zinostatin and Breast-Neoplasms

Topics: Altretamine; Aminoacridines; Amsacrine; Antineoplastic Agents; Breast Neoplasms; Clinical Trials as Topic; Daunorubicin; Doxorubicin; Female; Gallium; Humans; Ifosfamide; Leukemia; Vinblastine; Vindesine; Zinostatin

Topics: Altretamine; Aminoacridines; Amsacrine; Antineoplastic Agents; Breast Neoplasms; Clinical Trials as Topic; Daunorubicin; Doxorubicin; Female; Gallium; Humans; Ifosfamide; Leukemia; Vinblastine; Vindesine; Zinostatin

Cells respond to DNA damage by activating a complex array of signaling networks, which include the AMPK and mTOR pathways. After DNA double-strand breakage, ATM, a core component of the DNA repair system, activates the AMPK-TSC2 pathway, leading to the inhibition of the mTOR cascade. Recently, we showed that both AMPK and mTOR interact with SMYD3, a methyltransferase involved in DNA damage response. In this study, through extensive molecular characterization of gastrointestinal and breast cancer cells, we found that SMYD3 is part of a multiprotein complex that is involved in DNA damage response and also comprises AMPK and mTOR. In particular, upon exposure to the double-strand break-inducing agent neocarzinostatin, SMYD3 pharmacological inhibition suppressed AMPK cascade activation and thereby promoted the mTOR pathway, which reveals the central role played by SMYD3 in the modulation of AMPK-mTOR signaling balance during cancer cell response to DNA double-strand breaks. Moreover, we found that SMYD3 can methylate AMPK at the evolutionarily conserved residues Lys411 and Lys424. Overall, our data revealed that SMYD3 can act as a bridge between the AMPK and mTOR pathways upon neocarzinostatin-induced DNA damage in gastrointestinal and breast cancer cells.

Topics: AMP-Activated Protein Kinases; Breast Neoplasms; DNA; DNA Damage; Female; Histone-Lysine N-Methyltransferase; Humans; TOR Serine-Threonine Kinases; Zinostatin

In response to DNA damage, the transcription factor p53 accumulates in a series of pulses. While p53 dynamics play a critical role in regulating stress responses, how p53 pulsing affects target protein expression is not well understood. Recently, we showed that p53 pulses generate diversity in target mRNA expression dynamics; however, given that mRNA and protein expression are not necessarily well correlated, it remains to be determined how p53 pulses impact target protein expression. Using computational and experimental approaches, we show that target protein decay rates filter p53 pulses: Distinct target protein expression dynamics are generated depending on the relationship between p53 pulse frequency and target mRNA and protein stability. Furthermore, by mutating the targets MDM2 and PUMA to alter their stabilities, we show that downstream pathways are sensitive to target protein decay rates. This study delineates the mechanisms by which p53 dynamics play a crucial role in orchestrating the timing of events in the DNA damage response network.

Topics: Apoptosis Regulatory Proteins; Breast Neoplasms; DNA Breaks, Double-Stranded; Female; Gene Expression Regulation, Neoplastic; Humans; Kinetics; MCF-7 Cells; Models, Biological; Mutation; Protein Stability; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-mdm2; RNA Stability; RNA, Messenger; Signal Transduction; Tumor Suppressor Protein p53; Zinostatin

To clarify the effect of SMANCS on malignant pleural carcinomatosis, seven patients with malignant pleural effusion were treated with SMANCS administered via an intracavitary route. Five patients showed improvement after one or two injections of SMANCS into the thoracic cavity, although 2 patients needed further therapy with the immunopotentiating agent picibanil (OK-432). No serious adverse effects were observed. This simple therapeutic tactic with SMANCS may be effective in cases of malignant pleural carcinomatosis.

Topics: Aged; Antineoplastic Agents; Breast Neoplasms; Colonic Neoplasms; Female; Humans; Lung Neoplasms; Male; Maleic Anhydrides; Middle Aged; Pleural Effusion, Malignant; Polystyrenes; Stomach Neoplasms; Zinostatin

MCF-7 human breast cancer cells do not express caspase 3, thought by some to be a critical component of the apoptosis cascade. Nonetheless, both mock- and bcl-2-transfected MCF-7 cells undergo apoptosis after treatment with a variety of stimuli, including the DNA-cleaving antimitotic agent, neocarzinostatin (NCS). Transfection with bcl-2 shifts the concentration-response curve to NCS but does not change the phenomenology of apoptosis when it occurs. In both cases, NCS treatment results in condensation and fragmentation of MCF-7 cell nuclei and release of cytochrome c from the mitochondria to the cytosol. This apoptosis is accompanied by decreased levels of Bcl-2 and increased levels of Bax. Using a series of caspase inhibitors with overlapping specificities, enzyme-specific chromogenic substrates, and an antibody specific for activated caspase 7, we have determined that apoptosis in MCF-7 cells proceeds via sequential activation of caspases 9, 7 and 6. P21 is detected only after activation of caspase 7, and P53 is neither expressed at baseline nor up-regulated with apoptosis induction. This pathway bypasses the need for activated caspase 3 in these cells.

Topics: Antibiotics, Antineoplastic; Apoptosis; bcl-2-Associated X Protein; Breast Neoplasms; Caspase 3; Caspase Inhibitors; Caspases; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Cysteine Proteinase Inhibitors; Cytochrome c Group; Humans; Kinetics; Models, Biological; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Transfection; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Zinostatin