Expression of the gene for a membrane-bound fatty acid receptor in the pancreas and islet cell tumours in humans: evidence for GPR40 expression in pancreatic beta cells and implications for insulin secretion

AIMS/HYPOTHESIS

G protein-coupled receptor 40 (GPR40) is abundantly expressed in pancreatic beta cells in rodents, where it facilitates glucose-induced insulin secretion in response to mid- to long-chain fatty acids in vitro. However, GPR40 gene expression in humans has not been fully investigated, and little is known about the physiological and pathophysiological roles of GPR40 in humans. The aim of this study, therefore, was to examine GPR40 expression and its clinical implications in humans.

METHODS

GPR40 mRNA expression in the human pancreas, pancreatic islets and islet cell tumours was analysed using TaqMan PCR.

RESULTS

GPR40 mRNA was detected in all human pancreases collected intraoperatively. It was enriched approximately 20-fold in isolated islets freshly prepared from the pancreases of the same individuals. The estimated mRNA copy number for the GPR40 gene in pancreatic islets was comparable to those for genes encoding sulfonylurea receptor 1, glucagon-like peptide 1 receptor and somatostatin receptors, all of which are known to be expressed abundantly in the human pancreatic islet. A large amount of GPR40 mRNA was detected in insulinoma tissues, whereas mRNA expression was undetectable in glucagonoma or gastrinoma. The GPR40 mRNA level in the pancreas correlated with the insulinogenic index, which reflects beta cell function (r=0.82, p=0.044), but not with glucose levels during the OGTT, the insulin area under the OGTT curve or the index for the homeostasis model assessment of insulin resistance (HOMA-IR).

CONCLUSIONS/INTERPRETATION

The present study provides evidence for GPR40 gene expression in pancreatic beta cells and implicates GPR40 in insulin secretion in humans.

Growth inhibition through activation of peroxisome proliferator-activated receptor gamma in human oesophageal squamous cell carcinoma

Peroxisome proliferator-activated receptor gamma (PPARgamma) heterodimerises with retinoid X receptor alpha (RXRalpha) and is thought to be a novel therapeutic target for human malignancies. We evaluated the ability of troglitazone (TRO) alone or in combination with 9-cis retinoic acid (9CRA), ligands of PPARgamma and RXRalpha, respectively, to inhibit the growth of oesophageal squamous cell carcinoma (OSCC). All 10 tested OSCC cell lines of a KYSE series expressed PPARgamma and RXRalpha at both the mRNA and protein levels. In four tested cell lines, TRO inhibited growth, and a synergistic effect was observed with simultaneous 9CRA application. In KYSE 270 cells, a luciferase reporter assay showed that the simultaneous application of TRO and 9CRA to the cells increased the relative luciferase activity approximately 20-fold compared with the controls without TRO or 9CRA application. In this cell line, flow cytometry demonstrated that combined treatment with TRO and 9CRA greatly increased the sub-G1 phase, and Hoechst 33342/propidium iodide (PI) staining showed that apoptotic cell death was mainly induced through ligand treatment. In addition, implanted tumours in nude mice showed significant inhibition of tumour growth when treated with TRO. These results suggest that the PPARgamma/RXRalpha heterodimer may be a new therapeutic target for OSCC.

Rac regulates vascular endothelial growth factor stimulated motility

During angiogenesis endothelial cells migrate towards a chemotactic stimulus. Understanding the mechanism of endothelial cell migration is critical to the therapeutic manipulation of angiogenesis and ultimately cancer prevention. Vascular endothelial growth factor (VEGF) is a potent chemotactic stimulus of endothelial cells during angiogenesis. The endothelial cell signal transduction pathway of VEGF represents a potential target for cancer therapy, but the mechanisms of post-receptor signal transduction including the roles of rho family GTPases in regulating the cytoskeletal effects of VEGF in endothelial cells are not understood. Here we analyze the mechanisms of cell migration in the mouse brain endothelial cell line (bEND3). Stable transfectants containing a tetracycline repressible expression vector were used to induce expression of Rac mutants. Endothelial cell haptotaxis was stimulated by constitutively active V12Rac on collagen and vitronectin coated supports, and chemotaxis was further stimulated by VEGF. Osteopontin coated supports were the most stimulatory to bEND3 haptotaxis, but VEGF was not effective in further increasing migration on osteopontin coated supports. Haptotaxis on support coated with collagen, vitronectin, and to a lesser degree osteopontin was inhibited by N17 Rac. N17 Rac expression blocked stimulation of endothelial cell chemotaxis by VEGF. As part of the chemotactic stimulation, VEGF caused a loss of actin organization at areas of cell-cell contact and increased stress fiber expression in endothelial cells which were directed towards pores in the transwell membrane. N17 Rac prevented the stimulation of cell-cell contact disruption and the stress fiber stimulation by VEGF. These data demonstrate two pathways of regulating endothelial cell motility, one in which Rac is activated by matrix/integrin stimulation and is a crucial modulator of endothelial cell haptotaxis. The other pathway, in the presence of osteopontin, is Rac independent. VEGF stimulated chemotaxis, is critically dependent on Rac activation. Osteopontin was a potent matrix activator of motility, and perhaps one explanation for the absence of a VEGF plus osteopontin effect is that osteopontin stimulated motility was inhibitory to the Rac pathway.

Recurrent acute myositis after allogeneic bone marrow transplantation for myelodysplasia

A 54-year-old woman developed polymyositis 6 months after allogeneic bone marrow transplantation (BMT) for acute myelogenous leukemia transformed from myelodysplasia. At the onset of myositis, the patient had oral dryness, and the histology of oral mucosa was compatible with chronic graft-versus-host disease (GVHD). Muscle biopsy revealed focal muscle necrosis with massive lymphocytic infiltration. She was diagnosed with polymyositis, and the dose of cyclosporine was increased. Three months later, a complete resolution of myositis had been obtained, and the cyclosporine was tapered off. However, 51 months after the first episode of myositis, she again noted severe myalgia and was diagnosed with a recurrence of polymyositis based on high serum creatinine kinase (CK) and the findings of magnetic resonance imaging (MRI). At that time, chronic GVHD in other organs was not present. She achieved a second remission of polymyositis with cyclosporine, and has remained in remission for 4 years. The pathogenesis of myositis can be attributed to the immunologic imbalance characteristic of the post-allogeneic BMT setting.

Ligands for peroxisome proliferator-activated receptor gamma inhibit growth of pancreatic cancers both in vitro and in vivo

Peroxisome proliferator-activated receptor gamma (PPARgamma) is expressed largely in adipose tissues and plays an important role in adipocyte differentiation. Several studies have recently shown that ligands of PPARgamma could lead to growth inhibition in some malignancies. In our study, we focused on pancreatic cancers, because the prognosis of advanced pancreatic cancer has not significantly improved due to its resistance to various chemotherapeutic regimens, so that a novel strategy should be required. We show here that PPARgamma is expressed in 5 pancreatic cancer cell lines detected in both mRNA and protein level as well as in human primary and metastatic pancreatic carcinomas examined by immunohistochemical studies. A specific ligand of PPARgamma, troglitazone, led to G1 accumulation with the increase in p27(Kip1), but not p21(Waf1/Cip1) and inhibited cellular proliferation in a pancreatic cancer cell line, Panc-1. The overexpression of PPARgamma in a pancreatic cancer cell line, KMP-3, caused lipid accumulation, which suggested cell growth in some cancers might be inhibited, at least in part, through terminal differentiation in the adipogenic lineage. In addition, implanted Panc-1 tumors in nude mice showed significant inhibition of tumor growth, when treated with pioglitazone, another specific ligand of PPARgamma. Our results suggest that ligands of PPARgamma may be a novel therapeutic agent for the treatment of pancreatic carcinomas.

Rho family GTPases regulate VEGF-stimulated endothelial cell motility

Migration of endothelial cells induced by vascular endothelial growth factor (VEGF) is a critical step in angiogenesis. Stimulation of motility by growth factors such as VEGF requires interaction with the signal transduction pathways activated by the extracellular matrix (ECM). Here we demonstrate that the Rac GTPase is the critical intersection activated by type 1 collagen ECM and VEGF during stimulation of endothelial cell motility. To analyze the role of the Rho family GTPases in VEGF-stimulated endothelial cell chemotaxis and ECM-stimulated haptotaxis, we transduced the respective fusion proteins in human foreskin dermal endothelial cells using a Tat peptide from the human immunodeficiency virus Tat protein. VEGF signaling required Rac activation during chemotaxis, and Rac and Cdc42 were activated during haptotaxis on type I collagen. Similar to VEGF, Rac activation induced an increase in endothelial cell stress fiber and focal adhesion. Surprisingly, Rho activation was not present in collagen-induced haptotaxis or stimulation of chemotaxis by VEGF, although Rho induced stress fibers and focal adhesions similar to Rac activation. The result of constitutive Rho activation was an inhibition of haptotaxis. Thus, Rac is required and sufficient for the activation of endothelial cell haptotaxis and VEGF-stimulated chemotaxis.

[Two cases of giant female urethral stone in long-term bedridden elderly]

A 78-year-old female suffering from a cerebral infarction and subdural hematoma was referred to us due to a hard mass in the anterior vaginal wall which was disclosed during gynecological examination. An abdominal X-ray, computed tomography (CT) and magnetic resonance imaging (MRI) showed that a large spindle-shaped stone, 60 x 42 mm in size, was impacting the urethra. It was impossible to catheterize the urethra. The stone gradually projected through the external urethral meatus and was removed by grasping and drawing with forceps. Another 83-year-old female with senile dementia was referred to us because of macrohematuria. An abdominal X-ray and CT showed the presence of two oval bladder stones, 32 x 24 mm and 30 x 21 mm in size. During a follow-up, one of the stones projected partially through the external urethral meatus and was removed by drawing with forceps. After a week, the other stone impacted the urethra and was removed in the same way. Both women were frail, bedridden institutionalized elderly with severe dementia, and their urination had been managed with diapers for years. As the proportion of elderly people in Japan rapidly increases, female urethral stones migrating from the urinary bladder, once very rare, may increase in number, to which we must pay attention.

The prevalence of renal cell carcinoma: a nation-wide survey in Japan in 1997

BACKGROUND

The present study was conducted to investigate the incidence of renal cell carcinoma by sex, age group and different regions in Japan.

METHODS

The survey was conducted from the beginning of January 1997 to the end of December 1997. A total of 1306 Institutions in all 47 prefectures throughout Japan were requested to register cases.

RESULTS

There were 6358 persons with renal cell carcinoma, consisting of 4372 men and 1986 women. The age-specific incidence rates showed a peak in the age group of 65-70 years in both men and women. The crude incidence rates per 100 000 population for men and women were 7.1 and 3.1, respectively, and age-standardized incidence rates per 100 000 population for men and women were 4.9 and 1.8, respectively. The incidence rates in the Hokkaido region were significantly higher than in other regions (P < 0.05), among which there was no significant difference in incidence rates.

CONCLUSIONS

The present study showed that the incidence rates of renal cell carcinoma in Japan were approximately the same as among Japanese in Los Angeles. The rates were, however, lower than North American and European countries, but higher than China, Central or South American countries and African countries. The reasons for the high incidence of renal cancer in the Hokkaido region are not entirely clear. Further epidemiologic research is required.

Induction of effective antitumor immune responses in a mouse bladder tumor model by using DNA of an alpha antigen from mycobacteria

One of the main objectives of cancer immunotherapy is the activation and increase in number of antitumor effector cells. Recently, genetically modified tumor cell vaccines have been proposed for elicitation of antitumor effector cells. Native alpha antigen (alpha Ag) (also known as MPT59 and antigen 85B) of mycobacteria, which cross-reacts among mycobacteria species, may play an important biological role in host-pathogen interaction because it elicits various helper T-cell type 1 immune responses. To assess the induction of antitumor immune responses by alpha Ag, mouse tumor cell lines transfected with cDNA of alpha Ag from Mycobacterium kansasii were established, and the possibility of producing a tumor cell vaccine for induction of antitumor effects was explored. Transfection of tumor cell lines with an alpha Ag gene lead to primary tumor rejection and the establishment of protective immunity to nontransfected original tumor cell lines in Mycobacterium bovis bacillus Calmette-Gurin (BCG)-primed and unprimed mice. Mice immunized with tumor cell lines transfected with the alpha Ag gene showed delayed-type hypersensitivity responses in vivo and proliferative responses together with induction of interferon-gamma of spleen cells against nontransfected wild-type tumor cell lines in in vitro experiments. Moreover, immunization of mice with alpha Ag-expressing tumor cells elicited tumor-specific and cytotoxic T lymphocyte (CTL) epitope peptide-specific CD8+ CTLs. The results of this study provided evidence of the potential usefulness of alpha Ag in tumor cell vaccines.

Impact of genetic polymorphisms of 17-hydroxylase cytochrome P-450 (CYP17) and steroid 5alpha-reductase type II (SRD5A2) genes on prostate-cancer risk among the Japanese population

Steroid hormones, especially testosterone, play important roles in the carcinogenesis of prostate cancer, and several studies have reported changes in risk with polymorphisms of genes involved in steroid metabolism. One example is the CYP17 gene, which has a polymorphic T-to-C substitution in the 5'-untranslated region giving rise to A1 (T) and A2 (C) alleles. Steroid 5alpha-reductase type II (SRD5A2), which converts testosterone to the metabolically more active dihydrotestosterone, exhibits 2 polymorphisms: V89L, which substitutes leucine for valine at codon 89, and A49T, which substitutes threonine for alanine at codon 49. We therefore designed a case-control study of 105 prostate-cancer patients and 210 controls with benign prostatic hyperplasia for the purpose of investigating the association between prostate-cancer risk and polymorphisms in the SRD5A2 and CYP17 genes among the Japanese. The frequency of the CYP17 A2/A2 genotype in cases (18.8%) was higher than in controls (14.5%). Compared with the A1/A1 genotype, the odds ratio for the A2/A2 genotype was 2.39 (95% confidence interval 1.04-5.46, p = 0.04). The frequency of the SRD5A2 LL genotype in cases (29.3%) was also slightly higher than in controls (24.6%), but this was not significant. Regarding the A49T polymorphism of SRD5A2, we could not detect the T allele in any of the examined samples. These data suggest a significant association between the CYP17 polymorphism and prostate-cancer risk among the Japanese.

Genetic polymorphisms in cytochrome P450 (CYP) 1A1, CYP1A2, CYP2E1, glutathione S-transferase (GST) M1 and GSTT1 and susceptibility to prostate cancer in the Japanese population

Associations between genetic polymorphisms of CYP1A1, CYP1A2, CYP2E1, GSTM1 and GSTT1 and prostate cancer (PCa) were analyzed in a case-control study of 315 individuals. The frequency of valine (Val)/valine (Val) genotypes for CYP1A1 was 11.3% in cases compared with 5.5% in controls, this polymorphism thus being associated with a significantly increased risk of PCa (odds ratio=2.4, 95% confidence interval (CI)=1.01-5.57). No links were detected between PCa and polymorphisms in other enzymes. However, the combination of CYP1A1 (Ile/Val and/or Val/Val) polymorphisms with the GSTM1 null type resulted in an OR of 2.2 (CI=1.10-4.57, 1.12-4.20, respectively). This study suggests that the CYP1A1 polymorphism and its combination with GSTM1 may be associated with PCa susceptibility in the Japanese population.

Mitogen-activated protein kinase pathway is involved in alpha6 integrin gene expression in androgen-independent prostate cancer cells: role of proximal Sp1 consensus sequence

Metastatic diseases of prostate cancer reveal high expression of alpha6 integrin and the activation of mitogen-activated protein kinases (MAP kinase). Therefore, the present study was conducted to examine whether MAP kinase pathway is involved in the alpha6 integrin gene expression in androgen-independent prostate cancer cell lines. alpha6 integrin mRNA expression, the alpha6 integrin promoter-induced luciferase activities and MAP kinase enzyme activities in androgen-independent LNCaP and PC-3 cell lines were higher than those in androgen-dependent LNCaP. Deletion and mutation analysis showed that Sp1 consensus sequence at -48 to -43 bp from the transcription start site was necessary for basal promoter activity. Binding of Sp1 to its consensus sequence in three cell lines was confirmed by electrophoretic mobility shift assays. Sp1 binding to its consensus sequence, as well as promoter activity and mRNA expression, were found to be inhibited by an inhibitor of MAP kinase kinase 1 and 2, U0126, in the androgen-independent cell lines. Our results indicate that the proximal Sp1 is necessary for basal promoter activity of the alpha6 integrin, suggesting that signal transduction from MAP kinases to activation of Sp1 might be involved in alpha6 integrin gene expression in androgen-independent prostate cancer cell lines.

Analysis of hypophosphatemia in calcium nephrolithiasis

PURPOSE AND METHODS

To analyze the pathophysiology of hypophosphatemia in calcium nephrolithiasis, we investigated the relation between serum phosphorus, 1,25-dihydroxyvitamin D, and parathyroid hormone (PTH) levels in 63 consecutive patients with calcium nephrolithiasis, comparing them with 26 age-matched control subjects.

RESULTS

Serum phosphorus concentrations in normocalciuric and absorptive hypercalciuric stone formers were significantly decreased compared with control subjects (P<0.001 and P<0.01, respectively). The fractional excretion (TRP) and renal threshold (TmP/GFR) of phosphorus were significantly decreased in the subjects with nephrolithiasis (P<0.01 and P<0.001, respectively). Serum phosphorus concentrations were inversely correlated with serum 1, 25-dihydroxyvitamin D in control subjects and in absorptive hypercalciuric stone formers (P<0.01 and P <0.05, respectively), suggesting that the physiologic relation between phosphorus and 1, 25-dihydroxyvitamin D is maintained in these patients. Serum phosphorus concentrations in absorptive hypercalciuric patients, although related to 1,25-dihydroxyvitamin D, were not related to PTH even though PTH and 1,25-dihydroxyvitamin D concentrations were directly related (P<0.05). The lack of a relation between PTH and serum phosphorus concentrations in absorptive hypercalciuric stone formers was similar to that in controls. In normocalciuric stone formers, there was no relation between serum 1,25-dihydroxyvitamin D and serum phosphorus, but PTH and 1,25-dihydroxyvitamin D were inversely correlated (P<0.05).

CONCLUSIONS

Abnormal renal tubular function with a depressed rate of renal phosphorus transport and an abnormal 1,25-dihydroxyvitamin D concentration is common in nephrolithiasis. Differences in the relations between phosphorus and 1,25-dihydroxyvitamin D observed in hypercalciuric v normocalciuric subjects suggest that the pathogenesis of proximal tubulopathy differs among patients with nephrolithiasis.

[Successful TS-1 therapy in a patient with non-resectable gastric cancer and renal dysfunction]

A 73-year-old woman presented to our hospital with epigastric pain and swelling of the left upper limb. Enlarged lymph nodes with adhesion were palpable in the left cervical region and supraclavicular fossa. Tests were performed with the thought that the left upper limb swelling was secondary to venous compression by the enlarged lymph nodes. Gastroscopy detected a torose lesion on the anterior wall at the gastric angle and biopsy revealed that it was moderately differentiated adenocarcinoma. MRI showed metastasis to the sixth cervical vertebra and the first thoracic vertebra. Based on these findings, she was diagnosed as having progressive gastric cancer with metastasis to Virchow's lymph node and the cervical and thoracic vertebrae. Because it was considered impossible to perform radical gastrectomy, chemotherapy was given. Since renal dysfunction was suggested by a serum Cr of 1.5 mg/ml and a Ccr of 26.2 ml/min, TS-1 was administered at a lower dose (50 mg/day for 4 weeks) than usual, followed by 2 weeks off therapy to complete 1 course. During TS-1 therapy, the plasma 5-FU concentration at 4 h was 129.5 ng/ml, indicating that an effective plasma level of the drug was achieved. TS-1 therapy was considered effective because it reduced the diameter of the primary tumor and the lymph node metastasis, with only mild adverse reactions including myelosuppression.

[Clinical study of prostate cancer: statistical analysis of 107 cases in the past 12 years]

One hundred and seven patients with prostate cancer were treated at Mie University Hospital during the past 12 years between 1988 and 1999. They were between 53 and 83 years old, with an average age of 70.8 years old. The clinical stage was defined as A, B, C and D in 3 (2.8%), 19 (17.8%), 50 (46.7%) and 35 (32.7%) patients, respectively. At initial diagnosis, the tumor was well, moderately and poorly differentiated adenocarcinoma in 26 (24.3%), 47 (43.9%) and 34 (31.8%) patients, respectively. The median follow-up period was 52.3 months. The overall 1, 3 and 5-year survival rates were 98.0%, 86.8% and 75.2%, respectively. The 5-year survival rates for stage A, B, C and D were 100%, 93.8%, 82.1% and 56.9%, respectively. A significant difference (p = 0.017) in 5-year survival rate was noted between stage C and D. The 5-year survival rate was 100% for well differentiated, 78.0% for moderately differentiated, and 53.2% for poorly differentiated adenocarcinoma. A significant difference (p = 0.0016) in the 5-year survival rate was noted between well differentiated and poorly differentiated adenocarcinoma. According to the therapy, the 5-year survival rate in stage C was 86.2% for the radical prostatectomy group and 84.0% for the endocrine therapy group. There was no significant difference between these 2 treatment groups. Endocrine therapies, classified into maximum androgen blockade (MAB) and endocrine therapy other than MAB were performed for stage D as an initial therapy. Although the prognosis in the patients treated with MAB was better than that with other endocrine therapies, there was no significant difference between these 2 endocrine treatment groups.

Effect of increased intrareservoir pressure on upper urinary tract function in continent urinary diversion patients assessed by radioisotope renography

To assess upper urinary tract function and determine an ideal continent reservoir capacity, we investigated the relationship between intrareservoir pressure and functional parameters using radioisotope renography. Forty-three patients for whom ileal reservoir construction was performed by Kock pouch (n = 33) or Hautmann's ileal neobladder (n = 14) approaches between November 1984 and September 1996 were studied. After the reservoir contents were catheterized, (99m)Tc-MAG 3 renoscintigraphy was carried out and time activity curves in the kidney (renogram) and reservoir (reservoirgram) were recorded, while saline solution was poured into the reservoir for monitoring of intrareservoir pressure. Three basic abnormal curves were noted in the excretory phase on renograms: a normal downward curve followed by an upward curve, a continuous upward curve associated with or without a sharp decline after the catheterization of the reservoir contents, and episodes of spike waves. Based on these curves, renograms were classified into five types: normal, high pressure, retention, obstruction, and reflux. Abnormal types were noted with 51 of 65 renal units (78.5%) in the Kock pouch group and 15 of 25 renal units (60.0%) in the neobladder group. This examination method may be useful for evaluating urodynamics in the upper urinary tract of patients with a continent ileal reservoir and provide data on adequate voiding volumes for the individual patient.

p27Kip1 is the key mediator of phenylacetate induced cell cycle arrest in human prostate cancer cells

Treatment with millimolar concentrations of phenylacetate (PA), results in cytostasis, growth inhibition and differentiation in several human cancer cell lines, including prostate cancer. However, the molecular basis of PA-induced biological effects has not been elucidated in detail. In this study we focused on its influence on cell cycle events and investigated alterations in cell cycle regulators in androgen-dependent and independent human prostate cancer cell lines. FACS analysis revealed that suppression of cell growth by PA was due to G1 arrest, with reduced phosphorylation of the retinoblastoma protein (pRb) and CDK2 activity. Expression of p27Kip1 was increased, while p21Cip1, p53, cyclinD1 and cyclin E were not affected by PA. Binding of p27Kip1 to CDK2 increased significantly following treatment with PA. Furthermore, antisense p27Kip1 oligonucleotide attenuated the inhibitory effect of PA. Our results suggested that p27Kip1 might be a critical target in PA-mediated cell growth arrest in prostate cancer cells playing a key role in CDK2 inactivation followed by hypophosphorylation of pRB and subsequent G1 cell cycle arrest.

Aneurysm of the left sinus of Valsalva causing aortic, mitral regurgitation and myocardial ischemia

An aneurysm of the left sinus of Valsalva producing aortic and mitral regurgitation with myocardial ischemia was treated successfully by reconstructing the left coronary sinus while preserving the aortic cusp combined with coronary artery bypass grafting. Aortic and mitral regurgitation occurred due to distortion of the left aortic cusp by a huge aneurysm that also compressed and obstructed the main trunk of the left coronary artery. The postoperative course was uneventful and follow-up showed aortic and mitral regurgitation to be absent and the coronary graft to be patent. Aortic valve-sparing surgery thus proved to be an appropriate procedure for this case.