In vivo proliferation of differentiated pancreatic islet beta cells in transgenic mice expressing mutated cyclin-dependent kinase 4

AIMS/HYPOTHESIS

It has previously been hypothesised that highly differentiated endocrine cells do not proliferate or regenerate. However, recent studies have revealed that cyclin-dependent kinase 4 (CDK4) is necessary for the proliferation of pancreatic islet beta cells. The aim of this study was to determine whether activation of CDK4 can potentially be used as a radical treatment for diabetes without malignant transformation.

METHODS

We generated transgenic mice expressing mutant CDK4 under the control of the insulin promoter to examine the effect of activated CDK4 overexpression in the postnatal development of pancreatic islets.

RESULTS

In the transgenic mice, total CDK4 protein expression was increased by up to 5-fold, with a concomitant increase in CDK4 activity indicated by the detection of phosphorylated Rb protein in pancreatic islets. Histopathologically, many cells tested positive for proliferating cell nuclear antigen, and pancreatic islets displayed hyperplasia due to the extreme proliferation of beta cells containing a large number of insulin granules. Pancreatic islet alpha, delta and PP cells did not increase. Over an 18-month observation period, the transgenic mice did not develop insulinoma. Levels of expression of GLUT1 and c-myc were comparable to those in the littermates of the transgenic mice. GLUT2 expression was identified in the pancreatic islets of transgenic mice. No significant differences in telomerase activities were detected between transgenic mice and their littermates. Transgenic mice were superior to their littermates in terms of glucose tolerance and insulin secretion in response to the intraperitoneal injection of glucose, and hypoglycaemia was not observed.

CONCLUSIONS/INTERPRETATION

Activated CDK4 stimulates postnatal pancreatic beta cell proliferation, during which the highly differentiated phenotypes of pancreatic islet beta cells are preserved without malignant transformation.

Redox state-dependent and sorbitol accumulation-independent diabetic albuminuria in mice with transgene-derived human aldose reductase and sorbitol dehydrogenase deficiency

AIMS/HYPOTHESIS

We investigated the role played by sorbitol accumulation in the kidney in the development of diabetic albuminuria.

METHODS

We created mice ( hAR-Tg:SDH null) with transgene-derived human aldose reductase and sorbitol dehydrogenase (SDH) deficiency, and analysed (i). the contribution of accumulated sorbitol to urinary albumin excretion rate, and (ii). the effect of the aldose reductase inhibitor, epalrestat, on the diabetic redox state, including decreased renal reduced glutathione concentrations or increased lactate to pyruvate ratios in the diabetic kidney.

RESULTS

Compared to littermates, non-diabetic transgenic mice had a 2.6-fold increase in aldose reductase mRNA. In a diabetic group, aldose reductase mRNA in hAR-Tg mice was 2.7-fold higher than in littermates. In the diabetic and non-diabetic groups, hAR-Tg:SDH null mice had the highest sorbitol content among all four genetic types including hAR-Tg:SDH null, SDH null, hAR-Tg and littermates. The urinary albumin excretion rate in non-diabetic groups was similar in the four genetic types of mouse. In diabetic groups it was greater than in non-diabetic groups, but did not correlate with the sorbitol content among the four genetic types of mouse. When aldose reductase inhibitor and streptozotocin were given simultaneously at 6 weeks of age, epalrestat prevented diabetic increases in urinary albumin excretion rate and completely prevented diabetic decreases in reduced glutathione concentrations and diabetic increases in lactate to pyruvate ratios, even in the presence of transgenic aldose reductase.

CONCLUSIONS/INTERPRETATION

The degree of diabetic albuminuria in genetically modified mice is dependent on the redox state and independent of polyol accumulation; aldose reductase inhibitor can prevent diabetic albuminuria by normalising diabetic redox changes.

Effect of serine residue on the effectiveness of cationic polypeptide-based gene delivery

Poly-L-lysine(pL) was chemically modified based on two essential features which we recently reported and subjected to the gene-transfer experiment in vitro. Introduction of 25 mol% serine residue to pL slightly enhanced the gene expression level, while trimethylation of epsilon-ammonium groups of lysine did not. Only when pL was modified in both way, giving N2-trimethyl poly(lysine-co-serine), markedly enhanced gene expression was observed. The cellular uptake and localization of DNA in the cells were similar for each cationic polypeptide. DNA forming complex with the polypeptides containing serine residue was found to be well transcribed in in vitro transcription/translation system, suggesting the hydrophilic nature may allow polypeptide/DNA complexes to be recognized by the transcriptional factors and lead the subsequent effective gene expression.

Characterization of RNA structure by bis-pyrene-labeled 2'-O-methyloligonucleotides

Properties of 2'-O-methyloligoribonucleotides containing two consecutive 2'-O-(1-pyrenylmethyl)uridine were investigated as a fluorescent probe to search the single strand regions of RNA. The bis-pyrene-labeled 2'-O-methyloligoribonucleotide (OMUpy2) induced the formation of pyrene dimer upon hybridization with the complementary oligoribonucleotides and showed remarkable appearance of broad structureless fluorescence at 480 nm. Contrarily, when OMUpy2 was hybridized with the complementary oligodeoxyribonucleotides, such enhancement of fluorescence was scarcely observed. When various OMUpy2 were applied to E. coli 5S-rRNA, the fluorescence intensity at 480 nm was varied in a sequence specific manner.

Structure/function relationship in the polyplexes containing cationic polypeptides for gene delivery

Various cationic polypeptides of linear or highly branched structures were synthesized by introducing tertiary or quaternary ammonium groups and hydroxyl groups to poly(L-lysine) (PL) or polyamideamine (PAMAM) dendrimers. These polycations were mixed with plasmid DNA to form polyplexes and subjected to in vitro gene introduction experiment. The transient gene expression was greatly affected by the side groups of PL derivatives or the surface cation charge density of PAMAM dendrimers. This difference in gene expression was found to result from two independent factors as follows: one is the cellular uptake of the polyplexes and the other is the compaction of the polyplexes. Lower charge density of PAMAM dendrimers suppressed the polyplex formation and cellular uptake, resulting the lower gene expression. Only the polycations that form polyplexes compacted at an adequate extent lead an effective gene expression, suggesting that the physicochemical properties of the polyplexes defined by the chemical structures of the polycations play an important role in the effective gene transfer.

Study on structure of ribosomal RNA by time-resolved luminescence anisotropy analysis

Evaluation of the folded structure of E.coli 16S-rRNA was performed using 5'-Ru(II) complex labeled oligodeoxyribonucleotide (Ru-probe) as the probe. This probe could evaluate the dynamic manner of the binding site of Ru-probe by using the time-resolved luminescence anisotropy technique. It was found that the rotational manner of Ru-probe in the presence of 16S-rRNA was markedly dependent on the oligonucleotide sequence, indicating that the microenvironments around the Ru-probes were largely different.

Laparoscope-assisted distal gastrectomy for early gastric cancer in a 76-year-old man with situs inversus totalis

We report a case of a 76-year-old man with situs inversus totalis (SIT) who developed early gastric cancer. He was successfully treated by laparoscope-assisted distal gastrectomy for the gastric cancer. This case suggests that patients with SIT with malignancy could also undergo laparoscopic surgery. To the best of our knowledge, no case of laparoscopic surgery for malignant neoplasms associated with SIT has been reported in the English literature. We therefore believe this is the first case report.

Alternative approach to endoluminal treatment of an anastomotic aneurysm

Conventional surgical treatment of patients with an anastomotic aneurysm can be a surgical challenge if severe adhesions are present. We report here effective treatment of an anastomotic aneurysm using an endoluminal stent graft. A 71-year-old man had undergone an aorto-bifemoral bypass for Leriche's syndrome in 1989 and partial gastrectomy for cancer in 1996. He was admitted to our department with a pseudoaneurysm of a proximal anastomosis located at the aorta below both renal arteries. Based on his medico-surgical history, we considered that an endovascular stent should be placed. This graft composed of an UBE(UBE-WOVEN GRAFT) graft and self-expandable Z stents were introduced through the right limb of the bifurcated graft previously implanted, then were placed using the delivery system while advancing under fluoroscopic control, using a pusher rod. Endoleakage was not evident and the postoperative course was uneventful. An endovascular graft is one alternative approach for treating patients with an anastomotic aneurysm as it is less invasive. This procedure proved satisfactory for this patient.

Effects of temperature and pressure on the aggregation properties of an engineered elastin model polypeptide in aqueous solution

The pressure and temperature dependence of the cloud point transition of an aqueous solution of an elastin-like polypeptide (MGLDGSMG(VPGIG)40VPLE), prepared by bacterial expression of the corresponding artificial gene, was measured. A temperature-pressure diagram was constructed over a wide range of conditions. The (VPGIG)40 solution exhibited a well-defined pressure-induced cloudpoint (Pc), as well as a temperature-induced transition (Tc). From near atmospheric pressure up to 100 MPa, Tc increased with increasing pressure, but decreased with further increases in pressure above 200 MPa. The maximum Tc was reached at 100-200 MPa. Between 10 and 25 degrees C, the Pc decreased with increasing temperature, and a broad maximum in Pc was observed in the range -10 to 0 degree C. These results are compared with our previous results on synthetic thermoresponsive vinyl polymers.

Effect of cholesteryl side chain and complexing with cholic acid on gene transfection by cationic poly(ethylene glycol) derivatives

A new class of poly(ethylene glycol) derivative, Chol-PEG-A, having both cholesteryl- and amino-pendant groups (2.89 and 5.39 groups per polymer molecule, respectively) was synthesized. This amphiphilic PEG derivative forms a cationic polymer assembly in water. Chol-PEG-A expressed high transfection efficiency in the serum-free medium at relatively low amine/phosphate (N/P) ratios (1.3-1.5), whereas PEG-A, having only amino pendants without the cholesteryl side chain could transfect the cells only at a very high N/P ratio (83). The efficiency remarkably decreased by addition of fetal bovine serum (FBS) to the medium. Mixing of cholic acid to Chol-PEG-A gave a neutralized polyion complex, and the interaction with serum proteins was evidently suppressed. This Chol-PEG-A-cholic acid system showed higher gene expression even in the FBS-containing medium and as high a transfection efficiency as a Superfect.

Inhibitory effect of prostaglandin E 1 on intimal thickening caused by poor runoff conditions in the canine autologous vein grafts

The efficacy of ONO-1608, a newly developed liposomal formulation of prostaglandin E 1 prodrug, was evaluated on intimal hyperplasia of experimental canine autologous vein grafts under distal poor runoff conditions. The femoral vein was implanted into the femoral artery, preparing a distal poor runoff canine model. After 4 weeks of preparing the poor runoff model, the femoral vein was implanted into the femoral artery. They were then divided into two groups consisting of the control group and the ONO-1608 group. At 4 weeks, the grafts were harvested and intimal hyperplasia of the graft was measured with an ocular cytometer. Intimal cell proliferation was determined by bromodeoxyuridine incorporation 2 weeks after surgery. In addition, the effect of ONO-1608 on the proliferation of platelet-derived growth factor (PDGF)-stimulated human aortic smooth muscle cells (HASMCs) in culture was also investigated. At 4 weeks, the degree of intimal hyperplasia of the graft in the ONO-1608 group was significantly less than that of the control group. The bromodeoxyuridine labeling index 2 weeks after grafting was significantly lower in the ONO-1608 group compared with that in the control group. In addition, ONO-1608 significantly inhibited the proliferation of PDGF-stimulated HASMCs in culture. These results demonstrate the efficacy of ONO-1608 in reducing the degree of intimal hyperplasia of canine autogenous vein grafts under poor runoff conditions. The mechanism of reducing the intimal hyperplasia may be that ONO-1608 inhibited PDGF-stimulated proliferation of the smooth muscle cell. These results suggest that the administration of ONO-1608 may be beneficial in patients who have undergone gone arterial reconstruction.

Successful and optimized in vivo gene transfer to rabbit carotid artery mediated by electronic pulse

Several gene transfer methods, including viral or nonviral vehicles have been developed, however, efficacy, safety or handling continue to present problems. We developed a nonviral and plasmid-based method for arterial gene transfer by in vivo electronic pulse, using a newly designed T-shaped electrode. Using rabbit carotid arteries, we first optimized gene transfer efficiency, and firefly luciferase gene transfer via electronic pulse under 20 voltage (the pulse length: P(on)time 20 ms, the pulse interval: P(off) time 80 ms, number of pulse: 10 times) showed the highest gene expression. Exogenous gene expression was detectable for at least up to 14 days. Electroporation-mediated gene transfer of E. coli lacZ with nuclear localizing signal revealed successful gene transfer to luminal endothelial cells and to medial cells. Histological damage was recognized as the voltage was increased but neointima formation 4 weeks after gene transfer was not induced. In vivo electroporation-mediated arterial gene transfer is readily facilitated, is safe and may prove to be an alternative form of gene transfer to the vasculature.

Natural course of the functional and morphological changes in canine autogenous arterial graft

BACKGROUND

We examined the time course of endothelium-dependent and -independent responses in reversed autogenous arterial grafts during regeneration and tissue repair processes after arterial grafting in dogs.

MATERIALS AND METHODS

Autogenous arterial grafts implanted in the canine femoral artery were removed, cut into rings and suspended in organ chambers for isometric tension recording on the 1st, 3rd, 7th, 14th and 28th days after implantation. Electron-microscopic examination on the 1st, 3rd,7th, 14th and 28th days after transplantation was also performed. Control arteries were taken from nonsurgically treated femoral arteries.

RESULTS

Acetylcholine (ACh) and A23187 caused endothelium-dependent relaxations in arterial grafts throughout the study. Although endothelium-dependent relaxations to ACh and A23187 on the 3rd day after transplantation were only significantly impaired compared to those of control, they were similar to the control within 1 week after grafting. Smooth muscle relaxations in response to sodium nitroprusside in arterial grafts throughout the study were comparable with those of control arteries. No apparent intimal thickening of the arterial grafts was observed. Electron microscopy scanning revealed mild endothelial cell damage in implanted autogenous arterial grafts on the 1st or 3rd day after grafting. Seven to 14 days after grafting, the endothelial cell layer appeared to be normal.

CONCLUSIONS

It was observed that the endothelial function remained intact and there was an absence of intimal thickening in the arterial grafts. These observations may explain the improved patency of autogenous arterial grafts compared to the vein grafts in aortocoronary revascularization.

Gene therapy for diabetes mellitus

There are diverse strategies for gene therapy of diabetes mellitus. Prevention of beta-cell autoimmunity is a specific gene therapy for prevention of type 1 (insulin-dependent) diabetes in a preclinical stage, whereas improvement in insulin sensitivity of peripheral tissues is a specific gene therapy for type 2 (non-insulin-dependent) diabetes. Suppression of beta-cell apoptosis, recovery from insulin deficiency, and relief of diabetic complications are common therapeutic approaches to both types of diabetes. Several approaches to insulin replacement by gene therapy are currently employed: 1) stimulation of beta-cell growth, 2) induction of beta-cell differentiation and regeneration, 3) genetic engineering of non-beta cells to produce insulin, and 4) transplantation of engineered islets or beta cells. In type 1 diabetes, the therapeutic effect of beta-cell proliferation and regeneration is limited as long as the autoimmune destruction of beta cells continues. Therefore, the utilization of engineered non-beta cells free from autoimmunity and islet transplantation with immunological barriers are considered potential therapies for type 1 diabetes. Proliferation of the patients' own beta cells and differentiation of the patients' own non-beta cells to beta cells are desirable strategies for gene therapy of type 2 diabetes because immunological problems can be circumvented. At present, however, these strategies are technically difficult, and transplantation of engineered beta cells or islets with immunological barriers is also a potential gene therapy for type 2 diabetes.

Feedback inhibition of amidophosphoribosyltransferase regulates the rate of cell growth via purine nucleotide, DNA, and protein syntheses

To clarify the contributions of amidophosphoribosyltransferase (ATase) and its feedback regulation to the rates of purine de novo synthesis, DNA synthesis, protein synthesis, and cell growth, mutated human ATase (mhATase) resistant to feedback inhibition by purine ribonucleotides was engineered by site-directed mutagenesis and expressed in CHO ade (-)A cells (an ATase-deficient cell line of Chinese hamster ovary fibroblasts) and in transgenic mice (mhATase-Tg mice). In Chinese hamster ovary transfectants with mhATase, the following parameters were examined: ATase activity and its subunit structure, the metabolic rates of de novo and salvage pathways, DNA and protein synthesis rates, and the rate of cell growth. In mhATase-Tg mice, ATase activity in the liver and spleen, the metabolic rate of the de novo pathway in the liver, serum uric acid concentration, urinary excretion of purine derivatives, and T lymphocyte proliferation by phytohemagglutinin were examined. We concluded the following. 1) ATase and its feedback inhibition regulate not only the rate of purine de novo synthesis but also DNA and protein synthesis rates and the rate of cell growth in cultured fibroblasts. 2) Suppression of the de novo pathway by the salvage pathway is mainly due to the feedback inhibition of ATase by purine ribonucleotides produced via the salvage pathway, whereas the suppression of the salvage pathway by the de novo pathway is due to consumption of 5-phosphoribosyl 1-pyrophosphate by the de novo pathway. 3) The feedback inhibition of ATase is more important for the regulation of the de novo pathway than that of 5-phosphoribosyl 1-pyrophosphate synthetase. 4) ATase superactivity leads to hyperuricemia and an increased bromodeoxyuridine incorporation in T lymphocytes stimulated by phytohemagglutinin.

Expression of somatostatin receptor subtypes and growth inhibition in human exocrine pancreatic cancers

The antiproliferative effects of somatostatin and its analogs on human pancreatic cancers were studied: (1) by evaluating the gene expression of somatostatin receptor (sstr) subtypes in human pancreatic cancer cell lines and cancer tissue specimens, (2) by evaluating the antiproliferative effects of somatostatin analogs, and (3) by evaluating the effect of sstr-2 cDNA transduction. Using a reverse transcriptase polymerase chain reaction (RT-PCR), the gene expression of five sstr subtypes (sstr-1 to -5) was examined in eight cell lines, and in ten pancreatic cancer tissues and in the normal surrounding pancreatic tissues. The antiproliferative effects of somatostatin (SS) -14 and its two analogs (SMS 201-995, RC-160) were examined by means of an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (thiazolyl blue)) assay on three cell lines and Panc-1 transfectants with human sstr (hsstr)-2A cDNA. Sstr-2 was expressed in all samples tested. All examined cell lines simultaneously expressed sstr-2 and -5, while most of the examined pancreatic cancer tissues did not express both of these subtypes simultaneously. Somatostatin analogs inhibited epidermal growth factor (EGF)-stimulated pancreatic cancer cell proliferation. The cell proliferation was further and significantly inhibited by 14% in stable transfectants of Panc-1 cells with hsstr-2A. Based on these findings, it is concluded that somatostatin analogs with their antiproliferative effects mediated by sstr-2 could be potentially useful in the treatment of pancreatic cancers.

Photodynamic antisense regulation of human cervical carcinoma cell growth using psoralen-conjugated oligo(nucleoside phosphorothioate)

The antisense strategy has been applied to regulate gene expression in a sequence specific manner, which enables suppression of the proliferation of cancer cells and exploration of the functions of unknown genes. In order to generalize and to enhance the ability of the strategy, functionalization of antisense DNAs was done using a photo-crosslinking reagent, 4,5',8-trimethylpsoralen, and the possibility of photodynamic antisense regulation of gene expression was examined. Psoralen-conjugated oligo(nucleoside phosphorothioate)s (Ps-S-oligo) were prepared and used to inhibit the proliferation of human cervical carcinoma cells. Upon UVA irradiation of Ps-S-oligo treated cells, Ps-S-oligo complementary to the initiation codon region (Ps-P-As) of HPV18-E6*-mRNA of human cervical carcinoma cells inhibited drastically the cell growth (IC(50)=16 nM). In contrast, Ps-S-oligo with mismatched sequences and scrambled one showed lesser inhibitory effects than Ps-P-As. These results showed that the inhibition by Ps-S-oligo was dependent on (a) sequence, (b) UVA irradiation, (c) concentration and (d) cell line. The amount of intact HPV18-E6*-mRNA was decreased in a sequence dependent manner, indicating that the antiproliferative effect of Ps-P-As was an antisense manner. The psoralen-conjugated antisense DNA has significant potential to regulate gene expression, which may provide useful information to explore the novel gene regulating reagents.

Novel adhesion prevention membrane based on a bioresorbable copoly(ester-ether) comprised of poly-L-lactide and Pluronic: in vitro and in vivo evaluations

Block copolymers consisting of poly(L-lactide) (PLLA) and poly(oxyethylene-co-oxypropylene), with various compositions, were synthesized and characterized in vitro and in vivo for their application as postoperative adhesion prevention membranes. It was found that the flexibility and degradability of the cast films of the block copolymers grew with increasing Pluronic F68 [PN; poly(oxyethylene-co-oxypropylene] composition. The receding contact angle of the copolymer films against water became lower than that of the PLLA film, because the surface was predominantly covered with more hydrophilic PN segments in a wet state. This surface property significantly affects the cell attachment property of the copolymer films, and the fibroblasts cultured on the films exhibit a spheroid-like morphology. The copolymer films subcutaneously implanted in the back of rats induced milder tissue responses compared with PLLA homopolymers, because of the increased surface hydrophilicity in the former. In vivo evaluation using a uterus horn model in rats revealed that the performance of these copolymer films as an adhesion-prevention membrane is comparable to that of a conventionally utilized membrane of oxidized regenerated cellulose. These results indicate that the copolymer films are biocompatible materials with controllable mechanical properties and biodegradability as adhesion-prevention membranes.

Non-penetrating Vascular Clips Anastomosis Inhibited Intimal Thickening Under Poor Runoff Conditions in Canine Autogenous Vein Grafts

OBJECTIVE

Late graft failure is still a significant problem, particularly in cases with poor runoff vessels. The main cause of late graft failure is intimal thickening of the anastomotic region. Vascular closure system (VCS) clips may provide ideal anastomosis, since they do not penetrate the wall. Therefore, we examined whether the VCS clips affect intimal thickening under poor runoff conditions in the canine autogenous vein grafts.

METHODS

A canine poor runoff model was prepared at both femoral veins. Four weeks after the first surgical procedure, two groups were established according to the two different methods of anastomosis employed. The right femoral vein graft was performed using polypropylene sutures, conventional surgical anastomosis (control group), while the left femoral vein graft was performed using VCS clips anastomosis (VCS group). Four weeks after grafting, the vein grafts were removed and the intimal thickening of proximal, distal anastomosis and midportion of the vein grafts were examined histologically.

RESULTS

In the control group, flow rate and variation were 26+/-8 ml/min and 51+/-10 dynes/cm(2), respectively. In the VCS group, the flow rate and variation were 23+/-11 ml/min and 44+/-14 dynes/cm(2), respectively. There were no significant differences between the two groups. The average value of intimal thickening of both the anastomotic region and the midportion of the vein graft in the VCS group was significantly inhibited compared to that of the control group. The number of positive cells of masson trichrome stain in the VCS group was significantly less than that of the control group.

CONCLUSIONS

These experiments indicate that VCS clips significantly inhibit intimal thickening under poor runoff conditions in canine autogenous vein grafts to a greater extent compared to suture-constructed anastomosis. One mechanism that may account for the decreased intimal thickening is the inhibition of the expression of transforming growth factor-beta (TGF-beta), because the number of positive cells of masson trichrome stain in the VCS group was significantly less than that of the control group.

Diabetes and tumor formation in transgenic mice expressing Reg I

To examine the effect of overexpressed regenerating gene (Reg) I on pancreatic beta-cells, we generated transgenic mice expressing Reg I in islets (Reg-Tg mice). Three lines of Reg-Tg mice were established. In line-1 Reg-Tg mice, the expression level of Reg I mRNA in islets was 7 times higher than those in lines 2 and 3 of Reg-Tg mice, and line 1 mice developed diabetes by apoptosis of beta-cells, as well as various malignant tumors. In addition to the decrease in beta-cells, compensatory islet regeneration and proliferation of ductal epithelial cells were observed in line-1 Reg-Tg mice. Because Reg I protein was secreted primarily into pancreatic ducts from acinar cells, it may primarily stimulate the proliferation of ductal epithelial cells, and not beta-cells, and their differentiation into islets. Moreover, the tumor-promoting activity of Reg I protein should be considered for its possible clinical applications.

Photodynamic antisense regulation using psoralen-conjugated oligo(nucleoside phosphorothioate)s (I). Growth regulation of cervical carcinoma cells

To increase the antisense regulatory effect of oligo(nucleoside phosphorothioate)s (S-Oligo), a photo-crosslinking reagent, 4, 5', 8-trimethylpsoralen, was used in this study. Psoralen-conjugated oligo(nucleoside phosphorothioate) (Ps-S-Oligo) complementary to the human papillomavirus type 18 (HPV18) mRNA drastically inhibited the cellular proliferation of cervical cancer cells only upon UVA-irradiation. In contrast, Ps-S-Oligos with mismatched sequences and scrambled one showed lesser inhibitory effects than that with matched one. These results suggest that psoralen-conjugated antisense S-Oligo has significant potential to regulate gene expression upon UVA-irradiation.

Study on RNA structure by pyrene-labeled 2'-O-methyloligoribonucleotides

Properties of 2'-O-methyloligoribonucleotides containing 2'-O-(1-pyrenylmethyl)uridine were investigated as the fluorescent probe to search the single strand regions on RNA secondary and tertiary structure. The pyrene-labeled 2'-O-methyloligoribonucleotide (OMUpy) showed remarkable increase of fluorescence intensity to 333-fold at 375 nm when hybridized with the complementary oligoribonucleotide. When OMUpy, complementary to loop or stem regions, was applied to E. coli 5S-rRNA, the fluorescence intensities were increased in a sequence specific manner. The difference of the fluorescence intensities corresponds to the higher-order structure of 5S-rRNA, suggesting that pyrene-labled 2'-O-methyloligoribonucleotide can be applicable to search single strand regions of RNA.

The rate of cell growth is regulated by purine biosynthesis via ATP production and G(1) to S phase transition

We recently showed that an increased supply of purine nucleotides increased the growth rate of cultured fibroblasts. To understand the mechanism of the growth rate regulation, CHO K1 (a wild type of Chinese hamster ovary fibroblast cell line) and CHO ade (-)A (a cell line deficient in amidophosphoribosyltransferase, a rate-limiting enzyme of the de novo pathway) were cultured under various conditions. Moreover, a defective de novo pathway in CHO ade (-)A cells was exogenously restored by 5-amino-4-imidazole-carboxamide riboside, a precursor of the de novo pathway. The following parameters were determined: the growth rate of CHO fibroblasts, the metabolic rate of the de novo pathway, the enzyme activities of amidophosphoribosyltransferase and hypoxanthine phosphoribosyltransferase, the content of intracellular nucleotides, and the duration of each cell-cycle phase. We concluded the following: (i) Purine de novo synthesis, rather than purine salvage synthesis or pyrimidine synthesis, limits the growth rate. (ii) Purine nucleotides are synthesized preferentially by the salvage pathway as long as hypoxanthine is available for energy conservation. (iii) The GTP content depends on the intracellular ATP content. (iv) Biosynthesis of purine nucleotides increases the growth rate mainly through ATP production and promotion of the G(1)/S transition.

Yolk sac tumor of the ovary: radiologic-pathologic correlation in four cases

We report the radiologic and pathologic features of yolk sac tumor (endodermal sinus tumor) of the ovary in four patients. Yolk sac tumors were shown as well-enhancing solid tumors on both CT and MR studies and were associated with prominent signal voids on MRI. A hypervascular nature was confirmed on microscopic studies. Areas of hemorrhage were another common characteristic. These imaging findings seem to have an important implication for the diagnosis of this tumor.

[Usefulness of preadmission autologous blood donation and intraoperative autotransfusion using the "cell saver" for the patients with abdominal aortic aneurysm repair]

To evaluate the effectiveness of preadmission autologous blood donation (PABD) and intraoperative autotransfusion (IAT) in reducing the homologous transfusion requirement of abdominal aortic aneurysm (AAA) resection, we retrospectively reviewed 232 AAA cases from January 1991 to December 1999. The patients were separated into three groups. The group I (n = 101) received no PAPD and IAT. The group II (n = 58) received only IAT. The group III (n = 73) received both PAPD and IAT. Surgical data indicating operative time and intraoperative blood loss did not differ among the three groups. However, the incidence of requirement for homologous transfusion in group III (19.2%) is significantly less than those of group I (63.4%) or group II (51.7%), although there was no significant difference between group I and group II. We concluded that the combination of PAPD and IAT are useful for reducing the incidence of requirement for homologous transfusion in the patients with aneurysmal resection.

Successful resection of superior mesenteric artery aneurysm. A case report and review of the literature

Superior mesenteric artery aneurysms are rare, comprising only 8% of all visceral artery aneurysms. Aneurysms at the site are very susceptible to rupture, irrespective of size and may be difficult to manage even in the case of elective surgery. In the absence of serious complicating factors, the treatment of choice is excision of the aneurysm and reconstruction of the artery, if necessary, to maintain patency. We report the successful resection of an aneurysm and the subsequent reconstruction of the superior mesenteric artery which was directly anastomosed to the aorta after resection of an aneurysm.

Linear type azo-containing polyurethane as drug-coating material for colon-specific delivery: its properties, degradation behavior, and utilization for drug formulation

A segmented polyurethane containing azo aromatic groups in the main chain was synthesized by reaction of isophorone diisocyanate with a mixture of m,m'-di(hydroxymethyl)azobenzene, poly(ethylene glycol) (Mn = 2000), and 1,2-propanediol. This polyurethane was soluble in various solvents and showed a good coating and film-forming property. A solution-cast film of this polyurethane was found to be degraded in a culture of intestinal flora with the azo group reduction to hydrazo groups, not to amino groups. The film degradation, therefore, was attributed to the decreased cohesive energy in the hydrazo polymer compared with that in the original azo polymer. Then, the drug pellets containing water-soluble drugs (ONO-3708 and OKY-046) were undercoated with (carboxymethyl)(ethyl)-cellulose and overcoated with the azo polymer in order to examine the drug-releasing profiles in the culture of intestinal flora. The releasing rate of drugs from these double-coating pellets was found to depend on the molecular weight and the composition of the polyurethane used as the overcoat as well as the hydrophilicity of the incorporated drugs. Since the polyurethane was glassy and its segment motion or conformational change is frozen, the structure change should be retarded even after partial reduction of the azo groups, resulting in the effective prevention of the drug leakage. These data suggested that the present azo-containing polyurethanes are applicable as coating material of drug pellets in a colon-targeting delivery system.

Development of new drug delivery system for protein drugs using silicone (I)

A novel technique, by which protein drugs effective in small doses can be released over a long period, was developed using silicone and a water-soluble substance. In this study, interferon (IFN) was used as a model of the protein drugs. The IFN-silicone formulation released IFN over long periods of time in vitro and suppressed tumor growth in nude mice for about 100 days after a single administration. This indicates that physiologically active IFN is released over a prolonged period of time from the IFN-silicone formulation in vivo. Silicone formulations are expected to be a practically feasible sustained-release formulation.

In vitro release of SM-11355, cis[((1R,2R)-1,2-cyclohexanediamine-N,N')bis(myristato)] platinum(II) suspended in lipiodol

SM-11355, cis[((1R,2R)-1,2-cyclohexanediamine-N,N')bis(myristato)] platinum(II) is a lipophilic platinum complex. SM-11355 suspended in Lipiodol (SM-11355/Lipiodol) was previously shown to have antitumor effects against rat hepatic tumors after intra-arterial administration. In the present study, the in vitro release of platinum compounds from SM-11355/Lipiodol was examined. A test tube containing 10 ml of saline and 1 ml of SM-11355/Lipiodol was rotated at 5 rpm in a vertical orientation. The platinum concentration in saline gradually increased for 28 d. From HPLC analysis, cyclohexane-1,2-diamineplatinum(II) dichloride (DPC) and cyclohexane-1,2-diamineplatinum(II) chloroiodide (DPCI) were detected in the saline, and the sum of these two compounds was equivalent to the total platinum amount in the saline determined by atomic absorption spectrophotometry at days 21 and 28. DPC showed significant growth inhibitory activities, with IC50 values of 0.1-0.7 nmol/ml in rat hepatoma AH-109A cells and 5 human tumor cell lines, as effective as cisplatin. These findings suggest that SM-11355/Lipiodol exerts antitumor effects by releasing active platinum compounds, and that DPC is one of the candidates of the active compounds.

In vitro cytotoxicity of cis[((1R,2R)-1,2-cyclohexanediamine-N,N')bis(myristato)] platinum(II) suspended in lipiodol in rat hepatoma AH-109A cells and human tumor cell lines

SM-11355, cis[((1R,2R)-1,2-cyclohexanediamine-N,N ')bis(myristato)] platinum(II), is a lipophilic platinum complex. SM-11355 suspended in Lipiodol (SM-11355/Lipiodol) was shown to have antitumor activity against hepatic tumors after intra-hepatic arterial administration in animal models. In this study, the in vitro growth inhibitory activities of SM-11355 and cisplatin (CDDP) following 7-d drug exposure were examined using rat ascite hepatoma AH-109A cells and various human tumor cell lines. In monolayer or suspension cell cultures, SM-11355 did not inhibit the cell growth, whereas SM-11355/Lipiodol had dose-dependent growth inhibitory activities, as did CDDP suspended in Lipiodol (CDDP/Lipiodol). This was also the case in the colony formation assay in agarose gel. CDDP/Lipiodol released platinum compound into the culture medium rapidly, whereas SM-11355/Lipiodol released it slowly but constantly for 7 d. Furthermore, a significant amount of platinum was detected in the cells treated with CDDP/Lipiodol and SM-11355/Lipiodol. These results suggest that Lipiodol plays an important role in the in vitro cytotoxicity of SM-11355, and certain platinum compounds released from SM-11355/Lipiodol have growth inhibitory effects on these cells.

Improved synthesis of paroxetine hydrochloride propan-2-ol solvate through one of metabolites in humans, and characterization of the solvate crystals

Paroxetine, a potent and selective inhibitor of 5-hydroxytryptamine (serotonin) uptake, was prepared through a piperidine derivative, which was reported to be one of the paroxetine metabolites in humans. Thus, the piperidine derivative was converted to its N-tert-butoxycarbonyl (N-Boc) derivative, which was then converted to N-Boc paroxetine. Paroxetine hydrochloride propan-2-ol (isopropyl alcohol (IPA)) solvate crystals were directly obtained from the N-Boc paroxetine by adding hydrogen chloride to the N-Boc paroxetine IPA solution. The amount of IPA content in the crystals was reduced by drying with a continuous change of powder X-ray diffraction patterns. Other characterizations of the solvate crystals were also conducted.

Molecular cloning and expression analysis of a putative nuclear protein, SR-25

We cloned a full-length mouse cDNA and its human homologue encoding a novel protein designated as "SR-25." In Northern blot analysis, SR-25 mRNA was expressed in all organs tested, and relatively abundant in testis and thymus. Deduced amino acid sequences of mouse SR-25 and human SR-25 showed 77.7% identity. SR-25 has a serine-arginine repeat (SR repeat) and two types of amino acid clusters: a serine cluster and a highly basic cluster. Based on the presence of many nuclear localizing signals and a similarity to RNA splicing proteins, SR-25 is strongly suggested to be a nuclear protein and may contribute to RNA splicing.

Penetration by a huge abdominal aortic aneurysm into the lumbar vertebrae: report of a case

We report herein the case of a 64-year-old man who underwent urgent surgery for a huge abdominal aortic aneurysm (AAA) with severe lumbago. At surgery, a defect in the posterior wall of the AAA, through which the adjacent lumbar vertebrae was seen after removal of intraluminal thrombi, was encountered with no evidence of blood leakage. This is a rare case of AAA that eroded the posterior wall and exposed the vertebrae.

Antitumor effects of a novel lipophilic platinum complex (SM-11355) against a slowly-growing rat hepatic tumor after intra-hepatic arterial administration

The antitumor effects of cis[((1R,2R)-1,2-cyclohexanediamine-N,N')bis(myristato)] platinum(II) (SM-11355) were evaluated in a rat hepatic tumor model, and were compared with those of cisplatin (CDDP). A novel slowly-growing rat hepatic tumor model was established by the successive transplantation of rat AH109A tumor into the liver. The drugs, which were suspended in Lipiodol, were administered into the proper hepatic artery of tumor-bearing rats. Tumor growth was suppressed in the group that received SM-11355 suspended in Lipiodol (SM-11355/Lipiodol). Mean tumor growth rates in the groups administered 20 microl of Lipiodol containing 0, 0.02, 0.04, 0.1, 0.2, or 0.4 mg of SM-11355 were 244, 86, 110, 81, 51, and 40%, respectively, 1 week after treatment. Those in the groups administered 20 microl of Lipiodol containing 0.1, 0.2, or 0.4 mg of CDDP were 240, 110, and 45%, respectively. In the groups administered 0.2 and 0.4 mg of SM-11355 or 0.4 mg of CDDP, massive necrosis was observed in the tumor tissue 1 week after drug administration, and the tumors disappeared 4 weeks after drug administration. Serum glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) levels were measured as markers of liver damage one day after the drug was administered into the hepatic artery of rats. The minimum toxic dose, which raised serum GOT and GPT levels significantly compared with Lipiodol alone, was 0.2 mg for SM-11355/Lipiodol and 0.1 mg for CDDP/Lipiodol, respectively. The results demonstrated that SM-11355/Lipiodol exerted antitumor activity at a dose that showed no hepatic toxicity in the rat model, but CDDP/Lipiodol did not.

Diabetes and pancreatic tumours in transgenic mice expressing Pa x 6

AIMS/HYPOTHESIS

Both endocrine and exocrine cells of the pancreas differentiate from epithelial cells of primitive pancreatic ducts, and four types of pancreatic islet cells (alpha, beta, delta, and PP cells) are derived from the common pluripotent precursor cells. Although Pa x 6 is expressed in all islet cells, Pa x 4 is detected only in beta cells. In homozygous Pa x 4-null mice, beta cells are absent, whereas the number of alpha cells is increased. Therefore, we hypothesized that the balance of Pa x 4 and 6 is one of the determinants by which the common progenitor cells differentiate into alpha or beta cells.

METHODS

To change this balance, we generated transgenic mice overexpressing Pa x 6 driven by the insulin promoter or the PDX1 promoter.

RESULTS

In both types of transgenic mice, normal development of beta cells was disturbed, resulting in apoptosis of beta cells and diabetes. In Insulin/Pa x 6-Tg mice, beta cells were specifically affected, whereas in PDX/Pa x 6-Tg mice, developmental abnormalities involved the whole pancreas including hypoplasia of the exocrine pancreas. Furthermore, PDX/Pa x 6-Tg mice experienced proliferation of both ductal epithelia and islet cells and subsequent cystic adenoma of the pancreas.

CONCLUSION/INTERPRETATION

These findings suggest that Pa x 6 promotes the growth of ductal epithelia and endocrine progenitor cells and that the suppression of Pa x 6 is necessary for the normal development of beta cells and the exocrine pancreas.

Molecular cloning and tissue-specific expression of a new member of the regenerating protein family, islet neogenesis-associated protein-related protein

Islet neogenesis-associated protein (INGAP) is a protein expressed during islet neogenesis. We have cloned a novel cDNA having a similar sequence to INGAP cDNA. The cDNA encodes 175 amino acids designated INGAP-related protein (INGAPrP). INGAP is expressed in cellophane-wrapped pancreas, but not in normal pancreas, whereas INGAPrP was abundantly expressed in normal pancreas.

Biologic and binding activities of IFN-alpha subtypes in ACHN human renal cell carcinoma cells and Daudi Burkitt's lymphoma cells

Nine interferon-alpha subtypes, IFN-alpha1, IFN-alpha2, IFN-alpha5, IFN-alpha7, IFN-alpha8, IFN-alpha10, IFN-alpha14, IFN-alpha17, and IFN-alpha21, were separated from purified human lymphoblastoid IFN. We tested their inhibitory effects on cell growth and replication of Semliki Forest virus (SFV) and vesicular stomatitis virus (VSV) and their induction of 2',5'-oligoadenylate synthetase (2', 5'-OAS) in ACHN renal cell carcinoma cells. In terms of all three activities, the nine subtypes had similar relative activities, with IFN-alpha10 the most active and IFN-alpha1 the least. Their relative effects on cell growth were similar in two other human cell lines, SK-LU-1 lung cancer cells and KU-2 renal cell carcinoma cells, whereas cells of the Daudi Burkitt lymphoma line behaved quite differently, being highly sensitive to all the nine subtypes. The relative effects with ACHN cells correlated well with their relative binding affinities. However, each of the subtypes bound to both ACHN and Daudi cells to almost the same extent. This suggests that their profound inhibitory effects on the growth of Daudi cells are amplified at some stage in the signal transduction pathway or in the expression of genes that results from binding to the IFN-alpha receptor.

Lymphocytic hypophysitis presenting with diabetes insipidus: MR findings

It has been thought that neurohypophysial involvement manifesting as central diabetes insipidus in lymphocytic hypophysitis is rare. The radiological and clinicopathological features of two cases represent a variant of lymphocytic adenohypophysitis and/or lymphocytic infundibulo-neurohypophysitis are discussed.

[Evaluation of amrubicin with a 5 day administration schedule in a mouse model]

It was reported that amrubicin hydrochloride (9-aminoanthracycline SM-5887), showed a higher therapeutic activity than doxorubicin against human tumor xenografts implanted into nude mice with a single treatment schedule. In order to find a more effective treatment schedule, the efficacy, toxicity and pharmacokinetic properties with a 5 consecutive day treatment schedule were investigated. The total amount of the maximum tolerated dose and tumor growth inhibiting activity with a 5 day schedule was found to be higher than with a single administration. High levels of amrubicinol, the active metabolite of amrubicin, was detected in the tumor tissue. It was thus assumed that the improved efficacy with the 5-day schedule resulted from the high accumulation of amrubicinol. Bone marrow suppression at the MTD with the 5 day schedule was severer than with a single dose, but recovery was rapid, similar to that following a single dose. In conclusion, it was demonstrated that a 5 day treatment schedule was more effective than a single administration.

[Usefulness of endovascular grafting for abdominal aortic aneurysm]

The purpose of this study was to determine the usefulness of endovascular grafting for abdominal aortic aneurysm (AAA) compared to conventional open repair. During the period from May 1998 through to April 1999, 16 patients (control group) with AAA underwent conventional open surgery and 6 patients (stent group) underwent endovascular grafting. Surgical data including operative time and intraoperative blood loss did not differ between the two groups. However, the postoperative parameters including the initiation of oral intake, the onset of flatus and the permission to walk were significantly sooner in the stent group than the control group. The postoperative changes of coagulopathy-fibrinolytic factor were comparable between the two groups. We conclude that the endovascular grafting is minimally invasive compared to conventional open surgery. In addition, there was no consumption coagulopathy in the endovascular grafting. However, it was necessary to develop new approach with new devices in order to perform endovascular grafting more safely.

2'-Pyrene modified oligonucleotide provides a highly sensitive fluorescent probe of RNA

Oligonucleotide 9mers containing 2'-O-(1-pyrenylmethyl)uridine [U(pyr)] at the center position were synthesized by using a protected U(pyr) phosphoramidite. The UV melting behaviors indicate that the pyrene-modified oligonucleotides can bind to both their complementary DNA and RNA in aqueous solution. When compared with the unmodified oligonucleotides, the pyrene-modified oligonucleotides showed higher affinity for DNA while exhibiting lower affinity for RNA. The pyrene-modified oligonucleotides in diluted solution exhibited fluorescence typical of pyrene monomer emission [lambdamax 378 (band I) and 391 nm (band III)]. When these oligomers bound to DNA, the fluorescence intensity ratio of band III/band I was increased. With this fluorescence change, a new broad emission (lambdamax 450 nm) due to exciplex between the pyrene and an adjacent nucleobase appeared. In contrast, addition of RNA to the pyrene oligonucleotides resulted in enhancement of the pyrene monomer emission with decrease in the fluorescence band ratio. The extent of the emission enhancement was found to be highly dependent on the nucleobase adjacent to the U(pyr) in the pyrene oligomers. The pyrene oligonucleotide containing dC at the 3'-site of the modification showed remarkable increase (approximately 250 times) in fluorescence (375 nm) upon binding to complementary RNA. The present findings would open the way to the design of a highly sensitive fluorescent probe of RNA.

Uptake and intracellular distribution of amrubicin, a novel 9-amino-anthracycline, and its active metabolite amrubicinol in P388 murine leukemia cells

Amrubicin, a 9-aminoanthracycline anti-cancer drug, and its C-13 hydroxyl metabolite amrubicinol, were examined for growth-inhibitory activity as well as cellular uptake and distribution in P388 murine leukemia cells and doxorubicin-resistant P388 cells. Also discussed are the differences in the mechanisms of action among amrubicin, amrubicinol and doxorubicin in terms of their cellular pharmacokinetic character. In P388 cells, amrubicinol was about 80 times as potent as amrubicin, and about 2 times more potent than doxorubicin in a 1-h drug exposure growth-inhibition test. A clear cross-resistance was observed to both amrubicin and amrubicinol in doxorubicin-resistant P388 cells, though the resistance index was lower for amrubicin. The intracellular concentration of amrubicinol was about 6 times and 2 times higher than those of amrubicin and doxorubicin, respectively. Compared to doxorubicin, amrubicin and amrubicinol were released rapidly after removal of the drugs from the medium. A clear correlation was found between the growth-inhibiting activity and the cellular level of amrubicin and amrubicinol in P388 cells. About 10 to 20% of amrubicin or amrubicinol taken up by the cells was detected in the cell nuclear fraction, whereas 70 to 80% of doxorubicin was localized in this fraction. These results suggest that amrubicin and amrubicinol exert cytotoxic activity via a different mechanism from that of doxorubicin.

Synthesis and properties of malic acid-containing functional polymers

Poly-L-lactides containing beta-alkyl alpha-malate-units were prepared by ring-opening copolymerizations of L-lactide with 3-(s)-[(benzyloxycarbonyl)methyl]- (BMD) and 3-(s)-[(dodecyloxycarbonyl)methyl]-1,4-dioxane-2,5-diones (DMD). The solution-cast films of these copolymers were alkali-treated to form a carboxyl-functionalized surface on which cell-binding Arg-Gly-Asp tripeptide (RGD) was immobilized with dicyclohexylcarbodiimide as coupling agent. For the copolymer of L-lactide and BMD the benzyl groups were removed by catalytic hydrogenolysis to obtain a fully carboxyl-functionalized copolymer (PLGM), and RGD was immobilized on the surface of its cast film. All the RGD-immobilized films thus prepared exhibited improved cell attachment compared with the original films. The cell attachment increased with increasing amount of immobilized RGD, which depended on the composition of the alpha-malate units in the copolymer. The RGD-immobilized PLGM films were degraded rapidly during the cell culture, while the RGD-immobilized films of the beta-alkyl alpha-malate-containing polymers survived the cell culture with little degradation. The rate of hydrolysis increased with increasing content of alpha-malate units for both series, depending on the structure of the protecting groups of the beta-carboxyl. These results suggest that the RGD-immobilized polymers could be a new class of functional bioresorbable polymer having improved cell-attachment and adjustable hydrolysis rate.

Apoptosis and remodelling of beta cells by paracrine interferon-gamma without insulitis in transgenic mice

AIMS/HYPOTHESIS

To examine whether interferon-gamma destroys islet beta cells directly or indirectly through lymphocyte activation, or whether direct action of interferon-gamma on beta cells by itself induces diabetes without insulitis.

METHODS

To avoid possible nonspecific breakdown of beta cells by transgenic overexpression of interferon-gamma by the insulin promoter, we generated transgenic mice expressing interferon-gamma under the control of rat glucagon promoter (RGP-IFN-gamma-Tg mice).

RESULTS

The absence of insulitis in RGP-IFN-gamma-Tg mice enabled us to investigate the direct effects of paracrine interferon-gamma. In RGP-IFN-gamma-Tg mice, serum concentrations of interferon-gamma and tumour necrosis factor-alpha (TNF-alpha) were 50 and 6 times higher than those in their littermates, respectively, and glucose-responsive insulin secretion decreased to one-half the level of that in the littermates. Transgenic interferon-gamma induced remodelling of beta cells where apoptosis of many beta cells was compensated by their vigorous regeneration and diabetes did not occur in most of the RGP-IFN-gamma-Tg mice.

CONCLUSION/INTERPRETATION

Interferon-gamma alone is insufficient for the complete destruction of beta cells in vivo, and factors other than interferon-gamma including activated lymphocytes or other cytokines, are necessary in addition to interferon-gamma for the development of Type I (insulin-dependent) diabetes mellitus.

Development of pancreatic islets (review)

Recent studies have revealed that islet cells differentiate from the epithelial cells of primitive pancreatic ducts during embryogenesis, and can regenerate in response to the loss of islet cells even in adult pancreas. The ability of islet cells to regenerate raises the possibility that impaired and decreased islets of diabetic patients can be restored. In this review, factors regulating islet development including differentiation factors (Shh, activin, follistatin, and TGF alpha), transcriptional factors (PDX1, Isl1, Pax4, Pax6, Nkx2.2, Nkx6.1, BETA2, and HNF), growth factors (the EGF family, HGF, IGF-I, IGF-II, Reg, INGAP, PDGF, FGF, VEGF, and NGF), hormones (insulin, the GH family, PTHrP, TRH, and gastrin), and cell adhesion molecules (N-CAM and cadherins) are described after a short introduction and an outline of pancreatic development.

Infrequent detectable somatic mutations of the RET and glial cell line-derived neurotrophic factor (GDNF) genes in human pituitary adenomas

RET is a receptor tyrosine kinase expressed in neuroendocrine cells and tumors. RET is activated by a ligand complex comprising glial cell line-derived neurotrophic factor (GDNF) and GDNF receptor-alpha (GDNFR-alpha). Activating mutations of the RET proto-oncogene were found in multiple endocrine neoplasia (MEN) 2 and in sporadic medullary thyroid carcinoma and pheochromocytoma of neuroendocrine origin. Mutations of the RET proto-oncogene and the glial cell line-derived neurotrophic factor (GDNF) gene were examined in human pituitary tumors. No mutations of the RET proto-oncogene including the cysteine-rich region or codon 768 and 918 in the tyrosine kinase domain were detected in 172 human pituitary adenomas either by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) or by PCR-restriction fragment length polymorphism (RFLP). Further, somatic mutations of the GDNF gene in 33 human pituitary adenomas were not detected by PCR-SSCP. One polymorphism of the GDNF gene at codon 145 of TGC or TGT was observed in a prolactinoma. The RET proto-oncogene message was detected in a normal human pituitary gland or 4 of 4 human pituitary adenomas with reverse transcription (RT)-PCR, and in rodent pituitary tumor cell lines with Western blotting. The expression of GDNF gene was detected in 1 of 4 human somatotroph adenomas, 1 of 2 corticotroph adenomas, and 2 of 6 rodent pituitary tumor cell lines with RT-PCR. Based on these, it is concluded that somatic mutations of the RET proto-oncogene or the GDNF gene do not appear to play a major role in the pituitary tumorigenesis in examined tumors.