Stable overexpression of TGFbeta1 in a transitional carcinoma cell line: impact on fibronectin production

Transforming Growth Factor-β Is an Upstream Regulator of Mammalian Target of Rapamycin Complex 2-Dependent Bladder Cancer Cell Migration and Invasion

Our prior work identified the mammalian target of rapamycin complex 2 (mTORC2) as a key regulator of bladder cancer cell migration and invasion, although upstream growth factor mediators of this pathway in bladder cancer have not been well delineated. We tested whether transforming growth factor (TGF)-β, which can function as a promotility factor in bladder cancer cells, could regulate mTORC2-dependent bladder cancer cell motility and invasion. In human bladder cancers, the highest levels of phosphorylated SMAD2, a TGF-β signaling intermediate, were present in high-grade invasive bladder cancers and associated with more frequent recurrence and decreased disease-specific survival. Increased expression of TGF-β isoforms, receptors, and signaling components was detected in invasive high-grade bladder cancer cells that expressed Vimentin and lacked E-cadherin. Application of TGF-β induced phosphorylation of the Ser473 residue of AKT, a selective target of mTORC2, in a SMAD2- and SMAD4-independent manner and increased bladder cancer cell migration in a modified scratch wound assay and invasion through Matrigel. Inhibition of TGF-β receptor I using SB431542 ablated TGF-β-induced migration and invasion. A similar effect was seen when Rictor, a key mTORC2 component, was selectively silenced. Our results suggest that TGF-β can induce bladder cancer cell invasion via mTORC2 signaling, which may be applicable in most bladder cancers.

Immunohistochemical evaluation of COX-1 and COX-2 expression in keloid and hypertrophic scar

Both keloids (KLs) and hypertrophic scars (HSs) are considered as dermal fibroproliferative diseases that differ clinically and histopathologically. Although several factors have been postulated in the etiopathogenesis of these conditions, there has been growing evidence to suggest the role of COXs in the pathogenesis of abnormal wound healing because of the reduction of formation of KL and HS in patients using nonsteroidal anti-inflammatory drugs and a COX-2 inhibitor. The aim of the present work is to evaluate the pattern and localization of COX-1 and COX-2 expression in KL and HS compared with surgical scars. COX-1 and COX-2 were analyzed on skin biopsies of 30 patients who presented with KL (15) and HS (15) and 10 normal surgical scars (controls). Both COX-1 and COX-2 were expressed not only in dermal components (fibroblasts, inflammatory cells, and endothelial cells) but also in keratinocytes of the overlying epidermis in the different studied scar lesions. The percentage of COX-1 expression increased progressively from surgical scar (40%) to HS (53.3%) to KL (100%) with a statistically significant difference (P = 0.002). COX-2 was expressed in 100% of surgical scars, 73.3% of HS and 86.7% of KL with the absence of significant differences (P > 0.05). The significant difference in COX-1 expression between HS and KL may refer to the presence of different pathways for the emergence of these diseases. The expression of COX-2 in all scars (normal or abnormal) indicates its active role as an inflammatory mediator. Keratinocytes play an active role in induction of scarring by up-regulation of inflammatory mediators, such as COX-1 and COX-2.

Micro-array analysis of the effect of post-transurethral bladder tumor resection urine on transforming growth factor-β1 dependent gene expression in transitional cell carcinoma☆

INTRODUCTION AND OBJECTIVES

Prior studies have shown that bladder trauma occurring during transurethral bladder tumor resection increases urinary levels of the cytokine transforming growth factor (TGF)-beta1. This study used complementary deoxyribonucleic acid micro-array technology to identify additional genes in human transitional cell carcinoma (TCC), whose expression is altered as a consequence of increased urinary levels of TGF-beta1.

METHODS

The human TCC line 253J was cultured in standard media, or media spiked with either 10% post-transurethral bladder tumor resection urine (PTU), or PTU and anti-TGF-beta1 neutralizing antibody. Messenger ribonucleic acid from these conditions, together with messenger ribonucleic acid from stably transfected 253J cells over-expressing TGF-beta1, was hybridized with ATLAS micro-array membranes (Clontech, Palo Alto, CA) containing 588 human genes. Hybridization signal intensity was quantified using phospho-imaging. An analytic strategy based on the variance in the signal intensity ratio of specific housekeeping genes in control and experimental comparisons was used to identify significant changes in gene expression. Reverse transcriptase polymerase chain reaction of target genes was used to confirm gene over-expression and TGF-beta1 responsiveness.

RESULTS

Seven genes were identified on micro-array: v-RAF-1, colony stimulating factor-1 receptor, v-FGR, insulin growth factor-1 receptor, epidermal growth factor receptor, alpha5 integrin, and interferon receptor-1. Reverse transcriptase polymerase chain reaction confirmed over-expression in the autocrine TGF-beta1 producing cell line and increased expression in response to exogenous TGF-beta1.

CONCLUSIONS

TGF-beta1 in PTU alters the expression of multiple genes in human TCC in vitro. The impact of these changes on the biologic phenotype of the malignant cell and the efficacy of adjuvant therapies requires further evaluation.

Autocrine over expression of fibronectin by human transitional carcinoma cells impairs bacillus Calmette-Guerin adherence and signaling

PURPOSE

Bacillus Calmette-Guerin (BCG) binds to the tumor cell as a result of mycobacterial receptors for fibronectin (FN). Cell surface bound FN serves as a bridge through which BCG attaches to the tumor cell. Despite the importance of FN studies have demonstrated an idiosyncratic decrease in BCG adherence in response to exogenous FN. We evaluated the effect of exogenous and autocrine FN on the ability of BCG to adhere to the tumor cell surface and initiate cellular signaling.

MATERIALS AND METHODS

BCG adherence to parental 253J and FN over expressing 253JTGFbeta1-8 cells as well as to the intrinsic FN expressing cell line 647V was quantified using green fluorescent protein-BCG. Experiments were performed to assess the effect of FN on BCG initiated signal transduction through nuclear factor kappaB and AP1. Finally, the integrity of the BCG activated signaling pathway in transforming growth factor-beta1/FN over expressors was assessed using antibody mediated cross-linking of the FN receptor.

RESULTS

BCG adherence was decreased in cell lines with high autocrine expression of FN. Exogenous FN prevented BCG induced transactivation of nuclear factor kappaB and AP1 reporter constructs. No BCG stimulated signaling to these reporters could be detected in FN over expressing 253J cells. NonFN dependent alpha5beta1 cross-linking initiated signal transduction in FN over expressing cells.

CONCLUSIONS

We propose that by saturating cellular and BCG receptors excess FN expression decreases the ability of cellular or mycobacterial bound FN to bind vacant receptors on BCG or on the cell. Excess FN inhibits BCG adherence and BCG initiated signal transduction.

Fibronectin stimulates human lung carcinoma cell growth by inducing cyclooxygenase-2 (COX-2) expression

Tobacco use is the most important risk factor for the development of lung carcinoma. One characteristic shared by tobacco-related lung diseases is altered lung connective tissue content and composition. In particular, tobacco results in increased expression of fibronectin (FN), a matrix glycoprotein implicated in lung development, injury and repair and in tumor cell invasion. We hypothesized that excessive deposition of FN in lung might promote lung carcinoma cell proliferation. Consistent with this hypothesis, we found that FN stimulated human lung carcinoma cell proliferation and diminished apoptosis in vitro, and that this effect was mediated through the integrin alpha5beta1 and associated with upregulation of cyclooxygenase-2 (COX-2) mRNA and protein expression, and increased prostaglandin E2 (PGE2) biosynthesis. The stimulatory effect of FN on COX-2 was blocked by the specific COX-2 inhibitor NS-398 and by inhibitors of protein kinase C (PKC), Calphostin C, and extracellular signal-regulated kinases (Erks), PD98095. Electrophoretic mobility shift assays revealed that FN increased the nuclear binding activity of cyclic AMP response element binding protein (CREB) and CCAAT/enhancer-binding protein (C/EBP), 2 proteins known to play important roles in the regulation of COX-2 promoter activity. Transient transfection assays with wild-type and mutated constructs of the human COX-2 gene promoter revealed that the stimulatory effect of FN was prevented when either the CRE or the NF-IL6 (C/EBP) sites were mutated. Taken together, the results indicate that FN stimulates human lung carcinoma cell proliferation and diminishes apoptosis by inducing COX-2 gene expression and PGE2 biosynthesis. Activation of PKC and Erk and DNA-protein interactions at CRE and NF-IL6 (C/EBP) sites in the COX-2 gene promoter appear to play key roles in this process. This work demonstrates that signaling through specific matrix-binding beta1 integrins (i.e., alpha5beta1) resulting from exaggerated deposition in lung of the matrix glycoprotein fibronectin might promote lung carcinoma cell growth.

Protein-bound polysaccharide PSK inhibits tumor invasiveness by down-regulation of TGF-beta1 and MMPs

Transforming growth factor beta1 (TGF-beta1) and matrix metalloproteinases (MMPs) produced by tumor cells play important roles in tumor invasion. PSK, a protein-bound polysaccharide, is widely used in Japan as an immunopotentiating biological response modifier for cancer patients. In this study, we focused on the effects of PSK on invasiveness, TGF-beta1 production, and MMPs expression in two human tumor cell lines, pancreatic cancer cell line (NOR-P1) and gastric cancer cell line (MK-1P3). PSK significantly decreased the invasiveness of both cell lines through Matrigel-coated filters but did not affect cell viability, proliferation, or adhesion. Decreased invasion was associated with the inhibition of TGF-beta1, MMP-2, and MMP-9 at both mRNA and protein levels as assessed by reverse transcriptase-polymerase chain reaction, gelatin zymography, and enzyme-linked immunosorbent assay. Antibody against TGF-beta1 neutralized the MMP activities of both cell lines. PSK also suppressed the expression of urokinase plasminogen activator (uPA) and uPA receptor but did not change plasminogen activator inhibitor-1 (PAI-1) expression. Western blot analysis showed that PSK reduced uPA protein expression but not PAI-1 expression in the both cell lines. These results indicate that PSK suppresses tumor cell invasiveness through down-regulation of several invasion-related factors including TGF-beta1, uPA, MMP-2, and MMP-9.