Combined treatment with glucagon-like peptide-1 receptor agonist exendin-4 and metformin attenuates breast cancer growth.

Cancer is a major cause of death in patients with diabetes. Incretin therapy has received much attention because of its tissue-protective effects. We have previously reported an anti-breast cancer effect of glucagon-like peptide-1 receptor agonist exendin-4 (Ex-4). An anti-cancer effect of metformin is well recognized. Therefore, we examined the effect of combined treatment with Ex-4 and metformin in breast cancer cells. In human breast cancer cell lines MCF-7, MDA-MB-231, and KPL-1, 0.1-10 mM metformin significantly reduced the cell number in growth curve analysis in a dose-dependent manner. Furthermore, combined treatment with 0.1 mM metformin and 10 nM Ex-4 additively attenuated the growth curve progression of breast cancer cells. In a bromodeoxyuridine (BrdU) assay, Ex-4 or metformin significantly decreased breast cancer cell proliferation and further reduction of BrdU incorporation was observed by combined treatment with Ex-4 and metformin, which suggested that Ex-4 and metformin additively decreased DNA synthesis in breast cancer cells. Although apoptotic cells were not observed among Ex-4-treated breast cancer cells, apoptotic cells were clearly detected among metformin-treated breast cancer cells by apoptosis assays. Furthermore, metformin decreased BCL-2 expression in MCF-7 cells. In vivo experiments using a xenograft model showed that Ex-4 and metformin significantly decreased the breast tumor weight and Ki67-positive proliferative cancer cells, and metformin reduced the serum insulin level in mice. These data suggested that Ex-4 and metformin attenuated cell proliferation and metformin induced apoptosis in breast cancer cells. Combined treatment of Ex-4 and metformin may be an optional therapy to inhibit breast cancer progression.

Sodium-glucose cotransporter 2 inhibitor canagliflozin attenuates lung cancer cell proliferation in vitro.

Cancer is a major cause of death in patients with type 2 diabetes mellitus (T2DM) and lung cancer is one of the most prevalent cancers in patients with T2DM. In the present study, we examined the anti-cancer effect of the Sodium-glucose cotransporter 2 (SGLT2) inhibitor, canagliflozin, using a lung cancer model. In lung cancer tissues from non-T2DM human subjects, SGLT2 was detected by immunohistochemistry. SGLT2 mRNA and protein were also detected in A549, H1975 and H520 lung cancer cell lines by RT-PCR and immunohistochemistry, respectively. Canagliflozin at 1-50 µM significantly suppressed the growth of A549 cells in a dose-dependent manner. In BrdU assays, canagliflozin attenuated the proliferation of A549 cells, but did not induce apoptosis. In cell cycle analysis, S phase entry was attenuated by canagliflozin in A549 cells. In in vivo experiments, a xenograft model of athymic mice implanted with A549 lung cancer cells was treated with low and high dose oral canagliflozin. Despite the results of the in vitro experiments, tumor weight was not decreased by canagliflozin. In addition, the serum insulin level, but not body weight or blood glucose level, was decreased by canagliflozin. The number of cells positive for Ki67 was slightly decreased by canagliflozin, but this was not statistically significant. In conclusion, SGLT2 is expressed in human lung cancer tissue and cell lines, and the SGLT2 inhibitor, canagliflozin, attenuated proliferation of A549 lung cancer cells by inhibiting cell cycle progression in vitro but not in vivo.

Pemafibrate, a PPAR alpha agonist, attenuates neointima formation after vascular injury in mice fed normal chow and a high-fat diet.

Recently, the prevention of cardiovascular events has become one of the most important aims of diabetes care. Peroxisome proliferator-activated receptor (PPAR) agonists have been reported to have vascular protective effects. Here, we examined whether pemafibrate, a selective PPAR alpha agonist, attenuated neointima formation after vascular injury and vascular smooth muscle cell (VSMC) proliferation. We performed endothelial denudation injury in mice treated with a high-fat diet (HFD) or normal chow. Orally administered pemafibrate significantly attenuated neointima formation after vascular injury in HFD and normal chow mice. Interestingly, pemafibrate increased the serum fibroblast growth factor 21 concentration and decreased serum insulin concentrations in HFD mice. In addition, body weight was slightly but significantly decreased by pemafibrate in HFD mice. Pemafibrate, but not bezafibrate, attenuated VSMC proliferation in vitro. The knockdown of PPAR alpha abolished the anti-VSMC proliferation effect of pemafibrate. BrdU assay results revealed that pemafibrate dose-dependently inhibited DNA synthesis in VSMCs. Flow cytometry analysis demonstrated that G1-to-S phase cell cycle transition was significantly inhibited by pemafibrate. Pemafibrate attenuated serum-induced cyclin D1 expression in VSMCs. However, apoptosis was not induced by pemafibrate as assessed by the TUNEL assay. Similar to the in vitro data, VSMC proliferation was also decreased by pemafibrate in mice. These data suggest that pemafibrate attenuates neointima formation after vascular injury and VSMC proliferation by inhibiting cell cycle progression.

Activation of overexpressed glucagon-like peptide-1 receptor attenuates prostate cancer growth by inhibiting cell cycle progression.

AIMS/INTRODUCTION: Incretin therapy is a common treatment for type 2 diabetes mellitus. We have previously reported an anti-prostate cancer effect of glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4. The attenuation of cell proliferation in the prostate cancer cell line was dependent on GLP-1R expression. Here, we examined the relationship between human prostate cancer severity and GLP-1R expression, as well as the effect of forced expression of GLP-1R using a lentiviral vector. MATERIALS AND METHODS: Prostate cancer tissues were extracted by prostatectomy and biopsy. GLP-1R was overexpressed in ALVA-41 cells using a lentiviral vector (ALVA-41-GLP-1R cells). GLP-1R expression was detected by immunohistochemistry and quantitative polymerase chain reaction. Cell proliferation was examined by growth curves and bromodeoxyuridine incorporation assays. Cell cycle distribution and regulators were examined by flow cytometry and western blotting. In vivo experiments were carried out using a xenografted model. RESULTS: GLP-1R expression levels were significantly inversely associated with the Gleason score of human prostate cancer tissues. Abundant GLP-1R expression and functions were confirmed in ALVA-41-GLP-1R cells. Exendin-4 significantly decreased ALVA-41-GLP-1R cell proliferation in a dose-dependent manner. DNA synthesis and G1-to-S phase transition were inhibited in ALVA-41-GLP-1R cells. SKP2 expression was decreased and p27Kip1 protein was subsequently increased in ALVA-41-GLP-1R cells treated with exendin-4. In vivo experiments carried out by implanting ALVA-41-GLP-1R cells showed that exendin-4 decreased prostate cancer growth by activation of GLP-1R overexpressed in ALVA41-GLP-1R cells. CONCLUSIONS: Forced expression of GLP-1R attenuates prostate cancer cell proliferation by inhibiting cell cycle progression in vitro and in vivo. Therefore, GLP-1R activation might be a potential therapy for prostate cancer.

SGLT2 inhibitor ipragliflozin attenuates breast cancer cell proliferation.

Cancer is currently one of the major causes of death in patients with type 2 diabetes mellitus. We previously reported the beneficial effects of the glucagon-like peptide-1 receptor agonist exendin-4 against prostate and breast cancer. In the present study, we examined the anti-cancer effect of the sodium-glucose cotransporter 2 (SGLT2) inhibitor ipragliflozin using a breast cancer model. In human breast cancer MCF-7 cells, SGLT2 expression was detected using both RT-PCR and immunohistochemistry. Ipragliflozin at 1-50 µM significantly and dose-dependently suppressed the growth of MCF-7 cells. BrdU assay also revealed that ipragliflozin attenuated the proliferation of MCF-7 cells in a dose-dependent manner. Because the effect of ipragliflozin against breast cancer cells was completely canceled by knocking down SGLT2, ipragliflozin could act via inhibiting SGLT2. We next measured membrane potential and whole-cell current using the patch clamp technique. When we treated MCF-7 cells with ipragliflozin or glucose-free medium, membrane hyperpolarization was observed. In addition, glucose-free medium and knockdown of SGLT2 by siRNA suppressed the glucose-induced whole-cell current of MCF-7 cells, suggesting that ipragliflozin inhibits sodium and glucose cotransport through SGLT2. Furthermore, JC-1 green fluorescence was significantly increased by ipragliflozin, suggesting the change of mitochondrial membrane potential. These findings suggest that the SGLT2 inhibitor ipragliflozin attenuates breast cancer cell proliferation via membrane hyperpolarization and mitochondrial membrane instability.

Combined treatment with DPP-4 inhibitor linagliptin and SGLT2 inhibitor empagliflozin attenuates neointima formation after vascular injury in diabetic mice.

Incretin therapy has emerged as one of the most popular medications for type 2 diabetes. We have previously reported that the dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin attenuates neointima formation after vascular injury in non-diabetic mice. In the present study, we examined whether combined treatment with linagliptin and the sodium glucose cotransporter 2 (SGLT2) inhibitor empagliflozin attenuates neointima formation in diabetic mice after vascular injury. Diabetic db/db mice were treated with 3 mg/kg/day linagliptin and/or 30 mg/kg/day empagliflozin from 5 to 10 weeks of age. Body weight was significantly decreased by empagliflozin and the combined treatment. Blood glucose levels and glucose tolerance test results were significantly improved by empagliflozin and the combined treatment, but not by linagliptin. An insulin tolerance test suggested that linagliptin and empagliflozin did not improve insulin sensitivity. In a model of guidewire-induced femoral artery injury in diabetic mice, neointima formation was significantly decreased in mice subjected to combined treatment. In an in vitro assay using rat aortic smooth muscle cells (RASMC), 100, 500, or 1000 nM empagliflozin significantly decreased the RASMC number in a dose-dependent manner. A further significant reduction in RASMC proliferation was observed after combined treatment with 10 nM linagliptin and 100 nM empagliflozin. These data suggest that combined treatment with the DPP-4 inhibitor linagliptin and SGLT2 inhibitor empagliflozin attenuates neointima formation after vascular injury in diabetic mice in vivo and smooth muscle cell proliferation in vitro.

GLP-1 Receptor Agonist Exendin-4 Attenuates NR4A Orphan Nuclear Receptor NOR1 Expression in Vascular Smooth Muscle Cells.

AIMS: Recently, incretin therapy has attracted increasing attention because of its potential use in tissue-protective therapy. Neuron-derived orphan receptor 1 (NOR1) is a nuclear orphan receptor that regulates vascular smooth muscle cell (VSMC) proliferation. In the present study, we investigated the vascular-protective effect of Exendin-4 (Ex-4), a glucagon-like peptide-1 receptor agonist, by inhibiting NOR1 expression in VSMCs. METHODS: We classified 7-week-old male 129X1/SvJ mice into control group and Ex-4 low- and high-dose-treated groups fed normal or high-fat diets, respectively. Endothelial denudation injuries were induced in the femoral artery at 8 weeks of age, followed by the evaluation of neointima formation at 12 weeks of age. To evaluate VSMC proliferation, bromodeoxyuridine incorporation assay and cell cycle distribution analysis were performed. NOR1 and cell cycle regulators were detected using immunohistochemistry, western blotting, quantitative reverse-transcription polymerase chain reaction, and luciferase assays. RESULTS: Ex-4 treatment reduced vascular injury-induced neointima formation compared with controls. In terms of VSMCs occupying the neointima area, VSMC numbers and NOR1-expressing proliferative cells were significantly decreased by Ex-4 in a dose-dependent manner in both diabetic and non-diabetic mice. In vitro experiments using primary cultured VSMCs revealed that Ex-4 attenuated NOR1 expression by reducing extracellular signal-regulated kinase-mitogen-activated protein kinase and cAMP-responsive element-binding protein phosphorylations. Furthermore, in the cell cycle distribution analysis, serum-induced G1-S phase entry was significantly attenuated by Ex-4 treatment of VSMCs by inhibiting the induction of S-phase kinase-associated protein 2. CONCLUSION: Ex-4 attenuates neointima formation after vascular injury and VSMC proliferation possibly by inhibiting NOR1 expression.

Selective Androgen Receptor Modulator S42 Suppresses Prostate Cancer Cell Proliferation.

We previously identified the selective androgen receptor (AR) modulator S42, which does not stimulate prostate growth but has a beneficial effect on lipid metabolism. In the prostate cancer (PC) cell line LNCaP, S42 did not induce AR transactivation but antagonized 5α-dihydrotestosterone (DHT)‒induced AR activation. Next, we investigated whether S42 suppresses the growth of PC cell lines. Basal growth of LNCaP cells was significantly suppressed by treatment with S42 compared with vehicle, as determined by cell counting and 5-bromo-2'-deoxyuridine assays. The suppressive effect of S42 on cell growth was evident in the AR-positive PC cells LNCaP and 22Rv1 and was slightly observed even in the AR-negative PC-3 cells. However, S42 did not induce apoptosis as determined by the terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assay. S42 had an even greater suppressive effect on DHT-dependent LNCaP cell proliferation than on basal proliferation (P < 0.05). DHT treatment increased the expression of phosphorylated extracellular signal-regulated kinase (ERK)-mitogen-activated protein kinase (MAPK), a major signaling molecule for PC proliferation, and this was significantly inhibited by S42. DHT also significantly upregulated AR, insulinlike growth factor-1 receptor (IGF-1R), and insulin receptor (IR)-ß protein levels, which were similarly reduced by S42 treatment. Importantly, S42 administration to mice attenuated the growth of LNCaP tumors and reduced tumor expression of the prostate-specific antigen, P504S, Ki67, and phosphorylated ERK-MAPK. These data suggest that S42 attenuates LNCaP tumor growth not by inducing apoptosis but by inhibiting the expression of proliferation-related receptors, including IGF-1R, IR, and AR, and by suppressing ERK-MAPK activation. S42 may thus be a feasible candidate for PC treatment.

Impact of metabolic disorders on prostate cancer growth: Androgen and insulin resistance perspectives.

Background: A high prevalence of cancers in metabolic disorders, like metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM), recently has been noted, including prostate cancer (PC), which is androgen-sensitive. However, the pathological relationship among testosterone and insulin and insulin-like growth factor (IGF)-1 signaling in relation to MetS and T2DM with PC remains unclear. Methods: Papers were reviewed, including those by the authors. Results: In MetS or the initial stage of T2DM accompanying insulin resistance, insulin and IGF-1 signaling could be essential for PC growth. In the advanced stage of T2DM, the decrease in insulin secretion might work against PC growth. A decrease in testosterone concentration with T2DM also might suppress PC proliferation. Androgen deprivation therapy in patients with PC might increase the risk of MetS and/or T2DM and consequently cardiovascular events. Certain drugs for T2DM treatment, such as metformin and glucagon-like peptide-1 analog, potentially might be useful for the treatment of PC. Conclusion: The improvement of insulin resistance appears to be essential for the prevention of PC growth. Further studies are needed to clarify the complicated pathophysiology of metabolic disorders in PC growth.

Exendin-4, a Glucagonlike Peptide-1 Receptor Agonist, Attenuates Breast Cancer Growth by Inhibiting NF-κB Activation.

Incretin therapies have received much attention because of their tissue-protective effects, which extend beyond those associated with glycemic control. Cancer is a primary cause of death in patients who have diabetes mellitus. We previously reported antiprostate cancer effects of the glucagonlike peptide-1 (GLP-1) receptor (GLP-1R) agonist exendin-4 (Ex-4). Breast cancer is one of the most common cancers in female patients who have type 2 diabetes mellitus and obesity. Thus, we examined whether GLP-1 action could attenuate breast cancer. GLP-1R was expressed in human breast cancer tissue and MCF-7, MDA-MB-231, and KPL-1 cell lines. We found that 0.1 to 10 nM Ex-4 significantly decreased the number of breast cancer cells in a dose-dependent manner. Although Ex-4 did not induce apoptosis, it attenuated breast cancer cell proliferation significantly and dose-dependently. However, the dipeptidyl peptidase-4 inhibitor linagliptin did not affect breast cancer cell proliferation. When MCF-7 cells were transplanted into athymic mice, Ex-4 decreased MCF-7 tumor size in vivo. Ki67 immunohistochemistry revealed that breast cancer cell proliferation was significantly reduced in tumors extracted from Ex-4-treated mice. In MCF-7 cells, Ex-4 significantly inhibited nuclear factor κB (NF-κB ) nuclear translocation and target gene expression. Furthermore, Ex-4 decreased both Akt and IκB phosphorylation. These results suggest that GLP-1 could attenuate breast cancer cell proliferation via activation of GLP-1R and subsequent inhibition of NF-κB activation.

Augmented Growth Hormone Secretion and Stat3 Phosphorylation in an Aryl Hydrocarbon Receptor Interacting Protein (AIP)-Disrupted Somatotroph Cell Line.

Aryl hydrocarbon receptor interacting protein (AIP) is thought to be a tumor suppressor gene, as indicated by a mutational analysis of pituitary somatotroph adenomas. However, the physiological significance of AIP inactivation in somatotroph cells remains unclear. Using CRISPR/Cas9, we identified a GH3 cell clone (termed GH3-FTY) in which Aip was genetically disrupted, and subsequently investigated its character with respect to growth hormone (Gh) synthesis and proliferation. Compared with GH3, GH3-FTY cells showed remarkably increased Gh production and a slight increase in cell proliferation. Gh-induced Stat3 phosphorylation is known to be a mechanism of Gh oversecretion in GH3. Interestingly, phosphorylated-Stat3 expression in GH3-FTY cells was increased more compared with GH3 cells, suggesting a stronger drive for this mechanism in GH3-FTY. The phenotypes of GH3-FTY concerning Gh overproduction, cell proliferation, and increased Stat3 phosphorylation were significantly reversed by the exogenous expression of Aip. GH3-FTY cells were less sensitive to somatostatin than GH3 cells in the suppression of cell proliferation, which might be associated with the reduced expression of somatostatin receptor type 2. GH3-FTY xenografts in BALB/c nude mice (GH3-FTY mice) formed more mitotic somatotroph tumors than GH3 xenografts (GH3 mice), as also evidenced by increased Ki67 scores. GH3-FTY mice were also much larger and had significantly higher plasma Gh levels than GH3 mice. Furthermore, GH3-FTY mice showed relative insulin resistance compared with GH3 mice. In conclusion, we established a somatotroph cell line, GH3-FTY, which possessed prominent Gh secretion and mitotic features associated with the disruption of Aip.

Combined Treatment with Exendin-4 and Metformin Attenuates Prostate Cancer Growth.

INTRODUCTION: Recently, the pleiotropic benefits of incretin-based therapy have been reported. We have previously reported that Exendin-4, a glucagon-like peptide-1 (GLP-1) receptor agonist, attenuates prostate cancer growth. Metformin is known for its anti-cancer effect. Here, we examined the anti-cancer effect of Exendin-4 and metformin using a prostate cancer model. METHODS: Prostate cancer cells were treated with Exendin-4 and/or metformin. Cell proliferation was quantified by growth curves and 5-bromo-2'-deoxyuridine (BrdU) assay. TUNEL assay and AMP-activated protein kinase (AMPK) phosphorylation were examined in LNCaP cells. For in vivo experiments, LNCaP cells were transplanted subcutaneously into the flank region of athymic mice, which were then treated with Exendin-4 and/or metformin. TUNEL assay and immunohistochemistry were performed on tumors. RESULTS: Exendin-4 and metformin additively decreased the growth curve, but not the migration, of prostate cancer cells. The BrdU assay revealed that both Exendin-4 and metformin significantly decreased prostate cancer cell proliferation. Furthermore, metformin, but not Exendin-4, activated AMPK and induced apoptosis in LNCaP cells. The anti-proliferative effect of metformin was abolished by inhibition or knock down of AMPK. In vivo, Exendin-4 and metformin significantly decreased tumor size, and further significant tumor size reduction was observed after combined treatment. Immunohistochemistry on tumors revealed that the P504S and Ki67 expression decreased by Exendin-4 and/or metformin, and that metformin increased phospho-AMPK expression and the apoptotic cell number. CONCLUSION: These data suggest that Exendin-4 and metformin attenuated prostate cancer growth by inhibiting proliferation, and that metformin inhibited proliferation by inducing apoptosis. Combined treatment with Exendin-4 and metformin attenuated prostate cancer growth more than separate treatments.

Dipeptidyl peptidase-4 inhibitor linagliptin attenuates neointima formation after vascular injury.

BACKGROUND: Recently, glucagon-like peptide-1 (GLP-1)-based therapy, including dipeptidyl peptidase-4 (DPP-4) inhibitors and GLP-1 receptor agonists, has emerged as one of the most popular anti-diabetic therapies. Furthermore, GLP-1-based therapy has attracted increased attention not only for its glucose-lowering ability, but also for its potential as a tissue-protective therapy. In this study, we investigated the vascular-protective effect of the DPP-4 inhibitor, linagliptin, using vascular smooth muscle cells (VSMCs). METHODS: Six-week-old male C57BL/6 mice were divided into control (n =19) and linagliptin (3 mg/kg/day, n =20) treated groups. Endothelial denudation injuries were induced in the femoral artery at 8 weeks of age, followed by evaluation of neointima formation at 12 weeks. To evaluate cell proliferation of rat aortic smooth muscle cells, a bromodeoxyuridine (BrdU) incorporation assay was performed. RESULTS: Linagliptin treatment reduced vascular injury-induced neointima formation, compared with controls (p <0.05). In these non-diabetic mice, the body weight and blood glucose levels did not change after treatment with linagliptin. Linagliptin caused an approximately 1.5-fold increase in serum active GLP-1 concentration, compared with controls. In addition, the vascular injury-induced increase in the oxidative stress marker, urinary 8-OHdG, was attenuated by linagliptin treatment, though this attenuation was not statistically significant (p =0.064). Moreover, linagliptin did not change the serum stromal cell-derived factor-1α (SDF-1α) or the serum platelet-derived growth factor (PDGF) concentration. However, linagliptin significantly reduced in vitro VSMC proliferation. CONCLUSION: Linagliptin attenuates neointima formation after vascular injury and VSMC proliferation beyond the glucose-lowering effect.

Exendin-4, a GLP-1 receptor agonist, attenuates prostate cancer growth.

Recently, pleiotropic benefits of incretin therapy beyond glycemic control have been reported. Although cancer is one of the main causes of death in diabetic patients, few reports describe the anticancer effects of incretin. Here, we examined the effect of the incretin drug exendin (Ex)-4, a GLP-1 receptor (GLP-1R) agonist, on prostate cancer. In human prostate cancer tissue obtained from patients after they had undergone radical prostatectomy, GLP-1R expression colocalized with P504S, a marker of prostate cancer. In in vitro experiments, Ex-4 significantly decreased the proliferation of the prostate cancer cell lines LNCap, PC3, and DU145, but not that of ALVA-41. This antiproliferative effect depended on GLP-1R expression. In accordance with the abundant expression of GLP-1R in LNCap cells, a GLP-1R antagonist or GLP-1R knockdown with small interfering RNA abolished the inhibitory effect of Ex-4 on cell proliferation. Although Ex-4 had no effect on either androgen receptor activation or apoptosis, it decreased extracellular signal-regulated kinase (ERK)-mitogen-activated protein kinase (MAPK) phosphorylation in LNCap cells. Importantly, Ex-4 attenuated in vivo prostate cancer growth induced by transplantation of LNCap cells into athymic mice and significantly reduced the tumor expression of P504S, Ki67, and phosphorylated ERK-MAPK. These data suggest that Ex-4 attenuates prostate cancer growth through the inhibition of ERK-MAPK activation.

A humanized anti-IGF-1R monoclonal antibody (R1507) and/or metformin enhance gemcitabine-induced apoptosis in pancreatic cancer cells.

Pancreatic cancer is a disease with a dismal prognosis and treatment options are limited. This study investigated the interaction of gemcitabine with R1507 and/or metformin and the induction of an inhibitor of apoptosis protein by this com-bination. Pancreatic cancer cells were treated with gemcitabine, R1507 and metformin alone or in combination. The effects of treatments were evaluated for cell proliferation, apoptosis, and the expression of genes related to inhibition of apoptosis and chemotherapy resistance. Combination of gemcitabine with R1507 and/or metformin additively interacted with the inhibition of cell proliferation in human pancreatic ductal adenocarcinoma cell lines, SUIT-2 and MIAPaCa-2 with differential gemcitabine resistance, and assessment of apoptosis demonstrated that drug associations increased the apoptotic index in both cell lines. Treatment with gemcitabine induced the expression of survivin and XIAP in both cell lines, indicating the induction of chemoresistance. In conclusion, these data demonstrate that the combination of gemcitabine with R1507 and/or metformin has an additive effect in pancreatic cancer cell lines with differential sensitivity to gemcitabine; however, gemcitabine may induce chemotherapy resistance.

Pancreatic hypertrophy in Ki-ras-induced actin-interacting protein gene knockout mice.

OBJECTIVES: Pancreatic functions were determined in a Ki-ras-induced actin-interacting protein (KRAP)-deficient (-/-) mouse mutant. METHODS: Pancreatic enzyme, protein, and DNA contents were measured, and histological examinations were conducted. The mixture of bile-pancreatic juice was collected, and amylase and bile acid outputs were determined. Oral glucose tolerance test was determined. Moreover, the gene expression of KRAP was determined in cholecystokinin (CCK)-A(1) receptor (-/-) mice. RESULTS: The body weight was smaller, and the ratio of pancreatic wet weight/body weight was higher in KRAP(-/-) mice compared with wild-type mice. The enzyme contents, but not DNA content, in the pancreas of KRAP(-/-) mice were higher than those of wild-type mice. Histological examination revealed the increase in the number of zymogen granules in the pancreatic acinar cells of KRAP(-/-) mice. Amylase secretions in response to CCK-octapeptide sulfate were significantly higher in KRAP(-/-) than wild-type mice, whereas the basal secretion did not differ between the 2 genotypes. A normal glucose tolerance was observed in KRAP(-/-) mice. The gene expression of KRAP in CCK-A(1) receptor (-/-) mice was significantly lower than in wild-type mice. CONCLUSIONS: The lack and/or decrease in KRAP level in the pancreas may promote the pancreatic growth and hypertrophy.

Association of aldehyde dehydrogenase 2 gene polymorphism with pancreatic cancer but not colon cancer.

AIMS: Most of the acetaldehyde, a recognized animal carcinogen, generated during alcohol metabolism is eliminated by liver mitochondrial aldehyde dehydrogenase 2 (ALDH2). More than 40% of Japanese people have the inactive form of ALDH2, and inactive ALDH2 is a risk factor for multiple cancer of the esophagus, as well as head and neck cancer. Possible associations between pancreatic cancer and ALDH2 gene polymorphism, as well as between colon cancer and ALDH2 gene polymorphism, in conjunction with smoking and/or drinking habits, were examined in a Japanese population. METHODS: Patients with pancreatic cancer (n = 187) and with colon cancer (n = 49) were examined. The drinking (5 g ethanol consumption/day) and/or smoking habits as well as ALDH2 gene polymorphism were examined. The age-matched control subjects were recruited in the NILS Longitudinal Study of Aging (LSA). RESULTS: Aging, smoking and inactive ALDH2, but not alcohol, are independent risk factors for pancreatic cancer. The frequency of smoking habits tended to be higher in patients with colon cancer compared with the patients without cancer. However, age, body mass index or the distribution of ALDH2 genotypes did not differ significantly among the patients with colon cancer, colon polyps and others. CONCLUSIONS: Inactive ALDH2 is an independent risk factor for pancreatic cancer, but inactive ALDH2 might not be a risk for colon cancer.

Inactive aldehyde dehydrogenase-2 increased the risk of pancreatic cancer among smokers in a Japanese male population.

OBJECTIVES: Most of the acetaldehyde, a recognized animal carcinogen, generated during alcohol metabolism is eliminated by liver mitochondrial aldehyde dehydrogenase 2 (ALDH2). More than 40% of Japanese have the inactive form of ALDH2, and inactive ALDH2 is a risk factor for multiple cancers of the esophagus as well as head and neck cancer. Possible associations between pancreatic cancer and ALDH2 gene polymorphism, in conjunction with smoking and/or drinking habits, were examined in a Japanese population. METHODS: We investigated 114 patients (70 male and 44 female) with pancreatic cancer and compared them with 2070 control subjects (1050 male and 1020 female). The drinking (5 g ethanol consumption/d) and/or smoking habits as well as ALDH2 gene polymorphism were examined. RESULTS: In male subjects, the frequency of the active form of ALDH2 (2*1/2*1) was lower in pancreatic cancer patients than in control subjects (P = 0.018). The frequency of subjects with both smoking and drinking habits was significantly higher in pancreatic cancer patients than in control subjects having ALDH2*1/2*1 and ALDH2*1/2*2. The frequency of smoking habit alone was significantly higher in pancreatic cancer patients compared with control subjects having inactive ALDH2. Drinking habit had no relation to pancreatic cancer. In female subjects, neither habit had a relation to pancreatic cancer. CONCLUSIONS: Smoking habit did increase the risk of pancreatic cancer, and this risk was further enhanced in subjects with inactive ALDH2 in a male population but not in a female population. There was no relationship between drinking habit and pancreatic cancer in either sex population.

Enhanced gastric emptying of a liquid gastric load in mice lacking cholecystokinin-B receptor: a study of CCK-A,B, and AB receptor gene knockout mice.

BACKGROUND: Although cholecystokinin (CCK) has been shown to inhibit gastric emptying via CCK-A receptors (CCK-ARs), the role of CCK-B receptors (CCK-BRs) has not been verified. We examined whether gastric emptying of a nonnutrient liquid load was modified in CCK-AR, BR, and ARBR gene knockout mice. METHODS: A liquid gastric load prepared with phenol red was administered via an orogastric tube (0.15 ml/mouse). The animals were killed by decapitation, and gastric emptying was estimated at 10 and 30 min after ingestion. The effects of the sulfated form of CCK-8 (CCK-8S) and of graded doses of atropine were examined. In addition, a proton pump inhibitor was administered to wild-type mice to examine the contribution of gastric acid to emptying. RESULTS: Gastric emptying was significantly enhanced in mice lacking CCK-BR, as compared with wild-type and CCK-AR(-/-) mice. CCK-8S inhibited gastric emptying in mice with CCK-AR, but not in mice without CCK-AR. A proton pump inhibitor did not affect gastric emptying. Atropine dose dependently inhibited gastric emptying in all genotypes. The thickness of smooth muscle was comparable for all genotypes. CONCLUSIONS: The gastric emptying of a nonnutrient liquid load was enhanced in mice without CCK-BR, although the precise mechanism is not known. Although cholecystokinin (CCK) has been shown to inhibit gastric emptying via CCK-A receptors (CCK-ARs), the role of CCK-B receptors (CCK-BRs) has not been verified. We examined whether gastric emptying of a nonnutrient liquid load was modified in CCK-AR, BR, and ARBR gene knockout mice.

Lack of cholecystokinin-A receptor enhanced gallstone formation: a study in CCK-A receptor gene knockout mice.

The etiology of gallstones is multifactorial, with interactions between genes and the environment. We generated cholecystokinin (CCK) -A receptor (R)-deficient (-/-) mice and found that CCK did not produce gallbladder contraction in CCK-AR(-/-) mice. The purpose of this study was to identify the role of CCK-AR on gallstone formation. Age-matched CCK-AR gene (+/+) and (-/-) progenies were used. Sludge and gallstone formation, as well as plasma cholesterol levels, were measured at 12 and 24 months of age. Sludge and gallstone formation were significantly higher in CCK-AR(-/-) mice than in CCK-AR(+/+) mice at 12 and 24 months of age, although these were not different between 12 and 24 months of age. The plasma cholesterol levels, daily food intake, and body weight were not significantly different between CCK-AR(+/+) and (-/-) mice. Sludge and gallstone formation were not observed at 6 months of age. In conclusion, deteriorated gallbladder contraction due to a lack of CCK-AR favored gallstone formation after the middle age of life.