Lipopolysaccharide can modify differentiation and immunomodulatory potential of periodontal ligament stem cells via ERK1,2 signaling.

Lipopolysaccharide (LPS) is a pertinent deleterious factor in oral microenvironment for cells which are carriers of regenerative processes. The aim of this study was to investigate the emerging in vitro effects of LPS (Escherichia coli) on human periodontal ligament stem cell (PDLSC) functions and associated signaling pathways. We demonstrated that LPS did not affect immunophenotype, proliferation, viability, and cell cycle of PDLSCs. However, LPS modified lineage commitment of PDLSCs inhibiting osteogenesis by downregulating Runx2, ALP, and Ocn mRNA expression, while stimulating chondrogenesis and adipogenesis by upregulating Sox9 and PPARγ mRNA expression. LPS promoted myofibroblast-like phenotype of PDLSCs, since it significantly enhanced PDLSC contractility, as well as protein and/or gene expression of TGF-ß, fibronectin (FN), α-SMA, and NG2. LPS also increased protein and gene expression levels of anti-inflammatory COX-2 and pro-inflammatory IL-6 molecules in PDLSCs. Inhibition of peripheral blood mononuclear cells (MNCs) transendothelial migration in presence of LPS-treated PDLSCs was accompanied by the reduction of CD29 expression within MNCs. However, LPS treatment did not change the inhibitory effect of PDLSCs on mitogen-stimulated proliferation of CD4+ and the ratio of CD4+ CD25high /CD4+ CD25low lymphocytes. LPS-treated PDLSCs did not change the frequency of CD34+ and CD45+ cells, but decreased the frequency of CD33+ and CD14+ myeloid cells within MNCs. Moreover, LPS treatment attenuated the stimulatory effect of PDLSCs on CFC activity of MNCs, predominantly the CFU-GM number. The results indicated that LPS-activated ERK1,2 was at least partly involved in the observed effects on PDLSC differentiation capacity, acquisition of myofibroblastic attributes, and changes of their immunomodulatory features.

Inflammatory cytokines prime adipose tissue mesenchymal stem cells to enhance malignancy of MCF-7 breast cancer cells via transforming growth factor-ß1.

Mesenchymal stem cells from human adipose tissue (hASCs) are proposed as suitable tools for soft tissue engineering and reconstruction. Although it is known that hASCs have the ability to home to sites of inflammation and tumor niche, the role of inflammatory cytokines in the hASCs-affected tumor development is not understood. We found that interferon-γ (IFN-γ) and/or tumor necrosis factor-α (TNF-α) prime hASCs to produce soluble factors which enhance MCF-7 cell line malignancy in vitro. IFN-γ and/or TNF-α-primed hASCs produced conditioned media (CM) which induced epithelial to mesenchymal transition (EMT) of MCF-7 cells by reducing E-Cadherin and increasing Vimentin expression. Induced EMT was accompanied by increased invasion, migration, and urokinase type-plasminogen activator (uPA) expression in MCF-7 cells. These effects were mediated by increased expression of transforming growth factor-ß1(TGF-ß1) in cytokines-primed hASCs, since inhibition of type I TGF-ß1 receptor on MCF-7 cells and neutralization of TGF-ß1 disabled the CM from primed hASCs to increase EMT, cell migration, and uPA expression in MCF-7 cells. Obtained data suggested that IFN-γ and/or TNF-α primed hASCs might enhance the malignancy of MCF-7 cell line by inducing EMT, cell motility and uPA expression in these cells via TGF-ß1-Smad3 signalization, with potentially important implications in breast cancer progression.

The Roles of Mesenchymal Stromal/Stem Cells in Tumor Microenvironment Associated with Inflammation.

State of tumor microenvironment (TME) is closely linked to regulation of tumor growth and progression affecting the final outcome, refractoriness, and relapse of disease. Interactions of tumor, immune, and mesenchymal stromal/stem cells (MSCs) have been recognized as crucial for understanding tumorigenesis. Due to their outstanding features, stem cell-like properties, capacity to regulate immune response, and dynamic functional phenotype dependent on microenvironmental stimuli, MSCs have been perceived as important players in TME. Signals provided by tumor-associated chronic inflammation educate MSCs to alter their phenotype and immunomodulatory potential in favor of tumor-biased state of MSCs. Adjustment of phenotype to TME and acquisition of tumor-promoting ability by MSCs help tumor cells in maintenance of permissive TME and suppression of antitumor immune response. Potential utilization of MSCs in treatment of tumor is based on their inherent ability to home tumor tissue that makes them suitable delivery vehicles for immune-stimulating factors and vectors for targeted antitumor therapy. Here, we review data regarding intrusive effects of inflammatory TME on MSCs capacity to affect tumor development through modification of their phenotype and interactions with immune system.

Doxycycline Inhibits IL-17-Stimulated MMP-9 Expression by Downregulating ERK1/2 Activation: Implications in Myogenic Differentiation.

Interleukin 17 (IL-17) is a cytokine with pleiotropic effects associated with several inflammatory diseases. Although elevated levels of IL-17 have been described in inflammatory myopathies, its role in muscle remodeling and regeneration is still unknown. Excessive extracellular matrix degradation in skeletal muscle is an important pathological consequence of many diseases involving muscle wasting. In this study, the role of IL-17 on the expression of matrix metalloproteinase- (MMP-) 9 in myoblast cells was investigated. The expression of MMP-9 after IL-17 treatment was analyzed in mouse myoblasts C2C12 cell line. The increase in MMP-9 production by IL-17 was concomitant with its capacity to inhibit myogenic differentiation of C2C12 cells. Doxycycline (Doxy) treatment protected the myogenic capacity of myoblasts from IL-17 inhibition and, moreover, increased myotubes hypertrophy. Doxy blocked the capacity of IL-17 to stimulate MMP-9 production by regulating IL-17-induced ERK1/2 MAPK activation. Our results imply that MMP-9 mediates IL-17's capacity to inhibit myoblast differentiation during inflammatory diseases and indicate that Doxy can modulate myoblast response to inflammatory induction by IL-17.

Characteristics of human adipose mesenchymal stem cells isolated from healthy and cancer affected people and their interactions with human breast cancer cell line MCF-7 in vitro.

Adipose tissue is an attractive source of mesenchymal stem/stromal cells (MSCs) with potential applications in reconstructive plastic surgery and regenerative medicine. The aim of this study was to characterise human adipose tissue MSCs (ASCs) derived from healthy individuals and cancer patients and to compare their interactions with tumour cells. ASCs were isolated from adipose tissue of healthy donors, breast cancer-adjacent adipose tissue of breast cancer patients and tumour-adjacent adipose tissue of non-breast cancer patients. Their proliferation, differentiation, immunophenotype and gene expression were assessed and effects on the proliferation of human breast cancer cell line MCF-7 compared. ASCs from all sources exhibited similar morphology, proliferative and differentiation potential, showing the characteristic pattern of mesenchymal surface markers expression (CD90, CD105, CD44H, CD73) and the lack of HLA-DR and hematopoietic markers (CD11a, CD33, CD45, Glycophorin-CD235a), but uneven expression of CD34. ASCs also shared a common positive gene expression of HLA-DR, HLA-A, IL-6, TGF-ß and HIF-1, but were negative for HLA-G, while the expression levels of Cox-2 and IDO-1 varied. All ASCs significantly stimulated the proliferation of MCF-7 tumour cells in direct mixed co-cultures and transwell system, although their conditioned media displayed antiproliferative activity. Data obtained showed that ASCs with similar characteristics are easily isolated from various donors and sites of origin, although ASCs could both suppress and favour tumour cells growth, emphasising the importance of cellular context within the microenvironment and pointing to the significance of safety studies to exclude any potential clinical risk of their application in regenerative medicine.

Recovery of brain cholinesterases and effect on parameters of oxidative stres and apoptosis in quails (Coturnix japonica) after chlorpyrifos and vitamin B1 administration.

Chlorpyrifos is a extensively used organophosphate pesticide (OP). In this study, we closely looked into neurotoxicity of CPF and effect of vitamin B1, by checking the levels of cholinesterases, determining the activity of parameters of oxidative stress, inflammation and also level of apoptotic regulator. The study was performed on a total of 80 male Japanese quails (Coturnix japonica), (two control and 6 experimental groups, n = 10). Three group of quails were given by gavage chlorpyrifos (CPF) for 7 consecutive days at doses of 1.50 mg/kg b.w., 3.00 mg/kg b.w., and 6.00 mg/kg b.w. Another three groups were treated with 10 mg/kg b.w. of vitamin B1 i.m. 30 min after CPF application (in above mentioned doses). Our study have proved that all doses of CPF significantly inhibited cholinesterases in brain, while vitamin B1 reactivated them. CPF has led to an increase in the concentration of malondialdehyde (MDA), and activity of catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), while tiamin changed the activity of antioxidant enzymes: CAT, SOD, GST. CPF stimulated apoptosis by decreasing B-cell lymphoma (Bcl-2) in brain, while application of vitamin B1 caused an increase of this parameter. CPF amplified inflammatory effect by elevating levels of inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX-2). Thiamine proved its anti-inflammatory property by decreasing the expression of iNOS and interleukin-1(IL-1) and interleukin-6(IL-6). This study is highly pertinent because there is little defense currently available to humans and animals to prevent toxic effects of pesticides.

Differential expansion of circulating human MDSC subsets in patients with cancer, infection and inflammation.

BACKGROUND: Myeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that includes myeloid cells with immune suppressive properties. The presence of MDSC has been reported in the peripheral blood of patients with several malignant and non-malignant diseases. So far, direct comparison of MDSC across different diseases and Centers is hindered by technical pitfalls and a lack of standardized methodology. To overcome this issue, we formed a network through the COST Action Mye-EUNITER (www.mye-euniter.eu) with the goal to standardize and facilitate the comparative analysis of human circulating MDSC in cancer, inflammation and infection. In this manuscript, we present the results of the multicenter study Mye-EUNITER MDSC Monitoring Initiative, that involved 13 laboratories and compared circulating MDSC subsets across multiple diseases, using a common protocol for the isolation, identification and characterization of these cells. METHODS: We developed, tested, executed and optimized a standard operating procedure for the isolation and immunophenotyping of MDSC using blood from healthy donors. We applied this procedure to the blood of almost 400 patients and controls with different solid tumors and non-malignant diseases. The latter included viral infections such as HIV and hepatitis B virus, but also psoriasis and cardiovascular disorders. RESULTS: We observed that the frequency of MDSC in healthy donors varied substantially between centers and was influenced by technical aspects such as the anticoagulant and separation method used. Expansion of polymorphonuclear (PMN)-MDSC exceeded the expansion of monocytic MDSC (M-MDSC) in five out of six solid tumors. PMN-MDSC expansion was more pronounced in cancer compared with infection and inflammation. Programmed death-ligand 1 was primarily expressed in M-MDSC and e-MDSC and was not upregulated as a consequence of disease. LOX-1 expression was confined to PMN-MDSC. CONCLUSIONS: This study provides improved technical protocols and workflows for the multi-center analysis of circulating human MDSC subsets. Application of these workflows revealed a predominant expansion of PMN-MDSC in solid tumors that exceeds expansion in chronic infection and inflammation.

Structural antitumoral activity relationships of synthetic chalcones.

Relationships between the structural characteristic of synthetic chalcones and their antitumoral activity were studied. Treatment of HepG2 cells for 24 h with synthetic 2'-hydroxychalcones resulted in apoptosis induction and dose-dependent inhibition of cell proliferation. The calculated reactivity indexes and the adiabatic electron affinities using the DFT method including solvent effects, suggest a structure-activity relationship between the Chalcones structure and the apoptosis in HepG2 cells. The absence of methoxy substituents in the B ring of synthetic 2'-hydroxychalcones, showed the mayor structure-activity pattern along the series.

Myeloid-Derived Suppressor Cells in Hematologic Diseases: Promising Biomarkers and Treatment Targets.

Myeloid-derived suppressor cells (MDSC) are a heterogeneous group of immature myeloid cells that exist at very low numbers in healthy subjects but can expand significantly in malignant, infectious, and chronic inflammatory diseases. These cells are characterized as early-MDSCs, monocytic-MDSCs, and polymorphonuclear-MDSCs and can be studied on the basis of their immunophenotypic characteristics and their functional properties to suppress T-cell activation and proliferation. MDSCs have emerged as important contributors to tumor expansion and chronic inflammation progression by inducing immunosuppressive mechanisms, angiogenesis and drug resistance. Most experimental and clinical studies concerning MDSCs have been mainly focused on solid tumors. In recent years, however, the implication of MDSCs in the immune dysregulation associated with hematologic malignancies, immune-mediated cytopenias and allogeneic hemopoietic stem cell transplantation has been documented and the potential role of these cells as biomarkers and therapeutic targets has started to attract a particular interest in hematology. The elucidation of the molecular and signaling pathways associated with the generation, expansion and function of MDSCs in malignant and immune-mediated hematologic diseases and the clarification of mechanisms related to the circulation and the crosstalk of MDSCs with malignant cells and other components of the immune system are anticipated to lead to novel therapeutic strategies. This review summarizes all available evidence on the implication of MDSCs in hematologic diseases highlighting the challenges and perspectives arising from this novel field of research.

Hyperosmotic stress-dependent NFkappaB activation is regulated by reactive oxygen species and IGF-1 in cultured cardiomyocytes.

We have recently shown that hyperosmotic stress activates p65/RelB NFkappaB in cultured cardiomyocytes with dichotomic actions on caspase activation and cell death. It remains unexplored how NFkappaB is regulated in cultured rat cardiomyocytes exposed to hyperosmotic stress. We study here: (a) if hyperosmotic stress triggers reactive oxygen species (ROS) generation and in turn whether they regulate NFkappaB and (b) if insulin-like growth factor-1 (IGF-1) modulates ROS production and NFkappaB activation in hyperosmotically-stressed cardiomyocytes. The results showed that hyperosmotic stress generated ROS in cultured cardiac myocytes, in particular the hydroxyl and superoxide species, which were inhibited by N-acetylcysteine (NAC). Hyperosmotic stress-induced NFkappaB activation as determined by IkappaBalpha degradation and NFkappaB DNA binding. NFkappaB activation and procaspase-3 and -9 fragmentation were prevented by NAC and IGF-1. However, this growth factor did not decrease ROS generation induced by hyperosmotic stress, suggesting that its actions over NFkappaB and caspase activation may be due to modulation of events downstream of ROS generation. We conclude that hyperosmotic stress induces ROS, which in turn activates NFkappaB and caspases. IGF-1 prevents NFkappaB activation by a ROS-independent mechanism.

Mesenchymal stem cells of different origin: Comparative evaluation of proliferative capacity, telomere length and pluripotency marker expression.

AIMS: In vitro expansion changes replication and differentiation capacity of mesenchymal stem cells (MSCs), increasing challenges and risks, while limiting the sufficient number of MSCs required for cytotherapy. Here, we characterized and compared proliferation, differentiation, telomere length and pluripotency marker expression in MSCs of various origins. MAIN METHODS: Immunophenotyping, proliferation and differentiation assays were performed. Pluripotency marker (Nanog, Oct-4, SOX-2, SSEA-4) expression was determined by immunofluorescence. Quantitative PCR was performed for relative telomere length (RTL) analyses, while expression of relevant genes for pluripotency markers, differentiation state (Cbfa1, human placental alkaline phosphatase, peroxisome proliferator activated receptor, Sox9 and Collagen II a1), and telomerase reverse transcriptase (hTERT) was determined by semiquantitative RT-PCR. KEY FINDINGS: Peripheral blood MSCs (PB-MSCs) and umbilical cord MSCs (UC-MSCs) showed the highest, while periodontal ligament MSCs (PDL-MSCs) and adipose tissue MSCs (AT-MSCs) the lowest values of both the replication potential and RTL. Although MSCs from exfoliated deciduous teeth (SHEDs), PDL-MSCs and AT-MSCs showed higher mRNA expression of pluripotency markers, all MSCs expressed pluripotency marker proteins. SHEDs and PDL-MSCs showed prominent capacity for osteogenesis, PB-MSCs and UC-MSCs showed strengthened adipogenic differentiation potential, while AT-MSCs displayed similar differentiation into both lines. SIGNIFICANCE: The MSCs populations derived from different sources, although displaying similar phenotype, exhibited high degree of variability regarding biological properties related to their self-renewal and differentiation capacity. These data indicate that for more accurate use in cell therapy, individualities of MSCs isolated from different tissues should be identified and taken into consideration when planning their use in clinical protocols.

TGF-beta(1) and Smad4 overexpression induce a less invasive phenotype in highly invasive spindle carcinoma cells.

We have examined the effect of transforming growth factor beta(1) (TGF-beta(1)) and overexpression of the Smad4 gene on the phenotype of Car C, a ras mutated highly malignant spindle carcinoma cell line. TGF-beta(1)-treated Car C cells overexpressing Smad4 spread with a flattened morphology with membrane ruffles abundant in vinculin and show a reduction in their invasive abilities. TGF-beta(1) treatment and overexpression of Smad4 also enhanced the production of PAI-1 measured by the activation of the p3TP-lux reporter gene containing a PAI-1-related promoter. This activation was abolished with a dominant-negative Smad4 construct. These results lead us to conclude that both TGF-beta(1) and Smad4 overexpression reduce the invasive potential of Car C cells, probably via the Smad pathway.

Mesenchymal stem cells isolated from peripheral blood and umbilical cord Wharton's jelly.

INTRODUCTION: Mesenchymal stem cells (MSCs) are a promising tool for regenerative medicine, but due to the heterogeneity of their populations, different sources and isolation techniques, the characteristics defining MSCs are inconsistent. OBJECTIVE: The aim of this study was to compare the characteristics of MSCs derived from two different human tissues: peripheral blood (PB-MSCs) and umbilical cord Wharton's Jelly (UC-MSCs). METHODS: The PB-MSC and UC-MSC were isolated by adherence to plastic after gradient-density separation or an explant culture method, respectively, and compared regarding their morphology, clonogenic efficiency, proliferating rates, immunophenotype and differentiation potential. RESULTS: MSCs derived from both sources exhibit similar morphology, proliferation capacity and multilineage (osteogenic, chondrogenic, adipogenic and myogenic) differentiation potential. Differences were observed in the clonogenic capacity and the immunophenotype, since UC-MSCs showed higher CFU-F (colony-forming units-fibroblastic) cloning efficiency, as well as higher embryonic markers (Na-nog, Sox2, SSEA4) expression. When additional surface antigens were analyzed by flow cytometry (CD44, CD90, CD105, CD33, CD34, CD45, CD11b, CD235a) or immunofluorescent labeling (vimentin, STRO-1 and alpha-smooth muscle actin), most appeared to have similar epitope profiles irrespective of MSC source. CONCLUSION: The results obtained demonstrated that both MSCs represent good alternative sources of adult MSCs that could be used in cell therapy applications.

Synthesis, structural and spectroscopic characterization, in vitro cytotoxicity and in vivo activity as free radical scavengers of chlorido(p-cymene) complexes of ruthenium(II) containing N-alkylphenothiazines.

Three new ruthenium(II) complexes 1-3 containing N-alkylphenothiazine molecules were synthesized by reaction of [RuCl(2)(η(6)-p-cymene)](2) with chlorpromazine hydrochloride (1), trifluoperazine dihydrochloride (2) or thioridazine hydrochloride (3). The compounds of the general formula L[RuCl(3)(η(6)-p-cymene)] were characterized by elemental analysis and spectroscopic methods (FT-IR, UV-Vis, (1)H and (13)C NMR). Complex 2 was structurally characterized by single crystal X-ray diffraction. In vitro cytotoxic activity of complexes 1-3 were assayed in four human carcinoma cell lines MCF-7, MDA-MB-453 (breast carcinoma), SW-480 (colon carcinoma) and IM9 (myeloma multiple cells). The highest cytotoxicity (12.1 ≤ IC(50) ≤ 17.3 µM) and induced a total (SW-480) or almost total cell death (MCF-7, MDA-MB-453) at 25 µM in 48 h of treatment were observed for complex 2. The influence of three different doses (0.4, 4.5 and 90.4 µM/kg bw) of complex 2 on activities of antioxidants enzymes (superoxide dismutase (SOD) and catalase (CAT)) and lactate dehydrogenase (LDH) were investigated under physiological conditions. The effects on nitrite production (NO(2)(-)) and level of erythrocytes malondialdehyde (MDA) in rats blood were evaluated, too.

New ruthenium(II) complexes with N-alkylphenothiazines: synthesis, structure, in vivo activity as free radical scavengers and in vitro cytotoxicity.

Three new complexes of the general formula L[RuCl(3)(DMSO)(3)] (1-3), where L = chlorpromazine hydrochloride, trifluoroperazine dihydrochloride or thioridazine hydrochloride, were prepared and characterized by elemental analysis and spectroscopic methods (FT-IR, UV-Vis, (1)H NMR and (13)C NMR). In addition, the crystal structure of the complex 2 containing trifluoroperazine dihydrochloride was solved by single crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group P2(1)/n, with a = 10.4935(7) A, b = 18.6836(12) A, c = 19.9250(13) A, beta = 98.448(2) degrees, V = 3864.0(4) A(3). The structure was refined to the agreement factors of R = 4.79%, R(w) = 11.23%. The effect of three different doses (0.4, 4.5 and 90.4 microM/kg bw) of complex 2 on superoxide dismutase (SOD) and catalase (CAT) activity was investigated under physiological conditions. Influence on nitrite production (NO(2)(-)) and the level of erythrocytes malondialdehyde (MDA) in rats blood was also evaluated. Complex 2 did not affect the CAT enzyme activity in vivo and did not cause the hydroxyl radicals production. In the 0.4 and 4.5 microM/kg bw doses it showed almost the same or lower SOD activity and nitrite levels, while the dose of 90.4 microM/kg bw significantly increased these parameters. Finally, the cytotoxicity of complexes were assayed in four human carcinoma cell lines MCF-7, MDA-MB-453 (breast carcinoma), SW-480 (colon adenocarcinoma) and IM9 (myeloma multiple cells). Antiproliferative activity in vitro with low IC(50) during 48 h of treatment was observed.

EGF receptor transactivation by urokinase receptor stimulus through a mechanism involving Src and matrix metalloproteinases.

Urokinase-type plasminogen activator receptor (uPAR) and epidermal growth factor receptor (EGFR) are ubiquitous receptors involved in the control of a variety of cellular processes frequently found altered in cancer cells. The EGFR has been recently described to play a transduction role of uPAR stimuli, mediating uPA-induced proliferation in highly malignant cells that overexpress uPAR. In the present work, we found for the first time that uPAR stimulation with the amino-terminal fragment (ATF) of urokinase devoid of proteolytic activity transactivates the EGFR in mammary MCF-7 cells through a mechanism involving Src and a metalloproteinase, as indicated by its sensitivity to selected inhibitors. In these cells, which express low levels of uPAR and malignancy, both ATF and EGF stimuli induced an interaction of the EGFR with uPAR and ERK activation. However, EGFR activation by uPAR stimuli mediated cellular invasion rather than proliferation, while EGFR activation by EGF led to a proliferative response. These results revealed a complex modulation of EGFR function toward different cellular responses according to the status of uPAR activity. On the other hand, we also found that MMP-mediated activation of EGFR can occur in an autocrine manner in cells which secrete uPA. All this reveals novel regulatory systems operating through autocrine loops involving uPAR stimuli, Src, MMP and EGFR activation which could mediate fine control of physiological processes as well as contribute to the expression of proliferative and invasive phenotypes of cancerous cells.

Transforming growth factor-beta1 modulates matrix metalloproteinase-9 production through the Ras/MAPK signaling pathway in transformed keratinocytes.

Mouse transformed keratinocytes cultured in the presence of transforming growth factor-beta1 (TGF-beta1) acquire a set of morphological and functional properties giving rise to a more motile phenotype that expresses mesenchymal markers. In this work, we present evidence showing that TGF-beta1 stimulates cellular production of MMP-9 (Gelatinase B), a metalloproteinase that plays an important role in tumoral invasion. Our results demonstrate that TGF-beta1stimulates MMP-9 production and MMP-9 promoter activity in a process that depends of the activation of the Ras-ERK1,2 MAP kinase pathway. The latter was demonstrated by cellular transfection of TGF-beta1-sensitive cells with a RasN17 mutant gene, using PD 098059, a MEK 1,2 inhibitor, and treating cells with anti-sense oligodeoxinucleotides. The enhanced MMP-9 production proved to be an important factor in the acquisition of migratory and invasive properties as shown by the use of a specific inhibitor of MMP-9 (GM6001) that inhibits the TGF-beta1-stimulated invasive and migratory properties of these transformed keratinocytes.