Development of a new invasion and metastasis model of human oral squamous cell carcinomas

CXCR7 promotes migration and invasion in head and neck squamous cell carcinoma by upregulating TGF-β1/Smad2/3 signaling

The chemokine receptor CXCR7 has been suggested to play important roles in the progression of several types of cancers. However, few studies have investigated the biological roles of CXCR7 in head and neck squamous cell carcinoma (HNSCC). CXCR7 expression and its clinical implications were examined in 103 HNSCC tissues using immunohistochemistry (IHC). The biological roles and mechanisms of CXCR7-mediated signaling pathways were investigated in HNSCC cells through CXCR7 overexpression in vitro and in vivo. High expression of CXCR7 was significantly associated with tumor size (P = 0.007), lymph node metastasis (P = 0.004), and stage (P = 0.020) in HNSCC. Overexpression of CXCR7 in HNSCC cells enhanced cell migration and invasion in vitro and promoted lymph node metastasis in vivo. CXCR7 also induced epithelial-mesenchymal transition through PI3K/AKT. CXCR7 increased secretion of transforming growth factor-β1 (TGF-β1) and promoted EMT through phosphorylated Smad2/3. Taken together, our results provide functional and mechanistic roles of CXCR7 as a master regulator of oncogenic TGF-β1/Smad2/3 signaling in HNSCC, suggesting that CXCR7 might be a therapeutic target for the treatment of HNSCC.

Determination of the origin of oral squamous cell carcinoma by microarray analysis: Squamous epithelium or minor salivary gland?

More than 90% of oral cancers are histopathologically squamous cell carcinomas (SCCs). According to clinical behavior and histopathological features, we hypothesize that oral SCC can originate from either oral squamous epithelium or minor salivary glands. Here, we examined whether some oral SCCs originate from minor salivary glands, and investigated whether these tumors show particularly aggressive biological behavior. The mRNA expression profiles of samples obtained from six patients with oral floor SCC (five men, one woman; mean age, 62.7 years) were analyzed using a microarray containing 32,878 probes. The six samples were divided into two groups by clustering of expression levels of 845 probes differentially expressed in normal oral squamous epithelium and normal salivary glands. The expression profile in four cases was similar to that of normal oral squamous epithelium, and in two cases was similar to that of normal salivary glands. Furthermore, we identified nine genes that reveal the origin of the oral SCC. Subsequently, we examined the expression levels of these nine marker genes by reverse transcriptase‐polymerase chain reaction to determine the origin of 66 oral SCCs. Twelve of the 66 oral SCCs were considered to originate from minor salivary glands, and these tumors showed high metastatic potential (p = 0.044, Chi‐square test). Furthermore, SCC derived from minor salivary glands showed a poor event‐free survival rate (p = 0.017, Kaplan–Meier analysis). In conclusion, determination of the origin of oral SCC is helpful in planning treatment for patients with oral SCC.

What's new?

In spite of several past attempts, no distinct factors controlling the biological aggressiveness of oral squamous cell carcinoma (SCC) have been identified. Determining the origin of the cancer cells could help predict biological aggressiveness, however. Here, the authors provide evidence that oral SCC has two different origins, as mucosal or salivary SCC. Furthermore, they identify nine genes able to reveal the origin of oral SCC. Based on their expression levels, the authors determined that twelve of the 66 oral SCCs in their sample originated from minor salivary glands. Salivary SCC tumors showed high metastatic potential and poor event‐free survival rate.

ISDoT: in situ decellularization of tissues for high-resolution imaging and proteomic analysis of native extracellular matrix

The extracellular matrix (ECM) is a master regulator of cellular phenotype and behavior. It has a crucial role in both normal tissue homeostasis and disease pathology. Here we present a fast and efficient approach to enhance the study of ECM composition and structure. Termed in situ decellularization of tissues (ISDoT), it allows whole organs to be decellularized, leaving native ECM architecture intact. These three-dimensional decellularized tissues can be studied using high-resolution fluorescence and second harmonic imaging, and can be used for quantitative proteomic interrogation of the ECM. Our method is superior to other methods tested in its ability to preserve the structural integrity of the ECM, facilitate high-resolution imaging and quantitatively detect ECM proteins. In particular, we performed high-resolution sub-micron imaging of matrix topography in normal tissue and over the course of primary tumor development and progression to metastasis in mice, providing the first detailed imaging of the metastatic niche. These data show that cancer-driven ECM remodeling is organ specific, and that it is accompanied by comprehensive changes in ECM composition and topological structure. We also describe differing patterns of basement-membrane organization surrounding different types of blood vessels in healthy and diseased tissues. The ISDoT procedure allows for the study of native ECM structure under normal and pathological conditions in unprecedented detail.

Regulation of PD-L1 expression in a high-grade invasive human oral squamous cell carcinoma microenvironment

Blockade of the programmed-death 1 receptor (PD-1)/programmed-death ligand (PD-L1) pathway efficiently reduces tumour growth and improves survival. Durable tumour regression with blockade of the PD-1/PD-L1 checkpoint has been demonstrated in recent clinical studies. Oral squamous cell carcinoma (OSCC) is highly immunosuppressive, and PD-L1 expression has been proposed as a potential mechanism responsible for this phenotype. Despite the fact that anti-PD-1 treatment can produce durable responses, such therapy appears to benefit only a subset of patients. Thus, it is important to understand the mechanisms underlying regulation of PD-L1 expression in the OSCC microenvironment. In this study, we showed that PD-L1 expression in high-grade invasive OSCC cell lines was lower than that in a low-grade invasive OSCC line and found a close correlation between PD-L1 expression and the epithelial-mesenchymal transition (EMT). PD-L1 expression was upregulated in macrophages and dendritic cells (DCs) in high-grade invasive human OSCC tissues or co-cultured with mesenchymal-phenotype OSCC cells in vitro. TLR4-inhibitory peptide successfully suppressed PD-L1 upregulation on macrophages and DCs co-cultured with mesenchymal-phenotype OSCC cells, suggesting that some EMT-induced tumour antigen is critical for PD-L1 induction on tumour-associated macrophages and DCs. Further studies are necessary to explore the impact of EMT on the tumour immune microenvironment and to identify potential biomarkers for selecting patients who might preferentially benefit from PD-1/PD-L1 blockade or immunotherapies more broadly.

Insulin-like growth factor-independent insulin-like growth factor binding protein 3 promotes cell migration and lymph node metastasis of oral squamous cell carcinoma cells by requirement of integrin β1

Frequent metastasis to the cervical lymph nodes leads to poor survival of patients with oral squamous cell carcinoma (OSCC). To understand the underlying mechanisms of lymph node metastasis, two sublines were successfully isolated from cervical lymph nodes of nude mice through in vivo selection, and identified as originating from poorly metastatic parental cells. These two sublines specifically metastasized to cervical lymph nodes in 83% of mice, whereas OEC-M1 cells did not metastasize after injection into the oral cavity. After gene expression analysis, we identified insulin-like growth factor binding protein 3 (IGFBP3) as one of the significantly up-regulated genes in the sublines in comparison with their parental cells. Consistently, meta-analysis of the public microarray datasets and IGFBP3 immunohistochemical analysis revealed increased both levels of IGFBP3 mRNA and protein in human OSCC tissues when compared to normal oral or adjacent nontumorous tissues. Interestingly, the up-regulated IGFBP3 mRNA expression was significantly associated with OSCC patients with lymph node metastasis. IGFBP3 knockdown in the sublines impaired and ectopic IGFBP3 expression in the parental cells promoted migration, transendothelial migration and lymph node metastasis of orthotopic transplantation. Additionally, ectopic expression of IGFBP3 with an IGF-binding defect sustained the IGFBP3-enhanced biological functions. Results indicated that IGFBP3 regulates metastasis-related functions of OSCC cells through an IGF-independent mechanism. Furthermore, exogenous IGFBP3 was sufficient to induce cell motility and extracellular signal-regulated kinase (ERK) activation. The silencing of integrin β1 was able to impair exogenous IGFBP3-mediated migration and ERK phosphorylation, suggesting a critical role of integrin β1 in IGFBP3-enchanced functions.

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.

Heterogeneous tumor stromal microenvironments of oral squamous cell carcinoma cells in tongue and nodal metastatic lesions in a xenograft mouse model

BACKGROUND

Oral squamous cell carcinoma exhibits a poor prognosis, caused by aggressive progression and early-stage metastasis to cervical lymph nodes. Here, we developed a xenograft mouse model to explore the heterogeneity of the tumor microenvironment that may govern local invasion and nodal metastasis of tumor cells.

METHODS

We transplanted five oral carcinoma cell lines into the tongues of nude mice and determined tongue tumor growth and micrometastatic dissemination by serially sectioning the tongue and lymph node lesions in combination with immunohistochemistry and computer-assisted image analysis. Our morphometric analysis enabled a quantitative assessment of blood and lymphatic endothelial densities in the intratumoral and host stromal regions.

RESULTS

All cell lines tested were tumorigenic in mouse tongue. The metastatic lesion-derived carcinoma cell lines (OSC19, OSC20, and HSC2) yielded a 100% nodal metastasis rate, whereas the primary tumor-derived cell lines (KOSC2 and HO-1-u-1) showed <40% metastatic potential. Immunohistochemistry showed that the individual cell lines gave rise to heterogeneous tumor architecture and phenotypes and that their micrometastatic lesions assimilated the immunophenotypic properties of the corresponding tongue tumors. Notably, OSC19 and OSC20 cells shared similar aggressive tumorigenicity in both the tongue and lymph node environments but displayed markedly diverse immunophenotypes and gene expression profiles.

CONCLUSIONS

Our model facilitated comparing the tumor microenvironments in tongue and lymph node lesions. The results support that tumorigenicity and tumor architecture in the host tongue environment depend on the origin and properties of the carcinoma cell lines and that metastatic progression may take place through heterogeneous tumor-host interactions.

Reviewing and reconsidering invasion assays in head and neck cancer

Head and neck squamous cell carcinomas (HNSCC) are malignant tumors that arise from the surface epithelium of the oral cavity, oropharynx and larynx, primarily due to exposure to chemical carcinogens or the human papilloma virus. Due to their location, dental practitioners are well-positioned to detect the lesions. Deadlier than lymphoma or melanoma, HNSCC is incompletely understood. For these reasons, dental practitioners and researchers are focused on understanding HNSCC and the processes driving it. One of these critical processes is invasion, the degradation of the basement membrane by HNSCC cells with subsequent movement into the underlying connective tissue, blood vessels or nerves. Cancer cells metastasize to distant sites via the blood vessels, lymphatics and nerves. Metastasis is associated with poor survival. Since invasion is essential for development and metastasis of HNSCC, it is essential to understand the mechanism(s) driving this process. Elucidation of the mechanisms involved will facilitate the development of targeted treatment, thereby accelerating development of precision/personalized medicine to treat HNSCC. Robust in vitro and in vivo assays are required to investigate the mechanistic basis of invasion. This review will focus on in vitro and in vivo assays used to study invasion in HNSCC, with special emphasis on some of the latest assays to study HNSCC.

The Ah receptor regulates growth factor expression in head and neck squamous cell carcinoma cell lines

Previous studies in head and neck squamous cell carcinoma (HNSCC) cell lines have revealed that the Ah receptor (AHR) plays a significant role in mediating the "aggressive" phenotype of these cells, which includes enhanced inflammatory signaling (e.g., IL6) and migratory potential. Here we sought to identify putative novel targets of the AHR associated with enhanced tumor invasiveness. Global gene expression analysis identified a number of genes that are repressed upon treatment of OSC-19 or HN30 cells with an AHR antagonist. Three growth factors were targets of AHR activity; amphiregulin (AREG), epiregulin (EREG), and platelet-derived growth factor A (PDGFA) were repressed by an AHR antagonist and further examined. Quantitative PCR analysis, ELISA, and siRNA-mediated knock down of AHR revealed an attenuation of basal and/or induced levels of expression of these growth factors in two HNSCC lines, following AHR antagonism. In silico analysis revealed that these growth factors possess dioxin-like response elements. Two other AHR ligands, 6-formylindolo[3,2-b]carbazole and benzo(a)pyrene (BP) also elicited similar responses. In conclusion, this study identified AREG, EREG, and PDGFA as growth factor targets of AHR activity associated with metastatic phenotype of HNSCC cells, suggesting that attenuation of AHR activity may be a therapeutic strategy.

Loss of claudin-7 is a negative prognostic factor for invasion and metastasis in oral squamous cell carcinoma

Claudin-7 belongs to the claudin family, which consists of 24 subtypes of essential tight junction (TJ) integral membrane proteins with molecular weights of 20-27 kDa. We investigated the interrelationship between clinicopathological findings and claudin-7 expression in oral squamous cell carcinoma (OSCC). Using immunohistochemical techniques to examine the expression levels of claudin-7 in 67 cases of OSCC, claudin-7 expression was detected in 35 (52.2%) of the 67 cases. We also compared the clinicopathological features of the OSCC cases with claudin-7 expression levels. Moreover, six cell lines with various invasive properties were investigated in vitro to compare mRNA and protein levels of claudin-7 using reverse transcription-polymerase chain reaction (RT-PCR) and the western blotting method. Decreased claudin-7 expression correlated significantly with T-category (p<0.05), lymph node metastasis (p<0.01), and mode of invasion (p<0.001). Patients with positive claudin-7 expression had a significantly better prognosis (p<0.05). Claudin-7 protein and mRNA levels were lower in the HOC313 and TSU cells, which have higher invasive potentials compared with other cell lines. These results suggest that loss of claudin-7 expression is associated closely with invasion and lymph metastasis and is an unfavorable prognostic factor in patients with OSCC.

CD44 expression in oro-pharyngeal carcinoma tissues and cell lines

Expression of CD44, a transmembrane hyaluronan-binding glycoprotein, is variably considered to have prognostic significance for different cancers, including oral squamous cell carcinoma. Although unclear at present, tissue-specific expression of particular isoforms of CD44 might underlie the different outcomes in currently available studies. We mined public transcriptomics databases for gene expression data on CD44, and analyzed normal, immortalized and tumour-derived human cell lines for splice variants of CD44 at both the transcript and protein levels. Bioinformatics readouts, from a total of more than 15,000 analyses, implied an increased CD44 expression in head and neck cancer, including increased expression levels relative to many normal and tumor tissue types. Also, meta-analysis of over 260 cell lines and over 4,000 tissue specimens of diverse origins indicated lower CD44 expression levels in cell lines compared to tissue. With minor exceptions, reverse transcribed polymerase chain reaction identified expression of the four main isoforms of CD44 in normal oral keratinocytes, transformed lines termed DT and HaCaT, and a series of paired primary and metastasis-derived cell lines from oral or pharyngeal carcinomas termed HN4/HN12, HN22/HN8 and HN30/HN31. Immunocytochemistry, Western blotting and flow cytometric assessments all confirmed the isoform expression pattern at the protein level. Overall, bioinformatic processing of large numbers of global gene expression analyses demonstrated elevated CD44 expression in head and neck cancer relative to other cancer types, and that the application of standard cell culture protocols might decrease CD44 expression. Additionally, the results show that the many variant CD44 exons are not fundamentally deregulated in a diverse range of cultured normal and transformed keratinocyte lines.

USPIO-enhanced MRI of highly invasive and highly metastasizing transplanted human squamous cell carcinoma: an experimental study

OBJECTIVE

The aim of this study was to investigate the signal intensity characteristics of highly invasive and highly metastasizing transplanted human squamous cell carcinoma using ultra-small super-paramagnetic iron oxide (USPIO)-enhanced MRI and to correlate them with USPIO distribution to tumour components revealed by histological examination.

METHODS

13 nude mice with transplanted human squamous cell carcinoma in the oral cavity were imaged before and 24 hours after intravenous administration of USPIO. The difference in signal intensity between pre-contrast and post-contrast MR images was visually evaluated. For quantitative analysis, signal intensity within a region of interest was measured. Histological findings were correlated with MR findings. The approximate USPIO concentration was evaluated using USPIO phantoms.

RESULTS

Seven tumours had an area showing signal intensity increase on post-contrast T₁ weighted images. Histopathologically, six of those tumours contained a small amount of iron particles in the stroma. The USPIO concentration was presumed low. Two tumours had an area showing signal intensity decrease on post-contrast T₁ and T₂ weighted images. The areas had a large amount of iron particles in the stroma and the USPIO concentration was presumed high. There was a minimal amount of iron particles in tumour parenchymal cells.

CONCLUSIONS

The amount of USPIO accumulation into tumour stroma was considered to affect MR signal intensity. A small amount increases T₁ weighted signal intensity, whereas a large amount decreases T₁ and T₂ weighted intensity. The USPIO accumulation into the tumour parenchyma was not thought to affect MR signal intensity.

Decreased lymphangiogenesis and lymph node metastasis by mTOR inhibition in head and neck cancer

Despite our improved understanding of cancer, the 5-year survival rate for head and neck squamous cell carcinomas (HNSCC) patients remains relatively unchanged at 50% for the past three decades. HNSCCs often metastasize to locoregional lymph nodes, and lymph node involvement represents one of the most important prognostic factors of poor clinical outcome. Among the multiple dysregulated molecular mechanism in HNSCCs, emerging basic, preclinical, and clinical findings support the importance of the mTOR signaling route in HNSCC progression. Indeed, we observed here that the activation of mTOR is a widespread event in clinical specimens of HNSCCs invading locoregional lymph nodes. We developed an orthotopic model of HNSCC consisting of the implantation of HNSCC cells into the tongues of immunocompromised mice. These orthotopic tumors spontaneously metastasize to the cervical lymph nodes, where the presence of HNSCC cells can be revealed by histologic and immunohistochemical evaluation. Both primary and metastatic experimental HNSCC lesions exhibited elevated mTOR activity. The ability to monitor and quantitate lymph node invasion in this model system enabled us to explore whether the blockade of mTOR could impact HNSCC metastasis. We found that inhibition of mTOR with rapamycin and the rapalog RAD001 diminished lymphangiogenesis in the primary tumors and prevented the dissemination of HNSCC cancer cells to the cervical lymph nodes, thereby prolonging animal survival. These findings may provide a rationale for the future clinical evaluation of mTOR inhibitors, including rapamycin and its analogues, as part of a molecular-targeted metastasis preventive strategy for the treatment of patients with HNSCC.

Quantitative chemical proteomics reveals new potential drug targets in head and neck cancer

Tumors of the head and neck represent a molecularly diverse set of human cancers, but relatively few proteins have actually been shown to drive the disease at the molecular level. To identify new targets for individualized diagnosis or therapeutic intervention, we performed a kinase centric chemical proteomics screen and quantified 146 kinases across 34 head and neck squamous cell carcinoma (HNSCC) cell lines using intensity-based label-free mass spectrometry. Statistical analysis of the profiles revealed significant intercell line differences for 42 kinases (p < 0.05), and loss of function experiments using siRNA in high and low expressing cell lines identified kinases including EGFR, NEK9, LYN, JAK1, WEE1, and EPHA2 involved in cell survival and proliferation. EGFR inhibition by the small molecule inhibitors lapatinib, gefitinib, and erlotinib as well as siRNA led to strong reduction of viability in high but not low expressing lines, confirming EGFR as a drug target in 10-20% of HNSCC cell lines. Similarly, high, but not low EPHA2-expressing cells showed strongly reduced viability concomitant with down-regulation of AKT and ERK signaling following EPHA2 siRNA treatment or EPHA1-Fc ligand exposure, suggesting that EPHA2 is a novel drug target in HNSCC. This notion is underscored by immunohistochemical analyses showing that high EPHA2 expression is detected in a subset of HNSCC tissues and is associated with poor prognosis. Given that the approved pan-SRC family kinase inhibitor dasatinib is also a very potent inhibitor of EPHA2, our findings may lead to new therapeutic options for HNSCC patients. Importantly, the strategy employed in this study is generic and therefore also of more general utility for the identification of novel drug targets and molecular pathway markers in tumors. This may ultimately lead to a more rational approach to individualized cancer diagnosis and therapy.

KITENIN represents a more aggressive phenotype in a murine model of oral cavity squamous carcinoma

Objective: To investigate the tumor invasiveness and early lung metastasis associated with KITENIN in a murine model of oral cavity squamous carcinoma.

Study Design: Cross-sectional study with planned data collection.

Setting: Department of Otolaryngology–Head and Neck Surgery, Medical Research Center for Gene Regulation, and Pathology, Chonnam National University Medical School and Hwasun Hospital.

Subjects and Methods: The cDNA of KITENIN and vector only were transfected into the SCC VII (murine squamous cell line) cells. The suspension of 5 × 105/mL viable KITENIN- or vector-transfected SCC VII cells was injected into the floor of the mouth of C3H/HeJ syngeneic mice, deep into the mylohyoid muscle via the intraoral approach. From the first to the sixth week after injection, tumor, lung, liver, and brain tissues were obtained.

Results: For all groups, the tumor invaded the superficial musculature of the floor of the mouth, the deep musculature of the floor of the mouth, the salivary glands, perineural tissue, bone, and skin, sequentially. Lung metastases developed multiple focal nodular patterns at first and then became more extensive. Earlier and more aggressive tumor invasion into the deep floor of the mouth musculature, salivary glands, perineural tissue, bone, and skin was observed in the KITENIN-transfected group compared to the vector-only group. An earlier and more extensive lung metastasis was observed in the KITENIN group.

Conclusion: An antisense KITENIN strategy might inhibit distant metastasis and the progression of head and neck squamous cell carcinoma.

Significance of stromal desmoplasia and myofibroblast appearance at the invasive front in squamous cell carcinoma of the oral cavity

BACKGROUND

Tumor invasion involves complex interactions between tumor and stromal cells. We examined the extent of connective tissue in the tumor stroma and whether myofibroblasts play a role in assisting cancer invasion and metastasis.

METHODS

Biopsy materials from 84 patients with oral squamous cell carcinoma (SCC) were used. We compared data from intrastromal collagen fibers using Azan staining, immunohistochemical identification of myofibroblasts by cytoskeletal markers, alpha-smooth muscle actin, vimentin, desmin, and clinicopathological parameters. Clinical outcome was compared by 5-year survival rate.

RESULTS

There were high levels of stromal collagen fibers in invasive tumors. Myofibroblast appearance increased with increasing tumor invasiveness. Lymph node metastasis occurred more frequently in the myofibroblast-positive group, and the survival rate was significantly poorer in this group.

CONCLUSIONS

Fibrous stroma in SCC appeared to have a desmoplastic response. However, an independent invasive mechanism may regulate the stroma, with tumor desmoplasia occurring in highly developed, invasive tumors.

Xenograft models of head and neck cancers

Head and neck cancers are among the most prevalent tumors in the world. Despite advances in the treatment of head and neck tumors, the survival of patients with these cancers has not markedly improved over the past several decades because of our inability to control and our poor understanding of the regional and distant spread of this disease. One of the factors contributing to our poor understanding may be the lack of reliable animal models of head and neck cancer metastasis. The earliest xenograft models in which human tumor cells were grown in immunosuppressed mice involved subcutaneous implantation of human head and neck cancer cell lines. Subcutaneous xenograft models have been popular because they are easy to establish, easy to manage, and lend themselves to ready quantitation of the tumor burden. More recently, orthotopic xenograft models, in which the tumor cells are implanted in the tumor site of origin, have been used with greater frequency in animal studies of head and neck cancers. Orthotopic xenograft models are advantageous for their ability to mimic local tumor growth and recapitulate the pathways of metastasis seen in human head and neck cancers. In addition, recent innovations in cell labeling techniques and small-animal imaging have enabled investigators to monitor the metastatic process and quantitate the growth and spread of orthopically implanted tumors. This review summarizes the progress in the development of murine xenograft models of head and neck cancers. We then discuss the advantages and disadvantages of each type of xenograft model. We also discuss the potential for these models to help elucidate the mechanisms of regional and distant metastasis, which could improve our ability to treat head and neck cancers.

An orthotopic floor-of-mouth model for locoregional growth and spread of human squamous cell carcinoma

The molecular investigation of head and neck cancer targets requires the utilization and optimization of established animal models to characterize the effects of gene transcription and protein expression on invasion and metastasis. Floor-of-the-mouth murine models have been developed to study tumor growth, invasion, and metastasis of murine squamous cell carcinoma (SCC) cells in immunocompetent mice and invasion and metastasis of human SCC cells in nude mice. However, there are tumor cell lines that do not produce tumors in mice, using standard techniques, thus reducing the utility of the model to study specific genetic or treatment conditions. Furthermore, these techniques require large tumor volumes raising the possibility of airway compromise. In this report, we detail significant modifications to the orthotopic floor-of-mouth murine model for human SCC to facilitate predictable growth of a large panel of University of Michigan SCC cell lines. Furthermore, we describe the use of bioluminescence and micro-computed tomography to monitor tumor growth and bony invasion.

Preclinical models of regional lymph node tumor metastasis

Animal models have produced vital information regarding the mechanisms of RLN metastasis. Modern imaging and molecular techniques have made it clear that growing tumors secrete cytokines that induce invasion, angiogenesis, lymphangiogenesis, increased intratumoral IFV and IFP, increased fluid flow from the tumor to the surrounding tissues, increased lymphatic flow, an increase in the rate of entry of tumor cells into lymphatic capillaries, and an increased number of tumor cells reaching the RLN(s). This is important knowledge that will help direct translational research in human patients. We can look forward to continued improvement in the management of human tumors that metastasize to the RLNs.

Periostin promotes invasion and anchorage-independent growth in the metastatic process of head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is one of the most common types of human cancer. Typically, HNSCC cells show persistent invasion that frequently leads to local recurrence and distant lymphatic metastasis. However, molecular mechanisms associated with the invasion and metastasis of HNSCC remain poorly understood. Here, we identified periostin as an invasion-promoting factor in HNSCC by comparing the gene expression profiles between parent HNSCC cells and a highly invasive clone. Indeed, periostin overexpression promoted invasion and anchorage-independent growth both in vitro and in vivo in HNSCC cells. Moreover, periostin-overexpressing cells spontaneously metastasized to cervical lymph nodes and to the lung through their aggressive invasiveness in an orthotopic mouse model of HNSCC. Interestingly, periostin was highly expressed in HNSCCs in comparison with normal tissues, and the level of periostin expression was well correlated with the invasiveness of HNSCC cases. In summary, these findings suggest that periostin plays an important role in the invasion and anchorage-independent growth of HNSCC.

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

Understanding the complex histological, genetic and molecular changes that lead to malignant transformation of squamous epithelia of the head and neck will likely guide the development of methods for improved diagnosis, monitoring and treatment of head and neck squamous cell carcinoma (HNSCC). The development and use of animal models that closely mimic the histopathology and molecular pathogenesis of HNSCC in humans would greatly expand the research possibilities and provide a means of testing potential therapeutic agents. However, many available animal models of HNSCC fall short of this objective. In order for investigators to select the appropriate model to answer scientific questions, it is important to understand the benefits and limitations of available animal models for the study of HNSCC. The purpose of this work is to give an overview of the most pertinent animal models of HNSCC, and to discuss future directions of research in this field.

Inhibition of invasion and metastasis in oral cancer by targeting urokinase-type plasminogen activator receptor

There have been reports of strong correlations between poor prognosis in various cancers and concomitant expression of urokinase-type plasminogen activator (uPA) and its surface receptor (uPAR). We and others have previously shown that the uPA system plays a significant role in a subset of head and neck squamous cell carcinoma. In the present study, we found that uPAR is required for invasion and metastasis of highly malignant oral cancer cells (OSC-19). Treating OSC-19 cells with antisense oligonucleotides (AS) targeting uPAR resulted in a dramatic decrease of uPAR mRNA expression. Furthermore, pretreatment with AS or siRNA targeting uPAR inhibited progression of OSC-19 cells in experimental models. These results suggest that overexpression of uPAR increases the invasiveness and metastasis of OSC-19 cells, and that uPAR is a promising therapeutic target for regulation of progression of oral cancer.

Development and immunophenotyping of squamous cell carcinoma xenografts: tools for translational immunology

OBJECTIVES/HYPOTHESIS

The objectives of this study were to delineate methods for the development of primary squamous cell carcinoma (SCCHN) xenografts and to define human leukocyte antigen (HLA), melanoma-associated antigen (MAGE)-A3, and human papilloma virus (HPV) 16 antigenic expression in resultant cellular products.

STUDY DESIGN

Prospective experimental model.

METHODS

Freshly isolated SCCHN xenografts were established in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice using a variety of methods. Resultant tumors were analyzed for expression patterns of HLA-A, MAGE-A3, and HPV 16. Appropriate controls were included to ensure the presence of human RNA.

RESULTS

Three xenografts were successfully established and passaged in vivo. Characterization of the resultant products revealed that one was positive for HLA-A2 at both the DNA and protein levels. One of the tumor lines expressed MAGE-A3, whereas none expressed HPV 16.

CONCLUSIONS

Freshly isolated SCCHN can be used to generate primary xenografts. Characterization of select patterns of protein expression in established xenografts is a precursor to the development of a mouse model for SCCHN using tumor bearing animals reconstituted with autologous patient leukocytes.

[Orthotopic murine model of head and neck squamous cell carcinoma]

PURPOSE

To develop a reliable animal model able to reproduce the behavior of head and neck squamous cell carcinomas (HNSCC). This model should facilitate our understanding of the molecular mechanisms of tumorigenicity and progression of these tumors, as well as the evaluation of novel therapies.

MATERIAL AND METHODS

20 nude mice nu/nu were injected intraorally and submucosally with a cell line derived from a human squamous cell carcinoma of the glottis.

RESULTS

90% of the mice developed locally agressive squamous cell carcinomas, invading the surrounding muscle fibers and into loose connective tissue structures. All the tumors showed perineural growth. Four (22%) of the 18 mice showed bone destruction, and 22% vascular invasion. Tumor cells invaded lymphatic vessels in all the specimens, and 100% of the mice developed regional lymph node metastases. None of the animals developed haematogenous metastases.

CONCLUSIONS

We present a metastasing model of HNSCC that resembles its human counterpart in many aspects.

Metastatic dissemination of human malignant oral keratinocyte cell lines following orthotopic transplantation reflects response to TGF-beta 1

This study examined the behaviour of nine human malignant oral keratinocyte cell lines following orthotopic transplantation to the floor of the mouth of athymic mice. Tumourigenesis, local spread, and metastatic dissemination were correlated with known cellular responses to transforming growth factor-beta 1 (TGF-beta 1). Six of nine cell lines were tumourigenic; four of these cell lines showed local spread which was characterized by vascular and bone invasion. Metastatic spread was uncommon, with only 9% of animals with primary tumours developing metastases and these were almost exclusively found in the regional lymph nodes; there was one pulmonary metastasis and no liver deposits. Tumour cell behaviour did not reflect the clinical stage of the original tumours. Cell lines that were resistant to TGF-beta 1-induced growth inhibition were more likely to form primary tumours, exhibit local spread, and metastasize than cells that were growth-inhibited by the ligand. The data demonstrate that tumourigenicity and tumour behaviour in this orthotopic mouse model varied between cell lines and that the pattern of local invasion and metastasis was similar to that seen in human oral cancer. Furthermore, cell lines that were refractory to the growth inhibitory effects of TGF-beta 1 behaved more aggressively than cells that underwent ligand-induced cell-cycle arrest.

Clinical, cellular, and molecular aspects of cancer invasion

Invasion causes cancer malignancy. We review recent data about cellular and molecular mechanisms of invasion, focusing on cross-talk between the invaders and the host. Cancer disturbs these cellular activities that maintain multicellular organisms, namely, growth, differentiation, apoptosis, and tissue integrity. Multiple alterations in the genome of cancer cells underlie tumor development. These genetic alterations occur in varying orders; many of them concomitantly influence invasion as well as the other cancer-related cellular activities. Examples discussed are genes encoding elements of the cadherin/catenin complex, the nonreceptor tyrosine kinase Src, the receptor tyrosine kinases c-Met and FGFR, the small GTPase Ras, and the dual phosphatase PTEN. In microorganisms, invasion genes belong to the class of virulence genes. There are numerous clinical and experimental observations showing that invasion results from the cross-talk between cancer cells and host cells, comprising myofibroblasts, endothelial cells, and leukocytes, all of which are themselves invasive. In bone metastases, host osteoclasts serve as targets for therapy. The molecular analysis of invasion-associated cellular activities, namely, homotypic and heterotypic cell-cell adhesion, cell-matrix interactions and ectopic survival, migration, and proteolysis, reveal branching signal transduction pathways with extensive networks between individual pathways. Cellular responses to invasion-stimulatory molecules such as scatter factor, chemokines, leptin, trefoil factors, and bile acids or inhibitory factors such as platelet activating factor and thrombin depend on activation of trimeric G proteins, phosphoinositide 3-kinase, and the Rac and Rho family of small GTPases. The role of proteolysis in invasion is not limited to breakdown of extracellular matrix but also causes cleavage of proinvasive fragments from cell surface glycoproteins.

Effects of fibroblast growth inhibitor on proliferation and metastasis of oral squamous cell carcinoma

Development of a new therapeutic approach to improve the prognosis of high grade invasion of oral squamous cell carcinoma is needed. To elucidate the effect of a fibroblast inhibitor (tranilast), we investigated the proliferation and metastasis of oral squamous cell carcinoma in a mouse model. The effect of tranilast on tumour growth, lymph node metastases, microvessel density, and the proliferating cell nuclear antigen (PCNA) labelling index of oral squamous cell carcinoma implanted into the tongue of nude mice was evaluated. Tumour growth and the incidence of cervical lymph node metastases were significantly suppressed by the administration of tranilast. The amount of fibrous tissue, the microvessel density, and the PCNA labelling index of tumour were also significantly reduced. Administration of a fibroblast inhibitor may well be clinically effective for the treatment of oral squamous cell carcinoma.

Inhibition of cervical lymph node metastasis by marimastat (BB-2516) in an orthotopic oral squamous cell carcinoma implantation model

Activation of matrix metalloproteinase-2 (MMP-2) is a common event in head and neck squamous cell carcinoma. An OSC-19 cell line, derived from human oral squamous cell carcinoma and known to metastasize to cervical lymph nodes, was implanted into the lingual margin of mice. The effect of marimastat (BB-2516), a broad MMP inhibitor, on the suppression of regional cervical lymph node metastasis was evaluated with an orthotopic implantation nude mice model. Marimastat was given immediately after OSC-19 implantation and continuously administered by an osmotic pump. The mice were divided into three groups by marimastat dose; Group A; 0 mg/kg/day, Group B; 30 mg/kg/day, and Group C; 150 mg/kg/day. Twenty-one days after implantation, primary oral tumors and cervical lymph nodes were resected. Cervical lymph node status was microscopically examined. Activation of MMP-2 in primary oral tumor was examined by gelatin zymography. Both cervical lymph node metastasis and activation of MMP-2 were significantly suppressed in Group C (P < 0.05). Moreover, the Group C mice had a significantly better survival than group A (P = 0.0026). There was a significant difference between Group A and Group C in terms of proliferation of tumor cells by proliferating cell nuclear antigen immunostaining (P = 0.0120). These results suggest a positive role for marimastat in the inhibition of MMP-2 activation and prevention of cervical lymph node metastasis in oral squamous cell carcinoma (OSCC). Improvement of survival in patients with OSCC could be expected using adjuvant therapy with marimastat.

Human tumor-derived genomic DNA transduced into a recipient cell induces tumor-specific immune responses ex vivo

This article describes a DNA-based vaccination strategy evaluated ex vivo with human cells. The vaccine was prepared by transferring tumor-derived genomic DNA to PCI-13 cells, a highly immunogenic tumor cell line ("recipient cell"), which had been genetically modified to secrete IL-2 (PCI-13/IL-2). PCI-13 cells expressed class I MHC determinants (HLA-A2) shared with the tumor from which the DNA was obtained as well as allogeneic determinants. DNA from a gp100(+) melanoma cell line was transduced into gp100(-) PCI-13/IL-2 cells (PCI-13/IL-2/DNA). A T cell line specific for the gp100 epitope responded to PCI-13/IL-2/DNA cells by IFN-gamma-secretion measured in enzyme-linked immunospot assays. The T cell line also recognized the gp100 epitope presented by dendritic cells that ingested PCI-13/IL-2/DNA cells, which had been induced by UVB irradiation to undergo apoptosis. After up-take and processing of apoptotic PCI-13/IL-2/DNA cells, the dendritic cells primed normal peripheral blood lymphocytes to generate effector T cells specific for the tumor donating the DNA. The results indicate that tumor epitopes encoded in such DNA are expressed in recipient cells and can induce tumor-specific T cells. The findings support translation of this vaccination strategy to a phase I trial in patients with cancer.

p120(cat) Delocalization in cell lines of oral cancer

p120(cat) is a novel component of the catenin family, a cytoplasmic molecule closely associated with the cell-cell adhesion molecule E (epithelial)-cadherin, by forming complexes between the cytoplasmic domain of E-cadherin and the cytoskeleton. Recent studies suppose a role for this molecule in human cancers and to date none report its expression in oral squamous cell carcinomas (SCCs). The goal of this study was to evaluate the role of this protein in the oral carcinogenetic process. A linked streptavidin-biotin-alkaline phosphatase technique was used to examine the immunoreactivity and cellular localisation of p120(cat) in five oral epithelial cell lines (NCTC 2544, normal and immortalized keratinocytes; KB, a poorly differentiated SCC cell line; OSC 20, a well differentiated oral SCC cell line; CAL 33 and CAL 27, moderately differentiated oral SCC cell lines) and 10 normal oral epithelium biopsies.

RESULTS

As already reported for E-cadherin, beta- and gamma-catenin, p120 expression showed a homogeneous membranous localization in normal oral specimens. The intensity of staining for p120 progressively increased from basal and parabasal layers toward the intermediate spinous layer. No staining for p120 was observed in the upper layer. NCTC showed a membranous positivity. OSC 20, CAL 33 and CAL 27 showed a membranous positivity, even if polarized to cell-cell adhesion sites, in 40-50% of cells. OSC 20, CAL 33 and CAL 27 cells showed also a cytoplasmic delocalization. All positive KB cells showed a prevalent cytoplasmic staining and 10% of these cells showed a nuclear delocalization. In cancer cells, p120 showed an inverse relationship with the degree of differentiation for a progressive displacement of the signal toward the cytoplasm or nucleus in dedifferentiated cells. In conclusions, this nuclear delocalization for p120 could suppose its potential involvement in signalling and cancer transformation.

Establishment and characterization of a human adenoid cystic carcinoma line of the salivary gland which is serially transplantable and spontaneously metastasises to the lung in nude mice

Adenoid cystic carcinoma (ACC) is a rare malignant tumour of the head and neck occurring in the salivary glands. We established a human ACC line which is serially transplantable in nude mice and designated it as KOA-1. The KOA-1 tumour doubled in 9.3 days and retained the histological characteristics of a solid pattern of ACC even after 22 serial passages. The KOA-1 metastasised to the lung when transplanted subcutaneously into the back. This tumour line may serve as a useful model for exploration of the biological behaviour and treatment of human ACC.

Effects of chemotherapy on invasion and metastasis of oral cavity cancer in mice

BACKGROUND

Using an orthotopic implantation model in which oral cancer invasion and metastasis can be reproduced, we investigated the inhibitory effects of anticancer agents on invasion and metastasis.

METHODS

A highly invasive and metastatic human oral squamous cell carcinoma cell line, OSC-19, was implanted into the oral floor of nude mice, and cisplatin or peplomycin was administered to the mice 7 or 14 days after implantation. The effects of each anticancer drug and different administration timings on cancer invasion and metastasis were investigated.

RESULTS

Tumor size and the ratio of proliferating cell nuclear antigen-positive cells was significantly reduced. In the control group, the tumors showed grade 4C mode of invasion, whereas in the groups treated with anticancer drugs, grade 3 was observed in 77.3% of the mice, with an inhibitory effect on tumor invasion being observed. The rate of metastasis in the cervical lymph node was significantly decreased in the groups treated with the cisplatin or peplomycin on day 7 after implantation. The tumor stage progression in the metastatic lymph nodes was also inhibited.

CONCLUSIONS

Chemotherapy is effective not only for tumor diminution but also for inhibiting invasion and metastasis. In light of these effects, administration of anticancer drugs may be clinically useful in this regard.

Establishment of an oral squamous cell carcinoma cell line (NOS-1) exhibiting amplification of the erbB-1 oncogene and point mutation of p53 tumor suppressor gene: its biological characteristics and animal model of local invasion by orthotopic transplantation of the cell line

We established a new cancer cell line, NOS-1, which was derived from a human oral primary squamous cell carcinoma. Geneticin treatment was adopted to eliminate contaminating fibroblasts and to enrich tumor cells in the early stage of the culture. The NOS-1 cells showed epithelial morphological features with light and electron microscopy, and immunohistochemical analysis confirmed their epithelial origin. Overexpression of mutant p53 protein, a p53 point mutation at codon 248 with transition from CGG to TGG, and amplification of the erbB-1 oncogene/epidermal growth factor receptor gene were also observed in NOS-1 cells. The NOS-1 cells formed tumors in nude mice when transplanted subcutaneously into their backs. Further, they were transplantable orthotopically in the tongues of nude mice, and the transplanted tumors in the tongue showed diffuse invasion without forming capsules. The NOS-1 cells were useful for elucidating the mechanism involving p53 inactivation and erbB-1 oncogene amplification, as well as treatment of oral cancer.

Loss of differentiation of 4NQO-induced rat malignant oral keratinocytes correlates with metastatic dissemination and is associated with a reduced cellular response to TGF-beta1 and an altered receptor profile

This study examined the metastatic capacity of clonal populations of 4NQO-induced rat malignant oral keratinocytes following orthotopic transplantation to athymic mice. Polygonal and spindle cells formed well-differentiated squamous cell carcinomas (keratin positive and vimentin negative) and undifferentiated spindle cell tumours (keratin negative and vimentin positive), respectively, in almost 100% of animals at the site of inoculation (floor of mouth). Transplantation of 5x 10(6) cells of either cell type at high cell density resulted in approximately 50% of animals forming pulmonary metastases. By contrast, inoculation of 2x 10(6) differentiated polygonal cells resulted in the formation of significantly fewer pulmonary metastases than the undifferentiated spindle cells. A single well-differentiated clone of polygonal cells and 3 of 4 of the undifferentiated spindle cell lines produced comparable levels of TGF-beta1. One undifferentiated spindle cell line expressed significantly more TGF-beta1 and, following transplantation orthotopically, fewer animals formed pulmonary metastases despite the formation of primary tumours in almost all grafted animals, suggesting that TGF-beta1 can act as a tumour suppressor in this cell type. All cell lines produced comparable amounts of TGF-beta2. The clones of polygonal cells were markedly inhibited and the spindle cells were only partially inhibited by exogenous TGF-beta1. Both cell types expressed high-affinity TGF-beta cell surface receptors; the ratio of type I to type II TGF-beta receptors was 1.0:<3.0 in the spindle cells and 1.0:17.9 in the polygonal clone. The results suggest that differentiated rat malignant oral keratinocytes are less aggressive and have a decreased potential to metastasise than their undifferentiated spindle cell counterparts. This may be attributable, in part, to a change in TGF-beta receptor profile leading to the partial loss of response to exogenous TGF-beta1.

Immunotherapy with effector cells and IL-2 of lymph node metastases of human squamous-cell carcinoma of the head and neck established in nude mice

We have previously reported that immune anti-tumor effector cells, both cytotoxic T lymphocytes (CTLs) and IL-2-activated natural killer (A-NK) cells, are effective at eliminating human head-and-neck cancer (HNC) targets in vitro and in vivo in xenograft models. In this study, these 2 types of human effector cell were compared for the ability to prevent the development of lymph node metastases in a metastasis model of human squamous-cell carcinoma of the head and neck (SCCHN) established in nude mice. A tumor cell line, OSC-19, was injected into the floor of the mouth in nude mice, and the tumor grew progressively and metastasized to cervical lymph nodes by day 21. As effector cells, a human HLA-A2-restricted CTL line recognizing a shared antigen on OSC-19 and human non-MHC-restricted A-NK cells were used. Both types of effector cell mediated high levels of lysis against OSC-19 targets in 4-hr (51)Cr-release assays. Administration of human CTLs or A-NK cells and IL-2 to the site of tumor growth in mice with 7-day OSC-19 tumors resulted in significant reduction of the number of lymph node metastases relative to untreated or sham-operated controls or to mice treated with IL-2 without the effector cells. Our results suggest that in a xenograft model of human SCCHN implanted in the oral cavity of nude mice, the development of lymph node metastases can be successfully controlled by adoptive transfer of human SCCHN-specific CTLs or SCCHN-reactive A-NK cells plus IL-2.

Reproduction of occult metastasis of head and neck cancer in nude mice

The presence of occult metastasis is the most important factor that influences the prognosis in patients with head and neck cancer. To reproduce occult metastasis of oral cancer cells, we serially resected the primary focus in an orthotopic implantation model to examine when metastasis of cancer cells occurs. Human squamous cell carcinoma was implanted into the tongue of nude mice divided into two groups, non-surgery and surgery groups. Mice in the non-surgery group were sacrificed, and the tongue cancer and cervical lymph nodes were resected simultaneously. In the surgery-group, resection of the tongue cancer was performed, and the cervical lymph nodes were resected on day 28. For the non-surgery-group, the incidences of metastasis were 0%, 9%, 36%, 91% and 100% on days 3, 7, 14, 21 and 28, respectively. For the surgery-group, resection of the tongue cancer was performed on days 3, 7 and 14, and the incidence of metastasis on day 28 was 0%, 82% and 91%, respectively. The occult metastasis was reproduced using resected primary cancer on day 7. This time-based model may be useful to clarify the mechanism of metastasis and to develop new treatments.

Expression of ICAM-1 in implanted primary and metastatic squamous cell carcinomas in rats

FF6 tumor cells are derived from a spontaneous rat squamous cell carcinoma (SCC) which originally arose in the facial skin of a DA rat. In this study, FF6 tumor cells were implanted into rat oral mucosa to establish an ex vivo metastatic model. We analyzed the expression of intercellular cell adhesion molecule-1 (ICAM-1) in the implanted primary and metastatic FF6 tumors by immuno-staining with a monoclonal antibody (mAb) against ICAM-1. The implanted primary FF6 cells showed strong expression of ICAM-1, whereas the tumor cells of metastatic lesions showed weak or negative expression of ICAM-1. By immunostaining with mAb OX6, a number of MHC class II-positive macrophages were detected in tumor mesenchyme and surrounding the metastatic foci. These results suggested that the local immune reaction in the lymph node influenced the expression of ICAM-1 on tumor cells, and that MHC class II-positive macrophages may play a role in transplanted tumor growth and metastases.