Animal models for the study of squamous cell carcinoma of the upper aerodigestive tract: a historical perspective with review of their utility and limitations. Part A. Chemically-induced de novo cancer, syngeneic animal models of HNSCC, animal models of transplanted xenogeneic human tumors

Towards system genetics analysis of head and neck squamous cell carcinoma using the mouse model, cellular platform, and clinical human data

Head and neck squamous cell cancer (HNSCC) is a leading global malignancy. Every year, More than 830 000 people are diagnosed with HNSCC globally, with more than 430 000 fatalities. HNSCC is a deadly diverse malignancy with many tumor locations and biological characteristics. It originates from the squamous epithelium of the oral cavity, oropharynx, nasopharynx, larynx, and hypopharynx. The most frequently impacted regions are the tongue and larynx. Previous investigations have demonstrated the critical role of host genetic susceptibility in the progression of HNSCC. Despite the advances in our knowledge, the improved survival rate of HNSCC patients over the last 40 years has been limited. Failure to identify the molecular origins of development of HNSCC and the genetic basis of the disease and its biological heterogeneity impedes the development of new therapeutic methods. These results indicate a need to identify more genetic factors underlying this complex disease, which can be better used in early detection and prevention strategies. The lack of reliable animal models to investigate the underlying molecular processes is one of the most significant barriers to understanding HNSCC tumors. In this report, we explore and discuss potential research prospects utilizing the Collaborative Cross mouse model and crossing it to mice carrying single or double knockout genes (e.g. Smad4 and P53 genes) to identify genetic factors affecting the development of this complex disease using genome-wide association studies, epigenetics, microRNA, long noncoding RNA, lncRNA, histone modifications, methylation, phosphorylation, and proteomics.

Establishment of head and neck squamous cell carcinoma mouse models for cetuximab resistance and sensitivity

Aim: Acquired resistance to the targeted agent cetuximab poses a significant challenge in finding effective anti-cancer treatments for head and neck squamous cell carcinoma (HNSCC). To accurately study novel combination treatments, suitable preclinical mouse models for cetuximab resistance are key yet currently limited. This study aimed to optimize an acquired cetuximab-resistant mouse model, with preservation of the innate immunity, ensuring intact antibody-dependent cellular cytotoxicity (ADCC) functionality. Methods: Cetuximab-sensitive and acquired-resistant HNSCC cell lines, generated in vitro, were subcutaneously engrafted in Rag2 knock-out (KO), BALB/c Nude and CB17 Scid mice with/without Matrigel or Geltrex. Once tumor growth was established, mice were intraperitoneally injected twice a week with cetuximab for a maximum of 3 weeks. In addition, immunohistochemistry was used to evaluate the tumor and its microenvironment. Results: Despite several adjustments in cell number, cell lines and the addition of Matrigel, Rag2 KO and BALB/C Nude mice proved to be unsuitable for xenografting our HNSCC cell lines. Durable tumor growth of resistant SC263-R cells could be induced in CB17 Scid mice. However, these cells had lost their resistance phenotype in vivo. Immunohistochemistry revealed a high infiltration of macrophages in cetuximab-treated SC263-R tumors. FaDu-S and FaDu-R cells successfully engrafted into CB17 Scid mice and maintained their sensitivity/resistance to cetuximab. Conclusion: We have established in vivo HNSCC mouse models with intact ADCC functionality for cetuximab resistance and sensitivity using the FaDu-R and FaDu-S cell lines, respectively. These models serve as valuable tools for investigating cetuximab resistance mechanisms and exploring novel drug combination strategies.

Exploring animal models in oral cancer research and clinical intervention: A critical review

Cancer is a leading cause of death worldwide, but advances in treatment, early detection, and prevention have helped to reduce its impact. To translate cancer research findings into clinical interventions for patients, appropriate animal experimental models, particularly in oral cancer therapy, can be helpful. In vitro experiments using animal or human cells can provide insight into cancer's biochemical pathways. This review discusses the various animal models used in recent years for research and clinical intervention in oral cancer, along with their advantages and disadvantages. We highlight the advantages and limitations of the used animal models in oral cancer research and therapy by searching the terms of animal models, oral cancer, oral cancer therapy, oral cancer research, and animals to find all relevant publications during 2010-2023. Mouse models, widely used in cancer research, can help us understand protein and gene functions in vivo and molecular pathways more deeply. To induce cancer in rodents, xenografts are often used, but companion animals with spontaneous tumours are underutilized for rapid advancement in human and veterinary cancer treatments. Like humans with cancer, companion animals exhibit biological behaviour, treatment responses, and cytotoxic agent responses similar to humans. In companion animal models, disease progression is more rapid, and the animals have a shorter lifespan. Animal models allow researchers to study how immune cells interact with cancer cells and how they can be targeted specifically. Additionally, animal models have been extensively used in research on oral cancers, so researchers can use existing knowledge and tools to better understand oral cancers using animal models.

Preclinical models in head and neck squamous cell carcinoma

Head and neck cancer is the sixth most frequent cancer type. Drug resistance and toxicity are common challenges of the existing therapies, making the development of reliable preclinical models essential for the study of the involved molecular mechanisms as well as for eventual intervention approaches that improve the clinical outcome. Preclinical models of head and neck squamous cell carcinoma have been traditionally based on cell lines and murine models. In this review, we will go over the most frequently used preclinical models, from immortalised-cell and primary tumour cultures in monolayer or 3D, to the currently available animal models. We will scrutinise their efficiency in mimicking the molecular and cellular complexity of head and neck squamous cell carcinoma. Finally, the challenges and the opportunities of other envisaged putative approaches, as well as the potential of the preclinical models to further develop personalised therapies will be discussed.

Modelling cutaneous squamous cell carcinoma for laboratory research

Cutaneous squamous cell carcinoma (cSCC) leads to significant morbidity for patients with progression and metastases. However, the molecular underpinnings of these tumors are still poorly understood. Dissecting human cSCC pathogenesis amplifies the exigence for preclinical models that mimic invasion and nodal spread. This review discusses the currently available models, including two- and three-dimensional tissue cultures, syngeneic and transgenic mice, and cell line-derived and patient-derived xenografts. We further highlight studies that have utilized the different models, considering how they recapitulate specific hallmarks of cSCC. Finally, we discuss the advantages, limitations and future research directions.

Canine oral squamous cell carcinoma as a spontaneous, translational model for radiation and immunology research

Introduction

Improving outcomes for oral squamous cell carcinoma (OSCC) patients has been hindered by a lack of effective predictive animal models. Spontaneously occurring canine OSCC could help fill this gap. The objective of this study was to characterize the immune landscape of canine OSCC to advance understanding of how dogs could serve as a surrogate for human OSCC.

Methods/Results

Canine OSCC contains a heterogenous tumor immune microenvironment. CD3+ T cells were the predominant tumor infiltrating immune cell population; however, there was a wide range CD3+ T cell density across samples. The most common CD3+ T cell micro-anatomical distribution was defined as "pre-existing immunity", but the remaining 20% of tumors were characterized as "immunologically ignorant" or "excluded infiltrates" patterns. When compared to normal oral mucosa, the tumor gene expression pattern suggests that canine OSCC microenvironment is highly inflamed and characterized by the presence of an anti-tumor immune response dominated by cytotoxic\effector T cells and NK cells (CD8a, GZMA, OX40, and HLA-A); however, overexpression of genes associated with effector T cell exhaustion and microenvironmental immunosuppression was also identified (PD-1, LAG3, CXCL2). Correlations between CD3+ T cell density and immune gene expression revealed key genes associated with cytotoxic anti-tumor T cell responses (GZMA, GZMB, PRF1), co-stimulation of T cells (CD27, CD28, ICOS), and other immune processes, including Type I IFN response (TNF, TNFSF10), and T cell exhaustion (CTLA4, PD-1). CD3+ T cell density in canine OSCC was significantly correlated with a cytolytic activity score (mean PRF1 and GZMA expression), suggestive of active effector CD8 T cell function. CD204+ macrophages were the second most abundant tumor infiltrating immune cell, and when comparing to normal oral mucosa, two differently expressed genes linked to tumor associated macrophages and myeloid derived suppressor cells (MDSC) were identified: CXCL2, CD70. Overexpression of CXCL2 was also identified in canine OSCC "T cell-high" tumors compared to "T cell-low" tumors.

Discussion

This study identified actionable immunotherapy targets which could inform future comparative oncology trials in canine OSCC: CTLA-4, PD-1, CXCL2. These data provide a good first step towards utilizing spontaneous canine OSCC as a comparative model for human OSCC radiation and immuno-oncology research.

Mouse Models for Immune Checkpoint Blockade Therapeutic Research in Oral Cancer

The most prevalent oral cancer globally is oral squamous cell carcinoma (OSCC). The invasion of adjacent bones and the metastasis to regional lymph nodes often lead to poor prognoses and shortened survival times in patients with OSCC. Encouraging immunotherapeutic responses have been seen with immune checkpoint inhibitors (ICIs); however, these positive responses to monotherapy have been limited to a small subset of patients. Therefore, it is urgent that further investigations into optimizing immunotherapies are conducted. Areas of research include identifying novel immune checkpoints and targets and tailoring treatment programs to meet the needs of individual patients. Furthermore, the advancement of combination therapies against OSCC is also critical. Thus, additional studies are needed to ensure clinical trials are successful. Mice models are advantageous in immunotherapy research with several advantages, such as relatively low costs and high tumor growth success rate. This review paper divided methods for establishing OSCC mouse models into four categories: syngeneic tumor models, chemical carcinogen induction, genetically engineered mouse, and humanized mouse. Each method has advantages and disadvantages that influence its application in OSCC research. This review comprehensively surveys the literature and summarizes the current mouse models used in immunotherapy, their advantages and disadvantages, and details relating to the cell lines for oral cancer growth. This review aims to present evidence and considerations for choosing a suitable model establishment method to investigate the early diagnosis, clinical treatment, and related pathogenesis of OSCC.

Defining the Role of Immunotherapy in the Curative Treatment of Locoregionally Advanced Head and Neck Cancer: Promises, Challenges, and Opportunities

Recent advancements in the development of immunotherapies have raised the hope for patients with locally-advanced HNSCC (LA-HNSCC) to achieve improved oncologic outcomes without the heavy burden of treatment-related morbidity. While there are several ongoing late phase clinical trials that seek to determine whether immunotherapy can be effectively employed in the definitive setting, initial results from concurrent immuno-radiotherapy therapy trials have not shown strong evidence of benefit. Encouragingly, evidence from preclinical studies and early-phase neoadjuvant studies have begun to show potential pathways forward, with therapeutic combinations and sequences that intentionally spare tumor draining lymphatics in order to maximize the synergy between definitive local therapy and immunotherapy. The intent of this review is to summarize the scientific rationale and current clinical evidence for employing immunotherapy for LA-HNSCC as well as the ongoing efforts and challenges to determine how to optimally deliver and sequence immunotherapy alongside traditional therapeutics. In both the preclinical and clinical settings, we will discuss the application of immunotherapies to both surgical and radiotherapeutic management of HNSCC.

The Effect of Low-Dose Gamma Irradiation on the Uptake of Boronophenylalanine to Enhance the Efficacy of Boron Neutron Capture Therapy in an Orthotopic Oral Cancer Model

The success of boron neutron capture therapy (BNCT) mainly depends on the boron concentration in the tumor and a high tumor/normal tissue (T/N) boron ratio or a high tumor/blood (T/B) boron ratio. Therefore, the effective enhancement of boron ratios is the first priority. Our study investigated whether a low-dose of γ-radiation (LDR) could improve boron ratios and enhance the therapeutic effects of BNCT in an orthotopic human oral squamous cell carcinoma-bearing animal model. SAS/luc cells were used to establish the orthotopic tumor-bearing model. The pharmacokinetics of boronophenylalanine (BPA) administration with 400 mg/kg of body weight both alone and in combination with LDR (0.1 Gy) was evaluated, and BNCT was performed at the Tsing Hua Open-pool Reactor (THOR). The radiation doses were evaluated using a treatment planning system. Moreover, tumor growth and metastasis were monitored via bioluminescence imaging (BLI). The therapeutic effects after BNCT were evaluated using BLI, histopathological findings and the overall survival rate. LDR increased the BPA accumulation in tumors by 52.2%. T/N and T/B ratios were enhanced from 3.77 to 5.31 and from 3.47 to 4.46, respectively. Radiation dose was increased by 44.3%. Notably, tumor recurrence and cervical lymph node metastasis were observed in the BNCT group, which had a survival rate of 50%. Complete responses were found in the combined-treatment group, which had a survival rate of 100%. No toxicity was found according to the histopathological findings. Conclusively, LDR increased BPA accumulation in the tumor and the T/N and T/B ratios, resulting in BNCT efficacy improvement and the overall survival rate extension.

Insulin-Like Growth Factor Binding Protein-3 Exerts Its Anti-Metastatic Effect in Aerodigestive Tract Cancers by Disrupting the Protein Stability of Vimentin

Simple Summary

Local invasion and distal metastasis are the main causes of cancer-related death and the poor prognosis of patients with aerodigestive tract cancers. Therefore, understanding the biology of invasion and metastasis is important for the development of effective therapeutic strategies. The present study shows that insulin-like growth factor binding protein-3 (IGFBP-3) inhibits the migration and invasion of non-small cell lung cancer (NSCLC) and head and neck squamous cell carcinoma (HNSCC) cells in vitro and the development of metastasized tumors in vivo. Mechanistic studies suggest vimentin as a cellular target for the antimetastatic effect of IGFBP-3. These results contribute to a better understanding on the regulation of metastasis of cancer cells, providing the rationale to utilize IGFBP-3 as an effective therapeutic strategy targeting migration and metastasis of aerodigestive tract cancers.

Abstract

The proapoptotic, antiangiogenic, and antimetastatic activities of insulin-like growth factor binding protein-3 (IGFBP-3) through IGF-dependent or -independent mechanisms have been suggested in various types of human cancers. However, a mechanistic explanation of and downstream targets involved in the antimetastatic effect of IGFBP-3 is still lacking. In this study, by applying various in vitro and in vivo models, we show that IGFBP-3 suppresses migration and invasion of human head and neck squamous carcinoma (HNSCC) and non-small cell lung cancer (NSCLC) cells. Silencing IGFBP-3 expression elevated the migration and invasion of NSCLC and HNSCC cells in vitro and their local invasion and metastasis in vivo, whereas overexpression of IGFBP-3 decreased such prometastatic changes. Local invasion of 4-nitroquinoline-1-oxide (4-NQO)-induced HNSCC tumors was consistently significantly potentiated in Igfbp3 knockout mice compared with that in wild-type mice. Mechanistically, IGFBP-3 disrupted the protein stability of vimentin via direct binding and promoting its association with the E3 ligase FBXL14, causing proteasomal degradation. The C-terminal domain of IGFBP-3 and the head domain of vimentin are essential for their interaction. These results provide a molecular framework for IGFBP-3′s IGF-independent antimetastatic and antitumor activities.

Characterization and Differentiation of the Tumor Microenvironment (TME) of Orthotopic and Subcutaneously Grown Head and Neck Squamous Cell Carcinoma (HNSCC) in Immunocompetent Mice

For the development and evaluation of new head and neck squamous cell carcinoma (HNSCC) therapeutics, suitable, well-characterized animal models are needed. Thus, by analyzing orthotopic versus subcutaneous models of HNSCC in immunocompetent mice, we evaluated the existence of adenosine-related immunosuppressive B- and T lymphocyte populations within the tumor microenvironment (TME). Applying the SCC VII model for the induction of HNSCC in immunocompetent C3H/HeN mice, the cellular TME was characterized after tumor initiation over time by flow cytometry. The TME in orthotopic grown tumors revealed a larger population of tumor-infiltrating lymphocytes (TIL) with more B cells and CD4⁺ T cells than the subcutaneously grown tumors. Immune cell populations in the blood and bone marrow showed a rather distinct reaction toward tumor induction and tumor location compared to the spleen, lymph nodes, or thymus. In addition, large numbers of immunosuppressive B- and T cells were identified within the TME but also in secondary lymphoid organs, independently of the tumor initiation site. The altered immunogenic TME may influence the response to any treatment attempt. Moreover, when analyzing the TME and other lymphoid organs of tumor-bearing mice, we observed conditions reflecting largely those of patients suffering from HNSCC suggesting the C3H/HeN mouse model as a suitable tool for studies aiming to target immunosuppression to improve anti-cancer therapies.

The 4-NQO mouse model: An update on a well-established in vivo model of oral carcinogenesis

The early detection and management of oral premalignant lesions (OPMDs) improve their outcomes. Animal models that mimic histological and biological processes of human oral carcinogenesis may help to improve the identification of OPMD at-risk of progression into oral squamous cell carcinoma and to develop preventive strategies for the entire field of cancerization. No animal model is perfectly applicable for investigating human oral carcinogenesis. However, the 4-nitroquinoline 1-oxide (4-NQO) mouse model is well established and mimics several morphological, histological, genomic and molecular features of human oral carcinogenesis. Some of the reasons for the success of this model include its reproducible experimental conditions with limited variation, the possibility of realizing longitudinal studies with invasive intervention or gene manipulation, and sample availability for all stages of oral carcinogenesis, especially premalignant lesions. Moreover, the role of histological and molecular alterations in the field of cancerization (i.e., macroscopically healthy mucosa exposed to a carcinogen) during oral carcinogenesis can be easily explored using this model. In this review, we discuss the advantages and drawbacks of this model for studying human oral carcinogenesis. In summary, the 4-NQO-induced murine oral cancer model is relevant for investigating human oral carcinogenesis, including the immune microenvironment, and for evaluating therapeutic and chemoprevention agents.

Spontaneous and Induced Animal Models for Cancer Research

Considering the complexity of the current framework in oncology, the relevance of animal models in biomedical research is critical in light of the capacity to produce valuable data with clinical translation. The laboratory mouse is the most common animal model used in cancer research due to its high adaptation to different environments, genetic variability, and physiological similarities with humans. Beginning with spontaneous mutations arising in mice colonies that allow for pursuing studies of specific pathological conditions, this area of in vivo research has significantly evolved, now capable of generating humanized mice models encompassing the human immune system in biological correlation with human tumor xenografts. Moreover, the era of genetic engineering, especially of the hijacking CRISPR/Cas9 technique, offers powerful tools in designing and developing various mouse strains. Within this article, we will cover the principal mouse models used in oncology research, beginning with behavioral science of animals vs. humans, and continuing on with genetically engineered mice, microsurgical-induced cancer models, and avatar mouse models for personalized cancer therapy. Moreover, the area of spontaneous large animal models for cancer research will be briefly presented.

The antilymphatic metastatic effect of hyaluronic acid in a mouse model of oral squamous cell carcinoma

Objectives: Lymphatic metastasis is the main cause of low patient survival in cases of oral squamous cell carcinoma (OSCC). Several animal models have been established to uncover the mechanism that regulates lymph node metastasis of OSCC cells. Unfortunately, these models often take a long time to establish. The prolonged tumor burden can lead to animal cachexia, which may ultimately affect the experimental outcome. To overcome the disadvantages of these models, we established an orthotopic metastatic animal model of OSCC that showed quick lymph node metastasis potential.Results: DiR dye-labeled CAL27 cells were injected into tongue tissues of BALB/c nude mice, and the cells metastasized to lymph nodes on day 3. Metastasis was monitored using an in vivo imaging system and confirmed by histological observation. Using this model, we investigated the role of hyaluronic acid (HA) on the cervical metastasis of OSCC cells. Surprisingly, we found that the presence of HA significantly reduced the incidence of metastasis to cervical lymph nodes compared with the control group. Further analysis revealed that the presence of exogenous HA promoted mesenchymal-epithelial transition (MET) in primary tumors while reducing the metastatic potential of OSCC.Conclusion: Our findings confirmed the establishment of a fast and reliable lymphatic metastatic mouse model of OSCC that can be used for investigating metastatic mechanisms and analyzing various antimetastasis strategies. An equally important discovery is the antimetastatic property of HA, which could provide a potential therapeutic strategy for OSCC.

Mouse Tumor-Bearing Models as Preclinical Study Platforms for Oral Squamous Cell Carcinoma

Preclinical animal models of oral squamous cell carcinoma (OSCC) have been extensively studied in recent years. Investigating the pathogenesis and potential therapeutic strategies of OSCC is required to further progress in this field, and a suitable research animal model that reflects the intricacies of cancer biology is crucial. Of the animal models established for the study of cancers, mouse tumor-bearing models are among the most popular and widely deployed for their high fertility, low cost, and molecular and physiological similarity to humans, as well as the ease of rearing experimental mice. Currently, the different methods of establishing OSCC mouse models can be divided into three categories: chemical carcinogen-induced, transplanted and genetically engineered mouse models. Each of these methods has unique advantages and limitations, and the appropriate application of these techniques in OSCC research deserves our attention. Therefore, this review comprehensively investigates and summarizes the tumorigenesis mechanisms, characteristics, establishment methods, and current applications of OSCC mouse models in published papers. The objective of this review is to provide foundations and considerations for choosing suitable model establishment methods to study the relevant pathogenesis, early diagnosis, and clinical treatment of OSCC.

Oral Mucosal Organoids as a Potential Platform for Personalized Cancer Therapy

Previous studies have described that tumor organoids can capture the diversity of defined human carcinoma types. Here, we describe conditions for long-term culture of human mucosal organoids. Using this protocol, a panel of 31 head and neck squamous cell carcinoma (HNSCC)-derived organoid lines was established. This panel recapitulates genetic and molecular characteristics previously described for HNSCC. Organoids retain their tumorigenic potential upon xenotransplantation. We observe differential responses to a panel of drugs including cisplatin, carboplatin, cetuximab, and radiotherapy in vitro. Additionally, drug screens reveal selective sensitivity to targeted drugs that are not normally used in the treatment of patients with HNSCC. These observations may inspire a personalized approach to the management of HNSCC and expand the repertoire of HNSCC drugs. SIGNIFICANCE: This work describes the culture of organoids derived from HNSCC and corresponding normal epithelium. These tumoroids recapitulate the disease genetically, histologically, and functionally. In vitro drug screening of tumoroids reveals responses to therapies both currently used in the treatment of HNSCC and those not (yet) used in clinical practice.See related commentary by Hill and D'Andrea, p. 828.This article is highlighted in the In This Issue feature, p. 813.

A History of Innovations in the Diagnosis and Treatment of Oral and Head and Neck Cancer

Historical records as far back as 3000 BCE show that oral and head and neck cancer was a disease process well known to Egyptian physicians. Luminaries such as Hippocrates, Galen, Pott, and Virchow were instrumental in shaping our understanding of the etiology and pathogenesis of cancer. During the 20th century, evidence-based medicine catalyzed the development of rigorous science-based diagnostic and treatment protocols. The use of surgery, therapeutic radiation, and chemotherapy as single-treatment agents or in combination with one another gradually emerged as the preferred approach to cancer therapy. The recognition of tobacco, alcohol, and human papillomavirus as etiological agents in oral and head and neck cancer prompted the development of new diagnostic aids and treatment strategies to mitigate cancer progression. More in-depth mechanistic insights into the multistep process of oral and head and neck cancer were made possible by the use of the hamster buccal pouch and mouse models. New technologies, such as the sequencing of the human genome, metabolomics, and proteomics, have provided the foundation for what we today call precision medicine. The future success of tailored medical treatment for cancer patients will depend on the discovery of new druggable targets with improved therapeutic efficacy. As the precision and sensitivity of existing tools for prevention and risk assessment improve, greater accuracy will be achieved in predicting health outcomes.

Establishing of mouse oral carcinoma cell lines derived from transgenic mice and their use as syngeneic tumorigenesis models

Background

The survival of OSCC patient needs to be further improved. miR-211 is oncogenic in OSCC and its upregulation is associated with tumor progression and poor patient survival. K14-EGFP-miR-211 transgenic mice also exhibit augmented potential for OSCC induction.

Methods

Four murine OSCC cell lines, designated MOC-L1 to MOC-L4, are established from tongue tumors induced by 4-nitroquinoline 1-oxide using the K14-EGFP-miR-211 transgenic mouse model. The genetic disruption, in vitro oncogenicity, and the eligibilities of tumorigenesis and metastasis of the cell lines are analyzed.

Results

All cell lines show green fluorescence and express a range of epithelial markers. The MOC-L1, MOC-L2 and MOC-L3 cells carry missense mutations in the DNA binding domain of the p53 gene. MOC-L1 exhibits a high level of epithelial-mesenchymal transition and has the aggressive characteristics associated with this. MOC-L1 and MOC-L2 are clonogenic in vitro as well as being tumorigenic when implanted into the dermis or tongue of syngeneic recipients. Nonetheless, only MOC-L1 exhibits immense potential for local regional and distal metastasis. Since the expression of miR-196b in MOC-L1 xenografts is drastically decreased on cisplatin treatment, it would seem that targeting of miR-196b might facilitate tumor abrogation.

Conclusions

As cell lines established in this study originated from the C57BL/6 mouse, the strain most suitable for transgenic engineering, exploring the interplay of these OSCC cells with other genetically modified cells in immune-competent mice would provide important insights into OSCC pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5486-7) contains supplementary material, which is available to authorized users.

Immune-relevant aspects of murine models of head and neck cancer

Head and neck cancers (HNCs) cause significant mortality and morbidity. There have been few advances in therapeutic management of HNC in the past 4 to 5 decades, which support the need for studies focusing on HNC biology. In recent years, increased recognition of the relevance of the host response in cancer progression has led to novel therapeutic strategies and putative biomarkers of tumor aggressiveness. However, tumor-immune interactions are highly complex and vary with cancer type. Pre-clinical, in vivo models represent an important and necessary step in understanding biological processes involved in development, progression and treatment of HNC. Rodents (mice, rats, hamsters) are the most frequently used animal models in HNC research. The relevance and utility of information generated by studies in murine models is unquestionable, but it is also limited in application to tumor-immune interactions. In this review, we present information regarding the immune-specific characteristics of the murine models most commonly used in HNC research, including immunocompromised and immunocompetent animals. The particular characteristics of xenograft, chemically induced, syngeneic, transgenic, and humanized models are discussed in order to provide context and insight for researchers interested in the in vivo study of tumor-immune interactions in HNC.

Effect of serpinE1 overexpression on the primary tumor and lymph node, and lung metastases in head and neck squamous cell carcinoma

BACKGROUND

Serpin Family E Member 1 (SerpinE1) overexpression associates with poor clinical outcome in head and neck squamous cell carcinoma (HNSCC) patients. This study analyzed the role of serpinE1 in HNSCC dissemination.

METHODS

We studied the phenotypic characteristics and dissemination of HNSCC cells overexpressing serpinE1 using an orthotopic model and the association between serpinE1 overexpression and clinicopathological variables in patients included in The Cancer Genome Atlas database.

RESULTS

SerpinE1 overexpression increased proliferation, tumor budding, and the stromal component, while inhibiting apoptosis in primary tumors. It also enhanced the affectation and metastatic growth in lymph nodes, and the dispersion and growth of metastatic foci in the lung. High serpinE1 expression was associated with larger tumor size, undifferentiated tumors, lymph node metastasis, extracapsular spread, and the presence of perineural and angiolymphatic invasion.

CONCLUSION

SerpinE1 overexpression promotes tumor aggressiveness and metastatic dissemination to lymph nodes and lung consistently with its association with poor outcome in HNSCC patients.

Investigation of novel chemotherapeutics for feline oral squamous cell carcinoma

Feline oral squamous cell carcinomas (FOSCC) are highly aggressive neoplasms with short survival times despite multimodal treatment. FOSCC are similar to squamous cell carcinomas of the head and neck (SCCHN) in humans, which also present therapeutic challenges. The current study was undertaken to identify novel chemotherapeutics using FOSCC cell lines. A high throughput drug screen using 1,952 drugs was performed to identify chemotherapeutics for further investigation. Two of the drugs identified in the drug screen, actinomycin D and methotrexate, and two drugs with similar molecular targets to drugs found to be efficacious in the screening, dinaciclib and flavopiridol, were selected for further investigation. Drug inhibition profiles were generated for each drug and cell line using an MTS assay. In addition, the effects of the drugs of interest on cell cycle progression were analyzed via a propidium iodide DNA labeling assay. Changes in caspase-3/7 activity after treatment with each drug were also determined. The findings demonstrated effectiveness of the drugs at nanomolar concentrations with sensitivity varying across cell lines. With all of the drugs except for actinomycin D, evidence for G1 arrest was found. Dinaciclib and flavopiridol were demonstrated to induce apoptosis. The results of the study suggest that the selected drugs are potential candidates for developing novel chemotherapeutic approaches to FOSCC. Through these studies, novel therapeutic strategies for the treatment of FOSCC can be developed to provide better care for affected cats which can also serve as proof of concept studies to inform translational studies in SCCHN in humans.

Potent Antitumor Effects of a Combination of Three Nutraceutical Compounds

Head and neck squamous cell carcinoma (HNSCC) is associated with low survival, and the current aggressive therapies result in high morbidity. Nutraceuticals are dietary compounds with few side effects. However, limited antitumor efficacy has restricted their application for cancer therapy. Here, we examine combining nutraceuticals, establishing a combination therapy that is more potent than any singular component, and delineate the mechanism of action. Three formulations were tested: GZ17-S (combined plant extracts from Arum palaestinum, Peganum harmala and Curcuma longa); GZ17-05.00 (16 synthetic components of GZ17-S); and GZ17-6.02 (3 synthetic components of GZ17S; curcumin, harmine and isovanillin). We tested the formulations on HNSCC proliferation, migration, invasion, angiogenesis, macrophage viability and infiltration into the tumor and tumor apoptosis. GZ17-6.02, the most effective formulation, significantly reduced in vitro assessments of HNSCC progression. When combined with cisplatin, GZ17-6.02 enhanced anti-proliferative effects. Molecular signaling cascades inhibited by GZ17-6.02 include EGFR, ERK1/2, and AKT, and molecular docking analyses demonstrate GZ17-6.02 components bind at distinct binding sites. GZ17-6.02 significantly inhibited growth of HNSCC cell line, patient-derived xenografts, and murine syngeneic tumors in vivo (P < 0.001). We demonstrate GZ17-6.02 as a highly effective plant extract combination and pave the way for future clinical application in HNSCC.

Identification and characterization of a highly metastatic epithelial cancer cell line from rat tongue cancer

OBJECTIVES

Tongue squamous cell carcinoma (TSCC) is a clinically devastating disease. However, most established TSCC cell lines currently show undesirable malignant behaviours. The purpose of this study is to establish a highly metastatic TSCC cell line to serve as a useful tool for basic research.

MATERIALS AND METHODS

TSCCs were induced by 4-nitroquinoline-1-oxide (4NQO) in Sprague-Dawley rats. Tumor cells were obtained from the cancer tissues by primary culture and were then purified by an in vitro invasion assay and a limiting dilution assay. The growth rate, cell cycle distribution, apoptotic rate, tumorigenicity and distant metastatic phenotypes of the rat tongue cancer cells were fully investigated and characterized.

RESULTS

To date, the rat tongue cancer cell line, named Rca-T, has been continuously cultured in vitro for over 210 passages and exhibit a long spindle-shaped morphology, adherent growth, and a stable epithelial phenotype. The population doubling time of Rca-T cells is 23.35 h. Approximately 39.8% of these cells are in S phase, and the apoptosis rate of Rca-T cells is 7.46%. Furthermore, in immunodeficient nude mice, both the xenograft rate and the incidence of experimental lung metastasis are 100%. The in vitro assays further reveal the highly malignant and epithelial-mesenchymal transition-like properties of Rca-T cells.

CONCLUSION

In this study, the tumorigenic and highly distant metastatic TSCC cell line Rca-T was established. The malignant features of this cell line, especially its metastatic potential, will enable a wealth of functional studies on the molecular mechanisms of TSCC metastasis in the future.

Mouse Models for Studying Oral Cancer: Impact in the Era of Cancer Immunotherapy

Model systems for oral cancer research have progressed from tumor epithelial cell cultures to in vivo systems that mimic oral cancer genetics, pathological characteristics, and tumor-stroma interactions of oral cancer patients. In the era of cancer immunotherapy, it is imperative to use model systems to test oral cancer prevention and therapeutic interventions in the presence of an immune system and to discover mechanisms of stromal contributions to oral cancer carcinogenesis. Here, we review in vivo mouse model systems commonly used for studying oral cancer and discuss the impact these models are having in advancing basic mechanisms, chemoprevention, and therapeutic intervention of oral cancer while highlighting recent discoveries concerning the role of immune cells in oral cancer. Improvements to in vivo model systems that highly recapitulate human oral cancer hold the key to identifying features of oral cancer initiation, progression, and invasion as well as molecular and cellular targets for prevention, therapeutic response, and immunotherapy development.

Treatment with docetaxel in combination with Aneustat leads to potent inhibition of metastasis in a patient-derived xenograft model of advanced prostate cancer

Background:

Docetaxel used for first-line treatment of advanced prostate cancer (PCa) is only marginally effective. We previously showed, using the LTL-313H subrenal capsule patient-derived metastatic PCa xenograft model, that docetaxel combined with Aneustat (OMN54), a multivalent plant-derived therapeutic, led to marked synergistic tumour growth inhibition. Here, we investigated the effect of docetaxel+Aneustat on metastasis.

Methods:

C4-2 cells were incubated with docetaxel, Aneustat and docetaxel+Aneustat to assess effects on cell migration. The LTL-313H model, similarly treated, was analysed for effects on lung micro-metastasis and kidney invasion. The LTL-313H gene expression profile was compared with profiles of PCa patients (obtained from Oncomine) and subjected to IPA to determine involvement of cancer driver genes.

Results:

Docetaxel+Aneustat markedly inhibited C4-2 cell migration and LTL-313H lung micro-metastasis/kidney invasion. Oncomine analysis indicated that treatment with docetaxel+Aneustat was associated with improved patient outcome. The drug combination markedly downregulated expression of cancer driver genes such as FOXM1 (and FOXM1-target genes). FOXM1 overexpression reduced the anti-metastatic activity of docetaxel+Aneustat.

Conclusions:

Docetaxel+Aneustat can inhibit PCa tissue invasion and metastasis. This activity appears to be based on reduced expression of cancer driver genes such as FOXM1. Use of docetaxel+Aneustat may provide a new, more effective regimen for therapy of metastatic PCa.

MERTK as a novel therapeutic target in head and neck cancer

Although head and neck cancer (HNSCC) is the sixth most common tumor entity worldwide therapy options remain limited leading to 5-year survival rates of only 50 %. MERTK is a promising therapeutic target in several tumor entities, however, its role in HNSCC has not been described yet. The aim of our study was to investigate the biological significance of MERTK and to evaluate its potential as a novel therapeutic target in this dismal tumor entity. In two large HNSCC cohorts (n=537 and n=520) we found that MERTK is overexpressed in one third of patients. In-vitro, MERTK overexpression led to increased proliferation, migration and invasion whereas MERTK inhibition with the small molecule inhibitor UNC1062 or MERTK knockdown reduced cell motility via the small GTPase RhoA.

Taken together, we are the first to show that MERTK is frequently overexpressed in HNSCC and plays an important role in tumor cell motility. It might therefore be a potential target for selected patients suffering from this dismal tumor entity.

Preventive effect of celecoxib use against cancer progression and occurrence of oral squamous cell carcinoma

Overexpression of cyclooxygenase-2 in oral cancer increases lymph node metastasis and is associated with a poor prognosis. The potential of celecoxib (CXB) use is reported in cancer treatment by inhibiting proliferation through apoptosis, but the effects on the epithelial-mesenchymal transition (EMT) and cancer cell mobility remain unclear. We performed a preclinical study and population-based study to evaluate CXB use in the prevention of oral cancer progression and occurrence. The in-vitro findings showed that CXB is involved in the inhibition of EMT and cell mobility through blocking transcription factors (Slug, Snail and ZEB1), cytoplasmic mediators (focal adhesion kinase (FAK), vimentin and β-catenin), cell adhesion molecules (cadherins and integrins), and surface receptors (AMFR and EGFR). The murine xenograft model showed a 65% inhibition in tumour growth after a 5-week treatment of CXB compared to placebo. Xenograft tumours in placebo-treated mice displayed a well-to-moderate/moderate differentiated SCC grade, while those from CXB-treated mice were well differentiated. The expression levels of membrane EGFR, and nuclear FAK, Slug and ZEB1 were decreased in the xenograft tumours of CXB-treated mice. A retrospective cohort study showed that increasing the daily dose and medication time of CXB was associated with oral cancer prevention. The findings provide an alternative prevention strategy for oral cancer development with CXB use.

Preclinical models in HNSCC: A comprehensive review

Head and neck cancer remains a significant public health concern. About 60% of patients die within 5years due to local recurrence. Head and neck squamous cell carcinoma (HNSCC) cell lines are important preclinical models in the search for new therapies against this disease. Furthermore, there is a need to test novel drugs before introduction into clinical practice. A preclinical model that closely resembles the in vivo situation would be highly valuable. In the last few decades, a multicellular spheroid model has gained attention as its behavior was comparable to in vivo tumors. Basic research is necessary to achieve an understanding of the normal and pathological state but cannot, in itself, provide sufficient information for clinical applications. Indeed, animal models are an inevitable prelude to assess the efficacy of new therapeutic approaches in HNSCC. The present review proposes an overview of HNSCC pre-clinical models in order to further understand the oncogenic properties for HNSCC and translate these findings into clinic for patients.

Immunocompromised and immunocompetent mouse models for head and neck squamous cell carcinoma

Mouse models can closely mimic human oral squamous epithelial carcinogenesis, greatly expand the in vivo research possibilities, and play a critical role in the development of diagnosis, monitoring, and treatment of head and neck squamous cell carcinoma. With the development of the recent research on the contribution of immunity/inflammation to cancer initiation and progression, mouse models have been divided into two categories, namely, immunocompromised and immunocompetent mouse models. And thus, this paper will review these two kinds of models applied in head and neck squamous cell carcinoma to provide a platform to understand the complicated histological, molecular, and genetic changes of oral squamous epithelial tumorigenesis.

Animal models of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the most common oral cancer worldwide. Local bone invasion into the maxilla or mandible and metastasis to regional lymph nodes often result in a poor prognosis, decreased quality of life and shortened survival time for HNSCC patients. Poor response to treatment and clinical outcomes are the major concerns in this aggressive cancer. Multiple animal models have been developed to replicate spontaneous HNSCC and investigate genetic alterations and novel therapeutic targets. This review provides an overview of HNSCC as well as the traditional animal models used in HNSCC preclinical research. The value and challenges of each in vivo model are discussed. Similarity between HNSCC in humans and cats and the possibility of using spontaneous feline oral squamous cell carcinoma (FOSCC) as a model for HNSCC in translational research are highlighted.

Mammalian models of chemically induced primary malignancies exploitable for imaging-based preclinical theragnostic research

Compared with transplanted tumor models or genetically engineered cancer models, chemically induced primary malignancies in experimental animals can mimic the clinical cancer progress from the early stage on. Cancer caused by chemical carcinogens generally develops through three phases namely initiation, promotion and progression. Based on different mechanisms, chemical carcinogens can be divided into genotoxic and non-genotoxic ones, or complete and incomplete ones, usually with an organ-specific property. Chemical carcinogens can be classified upon their origins such as environmental pollutants, cooked meat derived carcinogens, N-nitroso compounds, food additives, antineoplastic agents, naturally occurring substances and synthetic carcinogens, etc. Carcinogen-induced models of primary cancers can be used to evaluate the diagnostic/therapeutic effects of candidate drugs, investigate the biological influential factors, explore preventive measures for carcinogenicity, and better understand molecular mechanisms involved in tumor initiation, promotion and progression. Among commonly adopted cancer models, chemically induced primary malignancies in mammals have several advantages including the easy procedures, fruitful tumor generation and high analogy to clinical human primary cancers. However, in addition to the time-consuming process, the major drawback of chemical carcinogenesis for translational research is the difficulty in noninvasive tumor burden assessment in small animals. Like human cancers, tumors occur unpredictably also among animals in terms of timing, location and the number of lesions. Thanks to the availability of magnetic resonance imaging (MRI) with various advantages such as ionizing-free scanning, superb soft tissue contrast, multi-parametric information, and utility of diverse contrast agents, now a workable solution to this bottleneck problem is to apply MRI for noninvasive detection, diagnosis and therapeutic monitoring on those otherwise uncontrollable animal models with primary cancers. Moreover, it is foreseeable that the combined use of chemically induced primary cancer models and molecular imaging techniques may help to develop new anticancer diagnostics and therapeutics.

Animal Models of Bone Metastasis

Bone is one of the most common sites of cancer metastasis in humans and is a significant source of morbidity and mortality. Bone metastases are considered incurable and result in pain, pathologic fracture, and decreased quality of life. Animal models of skeletal metastases are essential to improve the understanding of the molecular pathways of cancer metastasis and growth in bone and to develop new therapies to inhibit and prevent bone metastases. The ideal animal model should be clinically relevant, reproducible, and representative of human disease. Currently, an ideal model does not exist; however, understanding the strengths and weaknesses of the available models will lead to proper study design and successful cancer research. This review provides an overview of the current in vivo animal models used in the study of skeletal metastases or local tumor invasion into bone and focuses on mammary and prostate cancer, lymphoma, multiple myeloma, head and neck squamous cell carcinoma, and miscellaneous tumors that metastasize to bone.

Systemic toxic effects during early phases of topical 4-NQO-induced oral carcinogenesis in rats

BACKGROUND

Most studies have demonstrated 4-NQO toxicity to oral epithelium during oral carcinogenesis induction, but systemic toxicity has been poorly addressed. The aim of this study was to describe the systemic effect of 4-NQO topical application during early phases of oral cancer induction.

METHODS

A 4-NQO propylene glycol ointment was topically applied on the rat tongue three times a week for 16 weeks. Local and systemic 4-NQO toxicity was evaluated by body weight gain, hematology, and serum chemistry analyses, histopathology, and proliferating cell nuclear antigen (PCNA) immunohistochemistry.

RESULTS

Significant reduction in body weight gain and in white blood cell count as well as significant increase in serum ALT and AST was observed after 16 weeks of 4-NQO topical application. Focal hepatic lobular necrosis, renal tubular degeneration, and decreased cellularity in the splenic white pulp were also detected.

CONCLUSIONS

4-NQO topical application on the tongue of rats for 16 weeks seems to have caused hepatic, renal, and splenic toxicity. Potential systemic toxicity should be considered to monitor for variables that could interfere in topical oral carcinogenesis experiments.

An animal explant model for the study of human cutaneous squamous cell carcinoma

We established a human tissue explant model to facilitate study of cutaneous squamous cell carcinoma. We accomplished this by implanting debulked SCC, from surgical discard, into nude rats. Human SCC remained viable and continued to proliferate for at least 4 weeks and showed evidence of neovascularization. At 4 weeks, SCC implants showed a trend toward increased PCNA positive cells compared to fresh SCC cells/mm(2) tissue) supporting continued proliferation throughout engraftment. Von Willebrand's Factor (VWF) positive cells were found within implants and likely represented rat vessel neovascularization. Human Langerhans' (Langerin+) cells, but no T cells (CD3+, CD8+, FoxP3+), macrophages (CD163), or NK cells (NKp46), were present in SCC implants at 4 weeks. These findings support the possibility that LCs fail to migrate from cutaneous SCC and thus contribute to lack of effective antitumor response. Our findings also provide a novel model system for further study of primary cutaneous SCC.

Tumor grafts derived from patients with head and neck squamous carcinoma authentically maintain the molecular and histologic characteristics of human cancers

BACKGROUND

The patient-derived xenograft (PDX) model is likely to reflect human tumor biology more accurately than cultured cell lines because human tumors are implanted directly into animals; maintained in an in vivo, three-dimensional environment; and never cultured on plastic. PDX models of head and neck squamous cell carcinoma (HNSCC) have been developed previously but were not well characterized at the molecular level. HNSCC is a deadly and disfiguring disease for which better systemic therapy is desperately needed. The development of new therapies and the understanding of HNSCC biology both depend upon clinically relevant animal models. We developed and characterized the patient-derived xenograft (PDX) model because it is likely to recapitulate human tumor biology.

METHODS

We transplanted 30 primary tumors directly into mice. The histology and stromal components were analyzed by immunohistochemistry. Gene expression analysis was conducted on patient tumors and on PDXs and cell lines derived from one PDX and from independent, human tumors.

RESULTS

Five of 30 (17%) transplanted tumors could be serially passaged. Engraftment was more frequent among HNSCC with poor differentiation and nodal disease. The tumors maintained the histologic characteristics of the parent tumor, although human stromal components were lost upon engraftment. The degree of difference in gene expression between the PDX and its parent tumor varied widely but was stable up to the tenth generation in one PDX. For genes whose expression differed between parent tumors and cell lines in culture, the PDX expression pattern was very similar to that of the parent tumor. There were also significant expression differences between the human tumors that subsequently grew in mice and those that did not, suggesting that this model enriches for cancers with distinct biological features. The PDX model was used successfully to test targeted drugs in vivo.

CONCLUSION

The PDX model for HNSCC is feasible, recapitulates the histology of the original tumor, and generates stable gene expression patterns. Gene expression patterns and histology suggested that the PDX more closely recapitulated the parental tumor than did cells in culture. Thus, the PDX is a robust model in which to evaluate tumor biology and novel therapeutics.

Evaluation of hypoxia in a feline model of head and neck cancer using ⁶⁴Cu-ATSM positron emission tomography/computed tomography

Background

Human and feline head and neck squamous cell carcinoma (HNSCC) share histology, certain molecular features, as well as locally aggressive and highly recurrent clinical behavior. In human HNSCC, the presence of significant hypoxia within these tumors is considered an important factor in the development of a more aggressive phenotype and poor response to therapy. We hypothesized that feline head and neck tumors, particularly HNSCC, would exhibit hypoxia and that ⁶⁴Cu-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) positron emission tomography/computed tomography (PET/CT) would permit detection of intratumoral hypoxia.

Methods

12 cats with measureable head and neck tumors were given ⁶⁴Cu-ATSM and iodinated contrast for PET/CT scan. The presence or absence of hypoxia was also assessed using an intratumoral fluorescent life-time probe to quantitate pO₂ and pimonidazole immunohistochemical staining in biopsy specimens. In two cats, intratumoral O₂ and ⁶⁴Cu-ATSM uptake was measured before and after treatment with anti-angiogenic agents to determine the effect of these agents on hypoxia.

Results

Eleven of twelve feline tumors demonstrated significant ⁶⁴Cu-ATSM uptake, regardless of malignant or benign etiology. The presence (and absence) of hypoxia was confirmed using the fluorescent O₂ detection probe in nine tumors, and using pimonidazole staining in three tumors. Squamous cell carcinomas (HNSCC) demonstrated the highest degree of hypoxia, with T_max/M ratios ranging from 4.3 to 21.8. Additional non-neoplastic tissues exhibited ⁶⁴Cu-ATSM uptake suggestive of hypoxia including reactive draining lymph nodes, non-malignant thyroid pathology, a tooth root abscess, and otitis media. In two cats with HNSCC that received anti-vascular agents, the pattern of ⁶⁴Cu-ATSM uptake was altered after treatment, demonstrating the potential of the feline model to study the modulation of tumor oxygenation.

Conclusion

Feline HNSCC serves as a clinically relevant model for the investigation of intratumoral hypoxia including its measurement, modulation and targeting.

Opposing function of MYBBP1A in proliferation and migration of head and neck squamous cell carcinoma cells

Background

Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent and lethal cancers worldwide and mortality mostly results from loco-regional recurrence and metastasis. Despite its significance, our knowledge on molecular, cellular and environmental mechanisms that drive disease pathogenesis remains largely elusive, and there are limited therapeutic options, with only negligible clinical benefit.

Methods

We applied global gene expression profiling with samples derived from a recently established mouse model for oral cancer recurrence and identified a list of genes with differential expression between primary and recurrent tumors.

Results

One differentially expressed gene codes for Myb-binding protein 1a (MYBBP1A), which is known as a transcriptional co-regulator that physically interacts with nuclear transcription factors, such as NFκB and p53. We confirmed significantly reduced MYBBP1A protein levels on tissue sections of recurrent mouse tumors compared to primary tumors by immunohistochemistry, and found aberrant MYBBP1A protein levels also in tumor samples of HNSCC patients. Interestingly, silencing of MYBBP1A expression in murine SCC7 and in human HNSCC cell lines elicited increased migration but decreased cell growth.

Conclusion

We provide experimental evidence that MYBBP1A is an important molecular switch in the regulation of tumor cell proliferation versus migration in HNSCC and it will be a major challenge for the future to proof the concept whether regulation MYBBP1A expression and/or function could serve as a novel option for anti-cancer therapy.

Characterization of bone resorption in novel in vitro and in vivo models of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most commonly diagnosed oral malignancy in humans and cats and frequently invades bone. The objective of this study was to determine if feline OSCC serves as a relevant model of human OSCC in terms of osteolytic behavior and expression of bone resorption agonists. Novel feline OSCC cell lines (SCCF2 and SCCF3) were derived from spontaneous carcinomas. Gene expression and osteolytic behavior were compared to an established feline OSCC cell line (SCCF1) and three human OSCC cell lines (UMSCC-12, A253 and SCC25). Interaction of OSCC with bone and murine pre-osteoblasts (MC3T3) was investigated using in vitro co-culture techniques. In vivo bioluminescent imaging, Faxitron radiography and microscopy were used to measure xenograft growth and bone invasion in nude mice. Human and feline OSCC expressing the highest levels of parathyroid hormone-related protein (PTHrP) were associated with in vitro and in vivo bone resorption and osteoclastogenesis. MC3T3 cells had increased receptor activator of nuclear factor κB ligand (RANKL) expression and reduced osteoprotegerin (OPG) expression in conditioned medium from bone-invasive SCCF2 cells compared to minimally bone invasive SCCF3 cells, which was partially reversed with a neutralizing anti-PTHrP antibody. Human and feline OSCC cells cultured in bone-conditioned medium had increased PTHrP secretion and proliferation. Feline OSCC-induced bone resorption was associated with tumor cell secretion of PTHrP and with increased RANKL:OPG expression ratio in mouse preosteoblasts. Bone-CM increased OSCC proliferation and secretion of PTHrP. The preclinical models of feline OSCC recapitulated the bone-invasive phenotype characteristic of spontaneous OSCC and will be useful to future preclinical and mechanistic studies of bone invasive behavior.

Biological characteristics of a cell subpopulation in tongue squamous cell carcinoma

OBJECTIVES

To isolate the CD133+CD44+ cells from human tongue squamous cell carcinoma (TSCC) Tca8113 cell line and investigate biological characteristics of them.

MATERIALS AND METHODS

Immunomagnetic microbeads were applied to sort the CD133+CD44+ cells. Flow cytometry was used to detect isolation purity. The proliferation, clone-formation efficiencies, invasion and migration, gene expressions, and tumor-formation abilities were analyzed among CD133+CD44+, CD133-CD44-, and total population of cells.

RESULTS

The average purities of CD133+ and CD44+ cells reached 97.3% and 98.7%, respectively. The proliferation of CD133+CD44+ cells was significantly higher than the other two groups. The clone-forming efficiency of three groups was 70%, 8%, and 14%, respectively. The average invaded and migrated cell numbers of CD133+CD44+ and total population cells were 132 and 36.2, 311.6, and 156.2, respectively. The expressions of Bcl-2 and Sox2 in CD133+CD44+ cells were significantly higher than those in total population cells. A total of 10(4) CD133+CD44+ cells could form secondary tumors in nude mice, while the total population group needed 10(6) cells.

CONCLUSIONS

The CD133+CD44+ subpopulation cells possess stem-like characteristics. They appear to be the potential targets for future biology therapy of human TSCC.

Selective M3 muscarinic receptor antagonist inhibits small-cell lung carcinoma growth in a mouse orthotopic xenograft model

In small cell lung carcinoma (SCLC), acetylcholine (ACh) is synthesized and secreted, and it acts as an autocrine growth factor through activation of its receptors, muscarinic receptor (mAChR) and nicotinic receptor (nAChR). Alteration of tumor growth by blockade of M(3) mAChR in a human SCLC cell line, NCI-H82, was investigated in the present study. We used a highly selective M(3) muscarinic antagonist, N-(2-[3-([3R]-1-(cyclohexylmethyl)-3-piperidinyl]methylamino)-3-oxopropyl]amino-2-oxoethyl)-3,3,3-triphenyl-propioamide (J-115311). Our results show that J-115311 inhibited the increased intracellular calcium elicited by carbachol, a muscarinic agonist, in SCLC cells. J-115311 also inhibited SCLC cell growth in vitro. In a mouse orthotopic xenograft model, J-115311 dose-dependently reduced tumor growth when NCI-H82 cells were inoculated into the upper left lobe of the lung. These findings indicate that blockade of M(3) mAChR can suppress tumor growth in SCLC, suggesting the potential therapeutic utility of M(3) muscarinic antagonists as anti-cancer agents.

Establishment and characterization of a rabbit oral squamous cell carcinoma cell line as a model for in vivo studies

The incidence of oral squamous cell carcinoma (SCC) is increasing but the long-term survival rate remains low. An animal model would therefore be helpful for evaluation of new treatment modalities for oral SCC. Hamster is small animal, therefore, the cancer of hamster cheek pouch is not optimal for tumor imaging. The VX2 cell line has been used in many carcinoma-related studies, including oral SCC research, but it is derived from cutaneous tissue and not mucosa. We chemically induced tongue squamous cell carcinoma in rabbits and subsequently established a rabbit squamous cell line. The cells grew in multiple layers without contact inhibition for 60 passages over 2 years and were positive for cytokeratin (CK). Electron microscopy revealed that cells were polygonal with rich microvilli on the surface, and there were desmosomes between cells and bundles of tonofibril beside the cell membrane. The chromosome number ranged from 71 to 272, with a modal value of 145 (12.4%). The cells were transplantable into nude mice subcutaneously or rabbit submucosally and produced carcinomas in all the animals. The cell line should be a useful tool for the study of the biological characteristics of oral SCC, especially tongue SCC.

TGF-β inhibits metastasis in late stage human squamous cell carcinoma of the skin by a mechanism that does not involve Id1

It is now generally accepted that TGF-β acts as a pro-metastatic factor in advanced human breast cancer. However, it is well documented, that TGF-β is context dependent, and whether the TGF-β pathway switches to promote metastasis during the progression of squamous cell carcinoma (SCC) is unknown. This study examined the role of TGF-β signalling in SCC using a series of genetically related keratinocyte cell lines representing later stages of the disease, stably transduced with a dominant negative TβRII cDNA (dnTβRII). We demonstrated that clones expressing dnTβRII lost their growth inhibitory response to TGF-βin vitro, while ligand expression remained unchanged. Following transplantation of transduced cells to athymic mice in vivo, we showed that attenuation of the TGF-β signal resulted in a loss of differentiation and increased metastasis. In human tissue samples loss of TGF-β signal transduction as measured by pSmad2 activity also correlated with a loss of differentiation. Id1, previously shown to be down regulated by TGF-β, an inhibitor of differentiation and associated with metastasis, was weakly expressed in focal areas of a small number of human tumours but expression did not correlate with low levels of pSmad2. Our data demonstrate that TGF-β does not switch to promote metastasis in late stage human SCC of the skin and that inhibition of TGF-β signalling results in a loss of differentiation and increased metastasis in the later stages of this disease.

Establishment of a highly metastatic tongue squamous cell carcinoma cell line from New Zealand White rabbit

OBJECTIVE

Prior to this study, the widely used tongue squamous cell carcinoma cell lines could only initiate tumours in immunodeficient mice, which greatly delayed studies on immune function during carcinogenesis. This study established a new tongue squamous cell carcinoma cell line named 'RSCC-1', which can initiate tumours in both immunocompetent rabbits and immunodeficient nude mice and has high metastatic ability.

DESIGN

Primary tongue cancer was induced by DMBA and local mechanical stimulation in New Zealand White rabbits. The induced cancer was serially transplanted into homogeneous rabbits to establish transplanted models. At the same time, cancer samples were collected, cultured and passaged in vitro. Finally, a cell line named 'RSCC-1' was established. Its growth behaviour, cell cycle distribution and tumourigenicity in rabbits and nude mice were investigated.

RESULTS

RSCC-1 cells were cultured continuously in vitro for 19 months (165 passages). They contain between 54 and 196 chromosomes, with a modal number of 75. Tumourigenicity rates were 100% in both homogeneous rabbits and nude mice, with 20% lung metastasis and 50% cervical lymph node metastasis in homogeneous rabbits.

CONCLUSION

RSCC-1 is a poorly differentiated, highly malignant rabbit tongue squamous cell carcinoma cell line. Its behaviour in the inoculated animal model closely resembles human tongue cancer, and could metastasize to local lymph nodes and remote organs.

Study of feline oral squamous cell carcinoma: potential target for cyclooxygenase inhibitor treatment

Oral squamous cell carcinoma (OSCC) is associated with high morbidity and mortality. A potential target for OSCC treatment is cyclooxygenase-2 (cox-2). Pet cats with naturally occurring OSCC may offer the opportunity to study anticancer activity of cox inhibitors. Cox-2 expression in feline OSCC was determined by immunohistochemistry. High intensity cox-2 immunoreactivity was detected in 6 of 34 (18%) feline OSCC samples. Weak immunoreactivity was noted in 22 OSCCs and in epithelial cells from oral mucosa of clinically normal cats. Pharmacokinetics of a cox inhibitor (piroxicam, 0.3 mg/kg) were studied in carcinoma-bearing cats to confirm a dose for follow-up trials. The average peak serum piroxicam concentration (948 ng/ml, which inhibited cox-2 activity) and serum half-life (15.9 h) were similar to that in normal cats. These results provide information (cox-2 expression as an inclusion criteria, 0.3 mg/kg daily piroxicam) for the design of follow-up trials of cox inhibitor treatment in pet cats with OSCC.

Age dependent and cellular origin (stem versus progenitor) of a selected group of spontaneous brain tumors in humans

The origin of spontaneous human brain tumors has been recently debated as originating from a stem rather than a progenitor cell. Based on the statistical distribution of a selected group of primary brain tumors, and on the clonality and field theory for cancer growth, we propose as plausible the contribution of progenitor cells in the origin of the most common brain tumors such as, pediatric, mixed (glial and neuronal), and the aggressive glioblastoma multiforme in adults. Operationally, stem cell is defined as having a renewal probability of p=1, a progenitor 0<p<1, and a terminally differentiated cell as p=0. The space-time field location (microenvironment, cell-cell interactions...) and mitotic potential of a cell limits the distinguishability between stem and progenitors, due to the interconvertibility of these states via the process of retrodifferentiation (dedifferentiation). If excessively iterated retrodifferentiation of a mitotically competent cell prompts such a cell to organize programs that are atypical vis-à-vis the standard ones. Regarding specifically malignant cells, aperiodic cycles of dedifferentiation favour emergence of subclonal populations whose anachronistic evolution might become idiosyncratically resistant to therapies previously efficient against the initial tumoral mass. Unfortunately the "ab initio" identification of such subclonal "drifters" is impaired by systematic uncertainties as quali-quantified in appendix.