Gene expression profiling in MOLT-4 cells during gamma-radiation-induced apoptosis

Abstract

This study aims to identify the temporal changes in gene expression in MOLT-4, a leukemia cell line, in response to radiation and to present a comprehensive description of the pathways and processes that most significantly relate to the cellular biological responses. A global gene expression profile of 24,500 genes was performed on MOLT-4 tumor cells following exposure to 5 Gy of ionizing radiation ((60)Co) using a bead chip array (Illumina). Signaling pathways and processes significantly altered following irradiation were explored using MetaCore. Cellular viability [3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide], activation of cell cycle checkpoints [fluorescence activated cell sorting (FACS)], and induction of apoptosis (FACS, caspase assays) were evaluated to correlate these biological responses to the gene expression changes. Totally, 698 different genes displayed a significantly altered expression following radiation, and out of these transcripts, all but one showed increased expression. One hour following irradiation, the expression was changed only for a few genes. Striking changes appeared at later time-points. From 3 to 24 h post-irradiation, a significant fraction of the genes with altered expression were found to be involved in cell cycle checkpoints and their regulation (CDKN1A), DNA repair (GADD45A, DDB2, XPC), apoptosis induction (DR5, FasR, Apo-2L, Bax), and T-cell activation/proliferation (CD70, OX40L). Irradiated MOLT-4 cells were arrested at the G2-checkpoint, followed by a decrease in cell viability, most pronounced 48 h after exposure. The cell death was executed by induced apoptosis and was visualized by an increase in subG1 cells and an increased activation of initiator (caspase-8 and caspase-9) and execution (caspase-3) caspases. Activation of cell cycle arrest and apoptosis correlated well in time with the changes in gene expression of those genes important for these biological processes. Activation of the apoptotic signaling pathways in MOLT-4 cells following irradiation includes components from the intrinsic as well as the extrinsic apoptotic pathways. This study indicates that the altered gene expression pattern induced by irradiation is important for the sequential steps observed in MOLT-4 cells during apoptosis induction.

Pingyangmycin stimulates apoptosis in human hemangioma-derived endothelial cells through activation of the p53 pathway

“…The TEM examination in the present study revealed typical apoptotic characteristics in the pingyangmycin-treated HemECs, including shrinkage of the cytoplasm, chromatin condensation and formation of apoptotic bodies. Gene expression profiling studies have indicated that apoptotic morphological changes are a consequence of the coordinated regulation of a large number of genes (22). Consistent with this view, the present study demonstrated that pingyangmycin treatment upregulated 2,544 genes and downregulated 2,208 genes in the HemECs.…”

X-ray-Induced Changes in the Expression of Inflammation-Related Genes in Human Peripheral Blood

“…In the present work, we used qPCR array to screen out 62 genes with significant differential expression (|fold regulation| > 2) associated with inflammatory reaction after X-ray irradiation. Including BCL2L1 , CARD6 , CASP1 , CASP5 , CCL2 , CCL7 , CD40LG , CXCL1 , CXCL2 , FADD , HSP90AA1 , HSP90B1 , IFNB1 , IFNG , IKBKG , IL12A , IL12B , IL18 , IL1B , IL6 , IRAK1 , IRF1 , MAP3K7 , MAPK12 , MAPK3 , MYD88 , NFKBIA , NLRP12 , NLRP3 , PTGS2 , SUGT1 , TNF , TNFSF11 , TNFSF14 , and TNFSF4 , 35 were associated with ionizing radiation response, as previously reported in different types of cells, tissues, and organisms [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]. Among these genes, 27 (including AIM2 , CARD18 , CIITA , IL33 , IRF2 , MAPK11 , MAPK13 , MAPK9 , MEFV , NFKBIB , NLRC4 , NLRC5 , NLRP1 , NLRP4 , NLRP5 , NLRP6 , NLRX1 , NOD2 , P2RX7 , PANX1 , PEA15 , PSTPIP1 , PYDC1 , MOK , RIPK2 , TIRAP , and TXNIP ) have not previously been shown to be responsive to ionizing radiation damage at the mRNA level (|fold regulation| > 2).…”

CD70: An emerging target in cancer immunotherapy

“…Furthermore, in literature it has been described that upon irradiation, a large pool of intracellular CD70 becomes exposed onto the surface of leukemia and lymphoma cells (Hintzen et al, 1994;Lindgren et al, 2012). It is an interesting hypothesis that irradiation could increase the levels of CD70 in tumors cells.…”