Methylprednisolone induces apoptosis by interacting with the JAK/STAT pathway in HL-60 and K-562 leukemic cells.
OBJECTIVE
To determine the gene expression profiles of the JAK/STAT pathway members STAT3, STAT5A, STAT5B at both mRNA and protein levels in HL-60 and K-562 leukemia cells that were undergoing apoptosis following high-dose methylprednisolone (MP) treatment.


METHODS
HL-60 cells were treated with 0.1 mM MP and K-562 cells were treated with 0.4 mM MP according to their IC(50) values. STAT3, STAT5A, and STAT5B mRNA relative expression levels were determined by qRT-PCR whereas the protein levels were detected via western-blot analysis and apoptosis was evaluated by Annexin V method.


RESULTS
A significant decrease was seen in STAT5A mRNA relative expression level at 48 hours of MP treatment (P < 0.05) both in HL-60 and K-562 cells. Other STATs showed a lower downregulation in their relative expressions at 48 hours at mRNA level for both of the cell lines. STAT proteins showed no expression change in K-562 cells in time course experiments but while STAT5A expression was downregulated; STAT5B showed an increase at 96 hours in HL-60 cells. Apoptosis was triggered by high-dose MP treatment that was evaluated by fluorescent microscopy.


CONCLUSIONS
The JAK/STAT pathway components may play an important role in the apoptosis mechanism of leukemic cells under MP treatment in HL-60 and K-562 cells. Other pathways may also be involved with a post-translational modification seen in the HL-60 cell line, with both upregulation and downregulation of protein expression levels of STAT5B and STAT5A, respectively.
Department of Medical Biology, Faculty of Medicine, Ege University, Izmir, Turkey. burcin.tezcanli@ege.edu.tr
Burçin Tezcanli
BT
Kaymaz
Nur
N
Selvi
Güray
G
Saydam
Fahri
F
Sahin
Buket
B
Kosova
D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D015153:Blotting, Western; D015870:Gene Expression; D005938:Glucocorticoids / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D020014:K562 Cells; D008775:Methylprednisolone / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
D005938:Glucocorticoids; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; C494092:STAT5A protein, human; C494095:STAT5B protein, human; D025521:Tumor Suppressor Proteins; D008775:Methylprednisolone