title: Guilty bystanders: nurse-like cells as a model of microenvironmental support for leukemic lymphocytes.
abstract: B-cell chronic lymphocytic leukemia (B-CLL) is one of the most common leukemias among the elderly and, despite many efforts, still stays incurable. Recent studies point to the microenvironment as the critical factor providing leukemic lymphocytes with pro-survival signals. Thus, the neighboring cells appear to be a perfect target for antileukemic therapy. Nurse-like cells (NLCs) largely contribute to CLL microenvironmental support. We developed the CLL lymphocyte/NLC co-culture model for the investigation of microenvironmental interactions. Viability and apoptosis were investigated in CLL lymphocytes treated with dexamethasone (DEX) and chlorambucil (CLB), with and without NLCs' support. For the first time, the capacity of DEX and CLB to affect NLCs viability was also evaluated. Apoptosis-associated gene expression profiles of leukemic lymphocytes ex vivo and cultured with NLCs were assessed by expression arrays. CLL lymphocytes escaped spontaneous apoptosis for several months when cultured with NLCs. The presence of NLCs significantly reduced apoptosis induced with DEX and CLB (p < 0.001; p = 0.012, respectively), and their protective effect was more evident than the effect of recombinant SDF1. Both DEX and CLB also decreased NLCs viability, but to a lesser extent (mean viability in DEX-treated cultures was 37.79% in NLCs compared to 29.24% in lymphocytes). NLCs induced the expression of important anti-apoptotic genes in cultured CLL lymphocytes; median expression of BCL2, SURVIVIN, BCL2A1, and XIAP was significantly higher as compared to ex vivo status. The CLL lymphocyte/NLC co-culture makes up the convenient and close to the natural-state model for studying the relationship between leukemic cells and the microenvironment. Direct cell-to-cell contact with NLCs increases the expression of anti-apoptotic genes in CLL lymphocytes, thus protecting them against induced apoptosis. As the effect of antileukemic drugs is not so apparent in NLCs, the combined therapy targeted at both lymphocytes and the microenvironment should be considered for CLL patients. Simultaneous aiming at the disruption of several different signaling pathways and/or anti-apoptotic proteins may further improve treatment efficiency.
authors: Department of Cancer Genetics, Medical University of Lublin, Radziwillowska 11, 20-080, Lublin, Poland, aafilip@hotmail.com.
authors: Agata A
authors: AA
authors: Filip
authors: Bogumiła
authors: B
authors: Ciseł
authors: Ewa
authors: E
authors: Wąsik-Szczepanek
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000187:drug effects; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D024201:Bystander Effect / Q000235:genetics*; D002470:Cell Survival / Q000187:drug effects; D054377:Chemokine CXCL12 / Q000235:genetics / Q000378:metabolism; D002699:Chlorambucil / Q000494:pharmacology; D018920:Coculture Techniques; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015778:Minor Histocompatibility Antigens; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D059016:Tumor Microenvironment / Q000187:drug effects / Q000235:genetics; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C000595707:BCL2 protein, human; C096816:BCL2-related protein A1; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D002699:Chlorambucil; D003907:Dexamethasone