title: Suppression of the Eag1 potassium channel sensitizes glioblastoma cells to injury caused by temozolomide.
abstract: Glioblastoma multiforme (GBM) is the most aggressive type of human primary brain tumor. The standard treatment protocol includes radiotherapy in combination with temozolomide (TMZ). Despite advances in GBM treatment, the survival time of patients diagnosed with glioma is 14.5 months. Regarding tumor biology, various types of cancer cell overexpress the ether à go-go 1 (Eag1) potassium channel. Therefore, the present study examined the role of Eag1 in the cell damage caused by TMZ on the U87MG glioblastoma cell line. Eag1 was inhibited using a channel blocker (astemizole) or silenced by a short-hairpin RNA expression vector (pKv10.1-3). pKv10.1-3 (0.2 µg) improved the Eag1 silencing caused by 250 µM TMZ, as determined by reverse transcription-quantitative polymerase chain reaction and immunocytochemistry. Additionally, inhibiting Eag1 with the vector or astemizole (5 µM) reduced glioblastoma cell viability and sensitized cells to TMZ. Cell viability decreased by 63% for pKv10.1-3 + TMZ compared with 34% for TMZ alone, and by 77% for astemizole + TMZ compared with 46% for TMZ alone, as determined by MTT assay. In addition, both the vector and astemizole increased the apoptosis rate of glioblastoma cells triggered by TMZ, as determined by an Annexin V apoptosis assay. Collectively, the current data reveal that Eag1 has a role in the damage caused to glioblastoma by TMZ. Furthermore, suppression of this channel can improve the action of TMZ on U87MG glioblastoma cells. Thus, silencing Eag1 is a promising strategy to improve GBM treatment and merits additional studies in animal models of glioma.
authors.affiliation: Technology for Gene Therapy Laboratory, Central Institute of Sciences, Faculty of Agronomy and Veterinary Medicine, University of Brasília, Brasília DF 70910-900, Brazil.
authors.forename: Thais Torquato
authors.initials: TT
authors.lastname: Sales
authors.affiliation: Technology for Gene Therapy Laboratory, Central Institute of Sciences, Faculty of Agronomy and Veterinary Medicine, University of Brasília, Brasília DF 70910-900, Brazil.
authors.forename: Fernando Francisco Borges
authors.initials: FF
authors.lastname: Resende
authors.affiliation: Department of Cellular Biology, Institute of Biological Sciences, University of Brasília, Brasília DF 70910-900, Brazil.
authors.forename: Natália Lemos
authors.initials: NL
authors.lastname: Chaves
authors.affiliation: Technology for Gene Therapy Laboratory, Central Institute of Sciences, Faculty of Agronomy and Veterinary Medicine, University of Brasília, Brasília DF 70910-900, Brazil.
authors.forename: Simoneide Souza
authors.initials: SS
authors.lastname: Titze-De-Almeida
authors.affiliation: Department of Cellular Biology, Institute of Biological Sciences, University of Brasília, Brasília DF 70910-900, Brazil.
authors.forename: Sônia Nair
authors.initials: SN
authors.lastname: Báo
authors.affiliation: Department of Cellular Biology, Institute of Biological Sciences, University of Brasília, Brasília DF 70910-900, Brazil; Planaltina Campus, University of Brasília, Brasília DF 70910-900, Brazil.
authors.forename: Marcella Lemos
authors.initials: ML
authors.lastname: Brettas
authors.affiliation: Technology for Gene Therapy Laboratory, Central Institute of Sciences, Faculty of Agronomy and Veterinary Medicine, University of Brasília, Brasília DF 70910-900, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Titze-De-Almeida
keywords: Kv10.1; RNA interference; U87MG glioblastoma multiforme cell line; astemizole; ether à go-go 1; gene therapy; short hairpin RNA; temozolomide