Repression of STAT3, STAT5A, and STAT5B expressions in chronic myelogenous leukemia cell line K–562 with unmodified or chemically modified siRNAs and induction of apoptosis

Abstract

Signal transducers and activators of transcription (STAT) proteins are latent cytoplasmic transcription factors that affect several cellular processes including cell growth, proliferation, differentiation, and survival. Following phosphorylation, STATs are activated, and their upregulated expressions increase in malignancies with playing a role in the development of leukemia. In this study, transfection of K-562 cells with either unmodified or chemically modified anti-STAT3, -STAT5A, -STAT5B siRNAs for duration of 12 days, determining gene silencing at mRNA and protein levels, evaluating apoptosis rate, and detecting JAK/STAT pathway members' gene expression profiles via array method were aimed. Quantitative RT-PCR and Western blot assays indicated that STAT expressions were downregulated both at mRNA and protein levels, and TUNEL assay showed that leukemic cell apoptosis was induced due to inhibition of STATs. Array analysis resulted with decreases in signal transducer, phosphorylation inducer, and oncogene expressions, whereas increased expressions in STAT inhibitor and apoptosis inducer genes were observed. These results point out that siRNA application could constitute a new and alternative curative method for supporting therapy of CML-diagnosed patients in the future.

Revealing genome-wide mRNA and microRNA expression patterns in leukemic cells highlighted “hsa-miR-2278” as a tumor suppressor for regain of chemotherapeutic imatinib response due to targeting STAT5A

“…Besides STAT5A, also STAT3 has significant roles in hematological malignancies as we and others also have reported before [22,23]. Similar to our inferences about the significance of JAK/STAT pathway members-especially STAT family, Rozovski U et al reported that STAT3 regulated microRNA gene expression in chronic lymphocytic leukemia cells and presence of activated STAT3 had a profound effect on miRNA expression in CLL cells [24].…”

STAT inhibitors for cancer therapy

“…However, data regarding siRNA targeted silencing of STAT genes for cancer therapy are limited to in vitro studies and in vivo studies of animal models only [72-81]. …”

Determination of the Gene Expression Profiles of JAK/STAT Cascade Components for the Potential Role of Capsaicin Induced Apoptosis of Acute T-Cell Lymphoblastic Leukemia Cells

“…Kapsaisinin CCRF-CEM hücreleri için belirlenmiş IC 50 dozu olan 80 μM ile deney setleri oluşturuldu 16 . İnkübasyonundan 72 saat sonra apoptoz analizi ve mRNA seviyesindeki gen ekspresyon analizi için sırasıyla 5x10 6 ve 1x10 6 hücre toplandı.…”

“…Sonuçlarımıza benzer olarak Zhang ve arkadaş-ları da 3 adet T hücreli lösemi hücre dizisine kapsaisin verdikten sonra, lösemi hücrelerinin proliferasyonunun inhibe edildiğini, apoptozun indüklendiğini rapor etmişlerdir. Ayrıca, 100 ve 200 μM kapsaisin 24 saat süreyle uygulandığında, CTL-1 hücre dizisinde sırasıyla %5,4 ve % 32,2 oranlarında apoptoz artışı saptanmışken, ATL-T hücrelerinde aynı dozlar için sırasıyla %8,8 ve %19,8 oranlarında artmış apoptoz gözlenmiştir 16 . Ito ve arkadaşlarının insan akut myeloid lösemi hücre dizileri NB4 ve Kasumi-1'e kapsaisin verdikleri çalışmalarında, G 0 /G 1 fazında hücre döngüsünü durdurması ve apoptozu indüklemesi suretiyle lösemi hücrelerinin proliferasyonu baskılanır-ken; normal kemik iliği mononükleer hücrelerin etkilenmediği görülmüştür 18 .…”