ID helix-loop-helix proteins as determinants of cell survival in B-cell chronic lymphocytic leukemia cells in vitro

Abstract

BackgroundMembers of the inhibitor of DNA-binding (ID) family of helix-loop-helix proteins have been causally implicated in the pathogenesis of several types of B-cell lineage malignancy, either on the basis of mutation or by altered expression. B-cell chronic lymphocytic leukemia encompasses a heterogeneous group of disorders and is the commonest leukaemia type in the Western world. In this study, we have investigated the pathobiological functions of the ID2 and ID3 proteins in this disease with an emphasis on their role in regulating leukemic cell death/survival.MethodsBioinformatics analysis of microarray gene expression data was used to investigate expression of ID2/ID3 in leukemic versus normal B cells, their association with clinical course of disease and molecular sub-type and to reconstruct a gene regulatory network using the ‘maximum information coefficient’ (MIC) for target gene inference. In vitro cultured primary leukemia cells, either in isolation or co-cultured with accessory vascular endothelial cells, were used to investigate ID2/ID3 protein expression by western blotting and to assess the cytotoxic response of different drugs (fludarabine, chlorambucil, ethacrynic acid) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. ID2/ID3 protein levels in primary leukemia cells and in MEC1 cells were manipulated by transduction with siRNA reagents.ResultsDatamining showed that the expression profiles of ID2 and ID3 are associated with distinct pathobiological features of disease and implicated both genes in regulating cell death/survival by targeting multiple non-overlapping sets of apoptosis effecter genes. Consistent with microarray data, the overall pattern of ID2/ID3 protein expression in relation to cell death/survival responses of primary leukemia cells was suggestive of a pro-survival function for both ID proteins. This was confirmed by siRNA knock-down experiments in MEC1 cells and in primary leukemia cells, but with variability in the dependence of leukemic cells from different patients on ID protein expression for cell survival. Vascular endothelial cells rescued leukemia cells from spontaneous and cytotoxic drug-induced cell death at least in part, via an ID protein-coupled redox-dependent mechanism.ConclusionsOur study provides evidence for a pro-survival function of the ID2/ID3 proteins in chronic lymphocytic leukemia cells and also highlights these proteins as potential determinants of the pathobiology of this disorder.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-014-0286-9) contains supplementary material, which is available to authorized users.

Identification of deubiquitinase targets of isothiocyanates using SILAC-assisted quantitative mass spectrometry

“…USP1 also deubiquitinates and stabilizes the transcriptional regulators ID1, ID2 and ID3 [ 40 – 42 ]. Thus the inhibition of USP1 can explain several PEITC activities: inhibition of DNA repair, sensitization to cisplatin and decrease in ID protein levels (Table 1 ) [ 13 , 15 , 24 ]. Therefore, we characterized the effects of PEITC on USP1 in more detail.…”

“…Our SILAC experiments also provide possible explanations for other previously described PEITC activities and suggest new PEITC activities. The PEITC-induced decrease in ID2 and ID3 can be attributed to the inhibition/knockdown of USP1 [ 24 , 40 ]. ID proteins are transcriptional regulators required for the maintenance of cancer stem cells.…”

“…PEITC also modulates proteostasis, the inflammatory response, angiogenesis, apoptosis, cell cycle progression, proliferation and autophagy [ 6 ]. PEITC reduces the levels of critical proteins in diverse cellular pathways, including MCL1, Bcr-Abl, inhibitor of DNA binding proteins 2 and 3 (ID2 and 3) as well as apoptosis proteins such as X-IAP, cIAPs and survivin [ 2 , 6 , 9 , 20 – 24 ].…”

Cancer Specific Long Noncoding RNAs Show Differential Expression Patterns and Competing Endogenous RNA Potential in Hepatocellular Carcinoma

“…In general gene co-expression network analysis, Pearson’s correlation is a measure for linear regression, but it is very sensitive to outliers. MIC and MINE are able to examine and characterize all potentially interesting relationships in a complex data set [ 33 ].…”

The vibration of nanosprings affected by van der Waals interactions

“…helical carbon nanotubes (CNTs), silicon nanowires, helical graphene ribbons, etc.) [1][2][3] and various protein molecules [4,5]. Owing to their unique helical structures, such structures exhibit some special electronic [6,7], mechanical [8,9] or magnetic properties [10,11] and possess significant potential to make resonators, nanosprings, electromagnetic wave absorbers, etc.…”