TRAIL, caspases and maturation of normal and leukemic myeloid precursors

Determination of normal expression patterns of CD86, CD210a, CD261, CD262, CD264, CD358, and CD361 in peripheral blood and bone marrow cells by flow cytometry

In 2010, new monoclonal antibodies were submitted to the 9th International Workshop on Human Leukocyte Differentiation Antigens, and there are few studies demonstrating normal expression patterns of these markers. Thus, the objective of this study was to determine the normal patterns of cell expression of CD86, CD210a, CD261, CD262, CD264, CD358, and CD361 in peripheral blood (PB) and bone marrow (BM) samples by flow cytometry. In the present study, CD86 was expressed only in monocytes and B lymphocytes in PB and in monocytes and plasma cells in BM. Regarding CD210a expression, in PB samples, monocytes and NK cells showed weak expression, while neutrophils, B and T lymphocytes, and basophils showed weak and partial expression. In BM samples, expression of CD210a was observed in eosinophils, monocytes, and B and T/NK lymphocytes. Weak expression of CD210a was also observed in neutrophilic cells and plasma cells. All B cell maturation stages had weak expression of CD210a except for immature B cells, which did not express this marker. In the present study, no cell type in PB samples showed positivity for CD261 and, in BM samples, there was very weak expression in neutrophilic series, monocytes, and B lymphocytes. Conversely, plasma cells showed positivity for CD261 with a homogeneous expression. For CD262, there was weak expression in monocytes, neutrophils, and B lymphocytes in PB samples and weak expression in monocytes, B lymphocytes, and plasma cells in BM samples. The evaluation of CD264 showed very weak expression in B cells in PB samples and no expression in BM cells. Very weak expression of CD358 was observed in neutrophils, monocytes, and B lymphocytes in PB and BM samples. In addition, in BM samples, plasma cells and T lymphocytes showed weak expression of CD358. In relation to the maturation stages of B cells, there was weak expression in pro-B cel, pre-B cell, and mature B cell. In the present study, it was possible to observe expression of CD361 in all cell types analyzed in PB and BM samples. The analyzed markers presented varied profiles of expression and, in some cases, these profiles were different from those observed in other studies. Further studies are needed to evaluate these molecules, mainly in relation to a possible application in the diagnosis of hematological malignancies or as new therapeutic targets for the treatment of hematological neoplasms or autoimmune diseases.

Association of serum TRAIL levels with atherosclerosis in patients with type 2 diabetes mellitus

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) was originally isolated as an inducer of apoptosis. Recent cross-sectional and prospective studies suggest an inverse association of serum TRAIL levels with the severity of coronary artery disease (CAD) and with an adverse outcome in patients with CAD or heart failure. However, it is unknown whether TRAIL can inversely reflect the progression of atherosclerosis from its early stage. We therefore examined the association between TRAIL measured by ELISA and intima-media thickness (IMT) in carotid and femoral arteries evaluated by ultrasonography as a surrogate marker of atherosclerosis in 416 type 2 diabetic patients without any symptoms of CAD and heart failure. Concurrently, the existence of calcified plaque (CP) was examined. There was no significant association between TRAIL and carotid IMT (ρ=-0.096, p=0.052) or femoral IMT (ρ=-0.025, p=0.610), although TRAIL was associated with carotid IMT in a subset of patients with macrovascular diseases (ρ=-0.174, p=0.034). No difference in TRAIL levels was found between two groups with or without CP. TRAIL may not be a good candidate as a biomarker to evaluate early-stage atherosclerotic lesions.

hPEBP4 resists TRAIL-induced apoptosis of human prostate cancer cells by activating Akt and deactivating ERK1/2 pathways

The treatment options available for prostate cancer are limited because of its resistance to therapeutic agents. Thus, a better understanding of the underlying mechanisms of the resistance of prostate cancer will facilitate the discovery of more efficient treatment protocols. Human phosphatidylethanolamine-binding protein 4 (hPEBP4) is recently identified by us as an anti-apoptotic molecule and a potential candidate target for breast cancer treatment. Here we found the expression levels of hPEBP4 were positively correlated with the severity of clinical prostate cancer. Furthermore, hPEBP4 was not expressed in TRAIL-sensitive DU145 prostate cancer cells, but was highly expressed in TRAIL-resistant LNCaP cells, which show highly activated Akt. Interestingly, hPEBP4 overexpression in TRAIL-sensitive DU145 cells promoted Akt activation but inhibited ERK1/2 activation. The hPEBP4-overexpressing DU145 cells became resistant to TRAIL-induced apoptosis consequently, which could be reversed by PI3K inhibitors. In contrast, silencing of hPEBP4 in TRAIL-resistant LNCaP cells inhibited Akt activation but increased ERK1/2 activation, resulting in their sensitivity to TRAIL-induced apoptosis that was restored by the MEK1 inhibitor. Therefore, hPEBP4 expression in prostate cancer can activate Akt and deactivate ERK1/2 signaling, leading to TRAIL resistance. We also demonstrated that hPEBP4-mediated resistance to TRAIL-induced apoptosis occurred downstream of caspase-8 and at the level of BID cleavage via the regulation of Akt and ERK pathways, and that hPEBP4-regulated ERK deactivation was upstream of Akt activation in prostate cancer cells. Considering that hPEBP4 confers cellular resistance to TRAIL-induced apoptosis and is abundantly expressed in poorly differentiated prostate cancer, silencing of hPEBP4 suggests a promising approach for prostate cancer treatment.