Sarcoplasmic reticulum calcium ATPase (SERCA) proteolysis by matrix metalloproteinase-2 contributes to vascular dysfunction in early hypertension.

AIMS: Hypertension is associated with an increased activity of matrix metalloproteinase (MMP)-2 in the vasculature, which, in turn, proteolyzes extra- and intracellular proteins that lead to vascular dysfunction. The activity of sarcoplasmic reticulum calcium ATPase (SERCA) is decreased in the aortas of hypertensive rats. Increased activity of MMP-2 proteolyzed SERCA in rat heart during ischemia and reperfusion injury, thus impairing cardiac function. Therefore, we examined whether increased activity of MMP-2 in early hypertension contributes to proteolyze SERCA in the aortas, thus leading to maladaptive vascular remodeling and dysfunction. MAIN METHODS: Male Sprague-Dawley rats were submitted to two kidney-one clip (2K-1C) or Sham surgery and treated with doxycycline. Systolic blood pressure (SBP) was assessed by tail-cuff plethysmography. After 7 days, aortas were collected for zymography assays, Western blot to SERCA, ATPase activity assay, vascular reactivity, Ki-67 immunofluorescence and hematoxylin/eosin stain. KEY FINDINGS: SBP was increased in 2K-1C rats and doxycycline did not reduce it, but decreased MMP-2 activity and prevented SERCA proteolysis in aortas. Cross sectional area, media to lumen ratio and Ki-67 were all increased in the aortas of hypertensive rats and doxycycline decreased Ki-67. In 2K-1C rats, arterial relaxation to acetylcholine was impaired and doxycycline ameliorated it. SIGNIFICANCE: doxycycline reduced MMP-2 activity in aortas of 2K-1C rats and prevented proteolysis of SERCA and its dysfunction, thus ameliorating hypertension-induced vascular dysfunction.

NONO2P, a novel nitric oxide donor, causes vasorelaxation through NO/sGC/PKG pathway, K+ channels opening and SERCA activation.

BACKGROUND & AIMS: The treatment of cardiovascular diseases (CVD) could greatly benefit from using nitric oxide (NO) donors. This study aimed to investigate the mechanisms of action of NONO2P that contribute to the observed responses in the mesenteric artery. The hypothesis was that NONO2P would have similar pharmacological actions to sodium nitroprusside (SNP) and NO. METHODS: Male Wistar rats were euthanized to isolate the superior mesenteric artery for isometric tension recordings. NO levels were measured using the DAF-FM/DA dye, and cyclic guanosine monophosphate (cGMP) levels were determined using a cGMP-ELISA Kit. RESULTS: NONO2P presented a similar maximum efficacy to SNP. The free radical of NO (NO•) scavengers (PTIO; 100 µM and hydroxocobalamin; 30 µM) and nitroxyl anion (NO-) scavenger (L-cysteine; 3 mM) decreased relaxations promoted by NONO2P. The presence of the specific soluble guanylyl cyclase (sGC) inhibitor (ODQ; 10 µM) nearly abolished the vasorelaxation. The cGMP-dependent protein kinase (PKG) inhibition (KT5823; 1 µM) attenuated the NONO2P relaxant effect. The vasorelaxant response was significantly attenuated by blocking inward rectifying K+ channels (Kir), voltage-operated K+ channels (KV), and large conductance Ca2+-activated K+ channels (BKCa). NONO2P-induced relaxation was attenuated by cyclopiazonic acid (10 µM), indicating that sarcoplasmic reticulum Ca2+-ATPase (SERCA) activation is involved in this relaxation. Moreover, NONO2P increased NO levels in endothelial cells and cGMP production. CONCLUSIONS: NONO2P induces vasorelaxation with the same magnitude as SNP, releasing NO• and NO-. Its vasorelaxant effect involves sGC, PKG, K+ channels opening, and SERCA activation, suggesting its potential as a therapeutic option for CVD.

A Single-Short Partial Reprogramming of the Endothelial Cells decreases Blood Pressure via attenuation of EndMT in Hypertensive Mice.

Background: Small artery remodeling and endothelial dysfunction are hallmarks of hypertension. Growing evidence supports a likely causal association between cardiovascular diseases and the presence of endothelial-to-mesenchymal transition (EndMT), a cellular transdifferentiation process in which endothelial cells (ECs) partially lose their identity and acquire additional mesenchymal phenotypes. EC reprogramming represents an innovative strategy in regenerative medicine to prevent deleterious effects induced by cardiovascular diseases. Methods: Using a partial reprogramming of ECs, via overexpression of Oct-3/4, Sox-2, and Klf-4 (OSK) transcription factors, we aimed to bring ECs back to a youthful phenotype in hypertensive mice. Primary ECs were infected with lentiviral vectors (LV) containing the specific EC marker cadherin 5 (Cdh5) and the fluorescent reporter enhanced green fluorescence protein (EGFP) with empty vector (LVCO) or with OSK (LV-OSK). Confocal microscopy and western blotting analysis were used to confirm the OSK overexpression. Cellular migration, senescence, and apoptosis were evaluated. Human aortic ECs (HAoECs) from male and female normotensive and hypertensive patients were analyzed after OSK or control treatments for their endothelial nitric oxide synthase (eNOS) levels, nitric oxide (NO), and genetic profile. Male and female normotensive (BPN/3J) and hypertensive (BPH/2J) mice were treated with an intravenous (i.v.) injection of LVCO or LV-OSK and evaluated 10 days post-infection. The blood pressure, cardiac function, vascular reactivity of small arteries, in vivo EGFP signal and EndMT inhibition were analyzed. Results: OSK overexpression induced partial EC reprogramming in vitro , and these cells showed endothelial progenitor cell (EPC)-like features with lower migratory capability. OSK treatment of hypertensive BPH/2J mice normalized blood pressure and resistance arteries hypercontractility, via the attenuation of EndMT and elastin breaks. EGFP signal was detected in vivo in the prefrontal cortex of both BPN/3J and BPH/2J-treated mice, but OSK induced angiogenesis only in male BPN/3J mice. OSK-treated human ECs from hypertensive patients showed high eNOS activation and NO production, with low ROS formation. Single-cell RNA analysis showed that OSK alleviated EC senescence and EndMT, restoring their phenotypes in human ECs from hypertensive patients. Conclusion: Overall, these data indicate that OSK treatment and EC reprogramming can decrease blood pressure and reverse hypertension-induced vascular damage.

The hydrogen sulfide donor 4-carboxyphenyl-isothiocyanate decreases blood pressure and promotes cardioprotective effect through reduction of oxidative stress and nuclear factor kappa B/matrix metalloproteinase (MMP)-2 axis in hypertension.

AIMS: Our aim was to evaluate whether the hydrogen sulfide (H2S) donor, 4-carboxyphenyl-isothiocyanate (4-CPI), exerts cardioprotective effect in the two kidney- one clip (2K-1C) rats through oxidative stress and MMP-2 activity attenuation and compare it with the classical H2S donor, Sodium Hydrosulfide (NaHS). MATERIALS AND METHODS: Renovascular hypertension (two kidneys-one clip; 2K-1C) was surgically induced in male Wistar rats. After two weeks, normotensive (2K) and hypertensive rats were intraperitoneally treated with vehicle (0.6 % dimethyl sulfoxide), NaHS (0.24 mg/Kg/day) or with 4-CPI (0.24 mg/Kg/day), for more 4 weeks. Systolic blood pressure (SBP) was evaluated weekly by tail-cuff plethysmography. Heart function was assessed by using the Millar catheter. Cardiac hypertrophy and fibrosis were evaluated by hematoxylin and eosin, and Picrosirius Red staining, respectively. The H2S was analyzed using WSP-1 fluorimetry and the cardiac oxidative stress was measured by lucigenin chemiluminescence and Amplex Red. MMP-2 activity was measured by in-gel gelatin or in situ zymography assays. Nox1, gp91phox, MMP-2 and the phospho-p65 subunit (Serine 279) nuclear factor kappa B (NF-κB) levels were evaluated by Western blotting. KEY FINDINGS: 4-CPI reduced blood pressure in hypertensive rats, decreased cardiac remodeling and promoted cardioprotection through the enhancement of cardiac H2S levels. An attenuation of oxidative stress, with inactivation of the p65-NF-κB/MMP-2 axis was similarly observed after NaHS or 4-CPI treatment in 2K-1C hypertension. SIGNIFICANCE: H2S is a mediator that promotes cardioprotective effects and decreases blood pressure, and 4-CPI seems to be a good candidate to reverse the maladaptive remodeling and cardiac dysfunction in renovascular hypertension.

Vascular dysfunction occurs prior to the onset of amyloid pathology and Aß plaque deposits colocalize with endothelial cells in the hippocampus of female APPswe/PSEN1dE9 mice.

Increasing evidence shows that cardiovascular diseases (CVDs) are associated with an increased risk of cognitive impairment and Alzheimer's diseases (AD). It is unknown whether systemic vascular dysfunction occurs prior to the development of AD, if this occurs in a sex-dependent manner, and whether endothelial cells play a role in the deposition of amyloid beta (Aß) peptides. We hypothesized that vascular dysfunction occurs prior to the onset of amyloid pathology, thus escalating its progression. Furthermore, endothelial cells from female mice will present with an exacerbated formation of Aß peptides due to an exacerbated pressure pulsatility. To test this hypothesis, we used a double transgenic mouse model of early-onset AD (APPswe/PSEN1dE9). We evaluated hippocampus-dependent recognition memory and the cardiovascular function by echocardiography and direct measurements of blood pressure through carotid artery catheterization. Vascular function was evaluated in resistance arteries, morphometric parameters in the aortas, and immunofluorescence in the hippocampus and aortas. We observed that endothelial dysfunction occurred prior to the onset of amyloid pathology irrespective of sex. However, during the onset of amyloid pathology, only female APP/PS1 mice had vascular stiffness in the aorta. There was elevated Aß deposition which colocalized with endothelial cells in the hippocampus from female APP/PS1 mice. Overall, these data showed that vascular abnormalities may be an early marker, and potential mediator of AD, but exacerbated aortic stiffness and pressure pulsatility after the onset of amyloid pathology may be associated with a greater burden of Aß formation in hippocampal endothelial cells from female but not male APP/PS1 mice.

The O-GlcNAc dichotomy: when does adaptation become pathological?

O-Linked attachment of ß-N-acetylglucosamine (O-GlcNAc) on serine and threonine residues of nuclear, cytoplasmic, and mitochondrial proteins is a highly dynamic and ubiquitous post-translational modification that impacts the function, activity, subcellular localization, and stability of target proteins. Physiologically, acute O-GlcNAcylation serves primarily to modulate cellular signaling and transcription regulatory pathways in response to nutrients and stress. To date, thousands of proteins have been revealed to be O-GlcNAcylated and this number continues to grow as the technology for the detection of O-GlcNAc improves. The attachment of a single O-GlcNAc is catalyzed by the enzyme O-GlcNAc transferase (OGT), and their removal is catalyzed by O-GlcNAcase (OGA). O-GlcNAcylation is regulated by the metabolism of glucose via the hexosamine biosynthesis pathway, and the metabolic abnormalities associated with pathophysiological conditions are all associated with increased flux through this pathway and elevate O-GlcNAc levels. While chronic O-GlcNAcylation is well associated with cardiovascular dysfunction, only until recently, and with genetically modified animals, has O-GlcNAcylation as a contributing mechanism of cardiovascular disease emerged. This review will address and critically evaluate the current literature on the role of O-GlcNAcylation in vascular physiology, with a view that this pathway can offer novel targets for the treatment and prevention of cardiovascular diseases.

Reprogramming endothelial and vascular smooth muscle cells to prevent and treat hypertension.

The major pathophysiological characteristic of hypertension is the occurrence of small artery remodeling and endothelial dysfunction. There is also solid evidence showing that microcirculation abnormalities occur prior to the onset of hypertension. However, the mechanism(s) that trigger these changes prior to the elevation of blood pressure are unknown, and this may limit our ability to identify the cause of this disease and effectively treat it. In hypertension, as with aging, the vasculature becomes less susceptible to repair. One of the reasons is because endothelial cells start to deteriorate and present with exacerbated endothelial-to-mesenchymal transition (EndMT). Likewise, vascular smooth muscle cells (VSMC) also dedifferentiate into a synthetic phenotype, whereby they start to produce and secrete extracellular vesicles with a high migration and proliferation capacity for repairing vascular injury. Uncontrolled EndMT and/or VSMC phenotype switching contributes to vascular diseases, but the initial trigger for these conditions is unidentified. Importantly, EndMT and synthetic VSMC exhibit plasticity and can return to adopt an endothelial cell-like fate and present contractile phenotype again, respectively. Therefore, in this hypothesis we will take advantage of this plasticity, and we propose to manipulate this fate by inducing partial cellular reprogramming without passing through the pluripotent state. Specifically, we suggest that activation of the three master transcription factors, Oct-4, Sox-2, and Klf-4 (collectively termed OSK) will reprogram endothelial cells and prevent and reduce EndMT and VSMC synthetic phenotype. It was recently shown that activation of OSK was able to restore lost vision in old mice, and cancer risk was reduced by excluding c-Myc. Therefore, OSK treatment could provide new possibilities for vascular rejuvenation and treatment of hypertension.

Type I collagen proteolysis by matrix metalloproteinase-2 contributes to focal adhesion kinase activation and vascular smooth muscle cell proliferation in the aorta in early hypertension.

INTRODUCTION: Increased matrix metalloproteinase (MMP)-2 activity contributes to increase vascular smooth muscle cell (VSMC) proliferation in the aorta in early hypertension by cleaving many proteins of the extracellular matrix. Cleaved products from type I collagen may activate focal adhesion kinases (FAK) that trigger migration and proliferation signals in VSMC. We therefore hypothesized that increased activity of MMP-2 proteolyzes type I collagen in aortas of hypertensive rats, and thereby, induces FAK activation, thus leading to increased VSMC proliferation and hypertrophic remodeling in early hypertension. METHODS: Male Sprague-Dawley rats were submitted to renovascular hypertension by the two kidney-one clip (2K1C) model and treated with doxycycline (30 mg/kg/day) by gavage from the third to seventh-day post-surgery. Controls were submitted to sham surgery. Systolic blood pressure (SBP) was measured daily by tail-cuff plethysmography and the aortas were processed for zymography and Western blot for MMP-2, pFAK/FAK, integrins and type I collagen. Mass spectrometry, morphological analysis and Ki67 immunofluorescence were also done to identify collagen changes and VSMC proliferation. A7r5 cells were stimulated with collagen and treated with the MMP inhibitors (doxycycline or ARP-100), and with the FAK inhibitor PND1186 for 24 h. Cells were lysed and evaluated by Western blot for pFAK/FAK. RESULTS: 2K1C rats developed elevated SBP in the first week as well as increased expression and activity of MMP-2 in the aorta (p < 0.05 vs. Sham). Treatment with doxycycline reduced both MMP activity and type I collagen proteolysis in aortas of 2K1C rats (p < 0.05). Increased pFAK/FAK and increased VSMC proliferation (p < 0.05 vs. Sham groups) were also seen in the aortas of 2K1C and doxycycline decreased both parameters (p < 0.05). Higher proliferation of VSMC contributed to hypertrophic remodeling as seen by increased media/lumen ratio and cross sectional area (p < 0.05 vs Sham groups). In cell culture, MMP-2 cleaves collagen, an effect reversed by MMP inhibitors (p < 0.05). Increased levels of pFAK/FAK were observed when collagen was added in the culture medium (p < 0.05 vs control) and MMP and FAK inhibitors reduced this effect. CONCLUSIONS: Increase in MMP-2 activity proteolyzes type I collagen in the aortas of 2K1C rats and contributes to activate FAK and induces VSMC proliferation during the initial phase of hypertension.

Quercetin decreases cardiac hypertrophic mediators and maladaptive coronary arterial remodeling in renovascular hypertensive rats without improving cardiac function.

Oxidative stress and MMP activity are found in the hearts and arteries in hypertension and contribute to the resulting hypertrophy and dysfunction. Quercetin is a flavonoid that reduces MMP-2 activity and ameliorates hypertrophic vascular remodeling of hypertension. The hypothesis is that treatment of hypertensive rats with quercetin ameliorates coronary maladaptive remodeling and decreases hypertrophic cardiac dysfunction by decreasing oxidative stress and MMP activity. Male Sprague-Dawley two-kidney, one-clip (2K1C) and Sham rats were treated with quercetin (10 mg/kg/day) or its vehicle for 8 weeks by gavage. Rats were analyzed at 10 weeks of hypertension. Systolic blood pressure (SBP) was examined by tail-cuff plethysmography. Cardiac left ventricles were used to determine MMP activity by in situ zymography and oxidative stress by dihydroethidium. Immunofluorescence was performed to detect transforming growth factor (TGF)-ß and nuclear factor kappa B (NFkB). Morphological analyses of heart and coronary arteries were done by H&E and picrosirius red, and cardiac function was measured by Langendorff. SBP was increased in 2K1C rats, and quercetin did not reduce it. However, quercetin decreased both oxidative stress and TGF-ß in the left ventricles of 2K1C rats. Quercetin also decreased the accentuated MMP activity in left ventricles and coronary arteries of 2K1C rats. Quercetin ameliorated hypertension-induced coronary arterial hypertrophic remodeling, although it did not reduce cardiac hypertrophic remodeling and dysfunction. Quercetin decreases cardiac oxidative stress and TGF-ß and MMP activity in addition to improving coronary remodeling, yet does not ameliorate cardiac dysfunction in 2K1C rats.

The janus face of ketone bodies in hypertension.

Hypertension is the most important risk factor for the development of terminal cardiovascular diseases, such as heart failure, chronic kidney disease, and atherosclerosis. Lifestyle interventions to lower blood pressure are generally desirable prior to initiating pharmaceutical drug treatments, which may have undesirable side effects. Ketogenic interventions are popular but the scientific literature supporting their efficacy is specific to certain interventions and outcomes in animal models and patient populations. For example, although caloric restriction has its own inherent difficulties (e.g. it requires high levels of motivation and adherence is difficult), it has unequivocally been associated with lowering blood pressure in hypertensive patients. On the other hand, the antihypertensive efficacy of ketogenic diets is inconclusive, and this is surprising, given that these diets have been largely helpful in mitigating metabolic syndrome and promoting longevity. It is possible that side effects associated with ketogenic diets (e.g. dyslipidemia) aggravate the hypertensive phenotype. However, given the recent data from our group, and others, reporting that the most abundant ketone body, ß-hydroxybutyrate, can have positive effects on endothelial and vascular health, there is hope that ketone bodies can be harnessed as a therapeutic strategy to combat hypertension. Therefore, we conclude this review with a summary of the type and efficacy of ketone supplements. We propose that ketone supplements warrant investigation as low-dose antihypertensive therapy that decreases total peripheral resistance with minimal adverse side effects.

Low load strength training, associated with or without blood flow restriction increased NO production and decreased production of reactive oxygen species in rats aorta.

Studies have shown that strength training (ST) with blood flow restriction (BFR) in which low load is used (20-50% of 1 maximum voluntary contraction - MVC) can produce positive adaptations similar to ST with loads equal to or greater than 70% 1 MVC. Furthermore, recent studies have investigated the effects of STBFR on muscle adaptations, but few studies investigated the effects of STBFR on vascular function. This study aimed to evaluate the effects of the STBFR program on the vascular reactivity of the abdominal aorta of Wistar rats with femoral arteriovenous blood flow restriction. Male rats were divided into four groups: sedentary sham (S/S), sedentary with blood flow restriction (S/BFR), trained sham (T/S), and trained with blood flow restriction (T/BFR). The animals in the S/BFR and T/BFR groups underwent surgery to BFR in the femoral artery and vein. After one week, the trained groups started the ST which consisted of climbing ladder, six sets of 10 repetitions with 50% of 1 MVC assessed by maximum loaded weight (MLW) carried out for four weeks. Concentration-response curves to Acetylcholine (ACh: 10 nM - 100 µM) and Phenylephrine (PHE: 1 nM - 30 µM) were performed in aortic rings with intact endothelium. The production of nitric oxide (NO) and reactive oxygen species (ROS) in situ and the vascular remodeling marker (MMP-2) were also measured. The ST increased the strength of the T/S and T/BFR groups in MLW tests. The S/BFR group showed a 22% reduction in relaxation to acetylcholine, but exercise prevented this reduction in the T/BFR group. In animals without BFR, ST did not alter the response to acetylcholine. An increase in NO production was seen in T/S and T/BFR showed a reduction in ROS production (62% and 40%, respectively). In conclusion low load ST with BFR promotes similar vascular function responses to ST without BFR. Low load ST with and without BFR is interventions that can improve performance with similar magnitudes. Both training methods could have some benefits for vascular health due to NO production in the aorta increased in the T/S group and decreased production of reactive oxygen species in the T/BFR group.

MMP inhibition attenuates hypertensive eccentric cardiac hypertrophy and dysfunction by preserving troponin I and dystrophin.

PURPOSE: Cardiac transition from concentric (C-LVH) to eccentric left ventricle hypertrophy (E-LVH) is a maladaptive response of hypertension. Matrix metalloproteinases (MMPs), in particular MMP-2, may contribute to tissue remodeling by proteolyzing extra- and intracellular proteins. Troponin I and dystrophin are two potential targets of MMP-2 examined in this study and their proteolysis would impair cardiac contractile function. We hypothesized that MMP-2 contributes to the decrease in troponin I and dystrophin in the hypertensive heart and thereby controls the transition from C-LVH to E-LVH and cardiac dysfunction. METHODS: Male Wistar rats were divided into sham or two kidney-1 clip (2K-1C) hypertensive groups and treated with water (vehicle) or doxycycline (MMP inhibitor, 15 mg/kg/day) by gavage from the tenth to the sixteenth week post-surgery. Tail-cuff plethysmography, echocardiography, gelatin zymography, confocal microscopy, western blot, mass spectrometry, in silico protein analysis and immunofluorescence were performed. RESULTS: 6 out of 23 2K-1C rats (26%) had E-LVH followed by reduced ejection fraction. The remaining had C-LVH with preserved cardiac function. Doxycycline prevented the transition from C-LVH to E-LVH. MMP activity is increased in C-LVH and E-LVH hearts which was inhibited by doxycycline. This effect was associated with an increase in troponin I cleavage products and a decline in dystrophin in the left ventricle of E-LVH rats, which was prevented by doxycycline. CONCLUSION: Hypertension causes increased cardiac MMP-2 activity which proteolyzes troponin I and dystrophin, contributing to the transition from C-LVH to E-LVH and cardiac dysfunction.

C-type natriuretic peptide-induced relaxation through cGMP-dependent protein kinase and SERCA activation is impaired in two kidney-one clip rat aorta.

AIMS: Hypertension underlies endothelial dysfunction, and activation of vasorelaxation signaling with low dependence on nitric oxide (NO) represents a good alternative for vascular modulation. C-type natriuretic peptide (CNP) causes relaxation by increasing cyclic guanosine 3',5'-monophosphate (cGMP) or Gi-protein activation through its natriuretic peptide receptor-B or -C, respectively. We have hypothesized that CNP could exerts its effects and could overcome endothelial dysfunction in two kidney-one clip (2K-1C) hypertensive rat aorta. Here, we investigate the intracellular signaling involved in CNP effects in hypertension. MATERIALS AND METHODS: The 2K-1C hypertension was induced in male Wistar rats (200 g). CNP-induced vascular relaxation and cGMP production were investigated in rat thoracic aortas. The natriuretic peptide receptor-B and -C localization was evaluated by immunofluorescence. Calcium mobilization was assessed in endothelial cells from rat aortas. KEY FINDINGS: CNP induced similar relaxation in normotensive and 2K-1C hypertensive rat aortas, which increased after endothelium removal. CNP-induced relaxation involved natriuretic peptide receptor-B and -C activation in 2K-1C rats. Nitric oxide synthase (NOS) and soluble guanylyl cyclase (sGC) counter-regulated CNP-particulate GC (pGC) activation in aortas. CNP reduced endothelial calcium and increased cGMP production, which was lower in 2K-1C. CNP-induced cGMP-dependent protein kinase (PKG) and sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) activation was impaired in 2K-1C rat aorta. SIGNIFICANCE: Our results indicated CNP triggered relaxation through its natriuretic peptide receptor-B and -C in 2K-1C rat aortas, and that CNP-induced relaxation overcomes endothelial dysfunction in hypertension. In addition, NOS and sGC activities counter-regulate CNP-pGC activation to induce vascular relaxation.

Improving Cytotoxicity against Breast Cancer Cells by Using Mixed-Ligand Ruthenium(II) Complexes of 2,2'-Bipyridine, Amino Acid, and Nitric Oxide Derivatives as Potential Anticancer Agents.

BACKGROUND: Several metal-based molecules that display cytotoxicity against multiple cell lines have been pursued in an attempt to fight against cancer and to overcome the typical side effects of drugs like cisplatin. In this scenario, ruthenium complexes have been extensively studied due to their activity in both in vitro and in vivo biological systems, including various cancer cell strains. OBJECTIVE: We aimed to develop a method to synthesize novel [Ru(NO)(bpy)2L2]2+ complexes containing amino acid ligands by using an alternative Click Chemistry approach, namely the copper azide-alkyne cycloaddition reaction (CuAAC reaction), to construct nitrosyl/nitrite complexes bearing a modified lysine residue. METHODS: We synthesized a new ligand by Click Chemistry approach and new compounds bearing the unprecedented ligand. Cytotoxicity was assessed by the classical MTT colorimetric assay. MCF-7 and MDAMB- 231 cells were used as breast cancer cell models. MCF-10 was used as a model of healthy cells. RESULTS: Amino acid ligands related to N3-Lys(Fmoc) and the new pyLys were successfully synthesized by the diazotransfer reaction and the CuAAC reaction, respectively. The latter reaction involves coupling between N3-Lys(Fmoc) and 3ethynylpyridine. Both N3-Lys(Fmoc) and the new pyLys were introduced into the ruthenium bipyridine complex I, or cis-[RuII(NO)(NO2)(bpy)2]2+, to generate the common nitro-based complex III, which was further converted to the final complex IV. Results of the MTT assay proved the cytotoxic effect of cis- [RuII(NO)(pyLysO-)(bpy)2](PF6)2 against the mammalian breast cancer cells MCF-7 and MDA-MB231. CONCLUSION: The viability assays revealed that complex IV, bearing a NO group and a modified lysine residue, was able to release NO and cross tumor cell membranes. In this work, Complex IV was observed to be the most active ruthenium bipyridine complex against the mammalian breast cancer cells MCF-7 and MDA-MB231: it was approximately twice as active as cisplatin, whilst complexes I-III proved to be less cytotoxic than complex IV. Additional tests using healthy MCF 10A cells showed that complexes II-IV were three- to sixfold less toxic than cisplatin, which suggested that complex IV was selective against cancer cells.

The Influence of Some Axial Ligands on Ruthenium-Phthalocyanine Complexes: Chemical, Photochemical, and Photobiological Properties.

This work presents a new procedure to synthesize ruthenium-phthalocyanine complexes and uses diverse spectroscopic techniques to characterize trans-[RuCl(Pc)DMSO] (I) (Pc = phthalocyanine) and trans-[Ru(Pc)(4-ampy)2] (II) (4-ampy = 4-aminopyridine). The triplet excited-state lifetimes of (I) measured by nanosecond transient absorption showed that two processes occurred, one around 15 ns and the other around 3.8 µs. Axial ligands seemed to affect the singlet oxygen quantum yield. Yields of 0.62 and 0.14 were achieved for (I) and (II), respectively. The lower value obtained for (II) probably resulted from secondary reactions of singlet oxygen in the presence of the ruthenium complex. We also investigate how axial ligands in the ruthenium-phthalocyanine complexes affect their photo-bioactivity in B16F10 murine melanoma cells. In the case of (I) at 1 µmol/L, photosensitization with 5.95 J/cm2 provided B16F10 cell viability of 6%, showing that (I) was more active than (II) at the same concentration. Furthermore, (II) was detected intracellularly in B16F10 cell extracts. The behavior of the evaluated ruthenium-phthalocyanine complexes point to the potential use of (I) as a metal-based drug in clinical therapy. Changes in axial ligands can modulate the photosensitizer activity of the ruthenium phthalocyanine complexes.

Vascular tone and angiogenesis modulation by catecholamine coordinated to ruthenium.

Catecholamines participate in angiogenesis, an important tumor development process. However, the way catecholamines interact with their receptors has not been completely elucidated, and doubts still remain as to whether these interactions occur between catechol and/or amine sites and particular amino acid residues on the catecholamine receptors. To evaluate how catechol and amine groups contribute to angiogenesis, we immobilized the catechol site through ruthenium ion (Ru) coordination, to obtain species with the general formula [Ru(NH3)4(catecholamine-R)]Cl. We then assessed the angiogenic activity of the complexes in a chorioallantoic membrane model (CAM) and examined vascular reactivity and calcium mobilization in rat aortas and vascular cells. [Ru(NH3)4(catecholamine-R)]Cl acted as partial agonists and/or antagonists of their respective receptors and induced calcium mobilization. [Ru(NH3)4(isoproterenol)]+ [Ru(NH3)4(noradrenaline)]+, and [Ru(NH3)4(adrenaline)]+ behaved as antiangiogenic complexes, whereas [Ru(NH3)4(dopamine)]+ proved to be a proangiogenic complex. In conclusion, catecholamines and [Ru(NH3)4(catecholamine-R)]Cl can modulate angiogenesis, and catechol group availability can modify the way these complexes impact the vascular tone, suggesting that catecholamines and their receptors interact differently after catecholamine coordination to ruthenium.

Matrix metalloproteinase-2-induced epidermal growth factor receptor transactivation impairs redox balance in vascular smooth muscle cells and facilitates vascular contraction.

Increased reactive oxygen species (ROS) formation may enhance matrix metalloproteinase (MMP)-2 activity and promote cardiovascular dysfunction. We show for the first time that MMP-2 is upstream of increased ROS formation and activates signaling mechanisms impairing redox balance. Incubation of vascular smooth muscle cells (VSMC) with recombinant MMP-2 increased ROS formation assessed with dihydroethidium (DHE) by flow cytometry. This effect was blocked by the antioxidant apocynin or by polyethylene glycol-catalase (PEG-catalase), and by MMP inhibitors (doxycycline or GM6001). Next, we showed in HEK293 cells that MMP-2 transactivates heparin-binding epidermal growth factor (HB-EGF) leading to EGF receptor (EGFR) activation and increased ROS concentrations. This effect was prevented by the EGFR kinase inhibitor Ag1478, and by phospholipase C (PLC) or protein kinase C (PKC) inhibitors (A778 or chelerythrine, respectively), confirming the involvement of EGFR pathway in MMP-2-induce responses. Next, we showed that intraluminal exposure of aortas to MMP-2 increased vascular MMP-2 levels detected by immunofluorescence and gelatinolytic activity (by in situ zimography) in association with increased ROS formation. This effect was inhibited by MMP inhibitors (phenanthroline or doxycycline) and by apocynin or PEG-catalase. MMP-2 also increased aortic contractility to phenylephrine and this effect was prevented by MMP inhibitor GM6001 and by apocynin or PEG-catalase, showing again that increased ROS formation mediates functional effects of MMP-2. These results show that MMP-2 activates the EGFR and triggers downstream signaling pathways increasing ROS formation and promoting vasoconstriction. These findings may have various implications for cardiovascular diseases.

GPER modulates tone and coronary vascular reactivity in male and female rats.

Compared with age-matched men, premenopausal women are largely protected from coronary artery disease, a difference that is lost after menopause. The effects of oestrogens are mediated by the activation of nuclear receptors (ERα and ERß) and by the G protein-coupled oestrogen receptor (GPER). This study aims to evaluate the potential role of GPER in coronary circulation in female and male rats. The baseline coronary perfusion pressure (CPP) and the concentration-response curve with a GPER agonist (G-1) were evaluated in isolated hearts before and after the blockade of GPER. GPER, superoxide dismutase (SOD-2), catalase and gp91phox protein expression were assessed by Western blotting. Superoxide production was evaluated 'in situ' via dihydroethidium fluorescence (DHE). GPER blockade significantly increased the CPP in both groups, demonstrating the modulation of coronary tone by GPER. G-1 causes relaxation of the coronary bed in a concentration-dependent manner and was significantly higher in female rats. No differences were detected in GPER, SOD-2 and catalase protein expression. However, gp91phox expression and DHE fluorescence were higher in male rats, indicating elevated superoxide production. Therefore, GPER plays an important role in modulating coronary tone and reactivity in female and male rats. The observed differences in vascular reactivity may be related to the higher superoxide production in male rats. These findings help to elucidate the role of GPER-modulating coronary circulation, providing new information to develop a potential therapeutic target for the treatment of coronary heart disease.

C-Type Natriuretic Peptide Induces Anti-contractile Effect Dependent on Nitric Oxide, Oxidative Stress, and NPR-B Activation in Sepsis.

AIMS: To evaluate the role of nitric oxide, reactive oxygen species (ROS), and natriuretic peptide receptor-B activation in C-type natriuretic peptide-anti-contractile effect on Phenylephrine-induced contraction in aorta isolated from septic rats. METHODS AND RESULTS: Cecal ligation and puncture (CLP) surgery was used to induce sepsis in male rats. Vascular reactivity was conducted in rat aorta and resistance mesenteric artery (RMA). Measurement of survival rate, mean arterial pressure (MAP), plasma nitric oxide, specific protein expression, and localization were evaluated. Septic rats had a survival rate about 37% at 4 h after the surgery, and these rats presented hypotension compared to control-operated (Sham) rats. Phenylephrine-induced contraction was decreased in sepsis. C-type natriuretic peptide (CNP) induced anti-contractile effect in aortas. Plasma nitric oxide was increased in sepsis. Nitric oxide-synthase but not natriuretic peptide receptor-B expression was increased in septic rat aortas. C-type natriuretic peptide-anti-contractile effect was dependent on nitric oxide-synthase, ROS, and natriuretic peptide receptor-B activation. Natriuretic peptide receptor-C, protein kinase-Cα mRNA, and basal nicotinamide adenine dinucleotide phosphate (NADPH)-dependent ROS production were lower in septic rats. Phenylephrine and CNP enhanced ROS production. However, stimulated ROS production was low in sepsis. CONCLUSION: CNP induced anti-contractile effect on Phenylephrine contraction in aortas from Sham and septic rats that was dependent on nitric oxide-synthase, ROS, and natriuretic peptide receptor-B activation.