Stimulatory effects of lipoprotein(a) and low-density lipoprotein on human umbilical vein endothelial cell migration and proliferation are partially mediated by fibroblast growth factor-2

Proteins Found in the Triple-Negative Breast Cancer Secretome and Their Therapeutic Potential

The cancer secretome comprises factors secreted by tumors, including cytokines, growth factors, proteins from the extracellular matrix (ECM), proteases and protease inhibitors, membrane and extracellular vesicle proteins, peptide hormones, and metabolic proteins. Secreted proteins provide an avenue for communication with other tumor cells and stromal cells, and these in turn promote tumor growth and progression. Breast cancer is the most commonly diagnosed cancer in women in the US and worldwide. Triple-negative breast cancer (TNBC) is characterized by its aggressiveness and its lack of expression of the estrogen receptor (ER), progesterone receptor (PR), and HER2, making it unable to be treated with therapies targeting these protein markers, and leaving patients to rely on standard chemotherapy. In order to develop more effective therapies against TNBC, researchers are searching for targetable molecules specific to TNBC. Proteins in the TNBC secretome are involved in wide-ranging cancer-promoting processes, including tumor growth, angiogenesis, inflammation, the EMT, drug resistance, invasion, and development of the premetastatic niche. In this review, we catalog the currently known proteins in the secretome of TNBC tumors and correlate these secreted molecules with potential therapeutic opportunities to facilitate translational research.

Lipoprotein(a) as an Old and New Causal Risk Factor of Atherosclerotic Cardiovascular Disease

Lipoprotein(a) [Lp(a)], discovered in 1963, has been associated with atherosclerotic cardiovascular disease (ASCVD) independent of other traditional risk factors, including LDL cholesterol. Lp(a) is an apolipoprotein B (apoB)-containing lipoprotein, which contains an LDL-like particle. Unlike LDL, which is a primary therapeutic target to decrease ASCVD, current guidelines recommend measuring Lp(a) for risk assessments because there is no clear evidence demonstrating the clinical benefit of decreasing Lp(a) using classical drugs such as niacin. However, recent Mendelian randomization studies indicate that Lp(a) causally correlates with ASCVD. In addition, novel drugs, including PCSK9 inhibitors, as well as antisense oligonucleotide for apo(a), have exhibited efficacy in decreasing Lp(a) substantially, invigorating a discussion whether Lp(a) could be a novel therapeutic target for further ASCVD risk reduction. This review aims to provide current understanding, and future perspectives, of Lp(a), which is currently considered a mere biomarker but may emerge as a novel therapeutic target in future clinical settings.

High-throughput proteomic characterization of plasma rich in growth factors (PRGF-Endoret)-derived fibrin clot interactome

Plasma rich in growth factors (PRGF®-Endoret®) is an autologous technology that contains a set of proteins specifically addressed to wound healing and tissue regeneration. The scaffold formed by using this technology is a clot mainly composed of fibrin protein, forming a three-dimensional (3D) macroscopic network. This biomaterial is easily obtained by biotechnological means from blood and can be used in a range of situations to help wound healing and tissue regeneration. Although the main constituent of this clot is the fibrin scaffold, little is known about other proteins interacting in this clot that may act as adjuvants in the healing process. The aim of this study was to characterize the proteins enclosed by PRGF-Endoret scaffold, using a double-proteomic approach that combines 1D-SDS-PAGE approach followed by LC-MS/MS, and 2-DE followed by MALDI-TOF/TOF. The results presented here provide a description of the catalogue of key proteins in close contact with the fibrin scaffold. The obtained lists of proteins were grouped into families and networks according to gene ontology. Taken together, an enrichment of both proteins and protein families specifically involved in tissue regeneration and wound healing has been found.

Lipoprotein(a): Cellular Effects and Molecular Mechanisms

Lipoprotein(a) (Lp(a)) is an independent risk factor for the development of cardiovascular disease (CVD). Indeed, individuals with plasma concentrations >20 mg/dL carry a 2-fold increased risk of developing CVD, accounting for ~25% of the population. Circulating levels of Lp(a) are remarkably resistant to common lipid lowering therapies, and there are currently no robust treatments available for reduction of Lp(a) apart from plasma apheresis, which is costly and labour intensive. The Lp(a) molecule is composed of two parts, an LDL/apoB-100 core and a unique glycoprotein, apolipoprotein(a) (apo(a)), both of which can interact with components of the coagulation cascade, inflammatory pathways, and cells of the blood vessel wall (smooth muscle cells (SMC) and endothelial cells (EC)). Therefore, it is of key importance to determine the molecular pathways by which Lp(a) exerts its influence on the vascular system in order to design therapeutics to target its cellular effects. This paper will summarise the role of Lp(a) in modulating cell behaviour in all aspects of the vascular system including platelets, monocytes, SMC, and EC.

Apolipoprotein(a) stimulates vascular endothelial cell growth and migration and signals through integrin alphaVbeta3

Elevated plasma concentrations of Lp(a) [lipoprotein(a)] are an emerging risk factor for atherothrombotic disease. Apo(a) [apolipoprotein(a)], the unique glycoprotein component of Lp(a), contains tandem repeats of a plasminogen kringle (K) IV-like domain. In the light of recent studies suggesting that apo(a)/Lp(a) affects endothelial function, we evaluated the effects of apo(a)/Lp(a) on growth and migration of cultured HUVECs (human umbilical-vein endothelial cells). Two full-length r-apo(a) [recombinant apo(a)] variants (12K and 17K), as well as Lp(a), were able to stimulate HUVEC growth and migration to a comparable extent; 17K r-apo(a) also decreased the levels of total and active transforming growth factor-beta secreted by these cells. Using additional r-apo(a) variants corresponding to deletions and/or site-directed mutants of various kringle domains in the molecule, we were able to determine that the observed effects of full-length r-apo(a) on HUVECs were dependent on the presence of a functional lysine-binding site(s) in the apo(a) molecule. With respect to signalling events elicited by apo(a) in HUVECs, we found that 17K treatment of the cells increased the phosphorylation level of FAK (focal adhesion kinase) and MAPKs (mitogen-activated protein kinases), including ERK (extracellular-signal-regulated kinase), p38 and JNK (c-Jun N-terminal kinase). In addition, we showed that LM609, the function-blocking antibody to integrin alphaVbeta3, abrogated the effects of 17K r-apo(a) and Lp(a) on HUVECs. Taken together, the results of the present study suggest that the apo(a) component of Lp(a) signals through integrin alphaVbeta3 to activate endothelial cells.

Lipoprotein(a): an emerging cardiovascular risk factor

Lipoprotein(a) is a cholesterol-enriched lipoprotein, consisting of a covalent linkage joining the unique and highly polymorphic apolipoprotein(a) to apolipoprotein B100, the main protein moiety of low-density lipoproteins. Although the concentration of lipoprotein(a) in humans is mostly genetically determined, acquired disorders might influence synthesis and catabolism of the particle. Raised concentration of lipoprotein(a) has been acknowledged as a leading inherited risk factor for both premature and advanced atherosclerosis at different vascular sites. The strong structural homologies with plasminogen and low-density lipoproteins suggest that lipoprotein(a) might represent the ideal bridge between the fields of atherosclerosis and thrombosis in the pathogenesis of vascular occlusive disorders. Unfortunately, the exact mechanisms by which lipoprotein(a) promotes, accelerates, and complicates atherosclerosis are only partially understood. In some clinical settings, such as in patients at exceptionally low risk for cardiovascular disease, the potential regenerative and antineoplastic properties of lipoprotein(a) might paradoxically counterbalance its athero-thrombogenicity, as attested by the compatibility between raised plasma lipoprotein(a) levels and longevity.

Extracellular angio-associated migratory cell protein plays a positive role in angiogenesis and is regulated by astrocytes in coculture

The extracellular form of angio-associated migratory cell protein (AAMP), a recently discovered protein, plays a positive role in angiogenesis and can be regulated by astrocytes. Angiogenic activities are inhibited by an affinity-purified, polyclonal antibody generated to recombinant AAMP. Inhibition of endothelial cell tube formation was previously shown and now endothelial cell migration assays using this antibody show dose-dependent inhibition (75%) of endothelial cell migration. Also, antisense inhibition has been used to determine the effects of reducing total AAMP (extracellular and intracellular forms). An AAMP-specific antisense oligonucleotide that targets a region near its amino terminus, anti-MES, inhibits (45%) total AAMP production by bovine aortic endothelial cells (BAECs), compared to a negative control oligonucleotide. Paradoxically, comparable use of antisense-MES results in a 27% increase in BAEC motility. Decreased cellular production of total AAMP (via antisense) that results in an increase of endothelial migration contrasts with antibody inhibition of extracellular AAMP that decreases migration. This indicates compartment-specific roles for AAMP in angiogenesis. Transwell cocultures of human astrocytes and BAECs increase (53%) the amount of extracellular AAMP found associated with endothelial cells. Therefore, regulation of extracellular AAMP by astrocytes is hypothesized to aid in angiogenesis of the nervous system. Extracellular AAMP's positive role may be either as a promoter or as a permissive protein in this process.

Biochemical risk factors for cardiovascular disease in an aged male population: emerging vascular pathogens

The progressive increase of deaths and morbidity from cardiovascular disease (CVD) in most developed societies has led to the formulation of preventive strategies and application of several diagnostic guidelines. However, there is emerging evidence that most panels and algorithms are inadequate and require urgent revision and updating. Therefore, the aim of this study was the evaluation of a wide cardiovascular risk profile in elderly male patients with acute myocardial infarction (AMI) or peripheral occlusive disease (POD). The risk profile was assessed by measuring conventional serum lipid and lipoprotein levels and emerging parameters: lipoprotein(a) (Lp[a]), homocysteine (Hcy), and C-reactive protein (CRP). The concentration of triglycerides, Lp(a), Hcy and the total cholesterol/high-density lipoprotein (TC/HDL) ratio were significantly higher in both classes of patients than in a population of matched healthy controls and, similarly, patients with CVD displayed lower plasma values of HDL. No significant differences were observed for TC, low-density lipoprotein (LDL), and CRP. Patients with POD exhibited a marked atherogenic profile, as attested by substantially increased values of Hcy, Lp(a), triglycerides, and TC/HDL ratio. The frequency distributions of Lp(a) and Hcy concentrations were markedly shifted toward upper values in both classes of patients than in controls. In multivariate regression analysis, Lp(a) and Hcy were the best predictors for AMI, whereas Lp(a), Hcy, and the TC/HDL ratio were the best predictors for POD. Taken together, these data suggest that Lp(a) and Hcy excesses might exert a central role in the development of atherosclerotic disease in elderly male patients. Thereby, the inclusion of those tests, along with the TC/HDL ratio and other more conventional analyses in panels for the evaluation of the cardiovascular risk might be profitable in terms of effectual prevention.

Evaluation of genetic risk factors for silent brain infarction

BACKGROUND AND PURPOSE

Silent brain infarction (SBI) is often found with white matter hyperintensity. A recent genetic study on elderly twins indicated that the susceptibility to white matter hyperintensity was largely determined by genetic factors, implying the existence of genetic susceptibility for SBI as well. We therefore studied 3 genetic polymorphisms in SBI, the deletion/insertion polymorphism of angiotensin-converting enzyme (ACE) gene, the apolipoprotein(a) [apo(a)] size polymorphism, and the T677C polymorphism of methylenetetrahydrofolate reductase (MTHFR) gene, by a case-control study.

METHODS

By MRI, 147 subjects with SBI and 214 without cerebral infarctions (control group) were selected from participants of a health examination of the brain. Seventy-four patients with symptomatic subcortical infarction (SSI) from the same area were also included in the study. In addition to the control group, 2 more reference populations were recruited. Typing of the apo(a) size polymorphism was done by Western blotting with the use of an anti-apo(a) antibody. Genotypes of ACE and MTHFR were determined by polymerase chain reaction amplification of the genomic DNA and subsequent restriction enzyme digestion.

RESULTS

The ACE polymorphism was not associated with either SBI or SSI. In contrast, the small apo(a) was associated with both SSI and SBI. The MTHFR polymorphism was associated only with SSI. The association of MTHFR and apo(a) was greater in the younger subjects.

CONCLUSIONS

Among the 3 genetic polymorphisms studied, only the apo(a) size polymorphism is a risk factor for SBI.