A comparative proteomic study identified LRPPRC and MCM7 as putative actors in imatinib mesylate cross-resistance in Lucena cell line

<p>Abstract</p> <p>Background</p> <p>Although chronic myeloid leukemia (CML) treatment has improved since the introduction of imatinib mesylate (IM), cases of resistance have been reported. This resistance has been associated with the emergence of multidrug resistance (MDR) phenotype, as a BCR-ABL independent mechanism. The classic pathway studied in MDR promotion is ATP-binding cassette (ABC) family transporters expression, but other mechanisms that drive drug resistance are largely unknown. To better understand IM therapy relapse due to the rise of MDR, we compared the proteomic profiles of K562 and Lucena (K562/VCR) cells.</p> <p>Results</p> <p>The use of 2-DE coupled with a MS approach resulted in the identification of 36 differentially expressed proteins. Differential mRNA levels of <it>leucine-rich PPR motif-containing (LRPPRC) protein, minichromosome maintenance complex component 7 (MCM7) </it>and <it>ATP-binding cassette sub-family B (MDR/TAP) member 1 (ABCB1) </it>were capable of defining samples from CML patients as responsive or resistant to therapy.</p> <p>Conclusions</p> <p>Through the data presented in this work, we show the relevance of MDR to IM therapy. In addition, our proteomic approach identified candidate actors involved in resistance, which could lead to additional information on BCR-ABL-independent molecular mechanisms.</p

Targeting hodgkin and reed–sternberg cells with an inhibitor of heat-shock protein 90: Molecular pathways of response and potential mechanisms of resistance

Classical Hodgkin lymphoma (cHL) cells overexpress heat-shock protein 90 (HSP90), an important intracellular signaling hub regulating cell survival, which is emerging as a promising therapeutic target. Here, we report the antitumor effect of celastrol, an anti-inflammatory compound and a recognized HSP90 inhibitor, in Hodgkin and Reed-Sternberg cell lines. Two disparate responses were recorded. In KM-H2 cells, celastrol inhibited cell proliferation, induced G0/G1 arrest, and triggered apoptosis through the activation of caspase-3/7. Conversely, L428 cells exhibited resistance to the compound. A proteomic screening identified a total of 262 differentially expressed proteins in sensitive KM-H2 cells and revealed that celastrol’s toxicity involved the suppression of the MAPK/ERK (extracellular signal regulated kinase/mitogen activated protein kinase) pathway. The apoptotic effects were preceded by a decrease in RAS (proto-oncogene protein Ras), p-ERK1/2 (phospho-extracellular signal-regulated Kinase-1/2), and c-Fos (proto-oncogene protein c-Fos) protein levels, as validated by immunoblot analysis. The L428 resistant cells exhibited a marked induction of HSP27 mRNA and protein after celastrol treatment. Our results provide the first evidence that celastrol has antitumor effects in cHL cells through the suppression of the MAPK/ERK pathway. Resistance to celastrol has rarely been described, and our results suggest that in cHL it may be mediated by the upregulation of HSP27. The antitumor properties of celastrol against cHL and whether the disparate responses observed in vitro have clinical correlates deserve further research.Fil: Segges, Priscilla. Instituto Nacional de Câncer; BrasilFil: Corrêa, Stephany. Instituto Nacional de Câncer; BrasilFil: Du Rocher, Bárbara. Fundación Oswaldo Cruz; Brasil. Instituto Nacional de Câncer; BrasilFil: Vera Lozada, Gabriela. Instituto Nacional de Câncer; BrasilFil: Krsticevic, Flavia Jorgelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; ArgentinaFil: Arce, Debora Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Sternberg, Cinthya. Universidade Federal do Rio de Janeiro; BrasilFil: Abdelhay, Eliana. Instituto Nacional de Câncer; BrasilFil: Hassan, Rocio. Instituto Nacional de Câncer; Brasi

Twist1 Influences the Expression of Leading Members of the IL-17 Signaling Pathway in HER2-Positive Breast Cancer Cells

Breast cancer (BC) is a heterogeneous disease composed of multiple subtypes with different molecular characteristics and clinical outcomes. The metastatic process in BC depends on the transcription factors (TFs) related to epithelial-mesenchymal transition (EMT), including the master regulator Twist1. However, its role beyond EMT in BC subtypes remains unclear. Our study aimed to investigate the role of Twist1, beyond EMT, in the molecular subtypes of BC. In patients, we observed the overexpression of TWIST1 in the HER2+ group. The silencing of TWIST1 in HER2+ BC cells resulted in the upregulation of 138 genes and the downregulation of 174 genes compared to control cells in a microarray assay. In silico analysis revealed correlations between Twist1 and important biological processes such as the Th17-mediated immune response, suggesting that Twist1 could be relevant for IL-17 signaling in HER2+ BC. IL-17 signaling was then examined, and it was shown that TWIST1 knockdown caused the downregulation of leading members of IL-17 signaling pathway. Taken together, our findings suggest that Twist1 plays a role on IL-17 signaling in HER2+ BC

Wnt/β-catenin pathway regulates <it>ABCB1</it> transcription in chronic myeloid leukemia

<p>Abstract</p> <p>Background</p> <p>The advanced phases of chronic myeloid leukemia (CML) are known to be more resistant to therapy. This resistance has been associated with the overexpression of <it>ABCB1</it>, which gives rise to the multidrug resistance (MDR) phenomenon. MDR is characterized by resistance to nonrelated drugs, and P-glycoprotein (encoded by <it>ABCB1</it>) has been implicated as the major cause of its emergence. Wnt signaling has been demonstrated to be important in several aspects of CML. Recently, Wnt signaling was linked to <it>ABCB1</it> regulation through its canonical pathway, which is mediated by β-catenin, in other types of cancer. In this study, we investigated the involvement of the Wnt/β-catenin pathway in the regulation of <it>ABCB1</it> transcription in CML, as the basal promoter of <it>ABCB1</it> has several β-catenin binding sites. β-catenin is the mediator of canonical Wnt signaling, which is important for CML progression.</p> <p>Methods</p> <p>In this work we used the K562 cell line and its derived MDR-resistant cell line Lucena (K562/VCR) as CML study models. Real time PCR (RT-qPCR), electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), flow cytometry (FACS), western blot, immunofluorescence, RNA knockdown (siRNA) and Luciferase reporter approaches were used.</p> <p>Results</p> <p>β-catenin was present in the protein complex on the basal promoter of <it>ABCB1</it> in both cell lines <it>in vitro</it>, but its binding was more pronounced in the resistant cell line <it>in vivo</it>. Lucena cells also exhibited higher β-catenin levels compared to its parental cell line. <it>Wnt1</it> and <it>β-catenin</it> depletion and overexpression of nuclear β-catenin, together with TCF binding sites activation demonstrated that <it>ABCB1</it> is positively regulated by the canonical pathway of Wnt signaling.</p> <p>Conclusions</p> <p>These results suggest, for the first time, that the Wnt/β-catenin pathway regulates <it>ABCB1</it> in CML.</p