Salinomycin induces apoptosis and senescence in breast cancer: upregulation of p21, downregulation of survivin and histone H3 and H4 hyperacetylation.
BACKGROUND
In the present study, we investigated the effect of Salinomycin on the survival of three human breast cancer cell lines MCF-7, T47D and MDA-MB-231 grown in adherent culture conditions.


METHODS
Cell viability was measured by Cell Titer-Glo and Trypan blue exclusion assay. Apoptosis was determined by caspase 3/7 activation, PARP cleavage and Annexin V staining. Cell cycle distribution was assessed by propidium iodide flow cytometry. Senescence was confirmed by measuring the senescence-associated β-galactosidase activity. Changes in protein expression and histone hyperacetylation was determined by western blot and confirmed by immunofluorescence assay.


RESULTS
Salinomycin was able to inhibit the growth of the three cell lines in time- and concentration-dependent manners. We showed that depending on the concentrations used, Salinomycin elicits different effects on the MDA-MB-231 cells. High concentrations of Salinomycin induced a G2 arrest, downregulation of survivin and triggered apoptosis. Interestingly, treatment with low concentrations of Salinomycin induced a transient G1 arrest at earlier time point and G2 arrest at later point and senescence associated with enlarged cellmorphology, upregulation of p21 protein, increase in histone H3 and H4 hyperacetylation and expression of SA-β-Gal activity. Furthermore, we found that Salinomycin was able to potentiate the killing of the MCF-7 and MDA-MB-231 cells, by the chemotherapeutic agents, 4-Hydroxytamoxifen and frondo side A, respectively.


CONCLUSIONS
Our data are the first to link senescence and histone modifications to Salinomycin.


CONCLUSIONS
This study provides a new insight to better understand the mechanism of action of Salinomycin, at least in breast cancer cells.
Department of Biology, College of Science, UAE University, P.O. Box: 17551, United Arab Emirates University, Al-Ain, P.O. Box 15551, United Arab Emirates.
Yusra
Y
Al Dhaheri
Samir
S
Attoub
Kholoud
K
Arafat
Synan
S
Abuqamar
Ali
A
Eid
Nesreen
N
Al Faresi
Rabah
R
Iratni
D000107:Acetylation; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics* / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005260:Female; D016195:G2 Phase / Q000187:drug effects; D006027:Glycosides / Q000494:pharmacology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000037:antagonists & inhibitors / Q000502:physiology; D011714:Pyrans / Q000494:pharmacology*; D000077022:Survivin; D014315:Triterpenes / Q000494:pharmacology; D000095662:Polyether Polyketides
D000900:Anti-Bacterial Agents; D050759:Cyclin-Dependent Kinase Inhibitor p21; D003598:Cytoskeletal Proteins; D006027:Glycosides; D006657:Histones; D051034:Inhibitor of Apoptosis Proteins; D011714:Pyrans; D000077022:Survivin; D014315:Triterpenes; C107489:BIRC5 protein, human; C088832:CCDC6 protein, human; C493956:CDKN1A protein, human; C468783:H2AX protein, human; C534797:frondoside A; C010327:salinomycin; D000095662:Polyether Polyketides