Antonello Petrella

NF-κB/Rel-mediated regulation of apoptosis in hematologic malignancies and normal hematopoietic progenitors

The activity of NF-κB/Rel transcription factors can downmodulate apoptosis in normal and neoplastic cells of the hematologic and other compartments, contributing in maintaining neoplastic clone survival and impairing response to therapy. Alterations in nfκb or iκB genes are documented in some hematologic neoplasias, while in others dysfunction in NF-κB/Rel-activating signaling pathways can be recognized. The prosurvival properties of NF-κB/Rel appear to rely on the induced expression of molecules (caspase inhibitors, Bcl2 protein family members, etc.), which interfere with the apoptosis pathway. Constitutive NF-κB/Rel activity in some hematologic malignancies could be advantageous for neoplastic clone expansion by counteracting stress stimuli (consumption of growth factors and metabolites) and immune system-triggered apoptosis; it is furthermore likely to play a central role in determining resistance to therapy. Based on this evidence, NF-κB/Rel-blocking approaches have been introduced in antineoplastic strategies. The identification of NF-κB/Rel target genes relevant for survival in specific neoplasias is required in order to address tailored therapies and avoid possible detrimental effects due to widespread NF-κB/Rel inhibition. Moreover, comparative analyses of normal hematopoietic progenitors and neoplastic cell sensitivities to inhibitors of NF-κB/Rel and their target genes will allow to evaluate the impact of these tools on normal bone marrow.

BAG3 protein regulates stress- induced apoptosis in normal and neoplastic leukocytes

We express our sincere thanks to Dr Junjiro Tsuchiyama for the NK-YS cell line and all medical and nursing staff in the Department of Medicine, Queen Mary Hospital for the provision of expert medical care. CS Chim KY Wong F Loong G Srivastava University Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong; and Department of Pathology, Queen Mary Hospital, The University of Hong Kong, Hong Kong

BAG3 protein regulates cell survival in childhood acute lymphoblastic leukemia cells.

No abstract available.

Cl-IB-MECA inhibits human thyroid cancer cell proliferation independently of A3 adenosine receptor activation

A3 adenosine receptor (A3AR) agonists have been reported to modulate cellular proliferation. This work was aimed to investigate the expression and the possible action of A3 receptor in the human thyroid carcinomas. Normal thyroid tissue samples did not express A3 adenosine receptor, while primary thyroid cancer tissues expressed high level of A3AR, as determined by immunohistochemistry analysis. In human papillary thyroid carcinoma cell line, NPA, at concentrations ≥10µM, the A3AR-selective agonist 2-chloro-N6-(3-iodobenzyl)adenosine-5’-N-methylcarboxamide (Cl-IB-MECA) produced inhibition of cell growth, by blocking the G1 cell cycle phase in a concentration- and time-dependent manner. This effect was well correlated with a reduction of protein expression of cyclins D1 and E2 after 24 hours of Cl-IB-MECA treatment. Moreover Cl-IB-MECA induced dephosphorylation of ERK1/2 in a time- and concentration-dependent manner, which in turn inhibits cell proliferation. The effect of Cl-IB-MECA was not prevented by A3AR antagonists, MRS1191 or MRS1523 or FA385. Furthermore, neither nucleoside transporter inhibitors, Dypiridamole and NBTI, nor the A1, A2A and A2B receptors antagonists were able to block the response to Cl-IB-MECA. Although Cl-IB-MECA has been shown to influence cell death and survival in other systems through an A3AR-mediated mechanism, in NPA cells the growth inhibition induced by micromolar concentrations of Cl-IB-MECA appeared not mediated through activation of this receptor and hence that its effects on human papillary carcinoma cell line seem to be independent of the presence of this receptor subtype.

Effects of FR235222, a novel HDAC inhibitor, in proliferation and apoptosis of human leukaemia cell lines: Role of Annexin A1

FR235222, a novel histone deacetylase inhibitor (HDACi), at 50nM caused accumulation of acetylated histone H4, inhibition of cell proliferation and G1 cycle arrest accompanied by increase of p21 and down-regulation of cyclin E in human promyelocytic leukaemia U937 cells. The compound was also able to increase the protein and mRNA levels of annexin A1 (ANXA1) without effects on apoptosis. Similar effects were observed in human chronic myelogenous leukaemia K562 cells and human T cell leukaemia Jurkat cells. Cycle arrest and ANXA1 expression, without significant effects on apoptosis, were also induced by different HDACi like suberoylanilide hydroxamic acid (SAHA) and trichostatin-A (TSA). FR235222 at 0.5 microM stimulated apoptosis of all leukaemia cell lines associated to an increased expression of the full-length (37kDa) protein and the appearance of a 33kDa N-terminal cleavage product in both cytosol and membrane. These results suggest that ANXA1 expression may mediate cycle arrest induced by low doses FR235222, whereas apoptosis induced by high doses FR235222 is associated to ANXA1 processing.

Role of Annexin A1 in Mouse Myoblast Cell Differentiation

Annexin A1 (ANXA1) is a calcium‐ and phospholipid‐binding protein involved in a broad range of cellular events. This study used molecular and microscopy approaches to explore the role of ANXA1 in mouse myoblast C2C12 cell differentiation. We report that ANXA1 expression increases during differentiation and that the down‐regulation of ANXA1 significantly inhibits the differentiation process. ANXA1 is expressed in vivo in both quiescent and activated satellite cells and is highly localized in the cells that migrate in the lumen of regenerating fibers after an acute injury. Endogenous ANXA1 co‐localizes with actin fibers at the protruding ends of undifferentiated but not differentiated cells suggesting a role of the protein in cell migration. Furthermore, ANXA1 neutralizing antibody reduces MyHC expression, decreases myotube formation and significantly inhibits cell migration. The data reported here suggest for the first time that ANXA1 plays a role in myogenic differentiation. J. Cell. Physiol. 224: 757–765, 2010.

Annexin-1 downregulation in thyroid cancer correlates to the degree of tumor differentiation.

We investigated the expression of annexin-1 (ANXA1) in thyroid carcinoma cell lines and in thyroid cancers with a different degree of differentiation. The highest level of ANXA1 expression examined by Western blotting was detected in the papillary carcinoma cells (NPA) and in the follicular cells (WRO). On the other hand, the most undifferentiated thyroid carcinoma cells (ARO and FRO) presented the lowest level of ANXA1 expression. In surgical tissue specimens from 32 patients with thyroid cancers, we found high immunoreactivity for ANXA1 in papillary (PTC) and follicular (FTC) thyroid cancers while in undifferentiated thyroid cancers (UTC) the expression of the protein was barely detectable. Control thyroid tissue resulted positive for ANXA1. In summary, 70% of UTC examined weakly expressed ANXA1, whereas 65% of PTC or FTC specimens tested showed high expression of the protein. Thus ANXA1 expression may correlate with the tumorigenesis suggesting that the protein may represent an effective differentiation marker in thyroid cancer.

Annexin A1: Novel roles in skeletal muscle biology

Annexin A1 (ANXA1, lipocortin‐1) is the first characterized member of the annexin superfamily of proteins, so called since their main property is to bind (i.e., to annex) to cellular membranes in a Ca2+‐dependent manner. ANXA1 has been involved in a broad range of molecular and cellular processes, including anti‐inflammatory signalling, kinase activities in signal transduction, maintenance of cytoskeleton and extracellular matrix integrity, tissue growth, apoptosis, and differentiation. New insights show that endogenous ANXA1 positively modulates myoblast cell differentiation by promoting migration of satellite cells and, consequently, skeletal muscle differentiation. This suggests that ANXA1 may contribute to the regeneration of skeletal muscle tissue and may have therapeutic implications with respect to the development of ANXA1 mimetics. J. Cell. Physiol. 227: 3007–3015, 2012.

Dipeptidyl Peptidase 4 Inhibition May Facilitate Healing of Chronic Foot Ulcers in Patients with Type 2 Diabetes

The pathophysiology of chronic diabetic ulcers is complex and still incompletely understood, both micro- and macroangiopathy strongly contribute to the development and delayed healing of diabetic wounds, through an impaired tissue feeding and response to ischemia. With adequate treatment, some ulcers may last only weeks; however, many ulcers are difficult to treat and may last months, in certain cases years; 19–35% of ulcers are reported as nonhealing. As no efficient therapy is available, it is a high priority to develop new strategies for treatment of this devastating complication. Because experimental and pathological studies suggest that incretin hormone glucagon-like peptide-1 may improves VEGF generation and promote the upregulation of HIF-1α through a reduction of oxidative stress, the study evaluated the effect of the augmentation of GLP-1, by inhibitors of the dipeptidyl peptidase-4, such as vildagliptin, on angiogenesis process and wound healing in diabetic chronic ulcers. Although elucidation of the pathophysiologic importance of these aspects awaits further confirmations, the present study evidences an additional aspect of how DPP-4 inhibition might contribute to improved ulcer outcome.

Cl‐IB‐MECA enhances TRAIL‐induced apoptosis via the modulation of NF‐κB signalling pathway in thyroid cancer cells

Apoptosis is an endogenous process that can be a useful anti‐cancer tool. This study aimed to investigate the effect of Cl‐IB‐MECA, adenosine receptor A3 agonist, on TRAIL‐induced apoptosis of thyroid carcinoma cells. Cl‐IB‐MECA enhanced TRAIL‐mediated apoptosis in FRO but not in ARO cells. This effect was correlated to higher expression levels of DR5 on FRO than ARO cells, that instead presented higher levels of decoy receptors, DcR1 and DcR2. To understand the cross‐talk between the effect of Cl‐IB‐MECA and TRAIL, we evaluated the nuclear translocation of p65 and c‐Rel. Since the dependency by NF‐κB, TRAIL promoted the nuclear translocation of both p65 and c‐Rel subunits. However, the addition of Cl‐IB‐MECA led to the predominant translocation of c‐Rel after TRAIL addition. Furthermore, Bcl‐2, cFLIP and pAkt were lower induced than caspase‐3 and ‐9 in FRO cells. To discriminate a specific effect of TRAIL, we used tumour necrosis factor‐alpha (TNF‐α) with Cl‐IB‐MECA. In this case, no synergism was observed. In addition, the effect of Cl‐IB‐MECA was not A3 receptor‐dependent since its antagonists, MRS1191 and FA385, failed to block Cl‐IB‐MECA activity on TRAIL‐treated FRO cells. In conclusion, Cl‐IB‐MECA enhanced TRAIL‐mediated apoptosis via NF‐κB/c‐Rel activation and DR5‐dependent manner. This study may shed light on a potential drug cocktail that may prove useful as anti‐cancer in an in vivo animal model. J. Cell. Physiol. 221: 378–386, 2009.