Oncogenes and onco-suppressor gene in adenocarcinoma of the oesophagus

Expression profile and cellular localizations of mucin proteins, CK7, and cytoplasmic p27 in Barrett's esophagus and esophageal adenocarcinoma

PURPOSE

Barrett's esophagus is one of the main risk factors for increased incidence of esophageal adenocarcinoma. In this study, we studied protein expression levels and cellular localizations of MUC-1, MUC-2, MUC-5AC, CK7, and cytoplasmic p27 to assess the relationship between the expression of each of these proteins and the disease progression on endoscopic biopsies.

MATERIALS AND METHODS

Immunohistochemical analyses were performed using antibodies produced against MUC-1, MUC-2, MUC-5AC, CK7, and p27. Endoscopic specimens of esophageal mucosa were obtained from 72 patients who underwent esophagectomy for Barrett's esophagus, metaplasia, dysplasia, or esophageal adenocarcinoma developed from Barrett's esophagus.

RESULTS

Multilayer squamous epithelium showed only MUC-1 positivity in the EAC group while MUC-2 and MUC-5AC staining could not be detected in this group. Strong and diffused membranous or cytoplasmic staining of CK7 was observed at squamous, ductal, surface columnar and/or glandular epithelium. c-p27 staining was diffused and moderate in the cellular membranes observed in all groups except for esophageal epithelial metaplasia without intestinal metaplasia. Additionally, weakly focal cytoplasmic staining in squamous epithelium of p27 in EAC was detected.

CONCLUSIONS

Barrett's esophagus, which has a heterogeneous epithelium, might yield different diagnosis based on endoscopic evaluation and immunohistological investigation. Thus, the use of MUC1, p27, and CK7 might strengthen the truthful diagnosis. MUC-1, CK7, and c-p27 immunostaining can be used as the predictive markers for esophageal cancer progression from Barrett's esophagus.

MiR-193a-5p/ERBB2 act as concurrent chemoradiation therapy response indicator of esophageal squamous cell carcinoma

Concurrent chemoradiation therapy (CCRT) is the predominant treatment in esophageal cancer, however resistance to therapy and tumor recurrence are exceedingly common. Elevated ERBB2/Her2 may be at least partially responsible for both the high rates of recurrence and resistance to CCRT. This receptor tyrosine kinase is upregulated in 10–20% of esophageal squamous cell carcinoma (ESCC) tissues, and amplification of ERBB2 has been correlated with poor prognosis in esophageal cancer. Tissues from 131 ESCC patients, along with cell and animal models of the disease were used to probe the underlying mechanisms by which ERBB2 upregulation occurs and causes negative outcomes in ESCC. We found that overexpression of ERBB2 inhibited radiosensitivity in vitro. Furthermore, miR-193a-5p reduced ERBB2 expression by directly targeting the 3′UTR. Increased miR-193a-5p enhanced radiosensitivity and inhibited tumorigenesis in vitro and in vivo. Additionally, low miR-193a-5p expression correlated with poor prognosis in ESCC patients, and ESCC patients with good CCRT response exhibited higher miR-193a-5p expression. Our data suggest that patients with high miR-193a-5p will likely benefit from CCRT treatment alone, however a combination of CCRT with Herceptin may be beneficial for patients with low miR-193a-5p expression.

Oncogene Expression and Amplification in Barrett Adenocarcinoma

Oncogene activation by amplification and/or overexpression has been implicated in the development and progression of a number of malignancies. To better define the role of oncogene activation in adenocarcinomas arising in the setting of Barrett esophagus, we examined 44 resected Barrett adenocarcinomas for c-erb B-2, epidermal growth factor receptor (EGFR), c-myc, and cyclin DI gene amplification as well as c-erb B-2 and EGFR expression. DNA was extracted from formalin-fixed paraffin-embedded tissue and analyzed by differential polymerase chain reaction, a technique that permits semiquantitative analysis of gene dosage on archival material. Formalinfixed paraffin-embedded sections were stained with monoclonal antibodies directed against either the internal domain of c-erb B-2 or the extracellular domain of EGFR with a labeled streptavidin biotin technique. C-erb B-2 amplification was identified in three (7%) cases. A plasma membrane pattern of c-erb B-2 immunoreactivity in >50% of tumor cells correlated highly with c-erb B-2 amplification ( P=.00008). EGFR amplification was noted in 18% of cases and correlated highly with the intensity of EGFR immunoreactivity ( P=.0004). C-myc amplification was present in 18% of cases. No tumors showed cyclin DI amplification. Follow-up was available regarding 29 patients and showed decreased mean survival ( P=.029) in patients with strong EGFR immunoreactivity (5.8 months) versus those with weak or absent EGFR labeling (11.8 months), and a trend toward decreased one-year survival (P=.069) for patients with (17%) versus those without (52%) c-myc amplification. Our results indicate one or more selected oncogenes are amplified/overexpressed in some Barrett adenocarcinomas and that EGFR and c-erb B-2 overexpression correlates with amplification. Additionally, strong EGFR expression in tumor cells indicates a poorer prognosis.

Chemoprevention in Barrett's Esophagus: Current Status

Chemoprevention in Barrett's esophagus is currently applied only in research settings. Identifying pathways that can be targeted by safe, pharmaceutical or natural compounds is key to expanding the scope of chemoprevention. Defining meaningful surrogate markers of cancer progression is critical to test the efficacy of chemopreventive approaches. Combinatorial chemoprevention that targets multiple components of the same pathway or parallel pathways could reduce the risk and improve the efficacy of chemoprevention. Here we discuss the role of chemoprevention as an independent or an adjuvant management option in BE-associated esophageal adenocarcinoma.

Translational research on esophageal adenocarcinoma: from cell line to clinic

Human esophageal adenocarcinoma (EAC) cell lines have made a substantial contribution to elucidating mechanisms of carcinogenesis and drug discovery. Model research on EAC relies almost entirely on a relatively small set of established tumor cell lines because appropriate animal models are lacking. Nowadays, more than 20% of all fundamental translational research studies regarding EAC are partially or entirely based on these cell lines. The ready availability of these cell lines to investigators worldwide have resulted in more than 250 publications, including many examples of important biomedical discoveries. The high genomic similarities (but certainly not completely identical) between the EAC cell lines and their original tumors provide rational for their use. Recently, in a collaborative effort all available EAC cell lines have been verified resulting in the establishment of a reliable panel of 10 EAC cell lines. It could be expected that the value of these cell lines increases as unlimited source of tumor material because new biomedical techniques require more tumor cells and the supply of viable tumor cells is diminishing because of neoadjuvant chemo(radio)therapy of patients with EAC. Here, we review the history of the EAC cell lines and their utility in translational research and biomedical discovery.

Human epidermal growth factor receptor 2 overexpression and amplification in endoscopic biopsies and resection specimens in esophageal and junctional adenocarcinoma

Human epidermal growth factor receptor 2 (HER2) is overexpressed in a subset of esophageal adenocarcinomas. Frequently, biopsy material is used for evaluation of HER2 status. The aim of the study was to determine if HER2 expression in preoperative endoscopic biopsies is representative for the entire tumor. Preoperative endoscopic biopsies and matched resection specimens were collected from 75 patients who underwent esophagectomy for esophageal adenocarcinoma. Immunohistochemical staining (IHC) on HER2 and dual-color in situ hybridization (ISH) were performed. HER2 status was determined by following a clinical algorithm, first determining HER2 overexpression on immunohistochemistry and, when equivocal (2+), determining HER2 amplification on ISH. Seventy-one of 75 (95%) biopsies and 69/75 (92%) resection specimens could be analyzed due to technical failure. HER2 positivity was seen in 18/71 (25%) biopsies and in 15/69 (22%) resection specimens. Overall, HER2 status in the biopsy was concordant with HER2 status in the resection specimen in 94% of cases. Interobserver agreement on IHC scoring for all three observers was 83% in biopsies and 85% in resection specimens. HER2 positivity was detected in 22% of esophageal adenocarcinomas. Although interobserver agreement was moderate, HER2 status of a primary tumor can be reliably determined based on the endoscopically obtained pretreatment biopsy.

Human epidermal growth factor receptor-2 in oesophageal cancers: An observational study

AIM: To determine the incidence of human epidermal growth factor receptor 2 (HER2) over expression in oesophageal cancers.

METHODS: A retrospective study, of one hundred consecutive cases of endoscopic histological samples of oesophageal cancers from a single British cancer network were included. Cancer cases were diagnosed between April 2007 and June 2010. HER2 over expression was assessed using immunohistochemistry, those that scored “0” and “+1” were considered “negative” for HER2; those that scored “+3” were considered “Positive”. Cases that were scored “+2” on immunohistochemistry further went on to have HER2 gene analysis using the Ventana HER brightfield dual-colour in situ hybridisations (HER B DISH) assay and either came back to be positive or negative for HER2 over expression. Overall survival was measured from date of histological diagnosis until date of death. 93% of the cases were followed up till five years or death, and all were followed up till two years. Cases of gastro-oesophageal junctional tumours were excluded.

RESULTS: The median age of our sample was 66 years (range: 38-91 years). Eighty one were male and 19 female. Ninety-one of the cases were adenocarcinoma of the oesophagus and the rest were cases of squamous cell carcinoma. The anatomical distribution of the tumours was; upper oesophagus 2, middle oesophagus 11, and 87 were in the lower oesophagus. Operative resection was completed in 15 cases; seven cases had attempted surgical resections, i.e., open and close, 33 patients received definitive chemo-radiation and 52 had palliative treatment. Twenty-five of the cancers showed evidence of HER2 over expression, all were adenocarcinomas. Of the 25 cases that showed evidence of HER2 over expression, 21 (84%) were located in the lower third of the oesophagus. On staging, 24 out of the 25 HER2 positive cases were at stage 3 or more (13 at stage 3 and 11 at stage 4), For HER2 negative cases 37 were at stage 3 and 32 were staged as stage 4. Seventeen out of twenty five cases (68%) with HER2 over expression received palliative therapy, in comparison to thirty five out of seventy five (46.7%) in tumours not expressing HER2. No significant difference in overall survival was demonstrated between patients whose cancers showed evidence of HER2 over expression and those who did not; median overall survival for HER2 positive tumours was 15 mo (95%CI, 11-19 mo) compared to 13 mo (95%CI, 9-17 mo) for HER2 negative ones. Two years cumulative survival for cases with HER2 over expression was 33.7% compared to 31.6% in cases without HER2 over expression (P = 0.576). Only cancer’s stage significantly affected overall survival on both univariant and multivariable analysis (P = 0.034 and P = 0.009 respectively). None of the patients included in this study received Trastuzumab.

CONCLUSION: Twenty-seven point five percent of oesophageal adenocarcinomas showed evidence of HER2 over expression. Routine testing for human HER2 in oesophageal adenocarcinomas can have significant implication on treatments offered to patients that may potentially affect their prognosis.

Clinicopathological characteristics of human epidermal growth factor receptor 2-positive Barrett's adenocarcinoma

AIM: To compare the clinicopathological characteristics of human epidermal growth factor receptor 2 (HER2)-positive and HER2-negative Barrett’s adenocarcinoma in Japan.

METHODS: We performed immunohistochemical analysis of HER2 in 30 samples taken from patients with Barrett’s adenocarcinoma and dual color in situ hybridization in cases showing 2+ reactions. We compared the clinicopathological characteristics of HER2-positive and HER2-negative patients.

RESULTS: HER2 positivity was identified in 8 (27%) carcinoma samples. We found that HER2 expression was associated with p53 overexpression (100% vs 52.6% in pT1 tumor; 100% vs 54.5% in all stage tumor, P < 0.05) and protruding lesions at the early disease stage. There was no association between the mucin phenotype of the carcinomas and prognosis. HER2 expression and low clinical stage were unexpectedly different between Barrett’s adenocarcinoma patients and gastric cancer patients, but the macroscopic features may be associated with earlier diagnosis in these patients.

CONCLUSION: Our results suggest that HER2-positive Barrett’s adenocarcinomas are associated with p53 overexpression and lesion protrusion at the early disease stage.

Dasatinib, a small molecule inhibitor of the Src kinase, reduces the growth and activates apoptosis in pre-neoplastic Barrett's esophagus cell lines: evidence for a noninvasive treatment of high-grade dysplasia

BACKGROUND

Only local ablation (radiofrequency ablation, cryotherapy) or esophagectomy currently is available to treat high-grade dysplasia in Barrett's esophagus. Alternative treatments, specifically chemopreventive strategies, are lacking. Our understanding of the molecular changes of high-grade dysplasia in Barrett's esophagus offers an opportunity to inhibit neoplastic progression of high-grade dysplasia in Barrett's esophagus. Increased activity of the Src kinase and deregulation of the tumor suppressor p27 are features of malignant cells and high-grade dysplasia in Barrett's esophagus. Src phosphorylates p27, inhibiting its regulatory function and increasing cell growth and proliferation. We hypothesized that a small molecule inhibitor of Src might reduce the growth and reverse Src-mediated deregulation of p27 in Barrett's esophagus cells.

METHODS

Immortalized Barrett's esophagus cell lines established from patient biopsies were treated with the Src kinase inhibitor dasatinib and evaluated for p27 localization and protein levels, as well as for effects on the cell cycle and apoptosis using flow cytometry, viability assays, and protein and RNA markers.

RESULTS

Dasatinib reduced both Src activation and p27 phosphorylation and increased p27 protein levels and nuclear localization. These effects correlated with decreased proliferation, cell-cycle arrest, and activation of apoptosis. Analysis of biopsies of patients with Barrett's esophagus revealed the presence of phosphorylated p27 in high-grade dysplasia, consistent with in vitro findings.

CONCLUSIONS

Dasatinib has considerable antineoplastic effects on Barrett's esophagus cell lines carrying genetic markers associated with dysplasia, which correlates with the reversal of p27 deregulation. These findings suggest that dasatinib has potential as a treatment for patients with high-grade dysplasia and Barrett's esophagus and that p27 holds promise as a biomarker in the clinical use of dasatinib in patients with high-grade dysplasia and Barrett's esophagus.

Involvement of CXCR4 chemokine receptor in metastastic HER2-positive esophageal cancer

A functional linkage of the structurally unrelated receptors HER2 and CXCR4 has been suggested for breast cancer but has not been evaluated for esophageal carcinoma. The inhibition of HER2 leads to a reduction of primary tumor growth and metastases in an orthotopic model of esophageal carcinoma. The chemokine receptor CXCR4 has been implicated in metastatic dissemination of various tumors and correlates with poor survival in esophageal carcinoma. The aim of this study was to investigate a correlation between the expression levels of HER2 and CXCR4 and to evaluate the involvement of CXCR4-expression in HER2-positive esophageal carcinoma. The effects of HER2-inhibition with trastuzumab and of CXCR4-inhibition with AMD3100 on primary tumor growth, metastatic homing, and receptor expression were evaluated in vitro and in an orthotopic model of metastatic esophageal carcinoma using MRI for imaging. The clinical relevance of HER2- and CXCR4-expression was examined in esophageal carcinoma patients. A significant correlation of HER2- and CXCR4-expression in primary tumor and metastases exists in the orthotopic model. Trastuzumab and AMD3100 treatment led to a significant reduction of primary tumor growth, metastases and micrometastases. HER2-expression was significantly elevated under AMD3100 treatment in the primary tumor and particularly in the metastases. The positive correlation between HER2- and CXCR4-expression was validated in esophageal cancer patients. The correlation of CXCR4- and HER2-expression and the elevation of HER2-expression and reduction of metastases through CXCR4-inhibition suggest a possible functional linkage and a role in tumor dissemination in HER2-positive esophageal carcinoma.

Current status of SRC inhibitors in solid tumor malignancies

SUMMARY

Src is believed to play an important role in cancer, and several agents targeting Src are in clinical development.

DESIGN

We reviewed Src structure and function and preclinical data supporting its role in the development of cancer via a PubMed search. We conducted an extensive review of Src inhibitors by searching abstracts from major oncology meeting databases in the last 3 years and by comprehensively reviewing ongoing clinical trials on ClinicalTrials.gov.

RESULTS

In this manuscript, we briefly review Src structure and function, mechanisms involving Src that lead to the development of cancer, and Src inhibitors and key preclinical data establishing a rationale for clinical application. We then focus on clinical data supporting their use in solid tumor malignancies, a newer arena than their more well-established hematologic applications. Particularly highlighted are clinical trials investigating new biomarkers as well as ongoing studies assessing Src inhibitor activity in biomarker-selected patient populations. We also review newer investigational Src-targeting agents.

CONCLUSIONS

Src inhibitors have shown little activity in monotherapy trials in unselected solid tumor patient populations. Combination studies and biomarker-driven clinical trials are under way.

Her-2/neu gene amplification in esophageal adenocarcinoma and its influence on survival

BACKGROUND

HER-2/neu (c-erbB-2, HER2) gene amplification and protein overexpression have been associated with poor prognosis in several solid tumors, including breast and gastric cancer. Its incidence and significance in esophageal adenocarcinoma is unknown.

MATERIALS AND METHODS

Tissue microarrays were successfully constructed from 89 paraffin-embedded archival specimens of esophageal adenocarcinomas for HER2 gene amplification by silver-enhanced in situ hybridization (SISH). No patients had undergone neoadjuvant therapy. Protein overexpression was tested with immunohistochemistry (IHC) using automated immunostaining (Ventana Benchmark). Incidence of HER2 positivity, correlation to clinicopathological variables in esophageal cancer patients, and concordance between SISH and IHC were determined.

RESULTS

True HER2 gene amplification was detected in 14 esophageal cancer specimens (16%), and 92% of those with high-level HER2 amplification showed positive HER2 protein overexpression. No significant associations were found among gene amplification and clinicopathological factors. The 5-year survival rates were 57% for esophageal cancer patients with HER2 amplification compared with 32% without, but the difference in overall survival was not significant (P = .37). The correlation between SISH and IHC was statistically significant (P < .0001).

CONCLUSION

While molecular targeting may be possible for approximately 16% of esophageal adenocarcinoma patients, HER2 oncogene amplification did not influence survival in this study.

Current diagnosis and future impact of micrometastases for therapeutic strategies in adenocarcinoma of the esophagus, gastric cardia, and upper gastric third

Esophageal and gastric cancers are aggressive neoplasms with a poor prognosis. Although postoperative mortality has declined and rates of complete resection have improved considerably, 5 year survival rates are still very low. Early metastatic relapse after complete resection of an apparently localized primary lesion indicates that disseminated tumor cells, undetectable by current methods, may already have been present at the time of surgery, even in patients with seemingly early tumor stages. Occult residual tumor disease is suggested when either bone marrow or lymph nodes from which tumor relapse may originate are affected by micrometastatic lesions undetectable by conventional histopathology. The presence of single tumor cells detected by immunohistological methods is increasingly regarded as a clinically relevant prognostic factor. The use of antibodies against tumor-associated targets enables detection of individual epithelial tumor cells in lymph nodes and in bone marrow in various tumor entities. The potential role and -benefit of an antibody-based treatment as a therapeutic target would be of particular interest in tumors with a notoriously poor prognosis such as esophageal cancer and cardia cancer.

Low Level of Her-2 Locus Amplification by Fluorescent In Situ Hybridization Does Not Correlate with Her-2 Protein Overexpression by Immunohistochemistry in Barrett's Esophagus

An accurate evaluation of the Her-2 status has important prognostic and therapeutic implications in many carcinomas. The aim of the study was to correlate Her-2 locus (17q11.2) amplification and chromosome 17 gains as assessed by fluorescent in situ hybridization (FISH) with Her-2 protein overexpression by immunohistochemistry (IHC) in patients with Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). We analyzed 34 patients with Her-2 amplification and/or chromosome 17gains using FISH on brush cytology specimens. Seven patients (21%) showed high Her-2 locus amplification (Her-2: Cep17 ≥ 5 : 1), 5 (15%) showed low Her-2 locus amplification (Her-2: Cep17 ≥ 2 < 5 : 1), and 22 (65%) displayed gains of chromosome 17 only. Further, we confirmed Her-2 amplification on corresponding biopsies that were taken at the same occasion as the cytologybrushings. Then, we compared the FISH results with IHC data obtained from the corresponding biopsies and showed that low level of Her-2 amplification does not correlate with Her-2 protein overexpression (score +3/+2; P = 1), in contrast to the high amplification level (P = .001). Thus, in our population of BE and EAC patients, low level of Her-2 amplification does not result in detectable level of Her-2 protein as assessed by IHC.

Treatment options for esophageal cancer

There is considerable controversy over the level of evidence from randomized trials underpinning management decisions for patients presenting with localized cancer of the esophagus and esophago-gastric junction. There is also an optimism that new drugs and new approaches, including response prediction based on sequential (18)FDG-PET scanning following induction chemotherapy, may improve treatments pathways and outcomes. In this review we assess the level of evidence from the major published trials, and discuss new trials and approaches.

Statins in esophageal cancer cell lines: promising lead?

Barrett's-associated esophageal adenocarcinoma (BEAC) is an important health concern in many western populations owing to its increasing incidence and the paucity of effective treatments. Statins have recently been suggested to induce anticancer effects against a variety of cancers in several, but not all, in vitro, in vivo, and epidemiologic studies. In the accompanying article by Ogunwobi and Beales, three statins were shown to inhibit proliferation and stimulate apoptosis in two EAC cell lines. These effects were achieved by reducing Ras, extracellular signal-regulated kinase (ERK), and protein kinase B (Akt)-related cellular signaling. Although these results are promising, they are clearly preliminary, and much additional work is needed to confirm or refute the potential anticancer effects of statins in human BEAC. In addition, the work of Ogunwobi and Beales highlights the importance of developing better, more predictive in vitro and in vivo models of BEAC, and of taking promising, low-risk agents, such as statins, into early-phase therapeutic and preventive clinical trials involving cancer patients and patients with Barrett's metaplasia/dysplasia, respectively.

Significance of HER2 low-level copy gain in Barrett's cancer: implications for fluorescence in situ hybridization testing in tissues

PURPOSE

HER2 may be a relevant biomarker in Barrett's cancer. We compared three HER2 laboratory methods, standard fluorescence in situ hybridization (FISH), image-based three-dimensional FISH in thick (16 microm) sections, and immunohistochemistry, to predict patient outcome.

EXPERIMENTAL DESIGN

Tissue microarray sections from 124 Barrett's cancer patients were analyzed by standard FISH on thin (4 microm) sections and by image-based three-dimensional FISH on thick (16 microm) sections for HER2 and chromosome-17, as well for p185(HER2) by immunohistochemistry. Correlations with clinical and follow-up data were examined.

RESULTS

Only three-dimensional FISH on thick (16 microm) sections revealed HER2 gene copy gain to be associated with increased disease-specific mortality (relative risk, 2.1; 95% confidence interval, 1.06-4.26; P = 0.033). In contrast, standard FISH on thin (4 microm) sections and immunohistochemistry failed to predict clinical outcome. Low-level gain of HER2 occurred frequently in Barrett's cancer (>or=2.5-4.0 HER2 copies, 59.7%; HER2-to-chromosome-17 ratio, >or=1.1-2.0; 61.2%) and defined a subpopulation for patient outcome as unfavorable as HER2 gene amplification [disease-free survival, P = 0.017 (HER2 copies)]. This low-level group was neither definable by standard FISH nor immunohistochemistry. No prognostic significance was found for chromosome-17 aneusomy.

CONCLUSIONS

Low-level copy gains of HER2 define a biologically distinct subpopulation of Barrett's cancer patients. Importantly, these subtle copy number changes are not reliably detected by standard FISH in thin (4 microm) tissue sections, highlighting a thus far unrecognized weakness in HER2 FISH testing. These results should be taken into account for accurate evaluation of biomarkers by FISH and for HER2 FISH testing in tissue sections.

Frequent homogeneous HER-2 amplification in primary and metastatic adenocarcinoma of the esophagus

HER-2 is the target for antibody based treatment of breast cancer (Herceptin). In order to evaluate the potential role of such a treatment in esophageal cancers, HER-2 amplification and overexpression was investigated in primary and metastatic cancers of the esophagus. A tissue microarray was constructed from 255 primary esophageal cancers (110 adenocarcinomas and 145 squamous cell carcinomas), 89 nodal and 33 distant metastases. Slides were analyzed by immunohistochemistry (HercepTest; DAKO) and fluorescence in situ hybridization (FISH; PathVysion; Vysis-Abbott) for HER-2 amplification and overexpression. Amplification was seen in 16/110 (15%) adenocarcinomas and in 7/145 (5%) squamous cell carcinomas. There was a strong association between HER-2 amplification and overexpression, especially in adenocarcinomas (P<0.0001, log rank). There was a 100% concordance of the HER-2 results in primary tumor and corresponding metastases in 84 analyzed pairs. Amplification was typically high-level with more than 10-15 HER-2 copies per tumor cell. Amplification was unrelated to survival, grading, pT, pN, pM or UICC stage. We conclude that esophageal adenocarcinomas belong to those cancer types with relevant frequency high-level HER-2 gene amplification clinical trials or individual case studies investigating the response of metastatic HER-2-positive esophageal cancers to Herceptin((R)) should be undertaken. The strong concordance of the HER-2 status in primary and metastatic cancers argues for a possible response of metastases from patients with HER-2-positive primary tumors to Herceptin.

Phase I/II study of trastuzumab, paclitaxel, cisplatin and radiation for locally advanced, HER2 overexpressing, esophageal adenocarcinoma

PURPOSE

To determine the overall survival for patients with locally advanced, HER2 overexpressing, esophageal adenocarcinoma receiving trastuzumab, paclitaxel, cisplatin, and radiation on a Phase I-II study.

METHODS AND MATERIALS

Patients with adenocarcinoma of the esophagus without distant organ metastases and 2+/3+ HER2 overexpression by immunohistochemistry (IHC) were eligible. All patients received cisplatin 25 mg/m2 and paclitaxel 50 mg/m2 weekly for 6 weeks with radiation therapy (RT) 50.4 Gy. Patients received trastuzumab at dose levels of 1, 1.5, or 2 mg/kg weekly for 5 weeks after an initial bolus of 2, 3, or 4 mg/kg.

RESULTS

Nineteen patients were entered: 7 (37%) had celiac adenopathy, and 7 (37%) had retroperitoneal, portal adenopathy, or scalene adenopathy. Fourteen of 19 patients (74%) had either 3+ HER2 expression by immunohistochemistry, or an increase in HER2 gene copy number by HER2 gene amplification or high polysomy by fluorescence in situ hybridization. The median survival of all patients was 24 months and the 2-year survival was 50%.

CONCLUSIONS

Assessment of the effect of trastuzumab in the treatment of patients with esophageal adenocarcinoma overexpressing HER2 is limited by the small number of patients in this study. Overall survival, however, was similar to prior studies without an increase in toxicity. Evaluation of HER2 status should be performed in future trials for patients with adenocarcinoma of the esophagus that investigate therapies targeting the HER family.

Her-2/neu in barrett esophagus: a comparative study between histology, immunohistochemistry, and fluorescence in situ hybridization

Her-2/neu is a protooncogene frequently overexpressed in breast cancer, recently found to be also overexpressed in carcinoma arising on Barrett esophagus (BE). Immunohistochemistry and fluorescence in situ hybridization (FISH) are conventionally used for Her-2 testing in carcinomas, but a single assay is not yet accepted as a "gold standard" in BE. To evaluate the correlation between histopathology variables and gene expression/amplification in the sequence BE-low grade dysplasia-high grade dysplasia-adenocarcinoma, fifty esophageal specimens from patients with a diagnosis of BE (21 BE, 4 low-grade dysplasia, 12 high-grade dysplasia, and 13 adenocarcinomas) were evaluated. Histopathologic evaluation was carried out using hematoxylin and eosin staining. Paraffin-embedded tissues were investigated for Her-2 by immunohistochemistry (HercepTest) and FISH. HercepTest was scored 0, 1+, 2+, and 3+ depending on the percentage (cut off 10%) of membrane staining, whereas gene assessment evaluated by FISH was based on the ratio between Her-2/neu and the 17 chromosome copy number. There was a positive correlation between gene amplification and protein overexpression. No case with HercepTest scoring 0 or 1+ displayed gene amplification, but this was present in 20% of cases scoring 2+ and in all cases scoring 3+. Her-2/neu amplification or overexpression was never observed in BE. Gene amplification and overexpression was observed in more than 50% of dysplasias and adenocarcinomas. Her-2/neu amplification/overexpression might be considered as a marker of progression from BE to dysplasia. FISH may represent a useful diagnostic tool to integrate the result of HercepTest for selecting patients for more targeted therapeutic approaches.

HER-2 overexpression (3+) in patients with squamous cell esophageal carcinoma correlates with poorer survival

The incidence of esophageal carcinoma is increasing worldwide. In Sweden, approximately 400 patients are diagnosed each year. The present study retrospectively investigates survival in 97 patients with esophageal carcinoma in regard to their HER-2 status as examined by immunohistochemistry (IHC) and chromogen in situ hybridization (CISH). Sixty-eight patients had localised disease and 29 patients had advanced disease. Seventy patients had squamous cell carcinoma, and nine of these patients (13%) had HER-2 overexpression (3+). Eight (30%) of 27 adenocarcinoma patients overexpressed (3+) HER-2. In patients overexpressing (3+) HER-2 a statistical trend towards poorer survival was observed (P = 0.057). In squamous cell carcinoma patients, HER-2 overexpression (3+) correlated with poorer survival (P = 0.035), whereas in adenocarcinoma patients, HER-2 status (3+) did not. HER-2 amplification according to CISH was present in five (two squamous cell carcinomas and three adenocarcinomas) out of 17 HER-2 overexpressing (3+) tumours. In conclusion, HER-2 overexpression (3+) seems to be associated with poorer survival in esophageal carcinomas, especially in patients with squamous cell esophageal carcinoma.

Multistage carcinogenesis in Barrett's esophagus

The multistage carcinogenesis of esophageal adenocarcinoma is a process of clonal evolution within Barrett's esophagus neoplasms. The initiating event for Barrett's esophagus is unknown, but is associated with chronic gastric reflux which probably also promotes progression. Inactivation of both alleles of CDKN2A appear to be early events causing clonal expansion. Clones with TP53 inactivated expand if they have already inactivated CDKN2A. After TP53 has been inactivated, tetraploid and aneuploid clones tend to develop. The final events that lead to invasion and metastasis are unknown. Evolutionary biology provides important tools to understand clonal evolution in progression and cancer prevention.

Molecular targets for treatment of Barrett's esophagus

SUMMARY. Esophageal cancer is one of the most deadly forms of gastrointestinal cancer with a mortality rate exceeding 90%. The major risk factors for esophageal adenocarcinoma are gastroesophageal reflux disease (GERD) and its sequela, Barrett's esophagus. GERD commonly leads to esophagitis. In a minority of patients however, ongoing GERD leads to replacement of esophageal squamous mucosa with metaplastic, intestinal-type Barrett's mucosa. In the setting of continued peptic injury, Barrett's mucosa can give rise to esophageal adenocarcinoma. Despite the widespread use of potent acid suppressive therapies for patients with GERD, the incidence of esophageal adenocarcinoma, among white men in the USA, the UK and Europe has continued to rise. Cancers in Barrett's esophagus arise through a sequence of genetic events that endow the cells with six essential physiologic hallmarks of cancer as described by Hanahan and Weinberg in 2000. These cancer hallmarks include the ability to proliferate without exogenous stimulation, to resist growth-inhibitory signals, to avoid triggering the programmed death mechanism (apoptosis), to resist cell senescence, to develop new vascular supplies (angiogenesis), and to invade and metastasize. While the acquisition of these essential attributes is not specific to the neoplastic progression of Barrett's esophagus, this review will focus on the genetic alterations that occur in Barrett's cells that contribute to the acquisition of each of the hallmarks. Moreover, potential diagnostic and therapeutic strategies for Barrett's patients aimed at each of these cancer hallmarks will be reviewed.

Monoclonal antibody to HER-2/neu receptor enhances radiosensitivity of esophageal cancer cell lines expressing HER-2/neu oncoprotein

PURPOSE

The role of HER-2/neu in the response of esophageal cancer to radiation is not well known. The purpose of this study was to evaluate the effect of an anti-HER-2/neu antibody trastuzumab on the proliferation, cell cycle distribution, and radiosensitivity of esophageal cancer cell lines.

EXPERIMENTAL DESIGN

Expression of HER-2/neu protein by four esophageal squamous cancer cell lines (KE4, TE8, TE9, and TE10) and an esophageal adenocarcinoma cell line (SKGT4) was assessed using immunohistochemical (IHC) analysis and flow cytometry. We also evaluated HER-2/neu oncogene expression by fluorescence in situ hybridization. As a control for HER-2/neu protein expression and gene amplification, breast cancer cell lines (MCF7, MDA MB175VII, and SKBR3) were also examined. The cytotoxity of trastuzumab (0.1-200 microg/mL) was estimated by the MTT assay, and the cell cycle distribution was determined by flow cytometry. The effect of 10 microg/mL trastuzumab combined with radiation was assessed by a clonogenic assay.

RESULTS

Flow cytometry and IHC revealed that two esophageal cancer cell lines (TE9 and SKGT4) showed HER-2/neu expression (IHC 1+ and mean fluorescence intensity of 11-20), while the other esophageal cancer cell lines were negative for HER-2/neu expression. Although trastuzumab alone had no effect on the esophageal cancer cell lines, the combination of 10 microg/mL trastuzumab with radiation showed a synergistic effect on the HER-2/neu expressing cell lines.

CONCLUSIONS

This study suggested that trastuzumab plus irradiation may be effective for the treatment of esophageal cancers, including adenocarcinoma and squamous cell cancer with HER-2/neu expression.

MUC4 is increased in high grade intraepithelial neoplasia in Barrett's oesophagus and is associated with a proapoptotic Bax to Bcl-2 ratio

BACKGROUND

Patients with Barrett's oesophagus (BO) are at risk of oesophageal adenocarcinoma. Because the pattern of mucosal mucins changes during neoplastic progression, it may serve as a marker of intraepithelial neoplasia.

AIMS

To determine the expression pattern of mucins in neoplastic BO epithelium (high grade dysplasia) and correlate it with the expression of apoptosis markers Bax and Bcl-2.

METHODS

Thirty seven patients with BO were studied: 16 without intraepithelial neoplasia, six with high grade intraepithelial neoplasia (HGN), and 15 with infiltrating adenocarcinoma. Biopsies were obtained from squamous epithelium, Barrett's epithelium, and (when present) foci of suspected HGN or adenocarcinoma. MUC1-4, MUC5AC, MUC5B, MUC6, Bax, and Bcl-2 mRNA were determined by semiquantitative RT-PCR. MUC2, MUC5AC, and MUC6 protein was determined by immunoblotting.

RESULTS

Mucin expression varied between neoplastic progression stages in BO. Mucin mRNA levels were low in squamous epithelium, except for MUC4, and were at least four times higher in BO and HGN (p<0.001), but less so in adenocarcinoma. MUC4 expression was significantly lower in BO than in normal squamous epithelium, whereas in HGN and adenocarcinoma, levels were significantly higher than in BO (p = 0.037). The Bax:Bcl-2 ratio was increased in HGN compared with BO (p = 0.04). MUC2, MUC5AC, and MUC6 protein values correlated with mRNA data.

CONCLUSIONS

Mucin expression varies during the development of oesophageal adenocarcinoma in BO. MUC4 could serve as a tumour marker in this process. In contrast to animal studies, upregulation of MUC4 in HGN is associated with increased apoptosis, suggesting that MUC4 plays a minor role in apoptosis regulation in BO.

The molecular biology of esophageal adenocarcinoma

BACKGROUND

Barrett's esophagus is an acquired metaplastic change that occurs in the distal esophagus secondary to chronic gastroesophageal reflux. This premalignant condition forms the most important risk factor for developing esophageal adenocarcinoma, which is an extremely aggressive tumor with a 5-year survival rate of less than 25%. Carcinomas that arise in the setting of Barrett's esophagus are thought to develop as part of the metaplasia-dysplasia-carcinoma sequence.

OBJECTIVE

To review the current knowledge on the genomic alterations involved in the development of Barrett's esophagus and its progression to dysplasia and/or cancer.

RESULTS

Several changes in gene structure, gene expression, and protein structure are associated with the progression of Barrett's esophagus to adenocarcinoma. Accumulation of these changes seems to be essential, rather than the exact sequence of these changes. Multiple molecular pathways are involved and interact with each other. Alterations in tumor suppressor genes, amongst which p53 and p16, are early events in the metaplasia-dysplasia-adenocarcinoma sequence, followed by loss of cell cycle checkpoints. Ongoing genomic instability leads to cumulative genetic errors and thereby the generation of multiple clones of transformed cells.

CONCLUSIONS

Within the multistep process of esophageal adenocarcinogenesis, to date no single molecular marker came forward able to predict who will and who will not develop cancer in the setting of Barrett's esophagus. Instead, panels of markers need to be developed in the future allowing to indicate disease progression. Identification of crucial molecular pathways involved in esophageal adenocarcinogenesis would ultimately improve therapy and facilitate development of new treatment strategies.

Cell cycle regulation in patients with intestinal metaplasia at the gastro-oesophageal junction

BACKGROUND/AIMS

The incidence of oesophageal adenocarcinoma is increasing rapidly and this may be related to the presence of intestinal metaplasia (IM) at the gastro-oesophageal junction (GOJ). Recent studies have distinguished two subtypes of IM at the GOJ: short segment Barrett's oesophagus (SSBO) and IM at a normal squamo-columnar junction (IMNSCJ). Because abnormal expression of cell cycle regulators is common in cancer and precancerous states, cell cycle regulation was studied in patients with IM at the GOJ.

METHODS

Biopsy samples and resected materials were identified from patients with SSBO (10), IMNSCJ (14), a normal SCJ with (14) and without (12) inflammation, conventional Barrett's oesophagus (BO) (12), and oesophageal adenocarcinoma (12). Sections were stained with antibodies to p21, p27, p53, Ki67, cyclin D1, and c-erbB2 and were assessed independently by two observers, using predetermined criteria.

RESULTS

Patients with oesophageal adenocarcinoma showed high expression of c-erbB2, p53, p27, and Ki67. Patients with BO showed expression of c-erbB2 but little expression of other markers. Greatly increased expression of cyclin D1 was seen in patients with IMNSCJ. The expression of all other markers was similar in patients with IMNSCJ and those with SSBO. Cyclin D1 and c-erbB-2 were coexpressed in patients with SSBO and IMNSCJ, and their expression was associated with the presence of p53 and p21.

CONCLUSIONS

Although the proposed aetiologies of SSBO (gastro-oesophageal reflux) and IMNSCJ (Helicobacter pylori infection) differ, the cell cycle response is similar and both may have malignant potential.

Modification of insulin-like growth factor 1 receptor, c-Src, and Bcl-XL protein expression during the progression of Barrett's neoplasia

Oncogenes, growth factors, cell surface receptors, and cell-cycle and apoptotic regulatory proteins have been implicated in the growth regulation and progression of Barrett's-associated neoplasia. Among these, insulin-like growth factor 1 receptor (IGF1-R) and c-Src are reported to be key regulators of mitogenesis and tumorigenesis. In addition, c-Src may exert its transforming capability by inducing increased expression of IGF1-R on the neoplastic cells. Bcl-X(L), a member of the Bcl-2 family, blocks apoptosis and has been reported to increase in Barrett's-associated neoplasia. To study the modifications in IGF1-R, c-Src, and Bcl-X(L) protein expression during the progression of Barrett's-associated neoplasia, we analyzed 34 resected gastroesophagectomy specimens by immunohistochemistry using antibodies to human IGF1-R, c-Src, and Bcl-X(L). In these cases, we found 22 intestinal (Barrett's) metaplasias (IMs), 25 low-grade dysplasias (LGDs), 28 high-grade dysplasias (HGDs), 34 invasive adenocarcinomas (CAs), and 19 lymph node metastases. High IGF1-R cytoplasmic staining was present in 14 of 19 (74%) node metastases, in 28 of 34 (82%) CAs, in 18 of 28 (64%) HGDs, in 13 of 25 (52%) LGDs, and in 5 of 22 (23%) IMs. Strong and diffuse c-Src expression was identified in 17 of 19 (89%) node metastases, in 29 of 34 (85%) Cas, in 26 of 28 (93%) HGDs, in 18 of 25 (72%) LGDs, and in 9 of 22 (41%) IMs. Bcl-X(L) cytoplasmic staining was evident in 12 of 19 (63%) node metastases, in 20 of 34 (59%) Cas, in 20 of 28 (71%) HGDs, in 15 of 25 (60%) LGDs, and in 6 of 22 (27%) IMs. In 11 cases, c-Src activity was measured by kinase assay and reflected the immunohistochemical results. Our data indicate that expression levels of IGF1-R, c-Src, and Bcl-X(L) proteins are coordinately elevated in Barrett's-associated neoplasia. These findings indicate important roles of these growth regulatory proteins in the malignant progression of Barrett's-associated neoplasia.

Barrett's esophagus: model of neoplastic progression

Human cancer progression is characterized by clonal expansion of cells with accumulated genetic errors. Invasive carcinomas contain all the genetic errors that were acquired during neoplastic progression and then continue to accumulate further abnormalities, leading to tumor heterogeneity. Many investigations of human cancer have given valuable insights in genetic abnormalities important for tumor biology. Early events responsible for neoplastic progression, however, are often impossible to investigate in invasive cancers because the premalignant tissue in which the tumors develop are often overgrown and the premalignant conditions cannot be studied in vivo because they are either not detected owing to lack of symptoms or are removed before cancer develops. Unlike many other premalignant conditions Barrett's esophagus is often associated with symptoms leading to diagnosis at an early stage before cancer develops, and the premalignant epithelium is seldom removed at an early stage of cancer progression. Furthermore, in patients who present with invasive carcinoma the tumor is often surrounded by premalignant epithelium, which is available for further investigations. Therefore Barrett's esophagus is an excellent model in which to study the early events of neoplastic progression. It may not only contribute to a better understanding of the neoplastic process but also provide a base for safer assessment of cancer risk during surveillance for early detection of esophageal adenocarcinoma.

The role of receptor tyrosine kinase inhibition in treating gastrointestinal malignancy

Tyrosine kinase receptors are proteins that transduce the signal from many growth factor and cytokine ligands to produce intracellular responses. As such they can activate multiple signalling cascade pathways and influence cell division, migration and survival. Many show upregulation in certain malignancies, including those of the gastrointestinal tract, and are thought to play key roles in carcinogenesis. This makes them attractive targets for drug therapy and in recent years many inhibitors have been developed. This review discusses the current situation regarding the development of inhibitors with particular reference to the erbB family, the insulin-like growth factor receptor, the Met receptor, the receptor for vascular endothelial growth factor and the Kit receptor. The evidence will be related back to cancers of the gut lumen. Clinical effectiveness in this area seems to lie in using a combinatorial approach that inhibits multiple key signalling points, and the reasons for this will be discussed.

Gene amplification and protein overexpression of c-erb-b2 in Barrett carcinoma and its precursor lesions

We examined 39 samples of metaplastic specialized epithelium (SE), 27 of low-grade dysplasia (LGD), 27 of high-grade dysplasia (HGD), and 46 of adenocarcinoma (CA) derived from Barrett esophagus for c-erb-b2 gene amplification using differential polymerase chain reaction and for overexpression of c-erb-b2 protein using immunohistochemical analysis. Amplification of the c-erb-b2 gene was as follows: SE, 0.0%; LGD, 0.0%; HGD, 11.1%; and CA, 13.6%; and protein overexpression was as follows: SE, 0.0%; LGD, 7.4%; HGD, 18.5%; and CA, 21.7%. In 8 (89%) of 9 samples, c-erb-b2 gene amplification correlated with protein overexpression. The reverse was true in 8 (47%) of 17 samples: c-erb-b2 protein overexpression was proved with simultaneous gene amplification. Amplification of c-erb-b2 is a late event in the carcinogenesis of Barrett esophagus. In contrast, protein overexpression appears more often and earlier Besides gene amplification, other mechanisms to induce protein overexpression must exist.

Genetic pathways involved in the progression of Barrett's metaplasia to adenocarcinoma

BACKGROUND

The prediction of which patients with Barrett's metaplasia will develop cancer is difficult. Better genetic characterization of the condition may aid clinicians in devising more effective management and follow-up strategies.

METHODS

A review was undertaken of the accumulated genetic data relating to the progression of squamous epithelium to adenocarcinoma. The normal functions of a number of cancer-related genes are described and an explanation is given of how alterations in these genes interfere with normal cell processes and lead to cancer.

RESULTS AND CONCLUSION

The main genetic alterations accompanying the progression through dysplasia to adenocarcinoma were collated from 135 papers. The principal genetic changes implicated are the loss of p16 gene expression (by deletion or hypermethylation), the loss of p53 expression (by mutation and deletion), the increase in cyclin D1 expression, the induction of aneuploidy and the losses of the Rb, DCC and APC chromosomal loci.

Molecular and biologic basis of upper gastrointestinal malignancy--esophageal carcinoma

Esophageal cancer is one of the most deadly forms of gastrointestinal cancer. Even though the incidence of esophageal adenocarcinoma has been rising in Western populations over the past two decades, esophageal squamous cell carcinoma remains the predominant type of esophageal malignancy in the remainder of the world. With the recent advances in molecular biology, high-output genome wide screening has provided comprehensive profiles of molecular alterations in human esophageal carcinomas. The elucidation of the basic mechanisms of esophageal carcinogenesis brings with it the promise of developing treatment and preventive strategies that are based on the molecular biology of these tumors. The genetic alterations discussed in this article are not unique to the formation of esophageal carcinomas and represent only a fraction of the molecular changes found in these tumors. The goal of this article is to provide the clinician with a useful conceptual basis for evaluating studies on the molecular mechanisms underlying the development of esophageal carcinomas.

Role of molecular biology in the follow-up of patients who have Barrett's esophagus

At present, the follow-up of patients who have Barrett's esophagus (BE) should occur within the setting of an endoscopic biopsy surveillance program and with the frequency of surveillance as proposed by the American College of Gastroenterology. In the future, patients who have BE will be further stratified according to their risk for progression to invasive carcinoma. This stratification will permit the development of more rational surveillance programs. Models that incorporate epidemiologic risk factors, reflux symptoms, and endoscopic and histologic findings will likely include panels of biomarkers for further stratification of patients as low, intermediate, or high risk. Therefore, the challenge over the next decade will be to define the role of molecular markers in endoscopic surveillance strategies and to identify additional clinically relevant molecular markers for prognosis as intermediate markers for chemoprevention and as molecular targets for novel gene therapies.

Targeting HER2 in other tumor types

The human epidermal growth factor receptor-2 (HER2) is overexpressed/amplified in a range of tumor types including breast, ovarian, bladder, salivary gland, endometrial, pancreatic and non-small-cell lung cancer (NSCLC). HER2 is implicated in disease initiation and progression, associated with poor prognosis, and may also predict the response to chemotherapy and hormonal therapy. Anti-HER2 monoclonal antibodies (MAbs) have been designed to specifically antagonize the function of the HER2 receptor in HER2-positive tumors. Clinical phase II and III trials have demonstrated the efficacy of the humanized anti-HER2 MAb, trastuzumab (Herceptin), both as a single agent and in combination with chemotherapy in HER2-positive, metastatic breast cancer patients. However, the prevalence of HER2 overexpression/amplification in various tumor types raises the possibility of using anti-HER2 MAbs to antagonize the abnormal function of overexpressed HER2 receptors in HER2-positive tumors other than breast. Preliminary in vitro studies indicate that anti-HER2 MAbs suppress the proliferation of ovarian, gastric and NSCLC cell lines that overexpress the HER2 receptor. These results indicate that anti-HER2 MAbs may have important therapeutic significance in patients presenting with these or other human carcinomas. Clinical trials are either planned or underway to assess the therapeutic role of trastuzumab in NSCLC, bladder and ovarian cancer.

The treatment, management and prevention of oesophageal cancer

The combination of a rising incidence and a poor survival rate makes oesophageal cancer a major health issue. Adenocarcinoma of the oesophagus is associated with one of the commonest pre-malignant lesions recognised, Barrett's metaplasia. This provides a focus for early detection and intervention. The subjects of acid suppression, bile reflux, COX-2 inhibition and ablation therapy will be discussed herewith. Established carcinoma is now rarely treated by surgery alone and this review discusses the benefits of multimodality therapy combined with more accurate staging techniques. Finally an emerging understanding of the molecular events that characterise the transition to carcinoma may provide novel targets in cancer therapy such as epidermal growth factor receptor (EGFR) and TNF-alpha. This review will focus on some of the future developments in the treatment of oesophageal cancer.

Review article: a conceptual approach to understanding the molecular mechanisms of cancer development in Barrett's oesophagus

Oesophageal adenocarcinoma is one of the most deadly human malignancies. Gastro-oesophageal reflux disease (GERD) has been established as a strong risk factor for oesophageal adenocarcinoma, and more than 40% of adult Americans experience regular GERD symptoms. GERD can be complicated by oesophagitis, and by replacement of oesophageal squamous mucosa with metaplastic, intestinal-type epithelium (Barrett's oesophagus) that is predisposed to malignancy. Cancers in Barrett's oesophagus arise through a sequence of genetic alterations which endow unlimited proliferative capacity upon the cells by affecting components of the cell cycle clock apparatus-the pivotal molecular machinery in the cell nucleus that controls whether a cell will proliferate, differentiate, become quiescent or die. This report describes how the genetic abnormalities that have been recognized in Barrett's oesophagus might promote carcinogenesis through effects on the cell cycle clock machinery. The goal of this review is to provide the clinician with a useful conceptual basis for evaluating studies on the molecular mechanisms underlying the progression from metaplasia to carcinoma in Barrett's oesophagus.

The HER-2/neu oncogene in tumors of the gastrointestinal tract

The HER-2/neu oncogene is localized to chromosome 17q and shares significant homology with the epidermal growth factor receptor. As a result of its potential role in the selection of therapy, HER-2/neu testing has reached near-standard-of-practice status in breast cancer. There is considerable interest in HER-2/neu as a prognostic factor and target of therapy in tumors of the gastrointestinal tract. In this review of HER-2/neu expression in esophageal squamous cell carcinoma and adenocarcinomas of the esophagus, stomach, and colon, a wide range of expression of HER-2/neu from 0 to 83% likely reflects both differences in methods and reagents, as well as study bias associated with patient selection (i.e., early versus advanced disease). For esophageal squamous cell carcinoma, little information exists as to the prognostic significance of HER-2/neu expression. In adenocarcinoma associated with Barrett's esophagus there is contradictory data. However, most of the information available indicates that this marker has significant prognostic value. In gastric adenocarcinoma, the wide expression range may truly reflect patient selection because HER-2/neu positivity appears linked to advanced rather than early disease with limited invasion. The majority of studies favor a significant prognostic value of HER-2/neu status for this tumor. Finally, in colorectal cancer HER-2/neu overexpression also appears to be a significant adverse outcome indicator as judged by the current published literature. In conclusion, given that either HER-2/neu protein overexpression or gene amplification is associated with approximately one-fourth of all gastrointestinal tract malignancies, strategies designed to employ the marker in therapy selection appear warranted. During the next several years it will not be surprising to see these tumors treated with antiHER-2/neu modalities such as Herceptin, likely in combination with other agents initially for patients with advanced disease, and possibly for individuals with high-risk lesions in an adjuvant setting.

Her-2/neu gene amplification, elevated mRNA expression, and protein overexpression in the metaplasia-dysplasia-adenocarcinoma sequence of Barrett's esophagus

SUMMARY

The importance of alterations of the Her-2/neu oncogene in the tumorigenesis of Barrett's adenocarcinoma (BCA) is discussed controversially. In the present study, we evaluated for the first time the Her-2/neu status in the metaplasia-dysplasia-adenocarcinoma sequence of BCA simultaneously at the DNA, mRNA, and protein level using resection specimens of 25 patients. The locus-specific Her-2/neu gene status was quantified by performing fluorescence in situ hybridization, and information about the ploidy status of chromosome 17 was obtained. Tissue sections from the same areas were used for quantitative RT-PCR (TaqMan RT-PCR) of laser-microdissected tumor cells and for immunohistochemistry to quantify Her-2/neu mRNA and oncoprotein expression. Her-2/neu gene amplification was observed in 35% of BCA, and all of these samples showed strong overexpression of both mRNA and oncoprotein. A polysomy 17 without Her-2/neu gene amplification was observed in 52% of BCA, showing a normal or moderately elevated mRNA expression and no or weak immunopositivity. From 13 areas of high-grade dysplasia (HGD) we found four to be amplified for the Her-2/neu locus, whereas five showed a polysomy 17. All four samples of HGD areas with Her-2/neu gene amplification displayed mRNA and strong oncoprotein overexpression; however, lower mRNA levels were seen than in the amplified BCA areas. None of the samples with low-grade dysplasia (LGD) showed a locus-specific Her-2/neu amplification, but polysomy 17 was present in four of eight cases. No changes were detected in BCA-associated intestinal metaplasia and squamous epithelium. In summary, only a locus-specific Her-2/neu gene amplification was associated with strong mRNA overexpression and strong membranous Her-2/neu immunostaining in BCA and HGD. A chromosome 17 polysomy, as found in the majority of BCA, led to no or weak mRNA overexpression and no or weak immunopositivity. In the metaplasia-dysplasia-adenocarcinoma sequence, a chromosome 17 polysomy without Her-2/neu gene amplification was already present in LGD. This may be a result of an early polyploidization, preceding the later genetic events, such as Her-2/neu gene amplification in HGD and BCA.

Biomarkers in Barrett esophagus

Barrett esophagus is a premalignant condition that may progress to adenocarcinoma. The risk of developing cancer has been estimated to be approximately 1 in 250 patient-years of observation; however, there appear to be subsets of patients at much higher risk. Risk stratification has previously been determined by histological identification of dysplasia. Several new biomarkers are being tested to help clinicians better determine the risk of cancer development. Although none of these biomarkers has been proven in a prospective study to predict the onset of cancer, they have been correlated with cancer development. Most of these are factors that have been associated with cancer development in other organs. These include assessment of cell proliferation, expression of cyclooxygenase 2, growth factors and oncogenes, secretory factors, cell cycle proteins, adhesion molecules, and aneuploidy and other genetic abnormalities. In addition to their role as potential cancer biomarkers, these factors have increasingly been reported as surrogate markers to monitor the effectiveness of conservative treatments for Barrett esophagus. In this article, biological markers are reviewed for their relevance in Barrett esophagus. Although most biological markers need to be evaluated further and, for most, prospective follow-up studies are lacking, at present abnormal ploidy status, P16 and P53 gene abnormalities, or allelic losses are the most extensively documented.

Biomarkers in Barrett esophagus

Barrett esophagus is a premalignant condition that may progress to adenocarcinoma. The risk of developing cancer has been estimated to be approximately 1 in 250 patient-years of observation; however, there appear to be subsets of patients at much higher risk. Risk stratification has previously been determined by histological identification of dysplasia. Several new biomarkers are being tested to help clinicians better determine the risk of cancer development. Although none of these biomarkers has been proven in a prospective study to predict the onset of cancer, they have been correlated with cancer development. Most of these are factors that have been associated with cancer development in other organs. These include assessment of cell proliferation, expression of cyclooxygenase 2, growth factors and oncogenes, secretory factors, cell cycle proteins, adhesion molecules, and aneuploidy and other genetic abnormalities. In addition to their role as potential cancer biomarkers, these factors have increasingly been reported as surrogate markers to monitor the effectiveness of conservative treatments for Barrett esophagus. In this article, biological markers are reviewed for their relevance in Barrett esophagus. Although most biological markers need to be evaluated further and, for most, prospective follow-up studies are lacking, at present abnormal ploidy status, P16 and P53 gene abnormalities, or allelic losses are the most extensively documented.

Molecular biology of Barrett's adenocarcinoma

OBJECTIVE

To review the current knowledge on the genetic alterations involved in the development and progression of Barrett's esophagus-associated neoplastic lesions.

SUMMARY BACKGROUND DATA

Barrett's esophagus (BE) is a premalignant condition in which the normal squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium. BE predisposes patients to the development of esophageal adenocarcinoma. Endoscopic surveillance can detect esophageal adenocarcinomas when they are early and curable, but most of the adenocarcinomas are detected at an advanced stage. Despite advances in multimodal therapy, the prognosis for invasive esophageal adenocarcinoma is poor. A better understanding of the molecular evolution of the Barrett's metaplasia to dysplasia to adenocarcinoma sequence may allow improved diagnosis, therapy, and prognosis.

METHODS

The authors reviewed data from the published literature to address what is known about the molecular changes thought to be important in the pathogenesis of BE-associated neoplastic lesions.

RESULTS

The progression of Barrett's metaplasia to adenocarcinoma is associated with several changes in gene structure, gene expression, and protein structure. Some of the molecular alterations already showed promise as markers for early cancer detection or prognostication. Among these, alterations in the p53 and p16 genes and cell cycle abnormalities or aneuploidy appear to be the most important and well-characterized molecular changes. However, the exact sequence of events is not known, and probably multiple molecular pathways interact and are involved in the progression of BE to adenocarcinoma.

CONCLUSIONS

Further research into the molecular biology of BE-associated adenocarcinoma will enhance our understanding of the genetic events critical for the initiation and progression of Barrett's adenocarcinoma, leading to more effective surveillance and treatment.

Mucin gene expression in Barrett's oesophagus: an in situ hybridisation and immunohistochemical study

BACKGROUND AND AIMS

Mucin genes are expressed in a site specific manner throughout the gastrointestinal tract. Little is known about the expression pattern in the oesophagus. In this study we have investigated MUC gene expression in both the normal oesophagus and specialised intestinal metaplasia (Barrett's oesophagus).

PATIENTS

Archived paraffin embedded material from eight specimens of normal oesophagus, 18 Barrett's oesophagus, eight gastric metaplasia, six high grade dysplasia, and six cases of adenocarcinoma were examined for expression of the mucin genes MUC1-6.

METHODS

Mucin mRNA was detected by in situ hybridisation using [(35)S] dATP labelled oligonucleotide probes. Mucin core protein was detected by immunohistochemistry.

RESULTS

Normal oesophagus expressed MUC5B in the submucosal glands and MUC1 and MUC4 in the stratified squamous epithelium. Barrett's oesophagus strongly expressed MUC5AC and MUC3 in the superficial columnar epithelium, MUC2 in the goblet cells, and MUC6 in the glands. In high grade dysplasia and adenocarcinoma there was downregulation of MUC2, MUC3, MUC5AC, and MUC6, but upregulation of MUC1 and MUC4 in half of the specimens examined.

CONCLUSIONS

Normal oesophagus and Barrett's oesophagus have a novel pattern of mucin gene expression. Barrett's oesophagus expressed the mucins associated with normal gastric epithelium and normal intestinal epithelium. While most mucin genes were downregulated in severely dysplastic and neoplastic tissues, there was upregulation of the membrane bound mucins MUC1 and MUC4. This may prove useful in detecting early signs of progression to adenocarcinoma of the oesophagus.