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Takako Asano

Publications and source records attributed to Takako Asano.

16 recordsLinked to original sources
PubMed2006

Increased serum leptin levels and over expression of leptin receptors are associated with the invasion and progression of renal cell carcinoma.

PURPOSE: Leptin, an adipocyte derived cytokine that is closely associated with obesity, was recently shown to be involved in carcinogenesis and cancer progression. Because obesity is a significant risk factor for renal cell carcinoma, we investigated the link between leptin and the development of renal cell carcinoma. MATERIALS AND METHODS: Associations between preoperative serum leptin levels and leptin receptor expression in tumor specimens and various clinicopathological parameters were analyzed in 57 patients with renal cell carcinoma. RESULTS: Serum leptin levels were 1.2 to 16.2 ng/ml (mean 4.5). Of 57 tumors 22 (38.6%) demonstrated high leptin receptor expression. Serum leptin levels were significantly higher in patients with vs without tumor specimen venous invasion (p = 0.030) and higher in patients with high vs low leptin receptor expression (p = 0.019). There were significant associations between high leptin receptor expression and the presence of venous invasion (p = 0.013), histological type (p = 0.0076) and regional lymph node metastasis (p = 0.047). Of 42 patients with N0M0 disease those with serum leptin 5.0 ng/ml or more had significantly shorter progression-free survival than patients with lower levels (p = 0.0043). Multivariate Cox proportional hazards model analysis demonstrated that higher serum leptin was an independent predictor of progression-free survival (p = 0.0406). CONCLUSIONS: Leptin and leptin receptor could have a key role in the invasion of renal cell carcinoma and they could be valuable predictors of progression.

Adult↗
PubMed2006

Leptin promotes invasiveness of murine renal cancer cells via extracellular signal-regulated kinases and rho dependent pathway.

PURPOSE: Obesity is a significant risk factor for renal cell carcinoma. The adipocyte derived cytokine leptin, which controls body weight homeostasis through food intake and energy expenditure, recently provided a potential link between obesity and cancer development. We examined whether leptin promotes the invasiveness of renal cancer cells and we investigated its underlying signaling pathway. MATERIALS AND METHODS: Leptin receptor expression in the 6 human renal cancer cell lines Caki-1, ACHN, 769P, A498, SKRC44 and SKRC49, and in the murine renal cancer cell line Renca was examined by reverse transcriptase-polymerase chain reaction and Western blotting. The effect of leptin on renal cancer cell invasiveness was assessed by the invasion of cells through Matrigel coated Transwell inserts. Leptin induced intracellular signaling was examined by Western blotting. RESULTS: Leptin receptor was detected in all renal cancer cells examined at the mRNA and protein levels. Leptin increased Renca cell invasiveness at 1 ng/ml (p < 0.05). There was up to 3-fold invasiveness compared to untreated cells at 100 ng/ml with the activation of extracellular signal-regulated kinases and rho guanosine triphosphatase (p < 0.01). Leptin induced activation of rho guanosine triphosphatase was inhibited not only by the rho kinase inhibitor Y27632, but also by the MEK1 inhibitor PD98059, of which each inhibited leptin induced invasion of Renca cells (p < 0.01). CONCLUSIONS: Leptin promoted the invasiveness of murine renal cancer cells via extracellular signal-regulated kinases and rho guanosine triphosphatase dependent pathways. Rho guanosine triphosphatase was a downstream effector of extracellular signal-regulated kinases in leptin induced invasion. Leptin signaling could have a key role in renal cell carcinoma invasion.

Animals↗
PubMed2005

Permanent genetic tagging of podocytes: fate of injured podocytes in a mouse model of glomerular sclerosis.

Injured podocytes lose differentiation markers. Therefore, the true identity of severely injured podocytes remains unverified. A transgenic mouse model equipped with a podocyte-selective injury induction system was established. After induction of podocyte injury, mice rapidly developed glomerulosclerosis, with downregulation of podocyte marker proteins. Proliferating epithelial cells accumulated within Bowman's space, as seen in collapsing glomerulosclerosis. In this study, the fate of injured podocytes was pursued. Utilizing Cre-loxP recombination, the podocyte lineage was genetically labeled with lacZ in an irreversible manner. After podocyte injury, the number of lacZ-labeled cells, which were often negative for synaptopodin, progressively declined, correlating with glomerular damage. Parietal epithelial cells, but not lacZ-labeled podocytes, avidly proliferated. The cells proliferating within Bowman's capsule and, occasionally, on the outer surface of the glomerular basement membrane were lacZ-negative. Thus, when podocytes are severely injured, proliferating parietal epithelial cells migrate onto the visceral site, thereby mimicking proliferating podocytes.

Animals↗
PubMed2005

Rapid downregulation of beta-actin-based CAG promoter and filamentous actin in injured podocytes.

Glomerular visceral epithelial cells or podocytes are located on the outer surface of the glomerular basement membrane and play an indispensable role as a filtration barrier. The core cytoskeleton of the foot processes is actin filaments, which play an important role in maintaining the unique structure of podocytes. We previously established a transgenic mouse line (NEP25), which expresses human (h)CD25 selectively on podocytes. By injecting an hCD25-targeted recombinant immunotoxin (LMB2), podocyte injury can be induced on demand. After LMB2 injection, NEP25 mice develop nephrotic syndrome with downregulation of podocyte-specific proteins. In the present study, we genetically labeled podocytes with lacZ linked with beta-actin-based CAG promoter. Utilizing the Cre-loxP system, this labeling was confined to the podocyte lineage. Without LMB2, all podocytes were positive for lacZ. After LMB2 injection, lacZ expression was rapidly downregulated, before podocytes showed any discernible morphological changes. Confocal imaging of filamentous (F)-actin-binding Alexa 488-phalloidin revealed that the normal continuous pattern of F-actin distribution in podocytes was punctuated after LMB2 injection. These collectively suggest that disturbance of actin filaments may be one of the key initial events leading to subsequent podocyte damage.

Actin Cytoskeleton↗
PubMed2004

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, p21(Waf1/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 mumol/L. This inhibitory effect was due to cell cycle arrest at the G(1) phase and induction of apoptosis accompanied by up-regulation of p21(Waf1/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.

Animals↗
PubMed2004

Identification of bladder cancer antigens recognized by IgG antibodies of a patient with metastatic bladder cancer.

To identify tumor antigens useful for the diagnosis and treatment of patients with bladder cancer, a lambda phage cDNA library constructed from a high-grade bladder cancer cell line was screened with autologous serum from a patient with metastatic bladder cancer. Forty-eight distinct antigens were isolated. By evaluating the immunogenicity and the tissue-specific expression, KU-BL-1 and KU-BL-2 were identified as immunogenic antigens with restricted tissue expression. KU-BL-1 was found to be a putative human lipoic acid synthetase with a metal-binding site, CXXXCXXC, that was expressed in bladder cancer cell lines and most bladder cancer tissues, as well as normal bladder mucosa and testis tissues. Immunoglobulin (Ig)G antibody to KU-BL-1 was detected in 2 of 28 patients with bladder cancer, but not in 30 healthy individuals. KU-BL-2 was found to be a putative human kelch-like protein that was homologous to Drosophila kelch, with a BTB/POZ domain and kelch repeats. KU-BL-2 was expressed in bladder cancer cell lines, most bladder cancer tissues, testis and heart, but not in normal bladder mucosa. IgG antibody to KU-BL-2 was detected in 8 of 28 patients with bladder cancer, but not in 16 healthy individuals. Tumor reactive T cells were induced from peripheral blood mononuclear cells (PBMC) by stimulation with one of the HLA-A24 binding KU-BL-2 peptides. Therefore, KU-BL-1 and KU-BL-2, which showed preferential expression in bladder cancer with restricted expression in normal tissues, as well as immunogenicity in multiple patients with bladder cancer, may be useful for the development of diagnostic and therapeutic methods for patients with bladder cancer.

Aged↗
PubMed2004

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 micro M 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.

Animals↗
PubMed2004

Chemosensitization of androgen-independent prostate cancer with neutral endopeptidase.

PURPOSE: We investigated whether neutral endopeptidase (NEP) could augment chemosensitivity to anticancer drugs by promoting protein kinase C (PKC)delta-mediated mitochondrial apoptosis in prostate cancer (PC) cells. EXPERIMENTAL DESIGN: Human PC cell lines LNCaP and PC-3, and a normal prostate epithelial cell line (PrEC) were used. The protein expression was detected by Western blot analysis, and the protein turnover was determined by pulse-chase assay. Apoptotic ratio was measured by annexin V staining. RESULTS: Western blot analyses and pulse-chase assays showed that the specific NEP inhibitor CGS24592 decreased PKCdelta protein expression by promoting PKCdelta protein degradation in NEP-expressing LNCaP cells. Conversely, recombinant NEP (rNEP) increased PKCdelta protein expression by delaying PKCdelta protein degradation in NEP-negative PC-3 cells. Apoptosis assays showed that rNEP promoted anticancer drug-induced apoptosis in PC-3 cells specifically through PKCdelta activity that mediated anticancer drug-induced mitochondrial change such as cytochrome-c release and caspase-9 activation. Of note, rNEP was able to increase PKCdelta protein expression predominantly in PC-3 cells rather than in PrEC cells. Treatment with rNEP before subtoxic concentrations of etoposide (0.1 micro M) significantly promoted mitochondrial apoptosis compared with only etoposide in PC-3 cells (P < 0.01) but not in PrEC cells. CONCLUSIONS: These results suggest that NEP enzyme activity contributes to anticancer drug-induced PC cell apoptosis dependent on PKCdelta-mediated mitochondrial events. More importantly, the combination of NEP with anticancer drugs may be a promising therapeutic modality because rNEP is able to augment chemosensitivity in androgen-independent PC with minimal toxicity in normal tissues.

Androgens↗
PubMed2004

Modulation of tumor growth and tumor induced angiogenesis after epidermal growth factor receptor inhibition by ZD1839 in renal cell carcinoma.

PURPOSE: ZD1839 or Iressa (AstraZeneca, Macclesfield, United Kingdom) is an orally active, selective epidermal growth factor receptor tyrosine kinase inhibitor. We evaluated the antitumor activity of ZD1839 in human renal cell carcinomas (RCC). MATERIALS AND METHODS: Six established human RCC lines and surgical specimens from 10 patients with RCC were used. Protein expression was detected by Western blotting and/or immunohistochemistry. The concentrations of vascular endothelial growth factor and interleukin-8 in the supernatants were measured by enzyme-linked immunosorbent assay. Cell cycle progression and the apoptotic ratio were evaluated by flow cytometry. In vitro angiogenesis was measured using human umbilical vascular endothelial cells by capillary-like network formation analysis. In vivo SKRC-49 cells injected subcutaneously into athymic nude mice were treated with various doses of ZD1839 orally. The effect of ZD1839 on tumor xenografts angiogenesis was evaluated by immunohistochemistry using CD34 Ab. RESULTS: Epidermal growth factor receptor was activated in all RCC lines and over expressed in 7 of 10 RCC specimens (70%) compared with adjacent normal renal tissues. Treatment of SKRC-49 cells with ZD1839 (0.1 to 10 microM) for 48 hours resulted in the accumulation of cells in the G1 phase and a 30% to 50% decrease in cellular proliferation compared with untreated controls (p <0.01). The tumor xenograft study confirmed that ZD1839 (50 to 100 mg/kg daily) significantly inhibited SKRC-49 tumor growth compared with controls within 3 weeks after treatment (p <0.01). Vascular endothelial growth factor and interleukin-8 production was significantly decreased in ZD1839 treated SKRC-49 cells compared with untreated controls (p <0.01). Treatment of human umbilical vascular endothelial cells with SKRC-49 supernatants treated with ZD1839 for 11 days resulted in an approximate 80% decrease in tubule formation compared with untreated controls (p <0.01). Immunohistochemical assays showed that ZD1839 treatment resulted in a significant decrease in CD34 positive neovessels compared with controls in SKRC-49 xenografts. CONCLUSIONS: These results suggest that the antitumor activity of ZD1839 appears to derive not only from direct inhibition of cell proliferation, but also from the inhibition of tumor angiogenesis in RCC.

Adult↗
PubMed2004

Impact of caveolin-1 expression on clinicopathological parameters in renal cell carcinoma.

PURPOSE: Caveolin-1 is a major structural component of caveolae, which are plasma membrane microdomains implicated in the regulation of intracellular signaling pathways. Previous studies of the expression and function of caveolin-1 in cancer have shown controversial results, indicating that the physiological role of caveolin-1 varies according to cancer type. We evaluated caveolin-1 expression in renal cell carcinoma and investigated its association with pathological features and clinical outcome. MATERIALS AND METHODS: Caveolin-1 expression was evaluated by immunohistochemistry using rabbit polyclonal antibody against caveolin-1 in 60 paraffin embedded primary renal cell carcinoma specimens and 6 metastatic renal cell carcinoma specimens. When more than 50% of all cancer cell cytoplasm stained, the tumor was considered caveolin-1 positive. Associations between caveolin-1 expression, and pathological features and clinical outcomes were analyzed. RESULTS: Of 60 primary tumors 16 (26.7%) and 5 of 6 metastatic tumors (83.3%) were immunoreactive in more than 50% of cancer cells and considered caveolin-1 positive. Although no significant associations between caveolin-1 expression, pathological stage (T stage) and distant metastasis at initial presentation were observed, significant associations between positive caveolin-1 expression and high grade tumor (p = 0.0009) and regional lymph node metastasis at initial presentation (p = 0.0049) and venous invasion (p = 0.0195) were observed. There was no difference in cancer specific survival between caveolin-1 positive and negative groups. However, in 43 patients without metastasis to regional lymph nodes or a distant site at initial presentation (N0M0) the caveolin-1 positive group had significantly shorter progression-free survival than the caveolin-1 negative group (p = 0.0332). CONCLUSIONS: Caveolin-1 over expression could be a common finding in aggressive forms of renal cell carcinoma. Caveolin-1 might have an important role in the invasion and metastatic progression of renal cell carcinoma.

Adult↗
PubMed2004

Atorvastatin ameliorates renal tissue damage in unilateral ureteral obstruction.

PURPOSE: The current study was done to determine whether atorvastatin, the HMGCoA (3-hydroxy-3-methylglutaryl CoA) reductase inhibitor, could decrease renal transforming growth factor-beta (TGF-beta) levels in unilateral ureteral obstruction (UUO) and concomitantly affect renal tissue damage in UUO. MATERIALS AND METHODS: Atorvastatin (20 mg/kg) was administered to rats 1 day prior to UUO and every day thereafter. Kidneys were harvested at day 14 after UUO. Tissue TGF-beta was measured by bioassay using mink lung epithelial cells. Renal tubular proliferation and apoptosis were detected by immunostaining proliferating cell nuclear antigen and polyclonal antisingle strand DNA antibody, respectively. Fibrosis was assessed by measuring collagen deposition with trichrome stained slides. Interstitial leukocyte was detected by immunostaining CD45. RESULTS: TGF-beta bioassay showed that the obstructed kidney in the control group contained significantly higher TGF-beta than the unobstructed kidney in the control group (mean +/- SD 79.1 +/- 48.5 vs 28.7 +/- 13.7 pg/mg tissue) and atorvastatin significantly decrease tissue TGF-beta in the obstructed kidney (53.4 +/- 37.0 pg/mg tissue). Immunostaining polyclonal antisingle strand DNA antibody demonstrated that the obstructed kidney in the control group has significantly more tubular apoptosis than the unobstructed counterpart (4.8 +/- 2.8 vs 2.1 +/- 1.2 nuclei per high power field) and atorvastatin significantly decreased renal tubular apoptosis in the obstructed kidney (1.1 +/- 0.7 nuclei per high power field). In addition, immunostaining proliferating cell nuclear antigen showed that the obstructed kidney in the atorvastatin group had significantly more renal tubular proliferation than the obstructed kidney in the control group (48.7 +/- 20.8 vs 17.3 +/- 10.6 per high power field). Control obstructed kidney showed significantly more fibrosis, which was also blunted by atorvastatin. CONCLUSIONS: Atorvastatin significantly decreases tissue TGF-beta, resulting in a decrease in tubular damage and interstitial fibrosis. This suggests that atorvastatin is a promising agent for preventing renal tubular damage in UUO.

Animals↗
PubMed2003

Selective Akt inactivation and tumor necrosis actor-related apoptosis-inducing ligand sensitization of renal cancer cells by low concentrations of paclitaxel.

Recent studies demonstrated that the resistance of cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) could be reversed by various chemotherapeutic agents. In the present study, we investigated the role of Akt in the apoptosis resistance to TRAIL and chemotherapeutic agents-induced TRAIL sensitization in human renal cell carcinoma cells. Apoptosis assays and Western blot analyses revealed that apoptosis resistance to TRAIL correlates well with the level of Akt phosphorylation at Ser 473 rather than protein expression levels of TRAIL receptors, DR4 and DR5. The apoptosis sensitivity to TRAIL in TRAIL-resistant SKRC-49 and TRAIL-sensitive Caki-1 cells was altered by modulation of Akt activity, which increased the protein expression of cellular FADD-like IL-1beta-converting enzyme-like inhibitory protein (cFLIP). Paclitaxel (5 and 100 nM) and cisplatin (10 microM) but not etoposide (1 and 10 microM) promoted TRAIL-induced apoptosis in SKRC-49 cells, which was not mediated by increased TRAIL receptor expression but by chemotherapeutic agents-induced Akt inactivation through ceramide formation derived from sphingomyelin hydrolysis. Of note, the low concentration (5 nM) of paclitaxel promoted ceramide formation and TRAIL-induced apoptosis predominantly in SKRC-49 cells but not in the normal renal proximal tubular epithelial cells. Our results may provide a novel therapeutic modality for selective killing of renal cell carcinoma with minimal toxicity on normal renal cells.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2003

Loss of expression of transforming growth factor-beta receptor as a prognostic factor in patients with renal cell carcinoma.

OBJECTIVES: To determine the clinical implication of the loss of transforming growth factor-beta (TGF-beta) receptor (TbetaR) expression for the pathologic features in renal cell carcinoma (RCC) and the prognosis of 62 patients (Stage I, 4; Stage II, 28; Stage III, 11; and Stage IV, 19) who underwent radical nephrectomy for RCC. Loss of expression in TbetaR could result in escape from the growth inhibitory effect of TGF-beta in TGF-beta-secreting cancer. METHODS: TbetaR and apoptosis in the tumor were detected by immunohistochemistry using samples from 62 patients. We statistically investigated the relationship among the TbetaR expression pattern, pathologic features, and the prognosis of patients with RCC. RESULTS: A loss of expression of TbetaR-I and TbetaR-II was identified in 29 patients (46.7%) and 31 patients (50.0%), respectively. Although the loss of TbetaR-I was not associated with clinical stage, the loss of TbetaR-II was associated with clinical stage (P <0.01). Univariate analysis of all patients demonstrated that Stage T3 or greater, clinical Stage III or greater, loss of TbetaR-II, and a tumor apoptotic index of less than 35 were associated with a significantly lower survival rate than their respective counterparts. Multivariate analysis showed that the only two significant prognostic factors were clinical stage and loss of TbetaR-II. In addition, TbetaR-negative RCC had significantly lower apoptosis than did TbetaR-positive RCC. CONCLUSIONS: These results suggest that a loss of TbetaR-II expression in the primary tumor is a significant prognostic factor in patients with RCC.

Adult↗
PubMed2002

Angiotensin II type I antagonist prevents pulmonary metastasis of murine renal cancer by inhibiting tumor angiogenesis.

Angiotensin II (AII) is a potent vasoconstrictor peptide from the renin-angiotensin system in the kidney. The AII type 1 receptor (AT1R) is reportedly expressed in several tumors including renal cell carcinoma, and AII is involved in tumor angiogenesis. We p.o. administered the long-acting AT1R antagonist, candesartan (10 mg/kg), to the 16 days mouse renal cancer lung metastasis model to test the preventive effects in tumor metastasis. Pulmonary metastases of renal cancer showed prominent AT1R expression in both mice and humans, and candesartan treatment dramatically prevented lung metastatic nodules (14.9 +/- 1.8; P < 0.0001; n = 12) in mice along with the inhibition of neovascularization and vascular endothelial growth factor expression, compared with control metastatic mice (123.3 +/- 8.6; n = 13). Candesartan is widely used clinically, so it seems to be a reasonable therapy for patients with lung metastases of renal cell carcinoma.

Adult↗
PubMed2002

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

We studied the role of protein kinase C isoform PKCdelta 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 PKCdelta-positive LNCaP and DU145 cells but not in PKCdelta-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 PKCdelta inhibitor, significantly inhibited drug-induced Cer formation and apoptosis in LNCaP cells, as did overexpression of dominant negative-type PKCdelta. Overexpression of wild-type PKCdelta 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 PKCdelta 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 PKCdelta mitochondrial translocation. These results indicate that PKCdelta plays a crucial role in activating anticancer drug-induced apoptosis signaling by amplifying the Cer-mediated mitochondrial amplification loop.

Acetophenones↗