Nox4-derived ROS signaling contributes to TGF-β-induced epithelial-mesenchymal transition in pancreatic cancer cells

Transforming growth factor (TGF)-β induces epithelial-mesenchymal transition (EMT) in pancreatic adenocarcinoma. In this study, we investigated how NADPH oxidase (Nox) 4-generated reactive oxygen species (ROS) regulate TGF-β-induced EMT in pancreatic cancer cells.

MATERIALS AND METHODS

Pancreatic cancer cells were transfected with Nox4 siRNAs or PTP1B mutants and subjected to TGF-β-induced EMT assay. Expression of Nox4, TGF-β, and N-cadherin was immunohistochemically-examined with patient tumor samples.

RESULTS

Treatment of pancreatic cancer cells with TGF-β induced Nox4 expression, indicating that Nox4 represents a major source for ROS production. The Nox4 inhibitor diphenylene iodonium and Nox4 siRNAs blocked TGF-β-induced EMT phenotype including morphological changes, augmented migration, and altered expression of E-cadherin and Snail. Furthermore, PTP1B as a redox-sensor for Nox4-derived ROS participated in TGF-β-promoted EMT. Nox4, TGF-β, and N-cadherin were up-regulated in tumors from pancreatic cancer patients.

CONCLUSIONS

These findings suggest that Nox4-derived ROS, at least in part, transmit TGF-β-triggered EMT signals through PTP1B in pancreatic cancer.

Esophageal cancer associated with other primary cancers--historical comparison of clinicopathologic features in 359 esophageal cancer patients

BACKGROUND/AIMS

We historically investigated the clinicopathologic features of esophageal cancer associated with other primary cancers (OPC), and discussed differences between the last decade and the previous period.

METHODOLOGY

A total of 359 patients with esophageal cancer treated between 1981 and 2006 were enrolled. They were divided into 2 groups; 213 patients between 1981 and 1996 (Group-A), and 146 patients between 1997 and 2006 (Group-B).

RESULTS

Between Group-A and Group-B, there was a significant difference in the frequency of OPC (15.5% vs. 32.2%, p < 0.001). Regarding the site of OPC, there was a significant difference in the frequency of head and neck cancers (p < 0.001). There was a significant difference in the frequency of metachronous OPC between Group-A and Group-B (5.6% vs. 18.5%, p < 0.001). Antecedent OPC was more frequently observed in Group-B than Group-A (3.3% vs. 11.0%, p < 0.01), and subsequent OPC was also more frequently observed in Group-B than Group-A (2.8% vs. 7.5%, p < 0.05). Although the 5-year survival rate after esophagectomy of the patients without OPC was better in Group-B than Group-A (31.5 % vs. 52.7 %; p < 0.01), there was no difference in that of the patients with OPC between Group-A and Group-B, (40.7% vs. 54.2%).

CONCLUSION

Metachronous as well as synchronous OPC in esophageal cancer patients were more frequent in the recent period than in the previous period. We should consider antecedent, synchronous, and subsequent OPC in esophageal cancer patients.

Gastric schwannoma exhibiting increased fluorodeoxyglucose uptake

This is the first case of gastric schwannoma that exhibited increased accumulation of [(18)F] fluorodeoxyglucose (FDG) on positron emission tomography (PET) imaging. The patient was a 60-year-old woman in whom esophagogastroduodenoscopy showed a submucosal tumor, about 25 mm in size, in the upper body of the stomach, with ulceration at the top of the tumor. Endoscopic ultrasonography revealed a well-defined hypoechoic mass located in the proper muscle layer of the stomach. The specimen taken from the tumor showed only inflammatory degenerative tissue. Abdominal computed tomography revealed a tumor in the upper body of the stomach. FDG-PET showed FDG uptake (standardized uptake value [SUV] max 5.8) coincident with the tumor. Hence, the tumor was diagnosed initially as a gastrointestinal stromal tumor of the stomach. Laparoscopic partial gastrectomy was performed. Pathological examination showed that the tumor consisted of spindle cells with large nuclei, and mitosis was absent. The Ki-67 labeling index of the tumor cells was 4%. Immunohistochemically, the tumor cells showed a positive reaction for S-100 protein, whereas they were negative for KIT, CD 34, and alpha-smooth muscle actin protein. The tumor was diagnosed as a benign gastric schwannoma. Gastric schwannoma should be included in the differential diagnosis of submucosal tumors of the stomach with FDG uptake.