Akira Chikamoto

Pancreatoduodenectomy using a no-touch isolation technique.

BACKGROUND Pancreatoduodenectomy is the only effective treatment for cancers of the periampullary region. Because surgeons usually grasp tumors during pancreatoduodenectomy, this procedure may increase the risk of squeezing and shedding the cancer cells into the portal vein, retroperitoneum, and/or peritoneal cavity. In an effort to overcome these problems, we have developed a surgical technique for no-touch pancreatoduodenectomy. METHODS From March 2005 through May 2008, 42 patients have been operated on following this technique. Resected margins were microscopically analyzed. RESULTS We describe a technique for pancreatoduodenectomy using a no-touch isolation technique. We resect cancers with wrapping them within Gerotas fascia and transect the retroperitoneal margin along the right surface of the superior mesenteric artery and abdominal aorta without grasping tumors. CONCLUSIONS No-touch pancreatoduodenectomy has many potential advantages that merit further investigation in future randomized controlled trials.

An Imbalance in TAZ and YAP Expression in Hepatocellular Carcinoma Confers Cancer Stem Cell–like Behaviors Contributing to Disease Progression

Transcriptional coactivator with PDZ-binding motif (TAZ) and yes-associated protein (YAP) are equivalently placed downstream effectors of the Hippo pathway with oncogenic roles in human cancers. However, the expression profiles of TAZ/YAP differ depending on the cancer cell type, suggesting that these proteins have different roles during cancer progression, yet no studies have examined the biologic significance of the balance between TAZ and YAP expression levels. Here we examined the functional roles of TAZ/YAP in hepatocellular carcinoma progression. We found that TAZ, but not YAP, was predominantly expressed in HCC. TAZ knockdown under normal conditions attenuated cell growth in HCC cells; however, TAZ knockdown combined with 5-fluorouracil treatment significantly increased chemoresistance compared with control cells. Notably, TAZ knockdown induced compensatory YAP expression and was accompanied by upregulation of CD90, a HCC-specific cancer stem cell marker. Continuous treatment with 5-fluorouracil also induced YAP expression and promoted tumor formation in vivo. Conversely, double knockdown of TAZ/YAP reduced chemoresistance and tumorigenicity. Moreover, YAP knockdown aggravated HCC cell growth to a greater degree than TAZ knockdown, and YAP overexpression was strongly associated with poor prognoses in patients with HCC. Collectively, these studies demonstrate that TAZ and YAP exhibit different functional roles in cancer progression, and a shift to predominant YAP expression upon TAZ depletion conferred cancer stem cell-like properties including chemoresistance and tumorigenicity in HCC. Therefore, targeting of both TAZ/YAP will be required for a complete antitumor response in HCC.

Comparison between hepatic resection and radiofrequency ablation as first-line treatment for solitary small-sized hepatocellular carcinoma of 3 cm or less.

It is a matter of debate whether hepatic resection (HR) or radiofrequency ablation (RFA) should be preferred for the treatment of patients with hepatocellular carcinoma (HCC). The aim of this study is to compare the long‐term outcome between HR and RFA in patients with solitary small‐sized HCC.

Carcinogenesis of Intraductal Papillary Mucinous Neoplasm of the Pancreas: Loss of MicroRNA-101 Promotes Overexpression of Histone Methyltransferase EZH2

BackgroundThe mechanisms of IPMN carcinogenesis are as yet unclear. This study aimed to determine whether expression of EZH2 promotes neoplastic progression of IPMN and PDCA, and to elucidate regulation of EZH2 expression by miR-101.MethodsEZH2 mRNA and protein expression were investigated in 8 human pancreatic cancer cell lines by PCR and western blotting. Pre-miR-101 and anti-miR-101 were transfected into pancreatic cancer cells to elucidate EZH2 regulation by miR-101. To evaluate whether EZH2 modulates malignant progression of IPMN, EZH2 expression in IPMN was examined by immunohistochemistry. Next, we collected malignant and benign cells from FFPE samples of IPMNs using laser capture microdissection and extracted the RNA. miR-101 expression in IPMN was assessed using real-time PCR.ResultsAll pancreatic cancer cell lines expressed EZH2 mRNA and protein. The induction of miR-101 by transfection of pre-miR-101 in MIA PaCa-2 was closely related to a reduction in EZH2 protein production compared with control, whereas there was little difference in the expression of EZH2 mRNA. Anti-miR-101 transfected pancreatic cancer cells showed an increase in EZH2 protein, while the level of EZH2 mRNA was not elevated. Immunohistochemistry revealed that the expression of EZH2 was significantly higher in malignant than benign IPMN. Expression of miR-101 was significantly lower in malignant IPMN than benign IPMN.ConclusionsMiR-101 targets EZH2 at the posttranscriptional level, and loss of miR-101 could be a trigger for the adenomacarcinoma sequence of IPMN by upregulation of EZH2. This study suggests miR-101–EZH2 blockade as a potential therapeutic target in IPMN carcinogenesis.

miR-9-3p plays a tumour-suppressor role by targeting TAZ (WWTR1) in hepatocellular carcinoma cells.

Background:The inactivation of the Hippo pathway lead to TAZ (PDZ-binding motif)/YAP (yes-associated protein) overexpression, and is associated with worse prognostic outcomes in various cancers including hepatocellular carcinoma (HCC). Although there are several reports of microRNA (miR) targeting for YAP, miR targeting for TAZ remains unclear. The aim of this study is to identify the miR targeting TAZ expression in HCC.Methods:MicroRNA expression was analysed using the Human miFinder 384HC miScript miR PCR array, and was compared between low and high TAZ expression cell lines. Then, we extracted miR-9-3p as a tumour-suppressor miR targeting TAZ. We examined the functional role of miR-9-3p using miR-9-3p mimic and inhibitor in HCC cell lines).Results:In HCC cell lines and HCC clinical samples, there was the inverse correlation between miR-9-3p and TAZ expressions. TAZ expression was induced by treatment of miR-9-3p inhibitor and was downregulated by treatment of miR-9-3p mimic. Treatment of miR-9-3p mimic inhibited cell proliferative ability with downregulated phosphorylations of Erk1/2, AKT, and β-catenin in HLF. Inversely, treatment of miR-9-3p inhibitor accelerated cell growth compared with control in HuH1.Conclusions:MicroRNA-9-3p was identified as the tumour-suppressor miR targetting TAZ expression in HCC cells.

CD44s signals the acquisition of the mesenchymal phenotype required for anchorage-independent cell survival in hepatocellular carcinoma

Background:Circulating tumour cells (CTCs) have an important role in metastatic processes, but details of their basic characteristics remain elusive. We hypothesised that CD44-expressing CTCs show a mesenchymal phenotype and high potential for survival in hepatocellular carcinoma (HCC).Methods:Circulating CD44+CD90+ cells, previously shown to be tumour-initiating cells, were sorted from human blood and their genetic characteristics were compared with those of tumour cells from primary tissues. The mechanism underlying the high survival potential of CD44-expressing cells in the circulatory system was investigated in vitro.Results:CD44+CD90+ cells in the blood acquired epithelial–mesenchymal transition, and CD44 expression remarkably increased from the tissue to the blood. In Li7 and HLE cells, the CD44high population showed higher anoikis resistance and sphere-forming ability than did the CD44low population. This difference was found to be attributed to the upregulation of Twist1 and Akt signal in the CD44high population. Twist1 knockdown showed remarkable reduction in anoikis resistance, sphere formation, and Akt signal in HLE cells. In addition, mesenchymal markers and CD44s expression were downregulated in the Twist1 knockdown.Conclusions:CD44s symbolises the acquisition of a mesenchymal phenotype regulating anchorage-independent capacity. CD44s-expressing tumour cells in peripheral blood are clinically important therapeutic targets in HCC.

Liver Hanging Maneuver Decreases Blood Loss and Operative Time in a Right-Side Hepatectomy

BACKGROUND/AIMS To clarify the clinical benefits of the maneuver in right-side hepatectomy. METHODOLOGY Eighty-one patients with liver tumor (54 hepatocellular carcinoma, 17 metastatic liver tumor and 10 other tumors) treated with a right-side hepatectomy were prospectively analyzed. The patients were divided into the following three groups: a conventional approach (group A, n=21); liver dissection under the hanging maneuver after liver mobilization (group B, n=19) and liver dissection under the hanging maneuver prior to liver mobilization (group C, n=41). RESULTS The liver hanging maneuver was safely performed in all the patients in groups B and C. Tumor size had a significantly positive correlation with the amount of intraoperative blood loss (R=0.52, p<0.05) in group A only. The patients in groups B and C had a significantly lower intraoperative use of blood loss (both p<0.01), operation time (p<0.05 and p<0.01) and the frequency of blood product (both p<0.05), in comparison to group A, respectively. The postoperative morbidity and the mortality rates were similar in the three groups. CONCLUSIONS Liver hanging maneuver is a safe procedure, which can decrease intraoperative blood loss and administration of blood product in right-side hepatectomy.

Functional assessment versus conventional volumetric assessment in the prediction of operative outcomes after major hepatectomy

PURPOSE In this study we examined whether conventional future remnant liver volume (FR volume) or function (FR function) better predicted the operative outcome after major hepatectomy. METHODS Of 510 patients who underwent hepatectomy for various indications, 133 patients with major hepatectomy were enrolled in this study. FR volume and the corresponding FR function routinely were measured with a 99mTc-GSA scintigraphy single-proton emission computed tomography fusion system. FR function was defined as the future remnant liver uptake ratio of 99mTc-GSA per whole liver by single-proton emission computed tomography. FR volume or function in cases with insufficient FR volume or function required for major hepatectomy were defined as marginal. RESULTS Morbidity, liver dysfunction-related morbidity, and mortality after major hepatectomy occurred in 40 (30%), 10 (7.5%), and 8 (5.7%) patients, respectively. Thirty-two of the 133 patients were diagnosed as marginal using FR volume, but only 11 patients were diagnosed as marginal using FR function. These results indicated that 21 patients (16%) were switched to the safe group using functional assessment. Operative outcomes in patients with safe FR function (n = 122) were equivalent to those of patients with safe FR volume (n = 101), but patients with marginal FR function (n = 11) had substantially worse outcomes than patients with marginal FR volumes (n = 32). Logistic regression analysis identified marginal FR function, but not volume, as a risk factor for worse operative outcome after major hepatectomy. Portal vein embolization induced the substantially greater FR function compared with FR volume. Although liver volume equally corresponds to liver function under normal conditions, liver cirrhosis was greatly associated with the major discrepancy (more than 10%) in patients without portal vein embolization. CONCLUSION Functional assessment for future remnant liver identified patients who were eligible for curative hepatectomy despite a marginal status based on conventional volumetric assessment. Thus, marginal FR function is a better predictor of operative outcome after major hepatectomy than FR volume, especially in patients with nonhealthy liver.

External biliary drainage and liver regeneration after major hepatectomy

Bile acid signalling and farnesoid X receptor activation are assumed to be essential for liver regeneration. This study was designed to investigate the association between serum bile acid levels and extent of liver regeneration after major hepatectomy.

Cystine/glutamic acid transporter is a novel marker for predicting poor survival in patients with hepatocellular carcinoma

Cystine/glutamic acid transporter (xCT) plays a role in tumor progression by regulating the redox status in several types of cancers. To demonstrate the importance of xCT expression for predicting the prognosis of hepatocellular carcinoma (HCC), we analyzed xCT gene expression in 130 paired HCC and non-cancerous tissues. xCT protein expression was confirmed using 7 HCC cell lines and samples from human subjects. xCT mRNA expression was detected in 34 (26%) tumor tissues. Expression of xCT was higher in HCC tissues compared to the corresponding normal tissues according to quantitative reverse transcriptase-polymerase chain reaction findings (P<0.0001). Patients in the group presenting with xCT mRNA expression showed poorer overall and disease-free survival than did those with an absence of xCT mRNA (P=0.0130 and 0.0416, respectively). xCT mRNA expression proved to be an independent factor for poor prognosis in a multivariate analysis of overall survival (hazard ratio, 1.68; 95% CI, 1.03-2.92). We observed xCT protein expression in both the HCC cell lines and in human tissue samples. In conclusion, the findings of the present study suggest that xCT is useful as a predictive marker for patient prognosis and that it may be a novel therapeutic target for HCC.