Project description: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.
Project description:Transcriptional profiling of human T cells analyzing the impact of race on the responsiveness to IFNa in healthy blood donors. Control and IFNa-treated samples derived from healthy Caucasian American vs. African American blood donors are compared.
Project description:Transcriptional profiling of human MSCs comparing control MSCs with parathyroid hormone (PTH)-stimulated MSCs. PTH-stimulated MSCs were treated with 0.1 nM recombinant human PTH (N-terminal fragment, amino acids 1-34) for 48 hours. Human MSCs were isolated from a bone marrow sample obtained from a healthy adult volunteer. Two-condition experiment: control MSCs vs. PTH-stimulated MSCs. 1 control MSCs and 1 PTH-stimulated MSCs.
Project description:It is now well established that bone marrow (BM) constitutes a microenvironment required for differentiation. Bone marrow mesenchymal stromal cells (BM-MSCs) strongly support MM cell growth, by producing a high level of Interleukin-6 (IL-6), a major MM cell growth factor. BM-MSCs also support osteoclastogenesis and angiogenesis. Previous studies have suggested that the direct (VLA-4, VCAM-1, CD44, VLA-5, LFA-1, syndecan-1,M-bM-^@M-&) and indirect interactions (soluble factors) between MM plasma cells and BM-MSCs result in constitutive abnormalities in BM-MSCs. In particular, MM BM-MSCs express less CD106 and fibronectin and more DKK1, IL-1M-NM-2 and TNF-M-NM-1 as compared with normal BM-MSCs. In order to gain a global view of the differences between BM-MSCs from MM patients and healthy donors, we used gene expression profiling to identify genes associated to the transformation of MM BM-MSCs. BM-MSCs were isolated from 3 healthy donors and 4 untreated multiple myeloma patients. Total RNA from BM-MSCs was exctracted and hybridyzed on Affymetrix GeneChipM-BM-. Human Genome U133 Plus 2.0 Array. Amplification, hybridization and scanning were done according to standard Affymetrix protocols (www.affymetrix.com). CEL files were normalized with RMA method.