title: Gossypol exerts its cytotoxic effect on HL-60 leukemic cell line via decreasing activity of protein phosphatase 2A and interacting with human telomerase reverse transcriptase activity.
abstract: In this study, we aimed to investigate the potential relationship between gossypol-induced cytotoxicity of human promyelocytic leukemia cell line (HL-60) leukemic cells and intracellular serine/threonine protein phosphatase (PP) dynamics and human telomerase reverse transcriptase (hTERT) activity. Gossypol was found to be cytotoxic in HL-60 cells with the IC(50) dose of 4.5 microM. The combination of gossypol and okadaic acid in IC(50) doses revealed the increased cytotoxicity in a time-dependent manner. Treatment of cells with gossypol has shown significant decrease in PP2A activity. The expression of the PP2A catalytic subunit was downregulated in gossypol-treated cells with 24 hours' intervals. hTERT mRNA levels were gradually decreased. In conclusion, during gossypol-induced cytotoxicity, intracellular activity and expression of PP2A was decreased as well as the activity of hTERT. The variation of hTERT activity in gossypol-treated HL-60 cells may be the potential reason for the phosphatase interaction during the gossypol treatment of leukemic cells resulting in cellular cytotoxicity.
authors.affiliation: Department of Hematology, Ege University School of Medicine, Bornova, Izmir, Turkey.
authors.forename: Fahri
authors.initials: F
authors.lastname: Sahin
authors.forename: Cigir Biray
authors.initials: CB
authors.lastname: Avci
authors.forename: Cumhur
authors.initials: C
authors.lastname: Gunduz
authors.forename: Canfeza
authors.initials: C
authors.lastname: Sezgin
authors.forename: Ilgin Yildirim
authors.initials: IY
authors.lastname: Simsir
authors.forename: Guray
authors.initials: G
authors.lastname: Saydam
mesh_terms: D017209:Apoptosis / Q000235:genetics; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006072:Gossypol / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000201:enzymology; D019319:Okadaic Acid / Q000494:pharmacology; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism*
chemical_list: D019319:Okadaic Acid; C509186:TERT protein, human; D019098:Telomerase; D054648:Protein Phosphatase 2; D006072:Gossypol