The role of Rho-associated kinase in differential regulation by statins of interleukin-1beta- and lipopolysaccharide-mediated nuclear factor kappaB activation and inducible nitric-oxide synthase gene expression in vascular smooth muscle cells

Statins in Mitigating Anticancer Treatment-Related Cardiovascular Disease

Certain anticancer therapies inevitably increase the risk of cardiovascular events, now the second leading cause of death among cancer patients. This underscores the critical need for developing effective drugs or regimens for cardiovascular protection. Statins possess properties such as antioxidative stress, anti-inflammatory effects, antifibrotic activity, endothelial protection, and immune modulation. These pathological processes are central to the cardiotoxicity associated with anticancer treatment. There is prospective clinical evidence confirming the protective role of statins in chemotherapy-induced cardiotoxicity. Numerous preclinical studies have demonstrated that statins can ameliorate heart and endothelial damage caused by radiotherapy, although clinical studies are scarce. In the animal models of trastuzumab-induced cardiomyopathy, statins provide protection through anti-inflammatory, antioxidant, and antifibrotic mechanisms. In animal and cell models, statins can mitigate inflammation, endothelial damage, and cardiac injury induced by immune checkpoint inhibitors. Chimeric antigen receptor (CAR)-T cell therapy-induced cardiotoxicity and immune effector cell-associated neurotoxicity syndrome are associated with uncontrolled inflammation and immune activation. Due to their anti-inflammatory and immunomodulatory effects, statins have been used to manage CAR-T cell therapy-induced immune effector cell-associated neurotoxicity syndrome in a clinical trial. However, direct evidence proving that statins can mitigate CAR-T cell therapy-induced cardiotoxicity is still lacking. This review summarizes the possible mechanisms of anticancer therapy-induced cardiotoxicity and the potential mechanisms by which statins may reduce related cardiac damage. We also discuss the current status of research on the protective effect of statins in anticancer treatment-related cardiovascular disease and provide directions for future research. Additionally, we propose further studies on using statins for the prevention of cardiovascular disease in anticancer treatment.

Statins for the Primary Prevention of Anthracycline Cardiotoxicity: A Comprehensive Review

PURPOSE OF REVIEW

The aim of this review is two-fold: (1) To examine the mechanisms by which statins may protect from anthracycline-induced cardiotoxicity and (2) To provide a comprehensive overview of the existing clinical literature investigating the role of statins for the primary prevention of anthracycline-induced cardiotoxicity.

RECENT FINDINGS

The underlying cardioprotective mechanisms associated with statins have not been fully elucidated. Key mechanisms related to the inhibition of Ras homologous (Rho) GTPases have been proposed. Data from observational studies has supported the beneficial role of statins for the primary prevention of anthracycline-induced cardiotoxicity. Recently, several randomized controlled trials investigating the role of statins for the primary prevention of anthracycline-induced cardiotoxicity have produced contrasting results. Statins have been associated with a lower risk of cardiac dysfunction in cancer patients receiving anthracyclines. Further investigation with larger randomized control trials and longer follow-up periods are needed to better evaluate the long-term role of statin therapy and identify the subgroups who benefit most from statin therapy.

Atorvastatin attenuates intestinal mucositis induced by 5-fluorouracil in mice by modulating the epithelial barrier and inflammatory response

Chemotherapy-induced intestinal mucositis is a major side effect of cancer treatment. Statins are 3-hydroxy-3-methyl glutaryl coenzyme reductase inhibitors used to treat hypercholesterolemia and atherosclerotic diseases. Recent studies have demonstrated that atorvastatin (ATV) has antioxidant, anti-inflammatory, and resulting from the regulation of different molecular pathways. In the present study, we investigated the effects of ATV on intestinal homeostasis in 5-fluorouracil (5-FU)-induced mucositis. Our results showed that ATV protected the intestinal mucosa from epithelial damage caused by 5-FU mainly due to inflammatory infiltrate and intestinal permeability reduction, downregulation of inflammatory markers, such as Tlr4, MyD88, NF-κB, Tnf-a, Il1β, and Il6 dose-dependent. ATV also improved epithelial barrier function by upregulating the mRNA transcript levels of mucin 2 (MUC2), and ZO-1 and occludin tight junction proteins. The results suggest that the ATV anti-inflammatory and protective effects on 5-FU-induced mice mucositis involve the inhibition of the TLR4/MYD88/NPRL3/NF-κB, iNos, and caspase 3.

Shared decision-making in the realm of uncertainty: The example of coronary artery disease through an EBM and complexity science lens

Patients look to their clinicians for explanations and treatments that achieve predictable cures with certainty. Clinicians usually respond accordingly. Acknowledging uncertainty, while necessary, is difficult, anxiety-provoking and at times overwhelming for patients and clinicians alike. We here present three case studies to illustrate the uncertainties of managing patients with potentially life-threatening illnesses. Research aims to provide answers to clinical problems. But, conducting research almost inevitably entails a reduction of real-world complexities. Research ultimately can only provide 'partial or in general answers' mostly revealing new questions. Due to the complexity of clinical care, research cannot really achieve certainty and predictability for an individual within his specific living context and values. In an unavoidably uncertain environment, instead of oversimplifying, clinicians like patients-as far as possible-ought to better embrace a complexity thinking frame. This provides a deeper understanding how living bodies function as-a-whole within their living contexts. Uncertainty and unpredictability, being inherent elements of complexity thinking, cannot be overcome. However, it may be made easier to cope with uncertainty by at least adopting the thinking in probabilities for benefits and harms of patient related outcomes as introduced in Sackett's Evidence-Based Medicine framework. Through the lenses of evidence-based medicine and complexity sciences this paper critically explores the clinical management of three patients diagnosed as having coronary artery disease. They all received the same treatment even though they presented with very different clinical complaints arising from different disease manifestations. Looking at these case studies the authors reflect on the reasons behind this astonishing, but widely seen medical behaviour of 'one size fits all'. They critically reflect the importance of research and evidence in view of a person-centred solution.

Rho-Proteins and Downstream Pathways as Potential Targets in Sepsis and Septic Shock: What Have We Learned from Basic Research

Sepsis and septic shock are associated with acute and sustained impairment in the function of the cardiovascular system, kidneys, lungs, liver, and brain, among others. Despite the significant advances in prevention and treatment, sepsis and septic shock sepsis remain global health problems with elevated mortality rates. Rho proteins can interact with a considerable number of targets, directly affecting cellular contractility, actin filament assembly and growing, cell motility and migration, cytoskeleton rearrangement, and actin polymerization, physiological functions that are intensively impaired during inflammatory conditions, such as the one that occurs in sepsis. In the last few decades, Rho proteins and their downstream pathways have been investigated in sepsis-associated experimental models. The most frequently used experimental design included the exposure to bacterial lipopolysaccharide (LPS), in both in vitro and in vivo approaches, but experiments using the cecal ligation and puncture (CLP) model of sepsis have also been performed. The findings described in this review indicate that Rho proteins, mainly RhoA and Rac1, are associated with the development of crucial sepsis-associated dysfunction in different systems and cells, including the endothelium, vessels, and heart. Notably, the data found in the literature suggest that either the inhibition or activation of Rho proteins and associated pathways might be desirable in sepsis and septic shock, accordingly with the cellular system evaluated. This review included the main findings, relevance, and limitations of the current knowledge connecting Rho proteins and sepsis-associated experimental models.

Involvement of Rho-kinase/IκB-α/NF-κB activation in IL-1β-induced inflammatory response and oxidative stress in human chondrocytes

It has been clearly indicated that osteoarthritis (OA) is an inflammatory and degenerative disease that could be promoted by Rho-kinase (ROCK); however, little is known about the role of ROCK/inhibitor κB alpha (IκB-α)/nuclear factor-κB (NF-κB) p65 pathway activation in interleukin-1β (IL-1β) induced inflammatory response and oxidative stress in primary human chondrocytes. To test this hypothesis, we focused on determining ROCK-II, IκB-α, p-IκB-α, NF-κB p65, p-NF-κB p65, IL-6, tumor necrosis factor alpha (TNF-α), cyclooxygenase-2 (COX-2), p22phox, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subtype 4 (NOX4) protein expression, ROCK-II activity, NADPH oxidase levels, and total antioxidant capacity (TAC) in the presence and absence of ROCK-inhibitor fasudil. IL-1β (2 ng·mL-1, 24 h) increased the expression of ROCK-II, p-IκB-α, NF-κB p65, p-NF-κB p65, IL-6, TNF-α, COX-2, and p22phox proteins, and decreased the expression of IκB-α, and the NOX4 protein level did not alter. ROCK activity and NADPH oxidase levels were increased, whereas the TAC was decreased by IL-1β. Fasudil (10-5-10-7 M) reversed all these changes induced by IL-1β. These results demonstrate that ROCK/IκB-α/NF-κB p65 pathway activation contributes to the IL-1β-induced inflammatory response and oxidative stress, and thus, ROCK inhibition might be a beneficial treatment option for OA patients mainly based on its anti-inflammatory and antioxidant effects.

Inflammation-Nature's Way to Efficiently Respond to All Types of Challenges: Implications for Understanding and Managing "the Epidemic" of Chronic Diseases

Siloed or singular system approach to disease management is common practice, developing out of traditional medical school education. Textbooks of medicine describe a huge number of discrete diseases, usually in a systematic fashion following headings like etiology, pathology, investigations, differential diagnoses, and management. This approach suggests that the body has a multitude of ways to respond to harmful incidences. However, physiology and systems biology provide evidence that there is a simple mechanism behind this phenotypical variability. Regardless if an injury or change was caused by trauma, infection, non-communicable disease, autoimmune disorders, or stress, the typical physiological response is: an increase in blood supply to the area, an increase in white cells into the affected tissue, an increase in phagocytic activity to remove the offending agent, followed by a down-regulation of these mechanisms resulting in healing. The cascade of inflammation is the body's unique mechanism to maintain its integrity in response to macroscopic as well as microscopic injuries. We hypothesize that chronic disease development and progression are linked to uncontrolled or dysfunctional inflammation to injuries regardless of their nature, physical, environmental, or psychological. Thus, we aim to reframe the prevailing approach of management of individual diseases into a more integrated systemic approach of treating the "person as a whole," enhancing the patient experience, ability to a make necessary changes, and maximize overall health and well-being. The first part of the paper reviews the local immune cascades of pro- and anti-inflammatory regulation and the interconnected feedback loops with neural and psychological pathways. The second part emphasizes one of nature's principles at work-system design and efficiency. Continually overwhelming this finely tuned system will result in systemic inflammation allowing chronic diseases to emerge; the pathways of several common conditions are described in detail. The final part of the paper considers the implications of these understandings for clinical care and explore how this lens could shape the physician-patient encounter and health system redesign. We conclude that healthcare professionals must advocate for an anti-inflammatory lifestyle at the patient level as well as at the local and national levels to enhance population health and well-being.

Statins in anthracycline-induced cardiotoxicity: Rac and Rho, and the heartbreakers

Cancer patients receiving anthracycline-based chemotherapy are at risk to develop life-threatening chronic cardiotoxicity with the pathophysiological mechanism of action not fully understood. Besides the most common hypothesis that anthracycline-induced congestive heart failure (CHF) is mainly caused by generation of reactive oxygen species, recent data point to a critical role of topoisomerase II beta (TOP2B), which is a primary target of anthracycline poisoning, in the pathophysiology of CHF. As the use of the only clinically approved cardioprotectant dexrazoxane has been limited by the FDA in 2011, there is an urgent need for alternative cardioprotective measures. Statins are anti-inflammatory and anti-oxidative drugs that are clinically well established for the prevention of cardiovascular diseases. They exhibit pleiotropic beneficial properties beyond cholesterol-lowering effects that most likely rest on the indirect inhibition of small Ras homologous (Rho) GTPases. The Rho GTPase Rac1 has been shown to be a major factor in the regulation of the pro-oxidative NADPH oxidase as well as in the regulation of type II topoisomerase. Both are discussed to play an important role in the pathophysiology of anthracycline-induced CHF. Therefore, off-label use of statins or novel Rac1 inhibitors might represent a promising pharmacological approach to gain control over chronic cardiotoxicity by interfering with key mechanisms of anthracycline-induced cardiomyocyte cell death.

Receptor proximal kinases in NF-κB signaling as potential therapeutic targets in cancer and inflammation

Many signaling pathways leading to activation of transcription factors and gene expression are characterized by phosphorylation events mediated by specific kinases. The transcription factor NF-κB plays a key role in multiple cellular processes, including immune signaling, inflammation, development, proliferation and survival. Dysregulated NF-κB activation is associated with autoimmunity, chronic inflammation and cancer. Activation of NF-κB requires IκB kinase (IKK)α or β, the activity of which is regulated via phosphorylation by specific IKK kinases and by autophosphorylation. Receptor specificity is further obtained by the use of multiple upstream receptor proximal kinases. We review the identities of several IKK regulatory kinases as well as the proposed molecular mechanisms. In addition, we discuss the potential for therapeutic targeting of some of these kinases in the context of inflammatory diseases and cancer.

The Rho/Rho-associated protein kinase inhibitor fasudil in the protection of endothelial cells against advanced glycation end products through the nuclear factor κB pathway

Accumulating evidence has demonstrated that the Rho/Rho-associated protein kinase (Rho/ROCK) and nuclear factor κB (NF-κB) signaling pathways are involved in the pathogenesis of diabetic vascular injury. In this study, we investigated the beneficial effects of fasudil, a ROCK inhibitor, on vascular endothelial injury induced by advanced glycation end products (AGEs) in vitro. Human umbilical vein endothelial cells (HUVECs) were stimulated with AGEs and AGEs plus fasudil in various concentrations for different time periods. Monocyte-endothelial cell adhesion, vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1) expression, protein expression and activation of Rho/ROCK, activation of NF-κB and reactive oxygen species (ROS) production were evaluated. Fasudil suppressed AGE-induced monocyte-endothelial adhesion. Fasudil also reduced the mRNA and protein expression of VCAM-1 and MCP-1 in a concentration- and time-dependent manner. Moreover, increases in the protein levels of Rho/ROCK and ROCK activity mediated by AGEs were inhibited by the addition of fasudil. Additionally, fasudil attenuated AGE-induced NF-κB-dependent transcriptional activity and inhibition of NF-κB (IκB) phosphorylation. ROS production induced by AGEs was also reduced by fasudil in HUVECs. The results suggest that ROCK inhibition may protect the vascular endothelium against AGE-induced monocyte-endothelial adhesion in vitro through the reduction of ROS generation and the downregulation of NF-κB signaling. Thus, ROCK inhibition may be a novel therapeutic approach for the treatment of vascular complications in diabetes.

Recent development in pleiotropic effects of statins on cardiovascular disease through regulation of transforming growth factor-beta superfamily

BACKGROUND

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, also known as statins, are a drug class that reduce the level of cholesterol in the blood. As a result, statins are used to suppress the progression of cardiovascular disease. Evidence points to another component of statins involving the non-lipid effects of the drug class in preventing cardiovascular disease. One specific mediator of this action is the transforming growth factor β (TGF-β) superfamily. The TGF-β superfamily consists of proteins that include TGF-β and bone morphogenetic proteins (BMPs). These proteins regulate cellular pathways to mediate effects including immunomodulation, cell cycling, and angiogenesis. One pathway that mediates these effects is Ras. Moreover, within this pathway, different functions are possible depending on the activation of the specific receptor subtype. This review discusses the recent development of the non-lipid effects of statins in preventing cardiovascular disease progression by regulating Ras pathway of the TGF-β superfamily, especially RhoA/ROCK pathway.

METHODS

A systematic PubMed database search of all English-language articles up to 2011 was conducted using the following terms: statin, TGF-β, Ras, ROCK, GGPP, inducible nitric oxide synthase, endothelial nitric oxide synthase, actin filament formation, PPARγ, MMP-2, and human trials.

CONCLUSION

With better understanding of the pathway, various mediators were identified; some of these mediators are important biomarkers producing more specific and accurate assessment of the pleiotropic effects of statins. The review of human trials also highlights that more specific biomarkers are employed in recent studies, and the non-lipid effects on human subjects are more accurately documented. Confirmation of the accuracy of these biomarkers by further large-scale studies and further development of new biomarkers may prove an important path leading to better patient selection for treatment, and thus better cost-effectiveness may be achieved.

Mitigation of the progression of heart failure with sildenafil involves inhibition of RhoA/Rho-kinase pathway

Chronic inhibition of phosphodiesterase-5 with sildenafil immediately after permanent occlusion of the left anterior descending coronary artery was shown to limit ischemic heart failure (HF) in mice. To mimic a more clinical scenario, we postulated that treatment with sildenafil beginning at 3 days post-myocardial infarction (MI) would also reduce HF progression through the inhibition of the RhoA/Rho-kinase pathway. Adult male ICR mice with fractional shortening < 25% at day 3 following permanent left anterior descending coronary artery ligation were continuously treated with either saline (volume matched, ip, 2 times/day) or sildenafil (21 mg/kg, ip, 2 times/day) for 25 days. Echocardiography showed fractional shortening preservation and less left ventricular end-diastolic dilatation with sildenafil treatment compared with saline treatment at 7 and 28 days post-MI (P < 0.05). Both fibrosis and apoptosis, determined by Masson's trichrome and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL), respectively, were attenuated in the sildenafil-treated mice (P < 0.05 vs. saline). Western blot analysis showed enchanced Bcl-2-to-Bax ratio with sildenafil treatment (P < 0.05 vs. saline). Activity assay showed sildenafil-mediated PKG activation 1 day after treatment (P < 0.05 vs. sham and saline). PKG activation was associated with sildenafil-mediated inhibition of Rho kinase (P < 0.05) compared with saline treatment, whereas PKG inhibition with KT-5823 abolished this inhibitory effect of sildenafil. In conclusion, for the first time, our findings show that chronic sildenafil treatment, initiated at 3 days post-MI, attenuates left ventricular dysfunction independent of its infarct-sparing effect, and this cardioprotection involves the inhibition of the RhoA/Rho-kinase pathway. Sildenafil may be a promising therapeutic tool for advanced HF in patients.

Simvastatin impairs murine melanoma growth

Background

Statins induces cell cycle arrest, apoptosis, reduction of angiogenic factors, inhibition of the endothelial growth factor, impairing tissue adhesion and attenuation of the resistance mechanisms. The aim of this study was evaluate the anti-tumoral activity of simvastatin in a B16F10 melanoma-mouse model.

Methods

Melanoma cells were treated with different concentrations of simvastatin and assessed by viability methods. Melanoma cells (5 × 10⁴) were implanted in two month old C57Bl6/J mice. Around 7 days after cells injection, the oral treatments were started with simvastatin (5 mg/kg/day, p.o.). Tumor size, hematological and biochemical analyses were evaluated.

Results

Simvastatin at a concentration of 0.8 μM, 1.2 μM and 1.6 μM had toxic effect. Concentration of 1.6 μM induced a massive death in the first 24 h of incubation. Simvastatin at 0.8 μM induces early cell cycle arrest in G0/G1, followed by increase of hypodiploidy. Tumor size were evaluated and the difference of treated group and control, after ten days, demonstrates that simvastatin inhibited the tumor expansion in 68%.

Conclusion

Simvastatin at 1.6 μM, presented cytototoxicity after 72 h of treatment, with an intense death. In vivo, simvastatin being potentially useful as an antiproliferative drug, with an impairment of growth after ten days.

SmgGDS is up-regulated in prostate carcinoma and promotes tumour phenotypes in prostate cancer cells

SmgGDS is a guanine nucleotide exchange factor with the unique ability to activate multiple small GTPases, implicating it in cancer development and progression. Here, we investigated the role of SmgGDS in prostate cancer by studying the expression of SmgGDS in benign and malignant prostatic tissues. We also probed SmgGDS function in three prostate carcinoma cell lines using small interfering RNA (siRNA). Immunohistochemical analysis revealed that SmgGDS levels were elevated in prostatic intraepithelial neoplasia (PIN), prostate carcinoma, and metastatic prostate carcinoma. In addition, expression of SmgGDS positively correlated with that of cyclooxygenase-2 (COX-2), a protein believed to promote the development of prostate carcinoma. Reduction of SmgGDS expression in prostate carcinoma cells inhibited proliferation and migration, irrespective of androgen receptor status. These effects were accompanied by a reduction in COX-2 expression and in activity of NF-kappaB, a known regulator of COX-2. Taken together, these findings suggest that SmgGDS promotes the development and progression of prostate cancer, possibly associated with NF-kappaB-dependent up-regulation of COX-2.

Beneficial effects of fluvastatin on liver microcirculation and regeneration after massive hepatectomy in rats

Fluvastatin, the first entirely synthetic statin, has a significant cholesterol-lowing effect comparable with other statins. In addition, it has been shown to inhibit oxidative stress and improve vascular endothelial function. The aim of this study was to clarify the pretreatment effects of fluvastatin on liver function after massive hepatectomy in rats. Six-week-old male Wister rats were divided into two groups: a fluvastatin group (group F), pretreated with oral administration of fluvastatin (20 mg/kg per day) for 2 days before 90% hepatectomy; and a control group (group C), pretreated with vehicle for 2 days before hepatectomy. Animals were sacrificed at 0, 12, 24, 48, and 72 h after hepatectomy. The liver regeneration rate, liver function tests, and hepatic stellate cell activation were examined. The liver regeneration rate in group F was significantly higher at 72 h after hepatectomy (P < 0.05). The serum level of total bilirubin in group F was significantly lower at 48 h after hepatectomy (P < 0.05). Sinusoidal area in group F was maintained histologically. Furthermore, the expression of alpha smooth-muscle actin (alpha-SMA) protein in the liver was inhibited in group F at 48 h after hepatectomy. This study demonstrated the beneficial effects of fluvastatin in a lethal massive hepatectomy model using rats, with improved hepatic regeneration and microcirculations, by inhibiting the activation of hepatic stellate cells.

Regulatory roles for Tiam1, a guanine nucleotide exchange factor for Rac1, in glucose-stimulated insulin secretion in pancreatic beta-cells

Using various biochemical, pharmacological and molecular biological approaches, we have recently reported regulatory roles for Rac1, a small G-protein, in glucose-stimulated insulin secretion (GSIS). However, little is understood with respect to localization of, and regulation by, specific regulatory factors of Rac1 in GSIS. Herein, we investigated regulatory roles for Tiam1, a specific nucleotide exchange factor (GEF) for Rac1, in GSIS in pancreatic beta-cells. Western blot analysis indicated that Tiam1 is predominantly cytosolic in distribution. NSC23766, a specific inhibitor of Tiam1-mediated activation of Rac1, markedly attenuated glucose-induced, but not KCl-induced insulin secretion in INS 832/13 cells and normal rat islets. Further, NSC23766 significantly reduced glucose-induced activation (i.e. GTP-bound form) and membrane association of Rac1 in INS 832/13 cells and rat islets. Moreover, siRNA-mediated knock-down of Tiam1 markedly inhibited glucose-induced membrane trafficking and activation of Rac1 in INS 832/13 cells. Interestingly, however, in contrast to the inhibitory effects of NSC23766, Tiam1 gene depletion potentiated GSIS in these cells; such a potentiation of GSIS was sensitive to extracellular calcium. Together, our studies present the first evidence for a regulatory role for Tiam1/Rac1-sensitive signaling step in GSIS. They also provide evidence for the existence of a potential Rac1/Tiam1-independent, but calcium-sensitive component for GSIS in these cells.

Statins induce regulatory T cell recruitment via a CCL1 dependent pathway

The statins, a group of inhibitors of the 3-hydroxy-3-methylglutaryl coenzyme A reductase, are reported to influence a variety of immune system activities through 3-hydroxy-3-methylglutaryl coenzyme A reductase-dependent and -independent mechanisms. How statin treatment regulates immune system function in vivo nonetheless remains to be fully defined. We analyzed the immunomodulatory effects of lovastatin in a Candida albicans-induced delayed-type hypersensitivity reaction in mice. In this model, lovastatin administration reduced the acute inflammatory response elicited by C. albicans challenge. This anti-inflammatory activity of lovastatin was associated with a shift from a Th1 to a Th2 immune response, as well as an increase in the percentage of regulatory T cells at the inflammation site and in the regional draining lymph node. The lovastatin-induced increase in regulatory T cells in the inflamed skin was dependent on expression of CCL1, a chemokine that is locally up-regulated by statin administration. The anti-inflammatory effect of lovastatin was abrogated in CCL1-deficient mice. These results suggest that local regulation of chemokine expression may be an important process in statin-induced modulation of the immune system.

SmgGDS regulates cell proliferation, migration, and NF-kappaB transcriptional activity in non-small cell lung carcinoma

Non-small cell lung carcinoma (NSCLC) is promoted by the increased activities of several small GTPases, including K-Ras4B, Rap1A, Rap1B, RhoC, and Rac1. SmgGDS is an unusual guanine nucleotide exchange factor that activates many of these small GTPases, and thus may promote NSCLC development or progression. We report here that SmgGDS protein levels are elevated in NSCLC tumors, compared with normal lung tissue from the same patients or from individuals without cancer. To characterize SmgGDS functions in NSCLC, we tested the effects of silencing SmgGDS expression by transfecting cultured NSCLC cells with SmgGDS small interfering RNA (siRNA). Cells with silenced SmgGDS expression form fewer colonies in soft agar, do not proliferate in culture due to an arrest in G(1) phase, and exhibit disrupted myosin organization and reduced cell migration. The transcriptional activity of NF-kappaB in NSCLC cells is diminished by transfecting the cells with SmgGDS siRNA, and enhanced by transfecting the cells with a cDNA encoding SmgGDS. Because RhoA is a major substrate for SmgGDS, we investigated whether diminished RhoA expression mimics the effects of diminished SmgGDS expression. Silencing RhoA expression with RhoA siRNA disrupts myosin organization, but only moderately decreases cell proliferation and does not inhibit migration. Our finding that the aggressive NSCLC phenotype is more effectively suppressed by silencing SmgGDS than by silencing RhoA is consistent with the ability of SmgGDS to regulate multiple small GTPases in addition to RhoA. These results demonstrate that SmgGDS promotes the malignant NSCLC phenotype and is an intriguing therapeutic target in NSCLC.

Decreased intrahepatic response to alpha(1)-adrenergic agonists in lipopolysaccharide-treated rats is located in the sinusoidal area and depends on Kupffer cell function

BACKGROUND AND AIM

Livers from lipopolysaccharide-treated rats have a decreased vascular response to alpha(1)-adrenergic agonists due to an increased production of nitric oxide. Kupffer cells play a central role in the development of intrahepatic microvascular abnormalities during endotoxemia. We investigated the role of Kupffer cells in the intrahepatic vascular tone control in normal and endotoxemic rats.

METHOD

Twenty-four hours after pretreatment with gadolinium chloride (to eliminate/inactivate Kupffer cells) or saline, rats were treated with lipopolysaccharide or a second dose of saline. Six hours later, rats (under deep anesthesia) were submitted to liver perfusion with Krebs-Henseleit solution using a system that allowed the measurement of both perfusion and sinusoidal pressures. Dose-response curves to methoxamine (alpha(1)-adrenergic agonist) were obtained in the absence or the presence of the nitric oxide synthase inhibitor N-monomethyl-L-arginine.

RESULTS

Pretreatment with gadolinium did not change the intrahepatic vascular response to methoxamine in normal livers. Livers from lipopolysaccharide-treated rats showed a decreased sinusoidal vascular response to methoxamine and a 10-fold increase in nitric oxide production during liver perfusion. Either pretreatment with gadolinium or the presence of N-monomethyl-L-arginine in the perfusate restored the response to methoxamine and decreased the nitric oxide overproduction by more than 50%.

CONCLUSIONS

Kupffer cells neither mediate nor modulate the intrahepatic vascular response to alpha(1)-adrenergic agonists in normal livers. Reduction in intrahepatic vascular response to alpha(1)-adrenergic agonists in livers from lipopolysaccharide-treated rats is located in the sinusoidal area and depends on Kupffer cell function.

Molecular programming of endothelin-1 in HIV-infected brain: role of Tat in up-regulation of ET-1 and its inhibition by statins

Human Immune Deficiency Virus-1 (HIV-1) infection can induce severe and debilitating neurological problems, including behavioral abnormalities, motor dysfunction, and dementia. HIV can persistently infect astrocytes, during which viral accessory proteins are produced that are unaffected by current antiretroviral therapy. The effect of these proteins on astrocyte function remains unknown. Astrocytes are the predominant cells within the brain; thus, disruption of astrocyte function could influence the neuropathogenesis of HIV infection. To explore further these effects, we constitutively expressed HIV-Tat protein in astrocytes. Since the nuclear presence of Tat protein leads to alteration of host gene expression, we further analyzed the effects of Tat on host gene transcripts. Endothelin-1 (ET-1) was a significantly elevated transcript as verified by reverse transcription-polymerase chain reaction (RT-PCR), and it was subsequently released extracellularly in Tat-expressing and HIV-infected astrocytes. ET-1 expression was also prominent in reactive astrocytes and neurons in brain tissues from basal ganglia and frontal lobes of HIV encephalitic patients. HIV-Tat regulated ET-1 at the transcriptional level through NF-kappaB (NF-kappaB)-responsive sites in the ET-1 promoter. Intriguingly, simvastatin (10 microM) down-regulated HIV-Tat-induced ET-1 and also inhibited activation of NF-kappaB in astrocytes. Our findings suggest that ET-1 may be critical in mediating the neuropathogenesis of HIV dementia and that statins may have therapeutic potential in these patients.

Rac1 mediates intestinal epithelial cell apoptosis via JNK

Apoptosis plays a key role in the maintenance of a constant cell number and a low incidence of cancer in the mucosa of the intestine. Although the small GTPase Rac1 has been established as an important regulator of migration of intestinal epithelial cells, whether Rac1 is also involved in apoptosis is unclear. The present study tested the hypothesis that Rac1 mediates TNF-alpha-induced apoptosis in IEC-6 cells. Rac1 is activated during TNF-alpha-induced apoptosis as judged by the level of GTP-Rac1, the level of microsomal membrane-associated Rac1, and lamellipodia formation. Although expression of constitutively active Rac1 does not increase apoptosis in the basal condition, inhibition of Rac1 either by NSC-23766 (Rac1 inhibitor) or expression of dominant negative Rac1 protects cells from TNF-alpha-induced apoptosis by inhibiting caspase-3, -8, and -9 activities. Inhibition of Rac1 before the administration of apoptotic stimuli significantly prevents TNF-alpha-induced activation of JNK1/2, the key proapoptotic regulator in IEC-6 cells. Inhibition of Rac1 does not modulate TNF-alpha-induced ERK1/2 and Akt activation. Inhibition of ERK1/2 and Akt activity by U-0126 and LY-294002, respectively, increased TNF-alpha-induced apoptosis. However, inhibition of Rac1 significantly decreased apoptosis in the presence of ERK1/2 and Akt inhibitors, similar to the effect observed with NSC-23766 alone in response to TNF-alpha. Thus, Rac1 inhibition protects cells independently of ERK1/2 and Akt activation during TNF-alpha-induced apoptosis. Although p38 MAPK is activated in response to TNF-alpha, inhibition of p38 MAPK did not decrease apoptosis. Rac1 inhibition did not alter p38 MAPK activity. Thus, these results indicate that Rac1 mediates apoptosis via JNK and plays a key role in proapoptotic pathways in intestinal epithelial cells.

Simvastatin inhibits NF-kappaB signaling in intestinal epithelial cells and ameliorates acute murine colitis

Statins, HMG-CoA reductase inhibitors exert pleiotropic anti-inflammatory properties in vitro and in vivo, and are associated with the risk reduction of colorectal cancer. It remains unknown, however, whether statin is effective for the treatment of inflammatory bowel disease (IBD). Therefore, we investigated anti-inflammatory effects of simvastatin on intestinal epithelial cells (IEC) and on an experimental murine colitis model, and elucidated its molecular mechanisms. Simvastatin (50 micro M) significantly inhibited TNF-alpha-induced IL-8 gene expression in COLO 205 cells. Simvastatin (50 micro M) blocked TNF-alpha-induced NF-kappaB transcriptional activity, IkappaB phosphorylation/degradation and DNA binding activity of NF-kappaB. Administration of simvastatin significantly reduced the severity of dextran sulfate sodium (DSS)-induced murine colitis as assessed by body weight, colon length, DAI, and histology in a dose-dependent manner. These results suggest that simvastatin inhibits proinflammatory gene expression by blocking NF-kappaB signaling in IEC, and attenuates DSS-induced acute murine colitis. Simvastatin could be a potential agent for the treatment of IBD.

Gene-based therapy for hypertension--do preclinical data suggest a promising future?

Many experimental studies have obtained a prolonged control of blood pressure through gene treatment. This consists in the administration of genes coding for vasodilator proteins (the 'sense' approach), or of nucleotide sequences that are complementary to the mRNA of vasoconstrictor proteins, which are consequently synthesized in smaller amounts (the 'antisense' approach). Examples of the sense approach include the genes encoding endothelial nitric oxide synthase and kallikrein. Examples of the second type of approach are the antisense oligodeoxynucleotides to angiotensin-converting enzyme and endothelin-1. Also, RNA molecules, such as ribozymes and small interfering RNAs, are capable to inhibit RNA function. Whole sense genes are usually administered through viral vectors, while antisense oligonucleotides may be administered with plasmids or liposomes. Both viral and non-viral vectors have advantages and disadvantages. Despite the still persisting limitations, the possibility exists that in the future some forms of genetic treatment will be extended to the clinical setting, allowing a prolonged control of essential hypertension and its end-organ sequelae.

Store-operated calcium channels and pro-inflammatory signals

In non-excitable cells such as T lymphocytes, hepatocytes, mast cells, endothelia and epithelia, the major pathway for calcium [Ca2+] entry is through store-operated Ca2+ channels in the plasma membrane. These channels are activated by the emptying of intracellular Ca2+ stores, however, neither the gating mechanism nor the downstream targets of these channels has been clear established. Here, I review some of the proposed gating mechanisms of store-operated Ca2+ channels and the functional implications in regulating pro-inflammatory signals.