Kiyoaki Funao

Relationship Between Cysteinyl-Leukotriene-1 Receptor and Human Transitional Cell Carcinoma in Bladder

OBJECTIVES To investigate the leukotriene (LT) D(4) (LTD(4)) receptor (cysteinyl-LT(1) receptor [CysLT(1)R]) expression in transitional cell carcinoma (TCC) of the bladder, as well as the effects of the CysLT(1)R antagonist on cell proliferation in TCC cell lines. The metabolism of arachidonic acid by either cyclooxygenase or lipoxygenase is thought to play an important role in carcinogenesis. LTD(4) is a pro-inflammatory mediator derived from arachidonic acid through various enzymatic steps, and 5-lipoxygenase is an important factor in generating LTD(4). METHODS CysLT(1)R expression in TCC tissue and normal bladder tissue was examined. CysLT(1)R expression was detected using immunohistochemistry. The effects of the CysLT(1)R antagonist on TCC cell growth were examined by 3-(4,5-dimethylthiazol-2-thiazolyl)-2,5-diphenyltetrazolium bromide assay and reverse transcriptase-polymerase chain reaction. Flow cytometry was used to determine whether the CysLT(1)R antagonist induced apoptosis. RESULTS Initially, only slight CysLT(1)R expression was detected in normal bladder tissues and marked CysLT(1)R expression was detected in the TCC tissues. CysLT(1)R expression was greater in high-grade cancer than in low-grade cancer. Furthermore, CysLT(1)R expression was also greater in advanced-stage cancer than in early-stage cancer. Finally, the CysLT(1)R antagonist caused marked inhibition of TCC cells by inducing early apoptosis. CONCLUSIONS CysLT(1)R was induced in TCC. The results suggest that the CysLT(1)R antagonist might mediate potent antiproliferative effects on TCC cells. Thus, the target of the CysLT(1)R is potentially a new therapy in the treatment of TCC.

Telmisartan as a peroxisome proliferator-activated receptor-γ ligand is a new target in the treatment of human renal cell carcinoma.

Angiotensin II receptor blockers (ARBs) are widely used as hypertensive therapeutic agents. However, it has been reported that Telmisartan (a type of ARB) additionally activates peroxisome proliferator-activated receptor (PPAR)-γ. We previously reported that PPAR-γ ligand induced the growth arrest of renal cell carcinoma (RCC) cells through apoptosis, and that Telmisartan had the potential to inhibit prostate cancer cell growth through apoptosis. In this study, we evaluated the effects of Telmisartan and other ARBs on cell proliferation in an RCC cell line using normal proximal tubular endothelial cells (PRTECs) and the human RCC (Caki-1) cell line. The effects of Telmisartan as well as of other ARBs (Candesartan, Valsartan, Irbesartan and Losartan) on RCC cell growth were examined by MTT assay. Flow cytometry and Hoechst staining were used to determine whether or not the ARBs induced apoptosis. Telmisartan caused marked inhibition in RCC cells in a concentration- and time-dependent manner. Treatment with 100 µM of Telmisartan induced early apoptosis and DNA fragmentation in the RCC cells, but not in the PRTECs. None of the other ARBs had an effect on cell proliferation in the RCC cells or the PRTECs. Telmisartan may mediate potent antiproliferative effects against RCC cells through PPAR-γ. Thus, Telmisartan is a potential target for prevention and treatment in RCC.

Treatment of bladder tumors and benign prostatic hyperplasia with a new TUR system using physiological saline as perfusate

This article presents a new transurethral resection (TUR) system for use in endoscopic surgery. By using an electroconductive solution (physiological saline) as the perfusate in lieu of conventional non-electroconductive solution (Uromatic), additional anesthesia (e.g., obturator nerve blocking) is not required. The new TUR is carried out in an electroconductive solution such as saline, and because radiofrequency current flows from the resecting electrode through the perfusate to the outer sheath, no counter-electrode is needed. We have treated both bladder tumor and benign prostatic hyperplasia cases with this new system. Surgery was safely performed in all TUR-bt cases without requiring obturator nerve blocking. During both TUR-bt and transurethral resection of the prostate (TUR-P) using this system, tissue resection and coagulation equivalents were similar to the conventional TUR system. In previous TUR, preoperative obturator nerve blocking was necessary, and in some cases, incomplete blocking or complications occurred. When physiological saline is used as the perfusate, blood electrolyte levels are not greatly changed, even after extensive resection of the bladder wall; as a result, this new system is also cost effective because physiological saline is less expensive than non-electroconductive solutions and requires no counter-electrode. Thus, in comparison with conventional TUR, this new system is both significantly safer and more cost effective.

Expression of cysteinylLT1 receptor in human testicular cancer and growth reduction by its antagonist through apoptosis

The metabolism of arachidonic acid by either cyclooxygenase or lipoxygenase is believed to play an important role in carcinogenesis. Leukotriene (LT) D4 is a pro-inflammatory mediator derived from arachidonic acid through various enzymatic steps, and 5-lipoxygenase is an important factor in generating LTD4. We investigated LTD4 receptor (cysteinylLT1 receptor; CysLT1R) expression in testicular cancer (TC), as well as the effects of the CysLT1R antagonist on cell proliferation in a TC cell line. CysLT1R expression in tissue from TC patients and normal testes (NTs) was detected using immunohistochemistry and RT-PCR. The effects of the CysLT1R antagonist on TC cell growth were examined using the MTT assay. Flow cytometry was used to determine whether or not the CysLT1R antagonist induces apoptosis. Immunohistochemistry indicated that CysLT1R expression was strong in all types of TC tissues, but very weak in NT tissues. The TC cell line expressed CysLT1R mRNA as detected by RT-PCR. MTT and flow cytometry revealed that the CysLT1R antagonist caused marked inhibition of TC cells through early apoptosis. In conclusion, CysLT1R was induced in TC. The results suggest that the CysLT1R antagonist may mediate potent anti-proliferative effects against TC cells. Thus, CysLT1R may become a new therapeutic target for the treatment of TC.

Study of Cysteinyl Leukotriene-1 Receptor in Rat Renal Ischemia-Reperfusion Injury

Renal ischemia-reperfusion (I/R) injury is a major cause of renal transplant dysfunction. Recent studies of I/R injury have focused on the function of neutrophils, the mechanisms of action of inflammatory cytokines, and oxygen free radicals, as well as other mediators. However, few reports address the cysteinyl leukotriene-1 receptor (CysLT1R), an important mediator of bronchial asthma in human beings. We examined the expression of CysLT1R in rat renal I/R injury. At laparotomy, the right kidney was harvested and the left renal artery and vein were clamped. The kidney was reperfused after 90 minutes of ischemia, and the rats were killed after 0, 3, 5, 12, or 24 hours. Expression of CysLT1R analyzed at immunohistochemistry was observed only in endothelial cells in nonischemic kidney. At 0 to 3 hours after reperfusion, CysLT1R expression on endothelial cells gradually became stronger, being most intense at 3 hours after reperfusion. Twelve hours after reperfusion, necrosis extended throughout the ischemic kidney; nearly all of the tubular epithelial cells were destroyed. At 3 to 12 hours after reperfusion, CysLT1R expression gradually became weaker on endothelial cells. At 24 hours after reperfusion, CysLT1R expression was almost at the level of that in nonischemic kidney. Expression of CysLT1R was noted in a rat model of renal I/R injury. Several hours after the maximal CysLT1R expression, we observed the maximum renal I/R injury. These results may suggest a relationship between the CysLT1R and renal I/R injury.

The Role of Cysteinyl-LT1Receptor (CysLT1R) in Renal Ischemia-Reperfusion Injury

The pathogenesis of ischemia-reperfusion (I/R) injury is known to involve cytokines and particularly surface adhesion molecules, the expression of which initiates the attachment of inflammatory cells. Renal I/R injury, a clinically important problem, is an invariable consequence of renal transplantation. The problem begins at the onset of acute tubular necrosis (ATN), when the transplantation includes a long ischemic interval or by use of a cardiac arrest donors kidney. The cysteinyl leukotriene-1 (CysLT(1)), a potent lipid mediator in allergic disease, acts through the CysLT(1)R receptor. We researched the expression of CysLT(1)R in rat renal I/R injury as well as correlations with the degree of ATN. The right kidney was harvested and the left renal artery and vein were clamped at laparotomy. The kidney was reperfused after 90 minutes of ischemia; rats were sacrificed at 0, 3, 5, 12, and 24 hours after reperfusion. CysLT(1)R expression was analyzed by immunohistochemistry. CysLT(1)R expression was observed only in endothelial cells of a normal kidney. CysLT(1)R expression was most intense on endothelial cells at 3 hours after reperfusion, and CysLT(1)R expression on endothelial cells gradually became weaker. Twelve hours after reperfusion, ATN extended throughout the ischemic kidney. Renal I/R injury gradually progressed at time after reperfusion. Several hours after the maximal CysLT(1)R expression, we observed the maximum renal I/R injury.

Expression of sphingosine-1 phosphate receptor in rat renal ischemia-reperfusion injury.

Sphingosine-1 phosphate receptor (S1PR) has come to the fore as a mediator of extracellular signaling through its interaction with G-protein-coupled receptors, which results in the induction of peripheral T-cell depletion. The mechanisms involved in renal ischemia-reperfusion (I/R) injury are complex, but appear to involve the early participation of bone marrow-derived cells, such as T lymphocytes. In this study, we investigated the expression of SIPR in a rat model of renal I/R injury. By means of a laparotomy, the right kidney was harvested and the left renal artery and vein were clamped. The kidney was reperfused after 90 min of ischemia, and rats were sacrificed at 0, 3, 6, 12 and 24 h after reperfusion. S1PR expression was analyzed by immunohistochemistry, and was observed only in endothelial cells of the normal kidneys. From 0 to 3 h after reperfusion, S1PR expression gradually became stronger in endothelial cells, reaching its peak intensity at 3 h after reperfusion. Twelve hours after reperfusion, necrosis had extended throughout the ischemic kidney, and nearly all the tubular epithelial cells had been destroyed. From 3 to 12 h after reperfusion, S1PR expression gradually weakened. At 24 h after reperfusion, levels of S1PR expression had almost reached those of the normal kidneys. In conclusion, S1PR was found to be expressed in a rat model of renal I/R injury. Several hours after achieving the maximum level of S1PR expression, the maximum level of renal I/R injury was observed. These results suggest a relationship between S1PR and renal I/R injury.

Cysteinyl-leukotriene1 receptor antagonist prevents urological cancer cell growth through early apoptosis

Recent studies have demonstrated that the cysteinyl-leukotriene1 receptor (CysLT1R) antagonist induces the growth arrest of cancer cells through apoptosis. In this study, we examined the effects of the CysLT1R antagonist on cell proliferation in urological cancer cell lines, including renal cell carcinoma, bladder cancer, prostate cancer and testicular cancer cells. The inhibitory effect of the CysLT1R antagonist on the urological cancer cells was investigated using the MTT assay and flow cytometry. The CysLT1R antagonist induced a reduction in cell viability with a half-maximal concentration of growth inhibition in all the urological cancer cell lines, and arrested the growth of the cells through early apoptosis. In conclusion, the CysLT1R antagonist may mediate potent anti-proliferative effects against urological cancer cells through early apoptosis, and may therefore serve as a novel therapeutic target in the treatment of urological cancer.