Takumi Irie

Identification of Pancreatic Cancer Stem Cells and Selective Toxicity of Chemotherapeutic Agents

BACKGROUND & AIMS Identification and purification of cancer stem cells (CSCs) could lead to new therapeutic targets, but their heterogeneous expansion is an obstacle to their study. We investigated whether it is possible to monitor pancreatic CSCs in real time, based on their intrinsic low level of proteasome activity. METHODS We engineered human pancreatic adenocarcinoma cells (PANC1, MIAPaCa2, BxPC3, and KLM1) to express a green fluorescent molecule fused to the degron of ornithine decarboxylase (Gdeg) from a retroviral vector; the fluorescent Gdeg accumulates in CSCs as a result of low activity of the 26S proteasome. Cells with high and low levels of fluorescence (Gdeg(high) and Gdeg(low)) were isolated by flow cytometry; tumor growth was analyzed in immunocompromised mice. We performed a screen for agents that were specifically toxic to pancreatic CSCs, in a synthetic lethal manner. RESULTS Gdeg(high) cells, but not Gdeg(low) cells, formed spheres and underwent asymmetric division-features of CSCs. Injection of as few as 10 Gdeg(high) cells led to tumor formation in mice. Gemcitabine was toxic to cultured Gdeg(low) cells, whereas Gdeg(high) cells were resistant. We observed that quercetin was toxic to Gdeg(high) cells in culture and in pre-established tumors grown from these cells in mice. Nuclear accumulation of β-catenin was detected in Gdeg(high), but not Gdeg(low), and lost after exposure to quercetin. CONCLUSIONS We used a fluorescence marker system for level of proteasome activity to identify pancreatic cancer cells with features of cancer stem cells. We identified quercetin as a compound that is specifically toxic to pancreatic CSCs.

Surgical Strategies for Hepatocellular Carcinoma with Special Reference to Anatomical Hepatic Resection and Intraoperative Contrast-Enhanced Ultrasonography

Here we described our strategies to attain a better prognosis for hepatocellular carcinoma (HCC) patients by surgery. Among a variety of attempts conducted to date, we focused on anatomical resection and intraoperative contrast-enhanced ultrasonography. There are still controversies with respect to the significance of anatomical resection. We analyzed the significance of this surgical procedure in 207 patients without macrovascular invasion. These patients underwent either anatomical resection or non-anatomical resection. We found that the patients with anatomical resection had higher recurrence-free survival rate than those with non-anatomical resection. Univariable analysis showed that liver damage, the serum level of α-fetoprotein, tumor number, surgical margin, and type of surgery (anatomical or non-anatomical resection) were significant predictive factors for intrahepatic recurrence. Multivariable analysis revealed that multiple tumors, α-fetoprotein, and non-anatomical resection were independent risk factors for recurrence. We conclude that anatomical resection is a recommendable surgical procedure in patients without macrovascular invasion. A recent innovation is the development of contrast-enhanced ultrasonography. Then we have applied this to liver surgery intraoperatively. We confirm that vascular images contribute to a precise diagnosis and the detection of small portal tumor thrombi, and that Kupffer images are useful to discover the minute tumors. In addition, by clarifying the relationship between tumors and the vascular architecture, real-time 3-dimensional images using Kupffer imaging are a promising guide during the surgical procedures, although further development is needed.

Gene expression signature of the gross morphology in hepatocellular carcinoma.

Objective:To evaluate the gene expression signature of hepatocellular carcinoma (HCC) in relation to the gross morphology. Background:Eggels nodular type of HCC is morphologically subclassified into the single nodular (SN) type, the single nodular type with extranodular growth (SNEG), and the confluent multinodular (CM) type, but their biomolecular differences remain unclear. Methods:The clinicopathological characteristics and genome-wide gene expressions were analyzed in 275 patients with nodular-type HCC (124 SN-type, 91 SNEG-type, and 60 CM-type) who received curative hepatectomy. Results:Significantly poor prognosis was recognized in CM types in overall survival (P = 0.0020) and recurrence-free survival (P = 0.0066). Analysis of the genome-wide expression patterns revealed significant difference of CM-type HCC from either SN- or SNEG-type HCC. In particular, a stem cell marker EpCAM was dominantly expressed in CM-type HCC. Immunohistochemical studies confirmed the specific expression of EpCAM in HCC cancer cells of CM type. In multivariate analysis, the gross morphology of CM type was significantly associated with EpCAM expression (P = 0.0092), &agr;-fetoprotein (P = 0.0424), “lens culinaris agglutinin-reactive fraction of &agr;-fetoprotein” level (P = 0.0288), and the portal vein invasion (P = 0.0150). Furthermore, EpCAM was predictive for poor prognosis in overall and recurrence-free survivals of patients with CM-type HCC (P = 0.0082 and P = 0.0043, respectively). Conclusion:Our studies suggest that the distinct signature of gene expression is closely related to morphological progression in HCC. Especially, EpCAM might play a critical role in the aggressiveness of CM-type HCC.

Visualization of stem cell features in human hepatocellular carcinoma reveals in vivo significance of tumor‐host interaction and clinical course

Hepatocellular carcinoma (HCC) is one of the most aggressive malignancies because of recurrence and/or metastasis even after curative resection. Emerging evidence suggests that tumor metastasis and recurrence might be driven by a small subpopulation of stemness cells, so‐called cancer stem cells (CSCs). Previous investigations have revealed that glioma and breast CSCs exhibit intrinsically low proteasome activity and that breast CSCs also reportedly contain a lower reactive oxygen species (ROS) level than corresponding nontumorigenic cells. Here we visualized two stem cell features, low proteasome activity and low intracellular ROS, in HCC cells using two‐color fluorescence activated cell sorting to isolate cells with stem cell features. These cells were then analyzed for their division behavior in normoxia and hypoxia, expression of stem cell markers, tumorigenicity, metastatic potential, specific gene expression signatures, and their clinical implications. A visualized small subpopulation of HCC cells demonstrated asymmetric divisions. Their remarkable tumorigenicity in nonobese diabetic/severe combined immunodeficient mice suggested the cancer initiation potential of these HCC CSCs. Comprehensive gene expression analysis revealed that chemokine‐related genes were up‐regulated in the CSCs subpopulation. Our identified HCC CSCs facilitated the migration of macrophages in vitro and demonstrated metastatic potential by way of recruitment of macrophages in vivo. In patients who undergo curative operation for HCC, the CSC‐specific gene signature in the liver microenvironment significantly correlates with recurrence. Conclusion: Based on these findings, the stem cell feature monitoring system proposed here is a promising tool to analyze the in vivo significance of CSC microenvironments in human HCCs. (HEPATOLOGY 2013;)

Resection of a cancer developing in the remnant pancreas after a pancreaticoduodenectomy for pancreas head cancer

We report a rare case of a curative resection performed on a carcinoma developing in the remnant pancreas at 3 years 7 months after a pancreaticoduodenectomy for pancreatic cancer. A 63-year-old man underwent a pancreaticoduodenectomy for pancreatic cancer on November 1999. Because the celiac trunk was occluded by atherosclerosis, an aortohepatic bypass with a saphenous vein graft was performed simultaneously. In May 2003, tumor marker levels increased, and a tumor was detected in the remnant pancreas on computed tomography. There were no findings such as invasion into the surrounding tissue or distant metastasis, and therefore we removed the remnant pancreas in July 2003. Histopathologically, the tumor consisted of a well-differentiated tubular adenocarcinoma and was limited to the pancreas. Moreover, the anastomotic site of the pancreaticojejunostomy was negative for cancer, and some foci of papillary hyperplasia and goblet cell metaplasia of the pancreatic ductal epithelium, which was thought to be the precursor of the pancreatic cancer, were seen. These findings suggested that the tumor was a second primary cancer developing in the remnant pancreas. This case provided suggestive evidence for the development of pancreatic cancer, and the surgical procedure for a pancreaticoduodenectomy with occlusion of the celiac trunk is discussed.

Oxidative stress pathways in noncancerous human liver tissue to predict hepatocellular carcinoma recurrence: A prospective, multicenter study†‡

The prediction of cancer recurrence holds the key to improvement of the postoperative prognosis of patients. In this study, the recurrence of early‐stage hepatocellular carcinoma (HCC) after curative hepatectomy was analyzed by the genome‐wide gene‐expression profiling on cancer tissue and the noncancerous liver tissue. Using the training set of 78 cases, the cytochrome P450 1A2 (CYP1A2) gene in noncancerous liver tissue was identified as the predictive candidate for postoperative recurrence (hazard ratio [HR], 0.447; 95% confidence interval [CI], 0.249‐0.808; P = 0.010). Multivariate analysis revealed the statistically significant advantage of CYP1A2 down‐regulation to predict recurrence (odds ratio, 0.534; 95% CI, 0.276‐0.916; P = 0.036), and the expression of CYP1A2 protein was confirmed immunohistochemically. An independently multi‐institutional cohort of 211 patients, using tissue microarrays, validated that loss of expression of CYP1A2 in noncancerous liver tissue as the only predictive factor of recurrence after curative hepatectomy for early‐stage HCC (HR, 0.480; 95% CI, 0.256‐0.902; P = 0.038). Gene set‐enrichment analysis revealed close association of CYP1A2 down‐regulation with oxidative stress pathways in liver tissue (P < 0.001, false discovery rate [FDR] = 0.042; P = 0.006, FDR = 0.035). Our results indicate these pathways as the molecular targets to prevent recurrence, as well as the potential prediction of the super high‐risk population of HCC using liver tissue. (HEPATOLOGY 2011;54:1273–1281)

Liver metastasis from rectal cancer with prominent intrabile duct growth.

Intrabiliary growth of liver metastases from colorectal cancer has rarely been studied. A surgically resected case of a metastatic liver tumor with prominent intrabiliary growth derived  from  rectal  cancer  is  reported.  The  patient  was  a 62‐year‐old man who had received a low anterior resection for rectal cancer in March 2000. He was re‐admitted due to obstructive jaundice in January 2003, and was diagnosed with hepatic malignancy in segment II of the liver with an intrabiliary tumor extending from the intrahepatic bile duct of segment II to the common hepatic duct. He underwent a left hepatectomy, a partial resection of segment VI, and an extrahepatic bile duct resection with reconstruction of the biliary tract. In the resected specimen, there were whitish tumors of 3 cm and 1.5 cm in diameter in segments II and VI, respectively, and an intrabiliary tumor originating from the main tumor in segment II extended to the common hepatic duct. Both the liver tumors and the intrabiliary tumor consisted of a well‐ to moderately differentiated adenocarcinoma, which showed the same histological features as the rectal cancer. The immunohistochemical findings strongly supported that these tumors, including the intrabiliary growth, were liver metastasis from the rectal cancer. The intrabiliary invasion and growth of metastatic liver tumors has generally been overlooked, notwithstanding their frequently observed biological behavior. The present case is informative, and further investigation into this type of metastatic liver tumor may be warranted.

Contrast‐enhanced intraoperative ultrasonography for vascular imaging of hepatocellular carcinoma: Clinical and biological significance

Abnormal tumor vascularity is one of the typical features of hepatocellular carcinoma (HCC). In this study, the significance of contrast‐enhanced intraoperative ultrasonography (CEIOUS) images of HCC vasculature was evaluated by clinicopathological and gene expression analyses. We enrolled 82 patients who underwent curative hepatic resection for HCC with CEIOUS. Clinicopathological and gene expression analyses were performed according to CEIOUS vasculature patterns. CEIOUS images of HCC vasculatures were classified as reticular HCC or thunderbolt HCC. Thunderbolt HCC was significantly correlated with higher alpha‐fetoprotein levels, tumor size, histological differentiation, portal vein invasion, and tumor‐node‐metastasis stage, and these patients demonstrated a significantly poorer prognosis for both recurrence‐free survival (P = 0.0193) and overall survival (P = 0.0362) compared with patients who had reticular HCC. Gene expression analysis revealed that a rereplication inhibitor geminin was significantly overexpressed in thunderbolt HCCs (P = 0.00326). In vitro knockdown of geminin gene reduced significantly the proliferation of human HCC cells. Immunohistochemical analysis confirmed overexpression of geminin protein in thunderbolt HCC (P < 0.0001). Multivariate analysis revealed geminin expression to be an independent factor in predicting poor survival in HCC patients (P = 0.0170). Conclusion: CEIOUS vascular patterns were distinctly identifiable by gene expression profiling associated with cellular proliferation of HCC and were significantly related to HCC progression and poor prognosis. These findings might be clinically useful as a determinant factor in the postoperative treatment of HCC. (HEPATOLOGY 2013)

Mixed adenoneuroendocrine carcinoma of the colon progressed rapidly after hepatic rupture: report of a case.

The rupture of a metastatic mixed adenoneuroendocrine carcinoma (MANEC) has not been previously reported, although the neuroendocrine cell carcinoma is often associated with a high incidence of hepatic metastases. The patient was a 39-year-old male who presented with upper abdominal pain over 3 months. Computed tomography showed multiple tumors in both hepatic lobes, while lower gastrointestinal endoscopy revealed a tumor in the transverse colon. Histopathologic examination of the tumor revealed it to be a neuroendocrine cell carcinoma. After the resection of the primary tumor, hepatic metastases rapidly increased, and one of them in the left lateral segment was ruptured with significant hemorrhage. The rupture led us to undertake the emergency operation to stop the bleeding. Histology showed a high-grade large-cell neuroendocrine carcinoma associated with moderately differentiated tubular adenocarcinoma. The Ki-67 labeling index was 80% (G3). The diagnosis was mixed adenoneuroendocrine carcinoma according to the 2010 World Health Organization guidelines. Hepatic arterial infusion chemotherapy, systemic chemotherapy, and transcatheter arterial chemoembolization did not decrease the tumor progress, and the patient died on postoperative day 110. Reporting this highly malignant case, I hope all doctors can be interested in MANEC.

Anatomic resection reduces the recurrence of solitary hepatocellular carcinoma ≤5 cm without macrovascular invasion

BACKGROUND In patients with solitary hepatocellular carcinoma ≤5 cm without macrovascular invasion, it is unknown whether the initial anatomic resection improves the long-term survival. METHODS Among 545 initial hepatectomies for hepatocellular carcinoma between 2000 and 2012, the 233 patients with the aforementioned criteria of hepatocellular carcinoma were enrolled. RESULTS The mean observation time was 1,125 days. Disease-free 5-year survival rates with and without anatomic resection were 46% and 23%, respectively (P = .009). Multivariate analyses for disease-free survival rates revealed the risk factors to be α-fetoprotein (odds ratio, 1.6; P = .028) and anatomic resection (odds ratio, .7; P = .048), while increased Child-Pugh score (>5) was the only independent risk factor for overall survival (odds ratio, 1.8; P = .043). The 5-year overall survival rates with and without Child-Pugh score 5 were 74% and 40%, respectively (P < .0001, log-rank test). CONCLUSIONS Initial anatomic resection for small solitary hepatocellular carcinoma without macrovascular invasion improved disease-free survival rates remarkably.