Am J Blood Res 2013;3(1):58-70
Original Article
Suppression of STAT5A and STAT5B chronic myeloid leukemia cells via
siRNA and antisense-oligonucleotide applications with the induc-tion of
apoptosis
Burçin Tezcanlı Kaymaz, Nur Selvi, Aysun Adan Gokbulut, Çağdaş Aktan, Cumhur Gündüz, Güray
Saydam, Fahri Şahin, Vildan Bozok Çetintaş, Yusuf Baran, Buket Kosova
Ege University, Faculty of Medicine, Department of Medical Biology, Bornova, İzmir, Turkey; İzmir Institute of Technology,
Department of Molecular Biology and Genetics, Urla, İzmir, Turkey; Ege University, Faculty of Medicine, Department of
Hematology, Bornova, İzmir, Turkey
Received November 24, 2012; Accepted December 23, 2012; Epub January 17, 2013; Published January 25, 2013
Abstract: Signal transducers and activators of transcription (STAT) proteins function in the JAK/STAT signaling pathway and
are activated by phosphorylation. As a result of this signaling event, they affect many cellular processes including cell growth,
proliferation, differentiation, and survival. Increases in the expressions of STAT5A and STAT5B play a remarkable role in the
development of leukemia in which leukemic cells gain uncontrolled proliferation and angiogenesis ability. At the same time,
these cells acquire ability to escape from apoptosis and host immune system. In this study, we aimed to suppress STAT-5A
and -5B genes in K562 CML cells by siRNA transfection and antisense oligonucleotides (ODN) targeting and then to evaluate
apoptosis rate. Finally, we compared the transfection efficiencies of these approaches. Quantitative RT-PCR and Western blot
results indicated that STAT expressions were downregulated at both mRNA and protein levels following siRNA transfection.
However, electroporation mediated ODN transfection could only provide limited suppression rates at mRNA and protein
levels. Moreover, it was displayed that apoptosis were significantly induced in siRNA treated leukemic cells as compared to
ODN treated cells. As a conclusion, siRNA applications were found to be more effective in terms of gene silencing when
compared to ODN treatment based on the higher apoptosis and mRNA suppression rates. siRNA application could be a new
and alternative curative method as a supporting therapy in CML patients. (AJBR1211002).
Keywords: Chronic myeloid leukemia, K562, STAT5, siRNA knockdown, antisense oligonucleotides, apoptosis
Address all correspondence to:
Dr. Buket Kosova
Ege University, Department of Medical Biology
Bornova, İzmir, Turkey.
Phone: + 90 232 3902260
E-mail: buket.kosova@ege.edu.tr
Original Article
Suppression of STAT5A and STAT5B chronic myeloid leukemia cells via
siRNA and antisense-oligonucleotide applications with the induc-tion of
apoptosis
Burçin Tezcanlı Kaymaz, Nur Selvi, Aysun Adan Gokbulut, Çağdaş Aktan, Cumhur Gündüz, Güray
Saydam, Fahri Şahin, Vildan Bozok Çetintaş, Yusuf Baran, Buket Kosova
Ege University, Faculty of Medicine, Department of Medical Biology, Bornova, İzmir, Turkey; İzmir Institute of Technology,
Department of Molecular Biology and Genetics, Urla, İzmir, Turkey; Ege University, Faculty of Medicine, Department of
Hematology, Bornova, İzmir, Turkey
Received November 24, 2012; Accepted December 23, 2012; Epub January 17, 2013; Published January 25, 2013
Abstract: Signal transducers and activators of transcription (STAT) proteins function in the JAK/STAT signaling pathway and
are activated by phosphorylation. As a result of this signaling event, they affect many cellular processes including cell growth,
proliferation, differentiation, and survival. Increases in the expressions of STAT5A and STAT5B play a remarkable role in the
development of leukemia in which leukemic cells gain uncontrolled proliferation and angiogenesis ability. At the same time,
these cells acquire ability to escape from apoptosis and host immune system. In this study, we aimed to suppress STAT-5A
and -5B genes in K562 CML cells by siRNA transfection and antisense oligonucleotides (ODN) targeting and then to evaluate
apoptosis rate. Finally, we compared the transfection efficiencies of these approaches. Quantitative RT-PCR and Western blot
results indicated that STAT expressions were downregulated at both mRNA and protein levels following siRNA transfection.
However, electroporation mediated ODN transfection could only provide limited suppression rates at mRNA and protein
levels. Moreover, it was displayed that apoptosis were significantly induced in siRNA treated leukemic cells as compared to
ODN treated cells. As a conclusion, siRNA applications were found to be more effective in terms of gene silencing when
compared to ODN treatment based on the higher apoptosis and mRNA suppression rates. siRNA application could be a new
and alternative curative method as a supporting therapy in CML patients. (AJBR1211002).
Keywords: Chronic myeloid leukemia, K562, STAT5, siRNA knockdown, antisense oligonucleotides, apoptosis
Address all correspondence to:
Dr. Buket Kosova
Ege University, Department of Medical Biology
Bornova, İzmir, Turkey.
Phone: + 90 232 3902260
E-mail: buket.kosova@ege.edu.tr
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