Mediation of multiple pathways regulating cell proliferation, migration, and apoptosis in the human malignant glioma cell line U87MG via unphosphorylated STAT1

Abstract

Signal transducer and activator of transcription 1 (STAT1) is thought to be a tumor suppressor protein. The authors investigated the expression and role of STAT1 in glioblastoma. Immunohistochemistry was used to detect the expression of STAT1 in glioblastoma and normal brain tissues. Reverse transcription-polymerase chain reaction and Western blot analysis were used to detect mRNA and protein expression levels of STAT1. Cell growth, proliferation, migration, apoptosis, and the expression of related genes and proteins (Bcl-2, Bax, cleaved caspase-3, caspase-9, p21, and proliferating cell nuclear antigen) were examined in vitro via cell counting kit-8, wound-healing, flow cytometry, Rhodamine B, TUNEL, and Western blot assays. Human glioblastoma had decreased expression of STAT1 proteins. Transfection of the U87MG cells with STAT1 plasmid in vitro demonstrated significant inhibition of cell growth and an increase in apoptotic cell death compared with cells transfected with vector or mock plasmids. These effects were associated with the upregulation of cleaved caspase-3, Bax, and p21 and the downregulation of Bcl-2 expression. The results of this study suggest that increased expression of STAT1 by transfection with STAT1 plasmid synergistically inhibits human U87MG glioblastoma cell growth in vitro.