ku-55933 and Carcinoma

We exploited the biological activity of an antibiotic agent asperlin isolated from Aspergillus nidulans against human cervical carcinoma cells. We found that asperlin dramatically increased reactive oxygen species (ROS) generation accompanied by a significant reduction in cell proliferation. Cleavage of caspase-3 and PARP and reduction of Bcl-2 could also be detected after asperlin treatment to the cells. An anti-oxidant N-acetyl-L-cysteine (NAC), however, blocked all the apoptotic effects of asperlin. The involvement of oxidative stress in asperlin induced apoptosis could be supported by the findings that ROS- and DNA damage-associated G2/M phase arrest and ATM phosphorylation were increased by asperlin. In addition, expression and phosphorylation of cell cycle proteins as well as G2/M phase arrest in response to asperlin were significantly blocked by NAC or an ATM inhibitor KU-55933 pretreatment. Collectively, our study proved for the first time that asperlin could be developed as a potential anti-cancer therapeutics through ROS generation in HeLa cells.

Topics: Anti-Bacterial Agents; Antibiotics, Antineoplastic; Apoptosis; Aspergillus nidulans; Ataxia Telangiectasia Mutated Proteins; Carcinoma; Cell Cycle Proteins; Cell Division; Checkpoint Kinase 2; DNA-Binding Proteins; Epoxy Compounds; Female; G2 Phase; HeLa Cells; Humans; Morpholines; Protein Serine-Threonine Kinases; Pyrones; Reactive Oxygen Species; Tumor Suppressor Proteins; Uterine Cervical Neoplasms

Premature or stress-induced senescence is a major cellular response to chemotherapy in solid tumors and contributes to successful treatment. However, senescent tumor cells are resistant to apoptosis and may also reenter the cell cycle. We set out to find a means to specifically induce senescent tumor cells to undergo cell death and not to reenter the cell cycle that may have general application in cancer therapy.. We investigated the mechanisms regulating cell survival in drug-induced senescent tumor cells. Using immunofluorescence and flow cytometry-based techniques, we established the status of the ataxia telangiectasia mutated (ATM) signaling pathway in these cells. We assayed the requirement of ATM signaling and p21(CIP1) expression for survival in premature senescent tumor cells using pharmacologic inhibitors and antisense oligonucleotides.. The ATM/ATR (ATM- and Rad3-related) signaling pathway was found to be constitutively active in drug-induced senescent tumor cells. We found that blocking ATM/ATR signaling with pharmacologic inhibitors, including the novel ATM inhibitors KU55933 and CGK733, induced senescent breast, lung, and colon carcinoma cells to undergo cell death. We show that the mechanism of action of this effect is directly via p21(CIP1), which acts downstream of ATM. This is in contrast to the effects of ATM inhibitors on normal, untransformed senescent cells.. Blocking ATM and/or p21(CIP1) following initial treatment with a low dose of senescence-inducing chemotherapy is a potentially less toxic and highly specific treatment for carcinomas.

Topics: Ataxia Telangiectasia Mutated Proteins; Benzeneacetamides; Breast Neoplasms; Carcinoma; Cell Cycle; Cell Cycle Proteins; Cell Survival; Cellular Senescence; Colonic Neoplasms; Cyclin-Dependent Kinase Inhibitor p21; DNA Damage; DNA-Binding Proteins; Drug Evaluation, Preclinical; Gene Expression Regulation, Neoplastic; HCT116 Cells; Humans; Lung Neoplasms; Morpholines; Protein Serine-Threonine Kinases; Pyrones; Thiourea; Tumor Cells, Cultured; Tumor Suppressor Proteins