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Expression data from MSCs of healthy donors vs. CML patients

ABSTRACT: The management of patients with chronic myeloid leukemia (CML) has been revolutionized by the introduction of tyrosine kinase inhibitors (TKIs), which induce deep molecular responses so that treatment can eventually be discontinued, leading to treatment-free remission (TFR) in a subset of patients. Unfortunately, leukemic stem cells (LSCs) often persist and a fraction of these can again expand in about half of patients that attempt TKI discontinuation. In this study, we show that presence of myelofibrosis (MF) at the time of diagnosis is a factor that strongly associates with TFR failure. Fibrotic transformation is governed by the action of several cytokines, and interestingly, some of them have also been described to support LSC persistence. At the cellular level, these could be produced by both malignant cells and by components of the bone marrow (BM) niche, including megakaryocytes (MKs) and mesenchymal stromal cells (MSCs). In our cohort of 57 patients, around 40% presented with MF at diagnosis and the number of blasts in the peripheral blood and BM was significantly elevated in patients with higher grade of MF. Employing a CML transgenic mouse model, we could observe higher levels of alpha-smooth muscle actin (α-SMA) in the BM when compared to control mice. Short-term treatment with the TKI nilotinib, efficiently reduced spleen weight and BCR-ABL1 mRNA levels, while α-SMA expression was only partially reduced. Interestingly, the number of MKs was increased in the spleen of CML mice and elevated in both BM and spleen upon nilotinib treatment. Microarray analysis of human CML- vs healthy donor (HD)-derived MSCs showed an altered expression of gene signatures reflecting fibrosis as well as hematopoietic support, thus suggesting MSCs as a potential player in these two processes. Finally, in our cohort, 12 patients qualified for TKI discontinuation, and here we observed that all patients who failed TFR had BM fibrosis at diagnosis, further linking fibrosis to LSC persistence. Although we have not investigated whether MF is directly responsible for LSC persistence or whether it is merely an epiphenomenon occurring alongside the development of an LSC-supportive niche, we strongly believe that this is a mechanism that merits further investigation We used microarrays to compare MSCs expression profiles of HD vs. CML patients.

ORGANISM(S): Homo sapiens

PROVIDER: GSE230534 | GEO | 2023/06/23

REPOSITORIES: GEO

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Project description:Tyrosine kinase inhibitors (TKI) are highly effective in treatment of chronic myeloid leukemia (CML) but do not eliminate leukemia stem cells (LSC), which remain a potential source of relapse. TKI treatment effectively inhibits BCR-ABL kinase activity in CML LSC, suggesting that additional kinase-independent mechanisms contribute to LSC preservation. We investigated whether signals from the bone marrow (BM) microenvironment protect CML LSC from TKI treatment. Coculture with human BM mesenchymal stromal cells (MSC) significantly inhibited apoptosis and preserved CML stem/progenitor cells following TKI exposure, maintaining colony forming ability and engraftment potential in immunodeficient mice. We found that the N-Cadherin receptor plays an important role in MSC-mediated protection of CML progenitors from TKI. N-Cadherin-mediated adhesion to MSC was associated with increased cytoplasmic N-Cadherin-M-NM-2-catenin complex formation, as well as enhanced M-NM-2-catenin nuclear translocation and transcriptional activity. Increased exogenous Wnt-mediated M-NM-2-catenin signaling played an important role in MSC-mediated protection of CML progenitors from TKI treatment. Our results reveal a close interplay between N-Cadherin and the Wnt-M-NM-2-catenin pathway in protecting CML LSC during TKI treatment. Importantly, these results reveal novel mechanisms of resistance of CML LSC to TKI treatment, and suggest new targets for treatment designed to eradicate residual LSC in CML patients. RNA was obtained from CML CD34+ cells treated with or without IM (5M-NM-<M) and MSC for 96 hours, amplified, labeled and hybridized to GeneChip 1.0 arrays (Affymetrix, Santa Clara, CA). Microarray data analysis was performed using R (version 2.9) with genomic analysis packages from Bioconductor (version 2.4). The 33297 probes represented on the microarray were filtered by cross-sample mean, and for standard deviation of greater than the 25% quantile, yielding 18624 probes representing 12553 genes. Linear regression was used to model the gene expression with the consideration of a 2x2 factorial design and matched samples. Differentially expressed genes were identified by calculating empirical Bayes moderated t-statistic, and p-values were adjusted by FDR using the M-bM-^@M-^\LIMMAM-bM-^@M-^] package. Gene Set Enrichment Analysis (GSEA) was performed using GSEA software version 2.04 to detect enrichment of predetermined gene sets using t-scores from all genes for 1263 gene sets in the C2 (curated gene sets) category from the Molecular Signature Database (MsigDB).

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Expression data from MSCs of healthy donors vs. CML patients

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