Impaired binding affinity of YTHDC1 with METTL3/METTL14 results in R-loop accumulation in myelodysplastic neoplasms with DDX41 mutation

DEAD box helicase 41 (DDX41) mutations are the most prevalent predisposition to familial myelodysplastic syndrome (MDS). However, the precise roles of these variants in the pathogenesis of MDS have yet to be elucidated. Here, we discovered a novel mechanism by which DDX41 contributes to R-loop-induced DNA damage responses (DDR) in cooperation with the m6A-METTL complex (MAC) and YTHDC1 using DDX41 knockout (KO) and DDX41 knock-in (KI, R525H, Y259C) cell lines as well as primary samples from MDS patients. Compared to wild type (WT), DDX41 KO and KI led to increased levels of m6A RNA methylated R-loop. Interestingly, we found that DDX41 regulates m6A/R-loop levels by interacting with MAC components. Further, DDX41 promoted the recruitment of YTHDC1 to R-loops by promoting the binding between METTL3 and YTHDC1, which was dysregulated in DDX41-deficient cells, contributing to genomic instability. Collectively, we demonstrated that DDX41 plays a key role in the physiological control of R-loops in cooperation with MAC and YTHDC1. These findings provide novel insights into how defects in DDX41 influence MDS pathogenesis and suggest potential therapeutic targets for the treatment of MDS.

Alteration of replication protein A binding mode on single-stranded DNA by NSMF potentiates RPA phosphorylation by ATR kinase

Replication protein A (RPA), a eukaryotic single-stranded DNA (ssDNA) binding protein, dynamically interacts with ssDNA in different binding modes and plays essential roles in DNA metabolism such as replication, repair, and recombination. RPA accumulation on ssDNA due to replication stress triggers the DNA damage response (DDR) by activating the ataxia telangiectasia and RAD3-related (ATR) kinase, which phosphorylates itself and downstream DDR factors, including RPA. We recently reported that the N-methyl-D-aspartate receptor synaptonuclear signaling and neuronal migration factor (NSMF), a neuronal protein associated with Kallmann syndrome, promotes RPA32 phosphorylation via ATR upon replication stress. However, how NSMF enhances ATR-mediated RPA32 phosphorylation remains elusive. Here, we demonstrate that NSMF colocalizes and physically interacts with RPA at DNA damage sites in vivo and in vitro. Using purified RPA and NSMF in biochemical and single-molecule assays, we find that NSMF selectively displaces RPA in the more weakly bound 8- and 20-nucleotide binding modes from ssDNA, allowing the retention of more stable RPA molecules in the 30-nt binding mode. The 30-nt binding mode of RPA enhances RPA32 phosphorylation by ATR, and phosphorylated RPA becomes stabilized on ssDNA. Our findings provide new mechanistic insight into how NSMF facilitates the role of RPA in the ATR pathway.

PWWP2B promotes DNA end resection and homologous recombination

Genome instability is one of the leading causes of gastric cancers. However, the mutational landscape of driver genes in gastric cancer is poorly understood. Here, we investigate somatic mutations in 25 Korean gastric adenocarcinoma patients using whole-exome sequencing and show that PWWP2B is one of the most frequently mutated genes. PWWP2B mutation correlates with lower cancer patient survival. We find that PWWP2B has a role in DNA double-strand break repair. As a nuclear protein, PWWP2B moves to sites of DNA damage through its interaction with UHRF1. Depletion of PWWP2B enhances cellular sensitivity to ionizing radiation (IR) and impairs IR-induced foci formation of RAD51. PWWP2B interacts with MRE11 and participates in homologous recombination via promoting DNA end-resection. Taken together, our data show that PWWP2B facilitates the recruitment of DNA repair machinery to sites of DNA damage and promotes HR-mediated DNA double-strand break repair. Impaired PWWP2B function might thus cause genome instability and promote gastric cancer development.

NSMF promotes the replication stress-induced DNA damage response for genome maintenance

Proper activation of DNA repair pathways in response to DNA replication stress is critical for maintaining genomic integrity. Due to the complex nature of the replication fork (RF), problems at the RF require multiple proteins, some of which remain unidentified, for resolution. In this study, we identified the N-methyl-D-aspartate receptor synaptonuclear signaling and neuronal migration factor (NSMF) as a key replication stress response factor that is important for ataxia telangiectasia and Rad3-related protein (ATR) activation. NSMF localizes rapidly to stalled RFs and acts as a scaffold to modulate replication protein A (RPA) complex formation with cell division cycle 5-like (CDC5L) and ATR/ATR-interacting protein (ATRIP). Depletion of NSMF compromised phosphorylation and ubiquitination of RPA2 and the ATR signaling cascade, resulting in genomic instability at RFs under DNA replication stress. Consistently, NSMF knockout mice exhibited increased genomic instability and hypersensitivity to genotoxic stress. NSMF deficiency in human and mouse cells also caused increased chromosomal instability. Collectively, these findings demonstrate that NSMF regulates the ATR pathway and the replication stress response network for genome maintenance and cell survival.

[Gene mutation spectrum and clinical characteristics analysis of 178 patients with essential thrombocytosis]

目的

分析原发性血小板增多症（ET）患者基因突变谱及临床特征。

方法

对2009年2月1日至2018年11月1日收治的178例初诊ET患者进行回顾性分析。

结果

全部178例患者中，男89例，女89例，中位初诊年龄为49.5（3~86）岁。JAK2V617F基因突变频率为16.45%（1.67%~43.90%），CALR基因突变频率为40.00%（10.00%~49.15%），MPL基因突变频率为25.10%（25.00%~40.00%）。与CALR基因突变的患者相比，JAK2V617F基因突变患者具有较高的发病年龄（P=0.035）、初诊白细胞计数（P=0.040）、初诊血红蛋白浓度（P=0.001）和较低的初诊血小板计数（P=0.002）。47例（27.01%）患者诊断ET前发生血栓事件，3例（1.72%）诊断ET后发生血栓事件。多因素分析结果显示，年龄>60岁（P=0.013，OR=4.595，95%CI1.382~15.282）、心血管危险因素（P<0.001，OR=8.873，95%CI2.921~26.955）为血栓事件的危险因素，CALR基因突变（P=0.032，OR=0.126，95%CI0.019~0.838）为血栓事件的保护性因素。年龄>60岁（P=0.042，OR=4.045，95%CI1.053~15.534）是影响ET患者总生存时间的危险因素。年龄≤60岁、年龄>60岁患者的OS时间分别为（115.231±1.899）、（83.291±4.991）个月（χ²=6.406，P=0.011）。

结论

心血管危险因素、年龄>60岁为ET患者血栓事件的危险因素，CALR基因突变为血栓事件的保护性因素。年龄>60岁是影响ET患者总生存的危险因素。

Reactive oxygen species induce epithelial‑mesenchymal transition, glycolytic switch, and mitochondrial repression through the Dlx‑2/Snail signaling pathways in MCF‑7 cells

Reactive oxygen species (ROS) are important cellular second messengers involved in various aspects of cell signaling. ROS are elevated in multiple types of cancer cells, and this elevation is known to be involved in pathological processes of cancer. Although high levels of ROS exert cytotoxic effects on cancer cells, low levels of ROS stimulate cell proliferation and survival by inducing several pro‑survival signaling pathways. In addition, ROS have been shown to induce epithelial‑mesenchymal transition (EMT), which is essential for the initiation of metastasis. However, the precise mechanism of ROS‑induced EMT remains to be elucidated. In the present study, it was indicated that ROS induce EMT by activating Snail expression, which then represses E‑cadherin expression in MCF‑7 cells. It was further indicated that distal‑less homeobox‑2 (Dlx‑2), one of the human Dlx gene family proteins involved in embryonic development, acts as an upstream regulator of ROS‑induced Snail expression. It was also revealed that ROS treatment induces the glycolytic switch, a phenomenon whereby cancer cells primarily rely on glycolysis instead of mitochondrial oxidative phosphorylation for ATP production, even in the presence of oxygen. In addition, ROS inhibited oxidative phosphorylation and caused cytochrome c oxidase inhibition via the Dlx‑2/Snail cascade. These results suggest that ROS induce EMT, the glycolytic switch and mitochondrial repression by activating the Dlx‑2/Snail axis, thereby playing crucial roles in MCF‑7 cancer cell progression.

[The value of platelet count in predicting the efficacy of rituximab treatment in adult patients with chronic primary immune thrombocytopenia]

目的

探讨血小板计数水平在成人慢性原发免疫性血小板减少症（ITP）患者利妥昔单抗疗效预测中的价值。

方法

回顾性分析2011年1月1日至2014年12月31日期间接受利妥昔单抗治疗（100 mg每周1次，连用4次）慢性ITP患者的临床资料，计算利妥昔单抗治疗后不同随访时间截点血小板计数预测疗效的敏感性、特异性和阳性预测值、阴性预测值，并通过ROC曲线下面积得出最佳截断点。

结果

103例患者纳入研究，男46例，女57例，中位年龄30（18~67）岁。首剂利妥昔单抗后第1、5、7天，成功组（治疗后PLT≥50×10⁹/L且未接受其他药物治疗）与无效组（治疗后PLT<50×10⁹/L）中位血小板计数差异均无统计学意义（P>0.05）；利妥昔单抗治疗后第14天，成功组中位血小板计数高于无效组[41（8~384）×10⁹/L对23（0~106）×10⁹/L，P=0.003]；在随后的各随访截点，成功组中位血小板计数进一步回升并维持于正常水平，无效组中位血小板计数均低于正常水平。以ROC曲线获得的预测治疗反应的优化界限值血小板计数50×10⁹/L为基础，首剂妥昔单抗治疗后第14、30、60天血小板计数能够组成一个预后评估体系。

结论

利妥昔单抗治疗后第14、30、60天血小板计数能够组成一个疗效预测评估体系，有助于随访和制定治疗计划。

Impact of Early Hospital Readmissions After Kidney Transplantation on Graft Function

Early hospital readmissions are common after kidney transplantation. This single-center retrospective study investigated the relationship between early hospital readmissions and clinical outcomes. All adult patients receiving a kidney transplant at this center between March 2009 and June 2015 were included. The early hospital readmissions within the first 30 days were numbered, and the diagnosis was ascertained. The patients were divided into None and Readmission groups. Clinical outcomes and patient- and death-censored graft survival were compared. Among the 103 patients included in the study, 32 (31.1%) had 1 or more readmissions within 30 days. Surgical complications, electrolyte imbalance, and acute rejection were common causes of readmission. No differences were observed in baseline characteristics between the two groups. Patients with early readmissions exhibited low renal function at 3, 6, and 12 months postoperatively (P = .002, .020, and .013, respectively). No difference in graft function was found 12 months after transplantation between the None and Readmission groups. Five-year graft and patient survival also showed no difference between the two groups (P = .424 and .442, respectively). In conclusion, early readmission after kidney transplantation affected lower graft function until 1 year after kidney transplantation. However, the long-term effect on graft function is limited in this study.

Induction of metastasis, cancer stem cell phenotype, and oncogenic metabolism in cancer cells by ionizing radiation

Radiation therapy is one of the major tools of cancer treatment, and is widely used for a variety of malignant tumours. Radiotherapy causes DNA damage directly by ionization or indirectly via the generation of reactive oxygen species (ROS), thereby destroying cancer cells. However, ionizing radiation (IR) paradoxically promotes metastasis and invasion of cancer cells by inducing the epithelial-mesenchymal transition (EMT). Metastasis is a major obstacle to successful cancer therapy, and is closely linked to the rates of morbidity and mortality of many cancers. ROS have been shown to play important roles in mediating the biological effects of IR. ROS have been implicated in IR-induced EMT, via activation of several EMT transcription factors—including Snail, HIF-1, ZEB1, and STAT3—that are activated by signalling pathways, including those of TGF-β, Wnt, Hedgehog, Notch, G-CSF, EGFR/PI3K/Akt, and MAPK. Cancer cells that undergo EMT have been shown to acquire stemness and undergo metabolic changes, although these points are debated. IR is known to induce cancer stem cell (CSC) properties, including dedifferentiation and self-renewal, and to promote oncogenic metabolism by activating these EMT-inducing pathways. Much accumulated evidence has shown that metabolic alterations in cancer cells are closely associated with the EMT and CSC phenotypes; specifically, the IR-induced oncogenic metabolism seems to be required for acquisition of the EMT and CSC phenotypes. IR can also elicit various changes in the tumour microenvironment (TME) that may affect invasion and metastasis. EMT, CSC, and oncogenic metabolism are involved in radioresistance; targeting them may improve the efficacy of radiotherapy, preventing tumour recurrence and metastasis. This study focuses on the molecular mechanisms of IR-induced EMT, CSCs, oncogenic metabolism, and alterations in the TME. We discuss how IR-induced EMT/CSC/oncogenic metabolism may promote resistance to radiotherapy; we also review efforts to develop therapeutic approaches to eliminate these IR-induced adverse effects.

Early Weight Gain After Transplantation Can Cause Adverse Effect on Transplant Kidney Function

BACKGROUND

The outcomes of kidney transplant recipients with increased body mass index (BMI) remain controversial. We studied the relationship between changes in BMI and kidney transplant function, especially during the first year after transplantation.

METHODS

We performed an observational cohort study of all kidney transplant recipients at our center from March 2009 to June 2014 to determine whether changes in BMI were associated with kidney transplant function, as measured by estimated glomerular filtration rate (eGFR). Recipient BMI and eGFR were calculated pre-transplant and at 1, 3, 6, 9, and 12 postoperative months (POM) after transplantation. The correlation between changes in BMI and eGFR was then evaluated.

RESULTS

Eighty-one patients were studied. There was a strong negative correlation between changes in BMI and eGFR from pre-transplant to POM 1 (correlation coefficient, -0.406; P < .0001) and from POM 1 to POM 3 (r = -0.324, P = .004).

CONCLUSIONS

We found that increased BMI caused a significant decline in renal function as measured by eGFR, especially in the initial 3 months after kidney transplantation.

Dlx-2 and glutaminase upregulate epithelial-mesenchymal transition and glycolytic switch

Most cancer cells depend on enhanced glucose and glutamine (Gln) metabolism for growth and survival. Oncogenic metabolism provides biosynthetic precursors for nucleotides, lipids, and amino acids; however, its specific roles in tumor progression are largely unknown. We previously showed that distal-less homeobox-2 (Dlx-2), a homeodomain transcription factor involved in embryonic and tumor development, induces glycolytic switch and epithelial-mesenchymal transition (EMT) by inducing Snail expression. Here we show that Dlx-2 also induces the expression of the crucial Gln metabolism enzyme glutaminase (GLS1), which converts Gln to glutamate. TGF-β and Wnt induced GLS1 expression in a Dlx-2-dependent manner. GLS1 shRNA (shGLS1) suppressed in vivo tumor metastasis and growth. Inhibition of Gln metabolism by shGLS1, Gln deprivation, and Gln metabolism inhibitors (DON, 968 and BPTES) prevented Dlx-2-, TGF-β-, Wnt-, and Snail-induced EMT and glycolytic switch. Finally, shDlx-2 and Gln metabolism inhibition decreased Snail mRNA levels through p53-dependent upregulation of Snail-targeting microRNAs. These results demonstrate that the Dlx-2/GLS1/Gln metabolism axis is an important regulator of TGF-β/Wnt-induced, Snail-dependent EMT, metastasis, and glycolytic switch.

Adjustment Experience of Kidney Transplantation Recipients in Korea

BACKGROUND

The purpose of this study was to understand the adjustment process after kidney transplantation.

METHODS

The research method followed grounded theory methodology of Strauss and Corbin. Twelve recipients after kidney transplantation were selected. The data were collected through in-depth, face-to-face interviews or e-mailing or phone-interviews and analyzed by means of a constant comparative method.

RESULTS

Through the category analysis, "struggling for independence" was verified as the central phenomenon of recipients, and the causal conditions that influence this phenomenon were "unpredictable physical status," "the difficulty of self-care," "apathy of families and friends," and "emotional instability." The contextual conditions were "social prejudice" and "difficulty in returning to society," and the intervening conditions were "significant others support" and "religious support." The action/interaction strategies were "inner reviewing strategies," "interactive strategies," and "active self-maintaining strategies." From this observation, "establishing guidelines for living" was derived as the result.

CONCLUSIONS

The results of this study provided deep understanding on the adjustment process after kidney transplantation, and this would help to provide a frame for individualized medical and nursing intervention strategies in assisting the psychosocial adaptation of the kidney transplantation recipient.

Dlx-2 is implicated in TGF-β- and Wnt-induced epithelial-mesenchymal, glycolytic switch, and mitochondrial repression by Snail activation

Epithelial-mesenchymal transition (EMT) and oncogenic metabolism (including glycolytic switch) are important for tumor development and progression. Here, we show that Dlx-2, one of distal-less (Dlx) homeobox genes, induces EMT and glycolytic switch by activation of Snail. In addition, it was induced by TGF-β and Wnt and regulates TGF-β- and Wnt-induced EMT and glycolytic switch by activating Snail. We also found that TGF-β/Wnt suppressed cytochrome c oxidase (COX), the terminal enzyme of the mitochondrial respiratory chain, in a Dlx-2/Snail-dependent manner. TGF-β/Wnt appeared to downregulate the expression of various COX subunits including COXVIc, COXVIIa and COXVIIc; among these COX subunits, COXVIc was a common target of TGF-β, Wnt, Dlx-2 and Snail, indicating that COXVIc downregulation plays an important role(s) in TGF-β/Wnt-induced COX inhibition. Taken together, our results showed that Dlx-2 is involved in TGF-β- and Wnt-induced EMT, glycolytic switch, and mitochondrial repression by Snail activation.

Proliferation and functional assessment of pseudo-islets with the use of pancreatic endocrine cells

Many obstacles beset islet transplantation, particularly insufficient tissue mass. Previously, we reported production of pseudo-islets. In addition, there have been reports in which coculture with pancreatic islet and bone marrow mesenchymal stem cells (BMSCs) demonstrated positive effects on pancreatic islet function. The purpose of this study was to perform morphologic and functional evaluations of pancreatic pseudo-islets cocultured with BMSCs. Pancreatic endocrine cells (PECs) were collected with a previously reported method; bone marrow was aspirated from the rat femur. Subsequently, PECs and BMSCs cocultured at high density on low-cell-binding culture dishes kept suspended by shaking. The functionality and characteristics of the mixed cell complexes were evaluated by glucose challenge, insulin enzyme-linked immunosorbent assay, reverse-transcription polymerase chain reaction, and immunohistochemistry. Through expansion for 2 weeks in continuous culture passages, ∼1 million PECs were recovered after aggregation. They presented spherical shapes and sizes similar to naïve islets, according to phase-contrast microscopy. The spheroid aggregates of pancreatic islet cells and BMSCs showed fortified functions and maintained viability. In conclusion, PECs served as a cell source for pseudo-islets, which were both morphologically and genetically similar to naïve islets. We also suggest a manufacturing method for mixed cellular complexes from 2 different origins that can improve secretion ability and cell differentiation.

Early growth response 1 regulates glucose deprivation-induced necrosis

Necrosis is commonly found in the core region of solid tumours due to metabolic stress such as hypoxia and glucose deprivation (GD) resulting from insufficient vascularization. Necrosis promotes tumour growth and development by releasing the tumour-promoting cytokine high mobility group box 1 (HMGB1); however, the molecular mechanism underlying necrotic cell death remains largely unknown. In this study, we show that early growth response 1 (Egr-1) is induced in a reactive oxygen species (ROS)-dependent manner by GD in several cell lines such as A549, MDA-MB-231 and HepG2 cells that exhibit necrosis upon GD. We found that Egr-1 short hairpin RNA (shRNA) prevented GD-induced necrosis and HMGB1 release. Necrosis-inhibiting activity of Egr-1 shRNA was also seen in multicellular tumour spheroids (MTSs), an in vitro tumour model system. In contrast, Egr-1 overexpression appeared to make tumour cells more susceptible to GD-induced necrosis. Finally, Egr-1 shRNA suppressed the growth of MTSs. These findings demonstrate that Egr-1 is implicated in GD-induced necrosis and tumour progression.

Does lymphocyte cross-matching predict acute rejection and graft survival in liver transplantation?

INTRODUCTION

The role of lymphocyte cross-matches (LCM) remains controversial in the liver transplant field. The aim of this study was to correlate the risk for acute rejection episodes and graft survival in liver transplantation with pretransplant LCM results.

PATIENTS AND METHODS

We enrolled 184 adult liver transplantation patients, excluding pediatric and second grafts. The 129 living donor and 55 deceased donor liver transplantations were divided into 2 groups: LCM (+); (n=20) and LCM (-); (n=164).

RESULTS

There were no differences in the demographic features, such as gender and recipient age, original disease, Model for End-Stage Liver Disease score, donor type, number of human leukocyte antigen mismatches, and cold ischemia times. There were no hyperacute rejection episodes in the LCM (+) group. Also, posttransplant complications such as acute rejection episode, biliary complication, or hepatic artery thrombosis were not different. Acute rejection episodes occurred in 5.0% of the LCM (+) group and 15.2% of the LCM (-) group (P=.317). Bile duct complications after transplantation arose in 20.0% of the LCM (+) group and in 32.9% of the LCM (-) group (P=.312). The 2 groups showed no difference in graft survival rate analyzed by the Kaplan-Meier method according to LCM results.

CONCLUSION

Pretransplant LCM results were not associated with overall graft survival or acute rejection episodes in this study.

Difference of regeneration potential between healthy and diseased liver

BACKGROUND

We sought to evaluate total and segmental liver regeneration by comparing preoperative computed tomographic (CT) volumetry and CT volumetry on postoperative day (POD) 7 after a right hepatectomy, in patients with various status and surgical indications.

METHOD

We included 36 patients who underwent right lobectomy for living donor liver transplantation (healthy group), and 29 for hepatocellular carcinoma treatment (disease group). All of the disease group patients were Child-Turcotte-Pugh (CTP) class A. The regeneration of lateral, medial segment and total remnant liver volumes were assessed on POD 7 using a CT-based program. Total volumes and segmental volumes were measured for total liver, future liver remnant (FLR), and liver remnant. We calculated total and segmental early regeneration indexes, defined as [(VLR-VFLR)/VFLR]×100, where VLR is volume of the liver remnant and VFLR is volume of the FLR.

RESULT

The VLR at POD 7 showed a 72.9% increase in volume among the healthy versus 55% in the disease group, (P=.012) In the disease group, segmental volume and regeneration indexes were also significantly lower than among the healthy group: 59.0% versus 46.9% in the medial and 86.8% versus 57.7% in the lateral segment (P=.023 and P<.001) respectively.

CONCLUSION

The volume regeneration potential in diseased livers is significantly lower than that of a normal, healthy liver. So, we must consider a patient's liver status and volume profile before an extensive liver.

Does video-assisted minilaparotomy surgical living donor nephrectomy satisfy donors?

PURPOSE

Video-assisted minilaparotomy surgical (VAMS) nephrectomy is believed to provide better cosmetic outcomes than open-donor nephrectomy in healthy donors. However, the results of a few studies have influenced the opinion of donors on their physical appearance. This study investigated the satisfaction of donors after a VAMS living donor nephrectomy.

METHODS

Donors who underwent VAMS living donor nephrectomy between 2009 and 2011 were requested to fill out a body image questionnaire. This questionnaire consisted of three subscales: body image scale (BS), confidence in surgery scale (CS), and hospital experience scale (HS). A total of 20 VAMS living nephrectomy donors completed the questionnaire.

RESULTS

The study included 3 male and 17 female donors of overall mean age of 38.7 ± 12.4 years. Eight donors were unmarried (40.0%), 11 were married (55.0%), and 1 was divorced. The mean follow-up was 7.9 ± 4.5 months. The mean BS, CS, and HS scores were 41.6 ± 5.3, 21.85 ± 8.3, and 13.9 ± 2.2, corresponding to perfect scores of 50, 30, and 20, respectively.

CONCLUSION

The results of this study showed that VAMS nephrectomy donors tended to be pleased with their body image, operation, and hospital experiences.

A 6-month, open-label, multicenter clinical study in Korean de novo renal transplant patients evaluating the efficacy, safety, and tolerance of myfortic concomitantly used with tacrolimus

Enteric-coated mycophenolate sodium (myfortic, Novartis Pharma AG, Basel, Switzerland) is designed to improve the gastrointestinal tolerability of micophenolic acid. This study was designed to evaluate the efficacy and safety of myfortic in Korean de novo renal transplantation. A total of 65 patients from four transplantation centers received the study drug at least once and were included in the intention-to-treat analysis. This study was an open-label, single-arm, multicenter trial with 6-month patient follow-up. Patients received 360 mg (body weight < 50 kg) or 720 mg (body weight > 50 kg) of myfortic per day with tacrolimus and steroids. Induction therapy included basiliximab. The incidence of biopsy-confirmed acute rejection (primary endpoint) within 6 months after transplantation was 7/65 (10.8%). There were 2 (3.1%) graft losses due to severe acute rejection and 1 (1.5%) patient-death due to cardiac arrest. Twenty-two (38.8%) patients experienced gastrointestinal discomfort; however, only 3 (4.5%) cases were associated with an apparent drug reaction. Seventeen (25.4%) patients underwent dose adjustment or myfortic discontinuation during the study period. Patient and graft survival rates at 6 months posttransplantation were 98.1% and 97.0%. Myfortic with tacrolimus-based immunosuppression was efficient and safe after de novo renal transplantation in Korean patients.

Homeobox gene Dlx-2 is implicated in metabolic stress-induced necrosis

BACKGROUND

In contrast to tumor-suppressive apoptosis and autophagic cell death, necrosis promotes tumor progression by releasing the pro-inflammatory and tumor-promoting cytokine high mobility group box 1 (HMGB1), and its presence in tumor patients is associated with poor prognosis. Thus, necrosis has important clinical implications in tumor development; however, its molecular mechanism remains poorly understood.

RESULTS

In the present study, we show that Distal-less 2 (Dlx-2), a homeobox gene of the Dlx family that is involved in embryonic development, is induced in cancer cell lines dependently of reactive oxygen species (ROS) in response to glucose deprivation (GD), one of the metabolic stresses occurring in solid tumors. Increased Dlx-2 expression was also detected in the inner regions, which experience metabolic stress, of human tumors and of a multicellular tumor spheroid, an in vitro model of solid tumors. Dlx-2 short hairpin RNA (shRNA) inhibited metabolic stress-induced increase in propidium iodide-positive cell population and HMGB1 and lactate dehydrogenase (LDH) release, indicating the important role(s) of Dlx-2 in metabolic stress-induced necrosis. Dlx-2 shRNA appeared to exert its anti-necrotic effects by preventing metabolic stress-induced increases in mitochondrial ROS, which are responsible for triggering necrosis.

CONCLUSIONS

These results suggest that Dlx-2 may be involved in tumor progression via the regulation of metabolic stress-induced necrosis.

Optimization of selective emitter fabrication method for solar cells using a laser grooving

In this paper, screen-printing laser grooved buried contact (LGBC) method was applied, which is compatible with the existing screen-printed solar cell equipment and facilities. Experiments were performed in order to optimize short circuit current (I(sc)), open circuit voltage (V(oc)) and fill factor of high efficiency solar cells. To enhance I(sc), V(oc) and efficiency, heavy doping was performed at low sheet resistance in the laser grooved region of the cell. In contrast, light doping was carried out at a high sheet resistance in the non-laser grooved region. To increase fill factor, porous silicon found on the wafer after dipping in an HF solution to remove SiN(x), was cleared. The fabricated screen-printing LGBC solar cell using a 125 mm x 125 mm single crystalline silicon wafer exhibited an efficiency of 17.2%. The results show that screen-printing LGBC method can be applied for high efficiency solar cells.

Implication of snail in metabolic stress-induced necrosis

BACKGROUND

Necrosis, a type of cell death accompanied by the rupture of the plasma membrane, promotes tumor progression and aggressiveness by releasing the pro-inflammatory and angiogenic cytokine high mobility group box 1. It is commonly found in the core region of solid tumors due to hypoxia and glucose depletion (GD) resulting from insufficient vascularization. Thus, metabolic stress-induced necrosis has important clinical implications for tumor development; however, its regulatory mechanisms have been poorly investigated.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we show that the transcription factor Snail, a key regulator of epithelial-mesenchymal transition, is induced in a reactive oxygen species (ROS)-dependent manner in both two-dimensional culture of cancer cells, including A549, HepG2, and MDA-MB-231, in response to GD and the inner regions of a multicellular tumor spheroid system, an in vitro model of solid tumors and of human tumors. Snail short hairpin (sh) RNA inhibited metabolic stress-induced necrosis in two-dimensional cell culture and in multicellular tumor spheroid system. Snail shRNA-mediated necrosis inhibition appeared to be linked to its ability to suppress metabolic stress-induced mitochondrial ROS production, loss of mitochondrial membrane potential, and mitochondrial permeability transition, which are the primary events that trigger necrosis.

CONCLUSIONS/SIGNIFICANCE

Taken together, our findings demonstrate that Snail is implicated in metabolic stress-induced necrosis, providing a new function for Snail in tumor progression.

The effect of later change or modulation of immunosuppression on long-term renal transplant results

Proper maintenance of immunosuppression is required to achieve long-term graft survival. The aim of this study was to evaluate the effect of change or modulation of an immunosuppressive regimen (IR) on graft survival during the posttransplant period in patients undergoing kidney transplantation. A total of 1164 patients who underwent kidney transplantation between January 1997 and December 2008 at Yonsei University Health System were enrolled. All patients initially received calcineurin inhibitor (CNI)-based double or triple IR (DIR and TIR, respectively). The causes of IR changes or modulation were reviewed retrospectively. Graft survival rate was compared according to types of maintenance immunosuppression (DIR versus TIR). Initially, DIR and TIR were adopted in 201 (17.3%) and 963 (82.7%) recipients, respectively. In 77 DIR recipients (38.8%) and 271 TIR recipients (28.1%), IRs were changed. Among recipients of an initial DIR, the most frequent reasons for IR change were acute rejection (50%) within 6 months of transplantation and chronic allograft dysfunction (70%) after 6 months. In TIR recipients, the reasons for IR change included drug toxicity or drug-related side effects (34.3%) within 6 months of transplantation and complications related to overimmunosuppression (39.3%) after 6 months. The group in which the IR was changed from the initial DIR to the later TIR had a statistically superior graft survival rate compared to the group that did not have a change in the initial DIR (P = .032). In contrast, TIR recipients without change had better graft survival rate than recipients with initial TIR change to later DIR (P < .001). Change or modulation of immunosuppression from initial DIR to later TIR could affect long-term graft survival.

Role of extracellular signal-regulated kinase (ERK)1/2 in multicellular resistance to docetaxel in MCF-7 cells

Cancer cells frequently fail to respond to chemotherapy due to acquisition of chemoresistance. Tumour cells are prone to die by necrosis when they are metabolically stressed by hypoxic and glucose depletion (OGD) due to insufficient vascularization, a common feature of solid tumours. Tumour necrosis indicates poor prognosis and emergence of drug resistance in cancer patients; however, its molecular mechanism remains unclear. In this study, we used multicellular tumour spheroids (MTS) as an in vitro tumour model to investigate the molecular mechanisms underlying necrosis-linked drug resistance. MCF-7 cells formed tight and spherical shape of spheroids and started to form the necrotic core at 8 days of culture. We found that docetaxel (DOC)-induced apoptosis was gradually reduced during MCF-7 spheroid culture compared to that in monolayers and that more prominent resistance to DOC was observed when spheroids containing the necrotic core were treated. ERK1/2 and Akt appeared to be activated in MCF-7 spheroids with necrotic core, but not in 2D culture cells and in spheroids without necrotic core. DOC resistance in spheroids was reversed by inhibition of ERK1/2, but not of Akt, suggesting an important role for ERK1/2 in the DOC resistance in MCF-7 spheroids. These results provide new insight into the possible relation between necrosis-linked ERK1/2 activation and acquisition of multicellular resistance.

Role of reactive oxygen species-dependent protein aggregation in metabolic stress-induced necrosis

Cancer cells in the inner region of avascularized solid tumours experience metabolical stress by hypoxic and glucose depletion (OGD) and are prone to die by necrosis to form a necrotic core, a common feature of solid tumours. Unlike in apoptosis, where the cellular contents remain packed in the apoptotic bodies that are removed by macrophages, necrosis is characterized by cell membrane rupture, and the release of many cellular proteins including tumour promoting cytokine high mobility group box 1 (HMGB1) into the extra-cellular space. Although ROS produced by metabolic stress are known to cause membrane damage leading to the plasma membrane rupture, its molecular mechanism remains unclear. In this study, we show that some cellular proteins including pro-apoptotic molecules p53, caspase-3, and caspase-9 and a pro-autophagic molecule beclin 1 are not released into the extracellular space but rather aggregated in the cytosol during GD-induced necrosis and that the protein aggregation occurs in a ROS-dependent manner. We also found that Snail, the transcription factor that is induced by GD, was not translocated to the nucleus and aggregated in the cytosol. In addition, Snail interference appeared to block metabolic stress-induced protein aggregation, indicating a critical role(s) of Snail in the protein aggregation. These results demonstrate that in metabolically stressed cancer cells, ROS induce a specific set of cellular proteins to form insoluble aggregates that are highly toxic to cells and trigger the necrosis-associated membrane rupture and HMGB1 release to promote tumour progression.

Proliferation of pancreatic endocrine cells using disaggregation-expansion-reaggregation technology in isolated rat islets

Donor scarcity is a major obstacle for clinical islet transplantation. Hence, the effective use of the limited number of available islets is necessary for successful islet transplantation. We have developed a new technology that could produce pseudo-islets. Morphologic and functional evaluation was performed to test the feasibility of using these cells for transplantation. A 3-step procedure known as disaggregation-expansion-reaggregation (DER) was employed for pseudo-islet preparation. Islets isolated from 200 to 250-g male Lewis rats by collagenase digestion were separated into single cells by trypsinization. These pancreatic endocrine cells (PECs) were expanded by serial passages in culture before being aggregated at a high cell-density in a suspended state. After DER, cells were morphologically analyzed over time, and gene expression evaluated by reverse transcriptase polymerase chain reaction (RT-PCR). Through expansion by passage for 2 weeks in continuous cultures, approximately 1 million PECs were recovered after aggregation. By phase-contrast microscopy, they presented with spherical shapes and similar sizes compared with naïve islets (50-800 microm). RT-PCR results indicated expression of insulin, glucagon, and pancreatic and duodenal homeobox gene 1, which were observed in primary isolated islets as well. The insulin secretion capacity of pseudo-islets was confirmed by enzyme-linked immunosorbent assay. In conclusion, PECs treated with DER showed potential to serve as a cell source for pseudo-islet generation after in vitro cellular expansion. These cells were both morphologically and genetically similar to naïve islets. Our new technique could be a potential method to overcome the scarcity of donor islets in the near future.

Role of reactive oxygen species-dependent protein aggregation in metabolic stress-induced necrosis

Cancer cells in the inner region of avascularized solid tumours experience metabolical stress by hypoxic and glucose depletion (OGD) and are prone to die by necrosis to form a necrotic core, a common feature of solid tumours. Unlike in apoptosis, where the cellular contents remain packed in the apoptotic bodies that are removed by macrophages, necrosis is characterized by cell membrane rupture, and the release of many cellular proteins including tumour promoting cytokine high mobility group box 1 (HMGB1) into the extra-cellular space. Although ROS produced by metabolic stress are known to cause membrane damage leading to the plasma membrane rupture, its molecular mechanism remains unclear. In this study, we show that some cellular proteins including pro-apoptotic molecules p53, caspase-3, and caspase-9 and a pro-autophagic molecule beclin 1 are not released into the extracellular space but rather aggregated in the cytosol during GD-induced necrosis and that the protein aggregation occurs in a ROS-dependent manner. We also found that Snail, the transcription factor that is induced by GD, was not translocated to the nucleus and aggregated in the cytosol. In addition, Snail interference appeared to block metabolic stress-induced protein aggregation, indicating a critical role(s) of Snail in the protein aggregation. These results demonstrate that in metabolically stressed cancer cells, ROS induce a specific set of cellular proteins to form insoluble aggregates that are highly toxic to cells and trigger the necrosis-associated membrane rupture and HMGB1 release to promote tumour progression.

CuZnSOD and MnSOD inhibit metabolic stress-induced necrosis and multicellular tumour spheroid growth

CuZnSOD and MnSOD have been shown to exert tumour suppressive activities; however, their exact molecular mechanism is still unclear. We investigated the molecular mechanism underlying the tumour suppressive activities of CuZnSOD and MnSOD using multicellular tumour spheroid (MTS), an in vitro tumour model. Overexpression of CuZnSOD and MnSOD significantly suppressed the growth of A549 and MCF-7 MTS, supporting a critical role(s) of reactive oxygen species (ROS) in tumour growth. In solid tumours, ROS is produced by metabolic stress due to insufficient oxygen and glucose supply and induces necrosis that is known to promote tumour progression by releasing the proinflammatory cytokine HMGB1. We observed that CuZnSOD and MnSOD overexpression prevents metabolic stress-induced necrosis and HMGB1 release by inhibiting mitochondrial ROS and intracellular O2- production in response to glucose depletion in two dimensional cell culture. CuZnSOD and MnSOD overexpression also significantly repressed the occurrence of necrosis that was observed during MTS culture. In human tumour tissues including lung pulmonary adenocarcinoma, CuZnSOD and MnSOD expression was detected in the para-necrotic region that was identified by the expression of a hypoxic marker carbonic anhydrase (CA) IX. These results suggest that CuZnSOD and MnSOD may suppress tumour growth through inhibiting metabolic stress-induced necrosis and HMGB1 release via inhibiting metabolic stress-induced mitochondrial ROS production.

Invasive pulmonary aspergillosis after solid organ transplantation: diagnosis and treatment based on 28 years of transplantation experience

Invasive pulmonary aspergillosis (IPA) is a serious and lethal complication among organ transplant recipients. This report described the clinical manifestations and treatment of IPA over a 28-year period. From January 1979 to December 2007, 3215 organ transplant patients (2954 kidney and 261 liver recipients) were enrolled in the study. Nine patients developed IPA (7 kidney and 2 liver recipients), yielding an incidence of 0.003% (9/3215). Five IPA patients (55.6%) were diagnosed by transbronchial lung biopsy or autopsy, and 3 (33.3%) by sputum culture study. One patient was diagnosed through clinical manifestations and observations of IPA characteristics on chest X ray. We used amphotericin B (n = 4; 44.4%), voriconazole (n = 2; 22.2%), or fluconazole (n = 1; 11.1%) as the primary antifungal agents, but 2 patients could not receive antifungal agents due to rapid disease progression and sequential mortality. This study showed a high mortality rate among IPA patients (55.6%; 5/9). Only patients who received early antifungal agent thereby after a prompt diagnosis recovered from IPA. This survival advantage warrants careful monitoring for invasive fungal infections after organ transplantation with immediate administration of antifungal agents or surgical intervention.

Effects of inosine monophosphate dehydrogenase inhibition on high glucose-induced cellular reactive oxygen species in mesangial cells

Mesangial cell extracellular matrix (ECM) synthesis plays an important role in chronic renal diseases including chronic renal allograft dysfunction and diabetic nephropathy. Although inosine monophosphate dehydrogenase 2 (IMPDH2), as a target of mycophenolic acid (MPA), is important for de novo guanosine synthesis in lymphocytes, mesenchymal cells are not wholly dependent on it. To explore the importance of IMPDH2 on the inhibitory effects of MPA in mesangial cells (MC), we compared the effects of MPA and IMPDH2 siRNA on high glucose (HG)-induced fibronectin secretion and cellular reactive oxygen species (ROS). Mouse mesangial cells (MMC) were stimulated with HG (30 mmol/L D-glucose) in the presence or absence of MPA pretreatment or IMPDH2 siRNA transfection. Fibronectin secretion was measured by Western blot analysis, and dichlorofluorescein (DCF)-sensitive cellular ROS assessed by flow cytometry. HG increased fibronectin secretion by 1.8-fold at 24 hours and DCF-sensitive cellular ROS by 1.5-fold at 1 hour. MPA at 10 micromol/L totally inhibited HG-induced fibronectin secretion and cellular ROS in MMC. However, IMPDH2 siRNA only partially suppressed HG-induced fibronectin secretion and cellular ROS. These results suggested that MPA may inhibit HG-induced fibronectin secretion partially through inhibiting cellular ROS and the inhibition of IMPDH2 may be partially involved in the mechanism of MPA.