Seung Ok Lee

MicroRNA15a modulates expression of the cell-cycle regulator Cdc25A and affects hepatic cystogenesis in a rat model of polycystic kidney disease

Hyperproliferation of bile duct epithelial cells due to cell-cycle dysregulation is a key feature of cystogenesis in polycystic liver diseases (PCLDs). Recent evidence suggests a regulatory role for microRNAs (miRNAs) in a variety of biological processes, including cell proliferation. We therefore hypothesized that miRNAs may be involved in the regulation of selected components of the cell cycle and might contribute to hepatic cystogenesis. We found that the cholangiocyte cell line PCK-CCL, which is derived from the PCK rat, a model of autosomal recessive polycystic kidney disease (ARPKD), displayed global changes in miRNA expression compared with normal rat cholangiocytes (NRCs). More specific analysis revealed decreased levels of 1 miRNA, miR15a, both in PCK-CCL cells and in liver tissue from PCK rats and patients with a PCLD. The decrease in miR15a expression was associated with upregulation of its target, the cell-cycle regulator cell division cycle 25A (Cdc25A). Overexpression of miR15a in PCK-CCL cells decreased Cdc25A levels, inhibited cell proliferation, and reduced cyst growth. In contrast, suppression of miR15a in NRCs accelerated cell proliferation, increased Cdc25A expression, and promoted cyst growth. Taken together, these results suggest that suppression of miR15a contributes to hepatic cystogenesis through dysregulation of Cdc25A.

Cholangiocyte primary cilia are chemosensory organelles that detect biliary nucleotides via P2Y12 purinergic receptors

Cholangiocytes, the epithelial cells lining intrahepatic bile ducts, contain primary cilia, which are mechano- and osmosensory organelles detecting changes in bile flow and osmolality and transducing them into intracellular signals. Here, we asked whether cholangiocyte cilia are chemosensory organelles by testing the expression of P2Y purinergic receptors and components of the cAMP signaling cascade in cilia and their involvement in nucleotide-induced cAMP signaling in the cells. We found that P2Y(12) purinergic receptor, adenylyl cyclases (i.e., AC4, AC6, and AC8), and protein kinase A (i.e., PKA RI-beta and PKA RII-alpha regulatory subunits), exchange protein directly activated by cAMP (EPAC) isoform 2, and A-kinase anchoring proteins (i.e., AKAP150) are expressed in cholangiocyte cilia. ADP, an endogenous agonist of P2Y(12) receptors, perfused through the lumen of isolated rat intrahepatic bile ducts or applied to the ciliated apical surface of normal rat cholangiocytes (NRCs) in culture induced a 1.9- and 1.5-fold decrease of forskolin-induced cAMP levels, respectively. In NRCs, the forskolin-induced cAMP increase was also lowered by 1.3-fold in response to ATP-gammaS, a nonhydrolyzed analog of ATP but was not affected by UTP. The ADP-induced changes in cAMP levels in cholangiocytes were abolished by chloral hydrate (a reagent that removes cilia) and by P2Y(12) siRNAs, suggesting that cilia and ciliary P2Y(12) are involved in nucleotide-induced cAMP signaling. In conclusion, cholangiocyte cilia are chemosensory organelles that detect biliary nucleotides through ciliary P2Y(12) receptors and transduce corresponding signals into a cAMP response.

Endoscopic ultrasound-guided biliary drainage with placement of a fully covered metal stent for malignant biliary obstruction

AIM To determine the utility of endoscopic ultrasound-guided biliary drainage (EUS-BD) with a fully covered self-expandable metal stent for managing malignant biliary stricture. METHODS We collected data from 13 patients who presented with malignant biliary obstruction and underwent EUS-BD with a nitinol fully covered self-expandable metal stent when endoscopic retrograde cholangiopancreatography (ERCP) fails. EUS-guided choledochoduodenostomy (EUS-CD) and EUS-guided hepaticogastrostomy (EUS-HG) was performed in 9 patients and 4 patients, respectively. RESULTS The technical and functional success rate was 92.3% (12/13) and 91.7% (11/12), respectively. Using an intrahepatic approach (EUS-HG, n = 4), there was mild peritonitis (n = 1) and migration of the metal stent to the stomach (n = 1). With an extrahepatic approach (EUS-CD, n = 10), there was pneumoperitoneum (n = 2), migration (n = 2), and mild peritonitis (n = 1). All patients were managed conservatively with antibiotics. During follow-up (range, 1-12 mo), there was re-intervention (4/13 cases, 30.7%) necessitated by stent migration (n = 2) and stent occlusion (n = 2). CONCLUSION EUS-BD with a nitinol fully covered self-expandable metal stent may be a feasible and effective treatment option in patients with malignant biliary obstruction when ERCP fails.

A superoxide anion generator, pyrogallol, inhibits the growth of HeLa cells via cell cycle arrest and apoptosis

We investigated the in vitro effects of pyrogallol on cell growth, cell cycle regulation, and apoptosis in HeLa cells. Pyrogallol inhibited the growth of HeLa cells with an IC50 of approximately 45 µM. Pyrogallol induced arrest during all phases of the cell cycle and also very efficiently resulted in apoptosis in HeLa cells, as evidenced by flow cytometric detection of sub‐G1 DNA content, annexin V binding assay, and DAPI staining. This apoptotic process was accompanied by the loss of mitochondrial transmembrane potential (ΔΨm), Bcl‐2 decrease, caspase‐3 activation, and PARP cleavage. Pan‐caspase inhibitor (Z‐VAD) could rescue some HeLa cells from pyrogallol‐induced cell death, while caspase‐8 and ‐9 inhibitors unexpectedly enhanced the apoptosis. When we examined the changes of the ROS, H2O2 or O  2.− in pyrogallol‐treated cells, H2O2 was slightly increased and O  2.− significantly was increased. In addition, we detected a decreased GSH content in pyrogallol‐treated cells. Only pan‐caspase inhibitor showing recovery of GSH depletion and reduced intracellular O  2.− level decreased PI staining in pyrogallol‐treated HeLa cells, which indicates dead cells. In summary, we have demonstrated that pyrogallol as a generator of ROS, especially O  2.− , potently inhibited the growth of HeLa cells through arrests during all phases of the cell cycle and apoptosis.

Incidence and risk factors of delayed postpolypectomy bleeding: a retrospective cohort study.

Background/Aim: Delayed bleeding is a serious complication that occurs after polypectomy. Many risk factors for delayed bleeding have been suggested, but there is little analysis of procedure-related risk factors. The purpose of this study is to identify a wide range of risk factors for delayed postpolypectomy bleeding (DPPB) and analyze the correlations of those potential DPPB risk factors. Materials and Methods: In this retrospective cohort study, 5981 polypectomies in 3788 patients were evaluated between January 2010 and February 2012. Patient-related, polyp-related, and procedure-related factors were evaluated as potential DPPB risk factors. Results: Delayed bleeding occurred in 42 patients (1.1%). Multivariate analysis revealed that polyp size >10 mm [odds ratio (OR), 2.785; 95% confidence interval (CI), 1.406-5.513; P=0.003], location in the right hemi-colon (OR, 2.289; 95% CI, 1.117-4.693; P=0.024), and endoscopist’s experience (<300 total cases of colonoscopy performed; OR, 4.803; 95% CI, 2.631-8.766; P=0.001) were significant risk factors for DPPB. Especially protruded type polyps (Ip, Isp) larger than 1 cm in the right-side colon were associated with increased risk. Right-side polypectomy by a nonexpert endoscopist was a significant risk factor for DPPB, especially with procedures in the cecum area. Taking the 1.5% DPPB incidence as cutoff value, the learning curve of colonoscopic polypectomy may be estimated as 400 cases of polypectomy. Conclusions: Polyp size, endoscopist’s experience, and right hemi-colon location were identified as potential risk factors for DPPB development.

Parthenolide-induced apoptosis of hepatic stellate cells and anti-fibrotic effects in an in vivo rat model

Parthenolide (PT), a sesquiterpene lactone derived from the plant feverfew, has pro-apoptotic activity in a number of cancer cell types. We assessed whether PT induces the apoptosis of hepatic stellate cells (HCSs) and examined its effects on hepatic fibrosis in an in vivo model. The effects of PT on rat HSCs were investigated in relation to cell growth inhibition, apoptosis, NF-κB binding activity, intracellular reactive oxygen species (ROS) generation, and glutathione (GSH) levels. In addition, the anti-fibrotic effects of PT were investigated in a thioacetamide-treated rat model. PT induced growth inhibition and apoptosis in HSCs, as evidenced by cell growth inhibition and apoptosis assays. PT increased the expression of Bax proteins during apoptosis, but decreased the expression of Bcl-2 and Bcl-XL proteins. PT also induced a reduction in mitochondrial membrane potential, poly(ADP-ribose) polymerase cleavage, and caspase-3 activation. PT inhibited TNF-α-stimulated NF-κB binding activity in HSCs. The pro-apoptotic activity of PT in HSCs was associated with increased intracellular oxidative stress as evidenced by increased intracellular ROS levels and depleted intracellular GSH levels. Furthermore, PT ameliorated hepatic fibrosis significantly in a thioacetamide-treated rat model. In conclusion, PT exhibited pro-apoptotic effects in rat HSCs and ameliorated hepatic fibrosis in a thioacetamide-induced rat model.

Parthenolide suppresses tumor growth in a xenograft model of colorectal cancer cells by inducing mitochondrial dysfunction and apoptosis

Parthenolide (PT), a principal active component in medicinal plants, has been used conventionally to treat migraine and inflammation. This component has recently been reported to induce apoptosis in cancer cells, through mitochondrial dysfunction. In the present study, we investigated PT-mediated cell death signaling pathway by focusing on the involvement of Bcl-2 family members in human colorectal cancer cells. We also investigated the inhibitory effect of PT on tumor growth in xenografts. Using the human colorectal cancer cell lines HT-29, SW620 and LS174T, we demonstrated that treatment of these cancer cells with PT induces apoptosis using MTT, Annexin V assay and Hoechst 33258 staining. Apoptosis through the mitochondrial pathway was confirmed by detecting regulation of Bcl-2 family members, cytochrome c release and caspase activation. Moreover, intraperitoneal injection of PT showed significant inhibition of tumor growth, angiogenesis in the xenograft model. These results demonstrate that PT exhibits anti-cancer activity in human colorectal cancer in vitro and in vivo. These findings may also provide a novel approach for the treatment of colorectal cancer.

Value of Adding T1-Weighted Image to MR Cholangiopancreatography for Detecting Intrahepatic Biliary Stones

OBJECTIVE The purpose of this study was to assess the value of adding a T1-weighted image to MR cholangiopancreatography (MRCP) to detect bile duct stones. MATERIALS AND METHODS During a 30-month period, 148 patients suspected of having biliary stones and who underwent MRI including MRCP, a fat-suppressed T1-weighted fast low-angle shot (FLASH) sequence, and an axial HASTE sequence were enrolled in this study. The biliary stones were confirmed by ERCP, surgery, and percutaneous transhepatic cholangiography. Of these 148 patients, 73 had extrahepatic stones, 45 had intrahepatic stones, 20 had both extrahepatic and intrahepatic stones, and 10 had no biliary stones. Two separate sets of images, the MRCP set (composed of MRCP and axial HASTE) and the combined interpretion of the MRCP set and the T1-weighted image, were analyzed independently and separately by two observers. The diagnostic accuracy was evaluated using the receiver operating characteristic method. The sensitivity and specificity were also calculated. RESULTS For common duct stones, the diagnostic accuracy and the sensitivity of both image sets showed similar values without any significant difference (0.998 [97.8%] for the combined interpretation; 0.988 [97.8%] for observer 1 and 0.995 [96.8%] for observer 2 for the MRCP set). However, for the intrahepatic stones, the diagnostic accuracy (0.993) and the sensitivity (98.5%) of the combined interpretation were significantly higher than those of the MRCP set for the two observers (0.926 [83.8%] for observer 1 and 0.922 [85.3%] for observer 2) (p < 0.05). No significant difference was seen in the specificity of the two image sets for both the intrahepatic and the common duct stones. CONCLUSION Combining the axial T1-weighted image with MRCP is valuable for detecting intrahepatic stones.

Palliation of postoperative gastrointestinal anastomotic malignant strictures with flexible covered metallic stents: Preliminary results

AbstractPurpose: To evaluate the efficacy of the placement of covered metallic stents for palliation of gastrointestinal anastomotic strictures secondary to recurrent gastric cancer. Methods: Under fluoroscopic guidance, placement of one or two self-expandable covered metallic stents was attempted perorally in 11 patents (aged 48-76 years) with anastomotic stenoses due to recurrent gastric malignancies. The strictures involved both the afferent and efferent loops in three patients. All patients had poor peroral food intake with severe nausea and vomiting after ingestion. The technical and clinical success was evaluated. Results: Placement of the covered stent was technically successful in 13 of 15 (87%) attempts in ten patients. After the procedure, 9 of 11 (82%) patients overall were able to ingest at least a liquid diet and had markedly decreased incidence of vomiting. During the follow-up of 2–31 weeks (mean 8.5 weeks) there were no major complications. Conclusion: These preliminary results suggest that flexible, covered stents may provide effective palliation of malignant anastomotic stricture secondary to recurrent gastric cancer.

Journey of a swallowed toothbrush to the colon.

Toothbrush swallowing is a rare event. Because no cases of spontaneous passage have been reported, prompt removal is recommended to prevent the development of complications. Most swallowed toothbrushes have been found in the esophagus or the stomach of affected patients, and there has been no previously reported case of a toothbrush in the colon. Here, we report a case of a swallowed toothbrush found in the ascending colon that caused a fistula between the right colon and the liver, with a complicating small hepatic abscess. This patient was successfully managed using exploratory laparotomy. To our knowledge, this is the first documented case of a swallowed toothbrush found in the colon.