ARGINYLATED CALRETICULIN MODULATES THE SENSITIVITY OF HUMAN GLIOMA-DERIVED CANCER CELLS TO BORTEZOMIB TREATMENT

ANDREA COMBA; VICTOR E. GOITEA; MAURICIO R. GALIANO

Rio de Janeiro

Congreso; 9th IBRO World Congress of Neuroscience; 2015

IBRO International Brain Research Organization

Gliomas are the most frequent type of primary brain tumors in adults. Despite advances in knowledge of brain tumor biology, the treatment of malignant gliomas remains a challenge in neuro-oncology. Calreticulin (CRT), a protein posttranslational arginylated (R-CRT) in different tissues including the brain, has been described in different subcellular localizations such as plasma membrane, cytosol and stress granules (SGs) with different functions. Besides, apoptosis resistance of cancer cells treated with therapeutic drugs as Bortezomib has been associated with SGs formation. Therefore, R-CRT has emerged as a candidate regulatory protein of cell survival probably depending on their subcellular location and/or interaction with other components such as SGs. To determine the role of R-CRT in apoptosis susceptibility of human glioma cancer cells, MO59K and HOG cell lines were treated with Bortezomib for 24 hrs. After treatment, cells viability was determined by colorimetric Resazurin assay, apoptosis by flow cytometry (Anexin V-PE and 7-AAD) and SGs formation and R-CRT localization and content by confocal microscopy and flow cytometry respectively. We observed that HOG cells showed a decrease of cell viability and an increase of apoptosis in a dose dependent manner but MO59K were more resistant to treatment. These results correlated with an increase of SGs formation in MO59K cells and a reduced SGs formation in HOG cells. In addition, Bortezomib treatment also induces R-CRT up-regulated expression levels in HOG cells but no in MO59K cells. Moreover, HOG cells has an increased content of R-CRT in the cell surface after treatment, whereas it was reduced in MO59K cells. Additionally, confocal analysis shows that R-CRT has an increased cytosolic association to SGs plus nuclear localization in MO59 cells compared with HOG cells after treatment. Taken together, these results show that R-CRT up-regulation and subcellular localization are involved in chemotherapeutic cell survival response of human glioma cancer cell lines. Further understanding of the pathways involved in R-CRT cellular alterations would contribute to improve therapeutic strategies of brain cancer.