Effects of epidermal growth factor on invasiveness through the extracellular matrix in high- and low-metastatic clones of RCT sarcoma in vitro

Correlations between EGFR gene polymorphisms and pleural metastasis of lung adenocarcinoma

Proliferation, growth, and differentiation of cells are strictly controlled by the signal system of epidermal growth factor receptor (EGFR). If any link of the EGFR signals system is interfered with or damaged, the proliferation, growth, and differentiation of cells would become uncontrolled. EGFR is overexpressed in a variety of malignant tumors, such as non-small-cell lung cancer, colorectal cancer and breast cancer. Results of the study have proved that EGFR overexpression is closely associated with mutations and variants of the EGFR genes, whose mutations and variants are associated with occurrence, metastasis, and prognosis of different types of tumors, including lung cancer. This study is aimed at investigating whether the polymorphisms of CA simple sequence repeat in intron 1 (CA-SSR1), -216G/T, and R497K in the EGFR are able to induce EGFR activation and whether overexpression is associated with pleural metastasis of lung adenocarcinoma. A total of 432 lung adenocarcinoma patients with pleural metastasis (metastasis group) and 424 patients with lung adenocarcinoma but without pleural metastasis (nonmetastasis group) were enrolled in this study. For all patients, the CA-SSR1 genotypes were determined by capillary electrophoresis, polymerase chain reaction amplification, and direct DNA sequencing, and the R497K and -216G/T genotypes were determined by polymerase chain reaction amplification and direct DNA sequencing. EGFR expression was evaluated by immunohistochemical staining in primary tumor tissues with different -216G/T, R497K, and CA-SSR1 genotypes. Our results showed significant differences between pleural metastasis and nonmetastasis groups in the genotype and allele distribution of -216G/T, R497K, and CA-SSR1 polymorphisms of the EGFR gene. The -216T allele, Arg allele, and shorter CA-SSR1 (<17) had significantly increased risks of pleural metastasis compared with the -216G allele, Lys allele, and longer CA-SSR1 (≥17), respectively. The expression of EGFR was higher in patients with genotypes of -216T/T or -216G/T, Arg/Arg or Arg/Lys, and shorter CA-SSR1 (<17) than that in patients with genotypes of -216G/G, Lys/Lys, and longer CA-SSR1 (≥17), respectively. These results indicate that -216G/T, R497K, and CA-SSR1 polymorphisms are associated with the risk of pleural metastasis of lung adenocarcinoma, which may be related to the overexpression of EGFR protein induced by -216G/T, R497K, and CA-SSR1 polymorphisms.

STAT3 is required but not sufficient for EGF receptor-mediated migration and invasion of human prostate carcinoma cell lines

Growth factor-induced migration is a rate-limiting step in tumour invasiveness. The molecules that regulate this cellular behaviour would represent novel targets for limiting tumour cell progression. Epidermal growth factor (EGF) receptor (EGFR)-mediated motility, present in both autocrine and paracrine modes in prostate carcinomas, requires de novo transcription to persist over times greater than a few hours. Therefore, we sought to define specific signalling pathways that directly alter cellular transcription. Signal transducer and activator of transcription 3 (STAT3) is activated, as determined by electrophoretic motility shift assays, by EGFR in DU145 and PC3 human prostate carcinoma cells in addition to the motility model NR6 fibroblast cell line. Inhibition of STAT3 activity by antisense or siRNA downregulation or expression of a dominant-negative construct limited cell motility as determined by an in vitro wound healing assay and invasiveness through a extracellular matrix barrier. The expression of constitutively activated STAT3 did not increase the migration, which indicates that STAT3 is necessary but not sufficient for EGFR-mediated migration. These findings suggest that STAT3 signalling may be a new target for limiting prostate tumour cell invasion. In a microarray gene analysis of what transcription units are altered by EGF in a STAT3-dependent manner we found that the expression of motility-limiting VASP protein and the apoptosis nexus caspase 3 were both downregulated upon EGF exposure. These findings suggest a molecular basis for the STAT3 dependence of EGFR-mediated prostate tumour progression.

Trophoblast 'pseudo-tumorigenesis': significance and contributory factors

Trophoblast cells of the human placenta proliferate, migrate, and invade the pregnant uterus and its vasculature in order to nourish the developing fetus, in a way that is imitated by malignant tumors. Many similarities exist between embryo implantation and the growth of cancer cells. We begin this article by reviewing decades of studies that have helped unearth the mechanisms that contribute to the tumor-like phenotype of human trophoblast cells. Interestingly, these attributes are only transient in nature, with stringent spatial and temporal confines. The importance of intrinsic molecular controls that effectively circumscribe the extent and duration of trophoblast incursion, becomes increasingly evident in abnormal pregnancies that are characterized by aberrant trophoblast proliferation/invasion. We summarize and discuss the significance of abnormalities in these regulatory mechanisms, and finally, speculate about the use of human trophoblastic cells as model systems for the study of a variety of cellular processes. While on one hand, human placental cells are bestowed with a capacity to proliferate indefinitely and invade extensively, on the other, these cells are also replete with mechanisms to regulate these tumor-like attributes and eventually progress to a senescent apoptotic state. This is therefore, a 'well-behaved' tumor. The comparison in the present review is between the invasive cytotrophoblastic cell type and the tumor cell type.

Analysis of growth factor-dependent signalling in human epithelioid sarcoma cell lines. clues To the role of autocrine, juxtacrine and paracrine interactions in epithelioid sarcoma

Human epithelioid sarcoma (ES) is an extremely aggressive soft tissue tumour of unknown histogenesis. Although growth factor-dependent signalling cascades significantly affect the biological behaviour of malignant tumours, little is known so far about their role in human ES. The present investigation, therefore, analyses the coexpression and function of different growth factors and their receptors in the human ES cell line GRU-1 and its clonal subpopulations (GRU-1A, GRU-1B and GRU-1C). As shown by Northern blot, flow cytometry, immunocytochemistry and MTT assay, all ES cell lines expressed transforming growth factor (TGF)-alpha and the epidermal growth factor receptor (EGF-R). Although no response to exogenous TGF-alpha was observed, antagonistic anti-EGF-R antibodies (at 20 microg/ml) induced significant (P<0.05) growth inhibition in all cell lines. All cell lines showed coexpression of platelet-derived growth factor (PDGF)-A and the corresponding receptors. Neutralisation of ES-derived PDGF by anti-hPDGF antibodies resulted in significant (P<0.05) growth inhibition of all clonal subpopulations. Although all cell lines expressed TGF-beta(1) as well as TGF-beta type I and type II receptors (TGF-BI-R and TGF-BII-R), growth inhibition (P<0.05) by exogenous TGF-beta(1) was achieved in the clonal subpopulations only and not in the parental cell line. No ES cell line expressed acidic fibroblast growth factor (FGF) but stimulation of FGF type 3 and type 4 receptors (FGF-3R and FGF-4R) by exogenous acidic FGF (aFGF) resulted in a marked (P<0.05) acceleration of proliferation in all cell lines. In conclusion, our investigation suggests an intricate network of autocrine, juxtacrine and paracrine signalling between ES tumour cells and adjacent non-neoplastic stromal cells.

Effects of sex steroids and growth factors on invasive activity and 5'-deoxy-5-fluorouridine sensitivity in ovarian adenocarcinoma OMC-3 cells

Effects of sex steroids (estradiol-17 beta, E2; progesterone, Prog) and growth factors (epidermal growth factor, EGF; transforming growth factor-alpha, TGF-alpha) on invasive activity and 5'-deoxy-5-fluorouridine (5'-dFUrd) sensitivity of ovarian adenocarcinoma OMC-3 cells were investigated. Tumor cell migration along a gradient of substratum-bound fibronectin and invasion into reconstituted basement membrane were inhibited by 10 microM Prog, but stimulated by 0.1-10 nM EGF and TGF-alpha in a concentration-dependent manner. E2 did not have any effect on tumor cell migration or invasion. The zymography of tumor conditioned medium showed that the treatment of OMC-3 cells with EGF and TGF-alpha resulted in increases of type IV collagenase, stromelysin and urokinase-type plasminogen activator (uPA). EGF and TGF-alpha up-regulated thymidine phosphorylase (dThdPase) expression of tumor cells and consequently enhanced the antiproliferative action of 5'-dFUrd, which is converted to 5-fluorouracil by dThdPase. E2 and Prog did not have significant effects on the expression of proteolytic enzymes and dThdPase, or on the 5'-dFUrd sensitivity of tumor cells. The inhibitory effect of Prog on tumor cell invasion may depend on its inhibitory action on the motility of tumor cells. These results suggest that EGF and TGF-alpha simultaneously up-regulate the potential of ovarian adenocarcinoma cells to invade extracellular matrices and their dThdPase expression, both of which are associated with the specific action of 5'-dFUrd selectively to kill tumor cells with high invasive and metastatic potential.

Stimulatory effects of EGF and TGF-alpha on invasive activity and 5'-deoxy-5-fluorouridine sensitivity in uterine cervical-carcinoma SKG-IIIb cells

We investigated the effects of epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha on migration, invasion and matrix metalloproteinase (MMP) expression of uterine cervical-carcinoma SKG-IIIb cells, and whether these growth factors affect pyrimidine-nucleoside-phosphorylase (PyNPase) activity and 5'-deoxy-5-fluorouridine (5'-dFUrd) sensitivity of tumor cells. Tumor-cell migration along a gradient of substratum-bound fibronectin and invasion into reconstituted basement membrane were stimulated by 0.1 to 100 ng/ml of EGF and TGF-alpha in a concentration-dependent manner. The zymography of tumor-conditioned medium showed that the treatment of tumor cells with EGF and TGF-alpha resulted in an increase of the 92-kDa type-IV collagenase (MMP-9), which was confirmed by immunoblot analysis. These growth factors also up-regulated the expression of PyNPase activity of tumor cells and consequently enhanced the anti-proliferative action of 5'-dFUrd, a cytostatic that is biotransformed to 5-fluorouracil (5-FUra) by PyNPase. However, EGF and TGF-alpha did not have significant effects on the 5-FUra sensitivity of tumor cells. These results suggest that EGF and TGF-alpha, tumor environmental factors, simultaneously up-regulate the potential of uterine cervical-carcinoma cells to invade extracellular matrices and their PyNPase activity, which are subsequently associated with the specific action of 5'-dFUrd selectively killing tumor cells of gynecological origin with high invasive and metastatic potential.

Eicosapentaenoic acid and epidermal growth factor modulation of human breast cancer cell adhesion

Cancer cell adhesion to the subendothelial extracellular matrix (ECM) is an important step in metastasis formation. The effect of epidermal growth factor (EGF) and eicosapentaenoic acid (EPA) on adhesion of the highly metastatic MDA-MB-231 human breast cancer cell line to ECM components was examined in the present study. MDA-MB-231 cells exhibited a dose-dependent decrease in adhesion to Matrigel when treated with EGF. EGF and EPA, alone or in combination, decreased adhesion to Matrigel, fibronectin and type IV collagen. These results suggest that decreased adhesion to ECM substrates by combined EPA and EGF treatment may be the result of a common post-receptor signaling pathway.

The relationship between 67KD laminin receptor expression and metastasis of hepatocellular carcinoma

The 67KD laminin receptor (LN-R) that binds laminin (LN) is involved in the metastasis cascade. Using immunohistochemical technique, in situ hybridization and reverse transcription polymerase chain reaction (RT-PCR), we studied LN-R protein and RNA levels in 30 cases of human hepatocellular carcinoma (HCC) to further understand its role in the metastasis of HCC. In our 14 cases of HCC with metastasis, its positive rates were 71.4%, 57.1%, 85.7% respectively, whereas its positive expression in 16 cases without metastasis were 31.3%, 18.8%, 50.0% respectively. The significant difference was found between these two groups. The results suggest that the 67KD LN-R expression plays a very important role in the metastasis of HCC.

Epidermal growth factor modulates cell attachment to hyaluronic acid by the cell surface glycoprotein CD44

Cell adhesion to and migration through extracellular matrices (ECM) are critical events in tumor invasion and metastasis. Previous work by us had demonstrated that signaling of epidermal growth factor receptor (EGFR) confers an oncogenic phenotype on NR6 cells and that these cells when transfected with holo EGFR demonstrate greater motility and invasiveness than cells carrying a carboxy-terminal truncated EGFR. Recently, a cell surface glycoprotein, CD44, has been implicated in cell-ECM adhesion involved in tumor cell migration, signal transduction, and metastasis. We investigated whether EGF regulates cellular interactions with ECM components, and in particular, hyaluronate, by modulating CD44 expression. In vitro cell attachment assays on hyaluronate-coated plates demonstrated similar basal level of binding (approximately 33%) for murine NR6 parental cells devoid of endogenous EGFR (P) or expressing wild-type EGFR (WT), while a time-dependent increase in binding was observed in WT cells stimulated with EGF. Additionally, utilizing monoclonal antibody blocking assays, CD44, but not EGFR, was shown to be directly involved in this attachment. Both WT and P cells possessed equivalent 95 kDa bands on immunoblots, corresponding to CD44. The existence of CD44 mRNA was verified by RT-PCR using synthetic oligonucleotides in which a 1.1 kb cDNA was detected in both cell lines and confirmed by DNA sequencing. After 24-h exposure to exogenous EGF, an increase in CD44 protein and mRNA expression was found in WT cells, but not in P cells, supporting the contention that a functional EGFR signaling pathway is required for CD44 regulation. Thus, EGF stimulates cell binding to hyaluronate in vitro by regulating CD44 expression.

Effects of sex steroids and growth factors on migration and invasion of endometrial adenocarcinoma SNG-M cells in vitro

Biological effects of sex steroids (estradiol-17beta, E2; progesterone, P; medroxyprogesterone acetate, MPA; Danazol, DZ) and growth factors (epidermal growth factor, EGF; transforming growth factor, TGF-alpha,beta) on migration and invasion of endometrial adenocarcinoma SNG-M cells were investigated by haptotactic migration and haptoinvasion assay. The enzymatic degradation of the extracellular matrix by tumor cells was also examined. Tumor cell migration along a gradient of substratum-bound fibronectin was inhibited by 0.1-10 microM MPA and DZ, but promoted by 0.1-10 nM EGF and TGF-alpha in a concentration-dependent manner. E2, P and TGF-beta did not have any effect on the motility of tumor cells. These effects were also confirmed by wound assay. The invasive activity of SNG-M cells into reconstituted basement membrane (Matrigel) was inhibited by the presence of 0.1-10 microM MPA and DZ, but promoted by 0.1-10 nM EGF and TGF-alpha in a concentration-dependent manner. E2, P and TGF-beta did not have any effect on tumor cell invasion. The zymography of tumor-conditioned medium showed that the treatment of SNG-M cells with EGF and TGF-alpha resulted in the increase of the 68, 72 and 92 kDa type IV collagenases (matrix metalloproteinase, MMP-2 and 9). Sex steroids and TGF-beta did not have significant effects on MMP-2 and 9. Stromelysin (MMP-3), also secreted by SNG-M cells, was not affected by sex steroids and growth factors. These results suggest that EGF and TGF-alpha act as positive regulators on the invasion process of endometrial adenocarcinoma cells, which may partly be associated with the induction of type IV collagenase secretion by tumor cells. The inhibitory effects of MPA and DZ on tumor cell invasion may depend at least partly on their inhibitory action on the motility of tumor cells.

Invasive capacity and regulation of urokinase-type plasminogen activator in estrogen receptor (ER)-negative MDA-MB-231 human breast cancer cells, and a transfectant (S30) stably expressing ER

We assessed the invasive capacities and expression of urokinase-type plasminogen activator (uPA) in the estrogen receptor (ER) negative MDA-MB-231 cell line, and the same cell transfected with an ER expression vector (S30 cells) in response to 17 beta-estradiol (E2; 1 nM) and epidermal growth factor (EGF; 1 ng/ml and 10 ng/ml). The invasive potential of S30 cells was only 50% that of MDA-MB-231 cells and was further reduced by E2. EGF increased the invasiveness of S30 cells, but was unable to reverse the inhibitory effects of E2. Invasion of MDA-MB-231 cells was unaffected by E2 or EGF. EGF increased uPA secretion from both cell lines, as determined by ELISA and zymography, and this correlated with increased expression of uPA mRNA. uPA expression in MDA-MB-231 cells was unaffected by E2; however, S30 cells responded to E2 with downregulation of uPA at both the protein and mRNA levels.

Tumor cell attachment to laminin promotes degradation of the extracellular matrix and cell migration in high-metastatic clone cells of RCT sarcoma in vitro

We investigated the roles of extracellular matrix proteins, laminin and fibronectin, in promoting invasiveness through the extracellular matrix in high-metastatic [RCT(+)] clone cells established from poorly differentiated murine RCT sarcoma in C3H/He mice. Laminin stimulated the type IV collagenolytic activity of RCT(+) cells. After more than 6 h of incubation, the type IV collagenolysis of the cell-conditioned medium was significantly higher in laminin-treated groups compared with the control. The migration activity of RCT(+) cells was stimulated by laminin. However, fibronectin did not influence the type IV collagenolysis or cell migration in this clone cell. The amino acid sequence YIGSR, which is derived from laminin, inhibited the laminin-mediated cell attachment and the laminin-promoted type IV collagenolysis, as well as cell migration of RCT(+) cells. RGD derived from fibronectin did not influence the cell attachment to laminin or Matrigel in this clone. In the invasion assay employing a Matrigel coated filter in a Boyden chamber, YIGSR showed greater inhibition of invasion through the Matrigel than did RGD with RCT(+) cells. YIGSR might inhibit the promoted-matrix degradation and cell migration in response to the cell attachment to laminin by competing with laminin for binding to cell surface laminin receptor. We suggest that laminin-mediated cell attachment to the extracellular matrix may play a role in promoting the matrix degradation and cell migration during metastatic cascades.

Serum levels of laminin, type IV collagen and type III procollagen peptide as markers for detection of metastasis

We investigated the clinical usefulness of serum laminin, type IV collagen and type III procollagen peptide (PIIIP) as markers for detection of metastasis in patients with primary or metastatic bone and soft part tumors. The subjects consisted of 28 patients with metastatic bone tumors, 18 with primary bone tumors (benign; 10, malignant; 8), 22 with primary soft part tumors (benign; 12, malignant; 10), 18 with cancer without metastasis (as controls to metastatic bone tumor) and 60 healthy controls. Elevated levels of serum laminin, type IV collagen and PIIIP were not associated with any specific histological subtype, tumor size or location, and were clearly related to evidence of metastasis. Mean serum concentrations of laminin, type IV collagen and PIIIP were significantly higher in patients with metastasis than in patients without metastasis. Positive correlations were observed among serum laminin, type IV collagen and PIIIP levels in tumor patients. The sensitivity values for laminin, type IV collagen and PIIIP in detecting metastasis were 83.7%, 83.3% and 80.5%, respectively, with specificity of 90.0%, 86.1% and 86.1%. When two of the three markers were evaluated in identical blood samples, combined sensitivity and specificity values exhibited further increases as compared to the sensitivity and specificity of each marker. The use of all three markers led to the best combined sensitivity and specificity. These findings suggest that the combination of these markers would be a valuable screening test in predicting metastasis.