Objective To identify a high affinity IRF-1 binding element in the translational start site of XAF1 promoter. Methods By the bioinformatics analysis, a putative IFN regulatory factor 1 binding element (IRF-E), named as IRFE-XAF1, was identified from -30nt to -38nt of the XAF1 gene, with 76.2% homogeneity with the synonymous IRF-E sequence. Electrophoresis mobility shift assay (EMSA) was performed to confirm the binding capacity of IRFE-XAF1. Two site-directed mutations were made, one mutation site was outside of the IRF-E region (-28nt) and another located at the center of IRF-E (-34nt). The promoter of XAF1 after mutation was examined, including its binding activity and response to IFN-?. Results It was found by EMSA assay that the doublestranded oligonucleotide DNA probe, containing IRFE-XAF1 and labeled with 32P, may be connected to the nuclear protein, and blocked by the unlabeled synonymous IRF-1 probe (cold probe). The binding capacity of IRF-E was lost after site-directed mutation. The XAF1 promoter containing IRFE-XAF1 site had the priming activity, and could be induced by IFN-?. The priming activity declined markedly after site-directed mutation of IRFE-XAF1, and -34 site mutation completely eliminated the effect of IFN-?. Conclusion A high affinity of IRF-E is found in -30nt to -38nt region upstream of ATG initiator codon of XAF1 gene. The code sequence is -38nt-GAAACGAAA--30nt. The present study suggests that XAF1 is one of the genes with which IFN-? may induce the differentiation of cancer cells.

Objective To evaluate the diagnostic value of endoscopic ultrasonography (EUS), and explore the efficacy of endoscopic treatment in patients with esophageal submucosal tumor. Methods Sixty-eight patients with esophageal submucosal tumor were selected, and the tumor was derived from the muscularis mucosa and submucosa according to the common endoscope and endoscopic ultrasonography detection. Endoscopic mucosal resection (EMR) was applied to remove submucosal tumor with diameter less than 1.0 cm, endoscopic piecemeal mucosal resection (EPMR) or endoscopic submucosal dissection (ESD) was applied to remove submucosal tumor with diameter 1.1 - 1.5 cm, and ESD was applied to remove submucosal tumor bigger than 1.5 cm. Samples were examined by pathology after treatment. Results Tumors in all the patients were completely removed, and the tumor diameter was 0.6-2.3 cm. Forty-one cases were treated with EMR, 9 cases were treated with EPMR and 18 cases were treated with ESD. Four patients had intra-operative bleeding that was stopped by electrocoagulation hemostasis. No perforation occurred in all cases. Postoperative pathology revealed 43 cases had leiomyoma, 23 cases had interstitialoma, and 2 cases had lipoma. Patients were reviewed by gastroscope 3 months after operation. The white scars formed in all patients, and there was no residue or recurrence. Conclusions Different origin layers and property of esophageal submucosal tumor can be diagnosed accurately by EUS, and endoscopic therapy (EMR, EPMR and ESD) is an effective treatment for submucosal tumor from muscularis mucosa and submucosa. Endoscopic therapy is safe and effective. It provides sufficient pathological information.