Caspase-4 has a role in cell division in epithelial cells through actin depolymerization.

In addition to its role in pyroptosis and inflammatory cytokine maturation, caspase-4 (CASP4) also contributes to the fusion of phagosomes with lysosomes and cell migration. However, its role in cell division remains elusive. In this study, we demonstrate that CASP4 is indispensable for proper cell division in epithelial cells. Knockout of CASP4 (CASP4 KO) in HepG2 cells led to delayed cell proliferation, increased cell size, and increased multinucleation. In mitosis, CASP4 KO cells showed multipolar spindles, asymmetric spindle positioning, and chromosome segregation errors, ultimately increasing DNA content and chromosome number. We also found that phalloidin, a marker of filamentous actin, increased in CASP4 KO cells owing to suppressed actin depolymerization. Moreover, the levels of actin polymerization-related proteins, including Rho-associated protein kinase1 (ROCK1), LIM kinase1 (LIMK1), and phosphorylated cofilin, significantly increased in CASP4 KO cells. These results suggest that CASP4 contributes to proper cell division through actin depolymerization.

Pentacyclic triterpenoid ursolic acid induces apoptosis with mitochondrial dysfunction in adult T-cell leukemia MT-4 cells to promote surrounding cell growth.

We investigated the antitumor effects of oleanolic acid (OA) and ursolic acid (UA) on adult T-cell leukemia cells. OA and UA dose-dependently inhibited the proliferation of adult T-cell leukemia cells. UA-treated cells showed caspase 3/7 and caspase 9 activation. PARP cleavage was detected in UA-treated MT-4 cells. Activation of mTOR and PDK-1 was inhibited by UA. Autophagosomes were detected in MT-4 cells after UA treatment using electron microscopy. Consistently, mitophagy was observed in OA- and UA-treated MT-4 cells by confocal microscopy. The mitochondrial membrane potential in MT-4 cells considerably decreased, and mitochondrial respiration and aerobic glycolysis were significantly reduced following UA treatment. Furthermore, MT-1 and MT-4 cells were sorted into two regions based on their mitochondrial membrane potential. UA-treated MT-4 cells from both regions showed high activation of caspase 3/7, which were inhibited by Z-vad. Interestingly, MT-4 cells cocultured with sorted UA-treated cells showed enhanced proliferation. Finally, UA induced cell death and ex vivo PARP cleavage in peripheral blood mononuclear cells from patients with adult T-cell leukemia. Therefore, UA-treated MT-4 cells show caspase activation following mitochondrial dysfunction and may produce survival signals to the surrounding cells.

Identification of candidate molecular targets of the novel antineoplastic antimitotic NP-10.

We previously reported the identification of a novel antimitotic agent with carbazole and benzohydrazide structures: N'-[(9-ethyl-9H-carbazol-3-yl)methylene]-2-iodobenzohydrazide (code number NP-10). However, the mechanism(s) underlying the cancer cell-selective inhibition of mitotic progression by NP-10 remains unclear. Here, we identified NP-10-interacting proteins by affinity purification from HeLa cell lysates using NP-10-immobilized beads followed by mass spectrometry. The results showed that several mitosis-associated factors specifically bind to active NP-10, but not to an inactive NP-10 derivative. Among them, NUP155 and importin ß may be involved in NP-10-mediated mitotic arrest. Because NP-10 did not show antitumor activity in vivo in a previous study, we synthesized 19 NP-10 derivatives to identify more effective NP-10-related compounds. HMI83-2, an NP-10-related compound with a Cl moiety, inhibited HCT116 cell tumor formation in nude mice without significant loss of body weight, suggesting that HMI83-2 is a promising lead compound for the development of novel antimitotic agents.

Calmodulin and protein kinases A/G mediate ciliary beat response in the human nasal epithelium.

BACKGROUND: Mucociliary clearance of the airway epithelium is an essential function for mucosal defense. We recently proposed a hypothetical mechanism of ciliary beat regulation, in which the pannexin-1 (Panx1)-P2X7 unit serves as an oscillator generating a periodic increase in intracellular Ca2+ ([Ca2+ ]i ). In the present study, we examined the localization of Panx1 and P2X7 at the ultrastructural level, and investigated the regulatory pathway subsequent to [Ca2+ ]i increase. METHODS: The inferior turbinate mucosa was collected from patients with chronic hypertrophic rhinitis during endoscopic sinonasal surgery. The mucosa was examined by transmission immunoelectron microscopy for Panx1 and P2X7. Alternatively, the mucosa was cut into thin strips, and ciliary beat frequency (CBF) was measured under a phase-contrast light microscope with a high-speed digital video camera. RESULTS: In immunoelectron microscopy, immunoreactivities for Panx1 and P2X7 were localized along the plasma membrane of the entire length of the cilia. CBF was significantly increased by stimulation with 100 µM acetylcholine (Ach). The Ach-induced CBF increase was significantly inhibited by calmidazolium (calmodulin antagonist), SQ22536 (adenylate cyclase inhibitor), ODQ (guanylate cyclase inhibitor), KT5720 (protein kinase A inhibitor), and KT5823 (protein kinase G inhibitor). Fluorodinitrobenzene (creatine kinase inhibitor) completely inhibited the ciliary beat in a time- and dose-dependent manner. CONCLUSION: These results indicate that Panx1 and P2X7 coexist at the cilia of the human nasal epithelial cells and that the ciliary beat is regulated by calmodulin, adenylate/guanylate cyclases and protein kinases A/G, and crucially depends on creatine kinase.

Skill-up study of systemic endoscopic examination technique using narrow band imaging of the head and neck region of patients with esophageal squamous cell carcinoma: Prospective multicenter study.

OBJECTIVE: To evaluate the usefulness of a training program on endoscopic head and neck surveillance for beginner endoscopists. METHODS: This prospective multicenter study included 13 beginner endoscopists from 10 institutions who received training in systematic observation techniques and diagnostic criteria, and the training involved hands-on learning. Between May 2016 and February 2017, enrolled patients with current or previously diagnosed esophageal squamous cell carcinomas underwent head and neck surveillance using narrow band imaging (NBI) endoscopy, and histologically confirmed head and neck squamous cell carcinoma (HNSCC) detection rates, endoscopic image quality, and examination times were compared before (group A) and after (group B) the training program. Maximum possible score for the endoscopic images was 30 points. RESULTS: A total of 330 patients, comprising 181 in group A and 149 in group B, were enrolled. Three patients with HNSCC were detected in group A (1.7%) and in group B (2.0%; P = 1.000). Mean ± standard deviation (SD) examination times were 157 ± 71 s and 174 ± 109 s in groups A and B, respectively, (P = 0.073). Mean ± SD scores of the endoscopic images were 25.04 ± 5.47 points and 27.01 ± 4.35 points in groups A and B, respectively, (P < 0.001). CONCLUSION: The HNSCC detection rate based on the use of NBI on patients with ESCC did not improve after the training program for beginner endoscopists; however, endoscopic image quality improved significantly after the training program.

Conventional versus traction-assisted endoscopic submucosal dissection for gastric neoplasms: a multicenter, randomized controlled trial (with video).

BACKGROUND AND AIMS: The aim of this study was to clarify whether dental floss clip (DFC) traction improves the technical outcomes of endoscopic submucosal dissection (ESD). METHODS: A superiority, randomized control trial was conducted at 14 institutions across Japan. Patients with single gastric neoplasm meeting the indications of the Japanese guidelines for gastric treatment were enrolled and assigned to receive conventional ESD or DFC traction-assisted ESD (DFC-ESD). Randomization was performed according to a computer-generated random sequence with stratification by institution, tumor location, tumor size, and operator experience. The primary endpoint was ESD procedure time, defined as the time from the start of the submucosal injection to the end of the tumor removal procedure. RESULTS: Between July 2015 and September 2016, 640 patients underwent randomization. Of these, 316 patients who underwent conventional ESD and 319 patients who underwent DFC-ESD were included in our analysis. The mean ESD procedure time was 60.7 and 58.1 minutes for conventional ESD and DFC-ESD, respectively (P = .45). Perforation was less frequent in the DFC-ESD group (2.2% vs .3%, P = .04). For lesions located in the greater curvature of the upper or middle stomach, the mean procedure time was significantly shorter in the DFC-ESD group (104.1 vs 57.2 minutes, P = .01). CONCLUSIONS: Our findings suggest that DFC-ESD does not result in shorter procedure time in the overall patient population, but it can reduce the risk of perforation. When selectively applied to lesions located in the greater curvature of the upper or middle stomach, DFC-ESD provides a remarkable reduction in procedure time.

Role of Protein Phosphatase 2A in Osteoblast Differentiation and Function.

The reversible phosphorylation of proteins plays hugely important roles in a variety of cellular processes, such as differentiation, proliferation, and apoptosis. These processes are strictly controlled by protein kinases (phosphorylation) and phosphatases (de-phosphorylation). Here we provide a brief history of the study of protein phosphorylation, including a summary of different types of protein kinases and phosphatases. One of the most physiologically important serine/threonine phosphatases is PP2A. This review provides a description of the phenotypes of various PP2A transgenic mice and further focuses on the known functions of PP2A in bone formation, including its role in osteoblast differentiation and function. A reduction in PP2A promotes bone formation and osteoblast differentiation through the regulation of bone-related transcription factors such as Osterix. Interestingly, downregulation of PP2A also stimulates adipocyte differentiation from undifferentiated mesenchymal cells under the appropriate adipogenic differentiation conditions. In osteoblasts, PP2A is also involved in the ability to control osteoclastogenesis as well as in the proliferation and metastasis of osteosarcoma cells. Thus, PP2A is considered to be a comprehensive factor in controlling the differentiation and function of cells derived from mesenchymal cells such as osteoblasts and adipocytes.

Clinical impact of surveillance for head and neck cancer in patients with esophageal squamous cell carcinoma.

AIM: To evaluate the clinical impact of surveillance for head and neck (HN) region with narrow band imaging (NBI) in patients with esophageal squamous cell carcinoma (ESCC). METHODS: Since 2006, we introduced the surveillance for HN region using NBI for all patients with ESCC before treatment, and each follow-up. The patients with newly diagnosed stage I to III ESCC were enrolled and classified into two groups as follows: Group A (no surveillance for HN region); between 1992 and 2000), and Group B (surveillance for HN region with NBI; between 2006 and 2008). We comparatively evaluated the detection rate of superficial head and neck squamous cell carcinoma (HNSCC), and the serious events due to metachronous advanced HNSCC during the follow-up. RESULTS: A total 561 patients (group A: 254, group B: 307) were enrolled. Synchronous superficial HNSCC was detected in 1 patient (0.3%) in group A, and in 12 (3.9%) in group B (P = 0.008). During the follow up period, metachronous HNSCC were detected in 10 patients (3.9%) in group A and in 30 patients (9.8%) in group B (P = 0.008). All metachronous lesions in group B were early stage, and 26 patients underwent local resection, however, 6 of 10 patients (60%) in group A lost their laryngeal function and died with metachronous HNSCC. CONCLUSION: Surveillance for the HN region by using NBI endoscopy increase the detection rate of early HNSCC in patients with ESCC, and led to decrease serious events related to advanced metachronous HNSCC.

Risk factors for intraoperative perforation during endoscopic submucosal dissection of superficial esophageal squamous cell carcinoma.

AIM: To identify the risk factors and clarify the subsequent clinical courses. METHODS: This study retrospectively analyzed consecutive patients with esophageal squamous cell carcinoma (ESCC) treated using endoscopic submucosal dissection (ESD) between April 2008 and October 2012. We divided the ESCC lesions into perforation cases and non-perforation cases, and compared characteristics and endoscopic findings between the two groups. "Intraoperative perforation" was defined as the detection of a perforation site during ESD and the presence of mediastinal emphysema. RESULTS: In total, 147 patients with 156 ESCC lesions were treated by ESD. Intraoperative perforation was recorded for nine lesions (5.8%) from nine patients. Multivariate analysis identified mucosal deficiency larger than 75% of the circumference of the esophagus as an independent risk factor for intraoperative perforation (OR = 7.37, 95%CI: 1.45-37.4, P = 0.016). The predominant site of perforation was the left wall [6/9 (67%)]. Six of nine perforation sites were successfully closed by clips during the procedures. Two of nine cases required drainage for pleural effusions; however, all nine cases recovered with conservative treatment and without surgical intervention. At the median follow up of 42 mo after ESD, no cases of local recurrence or distant organ metastasis had been observed. CONCLUSION: This study suggests that mucosal deficiency larger than 75% of the luminal circumference is a risk factor for intraoperative perforation during ESD for ESCC.

Prospective trial of biodegradable stents for refractory benign esophageal strictures after curative treatment of esophageal cancer.

BACKGROUND AND AIMS: Biodegradable stents are reportedly effective for refractory benign esophageal strictures; however, little is known about their use in patients with refractory stricture after endoscopic submucosal dissection (ESD) or chemoradiotherapy (CRT) for esophageal cancer. This study aimed to evaluate the effectiveness of biodegradable stents for these patients. METHODS: Patients with refractory benign esophageal stricture with a dysphagia score (DS) of 2 or worse and for whom the passage of a standard size endoscope was not possible were eligible. The primary endpoint was the proportion of those who improved their DSs (% DS improved) at 12 weeks after stent placement, and the secondary endpoints were the proportion of those who improved their DSs at 24 weeks, dysphagia-free survival (DFS), and adverse events. RESULTS: Eighteen patients (men:women, 15:3; median age, 72 years; range, 53-80) were enrolled. Twelve patients improved their DS at 12 weeks (% DS improved, 66.7%; 90% CI, 44.6%-84.4%). Also, 8 of 11 patients (72.7%) after esophagectomy, 4 of 6 patients (66.7%) after ESD, and 3 of 4 patients (75%) after CRT improved at 12 weeks. Three patients who were treated with esophagectomy maintained their DS improvement at 24 weeks (% DS improved, 16.7%; 95% CI, 3.6%-41.4%). The median DFS was 14.1 weeks (95% CI, 13.0-19.0). One patient who had ESD and CRT developed an esophagobronchial fistula 3 months after stent placement. CONCLUSIONS: Biodegradable stents are effective and tolerable for refractory benign esophageal strictures after treatment for esophageal cancer; however, long-term efficacy was limited, especially after ESD or CRT. (Clinical trial registration number: UMIN000008054.).

Prophylactic steroid administration for strictures after endoscopic resection of large superficial esophageal squamous cell carcinoma.

Background and study aims: One of the major complications after endoscopic resection (ER) for large superficial esophageal squamous cell carcinoma (ESCC) is benign esophageal stricture, which can reduce quality of life even if ESCC achieves a cure without organ resection. Recently, steroid administration has been reported as a prophylactic treatment to prevent esophageal strictures. This retrospective study evaluated the stricture rate according to the different width of mucosal defects due to ER and compared it to that seen with prophylactic steroid administration. Patients and methods: Between June 2007 and December 2013, we enrolled patients with ESCC who had 3/4 or larger circumferential mucosal defects due to ER. In December 2009, steroid injections (triamcinolone acetonide 50 mg) into the ulcer bed due to ER were introduced. Beginning in November 2012, we commenced oral steroid administration (prednisolone 30 mg/day, tapered gradually for 8 weeks) in addition to steroid injection. Patients were classified into 3 groups according to the width of mucosal defect after ER (Group A, ≥ 3/4 and < 7/8; Group B, ≥ 7/8 and less than the entire circumference; and Group C, the entire circumference). We retrospectively evaluated the stricture rate by comparing no treatment, steroid injection, or steroid injection followed by oral steroid according to the width of mucosal defect. Results: A total of 115 patients met the selection criteria. In Group B, no treatment had a significantly higher stricture rate (100 %, vs. steroid injection: 56 % P = 0.015; vs steroid injection followed by oral steroid: 20 % P < 0.001). Conversely, in Group C, the stricture rate was high, regardless of treatment (no treatment: 100 %; steroid injection: 100 %; steroid injection followed by oral steroid: 71 %). Conclusions: Although prophylactic steroid administration is effective to prevent strictures for 7/8 circumference or larger mucosal defects, it is ineffective for whole-circumference defects. Further investigation is required.

Protein phosphatase 2A Cα regulates proliferation, migration, and metastasis of osteosarcoma cells.

Osteosarcoma is the most frequent primary bone tumor. Serine/threonine protein phosphatase 2A (PP2A) participates in regulating many important physiological processes, such as cell cycle, growth, apoptosis, and signal transduction. In this study, we examined the expression and function of PP2A Cα in osteosarcoma cells. PP2A Cα expression was expected to be higher in malignant osteosarcoma tissues. PP2A Cα expression level and PP2A activity was higher in malignant osteosarcoma LM8 cells compared with that in primary osteoblasts and in the osteoblast-like cell line MC3T3-E1. Okadaic acid, an inhibitor of PP2A, reduced cell viability and induced apoptosis in LM8 cells. PP2A Cα-knockdown LM8 cells (shPP2A) exhibited less striking filopodial and lamellipodial structures than that in original LM8 cells. Focal adhesion kinase phosphorylation and NF-κB activity decreased in shPP2A-treated cells. Sensitivity to serum deprivation-induced apoptosis increased in shPP2A-treated cells, accompanied by a lower expression level of anti-apoptotic BCL-2 in these cells. Reduction of PP2A Cα resulted in a decrease in the migration ability of LM8 cells in vitro. Reduction in PP2A Cα levels in vivo suppressed proliferation and metastasis in LM8 cells. PP2A Cα expression was also higher in human osteosarcoma MG63 and SaOS-2 cells than that in primary osteoblasts and MC3T3-E1 cells, and reduction in PP2A Cα levels suppressed the cell proliferation rate and migration ability of MG63 cells. These results indicate that PP2A Cα has a critical role in the proliferation and metastasis of osteosarcoma cells; therefore, its inhibition could potentially suppress the malignancy of osteosarcoma cells.

A novel anti-microtubule agent with carbazole and benzohydrazide structures suppresses tumor cell growth in vivo.

BACKGROUND: The mitotic spindles are among the most successful targets of anti-cancer chemotherapy, and they still hold promise as targets for novel drugs. The anti-mitotic drugs in current clinical use, including taxanes, epothilones, vinca alkaloids, and halichondrins, are all microtubule-targeting agents. Although these drugs are effective for cancer chemotherapy, they have some critical problems; e.g., neurotoxicity caused by damage to neuronal microtubules, as well as innate or acquired drug resistance. To overcome these problems, a great deal of effort has been expended on development of novel anti-mitotics. METHODS: We identified novel microtubule-targeting agents with carbazole and benzohydrazide structures: N'-[(9-ethyl-9H-carbazol-3-yl)methylene]-2-methylbenzohydrazide (code number HND-007) and its related compounds. We investigated their activities against cancer cells using various methods including cell growth assay, immunofluorescence analysis, cell cycle analysis, tubulin polymerization assay, and tumor inhibition assay in nude mice. RESULTS: HND-007 inhibits tubulin polymerization in vitro and blocks microtubule formation and centrosome separation in cancer cells. Consequently, it suppresses the growth of various cancer cell lines, with IC50 values in the range 1.3-4.6µM. In addition, HND-007 can inhibit the growth of taxane-resistant cancer cells that overexpress P-glycoprotein. Finally, HND-007 can inhibit HeLa cell tumor growth in nude mice. CONCLUSIONS AND GENERAL SIGNIFICANCE: Taken together, these findings suggest that HND-007 is a promising lead compound for development of novel anti-mitotic, anti-microtubule chemotherapeutic agents.

Usefulness of narrow-band imaging with dual-focus magnification for differential diagnosis of small colorectal polyps.

BACKGROUND: Many authors have already reported the usefulness of narrow-band imaging (NBI) for the differential diagnosis of non-neoplastic and neoplastic colorectal lesions. However, it is not clear whether magnification is required for differential diagnosis. The aim of this prospective study was to clarify the clinical usefulness of a newly developed NBI system with a dual focus function (dual-focus NBI) compared with conventional white-light imaging (WLI) and NBI without magnification for distinguishing between non-neoplastic and neoplastic lesions. PATIENTS AND METHODS: Thirty-seven consecutive patients who underwent screening colonoscopy with the novel system between July and December 2013 were analyzed. Patients with polyps >10 mm and those with polyps previously evaluated by histologic examination or colonoscopy were excluded. Lesions were diagnosed in real time with WLI, NBI without magnification, and dual-focus NBI, and then excised endoscopically. Each diagnosis was compared to that in the final histopathology reports. The primary endpoint was the diagnostic accuracy and the confidence level assigned to each modality by the endoscopists. The secondary endpoint was the differentiation ability according to the size of the lesion (≤5 and 6-10 mm). RESULTS: In all, 100 lesions including 76 adenomatous polyps and 24 hyperplastic polyps were analyzed in 37 patients. The overall diagnostic accuracy, sensitivity, and specificity for differentiating adenomatous from hyperplastic polyps were 87.0, 89.5, and 79.2 % for WLI, 93.0, 94.7, and 87.5 % for NBI without magnification, and 94.0, 96.1, and 87.5 % for dual-focus NBI, respectively. The level of confidence was significantly different between dual-focus NBI and WLI and NBI without magnification for diminutive (≤5 mm) lesions (p < 0.001 and p < 0.01). CONCLUSION: Dual-focus NBI is especially useful for differential diagnosis of diminutive colorectal lesions.

Photodynamic therapy for esophageal cancer.

Photodynamic therapy (PDT) is a treatment that uses a photosensitizing drug that is administered to the patient, localized to a tumor, and then activated with a laser to induce a photochemical reaction to destroy the cell. PDT using porfimer sodium followed by excimer dye laser irradiation is approved as a curative treatment for superficial esophageal cancer in Japan. While endoscopic submucosal dissection (ESD) is currently more popular for esophageal cancer, there is evidence to support PDT as an alternative treatment and as a salvage treatment for local failure after chemoradiotherapy (CRT). A photosensitizing agent has also been developed that requires a shorter sun shade period after administration, and studies are currently underway to establish an esophageal cancer indication for this next-generation PDT in Japan.

Cleavage of unactivated amide bonds by ammonium salt-accelerated hydrazinolysis.

Hydrazinolysis of unactivated amide bonds is significantly accelerated by the addition of ammonium salts. The reactions proceed at 50-70 °C to give amines with broad substrate scope that outperforms existing amide bond cleavage reactions. Application to peptide and amino sugar derivatives is also demonstrated.

Possible participation of acidic pH in bone resorption in middle ear cholesteatoma.

OBJECTIVES/HYPOTHESIS: The etiopathology of bone resorption in cholesteatoma is unclear. We studied pH in middle ear cholesteatoma tissue and the permeability of the cholesteatoma epithelium in an attempt to elucidate the mechanism of bone resorption in this disease. STUDY DESIGN: Laboratorial study. METHODS: Cholesteatoma tissue was collected from patients with primary acquired middle ear cholesteatoma. The pH of the keratin debris of cholesteatoma was measured using a pH meter. The cholesteatoma epithelium was examined under a confocal laser scanning microscope, and under a transmission electron microscope. Expression of filaggrin in the cholesteatoma tissue was explored by fluorescence immunohistochemistry and by quantitative reverse transcription-polymerase chain reaction. RESULTS: The pH of the keratin debris of cholesteatoma was acidic. The pH of the basal layer of the cholesteatoma epithelium was significantly lower than that of the antrum mucosa. Transmission electron microscope showed distinct penetration of lanthanum in the intercellular space of the basal, spinous, and granular layers of the cholesteatoma epithelium, but only a small amount of lanthanum in the granular layer in the normal skin. The expression of filaggrin mRNA was significantly lower in the cholesteatoma tissue than in the normal skin. CONCLUSIONS: These results indicate that acid leakage through the cholesteatoma epithelium probably participates in the resorption of the underlying bone structure. The increased permeability of the cholesteatoma epithelium may be explained by a decrease in filaggrin expression.

Okadaic acid activates the PKR pathway and induces apoptosis through PKR stimulation in MG63 osteoblast-like cells.

Double-stranded RNA-dependent protein kinase (PKR) is one of the players in the cellular antiviral responses and is involved in transcriptional stimulation through activation of NF-κB. Treatment of the human osteosarcoma cell line MG63 with the protein phosphatase inhibitor okadaic acid stimulated the expression and phosphorylation of IκBα, as judged from the results of real-time PCR and western blot analysis. We investigated the functional relationship between PKR and signal transduction of NF-κB by establishing PKR-K/R cells that produced a catalytically inactive mutant of PKR. Phosphorylation of eIF-2α, a substrate of PKR, was not stimulated by okadaic acid in the PKR-K/R cells, whereas okadaic acid induced phosphorylation of eIF-2α in MG63 cells. Phosphorylation of NF-κB in MG63 cells was stimulated by okadaic acid; however, okadaic acid did not induce phosphorylation of NF-κB in the PKR-K/R cells. Finally, okadaic acid-induced apoptosis was inhibited in the PKR-K/R cells. Our results suggest that okadaic acid-induced phosphorylation of IκBα was mediated by PKR kinase activity, thus, indicating the involvement of this kinase in the control mechanism governing the activation of NF-κB and induction of apoptosis.

Adipose tissue behavior is distinctly regulated by neighboring cells and fluid flow stress: a possible role of adipose tissue in peritoneal fibrosis.

Adipose tissue, together with the mesothelial layer and microvessels, is a major component of the mesenteric peritoneum, and the mesenterium is a target site for peritoneal fibrosis. Adipose tissue has been speculated to play a role in peritoneal dialysis (PD)-related fibrosis, but the precise cellular kinetics of adipose tissue during this process remain to be determined. To clarify this critical issue, we analyzed the kinetics of adipose tissue using a novel peritoneal reconstruction model in which the effects of mesothelial cells or endothelial cells could be identified. Adipose tissue was co-cultured with mesothelial cells or endothelial cells in a combined organ culture and fluid flow stress culture system. Spindle mesenchymal cells and immature adipocytes derived from adipose tissue were characterized by immunohistochemistry. Adipose tissue fragments cultured in this system yielded many spindle mesenchymal cells in non-co-culture conditions. However, the number of spindle mesenchymal cells emerging from adipose tissue was reduced in co-culture conditions with a covering layer of mesothelial cells. Mesothelial cells co-cultured in the separated condition did not inhibit the emergence of spindle mesenchymal cells from adipose tissue. Interestingly, endothelial cells promoted the emergence of lipid-laden immature adipocytes from adipose tissue under fluid flow stress. We have demonstrated that adipose tissue behavior is not only regulated by mesothelial cells and endothelial cells under fluid flow stress, but is also involved in fibrosis and fat mass production in the peritoneum. Our findings suggest that adipose tissue is a potential source of cells for peritoneal fibrosis caused by PD therapy.