A novel 3-dimensional culture system as an in vitro model for studying oral cancer cell invasion

Bex1 significantly contributes to the proliferation and invasiveness of malignant tumor cells

Invasion has a significant role in cancer progression, including expansion to surrounding tissue and metastasis. Previously, we assessed the invasive ability of cancer cells using an easy-to-prepare double-layered collagen gel hemisphere (DL-CGH) method by which cancer cell invasion can be easily visualized. The present study examined multiple lung adenocarcinoma and malignant pleural mesothelioma (MPM) cell lines using the DL-CGH method and identified inherently invasive cell lines. Next, by comparing gene expression between invasive and non-invasive cells by cDNA microarray, the potential candidate gene brain-expressed x-linked protein 1 (Bex1) was identified to be involved in cancer invasion, as it was highly expressed in the invasive cell lines. Downregulation of Bex1 suppressed the invasion and proliferation of the invasive tumor cell lines. The findings of the present study suggested that Bex1 may promote metastasis in vivo and could be a potential oncogene and molecular therapeutic target in lung adenocarcinoma and MPM.

3-D Cell Culture System for Studying Invasion and Evaluating Therapeutics in Bladder Cancer

Bladder cancer is a significant health problem. It is estimated that more than 16,000 people will die this year in the United States from bladder cancer. While 75% of bladder cancers are non-invasive and unlikely to metastasize, about 25% progress to an invasive growth pattern. Up to half of the patients with invasive cancers will develop lethal metastatic relapse. Thus, understanding the mechanism of invasive progression in bladder cancer is crucial to predict patient outcomes and prevent lethal metastases. In this article, we present a three-dimensional cancer invasion model which allows incorporation of tumor cells and stromal components to mimic in vivo conditions occurring in the bladder tumor microenvironment. This model provides the opportunity to observe the invasive process in real time using time-lapse imaging, interrogate the molecular pathways involved using confocal immunofluorescent imaging and screen compounds with the potential to block invasion. While this protocol focuses on bladder cancer, it is likely that similar methods could be used to examine invasion and motility in other tumor types as well.

Human uterus myoma and gene expression profiling: A novel in vitro model for studying secretory leukocyte protease inhibitor-mediated tumor invasion

Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor that diminishes tissue destruction during inflammation. A recent report revealed high levels of SLPI expression in the oral carcinoma cell. In addition, overexpression of SLPI up-regulates metastasis in lung carcinoma cells. On the other hand, matrix metalloproteinases (MMPs) are proteinases that participate in extracellular matrix degradation. SLPI and MMPs are involved as accelerators of the tumor invasion process; however, their exact roles are not fully understood. Understanding the mechanism of tumor invasion requires models that take the effect of microenvironmental factors into account. In one such in vitro model, different carcinoma cells have been shown to invade myoma tissue in highly distinct patterns. We have used this myoma model, as it provides a more natural stroma-like environment, to investigate the role of SLPI in tumor invasion. Our results indicate that the model provides a relevant matrix for tumor invasion studies, and that SLPI is important for the invasion of oral carcinoma Ca9-22 cells in conjunction with MMPs. Furthermore, using bioinformatics analysis, we have identified candidates as key molecules involved in SLPI-mediated tumor invasion.

Hypoxia inducible factor-1 mediates upregulation of urokinase-type plasminogen activator receptor gene transcription during hypoxia in cervical cancer cells

Hypoxia occurs during development of cervical cancer and is considered to correlate with its invasion. Hypoxia mediates tumor cells to have more invasive property in a variety of cancers. Urokinase plasminogen activator receptor (uPAR) which mediates invasion is considered to be induced by hypoxia. We sought to determine the regulators of uPAR expression during hypoxia in cervical cancer. We showed that cervical cancer cell lines, CaSki and CA, were more invasive under hypoxic condition (1% O2) than under normoxic condition (20% O2) by invasion assays. Using western blot analysis, hypoxia enhanced the endogenous hypoxia-inducible factor (HIF)-1α and uPAR protein expression. uPAR mRNA level was also upregulated by hypoxia using real-time RT-PCR. Overexpression of HIF-1α which is induced by hypoxia activated the transcriptional activity of the uPAR promoter by luciferase assays. HIF-1 protein bound the putative HIF-1 response element on the uPAR promoter using electrophoretic mobility shift analysis, and additional luciferase assays show that this is essential for uPAR transactivation by HIF-1. HIF-1 overexpression enhanced the endogenous uPAR expression and introduction of siRNA for HIF-1α diminishes uPAR expression during hypoxia. These results indicate the upregulation of uPAR by hypoxia in cervical cancer cells is mediated through HIF-1. In cervical cancer tissues, we also demonstrated that uPAR protein expression was detected in cervical cancer but not in normal cervix or cervical intraepithelial neoplasia (CIN) by immunohistopathological staining. Our results provide evidence that regulation of uPAR expression by HIF-1 represents a mechanism for cervical cancer invasion during hypoxia.

Migration of breast cancer cells into reconstituted type I collagen gels assessed via a combination of frozen sectioning and azan staining

This study sought to devise a way to assess the infiltration of cancer cells in model stromal tissues. Human breast carcinoma MDA-MB-231 cells were loaded on the surface of a type I collagen gel in the well of 8-well chamber slide and allowed to migrate into the gel. The gel was then subjected to frozen sectioning and staining. Azan staining facilitated satisfactory microscopic observation of cancer cells migrating into the collagen gel. Cell migration was promoted by the presence of fetal calf serum in the gel. In contrast, the proportion of cells remaining on the gel surface increased in the presence of galardin, a matrix metalloproteinase inhibitor. Moreover, the distance of cell migration from the gel surface was significantly shorter depending on the concentration of galardin. Observation of cancer cell migration into reconstituted type I collagen gel with a combination of frozen sectioning and azan staining is a useful way to assess the ability of individual cancer cells to migrate and to evaluate how effectively pharmaceuticals inhibit the first step of invasion.

A three-dimensional tissue culture model to study primary human bone marrow and its malignancies

Tissue culture has been an invaluable tool to study many aspects of cell function, from normal development to disease. Conventional cell culture methods rely on the ability of cells either to attach to a solid substratum of a tissue culture dish or to grow in suspension in liquid medium. Multiple immortal cell lines have been created and grown using such approaches, however, these methods frequently fail when primary cells need to be grown ex vivo. Such failure has been attributed to the absence of the appropriate extracellular matrix components of the tissue microenvironment from the standard systems where tissue culture plastic is used as a surface for cell growth. Extracellular matrix is an integral component of the tissue microenvironment and its presence is crucial for the maintenance of physiological functions such as cell polarization, survival, and proliferation. Here we present a 3-dimensional tissue culture method where primary bone marrow cells are grown in extracellular matrix formulated to recapitulate the microenvironment of the human bone (rBM system). Embedded in the extracellular matrix, cells are supplied with nutrients through the medium supplemented with human plasma, thus providing a comprehensive system where cell survival and proliferation can be sustained for up to 30 days while maintaining the cellular composition of the primary tissue. Using the rBM system we have successfully grown primary bone marrow cells from normal donors and patients with amyloidosis, and various hematological malignancies. The rBM system allows for direct, in-matrix real time visualization of the cell behavior and evaluation of preclinical efficacy of novel therapeutics. Moreover, cells can be isolated from the rBM and subsequently used for in vivo transplantation, cell sorting, flow cytometry, and nucleic acid and protein analysis. Taken together, the rBM method provides a reliable system for the growth of primary bone marrow cells under physiological conditions.

Comparison of human chordoma cell-kill for 290 MeV/n carbon ions versus 70 MeV protons in vitro

BACKGROUND

While the pace of commissioning of new charged particle radiation therapy facilities is accelerating worldwide, biological data pertaining to chordomas, theoretically and clinically optimally suited targets for particle radiotherapy, are still lacking. In spite of the numerous clinical reports of successful treatment of these malignancies with this modality, the characterization of this malignancy remains hampered by its characteristic slow cell growth, particularly in vitro.

METHODS

Cellular lethality of U-CH1-N cells in response to different qualities of radiation was compared with immediate plating after radiation or as previously reported using the multilayered OptiCell™ system. The OptiCell™ system was used to evaluate cellular lethality over a broad dose-depth deposition range of particle radiation to anatomically mimic the clinical setting. Cells were irradiated with either 290 MeV/n accelerated carbon ions or 70 MeV accelerated protons and photons and evaluated through colony formation assays at a single position or at each depth, depending on the system.

RESULTS

There was a cell killing of approximately 20-40% for all radiation qualities in the OptiCell™ system in which chordoma cells are herein described as more radiation sensitive than regular colony formation assay. The relative biological effectiveness values were, however, similar in both in vitro systems for any given radiation quality. Relative biological effectiveness values of proton was 0.89, of 13-20 keV/μm carbon ions was 0.85, of 20-30 keV/μm carbon ions was 1.27, and >30 keV/μm carbon ions was 1.69. Carbon-ions killed cells depending on both the dose and the LET, while protons depended on the dose alone in the condition of our study. This is the first report and characterization of a direct comparison between the effects of charged particle carbon ions versus protons for a chordoma cell line in vitro. Our results support a potentially superior therapeutic value of carbon particle irradiation in chordoma patients.

CONCLUSION

Carbon ion therapy may have an advantage for chordoma radiotherapy because of higher cell-killing effect with high LET doses from biological observation in this study.

AlgiMatrix™ based 3D cell culture system as an in-vitro tumor model for anticancer studies

Background

Three-dimensional (3D) in-vitro cultures are recognized for recapitulating the physiological microenvironment and exhibiting high concordance with in-vivo conditions. Taking the advantages of 3D culture, we have developed the in-vitro tumor model for anticancer drug screening.

Methods

Cancer cells grown in 6 and 96 well AlgiMatrix™ scaffolds resulted in the formation of multicellular spheroids in the size range of 100–300 µm. Spheroids were grown in two weeks in cultures without compromising the growth characteristics. Different marketed anticancer drugs were screened by incubating them for 24 h at 7, 9 and 11 days in 3D cultures and cytotoxicity was measured by AlamarBlue® assay. Effectiveness of anticancer drug treatments were measured based on spheroid number and size distribution. Evaluation of apoptotic and anti-apoptotic markers was done by immunohistochemistry and RT-PCR. The 3D results were compared with the conventional 2D monolayer cultures. Cellular uptake studies for drug (Doxorubicin) and nanoparticle (NLC) were done using spheroids.

Results

IC₅₀ values for anticancer drugs were significantly higher in AlgiMatrix™ systems compared to 2D culture models. The cleaved caspase-3 expression was significantly decreased (2.09 and 2.47 folds respectively for 5-Fluorouracil and Camptothecin) in H460 spheroid cultures compared to 2D culture system. The cytotoxicity, spheroid size distribution, immunohistochemistry, RT-PCR and nanoparticle penetration data suggested that in vitro tumor models show higher resistance to anticancer drugs and supporting the fact that 3D culture is a better model for the cytotoxic evaluation of anticancer drugs in vitro.

Conclusion

The results from our studies are useful to develop a high throughput in vitro tumor model to study the effect of various anticancer agents and various molecular pathways affected by the anticancer drugs and formulations.

Two-dimensional vs. three-dimensional in vitro tumor migration and invasion assays

Motility and invasion are key hallmarks that distinguish benign from malignant tumors, enabling cells to cross tissue boundaries, disseminate in blood and lymph and establish metastases at distant sites. Similar properties are also utilized by activated endothelial cells during tumor-induced angiogenesis. It is now appreciated that these processes might provide a rich source of novel molecular targets with the potential for inhibitors to restrain both metastasis and neoangiogenesis. Such therapeutic strategies require assays that can rapidly and quantitatively measure cell movement and the ability to traverse physiological barriers. The need for high-throughput, however, must be balanced by assay designs that accommodate, as far as possible, the complexity of the in vivo tumor microenvironment. This chapter aims to give an overview of some commonly used migration and invasion assays to aid in the selection of a balanced portfolio of techniques for the rapid and accurate evaluation of novel therapeutic agents.

Tissue inhibitor of metalloproteinases in oral squamous cell carcinomas - a therapeutic target?

Matrix metalloproteinases (MMPs) are proteases responsible for remodeling the extracellular matrix (ECM) and enabling spreading and metastasis of tumor cells, a common phenomenon in oral squamous cell carcinomas (OSCC). They are strongly blocked by several inhibitors, among which we must highlight, for their specificity and potency, the endogenous tissue inhibitors of metalloproteinases (TIMP-1, -2, -3 and -4). The goal of this paper is to describe the expression of TIMPs in OSCC, determining their relation with clinical, histological and prognostic factors, delving into OSCC regulation mechanisms and discussing the use of exogenous TIMPs to treat this type of tumors. Expression of TIMPs in OSCC is higher in tumors than in normal tissue, which correlates with an increase of metastatic risk and regional lymph node affectation. Although some metalloproteinases inhibitors (MMIs) have shown promising results in the treatment of these tumors, their use in OSCC has not been widely tested; and although some indirect MMIs, like COX-2 inhibitors, flavonoids and endostatin seem to have beneficial effects on the invasive capacity of OSCC through regulation of MMPs and TIMP levels, routine clinical use has not been accepted yet.

Invasion of carcinoma cells into reconstituted type I collagen gels: visual real-time analysis by time-lapse microscopy

Stromal-epithelial interactions play a critical role in promoting tumorigenesis and invasion. To obtain detailed information on cancer cell behaviors on the stroma and kinetics of cell migration, which cannot be observed by conventionally-used Boyden chamber assays, this study was aimed at analyzing the cell invasion process in vitro using time-lapse microscopic observation. Serum-free conditions and reconstituted type I collagen gels which provided a basal membrane-stroma-like microenvironment were used to first establish a basal condition. Time-lapse microscopic observation for 30 h of cell invasion into the collagen gel revealed kinetic parameters and individualistic behavior of cancer cells. Of breast cancer MDA-MB-231 or MCF-7 cells and colon cancer LS180 or HT29 cells examined, MDA-MB-231 cells most rapidly disappeared from the collagen gel surface under basal conditions. Estrogen-dependent MCF-7 cells disappeared at a rate approximately two times slower than that of MDA-MB-231 cells under serum- and phenol red-free conditions. By the addition of 10 nM β-estradiol to the basal medium, MCF-7 cell invasion was facilitated to a rate similar to that of MDA-MB-231 cells. Microscopic analyses of collagen gel-sections demonstrated that most of the MDA-MB-231 and MCF-7 cells remained within 60 μm from the gel top under basal conditions, which is consistent with the observation obtained using Boyden chambers that no cells could cross the collagen I gel barrier unless 1% fetal calf serum was added to basal conditions. In summary, this study demonstrated future applicability of this method to understand the initial phase of cancer cell invasion processes.

MT1-MMP plays an important role in an invasive activity of malignant pleural mesothelioma cell

Malignant pleural mesothelioma (MPM) has a poor prognosis and is a treatment resistant tumor, which is increasing in frequency throughout the world. The poor prognosis is due to the aggressive local invasiveness rather than distant metastasis. In this study, we established a cell line of malignant mesothelioma from a clinical specimen and assessed the relationship between the expression of MT1-MMP and the invasion ability of that line, as well as the cultured cells of several other lines, using the simple method that we created previously. We established a cell line from a clinical specimen from a patient with malignant mesothelioma. We assessed the invasive activities of MPM cells in an easy-to-prepare double-layered collagen gel hemisphere (DL-CGH) system that enabled us to visualize cell movements during invasion. To assess the role of MT1-MMP in the invasive activity of MPM cells, we knocked down its expression by RNA interference (RNAi). The invasion assay with DL-CGH revealed that a high expression of MT1-MMP in MPM cells was associated with aggressive invasive activity. The RNAi of MT1-MMP indicated that the expression of MT1-MMP might have a crucial role in the invasiveness of MPM cells. The MT1-MMP expression in MPM cells is related to their capacity for locally aggressive spreading into the pleura and the surrounding tissues, and MT1-MMP should be a suitable molecular target for the suppression of the invasiveness of MPM.

Applications of a new In vivo tumor spheroid based shell-less chorioallantoic membrane 3-D model in bioengineering research

The chicken chorioallantoic membrane (CAM) is a classical in vivo biological model in studies of angiogenesis. Combined with the right tumor system and experimental configuration this classical model can offer new approaches to investigating tumor processes. The increase in development of biotechnological devices for cancer diagnosis and treatment, calls for more sophisticated tumor models that can easily adapt to the technology, and provide a more accurate, stable and consistent platform for rapid quantitative and qualitative analysis. As we discuss a variety of applications of this novel in vivo tumor spheroid based shell-less CAM model in biomedical engineering research, we will show that it is extremely versatile and easily adaptable to an array of biomedical applications. The model is particularly useful in quantitative studies of the progression of avascular tumors into vascularized tumors in the CAM. Its environment is more stable, flat and has a large working area and wider field of view excellent for imaging and longitudinal studies. Finally, rapid data acquisition, screening and validation of biomedical devices and therapeutics are possible with the short experimental window.

Organotypic human oral tissue models for toxicological studies

Three-dimensional models of the human oral epithelia have been developed to test the irritation of oral-care products and to provide systems to study the pathology of the oral cavity. The in vitro tissue models, cultured using normal oral epithelial cells and serum free medium, adopt a buccal or gingival phenotype. The buccal tissue (designated ORL-200) is 8-12 cell layers thick and non-cornified; the gingival tissue (designated GIN-100) is 9-13 layers thick and cornified at the apical surface. The tissues express cytokeratins 13 and 14 similar to their corresponding native oral tissues. The MTT viability assay was used to assess inter-lot and intra-lot reproducibility. The MTT average intra-lot coefficient of variation (CV) was less than 10% for both tissues and the time required to reduce tissue viability by 50% (ET-50) following application of 1% Triton-X 100 averaged 1.02+/-0.33 h (n=26) and 7.97+/-0.80 h (n=14) for the buccal and gingival tissues, respectively. The utility of the buccal tissue for irritation studies was examined by testing prototype dentifrice formulations and commercially available products including mouthwashes, toothpastes, and oral cleansers. Use of the MTT ET-50 assay and cytokine release clearly differentiated between the formulations and the oral care products. In conclusion, the oral tissue models represent highly reproducible, non-animal means to screen the irritation potential of newly developed oral care products and should be useful to study the innate immunity, biology, and pathology of the oral mucosa.

Matrix metalloproteinase-7 and epidermal growth factor receptor mediate hypoxia-induced extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase activation and subsequent proliferation in bladder smooth muscle cells

Low oxygen tension (hypoxia) has been implicated in proliferation of vascular smooth muscle cells (SMCs) of the lung. Tissue hypoxia also occurs in the obstructed bladder. The extracellular-regulated kinase mitogen-activated protein kinase 1/2 (Erk1/2) pathway is induced in many cell types during hypoxia. We examined whether hypoxia (3% O2), compared with normoxia (21% O2), induces proliferation responses and activation of the Erk1/2 pathways in primary rat bladder smooth muscle cells (BSMCs). We show that hypoxia induces proliferation of BSMCs at 18 h and, although reduced at 22 h, still remained above normoxic levels. Hypoxia induced a strikingly transient activation of Erk1/2 that lasted only 10-30 min. However, inhibition of the transient Erk1/2 activity with a specific mitogen-activated protein kinase kinase 1 (MEK-1) inhibitor PD 98059 prevented subsequent hypoxia-induced proliferation at 18 h. Interestingly, inhibition of general matrix metalloproteinase (MMP) activity, using either doxycycline or GM 6001, prevented both transient Erk1/2 activity and subsequent proliferation in response to hypoxia. Furthermore, MMP-7 (matrilysin) is activated in the conditioned medium (CM) of BSMCs at 10-20 min of hypoxia. In addition, MMP-7 was also transcriptionally induced at 6 h of hypoxia in an Erk1/2-dependent manner. Moreover, transient Erk1/2 activation and BSMC proliferation were both dependent on epidermal growth factor receptor (EGFR/HER1) but not neu receptor (HER2/ERB2) autophosphorylation. We conclude that hypoxia leads to Erk1/2 activation, which appears to modulate BSMC proliferation through MMP-7-and EGFR-mediated mechanisms.