolic response (≥25% reduction in SUV_max) was observed in 6 of 13 (46%) evaluable patients (median 25% decrease, range 6%-52%). Clinical-to-pathologic tumor downstaging occurred in 9 of 17 (53%) evaluable patients.Conclusions: Trametinib resulted in significant reduction in Ras/MEK/ERK pathway activation and in clinical and metabolic tumor responses in patients with OCSCC. Clin Cancer Res; 23(9); 2186-94. ©2016 AACR.

Approaches for targeting cancer stem cells drug resistance

INTRODUCTION

Several reports have suggested that a population of undifferentiated cells known as cancer stem cells (CSCs), is responsible for cancer formation and maintenance. In the last decade, the presence of CSCs in solid cancers have been reported. Areas covered: This review summarizes the main approaches for targeting CSCs drug resistance. It is indeed known that CSCs may contribute to resistance to conventional chemotherapy, radiotherapy and targeted agents. Among the mechanisms by which CSCs escape anticancer therapies, removal of therapeutic agents by drug efflux pumps, enhanced DNA damage repair, activation of mitogenic/anti-apoptotic pathways; the main features of CSCs, stemness and EMT, are involved, as well as the capability to evade immune response. Expert opinion: Different approaches are suitable to target CSCs mediated drug resistance. Some of them are currently under clinical evaluation in different cancer types. A better understanding of CSC biology, as well as more accurate study design, may maximize the therapeutic effects of these agents. In this respect, it is important to establish: (i) which molecules should be targeted; (ii) what drug combinations may be suitable; (iii) which patient settings will CSC targeting offer the highest clinical benefit; and (iv) how to integrate therapeutic approaches targeting CSCs with standard cancer therapy.

Transcriptomic characterization of differential gene expression in oral squamous cell carcinoma: a meta-analysis of publicly available microarray data sets

Oral squamous cell carcinoma (OSCC) is a highly prevalent cancer worldwide, and OSCC often goes undiagnosed until advanced disease is present, which contributes to a low survival rate for OSCC patients. The identification of biomarkers for the early detection OSCC and novel therapeutic targets for OSCC treatment is an important research objective. We performed bioinformatics analyses of the gene expression profile of OSCC using microarray data to identify genes that contribute to the development of OSCC. We also predicted the transcription factors involved in the regulation of differential gene expression in OSCC. Our results showed that PI3K, EGFR, STAT1, and CPBP are important contributors to the changes in cellular physiology that occur during the development of OSCC. Therefore, these genes represent potential diagnostic biomarkers and therapeutic targets for OSCC.

Hyaluronan induces odontoblastic differentiation of dental pulp stem cells via CD44

Background

Dental pulp tissue contains many undifferentiated mesenchymal cells, which retain the ability to differentiate into mature cells. Induced pluripotent stem cells have been developed from various cell sources, including dental pulp-derived stem cells, and evaluated for potential application to regenerative therapy. Dental pulp tissues overexpress CD44, a cell-adhesion factor involved in the induction of mineralization. In this study, we investigated the effects of hyaluronan—a known CD44 ligand—on dental pulp stem cells (DPSCs).

Methods

DPSC CD44 expression was analyzed using immunofluorescence staining, flow cytometry, and western blotting. Cell proliferation was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Effects of hyaluronan on the cell cycle were analyzed by flow cytometry. Alkaline phosphatase activity was employed as marker of mineralization and measured by fluorometric quantification and western blotting. Bone morphogenetic protein (BMP)-2, BMP-4, dentin sialophosphoprotein (DSPP), and dentin matrix acidic phosphoprotein 1 (DMP-1) levels were measured using real-time polymerase chain reaction. Odontoblastic differentiation and the close cell signaling examination of DPSC differentiation were determined using western blotting.

Results

Hyaluronan induced expression of the odontoblastic differentiation markers DMP-1 and DSPP. Moreover, the odontoblastic differentiation induced by hyaluronan was mediated by CD44—but not by Akt, Smad1 or MAPK signaling.

Conclusions

Our results indicate that hyaluronan induces odontoblastic differentiation of DPSCs via CD44. This suggests that hyaluronan plays a crucial role in the induction of odontoblastic differentiation from DPSCs. Our findings may aid the development of new, inexpensive, and effective conservative treatments for dental pulp repair.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0399-8) contains supplementary material, which is available to authorized users.

JARID1B Enables Transit between Distinct States of the Stem-like Cell Population in Oral Cancers

The degree of heterogeneity among cancer stem cells (CSC) remains ill-defined and may hinder effective anti-CSC therapy. Evaluation of oral cancers for such heterogeneity identified two compartments within the CSC pool. One compartment was detected using a reporter for expression of the H3K4me3 demethylase JARID1B to isolate a JARID1B(high) fraction of cells with stem cell-like function. JARID1B(high) cells expressed oral CSC markers including CD44 and ALDH1 and showed increased PI3K pathway activation. They were distinguished from a fraction in a G0-like cell-cycle state characterized by low reactive oxygen species and suppressed PI3K/AKT signaling. G0-like cells lacked conventional CSC markers but were primed to acquire stem cell-like function by upregulating JARID1B, which directly mediated transition to a state expressing known oral CSC markers. The transition was regulated by PI3K signals acting upstream of JARID1B expression, resulting in PI3K inhibition depleting JARID1B(high) cells but expanding the G0-like subset. These findings define a novel developmental relationship between two cell phenotypes that may jointly contribute to CSC maintenance. Expansion of the G0-like subset during targeted depletion of JARID1B(high) cells implicates it as a candidate therapeutic target within the oral CSC pool. Cancer Res; 76(18); 5538-49. ©2016 AACR.

WNT5A signaling impairs breast cancer cell migration and invasion via mechanisms independent of the epithelial-mesenchymal transition

BACKGROUND

WNT5A (-/-) mammary tissue has been shown to exhibit increased ductal elongation, suggesting elevated mammary cell migration. Increased epithelial cell migration/invasion has often but not always been linked to the epithelial-mesenchymal transition (EMT). In the current study, we investigated the loss of WNT5A in HB2 human mammary epithelial cells and hypothesized that this loss increased their invasion via the EMT. Based on these results, we postulated that suppression of breast cancer cell migration and invasion by WNT5A is due to EMT reversal.

METHODS

WNT5A was transiently knocked down using specific siRNAs, whereas WNT5A signaling was induced in MDA-MB468 and MDA-MB231 breast cancer cells by stably transfecting cells with WNT5A or treating them with recombinant WNT5A (rWNT5A). Changes in EMT markers, CD44, pAKT and AKT expression were assessed using Western blotting and immunofluorescence. The physiological relevance of altered WNT5A signaling was assessed using migration and invasion assays.

RESULTS

WNT5A knockdown in HB2 mammary epithelial cells resulted in EMT-like changes and increased invasiveness, and these changes were partially reversed by the addition of rWNT5A. These data suggest that WNT5A might inhibit breast cancer cell migration and invasion by a similar EMT reversal. Contrary to our expectations, we did not observe any changes in the EMT status of breast cancer cells, either after treatment with rWNT5A or stable transfection with a WNT5A plasmid, despite the parallel WNT5A-induced inhibition of migration and invasion. Instead, we found that WNT5A signaling impaired CD44 expression and its downstream signaling via AKT. Moreover, knocking down CD44 in breast cancer cells using siRNA impaired cell migration and invasion.

CONCLUSIONS

WNT5A bi-directionally regulates EMT in mammary epithelial cells, thereby affecting their migration and invasion. However, the ability of WNT5A to inhibit breast cancer cell migration and invasion is an EMT-independent mechanism that, at least in part, can be explained by decreased CD44 expression.

Anti-Cancer Stem-like Cell Compounds in Clinical Development - An Overview and Critical Appraisal

Cancer stem-like cells (CSC) represent a subpopulation of tumor cells with elevated tumor-initiating potential. Upon differentiation, they replenish the bulk of the tumor cell population. Enhanced tumor-forming capacity, resistance to antitumor drugs, and metastasis-forming potential are the hallmark traits of CSCs. Given these properties, it is not surprising that CSCs have become a therapeutic target of prime interest in drug discovery. In fact, over the last few years, an enormous number of articles describing compounds endowed with anti-CSC activities have been published. In the meanwhile, several of these compounds and also approaches that are not based on the use of pharmacologically active compounds (e.g., vaccination, radiotherapy) have progressed into clinical studies. This article gives an overview of these compounds, proposes a tentative classification, and describes their biological properties and their developmental stage. Eventually, we discuss the optimal clinical setting for these compounds, the need for biomarkers allowing patient selection, the redundancy of CSC signaling pathways and the utility of employing combinations of anti-CSC compounds and the therapeutic limitations posed by the plasticity of CSCs.

Enhanced Tumor Control with Combination mTOR and PD-L1 Inhibition in Syngeneic Oral Cavity Cancers

Significant subsets of patients with oral cancer fail to respond to single-agent programmed death (PD) blockade. Syngeneic models of oral cancer were used to determine if blocking oncogenic signaling improved in vivo responses to PD-L1 monoclonal antibody (mAb). Anti-PD-L1 enhanced durable primary tumor control and survival when combined with mTOR (rapamycin), but not in combination with MEK inhibition (PD901) in immunogenic MOC1 tumors. Conversely, PD-L1 mAb did not enhance tumor control in poorly immunogenic MOC2 tumors. Rapamycin enhanced expansion of peripheral antigen-specific CD8 T cells and IFNγ production following ex vivo antigen stimulation. More CD8 T cells infiltrated and were activated after PD-L1 mAb treatment in mice with immunogenic MOC1 tumors, which were stable or increased by the addition of rapamycin, but suppressed when PD901 was added. Rapamycin increased IFNγ production capacity in peripheral and tumor-infiltrating CD8 T cells. In vivo antibody depletion revealed a CD8 T-cell-dependent, and not NK cell-dependent mechanism of tumor growth inhibition after treatment with rapamycin and PD-L1 mAb, ruling out significant effects from NK cell-mediated antibody-dependent cellular cytotoxicity. Rapamycin also enhanced IFNγ or PD-L1 mAb treatment-associated induction of MHC class I expression on MOC1 tumor cells, an effect abrogated by depleting infiltrating CD8 T cells from the tumor microenvironment. These data conflict with traditional views of rapamycin as a universal immunosuppressant, and when combined with evidence of enhanced antitumor activity with the combination of rapamycin and PD-L1 mAb, suggest that this treatment combination deserves careful evaluation in the clinical setting. Cancer Immunol Res; 4(7); 611-20. ©2016 AACR.

Pools of programmed death-ligand within the oral cavity tumor microenvironment: Variable alteration by targeted therapies

BACKGROUND

Enhanced understanding of programmed death-ligand (PD-L) expression in oral cancer is important for establishing rational combinations of emerging immune checkpoint and molecular targeted therapies.

METHODS

We assessed PD-L and interferon (IFN) expression in immunogenic murine oral cancer-1 (MOC1) and poorly immunogenic MOC2 cell models after treatment with mammalian target of rapamycin (mTOR) and MEK1/2 small molecule inhibitors in vitro and in vivo.

RESULTS

PD-L1 but not PD-L2 is expressed on MOC1 and 2 cells and is type I and II IFN-dependent. PD-L1 is differentially expressed on cancer and endothelial cells and infiltrating myeloid-derived suppressor cells, macrophages, and regulatory T cells (Tregs) in highly and poorly immunogenic tumors. PD-L1 expression is variably altered after treatment with inhibitors in vivo, with an imperfect relationship to alterations in IFN levels in the tumor microenvironment.

CONCLUSION

PD-L1 expressed on cancer and infiltrating immune cells is variably altered by targeted therapies and may, in part, reflect changes in tumor IFN. © 2016 Wiley Periodicals, Inc. Head Neck 38:1176-1186, 2016.

Growth-suppressive effect of suberoylanilide hydroxamic acid (SAHA) on human oral cancer cells

PURPOSE

The histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) has been reported to exhibit anticancer activities in various cancer cell types, but as yet there are few reports on the anticancer effects of SAHA in oral squamous cell carcinoma (OSCC)-derived cells and xenograft models.

METHODS

The anti-proliferative and apoptotic activities of SAHA were assessed in human HSC-3 and HSC-4 (OSCC)-derived cell lines and JB6 normal mouse skin-derived epidermal cells using histone acetylation, soft agar colony formation, trypan blue exclusion, 4'-6-diamidino-2-phenylindole (DAPI) staining, Live/Dead viability/cytotoxicity and Western blot analyses.

RESULTS

We found that SAHA treatment resulted in hyperacetylation of histones H2A and H3 and a concomitant decrease in the viability of HSC-3 and HSC-4 cells. SAHA also significantly inhibited the neoplastic transformation of JB6 cells treated with TPA, whereas the viability of these cells was not affected by this treatment. Additionally, we found that SAHA suppressed the anchorage-independent growth (colony forming capacity in soft agar) of HSC-3 and HSC-4 cells. DAPI staining, Live/Dead and Western blot analyses revealed that SAHA can induce caspase-dependent apoptosis in HSC-3 and HSC-4 cells. We also found that SAHA treatment led to inhibition of ERK phosphorylation, and that two MEK inhibitors potentiated SAHA-mediated apoptosis. Okadaic acid treatment inhibited SAHA-mediated apoptosis in both the HSC-3 and HSC-4 cell lines, wheras SAHA induced a profound in vivo inhibition of tumor growth in HSC-3 xenografts.

CONCLUSIONS

Our results indicate that the ERK signaling pathway may constitute a critical denominator of SAHA-induced apoptosis in OSCC-derived cells and that SAHA may have therapeutic potential for OSCC.

mTOR and MEK1/2 inhibition differentially modulate tumor growth and the immune microenvironment in syngeneic models of oral cavity cancer

We investigated the effects of mTOR and MEK1/2 inhibition on tumor growth and the tumor microenvironment in immunogenic and poorly immunogenic models of murine oral cancer. In vitro, rapamycin and PD901 inhibited signaling through expected downstream targets, but only PD901 reduced viability and altered function of MOC cells. Following transplantation of MOC cells into immune-competent mice, effects on both cancer and infiltrating immune cells were characterized following rapamycin and/or PD901 treatment for 21 days. In vivo, both rapamycin and PD901 inhibition reduced primary growth of established MOC tumors on treatment. Following withdrawal of PD901, rapid rebound of tumor growth limited survival, whereas durable tumor control was observed following rapamycin treatment in immunogenic MOC1 tumors despite more robust inhibition of oncogenic signaling by PD901. Characterization of the immune microenvironment revealed diminished infiltration and activation of antigen-specific CD8+ T-cells and other immune cells following PD901 but not rapamycin in immunogenic tumors. Subsequent in vitro T-cell assays validated robust inhibition of T-cell expansion and activation following MEK inhibition compared to mTOR inhibition. CD8 cell depletion abrogated rapamycin-induced primary tumor growth inhibition in MOC1 mice. These data have critical implications in the design of combination targeted and immune therapies in oral cancer.

Uncovering the dual role of RHAMM as an HA receptor and a regulator of CD44 expression in RHAMM-expressing mesenchymal progenitor cells

The interaction of hyaluronan (HA) with mesenchymal progenitor cells impacts trafficking and fate after tissue colonization during wound repair and these events contribute to diseases such as cancer. How this interaction occurs is poorly understood. Using 10T½ cells as a mesenchymal progenitor model and fluorescent (F-HA) or gold-labeled HA (G-HA) polymers, we studied the role of two HA receptors, RHAMM and CD44, in HA binding and uptake in non-adherent and adherent mesenchymal progenitor (10T½) cells to mimic aspects of cell trafficking and tissue colonization. We show that fluorescent labeled HA (F-HA) binding/uptake was high in non-adherent cells but dropped over time as cells became increasingly adherent. Non-adherent cells displayed both CD44 and RHAMM but only function-blocking anti-RHAMM and not anti-CD44 antibodies significantly reduced F-HA binding/uptake. Adherent cells, which also expressed CD44 and RHAMM, primarily utilized CD44 to bind to F-HA since anti-CD44 but not anti-RHAMM antibodies blocked F-HA uptake. RHAMM overexpression in adherent 10T½ cells led to increased F-HA uptake but this increased binding remained CD44 dependent. Further studies showed that RHAMM-transfection increased CD44 mRNA and protein expression while blocking RHAMM function reduced expression. Collectively, these results suggest that cellular microenvironments in which these receptors function as HA binding proteins differ significantly, and that RHAMM plays at least two roles in F-HA binding by acting as an HA receptor in non-attached cells and by regulating CD44 expression and display in attached cells. Our findings demonstrate adhesion-dependent mechanisms governing HA binding/ uptake that may impact development of new mesenchymal cell-based therapies.

Sulforaphane inhibits invasion by phosphorylating ERK1/2 to regulate E-cadherin and CD44v6 in human prostate cancer DU145 cells

Advanced prostate cancer has highly invasive potential, which may lead to metastasis associated with poor prognosis. Sulforaphane (SFN), abundant in cruciferous vegetables, exhibited effective resistance to carcinogenesis in a variety of tumors. The aim of the present study was to investigate whether SFN inhibited invasion in human prostate cancer cells via sustained activation of ERK1/2 and downstream signaling by an invasion assay, gelatin zymography and western blot analysis. The results showed that SFN inhibited invasion and we characterized the underlying mechanisms in human DU145 prostate cancer cells. SFN (15 µM) changed cell morphology leading to short‑cell pseudopodia which may suppress tumor migration and invasion. The Transwell assay showed that SFN phosphorylated ERK1/2 in a dose- and time-dependent manner and significantly inhibited cell invasion, while the effect was reduced by the ERK1/2 blocker PD98059 (25 µM). Furthermore, these effects contributed to the upregulation of E-cadherin and the downregulation of CD44v6 and were eradicated by PD98059. Western blot analysis and gelatin zymography showed that SFN decreased the expression and activity of MMP-2. Thus, SFN inhibited invasion by activating ERK1/2 to upregulate E-cadherin and downregulate CD44v6, thereby reducing MMP-2 expression and activity. E-cadherin is an invasion inhibitor, while CD44v6 and MMP-2 are invasion promoters. Therefore, SFN is a prospective therapeutic agent that may be used to prevent invasion in prostate cancer.

Mechanisms of Invasion in Head and Neck Cancer

CONTEXT

The highly invasive properties demonstrated by head and neck squamous cell carcinoma (HNSCC) are often associated with locoregional recurrence and lymph node metastasis in patients and is a key factor leading to an expected 5-year survival rate of approximately 50% for patients with advanced disease. It is important to understand the features and mediators of HNSCC invasion so that new treatment approaches can be developed.

OBJECTIVES

To provide an overview of the characteristics, mediators, and mechanisms of HNSCC invasion.

DATA SOURCES

A literature review of peer-reviewed articles in PubMed on HNSCC invasion.

CONCLUSIONS

Histologic features of HNSCC tumors can help predict prognosis and influence clinical treatment decisions. Cell surface receptors, signaling pathways, proteases, invadopodia function, epithelial-mesenchymal transition, microRNAs, and tumor microenvironment are all involved in the regulation of the invasive behavior of HNSCC cells. Identifying effective HNSCC invasion inhibitors has the potential to improve outcomes for patients by reducing the rate of spread and increasing responsiveness to chemoradiation.

CD271 is a functional and targetable marker of tumor-initiating cells in head and neck squamous cell carcinoma

Tumor-initiating cells (TICs) in squamous cell carcinoma of the head and neck (SCCHN) are best characterized by their surface expression of CD44. Although there is great interest in identifying strategies to target this population, no marker of these cells has been found to be functionally active. Here, we examined the expression of the purported marker of normal human oral epithelial stem cells, CD271. We show that CD271 expression is restricted to a subset of the CD44⁺ cells. Using xenograft assays, we show that the CD44⁺CD271⁺ subpopulation contains the most tumorigenic cells. Loss of CD271 function results in a block in the G2-M phase of the cell cycle and a profound negative impact on the capacity of these cells to initiate tumor formation in vivo. Incubation with recombinant NGF results in enhanced phosphorylation of Erk, providing additional evidence that CD271 is functionally active. Finally, incubation of SCCHN cells with antibody to CD271 results in decreased Erk phosphorylation and decreased tumor formation in vivo. Thus, our data are the first to demonstrate that CD271 more specifically identifies the TIC subpopulation within the CD44⁺ compartment in SCCHN and that this receptor is a functionally active and targetable molecule.

Genomic analysis to define molecular basis of aggressiveness in a mouse model of oral cancer

To investigate the molecular basis underlying aggressive behavior in oral squamous cell carcinoma (OSCC), our laboratory developed a carcinogen-induced mouse oral cancer (MOC) cell line model that encompasses the growth and metastasis spectrum of its human counterpart. We performed next-generation sequencing (NGS) and gene expression microarray profiles to explore the genomic and transcriptional backgrounds of the differential MOC line phenotypes, as well as, the cross-species relevance of the model. Here we describe the comparative analysis of NGS (www.ncbi.nlm.nih.gov/biosample?LinkName=bioproject_biosample_all&from_uid=247825) and expression microarray (www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE50041) data from the MOC lines and corresponding human data, as described in our recent publication [1].

Asporin participates in gastric cancer cell growth and migration by influencing EGF receptor signaling

Asporin (ASPN), a novel member of the small leucine-rich proteoglycan (SLRP) family, serves as a key component of the tumor stroma and has been reported to be abnormally expressed in certain types of tumors. Specifically, the proteoglycan was proven to activate the coordinated invasion of scirrhous gastric cancer and cancer-associated fibroblasts. However, the role of ASPN in cancer cell growth and metastasis has not yet been addressed. In the present study, we aimed to evaluate the tumoricidal benefits of ASPN on tumorigenesis and progression of gastric cancer. Firstly, it was demonstrated that ASPN was overexpressed in gastric carcinoma tissues when compared to the corresponding non‑cancerous tissues, and it had varied levels of expression in gastric cancer epithelial cell lines. Additionally, we assessed the effects of transient siRNA‑mediated ASPN knockdown on gastric cancer cells. ASPN silencing inhibited proliferation and suppressed the migration of immortalized neoplastic epithelial cells. Furthermore, at the molecular level, we found that downregulation of ASPN blocked the anti-apoptotic molecule Bcl-2, increased the expression of pro-apoptotic molecule Bad, reduced the expression of migration-related proteins CD44 and matrix metalloproteinase (MMP)-2, and abrogated the activation of the phosphorylation status of ERK and epidermal growth factor (EGF) and its receptor (EGFR). Collectively, our findings indicate that ASPN is upregulated and plays an oncogenic role in gastric cancer progression and metastasis by influencing the EGFR signaling pathway.

Identification and characterization of Dicer1e, a Dicer1 protein variant, in oral cancer cells

Background

The human dicer1 gene has been predicted to produce several mRNA variants that encode truncated Dicer1 proteins of varying lengths. One of these Dicer1 variants, Dicer1e, was recently found to be differentially expressed in breast cancer cells. Because the expression and function of the Dicer1e protein variant has not been well characterized and the underlying molecular mechanisms for the development of oral squamous cell carcinomas (OSCCs) are poorly understood, the present study sought to characterize the biological role of Dicer1e and determine its relationship, if any, to OSCC pathogenesis.

Methods

Western blot analyses were used to examine Dicer1e expression levels in a panel of oral cancer cells/tissues and during epithelial-mesenchymal transition (EMT), followed by 5′/3′-RACE analyses to obtain the full-length Dicer1e transcript. Biochemical fractionation and indirect immunofluorescent studies were performed to determine the cellular localization of Dicer1e and the effects of Dicer1e silencing on cancer cell proliferation, clonogenicity, and drug sensitivity were also assessed.

Results

Dicer1e protein levels were found to be overexpressed in OSCC cell lines of epithelial phenotype and in OSCC tissues with its levels downregulated during EMT. Moreover, the Dicer1e protein was observed to predominantly localize in the nucleus. 5′/3′-RACE analyses confirmed the presence of the Dicer1e transcript and silencing of Dicer1e impaired both cancer cell proliferation and clonogenicity by inducing either apoptosis and/or G2/M cell cycle arrest. Lastly, Dicer1e knockdown enhanced the chemosensitivity of oral cancer cells to cisplatin.

Conclusion

The expression levels of Dicer1e influence the pathogenesis of oral cancer cells and alter their response to chemosensitivity, thus supporting the importance of Dicer1e as a therapeutic target for OSCCs.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-190) contains supplementary material, which is available to authorized users.

Induction of cell cycle arrest and apoptosis in caspase-3 deficient MCF-7 cells by Dillenia suffruticosa root extract via multiple signalling pathways

BACKGROUND

Dillenia suffruticosa root dichloromethane extract (DCM-DS) has been reported to exhibit strong cytotoxicity towards breast cancer cells. The present study was designed to investigate the cell cycle profile, mode of cell death and signalling pathways of DCM-DS-treated human caspase-3 deficient MCF-7 breast cancer cells.

METHODS

Dillenia suffruticosa root was extracted by sequential solvent extraction. The anti-proliferative activity of DCM-DS was determined by using MTT assay. The mode of cell death was evaluated by using inverted light microscope and Annexin-V/PI-flow cytometry analysis. Cell cycle analysis and measurement of intracellular reactive oxygen species (ROS) were performed by using flow cytometry. MCF-7 cells were co-treated with antioxidants α-tocopherol and ascorbic acid to evaluate whether the cell death was mainly due to oxidative stress. GeXP-based multiplex system was employed to investigate the expression of apoptotic, growth and survival genes in MCF-7 cells. Western blot analysis was performed to confirm the expression of the genes.

RESULTS

DCM-DS was cytotoxic to the MCF-7 cells in a time-and dose-dependent manner. The IC50 values of DCM-DS at 24, 48 and 72 hours were 20.3 ± 2.8, 17.8 ± 1.5 and 15.5 ± 0.5 μg/mL, respectively. Cell cycle analysis revealed that DCM-DS induced G0/G1 and G2/M phase cell cycle arrest in MCF-7 cells at low concentration (12.5 and 25 μg/mL) and high concentration (50 μg/mL), respectively. Although Annexin-V/PI-flow cytometry analysis has confirmed that DCM-DS induced apoptosis in MCF-7 cells, the distinct characteristics of apoptosis such as membrane blebbing, chromatin condensation, nuclear fragmentation and formation of apoptotic bodies were not observed under microscope. DCM-DS induced formation of ROS in MCF-7 cells. Nevertheless, co-treatment with antioxidants did not attenuate the cell death at low concentration of DCM-DS. The pro-apoptotic gene JNK was up-regulated whereby anti-apoptotic genes AKT1 and ERK1/2 were down-regulated in a dose-dependent manner. Western blot analysis has confirmed that DCM-DS significantly up-regulated the expression of pro-apoptotic JNK1, pJNK and down-regulated anti-apoptotic AKT1, ERK1 in MCF-7 cells.

CONCLUSION

DCM-DS induced cell cycle arrest and apoptosis in MCF-7 cells via multiple signalling pathways. It shows the potential of DCM-DS to be developed to target the cancer cells with mutant caspase-3.

A surprising cross-species conservation in the genomic landscape of mouse and human oral cancer identifies a transcriptional signature predicting metastatic disease

PURPOSE

Improved understanding of the molecular basis underlying oral squamous cell carcinoma (OSCC) aggressive growth has significant clinical implications. Herein, cross-species genomic comparison of carcinogen-induced murine and human OSCCs with indolent or metastatic growth yielded results with surprising translational relevance.

EXPERIMENTAL DESIGN

Murine OSCC cell lines were subjected to next-generation sequencing (NGS) to define their mutational landscape, to define novel candidate cancer genes, and to assess for parallels with known drivers in human OSCC. Expression arrays identified a mouse metastasis signature, and we assessed its representation in four independent human datasets comprising 324 patients using weighted voting and gene set enrichment analysis. Kaplan-Meier analysis and multivariate Cox proportional hazards modeling were used to stratify outcomes. A quantitative real-time PCR assay based on the mouse signature coupled to a machine-learning algorithm was developed and used to stratify an independent set of 31 patients with respect to metastatic lymphadenopathy.

RESULTS

NGS revealed conservation of human driver pathway mutations in mouse OSCC, including in Trp53, mitogen-activated protein kinase, phosphoinositide 3-kinase, NOTCH, JAK/STAT, and Fat1-4. Moreover, comparative analysis between The Cancer Genome Atlas and mouse samples defined AKAP9, MED12L, and MYH6 as novel putative cancer genes. Expression analysis identified a transcriptional signature predicting aggressiveness and clinical outcomes, which were validated in four independent human OSCC datasets. Finally, we harnessed the translational potential of this signature by creating a clinically feasible assay that stratified patients with OSCC with a 93.5% accuracy.

CONCLUSIONS

These data demonstrate surprising cross-species genomic conservation that has translational relevance for human oral squamous cell cancer. Clin Cancer Res; 20(11); 2873-84. ©2014 AACR.

Prognostic biomarkers in phase II trial of cetuximab-containing induction and chemoradiation in resectable HNSCC: Eastern cooperative oncology group E2303

PURPOSE

We sought to evaluate the correlation between tissue biomarker expression (using standardized, quantitative immunofluorescence) and clinical outcome in the E2303 trial.

EXPERIMENTAL DESIGN

Sixty-three eligible patients with operable stage III/IV head and neck squamous cell cancer (HNSCC) participated in the Eastern Cooperative Oncology Group (ECOG) 2303 phase II trial of induction chemotherapy with weekly cetuximab, paclitaxel, and carboplatin followed by chemoradiation with the same regimen. A tissue microarray (TMA) was constructed and EGF receptor (EGFR), ERK1/2, Met, Akt, STAT3, β-catenin, E-cadherin, EGFR Variant III, insulin-like growth factor-1 receptor, NF-κB, p53, PI3Kp85, PI3Kp110a, PTEN, NRAS, and pRb protein expression levels were assessed using automated quantitative protein analysis (AQUA). For each dichotomized biomarker, overall survival (OS), progression-free survival (PFS), and event-free survival (EFS) were estimated by the Kaplan-Meier method and compared using log-rank tests. Multivariable Cox proportional hazards models were used to estimate HRs and test for significance.

RESULTS

Forty-two of 63 patients with TMA data on at least one biomarker were included in the biomarker analysis. Tumor extracellular signal-regulated kinase (ERK)1/2 levels were significantly associated with PFS [HR (low/high), 3.29; P = 0.026] and OS [HR (low/high), 4.34; P = 0.008]. On multivariable Cox regression analysis, ERK1/2 remained significantly associated with OS (P = 0.024) and PFS (P = 0.022) after controlling for primary site (oropharynx vs. non-oropharynx) and disease stage (III vs. IV), respectively. Clustering analysis revealed that clusters indicative of activated RAS/MAPK/ERK and/or PI3K/Akt pathways were associated with inferior OS and/or PFS and maintained significance in multivariable analysis.

CONCLUSIONS

These results implicate PI3K/Akt and RAS/MAPK/ERK pathways in resistance to cetuximab-containing chemoradiation in HNSCC. Large prospective studies are required to validate these results.

CD44 gene polymorphisms and environmental factors on oral cancer susceptibility in Taiwan

Background

Oral squamous cell carcinoma (OSCC) is the fourth leading cause of male cancer death in Taiwan. Exposure to environmental carcinogens is the primary risk factor for developing OSCC. CD44, a well-known tumor marker, plays a crucial role in tumor cell differentiation, invasion, and metastasis. This study investigated CD44 single-nucleotide polymorphisms (SNPs) with environmental risk factors to determine OSCC susceptibility and clinicopathological characteristics.

Methodology/Principal Findings

Real-time polymerase chain reaction (PCR) was used to analyze 6 SNPs of CD44 in 599 patients with oral cancer and 561 cancer-free controls. We determined that the CD44 rs187115 polymorphism carriers with the genotype AG, GG, or AG+GG were associated with oral cancer susceptibility. Among 731 smokers, CD44 polymorphisms carriers with the betel-nut chewing habit had a 10.30–37.63-fold greater risk of having oral cancer compared to CD44 wild-type (WT) carriers without the betel-nut chewing habit. Among 552 betel-nut chewers, CD44 polymorphisms carriers who smoked had a 4.23–16.11-fold greater risk of having oral cancer compared to those who carried the WT but did not smoke. Finally, we also observed that the stage III and IV oral cancer patients had higher frequencies of CD44 rs187115 polymorphisms with the variant genotype (AG+GG) compared with the wild-type (WT) carriers.

Conclusion

Our results suggest that gene–environment interactions between the CD44 polymorphisms and betel quid chewing and tobacco smoking increase the susceptibility to oral cancer development. Patients with CD44 rs187115 variant genotypes (AG+GG) were correlated with a higher risk of oral cancer development, and these patients may possess greater chemoresistance to advanced- to late-stage oral cancer than WT carriers do. The CD44 rs187115 polymorphism has potential predictive significance in oral carcinogenesis and also may be applied as factors to predict the clinical stage in OSCC patients.

Sulforaphane inhibits invasion via activating ERK1/2 signaling in human glioblastoma U87MG and U373MG cells

BACKGROUND

Glioblastoma has highly invasive potential, which might result in poor prognosis and therapeutic failure. Hence, the key we study is to find effective therapies to repress migration and invasion. Sulforaphane (SFN) was demonstrated to inhibit cell growth in a variety of tumors. Here, we will further investigate whether SFN inhibits migration and invasion and find the possible mechanisms in human glioblastoma U87MG and U373MG cells.

METHODS

First, the optimal time and dose of SFN for migration and invasion study were determined via cell viability and cell morphological assay. Further, scratch assay and transwell invasion assay were employed to investigate the effect of SFN on migration and invasion. Meanwhile, Western blots were used to detect the molecular linkage among invasion related proteins phosphorylated ERK1/2, matrix metalloproteinase-2 (MMP-2) and CD44v6. Furthermore, Gelatin zymography was performed to detect the inhibition of MMP-2 activation. In addition, ERK1/2 blocker PD98059 (25 µM) was integrated to find the link between activated ERK1/2 and invasion, MMP-2 and CD44v6.

RESULTS

The results showed that SFN (20 µM) remarkably reduced the formation of cell pseudopodia, indicating that SFN might inhibit cell motility. As expected, scratch assay and transwell invasion assay showed that SFN inhibited glioblastoma cell migration and invasion. Western blot and Gelatin zymography showed that SFN phosphorylated ERK1/2 in a sustained way, which contributed to the downregulated MMP-2 expression and activity, and the upregulated CD44v6 expression. These molecular interactions resulted in the inhibition of cell invasion.

CONCLUSIONS

SFN inhibited migration and invasion processes. Furthermore, SFN inhibited invasion via activating ERK1/2 in a sustained way. The accumulated ERK1/2 activation downregulated MMP-2 expression and decreased its activity and upregulated CD44v6. SFN might be a potential therapeutic agent by activating ERK1/2 signaling against human glioblastoma.

CD26 expression on T-anaplastic large cell lymphoma (ALCL) line Karpas 299 is associated with increased expression of versican and MT1-MMP and enhanced adhesion

Background

CD26/dipeptidyl peptidase IV (DPPIV) is a multifunctional membrane protein with a key role in T-cell biology and also serves as a marker of aggressive cancers, including T-cell malignancies.

Methods

Versican expression was measured by real-time RT-PCR and Western blots. Gene silencing of versican in parental Karpas 299 cells was performed using transduction-ready viral particles. The effect of versican depletion on surface expression of MT1-MMP was monitored by flow cytometry and surface biotinylation. CD44 secretion/cleavage and ERK (1/2) activation was followed by Western blotting. Collagenase I activity was measured by a live cell assay and in vesicles using a liquid-phase assay. Adhesion to collagen I was quantified by an MTS assay.

Results

Versican expression was down-regulated in CD26-depleted Karpas 299 cells compared to the parental T-ALCL Karpas 299 cells. Knock down of versican in the parental Karpas 299 cells led to decreased MT1-MMP surface expression as well as decreased CD44 expression and secretion of the cleaved form of CD44. Parental Karpas 299 cells also exhibited higher collagenase I activity and greater adhesion to collagenase I than CD26-knockdown or versican-knockdown cells. ERK activation was also highest in parental Karpas 299 cells compared to CD26-knockdown or versican-knockdown clones.

Conclusions

Our data indicate that CD26 has a key role in cell adhesion and invasion, and potentially in tumorigenesis of T-cell lines, through its association with molecules and signal transduction pathways integral to these processes.