ABSTRACT
Anaplastic Lymphoma Kinase-positive Anaplastic Large Cell Lymphomas (ALK+ ALCL) occur predominantly in children and young adults. Their treatment, based on aggressive chemotherapy, is not optimal since ALCL patients can still expect a 30% 2-year relapse rate. Tumor relapses are very aggressive and their underlying mechanisms are unknown. Crizotinib is the most advanced ALK tyrosine kinase inhibitor and is already used in clinics to treat ALK-associated cancers. However, crizotinib escape mechanisms have emerged, thus preventing its use in frontline ALCL therapy. The process of autophagy has been proposed as the next target for elimination of the resistance to tyrosine kinase inhibitors. In this study, we investigated whether autophagy is activated in ALCL cells submitted to ALK inactivation (using crizotinib or ALK-targeting siRNA). Classical autophagy read-outs such as autophagosome visualization/quantification by electron microscopy and LC3-B marker turn-over assays were used to demonstrate autophagy induction and flux activation upon ALK inactivation. This was demonstrated to have a cytoprotective role on cell viability and clonogenic assays following combined ALK and autophagy inhibition. Altogether, our results suggest that co-treatment with crizotinib and chloroquine (two drugs already used in clinics) could be beneficial for ALK-positive ALCL patients.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Autophagy/drug effects , Chloroquine/pharmacology , Lymphoma, Large-Cell, Anaplastic/drug therapy , Protein Kinase Inhibitors/pharmacology , Pyrazoles/pharmacology , Pyridines/pharmacology , Receptor Protein-Tyrosine Kinases/antagonists & inhibitors , Anaplastic Lymphoma Kinase , Animals , Cell Line, Tumor , Cell Survival/drug effects , Crizotinib , Dose-Response Relationship, Drug , Drug Synergism , Female , Humans , Lymphoma, Large-Cell, Anaplastic/enzymology , Lymphoma, Large-Cell, Anaplastic/genetics , Lymphoma, Large-Cell, Anaplastic/pathology , Mice, Inbred NOD , Mice, SCID , Microtubule-Associated Proteins/metabolism , RNA Interference , Receptor Protein-Tyrosine Kinases/genetics , Receptor Protein-Tyrosine Kinases/metabolism , Signal Transduction/drug effects , Time Factors , Transfection , Xenograft Model Antitumor AssaysABSTRACT
Graft-versus-host disease (GvHD) is a major complication of allogeneic bone marrow transplantation and occurs when donor T cells react with histo-incompatible recipient's antigens. In the present study, we analyzed the contribution of CD4 T cell subsets, defined according to their CD45RC expression level, in the development of acute and chronic GvHD. For this purpose, we used the model of GvHD induced in rats when parental lymphocytes are transferred to irradiated (LEWxBN) F1 hybrid recipients. We showed that parental CD45RC(high) (naive cells) CD4 T cells induced both acute and chronic GvHD while CD45RC(low) (memory cells) subset did not. In vitro, only CD45RC(high) CD4 T cells proliferated and produced cytokines in response to alloantigen stimulation. LEW and BN CD45RC(high) CD4 T cells produced different cytokine profiles in response to in vitro allostimulation, which could explain their ability to induce different forms of GvHD. Finally, we showed that memory CD45RC(low) CD4 T cells, known to contain regulatory T cells, were unable to prevent GvHD induction. Together these data show that memory CD45RC(low) CD4 T cells do not contain functional alloreactive T cells and suggest that selective transfusion of donor memory cells could greatly improve post-transplant immune reconstitution without risk of GvHD induction.
