nitrophenols and Kidney-Neoplasms

Aspirin is a novel chemopreventive agent against malignancy. However, outcomes of aspirin monotherapy of renal cell carcinoma (RCC) are inconsistent across studies. ABT-737, an BH3 mimetic inhibitor, is also a promising antitumor drug. Cancer cells including those from RCC, that have high levels of Mcl-1, are refractory to ABT-737-induced apoptosis. We here investigated how aspirin treatment modulates the ABT-737-induced apoptosis. Using the in vitro model of human 786-O cells, we showed that aspirin had sensitized cells to ABT-737 induced apoptosis. Such aspirin-induced changes of ABT-737 resistance was accompanied by a host of biochemical events like protein phosphatase 2A (PP2A) activation, AKT dephosphorylation, Mcl-1/FLICE inhibiting protein (FLIP)/XIAP downregulation, and Bax mitochondrial redistribution. The PP2A inhibitor, okadaic acid, was able to reverse the apirin-induced apoptotic changes. Apart from the aspirin treatment, Mcl-1 silencing also rendered cells vulnerable to ABT-737 induced apoptosis. Since PP2A, Akt, and Mcl-1 play critical roles in RCC malignancy and treatment resistance, our present study showed that aspirin, an alternative adjuvant agent, had recalled ABT-737 sensitivity in the RCC cells through processes involving the PP2A/Akt/Mcl-1 axis.

Topics: Anticarcinogenic Agents; Apoptosis; Aspirin; Biphenyl Compounds; Carcinoma, Renal Cell; Cell Line, Tumor; Cell Survival; Drug Resistance, Neoplasm; Drug Synergism; Humans; Kidney Neoplasms; Myeloid Cell Leukemia Sequence 1 Protein; Nitrophenols; Piperazines; Protein Phosphatase 2; Proto-Oncogene Proteins c-akt; RNA, Small Interfering; Sulfonamides

Renal cell carcinoma (RCC) is the most common malignancy in the kidney in the world, and the 5-year overall survival for patients remains poor due to the lack of effective treatment strategies. Although ABT-737, as a Bcl-2/Bcl-xL inhibitor, has recently emerged as a novel cancer therapeutic reagent, apoptosis induced by ABT-737 is often blocked in several types of cancer cells. This study investigated whether the combination of the small-molecule BH3 mimetic ABT-737 and the lysosome inhibitor chloroquine was an effective strategy for treating renal cancer cells. We found that the combination of ABT-737 and chloroquine synergistically decreased cell viability when compared to treatment with either single reagent. Cell apoptosis induced by a combined treatment was markedly inhibited by the caspase inhibitors z-DEVD-FMK and z-VAD-FMK. It was also inhibited by cathepsin inhibitor E-64 and CTSI (cathepsin inhibitor), which suggested that apoptosis was dependent on the cascade of caspase activation and cathepsins released from lysosomes. Furthermore, we found that ABT-737 could increase the cell level of ROS, which triggers cathepsin-mediated cell death and augments the role of chloroquine in cell death. So the combination of ABT-737 and chloroquine was an effective strategy for the treatment of renal cancer cells, and this combined strategy may widen the therapeutic window of ABT-737 and chloroquine as well as enhance the clinical efficacy of synergistic drug combinations.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Biphenyl Compounds; Carcinoma, Renal Cell; Cell Death; Cell Line, Tumor; Chloroquine; Drug Synergism; Humans; Kidney Neoplasms; Leucine; Nitrophenols; Oligopeptides; Piperazines; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Thiadiazoles

Although ABT-737, a small-molecule Bcl-2/Bcl-xL inhibitor, has recently emerged as a novel cancer therapeutic agent, ABT-737-induced apoptosis is often blocked in several types of cancer cells with elevated expression of Mcl-1. Cafestol, one of the major compounds in coffee beans, has been reported to have anti-carcinogenic activity and tumor cell growth-inhibitory activity, and we examined whether cafestol could overcome resistance against ABT-737 in Mcl-1-overexpressed human renal carcinoma Caki cells. ABT-737 alone had no effect on apoptosis, but cafestol markedly enhanced ABT-737-mediated apoptosis in Mcl-1-overexpressed Caki cells, human glioma U251MG cells, and human breast carcinoma MDA-MB231 cells. By contrast, co-treatment with ABT-737 and cafestol did not induce apoptosis in normal human skin fibroblast. Furthermore, combined treatment with cafestol and ABT-737 markedly reduced tumor growth compared with either drug alone in xenograft models. We found that cafestol inhibited Mcl-1 protein expression, which is important for ABT-737 resistance, through promotion of protein degradation. Moreover, cafestol increased Bim expression, and siRNA-mediated suppression of Bim expression reduced the apoptosis induced by cafestol plus ABT-737. Taken together, cafestol may be effectively used to enhance ABT-737 sensitivity in cancer therapy via downregulation of Mcl-1 expression and upregulation of Bim expression.

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Biphenyl Compounds; Carcinoma, Renal Cell; Cell Line, Tumor; Diterpenes; Drug Synergism; Drug Therapy, Combination; Fibroblasts; Gene Expression Regulation, Neoplastic; Humans; Kidney Neoplasms; Male; Membrane Proteins; Mice; Mice, Nude; Myeloid Cell Leukemia Sequence 1 Protein; Nitrophenols; Piperazines; Primary Cell Culture; Proto-Oncogene Proteins; RNA, Small Interfering; Signal Transduction; Sulfonamides; Xenograft Model Antitumor Assays

Inhibitors of PI3-K/Akt are currently being assessed clinically in patients with advanced RCC. Identification of therapeutic strategies that might enhance the efficacy of PI3-K/Akt inhibitors is therefore of great interest. As PI3-K inhibition would be expected to have many pro-apoptotic effects, we hypothesized that there may be unique synergy between PI3-K inhibitors and BH3-mimetics. Towards this end, we assessed the combination of the PI3K inhibitor LY 294002 and the Bcl-2 family inhibitor ABT-737 in RCC cell lines. We found that the combinatorial treatment with these agents led to a significant increase in PARP cleavage and cell death in all RCC cell lines. The synergized cell death was correlated with decreased levels of Mcl-1 and XIAP, and increased levels in Bim, and appears critically dependent upon the activation of caspase 3 and 8. The enhanced lethality observed with the combination also appears dependent upon the regulation of XIAP, Mcl-1 and Bim levels. Our results suggest that the combination of PI3-K inhibitors with BH3-mimetics may be a viable therapeutic strategy in RCC.

Topics: Apoptosis; Biphenyl Compounds; Blotting, Western; Carcinoma, Renal Cell; Caspase 3; Caspase 8; Cell Proliferation; Chromones; Drug Synergism; Enzyme Inhibitors; Humans; Kidney Neoplasms; Morpholines; Myeloid Cell Leukemia Sequence 1 Protein; Nitrophenols; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Piperazines; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Tumor Cells, Cultured; X-Linked Inhibitor of Apoptosis Protein

Human renal cell carcinoma (RCC) is very resistant to chemotherapy. ABT-737 is a novel inhibitor of anti-apoptotic proteins of the Bcl-2 family that has shown promise in various preclinical tumour models.. We here report a strong over-additive pro-apoptotic effect of ABT-737 and etoposide, vinblastine or paclitaxel but not 5-fluorouracil in cell lines from human RCC. ABT-737 showed very little activity as a single agent but killed RCC cells potently when anti-apoptotic Mcl-1 or, unexpectedly, A1 was targeted by RNAi. This potent augmentation required endogenous Noxa protein since RNAi directed against Noxa but not against Bim or Puma reduced apoptosis induction by the combination of ABT-737 and etoposide or vinblastine. At the level of mitochondria, etoposide-treatment had a similar sensitizing activity and allowed for ABT-737-induced release of cytochrome c.. Chemotherapeutic drugs can overcome protection afforded by Mcl-1 and A1 through endogenous Noxa protein in RCC cells, and the combination of such drugs with ABT-737 may be a promising strategy in RCC. Strikingly, A1 emerged in RCC cell lines as a protein of similar importance as the well-established Mcl-1 in protection against apoptosis in these cells.

Topics: Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Carcinoma, Renal Cell; Cell Line, Tumor; Drug Synergism; Humans; Kidney Neoplasms; Mitochondria; Myeloid Cell Leukemia Sequence 1 Protein; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Sulfonamides

To compare N-acetyl-beta-hexosaminidase (HEX) activity in the serum and urine of smokers as well as non-smokers with renal cancer, and healthy people.. To assess hexosaminidase activity the level of p-nitrophenol released from p-nitrophenol derivatives was measured.. The activity of enzyme was significantly higher in cancer group, with the highest activity in non-smokers.. Cigarette smoking can inhibit, by the influence on HEX activity, catabolism of oligosaccharide chains in cancer tissues.

Topics: beta-N-Acetylhexosaminidases; Biomarkers, Tumor; Humans; Kidney Neoplasms; Nitrophenols; Oligosaccharides; Risk Factors; Smoking

Topics: Epoxy Compounds; Female; Glutathione; Glutathione Transferase; Humans; Isoenzymes; Kidney Cortex; Kidney Neoplasms; Male; Naphthalenes; Nitrophenols; Sex Characteristics

1,1-Dichloroethene is used as intermediate in the manufacture of polymers. In male mice, 1,1-dichloroethene caused renal tumors after inhalation. Renal tumors were not observed in female mice or in both sexes of rats. We investigated the metabolic basis for the species- and sex-specific nephrotoxicity and tumorigenicity of 1,1-dichloroethene. Kidney microsomes from male mice biotransformed 1,1-dichloroethene to chloroacetic acid; the amounts of chloroacetic acid formed were dependent on the hormonal status of the animals and correlated well with the ability of kidney microsomes to oxidize p-nitrophenol and chlorozoxazone, specific substrates for cytochrome P450 2E1. In kidney microsomes from naive females, significantly lower rates of oxidation of 1,1-dichloroethene, p-nitrophenol, and chlorozoxazone were observed; oxidation could be induced by testosterone. With a rabbit anti-rat liver cytochrome P450 2E1 antibody, a cross-reactive protein was detected in male mouse kidney microsomes with a molecular weight very similar to that of rat liver cytochrome P450 2E1; the expression of this protein was regulated by testosterone and correlated well with the ability of the microsomes to oxidize p-nitrophenol, chlorozoxazone, and 1,1-dichloroethene. When the relative cytochrome P450 2E1 contents of renal microsomes of male mice from different strains were compared, differences in the expression of cytochrome P450 2E1 were observed. Moreover, nephrotoxicity in Swiss-Webster mice after inhalation of 1,1-dichloroethene was observed only in males and testosterone-treated females, but not in naive females. In kidney microsomes obtained from both sexes of rats and in six samples of human kidney (male donors), no p-nitrophenol oxidase activity was detected. These data suggest that cytochrome P450 2E1 or a P450 enzyme with very similar molecular weight, substrate specificities, and immunological properties is expressed only in male mouse kidney and bioactivates 1,1-dichloroethene.

Topics: Acetates; Administration, Inhalation; Animals; Biotransformation; Blotting, Western; Carcinogens; Chlorzoxazone; Cytochrome P-450 CYP2E1; Cytochrome P-450 Enzyme System; Dichloroethylenes; Female; Humans; Hydroxylation; Kidney; Kidney Neoplasms; Liver; Lung; Male; Mice; Microsomes; Nitrophenols; Oxidation-Reduction; Oxidoreductases, N-Demethylating; Rats; Sex Factors; Species Specificity; Testosterone