Makoto Sohda

The incremental effect of positron emission tomography on diagnostic accuracy in the initial staging of esophageal carcinoma

The purpose of the current study was to assess whether [18F]fluorodeoxyglucose positron emission tomography (FDG‐PET) provides incremental value (e.g., additional information on lymph node involvement or the presence of distant metastases) compared with computed tomography (CT) in patients with esophageal carcinoma.

FAK overexpression is correlated with tumour invasiveness and lymph node metastasis in oesophageal squamous cell carcinoma

Focal adhesion kinase (p125FAK; ‘FAK’) is a tyrosine kinase that is localised to cellular focal adhesions and is associated with a number of other proteins, such as integrin adhesion receptors. We performed an immunohistochemical analysis of FAK protein expression to determine the relationship between FAK overexpression and clinicopathological factors in oesophageal squamous cell carcinoma (ESCC). We examined tissue specimens that had been removed from 91 patients with thoracic oesophageal cancer who had undergone surgery between 1983 and 2001. Immunohistochemical staining was performed by the standard streptavidin–biotin method. Seven human ESCC cell lines–TE-1, TE-2, TE-8, TE-13, TE-15, TT, and TTn–and one immortalized human keratinocyte cell line–HaCaT–were used in Western blot analysis. Immunostaining of FAK was seen in the cytoplasm of cancer cells, particularly in cells located in the invasive fronts of cancer nests. FAK overexpression was detected in 54 of the 91 patients (59.3%). Significant correlations were observed between FAK overexpression and cell differentiation (P=0.0057), depth of tumour invasion (P=0.0023), presence of regional lymph node metastasis (P=0.0097), number of lymph node metastases (P=0.0026), and disease stage (P=0.012). The survival rates of patients with FAK-overexpressing cancer were significantly lower than those of patients without FAK-overexpression cancer (P=0.006). The 5-year survival rate of patients without FAK overexpression was 69%, whereas that of patients with FAK overexpression was 38%. On Western blot analysis, FAK was expressed at a high level in TE-1, TE-8, TE-15, and TT cells, at a moderate level in TE-2 and TTn cells, and at a low level in TE13 and HaCaT cells. FAK phosphorylation at tyrosine 397 was demonstrated in proportion to the intensity of FAK in all cell lines except TE15 and HaCaT. In conclusion, FAK overexpression of ESCC was related to cell differentiation, tumour invasiveness, and lymph node metastasis. Consequently, patients with ESCC who had FAK overexpression had a poor prognosis.

Genetic Alterations in Esophageal Cancer

Esophageal cancer is a common malignancy with a striking variation in geographical distribution; a reflection of exposure to specific environmental factors, which are still poorly defined. We discuss the recent progress made in the investigation of the molecular biology of esophageal cancer, addressing the topics of genetic alterations, methylation, overexpression of molecules thought to cause malignant transformation, carcinogenesis, invasion, and metastasis. We review six aspects of the research literature on esophageal cancer: epidemiology and etiology, epidermal growth factor receptor and related growth factor receptors, cell cycle regulatory proteins, transforming growth factor-β/Smad proteins, mismatch repair genes, and other genes. This article provides a conceptual basis for evaluating studies on the molecular mechanism of esophageal carcinogenesis and for devising therapeutic and preventive strategies based on molecular biology. We hope that in the near future, the clinical outcome of patients with esophageal carcinoma will be improved by a better understanding of the basic mechanisms of carcinogenesis.

MiR‐150 is associated with poor prognosis in esophageal squamous cell carcinoma via targeting the EMT inducer ZEB1

The association of microRNAs (miRs) with cancer progression has been established in many cancers including esophageal squamous cell carcinoma (ESCC). A public microarray database showed that the expression of miR‐150 was lower in ESCC than in normal esophageal mucosa. Here, we focused on ZEB1, epithelial‐mesenchymal‐transition (EMT)‐inducer, as a target gene of miR‐150 based on in silico predictions. The purpose of this study was to clarify the clinicopathological significance of miR‐150 in ESCC, and to investigate miR‐150′s EMT‐regulatory ability. Quantitative RT‐PCR was used to evaluate miR‐150 expression in 108 curative resected ESCC samples to determine the clinicopathological significance. Moreover, we examined the in vitro and in vivo function of miR‐150 via degradation of ZEB1. MiR‐150 expression was significantly lower in cancer tissues compared to adjacent non‐cancerous tissues (P < 0.001). Low expression of miR‐150 in ESCC contributed to malignant potential, such as tumor depth, lymph node metastasis, lymphatic invasion, venous invasion, clinical staging, and poor prognosis (P < 0.05). In vitro assays showed that EMT‐inducer‐ZEB1 is a new direct target of miR‐150. Moreover, miR‐150 induced MET‐like changes in TE‐8 cells through ZEB1 degradation (e.g., E‐cadherin expression, vimentin repression, epithelial morphology, and suppression of migration ability), and significantly inhibited tumorigenicity and tumor growth in a mouse xenograft model. Analysis of the regulation of ZEB1 by miR‐150 could provide new insights into preventing metastasis and also suggests novel targeted therapeutic strategies in ESCC. (Cancer Sci 2013; 104: 48–54)

Increased expression of c-Ski as a co-repressor in transforming growth factor-β signaling correlates with progression of esophageal squamous cell carcinoma

Transforming growth factor‐β (TGF‐β) regulates cell growth inhibition, and inactivation of the TGF‐β signaling pathway contributes to tumor development. In our previous study, altered expression of TGF‐β, TGF‐β‐specific receptors and Smad4 was shown to correlate with tumor progression in esophageal squamous cell carcinoma (SCC). These components, however, were maintained normally in some patients with esophageal SCC. In our study, the mechanism by which aggressive esophageal SCC maintains these components was investigated, with particular emphasis on the participation of c‐Ski and SnoN as transcriptional co‐repressors in TGF‐β signaling. Immunohistochemistry for c‐Ski and SnoN was carried out on surgical specimens obtained from 80 patients with esophageal SCC. The expression of c‐Ski and SnoN was also studied in 6 established cell lines derived from esophageal SCC and compared to an immortalized human esophageal cell line by Western blotting. High levels of expression of c‐Ski, detected immunohistologically, were found to correlate with depth of invasion (p = 0.0080) and pathologic stage (p = 0.0447). There was, however, no significant correlation between expression of SnoN and clinicopathologic characteristics. A significant correlation between c‐Ski and TGF‐β expression was observed. Moreover, in patients with TGF‐β negative expression, the survival rates of patients with c‐Ski positive expression were significantly lower than those of patients with c‐Ski negative expression (p = 0.0486). c‐Ski was expressed at a high level in 5 of 6 cell lines derived from esophageal SCC compared to immortalized esophageal keratinocytes. Furthermore, the cyclin‐dependent kinase (CDK) inhibitor, p21 that was up‐regulated by TGF‐β signaling was expressed at a low level in the 5 cell lines. The expression of c‐Ski protein as a transcriptional co‐repressor in TGF‐β signaling seems to be correlated with tumor progression of esophageal SCC.

The clinical application of 18F‐fluorodeoxyglucose positron emission tomography to predict survival in patients with operable esophageal cancer

Metabolic tumor activity using 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) was believed to have a predictive value for patient outcome in malignancies. The objective of the current study was to assess the prognostic effectiveness of the highest standardized uptake value (SUV) in the primary or regional area (peak SUV) and the number of PET‐positive lymph nodes in esophageal cancer.

Pretreatment evaluation of combined HIF‐1α, p53 and p21 expression is a useful and sensitive indicator of response to radiation and chemotherapy in esophageal cancer

Tumor hypoxia has been known to be associated with resistance to radiation and chemotherapy (CRT). Hypoxia‐inducible factor‐1α (HIF‐1α), a transcription factor induced by hypoxic condition, plays a major role in the pleiotropic response observed under hypoxic conditions. It encodes proteins that play key roles in critical development and physiologic processes, including angiogenesis, glucose transport and erythropoiesis. On the other hand, cell cycle‐ and apoptosis‐control genes p53 and p21 may play major roles in the tumor response to cytotoxic agents such as radiation and chemotherapy. Previous reports have suggested that the regulation of p53 and p21 is HIF‐1‐dependent. Our aim was to evaluate the expression of the HIF‐1α, p53 and p21 proteins by immunohistochemistry in biopsy specimens of esophageal squamous cell carcinoma, which were obtained endoscopically from 65 patients before CRT, and then determine whether the levels of expression of these proteins predicted the clinical effectiveness of CRT in individual cancers. Also, to assess the relationship between expression of these proteins and cell death and cellular proliferation activity, we evaluated Ki67 expression and the apoptosis index (TUNEL). HIF‐1α expression in esophageal cancer was significantly and negatively related to the response to CRT, independently of p53 and p21 expression. Interestingly, 44.4% (12/27) of the HIF‐1α‐negative group showed a complete response to therapy. There was no significant correlation between the expression of HIF‐1α, p53 and p21 and proliferation and apoptosis. HIF‐1α overexpression may predict resistance to CRT and may be a helpful guide in choosing between therapeutic strategies, such as intensive combined modality therapy vs. palliative therapy. Combined immunohistochemical evaluation of HIF‐1α, p53 and p21 protein expression at the pretreatment biopsy is a very useful and powerful indicator of sensitivity to CRT in human esophageal cancer. Our data also indicate the importance of having a clear grasp of the degree of hypoxia (HIF‐1α) of a tumor, rather than its cellular character (proliferation and apoptosis), to indicate the likely impact of CRT.

Sentinel lymph nodes with technetium‐99m colloidal rhenium sulfide in patients with esophageal carcinoma

The authors assessed the detection of sentinel lymph nodes in patients with esophageal squamous cell carcinoma (SCC) using technetium‐99m colloidal rhenium sulfide. They studied whether an analysis of sentinel lymph nodes using cytokeratin (CK) immunohistochemistry increased the accuracy of staging.

Plasma Level of Transforming Growth Factor β1 Measured from the Azygos Vein Predicts Prognosis in Patients with Esophageal Cancer

Purpose: Transforming growth factor (TGF)-β regulates cell growth inhibition. When tumor cells lose their sensitivity to TGF-β growth inhibition, the excess TGF-β that results may act on tumor cells to facilitate tumor development. Previously, we have shown that an elevated systemic TGF-β1 level is not related to tumor progression in esophageal cancer (Y. Fukai et al., Int J Cancer 2003;104:161–6). We considered that systemic inflammation or chronic disease, in addition to the tumor, may influence the plasma TGF-β level. Therefore, we examined the hypothesis that the plasma TGF-β level measured from the azygos vein would independently predict tumor progression and prognosis in patients with esophageal cancer. Experimental Design: Fifty-seven plasma samples were obtained intraoperatively from the azygos vein in patients with esophageal cancer. ELISA was used to quantify the plasma TGF-β1 levels, which were correlated with pathological features and patient survival. Results: The mean plasma TGF-β1 level measured from the azygos vein of esophageal cancer patients was 5.09 ± 0.48 ng/ml (mean ± SE). The survival rates of patients with a high TGF-β1 level (defined as a level above the 4.6 ng/ml level of normal controls) in the azygos vein were significantly lower than those of patients with a low TGF-β1 level (P = 0.0317). Moreover, the TGF-β1 level in the azygos vein was an independent prognostic factor for overall survival (P = 0.0474). Conclusions: The level of plasma TGF-β1 measured from the azygos vein is an independent predictor in patients with esophageal cancer and may reflect tumor progression more specifically because the azygos vein is responsible for venous return from the esophagus.

Surgical Treatment for Esophageal Cancer

Esophageal cancer is one of the most difficult malignancies to cure. The prognosis remains unsatisfactory despite significant advances in surgical techniques and perioperative management. The optimal treatment strategy for localized esophageal cancer has not yet been established. Surgical resection remains the mainstay of treatment for esophageal cancer, and curative resection is the most important surgery. Extended esophagectomy with three-field lymphadenectomy provides the highest quality of tumor clearance and prolongation of patient survival. There has been intense effort in developing novel strategies to treat patients with resectable esophageal cancer. Various combined-modality approaches have been attempted to improve treatment outcomes. Definitive chemoradiotherapy has an impact on long-term survival in patients with resectable esophageal cancer. Accordingly, there are three main combined-modality approaches: esophagectomy with adjuvant chemotherapy or chemoradiotherapy; primary definitive chemoradiotherapy with or without salvage esophagectomy, and preoperative chemoradiotherapy followed by planned esophagectomy. Recently, owing to the remarkable advances in optical technology, minimally invasive esophagectomy using endoscopic instruments has been introduced into esophageal cancer surgery. This article reviews recent changes in the treatment of esophageal cancer surgery, and considers the role of esophagectomy.