TY - JOUR
T1 - Metformin plus sorafenib highly impacts temozolomide-resistant glioblastoma stem-like cells
AU - Aldea, Mihaela D.
AU - Petrushev, Bobe
AU - Soritau, Olga
AU - Tomuleasa, Ciprian I.
AU - Berindan-Neagoe, Ioana
AU - Filip, Adriana G.
AU - Chereches, Gabriela
AU - Cenariu, Mihai
AU - Craciun, Lucian
AU - Tatomir, Corina
AU - Florian, Ioan Stefan
AU - Crivii, Carmen B.
AU - Kacso, Gabriel
PY - 2014/1/1
Y1 - 2014/1/1
N2 - Purpose; Glioblastoma stem cells (GSCs), responsible for the dismal disease prognosis after conventional treatments, are driven by overactive signaling pathways, such as PI3K/ AKT/mTOR and RAS/RAF/MAPK. The objective of our study was to target in vitro-GSCs by combining metformin (Met) as a mTOR inhibitor, with sorafenib (Soraf) as a RAF inhibitor. Methods: GSCs cultured under basal conditions were treated with Met, temozolomide (TMZ), Soraf, Met+TMZ and Met+Soraf, as untreated arm served as control. At 4 hrs of drug exposure, we measured the level of reactive oxygen species (ROS) by 2',7'-dichlorofluorescein diacetate (DCFDA) assay, apoptosis by prodium iodide (PI)-V Annexin staining and efflux pump activity by using the fluorescent dye rhodamine 123. At 24 hrs, we measured cell proliferation by 3-(4,5-dimethylthiazolyl-2)-2,5- diphenyltetrazolium bromide (MTT) assay, apoptosis and malondialdehyde (MDA) levels. MTT results were compared with corresponding measurements on cultures of non-stem glioblastoma ells and osteoblasts. Results: Met+Soraf exerted the highest antiproliferative effects in GSCs and non-stem glioblasto)na cells (p<0.001). Both Met and Soraf monotherapy exhibited a selective cytotoxic effect on GSCs (p<0.001), while no effect was detected on non-stem glioblastoma cells (p>0.05). Soraf, but not Met, impacted the proliferation of normal cells. Soraf displayed synergism with Met in producing high levels of ROS, decreasing efflux pump activity and generating the highest apoptotic rates when compared to either drug alone (p<0.001). Conclusion: GSCs were highly sensitive to the combination of Met and Soraf which reduced cell proliferation, increased oxidative stress, inhibited efflux pump activity and ultimately killed GSCs. We strongly believe that these results warrant further in vivo exploration.
AB - Purpose; Glioblastoma stem cells (GSCs), responsible for the dismal disease prognosis after conventional treatments, are driven by overactive signaling pathways, such as PI3K/ AKT/mTOR and RAS/RAF/MAPK. The objective of our study was to target in vitro-GSCs by combining metformin (Met) as a mTOR inhibitor, with sorafenib (Soraf) as a RAF inhibitor. Methods: GSCs cultured under basal conditions were treated with Met, temozolomide (TMZ), Soraf, Met+TMZ and Met+Soraf, as untreated arm served as control. At 4 hrs of drug exposure, we measured the level of reactive oxygen species (ROS) by 2',7'-dichlorofluorescein diacetate (DCFDA) assay, apoptosis by prodium iodide (PI)-V Annexin staining and efflux pump activity by using the fluorescent dye rhodamine 123. At 24 hrs, we measured cell proliferation by 3-(4,5-dimethylthiazolyl-2)-2,5- diphenyltetrazolium bromide (MTT) assay, apoptosis and malondialdehyde (MDA) levels. MTT results were compared with corresponding measurements on cultures of non-stem glioblastoma ells and osteoblasts. Results: Met+Soraf exerted the highest antiproliferative effects in GSCs and non-stem glioblasto)na cells (p<0.001). Both Met and Soraf monotherapy exhibited a selective cytotoxic effect on GSCs (p<0.001), while no effect was detected on non-stem glioblastoma cells (p>0.05). Soraf, but not Met, impacted the proliferation of normal cells. Soraf displayed synergism with Met in producing high levels of ROS, decreasing efflux pump activity and generating the highest apoptotic rates when compared to either drug alone (p<0.001). Conclusion: GSCs were highly sensitive to the combination of Met and Soraf which reduced cell proliferation, increased oxidative stress, inhibited efflux pump activity and ultimately killed GSCs. We strongly believe that these results warrant further in vivo exploration.
KW - Glioblastoma
KW - Metformin
KW - Sorafenib
KW - Stem-like cells
KW - Temozolomide
UR - http://www.scopus.com/inward/record.url?scp=84904200125&partnerID=8YFLogxK
M3 - Article
C2 - 24965413
AN - SCOPUS:84904200125
SN - 1107-0625
VL - 19
SP - 502
EP - 511
JO - Journal of B.U.ON.
JF - Journal of B.U.ON.
IS - 2
ER -