Co-expression of heparin-binding EGF-like growth factor and related peptides in human gastric carcinoma

T cell landscape and dynamics in immunoglobulin light chain amyloidosis before and after daratumumab-based therapy

Amyloid light-chain (AL) is characterized by the presence of small, poorly proliferating plasma cell clones with the production and deposition of light chains into tissues. T cell changes within the tumour microenvironment in AL are poorly understood. By sequencing at a single-cell level of CD3+ T cells purified from bone marrow (BM) and blood of newly diagnosed AL patients before and after a combination of daratumumab with cyclophosphamide, bortezomib, and dexamethasone (Dara-BCD), we analysed the transcriptomic features of T cells and found an expansion, activation and type I cytokine upregulation in BM and circulating T cells after the treatment. More prominent changes were shown in CD8+ T cells. In particular, we found the presence of CD8+ BM resident memory T cells (TRM ) with high expression of inhibitory molecules in AL patients at diagnosis. After Dara-BCD, these TRM cells were quickly activated with downregulation of suppressive molecules and upregulation of IFNG expression. These data collectively demonstrate that Dara-based therapy in patients with AL amyloidosis promotes anti-tumour T cell responses. The similar transcriptomic features of BM and circulating T cells before and after therapy further provide a less invasive approach for molecular monitoring of T cell response in AL amyloidosis.

Mechanisms of the Epithelial-Mesenchymal Transition and Tumor Microenvironment in Helicobacter pylori-Induced Gastric Cancer

Helicobacter pylori (H. pylori) is one of the most common human pathogens, affecting half of the world’s population. Approximately 20% of the infected patients develop gastric ulcers or neoplastic changes in the gastric stroma. An infection also leads to the progression of epithelial–mesenchymal transition within gastric tissue, increasing the probability of gastric cancer development. This paper aims to review the role of H. pylori and its virulence factors in epithelial–mesenchymal transition associated with malignant transformation within the gastric stroma. The reviewed factors included: CagA (cytotoxin-associated gene A) along with induction of cancer stem-cell properties and interaction with YAP (Yes-associated protein pathway), tumor necrosis factor α-inducing protein, Lpp20 lipoprotein, Afadin protein, penicillin-binding protein 1A, microRNA-29a-3p, programmed cell death protein 4, lysosomal-associated protein transmembrane 4β, cancer-associated fibroblasts, heparin-binding epidermal growth factor (HB-EGF), matrix metalloproteinase-7 (MMP-7), and cancer stem cells (CSCs). The review summarizes the most recent findings, providing insight into potential molecular targets and new treatment strategies for gastric cancer.

Influence of the HER receptor ligand system on sensitivity to cetuximab and trastuzumab in gastric cancer cell lines

Purpose

Gastric cancer remains a major health concern, and improvement of the therapeutic options is crucial. Treatment with targeted therapeutics such as the EGFR-targeting antibody cetuximab or the HER2-targeting antibody trastuzumab is either ineffective or moderately effective in this disease, respectively. In this study, we analysed the involvement of the HER receptor ligands amphiregulin (AREG), epidermal growth factor (EGF), heparin-binding epidermal growth factor (HB-EGF) and transforming growth factor alpha (TGFα) in the responsiveness of gastric cancer cell lines to cetuximab and trastuzumab.

Methods

A panel of 11 gastric cancer cell lines was characterized for cetuximab and trastuzumab sensitivity, ligand secretion and expression and activation of the HER receptors using WST-1 cell proliferation assays, ELISAs and Western blot analyses. We further investigated the effects of an exogenous ligand application on the cetuximab and trastuzumab sensitivity.

Results

We found no correlation between TGFα secretion and the sensitivity to cetuximab or trastuzumab. For AREG, we confirmed previous results indicating that this ligand is a positive predictor of cetuximab sensitivity. Exogenous HB-EGF was effective in rescuing sensitive cell lines from inhibition of cell proliferation by both, cetuximab and trastuzumab.

Conclusions

Our data indicate that HB-EGF may be a useful marker for the prediction of trastuzumab sensitivity in gastric cancer.

Electronic supplementary material

The online version of this article (doi:10.1007/s00432-016-2308-z) contains supplementary material, which is available to authorized users.

Characterization of a Novel Anti-Human HB-EGF Monoclonal Antibody Applicable for Paraffin-Embedded Tissues and Diagnosis of HB-EGF-Related Cancers

Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family of growth factors that bind to and activate the EGF receptor (EGFR/ErbB1) and ErbB4. HB-EGF plays pivotal roles in pathophysiological processes, including cancer. Thus, monoclonal antibodies (mAbs) for HB-EGF detection could be an important tool in the therapeutic diagnosis of HB-EGF-related cancers and other diseases. However, few mAbs, especially those applicable for immunohistochemistry (IHC), have been established to date. In this study, we generated a clone of hybridoma-derived mAb 2-108 by immunizing mice with recombinant human HB-EGF protein expressed by human cells. The mAb 2-108 specifically bound to human HB-EGF but not to mouse HB-EGF and was successful in immunoblotting, even under reducing conditions, immunoprecipitation, and immunofluorescence for unfixed as well as paraformaldehyde-fixed cells. Notably, this mAb was effective in IHC of paraffin-embedded tumor specimens. Epitope mapping analysis showed that mAb 2-108 recognized the N-terminal prodomain in HB-EGF. These results indicate that this new anti-HB-EGF mAb 2-108 would be useful in the diagnosis of HB-EGF-related cancers and would be a strong tool in both basic and clinical research on HB-EGF.

Improving gastric cancer preclinical studies using diverse in vitro and in vivo model systems

BACKGROUND

"Biomarker-driven targeted therapy," the practice of tailoring patients' treatment to the expression/activity levels of disease-specific genes/proteins, remains challenging. For example, while the anti-ERBB2 monoclonal antibody, trastuzumab, was first developed using well-characterized, diverse in vitro breast cancer models (and is now a standard adjuvant therapy for ERBB2-positive breast cancer patients), trastuzumab approval for ERBB2-positive gastric cancer was largely based on preclinical studies of a single cell line, NCI-N87. Ensuing clinical trials revealed only modest patient efficacy, and many ERBB2-positive gastric cancer (GC) patients failed to respond at all (i.e., were inherently recalcitrant), or succumbed to acquired resistance.

METHOD

To assess mechanisms underlying GC insensitivity to ERBB2 therapies, we established a diverse panel of GC cells, differing in ERBB2 expression levels, for comprehensive in vitro and in vivo characterization. For higher throughput assays of ERBB2 DNA and protein levels, we compared the concordance of various laboratory quantification methods, including those of in vitro and in vivo genetic anomalies (FISH and SISH) and xenograft protein expression (Western blot vs. IHC), of both cell and xenograft (tissue-sectioned) microarrays.

RESULTS

The biomarker assessment methods strongly agreed, as did correlation between RNA and protein expression. However, although ERBB2 genomic anomalies showed good in vitro vs. in vivo correlation, we observed striking differences in protein expression between cultured cells and mouse xenografts (even within the same GC cell type). Via our unique pathway analysis, we delineated a signaling network, in addition to specific pathways/biological processes, emanating from the ERBB2 signaling cascade, as a potential useful target of clinical treatment. Integrated analysis of public data from gastric tumors revealed frequent (10 - 20 %) amplification of the genes NFKBIE, PTK2, and PIK3CA, each of which resides in an ERBB2-derived subpathway network.

CONCLUSION

Our comprehensive bioinformatics analyses of highly heterogeneous cancer cells, combined with tumor "omics" profiles, can optimally characterize the expression patterns and activity of specific tumor biomarkers. Subsequent in vitro and in vivo validation, of specific disease biomarkers (using multiple methodologies), can improve prediction of patient stratification according to drug response or nonresponse.

Enhancing tumor-specific intracellular delivering efficiency of cell-penetrating peptide by fusion with a peptide targeting to EGFR

Cell-penetrating peptides (CPPs) are well known as intracellular delivery vectors. However, unsatisfactory delivery efficiency and poor specificity are challenging barriers to CPP applications at the clinical trial stage. Here, we showed that S3, an EGFR-binding domain derived from vaccinia virus growth factor, when fused to a CPP such as HBD or TAT can substantially enhance its internalization efficiency and tumor selectivity. The uptake of S3-HBD (S3H) recombinant molecule by tumor cells was nearly 80 folds increased compared to HBD alone. By contrast, the uptake of S3H by non-neoplastic cells still remained at a low level. The specific recognition between S3 and its receptor, EGFR, as well as between HBD and heparan sulfate proteoglycans on the cell surface was essential for these improvements, suggesting a syngeneic effect between the two functional domains in conjugation. This syngeneic effect is likely similar to that of the heparin-binding epidermal growth factor, which is highly abundant particularly in metastatic tumors. The process that S3H entered cells was dependent on time, dosage, and energy, via macropinocytosis pathway. With excellent cell-penetrating efficacy and a novel tumor-targeting ability, S3H appears as a promising candidate vector for targeted anti-cancer drug delivery.

Epithelial cell ADAM17 activation by Helicobacter pylori: role of ADAM17 C-terminus and Threonine-735 phosphorylation

Helicobacter pylori transactivates the epidermal growth factor receptor (EGFR) on gastric epithelial cells via a signalling cascade involving a disintegrin and metalloprotease 17 (ADAM17) cleavage of membrane bound heparin binding-epidermal growth factor (HB-EGF). The effects of H. pylori on ADAM17 C-terminus in epithelial cells have been examined. Total cellular ADAM17 and surface expression of ADAM17 were significantly increased by H. pylori in AGS gastric epithelial cells. These changes were associated with ADAM17 C-terminal phosphorylation at T375 and S791. AGS cells lacking the ADAM17 C-terminal domain induced significantly attenuated cleavage of HB-EGF and were also unable to upregulate HB-EGF and EGFR transcripts to the same extent as cells expressing full length ADAM17. In mitotic unstimulated AGS and ADAM17 over-expressing AGS cells, ADAM17 was highly T735 phosphorylated indicating ADAM17 T735 phosphorylation is modified during the cell cycle. In conclusion, H. pylori induced ADAM17 C-terminal T735 and/or S791 phosphorylation in gastric epithelial cells are likely to be an important trigger inducing ADAM17 activation and shedding of HB-EGF leading to EGFR transactivation. ADAM17 over-expression in gastric cancer represents a potential target for therapeutic intervention.

Identification of diphtheria toxin R domain mutants with enhanced inhibitory activity against HB-EGF

Heparin-binding epidermal growth factor-like growth factor (HB-EGF), a ligand of EGF receptor, is involved in the growth and malignant progression of cancers. Cross-reacting material 197, CRM197, a non-toxic mutant of diphtheria toxin (DT), specifically binds to the EGF-like domain of HB-EGF and inhibits its mitogenic activity, thus CRM197 is currently under evaluation in clinical trials for cancer therapy. To develop more potent DT mutants than CRM197, we screened various mutant proteins of R domain of DT, the binding site for HB-EGF. A variety of R-domain mutant proteins fused with maltose-binding protein were produced and their inhibitory activity was evaluated in vitro. We found four R domain mutants that showed much higher inhibitory activity against HB-EGF than wild-type (WT) R domain. These R domain mutants suppressed HB-EGF-dependent cell proliferation more effectively than WT R domain. Surface plasmon resonance revealed their higher affinity to HB-EGF than WT R domain. CRM197(R460H) carrying the newly identified mutation showed increased cell proliferation inhibitory activity and affinity to HB-EGF. These results suggest that CRM197(R460H) or other recombinant proteins carrying newly identified mutation(s) in the R domain are potential therapeutics targeting HB-EGF.

Prognostic value of NF-κB, CD9, and VEGF in gastrointestinal stromal tumors

AIM OF THE STUDY

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal system. We aimed to determine whether nuclear transcription factor κB (NF-κB), CD9 and vascular endothelial growth factor (VEGF) have prognostic value in patients with GIST.

MATERIAL AND METHODS

Thirty-five patients with GIST, who were diagnosed in the Pathology Department of Erciyes University, were included in the study. Cases were classified based on the 2002 NIH consensus. CD9, VEGF, and NF-κB immunohistochemistry were applied to GIST cases positive for CD117 and CD34, which are used to evaluate GISTs immunohistochemically.

RESULTS

Although there are no statistically significant differences between NF-κB (p = 0.329), CD9 (p = 0.269), and VEGF (p = 0.372) and risk groups, 79.22% of cases that stained positive for NF-κB, 81% of cases that stained positive for CD9, and 80% of cases that stained positive of VEGF were in the high risk group.

CONCLUSIONS

It was found that NF-κB, CD9, and VEGF, which are important in predicting behaviors of other malign tumors, were expressed at high rates in high risk group GISTs. This can be used to determine prognosis with tumor diameter, mitosis rate under 50 BBS, Ki-67 proliferation index and other parameters.

Effects of EGFR Inhibitor on Helicobacter pylori Induced Gastric Epithelial Pathology in Vivo

Helicobacter pylori transactivates the Epidermal Growth Factor Receptor (EGFR) and predisposes to gastric cancer development in humans and animal models. To examine the importance of EGFR signalling to gastric pathology, this study investigated whether treatment of Mongolian gerbils with a selective EGFR tyrosine kinase inhibitor, EKB-569, altered gastric pathology in chronic H. pylori infection. Gerbils were infected with H. pylori and six weeks later received either EKB-569-supplemented, or control diet, for 32 weeks prior to sacrifice. EKB-569-treated H. pylori-infected gerbils had no difference in H. pylori colonisation or inflammation scores compared to infected animals on control diet, but showed significantly less corpus atrophy, mucous metaplasia and submucosal glandular herniations along with markedly reduced antral and corpus epithelial proliferation to apoptosis ratios. EKB-569-treated infected gerbils had significantly decreased abundance of Cox-2, Adam17 and Egfr gastric transcripts relative to infected animals on control diet. EGFR inhibition by EKB-569 therefore reduced the severity of pre-neoplastic gastric pathology in chronically H. pylori-infected gerbils. EKB-569 increased gastric epithelial apoptosis in H. pylori-infected gerbils which counteracted some of the consequences of increased gastric epithelial cell proliferation. Similar chemopreventative strategies may be useful in humans who are at high risk of developing H. pylori- induced gastric adenocarcinoma.

Heparin-binding EGF-like growth factor enhances the activity of invasion and metastasis in thyroid cancer cells

Thyroid cancer sometimes contains poorly differentiated components, which have the potential of invasion and metastasis. We evaluated the possible roles of heparin-binding EGF-like growth factor (HB-EGF), a member of the epidermal growth factor (EGF) family, in cell growth and invasion of thyroid cancer cells, and demonstrated that HB-EGF is not only a potent mitogen but also a chemotactic factor in the thyroid cancer cells 8305C and SW579. The HB-EGF-mediated chemotaxis was inhibited by neutralizing antibody against the EGF receptor (EGFR/HER1/ErbB1) or tyrphostin AG1478, a specific inhibitor of the EGFR tyrosine kinase. The HB-EGF mRNA and protein expression was also analyzed using RT-PCR and immunofluorescence methods, respectively. In addition, in clinical immunohistochemical study, increased expression of HB-EGF and its receptors, HER1 and EGFR4 (HER4/ErbB4), was observed in thyroid carcinoma cells. Our findings suggest that HB-EGF acts as a potent paracrine and/or autocrine chemotactic factor as well as a mitogen that mediates HER1 and/or HER4 in the invasion and metastasis of thyroid carcinoma cells, including poorly differentiated papillary carcinomas or undifferentiated/anaplastic carcinomas. These data may aid in the development of novel therapeutic strategies for thyroid cancer.

Identification of the cancer cell proliferation and survival functions of proHB-EGF by using an anti-HB-EGF antibody

PURPOSE

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the epidermal growth factor family. The membrane-bound proHB-EGF is known to be a precursor of the soluble form of HB-EGF (sHB-EGF), which promotes cell proliferation and survival. While the functions of sHB-EGF have been extensively studied, it is not yet fully understood if proHB-EGF is also involved in cellular signaling events. In this study, we utilized the anti-HB-EGF monoclonal antibodies Y-142 and Y-073, which have differential specificities toward proHB-EGF, in order to elucidate proHB-EGF functions in cancer cells.

EXPERIMENTAL DESIGN

The biological activities of proHB-EGF were assessed in cell proliferation, caspase activation, and juxtacrine activity assays by using a 3D spheroid culture of NUGC-3 cells.

RESULTS

Y-142 and Y-073 exhibited similar binding and neutralizing activities for sHB-EGF. However, only Y-142 bound to proHB-EGF. We could detect the function of endogenously expressed proHB-EGF in a 3D spheroid culture. Blocking proHB-EGF with Y-142 reduced spheroid formation, suppressed cell proliferation, and increased caspase activation in the 3D spheroid culture of NUGC-3 cells.

CONCLUSIONS

Our results show that proHB-EGF acts as a cell proliferation and cell survival factor in cancer cells. The results suggest that proHB-EGF may play an important role in tumor progression.

A potent anti-HB-EGF monoclonal antibody inhibits cancer cell proliferation and multiple angiogenic activities of HB-EGF

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the epidermal growth factor family and has a variety of physiological and pathological functions. Modulation of HB-EGF activity might have a therapeutic potential in the oncology area. We explored the therapeutic possibilities by characterizing the in vitro biological activity of anti-HB-EGF monoclonal antibody Y-142. EGF receptor (EGFR) ligand and species specificities of Y-142 were tested. Neutralizing activities of Y-142 against HB-EGF were evaluated in EGFR and ERBB4 signaling. Biological activities of Y-142 were assessed in cancer cell proliferation and angiogenesis assays and compared with the anti-EGFR antibody cetuximab, the HB-EGF inhibitor CRM197, and the anti-vascular endothelial growth factor (VEGF) antibody bevacizumab. The binding epitope was determined with alanine scanning. Y-142 recognized HB-EGF as well as the EGFR ligand amphiregulin, and bound specifically to human HB-EGF, but not to rodent HB-EGF. In addition, Y-142 neutralized HB-EGF-induced phosphorylation of EGFR and ERBB4, and blocked their downstream ERK1/2 and AKT signaling. We also found that Y-142 inhibited HB-EGF-induced cancer cell proliferation, endothelial cell proliferation, tube formation, and VEGF production more effectively than cetuximab and CRM197 and that Y-142 was superior to bevacizumab in the inhibition of HB-EGF-induced tube formation. Six amino acids in the EGF-like domain were identified as the Y-142 binding epitope. Among the six amino acids, the combination of F115 and Y123 determined the amphiregulin cross-reactivity and that F115 accounted for the species selectivity. Furthermore, it was suggested that the potent neutralizing activity of Y-142 was derived from its recognition of R142 and Y123 and its high affinity to HB-EGF. Y-142 has a potent HB-EGF neutralizing activity that modulates multiple biological activities of HB-EGF including cancer cell proliferation and angiogenic activities. Y-142 may have a potential to be developed into a therapeutic agent for the treatment of HB-EGF-dependent cancers.

Characterization of a variety of neutralizing anti-heparin-binding epidermal growth factor-like growth factor monoclonal antibodies by different immunization methods

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the epidermal growth factor family. The accumulated evidence on the tumor-progressing roles of HB-EGF has suggested that HB-EGF-targeted cancer therapy is expected to be promising. However, the generation of neutralizing anti-HB-EGF monoclonal antibodies (mAbs) has proved difficult. To overcome this difficulty, we performed a hybridoma approach using mice from different genetic backgrounds, as well as different types of HB-EGF immunogens. To increase the number of hybridoma clones to screen, we used an electrofusion system to generate hybridomas and a fluorometric microvolume assay technology to screen anti-HB-EGF mAbs. We succeeded in obtaining neutralizing anti-HB-EGF mAbs, primarily from BALB/c and CD1 mice, and these were classified into 7 epitope bins based on their competitive binding to the soluble form of HB-EGF (sHB-EGF). The mAbs showed several epitope bin-dependent characteristics, including neutralizing and binding activity to human sHB-EGF, cross-reactivity to mouse/rat sHB-EGF and binding activity to the precursor form of HB-EGF. The neutralizing activity was also validated in colony formation assays. Interestingly, we found that the populations of mAb bins and the production rates of the neutralizing mAbs were strikingly different by mouse strain and by immunogen type. We succeeded in generating a variety of neutralizing anti-HB-EGF mAbs, including potent sHB-EGF neutralizers that may have potential as therapeutic agents for treating HB-EGF-dependent cancers. Our results also suggest that immunization approaches using different mouse strains and immunogen types affect the biological activity of individual neutralizing antibodies.

Nuclear translocation of the cytoplasmic domain of HB-EGF induces gastric cancer invasion

Background

Membrane-anchored heparin-binding epidermal growth factor-like growth factor (proHB-EGF) yields soluble HB-EGF, which is an epidermal growth factor receptor (EGFR) ligand, and a carboxy-terminal fragment of HB-EGF (HB-EGF-CTF) after ectodomain shedding. We previously reported that HB-EGF-CTF and unshed proHB-EGF which has the cytoplasmic domain of proHB-EGF (HB-EGF-C), translocate from the plasma membrane to the nucleus and regulate cell cycle after shedding stimuli. However, the significance of nuclear exported HB-EGF-C in human gastric cancer is unclear.

Methods

We investigated the relationship between intracellular localization of HB-EGF-C and clinical outcome in 96 gastric cancer patients treated with gastrectomy. Moreover, we established stable gastric cancer cell lines overexpressing wild-type HB-EGF (wt-HB-EGF) and mutated HB-EGF (HB-EGF-mC), which prevented HB-EGF-C nuclear translocation after shedding. Cell motility between these 2 gastric cancer cell lines was investigated using a transwell invasion assay and a wound healing assay.

Results

Of the 96 gastric cancer cases, HB-EGF-C immunoreactivity was detected in both the nucleus and cytoplasm in 19 cases (19.8 %) and in the cytoplasm only in 25 cases (26.0 %). The nuclear immunoreactivity of HB-EGF-C was significantly increased in stage pT3/4 tumors compared with pT1/2 tumors (T1/2 vs. T3/4: 11.1 % vs. 36.4 %, P < 0.01). The growth of wt-HB-EGF- and HB-EGF-mC-expressing cells significantly increased compared with control cells, but the growth of HB-EGF-mC-expressing cells was significantly decreased compared with wt-HB-EGF-expressing cells. Gastric cancer cell invasion obviously increased in wt-HB-EGF-expressing cells, but invasion in HB-EGF-mC-expressing cells showed a slight increase compared with control cells. Moreover, wt-HB-EGF overexpression increased the effectiveness of wound healing, but had no significant effect in HB-EGF-mC-expressing cells.

Conclusions

Both the function of HB-EGF as an EGFR ligand and a novel signal for HB-EGF-C nuclear translocation induce gastric cancer growth, whereas HB-EGF-C nuclear translocation independently plays a critical role in gastric cancer invasion. The present study demonstrated that HB-EGF-C nuclear translocation might be crucial in gastric cancer invasion. HB-EGF-C nuclear translocation may offer a prognostic marker and a new molecular target for gastric cancer therapy.

Membrane type 1-matrix metalloproteinase cleaves off the NH2-terminal portion of heparin-binding epidermal growth factor and converts it into a heparin-independent growth factor

Epidermal growth factor (EGF) receptors (ErbB) and EGF family members represent promising targets for cancer therapy. Heparin-binding EGF (HB-EGF) is a member of the EGF family and is an important target for therapy in some types of human cancers. Processing of HB-EGF by proprotein convertases, and successively, by ADAM family proteases, generates a soluble growth factor that requires heparin as a cofactor. Although heparin potentiates HB-EGF activity in vitro, it is not clear how the heparin-binding activity of HB-EGF is regulated. Here, we show that membrane type 1-matrix metalloproteinase (MT1-MMP; MMP14), a potent invasion-promoting protease, markedly enhances HB-EGF-dependent tumor formation in mice. MT1-MMP additionally cleaves HB-EGF and removes the NH(2)-terminal 20 amino acids that are important for binding heparin. Consequently, the processing of HB-EGF by MT1-MMP converts HB-EGF into a heparin-independent growth factor with enhanced mitogenic activity, and thereby, expression of both proteins costimulates tumor cell growth in vitro and in vivo. The ErbB family of receptors expressed in human gastric carcinoma cells play a role in mediating enhanced HB-EGF activity by MT1-MMP during invasive cell growth in collagen. Thus, we shed light on a new mechanism whereby HB-EGF activity is regulated that should be considered when designing HB-EGF-targeted cancer therapy.

Prognostic significance of CD9 expression in locally advanced gastric cancer treated with surgery and adjuvant chemoradiotherapy

The tetraspanin transmembrane protein CD9 plays an important role in inhibiting cell motility in numerous neoplastic cell lines, including lung, gastric, pancreatic, and bladder carcinomas. The prognostic importance of CD9 in the survival of gastric carcinoma patients has not been examined to date, and in the present study, we attempted to define its prognostic value. The study included 49 (35 men and 14 women) patients with locally advanced (stages II-IV) gastric cancer. The median age was 55 years (range, 22-73 years). Surgery was the initial treatment for all patients, followed by adjuvant chemoradiotherapy. Tissue sections were evaluated immunohistochemically with a monoclonal anti-CD9 antibody. Of the 49 patients with gastric adenocarcinoma, 11 (22.4%) were CD9-positive, and 38 (77.6%) were CD9-negative. A significant prognostic value in disease-free survival and overall survival was observed in T classification and CD9 positivity. In conclusion, CD9 expression in gastric cancer appears to be associated with poor prognosis.

Histamine stimulation of MMP-1(collagenase-1) secretion and gene expression in gastric epithelial cells: role of EGFR transactivation and the MAP kinase pathway

BACKGROUND AND AIMS

GPCR stimulation by various ligands including histamine has been shown to transactivate the epidermal growth factor receptor (EGFR). This study examines the functional interactions between the H2 receptor and the EGFR in the regulation of matrix metalloproteinase-1 (MMP-1) secretion and gene expressions in cultured gastric epithelial cells.

METHODS

AGS cells were incubated for up to 24 h with either histamine or heparin binding-epidermal growth factor (HB-EGF) and MMP-1 release was determined by immunoassay. MMP-1 responses to histamine and HB-EGF were further tested by the use of H2 receptor antagonist, EGFR inhibitor and mitogen activator protein kinase (MAPK) inhibitor. The role of EGFR in MMP-1 release was further tested in cells transfected with specific EGFR siRNA. EGFR and ERK1/2 phosphorylation was determined by Western blot analysis. MMP-1 gene expression was determined by RNase protection assay (RPA).

RESULTS

Histamine and HB-EGF caused a dose-dependent release of MMP-1 with maximal responses that were 2.7- and 4.5-fold greater, respectively, than control, P<0.001. Famotidine prevented histamine-mediated MMP-1 release and AG1478 and EGFR siRNA completely inhibited MMP-1 secretion stimulated by both histamine and HB-EGF. Both histamine and HB-EGF stimulation of MMP-1 release was associated with activation of ERK1/2. MAPK inhibition also prevented histamine-and HB-EGF-induced MMP-1 secretion. Results of MMP-1 gene expression, either stimulatory or inhibitory, paralleled responses to MMP-1 secretion.

CONCLUSION

Histamine stimulation of the H2 receptor on AGS cells evoked MMP-1 secretion and gene up regulation that was dependent on transactivation of the EGFR and downstream activation of MAPK.

The epidermal growth factor family has a dual role in deciding the fate of cancer cells

Expression of the epidermal growth factor (EGF) receptors HER1 and HER2 has been implicated in tumour growth and poor survival, whereas expression of HER3 and HER4 has been associated with improved survival of bladder cancer patients. The balance between the expression of the EGF family members may therefore have a role to play in determining the final outcome in cancer cells. To check this, we examined the effect of HER1 activation and inhibition on the expression of the EGF receptors HER3 and HER4 and ligands - the heregulins (HRGs). RT4 bladder cancer cells were treated with 1nM HB-EGF (known to induce cell proliferation by activating HER1 receptor) and the mRNA content of the two receptors (HER3 and HER4) and their activating ligands (HRG1-HRG4) was quantified by real time PCR at indicated time-points. Expressions of HRG1alpha and HRG1beta increased 8-fold and 9-fold, respectively, whereas the expressions of HRG2alpha (4-fold), HRG2beta (2.5-fold) and HRG4 (3.5-fold) decreased. In contrast, inhibition of tyrosine kinase activity of HER1 with 5 microM Iressa (a specific inhibitor of HER1) resulted in an increase in mRNA expression of HRG2alpha (2.5-fold) and HRG4 (1.5-fold). In addition, expression of the receptors HER3 (1.5-fold) and HER4 (2-fold) was also increased. In conclusion, we demonstrate that activation of the HER1 receptor suppressed the expression of a specific set of HRGs. A decrease in expression of HRG2 and HRG4 during HB-EGF treatment supports their role in growth inhibition, whereas an increase in HRG1 expression points to a role as a growth stimulatory member of the EGF family.

Protease-activated receptor-2 activation in gastric cancer cells promotes epidermal growth factor receptor trans-activation and proliferation

Dysregulated epidermal growth factor receptor (EGFR) signaling is involved in gastric cancer (GC) cell growth. However, the mechanism that sustains EGFR signaling in GC remains unknown. Since protease-activated receptor-2 (PAR-2), a G protein-coupled receptor, has been shown to trans-activate EGFR in several cell types, we examined the role of PAR-2 in GC. We show here that in vitro activation of PAR-2 enhances the growth of two GC cell lines, AGS and MKN28. In both these cell lines, PAR-2 trans-activated EGFR and inhibition of EGFR tyrosine kinase activity by AG1478 or specific EGFR siRNA completely prevented PAR-2-driven proliferation. Antibody blockade of EGF-like ligands to EGFR did not modify EGFR signaling or cell growth induced by PAR-2 activation. In contrast, PAR-2 promoted Src activation and interaction of this kinase with EGFR. In support of this, inhibition of Src kinase activity by PP1 or siRNA blocked PAR-2-induced EGFR signaling cascade and cell growth. Finally, PAR-2 was detectable in both normal and GC specimens, but its expression was more pronounced in GC than controls and correlated with activated EGFR. These data show that PAR-2 is overexpressed in GC and suggest a role of PAR-2 in EGFR trans-activation and cell growth.

The cationic host defense peptide rCRAMP promotes gastric ulcer healing in rats

Cathelicidin, a cationic host defense peptide, has been shown to promote cutaneous wound repair and reaches high levels in the gastric mucosa during infection and inflammation. Therefore, we investigated whether this peptide contributes to gastric ulcer healing in rats. Ulcer induction increased the expression of rat cathelicidin rCRAMP in the gastric mucosa. Further increase in expression of rCRAMP by local injection of rCRAMP-encoding plasmid promoted ulcer healing by enhancing cell proliferation and angiogenesis. rCRAMP directly stimulated proliferation of cultured rat gastric epithelial cells (RGM-1), which was abolished by inhibitors of matrix metalloproteinase (MMP), epidermal growth factor receptors (EGFR) tyrosine kinase, or mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase. rCRAMP also increased EGFR and ERK1/2 phosphorylation via an MMP-dependent mechanism. Knockdown of transforming growth factor alpha (TGFalpha), which is a ligand of EGFR, by small interfering RNA completely nullified the mitogenic signals evoked by rCRAMP in RGM-1 cells. These findings suggest that rCRAMP exhibits prohealing activity in stomachs through TGFalpha-dependent transactivation of EGFR and its related signaling pathway to induce proliferation of gastric epithelial cells.

Tyrosine kinases in disease: overview of kinase inhibitors as therapeutic agents and current drugs in clinical trials

Tyrosine kinases, first described as oncogenes, have been shown to play a role in normal cellular processes. Aberrations in tyrosine kinase activity lead to disease states. For fifteen years it has been postulated that the inhibition of tyrosine kinases may have therapeutic utility and the design and testing of inhibitors have been major focuses of research and development in both academic institutions and pharmaceutical companies. While early research focused on developing chemical entities that mimic phosphotyrosine, later research has focused on developing competitive adenosine triphosphate (ATP) inhibitors with various levels of selectivity on kinase targets. This review focuses on a discussion of tyrosine kinases thought to be important in disease, including platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), vascular endothelial cell growth factor (VEGF), epidermal growth factor (EGF) receptors, HER-2 and Src. In addition, the classes of inhibitors designed to affect these targets and that have overcome research and development challenges and entered clinical trials are discussed. These include isoxazole, quinazoline, substituted pyrimidines and indolinone compounds, all of which are in clinical trials or near clinical development by SUGEN, Zeneca, Novartis, Pfizer and Parke-Davis. A summary of the chemistry and activity of these agents is provided.

Gefitinib (Iressa, ZD1839) inhibits SN38-triggered EGF signals and IL-8 production in gastric cancer cells

Epidermal growth factor receptor (EGFR) and its ligands are involved in tumor growth, metastasis, angiogenesis, and resistance to chemotherapy. In the experiments described here using AGS gastric cancer cells, SN38 (the active metabolite of CPT-11) induced tyrosine phosphorylation of EGFR within 5 min, and this was followed by the induction of transcripts and/or proteins of heparin-binding EGF-like growth factor, amphiregulin, transforming growth factor-alpha, and interlukin-8 (IL-8). SN38 also activates nuclear factor-kappaB and activator protein-1, both of which are critical for the transcription of the IL-8 gene. However, the blocking of EGFR activation by gefitinib (Iressa, ZD1839), an EGFR-TKI (tyrosine kinase inhibitor), abrogates all the above reactions. The SN38-triggered mechanisms include the generation of reactive oxygen species (ROS) and the activation of protein kinase C (PKC), followed by metalloproteinase activation and the sequential ectodomain shedding of EGFR ligands. These findings suggest that EGF signaling is enhanced by CPT-11 and point to the potential benefit of the use of a combination of CPT-11 with gefitinib in the treatment of certain gastric cancers.

Establishment of human gastric epithelial (HGE) cell lines exhibiting barrier function, progenitor, and prezymogenic characteristics

The unavailability of human cell lines representative of the gastric glandular epithelium while able to form a functional barrier restricts the application of a cell culture approach to the field of gastric epithelial physiology. In the current study, we have characterized new non-transfected clones isolated from gastric carcinoma cell lines known to express functional markers of the human gastric mucosa (J Cell Biochem 2001;81:241). Twenty-one clones exhibiting epithelial-type junctions (renamed HGE cell lines) were isolated from NCI-N87 (ATCC CRL 5822), whereas only squamous cell lines could be generated from other native strains. Of these 21 clones, HGE-17 and HGE-20 formed dense coherent monolayers and displayed true epithelial phenotype. E-cadherin and ZO-1 proteins were consistently localized at the periphery of all cells which also generated transepithelial electrical resistance. Moreover, growth factors known to be trophic for the gastric mucosa were able to stimulate mitogenesis at subconfluence. HGE-17 exhibited a poorly differentiated precursor-like status and responded strongly to EGF/TGFalpha treatment in restitution assays. HGE-20 cells, on the other hand, exhibited a higher degree of differentiation at the ultrastructural level as well as higher gastric lipase and pepsinogen levels. These latter zymogens were compartmentalized into granules which also contained mucin-6 (MUC6, prezymogenic-like status). Exogenous hormones, i.e., 1 mug/ml hydrocortisone and 5 microM retinoic acid, significantly increased enzyme levels in HGE-20. In conclusion, HGE-17 and HGE-20 represent the first human gastric cell lines with true epithelial characteristics, opening a venue to important applications for the study of re-epithelization, permeability, and regulation of digestive functions in the context of gastric physiology and pathology.

Gastrin and interleukin-1beta stimulate growth factor secretion from cultured rabbit gastric parietal cells

The hormone gastrin stimulates proliferation of the gastric mucosa. Inflammation of the stomach is also associated with increased proliferation. The proliferative response is important in the reparative response to injury but can be deleterious by predisposing to the development of cancer. Parietal cells, but not the cells in the proliferative zone of the gastric glands, express the appropriate gastrin receptor. Parietal cells may mediate the trophic effects of gastrin by secreting other growth factors. The role of parietal cells in the proliferative responses has been examined in this study. Rabbit parietal cells were cultured with gastrin or the cytokine interleukin-1beta for 18 hours. The conditioned medium from gastrin or IL-1beta stimulated parietal cells increased proliferation of HeLa cells in an epidermal growth factor-receptor dependant manner. Gastrin and IL-1beta stimulated the secretion of heparin-binding epidermal growth factor and amphiregulin but not transforming growth factor-alpha from parietal cells. Combinations of gastrin and IL-1beta on growth factor secretion were synergistic. The protein kinase C inhibitor staurosporine abolished these stimulatory effects of gastrin and IL-1beta. Divergent effects on histamine-stimulated acid secretion were observed; 18 hours pre-treatment with gastrin enhanced acid secretion by 50% but IL-1beta inhibited acid secretion in both control and gastrin pre-treated parietal cells. The acid-secreting parietal cell plays a central role in the regulation of mucosal proliferation in gastric inflammation. Secretion of paracrine growth factors by parietal cells may be an important point of integration between the endocrine and inflammatory stimuli in determining mucosal responses to injury and inflammation.

Gefitinib ("Iressa", ZD1839) inhibits SN38-triggered EGF signals and IL-8 production in gastric cancer cells

The epidermal growth factor receptor (EGFR) and its ligands are involved in tumor growth, metastasis, angiogenesis, and resistance to chemotherapy. The findings reported here demonstrate that SN38 (the active metabolite of CPT-11) induces the tyrosine phosphorylation of EGFR within 5 min, followed by the induction of transcripts and/or proteins of the heparin-binding EGF-like growth factor, amphiregulin, transforming growth factor-alpha, and interlukin-8 (IL-8) in AGS gastric cancer cells. SN38 also activates nuclear factor-kappa B and activator protein-1, both of which are critical for the transcription of the IL-8 gene. However, the blocking of EGFR activation by gefitinib ("Iressa", ZD1839), an EGFR-TKI (tyrosine kinase inhibitor), abrogates all the above reactions. The SN38-triggered mechanisms include the generation of reactive oxygen species (ROS) and the activation of protein kinase C (PKC), followed by metalloproteinase activation and the sequential ectodomain shedding of EGFR ligands. These findings suggest that EGF signaling is enhanced by CPT-11 and point to the potential benefit of the use of a combination of CPT-11 with gefitinib in the treatment of certain gastric cancers.

The mechanism of cleavage of EGFR ligands induced by inflammatory cytokines in gastric cancer cells

BACKGROUND & AIMS

The epidermal growth factor (EGF) receptor (EGFR) can be transactivated by many factors including G-protein-coupled receptor agonists and cytokines. Although this EGFR transactivation reportedly requires a disintegrin and metalloproteinase (ADAM) that sheds the ectodomain of EGFR ligands, the detailed mechanisms are still unknown. This study evaluated the mechanism of interleukin (IL)-8- and IL-1beta-dependent shedding of the EGFR ligand in KATO III cells.

METHODS

We established transfectants stably expressing alkaline phosphatase-tagged heparin-binding EGF-like growth factor (HB-EGF), transforming growth factor alpha, or amphiregulin precursors, and depleted ADAM proteins, using short interfering RNA against ADAM10, 12, or 17. We assessed shedding of EGFR ligands by measuring AP activities in the conditioned media after IL-1beta or IL-8 stimulation. EGFR activation was examined by immunoprecipitation and Western blotting using antiphosphotyrosine antibody. KB-R7785 and anti-IL-8 neutralizing antibody were used to inhibit activities of ADAMs and IL-8 action, respectively.

RESULTS

IL-8 dose dependently released the EGFR ligands and transiently phosphorylated EGFR, with a peak at 15 minutes. KB-R7785 completely blocked IL-8-induced shedding and EGFR transactivation. Depletion of ADAM10 also dramatically reduced IL-8-induced shedding and EGFR transactivation, but depletion of ADAM12 and 17 did not. IL-1beta dose dependently enhanced shedding of HB-EGF, which was not blocked by KB-R7785 in the early phase. In the late phase, however, the EGFR transactivation was blocked by KB-R7785 and abrogated by anti-IL-8 neutralizing antibody.

CONCLUSIONS

IL-8 induces shedding of EGFR ligands because of an ADAM10-dependent pathway in gastric cancer cells, whereas IL-1beta acts principally by an ADAM-independent pathway. IL-1beta-dependent prolonged EGFR transactivation involves multiple pathways, including an IL-8-dependent pathway.

CD9 expression in gastric cancer and its significance

BACKGROUND

The tetraspanin transmembrane protein CD9 is known to be involved in cell adhesion, proliferation, and cell motility. Previous studies have reported that reduced expression of CD9 is related to aggressive behavior of cancer cells. However, the cause-and-effect relationship between the CD9 expression level and the state of malignancy remains unclear. Here, we investigated the connection between the CD9 expression level and the state of malignancy in gastric cancers.

MATERIALS AND METHODS

The expression of CD9 was examined in primary and metastatic gastric carcinoma tissues. In total, specimens from 78 patients were used for immunohistological staining and specimens from 57 patients were subjected to Northern blotting. Paired samples of tumor/normal tissues obtained from five cases of gastric cancer were used for Western blotting.

RESULTS

CD9 expression was observed at both the message level and the protein level in primary gastric carcinoma tissues, lymph node metastatic tissues, and peritoneal dissemination tissues. Contrary to previous reports for other cancers, CD9 expression was intensified in cancerous areas of gastric cancers in comparison with noncancerous areas in the same patient. When analyzed by the malignancy status based on the clinicopathological diagnosis, there was a tendency that CD9 expression was observed in severe vessel invasion, active lymph node metastasis, and advanced stage.

CONCLUSIONS

CD9 expression was rather intensified in gastric cancer tissue in comparison with normal tissues. CD9 expression was more prominent in advanced gastric cancer.

Prevention of gastric cancer by Helicobacter pylori eradication

The evidence supporting the important role of Helicobacter pylori causing gastric cancer is getting stronger. The mechanisms by which H. pylori can influence the progression to severe changes in the gastric mucosa are under investigation. An increased gastric epithelial cell proliferation has been observed in individuals infected with H. pylori. This lifelong increased cell turnover is deemed to be a major risk factor for increased mutational changes and may lead to the development of gastric cancer. Successful eradication of H. pylori infection induces the healing of the gastritis and a significant decrease in gastric epithelial cell proliferation. Nevertheless, it is right now unknown at which time the point of no return, meaning at which time an eradication therapy leads to a benefit for the individual to prevent gastric cancer, has been reached. Therefore the major question that arises is to whom an eradication therapy should be offered to prevent gastric cancer. A general elimination of the infection might be worthwhile, but seems to be unrealistic now because of the high prevalence of the infection and the missing of a vaccine. This review reflects possible mechanisms of gastric cancer development induced by chronic H. pylori infection and recent investigational trials for prevention of gastric cancer by H. pylori eradication therapy will be discussed.

Transactivation of epidermal growth factor receptor after heparin-binding epidermal growth factor-like growth factor shedding in the migration of prostate cancer cells promoted by bombesin

BACKGROUND

A pathway consisting of bombesin, G-protein coupling receptors (GPCRs), metalloproteases, pro-heparin-binding epidermal growth factor (proHB-EGF), and epidermal growth factor receptor (EGFR) has been reported in prostate cancer cells. The occurrence of HB-EGF shedding from proHB-EGF in this pathway, however, has not been proven directly. In addition, it is still unclear how much this pathway contributes to the migration of prostate cancer cells. In this study, we tried to directly elucidate HB-EGF shedding in this pathway and to determine its contribution to the migration of prostate cancer cells.

METHODS

RT-PCR and indirect immunofluorescence staining for HB-EGF and its receptors, such as EGFR and HER4/erbB4, were performed on PC-3 cells. The influences of bombesin, anti-EGFR neutralizing monoclonal antibody, HB-EGF, and HB-EGF shedding inhibitor on the migration of PC-3 cells were studied by means of in vitro wound assays. The amount of HB-EGF shed from PC-3 cells with alkaline phosphatase-tagged HB-EGF in the presence of bombesin was determined by measuring AP activity. Immunoprecipitations and phosphotyrosine Western blotting were performed to detect EGFR transactivated by bombesin.

RESULTS

PC-3 expressed HB-EGF and EGFR, but not HER4/erbB4. PC-3 migrated in the presence of bombesin, but its migration was partly inhibited by the neutralizing antibody against EGFR. PC-3 also migrated in the presence of HB-EGF, but HB-EGF shedding inhibitor partly inhibited this phenomenon. HB-EGF was shed from PC-3 cells in the presence of bombesin, and this shedding was inhibited by HB-EGF shedding inhibitor. In addition, the EGFR on PC-3 was activated in the presence of bombesin and inactivated in the presence of HB-EGF shedding inhibitor.

CONCLUSIONS

These results indicated that HB-EGF shedding and the following transactivation of EGFR occurs in this pathway and that this pathway partly contributes to the migration of prostate cancer cells.

The role of ultraviolet irradiation and heparin-binding epidermal growth factor-like growth factor in the pathogenesis of pterygium

Ultraviolet (UV) light is one of the major factors implicated in the pathogenesis of pterygium. The mechanism by which UV light induces this disease remains elusive. The aim of this study was to evaluate the effects of UVB irradiation on the expression of growth factors in cultured pterygium epithelial cells and to demonstrate their distribution within pterygium. We cultured pterygial epithelial cells from pterygium explants and these cells were exposed to 20 mJ/cm(2) of UVB. Total RNA was extracted at 0, 6, and 12 hours after irradiation. (32)P-labeled cDNA was synthesized and analyzed using microarray technology to determine the differential expression of 268 growth factor and cytokine related genes. Semiquantitative reverse transcriptase-polymerase chain reaction was used to corroborate this data. Conditioned media derived from cells exposed to UVB irradiation was analyzed for protein expression by enzyme-linked immunosorbent assay. Immunohistochemistry was used to evaluate the distribution of heparin-binding epidermal growth factor-like growth factor (HB-EGF) in pterygium tissue. Analysis of the hybridization signals revealed that the genes encoding HB-EGF, fibroblast growth factor 3, and cytotoxic trail ligand receptor were consistently elevated at 6 and 12 hours after UVB treatment. HB-EGF mRNA was elevated 6.8-fold at 6 hours after irradiation and was augmented in culture supernatants after the same treatment. Furthermore, HB-EGF reactivity was identified in the epithelium and vasculature of pterygium by immunohistochemistry. HB-EGF was present in normal limbal epithelium, although it was not induced in cultured limbal epithelial cells by UV irradiation. HB-EGF is a potent mitogen, localized in pterygium tissue, and significantly induced by UVB in pterygium-derived epithelial cells. We postulate that this growth factor is a major driving force in the development of pterygia and a means by which UV irradiation causes the pathogenesis of pterygium.

Helicobacter pylori-stimulated EGF receptor transactivation requires metalloprotease cleavage of HB-EGF

Helicobacter pylori has a major aetiological role in human gastric carcinogenesis but the cellular and molecular pathways by which infection promotes transformation remain to be resolved. This study demonstrates that H. pylori exposure to MKN-1, ST42, and MKN-28 gastric epithelial tumour cells results in the activation of HB-EGF gene expression and EGFR tyrosine phosphorylation. These cell responses are induced by both cagPAI positive and cagPAI negative H. pylori strains and are dependent on cell surface expression of the HB-EGF precursor. The induction of HB-EGF gene transcription by H. pylori requires metalloprotease-, EGFR-, and Mek1-activities, indicating the involvement of the "triple membrane passing signal" (TMPS) for EGFR transactivation. Moreover, the release of the inflammatory cytokine IL-8 by cells exposed to H. pylori is significantly impaired by inhibitors of TMPS pathway elements. Our findings support a model in which H. pylori triggers constitutive EGFR signal activation, which enhances IL-8 production, and initiates neoplastic transformation of gastric epithelial cells.

Up-regulation of heparin binding epidermal growth factor-like growth factor and amphiregulin expression in Helicobacter pylori-infected human gastric mucosa

BACKGROUND

Host response plays a major role in pathogenesis of Helicobacter pylori-induced gastroduodenal disease including adenocarcinoma of distal stomach. Epidermal growth factor-related growth factors are important modulators of gastric homeostasis in normal and damaged gastrointestinal mucosa.

AIM

To evaluate expression of heparin binding epidermal growth factor and amphiregulin in antral mucosa of Helicobacter pylori-infected and non-infected dyspeptic patients and to correlate levels of heparin binding-epidermal growth factor and amphiregulin mRNA with mitogenic activity of gastric epithelial cells.

METHODS

A total of 10 Helicobacter pylori-infected and 15 Helicobacter pylori non-infected (10 with and 5 without gastritis) dyspeptic patients were studied. Diagnosis of Helicobacter pylori infection was based on rapid urease test and histology. Heparin binding-epidermal growth factor and amphiregulin mRNA expression in antral mucosa were assessed by reverse transcriptase-polymerase chain reaction. Protein expression and localization of both peptides were determined by immunohistochemistry. Mitogenic activity of antral gastric mucosa was assessed by determination of proliferating cell nuclear antigen labelling index by immunohistochemistry.

RESULTS

Heparin binding-epidermal growth factor and amphiregulin mRNA expression increased in Helicobacter pylori-infected vs Helicobacter pylori non-infected patients. Heparin binding-epidermal growth factor and amphiregulin immunostaining was more intense and deeper in gastric gland compartment in infected mucosa than in non-infected mucosa. Increase in heparin binding-epidermal growth factor and amphiregulin mRNA expression significantly correlated with increase in proliferating cell nuclear antigen labelling index.

CONCLUSIONS

Helicobacter pylori gastritis is associated with up-regulation of heparin binding-epidermal growth factor and amphiregulin which correlates with increased mitogenic activity of gastric mucosa. Increased heparin binding-epidermal growth factor and amphiregulin expression is postulated to contribute to reparative response of gastric mucosa to Helicobacter pylori infection.

Novel targets for lung cancer therapy: part I

Lung cancer is the second most common form of cancer in the United States, and although it accounts for 15% of all cancers, it is the most lethal, accounting for approximately 28% of cancer deaths. In 2002, it is estimated that 177,000 new cases of lung cancer will be diagnosed in the United States, and an estimated 160,000 men and women will die from the disease. This mortality rate is greater than that attributable to colorectal, breast, and prostate cancer combined. Systemic treatments for lung cancer with standard chemotherapy agents are still relatively ineffective. Agents targeting novel proliferative and survival pathways in lung cancer are needed to improve treatment outcomes. In recent years, numerous agents inhibiting aberrant processes in tumor cells have undergone clinical evaluation. This review is the first of a two-part series that summarizes pertinent preclinical and clinical information on novel drugs that target critical abnormalities in lung cancer. In this article, agents inhibiting growth factor receptors and various molecules downstream of activated signaling cascades, such as cytoplasmic second messengers, are described.

Effects of epidermal growth factor on the growth of human gastric cancer cell and the implanted tumor of nude mice

AIM: Epidermal growth factor (EGF) plays an important role in the regulation of gastrointestinal tissue growth and development, and it can stimulate epithelial proliferation, cell differentiation and growth. It has been established that the EGF can promote gastric cytoprotection and ulcer healing. But the potential ability of EGF to regulate the gastric cancer growth is unknown. This study is to investigate the influence of EGF on human gastric cancer cell and the implanted tumor growth of nude mice.

METHODS: The cell growth rates of human gastric adenocarinoma cell lines MKN-28, MKN-45, SGC-7901 and normal human gastric epithelial cells 3T3 were assessed when incubated with recombinant human EGF (rhEGF, 0.05, 0.1, 0.5, 1.0, 10, 50, 100 mg·L^-1) using MTT method. The cells of MKN-28, MKN-45, SGC-7901 (gastric cancer tissue 1.5 mm³) were implanted in the BALB/cA nude mice for 10 days. The EGF was given intraperitoneally (15, 30, 60 μg·kg^-1) for 3 weeks. The body weights of the tumor-bearing animals and their tumor mass were measured afterwards to assess the mitogenic effect of rhEGF in the nude mice.

RESULTS: Within the concentration range of 0.05-100 mg·L^-1, rhEGF could increase the cell growth of normal 3T3 cells (cell growth rate 100% vs 102.8%, P < 0.05), but partially restrain the gastric cancer cell growth. The latter effect was related to cell differentiation. In 15-60 μg/kg rhEGF groups, the mean implanted tumor mass of MKN-28 cell were 1.75 g, 1.91 g, 2.08 g/NS group 1.97 g (P > 0.05), the mean tumor mass of SGC-7901 cell were 1.53 g, 1.07 g, 1.20 g/NS group 1.07 g (P > 0.05), and for MKN-45 cell, the tumor mass were respectively 1.92 g, 1.29 g, 1.77 g/NS group 1.82 g (P > 0.05). So rhEGF had no obvious effect on implanted MKN-28, SGC-7901 and MKN-45 tumor growth.

CONCLUSION: EGF has no stimulating effect on the human gastric cancer cell growth neither in vitro nor in vivo.

Significance of the association between heparin-binding epidermal growth factor-like growth factor and CD9 in human gastric cancer

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the EGF family. Juxtacrine activity of proHB-EGF (the membrane-anchored form of HB-EGF) has been shown to be significantly potentiated when it is coexpressed with CD9 in vitro. The purpose of our study was to investigate the issue of whether proHB-EGF and CD9 are coexpressed in gastric cancer. HB-EGF gene expression and protein production in human gastric cancers was investigated, and EGF receptor and CD9 expressions were also evaluated. HB-EGF mRNA levels in gastric cancers were elevated, compared with normal gastric tissues, especially in the intestinal type. ProHB-EGF immunoreactivity was detected primarily in the cytoplasm and plasma membrane of gastric cancer cells. Of 66 patients, 40 (60.6%) exhibited proHB-EGF immunoreactivity and the level of its expression was significantly associated with tumor status (p < 0.01) and histological differentiation (p < 0.001). In addition, proHB-EGF mRNA was detected at high levels in the intestinal type by in situ hybridization. CD9 immunoreactivity was found to be preserved in 26 of 36 patients (72.2%) and CD9 protein expression was inversely associated with lymph node status (p < 0.05). A significant correlation between its expression and histological differentiation (p < 0.01) was found, and the association of CD9 with proHB-EGF was increased in the intestinal type, as evidenced by an immunoprecipitation method. These results indicate that the coexpression of proHB-EGF and CD9 may be involved in the tumorigenesis and/or proliferation of gastric cancers in a juxtacrine manner.

PPARgamma agonists inhibit cell growth and suppress the expression of cyclin D1 and EGF-like growth factors in ras-transformed rat intestinal epithelial cells

Peroxisome proliferator-activated receptor gamma (PPARgamma) inhibits the growth of several types of cancer cells. However, the mechanisms by which this occurs are poorly understood. The goal of the present study was to investigate the effects of PPARgamma on mutated ras-induced cell growth, activation of transcription factors and expression of genes associated with cellular transformation in rat intestinal epithelial cells. A human PPARgamma cDNA was introduced to the activated H-ras-transfected IEC-6 cells (IECras) and 1 clone (IECrasPR82) that stably expresses both activated ras and PPARgamma was obtained. Thiazolidinedione derivatives such as troglitazone and rosiglitazone, selective ligands for PPARgamma, inhibited the cellular growth of IECrasPR82 cells in a time-dependent manner and induced G1 cell cycle arrest. Treatment with troglitazone (20 microM) decreased the expression of cyclin D1, heparin-binding epidermal growth factor-like growth factor (HB-EGF) and amphiregulin and suppressed the promoter activities of cyclin D1 and HB-EGF. Furthermore, a luciferase assay and an electrophoretic mobility shift assay showed that thiazolidinedione derivatives suppressed the transcriptional activities of AP-1 and Ets, both of which play crucial roles in the expression of cyclin D1 and HB-EGF. These findings suggest that reduction of EGF-like growth factors and cyclin D1 through the suppression of AP-1 and Ets may be 1 mechanism whereby PPARgamma inhibits their growth.

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.

Regulation of heparin-binding EGF-like growth factor expression in Ha-ras transformed human mammary epithelial cells

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) mRNA and protein expression is induced by EGF in MCF-10A nontransformed and Ha-ras transfected human mammary epithelial cells. The anti-EGF receptor (EGFR) blocking monoclonal antibody (MAb) 225 and the EGFR tyrosine kinase inhibitor PD153035 were able to inhibit the induction of HB-EGF mRNA levels in MCF-10A cells. However, the Ha-ras transformed MCF-10A cells were more refractory to inhibition by these agents and only a combination of the 225 MAb and PD153035 was able to significantly abrogate HB-EGF induction by EGF. The anti-erbB2 MAb L26 which interferes with heterodimer formation was able to block HB-EGF induction in response to EGF in MCF-10A cells and in the Ha-ras transformed cells only when used in combination with either the 225 MAb or PD153035. The MEK inhibitor PD90859 completely blocked EGF induction of HB-EGF mRNA levels in the nontransformed and Ha-ras transformed MCF-10A cells, which indicates that MAPK is involved in the signaling pathway of HB-EGF induction by EGF. An increase in the levels of HB-EGF may, therefore, be an important contributor to oncogenic transformation that is caused by Ha-ras overexpression in mammary epithelial cells. J. Cell. Physiol. 186:233-242, 2001. Published 2001 Wiley-Liss, Inc.

Activated mesothelial cells produce heparin-binding growth factors: implications for tumour metastases

Curative surgery for gastrointestinal malignancy is commonly thwarted by local tumour recurrence. The heparin-binding growth factors, basic fibroblast growth factor (bFGF), heparin-binding epidermal growth factor-like growth factor (HB-EGF) and vascular epidermal growth factor (VEGF) are all implicated in the metastatic process, but whether or not these essential growth factors are produced by the activated peritoneum is unknown. This study reveals that peritoneal mesothelial cells constitutively express mRNA for bFGF, HB-EGF and two VEGF spliced variants, VEGF121 and VEGF165. Mesothelial activation with interleukin (IL)-1b or tumour necrosis factor (TNF)-a produced an up-regulation of mRNA for HB-EGF and VEGF, but not bFGF expression. IL-6 failed to stimulate growth factor expression, whereas IL-2 produced a marked suppression in HB-EGF and bFGF, but not VEGF expression. Mesothelial cells were shown to predominantly express mRNA for the intermediate affinity (bg(c)) IL-2 receptor. Cytokine-induced growth factor up-regulation was confirmed at the protein level using Western blotting of mesothelial cell lysates for HB-EGF and culture supernatant enzyme-linked immunosorbent assay for VEGF. The production of these growth factors by human mesothelial cells may play a significant role in post-operative peritoneal tumour recurrence. Their common heparin-binding property offers a potential therapeutic target for manipulating the growth factor environment of the human peritoneum.

Induction of anchorage independent growth by heparin-binding EGF-like growth factor (HB-EGF)

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is initially synthesized as a membrane bound protein that is subsequently processed to yield an approximately 74 amino acid secreted product. To investigate the biological activities of HB-EGF and its role(s) in tumor formation, the full-length HB-EGF cDNA was cloned under the regulation of the mouse metallothionein promoter and stably expressed in HB-EGF deficient mouse L cells. HB-EGF immunoreactive proteins of 21 and 24 kDa were observed from transfected MLC lysates, and these lysates exhibited the ability to bind to the EGF receptor, stimulate 3H-thymidine uptake in BALB/c-3T3 cells, and induce anchorage independent growth (AIG) of normal rat kidney (NRK) cells. Furthermore, NRK cells treated with either E. coli-derived or vaccinia virus-derived HB-EGF, as well as NRK cells directly transfected with the HB-EGF construct, demonstrated AIG. We conclude that HB-EGF is a potent growth factor capable of stimulating altered cell growth and anchorage independence.

Helicobacter pylori culture supernatant interferes with epidermal growth factor-activated signal transduction in human gastric KATO III cells

The mechanisms by which Helicobacter pylori infection leads to gastroduodenal ulceration remain poorly understood. Previous studies have shown that H. pylori vacuolating cytotoxin (VacA) inhibits proliferation of gastric epithelial cells, which suggests that H pylori may interfere with gastric mucosal repair mechanisms. In this study, we investigated the effects of H. pylori broth culture supernatants on epidermal growth factor (EGF)-mediated signal transduction pathways in a gastric carcinoma cell line (KATO III). Exposure of these cells to EGF resulted in increased expression and phosphorylation of the EGF receptor (EGF-R), increased ERK2 activity and phosphorylation, and increased c-fos protein levels. Preincubation of cells with broth culture supernatant from VacA (+) H. pylori strain 60190 inhibited the capacity of EGF to induce each of these effects. In contrast, preincubation of cells with broth culture supernatant from an isogenic VacA-mutant strain (H. pylori 60190-v1) failed to inhibit the effects of EGF. These results suggest that the H. pylori vacuolating cytotoxin interferes with EGF-activated signal transduction pathways, which are known to be essential for cell proliferation and ulcer healing.

Intercellular communication between vascular smooth muscle and endothelial cells mediated by heparin-binding epidermal growth factor-like growth factor and vascular endothelial growth factor

Heparin-binding epidermal growth factor-like growth factor (HB-EGF), a potent mitogen and migration factor for vascular smooth muscle cells (SMC), promoted neovascularization in vivo in the rabbit cornea. MRI demonstrated quantitatively the angiogenic effect of HB-EGF when introduced subcutaneously into nude mice. HB-EGF is not directly mitogenic to endothelial cells but it induced the migration of bovine endothelial cells and release of endothelial cell mitogenic activity from bovine vascular SMC. This mitogenic activity was specifically blocked by neutralizing anti-vascular endothelial growth factor (VEGF) antibodies. In contrast, EGF or transforming growth factor-alpha (TGF-alpha) had almost no effect on release of endothelial mitogenicity from SMC. In addition, RT-PCR analysis demonstrated that VEGF165 mRNA levels were increased in vascular SMC 4-10-fold by 0.35-2 nM of HB-EGF, respectively. Our data suggest that HB-EGF, as a mediator of intercellular communication, may play a new important role in supporting wound healing, tumor progression and atherosclerosis by stimulating angiogenesis.

The role of epidermal growth factor (EGF) and its receptor in mucosal protection, adaptation to injury, and ulcer healing: involvement of EGF-R signal transduction pathways

Growth factors and their receptors are known to play important roles in normal cell proliferation, morphogenesis, tissue repair, and ulcer healing. Epidermal growth factor (EGF) inhibits acid secretion, exerts a trophic effect on gastroduodenal mucosa, protects gastric mucosa against injury, mediates mucosal adaptation, and accelerates gastroduodenal ulcer healing by stimulating cell migration and proliferation. EGF exerts its actions by binding to its receptor, EGF-R, a transmembrane protein tyrosine kinase, which triggers receptor dimerization, autophosphorylation, and recruitment of kinase substrates. These events result in Ras (GTP-binding protein) activation of the Ras/Raf/MAP kinase pathway, leading to phosphorylation of regulatory proteins and transcription factors and culminating in cell proliferation. Other pathways potentially activated by EGF include the phosphatidylinositol pathway and the JAK/STAT signaling pathway. Recent studies demonstrated that EGF-R-associated tyrosine kinase plays an essential role in regulating gastric mucosal cell proliferation after acute injury and further demonstrated activation of the EGF-R gene, EGF-R phosphorylation, and increased MAP kinase activity during early stages of experimental gastric ulcer healing. Finally, experimental data indicate that Helicobacter pylori vacuolating cytotoxin inhibits healing of experimental gastric ulcers, cell proliferation, binding of EGF to its receptor, EGF-induced EGF-R phosphorylation, and MAP kinase (ERK-2) activation. These H. pylori actions can explain its interference with the ulcer healing process.

Heparin-binding EGF-like growth factor

HB-EGF is a heparin-binding member of the EGF family that was initially identified in the conditioned medium of human macrophages. Soluble mature HB-EGF is proteolytically processed from a larger membrane-anchored precursor and is a potent mitogen and chemotactic factor for fibroblasts, smooth muscle cells but not endothelial cells. HB-EGF activates two EGF receptor subtypes, HER1 and HER4 and binds to cell surface HSPG. The transmembrane form of HB-EGF is a juxtacrine growth and adhesion factor and is uniquely the receptor for diphtheria toxin. HB-EGF gene expression is highly regulated, for example by cytokines, growth factors, and transcription factors such as MyoD. HB-EGF has been implicated as a participant in a variety of normal physiological processes such as blastocyst implantation and wound healing, and in pathological processes such as tumor growth, SMC hyperplasia and atherosclerosis.

Immunohistochemical localization of heparin-binding epidermal growth factor-like growth factor in normal skin and skin cancers

Heparin-binding epidermal growth factor (EGF)-like growth factor is a 22-kDa glycoprotein that was originally identified as a secreted product of cultured human macrophages. Although the growth factor mRNA has been identified in various cells and tissues, the tissue distribution of the protein itself has rarely been demonstrated. In this study, the EGF-like growth factor was detected immunohistochemically in a variety of human skin samples by indirect immunofluorescence using a polyclonal rabbit antiserum raised against residues 26-41 of mature heparin-binding EGF. The keratinocytes of a variety of epithelium-derived structures demonstrated reproducible, specific staining for the EGF. In normal tissues, this staining was prominent in the basal cells of the epidermis and in the epithelial cells lining epidermal appendages such as hair follicles, sebaceous sweat glands and eccrine sweat glands. In addition, specific staining was detected in skin cancers derived from the basal epithelial cell layer, including basal and squamous cell carcinomas of the skin, with no staining detected in melanoma specimens. Immunoreactive heparin-binding EGF was characteristically associated with the surface of cells. With minor exceptions, the immunoreactive sites are identical to the known EGF receptor distribution in the skin, and suggest that keratinocyte-derived heparin-binding EGF may act in concert with other EGF family members in processes such as skin morphogenesis and wound repair, as well as in the development of skin cancers.