Heterogeneity in epidermal growth factor responsiveness and tumor growth of human maxillary cancer cell lines

Establishment and characterization of an orthotopic sinonasal squamous cell carcinoma mouse model

BACKGROUND

Despite therapeutic improvements, patients with sinonasal squamous cell carcinoma (SCC) still face an unfavorable prognosis and there is great need for alternative treatments.

METHODS

SCCNC4 cells, originally derived from a T2N1M0 primary and untreated sinonasal SCC, were inoculated in the maxillary sinus of immunodeficient mice. Histology, invasive behavior, and genetic features were evaluated and compared with the original primary tumor.

RESULTS

The mice developed tumors that invaded bone, surrounding tissues, and brain, showing the same poor differentiation as the original primary tumor. Genetic analysis revealed an almost identical pattern of copy number alterations, except for the deletion and loss of expression of the genes CDKN2A and PTEN.

CONCLUSION

This article shows the feasibility of an orthotopic mouse model of SCC of the maxillary sinus. Completed by genome-wide genetic profiling data, this model will be useful for preclinical testing of specific gene-targeted anticancer drugs.

Establishment and genetic characterization of six unique tumor cell lines as preclinical models for sinonasal squamous cell carcinoma

Sinonasal squamous cell carcinomas (SCC) are rare tumors, etiologically related to occupational exposure to wood and leather dust. In spite of surgical and radiotherapeutic advances, the 5 year survival is still 30–50%. Therefore, alternative treatment options are needed. We report the establishment and characterization of six unique human sinonasal SCC cell lines, named SCCNC1, 2, 4, 5, 6 and 7. In vitro growth and invasion characteristics were evaluated and genetic profiles were compared to those of the original primary tumors. The population doubling times ranged from 21 to 34 hours. Cell lines SCCNC2 and 7 were highly invasive in matrigel. Five cell lines carried a high number of copy number alterations, including amplifications and homozygous deletions, while one showed only three abnormalities. Sequence analysis revealed three cell lines with TP53 mutation and none with KRAS or BRAF. Overexpression of p53 was observed in five, and of EGFR in four cell lines. None of the cell lines showed strong immunopositivity of p16 or presence of human papilloma virus. In conclusion, we have created six new cell lines that are clinically and genetically representative of sinonasal SCC and that will be a useful tool for the preclinical testing of new therapeutic agents.

Expression of CXCR4 and Its Down-Regulation by IFN-γ in Head and Neck Squamous Cell Carcinoma

PURPOSE

The functional expression of CXCR4, which plays roles in cell migration and proliferation in response to its unique ligand stromal cell-derived factor-1 (SDF-1), has been reported in variety of carcinomas. However, CXCR4 expression and its functional role in head and neck squamous cell carcinomas (HNSCC) remain unclear. In this study, we investigated CXCR4 expression and analyzed its functions in HNSCC cell lines. We also attempted to regulate CXCR4 expression using cytokines, such as interleukin-1beta, tumor necrosis factor-alpha, and IFN-gamma. Finally, we investigated correlation between CXCR4 expression and clinical features in patients with HNSCC.

EXPERIMENTAL DESIGN

Six HNSCC cell lines were used in this study. Reverse transcription-PCR and flow cytometry analysis were shown for CXCR4 expressions with or without stimulations of cytokines. SDF-1-mediated cell migration was assayed in Matrigel-coated chemotaxis chamber. The SDF-1-mediated cell proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The SDF-1-mediated signaling pathways were analyzed by Western blot analysis. Biopsy specimens from 56 patients with HNSCC were used for immunohistologic analysis.

RESULTS

The significant CXCR4 expression was found in HSQ-89, IMC-3, and Nakamura cells. The SDF-1-mediated cell migration and proliferation were observed in CXCR4-positive cells. SDF-1 also promoted rapid phosphorylation of extracellular signal-regulated kinase 1/2 and Akt signaling pathways in CXCR4-positive cells. The SDF-1-mediated cell migration and proliferation of CXCR4-positive cells were inhibited by neutralization of CXCR4. Among three cytokines tested, IFN-gamma significantly reduced CXCR4 expression and SDF-1-induced cell migration and proliferation of CXCR4-positive cells. Immunohistologic analysis revealed that patients with advanced neck status and patients who developed distant metastases showed significantly higher CXCR4 expression, and the cause-specific survival of patients with CXCR4-expression was significantly shorter. Furthermore, multivariate analysis confirmed that CXCR4 positive was the independent factor for cause-specific death.

CONCLUSION

Our results may provide an insight into future therapeutic agent that inhibits tumor metastasis and progression via down-regulating CXCR4 expression in patients with HNSCC.

Simulation of cell proliferation in mouse oral epithelium, and the action of epidermal growth factor: evidence for a high degree of synchronization of the stem cells

Computer simulation has been carried out to help to determine the cell-proliferative mechanisms underlying data gathered from a double-labelling experiment on the dorsal tongue of the mouse. Good fits to the data have been obtained by assuming that there is a high degree of synchrony in the stem cells, which have a 24-h cell cycle time, and that daughters of these cells undergo two further divisions, with mean cell cycle times of 48 h, before differentiating. This results in one-seventh of proliferative cells being stem cells, which ties in well with the concept of epidermal proliferative units. There is no need to assume that S-phase duration changes diurnally. The administration of epidermal growth factor seems to increase the degree of synchrony. In such systems, the influx to S-phase and the efflux from it have very sudden short peaks, which it is impossible to observe unless observations are taken very frequently. There are therefore implications for the designs of experiments that attempt to study diurnal rhythms or the effect of factors that disturb the normal proliferative pattern of cells.

Tritiated thymidine and bromodeoxyuridine double-labelling studies on growth factors and oral epithelial proliferation in the mouse

Mouse tongue epithelium is characterized by a circadian variation in the number of cells undergoing DNA synthesis. Groups of male BDF1 mice were followed over 48 h and a double-labelling method with tritiated thymidine and bromodeoxyuridine used to determine S-phase labelling indices, together with cell influx to and cell efflux from S, at 4-hourly time points. Control animals exhibited diurnal peaks in labelling index at 03:00 with trough activity 12 h later at 15:00. Cell influx peaked at 23:00 with troughs occurring between 11:00 to 15:00. Peak cell efflux occurred at 07:00 with trough activity at 19:00. Animals injected with epidermal growth factor at 05:00 demonstrated a significant fall in both influx and efflux throughout the 48-h period (P < 0.001), but with preservation of labelling indices, suggesting a slower transit of cells through S-phase, whereas epidermal growth factor injected at 15:00 only produced a significant rise in cell-efflux values. Adrenergic stimulation by intravenous phenylephrine/isoprenaline injection at both 05:00 and 15:00 resulted in a significant rise in cell efflux (P < 0.001), although there was also a rise in labelling index in the 15:00 group (P < 0.001). Animals injected with calmodulin at 05:00 demonstrated a significant reduction in labelling index throughout the 48-h period (P < 0.001), but maintained control values for cell influx and efflux, suggesting faster transit of cells through S. Calmodulin injection at 15:00 produced only a significant reduction in cell influx (P < 0.001). Administration of exogenous growth factors significantly alters the normal rhythmical proliferation of oral epithelial cells in a mouse model. These effects appear to be both growth factor- and time-dependent, and may have both physiological and pathological implications.

Correlation of epidermal growth factor receptor and radiosensitivity in human maxillary carcinoma cell lines

To determine the relationship between epidermal growth factor receptor (EGFR) and radiosensitivity, we immunostained cells from three maxillary carcinoma cell lines with an anti-EGFR antibody. The intensity of staining reactivity, determined by means of an image analysis system, was expressed as grey value (0-black to 255-white). The mean grey values for cell lines IMC-2, IMC-3, and IMC-4 were 181, 210, and 222, respectively, and differed significantly (p < 0.001). This indicates that IMC-2 had the highest number of EGFR, followed by IMC-3 and IMC-4. The cells were then irradiated at 1, 2, 4, or 6 Gy, and cell survival was assessed by means of a standard colony-forming assay. IMC-2 had the highest survival rates at 1, 2 and 4 Gy, followed by IMC-3 and IMC-4. Therefore, the survival rates for IMC-2, IMC-3, and IMC-4 after irradiation increased in proportion to the amount of EGFR in each cell line. These results support the findings of previous clinical studies which showed that increased expression of EGFR was associated with higher recurrence rates of glottic and maxillary sinus carcinoma in patients treated with radiation therapy. The amount of EGFR in cells may therefore be associated with their radiosensitivity.

Cell, tissue and organ culture as in vitro models to study the biology of squamous cell carcinomas of the head and neck

In vitro models are currently being used to study head and neck squamous cell carcinoma (HNSCC). Several hundred HNSCC cell lines have been established by various investigators and used to study a broad spectrum of questions related to head and neck cancer. The head and neck model with respect to multistage carcinogenesis is now complete. Several techniques exist for the culture of normal epithelial cells from the upper aerodigestive tract (UADT). The biology of these UADT cells (oral cavity, oropharynx, hypopharynx and larynx) is being studied. Successful culture of premalignant lesions (dysplastic mucosa, leukoplakia, erythroplakia) has resulted in establishment of a limited number of premalignant cell lines and cell cultures. HPV infection of normal oral epithelial cells for immortalization (approximately premalignant cells) coupled with transformation with carcinogens (malignant cells) has established an experimental model for progression. Two in vivo models for oral carcinogenesis, the 7,12 dimethylbenz(a)anthracene-induced hamster cheek pouch model and the 4-nitroquinoline-N-oxide rat oral model, have been established in culture. Thus, multistage carcinogenesis models have been established from both human tissues and animal models and include cultures of normal, premalignant and malignant cells. Culture techniques for growing dissociated primary tumor cells for short term experimental analysis are being used. The culture of normal or tumor tissue as organ/explant cultures allows for the maintenance of normal cell-cell and cell-matrix interaction, but limits experimentation since these cultures cannot be propagated. Several three dimensional model systems are being used to obtain this histological complexity but allow for experimentation. The ability to culture normal, premalignant and malignant cells coupled with the use of a variety of culture techniques, should allow for the continued growth and experimentation in head and neck cancer research.