Role of prosurvival molecules in the action of lidamycin toward human tumor cells.
OBJECTIVE
Lidamycin, an enediyne antibiotic, leads to apoptosis and mitotic cell death of human tumor cells at high and low concentrations. The reason why tumor cells have distinct responses to lidamycin remains elusive. This study was to elucidate if cellular prosurvival molecules are involved in these responses.


METHODS
Cleavage of chromatin and DNA was observed by chromatin condensation and agarose gel electrophoresis. Accumulation of rhodamine 123 in lidamycin-treated cells was assayed by flow cytometry. Cell multinucleation was detected by staining with Hoechst 33342. Western blot and senescence-associated beta-galactosidase (SA-beta-gal) staining were used to analyze protein expression and senescence-like phenotype, respectively.


RESULTS
SIRT1 deacetylase remained unchanged in 0.5 nmol/L lidamycin whereas cleavage occurred when apoptosis was induced by lidamycin. Increased FOXO3a, SOD-1 and SOD-2 expression and transient phosphorylation of ERK were detected after exposure of human hepatoma BEL-7402 cells to 0.5 nmol/L lidamycin. High expressions of SIRT1 and Akt were found in colon carcinoma HCT116 p53 knock-out cells exposed to lidamycin. Degradation of PARP and p53 by lidamycin as a substitute for SIRT1 and Akt was confirmed with caspase inhibitor Q-VD-OPh and proteasome inhibitor MG132. Resistance to lidamycin-induced DNA cleavage was observed in breast cancer doxorubicin-resistant MCF-7 cells. This was not induced by P-glycoprotein as no accumulation of rhodamine 123 was detected in the resistant cells following exposure to lidamycin. In contrast to sensitive MCF-7 cells, a lower multinucleation rate for the resistant cells was measured following exposure to equal concentrations of lidamycin.


CONCLUSIONS
Cellular prosurvival molecules, such as SIRT1, Akt, SOD-1, SOD-2 and other unknown factors can influence the action of lidamycin on human tumor cells.
Yang
A-Jing
AJ
Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100050, China.
Shi
Wei-Wei
WW
Li
Yong
Y
Wang
Zhen
Z
Shao
Rong-Guang
RG
Li
Dian-Dong
DD
He
Qi-Yang
QY
D000617:Aminoglycosides / Q000494:pharmacology*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D053837:DNA Cleavage; D004317:Doxorubicin / Q000494:pharmacology; D053281:Enediynes / Q000494:pharmacology*; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D056564:Sirtuin 1; D037761:Sirtuins / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
D000617:Aminoglycosides; D000903:Antibiotics, Antineoplastic; D053281:Enediynes; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D016159:Tumor Suppressor Protein p53; C058024:C 1027; D004317:Doxorubicin; D011065:Poly(ADP-ribose) Polymerases; D051057:Proto-Oncogene Proteins c-akt; D020929:Mitogen-Activated Protein Kinase Kinases; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D037761:Sirtuins