Yasuaki Miyazaki

Upregulation of miR-196a and HOTAIR Drive Malignant Character in Gastrointestinal Stromal Tumors

Large intergenic noncoding RNAs (lincRNA) have been less studied than miRNAs in cancer, although both offer considerable theranostic potential. In this study, we identified frequent upregulation of miR-196a and lincRNA HOTAIR in high-risk gastrointestinal stromal tumors (GIST). Overexpression of miR-196a was associated with high-risk grade, metastasis and poor survival among GIST specimens. miR-196a genes are located within the HOX gene clusters and microarray expression analysis revealed that the HOXC and HOTAIR gene were also coordinately upregulated in GISTs which overexpress miR-196a. In like manner, overexpression of HOTAIR was also strongly associated with high-risk grade and metastasis among GIST specimens. RNA interference-mediated knockdown of HOTAIR altered the expression of reported HOTAIR target genes and suppressed GIST cell invasiveness. These findings reveal concurrent overexpression of HOX genes with noncoding RNAs in human cancer in this setting, revealing miR-196a and HOTAIR as potentially useful biomarkers and therapeutic targets in malignant GISTs.

A Novel Correlation between LINE-1 Hypomethylation and the Malignancy of Gastrointestinal Stromal Tumors

Purpose: Gastrointestinal stromal tumors (GIST) are the most important mesenchymal tumors of the gastrointestinal tract. The vast majority of GISTs exhibit activating mutations of KIT or PDGFRA, but epigenetic alteration of GISTs is largely unknown. In this study, we aimed to clarify the involvement of DNA methylation in GIST malignancy. Experimental Design: A total of 106 GIST specimens were studied. Levels of LINE-1 methylation were analyzed using bisulfite pyrosequencing. In addition, methylation of three other repetitive sequences (Alu Yb8, Satellite-α, and NBL2) was similarly analyzed, and CpG island hypermethylation was analyzed using MethyLight. Array-based comparative genomic hybridization (array CGH) was carried out in 25 GIST specimens. Results: LINE-1 hypomethylation was significantly correlated with risk, and high-risk GISTs exhibited significantly lower levels of LINE-1 methylation than low-risk (61.3% versus 53.2%; P = 0.001) or intermediate-risk GISTs (60.8% versus 53.2%; P = 0.002). Hypomethylation of Satellite-α and NBL2 was also observed in high-risk GISTs. By contrast, promoter hypermethylation was relatively infrequent (CDH1, 11.2%; MLH1, 9.8%; SFRP1, 1.2%; SFRP2, 11.0%; CHFR, 9.8%; APC, 6.1%; CDKN2A, 0%; RASSF1A, 0%; RASSF2, 0%) and did not correlate with LINE-1 methylation or risk. Array CGH analysis revealed a significant correlation between LINE-1 hypomethylation and chromosomal aberrations. Conclusions: Our data suggest that LINE-1 hypomethylation correlates significantly with the aggressiveness of GISTs and that LINE-1 methylation could be a useful marker for risk assessment. Hypomethylation may increase the malignant potential of GISTs by inducing accumulation of chromosomal aberrations. Clin Cancer Res; 16(21); 5114–23. ©2010 AACR.

New findings of kinase switching in gastrointestinal stromal tumor under imatinib using phosphoproteomic analysis.

Despite the revolutionary effects of imatinib on advanced gastrointestinal stromal tumors (GISTs), most patients eventually develop disease progression following primary resistance or acquired resistance driven by secondary‐resistant mutations. Even in radiographically vanishing lesions, pathology has revealed persistent viable cells during imatinib therapy, which could lead to the emergence of drug‐resistant clones. To uncover the mechanisms underlying these clinical issues, here we examined imatinib‐induced phosphoproteomic alterations in GIST‐T1 cells, using our quantitative tyrosine phosphoproteomic analysis method, which combined immunoaffinity enrichment of phosphotyrosine‐containing peptides with isobaric tags for relative and absolute quantitation (iTRAQ) technology. Using this approach, we identified 171 tyrosine phosphorylation sites spanning 134 proteins, with 11 proteins exhibiting greater than 1.5‐fold increases in tyrosine phosphorylation. Among them, we evaluated FYN and focal adhesion kinase (FAK), both of which are reportedly involved in proliferation and malignant alteration of tumors. We confirmed increased tyrosine phosphorylation of both kinases by western blotting. Inhibition of FYN and FAK phosphorylation each increased tumor cell sensitivity to imatinib. Furthermore, a FAK‐selective inhibitor (TAG372) induced apoptosis of imatinib‐resistant GIST‐T1 cells and decreased the imatinib IC50. These results indicate that FYN or FAK might be potential therapeutic targets to overcome resistance to imatinib in GISTs. Additionally, we showed that the iTRAQ‐based quantitative phosphotyrosine‐focused phosphoproteomic approach is a powerful method for screening phosphoproteins associated with drug resistance.

Gastrointestinal stromal tumor: a bridge between bench and bedside

Gastrointestinal stromal tumor (GIST) is considered to be driven by a gain-of-function mutation in the KIT or PDGFRA gene. Cure can be obtained only by complete surgical removal of the GIST; however, imatinib, an inhibitor of KIT and PDGFRA, is indicated for advanced, recurrent, and/or metastatic GISTs. Imatinib exhibited remarkable clinical effects on advanced GISTs, with substantial tolerability. Its efficacy greatly depends on the genotype of GIST. The drug, however, met intrinsic or acquired resistance during the treatment, of which the molecular mechanisms were mostly dependent on the genotype of GIST, including primary mutations or secondary mutations in the kinase domains of the corresponding target genes, respectively. Although sunitinib had substantial effects on imatinib-resistant GIST, this drug also encountered primary or secondary resistance depending on the genotype. Thus, advanced GIST may require multidisciplinary treatment. Because resistance mechanisms show some regularity, it is hoped that, in the near future, we may be able to develop a new drug to which resistance does not occur easily, based on scientific evidence.

Esophageal submucosal dissection under steady pressure automatically controlled endoscopy (SPACE) : a randomized preclinical trial

BACKGROUND AND STUDY AIMS A new overtube system has been developed for steady pressure automatically controlled endoscopy (SPACE) in the gastrointestinal tract. The objectives of this study were to validate the feasibility and safety of SPACE in the esophagus, and to evaluate its potential advantages over conventional (manually insufflating) endoscopy in endoscopic submucosal dissection (ESD). METHODS This was a multicenter preclinical trial using acute porcine models (n = 20). In Experiment 1 (feasibility/safety study), SPACE was attempted in the esophagus with continuous monitoring of cardiopulmonary parameters and intraluminal pressures in the downstream bowel. Different insufflation pressures were tested to optimize the insufflation condition. Each session was video-recorded and scored by blinded reviewers. In Experiment 2 (randomized trial), esophageal ESD was attempted using either SPACE or conventional endoscopy, and results were compared. RESULTS In Experiment 1, SPACE was performed safely without intraluminal pressure elevation in the downstream bowel. According to video review, SPACE provided more stable, reproducible, and rapid visualization than conventional endoscopy. The insufflation pressure was optimized at 14 mmHg for esophageal SPACE. In Experiment 2, ESD was completed in all animals. The ESD time was significantly shorter with SPACE compared with conventional endoscopy (1326 vs. 1616 seconds; P = 0.009). Responses to questionnaires showed that 94 % - 100 % of participants considered SPACE to provide improved exposure and more uniform tissue tension than conventional endoscopy. Other data were comparable. CONCLUSIONS SPACE is feasible, safe, and potentially effective for complicated endoscopic procedures, such as ESD. SPACE improves and standardizes endoscopic exposure and tissue tension. A clinical study is required to further confirm its safety and clinical effectiveness.

Surgical strategy for the gastric gastrointestinal stromal tumors (GISTs) larger than 5 cm: laparoscopic surgery is feasible, safe, and oncologically acceptable.

Background: The efficacy and feasibility of laparoscopic surgery (LAP) for gastric GISTs >5 cm has not been adequately assessed. Here we investigated the clinical outcomes of these patients. Patients and Methods: Twenty-seven consecutive patients who underwent resection for gastric GISTs >5 cm were enrolled in this retrospective study. We assessed the tumor characteristics, surgical outcomes, tumor recurrence, and patient survival in the open surgery (OPEN) group and in the LAP group. Results: The tumor size in the OPEN group was larger than that in the LAP group, but there were no differences in the mitotic count. There were no differences in operative complications. Finally, there were no differences in the disease-free and no patients in the LAP group died. Conclusions: In patients with gastric GISTs >5 cm, LAP can be performed with outcomes equivalent to those of OPEN if patient selection and intraoperative judgment are appropriate.

Esophageal submucosal dissection under steady pressure automatically controlled endoscopy (SPACE): a clinical feasibility study.

BACKGROUND AND STUDY AIMS Steady pressure automatically controlled endoscopy (SPACE) is a new insufflation system that provides constant carbon dioxide (CO2) insufflation pressure during prolonged procedures. The system consists of an overtube, a surgical insufflator, and a newly developed leak-proof valve. The aims of this study were to validate the feasibility and safety of SPACE for esophageal endoscopic submucosal dissection (ESD). PATIENTS AND METHODS This was a clinical phase I trial, involving 10 patients who underwent esophageal ESD. The primary end point was the rate of adverse events within 30 days (grade 0 to 4). Secondary end points were changes in partial pressure of carbon dioxide (PaCO2) and vital signs during ESD, completion rate of ESD, and degree of abdominal distension by patient assessment and radiographic grading. RESULTS All adverse events were Grade 2 or less. Mild PaCO2 elevation after ESD was noted; however, no associated symptoms were reported. The procedure was completed under SPACE alone in 8 of 10 patients. Minimal post-procedural bowel distension was observed. CONCLUSIONS In this small pilot study, SPACE was feasible and appeared to be safe. Further study with larger case numbers is required to demonstrate efficacy and safety. CLINICAL TRIAL REGISTRATION UMIN000005434.

Impact of number of [(18)F]fluorodeoxyglucose-PET-positive lymph nodes on survival of patients receiving neoadjuvant chemotherapy and surgery for oesophageal cancer.

[18F]fluorodeoxyglucose (FDG)‐PET has been used to evaluate the response of primary tumours to neoadjuvant therapy for oesophageal cancer. The clinical significance of the number of PET‐positive nodes before and after therapy has not been investigated previously.