Clinical implications of the EGF receptor/ligand system for tumor progression and survival in gastrointestinal carcinomas: evidence for new therapeutic options

Hepatobiliary surgeons meet immunologists: the case of colorectal liver metastases patients

The burgeoning field of cancer immunology demands a change in the paradigm of cancer patient management. The understanding of the course of a given malignant disease should also include the host immune system as one of the key factors in determining the patient's prognosis. Surgical and medical oncologists need to understand the basic and advanced applications of immunotherapies, which are rapidly evolving, and are nowadays an integral part of the armamentarium for the treatment of cancer patients. In the present work, we review the current knowledge concerning the immune landscape of colorectal cancer (CRC) patients with liver metastases, as recently discovered.

Mechanisms Underlying the Action and Synergism of Trastuzumab and Pertuzumab in Targeting HER2-Positive Breast Cancer

Human epidermal growth factor receptor (HER) 2 (HER2) is overexpressed in 20⁻30% of breast cancers. HER2 is a preferred target for treating HER2-positive breast cancer. Trastuzumab and pertuzumab are two HER2-targeted monoclonal antibodies approved by the Food and Drug Administration (FDA) to use as adjuvant therapy in combination with docetaxel to treat metastatic HER2-positive breast cancer. Adding the monoclonal antibodies to treatment regimen has changed the paradigm for treatment of HER2-positive breast cancer. Despite improving outcomes, the percentage of the patients who benefit from the treatment is still low. Continued research and development of novel agents and strategies of drug combinations is needed. A thorough understanding of the molecular mechanisms underlying the action and synergism of trastuzumab and pertuzumab is essential for moving forward to achieve high efficacy in treating HER2-positive breast cancer. This review examined and analyzed findings and hypotheses regarding the action and synergism of trastuzumab and pertuzumab and proposed a model of synergism based on available information.

The Shifting Paradigm of Prognostic Factors of Colorectal Liver Metastases: From Tumor-Centered to Host Immune-Centered Factors

The determinants of prognosis in patients with colorectal liver metastases (CLM) have been traditionally searched among the tumoral factors, either of the primary colorectal tumor or of the CLM. While many different scoring systems have been developed based on those clinic-pathological factors with disparate results, there has been the introduction of genetic biological markers that added a theranostic perspective. More recently, other important elements, such as those factors related to the host immune system, have been proposed as determinants of prognosis of CLM patients. In the present work, we review the current prognostic factors of CLM patients as well as the burgeoning shifting paradigm of prognostication that relies on the host immune system.

ErbB Receptors and Cancer

The ErbB receptor family, also known as the EGF receptor family or type I receptor family, includes the epidermal growth factor (EGF) receptor (EGFR) or ErbB1/Her1, ErbB2/Her2, ErbB3/Her3, and ErbB4/Her4. Among all RTKs, EGFR was the first RTK identified and the first one linked to cancer. Thus, EGFR has also been the most intensively studied among all RTKs. ErbB receptors are activated after homodimerization or heterodimerization. The ErbB family is unique among the various groups of receptor tyrosine kinases (RTKs) in that ErbB3 has impaired kinase activity, while ErbB2 does not have a direct ligand. Therefore, heterodimerization is an important mechanism that allows the activation of all ErbB receptors in response to ligand stimulation. The activated ErbB receptors bind to many signaling proteins and stimulate the activation of many signaling pathways. The specificity and potency of intracellular signaling pathways are determined by positive and negative regulators, the specific composition of activating ligand(s), receptor dimer components, and the diverse range of proteins that associate with the tyrosine phosphorylated C-terminal domain of the ErbB receptors. ErbB receptors are overexpressed or mutated in many cancers, especially in breast cancer, ovarian cancer, and non-small cell lung cancer. The overexpression and overactivation of ErbB receptors are correlated with poor prognosis, drug resistance, cancer metastasis, and lower survival rate. ErbB receptors, especially EGFR and ErbB2 have been the primary choices as targets for developing cancer therapies.

Relationship between Preoperative ¹⁸F-Fluorodeoxyglucose Uptake and Epidermal Growth Factor Receptor Status in Primary Colorectal Cancer

PURPOSE

Both ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake and epidermal growth factor receptor (EGFR) status are prognostic variables of colorectal cancer (CRC). The aim of this study was to investigate a possible association between ¹⁸F-FDG uptake on preoperative positron emission tomography/computed tomography (PET/CT) and EGFR status in primary CRC.

MATERIALS AND METHODS

Records of 132 patients (66 men and 66 women; mean age=67.1±11.1 years) who underwent ¹⁸F-FDG PET/CT for CRC staging and subsequent bowel resection were reviewed. In primary lesions, ¹⁸F-FDG uptake was semiquantitatively evaluated in terms of maximum standardized uptake value (SUVmax), and EGFR status was determined by immunohistochemistry. Associations of clinicopathological parameters and EGFR status were analyzed by Pearson's chi-square test, multiple logistic regression, and receiver operating characteristic curves.

RESULTS

Eighty-six patients (65.2%) showed EGFR expression. SUVmax was significantly lower in EGFR-negative tumors than in EGFR-expressing tumors (10.0±4.2 vs. 12.1±2.1; p=0.012). It was the only significant parameter correlated with EGFR expression (odds ratio=2.457; relative risk=2.013; p=0.038). At the SUVmax threshold of 7.5, the sensitivity and specificity for predicting EGFR expression were 84.9% and 40.4%, respectively (area under the curve=0.624; p=0.019).

CONCLUSION

Preoperative ¹⁸F-FDG uptake is slightly correlated with EGFR status in primary CRC. Preoperative SUVmax of ¹⁸F-FDG may have a limited role in predicting EGFR expression in such tumors because of its poor specificity.

The prognostic significance of tumor epidermal growth factor receptor (EGFR) expression change after neoadjuvant chemoradiation in patients with rectal adenocarcinoma

Aim of the study

The aim of this retrospective study was to determine the prognostic impact of epidermal growth factor receptor (EGFR) expression changes during neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer.

Material and methods

Fifty patients with locally advanced rectal cancer were evaluated. All the patients were administered the total dose of 44 Gy. Capecitabine has been concomitantly administered in the dose 825 mg/m² in two daily oral administrations. Surgery was indicated 4–8 weeks from the chemoradiotherapy completion. Epidermal growth factor receptor expression in the pretreatment biopsies and in the resected specimens was assessed with immunohistochemistry.

Results

All of 50 patients received radiotherapy without interruption up to the total planned dose. In 30 patients sphincter-saving surgery was performed, 20 patients underwent amputation of the rectum. Downstaging was described in 30 patients. Four patients have had complete pathologic remission. Twenty-six patients have had partial remission, the disease was stable in 15 patients. Progression was reported in 5 patients. The median disease-free survival was 64.9 months, median overall survival was 76.4 months. Increased EGFR expression was found in 12 patients (26.1%). A statistically significantly shorter overall survival (p < 0.0001) and disease-free survival (p < 0.0001) was found in patients with increased expression of EGFR compared with patients where no increase in the expression of EGFR during neoadjuvant chemoradiotherapy was observed.

Conclusions

The overexpression of EGFR during neoadjuvant chemoradiotherapy for locally advanced rectal adenokarcinoma associated with significant shorter overall survival and disease free survival.

Prognostic implications of EGFR and HER-2 alteration assessed by immunohistochemistry and silver in situ hybridization in gastric cancer patients following curative resection

BACKGROUND

The aim of this study was to use immunohistochemistry (IHC) and silver in situ hybridization (SISH) to evaluate alterations in EGFR and HER2 in gastric cancer in order to determine the relationship with prognosis in gastric cancer patients following curative resection.

PATIENTS AND METHODS

In this study, we analyzed EGFR and HER-2 status by IHC and SISH in 254 stage I-III gastric cancer patients who underwent curative surgery.

RESULTS

Thirteen cases (2.48 %) showed EGFR alteration by IHC or SISH. EGFR alteration was associated with older age (P = 0.021), intestinal type (P = 0.040) and higher stage disease (P < 0.001). The patients with operable state gastric cancer who had EGFR alteration had an unfavorable prognosis, and multivariate analysis confirmed that EGFR alteration was an independent unfavorable prognostic factor. Twenty-seven cases (10.6 %) showed HER-2 alteration by IHC or SISH. HER-2 alteration was associated with older age (P = 0.006), well or moderately differentiated histology (P < 0.001) and intestinal type (P = 0.002).

CONCLUSION

HER-2 alteration is not an independent prognostic factor for curatively resectable gastric cancer. We observed EGFR alteration in a subset of cases with operable state gastric cancer and determined that it was associated with an unfavorable prognosis.

Asporin participates in gastric cancer cell growth and migration by influencing EGF receptor signaling

Asporin (ASPN), a novel member of the small leucine-rich proteoglycan (SLRP) family, serves as a key component of the tumor stroma and has been reported to be abnormally expressed in certain types of tumors. Specifically, the proteoglycan was proven to activate the coordinated invasion of scirrhous gastric cancer and cancer-associated fibroblasts. However, the role of ASPN in cancer cell growth and metastasis has not yet been addressed. In the present study, we aimed to evaluate the tumoricidal benefits of ASPN on tumorigenesis and progression of gastric cancer. Firstly, it was demonstrated that ASPN was overexpressed in gastric carcinoma tissues when compared to the corresponding non‑cancerous tissues, and it had varied levels of expression in gastric cancer epithelial cell lines. Additionally, we assessed the effects of transient siRNA‑mediated ASPN knockdown on gastric cancer cells. ASPN silencing inhibited proliferation and suppressed the migration of immortalized neoplastic epithelial cells. Furthermore, at the molecular level, we found that downregulation of ASPN blocked the anti-apoptotic molecule Bcl-2, increased the expression of pro-apoptotic molecule Bad, reduced the expression of migration-related proteins CD44 and matrix metalloproteinase (MMP)-2, and abrogated the activation of the phosphorylation status of ERK and epidermal growth factor (EGF) and its receptor (EGFR). Collectively, our findings indicate that ASPN is upregulated and plays an oncogenic role in gastric cancer progression and metastasis by influencing the EGFR signaling pathway.

Efficacy of an EGFR-specific peptide against EGFR-dependent cancer cell lines and tumor xenografts

We have recently synthesized a peptide called Disruptin, which comprised the SVDNPHVC segment of the epidermal growth factor receptor (EGFR) that inhibits binding of heat shock protein 90 (Hsp90) to the EGFR and EGF-dependent EGFR dimerization to cause EGFR degradation. The effect is specific for EGFR versus other Hsp90 client proteins [Ahsan et al.: (2013). Destabilization of the epidermal growth factor receptor (EGFR) by a peptide that inhibits EGFR binding to heat shock protein 90 and receptor dimerization. J Biol Chem288, 26879-26886]. Here, we show that Disruptin decreases the clonogenicity of a variety of EGFR-dependent cancer cells in culture but not of EGFR-independent cancer or noncancerous cells. The selectivity of Disruptin toward EGFR-driven cancer cells is due to the high level of EGF stimulation of EGFR in EGFR-dependent tumor cells relative to normal cells. When administered by intraperitoneal injection into nude mice bearing EGFR-driven human tumor xenografts, Disruptin causes extensive degradation of EGFR in the tumor but not in adjacent host tissue. Disruptin markedly inhibits the growth of EGFR-driven tumors without producing the major toxicities caused by the Hsp90 inhibitor geldanamycin or by cisplatin. These findings provide proof of concept for development of a new Disruptin-like class of antitumor drugs that are directed specifically against EGFR-driven tumors.

Functions and regulation of MUC13 mucin in colon cancer cells

BACKGROUND

MUC13 is overexpressed and aberrantly localized in colon cancer tissue; however, the specific functions and regulation of MUC13 expression are unknown.

METHODS

Stable cell lines with either overexpressed or suppressed MUC13 levels were analyzed to determine cell growth, colony formation, cell migration, and cell invasion assays. The molecular mechanisms involved in MUC13 regulation were elucidated via chromatin immunoprecipitation (ChIP) and analysis of interleukin 6 (IL6) treatments. Colon cancer tissues were analyzed by immunohistochemistry (IHC) for the protein levels of MUC13 and P-STAT5 in colon cancer cells.

RESULTS

Overexpression of MUC13 increased cell growth, colony formation, cell migration, and invasion. In concordance, MUC13 silencing decreased these tumorigenic features. Overexpression of MUC13 also modulated various cancer-associated proteins, including telomerase reverse transcriptase, sonic hedgehog, B cell lymphoma murine like site 1, and GATA like transcription factor 1. Additionally, MUC13-overexpressing cells showed increased HER2 and P-ERK expression. ChIP analysis revealed binding of STAT5 to the predicted MUC13 promoter. IL6 treatment of colon cancer cells increased the expression of MUC13 via activation of the JAK2/STAT5 signaling pathway. Suppression of JAK2 and STAT5 signaling by chemical inhibitors abolished IL6-induced MUC13 expression. IHC analysis showed increased expression of both P-STAT5 and MUC13 in colon cancer as compared to adjacent normal tissue.

CONCLUSIONS

The results of this study, for the first time, suggest functional roles of MUC13 in colon cancer progression and provide information regarding the regulation of MUC13 expression via JAK2/STAT5 which may reveal promising therapeutic approaches for colon cancer treatment.

Cell surface epidermal growth factor receptors increase Src and c-Cbl activity and receptor ubiquitylation

There is an established role for the endocytic pathway in regulation of epidermal growth factor receptor (EGFR) signaling to downstream effectors. However, because ligand-mediated EGFR endocytosis utilizes multiple "moving parts," dissecting the spatial versus temporal contributions has been challenging. Blocking all endocytic trafficking can have unintended effects on other receptors as well as give rise to compensatory mechanisms, both of which impact interpretation of EGFR signaling. To overcome these limitations, we used epidermal growth factor (EGF) conjugated to polystyrene beads (EGF beads). EGF beads simultaneously activate the EGFR while blocking its endocytosis and allow analysis of EGFR signaling from the plasma membrane. Human telomerase immortalized corneal epithelial (hTCEpi) cells were used to model normal epithelial cell biology. In hTCEpi cells, both cell surface and intracellular EGFRs exhibited dose-dependent increases in effector activity after 15 min of ligand stimulation, but only the serine phosphorylation of signal transducer and activator of transcription 3 (STAT3) was statistically significant when accounting for receptor phosphorylation. However, over time with physiological levels of receptor phosphorylation, cell surface receptors produced either enhanced or sustained mitogen-activated protein kinase kinase (MEK), Casitas B-lineage lymphoma (c-Cbl), and the pro-oncogene Src activity. These increases in effector communication by cell surface receptors resulted in an increase in EGFR ubiquitylation with sustained ligand incubation. Together, these data indicate that spatial regulation of EGFR signaling may be an important regulatory mechanism in receptor down-regulation.

Gefitinib and celecoxib in advanced metastatic gastrointestinal tumors: a pilot feasibility study

BACKGROUND

This pilot, open-label study examined the safety and tolerability (primary objective) and efficacy (secondary objective) of gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, in combination with celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, in patients with advanced or refractory gastrointestinal (GI) tumors of epithelial origin.

METHODS

Patients were administered gefitinib (250 mg/day) plus celecoxib (400 mg twice daily). In the event of toxicity, dose interruptions were permitted and a single celecoxib dose reduction was allowed.

RESULTS

Thirty patients (median age 60 years) with primary colorectal (25 patients), pancreatic (3 patients), esophageal (1 patient), or gall bladder (1 patient) tumors were recruited, 29 of whom had received prior chemotherapy. Adverse events (AEs) were generally mild and consisted mainly of acne, diarrhea, and nausea. Few severe AEs were noted. There were no withdrawals or deaths due to AEs. Dose reductions for celecoxib were reported for five patients, in three cases due to toxicity. Stable disease was confirmed in 12 patients (40%), with progressive disease in 18 patients (60%).

CONCLUSIONS

After study completion, safety issues relating to the long-term use of COX-2 inhibitors have been raised. However, in this pilot study, the combination of gefitinib and celecoxib was generally well tolerated in patients with advanced GI cancer.

Cell and molecular biology of epidermal growth factor receptor

The epidermal growth factor receptor (EGFR) has been one of the most intensely studied cell surface receptors due to its well-established roles in developmental biology, tissue homeostasis, and cancer biology. The EGFR has been critical for creating paradigms for numerous aspects of cell biology, such as ligand binding, signal transduction, and membrane trafficking. Despite this history of discovery, there is a continual stream of evidence that only the surface has been scratched. New ways of receptor regulation continue to be identified, each of which is a potential molecular target for manipulating EGFR signaling and the resultant changes in cell and tissue biology. This chapter is an update on EGFR-mediated signaling, and describes some recent developments in the regulation of receptor biology.

Enterocyte proliferation and signaling are constitutively altered in celiac disease

Celiac disease (CD) occurs frequently, and is caused by ingestion of prolamins from cereals in subjects with a genetic predisposition. The small intestinal damage depends on an intestinal stress/innate immune response to certain gliadin peptides (e.g., A-gliadin P31-43) in association with an adaptive immune response to other gliadin peptides (e.g., A-gliadin P57-68). Gliadin and peptide P31-43 affect epithelial growth factor receptor (EGFR) signaling and CD enterocyte proliferation. The reason why the stress/innate immune and proliferative responses to certain gliadin peptides are present in CD and not in control intestine is so far unknown. The aim of this work is to investigate if, in CD, a constitutive alteration of enterocyte proliferation and signaling exists that may represent a predisposing condition to the damaging effects of gliadin. Immunofluorescence and immunohistochemistry were used to study signaling in CD fibroblasts and intestinal biopsies. Western blot (WB) analysis, immunoprecipitation, and quantitative PCR were also used. We found in CD enterocytes enhancement of both proliferation and Epidermal Growth Factor Receptor (EGFR)/ligand system. In CD enterocytes and fibroblasts we found increase of the phosphorylated downstream signaling molecule Extracellular Signal Regulated Kinase (ERK); block of the ERK activation normalizes enterocytes proliferation in CD mucosa. In conclusion the same pathway, which gliadin and gliadin peptide P31-43 can interfere with, is constitutively altered in CD cells. This observation potentially explains the specificity of the damaging effects of certain gliadin peptides on CD intestine.

Overexpression of epidermal growth factor receptor as a prognostic factor in colorectal cancer on the basis of the Allred scoring system

BACKGROUND

Overexpression of epidermal growth factor receptor (EGFR) is found in many types of neoplasms. The aim of the study was to evaluate EGFR expression in colorectal cancer (CRC) specimens and to determine whether EGFR expression correlates with clinicopathological data and overall survival.

PATIENTS AND METHODS

Tissue specimens from 181 consecutive CRC patients treated at the Military Institute of Medicine in 2006-2010 were collected and examined for EGFR expression, by immunohistochemistry staining. The staining intensity and percentage of cells with membranous EGFR expression were scored and then grouped according to the parameters of the Allred Scoring system. Cutoff values were subjected to further statistical analysis. Univariate tests and a multivariate Cox proportional hazards model were used in data analysis.

RESULTS

EGFR was overexpressed in 96 of 181 CRC specimens (53%). EGFR expression was not correlated with other clinicopathological variables. On univariate analysis, overexpression of EGFR, determined by PS (percentage score) (>3) and total score (sum of PS and intensity score) (>4), was associated with poor overall survival. On multivariate analysis, EGFR overexpression (PS > 3) was an independent adverse prognostic factor (hazard ratio [HR] 1.62; 95% confidence interval [CI]: 1.03-2.53). Elevated carcinoembryonic antigen (CEA) serum concentration before treatment, performance status (Word Health Organization [WHO]-2), and tumor localized in colon and liver metastases were also independent unfavorable prognostic factors.

CONCLUSION

EGFR overexpression (PS > 3) in a CRC patient population was an independent adverse prognostic factor. Implementation of the Allred Scoring system criteria into clinical practice might facilitate treatment decisions in CRC patients.

Telmisartan inhibits cell proliferation by blocking nuclear translocation of ProHB-EGF C-terminal fragment in colon cancer cells

Background & Aims

Current treatment target toward advanced colorectal cancers is mainly focused on the epidermal growth factor receptor (EGFR) signaling, but its additive effects with chemotherapy are still limited. A disintegrin and metalloproteinase (ADAM) cleaves the proheparin-binding epidermal growth factor like growth factor (proHB-EGF). And soluble HB-EGF activates EGFR. In parallel, the carboxy-terminal fragment of proHB-EGF (HB-EGF-CTF) translocates into the inner nuclear membrane, and subsequently exerts on the regulation of cell proliferation by binding nuclear promyelocytic leukemia zinc finger (PLZF) protein, a transcriptional repressor, thereby causing its nuclear export. We hypothesized that the inhibition of HB-EGF-CTF nuclear translocation may be a new strategy in preventing cell proliferation.

Methods

12-O-tetradecanoylphorbor-13-acetate (TPA) was treated to activate ADAM. Nine-thousand chemical compounds were screened for their efficacies in blocking the binding of HB-EGF-CTF to promyelocytic leukemia zinc finger (PLZF) with Alphascreen system. The obtained candidates were then used to block the binding of HB-EGF-CTF to PLZF in colon cancer cells, HT29 and HCT116. Cell proliferation was investigated with a growth curve assay. The intracellular localization, and association between HB-EGF-CTF and PLZF, was assessed with immunofluorescent staining, and immunoprecipitation and Western blotting, respectively. The effects of obtained candidates on EGFR phosphorylation and on nuclear translocation of HB-EGF-CTF and export of PLZF during the angiotensin II type1 receptor (AT1R) knockdown were also investigated.

Results

Telmisartan and candesartan were found to be potential candidates. Telmisartan inhibited TPA-induced cell proliferation stronger than candesartan. Telmisartan, but not candesartan blocked the nuclear translocation of HB-EGF-CTF, and binding of HB-EGF-CTF to PLZF, during TPA stimulation. Both telmisartan and candesartan did not inhibit TPA-induced EGFR phosphorylation, and telmisartan, but not candesartan, inhibited TPA-induced nuclear translocation of HB-EGF-CTF after knockdown of AT1R.

Conclusions

The inhibition of HB-EGF-CTF nuclear translocation with telmisartan may be a novel strategy in preventing cell proliferation.

Significance of regenerating islet-derived type IV gene expression in gastroenterological cancers

The regenerating islet-derived members (Reg), a group of small secretory proteins, which are involved in cell proliferation or differentiation in digestive organs, are upregulated in several gastrointestinal cancers, functioning as trophic or antiapoptotic factors. Regenerating islet-derived type IV (RegIV), a member of the Reg gene family, has been reported to be overexpressed in gastroenterological cancers. RegIV overexpression in tumor cells has been associated with carcinogenesis, cell growth, survival and resistance to apoptosis. Cancer tissue expressing RegIV is generally associated with more malignant characteristics than that without such expression, and RegIV is considered a novel prognostic factor as well as diagnostic marker in some gastroenterological cancers. We previously investigated the expression levels of RegIV mRNA of 202 surgical colorectal cancer specimens with quantitative real-time reverse-transcriptase polymerase chain reaction and reported that a higher level of RegIV gene expression was a significant independent predictor of colorectal cancer. The biologic functions of RegIV protein in cancer tissue, associated with carcinogenesis, anti-apoptosis and invasiveness, are being elucidated by molecular investigations using transfection techniques or neutralizing antibodies of RegIV, and the feasibility of antibody therapy targeting RegIV is being assessed. These studies may lead to novel therapeutic strategies for gastroenterological cancers expressing RegIV. This review article summarizes the current information related to biological functions as well as clinical importance of RegIV gene to clarify the significance of RegIV expression in gastroenterological cancers.

Biologics against cancer-specific receptors - challenges to personalised medicine from early trial results

Understanding molecular mechanisms of tumourigenesis underlies new therapeutic strategies that specifically target tumours. This has led to the evolution of personalised therapy that was first used in breast cancer when hormone receptor status was determined. More recently in colorectal cancer treatment the Epidermal Growth Factor receptor and its tumourigenic role has led to its targeting by using Cetuximab and Panitumumab. Addition of these drugs to existing drug regimes (FOLFOX and FOLFIRI) showed improved respectability rates in patients with liver metastasis. Most recently the Endothelin receptor has been implicated in multiple tumourigenic processes. Interest has grown in using Endothelin A receptor antagonists as adjuvant or combination therapy as suggested by the FOLFERA and FOLFIRI trials currently on-going.

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.

Prognostic value of tumor growth factor levels during chemotherapy in patients with metastatic colorectal cancer

Tumor growth and angiogenic factors are usually overexpressed in colorectal carcinomas. We aimed to assess the prognostic role of VEGF, bFGF, PDGF-AA, EGF, HGF, and E-selectin in patients with metastatic colorectal cancer treated with capecitabine and oxaliplatin (XELOX) chemotherapy protocol. Thirty-eight colorectal cancer patients who had evidence of distant metastasis were enrolled in the study. Angiogenic factors were measured before and after third cycle of chemotherapy. Patients were randomized into three groups, partial response (PR), stable disease (SD), and progressive disease (PD) groups, according to their clinical and radiologic evaluation after three cycles of XELOX chemotherapy. Eighteen patients (47.3 %) achieved partial response, 10 (26.3 %) stable disease, and 10 (26.3 %) progressive disease. VEGF (63.20 Pg/ml vs. 19,79 Pg/ml; p < 0.001), EGF (7.29 ± 3.08 Pg/ml vs. 4.79 ± 2.05 Pg/ml; p < 0.011), HGF (618.16 ± 340.39 Pg/ml vs. 452.02 ± 217.18 Pg/ml; p < 0.049), and PDGF-AA (691.68 ± 187.10 Pg/ml vs. 404.89 ± 168.47 Pg/ml; p < 0.001) were significantly decreased in PR group. PDGF-AA levels were also decreased in SD group (706.66 ± 206.66 Pg/ml vs. 389.79 ± 143.16 Pg/ml; p < 0,001). HGF levels were significantly increased in PD disease group (449.99 Pg/ml vs. 682.22 Pg/ml; p < 0.046). The baseline E-selectin levels were inversely proportional with overall survival that could be an important prognostic factor at the time of diagnosis. This study demonstrated that tumor growth factors can be helpful to determine colorectal cancer prognosis and overall survival in patients with metastatic disease. VEGF, HGF, EGF, and PDGF-AA levels were decreased in PR group. However, meaningful increment was seen HGF levels in PD group. Angiogenic factors and E-selectin provided unique prognostic information in advanced colorectal carcinoma patients.

Role of epidermal growth factor receptor expression on patient survival in pancreatic cancer: a meta-analysis

BACKGROUND/AIMS

Epidermal growth factor receptor (EGFR) has been considered as an attractive and potential therapeutic target of pancreatic cancer. However, the clinical importance of EGFR expression remains controversial.

METHODS

We performed a meta-analysis of previous studies to quantitatively review the effects of EGFR expression on survival in patients with pancreatic cancer.

RESULTS

Eight studies (570 patients) were included to perform a meta-analysis of the survival results. Overall, positivity for EGFR expression was 45.1% in pancreatic carcinoma. The combined hazard ratio was 1.225 (95% CI 1.014-1.481; p = 0.035), indicating that EGFR expression has a significant impact on survival. Heterogeneity was absent between studies and publication bias, which suggests that the summary statistics obtained may approximate the actual average. Three trials reported a survival disadvantage for patients with EGFR expression while five trials reported no statistically significant difference.

CONCLUSION

EGFR expression is a poor prognostic factor for survival in patients with pancreatic cancer. and IAP.

The neoadjuvant therapy of colorectal hepatic metastases and the role of biologic sensitizing and resistance factors

Liver metastasis represents a common systemic complication of colorectal cancers (CRCs). Partial liver resection has been demonstrated to result in long-term survival in certain well-selected patients with otherwise well-controlled systemic disease. Neoadjuvant therapy has been demonstrated to result in improved resectability and potentially longer survival in patients with liver metastases from CRC. The addition of biologic agents to chemotherapy has been shown to improve response rates and overall survival in patients with metastatic CRC. Here, we are discussing the role of biologic agents in the treatment of patients with liver metastases from CRC. We also discuss the role of biomarkers for response and resistance to such novel therapies.

Lack of correlation between epidermal growth factor receptor status and response to Panitumumab monotherapy in metastatic colorectal cancer

PURPOSE

Panitumumab, a fully human anti-epidermal growth factor receptor (EGFR) monoclonal antibody, is approved as monotherapy for the treatment of metastatic colorectal cancer. We evaluated the association of tumor EGFR expression levels with outcomes in patients with chemorefractory metastatic colorectal cancer.

EXPERIMENTAL DESIGN

Two phase II, multicenter, single-arm, open-label studies enrolled chemorefractory patients with tumors expressing low/negative (1-9%/<1%; Low/Negative EGFR study) or high (> or =10%; High EGFR study) levels of EGFR. Patients received panitumumab 6 mg/kg every two weeks until disease progression or intolerance. End points included objective response rate (per response evaluation criteria in solid tumors), progression-free survival (PFS), overall survival (OS), and safety. Exploratory analyses by tumor KRAS status were carried out.

RESULTS

A total of 203 patients (Low/Negative EGFR) and 185 patients (High EGFR) enrolled in the studies. The overall response rate was 5.7% [95% confidence interval (95% CI), 2.6-10.5] in patients with low/negative EGFR and 4.2% (95% CI, 1.6-9.0) in patients with high EGFR; the response rate at week 16 was 4% in both studies (all partial responses). Median PFS times were 8.1 weeks (95% CI, 7.1-12.6), 8.1 weeks (95% CI, 7.4-11.1), and 7.3 weeks (95% CI, 7.1-7.6) in patients with negative, low, and high levels of EGFR expression, respectively. PFS and OS were longer in patients with wild-type KRAS than those with mutant KRAS. As expected, most adverse events were skin related.

CONCLUSIONS

These studies confirm previous reports that tumor EGFR expression levels are not associated with efficacy with an anti-EGFR antibody and that anti-EGFR antibody therapy should be limited to those patients whose tumors express wild-type KRAS.

K-ras mutation status correlates with the expression of VEGFR1, VEGFR2, and PDGFRalpha in colorectal cancer

AIM

We initiated this study in order to analyze whether the expression level of targeted receptor tyrosine kinases (RTK) is associated with the K-ras mutation status.

METHODS

The expression pattern of VEGFR1, VEGFR2, VEGFR3, PDGFRalpha, PDGFRbeta, and EGFR1 was analyzed in 93 samples of human colorectal carcinoma samples and correlated with the K-ras mutation status as identified by PCR-RFLP.

RESULTS

VEGFR1, VEGFR2, VEGFR3, PDGFRalpha, PDGFRbeta, and EGFR1 were expressed at relevant levels in 95%, 46%, 46%, 85%, 62%, and 82%, respectively. K-ras mutations were present in 53% (codon 12, 47%; codon 13, 6%). Expression of VEGFR1 (P = 0.0263), VEGFR2 (P = 0.0466), and PDGFRalpha (P = 0.0063) was significantly linked to K-ras codon 12 or 13 mutation. In addition, co-expression of VEGFR2 and PDGFRalpha was significantly associated with K-ras mutation (P = 0.0145).

CONCLUSION

Our data reveal that specific RTKs are over-expressed in K-ras mutated cancers. It needs to be addressed in prospective studies whether these patients will benefit from tyrosine kinase inhibitors more than K-ras wild-type.

Immunohistochemical detection of receptor tyrosine kinases c-kit, EGF-R, and PDGF-R in colorectal adenocarcinomas

PURPOSE

The selective inhibition of tyrosine kinases is a promising strategy in the treatment of several human malignancies. This study aimed to clarify expression patterns of therapeutically addressable receptor tyrosine kinases in colorectal cancer.

MATERIALS AND METHODS

In this study, we used tissue arrays to analyze 263 specimen of colorectal carcinoma for the expression of the tyrosine kinases c-kit (CD117), epidermal growth factor receptor (EGF-R), and platelet-derived growth factor receptor (PDGF-R). Staining patterns were then correlated with tumor stage and survival.

RESULTS

Five tumors (1.9%) showed a strong expression of c-kit (CD117), while in 40 samples (15.2%), a weak/intermediate expression was observed. Positive staining did not correlate with histopathological parameters although a trend toward a better survival of c-kit-positive patients was observed. No positivity for PDGF-R was observed in 263 samples of colorectal carcinomas. Positive EGF-R expression was identified in 39 cases (15.2%), whereas 218 samples (84.8%) stained negative.

CONCLUSIONS

Our study confirms that expression of the tyrosine kinases c-kit and PDGF-R are rare in colorectal carcinomas and do not correlate with tumor stage.

Targeting apoptosis as an approach for gastrointestinal cancer therapy

Cancers in the gastrointestinal system account for a large proportion of malignancies and cancer-related deaths with gastric cancer and colorectal cancer being the most common ones. For those patients in whom surgical resection is not possible, other therapeutic approaches are necessary. Disordered apoptosis has been linked to cancer development and treatment resistance. Apoptosis occurs via extrinsic or intrinsic signaling each triggered and regulated by many different molecular pathways. In recent years, the selective induction of apoptosis in tumor cells has been increasingly recognized as a promising approach for cancer therapy. A detailed understanding of the molecular pathways involved in the regulation of apoptosis is essential for developing novel effective therapeutic approaches. Apoptosis can be induced by many different approaches including activating cell surface death receptors (for example, Fas, TRAIL and TNF receptors), inhibiting cell survival signaling (such as EGFR, MAPK and PI3K), altering apoptosis threshold by modulating pro-apoptotic and anti-apoptotic members of the Bcl-2 family, down-regulating anti-apoptosis proteins (such as XIAP, survivin and c-IAP2), and using other pro-apoptotic agents. In this review, the authors reviewed the currently reported apoptosis-targeting approaches in gastrointestinal cancers.

Akt-dependent NF-kappaB activation is required for bile acids to rescue colon cancer cells from stress-induced apoptosis

Conjugated secondary bile acids promote human colon cancer cell proliferation by activating EGF receptors (EGFR). We hypothesized that bile acid-induced EGFR activation also mediates cell survival by downstream Akt-regulated activation of NF-kappaB. Deoxycholyltaurine (DCT) treatment attenuated TNF-alpha-induced colon cancer cell apoptosis, and stimulated rapid and sustained NF-kappaB nuclear translocation and transcriptional activity (detected by NF-kappaB binding to an oligonucleotide consensus sequence and by activation of luciferase reporter gene constructs). Both DCT-induced NF-kappaB nuclear translocation and attenuation of TNF-alpha-stimulated apoptosis were dependent on EGFR activation. Inhibitors of nuclear translocation, proteosome activity, and IkappaBalpha kinase attenuated NF-kappaB transcriptional activity. Cell transfection with adenoviral vectors encoding a non-degradable IkappaBalpha 'super-repressor' blocked the actions of DCT on both NF-kappaB activation and TNF-alpha-induced apoptosis. Likewise, transfection with mutant akt and treatment with a chemical inhibitor of Akt attenuated effects of DCT on NF-kappaB transcriptional activity and TNF-alpha-induced apoptosis. Chemical inhibitors of Akt and NF-kappaB activation also attenuated DCT-induced rescue of H508 cells from ultraviolet radiation-induced apoptosis. Collectively, these observations indicate that, downstream of EGFR, bile acid-induced colon cancer cell survival is mediated by Akt-dependent NF-kappaB activation. These findings provide a mechanism whereby bile acids increase resistance of colon cancer to chemotherapy and radiation.

Id-1: regulator of EGFR and VEGF and potential target for colorectal cancer therapy

Background

The helix-loop-helix transcription factor Id-1 (an inhibitor of differentiation and DNA binding) plays a role in development and progression of many tumours. Id-1 is known to exert its effects on the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor (VEGF). The aim of this study was to reveal whether there was a relationship between Id-1 and EGFR and VEGF in colorectal carcinoma.

Methods

Tumour and non-tumour tissue specimens from 46 cases of colorectal carcinoma were exposed to immunohistochemical staining for Id-1, EGFR and VEGF. The relationship between the degree of staining and tumour grade, tumour stage and all tumour markers was investigated.

Results

Tumour cells showed positive staining for Id-1 in 43 cases (93.5%), for EGFR in 41 cases (89%) and for VEGF in 42 cases (91%). There was a significant relation between the tumour grade and the degree of staining for Id-1, EGFR and VEGF. The relation between the tumour stage and the degree of staining for Id-1, EGFR and VEGF was also significant. There was a significant relation between Id-1 expression and EGFR and VEGF expressions. Non-tumoural tissue specimens were not stained with Id-1 and EGFR antibodies in any of the cases, but stained with VEGF antibody in 3 cases.

Conclusion

This study revealed that Id-1, EGFR and VEGF took part in development and progression of colorectal carcinomas and that Id-1 was associated with regulations of EGFR and VEGF. The results of this study support the idea that not only EGFR and VEGF but also Id-1 could be new targets in cancer treatment.

Systemic and targeted therapy for advanced colon cancer

Colorectal cancer (CRC) is the third most common malignancy and the second most common cause of cancer-related death in the USA. Prognosis is best when the disease is detected early; however, nearly two-thirds of newly diagnosed cases of CRC have lymph node involvement or metastatic disease. For years, 5-fluorouracil (FU)-based regimens represented the only viable treatment option for patients with metastatic CRC. However, in recent years several newer agents have been added to the treatment arsenal for this disease. These agents include oxaliplatin, irinotecan and newer monoclonal antibodies targeting the epidermal growth factor receptor (cetuximab and panitumumab) and VEGF (bevacizumab). This review aims to discuss current systemic and targeted therapies for metastatic colon cancer with a focus on mechanism of action, indications, toxicity and efficacy.

Epidermal growth factor receptor (EGFR) expression is associated with a worse prognosis in gastric cancer patients undergoing curative surgery

BACKGROUND

In gastric cancer, the recurrence rate is high even after curative surgery. A relevant issue is the identification of independent prognostic factors to select high-risk patients; such features can be used as predictive factors for tailored therapies. In this study we have investigated the role of epidermal growth factor receptor (EGFR) expression as a prognostic marker for predicting cancer behavior and clinical outcome in gastric cancer patients undergoing potentially curative surgery.

METHODS

Epidermal growth factor receptor determination using a commercially available immunohistochemistry (IHC) kit was performed in tissues from 82 gastric cancer patients receiving primary surgical treatment and in 25 normal gastric mucosa specimens from noncancer patients. The EGFR positivity was correlated with disease recurrence and survival in univariate and multivariate analyses.

RESULTS

Forty-four percent (36 cases) of gastric cancers were EGFR positive. In 66 curatively treated patients, EGFR expression correlated with disease recurrence and poorer survival in both univariate and multivariate analyses. In a multivariate model for predicting recurrence and survival, advanced tumor extension (T(3) or T(4)), nodal metastases, and EGFR expression were the only independent covariates. In particular, EGFR expression was shown to be a significant predictor of poor prognosis among gastric cancer patients having the same stage according to the current TNM staging system.

CONCLUSIONS

These findings suggest that EGFR expression may be useful in identifying high-risk gastric cancer patients undergoing potentially curative surgery. Multimodal treatments should be considered in the adjuvant treatment of these patients.

The binding of human betacellulin to heparin, heparan sulfate and related polysaccharides

Recombinant human betacellulin binds strongly to heparin, requiring of the order of 0.8 M NaCl for its elution from a heparin affinity matrix. This is in complete contrast to the prototypic member of its cytokine superfamily, epidermal growth factor, which fails to bind to the column at physiological pH and strength. We used a well-established heparin binding ELISA to demonstrate that fucoidan and a highly sulfated variant of heparan sulfate compete strongly for heparin binding. Low sulfated heparan sulfates and also chondroitin sulfates are weaker competitors. Moreover, although competitive activity is reduced by selective desulfation, residual binding to extensively desulfated heparin remains. Even carboxyl reduction followed by extensive desulfation does not completely remove activity. We further demonstrate that both hyaluronic acid and the E. coli capsular polysaccharide K5, both of which are unsulfated polysaccharides with unbranched chains of alternating N-acetylglucosamine linked beta(1-4) to glucuronic acid, are also capable of a limited degree of competition with heparin. Heparin protects betacellulin from proteolysis by LysC, but K5 polysaccharide does not. Betacellulin possesses a prominent cluster of basic residues, which is likely to constitute a binding site for sulfated polysaccharides, but the binding of nonsulfated polysaccharides may take place at a different site.

Gastric cancer: an update

Gastric cancer is an aggressive malignancy, which, if metastatic or unresectable, is incurable. However, with metastatic or unresectable disease, patients receive a palliative benefit from chemotherapy. Although the understanding of the biology of this disease is increasing, the development of biologically targeted therapies for gastric cancer has been limited. Cytotoxic therapy remains the standard approach, and although there is agreement on the active agents and active combination chemotherapy regimens, consensus on the standard or reference regimen is lacking. This article reviews the pathophysiology of this disease, placing it in the context of its epidemiology, and the current advances in the treatment of this disease.

Intérêt de la chronothérapie dans le traitement pluridisciplinaire des cancers de l'œsophage et de l'estomac

The authors evaluated the impact of a chronotherapy with 5-FU, folinic acid and carboplatine (chronomodulated infusions by ambulatory pumps; 5/21 days) for the management of oesophagus (52 cases) and gastric (56 cases) cancer patients. The overall tolerance of treatment was gauged excellent (grade 3-4; % patients: mucitis: 11-23%; leucopenia 6-19%; thrombopenia 18-50%; almost no digestive disturbances nor alopecia). Also tumor outcome was considered interesting with major responses rate in 61% (gastric) to 79% (oesophagus) of patients. The median survival of oesophageal cancer was limited to 9.2 months; the one of disseminated gastric cancer was 12.7 months but 72% of curatively resected patients were alive at 5+ years.

The complexity of targeting EGFR signalling in cancer: from expression to turnover

The epidermal growth factor receptor (ErbB1 or EGFR) has been found to be altered in a variety of human cancers. A number of agents targeting these receptors, including specific antibodies directed against the ligand-binding domain of the receptor and small molecules that inhibit kinase activity are either in clinical trials or are already approved for clinical treatment. However, identifying patients that are likely to respond to such treatments has been challenging. As a consequence, it still remains important to identify additional alterations of the tumor cell that contribute to the response to EGFR-targeted agents. While EGFR-mediated signalling pathways have been well established, there is still a rather limited understanding of how intracellular protein-protein interactions, ubiquitination, endocytosis and subsequent degradation of EGFR contribute to the determination of sensitivity to EGFR targeting agents and are emerging areas of investigation. This review primarily focuses on the basic signal transduction pathways mediated through activated membrane bound and/or endosomal EGFR and emphasizes the need to co-target additional proteins that function either upstream or downstream of EGFR to improve cancer therapy.

NFAT3 is Required for EGF-Induced COX-2 Transcription, but Neither iNOS Transcription Nor Cell Transformation in Cl 41 Cells

Epidermal growth factor (EGF) has been reported to act as a tumor promoter in several tissues, such as skin, in association with the induction of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). However, molecular mechanisms involved in these regulations are not well defined. This study addressed a potential role of nuclear factor of activated T cells 3 (NFAT3) in EGF-induced COX-2 and iNOS transcription and cell transformation in mouse epidermal Cl 41 cells. We found that EGF markedly induced anchorage-independent growth (cell transformation) of Cl 41 cells, as well as COX-2 (> 6-fold) and iNOS (> 5-fold) promoter-dependent transcription. The EGF-induced COX-2 transcription was blocked by knockdown of NFAT3 with NFAT3 siRNA, whereas the transcription of iNOS and cell transformation induced by EGF were not affected. Although our recent studies supported that NFAT3 plays an essential role in chemical carcinogen benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE)-induced cell transformation, the data presented here demonstrated that NFAT3 is required for EGF-induced COX-2 transcription, but neither iNOS transcription nor cell transformation, indicating that the role of NFAT3 in regulating cell transformation is carcinogen-specific.

Reg IV activates the epidermal growth factor receptor/Akt/AP-1 signaling pathway in colon adenocarcinomas

BACKGROUND & AIMS

Reg IV, a secreted protein and member of the Reg multigene family, is up-regulated in malignancies of the human gastrointestinal tract, including colorectal carcinoma (CRC). However, in vitro signal transduction pathway(s) utilized by Reg IV are not yet known.

METHODS

To determine the signaling pathway(s) responsive to Reg IV, we examined the effects of purified recombinant human Reg IV (rhR4) on HCT116 and HT29 colon adenocarcinoma cells.

RESULTS

Addition of rhR4 to cultures led to a dose-dependent increase in cell number similar to that observed after treatment with epidermal growth factor (EGF). In addition, rhR4 treatment resulted in rapid phosphorylation of EGF receptor at Tyr992 and Tyr1068 and Akt at Thr308 and Ser473. Using luciferase reporter gene assays, we demonstrated that Reg IV signaling through EGF receptor and Akt results in increased activator protein-1 (AP-1) transcription factor activity. Real-time reverse-transcription polymerase chain reaction and Western blot analyses revealed quantitative increases in c-Jun, JunB, JunD, and FosB expression associated with increased AP-1 activity. Electrophoretic mobility shift assay further revealed significant increases in AP-1 binding activity in rhR4-treated cells, with increased supershift in the presence of antibodies to JunB, JunD, and FosB. Furthermore, rhR4 treatments led to the increased expression of Bcl-2, Bcl-XL, survivin, and matrilysin, genes associated with a poor prognosis in advanced CRC.

CONCLUSIONS

Reg IV is a potent activator of the EGF receptor/Akt/AP-1 signaling pathway in CRC. Disruption of Reg signaling may have utility as a therapeutic intervention for human gastrointestinal adenocarcinomas.

Lysophosphatidic acid-induced effects in human colon carcinoma DLD1 cells are partially dependent on transactivation of epidermal growth factor receptor

BACKGROUND

Lysophosphatidic acid (LPA) is a lipid mediator of diverse effects on various cells. LPA is well known to induce phosphorylation of the epidermal growth factor receptor (EGFR), which is termed transactivation, in some cell types. In this study, we investigated the contribution of EGFR transactivation in LPA-induced responses in colon cancer DLD1 cells.

MATERIALS AND METHODS

Immunoprecipitation was performed to investigate whether LPA induced EGFR phosphorylation. Then, we investigated LPA-induced migration and IL-8 secretion in DLD1 cells. Migration was measured in a modified Boyden chamber and IL-8 secretion was measured by ELISA. In these experiments we used an EGFR inhibitor, AG1478 or matrix metalloproteinase (MMP) inhibitor, GM6001.

RESULTS

Immunoprecipitation analysis revealed that LPA induced a significant level of tyrosine phosphorylation of EGFR in DLD1 cells. The LPA-induced phosphorylation of EGFR was almost completely abrogated by either AG1478 or GM6001. LPA induced significant migration and IL-8 secretion in DLD1, both of which were significantly inhibited by AG1478 or GM6001. However, the inhibitory effects were only partial (migration; 29% +/- 2%, 32 +/- 13% inhibition, IL-8 secretion; 33% +/- 1%, 26% +/- 5% inhibition, respectively).

CONCLUSION

These results clearly indicate that LPA acts upstream of EGFR and compensates the EGF signal and antagonism of the EGF signal cannot completely block tumor progression in colon cancer cells. Blockade of the LPA signal may have clinical significance in the treatment of colon cancer.

Imaging Epidermal Growth Factor Receptor Phosphorylation in Human Colorectal Cancer Cells and Human Tissues

In tumor cells, high phosphorylation levels of receptor tyrosine kinases may occur in the absence of exogenous ligands due to autocrine signaling or enhanced tyrosine kinase activity. Here we show that the phosphorylation state of the endogenous epidermal growth factor receptor (EGFR) can be quantitatively imaged in tumor cells and tissues by detecting fluorescence resonance energy transfer between fluorophores conjugated to antibodies against the receptor and phosphotyrosine, respectively. Five different human colorectal cell lines were analyzed for activity and expression of EGFR. All cell lines exhibited basal EGFR phosphorylation under serum starvation conditions. Phosphorylation levels increased after stimulation with EGF or pervanadate, dependent on the level of basal EGFR phosphorylation in the respective cell lines. This basal activity correlated inversely with receptor expression. Using the acceptor photobleaching fluorescence resonance energy transfer imaging approach, a significantly higher phosphorylation state of EGFR was also found in resected human colorectal tumor samples as compared with adjacent healthy tissue. Imaging of EGFR phosphorylation may thus serve as a valuable tool to investigate the role of receptor tyrosine kinase activity in malignant cell growth.

Epidermal growth factor receptor-targeted treatment for advanced colorectal carcinoma

Substantial effort has focused on the development of novel targeted agents for treating patients with late-stage colorectal carcinoma. These agents are designed specifically to inhibit biochemical processes associated with pathogenesis. Numerous molecules targeting the epidermal growth factor receptor have been investigated as therapeutic agents and appear to herald a shift in the treatment paradigm for colorectal carcinoma.

Synergistic interaction between gefitinib (Iressa, ZD1839) and paclitaxel against human gastric carcinoma cells

We have evaluated the antitumor effects of gefitinib (Iressa, ZD1839) in SNU-1 human gastric cancer cells (hMLH1-deficient and epidermal growth factor receptor-overexpressed) when given alone or as a doublet with oxaliplatin (LOHP), 5-fluorouracil (5-FU) or paclitaxel (PTX). The four drugs showed IC50s ranging from 1.81 nM to 13.2 microM. LOHP and PTX induced G2/M arrest, 5-FU increased S phase, and gefitinib increased G1 in a concentration-dependent manner. The analysis using the previously developed cytostatic TPi model showed that 64 and 80% of the overall growth inhibition was attributed to cell cycle arrest in cells exposed to 7.55 microM of LOHP or 10 nM of PTX for 72 h, respectively. PTX + gefitinib showed greatest synergism as determined by combination index analysis and apoptosis induced by PTX was potentiated by the co-administration of gefitinib. LOHP + gefitinib showed a similar, although to a lesser degree, synergistic effect. This study demonstrates the antitumor activity and the significant cell cycle arrest induced by gefitinib in SNU-1 human gastric carcinoma cells, and its synergistic interaction with LOHP and PTX.

The treatment of advanced gastric cancer: new findings on the activity of the taxanes

Globally, gastric cancer is one of the most common types of cancer and one of the most frequent causes of cancer-related death. Despite many advances in the diagnosis and treatment of this disease, the prognosis for gastric cancer remains poor, especially in more advanced stages. In metastatic disease, benefits in survival and quality of life have been demonstrated in patients with unresectable or metastatic gastric cancer receiving chemotherapy plus best supportive care versus best supportive care alone. The taxanes, which are among the most promising cytotoxic agents in clinical use, have shown encouraging activity in early-phase studies as single agents and in combination regimens in the treatment of advanced gastric cancer. Recently, interim results of a randomized phase III trial comparing the triplet of docetaxel, cisplatin, and 5-fluorouracil with a standard reference regimen of cisplatin and 5-fluorouracil were reported. Patients treated with the docetaxel-containing regimen had a statistically superior response rate and time to disease progression as well as a clinically significant prolongation of survival. This study underscores the importance of developing new therapeutic options for patients with advanced gastric cancer.