Keisuke Koeda

Hypoxia-induced Jagged2 promotes breast cancer metastasis and self-renewal of cancer stem-like cells.

Notch signaling is often and aberrantly activated by hypoxia during tumor progression; however, the exact pathological role of hypoxia-induced Notch signaling in tumor metastasis is as yet poorly understood. In this study, we aimed to define the mechanism of Notch-ligand activation by hypoxia in both primary tumor and bone stromal cells in the metastatic niche and to clarify their roles in tumor progression. We have analyzed the expression profiles of various Notch ligands in 779 breast cancer patients in GEO database and found that the expression of Jagged2 among all five ligands is most significantly correlated with the overall- and metastasis-free survival of breast cancer patients. The results of our immunohistochemical (IHC) analysis for Jagged2 in 61 clinical samples also revealed that both Jagged2 and Notch signaling were strongly upregulated at the hypoxic invasive front. Activation of Jagged2 by hypoxia in tumor cells induced EMT and also promoted cell survival in vitro. Notably, a γ-secretase inhibitor significantly blocked Notch-mediated invasion and survival under hypoxia by promoting expression of E-cadherin and inhibiting Akt phosphorylation. Importantly, Jagged2 was also found to be upregulated in bone marrow stroma under hypoxia and promoted the growth of cancer stem-like cells by activating their Notch signaling. Therefore, hypoxia-induced Jagged2 activation in both tumor invasive front and normal bone stroma has a critical role in tumor progression and metastasis, and Jagged2 is considered to be a valuable prognostic marker and may serve as a novel therapeutic target for metastatic breast cancer.

Resveratrol suppresses growth of cancer stem-like cells by inhibiting fatty acid synthase.

Resveratrol is a natural polyphenolic compound and has been shown to exhibit cardio-protective as well as anti-neoplastic effects on various types of cancers. However, the exact mechanism of its anti-tumor effect is not clearly defined. Resveratrol has been shown to have strong hypolipidemic effect on normal adipocytes and as hyper-lipogenesis is a hallmark of cancer cell physiology, the effect of resveratrol on lipid synthesis in cancer stem-like cells (CD24−/CD44+/ESA+) that were isolated from both ER+ and ER− breast cancer cell lines was examined. The authors found that resveratrol significantly reduced the cell viability and mammosphere formation followed by inducing apoptosis in cancer stem-like cells. This inhibitory effect of resveratrol is accompanied by a significant reduction in lipid synthesis which is caused by the down-regulation of the fatty acid synthase (FAS) gene followed by up-regulation of pro-apoptotic genes, DAPK2 and BNIP3. The activation of apoptotic pathway in the cancer stem-like cells was suppressed by TOFA and by Fumonisin B1, suggesting that resveratrol-induced apoptosis is indeed through the modulation of FAS-mediated cell survival signaling. Importantly, resveratrol was able to significantly suppress the growth of cancer stem-like cells in an animal model of xenograft without showing apparental toxicity. Taken together, the results of this study indicate that resveratrol is capable of inducing apoptosis in the cancer stem-like cells through suppression of lipogenesis by modulating FAS expression, which highlights a novel mechanism of anti-tumor effect of resveratrol.

Tailored laparoscopic resection for suspected gastric gastrointestinal stromal tumors

BACKGROUND The aim of the present study was to evaluate the long-term outcomes of tailored laparoscopic resections for suspected gastric gastrointestinal stromal tumors (GISTs) based on the tumor size, location, and growth morphology. METHODS Between February 1994 and April 2009, 64 patients undergoing gastric resections of suspected gastric GISTs were identified in a prospectively collected database. Medical records were reviewed for patient demographics, perioperative outcomes, and follow-up. RESULTS Forty-five patients underwent attempted laparoscopic resections, with 44 completed laparoscopically. Twenty-eight neoplasms were located in the upper third of the stomach (including 6 neoplasms at the esophagogastric junction), 9 in the middle third, and 8 in the lower third (including 4 prepyloric neoplasms). Laparoscopic approaches included 35 exogastric (3 single incision access) and 10 transgastric approaches. Median operating time was 100min (range, 30-240), and blood loss was 5ml (range, 1-80). Median tumor size and operative margin were 32mm (range, 16-74) and 7mm (range, 1-20), respectively. One patient was converted to an open, pylorus-preserving gastrectomy. One patient developed a complication. The histopathologic risk assessment classifications of 37 GISTs were 2 very low, 26 low, 7 intermediate, and 2 high risk. Although 1 patient developed a local recurrence after intragastric resection, all 45 patients were disease free at a median follow-up of 74 months (range, 1-181). CONCLUSION Although technically demanding, tailored laparoscopic resection based on tumor characteristics in most patients with suspected gastric GIST is safe and feasible and resultis in good both surgical and oncologic outcomes.

Minimally Invasive Surgery for Gastric Cancer: The Future Standard of Care

Laparoscopy-assisted distal gastrectomy for gastric cancer was first reported by Kitano et al. in 1991. Laparoscopic wedge resection (LWR) and intragastric mucosal resection (IGMR) were quickly adapted for gastric cancer limited to the mucosal layer and having no risk of lymph node metastasis. Following improvements in endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), the use of LWR and IGMR for these indications decreased, and patients with gastric cancer, including those with a risk of lymph node metastases, were more likely to be managed with laparoscopic gastrectomy (LG) with lymph node dissection. Many retrospective comparative trials and randomized-controlled trials (RCT) have confirmed that LG is safe and feasible, and that short-term outcomes are better than those of open gastrectomy (OG) in patients with early gastric cancer (EGC). However, these trials did not include a satisfactory number of patients to establish clinical evidence. Thus, additional multicenter randomized-controlled trials are needed to delineate significantly quantifiable differences between LG and OG. As laparoscopic experience has accumulated, the indications for LG have been broadened to include older and overweight patients and those with advanced gastric cancer. Moreover, advanced techniques, such as laparoscopy-assisted total gastrectomy, laparoscopy-assisted proximal gastrectomy, laparoscopy-assisted pylorus-preserving gastrectomy (PPG), and extended lymph node dissection (D2) have been widely performed.In the near future, sentinel node navigation and robotic surgery will become additional options in minimally invasive surgery (MIS) involving LG. Such developments will improve the quality of life of patients following gastric cancer surgery.

Single-incision laparoscopic gastric resection for submucosal tumors: Report of three cases

Between March and April 2009, three consecutive patients underwent single-incision laparoscopic gastric wedge resection for a submucosal tumor located in the anterior wall or greater curvature of the stomach. First, we placed two or three trocars through the same infra-umbilical skin incision. Then, we either elevated the tumor with a mini-loop retractor or retracted the gastric wall near the tumor with a laparoscopic grasper. Finally, we resected the tumor using an endoscopic linear stapler. Single-incision laparoscopic gastric resection was successfully completed in all three patients without the need for any extraumbilical skin incisions or conversion to conventional laparoscopic procedures. There was no morbidity. The mean operating time and blood loss were 86 min and 4 ml, respectively, and the mean tumor size and surgical margin were 34 mm and 8 mm, respectively. Histopathologically, two tumors were diagnosed as gastrointestinal stromal tumors and one as a carcinoid tumor. Thus, single-incision laparoscopic gastric resection for submucosal tumors is safe and feasible when performed by experienced laparoscopic surgeons using conventional laparoscopic instruments.

Molecular analysis of gastric differentiated-type intramucosal and submucosal cancers

Identification of the molecular characteristics of intramucosal (IMCs) and submucosal cancers (SMCs) is essential to our understanding of early gastric carcinogenesis. However, little is known regarding the differences between the 2 lesions. One hundred and forty‐eight patients with primary early gastric cancer [IMC, 106; SMC, 42] were characterized for expression of cell cycle‐related proteins and loss of heterozygosity (LOH). We also examined microsatellite instability (MSI) and methylation status. For LOH and methylation studies, we used a panel of 17 microsatellite markers (3p, 4p, 5q, 9p. 13q, 17p, 18q and 22q) and promoter regions of 9 genes (MLH‐1, RUNX3, p16, HPP1, RASSF2A, SFRP1, DKK‐1, ZFP64 and SALL4) that are frequently altered or methylated in gastric cancers. Overexpression of p53 and cyclin D1 was observed in SMC. In addition, low expression of p27 was more frequent in SMC than in IMC. Frequencies of 4p, 9p, 13q and 22q were significantly higher in SMC than in IMC. The SALL4 gene was frequently methylated in SMC compared with IMC. However, other gene methylations were common in both IMC and SMC. The frequency of LOH‐high status/methylation‐low status was significantly higher in SMC than in IMC. However, LOH‐low status/methylation‐high status in SMC was more frequently found in IMC. Our data confirm that methylation of cancer‐related genes plays a major role in the development of IMCs. Importantly, the results also show that gastric submucosal progression is characterized by the accumulation of specific genetic alterations. In addition, changes of cell cycle‐related proteins are associated with cancer progression.

Infrequent frameshift mutations of polynucleotide repeats in multiple primary cancers affecting the esophagus and other organs.

Frequent frameshift mutations of simple nucleotide repeats in the protein‐encoding regions, as well as replication errors (RERs) at microsatellite loci, have recently been demonstrated in gastrointestinal tumors. These genetic instabilities have been considered indicative of an increased risk of accumulating mutations in cancer‐associated genes and of developing multiple cancers. We studied frameshift (or insertion/ deletion) mutations of simple nucleotide repeats in five genes (TGFβ type II receptor [TGFβRII], E2F4, MSH2, MSH3, and MSH6) in 23 tumors from 12 patients who had synchronous cancers of the esophagus and other organs. Genetic instability at four microsatellite loci, as well as mutations in the TP53, APC, and KRAS2 genes, were also studied. No frameshift mutations were observed in the TGFβRII, MSH3, and MSH6 genes. RER and a deletion mutation of BAT26 in MSH2 were present in one (1/ 23; 4%) gastric cancer. This tumor also carried a deletion mutation in the serine (AGC) repeat of the E2F4 gene. Mutation screening of the TP53, APC, and KRAS2 genes revealed that the synchronous cancers did not carry the same mutations. Our results suggested that genetic instability, such as insertion/ deletion mutations in simple nucleotide repeats, is not significantly associated with the development of multiple primary cancers of the esophagus and other organs, and that these synchronous cancers developed independently according to their different environmental factors. Genes Chromosomes Cancer 23:317–322, 1998.

Effect of Daikenchuto, a Traditional Japanese Herbal Medicine, after Total Gastrectomy for Gastric Cancer: A Multicenter, Randomized, Double-Blind, Placebo-Controlled, Phase II Trial

BACKGROUND Daikenchuto (DKT) has widely been used to improve abdominal symptoms by being expected to accelerate bowel motility. The purpose of this study is to examine the efficacy and safety of DKT for prevention of ileus and associated gastrointestinal symptoms after total gastrectomy. STUDY DESIGN Two hundred and forty-five gastric cancer patients who underwent total gastrectomy were enrolled. Patients received either DKT (15.0 g/d) or matching placebo from postoperative days 1 to 12. Primary end points were time to first flatus, time to first bowel movement (BM), and frequency of BM. Secondary end points included quality of life, C-reactive protein level, symptoms indicative of a severe gastrointestinal disorder, and incidence of postoperative ileus. RESULTS A total of 195 patients (DKT, n = 96; placebo, n = 99) were included in the per-protocol set analysis. There were no significant differences between the groups in terms of patient background characteristics. Median time to first BM was shorter in the DKT group than in the placebo group (94.7 hours vs 113.9 hours; p = 0.051). In patients with high medication adherence, median time to first BM was significantly shorter in the DKT group than in the placebo group (93.8 hours vs 115.1 hours; p = 0.014). Significantly fewer patients in the DKT group had ≥2 symptoms of gastrointestinal dysfunction than those in the placebo group on postoperative day 12 (p = 0.026). CONCLUSIONS Administration of DKT during the immediate postoperative period after total gastrectomy appears to promote early recovery of postoperative bowel function.

Minimally invasive surgical enucleation for esophageal leiomyoma: report of seven cases.

Benign esophageal tumor is a rare entity, with leiomyoma being the most common lesion. We present our experience with enucleation of esophageal leiomyomas using a minimally invasive approach. Between March 1998 and June 2008, seven patients with esophageal leiomyoma underwent right thoracosopic enucleation (n=4) or laparoscopic transhiatal enucleation (n=3). A Dor (n=2) or Toupet fundoplication (n=1) were added for laparoscopic procedure. The mean tumor size was 3.9 cm (range, 1.5-5.5 cm). Tumor locations were upper (n=2), middle (n=1), and lower (n=4) thirds of the esophagus. No major morbidities including postoperative leakage or mortalities occurred. At a mean follow-up period of 60.1 months (range, 14-260 months), no evidence of recurrences were observed. Thoracoscopic and laparoscopic transhiatal enucleation for esophageal leiomyomas is a safe and feasible procedure. The optimal approaches should be tailored based on the location and size of the tumor.

A compensatory role of NF-κB to p53 in response to 5-FU-based chemotherapy for gastric cancer cell lines.

Despite of remarkable improvement of postoperative 5-FU–based adjuvant chemotherapy, the relapse rate of gastric cancer patients who undergo curative resection followed by the adjuvant chemotherapy remains substantial. Therefore, it is important to identify prediction markers for the chemotherapeutic efficacy of 5-FU. We recently identified NF-κB as a candidate relapse prediction biomarker in gastric cancer. To evaluate the biological significance of NF-κB in the context of 5-FU–based chemotherapy, we analyzed the NF-κB-dependent biological response upon 5-FU treatment in gastric cancer cell lines. Seven genes induced by 5-FU treatment in an NF-κB-dependent manner were identified, five of which are known p53 targets. Knockdown of RELA, which encodes the p65 subunit of NF-κB, decreased both p53 and p53 target protein levels. In contrast, NF-κB was not affected by TP53 knockdown. We also demonstrated that cell lines bearing Pro/Pro homozygosity in codon72 of p53 exon4, which is important for NF-κB binding to p53, are more resistant to 5-FU than those with Arg/Arg homozygosity. We conclude that NF-κB plays an important role in the response to 5-FU treatment in gastric cancer cell lines, with a possible compensatory function of p53. These results suggest that NF-κB is a potential 5-FU-chemosensitivity prediction marker that may reflect 5-FU-induced stress-response pathways, including p53.