Kazuhiro Mizumoto

Randomized Phase III Study of Gemcitabine Plus S-1, S-1 Alone, or Gemcitabine Alone in Patients With Locally Advanced and Metastatic Pancreatic Cancer in Japan and Taiwan: GEST Study

PURPOSE The present phase III study was designed to investigate the noninferiority of S-1 alone and superiority of gemcitabine plus S-1 compared with gemcitabine alone with respect to overall survival. PATIENTS AND METHODS The participants were chemotherapy-naive patients with locally advanced or metastatic pancreatic cancer. Patients were randomly assigned to receive only gemcitabine (1,000 mg/m(2) on days 1, 8, and 15 of a 28-day cycle), only S-1 (80, 100, or 120 mg/d according to body-surface area on days 1 through 28 of a 42-day cycle), or gemcitabine plus S-1 (gemcitabine 1,000 mg/m(2) on days 1 and 8 plus S-1 60, 80, or 100 mg/d according to body-surface area on days 1 through 14 of a 21-day cycle). RESULTS In the total of 834 enrolled patients, median overall survival was 8.8 months in the gemcitabine group, 9.7 months in the S-1 group, and 10.1 months in the gemcitabine plus S-1 group. The noninferiority of S-1 to gemcitabine was demonstrated (hazard ratio, 0.96; 97.5% CI, 0.78 to 1.18; P < .001 for noninferiority), whereas the superiority of gemcitabine plus S-1 was not (hazard ratio, 0.88; 97.5% CI, 0.71 to 1.08; P = .15). All treatments were generally well tolerated, although hematologic and GI toxicities were more severe in the gemcitabine plus S-1 group than in the gemcitabine group. CONCLUSION Monotherapy with S-1 demonstrated noninferiority to gemcitabine in overall survival with good tolerability and presents a convenient oral alternative for locally advanced and metastatic pancreatic cancer.

Radiation to stromal fibroblasts increases invasiveness of pancreatic cancer cells through tumor-stromal interactions.

Radiotherapy represents a major treatment option for patients with pancreatic cancer, but recent evidence suggests that radiation can promote invasion and metastasis of cancer cells. Interactions between cancer cells and surrounding stromal cells may play an important role in aggressive tumor progression. In the present study, we investigated the invasive phenotype of pancreatic cancer cells in response to coculture with irradiated fibroblasts. Using in vitro invasion assay, we demonstrated that coculture with nonirradiated fibroblasts significantly increased the invasive ability of pancreatic cancer cells and, surprisingly, the increased invasiveness was further accelerated when they were cocultured with irradiated fibroblasts. The hepatocyte growth factor (HGF) secretion from fibroblasts remained unchanged after irradiation, whereas exposure of pancreatic cancer cells to supernatant from irradiated fibroblasts resulted in increased phosphorylation of c-Met (HGF receptor) and mitogen-activated protein kinase activity, possibly or partially via increased expression of c-Met. We also demonstrated that scattering of pancreatic cancer cells was accelerated by the supernatant from irradiated fibroblasts. The enhanced invasiveness of pancreatic cancer cells induced by coculture with irradiated fibroblasts was completely blocked by NK4, a specific antagonist of HGF. These data suggest that invasive potential of certain pancreatic cancer cells is enhanced by soluble mediator(s) released from irradiated fibroblasts possibly through up-regulation of c-Met expression/phosphorylation and mitogen-activated protein kinase activity in pancreatic cancer cells. Our present findings further support the potential use of NK4 during radiotherapy for patients with pancreatic cancer.

MicroRNA-21 modulates biological functions of pancreatic cancer cells including their proliferation, invasion, and chemoresistance.

Due to the poor prognosis of pancreatic cancer, novel diagnostic modalities for early diagnosis and new therapeutic strategy are urgently needed. Recently, microRNA-21 (miR-21) was reported to be strongly overexpressed in pancreatic cancer as well as in other solid cancers. We investigated the functional roles of miR-21, which have not been fully elucidated in pancreatic cancer. miR-21 expression was assessed in pancreatic cancer cell lines (14 cancer cell lines, primary cultures of normal pancreatic epithelial cells and fibroblasts, and a human normal pancreatic ductal epithelial cell line) and pancreatic tissue samples (25 cancer tissues and 25 normal tissues) by quantitative real-time reverse transcription-PCR amplification. Moreover, we investigated the proliferation, invasion, and chemoresistance of pancreatic cancer cells transfected with miR-21 precursor or inhibitor. miR-21 was markedly overexpressed in pancreatic cancer cells compared with nonmalignant cells, and miR-21 in cancer tissues was much higher than in nonmalignant tissues. The cancer cells transfected with the miR-21 precursor showed significantly increased proliferation, Matrigel invasion, and chemoresistance for gemcitabine compared with the control cells. In contrast, inhibition of miR-21 decreased proliferation, Matrigel invasion, and chemoresistance for gemcitabine. Moreover, miR-21 positively correlated with the mRNA expression of invasion-related genes, matrix metalloproteinase-2 and -9, and vascular endothelial growth factor. These data suggest that miR-21 expression is increased in pancreatic cancer cells and that miR-21 contributes to the cell proliferation, invasion, and chemoresistance of pancreatic cancer.[Mol Cancer Ther 2009;8(5):1067–74]

MicroRNA, hsa-miR-200c, is an independent prognostic factor in pancreatic cancer and its upregulation inhibits pancreatic cancer invasion but increases cell proliferation

BackgroundRecently, the microRNA-200 family was reported to affect cancer biology by regulating epithelial to mesenchymal transition (EMT). Especially, the expression of miR-200c has been shown to be associated with upregulating the expression of E-cadherin, a gene known to be involved in pancreatic cancer behavior. However, the significance of miR-200c in pancreatic cancer is unknown.MethodsIn the present study, we investigated the relationship between E-cadherin and miR-200c expression in a panel of 14 pancreatic cancer cell lines and in macro-dissected formalin-fixed paraffin-embedded (FFPE) tissue samples obtained from 99 patients who underwent pancreatectomy for pancreatic cancer. We also investigated the effects of miR-200c on the proliferation and invasion of pancreatic cancer cells.ResultsWe found that patients with high levels of miR-200c expression had significantly better survival rates than those with low levels of miR-200c expression. We also found a remarkably strong correlation between the levels of miR-200c and E-cadherin expression.ConclusionsThese data indicate that miR-200c may play a role in the pancreatic cancer biology and may be a novel marker for the prognosis of pancreatic cancer.

The Role of S100A6 in Pancreatic Cancer Development and Its Clinical Implication as a Diagnostic Marker and Therapeutic Target

Recent microarray analyses showed that the S100 family contains members that are candidate diagnostic markers or therapeutic targets. In the present study, to evaluate the involvement of S100A6 in pancreatic cancer and its clinical usefulness for diagnosis, we examined S100A6 mRNA expression in pancreatic tissues and pancreatic juice from patients with different pancreatic diseases. To investigate the role of S100A6 in carcinogenesis of pancreatic cancer and the potential of S100A6 as a diagnostic marker for early detection of pancreatic cancer, we did immunohistochemistry and microdissection-based mRNA analysis of pancreatic normal ducts, pancreatic intraepithelial neoplasias, and invasive ductal carcinomas. We also used in vitro experiments and microarray analysis with RNA interference to evaluate the functional role of S100A6 and its potential as a therapeutic target for pancreatic cancer. S100A6 mRNA levels were significantly higher in carcinoma specimens than in nonneoplastic tissues. In pancreatic juice, there was a significant difference in S100A6 expression between patients with carcinoma and those with nonneoplastic disease. Receiver operating characteristic curves revealed that S100A6 might be a useful marker for diagnosis of pancreatic cancer. Immunohistochemistry and microdissection-based analysis showed differential expression of S100A6 among normal ducts, pancreatic intraepithelial neoplasias, and invasive ductal carcinomas. In vitro data showed that inhibition of S100A6 decreased proliferation and invasiveness of cancer cells, and these findings were supported by microarray data. Our present results suggest that quantitation of S100A6 mRNA is a promising tool for diagnosis of pancreatic cancer, and that S100A6 may be a promising therapeutic target for pancreatic cancer.

Laparoscopically assisted distal gastrectomy for early gastric cancer: is it superior to open surgery?

BackgroundThe purpose of this study was to compare clinical outcomes between laparoscopically assisted and open distal gastrectomy for early gastric cancer.MethodsThe records of 21 patients who underwent laparoscopically assisted distal gastrectomy (LG) for preoperative diagnosis of intramucosal gastric carcinoma between January 1996 and August 1998 were reviewed and compared with those of 31 open distal gastrectomy patients during the same period.ResultsAge, gender, and size and histologic differentiation of the lesions were matched. Those located at the body of the stomach (p=0.011) and those macroscopically depressed (p=0.049) were subjected more frequently to open surgery. Laparoscopically assisted gastrectomy required significantly longer operative time (p<0.001) with less extensive lymph node dissection (p<0.001). However, time to start of walking (p=0.032), time to flatus (p=0.002), duration of postoperative fever (p=0.027), and postoperative hospital stay (p=0.001) were significantly shorter in the LG group, and this group had a lower white blood cell count on the first postoperative day (p=0.010). Blood loss and time to oral intake were comparable between the groups. Complications included one conversion to open surgery, one leakage, and one stenosis in the LG group, and two leakages and an atelectasis in the OG group.ConclusionsAlthough LG requires longer surgical time, this retrospective study suggests that it is superior to open surgery in terms of faster postoperative recoveries, shorter hospital stays, and cosmetic outcomes.

Cyst size indicates malignant transformation in branch duct intraductal papillary mucinous neoplasm of the pancreas without mural nodules.

Objectives: In branch duct intraductal papillary mucinous neoplasm (IPMN) of the pancreas, the importance of the cyst size to predict malignancy is still controversial. Our aim was to elucidate the malignant potential of branch duct IPMN without mural nodules (flat branch duct IPMN). Methods: Seventy-three patients with flat branch duct IPMNs were studied in our institution. Results: There were 6 malignant IPMNs in this series, all of which were 30 mm or more in size, whereas there was no malignancy in IPMNs of less than 30 mm. Statistically significant predictors of malignancy were atypical cytological condition and main pancreatic duct (MPD) diameter of 5 mm or more. The cyst size of 30 mm or more tended to be associated with malignancy. The frequency of malignancy in flat branch duct IPMNs with the size of 30 mm or more and MPD diameter of less than 5 mm was 3.6%, whereas there were 5 malignant cases (26.3%) in flat branch duct IPMNs with the size of 30 mm or more and MPD diameter of 5 mm or more. Conclusions: We conclude that the size criteria (≥30 mm) to predict malignancy proposed in the international consensus guidelines is appropriate and resection or meticulous follow-up using cytological examination and MPD dilatation is needed in patients with flat branch duct IPMNs.

Laparoscopic pancreatic surgery: Current indications and surgical results

Background: Although minimally invasive surgery has achieved worldwide acceptance in various fields, laparoscopic surgery for pancreatic diseases has been reported only rarely. The purpose of this study was to evaluate the outcomes and feasibility of laparoscopic pancreatic surgery. Methods: Fifteen patients, comprising eight men and seven women with an average age of 54 years, underwent laparoscopic pancreatic surgery. Distal pancreatectomy was indicated for solid tumors (n = 4), cystic lesions (n = 3), and chronic pancreatitis (n = 2). Cystogastrostomy was performed for pseudocysts (n = 4) and enucleation for insulinomas (n = 2). The lesions varied in size from 1 to 9 cm (2.9 ± 2.4 cm) and were located in the pancreatic head (n = 2), body (n = 3), or tail (n = 10). For distal pancreatectomy, the splenic artery was divided and the parenchyma was transected with a linear stapler. Laparoscopic ultrasonography was used to determine the distance between the tumor and the main pancreatic duct for enucleation as well as to localize the lesion for distal pancreatectomy. Cystogastrostomy, 4.5 cm in length, was also performed with the linear stapler through the window of the lesser omentum. Results: Mean operation time was 249 ± 70 min (293 ± 58 min in distal pancreatectomy, 185 ± 14 min in enucleation, 204 ± 50 min in cystogastrostomy), and mean blood loss was 138 ± 184 g (213 ± 227 g, 75 ± 35 g, 38 ± 48 g, respectively). Two distal pancreatectomies (13%) were converted to open surgery due to severe peripancreatic inflammation. There was no related mortality, but there were two cases (15%) of pancreatic fistula, one in a distal pancreatectomy case and the other in an enucleation case, and both were treated conservatively. Conclusions: Laparoscopic pancreatic surgery is safe and feasible for patients with benign tumors and cystic lesions.

Correlation between centrosome abnormalities and chromosomal instability in human pancreatic cancer cells

Chromosomal instability, characterized by abnormal numbers or structures of chromosomes, is a common feature of human cancers, but the mechanisms behind these changes are still unclear. Since centrosomes play a pivotal role in balanced chromosomal segregation during mitosis, we attempted to investigate the association between centrosome abnormalities and chromosomal instability in a large number of human pancreatic cancer cell lines. Immunofluorescence microscopy revealed centrosomes that were highly atypical with respect to their size, shape, and number in most cell lines. These abnormal centrosomes contributed to the assembly of multipolar spindles, resulting in defective mitosis and chromosome mis-segregation. Interestingly, a high frequency of centrosome defects inversely correlated with the growth rate of cells in culture. Fluorescence in situ hybridization revealed a dramatic variation of chromosome numbers in cell lines with the defective centrosome phenotype. Furthermore, a significant positive correlation existed between the level of centrosome defects and the level of chromosomal imbalances. These results indicate that centrosome abnormalities can lead to spindle disorganization and chromosome segregation errors, which may drive the accumulation of chromosomal alterations. Thus, defects in centrosome function may be an underlying cause of genetic instability in human pancreatic cancers.

MicroRNA-10b is overexpressed in pancreatic cancer, promotes its invasiveness, and correlates with a poor prognosis

BACKGROUND MicroRNAs (miRNAs) have been gaining attention as new, key molecules that contribute to carcinogenesis. In pancreatic cancer, previous profiling analyses of miRNA expression have shown that several miRNAs are differently expressed in normal and cancerous tissues. Several pancreatic cancer-specific miRNAs differed, however, in each analysis. METHODS We investigated the miRNA expression profiles of the pancreatic cancer cell lines CAPAN-1 and CFPAC1 and an immortalized human normal pancreatic ductal epithelial cell line (HPDE) using a high-throughput, TaqMan, qRT-PCR array analysis. We also analyzed the expression levels of this miRNA in microdissected (n = 15) and formalin-fixed, paraffin-embedded (FFPE) (n = 115) samples from pancreatic cancers by quantitative RT-PCR. Finally, we investigated the effects of this miRNA on the invasiveness of pancreatic cancer cells. RESULTS Based on the microarray analysis, miR-372, miR-146a, miR-204, miR-10a, and miR-10b showed particularly large differences (>10-fold changes) between both pancreatic cell lines and HPDE cells. Thirteen of the 15 pancreatic cancer cell lines showed 2.1- to 36.4-fold (median, 15.3-fold) greater levels of miR-10b than HPDE cells. Microdissection analysis revealed that miR-10b exhibited greater expression levels in pancreatic cancer cells (n = 5) than in normal pancreatic ductal cells (n = 10) (P < .020). Analysis of FFPE samples showed that high miR-10b expression was associated with a lesser overall survival (P = .014). Furthermore, miR-10b correlated with the invasiveness of pancreatic cancer cells (P < .01). CONCLUSION miR-10b is overexpressed in pancreatic cancer and may be involved in the invasiveness in pancreatic cancer cells, thereby leading to a poor prognosis.