Current Molecular Medicine (v.14, #4)

Multiple myeloma (MM) is a clonal neoplasm characterized by expansion of malignant plasma cellsin the bone marrow causing various complications including osteolytic lesions and impaired immune function. Ithas recently been reported that human myeloma cells express multiple Toll-like receptors (TLRs), and theiractivation-induced functional responses show heterogeneity among cell lines and patient samples. TLRs arecritical germ-line encoded molecules expressed in immune cells as well as in a variety of cancer cells. Inmultiple myeloma, they may induce cell growth and proliferation or promote cell death. In fact, our currentknowledge of Toll-like receptor function has gone beyond their main function as triggers of innate and adaptiveimmune responses. Considering the essential role of bone marrow microenvironment components in myelomatumor expansion, survival, invasion and drug resistance, TLR triggering may contribute to adhesion-induced orde novo drug resistance of MM cells. Future preclinical and clinical studies are needed to address if TLRs canbe exploited as novel therapeutic targets for MM.

The TP73 gene is a member of the TP53 family with high structural homology to p53 and capable oftransactivating p53 target genes. The TP73 gene locus which is highly conserved and complex, encodes fortwo classes of isoforms TAp73 (tumor suppressor isoforms containing the transactivation domain) and ΔNp73(oncogenic isoforms, truncated and lacking the transactivation domain) with opposing effects. The balancebetween TAp73 and ΔNp73 isoforms and their harmony with other members of the TP73 family regulatevarious cellular responses such as apoptosis, autophagy, proliferation, and differentiation. The transcriptionallyactive isoforms of p73 are capable of inducing apoptosis in cancer cells independent of p53 status. Unlike p53,p73 is rarely mutated in cancers, however, the ratio of ΔNp73:TAp73 is frequently up-regulated in manycarcinomas and is indicative of poor prognosis. Moreover, p73 is an important determinant of chemosensitivityand radiosensitivity, the two major treatment modalities for lymphoma. In the current review, we will provide anoverview of recent progress discussing the role of TP73 in cancer, specifically addressing its relevance tolymphomagenesis, progression, therapy resistance, and its potential as a novel therapeutic target.

Detection of Circulating Tumor Cells from Lung Cancer Patients in the Era of Targeted Therapy : Promises, Drawbacks and Pitfalls by V. Hofman, M. Ilie, E. Long, N. Guibert, E. Selva, K. Washetine, B. Mograbi, J. Mouroux, N. Venissac, J. Reverso-Meinietti, G. Milano, J. Mazieres, C.-H. Marquette, P. Paterlini-Brechot, P. Hofman (440-456).
Interest in biomarkers in the field of thoracic oncology is focused on the search for new robust testsfor diagnosis (in particular for screening), prognosis and theragnosis. These biomarkers can be detected intissues and/or cells, but also in biological fluids, mainly the blood. In this context, there is growing interest inthe detection of circulating tumor cells (CTCs) in the blood of lung cancer patients since CTC identification,enumeration and characterization may have a direct impact on diagnosis, prognosis and theragnosis in thedaily clinical practice. Many direct and indirect methods have been developed to detect and characterize CTCsin lung cancer patients. However, these different approaches still hold limitations and many of them havedemonstrated unequal sensitivity and specificity. Indeed, these methods hold advantages but also certaindisadvantages. Therefore, despite the promises, it is currently difficult and premature to apply this methodologyto the routine care of lung cancer patients. This situation is the consequence of the analysis of themethodological approaches for the detection and characterization of CTCs and of the results published to date.Finally, the advent of targeted cancer therapies in thoracic oncology has stimulated considerable interest innon-invasive detection of genomic alterations in tumors over time through the analysis of CTCs, an approachthat may help clinicians to optimize therapeutic strategies for lung cancer patients. We describe here the mainmethods for CTC detection, the advantages and limitations of these different approaches and the potentialusefulness and value of CTC characterization in the field of thoracic oncology.

Endothelial Remodelling and Intracellular Calcium Machinery by F. Moccia, F. Tanzi, L. Munaron (457-480).
Rather being an inert barrier between vessel lumen and surrounding tissues, vascular endotheliumplays a key role in the maintenance of cardiovascular homeostasis. The de-endothelialization of blood vesselsis regarded as the early event that results in the onset of severe vascular disorders, including atherosclerosis,acute myocardial infarction, brain stroke, and aortic aneurysm. Restoration of the endothelial lining may beaccomplished by the activation of neighbouring endothelial cells (ECs) freed by contact inhibition and bycirculating endothelial progenitor cells (EPCs). Intracellular Ca2+ signalling is essential to promote woundhealing: however, the molecular underpinnings of the Ca2+ response to injury are yet to be fully elucidated.Similarly, the components of the Ca2+ toolkit that drive EPC incorporation into denuded vessels are far frombeing fully elucidated. The present review will survey the current knowledge on the role of Ca2+ signalling inendothelial repair and in EPC activation. We propose that endothelial regeneration might be boosted byintraluminal release of specific Ca2+ channel agonists or by gene transfer strategies aiming to enhance theexpression of the most suitable Ca2+ channels at the wound site. In this view, connexin (Cx)channels/hemichannels and store-operated Ca2+ entry (SOCE) stand amid the most proper routes totherapeutically induce the regrowth of denuded vessels. Cx stimulation might trigger the proliferative andmigratory behaviour of ECs facing the lesion site, whereas activation of SOCE is likely to favour EPC homingto the wounded vessel.

Pleiotropic Effects of HDL: Towards New Therapeutic Areas for HDL-Targeted Interventions by S.C. Gordts, N. Singh, I. Muthuramu, B. De Geest (481-503).
Plasma levels of high density lipoprotein (HDL) cholesterol levels and of apolipoprotein A-I areinversely correlated with the incidence of coronary heart disease. According to the HDL hypothesis, raisingHDL cholesterol is expected to lead to a decrease of coronary heart disease risk. The stringent requirement forproving or refuting this hypothesis is that the causal pathway between the therapeutic intervention and a hardclinical end-point obligatory passes through HDL. The lack of positive clinical results in several recent HDLtrials should be interpreted in light of the poor HDL specificity of the drugs that were investigated in these trials.Nevertheless, the results of Mendelian randomization studies further raise the possibility that theepidemiological relationship between HDL cholesterol and coronary artery disease might reflect residualconfounding;HDL are circulating multimolecular platforms that exert divergent functions: reverse cholesterol transport, antiinflammatoryeffects, anti-oxidative effects, immunomodulatory effects, improved endothelial function,increased endothelial progenitor cell number and function, antithrombotic effects, and potentiation of insulinsecretion and improvement of insulin sensitivity. Pleiotropic effects of HDL might be translated in clinicallysignificant effects in strategically selected therapeutic areas that are not directly related to native coronaryartery disease. In this review, four new therapeutic areas for HDL-targeted diseases are presented: criticalillness, allograft vasculopathy and vein graft atherosclerosis, type 2 diabetes mellitus, and heart failure. Thestrategic selection of these therapeutic areas is not only based on specific functional properties of HDL but alsoon significant pre-clinical and clinical data that support this choice.

The Fgf family comprises 22 members with diverse functions in development, repair, metabolism,and neuronal activities. Fgf10 mediates biological responses by activating Fgf receptor 2b (Fgfr2b) withheparin/heparan sulfate in a paracrine manner. Fgf10 and Fgfr2b are expressed in mesenchymal and epithelialtissues, respectively. Fgf10 is an epithelial-mesenchymal signaling molecule. Fgf10 knockout mice showsevere phenotypes with complete truncation of the fore- and hindlimbs and die shortly after birth due toimpaired lung development, indicating that Fgf10 serves as an essential regulator of lung and limb formation.Fgf10 also has roles in the development of white adipose tissue, heart, liver, brain, kidney, cecum, ocularglands, thymus, inner ear, tongue, trachea, eye, stomach, prostate, salivary gland, mammary gland, andwhiskers. The diverse phenotypes of Fgf10 knockout mice are closely related to those of Fgfr2 knockout mice,suggesting that Fgf10 acts as a major ligand for Fgfr2b in mouse multi-organ development. Aplasia of lacrimaland salivary glands and lacrimo-auriculo-dento-digital syndrome are caused by Fgf10 mutations in humans.Variants in Fgf10 may be involved in an increased risk for limb deficiencies and cleft lip and palate. Patientswith Fgf10 haploinsufficiency have lung function parameters indicating chronic obstructive pulmonary disease.Fgf10 induces migration and invasion in pancreatic cancer cells. Fgf10 signaling may be involved in anincreased risk for breast cancer. Fgf10 also induces the differentiation of embryonic stem cells into a gut-likestructure, cardiomyocytes, and hepatocytes. These findings indicate the crucial roles of Fgf10 in development,disease, and regenerative medicine.

Role of Wnt Signaling in Tissue Fibrosis, Lessons from Skeletal Muscle and Kidney by P. Cisternas, C.P. Vio, N.C. Inestrosa (510-522).
Several studies have provided clear evidence of the importance of Wnt signaling in the function ofseveral tissues. Wnt signaling has been related to several cellular processes including pre-natal development,cell division, regeneration and stem cell generation. By contrast, deregulation of this pathway has beenassociated with several diseases such as cancer, Alzheimer's disease, diabetes and, in recent years, fibroticdiseases in tissues such as skeletal muscle and kidney. Fibrotic diseases are characterized by an increase inthe production and accumulation of extracellular matrix (ECM) components leading to the loss of tissuearchitecture and function. In a classical view, several molecules are related to the establishment of the fibroticcondition, including angiotensin II, transforming growth factorβ(TGF-β) and the connective tissue growthfactor (CTGF) and a crosstalk has been suggested between these signaling molecules and the Wnt pathway.Skeletal muscle fibrosis, the most common disease, is typical of muscle dystrophies, where deregulation of theregenerative process in postnatal muscle leads to fibrotic differentiation and eventually to the failure of skeletalmuscle. The fibrotic condition is also present in kidney pathologies such as polycystic kidney disease (PKD), inwhich fibrosis leads to a loss of tubule architecture and to a loss of function, which in almost all cases requireskidney surgery. A new actor in the pro-fibrotic effect of Wnt signaling in the kidney has been described, theprimary cilium, an organelle that plays an important role in the onset of fibrosis.The aim of this review is to discuss the pro-fibrotic effect of Wnt signaling in both skeletal muscle and kidney,and to try to understand how this pathway is associated with the TGF-β, CTGF and angiotensin II pro-fibroticpathway.

The epithelial-mesenchymal transition (EMT) of retinal pigment epithelium (RPE) cells plays a keyrole in proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR), which lead to the lossof vision. The Jagged/Notch pathway has been reported to be essential in EMT during embryonicdevelopment, fibrotic diseases and cancer metastasis. However, the function of Jagged/Notch signaling inEMT of RPE cells is unknown. Thus, we hypothesized that a crosstalk between Notch and transforming growthfactor β2 (TGF-β2) signaling could induce EMT in RPE cells, which subsequently contributes to PVR and PDR.Here, we demonstrate that Jagged-1/Notch pathway is involved in the TGF-β2-mediated EMT of human RPEcells. Blockade of Notch pathway with DAPT (a specific inhibitor of Notch receptor cleavage) and knockdownof Jagged-1 expression inhibited TGF-β2-induced EMT through regulating the expression of Snail, Slug andZEB1. Besides the canonical Smad signaling pathway, the noncanonical PI3K/Akt and MAPK pathway alsocontributed to TGF-β2-induced up-regulation of Jagged-1 in RPE cells. Overexpression of Jagged-1 couldmimic TGF-β2 induce EMT. Our data suggest that the Jagged-1/Notch signaling pathway plays a critical role inTGF-β2-induced EMT in human RPE cells, and may contribute to the development of PVR and PDR. Inhibitionof the Jagged/Notch signaling pathway, therefore, may have therapeutic value in the prevention and treatmentof PVR and PDR.

A Possible Role for Interleukin 37 in the Pathogenesis of Behcet's Disease by Z. Ye, C. Wang, A. Kijlstra, X. Zhou, P. Yang (535-542).
Interleukin 37 has been found to play a significant regulatory role in the innate immune response. Itis not yet known whether IL-37 has also been involved in the development of Behcet's disease (BD), a chronicsystemic inflammatory disease. To examine the role of IL-37 in the pathogenesis of BD, a number ofexperiments were performed. IL-37 expression in peripheral blood mononuclear cells (PBMCs) from BDpatients and normal controls was measured by RT-PCR and flow cytometry. Monocyte-derived Dendritic Cells(DCs) were cultured with or without IL-37 and levels of cytokines in the culture supernatants were measured byELISA. The DC surface markers, reactive oxygen species (ROS) production and mitogen-activated proteinkinase (MAPK) activation were measured by flow cytometry. The effect of IL-37-treated DCs on thedevelopment of CD4+ T cells was measured by ELISA and flow cytometry. The results show that both IL-37mRNA level and protein expression were significantly decreased in PBMCs from active BD patients comparedto normal controls. DCs stimulated with rIL-37 showed a decreased expression of IL-6, IL-1β and TNF-α, and ahigher production of IL-27. rIL-37 significantly inhibited the production of ROS by DCs and reduced theactivation of ERK1/2, JNK and P38 MAPK in DCs. rIL-37-treated DCs remarkably inhibited Th17 and Th1 cellresponses as compared to control DCs. rIL-37 did not affect the expression of DC surface markers (CD40,CD86, CD80 and HLA-DR) or IL-10 production by DCs. We conclude that a decreased IL-37 expression inactive BD patients may trigger the production of pro-inflammatory cytokines and ROS in association withactivation of Th1 and Th17 cells by DCs.

G protein-coupled receptor 124 (GPR124; also called tumor endothelial marker 5, TEM5) is highlyexpressed in tumor vasculature. While recent studies have revealed a role in vasculogenesis, evidence forGPR124 function in tumor angiogenesis is lacking. Here, we demonstrate that GPR124 is required for VEGFinducedtumor angiogenesis. GPR124 silencing in human endothelial cells inhibited mouse xenograft tumorangiogenic vessel formation and tumor growth. GPR124 regulated VEGF-induced tumor angiogenic processesin vitro including cell-cell interaction, permeability, migration, invasion, and tube formation. Therefore, GPR124plays a key role in VEGF-induced tumor angiogenesis.

Objectives: Celastrol, a quinone methide triterpenoid, could induce apoptosis in pancreatic cancercells. The purpose of this study is to determine whether there is protective autophagy after celastrol treatmentin pancreatic cancer cells and the synergistic effects of celastrol and 3-MA in vitro and in vivo.Methods: The cells viability was measured using MTT assays. Degree of apoptosis and amount of autophagicvacuoles were measured by flow cytometry. Immunofluorescence was adapted to monitor the localization ofautophagic protein LC3-II. Expression of LC3-II, cleaved caspase-3, Bax and bcl-2 was detected byimmunoblot. Autophagosomes were observed by electron microscopy. The synergistic effect of celastrol and 3-MA in vivo was studied in the MiaPaCa-2 xenograft tumor model.Results: Celastrol increased the level of autophagy in pancreatic cancer cells. Furthermore in vitro, wheninhibiting the autophagy with 3-MA, the level of celastrol-induced apoptosis elevated; after upgradingautophagy by starvation, the level of celastrol-induced apoptosis descended. 3-MA enhanced celastrol-inducedapoptosis and inhibitory effect on tumor growth in vivo.Conclusions: In pancreatic cancer, celastrol treatment increased the level of autophagy to protect cancer cellsagainst apoptosis. Autophagy inhibitor 3-MA could improve the therapeutic effect of celastrol in vitro and invivo.