CELLULAR CHANGES ASSOCIATED WITH R-CRT PRO-APOPTOTIC ACTION INDUCED BY BORTEZOMIB IN GLIOMA CELLS

ANDREA COMBA; LAURA V. BONNET; VICTOR E. GOITEA; MAURICIO R. GALIANO; MARTA E. HALLAK

Córdoba

Congreso; 52th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2016

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

A variable efficiency has been reported for the Bortezomib treatment (BT) of different types of cancer. After BT of different human glioma cells, we determined that MO59K cells are resistant to this drug showing increased stress granules (SGs) formation, a phenotype related with drug resistance. These cells showed a modest increase of arginylated calreticulin (R-CRT) that appears confined to SGs. Conversely, the highest susceptibility to BT was shown by HOG cells, which after BT significantly increased R-CRT levels, a modified protein that get enriched at the plasma membrane where it participates of pro-apoptotic signaling. To understand these differences, other parameters were analyzed after BT. Firstly, by Fluo3-AM fluorescence activation, we determined that HOG cells exposed to BT showed a robust mobilization of intracellular calcium that is not shown by MO59K cells. Secondly, by Western blot of different ER stress markers we observed that HOG cells exhibit a stronger ER stress activation than MO59K cells after BT. Moreover, we determined that the susceptibility of MO59K to BT get increased when a cytosolic R-CRT-GFP chimera was overexpressed in these cells. Thus, an efficient BT involve: induction of ER stress associated to intracellular calcium mobilization, concomitantly with increased re-localization of R-CRT at the cell membrane, which induce caspase-3 dependent cell death.