Citrullination of histone H3 drives IL-6 production by bone marrow mesenchymal stem cells in MGUS and multiple myeloma

Multiple myeloma (MM), an incurable plasma cell malignancy, requires localisation within the bone marrow. This microenvironment facilitates crucial interactions between the cancer cells and stromal cell types that permit the tumour to survival and proliferate. There is increasing evidence that the bone marrow mesenchymal stem cell (BMMSC) is stably altered in patients with MM – a phenotype also postulated to exist in patients with monoclonal gammopathy of undetermined significance (MGUS) a benign condition that precedes MM. In this study, we describe a mechanism by which increased expression of peptidyl arginine deiminase 2 (PADI2) by BMMSCs in patients with MGUS and MM directly alters malignant plasma cell phenotype. We identify PADI2 as one of the most highly upregulated transcripts in BMMSCs from both MGUS and MM patients, and that through its enzymatic deimination of histone H3 arginine 26, PADI2 activity directly induces the upregulation of interleukin-6 (IL-6) expression. This leads to the acquisition of resistance to the chemotherapeutic agent, bortezomib, by malignant plasma cells. We therefore describe a novel mechanism by which BMMSC dysfunction in patients with MGUS and MM directly leads to pro-malignancy signalling through the citrullination of histone H3R26

Comparative analysis of different methodological approaches to the in vitro study of tumour cells chemosensitivity

Drug sensitivity assay was performed using two human tumour celi lines: HeLa and Hep-2 cultivated in two-dimensional monolayer celi cultures and three-dimensional cultures on gelatine sponge SpongostanK. Two cytostatics with different mechanisms of anti-tumour action were used: cisplatin and etoposide. Chemosensitivity of tumour cells was assessed by counting the number of viable and nonviable cells (cytostatic and cytotoxic activity of drugs), by counting the number of apoptotic cells and by clonogenic assay of viable cells. We found that the clonogenic assay was morę sensitive than the other tests used, especially after long-term (7 days) treatment of tumour cells with cytostatics. A short (24h) treatment with cytostatics gave false results which were not confirmed after prolonged treatment with cytostatics. We suppose that short treatment tests should not be used for examination of the chemosensitivity of tumour cells isolated from patients. Tumour cells growing on SpongostanH were viable for a longer time than in monolayer cultures and exhibited chemosensitivity comparable to monolayer celi cultures despite of their multilayer growth on gelatine sponge.Do badań wrażliwości na cytostatyki użyto dwie ludzkie linie nowotworowe: HeLa i Hep-2, hodowane w formie murawy dwuwymiarowej (płaskiej) oraz w formie przestrzennej, trójwymiarowej, na gąbce żelatynowej Spongostan". W badaniach użyto cytostatyki posiadające różny mechanizm działania przeciwnowotworowego, a mianowicie cisplatynę i etopozyd. Wrażliwość komórek nowotworowych na chemioterapeutyki określano ilością komórek przeżywających i martwych (cytostatyczne i cytotoksyczne właściwości leków), ilością komórek apoptotycznych oraz oceniano klonogenne właściwości komórek przeżywających. Stwierdzono, że ocena klonogennych właściwości komórek jest metodą bardziej czułą w porównaniu z innymi testami, szczególnie po długim (7-dniowym) kontakcie komórek z cytostatykami. Ocena krótkotrwałego (24-godz.) kontaktu komórek nowotworowych z cytostatykami dawała fałszywe wyniki, nie potwierdzone po długotrwałej inkubacji komórek z cytostatykami. Uważamy, że testy polegające na ocenie efektu krótkotrwałej inkubacji komórek z lekami nie powinny być stosowane do oceny wrażliwości na chemioterapeutyki komórek nowotworowych izolowanych od pacjenta. Komórki nowotworowe rosnące na Spongostanie” były żywe dłużej niż rosnące w hodowlach płaskich i pomimo wielowarstwowego wzrostu na gąbce żelatynowej wykazywały wrażliwość na leki porównywalną z hodowlami płaskimi

Evidences of Early Senescence in Multiple Myeloma Bone Marrow Mesenchymal Stromal Cells

Background: In multiple myeloma, bone marrow mesenchymal stromal cells support myeloma cell growth. Previous studies have suggested that direct and indirect interactions between malignant cells and bone marrow mesenchymal stromal cells result in constitutive abnormalities in the bone marrow mesenchymal stromal cells. Design and Methods: The aims of this study were to investigate the constitutive abnormalities in myeloma bone marrow mesenchymal stromal cells and to evaluate the impact of new treatments. Results: We demonstrated that myeloma bone marrow mesenchymal stromal cells have an increased expression of senescence-associated β-galactosidase, increased cell size, reduced proliferation capacity and characteristic expression of senescence-associated secretory profile members. We also observed a reduction in osteoblastogenic capacity and immunomodulatory activity and an increase in hematopoietic support capacity. Finally, we determined that current treatments were able to partially reduce some abnormalities in secreted factors, proliferation and osteoblastogenesis. Conclusions: We showed that myeloma bone marrow mesenchymal stromal cells have an early senescent profile with profound alterations in their characteristics. This senescent state most likely participates in disease progression and relapse by altering the tumor microenvironment. © 2013 André et al.SCOPUS: ar.jinfo:eu-repo/semantics/publishe