Tadahiko Kikugawa

Inhibition of bladder tumour growth by histone deacetylase inhibitor

To examine the expression profile of histone deacetylase (HDAC)‐1 and explore its potential role in the development of bladder cancer, using valproic acid (VPA), a HDAC inhibitor, which reduces tumour growth and metastasis formation in animal models.

Adseverin: A novel cisplatin-resistant marker in the human bladder cancer cell line HT1376 identified by quantitative proteomic analysis

Cisplatin is currently the most effective antitumor agent available against bladder cancer. However, a majority of patients eventually relapse with cisplatin‐resistant disease. Chemoresistance thus remains a major obstacle in bladder cancer therapy. To clarify the molecular mechanisms underlying cisplatin resistance in bladder cancer, we established a cisplatin‐resistant subline from the human bladder cancer cell line HT1376 (HT1376‐CisR), and conducted large‐scale analyses of the expressed proteins using two‐dimensional (2D) gel electrophoresis coupled with mass spectrometry (MS). Comparative proteomic analysis of HT1376 and HT1376‐CisR cells revealed 36 differentially expressed proteins, wherein 21 proteins were upregulated and 15 were downregulated in HT1376‐CisR cells. Among the differentially regulated proteins, adseverin (SCIN), a calcium‐dependent actin‐binding protein, was overexpressed (4‐fold upregulation) in HT1376‐CisR, with the increase being more prominent in the mitochondrial fraction than in the cytosol fraction. SCIN mRNA knockdown significantly reduced cell proliferation with mitochondria‐mediated apoptosis in HT1376‐CisR cells. Immunoprecipitation analysis revealed voltage‐dependent anion channels (VDACs) to be bound to SCIN in the mitochondrial fraction. Our results suggest that the VDAC‐SCIN interaction may inhibit mitochondria‐mediated apoptosis in cisplatin‐resistant cells. Targeting the VDAC‐SCIN interaction may offer a new therapeutic strategy for cisplatin‐resistant bladder cancer.

Long‑term exposure to leptin enhances the growth of prostate cancer cells.

Obesity correlates with an increased risk of developing prostate cancer (PCa) and leptin plays an important role in PCa progression. Since leptin is produced by adipocytes, the serum leptin level is higher in obese than in non-obese individuals. However, the effects of leptin remain controversial and unclear. The aim of the present study was to investigate the effect of leptin on PCa cell aggressiveness. Three human PCa cell lines (LNCaP, DU145 and PC-3) were treated with recombinant leptin for 28 days. Cell proliferation, migration, and invasion were estimated using the WST assay, a wound-healing assay, and a BD Matrigel invasion assay, respectively. The mechanism underlying the proliferative effect of leptin was investigated by cell transfections with small interfering RNA (siRNA) against the leptin receptor (ObR) or forkhead box O1 (FOXO1), and by immunocytochemistry. Long-term exposure of PCa cells to leptin enhanced their proliferation, migration and invasion. Leptin increased ObR expression and enhanced Akt phosphorylation constitutively. Leptin also increased the phosphorylation of FOXO1 via PI3K signaling and FOXO1 gene silencing enhanced PCa cell proliferation. Leptin induced the translocation of FOXO1 from the nucleus to the cytoplasm. Furthermore, the PI3K inhibitor, LY294002 suppressed this translocation. These results suggested that leptin regulated the subcellular localization of FOXO1 and induced Akt phosphorylation. Additionally, we revealed that leptin increased the expression of cyclin D1 and decreased the expression of p21 protein. In conclusion, long-term exposure to leptin increased the cell proliferation, migration, and invasion of PCa cells through inactivation of FOXO1. This inactivation resulted from exclusion of FOXO1 from the nucleus and its restriction to the cytoplasm through PI3K/Akt signaling. Our findings contribute to an understanding of the association between obesity and PCa aggressiveness.

A Signaling Network in Phenylephrine-Induced Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is an age-related disease of unknown etiology characterized by prostatic enlargement and coinciding with distinctive alterations in tissue histomorphology. To identify the molecular mechanisms underlying the development of BPH, we conducted a DNA microarray study using a previously described animal model in which chronic alpha(1)-adrenergic stimulation by repeated administration of phenylephrine evokes histomorphological changes in the rat prostate that resemble human BPH. Bioinformatic tools were applied to microarray data obtained from prostate tissue to construct a network model of potentially relevant signal transduction pathways. Significant involvement of inflammatory pathways was demonstrable, including evidence for activation of a TGF-beta signaling cascade. The heterodimeric protein clusterin (apolipoprotein J) was also identified as a prominent node in the network. Responsiveness of TGF-beta signaling and clusterin gene and protein expression were confirmed independently of the microarray data, verifying some components of the model. This is the first attempt to develop a comprehensive molecular network for histological BPH induced by adrenergic activation. The study also implicated clusterin as a novel biochemical target for therapy.

Expression of aquaporin 3 in the human prostate

Objective:  Aquaporins (AQPs) function as selective pores allowing water, glycerol and other small solutes to pass through the cell membrane. The present study investigated the expression and localization of AQP3 in the human prostate.

Androgens upregulate aquaporin 9 expression in the prostate

Objectives:  Aquaporins (AQP) function as selective pores allowing water, glycerol and other small solutes to pass through the cell membrane. We previously reported that AQP are expressed in the prostates of both humans and rats. The present study investigated the androgen‐dependent expression of AQP9 in the prostate in vivo and in vitro.

Modified FOLFOX6 Chemotherapy in Patients with Metastatic Urachal Cancer

Background: To improve the prognosis of patients with urachal cancer and establish an effective chemotherapeutic regimen for distant metastases. Methods: We conducted a retrospective study to evaluate the efficacy and safety of a modified combination of 5-fluorouracil, leucovorin and oxaliplatin (mFOLFOX6) therapy in patients with metastatic urachal cancer. Results: Five patients were treated with mFOLFOX6. Their median age was 65 years (range 41-80). The median follow-up time was 42 months (range 18-46). Two of the 5 patients (40%) showed an objective response: 1 achieved a clinically complete response and 1 a partial response. The grade 3/4 toxicity associated with this regimen was primarily neutropenia, but febrile neutropenia was not observed. Oxaliplatin treatment was discontinued because of a grade 2 allergic reaction in 1 patient. Grade 2 peripheral sensory neuropathy caused by oxaliplatin was observed in 2 patients, and the OPTIMOX (stop and go) approach had to be adopted. Conclusions: mFOLFOX6 appears to be effective for the treatment of metastatic urachal cancer.

Cisplatin resistance by induction of aldo-keto reductase family 1 member C2 in human bladder cancer cells

Cisplatin is currently the most effective anti-tumor agent available against bladder cancer. To clarify the mechanism underlying cisplatin resistance in bladder cancer, the present study examined the role of the aldo-keto reductase family 1 member C2 (AKR1C2) protein on chemoresistance using a human bladder cancer cell line. The function of AKR1C2 in chemoresistance was studied using the human HT1376 bladder cancer cell line and the cisplatin-resistant HT1376-CisR subline. AKR1C2 was expressed in HT1376-CisR cells, but not in the parental cells. The effect of small interfering (si) RNAs and an inhibitor targeting AKR1C2 was examined to determine whether cisplatin sensitivity can be rescued by blocking AKR1C2 expression or function. Silencing of AKR1C2 mRNA or inhibition of AKR1C2 by 5β-cholanic acid resulted in a decrease in the survival of cells following cisplatin exposure. Intracellular accumulation of reactive oxygen species (ROS) was determined using a 2,7-dichlorodihydrofluorescein diacetate (H2DCFDA) fluorescent probe. Cisplatin exposure increased the level of intracellular ROS in HT1376 cells in a dose-dependent manner. The ROS levels in HT1376-CisR cells were significantly lower than those in HT1376 cells and knockdown of AKR1C2 mRNA significantly restored ROS levels. Cisplatin exposure did not increase intracellular ROS in HT1376-CisR cells, although the level of intracellular ROS increased in HT1376 cells following cisplatin exposure. Silencing of AKR1C2 mRNA restored the ROS increase response to cisplatin and menadione as an oxidative stressor in HT1376-CisR cells. Menadione has the function of an oxidative stressor. The silencing of AKR1C2 mRNA restored the increased ROS response to cisplatin and menadione in HT1376-CisR cells. These results indicate that induction of AKR1C2 in human bladder cancer cells aids in the development of cisplatin resistance through antioxidative effects. The results of this study indicate that AKR1C2 may be an effective molecular target for restoring cisplatin resistance.

Potential of histone deacetylase inhibitors for bladder cancer treatment

Bladder cancer incidence increases with age, presumably reflecting a cumulative exposure to carcinogens and ever-increasing life expectancy. While aberrant protein expression due to DNA mutations is an essential step during oncogenesis, one recent interest has been the role of epigenetic changes in regulating bladder tumor development. Because aberrant histone acetylation has been linked to malignant diseases in several cases, histone deacetylase inhibitors have great potential as new anticancer drugs owing to their ability to modulate transcription and induce differentiation and apoptosis. We herein review the current knowledge on epigenetic issues in bladder cancer, particularly regarding histone acetylation, and discuss its implications for understanding the molecular basis and treatment of this disease.

Smooth muscle hyperplasia of the epididymis: a case report

(2003). Smooth muscle hyperplasia of theepididymis: a case report. Pathology: Vol. 35, No. 5, pp. 454-455.