title: Induced growth inhibition, cell cycle arrest and apoptosis in CD133+/CD44+ prostate cancer stem cells by flavopiridol.
abstract: Flavopiridol is a flavone that inhibits several cyclin‑dependent kinases and exhibits potent growth‑inhibitory activity, apoptosis and G1‑phase arrest in a number of human tumor cell lines. Flavopiridol is currently undergoing investigation in human clinical trials. The present study focused on the effect of flavopiridol in cell proliferation, cell cycle progression and apoptosis in prostate cancer stem cells (CSCs). Therefore, cluster of differentiation 133 (CD133)(+high)/CD44(+high) prostate CSCs were isolated from the DU145 human prostate cancer cell line. The cells were treated with flavopiridol in a dose‑ and time‑dependent manner to determine the inhibitory effect. Cell viability and proliferation were analyzed and the efficiency of flavopiridol was assessed using the sphere‑forming assay. Flavopiridol was applied to monolayer cultures of CD133(high)/CD44(high) human prostate CSCs at the following final concentrations: 100, 300, 500 and 1000 nM . The cultures were incubated for 24, 48 and 72 h. The half maximal inhibitory concentration (IC(50)) value of the drug was determined as 500 nM for monolayer cells. Dead cells were analyzed prior and subsequent to exposure to increasing flavopiridol doses. Annexin‑V and immunofluorescence analyses were performed for the evaluation of apoptotic pathways. According to the results, flavopiridol treatment caused significant growth inhibition at 500 and 1000 nM when compared to the control at 24 h. G(0)/G(1) analysis showed a statistically significant difference between 100 and 500 nM (P<0.005), 100 and 1000 nM (P<0.001), 300 and 1000 nM (P<0.001), and 500 and 1000 nM (P<0.001). Flavopiridol also significantly influenced the cells in the G(2)/M phase, particularly at high‑dose treatments. Flavopiridol induced growth inhibition and apoptosis at the IC(50) dose (500 nM), resulting in a significant increase in immunofluorescence staining of caspase‑3, caspase‑8 and p53. In conclusion, the present results indicated that flavopiridol could be a useful therapeutic agent for prostate CSCs by inhibiting tumor growth and malignant progression, and inducing apoptosis.
authors.affiliation: Necmettin Erbakan University, Meram Faculty of Medicine, Department of Medical Pharmacology, 42100, Konya, Turkey.
authors.forename: Burak Cem
authors.initials: BC
authors.lastname: Soner
authors.affiliation: Ege University Faculty of Medicine, Department of Histology and Embryology, Bornova 35100, Izmir, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Aktug
authors.affiliation: Ege University Faculty of Medicine, Department of Histology and Embryology, Bornova 35100, Izmir, Turkey.
authors.forename: Eda
authors.initials: E
authors.lastname: Acikgoz
authors.affiliation: Ege University Health Science Institute, Department of Stem Cell, 35100, Izmir, Turkey.
authors.forename: Fahriye
authors.initials: F
authors.lastname: Duzagac
authors.affiliation: Ege University Health Science Institute, Department of Stem Cell, 35100, Izmir, Turkey.
authors.forename: Ummu
authors.initials: U
authors.lastname: Guven
authors.affiliation: Zeynep Kamil Gynecology and Maternity Training and Research Hospital, Department of Obstetrics and Gynecology, 34668 Istanbul, Turkey.
authors.forename: Sule
authors.initials: S
authors.lastname: Ayla
authors.affiliation: Izmir University of Economics, Faculty of Health Sciences, 35330, Izmir, Turkey.
authors.forename: Cag
authors.initials: C
authors.lastname: Cal
authors.affiliation: Ege University Faculty of Medicine, Department of Histology and Embryology, Bornova 35100, Izmir, Turkey.
authors.forename: Gulperi
authors.initials: G
authors.lastname: Oktem
mesh_terms: D000071916:AC133 Antigen; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology*; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D008297:Male; D014411:Neoplastic Stem Cells / Q000187:drug effects*; D010455:Peptides / Q000378:metabolism; D010880:Piperidines / Q000494:pharmacology*; D011467:Prostate / Q000166:cytology / Q000187:drug effects*; D011471:Prostatic Neoplasms / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D005419:Flavonoids; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; D010880:Piperidines; D016159:Tumor Suppressor Protein p53; C077990:alvocidib; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8