title: Molecular mode of action and role of TP53 in the sensitivity to the novel epothilone sagopilone (ZK-EPO) in A549 non-small cell lung cancer cells.
abstract: Sagopilone, an optimized fully synthetic epothilone, is a microtubule-stabilizing compound that has shown high in vitro and in vivo activity against a broad range of human tumor models. We analyzed the differential mechanism of action of sagopilone in non-small cell lung cancer cell lines in vitro. Sagopilone inhibited proliferation of non-small cell lung cancer cell lines at lower nanomolar concentration. The treatment with sagopilone caused strong disturbances of cellular cytoskeletal organization. Two concentration-dependent phenotypes were observed. At 2.5 nM sagopilone or 4 nM paclitaxel an aneuploid phenotype occur whereas a mitotic arrest phenotype was induced by 40 nM sagopilone or paclitaxel. Interestingly, treatment with 2.5 nM of sagopilone effectively inhibited cell proliferation, but--compared to high concentrations (40 nM)--only marginally induced apoptosis. Treatment with a high versus a low concentration of sagopilone or paclitaxel regulates a non-overlapping set of genes, indicating that both phenotypes substantially differ from each other. Genes involved in G2/M phase transition and the spindle assembly checkpoint, like Cyclin B1 and BUBR1 were upregulated by treatment with 40 nM sagopilone. Unexpectedly, also genes involved in DNA damage response were upregulated under that treatment. In contrast, treatment of A549 cells with a low concentration of sagopilone revealed an upregulation of direct transcriptional target genes of TP53, like CDKN1A, MDM2, GADD45A, FAS. Knockdown of TP53, which inhibited the transcriptional induction of TP53 target genes, led to a significant increase in apoptosis induction in A549 cells when treated with a low concentration of sagopilone. The results indicate that activation of TP53 and its downstream effectors like CDKN1A by low concentrations of sagopilone is responsible for the relative apoptosis resistance of A549 cells and might represent a mechanism of resistance to sagopilone.
authors.affiliation: Global Drug Discovery, Bayer Healthcare, Berlin, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Winsel
authors.forename: Anette
authors.initials: A
authors.lastname: Sommer
authors.forename: Julia
authors.initials: J
authors.lastname: Eschenbrenner
authors.forename: Kevin
authors.initials: K
authors.lastname: Mittelstaedt
authors.forename: Ulrich
authors.initials: U
authors.lastname: Klar
authors.forename: Stefanie
authors.initials: S
authors.lastname: Hammer
authors.forename: Jens
authors.initials: J
authors.lastname: Hoffmann
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D052160:Benzothiazoles / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D004249:DNA Damage; D034261:Epothilones / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008175:Lung Neoplasms / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D017239:Paclitaxel / Q000494:pharmacology; D010641:Phenotype; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D052160:Benzothiazoles; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D034261:Epothilones; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C530494:sagopilone; D017239:Paclitaxel