Masamichi Hayakawa

Protein kinase Cδ amplifies ceramide formation via mitochondrial signaling in prostate cancer cells

We studied the role of protein kinase C isoform PKCδ in ceramide (Cer) formation, as well as in the mitochondrial apoptosis pathway induced by anticancer drugs in prostate cancer (PC) cells. Etoposide and paclitaxel induced Cer formation and apoptosis in PKCδ-positive LNCaP and DU145 cells but not in PKCδ-negative LN-TPA or PC-3 cells. In contrast, these drugs induced mitotic cell cycle arrest in all PC cell lines. Treatment with Rottlerin, a specific PKCδ inhibitor, significantly inhibited drug-induced Cer formation and apoptosis in LNCaP cells, as did overexpression of dominant negative–type PKCδ. Overexpression of wild-type PKCδ had an opposite effect in PC-3 cells. Notably, etoposide induced biphasic Cer formation in LNCaP cells. The early and transient Cer increase resulted from de novo Cer synthesis, while the late and sustained Cer accumulation was derived from sphingomyelin hydrolysis by neutral sphingomyelinase (nSMase). Cer, in turn, induced mitochondrial translocation of PKCδ and stimulated the activity of this kinase, promoting cytochrome c release and caspase-9 activation. Furthermore, the specific caspase-9 inhibitor LEHD-fmk significantly inhibited etoposide-induced nSMase activation, Cer accumulation, and PKCδ mitochondrial translocation. These results indicate that PKCδ plays a crucial role in activating anticancer drug–induced apoptosis signaling by amplifying the Cer-mediated mitochondrial amplification loop.

AN ESSENTIAL ROLE FOR NUCLEAR FACTOR KAPPA B IN PREVENTING TNF-alpha-INDUCED CELL DEATH IN PROSTATE CANCER CELLS

PURPOSE Although tumor necrosis factor-alpha (TNF-alpha) induces a strong cytotoxic effect on cell growth, many authors have reported that various cancer cells are resistant to TNF-alpha and the basis for this sensitivity or resistance to TNF-alpha remains to be elucidated. Since nuclear factor kappa B (NF-kappaB) activation has recently been reported to inhibit TNF-alpha-induced cell death, we studied whether NF-kappaB also assumes a protective role in TNF-alpha-induced cell death in prostate cancer cells. MATERIALS AND METHODS We used two human prostate cancer cell lines of DU145 and PC-3. We prepared two different NF-kappaB inhibitors, pyrrolidine dithiocarbamate (PDTC) and NF-kappaB decoy. NF-kappaB DNA binding activity was detected by electrophoretic mobility shift assay (EMSA). Cell survivals were measured by MTT assay. Induction of apoptosis was detected by nuclear staining and measured by fragmented DNA ELISA. RESULTS EMSA showed that NF-kappaB inhibitors continuously inhibited TNF-alpha-induced NF-kappaB activation. Cell growth was not inhibited by either TNF-alpha (50 ng./ml. or less) or NF-kappaB inhibitors. However, both PCA cells treated with TNF-alpha (20 ng./ml.) plus NF-kappaB inhibitors showed significant growth inhibition compared with controls (p<0.05). Nuclei of PCA cells appeared severely fragmented by this combination therapy. Furthermore, the levels of DNA fragmentation were significantly elevated in PCA cells treated with TNF-alpha (20 ng./ml.) plus NF-kappaB inhibitors compared with controls (p<0.05). CONCLUSIONS NF-kappaB activation is suggested to produce the resistance of DU145 and PC-3 to TNF-alpha and that the combination of TNF-alpha and NF-kappaB inhibitors could be constituted an effective therapy to TNF-alpha-resistant human prostate cancer cells.

3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Inhibitor, Fluvastatin, as a Novel Agent for Prophylaxis of Renal Cancer Metastasis

Purpose: Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, also called statins, are currently used widely as a safe, effective therapeutic in the treatment of hypercholesterolemia. Recently, statins have been recognized for their activity against cancer. In the present study, we examined the effect of a synthetic statin, fluvastatin, on the development of renal cancer. Experimental Design: The effects of fluvastatin on cell viability, cell cycle, in vitro angiogenesis, and invasive properties were examined in murine renal cancer cell Renca. The changes in cell cycle-associated proteins, p21Waf1/Cip1 and p53, and rac1 phosphorylation were analyzed by Western blotting. The prophylactic efficacy of fluvastatin to murine pulmonary metastasis of Renca was examined. Results: Fluvastatin inhibited in vitro growth of Renca cells in a time- and dose-dependent manner, with up to 70% inhibition at a concentration of 10 μmol/L. This inhibitory effect was due to cell cycle arrest at the G1 phase and induction of apoptosis accompanied by up-regulation of p21Waf1/Cip1 and p53. The invasive properties of Renca cells through Matrigel were inhibited by fluvastatin, with decreased phosphorylation of rac1. In vitro angiogenesis was also inhibited by fluvastatin. Furthermore, oral administration at doses of 1 to 10 mg/kg/d, for 12 days after inoculation of Renca cells via the tail vein, significantly decreased the amount of pulmonary metastasis. Conclusions: Because our results suggest that fluvastatin may effectively inhibit in vitro tumor growth, invasion, angiogenesis, and metastasis of Renca cells, oral administration of fluvastatin could be a novel, safe, and effective agent for preventing metastasis of renal cancer.

Impact of thrombocytosis and C-reactive protein elevation on the prognosis for patients with renal cell carcinoma.

Aim: C‐reactive protein (CRP) elevation is reportedly a prognostic factor in patients with renal cell carcinoma (RCC). Thrombocytosis has recently been reported also to be a prognostic factor in RCC and, like CRP, to be related to inflammatory cytokines such as interleukin‐6. The aim of this study was to evaluate the importance of both thrombocytosis and CRP elevation in tumor recurrence and prognosis for patients with RCC.

STAT3 inhibitor WP1066 as a novel therapeutic agent for renal cell carcinoma

Background:Signal transducer and activator of transcription 3 (STAT3) regulates the expression of genes that mediate cell survival, proliferation, and angiogenesis and is aberrantly activated in various types of malignancies, including renal cell carcinoma (RCC). We examined whether it could be a novel therapeutic target for RCC by using the STAT3 inhibitor WP1066.Methods:The antitumour activities and related mechanisms of WP1066 were investigated in vitro on renal cancer cell lines and in vivo on murine xenografts.Results:In Caki-1 and 786-O renal cancer cells, 5 μM WP1066 prevented the phosphorylation of STAT3, and 2.5 μM WP1066 significantly (P<0.01) inhibited cell survival and proliferation. WP1066 suppressed the expression of Bcl-2, induced apoptosis, and inhibited the basal and hypoxia-induced expression of HIF1α and HIF2α, as well as vascular endothelial growth factor secretion into cell culture medium. Human umbilical vascular endothelial cells cocultured with media from WP1066-treated cells showed significantly reduced tubulogenesis (P<0.05). Systemic oral administration of WP1066 to mice for 19 days significantly inhibited the growth of Caki-1 xenograft tumours (P<0.05), and pathological analysis of xenografts of WP1066-treated mice showed decreased immunostaining of phosphorylated STAT3 and reduced length of CD34-positive vessels (P<0.05).Conclusion:Our results suggest that using WP1066 to inhibit the STAT3 signalling pathway could be a novel therapeutic strategy against RCC.

Induction of Apoptosis of Cytokine-Producing Bladder Cancer Cells by Adenovirus-Mediated I kappa B alpha Overexpression

We investigated whether the cell growth and apoptosis of multiple cytokine-producing bladder cancer cells can be regulated by nuclear factor kappaB (NF-kappaB). The bladder cancer cell line KU-19-19, obtained from a 76-year-old man who demonstrated marked leukocytosis, produces multiple cytokines and demonstrates autocrine growth by granulocyte colony-stimulating factor (G-CSF). Electrophoretic mobility shift assay (EMSA) revealed that NF-kappaB was activated in KU-19-19 but not in other bladder cancer cell lines (KU-1, KU-7, or T-24, respectively). The inhibition of NF-kappaB DNA-binding activity with adenovirus vectors expressing the stable form of the NF-kappaB inhibitor IkappaBalpha (multiplicity of infection [MOI] of 10) inhibited growth and induced apoptosis of KU-19-19, but not KU-1, KU-7, or T-24. The production of several cytokines was suppressed significantly in KU-19-19 by this gene delivery. Although dexamethasone (10 microM) could also suppress cytokine production, it did not induce dramatic cell death in KU-19-19 because it could not inhibit NF-kappaB activation stably and strongly. These results suggest that NF-kappaB activation maintains the cell viability as well as regulates cytokine production in cytokine-producing cancer cells and therefore these in vitro experiments support a rationale for preclinical in vivo studies to demonstrate growth inhibition in established tumors.

Novel SN-38–Incorporated Polymeric Micelle, NK012, Strongly Suppresses Renal Cancer Progression

It has been recently reported that NK012, a 7-ethyl-10-hydroxy-camptothecin (SN-38)-releasing nanodevice, markedly enhances the antitumor activity of SN-38, especially in hypervascular tumors through the enhanced permeability and retention effect. Renal cell carcinoma (RCC) is a typical hypervascular tumor with an irregular vascular architecture. We therefore investigated the antitumor activity of NK012 in a hypervascular tumor model from RCC. Immunohistochemical examination revealed that Renca tumors contained much more CD34-positive neovessels than SKRC-49 tumors. Compared with CPT-11, NK012 had significant antitumor activity against both bulky Renca and SKRC-49 tumors. Notably, NK012 eradicated rapid-growing Renca tumors in 6 of 10 mice, whereas it failed to eradicate SKRC-49 tumors. In the pulmonary metastasis treatment model, an enhanced and prolonged distribution of free SN-38 was observed in metastatic lung tissues but not in nonmetastatic lung tissues after NK012 administration. NK012 treatment resulted in a significant decrease in metastatic nodule number and was of benefit to survival. Our study shows the outstanding advantage of polymeric micelle-based drug carriers and suggests that NK012 would be effective in treating disseminated RCCs with irregular vascular architectures.

ZD1839 Modulates Paclitaxel Response in Renal Cancer by Blocking Paclitaxel-Induced Activation of the Epidermal Growth Factor Receptor–Extracellular Signal-Regulated Kinase Pathway

Purpose: We evaluated the antitumor activity of ZD1839, a selective epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor, in combination with paclitaxel in human renal cell carcinomas (RCCs). Experimental Design: Eight human RCC lines and the surgical specimens obtained from 10 RCC patients were used. The protein expression was detected by Western blotting, immunohistochemistry and/or flow cytometry. Apoptosis was evaluated by flow cytometry and fragmented DNA ELISA. SKRC-49 tumor xenografts in athymic nude mice were treated with ZD1839 and/or paclitaxel, and tumor volume was determined Results: EGFR protein was expressed and phosphorylated in eight RCC lines and EGFR expression was markedly increased in RCC specimens compared with adjacent normal renal tissues. Treatment of SKRC-49 with 1 μm ZD1839 resulted in a marked decrease in the phosphorylation of EGFR but not of HER-2. Treatment of SKRC-49 with ZD1839 in combination with 5 nm paclitaxel resulted in a significant increase in apoptotic cell number compared with paclitaxel alone, whereas ZD1839 alone failed to induce apoptosis. Although administration of ZD1839 or paclitaxel resulted in a transient growth inhibition in SKRC-49 xenografts, significant tumor regrowth delay was observed when paclitaxel was combined with ZD1839. Paclitaxel phosphorylated extracellular signal-regulated kinase through EGFR activation predominantly in cancer cells. ZD1839 promoted paclitaxel-induced Bcl-2 down-regulation resulting in promoting apoptosis by blocking paclitaxel-induced activation of the EGFR—extracellular signal-regulated kinase antiapoptotic pathway independent of Akt activity in SKRC-49. Conclusions: Our findings support the idea that the significant clinical benefit is obtained from ZD1839 in combination with paclitaxel for the treatment of RCC.

Patients with renal cysts associated with renal cell carcinoma and the clinical implications of cyst puncture: a study of 223 cases

OBJECTIVES To clarify the association between renal cysts and renal cell carcinoma (RCC), we analyzed patient demographics, types of cystic disease, and modes of cyst-tumor coexistence along with the results of cyst puncture. METHODS A total of 507 hospitals provided information regarding clinical experiences with RCC and cyst puncture over a 2-year period. RESULTS Renal cysts were identified by preoperative imaging in 223 (4%) of 5721 patients with RCC. Histologic examination revealed cystic RCC in 56 patients (25%) and RCC associated with cystic diseases in 167 (75%). Cystic disease included simple cysts in 72 patients (32%), acquired cystic disease of the kidney (ACDK) in 62 (28%), multilocular renal cysts in 20 (9%), polycystic kidney in 3 (1%), and unspecified or miscellaneous in 10. Cyst puncture performed in 47 (21%) of 223 patients demonstrated bloody fluid in 20 cases and nonbloody fluid in 27. Cytologic analysis of cystic fluid obtained from 37 patients revealed a malignancy in 5 (14%), accounting for 25% of the bloody and 4.8% of nonbloody specimens. Cytology failed to detect RCC in ACDK and multilocular cysts but was positive in cases of cystic RCC and solitary cysts. Four of 5 cytology-positive cases comprised those of tumor in cyst and cyst within tumor. CONCLUSIONS Simple cysts and ACDK accounted for 60% of the renal cysts associated with RCC. Cystic RCC was involved in 25% of cases. Positive cytology may be expected in select cases, including those with close cyst-tumor relationships and those involving bloody cyst fluid. However, negative cytology does not exclude RCC.

Induction of CD16+ CD56bright NK Cells with Antitumour Cytotoxicity not only from CD16− CD56bright NK Cells but also from CD16− CD56dim NK Cells

The aim of this study was to examine the effect of cytokines on different subsets of NK cells, while especially focusing on CD16− CD56dim cells and CD16− CD56bright cells. When human peripheral blood mononuclear cells (PBMC) were cultured with a combination of IL‐2, IL‐12 and IL‐15 for several days, a minor population of CD56bright NK cells expanded up to 15%, and also showed potent cytotoxicities against various cancer cells. Sorting experiments revealed that unconventional CD16− CD56+ NK cells (CD16− CD56dim NK cells and CD16− CD56bright NK cells, both of which are less than 1% in PBMC) much more vigorously proliferated after cytokine stimulation, whereas predominant CD16+ CD56dim NK cells proliferated poorly. In addition, many of the resting CD16− CD56bright NK cells developed into CD16+ CD56bright NK cells, and CD16− CD56dim NK cells developed into CD16− CD56bright NK cells and also further into CD16+ CD56bright NK cells by the cytokines. CSFE label experiments further substantiated the proliferation capacity of each subset and the developmental process of CD16+ CD56bright NK cells. Both CD16− CD56dim NK cells and CD16− CD56bright NK cells produced large amounts of IFN‐γ and Fas‐ligands. The CD16+ CD56bright NK cells showed strong cytotoxicities against not only MHC class I (−) but also MHC class I (+) tumours regardless of their expression of CD94/NKG2A presumably because they expressed NKG2D as well as natural cytotoxicity receptors. The proliferation of CD16+ CD56bright NK cells was also induced when PBMC were stimulated with penicillin‐treated Streptococcus pyogenes, thus suggesting their role in tumour immunity and bacterial infections.