Regulation of osteoprotegerin pro- or anti-tumoral activity by bone tumor microenvironment.

Tumor development in bone is often associated with fractures, bone loss and bone pain, and improvement is still needed in therapeutic approaches. Bone tumors are related to the existence of a vicious cycle between bone resorption and tumor proliferation in which the molecular triad osteoprotegerin (OPG)/receptor activator of NF-kappaB (RANK)/RANK ligand (RANKL) plays a pivotal role. RANKL, a member of the TNF superfamily, is one of the main inducers of bone resorption. Its soluble receptor OPG represents a promising therapeutic candidate as it prevents bone lesions and inhibits associated tumor growth. However, its therapeutic use in bone tumors remains controversial due to its ability to bind and inhibit another member of the TNF superfamily, TNF related apoptosis inducing ligand (TRAIL), which is a potent inducer of tumor cell apoptosis. Through its heparin binding domain, OPG is also able to bind proteoglycans present in the bone matrix. This paper is an overview of the involvement of the micro-environment, as represented by the balance of RANKL/TRAIL and the presence of proteoglycans in the regulation of OPG biological activity in bone tumors.

Evaluation of vasospasm secondary to subarachnoid hemorrhage with technetium-99m-hexamethyl-propyleneamine oxime (HM-PAO) tomoscintigraphy.

Vasospasm of intracranial vessels is difficult to diagnose on clinical ground alone. Still, a clear diagnosis is important because it can impact on surgical timing; and also because it can help evaluate new treatments. Fifteen patients with sub-arachnoid hemorrhage secondary to aneurysm rupture were submitted to a total of 26 tomographic technetium-99m-hexamethyl-propyleneamine oxime (99mTc-HM-PAO) brain examinations that were correlated with temporally close (generally less than 24 hr) angiography or transmission computed tomography (TCT). Nine of 10 angiographically confirmed episodes of spasm and 6 of 6 infarcts seen on angiography or TCT were correctly diagnosed with 99mTc-HM-PAO. One normal scintigraphic exam was angiographically doubtful, one positive 99mTc-HM-PAO study was normal on angiography (sub-radiologic spasm?), one technically poor scintigraphy was positive for spasm on angiograms, and eight exams were normal for spasm with all modalities. We had agreement between tests in 23 of 26 series of exams (88%) obtained in 15 patients. We think that 99mTc-HM-PAO tomography should be useful for the evaluation of patients with suspected vasospasm.

Spontaneous resolution of severe right ventricular dysfunction in right ventricular infarction: documentation by radionuclide studies.

A case of inferior myocardial infarction complicated by severe arrhythmias and right heart failure is presented. Radionuclide studies performed near the acute phase and one month later illustrate the reversibility of right heart dysfunction caused by infarction. Signs of right ventricular involvement in acute inferior myocardial infarction are noted in about 40% of cardiac blood-pool studies: right ventricular dilatation with a significantly decreased ejection fraction, and ventricular wall motion abnormalities. Follow-up studies in the recovery period show good recovery of right ventricular function.

Dipyridamole testing compared to exercise stress for thallium-201 imaging in patients with left bundle branch block.

Because of numerous reports of false positive results with thallium-201 (Tl-201) stress testing in patients with left bundle branch block, the authors decided to evaluate another mode of coronary vasodilatation, dipyridamole, for the diagnosis of coronary atheromatosis. Nine patients were prospectively studied with stress and dipyridamole Tl-201 scintigraphy; both tests were performed within three to 79 days of one another. Five of the patients also had coronary angiograms (four within one year, one five years earlier). Four of the patients had normal results with both tests (two normal angiograms, two not performed); two had reversible septal defects with stress-induced coronary vasodilatation but normal dipyridamole studies (only one had an angiogram, which was normal); one patient had a fully reversible septal defect with stress and a fixed defect with dipyridamole (normal angiogram); one had a partially reversible septal stress defect which was fixed with dipyridamole; and one had a normal stress study but a reversible septal defect with dipyridamole (an angiogram performed five years earlier showed 30 to 40% stenosis of the anterior descending artery). Because it seems that dipyridamole produces fewer false positive results, it should be used instead of stress testing to induce coronary vasodilatation in patients with left bundle branch block.

Lyn tyrosine kinase regulates androgen receptor expression and activity in castrate-resistant prostate cancer.

Castrate-resistant prostate cancer (CRPC) progression is a complex process by which prostate cells acquire the ability to survive and proliferate in the absence or under very low levels of androgens. Most CRPC tumors continue to express the androgen receptor (AR) as well as androgen-responsive genes owing to reactivation of AR. Protein tyrosine kinases have been implicated in supporting AR activation under castrate conditions. Here we report that Lyn tyrosine kinase expression is upregulated in CRPC human specimens compared with hormone naive or normal tissue. Lyn overexpression enhanced AR transcriptional activity both in vitro and in vivo and accelerated CRPC. Reciprocally, specific targeting of Lyn resulted in a decrease of AR transcriptional activity in vitro and in vivo and prolonged time to castration. Mechanistically, we found that targeting Lyn kinase induces AR dissociation from the molecular chaperone Hsp90, leading to its ubiquitination and proteasomal degradation. This work indicates a novel mechanism of regulation of AR stability and transcriptional activity by Lyn and justifies further investigation of the Lyn tyrosine kinase as a therapeutic target for the treatment of CRPC.Oncogenesis (2014) 3, e115; doi:10.1038/oncsis.2014.30; published online 18 August 2014.

Mapping cyclosporine-induced changes in protein secretion by renal cells using stable isotope labeling with amino acids in cell culture (SILAC).

Nephrotoxicity is an adverse event that strongly limits the use of the immunosuppressant cyclosporine in solid organ transplantation and the precise molecular mechanisms underlying this toxicity remain unclear. MS-based proteomic analysis of the secretome of HEK-293 renal cells exposed to cyclosporine was performed to identify changes in protein secretion, as a first step to discover potential biomarkers of such nephrotoxicity. To detect and quantify the perturbed proteins in the culture medium we used SILAC and nano-scale liquid chromatography followed by MALDI-TOF/TOF mass spectrometry. Among 106 proteins identified, 80 were quantified in both forward/reverse SILAC experiments and quantitative proteomic analysis revealed altered levels of expression for 24 secreted proteins. These included the down-regulation of a number of extracellular matrix/cell adhesion components, and the up-regulation of secreted cyclophilins A and B, macrophage inhibition factor and phosphatidylethanolamine-binding protein 1. These changes in protein secretion were not prevented by co-incubation with the antioxidant N-acetylcysteine, suggesting that they were not triggered by cyclosporine-induced oxidative stress. The results from the present study provide important new knowledge to gain insights into the molecular mechanisms of cyclosporine-related toxicity. Some of the proteins identified here should be tested as potential biomarkers of cyclosporine nephrotoxicity in subsequent clinical studies.

Quantitative proteomic analysis of cyclosporine-induced toxicity in a human kidney cell line and comparison with tacrolimus.

The calcineurin-inhibitors (CNIs) cyclosporine (CsA) and tacrolimus (TAC) remain the pillars of modern immunosuppression regimens used in solid organ transplantation. Nephrotoxicity is an adverse effect that limits their successful use. The precise molecular mechanisms underlying this nephrotoxicity remain unclear. Using SILAC together with LC-MALDI-TOF/TOF, we investigated the CNIs-induced proteomic perturbations in renal cells. Among the 495 proteins quantifiable in both forward and reverse SILAC, 69 displayed CsA-induced perturbations: proteins involved in ER-stress/protein folding, apoptosis, metabolism/transport or cytoskeleton pathways were up-regulated, while cyclophilin B as well as nuclear and RNA-processing proteins were down-regulated. Co-administration of CsA with the antioxidant N-acetylcysteine significantly decreased lipid peroxidation and also partially corrected the CsA-induced unfolded protein response. TAC toxicity profile was apparently different from that of CsA, especially without perturbation of cyclophilins A and B, up-regulation of ER-chaperones nor down-regulation of a number of nuclear proteins. These results provide a new insight and are consistent with recent data regarding the molecular mechanisms of CNIs-induced nephrotoxicity. Our findings offer new directions for future research aiming to identify specific biomarkers of CsA nephrotoxicity.

RANKL, RANK, osteoprotegerin: key partners of osteoimmunology and vascular diseases.

1997 saw the identification of a novel set of proteins within the tumor necrosis factor (TNF)/TNF receptor families that are required for the control of bone remodeling. Therefore, these receptors, receptor activator of nuclear factor kappa B (RANK), osteoprotegerin (OPG) and their ligand RANK ligand (RANKL) became the critical molecular triad controlling osteoclastogenesis and pathophysiologic bone remodeling. However, the establishment of the corresponding knock-out and transgenic mice revealed unexpected results, most particularly, the involvement of these factors in the vascular system and immunity. Thus, the OPG/RANK/RANKL molecular triad appears to be associated with vascular calcifications and plays a pivotal function in the development of the immune system through dendritic cells. OPG/RANK/RANKL thus constitute a molecular bridge spanning bone metabolism, vascular biology and immunity. This review summarizes recent knowledge of OPG/RANK/RANKL interactions and activities as well as the current evidence for their participation in osteoimmunology and vascular diseases. In fine, the targeting of the OPG/RANK/RANKL axis as novel therapeutic approaches will be discussed.

[Hepatobiliary scintigraphy using 99m Tc-DISIDA and obstructive cholangiopathy in children]. / Scintigraphie hépato-biliaire au disida-99mTc et cholangiopathies obstructives infantiles.

Technetium 99m-labeled diisopropyl iminodiacetic acid (99m Tc-DISIDA) hepatobiliary scintigraphy of 26 patients with pathologically proven infantile obstructive cholangiopathy are retrospectively studied according to two types of criteria. Those of type 1 consider 1) hepatocyte clearance 2) hepatobiliary transit time and 3) visualisation of intestinal activity. For biliary atresia, sensitivity of 88.2%, specificity of 88.9%, positive predictive value of 93.8% and negative predictive value of 80.0% were obtained. For neonatal hepatitis, those parameters were 57.1%, 94.7%, 80.0% and 85.7% respectively. Criteria of type 2 identify only biliary atresia. They consider 1) presence or absence of intestinal radioactivity through 24 hours and 2) birth weight. Sensitivity, specificity, positive and negative predictive values were 88.2%, 88.9%, 93.8% and 80.0% respectively. Even if all these values are inferior to many reported in literature, we consider that the two types of criteria are relatively sensitive and specific to detect biliary atresia. Even through there are a few false negatives, biliary scintigraphy does remain one of the most important diagnostic tests in the context of biliary atresia.