Hisashi Tsurumi

Synergistic effects of RXRα and PPARγ ligands to inhibit growth in human colon cancer cells—phosphorylated RXRα is a critical target for colon cancer management

Background and aims: The activation of the peroxisome proliferator-activated receptor &ggr; (PPAR&ggr;) that forms heterodimers with retinoid X receptors (RXRs) elicits an antineoplastic effect on colorectal cancer. It was previously reported that the accumulation of the non-functional phosphorylated form of RXR&agr; (p-RXR&agr;) interfered with its signalling and promoted the growth of hepatoma cells. In this study the effects of p-RXR&agr; on the ability of RXR&agr; and PPAR&ggr; ligands to inhibit growth in colon cancer cells was examined. Methods: The effects of the combination of the PPAR&ggr; ligand ciglitazone and the RXR&agr; lignad 9-cis-retinoic acid (RA) on inhibition of cell growth in Caco2 human colon cancer cells which express high levels of p-RXR&agr; protein were examined Results: The RXR&agr; protein was phospholylated and also accumulated in human colon cancer tissue samples as well as human colon cancer cell lines. When the phosphorylation of RXR&agr; was inhibited by the MEK inhibitor PD98059 or by transfection with a point-mutated RXR&agr;, which mimicked the unphosphorylated form, the combination of 9-cisRA and ciglitazone synergistically inhibited the cell growth and induced apoptosis. The combined treatment with these agents also caused a decrease in the expression levels of both cyclo-oxygenase-2 (COX-2) and c-Jun proteins and mRNAs. Reporter assays indicated that this combination induced the transcriptional activity of the peroxisome proliferator-responsive element promoter and also inhibited that of the AP-1 promoter. Conclusion: A malfunction of RXR&agr; due to phosphorylation is associated with colorectal cancer. Therefore, the inhibition of phosphorylation of RXR&agr; and the activation of the RXR–PPAR&ggr; heterodimer by their respective ligands may be useful in the chemoprevention and/or treatment of colorectal cancer.

Prevalence of hepatitis B and C virus infection in haematological malignancies and liver injury following chemotherapy

Abstract:  The aim of this study was to determine the carrier rate of hepatitis virus in patients with haematological malignancies and the incidence of liver injury in these patients following chemotherapy. From January 1996 to September 2002, we studied 601 consecutive, unselected series of patients with haematological malignancies admitted in our hospital unit (Japan). They consisted of 246 cases of acute leukaemia, 218 non‐Hodgkins lymphoma (NHL), 13 adult T‐cell leukaemia, and 124 multiple myeloma. Of these 601 patients, 373 were men and 228 were women; their mean age was 61 yr, with a range from 18 to 89 yr. The prevalences of hepatitis B virus (HBV) and hepatitis C virus (HCV) were 7.3% and 10.1%, respectively, in NHL, both higher than those in acute leukaemia (1.7% and 2.9%, P < 0.005) and in general Japanese population (1.2% and 2.6%). The incidence of post‐chemotherapy liver injury in 25 HBV carriers (36.0%) was significantly higher than that in 539 non‐hepatitis virus carriers (12.6%, P = 0.003) and 37 HCV carriers (10.8%, P = 0.026). Liver injury in HBV carriers was more often present in patients who had been treated with steroids than in those without steroids (72.7% and 0%, P = 0.013). After lamivudine became available in our institution, the incidence of liver injury in HBV carriers was reduced from 53.3% to 10.0% (P = 0.041). The therapeutic strategy for haematological malignancies in hepatitis virus carriers should be further investigated.

(-)-Epigallocatechin gallate inhibits growth and activation of the VEGF/VEGFR axis in human colorectal cancer cells.

(-)-Epigallocatechin gallate (EGCG), the major constituent of green tea, inhibits the growth of colorectal cancer cells by inhibiting the activation of various types of receptor tyrosine kinases (RTKs). The RTK vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) axis induces tumor angiogenesis in colorectal cancer. This study examined the effects of EGCG on the activity of the VEGF/VEGFR axis and the expression of hypoxia-inducible factor (HIF)-1alpha, which promotes angiogenesis by elevating VEGF levels, in human colorectal cancer cells. Total and phosphorylated (i.e., activated) form (p-VEGFR-2) of VEGFR-2 proteins were overexpressed in a series of human colorectal cancer cell lines. Within 3h, EGCG caused a decrease in the expression of HIF-1alpha protein and VEGF, HIF-1alpha, insulin-like growth factor (IGF)-1, IGF-2, epidermal growth factor (EGF), and heregulin mRNAs in SW837 colorectal cancer cells, which express a constitutively activated VEGF/VEGFR axis. A decrease was also observed in the expression of VEGFR-2, p-VEGFR-2, p-IGF-1 receptor, p-ERK, and p-Akt proteins within 6h after EGCG treatment. Drinking EGCG significantly inhibited the growth of SW837 xenografts in nude mice, and this was associated with the inhibition of the expression and activation of VEGFR-2. The consumption of EGCG also inhibited activation of ERK and Akt, both of which are downstream signaling molecules of the VEGF/VEGFR axis, and reduced the expression of VEGF mRNA in xenografts. These findings suggest that EGCG may exert, at least in part, growth-inhibitory effects on colorectal cancer cells by inhibiting the activation of the VEGF/VEGFR axis through suppressing the expression of HIF-1alpha and several major growth factors. EGCG may therefore be useful in the chemoprevention and/or treatment of colorectal cancer.

(–)‐Epigallocatechin gallate suppresses the growth of human hepatocellular carcinoma cells by inhibiting activation of the vascular endothelial growth factor–vascular endothelial growth factor receptor axis

The receptor tyrosine kinase vascular endothelial growth factor (VEGF) receptor (VEGFR) plays an important role in tumor angiogenesis of hepatocellular carcinoma (HCC). (–)‐Epigallocatechin gallate (EGCG), the major biologically active component of green tea, inhibits growth in a variety of human cancer cells by inhibiting the activation of several types of receptor tyrosine kinases. In this study, we examined the effects of EGCG on the activity of the VEGF–VEGFR axis in human HCC cells. The levels of total and phosphorylated (i.e. activated) form of VEGFR‐2 protein (p‐VEGFR‐2) were observed to increase in a series of human HCC cell lines in comparison to the Hc normal human hepatocytes. EGCG preferentially inhibited the growth of HuH7 HCC cells, which express constitutive activation of the VEGF–VEGFR axis, in comparison to Hc cells. Treatment of HuH7 cells with EGCG caused a time‐ and dose‐dependent decrease in the expression of VEGFR‐2 and p‐VEGFR‐2 proteins. The production of VEGF from HuH7 cells was reduced by treatment with EGCG. Drinking of EGCG significantly inhibited the growth of HuH7 xenografts in nude mice and this was associated with inhibition of the activation of VEGFR‐2 and its related downstream signaling molecules, including ERK and Akt. EGCG drinking also decreased the expression of Bcl‐xL protein and VEGF mRNA in the xenografts. These findings suggest that EGCG can exert, at least in part, its growth‐inhibitive effect on HCC cells by inhibiting the VEGF–VEGFR axis. EGCG might therefore be useful in the treatment of HCC. (Cancer Sci 2009; 100: 1957–1962)

Prevention of Second Primary Tumors by an Acyclic Retinoid in Patients with Hepatocellular Carcinoma

Oral administration with acyclic retinoid, a synthetic vitamin A analog, for a limited period of 12 months (48 weeks) prevented the development of second primary hepatocellular carcinoma (HCC) and also improved the survival of patients who underwent curative treatments of the initial tumor. Following that randomized controlled study reported in 1996 and 1999, we have continued to follow up the patients by medical imaging and blood chemical analyses, and found that the preventive effect of acyclic retinoid lasted up to 199 weeks after randomization (or 151 weeks after completion of retinoid administration). The retinoid’s effect was not mediated by reduction in hepatic necro-inflammation since no significant decrease in serum aminotransferase activity was seen in the retinoid group. Such observation seems quite distinct from the cancer-preventive mechanism of interferon, a potent immunopreventive agent for HCC. We have also shown here the reduction by the retinoid in serum levels of lectin-reactive α-fetoprotein (AFP-L3) and protein induced by vitamin K absence or antagonist-II (PIVKA-II), both of which indicate the presence of latent HCC cells. These results suggest that acyclic retinoid may delete such malignant clones before they expand to clinically detectable tumors and thereby inhibited second primary HCC. Once such latent clones are eradicated, it may well take at least several years for the next cancer clone to arise clinically. This may possibly explain a reason for the long-term effect of the retinoid even after the limited period of administration.

Dietary supplementation with branched-chain amino acids suppresses diethylnitrosamine-induced liver tumorigenesis in obese and diabetic C57BL/KsJ-db/db mice

Obesity and related metabolic abnormalities, including insulin resistance, are risk factors for hepatocellular carcinoma in non‐alcoholic steatohepatitis as well as in chronic viral hepatitis. Branched‐chain amino acids (BCAA), which improve insulin resistance, inhibited obesity‐related colon carcinogenesis in a rodent model, and also reduced the incidence of hepatocellular carcinoma in obese patients with liver cirrhosis. In the present study, we determined the effects of BCAA on the development of diethylnitrosamine (DEN)‐induced liver tumorigenesis in obese C57BL/KsJ‐db/db (db/db) mice with diabetes mellitus. Male db/db mice were given tap water containing 40 ppm DEN for an initial 2 weeks and thereafter they received a basal diet containing 3.0% of BCAA or casein, which served as a nitrogen content‐matched control of BCAA, throughout the experiment. Supplementation with BCAA significantly reduced the total number of foci of cellular alteration, a premalignant lesion of the liver, and the expression of insulin‐like growth factor (IGF)‐1, IGF‐2, and IGF‐1 receptor in the liver when compared to the casein supplementation. BCAA supplementation for 34 weeks also significantly inhibited both the development of hepatocellular neoplasms and the proliferation of hepatocytes in comparison to the basal diet or casein‐fed groups. Supplementation with BCAA improved liver steatosis and fibrosis and inhibited the expression of α‐smooth muscle actin in the DEN‐treated db/db mice. The serum levels of glucose and leptin decreased by dietary BCAA, whereas the value of the quantitative insulin sensitivity check index increased by this agent, indicating the improvement of insulin resistance and hyperleptinemia. In conclusion, oral BCAA supplementation improves insulin resistance and prevents the development of liver tumorigenesis in obese and diabetic mice. (Cancer Sci 2009)

Endoscopic Ultrasound-Guided Fine Needle Aspiration Biopsy for Diagnosis of Lymphoproliferative Disorders: Feasibility of Immunohistological, Flow Cytometric, and Cytogenetic Assessments

OBJECTIVES:In addition to morphology, immunophenotype and genetic abnormalities should be assessed during diagnosis and subclassification of lymphoproliferative disorders. The objective of this study was to evaluate the yield of endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) using a standard 19-gauge needle for diagnosis and subclassification of lymphoma, assessing the feasibility of immunohistological, flow cytometric, and cytogenetic assessments.METHODS:Two hundred forty patients with suspected lymphoma were referred for EUS-FNAB to our quaternary EUS center between June 2005 and December 2010. EUS-FNAB using a conventional 19-gauge needle was attempted for all patients, followed by histological assessments including immunohistological staining, flow cytometry, and cytogenetic analysis (G-band karyotyping). Among the patients, 152 were ultimately diagnosed with lymphoma. The primary outcome measure of this study was the sensitivity of histological assessment, including immunohistological staining, flow cytometry, and G-band karyotyping, for diagnosis and subclassification of lymphoma.RESULTS:Among the 152 patients ultimately diagnosed with lymphoma, 147 patients (96.7%) were diagnosed by EUS-FNAB, and classification in accordance with the WHO (World Health Organization) system was also possible for 135 patients (88.8%) on the basis of histological findings, including immunohistological staining. Flow cytometry showed abnormal or unusual cell populations in 121 (79.6%) of the 152 patients diagnosed with lymphoma, and in 114 (90.5%) of the 126 patients diagnosed with B-cell lymphoma. Specific cytogenetic abnormalities were detected in 21 (13.8%) of the lymphoma patients.CONCLUSIONS:EUS-FNAB using a standard 19-gauge needle has high diagnostic value for lymphoma. Immunophenotyping is usually possible, while cytogenetic abnormalities can be identified in a relatively limited number of patients.

Pitavastatin inhibits azoxymethane-induced colonic preneoplastic lesions in C57BL/KsJ-db/db obese mice.

Obesity and related metabolic abnormalities are risk factors for colorectal cancer. A state of chronic inflammation and adipocytokine imbalance may play a role in colorectal carcinogenesis. Statins, which are commonly used for the treatment of hyperlipidemia, are known to possess anti‐inflammatory effects. Statins also exert chemopreventive properties against various cancers. The present study examined the effects of pitavastatin, a recently developed lipophilic statin, on the development of azoxymethane (AOM)‐initiated colonic premalignant lesions in C57BL/KsJ‐db/db (db/db) obese mice. Male db/db mice were administrated weekly subcutaneous injections of AOM (15 mg/kg body weight) for 4 weeks and then were subsequently fed a diet containing 1 ppm or 10 ppm pitavastatin for 8 weeks. Feeding with either dose of pitavastatin significantly reduced the number of colonic premalignant lesions, β‐catenin accumulated crypts, by inhibiting proliferation and the surrounding inflammation. Pitavastatin increased the serum levels of adiponectin while conversely decreasing the serum levels of total cholesterol, tumor necrosis factor‐α (TNF‐α), interleukin (IL)‐6, IL‐18, and leptin. Pitavastatin also caused a significant increase in the expression of phosphorylated form of the AMP‐activated kinase (AMPK) protein on the colonic mucosa of AOM‐treated mice. In addition, the expression levels of TNF‐α, IL‐6, IL‐18, and COX‐2 mRNAs on the colonic mucosa of AOM‐treated mice were decreased by treatment with this agent. These findings suggest that pitavastatin attenuates chronic inflammation and improves the imbalance of adipocytokines, both of which are caused by the presence of excess adipose tissues, thereby preventing the development of colonic premalignancies in an obesity‐related colon cancer model. Therefore, some types of statins, including pitavastatin, may be a useful chemoprevention modality for colon cancer in obese individuals. (Cancer Sci 2010)

Combined endobronchial and endoscopic ultrasound-guided fine needle aspiration for mediastinal nodal staging of lung cancer

BACKGROUND Recently, transesophageal endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has been evaluated for mediastinal nodal staging (N staging) of lung cancer, as this technique is less invasive than mediastinoscopy and possibly more accurate than 18F-fluorodeoxyglucose positron emission tomography with computed tomography (PET-CT). However, EUS-FNA does not provide access to pretracheal and hilar lymph nodes. More recently, endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has been introduced as a novel technique for accessing pretracheal and hilar lymph nodes. Although the combined endoscopic approach of EUS-FNA and EBUS-TBNA is presumably more accurate than PET-CT, only a few reports have quantitatively evaluated its diagnostic ability. Therefore, we prospectively assessed the diagnostic yield of this combined endoscopic approach for mediastinal N staging of lung cancer. METHODS A consecutive series of 120 patients with suspected resectable lung cancer on CT findings underwent PET-CT and combined EUS-FNA/EBUS-TBNA. The accuracy and other diagnostic indices of the combined approach in mediastinal N staging were compared with those of PET-CT. RESULTS Among the enrolled patients, a final pathological N stage was established in 110 patients. The accuracy of the combined approach using EUS-FNA and EBUS-TBNA was significantly higher than that of PET-CT (90.0 % vs. 73.6 %; P < 0.0001). The sensitivity, specificity, and positive and negative predictive values were respectively 71.8 %, 100 %, 100 %, and 86.6 % for the combined approach vs. 47.4 %, 87.5 %, 66.7 %, and 75.9 % for PET-CT. CONCLUSIONS The combined endoscopic approach using EUS-FNA and EBUS-TBNA provided excellent diagnostic performance. Therefore, this approach is strongly recommended before surgery or mediastinoscopy to avoid futile thoracotomy and surgical intervention.

Serum concentration of L-kynurenine predicts the clinical outcome of patients with diffuse large B-cell lymphoma treated with R-CHOP

Purpose: Introduction of rituximab has largely improved the prognosis of patients with diffuse large B‐cell lymphoma(DLBCL). Such change in therapeutic outcome necessitates the identification of additional prognostic factors to conventional indexes that have been validated for CHOP without rituximab. Indoleamine 2,3‐dioxygenase (IDO) exerts intense immunomodulatory effects because of enzymatic activities that catalyze the breakdown of the essential amino acid L‐tryptophan. The activity of IDO can be estimated by measuring the serum concentration of L‐kynurenine. Here, we investigated the role of L‐kynurenine as a prognostic marker in R‐CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) therapy. Experimental design: Data from 73 consecutive patients treated with eight cycles of R‐CHOP or R‐THP (tetrahydropyranyl adriamycin)‐COP between December 2002 and March 2007 were analyzed. L‐kynurenine concentrations in serum samples obtained at admission were measured by high‐performance liquid chromatography. Results: The median serum L‐kynurenine level was 1.575 μm (range 0.537–9.588). The complete response (CR) rates of patients with L‐kynurenine <1.5 and ≥1.5 μm were 83% and 61%, respectively (P < 0.05). The three‐yr overall survival (OS) rates for patients with L‐kynurenine <1.5 and ≥1.5 μm were 89% and 58%, respectively (P < 0.005). In addition, higher age, poor performance status, elevated serum lactate dehydrogenase, and unfavorable as well as revised International Prognosis Index were significantly worse factors for CR rate and OS. Multivariate analyses revealed only L‐kynurenine as an independent prognostic factor for OS. Conclusions: Serum L‐kynurenine might be a novel prognostic factor to determine the treatment outcome of DLBCL with the R‐CHOP regimen.