Induction of growth factor-receptor and metalloproteinase genes by epidermal growth factor and/or transforming growth factor-alpha in human gastric carcinoma cell line MKN-28

PKG II effectively reversed EGF-induced protein expression alterations in human gastric cancer cell lines

Epidermal growth factor receptor (EGFR) plays an important role in gastric cancer (GC) progression. Our previous data demonstrated that type II cGMP-dependent protein kinase (PKG II) could block the EGF-EGFR axis as well as down-stream signaling pathways, for example, MAPK, PI3 K, and PLC in GC cells. However, the exact mechanisms of PKG II against cancer remain unclear. Therefore, the present work was to address the above question. Human GC cell line AGS was infected with adenoviral construct encoding cDNA of PKG II (Ad-PKG II) to up-regulate PKG II and then treated with 8-pCPT-cGMP. Two-dimensional electrophoresis (2-DE) was used to analyze the changes of protein expression in the cells. The results showed that 17 proteins had more than twofold changes in EGF-treated group compared with control. However, Ad-PKG II could effectively reversed the changes. Furthermore, far upstream element-binding protein 1 (FUBP1) and MarvelD3 were chosen and PKG II activation reversed EGF/EGFR-induced up-regulation of FUBP1 and downregulation of MarvelD3, respectively. MarvelD3 silence effectively abolished the inhibitory effect of PKG II on EGF-triggered migration. These data indicated that the inhibitory effect of PKG II partially was associated with MarvelD3.

Anacardic acid inhibits gelatinases through the regulation of Spry2, MMP-14, EMMPRIN and RECK

Earlier studies from our laboratory have identified Anacardic acid (AA) as a potent inhibitor of gelatinases (MMP-2 and 9), which are over-expressed in a wide variety of cancers (Omanakuttan et al., 2012). Disruption of the finely tuned matrix metalloproteinase (MMP) activator/inhibitor balance plays a decisive role in determining the fate of the cell. The present study demonstrates for the first time, that in addition to regulating the expression as well as activity of gelatinases, AA also inhibits the expression of its endogenous activators like MMP-14 and Extracellular Matrix MetalloProteinase Inducer (EMMPRIN) and induces the expression of its endogenous inhibitor, REversion-inducing Cysteine-rich protein with Kazal motifs (RECK). In addition to modulating gelatinases, AA also inhibits the expression of various components of the Epidermal Growth Factor (EGF) pathway like EGF, Protein Kinase B (Akt) and Mitogen-activated protein kinases (MAPK). Furthermore, AA also activates the expression of Sprouty 2 (Spry2), a negative regulator of EGF pathway, and silencing Spry2 results in up-regulation of expression of gelatinases as well as MMP-14. The present study thus elucidates a novel mechanism of action of AA and provides a strong basis for utilizing this molecule as a template for cancer therapeutics.

Liver-intestine cadherin induction by epidermal growth factor receptor is associated with intestinal differentiation of gastric cancer

Gastric cancer (GC) is one of the most common malignancies worldwide. The epidermal growth factor receptor (EGFR) molecule is very important in GC progression. To examine the correlation between EGFR and GC-related genes, we analyzed gene expression profiles of HT-29 cells treated with EGFR ligands and identified six genes upregulated by epidermal growth factor (EGF) and transforming growth factor (TGF)-α treatment. Among these, we focused on cadherin 17 (CDH17) encoding liver-intestine cadherin (LI-cadherin). Expression of LI-cadherin was induced by both EGF and TGF-α, as detected by quantitative RT-PCR and Western blot analysis. A luciferase assay showed that LI-cadherin promoter activity was enhanced by EGF or TGF-α in both HT-29 cells and MKN-74 GC cells. Immunohistochemical analysis of 152 GC cases showed that out of 58 LI-cadherin-positive cases, 24 (41%) cases were also positive for EGFR, whereas out of 94 LI-cadherin-negative cases, only 9 (10%) cases were positive for EGFR (P < 0.0001). Double-immunofluorescence staining revealed that EGFR and LI-cadherin were coexpressed. Significant correlation was found between LI-cadherin expression and advanced T grade and N grade. Both EGFR and LI-cadherin expression were more frequently found in GC cases with an intestinal mucin phenotype than in cases with a gastric mucin phenotype. These results indicate that, in addition to the known intestinal transcription factor caudal type homeobox 2, EGFR activation induces LI-cadherin expression and participates in intestinal differentiation of GC.

Southwest Oncology Group study S0413: a phase II trial of lapatinib (GW572016) as first-line therapy in patients with advanced or metastatic gastric cancer

BACKGROUND

Lapatinib (GW572016) is a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2/ErbB2), which are reported as overexpressed in 15%-45% of gastric cancers, making them potential targets.

PATIENTS AND METHODS

The primary objective of this study was to assess response rate. Secondary objectives included overall survival (OS), toxicity, and the relationship of EGFR, ErbB2, and markers of angiogenesis with clinical outcome. Lapatinib was administered to chemonaive metastatic gastric cancer patients at a dose of 1500 mg orally daily for 28 days.

RESULTS

The study enrolled 47 patients from February 2005 until May 2006. Four patients (9%) had a confirmed partial response (PR), 1 (2%) had an unconfirmed PR, and 10 (23%) had stable disease. Median (95% confidence interval) time to treatment failure was 1.9 (1.6-3.1) months and OS was 4.8 (3.2-7.4) months. Significant adverse events: one grade 4 cardiac ischemia/infarction, one grade 4 fatigue, and one grade 4 emesis. One treatment-related death was due to central nervous system ischemia. An exploratory analysis of markers revealed gene expression of HER2, interleukin (IL)-8 and genomic polymorphisms IL-8, and vascular endothelial growth factor correlated with OS.

CONCLUSIONS

Lapatinib is well tolerated, with modest single-agent activity in advanced/metastatic gastric cancer patients. Potential molecular correlatives were identified which warrant further validation.

Requirement of MMP-3 in anchorage-independent growth of oral squamous cell carcinomas

BACKGROUND

Matrix metalloproteinase-3 (MMP-3) is expressed in various carcinomas; however, its function is not clearly established. This study was to assess its possible role in oral squamous cell carcinomas (OSCCs).

MATERIALS AND METHODS

Specimens of seven oral pre-malignant lesions (OPMLs) and 92 OSCCs were subjected to MMP-3 detection by RT-PCR and Western blot. Antisense oligodeoxynucleotides (AODNs) of MMP-3 were used to transfect OSCC (OECM-1 and SCC-9) and esophageal carcinoma (CE81T/VGH) cell lines, and their growth was subsequently analyzed by XTT and soft-agar colony assay.

RESULTS

MMP-3 transcript was preferentially expressed in OSCCs (71 of 92, 77%) than in OPMLs (two of seven, 29%; P = 0.012). Both MMP-3 transcript and protein levels were significantly higher in OSCC masses than in neighboring tissues (P < 0.0001 and P = 0.04, respectively). Growth of the three cell lines was not affected, while the colony numbers of OECM-1 and CE81T/VGH were significantly reduced by the transfection of MMP-3 AODNs (P = 0.002 and P = 0.004, respectively). SCC-9 did not form colonies in soft-agar/medium.

CONCLUSIONS

MMP-3 function may be required in most OSCCs, and it may support the anchorage-independent growth of both OSCC and esophageal carcinoma.

Sivelestat, a specific neutrophil elastase inhibitor, suppresses the growth of gastric carcinoma cells by preventing the release of transforming growth factor-alpha

Neutrophil elastase is a neutral serine proteinase produced by polymorphonuclear leukocytes and monocytes/macrophages, especially under surgical stress. In the present study, we investigated whether NE promotes cell growth by activation of EGFR to elucidate whether surgical stress induces tumor proliferation and progression. Furthermore, we examined the antitumor effect of a specific NE inhibitor, sivelestat. Cell growth assays were carried out in vitro and in vivo using TMK-1 gastric cancer cells. TMK-1 cell growth was stimulated to 118% of that of the control cells after 48 h stimulation with 1 microg/mL NE according to an MTT assay. Sivelestat inhibited cell growth to 23.4 and 58.0% of control values at concentrations of 100 and 1,000 microg/mL, respectively. NE rapidly phosphorylated EGFR in only 5 min and triggered the ERK1/2-mitogenic signaling pathway in TMK-1. It was further demonstrated that NE-induced EGFR phosphorylation was transactivated through TGF-alpha, using ELISA. NE increased the cleavage of TGF-alpha from the cell surface 30-fold compared with the cells without treatment. Interestingly, sivelestat significantly reduced NE-induced EGFR phosphorylation and ERK1/2 activation and completely blocked the release of TGF-alpha from the TMK-1 cell surface. In a xenograft study, the addition of ventrotomy as a surgical stress promoted tumor growth. Sivelestat significantly suppressed the tumor growth induced by surgical stress. These results indicate that sivelestat suppresses the growth of gastric cancer cells by inhibiting the release of TGF-alpha stimulated by NE, which often occurs after surgical stresses.

Cellular and molecular aspects of gastric cancer

Gastric cancer remains a global killer with a shifting burden from the developed to the developing world. The cancer develops along a multistage process that is defined by distinct histological and pathophysiological phases. Several genetic and epigenetic alterations mediate the transition from one stage to another and these include mutations in oncogenes, tumour suppressor genes and cell cycle and mismatch repair genes. The most significant advance in the fight against gastric caner came with the recognition of the role of Helicobacter pylori (H pylori) as the most important acquired aetiological agent for this cancer. Recent work has focussed on elucidating the complex host/microbial interactions that underlie the neoplastic process. There is now considerable insight into the pathogenesis of this cancer and the prospect of preventing and eradicating the disease has become a reality. Perhaps more importantly, the study of H pylori-induced gastric carcinogenesis offers a paradigm for understanding more complex human cancers. In this review, we examine the molecular and cellular events that underlie H pylori-induced gastric cancer.

Expression of Cbl linking with the epidermal growth factor receptor system is associated with tumor progression and poor prognosis of human gastric carcinoma

Cbl proteins play important roles in downregulation of growth factor receptors by acting as ubiquitin ligases and multi-adapter proteins. Ligand-induced desensitization of the epidermal growth factor receptor (EGFR) has been shown to be controlled by Cbl. In the present study, we examined the expression of Cbl in gastric carcinomas and studied the correlation of Cbl expression with clinicopathological characteristics as well as EGFR expression. Cbl protein was expressed in 67% (82/122) of gastric carcinomas, and diffuse expression of Cbl was detected in 29% (35/122) of the cases. The incidence of cases with diffuse expression of Cbl was significantly higher in advanced cases (28/70, 40%) than in early cases (7/52, 14%) (P=0.0010). Diffuse expression of Cbl was significantly associated with metastasis of tumor cells in lymph nodes (P=0.0318). Diffuse expression of EGFR was significantly associated with depth of invasion (P=0.0057), lymph-node metastasis (P=0.0371) and tumor stages (P=0.0278). As the grades of Cbl expression became stronger, the cases with diffuse EGFR expression increased, the positive correlation being significant (P=0.049). All the cases with diffuse expression of Cbl and EGFR were found to show nodal metastasis and to be at an advanced stage. Moreover, the prognosis of the patients with synchronous diffuse expression of Cbl and EGFR was significantly poorer than that of the patients negative for Cbl and focal or negative for EGFR (P=0.0086). The expression of Cbl protein was clearly induced in gastric carcinoma cell lines by transforming growth factor-alpha treatment. These results suggest that Cbl in connection with the EGFR system may be associated with stomach carcinogenesis, invasion and metastasis. Cbl may serve as a novel molecular marker for aggressive gastric carcinoma.

Effect of 5-fluorouracil and epidermal growth factor on cell growth and dihydropyrimidine dehydrogenase regulation in human uterine cervical carcinoma SKG-IIIb cells

We previously demonstrated that epidermal growth factor (EGF) induces a decrease in dihydropyrimidine dehydrogenase (DPD), which is the first and rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU), in EGF receptor (EGFR)-positive human SKG-IIIb uterine cervical carcinoma cells, and thereby increased the sensitivity of the cells to 5-FU. In the present study, we examined the individual and combined effects of 5-FU and EGF on growth and DPD activity in SKG-IIIb cells, and also investigated the mode of regulation of DPD activity. The cells showed sensitivity to 5-FU, and growth was stimulated by EGF. When the agents were used in combination, the sensitivity of SKG-IIIb cells to 5-FU was increased roughly sixfold at maximum, as judged in terms of the 50% growth-inhibitory concentration. We then examined the effects of 5-FU and EGF on DPD. Either agent inhibited DPD activity and protein expression in a concentration-dependent manner. Expression of DPD mRNA was concentration-dependently inhibited by treatment with 5-FU and by EGF at a concentration that strongly stimulated cell growth. Further, combination treatment inhibited DPD activity, as well as DPD protein and mRNA expression, more strongly than did treatment with 5-FU or EGF alone. These results suggest that inhibition of DPD activity by EGF or 5-FU is regulated at least at the level of protein expression and that regulation via mRNA is also involved. The above findings indicate that 5-FU and EGF act synergistically in suppressing DPD activity and that the use of 5-FU against tumors in which EGF plays an important role would maximize the potential of 5-FU as an anticancer drug.

Motility is rate-limiting for invasion of bladder carcinoma cell lines

Induced migration of tumor cells is generally considered to be one critical step in cancer progression to the invasive and metastatic stage. The implicit caveat of studies that show this is that other, unknown, signaling pathways and biophysical events are actually the operative rate-limiting steps, and not motility per se. Thus, to examine the hypothesis that motility is a single, but overall rate-limiting function required for invasion, disparate motility processes need be blocked with concordant effects on tumor invasion. Recently, we and others have described two signaling pathways that are critical to growth factor-induced motility but not mitogenesis. The key molecular switches are phospholipase C-gamma (PLCgamma) and calpain for cytoskeletal reorganization and rear detachment, respectively. We examined this hypothesis in a highly invasive tumor, bladder carcinoma. Three different human tumor cell lines, 253J-B-V, UMUC and T-24, were tested for invasiveness in vitro by transmigration of a Matrigel barrier. Inhibiting PLCgamma with the pharmacologic agent U73122 or the molecular dominant-negative PLCz construct reduced both invasiveness and motility. The same was noted when calpain was blocked using calpain inhibitor I (ALLN). These results demonstrate that one interventional target for limiting invasion is not necessarily an individual motility pathway but rather cell migration per se.

Indomethacin delays gastric restitution: association with the inhibition of focal adhesion kinase and tensin phosphorylation and reduced actin stress fibers

Repair of superficial gastric mucosal injury is accomplished by the process of restitution-migration of epithelial cells to restore continuity of the mucosal surface. Actin filaments, focal adhesions, and focal adhesion kinase (FAK) play crucial roles in cell motility essential for restitution. We studied whether epidermal growth factor (EGF) and/or indomethacin (IND) affect cell migration, actin stress fiber formation, and/or phosphorylation of FAK and tensin in wounded gastric monolayers. Human gastric epithelial monolayers (MKN 28 cells) were wounded and treated with either vehicle or 0.5 mM IND for 16 hr followed by EGF. EGF treatment significantly stimulated cell migration and actin stress fiber formation, and increased FAK localization to focal adhesions, and phosphorylation of FAK and tensin, whereas IND inhibited all these at the baseline and EGF-stimulated conditions. IND-induced inhibition of FAK phosphorylation preceded changes in actin polymerization, indicating that actin depolymerization might be the consequence of decreased FAK activity. In in vivo experiments, rats received either vehicle or IND (5 mg/kg i.g.), and 3 min later, they received water or 5% hypertonic NaCl; gastric mucosa was obtained at 1, 4, and 8 hr after injury. Four and 8 hr after hypertonic injury, FAK phosphorylation was induced in gastric mucosa compared with controls. IND pretreatment significantly delayed epithelial restitution in vivo, and reduced FAK phosphorylation and recruitment to adhesion points, as well as actin stress fiber formation in migrating surface epithelial cells. Our study indicates that FAK, tensin, and actin stress fibers are likely mediators of EGF-stimulated cell migration in wounded human gastric monolayers and potential targets for IND-induced inhibition of restitution.

Epidermal growth factor receptor signaling and the invasive phenotype of ovarian carcinoma cells

BACKGROUND

Most (70%-100%) ovarian carcinomas express high levels of the epidermal growth factor receptor (EGFR). To examine the relationship between EGFR and the invasive phenotype, we assessed integrin expression, adhesion, matrix metalloproteinase (MMP) activity, and migration in ovarian cancer cells in which EGFR expression was modified.

METHODS

NIH:OVCAR-8 human ovarian carcinoma cells were transfected with an expression vector containing the human EGFR complementary DNA in an antisense orientation (EGFR-antisense cells) or the vector alone (vector control cells). We compared vector control and EGFR-antisense cells for cell morphology and adhesion by light microscopy, expression of alpha(6)- and alpha(3)-integrin subunits by flow cytometry, MMP and tissue inhibitor of MMP (TIMP) activity by zymography, and migration by a wound migration assay. In some experiments, EGFR kinase activity in parental cells was inhibited by treatment with PD153035. All statistical tests were two-sided.

RESULTS

EGFR-antisense cells were morphologically distinct from vector control cells and had a selective decrease in adhesion to laminin-1 that was not observed with vector control cells (P = .008) or on other extracellular matrix substrates. Compared with vector control cells, cell surface alpha(6)-integrin expression decreased by approximately 80% (difference = 78.7%; 95% confidence interval [CI] = 77.8% to 79.6), MMP-9 activity decreased by approximately 50%, and TIMP activity increased by approximately 50% in EGFR-antisense cells. Vector control cells were highly motile (5.51 arbitrary distance unit; 95% CI = 4.98 to 6.04), whereas the EGFR-antisense cells were not (0.99 arbitrary distance units; 95% CI = 0.38 to 1.60). The morphology and integrin profile of NIH:OVCAR-8 parental cells treated with PD153035 were similar to those of the EGFR-antisense cells.

CONCLUSIONS

Reduced EGFR expression in ovarian carcinoma cells decreased their adhesion to laminin-1, expression of the alpha(6)-integrin subunit (a well-characterized laminin-1 receptor), and MMP-9 activity. These data support the hypothesis that EGFR overexpression in ovarian cancer cells results in multiple phenotypic changes that enhance the invasive phenotype.

Genetic and epigenetic changes in stomach cancer

Genetic and epigenetic alterations of multiple cancer-related genes and molecules are implicated in the development and progression of human gastric carcinomas. Reactivation of telomerase, inactivation of p53 tumor suppressor gene, overexpression of cyclin E, and reduced expression of p27 KIP1 by disorganized degradation in proteasome are common events of both well-differentiated and poorly differentiated gastric adenocarcinomas. Inactivation of hMLH1 mismatch repair gene by CpG hypermethylation resulting in microsatellite instability, amplification of c-erbB2 oncogene, inactivation of APC tumor suppressor gene, and K-ras mutations are preferentially associated with well-differentiated gastric cancer. Conversely, reduction or loss of E-cadherin and catenins by both mutation and CpG hypermethylation and K-sam and c-met oncogene amplification are necessary for the development and progression of poorly differentiated or scirrhous gastric carcinomas. Interaction between cancer cells expressing c-met and hepatocyte growth factor from stromal cells is implicated in morphogenesis of gastric cancer.

Molecular characteristics of eight gastric cancer cell lines established in Japan

Molecular characterization of eight gastric cancer cell lines established in Japan are summarized according to the genetic and epigenetic alterations and growth factor status. TMK-1 poorly differentiated adenocarcinoma cell line harbors mutant p53 tumor suppressor gene and rearrangement of p15MTS2. MKN-1 adenosquamous carcinoma line with mutant p53 reveals silencing of E-cadherin by promoter CpG hypermethylation. MKN-7 well-differentiated adenocarcinoma cell line has amplification of c-erbB2 oncogene and cyclin E gene. MKN-28 well-differentiated adenocarcinoma cell line reveals mutations in p53 and APC tumor suppressor genes and silencing of CD44. The MKN-45 poorly differentiated adenocarcinoma cell line with wild-type p53 is characterized by homozygous deletion of p16CDKN2/MTS1/INK4A and p15MTS2, amplification of c-met oncogene and promoter mutation of E-cadherin. MKN-74 derived from moderately differentiated tubular adenocarcinoma has wild-type p53. KATO-III signet ring cell carcinoma line has genomic deletion of p53, amplification of K-sam and c-met oncogene and mutation of E-cadherin. HSC-39 signet ring cell carcinoma cell line harboring p53 missense mutation has homozygous deletion of p16CDKN2/MTS1/INK4A and p15MTS2, amplifications of c-myc, c-met, K-sam and CD44 gene and mutation in beta-catenin gene.

Electrocautery snare resection stimulates cellular proliferation of residual colorectal tumor: an increasing gene expression related to tumor growth

PURPOSE

Recently, endoscopic mucosal resection has been performed commonly for colorectal tumors. However, incomplete endoscopic mucosal resection produces a residual tumor that grows rapidly. The aim of this study was to clarify the characteristics of the residual tumor using the nude mouse model.

METHODS

Human colon cancer cells (colo201 or colo320DM) were implanted subcutaneous into nude mice. We then removed more than one-half of the tumor with an electrocautery snare or a surgical knife, and compared the tumor growth rate with that of control tumors. Before and after resection, we examined the Ki-67 labeling index of the tumors with an immunohistochemical assay and mRNA expression for epidermal growth factor receptor, vascular endothelial growth factor, and transforming growth factor alpha.

RESULTS

Residual tumors showed a higher growth rate in tumor volume than control tumors using both methods (electrocautery snare and surgical knife). Colo201 groups showed a higher total volume change per day than colo320DM groups after resection. Furthermore, these tumors also showed a higher Ki-7 labeling index, and a stronger epidermal growth factor receptor and transforming growth factor alpha mRNA expression than primary and control tumors in the colo201 implanted groups. There was no significant difference in vascular endothelial growth factor mRNA expression between groups implanted with colo201 or colo320DM.

CONCLUSION

Our results suggest that residual tumors caused by incomplete endoscopic mucosal resection may have a higher growth potential than the tumors before resection.

Epidermal growth factor receptor relocalization and kinase activity are necessary for directional migration of keratinocytes in DC electric fields

Human keratinocytes migrate towards the negative pole in DC electric fields of physiological strength. This directional migration is promoted by epidermal growth factor (EGF). To investigate how EGF and its receptor (EGFR) regulate this directionality, we first examined the effect of protein tyrosine kinase inhibitors, including PD158780, a specific inhibitor for EGFR, on this response. At low concentrations, PD158780 inhibited keratinocyte migration directionality, but not the rate of migration; at higher concentrations, it reduced the migration rate as well. The less specific inhibitors, genistein, lavendustin A and tyrphostin B46, reduced the migration rate, but did not affect migration directionality. These data suggest that inhibition of EGFR kinase activity alone reduces directed motility, and inhibition of multiple tyrosine kinases, including EGFR, reduces the cell migration rate. EGFR redistribution also correlates with directional migration. EGFR concentrated on the cathodal face of the cell as early as 5 minutes after exposure to electric fields. PD158780 abolished EGFR localization to the cathodal face. These data suggest that EGFR kinase activity and redistribution in the plasma membrane are required for the directional migration of keratinocytes in DC electric fields. This study provides the first insights into the mechanisms of directed cell migration in electric fields.

Integrin-mediated migration of murine B82L fibroblasts is dependent on the expression of an intact epidermal growth factor receptor

To evaluate the mechanisms by which epidermal growth factor (EGF) regulates actin-based cellular processes such as cell migration, we first examined the effects of EGF on cell adhesion, which is essential for cell migration. In mouse B82L fibroblasts transfected with the full-length EGF receptor, EGF promotes cell rounding and attenuates cell spreading on fibronectin, laminin, and vitronectin, and thus appears to reduce the strength of cell adhesion. Moreover, EGF synergizes with multiple extracellular matrix (ECM) components in the promotion of integrin-mediated cell migration of several different cell types, including fibroblasts and various carcinoma and osteosarcoma cell lines. Interestingly, co-presentation (co-positioning) of EGF with laminin or fibronectin is essential for EGF-stimulated migration. When EGF is mixed with the cells instead of the ECM components, it has little effect on cell migration. These results suggest that co-presentation of EGF with ECM components can enhance the polarization events required for directional cell movement. To identify the EGF receptor elements critical for the EGF stimulation of cell migration, B82L fibroblasts were transfected with either mutated or wild-type EGF receptors. Surprisingly, we found that B82L-Parental cells that lack the EGF receptor are not able to migrate to fibronectin, even though they can adhere to fibronectin. However, the introduction of wild-type EGF receptors into these fibroblasts enables them to migrate toward fibronectin even in the absence of EGF. The requirement of the EGF receptor for cell migration does not appear to result from the secretion of EGF or TGF-alpha by the cells transfected with the EGF receptor. Furthermore, cells expressing EGF receptors that are kinase-inactive, or C-terminally truncated, exhibit little migration toward fibronectin, indicating that an intact EGF receptor kinase is required for fibronectin-induced cell migration. In addition, neutralizing anti-EGF receptor antibodies attenuate cell migration in the presence of EGF, and inhibit migration to fibronectin or laminin alone. These results further suggest that the EGF receptor is downstream of integrin activation in the signal transduction pathways leading to fibroblast migration.

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.

In vitro invasion of small-cell lung cancer cell lines correlates with expression of epidermal growth factor receptor

Formation of metastasis is a multistep process involving attachment to the basement membrane, local proteolysis and migration into surrounding tissues, lymph or bloodstream. In the present study, we have analysed the correlation between in vitro invasion and presence of the epidermal growth factor receptor (EGFR) in a panel of 21 small-cell lung cancer (SCLC) cell lines. We have previously reported that ten of these cell lines expressed EGFR protein detected by radioreceptor and affinity labelling assays. In 11 small-cell lung cancer (SCLC) cell lines, EGFR mRNA was detected by Northern blot analysis. In vitro invasion in a Boyden chamber assay was found in all EGFR-positive cell lines, whereas no invasion was detected in the EGFR-negative cell lines. Quantification of the in vitro invasion in 12 selected SCLC cell lines demonstrated that, in the EGFR-positive cell lines, between 5% and 16% of the cells added to the upper chamber were able to traverse the Matrigel membrane. Expression of several matrix metalloproteases (MMP), of tissue inhibitor of MMP (TIMP) and of cathepsin B was evaluated by immunoprecipitation, Western blot analysis and reverse transcriptase polymerase chain reaction (RT-PCR). However, in vitro invasive SCLC cell lines could not be distinguished from non-invasive cell lines based on the expression pattern of these molecules. In six SCLC cell lines, in vitro invasion was also determined in the presence of the EGFR-neutralizing monoclonal antibody mAb528. The addition of this antibody resulted in a significant reduction of the in vitro invasion in three selected EGFR-positive cell lines. Our results show that only EGFR-positive SCLC cell lines had the in vitro invasive phenotype, and it is therefore suggested that the EGFR might play an important role for the invasion potential of SCLC cell lines.

Expression of interleukin-6 and its effect on the cell growth of gastric carcinoma cell lines

The expression and the effect of IL-6 were examined in human gastric carcinoma cell lines to determine whether IL-6 serves as a growth stimulator. The expression of IL-6 mRNA was detected in three (TMK-1, MKN-1, MKN-7) of 8 gastric carcinoma cell lines. All three cell lines secreted IL-6 into the culture fluid, in large amounts in the cases of MKN-1 and MKN-7 cells. Scatchard plot analysis of IL-6 binding revealed that MKN-1 and MKN-7 cells had both high- and low-affinity receptors. Cell growth of MKN-1 and MKN-7 cells was stimulated by IL-6, while anti-IL-6 antibody inhibited growth. The expression of IL-1 alpha mRNA by these three cell lines was induced by IL-6. IL-1 alpha increased the expression of mRNA for IL-6 by TMK-1 cells. These findings indicate that IL-6 induced by IL-1 alpha is an autocrine growth factor for some gastric carcinomas.

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.

Rho proteins play a critical role in cell migration during the early phase of mucosal restitution

In the intestine, several growth factors stimulate migration of epithelial cells, contributing to the maintenance of tissue integrity. The Ras-like GTPase Rho regulates a signal transduction pathway linking growth factor receptors to the formation of actin stress fibers and focal adhesions, presumed to be important for motility. Using an in vitro wound-induced migration assay, we have examined the role of Rho GTPases in the migration of IEC-6 and Caco-2 cells, and provide evidence that the Rho GTPases play an essential role in the initial phase of mucosal wound healing. Treatment of the cells with Clostridium difficile toxins A and B, inhibitors of the Rho family GTPases inhibited migration in a dose-dependent fashion. Microinjection of the inhibitory exchange factor Rho-guanine nucleotide dissociation inhibitor (GDI), or Clostridium botulinum C3 ADP-ribosyl transferase (C3) toxin, a Rho-ADP-ribosylating exoenzyme, potently inhibited migration. Microinjection of RhoT19N, a dominant negative form of RhoA, or in vitro ADP-ribosylated RhoA impaired the ability of cells to migrate. Rho-GDI and C3 exoenzyme also inhibited EGF-induced migration of IEC-6 cells. These results demonstrate that Rho is required for endogenous and EGF-induced migration of small intestinal crypt cells, and that Rho proteins are essential elements of a mechanism by which growth factors induce cell migration to restitute mucosal integrity.

Direct intratumoral gene transfer of the herpes simplex virus thymidine kinase gene with DNA-liposome complexes: growth inhibition of tumors and lack of localization in normal tissues

To constitute the site-specific expression of the herpes simplex virus thymidine-kinase (HSV-TK) gene in tumor cells, we have assessed the promoter function of the simian virus 40 (SV40) promoter and the 5'flanking region of c-erbB-2 gene using a luciferase-expressing reporter plasmid. After the transfection of the luciferase plasmid directed by the promoter region of c-erbB-2 gene, a large amount of luciferase activity was observed in c-erbB-2-expressing cells (Colo201, MCF-7, and HEC1-A), while none was detected in cells with no expression of c-erbB-2 protein (HRA and KF cells). On the other hand, a high level of luciferase activity was detected in all tumor cell lines tested, when the transfection was performed with SV40 promoter. The repeated transfection of the liposome-conjugated HSV-TK gene regulated by the SV40 promoter or by the promoter region of c-erbB-2 gene with cultivation in 100 micrograms/ml of aciclovir for 5 days in vitro resulted in growth inhibition for all four cell lines examined or for only c-erbB-2-expressing cells in the presence of SV40 promoter or c-erbB-2 promoter, respectively. Finally, direct injection of the DNA-liposome complex into established tumors in the presence of 50 mg/kg of aciclovir led to significant tumor volume reduction in all three tumors tested when SV40 promoter was employed. However, this anti-tumor effect was noted only in c-erbB-2-positive cells (Colo201 cells) upon intratumoral injection of HSV-TK gene regulated by c-erbB-2 promoter. In the case of intratumoral gene transfer, foreign DNA was detected in only one of seven mice by polymerase chain reaction (PCR) analysis performed 7 days following injection. When PCR analysis was carried out at 14 or 21 days following injection, no DNA signal was found at all. However, DNA was detected in several normal tissues at all three times tested in the case of intravenous injection. No abnormalities were seen in histologic examinations of normal tissues or in serum biochemical parameters following DNA liposome delivery. These results suggest that the direct gene transfer of HSV-TK gene regulated by tumor-specific transcriptional units may be one of the most clinically promising of the selective genetic strategies against cancer.

Induction of metalloproteinase (MMP1) expression by epidermal growth factor (EGF) receptor stimulation and serum deprivation in human breast tumour cells

The levels of the matrix metalloproteinase MMP1 mRNA in three breast tumour cell lines with varying numbers of epidermal growth factor (EGF) receptors, MDA-MB-231, T47D and MCF7, were investigated following treatment with EGF or TGF alpha in serum-free medium for up to 24 h. A higher level of MMP1 mRNA was found in both control and treated MDA-MB-231 cells compared with the other two cell lines. A 2-fold increase in MMP1 transcripts was observed in MDA-MB-231 cells following a 30 min treatment with EGF and 2 h with TGF alpha. An increase in MMP1 transcripts following serum deprivation in the absence of growth factor stimulation was also seen. This effect was not evident with the other cell lines. In MDA-MB-231 cells, low concentrations of MMP1 protein were detected in medium from treated cells and was only significantly increased after 24 h but it was inhibited by cycloheximide. The early effect of EGF on MMP1 expression was not inhibited by cycloheximide. Treatment with cycloheximide for longer periods produced increased transcripts of MMP1, TGF alpha and EGF-receptor, suggesting the activation of processes for tissue breakdown and subsequent repair may occur on prolonged inhibition of protein synthesis. These results confirm a relationship between EGF-receptor stimulation and MMP1 expression in some EGF-receptor positive tumour cells, which, in part, occurs at the transcriptional level, and have implications for the invasive progression of EGF-receptor positive tumours particularly in areas of nutritional deprivation.

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.

In vitro invasiveness of DU-145 human prostate carcinoma cells is modulated by EGF receptor-mediated signals

Prostate carcinomas often present an autocrine stimulatory loop in which the transformed cells both express the EGF receptor (EGFR) and produce activating ligands (TGF alpha and EGF forms). Up-regulated EGFR signalling has been correlated with tumor progression in other human neoplasia; however, the cell behaviour which is promoted remains undefined. To determine whether an EGFR-induced response contributes to cell invasiveness, we transduced DU-145 human prostate carcinoma cells with either a full-length (WT) or a mitogenically-active but motility-deficient truncated (c'973) EGFR. The DU-145 Parental and two transgene sublines all produced EGFR and TGF alpha, but the transduced WT and c'973 EGFR underwent autocrine downregulation to a lesser degree, with more receptor remaining intact. DU-145 cells transduced with WT EGFR transmigrated a human amniotic basement membrane matrix (Amgel) to a greater extent than did Parental DU-145 cells (175 +/- 22%). Cells expressing the c'973 EGFR invaded through the Amgel only to about two thirds the extent of the Parental cells (62 +/- 23%). A monoclonal antibody which prevents ligand-induced activation of EGFR decreased the invasiveness of WT-expressing cells by half and Parental cells by a fifth, but had little effect on the invasiveness of c'973-expressing cells; with the result that in the presence of antibody, all three cell lines transmigrated the Amgel to the same extent. The different levels of invasiveness between the three sublines were independent of cell proliferation. These findings demonstrated that EGFR-mediated signals increase tumor cell invasiveness and suggested that domains in the carboxy-terminus are required to signal invasiveness. As an initial investigation into the mechanisms underlying the EGFR-mediated enhanced invasiveness, we determined whether these cells presented different collagenolytic activity, as the major constituents of Amgel are collagen types I and IV. All three sublines secreted easily detectable levels of gelatin-directed proteases and TIMP-1, with WT cells secreting equivalent or lower levels of proteases. The proteolytic balance in these cells did not correlate with invasiveness. These data suggest that the TGF alpha-EGFR autocrine loop promotes invasiveness and that this is accomplished by signalling cell properties other than differential secretion of collagenolytic activity.

Cell movement elicited by epidermal growth factor receptor requires kinase and autophosphorylation but is separable from mitogenesis

The EGF receptor (EGFR) upon activation signals increased cell movement. However, the domains within the receptor, and the pathway which trigger movement are undefined. We expressed EGFR mutants at physiologic levels in receptor-devoid NR6 cells to investigate this biologic response. The receptors possessed kinase activity and underwent autophosphorylation as predicted by primary amino acid sequence. EGF-induced cell motility was assessed in vitro by excess migration into an acellular area and colony scatter in the presence of saturating concentrations of EGF. Wild-type (WT)-EGFR signaled increased motility. However, replacing the conserved lysine721 with methionine resulted in a kinase-inactive receptor which did not elicit movement. Removal of the entire terminus by truncation (c'973) also abrogated ligand-induced motility. Thus, we concentrated on the carboxy-terminal domains. EGF-induced movement was seen with a less-truncated mutant (c'1000) that contained a single autophosphorylated tyrosine (tyrosine992). Other mutants, c'991 and c'1000F992, in which this tyrosine was removed did not signal motility. Fusion mutants which presented other autophosphorylated tyrosine domains also exhibited EGF-induced movement. These findings suggested that the presence of both an autophosphorylated tyrosine signaling domain and the kinase activity are necessary for this biologic response. All kinase-positive mutants signaled cell proliferation but only those that contained autophosphorylatable tyrosines induced movement. The motility responses mediated by these EGFR were identical in the presence or absence of mitomycin-C, at a dose (0.5 micrograms/ml) which completely inhibited cell proliferation. On the other side, D-actinomycin (50 ng/ml) blocked EGF-induced motility but did not affect thymidine incorporation. Thus, EGF-induced mitogenesis and cell motility are mediated through different pathways.

Effect of epidermal growth factor on prostate cancer cell line PC3 growth and invasion

Elevated levels of epidermal growth factor (EGF) and epidermal growth factor receptor (EGF-R) have been demonstrated in prostate cancer cell lines and clinical specimens suggesting a role for polypeptide growth factors in prostate tumor cell growth and invasion. To more clearly define the role of EGF in prostate cancer invasion, we undertook a series of studies utilizing the PC3 prostate cancer cell line, an aggressive, hormone-independent cell line derived from a metastatic lesion. No statistical differences were noted in the growth of PC3 cells under serum-free conditions when EGF (10(-10) M-10(-8) M) or monoclonal anti-EGF-R antibody (10(-11) M-10(-8) M) were added. Utilizing the Boyden chamber microinvasion assay, EGF supplemented cells demonstrated a statistically significant augmentation in invasion (P < 0.05) when compared to control cells at each time point in the study. With increasing length of exposure to EGF, the number of concentrations that produced significant invasion increased: day 1 (10(-8) M), day 3 (10(-8), 10(-9) M), and day 5 (10(-7), 10(-8), 10(-10) M). Northern blot analysis of EGF supplemented cells revealed an increase in expression of urokinase plasminogen activator (uPA) RNA, a serine protease involved in the regulation of pericellular proteolysis and membrane degradation. Protein analysis confirmed these findings. Statistically significant inhibition of invasion by anti-uPA antibodies was demonstrated for EGF-stimulated and PC3 control cells. Our results demonstrate that certain concentrations of EGF augment invasion in the PC3 cell line. This enhancement of invasion occurs in part by an overproduction of uPA, an extracellular protease. These findings suggest that the autocrine production of EGF may potentiate tumor cell invasion.

Interstitial collagenase gene expression in colonic neoplasia

Tumor invasion and metastasis are complex phenomena believed to be facilitated by the disruption of collagen and elastin fibers in the extracellular matrix. Interstitial collagenase gene expression was studied in colonic adenocarcinoma and adenoma using in situ hybridization. The data indicated that three cell types within the tumor stroma expressed collagenase transcripts; they were eosinophils, fibroblasts, and vascular endothelium. In all 12 adenocarcinomas, a high to moderate level of expression was seen in 1 to 5% of eosinophils and in occasional fibroblasts, whereas these cell types in non-neoplastic mucosa adjacent to tumor showed no detectable expression. Two adenocarcinomas showed expression in hyperplastic endothelium in vascularized granulation tissue. Two out of three adenomas showed expression in eosinophils and fibroblasts at a reduced level. Tissue inhibitor of metalloproteinase-1 gene expression was, however, negligible in all tissue examined. These results suggest that interstitial collagenase gene activation in the tumor stroma, especially eosinophils, may have an important role in tumor invasion and metastasis.

Expression of amphiregulin, a novel gene of the epidermal growth factor family, in human gastric carcinomas

The expression of mRNA for amphiregulin (AR), a novel gene of the epidermal growth factor family, was examined in 8 human gastric carcinoma cell lines and 32 gastric carcinoma tissues as well as corresponding normal mucosa. Of the 8 gastric carcinoma cell lines, 7 expressed 1.4 kb AR mRNA at various levels. The expression of AR mRNA by TMK-1 and MKN-28 cells was increased by treatment with epidermal growth factor or transforming growth factor a. In surgical cases, all the gastric carcinoma tissues and their adjacent normal mucosa expressed AR mRNA. Interestingly, 20 (62.5%) out of 32 tumors expressed AR mRNA at higher levels than their corresponding normal mucosas (tumor/normal > or = 1.2). No obvious correlation was observed between the AR mRNA levels and the histological types or tumor staging of gastric carcinoma. Immunohistochemically, AR protein was localized to the cytoplasm and/or nucleus in tumor cells. These results suggest that AR produced by tumor cells may be involved in the pathogenesis and/or progression of human gastric carcinoma.

Molecular mechanism of stomach carcinogenesis

Gene changes in multiple oncogenes, multiple growth factors and multiple tumor-suppressor genes are observed in stomach cancer. Among them, those most commonly implicated in both well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma are inactivation (mutations and allele loss) of the p53 gene, and activation (abnormal expression and amplification) of the c-met gene. Moreover, they occur at an early stage of stomach carcinogenesis. In addition, loss of heterozygosity (LOH) on chromosome 5q (APC locus) is frequently associated with well-differentiated adenocarcinoma. LOH on chromosome 18q (DCC locus) and LOH of the bcl-2 gene also are common events of well-differentiated adenocarcinoma. LOH on chromosomes 1q and 7q may be involved in the progression of well-differentiated adenocarcinoma. Conversely, the development of poorly differentiated adenocarcinoma, in addition to changes in p53 and c-met genes, requires reduction or dysfunction of cadherin. Overexpression of bcl-2 protein is observed in poorly differentiated adenocarcinoma or signet-ring cell carcinoma. Moreover, the K-sam gene is amplified preferentially in poorly differentiated adenocarcinoma of scirrhous carcinoma. K-sam amplification in scirrhous carcinoma often occurs independently of c-met gene amplification. LOH on chromosome 1p also is relatively common in poorly differentiated adenocarcinoma. Exceptionally, signet-ring cell carcinoma shares APC mutations. There are some differences in expression of the growth-factor/receptor system between well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma. Moreover, interaction between cell-adhesion molecules in tumor cells expressing c-met and hepatocyte growth factor (HGF) from stromal cells is linked with morphogenesis of two histological types of stomach cancer. Intestinal metaplasia and adenoma of the stomach also contain p53 mutations and K-ras mutations or tpr-met rearrangement. Taken together, different genetic pathways of stomach carcinogenesis may exist for poorly differentiated and well-differentiated stomach cancers. Some of the latter may develop by a cumulative series of gene alterations similar to those of colorectal cancer.

Protein secretion by the mouse blastocyst: stimulatory effect on secretion into the blastocoel by transforming growth factor-alpha

We have previously demonstrated that newly synthesized proteins are secreted into the mouse blastocoel [Dardik and Schultz (1991): Biol Reprod 45:328-333]. In the present study we examine the effect of transforming growth factor-alpha (TGF-alpha) on these proteins. We observe that TGF-alpha stimulates secretion of these newly synthesized proteins into the blastocoel and apical medium, which faces the zona pellucida, by about 65%. Although one-dimensional gel electrophoretic analysis does not reveal any marked differences in the patterns of newly synthesized proteins secreted into the blastocoel in response to TGF-alpha, zymography reveals a marked stimulation in the secretion of several gelatinases into the blastocoel and apical medium. These results suggest additional functions for TGF-alpha in mouse preimplantation development.

The level of a transcription factor Sp1 is correlated with the expression of EGF receptor in human gastric carcinomas

The expression of the transcription factor Sp1 and EGF receptor (EGFR) was examined on human gastric carcinoma cell lines and gastric carcinoma tissues as well as corresponding normal mucosa in order to clarify the mechanism of overexpression of EGFR gene without gene amplification. All 7 carcinoma cell lines expressed Sp1 mRNA, the levels of which were closely correlated with the expression of EGFR mRNA except for one cell line. The gel retardation analysis revealed that the levels of Sp1 mRNA were parallel to its DNA binding activities. In 18 surgical cases, 12 tumors expressed Sp1 mRNA at higher levels than normal mucosa. The cases with overexpression of Sp1 showed the high level of EGFR mRNA. These results suggest that overexpression of Sp1 in tumor cells may induce overexpression of EGFR without gene amplification in human gastric carcinomas.

Expression of transforming growth factor alpha in human tissues: immunohistochemical study and northern blot analysis

The expression of transforming growth factor alpha (TGF-alpha) was examined in various human tissues and the fetus, using immunohistochemistry and Northern blot analysis. TGF-alpha immunoreactivity was detected mainly in the epithelial cells of the digestive tract, liver, pancreas, kidney, thyroid, adrenal, skin, mammary gland and genital organs. In the digestive tract, epithelial cells with regenerative change or hyperplastic change showed strong immunoreactivity to TGF-alpha. Peripheral nerve, vessels, megakaryocytes and macrophages in the lung and spleen were also positive for TGF-alpha. By Northern blot analysis the expression of TGF-alpha mRNA was confirmed in the digestive tract, salivary gland, thyroid, kidney and mammary gland. In the human fetus, the nerve tissues, liver, adrenal and kidney were positive for TGF-alpha. Strong immunoreactivity to TGF-alpha was observed in the hepatocytes of the fetus. These findings indicate that TGF-alpha is produced by a variety of non-neoplastic cells in both adult and fetal tissues.

A serine protease-inhibitory benzamidine derivative inhibits the growth of human colon carcinoma cells

The inhibitory effect of a serine protease-inhibiting tetra-benzamidine derivative, TAPP-Br, on the cell growth of 8 human colon carcinoma cell lines was examined and the mechanism of the inhibition was analyzed. TAPP-Br inhibited the cell growth of all the colon carcinoma cell lines, and this effect was irreversible. The expression of mRNAs for nuclear oncogenes such as MYC, FOS and JUN was decreased by TAPP-Br after treatment for 3 h and the effect continued for 48 h. mRNA expression of epidermal growth factor receptor, transforming growth factor-beta and type IV collagenase was suppressed at 48 h after the initiation of TAPP-Br treatment, suggesting an indirect action of TAPP-Br. TAPP-Br decreased protein kinase C activity in the particulate fraction, whereas it increased the enzyme activity in the soluble fraction. These findings overall suggest that the serine protease inhibitor, TAPP-Br, might inhibit the cell growth of colon carcinoma cell lines through suppressing the expression of genes whose promoter contains a 12-O-tetradecanoylphorbol-13-acetate-responsive element or serum-responsive element.

Reduced levels of transforming growth factor-beta type I receptor in human gastric carcinomas

The expressions of transforming growth factor beta (TGF-beta) and its receptor and TGF-beta inhibitory element (TIE)-binding protein were examined on human gastric carcinomas by Northern blot hybridization, immunohistochemistry, affinity labeling and gel retardation analysis. TGF-beta mRNA was expressed in tumor and normal tissues at various levels. Immunohistochemically, TGF-beta expression was confirmed to be present within tumor cells. Out of the 17 human gastric carcinoma tissues, 14 (82%) showed a reduction in the level of type I receptor (65 kDa) for TGF-beta when compared to corresponding normal mucosas. Interestingly, in seven of the 14 tumors the level of TIE-binding protein in the tumor tissue was lower than that in normal mucosa. Human gastric carcinoma cell line TMK-1, whose growth was inhibited by TGF-beta, had only type I receptor for TGF-beta and showed a high level of TIE-binding protein. Conversely, MKN-1, a TGF-beta-resistant cell line, exhibited an extremely low level of TGF-beta receptor and had no TIE-binding protein. These results overall indicate that although human gastric carcinoma cells produced TGF-beta, they showed a reduction in TGF-beta type I receptor and a low level of TIE-binding protein, resulting in escape from growth inhibition by TGF-beta.

Effects of human recombinant epidermal growth factor on the growth of MKN-28 human gastric carcinoma transplanted into nude mice

The effects of human recombinant epidermal growth factor (EGF) on the growth of MKN-28 human gastric carcinoma, transplanted into nude mice were studied. Modulation of tissue cAMP and EGF receptor levels by EGF was also studied to reveal the mechanism of the growth inhibitory effects of EGF. EGF exhibited a dose-dependent growth inhibitory effect on MKN-28 human gastric carcinoma transplanted into nude mice. Local injection of 2 ng of EGF moderately inhibited the growth of MKN-28 gastric carcinoma, while injections of 20 ng, 200 ng and 2 micrograms of EGF significantly inhibited tumour growth. EGF decreased tissue cAMP levels in a dose-dependent manner within 24 h after EGF injection. On the other hand, EGF increased the EGF receptor levels up to two or three fold within 24 h after EGF injection. Conversely, the EGF receptor affinity for EGF decreased according to the increase in EGF receptor levels.

Effects of tyrosine kinase inhibitor, erbstatin, on cell growth and growth-factor/receptor gene expression in human gastric carcinoma cells

The effect of tyrosine kinase inhibitor, erbstatin, on cell growth and mRNA expression of growth-factor/receptor system was examined in 6 human gastric-carcinoma cell lines. Erbstatin inhibited both EGF-induced and serum-stimulated cell growth of all 6 cell lines (TMK-1, MKN-1, -7, -28, -45, -74) in a dose-dependent manner. 3H-thymidine incorporation by TMK-1 cells was also suppressed by erbstatin. Erbstatin inhibited protein kinase activity of EGF receptor, p185ERBB2 and pp60c-src in TMK-1 cells. The expression of mRNA of EGF receptor gene and ERBB-2 by TMK-1 cells was not changed by erbstatin treatment, whereas that of c-src was slightly decreased. Interestingly, erbstatin decreased membrane-bound TGF-alpha precursor as measured by anti-TGF-alpha antibody-binding assay, although mRNA expression for TGF-alpha was not altered by erbstatin. Our findings suggest that erbstatin may act as a growth inhibitor for human gastric-carcinoma cells and may not only inhibit tyrosine kinase activities but also negatively modulate the post-transcriptional step of TGF-alpha expression.

Growth factors in progression of human esophageal and gastric carcinomas

Human esophageal and gastric carcinomas express multi-autocrine growth factors and hormones including epidermal growth factor (EGF), transforming growth factor (TGF)-alpha and beta, platelet-derived growth factor (PDGF), insulin-like growth factor (IGF) and sex hormones. Overexpression of EGF, TGF-alpha and EGF receptor (EGFR) by tumor cells is closely correlated with the tumor invasion and patient prognosis. This is substantiated by the facts that EGF and TGF-alpha act as autocrine growth factors and then induce the expression of mRNAs for multi-growth factors and their receptors (EGF, TGF-alpha, EGFR, ERBB2, PDGF). Moreover, they stimulate the expression of metalloproteinase genes suggesting that EGF and TGF-alpha successively evoke cascade phenomena which are most convenient for tumor progression, invasion and metastasis. On the other hand, multiple oncogene alterations take place in the process of tumor progression. HST-1 and INT-2 genes which is a member of fibroblast growth factor gene family, are amplified in approximately 50% of primary tumors and all the metastatic tumors of esophageal carcinomas. The amplification of ERBB2 gene in metastatic gastric carcinomas is detected more frequently than in primary carcinomas. Overexpression of multi-growth factor-receptor systems might lead to genetical alterations. Scirrhous gastric carcinoma has vast fibrous stroma with rapid and extensive growth and exhibits high malignancy. Its fibrous stroma may account for synchronous overexpression of EGF, TGF-alpha, PDGF, IGF and TGF-beta by tumor cells. Most of well differentiated adenocarcinomas show overexpression of p 185ERBB2 and coexpression of p 185ERBB2, and EGFR evidently correlates with high malignancy. In conclusion, the accumulation and interaction of several growth factors produced by tumor cells are necessary for the progression of human esophageal and gastric carcinomas. They may be attributed to genetic changes including activation of oncogenes, inactivation and deletion of anti-oncogenes and transcriptional regulatory sequences.