Spironolactone-induced XPB degradation depends on CDK7 kinase and SCFFBXL18 E3 ligase.

The multisubunit complex transcription factor IIH (TFIIH) has dual functions in transcriptional initiation and nucleotide excision repair (NER). TFIIH is comprised of two subcomplexes, the core subcomplex (seven subunits) including XPB and XPD helicases and the cyclin-dependent kinase (CDK)-activating kinase (CAK) subcomplex (three subunits) containing CDK7 kinase. Recently, it has been reported that spironolactone, an anti-aldosterone drug, inhibits cellular NER by inducing proteasomal degradation of XPB and potentiates the cytotoxicity of platinum-based drugs in cancer cells, suggesting possible drug repositioning. In this study, we have tried to uncover the mechanism underlying the chemical-induced XPB destabilization. Based on siRNA library screening and subsequent analyses, we identified SCFFBXL18 E3 ligase consisting of Skp1, Cul1, F-box protein FBXL18 and Rbx1 responsible for spironolactone-induced XPB polyubiquitination and degradation. In addition, we showed that CDK7 kinase activity is required for this process. Finally, we found that the Ser90 residue of XPB is essential for the chemical-induced destabilization. These results led us to propose a model that spironolactone may trigger the phosphorylation of XPB at Ser90 by CDK7, which promotes the recognition and polyubiquitination of XPB by SCFFBXL18 for proteasomal degradation.

Neuroendocrine carcinoma of the esophagus: Clinicopathological and immunohistochemical features of 14 cases.

BACKGROUND: Neuroendocrine carcinoma (NEC) of the esophagus is a rare and highly aggressive disease but the biological features are poorly understood. The objective of this study was to analyze the clinicopathological and immunohistochemical features of NEC of the esophagus. METHODS: Fourteen patients diagnosed with NEC of the esophagus from 1998 to 2013 were included in this study. Clinicopathologic features, therapeutic outcomes and immunohistochemical results were analyzed. RESULTS: Eleven out of 14 cases showed protruding or localized type with or without ulceration. Only three patients were negative for both lymph node and organ metastasis and seven cases were positive for metastases to distant organs and/or distant lymph nodes. Of the six patients with limited disease (LD), three patients were treated by surgery. Three patients with LD and seven patients with extensive disease (ED) were initially treated with chemotherapy, except for one who underwent concurrent chemo-radiotherapy due to passage disturbance. The median survival of patients with LD was 8.5 months, whereas that of patients with LD was 17 months. Among the 14 cases, 12 cases (83.3%), 13 cases (91.7%) and 12 cases (83.3%) showed positive immunostaining for choromogranin A, synaptophysin and CD56, respectively. Nine of 14 cases (64.2%) presented positive staining for c-kit and most (8/9, 88%) simultaneously showed p53 protein abnormality. Two cases were negative for c-kit and p53, and positive for CK20. CONCLUSION: Consistent with previous reports, the prognosis of NEC of esophagus is dismal. From the results of immunohistochemical study, NEC of esophagus might be divided into two categories due to the staining positivity of c-kit and p53. This study provides new insight into the biology of NEC of the esophagus.

Retrograde colon intussusception in an adult due to adenoma: treatment by combined laparoscopic and endoscopic approach.

This report describes the case of a young patient who underwent laparoscopic surgery to reduce for a retrograde intussusception of the sigmoid-descending colon caused by adenoma of the sigmoid colon. A 36-year-old woman visited our hospital, complaining primarily of vomiting and abdominal pain. Abdominal CT scan showed the typical finding of intussusception. An emergency colonoscopy revealed that the invaginated colon with a polypoid mass was protruding into the descending colon. A gastrografin enema showed the invaginated bowel segment at the descending colon. We performed endoscopic polypectomy and then hand-assisted laparoscopic reduction. The pathological finding showed tubular adenoma. Laparoscopy is a diagnostic or therapeutic tool for selected cases of adult intussusception. Benign tumor is one of the causes of intussusception in adults and a good indication for laparoscopic surgery.

Predictive factors of esophageal stenosis associated with tumor regression in radiation therapy for locally advanced esophageal cancer.

The purpose of this retrospective study was to clarify the predictive factors correlated with esophageal stenosis within three months after radiation therapy for locally advanced esophageal cancer. We enrolled 47 patients with advanced esophageal cancer with T2-4 and stage II-III who were treated with definitive radiation therapy and achieving complete response of primary lesion at Kyushu University Hospital between January 1998 and December 2005. Esophagography was performed for all patients before treatment and within three months after completion of the radiation therapy, the esophageal stenotic ratio was evaluated. The stenotic ratio was used to define four levels of stenosis: stenosis level 1, stenotic ratio of 0-25%; 2, 25-50%; 3,50-75%; 4,75-100%. We then estimated the correlation between the esophageal stenosis level after radiation therapy and each of numerous factors. The numbers and total percentages of patients at each stenosis level were as follows: level 1: n = 14 (30%); level 2: 8 (17%); level 3: 14 (30%); and level 4: 11 (23%). Esophageal stenosis in the case of full circumference involvement tended to be more severe and more frequent. Increases in wall thickness tended to be associated with increases in esophageal stenosis severity and frequency. The extent of involved circumference and wall thickness of tumor region were significantly correlated with esophageal stenosis associated with tumor regression in radiation therapy (p = 0.0006, p = 0.005). For predicting the possibility of esophageal stenosis with tumor regression within three months in radiation therapy, the extent of involved circumference and esophageal wall thickness of the tumor region may be useful.