Gallic acid triphenylphosphonium derivatives TPP+-C10 and TPP+-C12 inhibit mitochondrial function in Candida albicans exerting antifungal and antibiofilm effects.

AIMS: To evaluate the antifungal and antibiofilm activity of gallic acid derivatives TPP+-C10 and TPP+-C12 and their effects on mitochondrial function on two Candida albicans reference strains (ATCC 90029 and ATCC 10231). METHODS AND RESULTS: First, we determined minimal inhibitory concentration (MIC) using a microdilution assay. Both compounds exerted antifungal effects, and their MICs ranged from 3.9 to 13 µM, with no statistically significant differences between them (P > 0.05, t-test). These concentrations served as references for following assays. Subsequently, we measured oxygen consumption with a Clark electrode. Our observations revealed that both drugs inhibited oxygen consumption in both strains with TPP+-C12 exerting a more pronounced inhibitory effect. We then employed flow cytometry with TMRE as a probe to assess mitochondrial membrane potential. For each strain assayed, the compounds induced a decay in transmembrane potential by 75%-90% compared to the control condition (P < 0.05, ANOVA). Then, we measured ATP levels using a commercial kit. TPP+-C12 showed a 50% decrease of ATP content (P < 0.05 ANOVA), while TPP+-C10 exhibited a less pronounced effect. Finally, we assessed the antibiofilm effect using the MTT reduction assay. Both compounds were effective, but TPP+-C12 displayed a greater potency, requiring a lower concentration to inhibit 50% of biofilms viability (P < 0.05, t-test). CONCLUSIONS: Derivatives of gallic acid linked to a TPP+ group exert antifungal and antibiofilm activity through impairment of mitochondrial function in C. albicans.

SGK1 is necessary to FoxO3a negative regulation, oxidative stress and cardiac fibroblast activation induced by TGF-ß1.

Cardiac fibroblasts (CFs) activation is a common response to most pathological conditions affecting the heart, characterized by increased cellular secretory capacity and increased expression of fibrotic markers, such as collagen I and smooth muscle actin type alpha (α-SMA). Fibrotic activation of CFs induces the increase in tissue protein content, with the consequent tissue stiffness, diastolic dysfunction, and heart failure. Therefore, the search for new mechanisms of CFs activation is important to find novel treatments for cardiac diseases characterized by fibrosis. In this regard, TGF-ß1, a cytokine with proinflammatory and fibrotic properties, is crucial in the CFs activation and the development of fibrotic diseases, whereas its molecular targets are not completely known. Serum and glucocorticoid-regulated kinase (SGK1) is a protein involved in various pathophysiological phenomena, especially cardiac and renal diseases that curse with fibrosis. Additionally, SGK1 phosphorylates and regulates the activity and expression of several targets, highlighting FoxO3a for its role in the regulation of oxidative stress and CFs activation induced by TGF-ß1. However, the regulation of SGK1 by TGF-ß1 and its role in CFs activation have not been studied. In this work, we evaluate the role of SGK1 in CFs isolated from neonatal Sprague-Dawley rats. The participation of SGK1 in the fibrotic activation of CFs induced by TGF-ß1 was analyzed, using an inhibitor or siRNA of SGK1. In addition, the role of SGK1 on the regulation of FoxO3a and oxidative stress induced by TGF-ß1 was analyzed. Our results indicate that TGF-ß1 increased both the activity and expression of SGK1 in CFs, requiring the activation of MAPKs, ERK1/2, p38 and JNK, while inhibition and silencing of SGK1 prevented TGF-ß1-induced fibrotic activation of CFs. In addition, SGK1 inhibition prevented FoxO3a inactivation and expression reduction, catalase and SOD2 expression decrease, and the increase of oxidative stress induced by TGF-ß1. Taken together, our results position SGK1 as an important regulator of CFs activation driven by TGF-ß1, at least in part, through the regulation of FoxO3a and oxidative stress.

Lipoxin A4 prevents high glucose-induced inflammatory response in cardiac fibroblast through FOXO1 inhibition.

Cardiac cells respond to various pathophysiological stimuli, synthesizing inflammatory molecules that allow tissue repair and proper functioning of the heart; however, perpetuation of the inflammatory response can lead to cardiac fibrosis and heart dysfunction. High concentration of glucose (HG) induces an inflammatory and fibrotic response in the heart. Cardiac fibroblasts (CFs) are resident cells of the heart that respond to deleterious stimuli, increasing the synthesis and secretion of both fibrotic and proinflammatory molecules. The molecular mechanisms that regulate inflammation in CFs are unknown, thus, it is important to find new targets that allow improving treatments for HG-induced cardiac dysfunction. NFκB is the master regulator of inflammation, while FoxO1 is a new participant in the inflammatory response, including inflammation induced by HG; however, its role in the inflammatory response of CFs is unknown. The inflammation resolution is essential for an effective tissue repair and recovery of the organ function. Lipoxin A4 (LXA4) is an anti-inflammatory agent with cytoprotective effects, while its cardioprotective effects have not been fully studied. Thus, in this study, we analyze the role of p65/NFκB, and FoxO1 in CFs inflammation induced by HG, evaluating the anti-inflammatory properties of LXA4. Our results demonstrated that HG induces the inflammatory response in CFs, using an in vitro and ex vivo model, while FoxO1 inhibition and silencing prevented HG effects. Additionally, LXA4 inhibited the activation of FoxO1 and p65/NFκB, and inflammation of CFs induced by HG. Therefore, our results suggest that FoxO1 and LXA4 could be novel drug targets for the treatment of HG-induced inflammatory and fibrotic disorders in the heart.

Pharmacological Effects of Caffeic Acid and Its Derivatives in Cancer: New Targeted Compounds for the Mitochondria.

Cancer is a complex pathology of great heterogeneity and difficulty that makes the constant search for new therapies necessary. A major advance on the subject has been made by focusing on the development of new drugs aimed to alter the metabolism of cancer cells, by generating a disruption of mitochondrial function. For this purpose, several new compounds with specific mitochondrial action have been tested, leading successfully to cell death. Recently, attention has centered on a group of natural compounds present in plants named polyphenols, among which is caffeic acid, a polyphenol that has proven to be a powerful antitumoral agent and a prominent compound for studies focused on the development of new therapies against cancer.In this review, we revised the antitumoral capacity and mechanisms of action of caffeic acid and its derivatives, with special emphasis in a new class of caffeic acid derivatives that target mitochondria by chemical binding to the lipophilic cation triphenylphosphonium.

Statins change the cytokine profile in Trypanosoma cruzi-infected U937 macrophages and murine cardiac tissue through Rho-associated kinases inhibition.

Introduction: Chronic Chagasic cardiomyopathy (CCC), caused by the protozoan Trypanosoma cruzi, is the most severe manifestation of Chagas disease.CCC is characterized by cardiac inflammation and fibrosis caused by a persistent inflammatory response. Following infection, macrophages secrete inflammatory mediators such as IL-1ß, IL-6, and TNF-α to control parasitemia. Although this response contains parasite infection, it causes damage to the heart tissue. Thus, the use of immunomodulators is a rational alternative to CCC. Rho-associated kinase (ROCK) 1 and 2 are RhoA-activated serine/threonine kinases that regulate the actomyosin cytoskeleton. Both ROCKs have been implicated in the polarization of macrophages towards an M1 (pro-inflammatory) phenotype. Statins are FDA-approved lipid-lowering drugs that reduce RhoA signaling by inhibiting geranylgeranyl pyrophosphate (GGPP) synthesis. This work aims to identify the effect of statins on U937 macrophage polarization and cardiac tissue inflammation and its relationship with ROCK activity during T. cruzi infection. Methods: PMA-induced, wild-type, GFP-, CA-ROCK1- and CA-ROCK2-expressing U937 macrophages were incubated with atorvastatin, or the inhibitors Y-27632, JSH-23, TAK-242, or C3 exoenzyme incubated with or without T. cruzi trypomastigotes for 30 min to evaluate the activity of ROCK and the M1 and M2 cytokine expression and secretion profiling. Also, ROCK activity was determined in T. cruzi-infected, BALB/c mice hearts. Results: In this study, we demonstrate for the first time in macrophages that incubation with T. cruzi leads to ROCK activation via the TLR4 pathway, which triggers NF-κB activation. Inhibition of ROCKs by Y-27632 prevents NF-κB activation and the expression and secretion of M1 markers, as does treatment with atorvastatin. Furthermore, we show that the effect of atorvastatin on the NF-kB pathway and cytokine secretion is mediated by ROCK. Finally, statin treatment decreased ROCK activation and expression, and the pro-inflammatory cytokine production, promoting anti-inflammatory cytokine expression in chronic chagasic mice hearts. Conclusion: These results suggest that the statin modulation of the inflammatory response due to ROCK inhibition is a potential pharmacological strategy to prevent cardiac inflammation in CCC.

FoxO1 is required for high glucose-dependent cardiac fibroblasts into myofibroblast phenoconversion.

In the normal heart, cardiac fibroblasts (CFs) maintain extracellular matrix (ECM) homeostasis, whereas in pathological conditions, such as diabetes mellitus (DM), CFs converse into cardiac myofibroblasts (CMFs) and this CFs phenoconversion increase the synthesis and secretion of ECM proteins, promoting cardiac fibrosis and heart dysfunction. High glucose (HG) conditions increase TGF-ß1 expression and FoxO1 activity, whereas FoxO1 is crucial to CFs phenoconversion induced by TGF-ß1. In addition, FoxO1 increases CTGF expression, whereas CTGF plays an active role in the fibrotic process induced by hyperglycemia. However, the role of FoxO1 and CTGF in CFs phenoconversion induced by HG is not clear. In this study, we investigated the effects of FoxO1 pharmacological inhibition on CFs phenoconversion in both in vitro and ex vivo models of DM. Our results demonstrate that HG induces CFs phenoconversion and FoxO1 activation. Moreover, AS1842856, a pharmacological inhibitor of FoxO1 activity, prevents CFs phenoconversion and CTGF expression increase induced by HG, whereas these results were corroborated by FoxO1 silencing. Additionally, K252a, a pharmacological blocker of CTGF receptor, prevents HG-induced CFs phenoconversion, which was corroborated with CTGF expression knockdown. Furthermore, through CFs isolation from heart of diabetic rats, we showed that hyperglycemia induces FoxO1 activation, the increase of CTGF expression and CFs phenoconversion, whereas the FoxO1 activity inhibition reverses the effects induced by hyperglycemia on CFs. Altogether, our results demonstrate that FoxO1 and CTGF are necessary for CFs phenoconversion induced by HG and suggest that both proteins are likely to become a potential targeted drug for fibrotic response induced by hyperglycemic conditions.

Kaempferol Induces Cell Death and Sensitizes Human Head and Neck Squamous Cell Carcinoma Cell Lines to Cisplatin.

Cisplatin is a first-line chemotherapeutic drug commonly used to treat patients with head and neck cancer; nevertheless, cisplatin resistance poses a main challenge for its clinical efficacy. Recent studies have shown that kaempferol, a natural flavonoid found in various plants and foods, has an anticancer effect. The following study evaluated the cytotoxic effects of kaempferol on head and neck tumor cells and their mechanism of action, evaluating the effects on proliferation, the oxygen consumption rate, transmembrane potential, tumor cell migration and induction of apoptosis. Moreover, we determined the effects of a combination of kaempferol and cisplatin on head and neck tumor cells. We found that kaempferol inhibited the oxygen consumption rate and decreased the intracellular ATP content in tumor cells. This novel mechanism may inhibit the migratory capacity and promote antiproliferative effects and apoptosis of tumor cells. Additionally, our in vitro data indicated that kaempferol may sensitize head and neck tumor cells to the effects of cisplatin. These effects provide new evidence for the use of a combination of kaempferol and cisplatin in vivo and their future applications in head and neck cancer therapy.

Medicinal Chemistry Targeting Mitochondria: From New Vehicles and Pharmacophore Groups to Old Drugs with Mitochondrial Activity.

Interest in tumor cell mitochondria as a pharmacological target has been rekindled in recent years. This attention is due in part to new publications documenting heterogenous characteristics of solid tumors, including anoxic and hypoxic zones that foster cellular populations with differentiating metabolic characteristics. These populations include tumor-initiating or cancer stem cells, which have a strong capacity to adapt to reduced oxygen availability, switching rapidly between glycolysis and oxidative phosphorylation as sources of energy and metabolites. Additionally, this cell subpopulation shows high chemo- and radioresistance and a high capacity for tumor repopulation. Interestingly, it has been shown that inhibiting mitochondrial function in tumor cells affects glycolysis pathways, cell bioenergy, and cell viability. Therefore, mitochondrial inhibition may be a viable strategy for eradicating cancer stem cells. In this context, medicinal chemistry research over the last decade has synthesized and characterized "vehicles" capable of transporting novel or existing pharmacophores to mitochondrial tumor cells, based on mechanisms that exploit the physicochemical properties of the vehicles and the inherent properties of the mitochondria. The pharmacophores, some of which have been isolated from plants and others, which were synthesized in the lab, are diverse in chemical nature. Some of these molecules are active, while others are prodrugs that have been evaluated alone or linked to mitochondria-targeted agents. Finally, researchers have recently described drugs with well-proven safety and efficacy that may exert a mitochondria-specific inhibitory effect in tumor cells through noncanonical mechanisms. The effectiveness of these molecules may be improved by linking them to mitochondrial carrier molecules. These promising pharmacological agents should be evaluated alone and in combination with classic chemotherapeutic drugs in clinical studies.

The Microbiota-Derived Metabolite of Quercetin, 3,4-Dihydroxyphenylacetic Acid Prevents Malignant Transformation and Mitochondrial Dysfunction Induced by Hemin in Colon Cancer and Normal Colon Epithelia Cell Lines.

Meat diet plays a pivotal role in colorectal cancer (CRC). Hemin, a metabolite of myoglobin, produced after meat intake, has been involved in CRC initiation. The compound, 3,4-dihydroxyphenylacetic acid (3,4HPAA) is a scarcely studied microbiota-derived metabolite of the flavonoid quercetin (QUE), which exert antioxidant properties. The aim of this study was to determine the protective effect of 3,4HPAA against malignant transformation (increased cell proliferation, decreased apoptosis, DNA oxidative damage and augmented reactive oxidative species (ROS) levels) and mitochondrial dysfunction induced by hemin in normal colon epithelial cells and colon cancer cells. The effect of 3,4HPAA was assessed in comparison to its precursor, QUE and to a known CRC protective agent, sulforaphane (SFN). The results showed that both, tumor and normal cells, exposed to hemin, presented increased cell proliferation, decreased caspase 3 activity and cytochrome c release, as well as augmented production of intracellular and mitochondrial ROS. In addition, hemin decreased the mitochondrial membrane potential (MMP) and the activity of complexes I and II of the electron transport chain. These effects of hemin were prevented by the action of 3,4HPAA. The metabolite showed to be more active than QUE and slightly less active than SFN. In conclusion, 3,4HPAA administration could represent a promising strategy for preventing malignant transformation and mitochondrial dysfunction in colon epithelia induced by hemin.

Novel benzoate-lipophilic cations selectively induce cell death in human colorectal cancer cell lines.

INTRODUCTION: Colorectal cancer (CRC) is a critical health issue worldwide. The high rate of liver and lung metastasis associated with CRC creates a significant barrier to effective and efficient therapy. Tumour cells, including CRC cells, have metabolic alterations, such as high levels of glycolytic activity, increased cell proliferation and invasiveness, and chemo- and radio-resistance. However, the abnormally elevated mitochondrial transmembrane potential of these cells also provides an opportunity to develop drugs that selectively target the mitochondrial functions of tumour cells. METHODS: In this work, we used a new batch of benzoic acid esters with cytotoxic activities attached to the triphenylphosphonium group as a vehicle to target tumour mitochondria and improve their activity. We evaluated the cytotoxicity, selectivity, and mechanism of action of these derivatives, including the effects on energy stress-induced apoptosis and metabolic behaviour in the human CRC cell lines HCT-15 and COLO-205. RESULTS: The benzoic acid derivatives selectively targeted the tumour cells with high potency and efficacy. The derivatives induced the uncoupling of the oxidative phosphorylation system, decreased the transmembrane potential, and reduced ATP levels while increasing AMPK activation, thereby triggering tumour cell apoptosis in both tumour cell lines tested. CONCLUSION: The benzoic acid derivatives studied here are promising candidates for assessing in vivo models of CRC, despite the diverse metabolic characteristics of these tumour cells.

Role of FoxO3a as a negative regulator of the cardiac myofibroblast conversion induced by TGF-ß1.

Cardiac fibroblasts (CFs) are necessary to maintain extracellular matrix (ECM) homeostasis in the heart. Normally, CFs are quiescent and secrete small amounts of ECM components, whereas, in pathological conditions, they differentiate into more active cells called cardiac myofibroblasts (CMF). CMF conversion is characteristic of cardiac fibrotic diseases, such as heart failure and diabetic cardiomyopathy. TGF-ß1 is a key protein involved in CMF conversion. SMADs are nuclear factor proteins activated by TGF-ß1 that need other proteins, such as forkhead box type O (FoxO) family members, to promote CMF conversion. FoxO1, a member of this family protein, is necessary for TGF-ß1-induced CMF conversion, whereas the role of FoxO3a, another FoxO family member, is unknown. FoxO3a plays an important role in many fibrotic processes in the kidney and lung. However, the participation of FoxO3a in the conversion of CFs into CMF is not clear. In this paper, we demonstrate that TGF-ß1 decreases the activation and expression of FoxO3a in CFs. FoxO3a regulation by TGF-ß1 requires activated SMAD3, ERK1/2 and Akt. Furthermore, we show that FoxO1 is crucial in the FoxO3a regulation induced by TGF-ß1, as shown by overexpressed FoxO1 enhancing and silenced FoxO1 suppressing the effects of TGF-ß1 on FoxO3a. Finally, the regulation of TGF-ß1-induced CMF conversion was enhanced by FoxO3a silencing and suppressed by inhibited FoxO3a degradation. Considering these collective findings, we suggest that FoxO3a acts as a negative regulator of the CMF conversion that is induced by TGF-ß1.

Complex Mitochondrial Dysfunction Induced by TPP+-Gentisic Acid and Mitochondrial Translation Inhibition by Doxycycline Evokes Synergistic Lethality in Breast Cancer Cells.

The mitochondrion has emerged as a promising therapeutic target for novel cancer treatments because of its essential role in tumorigenesis and resistance to chemotherapy. Previously, we described a natural compound, 10-((2,5-dihydroxybenzoyl)oxy)decyl) triphenylphosphonium bromide (GA-TPP+C10), with a hydroquinone scaffold that selectively targets the mitochondria of breast cancer (BC) cells by binding to the triphenylphosphonium group as a chemical chaperone; however, the mechanism of action remains unclear. In this work, we showed that GA-TPP+C10 causes time-dependent complex inhibition of the mitochondrial bioenergetics of BC cells, characterized by (1) an initial phase of mitochondrial uptake with an uncoupling effect of oxidative phosphorylation, as previously reported, (2) inhibition of Complex I-dependent respiration, and (3) a late phase of mitochondrial accumulation with inhibition of α-ketoglutarate dehydrogenase complex (αKGDHC) activity. These events led to cell cycle arrest in the G1 phase and cell death at 24 and 48 h of exposure, and the cells were rescued by the addition of the cell-penetrating metabolic intermediates l-aspartic acid ß-methyl ester (mAsp) and dimethyl α-ketoglutarate (dm-KG). In addition, this unexpected blocking of mitochondrial function triggered metabolic remodeling toward glycolysis, AMPK activation, increased expression of proliferator-activated receptor gamma coactivator 1-alpha (pgc1α) and electron transport chain (ETC) component-related genes encoded by mitochondrial DNA and downregulation of the uncoupling proteins ucp3 and ucp4, suggesting an AMPK-dependent prosurvival adaptive response in cancer cells. Consistent with this finding, we showed that inhibition of mitochondrial translation with doxycycline, a broad-spectrum antibiotic that inhibits the 28 S subunit of the mitochondrial ribosome, in the presence of GA-TPP+C10 significantly reduces the mt-CO1 and VDAC protein levels and the FCCP-stimulated maximal electron flux and promotes selective and synergistic cytotoxic effects on BC cells at 24 h of treatment. Based on our results, we propose that this combined strategy based on blockage of the adaptive response induced by mitochondrial bioenergetic inhibition may have therapeutic relevance in BC.

Continuous flow synthesis of lipophilic cations derived from benzoic acid as new cytotoxic chemical entities in human head and neck carcinoma cell lines.

Continuous flow chemistry was used for the synthesis of a series of delocalized lipophilic triphenylphosphonium cations (DLCs) linked by means of an ester functional group to several hydroxylated benzoic acid derivatives and evaluated in terms of both reaction time and selectivity. The synthesized compounds showed cytotoxic activity and selectivity in head and neck tumor cell lines. The mechanism of action of the molecules involved a mitochondrial uncoupling effect and a decrease in both intracellular ATP production and apoptosis induction.

TGF-ß1 induced up-regulation of B1 kinin receptor promotes antifibrotic activity in rat cardiac myofibroblasts.

Cardiac myofibroblast (CMF) are non-muscle cardiac cells that play a crucial role in wound healing and in pathological remodeling. These cells are mainly derived of cardiac fibroblast (CF) differentiation mediated by TGF-ß1. Evidence suggests that bradykinin (BK) regulates cardiac fibroblast function in the heart. Both B1 and B2 kinin receptors (B1R and B2R, respectively) mediate the biological effects of kinins. We recently showed that both receptors are expressed in CMF and its stimulation decreases collagen secretion. Whether TGF-ß1 regulates B1R and B2R expression, and how these receptors control antifibrotic activity in CMF remains poorly understood. In this work, we sought to study, the regulation of B1R expression in cultured CMF mediated by TGF-ß1, and the molecular mechanisms involved in B1R activation on CMF intracellular collagen type-I levels. Cardiac fibroblast-primary culture was obtained from neonatal rats. Hearts were digested and CFs were attached to dishes and separated from cardiomyoctes. CMF were obtained from CF differentiation with TGF-ß1 5 ng/mL. CF and CMF were treated with B1R and B2R agonists and with TGF-ß1 at different times and concentrations, in the presence or absence of chemical inhibitors, to evaluate signaling pathways involved in B1R expression, collagen type-I and prostacyclin levels. B1R and collagen type-I levels were evaluated by western blot. Prostacyclin levels were quantified by an ELISA kit. TGF-ß1 increased B1R expression via TGFß type I receptor kinase (ALK5) activation and its subsequent signaling pathways involving Smad2, p38, JNK and ERK1/2 activation. Moreover, in CMF, the activation of B1R and B2R by their respective agonists, reduced collagen synthesis. This effect was mediated by the canonical signaling pathway; phospholipase C (PLC), protein kinase C (PKC), phospholipase A2 (PLA2), COX-2 activation and PGI2 secretion and its autocrine effect. TGF-ß1 through ALK5, Smad2, p38, JNK and ERK1/2 increases B1R expression; whereas in CMF, B1R and B2R activation share common signaling pathways for reducing collagen synthesis.

Antiproliferative and proapoptotic activities of aza-annulated naphthoquinone analogs.

1,4-Naphthoquinone derivatives have been widely documented with regard to their biological properties, and particularly their anticancer activities. In the 9,10-anthraquinone family, aza-annulation involving one of the carbonyl oxygen atoms has afforded more potent, possibly less toxic analogues. We recently carried out different modifications on the naphthoquinone skeleton to generate 3-chloro-2-amino- and 3-chloro-2-(N-acetamido)-1,4-naphthoquinone and 3,4-dihydrobenzo[f]quinoxalin-6(2H)-one derivatives. These three series of compounds were now tested against normal human fibroblasts and six human cancer cell lines. Some of the dihydrobenzoquinoxalinone derivatives were not only more potent than their 1,4-naphthoquinone counterparts, but also exhibited 10- to 14-fold selectivity between bladder carcinoma and normal cells and were equipotent with the non-selective reference drug used (etoposide). The fusion of an additional azaheterocycle to the 1,4-naphthoquinone nucleus modulates both the activity, selectivity and mechanism of action of the compounds. The electrochemical properties of selected compounds were evaluated in an attempt to correlate them with cytotoxic activity and mechanism of action. Finally, 3D-QSAR CoMFA and CoMSIA models were built on the AGS, J82, and HL-60 cell lines. The best models had values of r2pred = 0.815; 0.823 and 0.925. The main structural relationships found, suggest that acetylation and alkylation of the amino group with large groups would be beneficial for cytotoxic activity.

Destabilization of mitochondrial functions as a target against breast cancer progression: Role of TPP(+)-linked-polyhydroxybenzoates.

Mitochondrion is an accepted molecular target in cancer treatment since it exhibits a higher transmembrane potential in cancer cells, making it susceptible to be targeted by lipophilic-delocalized cations of triphenylphosphonium (TPP(+)). Thus, we evaluated five TPP(+)-linked decyl polyhydroxybenzoates as potential cytotoxic agents in several human breast cancer cell lines that differ in estrogen receptor and HER2/neu expression, and in metabolic profile. Results showed that all cell lines tested were sensitive to the cytotoxic action of these compounds. The mechanism underlying the cytotoxicity would be triggered by their weak uncoupling effect on the oxidative phosphorylation system, while having a wider and safer therapeutic range than other uncouplers and a significant lowering in transmembrane potential. Noteworthy, while the TPP(+)-derivatives alone led to almost negligible losses of ATP, when these were added in the presence of an AMP-activated protein kinase inhibitor, the levels of ATP fell greatly. Overall, data presented suggest that decyl polyhydroxybenzoates-TPP(+) and its derivatives warrant future investigation as potential anti-tumor agents.

EPAC expression and function in cardiac fibroblasts and myofibroblasts.

UNLABELLED: In the heart, cardiac fibroblasts (CF) and cardiac myofibroblasts (CMF) are the main cells responsible for wound healing after cardiac insult. Exchange protein activated by cAMP (EPAC) is a downstream effector of cAMP, and it has been not completely studied on CF. Moreover, in CMF, which are the main cells responsible for cardiac healing, EPAC expression and function are unknown. We evaluated in both CF and CMF the effect of transforming growth factor ß1 (TGF-ß1) on EPAC-1 expression. We also studied the EPAC involvement on collagen synthesis, adhesion, migration and collagen gel contraction. METHOD: Rat neonatal CF and CMF were treated with TGF-ß1 at different times and concentrations. EPAC-1 protein levels and Rap1 activation were measured by western blot and pull down assay respectively. EPAC cellular functions were determined by adhesion, migration and collagen gel contraction assay; and collagen expression was determined by western blot. RESULTS: TGF-ß1 through Smad and JNK significantly reduced EPAC-1 expression in CF, while in CMF this cytokine increased EPAC-1 expression through ERK1/2, JNK, p38, AKT and Smad3. EPAC activation was able to induce higher Rap1-GTP levels in CMF than in CF. EPAC and PKA, both cAMP effectors, promoted CF and CMF adhesion on fibronectin, as well as CF migration; however, this effect was not observed in CMF. EPAC but not PKA activation mediated collagen gel contraction in CF, while in CMF both PKA and EPAC mediated collagen gel contraction. Finally, the EPAC and PKA activation reduced collagen synthesis in CF and CMF. CONCLUSION: TGF-ß1 differentially regulates the expression of EPAC in CF and CMF; and EPAC regulates differentially CF and CMF functions associated with cardiac remodeling.

TGF-ß1 prevents simulated ischemia/reperfusion-induced cardiac fibroblast apoptosis by activation of both canonical and non-canonical signaling pathways.

Ischemia/reperfusion injury is a major cause of myocardial death. In the heart, cardiac fibroblasts play a critical role in healing post myocardial infarction. TGF-ß1 has shown cardioprotective effects in cardiac damage; however, if TGF-ß1 can prevent cardiac fibroblast death triggered by ischemia/reperfusion is unknown. Therefore, we test this hypothesis, and whether the canonical and/or non-canonical TGF-ß1 signaling pathways are involved in this protective effect. Cultured rat cardiac fibroblasts were subjected to simulated ischemia/reperfusion. Cell viability was analyzed by trypan blue exclusion and propidium iodide by flow cytometry. The processing of procaspases 8, 9 and 3 to their active forms was assessed by Western blot, whereas subG1 population was evaluated by flow cytometry. Levels of total and phosphorylated forms of ERK1/2, Akt and Smad2/3 were determined by Western blot. The role of these signaling pathways on the protective effect of TGF-ß1 was studied using specific chemical inhibitors. Simulated ischemia over 8h triggers a significant cardiac fibroblast death, which increased by reperfusion, with apoptosis actively involved. These effects were only prevented by the addition of TGF-ß1 during reperfusion. TGF-ß1 pretreatment increased the levels of phosphorylated forms of ERK1/2, Akt and Smad2/3. The inhibition of ERK1/2, Akt and Smad3 also blocked the preventive effects of TGF-ß1 on cardiac fibroblast apoptosis induced by simulated ischemia/reperfusion. Overall, our data suggest that TGF-ß1 prevents cardiac fibroblast apoptosis induced by simulated ischemia-reperfusion through the canonical (Smad3) and non canonical (ERK1/2 and Akt) signaling pathways.

Differential regulation of collagen secretion by kinin receptors in cardiac fibroblast and myofibroblast.

UNLABELLED: Kinins mediate their cellular effects through B1 (B1R) and B2 (B2R) receptors, and the activation of B2R reduces collagen synthesis in cardiac fibroblasts (CF). However, the question of whether B1R and/or B2R have a role in cardiac myofibroblasts remains unanswered. METHODS: CF were isolated from neonate rats and myofibroblasts were generated by an 84 h treatment with TGF-ß1 (CMF). B1R was evaluated by western blot, immunocytochemistry and radioligand assay; B2R, inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), and cyclooxygenases 1 and 2 (COX-1, and COX-2) were evaluated by western blot; intracellular Ca⁺² levels were evaluated with Fluo-4AM; collagen secretion was measured in the culture media using the picrosirius red assay kit. RESULTS: B2R, iNOS, COX-1 and low levels of B1R but not eNOS, were detected by western blot in CF. Also, B1R, B2R, and COX-2 but not iNOS, eNOS or COX-1, were detected by western blot in CMF. By immunocytochemistry, our results showed lower intracellular B1R levels in CF and higher B1R levels in CMF, mainly localized on the cell membrane. Additionally, we found B1R only in CMF cellular membrane through radioligand displacement assay. Bradykinin (BK) B2R agonist increased intracellular Ca²âº levels and reduced collagen secretion both in CF and CMF. These effects were blocked by HOE-140, and inhibited by L-NAME, 1400 W and indomethacin. Des-Arg-kallidin (DAKD) B1R agonist did not increase intracellular Ca²âº levels in CF; however, after preincubation for 1h with DAKD and re-stimulation with the same agonist, we found a low increase in intracellular Ca²âº levels. Finally, DAKD increased intracellular Ca²âº levels and decreased collagen secretion in CMF, being this effect blocked by the B1R antagonist des-Arg9-Leu8-kallidin and indomethacin, but not by L-NAME or 1400 W. CONCLUSION: B1R, B2R, iNOS and COX-1 were expressed differently between CF and CMF, and collagen secretion was regulated differentially by kinin receptor agonists in cultured CF and CMF.

Cardiac fibroblast death by ischemia/reperfusion is partially inhibited by IGF-1 through both PI3K/Akt and MEK-ERK pathways.

UNLABELLED: Cardiac fibroblast (CF) death by ischemia/reperfusion (I/R) has major implications for cardiac wound healing. Although IGF-1 has well-known cytoprotective effects, no study has been done on CF subjected to simulated I/R. Simulated ischemia of neonate rat CF was performed in a free oxygen chamber in an ischemic medium; reperfusion was done in normal culture conditions. Cell viability was evaluated by trypan blue assay, and apoptosis by a FACS flow cytometer; p-ERK-1/2 and p-Akt levels were determined by western blot. We showed that simulated I/R triggers CF death by necrosis and apoptosis. IGF-1 partially inhibits I/R-induced apoptosis. PD98059 and LY294002 neutralize the preventive effects of IGF-1. CONCLUSION: IGF-1 partially inhibits CF apoptosis induced by simulated I/R by PI3K/Akt- and MEK/ERK1/2-dependent signaling pathways.