The Natural Product Parthenolide Inhibits Both Angiogenesis and Invasiveness and Improves Gemcitabine Resistance by Suppressing Nuclear Factor κB Activation in Pancreatic Cancer Cell Lines.

We previously established pancreatic cancer (PaCa) cell lines resistant to gemcitabine and found that the activity of nuclear factor κB (NF-κB) was enhanced upon the acquisition of gemcitabine resistance. Parthenolide, the main active ingredient in feverfew, has been reported to exhibit antitumor activity by suppressing the NF-κB signaling pathway in several types of cancers. However, the antitumor effect of parthenolide on gemcitabine-resistant PaCa has not been elucidated. Here, we confirmed that parthenolide significantly inhibits the proliferation of both gemcitabine-resistant and normal PaCa cells at concentrations of 10 µM and higher, and that the NF-κB activity is significantly inhibited, even by 1 µM parthenolide. In Matrigel invasion assays and angiogenesis assays, the invasive and angiogenic potentials were higher in gemcitabine-resistant than normal PaCa cells and were inhibited by a low concentration of parthenolide. Furthermore, Western blotting showed suppressed MRP1 expression in gemcitabine-resistant PaCa treated with a low parthenolide concentration. In a colony formation assay, the addition of 1 µM parthenolide improved the sensitivity of gemcitabine-resistant PaCa cell lines to gemcitabine. These results suggest that parthenolide may be used as a novel therapeutic agent for the treatment of gemcitabine-resistant PaCa.

Robotic resection for splenic artery aneurysm associated with neurofibromatosis type 1: a case report.

BACKGROUND: Neurofibromatosis type 1 is an autosomal-dominant disease characterized by café-au-lait spots and neurofibromas, as well as various other symptoms in the bones, eyes, and nervous system. Due to its connection with vascular fragility, neurofibromatosis type 1 has been reported to be associated with vascular lesions, such as aneurysms. However, there have been few reports of abdominal visceral aneurysms associated with neurofibromatosis type 1. Furthermore, there have been no reports of robotic treatment of aneurysms associated with neurofibromatosis type 1. In this report, we describe the case of a patient with neurofibromatosis type 1 with a splenic artery aneurysm who was successfully treated with robotic surgery. CASE PRESENTATION: This report describes a 41-year-old Asian woman with a history of neurofibromatosis type 1 who was referred to our hospital for evaluation of a 28 mm splenic artery aneurysm observed on abdominal ultrasound. The aneurysm was in the splenic hilum, and transcatheter arterial embolization was attempted; however, this was difficult due to the tortuosity of the splenic artery. Thus, we suggested minimally invasive robotic surgery for treatment and resection of the splenic artery aneurysm with preservation of the spleen. The postoperative course was uneventful, and the patient was discharged on the eighth day after surgery. At 1 year of follow-up, the patient was doing well, with no evidence of recurrence. CONCLUSION: We encountered a rare case of splenic artery aneurysm in a patient with neurofibromatosis type 1 who was successfully treated with robotic surgery. There is no consensus on treatment modalities for neurofibromatosis-related aneurysms, and endovascular treatment is considered safe and effective; however, surgery remains an important treatment modality. Especially in patients with stable hemodynamic status, robotic surgery may be considered as definitive treatment. To our knowledge, this is the first successfully treated case of a splenic artery aneurysm in a patient with neurofibromatosis type 1.

Simultaneous presentation and resection of esophageal cancer and metastasis to the pancreas: Α case report and literature review.

The frequency of metastasis to the pancreas is limited, and the frequency of metastasis of a squamous cell carcinoma of the esophagus is limited even further. The curative resection of this type of metastatic lesion has been reported for some patients; however, the survival benefit that can be attributed to these procedures has not yet been clearly determined. The patient examined in the present study was a 54-year-old man who was diagnosed with a lower thoracic esophageal cancer. Computed tomography revealed a 2-cm tumor at the tail of the pancreas. Since no other obvious distal metastases were observed, the patient underwent simultaneous surgical procedures, excising the esophageal squamous cell carcinoma and the pancreatic metastasis. A histopathological examination confirmed squamous cell carcinoma in both specimens. The patient has been free of disease for 9 months since the resection. A literature review of all relevant cases to date also demonstrated that the primary tumor site in all cases of patients with esophageal cancer presenting with metastasis to the pancreas was the lower thoracic esophagus. Complete simultaneous resections of esophageal squamous cell carcinoma and a solitary metastasis to the pancreas is beneficial and may produce favorable outcomes. However, due to the reduced number of corresponding reports, further studies are required for the confirmation of the benefits of surgery.

Girdin regulates both migration and angiogenesis in pancreatic cancer cell lines.

Girdin, an actin­binding protein, is reportedly involved in the invasion and angiogenesis of various cancers. It has been suggested that the flavonoid Scutellarin (SCU) inhibits Girdin signaling. In the present study, the function and therapeutic applications of Girdin in pancreatic cancer (PaCa) were investigated. Immunohistochemical staining of Girdin in resected PaCa specimens from the Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Science showed that high Girdin expression was associated with poor overall survival and relapse­free survival, as well as with T factor, indicating invasion into the surrounding tissues. On the other hand, Girdin was highly expressed in almost all PaCa cell lines, and the migration ability of Girdin­knockdown cell lines was decreased even under epidermal growth factor (EGF) stimulation. In addition, SCU suppressed PaCa cell migration by inhibiting the phosphorylation of Girdin. The expression and production of vascular endothelial growth factor A (VEGF­A) was significantly decreased in Girdin­knockdown cell lines. Furthermore, in Matrigel tube formation assays performed using culture supernatant, the lumen­forming ability of vascular endothelial cells was also decreased in Girdin­knockdown cell lines. However, SCU treatment did not significantly alter the expression or production of VEGF­A. These results suggested that Girdin is involved in EGF signaling­mediated migration of PaCa cells, that SCU inhibits PaCa invasion by suppressing Girdin activity, and that Girdin is also involved in angiogenesis via an activation pathway different from the action site of SCU. Girdin may be a prognostic biomarker, and the development of a novel molecular­targeted drugs for Girdin may improve the prognosis of PaCa in the future.

Glissonean Pedicle Isolation Focusing on the Laennec's Capsule for Minimally Invasive Anatomical Liver Resection.

Background: Inflow control is one of the most important procedures during anatomical liver resection (ALR), and Glissonean pedicle isolation (GPI) is one of the most efficacious methods used in laparoscopic anatomical liver resection (LALR). Recognition of the Laennec's capsule covering the liver parenchyma is essential for safe and precise GPI. The purpose of this study was to verify identification of the Laennec's capsule, to confirm the validity of GPI in minimally invasive surgery, and to demonstrate the value of GPI focusing on the Laennec's capsule using a robotic system that has been developed in recent years. Methods: We used a cadaveric model to simulate the Glissonean pedicle and the surrounding liver parenchyma for pathologic verification of the layers. We performed 60 LALRs and 39 robotic anatomical liver resections (RALRs) using an extrahepatic Glissonean approach, from April 2020 to April 2023, and verified the layers of the specimens removed during LALR and RALR based on pathologic examination. In addition, the surgical outcomes of LALR and RALR were compared. Results: Histologic examination facilitated by Elastica van Gieson staining revealed the presence of Laennec's capsule covering the liver parenchyma in a cadaveric model. Similar findings were obtained following LALR and RALR, thus confirming that the gap between the Glissonean pedicle and the Laennec's capsule can be dissected without injury to the parenchyma. The mean GPI time was 32.9 and 27.2 min in LALR and RALR, respectively. The mean blood loss was 289.7 and 131.6 mL in LALR and RALR, respectively. There was no significant difference in the incidence of Clavien-Dindo grade ≥III complications between the two groups. Conclusions: Laennec's capsule is the most important anatomical landmark in performing a safe and successful extrahepatic GPI. Based on this concept, it is possible for LALR and RALR to develop GPI focusing on the Laennec's capsule. Furthermore, a robotic system has the potential to increase the safety and decrease the difficulty of this challenging procedure.

Upregulation of integrin­linked kinase enhances tumor progression in gemcitabine­resistant pancreatic cancer.

Pancreatic cancer (PaCa) tends to be resistant to chemotherapy and is associated with a very poor prognosis. It has been previously reported by the authors that integrin­linked kinase (ILK) is a prognostic factor in PaCa. ILK expression was examined in a newly established gemcitabine (Gem)­resistant (Gem­R) PaCa cell line and it was demonstrated that ILK expression was upregulated compared with that in Gem­sensitive (Gem­S) cells. In the present study, the effects of increased ILK expression in Gem­R PaCa cells were evaluated and it was examined whether compound 22 (Cpd22), an ILK inhibitor, exerted antitumor effects not only in Gem­S cells but also in Gem­R cells. Reverse transcription­quantitative polymerase chain reaction and western blotting revealed that ILK expression was higher in Gem­R PaCa cells than in Gem­S PaCa cells. Cpd22 inhibited the growth of PaCa cells in a concentration­dependent manner. Cpd22 also inhibited the growth of Gem­R PaCa cells. The invasive and angiogenic potential of Gem­R PaCa cells was enhanced compared with that in Gem­S cells; however, ILK small interfering RNA and Cpd22 treatment suppressed this enhancement of invasive potential compared with that in Gem­S cells. The addition of Cpd22 to Gem also improved the sensitivity of Gem­R cell lines to Gem. Furthermore, enhanced Akt signaling was associated with increased malignancy in Gem­R cell lines. In conclusion, ILK was upregulated with resistance and may be involved in tumor angiogenesis, invasive potential, and chemotherapy resistance, which were all suppressed by Cpd22 treatment. Thus, Cpd22 may be a novel therapeutic agent for the treatment of PaCa.

Neuroendocrine carcinoma of the minor papilla with pancreas divisum: a case report and review of the literature.

BACKGROUND: Neuroendocrine tumors of the minor papilla are very rare, and only 20 cases have been reported in the literature. Neuroendocrine carcinoma of the minor papilla with pancreas divisum has not been reported previously, making this the first reported case. Neuroendocrine tumors of the minor papilla have been reported in association with pancreas divisum in about 50% of cases reported in the literature. We herein present our case of neuroendocrine carcinoma of the minor papilla with pancreas divisum in a 75-year-old male with a systematic literature review of the previous 20 reports of neuroendocrine tumors of the minor papilla. CASE PRESENTATION: A 75-year-old Asian man was referred to our hospital for evaluation of dilation of the main pancreatic duct noted on abdominal ultrasonography. Magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography showed a dilated dorsal pancreatic duct, which was not connected to the ventral pancreatic duct; however, it opened to the minor papilla, indicating pancreas divisum. The common bile duct had no communication with the pancreatic main duct and opened to the ampulla of Vater. A contrast-enhanced computed tomography scan showed a 12-mm hypervascular mass near the ampulla of Vater. Endoscopic ultrasonography showed a defined hypoechoic mass in the minor papilla with no invasion. The biopsies performed at the previous hospital found adenocarcinoma. The patient underwent a subtotal stomach-preserving pancreaticoduodenectomy. The pathological diagnosis was neuroendocrine carcinoma. At the 15-year follow-up visit, the patient was doing well with no evidence of tumor recurrence. CONCLUSION: In our case, because the tumor was discovered during a medical check-up relatively early in the course of disease, the patient was doing well at the 15-year follow-up visit, with no evidence of tumor recurrence. Diagnosing a tumor of the minor papilla is very difficult because of the relatively small size and submucosal location. Carcinoids and endocrine cell micronests in the minor papilla occur more frequently than generally thought. It is very important to include neuroendocrine tumors of the minor papilla in the differential diagnosis of patients with recurrent pancreatitis or pancreatitis of unknown cause, especially for patients with pancreas divisum.

Accurate intraoperative real-time blood flow assessment of the remnant stomach during robot-assisted distal pancreatectomy with celiac axis resection using indocyanine green fluorescence imaging and da Vinci Firefly technology.

INTRODUCTION: Ischemic gastropathy is one of the unique postoperative complications associated with distal pancreatectomy with celiac axis resection for locally advanced pancreatic cancer. Therefore, it is essential to evaluate blood flow to the stomach following a resection; however, no intraoperative procedures have been established to assess this issue. Herein we describe two cases in which intraoperative evaluation of real-time blood flow in the residual stomach was performed using indocyanine green fluorescence and da Vinci Firefly technology during a robot-assisted distal pancreatectomy with celiac axis resection. METHODS: Robot-assisted distal pancreatectomy with celiac axis resection was performed using a da Vinci Xi surgical system on two patients with locally advanced pancreatic cancer and suspected invasion of the celiac artery. Indocyanine green (ICG) (0.5 mg/kg) was injected intravenously after resection to evaluate real-time blood flow of the stomach using the da Vinci Firefly system. Blood flow of the stomach was evaluated 60 seconds after the intravenous injection of ICG. RESULTS: All cases were confirmed that there was sufficient blood flow in the residual stomach. Therefore, reconstruction of the left gastric artery was not performed, and the surgery was completed with preservation of the stomach. Good postoperative outcomes were achieved and there was no evidence of ischemic gastropathy or delayed gastric emptying in both cases. CONCLUSION: This method is very useful in determining whether or not to perform reconstruction of the left gastric artery and/or additional resection of the remnant stomach during a robot-assisted distal pancreatectomy with celiac axis resection.

[An Intraductal Papillary Mucinous Neoplasm of the Pancreas with Metachronous Quadruple Cancers].

The patient described herein was diagnosed with left breast, endometrial, and early gastric cancers at 49, 53, and 57 years of age, respectively. Magnetic resonance cholangiopancreatography performed when she was undergoing treatment for cholecystitis at 50 years of age showed local pancreatic duct dilatation in the pancreatic head. She was followed in the Department of Gastroenterology at our hospital for an intraductal papillary mucinous neoplasm(IPMN). An abdominal computed tomography scan obtained at 59 years of age revealed dilation of the main pancreatic duct in the pancreas body and tail, therefore an endoscopic ultrasound-guided fine needle aspiration was performed. She was diagnosed with pancreatic cancer and underwent a laparoscopic distal pancreatectomy. The postoperative course was uneventful; however, the pancreatic cancer recurred and she died approximately 14 months postoperatively. Reports of multiple cancers associated with IPMNs are rare, yet we managed a patient with a pancreatic head IPMN complicated by metachronous quadruple carcinomas( breast, endometrial, gastric, and pancreatic cancers).

Enhanced CXCL12/CXCR4 signaling increases tumor progression in radiation­resistant pancreatic cancer.

Pancreatic cancer (PaCa) exhibits one of the poorest prognoses among all gastrointestinal cancers due to the rapid development of treatment resistance, which renders chemotherapy and radiotherapy no longer effective. However, the mechanisms through which PaCa becomes resistant to radiotherapy are unknown. Here, we established radiation­resistant PaCa cell lines to investigate the factors involved in radiation resistance. The role of the C­X­C motif chemokine ligand 12 (CXCL12)/C­X­C chemokine receptor type 4 (CXCR4) axis in radiation resistance in PaCa and the effects of a CXCR4 antagonist on radiation­resistant PaCa cell lines were investigated. As confirmed by immunofluorescence staining, reverse transcription quantitative polymerase chain reaction, and western blotting, the expression of CXCR4 was higher in radiation­resistant PaCa cell lines than that noted in normal PaCa cell lines. The invasion ability of radiation­resistant PaCa cell lines was greater than that of normal cell lines and was enhanced by CXCL12 treatment and coculture with fibroblasts; this enhanced invasion ability was suppressed by the CXCR4 antagonist AMD070. Irradiation after treatment with the CXCR4 antagonist suppressed the colonization of radiation­resistant PaCa cell lines. In conclusion, the CXCL12/CXCR4 axis may be involved in the radiation resistance of PaCa. These findings may facilitate the development of novel treatments for PaCa.

10Z­Hymenialdisine inhibits angiogenesis by suppressing NF­κB activation in pancreatic cancer cell lines.

10Z­Hymenialdisine is a natural product derived from the marine sponge Axinella carteri. 10Z­Hymenialdisine has anti­inflammatory effects exerted through NF­κB; however, it is unclear whether 10Z­Hymenialdisine has anti­angiogenic effects in cancer cells. In the present study, both the anti­angiogenic and antimetastatic effects of this compound in pancreatic cancer were investigated. It was initially confirmed that 10Z­Hymenialdisine significantly inhibited the proliferation of pancreatic cancer cells. Next, using both reverse transcription­quantitative PCR and ELISA, it was demonstrated that 10Z­Hymenialdisine significantly suppressed the expression of VEGF and IL­8 mRNAs and proteins in pancreatic cancer. Immunohistochemical analysis revealed that 10Z­Hymenialdisine inhibited NF­κB activity in pancreatic cancer cell lines. It was also identified that 10Z­Hymenialdisine inhibited tube formation in EA.hy926 cells. In vivo, 10Z­Hymenialdisine significantly inhibited the growth of BxPC­3 pancreatic cancer cells that were subcutaneously injected into model mice. In conclusion, the present study demonstrated that 10Z­Hymenialdisine exerted anti­angiogenic effects by suppressing NF­κB activity and angiogenic factors, such as VEGF and IL­8, in pancreatic cancer cell lines. 10Z­Hymenialdisine has potential applications as a novel therapeutic agent for the treatment of pancreatic cancer.

A novel approach to the selection of an appropriate pacing position for optimal cardiac resynchronization therapy using CT coronary venography and myocardial perfusion imaging: FIVE STaR method (fusion image using CT coronary venography and perfusion SPECT applied for cardiac resynchronization therapy).

BACKGROUND: Nearly one-third of patients with advanced heart failure (HF) do not benefit from cardiac resynchronization therapy (CRT). We developed a novel approach for optimizing CRT via a simultaneous assessment of the myocardial viability and an appropriate lead position using a fusion technique with CT coronary venography and myocardial perfusion imaging. METHODS AND RESULTS: The myocardial viability and coronary venous anatomy were evaluated by resting Tc-99m-tetrofosmin myocardial perfusion imaging (MPI) and contrast CT venography, respectively. Using fusion images reconstructed by MPI and CT coronary venography, the pacing site and lead length were determined for appropriate CRT device implantations in 4 HF patients. The efficacy of this method was estimated by the symptomatic and echocardiographic functional parameters. In all patients, fusion images using MPI and CT coronary venograms were successfully reconstructed without any misregistration and contributed to an effective CRT. Before the surgery, this method enabled the operators to precisely identify the optimal indwelling site, which exhibited myocardial viability and had a lead length necessary for an appropriate device implantation. CONCLUSIONS: The fusion image technique using myocardial perfusion imaging and CT coronary venography is clinically feasible and promising for CRT optimization and enhancing the patient safety in patients with advanced HF.

Diabetes increases the susceptibility to acute kidney injury after myocardial infarction through augmented activation of renal Toll-like receptors in rats.

Acute kidney injury (AKI) after acute myocardial infarction (MI) worsens the prognosis of MI patients. Although type 2 diabetes mellitus (DM) is a major risk factor of AKI after MI, the underlying mechanism remains unclear. Here, we examined the roles of renal Toll-like receptors (TLRs) in the impact of DM on AKI after MI. MI was induced by coronary artery ligation in Otsuka-Long-Evans-Tokushima fatty (OLETF) rats, a rat DM model, and Long-Evans-Tokushima-Otsuka (LETO) rats, nondiabetic controls. Sham-operated rats served as no-MI controls. Renal mRNA levels of TLR2 and myeloid differentiation factor 88 (MyD88) were significantly higher in sham-operated OLETF rats than in sham-operated LETO rats, although levels of TLR1, TLR3, and TLR4 were similar. At 12 h after MI, protein levels of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) in the kidney were elevated by 5.3- and 4.0-fold, respectively, and their mRNA levels were increased in OLETF but not LETO rats. The increased KIM-1 and NGAL expression levels after MI in the OLETF kidney were associated with upregulated expression of TLR1, TLR2, TLR4, MyD88, IL-6, TNF-α, chemokine (C-C motif) ligand 2, and transforming growth factor-ß1 and also with activation of p38 MAPK, JNK, and NF-κB. Cu-CPT22, a TLR1/TLR2 antagonist, administered before MI significantly suppressed MI-induced upregulation of KIM-1, TLR2, TLR4, MyD88, and chemokine (C-C motif) ligand 2 levels and activation of NF-κB, whereas NGAL levels and IL-6 and TNF-α expression levels were unchanged. The results suggest that DM increases the susceptibility to AKI after acute MI by augmented activation of renal TLRs and that TLR1/TLR2-mediated signaling mediates KIM-1 upregulation after MI.NEW & NOTEWORTHY This is the first report to demonstrate the involvement of Toll-like recpetors (TLRs) in diabetes-induced susceptibility to acute kidney injury after acute myocardial infarction. We propose that the TLR1/TLR2 heterodimer may be a new therapeutic target for the prevention of acute kidney injury in diabetic patients.

Inhibition of DPP-4 reduces acute mortality after myocardial infarction with restoration of autophagic response in type 2 diabetic rats.

BACKGROUND: Type 2 diabetes mellitus (T2DM) worsens the outcome after myocardial infarction (MI). Here, we hypothesized that inhibition of dipeptidyl peptidase-4 (DPP-4) improves survival after MI in T2DM by modifying autophagy in the non-infarcted region of the heart. METHODS AND RESULTS: Under baseline conditions, there was no significant difference between levels of myocardial autophagy marker proteins in OLETF, a rat model of T2DM, and in LETO, a non-diabetic control. However, in contrast to the response in LETO, LC3-II protein and LC3-positive autophagosomes in the non-infarcted region of the myocardium were not increased after MI in OLETF. The altered autophagic response in OLETF was associated with lack of AMPK/ULK-1 activation, attenuated response of Akt/mTOR/S6 signaling and increased Beclin-1-Bcl-2 interaction after MI. Treatment with vildagliptin (10 mg/kg/day s.c.), a DPP-4 inhibitor, suppressed Beclin-1-Bcl-2 interaction and increased both LC3-II protein level and autophagosomes in the non-infarcted region in OLETF, though it did not normalize AMPK/ULK-1 or mTOR/S6 signaling. Plasma insulin level, but not glucose level, was significantly reduced by vildagliptin at the dose used in this study. Survival rate at 48 h after MI was significantly lower in OLETF than in LETO (32 vs. 82%), despite similar infarct sizes. Vildagliptin improved the survival rate in OLETF to 80%, the benefit of which was abrogated by chloroquine, an autophagy inhibitor. CONCLUSIONS: The results indicate that vildagliptin reduces T2DM-induced increase in post-MI acute mortality possibly by restoring the autophagic response through attenuation of Bcl-2-Beclin-1 interaction.

Excessive degradation of adenine nucleotides by up-regulated AMP deaminase underlies afterload-induced diastolic dysfunction in the type 2 diabetic heart.

Type 2 diabetes mellitus (T2DM) is often complicated with diastolic heart failure, which decompensates under increased afterload. Focusing on cardiac metabolomes, we examined mechanisms by which T2DM augments ventricular diastolic stiffness in response to pressure overloading. Pressure-volume relationships (PVRs) and myocardial metabolomes were determined at baseline and during elevation of aortic pressure by phenylephrine infusion in a model of T2DM, OLETF, and its non-diabetic control, LETO. Pressure overloading augmented diastolic stiffness without change in systolic reserve in OLETF as indicated by a left-upward shift of end-diastolic PVR. In contrast, PVRs under cardioplegic arrest in buffer-perfused isolated hearts were similar in OLETF and LETO, indicating that extracellular matrix or titin remodeling does not contribute to the afterload-induced increase in stiffness of the beating ventricle of OLETF. Metabolome analyses revealed impaired glycolysis and facilitation of the pentose phosphate pathway in OLETF. Pressure overloading significantly reduced ATP and total adenine nucleotides by 34% and 40%, respectively, in OLETF but not in LETO, while NADH-to-NAD(+) ratios were similar in the two groups. The decline in ATP by pressure overloading in OLETF was associated with increased inosine 5-monophosphate and decreased adenosine levels, being consistent with the 2.5-times higher activity of cardiac AMP deaminase in OLETF. Tissue ATP level was negatively correlated with tau of LV pressure and LVEDP. These results suggest that ATP depletion due to excessive degradation of adenine nucleotides by up-regulated AMP deaminase underlies ventricular stiffening during acute pressure overloading in T2DM hearts.

Translocation of glycogen synthase kinase-3ß (GSK-3ß), a trigger of permeability transition, is kinase activity-dependent and mediated by interaction with voltage-dependent anion channel 2 (VDAC2).

Glycogen synthase kinase-3ß (GSK-3ß) is a major positive regulator of the mitochondrial permeability transition pore (mPTP), a principle trigger of cell death, under the condition of oxidative stress. However, the mechanism by which cytosolic GSK-3ß translocates to mitochondria, promoting mPTP opening, remains unclear. Here we addressed this issue by analyses of the effect of site-directed mutations in GSK-3ß on mitochondrial translocation and protein/protein interactions upon oxidative stress. H9c2 cardiomyoblasts were transfected with GFP-tagged GSK-3ß (WT), a mutant GSK-3ß insensitive to inhibitory phosphorylation (S9A), or kinase-deficient GSK-3ß (K85R). Time lapse observation revealed that WT and S9A translocated from the cytosol to the mitochondria more promptly than did K85R after exposure to oxidative stress. H2O2 increased the density of nine spots on two-dimensional gel electrophoresis of anti-GSK-3ß-immunoprecipitates by more than 3-fold. MALDI-TOF/MS analysis revealed that one of the spots contained voltage-dependent anion channel 2 (VDAC2). Knockdown of VDAC2, but not VDAC1 or VDAC3, by siRNA attenuated both the mitochondrial translocation of GSK-3ß and mPTP opening under stress conditions. The mitochondrial translocation of GSK-3ß was attenuated also when Lys-15, but not Arg-4 or Arg-6, in the N-terminal domain of GSK-3ß was replaced with alanine. The oxidative stress-induced mitochondrial translocation of GSK-3ß was associated with an increase in cell death, which was suppressed by lithium chloride (LiCl), a GSK-3ß inhibitor. These results demonstrate that GSK-3ß translocates from the cytosol to mitochondria in a kinase activity- and VDAC2-dependent manner in which an N-terminal domain of GSK-3ß may function as a mitochondrial targeting sequence.

Does glycemic control reverse dispersion of ventricular repolarization in type 2 diabetes?

BACKGROUND: Abnormal ventricular repolarization is a predictor of cardiovascular mortality. In this study, we tested the hypothesis that glycemic control reverses abnormal ventricular repolarization in patients with type 2 diabetes. METHODS: We analyzed longitudinal changes in repolarization indices of electrocardiograms in retrospectively enrolled 44 patients with type 2 diabetes and 44 age-matched healthy subjects. RESULTS: In the diabetic group, BMI was greater, levels of HbA1c (10.0 ± 1.6 vs. 5.6 ± 0.3%) and triglyceride were higher and level of HDL cholesterol was lower than those in the control group. Although mean QTc intervals were similar (413.6 ± 18.5 vs. 408.3 ± 22.7 ms), QT dispersion (41.8 ± 15.4 vs. 28.7 ± 7.7 ms) and Tpeak-Tend in lead V5 (83.6 ± 13.6 vs. 71.3 ± 10.3 ms) were significantly longer in the diabetic group than in the control group, indicating increased heterogeneity of ventricular repolarization in type 2 diabetes. During follow-up of 36 patients in the diabetic group for 787 ± 301 days, HbA1c level decreased to 7.3 ± 1.6%, while BMI did not significantly change. In contrast to HbA1c, QT dispersion (45.8 ± 15.0 ms) and Tpeak-Tend in lead V5 (83.6 ± 10.6 ms) were not significantly reduced during the follow-up period. There was no correlation between the change in HbA1c and the change in QT dispersion or Tpeak-Tend. CONCLUSIONS: Increased heterogeneity of ventricular repolarization in type 2 diabetic patients was not reduced during the relatively short follow-up period despite significantly improved glycemic control.

Cytoprotective regulation of the mitochondrial permeability transition pore is impaired in type 2 diabetic Goto-Kakizaki rat hearts.

Our recent studies indicated that up-regulation of calcineurin activity and unfolded protein responses (UPRs) disrupt cytoprotective Akt- and ERK-signaling in OLETF, a model of obese type 2 diabetes (T2DM). To determine whether the mechanisms can be generalized, we used Goto-Kakizaki rats (GK), a model of non-obese T2DM, in this study. Infarct sizes after 20-min ischemia/2-h reperfusion were similar in GK and non-diabetic controls, Wistar rats (Wistar). However, erythropoietin (EPO) limited infarct size in Wistar (64.0±5.3% vs. 45.7±4.4%, p<0.05) but not in GK (56.2±2.2% vs. 52.6±2.3%). Levels of calcineurin activity and EPO-induced phosphorylation of Akt and ERK were similar in GK and Wistar, though cytosolic HSP70 level was 50% lower and mitochondrial HSP60 level was 60% higher in GK. EPO preserved mitochondrial calcium retention capacity (CRC), an index of the threshold for opening of the mitochondrial permeability transition pore (mPTP), after ischemia/reperfusion in Wistar but not in GK. Interaction of cyclophilin D (CypD) with mitochondrial inorganic phosphate carrier (PiC), which sensitizes the mPTP, was enhanced in GK. There was a negative exponential relationship between CypD-PiC interaction and CRC upon reperfusion, indicating that increase in CRC by reduction of CypD-PiC interaction is smaller when CypD-PiC interaction level is at a higher range. A chemical chaperone, 4-phenylbutyric acid, attenuated the changes in HSPs and CypD-PiC interaction and restored responses of CRC and infarct size to EPO in GK. These results suggest that cytoprotective regulation of the mPTP is impaired in GK by enhanced CypD-PiC interaction in which UPRs are involved.

Role of connexin-43 in protective PI3K-Akt-GSK-3ß signaling in cardiomyocytes.

Sarcolemmal connexin-43 (Cx43) and mitochondrial Cx43 play distinct roles: formation of gap junctions and production of reactive oxygen species (ROS) for redox signaling. In this study, we examined the hypothesis that Cx43 contributes to activation of a major cytoprotective signal pathway, phosphoinositide 3-kinase (PI3K)-Akt-glycogen synthase kinase-3ß (GSK-3ß) signaling, in cardiomyocytes. A δ-opioid receptor agonist {[d-Ala(2),d-Leu(5)]enkephalin acetate (DADLE)}, endothelin-1 (ET-1), and insulin-like growth factor-1 (IGF-1) induced phosphorylation of Akt and GSK-3ß in H9c2 cardiomyocytes. Reduction of Cx43 protein to 20% of the normal level by Cx43 small interfering RNA abolished phosphorylation of Akt and GSK-3ß induced by DADLE or ET-1 but not that induced by IGF-1. DADLE and IGF-1 protected H9c2 cells from necrosis after treatment with H(2)O(2) or antimycin A. The protection by DADLE or ET-1, but not that by IGF-1, was lost by reduction of Cx43 protein expression. In contrast to Akt and GSK-3ß, PKC-ε, ERK and p38 mitogen-activated protein kinase were phosphorylated by ET-1 in Cx43-knocked-down cells. Like diazoxide, an activator of the mitochondrial ATP-sensitive K(+) channel, DADLE and ET-1 induced significant ROS production in mitochondria, although such an effect was not observed for IGF-1. Cx43 knockdown did not attenuate the mitochondrial ROS production by DADLE or ET-1. Cx43 was coimmunoprecipitated with the ß-subunit of G protein (Gß), and knockdown of Gß mimicked the effect of Cx43 knockdown on ET-1-induced phosphorylation of Akt and GSK-3ß. These results suggest that Cx43 contributes to activation of class I(B) PI3K in PI3K-Akt-GSK-3ß signaling possibly as a cofactor of Gß in cardiomyocytes.