Proteomics and metabolomics identify molecular mechanisms of aging potentially predisposing for chronic lymphocytic leukemia.

B cell chronic lymphocytic leukemia (B-CLL), the most common type of leukemia in adults, is still essentially incurable despite the development of novel therapeutic strategies. This reflects the incomplete understanding of the pathophysiology of this disease. A comprehensive proteome analysis of primary human B-CLL cells and B cells from younger as well as elderly healthy donors was performed. For comparison, the chronic B cell leukemia cell line JVM-13 was also included. A principal component analysis comprising 6,945 proteins separated these four groups, placing B cells of aged-matched controls between those of young donors and B-CLL patients, while identifying JVM-13 as poorly related cells. Mass spectrometric proteomics data have been made fully accessible via ProteomeXchange with identifier PXD006570-PXD006572, PXD006576, PXD006578, and PXD006589-PXD006591. Remarkably, B cells from aged controls displayed significant regulation of proteins related to stress management in mitochondria and ROS stress such as DLAT, FIS1, and NDUFAB1, and DNA repair, including RAD9A, MGMT, and XPA. ROS levels were indeed found significantly increased in B cells but not in T cells or monocytes from aged individuals. These alterations may be relevant for tumorigenesis and were observed similarly in B-CLL cells. In B-CLL cells, some remarkable unique features like the loss of tumor suppressor molecules PNN and JARID2, the stress-related serotonin transporter SLC6A4, and high expression of ZNF207, CCDC88A, PIGR and ID3, otherwise associated with stem cell phenotype, were determined. Alterations of metabolic enzymes were another outstanding feature in comparison to normal B cells, indicating increased beta-oxidation of fatty acids and increased consumption of glutamine. Targeted metabolomics assays corroborated these results. The present findings identify a potential proteome signature for immune senescence in addition to previously unrecognized features of B-CLL cells and suggest that aging may be accompanied by cellular reprogramming functionally relevant for predisposing B cells to transform to B-CLL cells.

Reconstitution of PTEN activity by CK2 inhibitors and interference with the PI3-K/Akt cascade counteract the antiapoptotic effect of human stromal cells in chronic lymphocytic leukemia.

Evidence suggests that tumor microenvironment is critically involved in supporting survival of chronic lymphocytic leukemia (CLL) cells. However, the molecular mechanisms of this effect and the clinical significance are not fully understood. We applied a microenvironment model to explore the interaction between CLL cells and stromal cells and to elucidate the role of phosphatidylinositol 3 kinase (PI3-K)/Akt/phosphatase and tensin homolog detected on chromosome 10 (PTEN) cascade in this process and its in vivo relevance. Primary human stromal cells from bone marrow, lymph nodes, and spleen significantly inhibited spontaneous apoptosis of CLL cells. Pan-PI3-K inhibitors (LY294002, wortmannin, PI-103), isotype-specific inhibitors of p110α, p110ß, p110γ, and small interfering RNA against PI3-K and Akt1 counteracted the antiapoptotic effect of the stromal cells. Induction of apoptosis was associated with a decrease in phosphatidylinositol-3,4,5-triphosphate, PI3-K-p85, and dephosphorylation of phosphatidylinositol-dependent kinase-1 (PDK-1), Akt1, and PTEN. Freshly isolated peripheral blood mononuclear cells from patients with CLL (n = 44) showed significantly higher levels of phosphorylated Akt1, PDK-1, PTEN, and CK2 than healthy persons (n = 8). CK2 inhibitors (4,5,6,7-tetrabromo-1H-benzotriazole, apigenin, and 5,6-dichloro-1-ß-D-ribofuranosylbenzimidazol) decreased phosphorylation of PTEN and Akt, induced apoptosis in CLL cells, and enhanced the response to fludarabine. In conclusion, bone marrow microenvironment modulates the PI3-K/Akt/PTEN cascade and prevents apoptosis of CLL cells. Combined inhibition of PI3-K/Akt and recovery of PTEN activity may represent a novel therapeutic concept for CLL.

NOTCH2 links protein kinase C delta to the expression of CD23 in chronic lymphocytic leukaemia (CLL) cells.

One characteristic of chronic lymphocytic leukaemia (CLL) lymphocytes is high expression of CD23, which has previously been identified as a downstream target for NOTCH2 signalling. The mechanisms regulating NOTCH2-dependent CD23 expression, however, are largely unknown. This study showed that peripheral CLL cells overexpressed transcriptionally active NOTCH2 (N2(IC)), irrespective of their prognostic marker profile. When placed in culture, NOTCH2 activity was spontaneously decreased in 25 out of 31 CLL cases (81%) within 24 h. DNA-bound N2(IC) complexes could be maintained by the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) or by gamma-interferon (IFN-gamma), two CLL characteristic inducers of CD23 expression. Inhibition of PKC-delta by RNA interference or by rottlerin antagonised PMA-induced NOTCH2 activation and also suppressed NOTCH2 activity in CLL cases with constitutively activated NOTCH2 signalling. In 23 out of 29 CLL cases tested (79%), DNA-bound N2(IC) complexes were found to be resistant to the gamma-secretase inhibitor (GSI) DAPT, suggesting that GSIs will be only effective in a subset of CLL cases. These data suggest that deregulation of NOTCH2 signalling is critically involved in maintaining the malignant phenotype of CLL lymphocytes and point to a link between PKC-delta and NOTCH2 signalling in the leukemic cells.

TGF-beta1 induces bone marrow reticulin fibrosis in hairy cell leukemia.

The mechanisms that lead to reticulin fibrosis of bone marrow (BM) in hairy cell leukemia (HCL) are not fully understood. We therefore investigated the involvement of TGF-beta1, a potent fibrogenic cytokine, in this process. Immunoassays revealed that TGF-beta1 is present at higher concentrations in BM, serum, and plasma of HCL patients in comparison with healthy donors (P < 0.001). RT-PCR and immunofluorescence studies showed that TGF-beta1 is overexpressed at the mRNA and protein levels in peripheral blood, spleen, and BM mononuclear cells and that hairy cells (HCs) are the main source of TGF-beta1. Active TGF-beta1 correlated significantly with grades of BM fibrosis, infiltration with HCs, and serum procollagen type III aminoterminal propeptide (PIIINP). Ex vivo studies demonstrated that TGF-beta1 significantly enhances the production and deposition of reticulin and collagen fibers by BM fibroblasts. In addition, BM plasma of HCL patients increased the synthesis of type I and type III procollagens, the main components of reticulin fibers, at the mRNA and protein levels. This fibrogenic activity of BM plasma was abolished by neutralizing anti-TGF-beta1 antibodies. These results show, for the first time to our knowledge, that TGF-beta1 is highly expressed in HCs and is directly involved in the pathogenesis of BM reticulin fibrosis in HCL.

Effect of combined spa-exercise therapy on circulating TGF-beta1 levels in patients with ankylosing spondylitis.

BACKGROUND: Ankylosing spondylitis (AS) is a chronic inflammatory disease of the axial joints with no satisfactory therapy. Reduction of joint pain has been reported after a course of therapy at a spa, Gasteiner Heilstollen, in Badgastein in Austria. The mechanism underlying this beneficial effect is not clearly understood and objective evidence for the biological response to therapy is lacking. The aim of this study was to find evidence for a biological response to speleotherapy in patients with AS and to study the involvement of the antiinflammatory cytokine TGF-beta1 in this response. PATIENTS AND METHODS: 83 patients with AS were treated in Badgastein for 3-4 weeks. Therapy included active exercises, hyperthermia and exposure to low doses of radon in a former mine. Response to therapy was assessed from measurement of morning pain and immunoassay of serum levels of TGF-beta1 before and after therapy. Ten AS patients who received conventional therapy and 10 patients with low back pain (LBP) served as controls. RESULTS: A significant increase in TGF-beta1 (total and active) was found in AS patients after spa therapy. Mean concentration of total TGF-beta1 increased from 28,715 pg/ml to 43,136 pg/ml, (P<0.01) and active TGF-beta1 increased from 77 pg/ml to 1096 pg/ml (P<0.001). When the AS patients were divided into two groups according to pain reduction, group 1 (decrease in morning pain, responders: n=46) exhibited a 17-fold increase of active TGF-beta1 levels (96 pg/ml to 1654 pg/ml, P<0.0001) whereas group 2 (no change or an increase in morning pain: nonresponders: n=37), showed only 7-fold increase (53 pg/ml to 402 pg/ml, P<0.01). There was a moderate increase in active TGF-beta1 from 31 pg/ml to 42 pg/ml (P<0.05) in patients with LBP and no significant change was observed in the patients treated with conventional therapy. CONCLUSION: These results demonstrate a significant increase in circulating TGF-beta1 in patients with AS after the combined spa-exercise therapy in Badgastein. The results also provide evidence for a biological response to speleotherapy and suggest that TGF-beta, through its antiinflammatory function, may play a role in this response.

Positive troponin T without cardiac involvement in inclusion body myositis.

Cardiac troponin T (cTnT) is considered as a specific marker for acute myocardial infarction. Here, we present a case with elevated cTnT, determined by a third-generation assay, without signs of a myocardial lesion. Routine investigation of a 66-year-old female patient with indolent B-cell lymphoma revealed increased serum levels of creatine kinase (CK), MB fraction of CK (CK-MB), and cTnT, although she did not complain of cardiac symptoms. Electrocardiographic monitoring, echocardiography, magnetic resonance computed angiography, and percutaneous coronary angiography excluded myocardial damage. However, the close follow-up showed a steady increase of CK-MB and cTnT levels and gradual development of weakness in both thighs. A biopsy of the right quadriceps muscle led to the diagnosis of inclusion body myositis. In contrast to cTnT, cardiac troponin I could not be detected retrospectively in any of her serum samples. These results demonstrate for the first time that cTnT is elevated in patients with inclusion body myositis.

The role of soluble CD23 in distinguishing stable and progressive forms of B-chronic lymphocytic leukemia.

Soluble CD23 (sCD23) has been recognized as an important prognostic parameter in patients with chronic lymphocytic leukemia (B-CLL) at early clinical stages. There is, however, no clear information on its prognostic significance in advanced stages and on its role as an indicator for aggressive or indolent courses of disease. Therefore, sCD23 was measured in the serum of 145 patients at diagnosis and serial determinations were carried out for 8 years in 38 patients. The results indicate that in patients with identical clinical stages at first presentation the disease could take different courses depending on initial sCD23 concentrations below or above specific threshold levels (860 and 5900U/ml). sCD23 higher than these thresholds was associated with faster progression into upper clinical stages. Furthermore, sCD23-doubling time (sCD23-DT) indicated that patients with long DT progressed slowly, while those with short DT had more aggressive disease. Particularly in patients with advanced disease stages, long sCD23-DT indicated development of smoldering disease. Since sCD23 levels reflect total tumor mass, determination of sCD23-DT has probably a better predictive value than lymphocyte doubling time. It appears that B-CLL patients can be divided into different risk categories according to initial determinations of sCD23 and that sCD23-DT is an additional important parameter in predicting disease progression.

In vitro cytotoxic effect of proteasome inhibitor bortezomib in combination with purine nucleoside analogues on chronic lymphocytic leukaemia cells.

OBJECTIVE: The anti-tumour in vitro activity of proteasome inhibitor bortezomib (PS-341, VELCADE) in combination with purine nucleoside analogues, cladribine (2-CdA) and fludarabine (FA) was tested in lymphocytes derived from 26 patients with B-cell chronic lymphocytic leukaemia (B-CLL). METHODS: Cell viability was assessed by propidium iodide staining, and apoptosis by annexin-V and caspase activation flow cytometry assays. Additionally, expression of the apoptosis-regulating proteins Bax, Bak, Bid, Bcl-w, Bcl-2, XIAP and Mcl-1 was evaluated in B-CLL lymphocytes. RESULTS: Bortezomib alone induced significant, dose-dependent cytotoxicity starting from the low concentration 2.5 nm, inducing apoptosis of B-CLL cells. Combination of this agent with 2-CdA or FA resulted in an increase of cytotoxicity when compared with that mediated by single drugs. The observed increase was especially evident when 5 nm of bortezomib were combined with suboptimal doses of 2-CdA or FA. The combination index (CI) was 0.87 for bortezomib + 2-CdA and 0.82 for bortezomib + FA, indicating an evident additive effect of these combinations. Moreover, B-CLL cells were more sensitive to proteasome inhibitor used alone or combined with 2-CdA or FA comparing to CD3+ lymphocytes. Corresponding to enhanced apoptosis, the expression levels of several apoptosis-regulating proteins were altered. The most pronounced changes were down-regulation of XIAP and up-regulation of Bid proteins by the combination of bortezomib with either 2-CdA or FA. CONCLUSIONS: This study suggest that the in vitro cytotoxic effect through proteasome inhibition by bortezomib can be increased substantially with low doses of the purine nucleoside analogues, 2-CdA and FA, and that this effect on B-CLL cell is selectively higher than on normal, CD3-positive lymphocytes.

Notch2 is involved in the overexpression of CD23 in B-cell chronic lymphocytic leukemia.

Members of the Notch family encode transmembrane receptors that modulate differentiation, proliferation, and apoptotic programs of many precursor cells, including hematopoietic progenitors. Stimulation of Notch causes cleavage followed by translocation of the intracellular domain (NotchIC) to the nucleus, where it activates transcription of CBF1 responsive genes. The aim of this study was to elucidate the mechanisms leading to the overexpression of CD23, a striking feature of B-cell chronic lymphocytic leukemia (B-CLL) cells. By electrophoretic mobility shift assays, we identified a transcription factor complex (C1) that binds sequence specific to one known and 4 newly identified putative CBF1 recognition sites in the CD23a core promoter region. With the use of Epstein-Barr virus (EBV)-infected B cells as a model for CBF1 mediated CD23a expression, C1 was found to be EBV inducible. Supershift assays revealed that the nuclear form of Notch2 is a component of C1 in B-CLL cells, supporting a model in which NotchIC activates transcription by binding to CBF1 tethered to DNA. Transient transfection of REH pre-B cells with an activated form of Notch2 induced endogenous CD23a, confirming that CD23a is a target gene of Notch2 signaling. Finally, reverse transcription-polymerase chain reaction and kinetic analysis demonstrated that the Notch2 oncogene is not only overexpressed in B-CLL cells but might also be related to the failure of apoptosis characteristic for this disease. In conclusion, these data suggest that deregulation of Notch2 signaling is involved in the aberrant expression of CD23 in B-CLL.