Cyclic ADP-ribose metabolism in rat kidney: High capacity for synthesis in glomeruli

Cyclic ADP-ribose metabolism in rat kidney: High capacity for synthesis in glomeruli. Recent discovery of cyclic ADP-ribose (cADPR) as an agent that triggers Ca2+ release from intracellular stores, through ryanodine receptor channel, is an important new development in the investigation of intracellular signaling mechanisms. We determined the capacity of kidney and its components for synthesis of cADPR from β-NAD, that is catalyzed by enzyme ADP-ribosyl cyclase, and enzymatic inactivation that is catalyzed by cADPR-glycohydrolase. Little or no activity of ADP-ribosyl cyclase was found in extracts from the whole rat kidney, renal cortex, outer and inner medulla. On the other hand, incubation of β-NAD with similar extracts from rat liver, spleen, heart, and brain resulted in biosynthesis of cADPR. In addition, extracts from suspension of proximal tubules or microdissected proximal convoluted tubules virtually lacked ADP-ribosyl cyclase activity. In sharp contrast to proximal tubules and cortex, extracts from glomeruli had high ADP-ribosyl cyclase activity, similar to that found in non-renal tissues. Authenticity of cADPR biosynthesized in glomeruli was documented by several criteria such as HPLC analysis, effect of inhibitors and homologous desensitization of Ca2+-release bioassay. On the other hand, the activity of cADPR-glycohydrolase was similar in extracts from glomeruli and in extracts from kidney cortex. Mesangial cells and vascular smooth muscle cells grown in primary culture displayed considerable ADPR-ribose cyclase activity. Our results show that extracts from glomeruli, unlike extracts from renal tissue zones and proximal tubules, have a singularly high capacity for synthesis of cADPR. We surmise that cADPR-triggered Ca2+-releasing system can serve as an intracellular signaling pathway that may be operant in regulations of glomerular cell functions

Complete suppression of viral gene expression is associated with the onset and progression of lymphoid malignancy: observations in Bovine Leukemia Virus-infected sheep

BACKGROUND: During malignant progression, tumor cells need to acquire novel characteristics that lead to uncontrolled growth and reduced immunogenicity. In the Bovine Leukemia Virus-induced ovine leukemia model, silencing of viral gene expression has been proposed as a mechanism leading to immune evasion. However, whether proviral expression in tumors is completely suppressed in vivo was not conclusively demonstrated. Therefore, we studied viral expression in two selected experimentally-infected sheep, the virus or the disease of which had features that made it possible to distinguish tumor cells from their nontransformed counterparts. RESULTS: In the first animal, we observed the emergence of a genetically modified provirus simultaneously with leukemia onset. We found a Tax-mutated (TaxK303) replication-deficient provirus in the malignant B-cell clone while functional provirus (TaxE303) had been consistently monitored over the 17-month aleukemic period. In the second case, both non-transformed and transformed BLV-infected cells were present at the same time, but at distinct sites. While there was potentially-active provirus in the non-leukemic blood B-cell population, as demonstrated by ex-vivo culture and injection into naïve sheep, virus expression was completely suppressed in the malignant B-cells isolated from the lymphoid tumors despite the absence of genetic alterations in the proviral genome. These observations suggest that silencing of viral genes, including the oncoprotein Tax, is associated with tumor onset. CONCLUSION: Our findings suggest that silencing is critical for tumor progression and identify two distinct mechanisms-genetic and epigenetic-involved in the complete suppression of virus and Tax expression. We demonstrate that, in contrast to systems that require sustained oncogene expression, the major viral transforming protein Tax can be turned-off without reversing the transformed phenotype. We propose that suppression of viral gene expression is a contributory factor in the impairment of immune surveillance and the uncontrolled proliferation of the BLV-infected tumor cell.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Activity of tafasitamab in combination with rituximab in subtypes of aggressive lymphoma

BackgroundDespite recent advances in the treatment of aggressive lymphomas, a significant fraction of patients still succumbs to their disease. Thus, novel therapies are urgently needed. As the anti-CD20 antibody rituximab and the CD19-targeting antibody tafasitamab share distinct modes of actions, we investigated if dual-targeting of aggressive lymphoma B-cells by combining rituximab and tafasitamab might increase cytotoxic effects.MethodsAntibody single and combination efficacy was determined investigating different modes of action including direct cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) in in vitro and in vivo models of aggressive B-cell lymphoma comprising diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL).ResultsThree different sensitivity profiles to antibody monotherapy or combination treatment were observed in in vitro models: while 1/11 cell lines was primarily sensitive to tafasitamab and 2/11 to rituximab, the combination resulted in enhanced cell death in 8/11 cell lines in at least one mode of action. Treatment with either antibody or the combination resulted in decreased expression of the oncogenic transcription factor MYC and inhibition of AKT signaling, which mirrored the cell line-specific sensitivities to direct cytotoxicity. At last, the combination resulted in a synergistic survival benefit in a PBMC-humanized Ramos NOD/SCID mouse model.ConclusionThis study demonstrates that the combination of tafasitamab and rituximab improves efficacy compared to single-agent treatments in models of aggressive B-cell lymphoma in vitro and in vivo

Analysis of TRAIL-induced apoptosis in acute myeloid leukemia cells

Advanced tumors, including leukemia, represent heterogeneous cell populations evolved from original malignant clones. Chemotherapy of leukemia is often associated with selection of drug-resistant cells followed by progression/relapse of the disease. Implementation of molecules that specifically target leukemia cells with minimal toxicity to normal tissues might significantly improve outcome of leukemia treatment. TRAIL belongs to the tumor necrosis factor (TNF) ligand family of cytokines. TRAIL triggers apoptosis in target cells via the receptor-mediated apoptotic pathway. Receptors for TRAIL can be divided into death receptors, TRAILR1/ DR4 , TRAIL-R2/DR5, and decoy receptors, TRAIL-R3/DcR1, TRAIL-R4/DcR2, osteoprotegerin/OPG/TRAIL-R5, based on their ability to transduce apoptotic signal. While normal tissues, including hematopoietic progenitor cells, are resistant to TRAIL-induced apoptosis, TRAIL induces programmed death in many tumor cell lines and primary cells. Various malignant cell lines and primary tumor cells, however, show resistance to TRAIL-induced apoptosis. TRAIL-resistance could represent important limitation for the potential TRAIL anti-tumor therapy. Combined in vitro application of TRAIL with other anti-cancer agents often increased sensitivity or overcame resistance of the tumor cells to..

Analýza TRAILem indukované apoptózy u buněk akutní myeloidní leukémie

Advanced tumors, including leukemia, represent heterogeneous cell populations evolved from original malignant clones. Chemotherapy of leukemia is often associated with selection of drug-resistant cells followed by progression/relapse of the disease. Implementation of molecules that specifically target leukemia cells with minimal toxicity to normal tissues might significantly improve outcome of leukemia treatment. TRAIL belongs to the tumor necrosis factor (TNF) ligand family of cytokines. TRAIL triggers apoptosis in target cells via the receptor-mediated apoptotic pathway. Receptors for TRAIL can be divided into death receptors, TRAILR1/ DR4 , TRAIL-R2/DR5, and decoy receptors, TRAIL-R3/DcR1, TRAIL-R4/DcR2, osteoprotegerin/OPG/TRAIL-R5, based on their ability to transduce apoptotic signal. While normal tissues, including hematopoietic progenitor cells, are resistant to TRAIL-induced apoptosis, TRAIL induces programmed death in many tumor cell lines and primary cells. Various malignant cell lines and primary tumor cells, however, show resistance to TRAIL-induced apoptosis. TRAIL-resistance could represent important limitation for the potential TRAIL anti-tumor therapy. Combined in vitro application of TRAIL with other anti-cancer agents often increased sensitivity or overcame resistance of the tumor cells to...Institute of Pathological Physiology First Faculty of Medicine Charles University in PragueÚstav patologické fyziologie 1. LF UK v PrazeFirst Faculty of Medicine1. lékařská fakult

Advances in Molecular Biology and Targeted Therapy of Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is a heterogeneous malignancy with a broad spectrum of clinical behavior from indolent to highly aggressive cases. Despite the fact that MCL remains in most cases incurable by currently applied immunochemotherapy, our increasing knowledge on the biology of MCL in the last two decades has led to the design, testing, and approval of several innovative agents that dramatically changed the treatment landscape for MCL patients. Most importantly, the implementation of new drugs and novel treatment algorithms into clinical practice has successfully translated into improved outcomes of MCL patients not only in the clinical trials, but also in real life. This review focuses on recent advances in our understanding of the pathogenesis of MCL, and provides a brief survey of currently used treatment options with special focus on mode of action of selected innovative anti-lymphoma molecules. Finally, it outlines future perspectives of patient management with progressive shift from generally applied immunotherapy toward risk-stratified, patient-tailored protocols that would implement innovative agents and/or procedures with the ultimate goal to eradicate the lymphoma and cure the patient