Slug is a predictor of poor prognosis in esophageal squamous cell carcinoma patients.

BACKGROUND: Slug, a regulator of epithelial mesenchymal transition, was identified to be differentially expressed in esophageal squamous cell carcinoma (ESCC) using cDNA microarrays by our laboratory. This study aimed to determine the clinical significance of Slug overexpression in ESCC and determine its correlation with clinicopathological parameters and disease prognosis for ESCC patients. METHODS: Immunohistochemical analysis of Slug expression was carried out in archived tissue sections from 91 ESCCs, 61 dysplastic and 47 histologically normal esophageal tissues. Slug immunopositivity in epithelial cells was correlated with clinicopathological parameters and disease prognosis over up to 7.5 years for ESCC patients. RESULTS: Increased expression of Slug was observed in esophageal dysplasia [cytoplasmic, 24/61 (39.3%) cases, p = 0.001, odd's ratio (OR) = 4.7; nuclear, 11/61 (18%) cases, p < 0.001, OR = 1.36] in comparison with normal esophageal tissues. The Slug expression was further increased in ESCCs [cytoplasmic, 64/91 (70.3%) p < 0.001, OR = 10.0; nuclear, 27/91 (29.7%) p < 0.001, OR = 1.42]. Kaplan Meier survival analysis showed significant association of nuclear Slug accumulation with reduced disease free survival of ESCC patients (median disease free survival (DFS) = 6 months, as compared to those that did not show overexpression, DFS = 18 months; p = 0.006). In multivariate Cox regression analysis nuclear Slug expression [p= 0.005, Hazard's ratio (HR) = 2.269, 95% CI = 1.289 - 3.996] emerged as the most significant independent predictor of poor prognosis for ESCC patients. CONCLUSIONS: Alterations in Slug expression occur in early stages of development of ESCC and are sustained during disease progression. Slug may serve as a diagnostic biomarker and as a predictor of poor disease prognosis to identify ESCC patients that are likely to show recurrence of the disease.

Overexpression of a splice variant of oncostatin M receptor beta in human esophageal squamous carcinoma.

BACKGROUND: Expression of oncostatin M receptor beta (OSMRß) has been reported in human cancers, however its role in esophageal squamous cell carcinoma (ESCC) remains unknown. Using differential display, earlier we reported the identification of an alternatively spliced variant of OSMRß in ESCC. Here in we characterized this novel variant encoding a soluble form of this receptor (sOSMRß) and determined its clinical significance and correlation with the expression of oncostatin (OSM) and leukemia inhibitory factor receptor beta (LIFR ß) in ESCC. MATERIALS AND METHODS: In silico analysis was carried out to characterize the differentially expressed transcript of OSMRß and its expression was determined in ESCCs and matched normal esophageal tissues using semiquantitative RT-PCR. The expressions of both truncated and full length OSMRß proteins were analyzed in ESCC tissues and patients' sera using western blotting and immunoprecipitation. By immunoprecipitation we have also shown direct interaction between sOSMRB and OSM. We also explored the relationship between expression of OSM and its receptors, OSMRß and LIFRß, in primary human ESCCs and normal epithelia using immunohistochemistry. RESULTS: Overexpression of alternatively spliced OSMR ß transcript was detected by RT-PCR in 9 of 11 ESCCs. Analysis of the soluble receptor revealed absence of sOSMRß protein in esophageal tissues, however, immunoprecipitation and western blot analysis showed its presence in sera of ESCC patients further confirming expression of the alternatively spliced OSMR ß in ESCC patients. Immunohistochemical analysis in tissue microarray (TMA) format showed expression of OSMR ß, LIFR and OSM in 11/50 (23%), 47/50 (94%) and 47/50 (94%) ESCCs, respectively. Strong correlation was observed between cytoplasmic expression of LIFRß and OSM in tumor cells (p = 0.000, O.R = 50, 95%CI = 8-31.9), and nuclear expression of LIFRß and OSM (p = 0.039 OR = 3.1, 95% CI = 1.1-8.2), suggesting that LIFRß serves as the major receptor in ESCCs. CONCLUSION: An alternatively spliced variant of OSMR transcribing a soluble form of this receptor has been characterized in ESCC. We speculate that the truncated OSMR characterized here in may act as a neutralizing receptor for OSM. Our immunohistochemical study showed that OSMRß and its pathway is not activated in ESCCs.

Clinical significance of GPR56, transglutaminase 2, and NF-κB in esophageal squamous cell carcinoma.

Proteins do not operate as individual units, and components of intracellular canonical pathways often cross talk in tumor genesis. We hypothesized that G-protein-coupled receptor 56 (GPR56), transglutaminase (TG2), and nuclear factor-κB (NF-κB) may collaborate in interconnected pathways and contribute to the aggressive behavior of esophageal squamous cell carcinoma (ESCC). Immunohistochemical analysis of GPR56, TG2, and NF-κB was carried out using ESCC tissue microarrays. Immunostaining of all the three proteins revealed a significant increase in their expression in ESCCs as compared with normal epithelia and correlated with their concomitant expression. A significant correlation between GPR56, TG2, and NF-κB was observed that correlated with nodal metastasis and tumor invasion in ESCCs.

Nuclear and cytoplasmic accumulation of Ep-ICD is frequently detected in human epithelial cancers.

BACKGROUND: We previously demonstrated that nuclear and cytoplasmic accumulation of the intracellular domain (Ep-ICD) of epithelial cell adhesion molecule (EpCAM) accompanied by a reciprocal reduction of its extracellular domain (EpEx), occurs in aggressive thyroid cancers. This study was designed to determine whether similar accumulation of Ep-ICD is a common event in other epithelial cancers. METHODOLOGY AND RESULTS: Ten epithelial cancers were immunohistochemically analyzed using Ep-ICD and EpEx domain-specific antibodies. The subcellular localization of EpEx and Ep-ICD in the human colon adenocarcinoma cell line CX-1 was observed using immunofluorescence. Nuclear and cytoplasmic Ep-ICD expression was increased in cancers of the breast (31 of 38 tissues, 82%), prostate (40 of 49 tissues, 82%), head and neck (37 of 57 tissues, 65%) and esophagus (17 of 46 tissues, 37%) compared to their corresponding normal tissues that showed membrane localization of the protein. Importantly, Ep-ICD was not detected in the nuclei of epithelial cells in most normal tissues. High nuclear and cytoplasmic Ep-ICD accumulation also occurred in the other six epithelial cancer types analyzed - lung, colon, liver, bladder, pancreatic, and ovarian. A concomitant reduction in membrane EpEx expression was observed in a subset of all cancer types. Receiver operating characteristic curve analysis revealed nuclear Ep-ICD distinguished breast cancers with 82% sensitivity and 100% specificity and prostate cancers with 82% sensitivity and 78% specificity. Similar findings were observed for cytoplasmic accumulation of Ep-ICD in these cancers. We provide clinical evidence of increased nuclear and cytoplasmic Ep-ICD accumulation and a reduction in membranous EpEx in these cancers. CONCLUSIONS: Increased nuclear and cytoplasmic Ep-ICD was observed in all epithelial cancers analyzed and distinguished them from normal tissues with high-sensitivity, specificity, and AUC. Development of a robust high throughput assay for Ep-ICD will facilitate the determination of its diagnostic, prognostic and therapeutic relevance in epithelial cancers.

Sperm protein 17 is a novel marker for predicting cisplatin response in esophageal squamous cancer cell lines.

Expression of sperm protein 17 (Sp17) mRNA has been reported in various malignancies. In an earlier study, we reported the upregulation of Sp17 transcripts in primary esophageal squamous cell carcinomas (ESCCs) using differential display and detected Sp17 transcripts in 86% of ESCCs by RT-PCR, whereas no transcripts were detected in the paired normal esophageal tissues. Herein we hypothesized that Sp17 might be used as a marker for detecting the response of anticancer therapies in ESCCs. Our results indicated that Sp17 protein levels in esophageal squamous cancer cell lines decreased in response to treatment with (i) the HSP90 activity inhibitor geldanamycin, (ii) the tyrosine kinase inhibitor erlotinib and (iii) cisplatin (chemotherapeutic agent commonly used in management of ESCC). In contrast, the Sp17 levels did not decrease in response to radiation therapy and treatment with the chemotherapeutic agent, gemcitabine. Further investigations showed that cisplatin induced decrease in Sp17 levels was due to transcriptional inhibition and cisplatin-resistant cell lines did not show this decrease in Sp17 levels in response to cisplatin treatment. In addition, we also carried our mass spectophotometric analysis to identify the binding partners of Sp17 to characterize its possible involvement in esophageal tumorigenesis and chemoresistance.