Tomomi Kusumi

Induction of differentiation and peroxisome proliferator-activated receptor γ expression in colon cancer cell lines by troglitazone

Purpose We investigated the relationship between the effects of troglitazone (TGZ) on cellular growth, differentiation and apoptosis induction, and the induction of peroxisome proliferator-activated receptor (PPAR) γ in three human colon cancer cell lines, HCT-15, DLD-1and LoVo.Methods Viable cell number was evaluated by the Alamar blue assay and apoptotic cell death by TUNEL methods. Expression of PPARγ mRNA and protein was examined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively. The differentiation markers of colonic mucosa, villin and MUC2 mRNAs, were analyzed by real-time RT-PCR.Results HCT-15 and DLD-1 cells proliferated rapidly while LoVo cells grew slowly. TGZ dose-dependently inhibited the proliferation of all the cell lines, and also induced apoptotic cell death. High expression of PPARγ mRNA and protein was demonstrated in DLD-1 and LoVo cells before TGZ treatment. After the treatment, PPARγ mRNA and protein levels were increased in HCT-15 and LoVo cells. Villin and MUC2 mRNAs were increased by TGZ treatment in HCT-15 cells while villin mRNA was repressed in LoVo cells. Changes in expression of PPARγ, villin or MUC2 mRNAs were not observed in DLD-1 cells.Conclusions These results suggest that PPARγ levels are not correlated with the rates of cell proliferation. Differentiation induction by TGZ was only observed in the cell lines with enhanced PPARγ expression.

Basic-helix-loop-helix (bHLH) transcription factor DEC2 negatively regulates vascular endothelial growth factor expression

DEC1 (BHLHB2/Sharp2/Stra13) and DEC2 (BHLHB3/Sharp1) are basic‐helix‐loop‐helix (bHLH) transcription factors, involved in cellular differentiation, responses to hypoxia and circadian rhythms. We recently showed that the expression of DEC1 and DEC2 was up‐regulated by hypoxia; however, the functions of these two factors under hypoxic conditions have not been elucidated in detail. It is well established that the expression of vascular endothelial growth factor (VEGF) is up‐regulated by hypoxia, and the expression of VEGF in response to hypoxia depends on transcriptional activation by a heterodimer comprising hypoxia‐inducible factor 1α (HIF‐1α) and arylhydrocarbon receptor nuclear translocator 1 (ARNT1). In the present study, we showed that DEC2, but not DEC1, suppressed VEGF gene expression under hypoxic conditions. DEC2 protein was co‐immunoprecipitated with HIF‐1α but not with ARNT1. The binding of HIF‐1α to the hypoxia response element (HRE) in the VEGF promoter was decreased by DEC2 over‐expression, and increased by DEC2 knockdown. We also showed that the circadian expression of VEGF showed a reciprocal pattern to that of DEC2 in cartilage. DEC2 had a circadian oscillation in implanted Sarcoma 180 cells. We conclude that DEC2 negatively regulates VEGF expression and plays an important role in the pathological conditions in which VEGF is involved.

Spatial distribution and histogenesis of colorectal Paneth cell metaplasia in idiopathic inflammatory bowel disease

Background and Aim: Colorectal Paneth cell metaplasia (PCM) is known to be a sign of idiopathic inflammatory bowel disease (IBD), although its distribution and histogenesis are not fully understood. Objectives of this research were to investigate the spatial distribution of PCM in IBD and other forms of colitis (non‐IBD), and to find stimuli causing PCM.

Regulation of synthesis of osteoprotegerin and soluble receptor activator of nuclear factor-κB ligand in normal human osteoblasts via the p38 mitogen-activated protein kinase pathway by the application of cyclic tensile strain

Mechanical stress is thought to play an important role in bone remodeling. However, the correlation between mechanical stress and bone remodeling is poorly understood. In this context, using a model of cyclic tensile strain (CTS) toward human osteoblasts, synthesis of osteoprotegerin (OPG) and soluble receptor activator of nuclear factor-κB ligand (sRANKL), and the activation of mitogen-activated protein kinases (MAPKs) were examined. The application of 7%, 0.25-Hz CTS once a day for 4 h for 3 successive days simultaneously caused an increase of OPG synthesis and a decrease of sRANKL release and RANKL mRNA expression in osteoblasts. As for MAPKs activation in osteoblasts with the application of CTS, p38 MAPK was activated 10–20 min after the application of CTS, but extracellular signal-regulated kinase (ERK1/2) and c-Jun NH2-terminal kinase (JNK) were not activated by such application. Furthermore, when CTS was applied once a day for 4 h for 1, 2, or 3 successive days to osteoblasts, p38 MAPK activation was maintained during the 3-day period but ERK1/2 activation was downregulated from day to day, simultaneously. Then, when CTS was applied once a day for 4 h for 3 successive days to osteoblasts pretreated with the p38 MAPK inhibitor SB203580 for 1 h, OPG synthesis was dose-dependently suppressed and inhibition of sRANKL release and RANKL mRNA expression was abrogated. These results indicate that biological responses of OPG and sRANKL synthesis in osteoblasts to the application of CTS are regulated via the p38 MAPK pathway and suggest that CTS might modulate and regulate bone metabolism.

Uni-axial Cyclic Stretch Induces Cbfa1 Expression in Spinal Ligament Cells Derived from Patients with Ossification of the Posterior Longitudinal Ligament

Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic bone formation in the spinal ligaments. Mechanical stress, which acts on the posterior ligaments, is thought to be an important factor in the progression of OPLL. To clarify this mechanism, we investigated the effects of in vitro cyclic stretch (120% peak to peak, at 0.5 Hz) on cultured spinal ligament cells derived from OPLL (OPLL cells) and non-OPLL (non-OPLL cells) patients. The mRNA expressions of Cbfa1 (an osteoblast-specific transcription factor), type I collagen, alkaline phosphatase (ALP), osteocalcin and integrin β1 (a mechanotransducer) were increased by cyclic stretch in OPLL cells, whereas no change was observed in non-OPLL cells. The effects of cyclic stretch on the spinal ligament tissues derived from OPLL and non-OPLL patients were also analyzed by immunohistochemistry using an antibody against Cbfa1. The expression of Cbfa1 was increased by cyclic stretch at the center of the spinal ligament tissues of OPLL patients, whereas no change was observed in the tissues of non-OPLL patients. Furthermore, U0126, a specific inhibitor of MAPK kinase (MEK), suppressed the stretch-induced mRNA expressions of Cbfa1, ALP and type I collagen in OPLL cells. These results suggest that in OPLL cells, mechanical stress is converted by integrin β1 into intracellular signaling and that Cbfa1 is activated through the MAP kinase pathway. Therefore, we propose that mechanical stress plays a key role in the progression of OPLL through an increase in Cbfa1 expression.

Osteochondritis dissecans of the elbow: histopathological assessment of the articular cartilage and subchondral bone with emphasis on their damage and repair.

Osteochondritis dissecans (OCD) of the elbow is a localized injury of the articular cartilage and subchondral bone that is commonly seen in the young athlete. In the present study, the extent of damage and repair on the articular cartilage and subchondral bone was examined histologically using specimens of 25 osteochondral cylinders and seven loose bodies obtained from 25 young athletes who had undergone osteochondral autograft surgery. Terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin nick end‐labeling (TUNEL) assays for detecting apoptotic cells and immunohistochemistry of matrix metalloproteinases (MMP) were performed on the osteochondral cylinder specimens. The histological findings of the OCD of the elbow showed that the articular cartilage exhibited degenerative change, mimicking osteoarthritis, and was markedly damaged as the lesion progressed. TUNEL‐positive cells and MMP‐3‐ and ‐13‐expressing cells were distributed in the degenerative articular cartilage and reparative fibrocartilage tissue. Separation occurred at either the deep articular cartilage or the subchondral bone, with the former being dominant in the early OCD lesions. The present results suggest that the primary pathological changes in OCD of the elbow were due to damage of articular cartilage induced by repeated stress following degenerative and reparative process of articular cartilage and subchondral fracturing, and separation subsequently occurred on the cartilage and developed onto the subchondral bone in its advanced stages.

Graft incorporation within the tibial bone tunnel after anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft*

We described histologic changes in patellar tendon autografts that occur over time within the tibial tunnel in specimens harvested from patients undergoing revision anterior cruciate ligament reconstruction. Ten patients, averaging 21.2 years of age, were divided into two groups based on the time period between their original and revision surgery: early revision (less than 1 year, four patients) and late revision (more than 1 year, six patients). Among the early revision group, the tendon within the tunnel showed increased cellularity and random collagen bundles. A specimen from the shortest early revision case revealed a normal original bone-tendon junction, whereas others showed an obscured structure. Between the tendon and the tunnel wall, granulation tissue was seen and the bone-tendon junction was still immature. In the late revision group, the tendon appeared similar to normal ligament. The original bone-tendon junction was not seen, and the tendon continued completely to the tunnel wall with Sharpey-like fibers. Observations in the early revision group suggest that tendon remodeling and bone-tendon integration continue for at least several months after transplantation. The original bone-tendon junction appears to have shifted to the proximal patellar tendon-tunnel wall junction with time. These findings are in agreement with prior animal studies.

Locally administered low-dose alendronate increases bone mineral density during distraction osteogenesis in a rabbit model

We investigated the effect of locally administered bisphosphonate on distraction osteogenesis in a rabbit model and evaluated its systemic effect. An osteotomy on the right tibia followed by distraction for four weeks was performed on 47 immature rabbits. They were divided into seven equal groups, with each group receiving a different treatment regime. Saline and three types of dosage of alendronate (low, 0.75 microg/kg; mid, 7.5 microg/kg and high 75 microg/kg) were given by systemic injection in four groups, and saline and two dosages (low and mild) were delivered by local injection to the distraction gap in the remaining three groups. The injections were performed five times weekly during the period of distraction. After nine weeks the animals were killed and image analysis and mechanical testing were performed on the distracted right tibiae and the left tibiae which served as a control group. The local low-dose alendronate group showed a mean increase in bone mineral density of 124.3 mg/cm(3) over the local saline group (analysis of variance, p < 0.05) without any adverse effect on the left control tibiae. The findings indicate that the administration of local low-dose alendronate could be an effective pharmacological means of improving bone formation in distraction osteogenesis.

An aggressive course of Xp11 translocation renal cell carcinoma in a 28-year-old man

Abstract:  Cases of renal cell carcinoma (RCC) associated with Xp11 translocations are rare and are reported predominantly in children. We report a case of a young man who developed an aggressive Xp11 translocation RCC. A 28‐year‐old man presented with back pain, fever and macroscopic hematuria. Computed tomography of the abdomen showed a heterogeneous mass in the left kidney. Left radical nephrectomy was performed. Hematoxylin–eosin staining revealed nested and papillary architecture, clear and eosinophilic cytoplasm and vesicles with prominent nucleoli. Immunohistochemical evaluation revealed that the tumor cells showed nuclear labeling for TFE3 protein. On the basis of these findings, the case was diagnosed as Xp11 translocation RCC. This tumor massively recurred and led to the patients death 2 years after the initial diagnosis. The utility of immunohistochemistry using antibodies against TFE3 in RCC occurring in young adults may be necessary for accurate diagnosis.

Immunohistochemical detection of carcinoma in radical prostatectomy specimens following hormone therapy.

Following hormone therapy, residual carcinoma is frequently difficult to identify on HE‐stained prostatectomy specimens. The aim of the present study was therefore to investigate whole‐mounted specimens obtained by radical prostatectomy from patients who had undergone hormone therapy. Formalin‐fixed and paraffin‐embedded specimens were immunostained with prostate secretory cell markers including prostate‐specific antigen (PSA), P504S (α‐methylacyl‐coenzyme A racemase, AMACR), P501S (prostein), and prostate‐specific membrane antigen (PSMA). Residual carcinoma was detected in 250 histological slides of 42 patients in a total of 497 slides from 45 patients. In five of 250 slides (2%), carcinoma was not able to be recognized on HE‐stained slides, but was found on the immunohistochemistry slides. PSMA had reacted positively beyond a moderate degree in carcinoma from all patients. PSA was positive for carcinoma in most of the patients, while negative or minimal staining was observed in a small number of patients. Carcinoma was positively reactive with P504S and P501S in most of the patients, but was negatively reactive in a few. The Gleason score for a pretreatment needle biopsy correlated with P504S staining of the prostatectomy specimens. P504S and P501S had limited ability to identify degenerated carcinoma. PSMA was the most useful marker to identify carcinoma after hormone therapy.