Evaluation of DSB repair by NHEJ in PIMREG-deficient reporter cells

Abstract

PIMREG (PICALM interacting mitotic regulator) is a nuclear protein enriched in the nucleolus and expressed mostly in lymph organs such as thymus and spleen. PIMREG is a proliferation marker and its expression varies according to the phase of the cell cycle. Furthermore, PIMREG is overexpressed in different types of cancer, especially in glioblastoma (GBM) and its high expression is related to tumor progression and worse patient outcome. The standard treatment for GBM is surgical resection of the tumor, followed by chemotherapy with temozolomide (TMZ), however, the resistance to treatment is often observed. Recent data from our group showed the participation of PIMREG in DNA damage signaling GBM cell lines. The expression of PIMREG increased in dose-dependent manner in GBM cells treated with TMZ and this increase was accompanied by the increased phosphorylation of the histone H2AX (gH2AX) on serine 139, a marker for DNA damage. In addition, the knockdown of PIMREG increased the sensitivity of cells to treatment and impaired the phosphorylation and activation of ATM after treatment with TMZ. Thus, this project aims to investigate if PIMREG participates of DNA repair through NHEJ pathway. This goal will be achieved by inducing double strand breaks (DSB) in the DNA of reporter cells for NHEJ repair pathway in absence (knockout) or overexpression of PIMREG. If we observe an impairment of NHEJ pathway, a phenotype in PIMREG knockout cells, we will perform rescue experiments through the expression of heterologous PIMREG in these cell lines.