Inhibition of angiotensin II receptor 1 limits tumor-associated angiogenesis and attenuates growth of murine melanoma

Advances in nuclei targeted delivery of nanoparticles for the management of cancer

A carrier is inserted into the appropriate organelles (nucleus) in successful medication transport, crucial to achieving very effective illness treatment. Cell-membrane targeting is the major focus of using nuclei to localize delivery. It has been demonstrated that high quantities of anticancer drugs can be injected directly into the nuclei of cancer cells, causing the cancer cells to die and increasing the effectiveness of chemotherapy. There are several effective ways to functionalize Nanoparticles (NPs), including changing their chemical makeup or attaching functional groups to their surface to increase their ability to target organelles. To cause tumor cells to apoptosis, released medicines must engage with molecular targets on particular organelles when their concentration is high enough. Targeted medication delivery studies will increasingly focus on organelle-specific delivery.

Angiotensin II receptor blockers in dermatology: a narrative review

Angiotensin II receptor blockers (ARBs) are commonly used for cardiovascular diseases, especially for patients who can't tolerate the side effects of cough and angioedema caused by angiotensin converting enzyme inhibitors (ACEIs). However, the evidence of using ARBs in dermatology is mostly anecdotal and limited to case reports or small case series. Here we present a narrative review focusing on the therapeutic use of ARBs in dermatology and adverse cutaneous reactions due to the administration of ARBs.

Drug Repurposing Strategies for Non-Cancer to Cancer Therapeutics

Global efforts invested for the prevention and treatment of cancer need to be repositioned to develop safe, effective, and economic anticancer therapeutics by adopting rational approaches of drug discovery. Drug repurposing is one of the established approaches to reposition old, clinically approved off patent noncancer drugs with known targets into newer indications. The literature review suggests key role of drug repurposing in the development of drugs intended for cancer as well as noncancer therapeutics. A wide category of noncancer drugs namely, drugs acting on CNS, anthelmintics, cardiovascular drugs, antimalarial drugs, anti-inflammatory drugs have come out with interesting outcomes during preclinical and clinical phases. In the present article a comprehensive overview of the current scenario of drug repurposing for the treatment of cancer has been focused. The details of some successful studies along with examples have been included followed by associated challenges.

Modulation of Epithelial Mesenchymal Transition after AGTR-1 Gene Edition by Crispr/Cas9 and Losartan Treatment in Mammary Tumor Cell Line: A Comparative Study between Human and Canine Species

Breast cancer is the most prevalent tumor type among women and female dogs. Tumor malignancy is characterized by the epithelial-to-mesenchymal transition (EMT) which leads to the metastasis formation. The inhibition of angiotensin II type I receptor (AGTR1) by an antagonist such as losartan can suppress angiogenesis, consequently contributing to the metastasis control. The aim of this study was to analyze the capacity of losartan and AGTR-1 gene edition to modulate the EMT process in triple negative/metastatic mammary tumor cells, compared to existing treatment protocols such as carboplatin. The cell lines CF41.Mg and MDA-MB-468, were cultured and treated with carboplatin, losartan, or submitted to AGTR-1 gene edition by CRISPR/Cas9. EMT markers and PARP-1 protein and gene expression were evaluated by immunofluorescence or immunocytochemistry and qRT-PCR, respectively. Cell migration capacity was also evaluated. For CF41.Mg and MDA-MB-468 cell lines, there was an increase in E-cadherin and a decrease in N-cadherin and PARP-1 protein and gene expression after treatment with carboplatin, losartan, both in combination and after AGTR-1 gene edition. There was a decrease in VEGF and PARP-1 protein and gene expression after AGTR-1 gene edition. Moreover, in both lines, reduction in invasion rate was observed after all treatments. Our data suggest that losartan and the gene edition of AGTR-1 by CRISPR/Cas9 were able to block the DNA repair and control the EMT process, such as carboplatin. The results in the canine species are unprecedented, as there are no data in the literature that demonstrate the action of losartan in this tumor type.

Associations between initiating antihypertensive regimens on stage I-III colorectal cancer outcomes: A Medicare SEER cohort analysis

Purpose

Colorectal cancer (CRC) diagnosis is associated with high mortality in the United States and thus warrants the study of novel treatment approaches. Vascular changes are well observed in cancers and evidence indicates that antihypertensive (AH) medications may interfere with both tumor vasculature and in recruiting immune cells to the tumor microenvironment based on preclinical models. Extant literature also shows that AH medications are correlated with improved survival in some forms of cancer. Thus, this study sought to explore the impact of AH therapies on CRC outcomes.

Patients and Methods

This study was a non‐interventional, retrospective analysis of patients aged 65 years and older with CRC diagnosed from January 1, 2007 to December 31st, 2012 in the Surveillance, Epidemiology, and End‐Results (SEER)‐Medicare database. The association between AH drug utilization on AJCC stage I–III CRC mortality rates in patients who underwent treatment for cancer was examined using Cox proportional hazards models.

Results

The study cohort consisted of 13,982 patients diagnosed with CRC. Adjusted Cox proportional hazards regression showed that among these patients, the use of AH drug was associated with decreased cancer‐specific mortality (HR: 0.79, 95% CI: 0.75–0.83). Specifically, ACE inhibitors (hazard ratio [HR]: 0.84, 95% CI: 0.80–0.87), beta‐blockers (HR: 0.87, 95% CI: 0.84–0.91), and thiazide diuretics (HR: 0.83, 95% CI: 0.80–0.87) were found to be associated with decreased mortality. An association was also found between adherence to AH therapy and decreased cancer‐specific mortality (HR: 0.94, 95% CI: 0.90–0.98).

Conclusion

Further research needs to be performed, but AH medications may present a promising, low‐cost pathway to supporting CRC treatment for stage I–III cancers.

Cancer Stem Cells in Head and Neck Metastatic Malignant Melanoma Express Components of the Renin-Angiotensin System

Components of the renin-angiotensin system (RAS) are expressed by cancer stem cells (CSCs) in many cancer types. We here investigated expression of the RAS by the CSC subpopulations in human head and neck metastatic malignant melanoma (HNmMM) tissue samples and HNmMM-derived primary cell lines. Immunohistochemical staining demonstrated expression of pro-renin receptor (PRR), angiotensin-converting enzyme (ACE), and angiotensin II receptor 2 (AT₂R) in all; renin in one; and ACE2 in none of the 20 HNmMM tissue samples. PRR was localized to cells within the tumor nests (TNs), while AT₂R was expressed by cells within the TNs and the peritumoral stroma (PTS). ACE was localized to the endothelium of the tumor microvessels within the PTS. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) detected transcripts for PRR, ACE, ACE2, and AT₁R, in all the five HNmMM tissue samples and four HNmMM-derived primary cell lines; renin in one tissue sample and one cell line, and AT₂R in none of the five HNmMM tissue samples and cell lines. Western blotting showed variable expression of ACE, PRR, and AT₂R, but not ACE2, in six HNmMM tissue samples and two HNmMM-derived primary cell lines. Immunofluorescence staining of two HNmMM tissue samples demonstrated expression of PRR and AT₂R by the SOX2+ CSCs within the TNs and the OCT4+ CSCs within the PTS, with ACE localized to the endothelium of the tumor microvessels within the PTS.

Antihypertensives and melanoma: An updated review

Antihypertensive medications are commonly prescribed and well-studied. Given the widespread use and potential side effects, various theories have been made about the relationship between antihypertensives and malignancy, including melanoma. This review describes the current understanding of the most commonly prescribed antihypertensives and their associations with melanoma. The literature demonstrates that diuretics, specifically hydrochlorothiazide and indapamide, may increase the risk of melanoma. While there is no evidence that antihypertensives have a role in melanoma prevention, non-selective β-blocker therapy has been associated with a decreased risk of disease progression and recurrence and may also improve outcomes in patients undergoing immunotherapy. In addition, experimental studies reveal that angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and calcium channel blockers have anti-tumor effects, meriting further study.

Losartan improves the therapeutic effect of metronomic cyclophosphamide in triple negative mammary cancer models

Metronomic chemotherapy refers to the minimum biologically effective doses of a chemotherapy agent given as a continuous regimen without extended rest periods. Drug repurposing is defined as the use of an already known drug for a new medical indication, different from the original one. In oncology the combination of these two therapeutic approaches is called “Metronomics”.

The aim of this work is to evaluate the therapeutic effect of cyclophosphamide in a metronomic schedule in combination with the repurposed drug losartan in two genetically different mice models of triple negative breast cancer.

Our findings showed that adding losartan to metronomic cyclophosphamide significantly improved the therapeutic outcome. In both models the combined treatment increased the mice’s survival without sings of toxicity. Moreover, we elucidated some of the mechanisms of action involved, which include a decrease of intratumor hypoxia, stimulation of the immune response and remodeling of the tumor microenvironment.

The remarkable therapeutic effect, the lack of toxicity, the low cost of the drugs and its oral administration, strongly suggest its translation to the clinical setting in the near future.

Repurposing of drugs approved for cardiovascular diseases: Opportunity or mirage?

Drug repurposing is a promising way in drug discovery to identify new therapeutic uses -different from the original medical indication- for existing drugs. It has many advantages over traditional approaches to de novo drug discovery, since it can significantly reduce healthcare costs and development timeline. In this review, we discuss the possible repurposing of drugs approved for cardiovascular diseases, such as β-blockers, angiotensin converting enzyme inhibitors (ACE-Is), angiotensin II receptor blockers (ARBs), statins, aspirin, cardiac glycosides and low-molecular-weight heparins (LMWHs). Indeed, numerous experimental and epidemiological studies have reported promising anti-cancer activities for these drugs. It is worth mentioning, however, that the results of these studies are often controversial and very few data were obtained by controlled prospective clinical trials. Therefore, no final conclusion has yet been reached in this area and no final recommendations can be made. Moreover, β-blockers, ARBs and statins showed promising results in randomised controlled trials (RCTs) where pathological conditions other than cancer were considered. The results obtained have led or may lead to new indications for these drugs. For each drug or class of drugs, the potential molecular mechanisms of action justifying repurposing, results obtained in vitro and in animal models and data from epidemiological and randomized studies are described.

The Angiotensin Receptor Blocker Losartan Suppresses Growth of Pulmonary Metastases via AT1R-Independent Inhibition of CCR2 Signaling and Monocyte Recruitment

Inflammatory monocytes have been shown to play key roles in cancer metastasis through promotion of tumor cell extravasation, growth, and angiogenesis. Monocyte recruitment to metastases is mediated primarily via the CCL2-CCR2 chemotactic axis. Thus, disruption of this axis represents an attractive therapeutic target for the treatment of metastatic disease. Losartan, a type I angiotensin II receptor (AT1R) antagonist, has been previously shown to have immunomodulatory actions involving monocyte and macrophage activity. However, the exact mechanisms accounting for these effects have not been fully elucidated. Therefore, we investigated the effects of losartan and its primary metabolite on CCL2-mediated monocyte recruitment and CCR2 receptor function using mouse tumor models and in vitro human monocyte cultures. We show, in this study, that losartan and its metabolite potently inhibit monocyte recruitment through the noncompetitive inhibition of CCL2-induced ERK1/2 activation, independent of AT1R activity. Studies in experimental metastasis models demonstrated that losartan treatment significantly reduced the metastatic burden in mice, an effect associated with a significant decrease in CD11b⁺/Ly6C⁺-recruited monocytes in the lungs. Collectively, these results indicate that losartan can exert antimetastatic activity by inhibiting CCR2 signaling and suppressing monocyte recruitment and therefore suggest that losartan (and potentially other AT1R blocker drugs) could be repurposed for use in cancer immunotherapy.

Telmisartan induces melanoma cell apoptosis and synergizes with vemurafenib in vitro by altering cell bioenergetics

Objective

Despite recent advancements in targeted therapy and immunotherapies, prognosis for metastatic melanoma patients remains extremely poor. Development of resistance to previously effective treatments presents a serious challenge and new approaches for melanoma treatment are urgently needed. The objective of this study was to examine the effects of telmisartan, an AGTR1 inhibitor and a partial agonist of PPARγ, on melanoma cells as a potential agent for repurposing in melanoma treatment.

Methods

Expression of AGTR1 and PPARγ mRNA in melanoma patient tumor samples was examined in publicly available datasets and confirmed in melanoma cell lines by qRT-PCR. A panel of melanoma cell lines was tested in viability, apoptosis and metabolic assays in presence of telmisartan by flow cytometry and immunocytochemistry. A cytotoxic effect of combinations of telmisartan and targeted therapy vemurafenib was examined using the Chou-Talalay combination index method.

Results

Both AGTR1 and PPARγ mRNA were expressed in melanoma patient tumor samples and decreased compared to the expression in the healthy skin. In vitro, we found that telmisartan decreased melanoma cell viability by inducing cell apoptosis. Increased glucose uptake, but not utilization, in the presence of telmisartan caused the fission of mitochondria and release of reactive oxygen species. Telmisartan altered the cell bioenergetics, thereby synergizing with vemurafenib in vitro, and even sensitized vemurafenib-resistant cells to the treatment.

Conclusions

Given that the effective doses of telmisartan examined in our study can be administered to patients and that telmisartan is a widely used and safe antihypertensive drug, our findings provide the scientific rationale for testing its efficacy in treatment of melanoma progression.

Perindopril, fosinopril and losartan inhibited the progression of diethylnitrosamine-induced hepatocellular carcinoma in mice via the inactivation of nuclear transcription factor kappa-B

Hepatocellular carcinoma (HCC) is a major global health problem. Therapeutic interventions of HCC are still limited because of its complicated molecular pathogenesis. Many reports showed that renin-angiotensin system (RAS) contributes to the development of different types of malignancies. Therefore, the present study aimed to examine the effect of RAS inhibition using perindopril (1 mg/kg), fosinopril (2 mg/kg), or losartan (10 mg/kg) on diethylnitrosamine-induced HCC compared to sorafenib (30 mg/kg). The administration of RAS inhibitors resulted in improved liver function and histologic picture with a reduction in AFP levels. These effects found to be mediated through inactivation of NFкB pathway by the inhibition of NFĸB p65 phosphorylation at the Ser536 residue and inhibition of the phosphorylation-induced degradation of NFĸBia. Consequently, expression levels of cyclin D1 mRNA were significantly lowered. In addition, NFкB-induced TNF-α and TGF-β1 levels were reduced leading to lower levels of MMP-2 and VEGF. We concluded that RAS inhibition either through inhibiting the ACE or the blockade of AT1R has the same therapeutic benefit and that the tissue affinity of the ACEIs has no impact on its anti-tumor activity. These results suggest that ACEIs and ARBs can serve as promising candidates for further clinical trials in the management of HCC.

Emerging Roles of G Protein-Coupled Receptors in Hepatocellular Carcinoma

Among a great variety of cell surface receptors, the largest superfamily is G protein-coupled receptors (GPCRs), also known as seven-transmembrane domain receptors. GPCRs can modulate diverse signal-transduction pathways through G protein-dependent or independent pathways which involve β-arrestins, G protein receptor kinases (GRKs), ion channels, or Src kinases under physiological and pathological conditions. Recent studies have revealed the crucial role of GPCRs in the tumorigenesis and the development of cancer metastasis. We will sum up the functions of GPCRs—particularly those coupled to chemokines, prostaglandin, lysophosphatidic acid, endothelin, catecholamine, and angiotensin—in the proliferation, invasion, metastasis, and angiogenesis of hepatoma cells and the development of hepatocellular carcinoma (HCC) in this review. We also highlight the potential avenues of GPCR-based therapeutics for HCC.

The role of angiotensin II in cancer metastasis: Potential of renin-angiotensin system blockade as a treatment for cancer metastasis

Hypertension, which often exists as a comorbid condition in cancer patients, is considered as a factor affecting cancer progression. The renin-angiotensin system (RAS) plays an important role in the regulation of blood pressure, and angiotensin II (Ang II) is a well-known pressor peptide in RAS. There is also accumulated evidence indicating that Ang II plays a critical role in the metastasis of various cancers by modulating adhesion, migration invasion, proliferation, and angiogenesis. Consistent with this, large epidemiological studies have reported the potential beneficial effects of angiotensin-converting enzyme (ACE) inhibitors and Ang II type 1 receptor blockers (ARBs) against cancer metastasis; however, some of the results remain controversial. Although the precise Ang II-related mechanisms involved in cancer metastasis are not completely clear yet, a number of basic and meta-analytic studies have shown that ACE inhibitors and ARBs reduce the metastatic potential of tumors. In this review, we summarize the relationships among hypertension, RAS, and metastasis as demonstrated in basic and clinical studies. Finally, we discuss the possibility of using RAS inhibitors as anti-metastatic drugs.

Use of inhibitors of the renin-angiotensin system is associated with longer survival in patients with hepatocellular carcinoma

BACKGROUND

Inhibition of the renin-angiotensin system (RAS) was associated with longer survival in patients with different solid malignancies.

OBJECTIVE

The objective of this study was to investigate the effect of RAS inhibitor (RASi) treatment (angiotensin-converting enzyme inhibitors or angiotensin-II-receptor blockers) on survival of patients with hepatocellular carcinoma (HCC).

METHODS

Patients diagnosed with HCC and Child-Pugh A between 1992 and 2013 who received sorafenib, experimental therapy, or best supportive care were eligible for the Vienna cohort. The Mainz cohort included patients with HCC and Child-Pugh A who received sorafenib treatment between 2007 and 2016. The association between RASi and overall survival (OS) was evaluated in univariate and multivariate analyses.

RESULTS

In the Vienna cohort, 43 of 156 patients received RASi for hypertension. RASi treatment was associated with longer OS (11.9 vs. 6.8 months (mo); p = 0.014) and remained a significant prognostic factor upon multivariate analysis (HR = 0.6; 95% CI 0.4-0.9; p = 0.011). In subgroup analysis, patients treated with sorafenib plus RASi had better median OS (19.5 mo) compared to those treated with either sorafenib (10.9 mo) or RASi (9.7 mo) alone (p = 0.043). The beneficial effect of RASi on survival was confirmed in the Mainz cohort (n = 76).

CONCLUSION

RAS inhibition is associated with longer survival in HCC patients with Child-Pugh class A.

Noninvasive Assessment of Losartan-Induced Increase in Functional Microvasculature and Drug Delivery in Pancreatic Ductal Adenocarcinoma

PURPOSE: Losartan, an angiotensin II receptor blocker, can reduce desmoplasia and enhance drug delivery and efficacy through improving interstitial transport and vascular perfusion in pancreatic ductal adenocarcinoma (PDAC) models in mice. The purpose of this study was to determine whether magnetic resonance imaging (MRI) of magnetic iron oxide nanoparticles (MNPs) and micro–positron emission tomography (PET) measurements could respectively detect improvements in tumor vascular parameters and drug uptake in orthotopic PDAC in mice treated with losartan. METHOD AND MATERIALS: All experiments were approved by the local Institutional Animal Care and Use Committee. FVB mice with orthotopic PDAC were treated daily with an i.p. injection of losartan (70 mg/kg) or saline (control vehicle) for 5 days. In order to calculate the fractional blood volume, vessel size index, and vessel density index, MRI was performed at 4.7 T following the injection of 3 mg/kg iron ferumoxytol (i.v.). Dynamic PET images were also acquired for 60 minutes using an ¹⁸F-5FU tracer dose of 200 μCi and analyzed for time activity curves normalized to muscle. Statistical analyses compared both cohorts using an unpaired two-tailed t test. RESULTS: In comparison to the control treatment, the losartan administration significantly increased the fractional blood volume (mean ± SEM) [12.1 ± 1.7 (n = 19) vs 6.7 ± 1.1 (n = 20); P < .02] and vessel size index (128.2 ± 35.6 vs 57.5 ± 18; P < .05). Losartan also induced a significant increase in the intratumoral uptake of ¹⁸F-5FU by 53% (P < .0001). CONCLUSION: MRI using FDA-approved MNPs provides a noninvasive, translatable means of assaying microvascular parameters induced by losartan in pancreatic cancer. PET measurements demonstrated that losartan significantly increased the uptake of ¹⁸F-5FU.

Repurposing of approved cardiovascular drugs

Research and development of new drugs requires both long time and high costs, whereas safety and tolerability profiles make the success rate of approval very low. Drug repurposing, applying known drugs and compounds to new indications, has been noted recently as a cost-effective and time-unconsuming way in developing new drugs, because they have already been proven safe in humans. In this review, we discuss drug repurposing of approved cardiovascular drugs, such as aspirin, beta-blockers, angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, cardiac glycosides and statins. Regarding anti-tumor activities of these agents, a number of experimental studies have demonstrated promising pleiotropic properties, whereas all clinical trials have not shown expected results. In pathological conditions other than cancer, repurposing of cardiovascular drugs is also expanding. Numerous experimental studies have reported possibilities of drug repurposing in this field and some of them have been tried for new indications ('bench to bedside'), while unexpected results of clinical studies have given hints for drug repurposing and some unknown mechanisms of action have been demonstrated by experimental studies ('bedside to bench'). The future perspective of experimental and clinical studies using cardiovascular drugs are also discussed.

Angiotensin II stimulates melanogenesis via the protein kinase C pathway

Melanogenesis is a physiological process that results in the synthesis of melanin pigments, which serve a crucial function in hyperpigmentation. The aim of the present study was to determine the effects of angiotensin II (Ang II) on melanogenesis and to elucidate the molecular events of Ang II-induced melanogenesis. Experiments were performed on human melanocytes to elucidate the pigmenting effect of Ang II and the underlying mechanisms. The elements involved in melanogenesis, including melanin content, tyrosinase (TYR) activity, and microphthalmia-associated transcription factor (MITF) and TYR expression at the mRNA and protein levels were evaluated. Melanin content and TYR activity increased in response to Ang II treatment in a concentration-dependent manner. MITF and TYR mRNA and protein expression levels were increased significantly in response to Ang II in a concentration-dependent manner. The Ang II-induced increase in melanin synthesis was reduced significantly in response to co-treatment with Ro-32-0432, a protein kinase C (PKC) inhibitor, whereas co-treatment with H-89, a PKA inhibitor, did not attenuate the Ang II-induced increase in melanin levels. These results suggest that PKC is required for Ang II-induced pigmentation in human melanocytes and that the mechanism involves the PKC pathway and MITF upregulation.

Current Approaches for Improving Intratumoral Accumulation and Distribution of Nanomedicines

The ability of nanoparticles and macromolecules to passively accumulate in solid tumors and enhance therapeutic effects in comparison with conventional anticancer agents has resulted in the development of various multifunctional nanomedicines including liposomes, polymeric micelles, and magnetic nanoparticles. Further modifications of these nanoparticles have improved their characteristics in terms of tumor selectivity, circulation time in blood, enhanced uptake by cancer cells, and sensitivity to tumor microenvironment. These "smart" systems have enabled highly effective delivery of drugs, genes, shRNA, radioisotopes, and other therapeutic molecules. However, the resulting therapeutically relevant local concentrations of anticancer agents are often insufficient to cause tumor regression and complete elimination. Poor perfusion of inner regions of solid tumors as well as vascular barrier, high interstitial fluid pressure, and dense intercellular matrix are the main intratumoral barriers that impair drug delivery and impede uniform distribution of nanomedicines throughout a tumor. Here we review existing methods and approaches for improving tumoral uptake and distribution of nano-scaled therapeutic particles and macromolecules (i.e. nanomedicines). Briefly, these strategies include tuning physicochemical characteristics of nanomedicines, modulating physiological state of tumors with physical impacts or physiologically active agents, and active delivery of nanomedicines using cellular hitchhiking.

High Tumor Penetration of Paclitaxel Loaded pH Sensitive Cleavable Liposomes by Depletion of Tumor Collagen I in Breast Cancer

The network of collagen I in tumors could prevent the penetration of drugs loaded in nanoparticles, and this would lead to impaired antitumor efficacy. In this study, free losartan (an angiotensin inhibitor) was injected before treatment to reduce the level of collagen I, which could facilitate the penetration of nanoparticles. Then the pH-sensitive cleavable liposomes (Cl-Lip) were injected subsequently to exert the antitumor effect. The Cl-Lip was constituted by PEG(5K)-Hydrazone-PE and DSPE-PEG(2K)-R8. When the Cl-Lip reached to the tumor site by the enhanced permeability and retention (EPR) effect, PEG(5K)-Hydrazone-PE was hydrolyzed from the Cl-Lip under the low extra-cellular pH conditions of tumors, then the R8 peptide was exposed, and finally liposomes could be internalized into tumor cells by the mediation of R8 peptide. In vitro experiments showed both the cellular uptake of Cl-Lip by 4T1 cells and cytotoxicity of paclitaxel loaded Cl-Lip (PTX-Cl-Lip) were pH sensitive. In vivo experiments showed the Cl-Lip had a good tumor targeting ability. After depletion of collagen I, Cl-Lip could penetrate into the deep place of tumors, the tumor accumulation of Cl-Lip was further increased by 22.0%, and the oxygen distributed in tumor tissues was also enhanced. The antitumor study indicated free losartan in combination with PTX-Cl-Lip (59.8%) was more effective than injection with PTX-Cl-Lip only (37.8%) in 4T1 tumor bearing mice. All results suggested that depletion of collagen I by losartan dramatically increased the penetration of PTX-Cl-Lip and combination of free losartan and PTX-CL-Lip could lead to better antitumor efficacy of chemical drugs. Thus, the combination strategy might be a promising tactic for better treatment of solid tumors with a high level of collagen I.

Bone marrow mononuclear cell angiogenic competency is suppressed by a high-salt diet

Autologous bone marrow-derived mononuclear cell (BM-MNC) transplantation is a potential therapy for inducing revascularization in ischemic tissues providing the underlying disease process had not negatively affected BM-MNC function. Previously, we have shown that skeletal muscle angiogenesis induced by electrical stimulation is impaired by a high-salt diet (HSD; 4% NaCl) in Sprague-Dawley (SD) rats. In this study we tested the hypothesis that BM-MNC angiogenic function is impaired by an elevated dietary sodium intake. Following 1 wk on HSD, either vehicle or BM-MNCs derived from SD donor rats on HSD or normal salt diet (NSD; 0.4% NaCl) were injected into male SD rats undergoing hindlimb stimulation. Administration of BM-MNCs (intramuscular or intravenous) from NSD donors, but not HSD donors, restored the angiogenic response in HSD recipients. Angiotensin II (3 ng · kg(-1) · min(-1)) infusion of HSD donor rats restored angiogenic capacity of BM-MNCs, and treatment of NSD donor rats with losartan, an angiotensin II receptor-1 antagonist, inhibited BM-MNC angiogenic competency. HSD BM-MNCs and NSD losartan BM-MNCs exhibited increased apoptosis in vitro following an acute 6-h hypoxic stimulus. HSD BM-MNCs also had increased apoptosis following injection into skeletal muscle. This study suggests that BM-MNC transplantation can restore skeletal muscle angiogenesis and that HSD impairs the angiogenic competency of BM-MNCs due to suppression of the renin-angiotensin system causing increased apoptosis.

Use of ACE Inhibitors and Angiotensin Receptor Blockers and Primary Breast Cancer Outcomes

BACKGROUND

ACE inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) may have anti-tumor properties. We investigated whether the use of ACEI/ARBs affects the clinical outcomes of primary breast cancer patients receiving taxane and anthracycline-based neoadjuvant chemotherapy.

METHODS

We included 1449 patients with diagnosis of invasive primary breast cancer diagnosed at the MD Anderson Cancer Center between 1995 and 2007 who underwent neoadjuvant chemotherapy. Of them, 160 (11%) patients were identified by review of their medical record, as ACEI/ARBs users. We compared pathologic complete response (pCR) rates, relapse-free survival (RFS), disease-specific survival (DSS) and overall survival (OS) between ACEI/ARB users and non-users. Descriptive statistics and Cox proportional hazards model were used in the analyses.

RESULTS

There was no difference in the pCR rates between ACEI/ARB users and non-users (16% vs 18.1%, p-=0.50). After adjustment for important demographic and clinical characteristics, no significant differences between ACEI/ARB users and nonusers were observed in RFS (HR=0.81; 95% CI=0.54-1.21), DSS (HR=0.83; 95% CI=0.52-1.31), or OS (HR=0.91; 95% CI =0.61-1.37). In a subgroup analysis, the 5-year RFS was 82% in ARB only users versus 71% in ACEI/ARB non-users (P=0.03). In the multivariable analysis, ARB use was also associated with a decreased risk of recurrence (HR=0.35; 95% CI=0.14-0.86). No statistically significant differences in DSS or OS were seen.

CONCLUSION

No differences in pCR and survival outcomes were seen between ACEI/ARB users and non-users among breast cancer patients receiving neoadjuvant chemotherapy. ARB use may be associated with improved RFS. Further research is needed to validate this finding.

Angiotensin-converting enzyme and the tumor microenvironment: mechanisms beyond angiogenesis

The renin angiotensin system (RAS) is a network of enzymes and peptides that coalesce primarily on the angiotensin II type 1 receptor (AT1R) to induce cell proliferation, angiogenesis, fibrosis, and blood pressure control. Angiotensin-converting enzyme (ACE), the key peptidase of the RAS, is promiscuous in that it cleaves other substrates such as substance P and bradykinin. Accumulating evidence implicates ACE in the pathophysiology of carcinogenesis. While the role of ACE and its peptide network in modulating angiogenesis via the AT1R is well documented, its involvement in shaping other aspects of the tumor microenvironment remains largely unknown. Here, we review the role of ACE in modulating the immune compartment of the tumor microenvironment, which encompasses the immunosuppressive, cancer-promoting myeloid-derived suppressor cells, alternatively activated tumor-associated macrophages, and T regulatory cells. We also discuss the potential roles of peptides that accumulate in the setting of chronic ACE inhibitor use, such as bradykinin, substance P, and N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), and how they may undercut the gains of anti-angiogenesis from ACE inhibition. These emerging mechanisms may harmonize the often-conflicting results on the role of ACE inhibitors and ACE polymorphisms in various cancers and call for further investigations into the potential benefit of ACE inhibitors in some neoplasms.

Proteinuria predicts 10-year cancer-related mortality in patients with type 2 diabetes

BACKGROUND

We conducted a cohort study to determine if proteinuria predicts cancer-related mortality in type 2 diabetic subjects.

METHODS

Between July 1996 and June 2003, we enrolled 646 type 2 diabetic subjects. Participants were followed-up until December 31, 2008. The vital status was ascertained by linking records with computerized death certificates in Taiwan.

RESULTS

During a median follow-up of 10.4 years, 158 subjects had died, including 59 from cancers. Subjects with proteinuria had a hazard ratio (HR) of 2.77 (95% CI 1.82-4.21) for all-cause mortality and 1.99 (95% CI 1.00-3.94) for cancer-related mortality after adjustment for demographic factors and medical conditions. Specifically, proteinuria showed a trend of increased colon cancer death. The presence of proteinuria significantly improved the predictive ability of cancer-related mortality (increase in concordance statistics or area under the ROC curve=0.03). Patients with both proteinuria and estimated glomerular filtration rate <60 ml/min per 1.73 m² showed higher HR for all-cause mortality than patients with proteinuria only (adjusted HRs (95% CI), 4.01 (2.42-6.67) vs. 2.69 (1.51-4.79), both p<0.01).

CONCLUSIONS

Proteinuria can predict 10-year all-cause and cancer-related mortalities independently in type 2 diabetic subjects, over and above the established risk factors associated with type 2 diabetes.

[Angiotensin-2 type 1 receptors (AT1R) and cancers]

Recently, several meta-analysis suggested an increased risk of cancers linked to the use of antagonists of angiotensin-2 receptors or inhibitors of angiotensinogen converting enzyme. The results of epidemiological studies are conflicting. Meta-analysis as well as retrospective studies are not reliable and biased, since they have never been designed to explore any pro- or antitumoral effect. We lack of prospective studies that could take off the doubt on these drugs. Nevertheless, all experimental researches pointed out potent antitumoral properties. Indeed, direct antiproliferative and neo-angiogenic inhibition have been described on tumor cell cultures as well as on animal models. Moreover, we are convinced that the use of antagonists of angiotensin-2 receptors and inhibitors of angiotensinogen converting enzyme may be then of clinical use in the near future in association with classical antitumor drugs. In this review, we proposed to explore these data by a thorough analysis of recent literature associating epidemiological and experimental studies.

How does inhibition of the renin-angiotensin system affect the prognosis of advanced gastric cancer patients receiving platinum-based chemotherapy?

BACKGROUND

The renin-angiotensin system (RAS) is related to the regulation of cell proliferation, angiogenesis, and tumor progression.

PATIENTS AND METHODS

We retrospectively analyzed the effect of angiotensin I-converting enzyme inhibitors (ACEIs) and angiotensin II type-1 receptor blockers (ARBs) in 63 patients with advanced gastric cancer (AGC) with platinum-based chemotherapy. All patients analyzed had received medications for hypertension at the diagnosis of AGC. Patients were divided into two groups: an ACEI/ARB group (n = 30) and a non-ACEI/ARB group (n = 33).

RESULTS

Patient characteristics were not different between patients with and without ACEI/ARB. The response rate for all patients was 25.4% and the disease control rate was 77.8%. The median progression-free survival (PFS) for first-line chemotherapy was 5.5 months (95% CI 3.71-7.29) in the ACEI/ARB group and 4.3 months (95% CI 2.39-6.21) in the non-ACEI/ARB group (p = 0.506). There was a significant difference in overall survival (OS) in the ACEI/ARB group compared to the non-ACEI/ARB group (median OS: 8.2 vs. 13.9, p = 0.0095). In multivariate analysis, the use of ACEI/ARB was a significant independent prognostic factor for OS (p = 0.039) but not for PFS.

CONCLUSION

ACEI/ARB in combination with standard chemotherapy might improve survival in patients with AGC and hypertension. These results support further investigation into the anticancer effects of ACEL/ARB.

Inhibition of the renin-angiotensin system downregulates tissue factor and vascular endothelial growth factor in human breast carcinoma cells

INTRODUCTION

The renin-angiotensin system (RAS) promotes angiogenesis and growth of neoplastic cells. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor AT1 blockers may protect against cancer. Tissue factor (TF), for its involvement in tumor growth, angiogenesis, and metastasis is considered a hallmark of cancer progression. In this study we evaluated whether RAS blockade modulates TF constitutive expression by the metastatic breast carcinoma MDA-MB-231 cell line.

MATERIALS AND METHODS

Cell TF activity was assessed by one stage clotting time, TF and VEGF antigens and mRNA levels by ELISA and RT-PCR, respectively. AT(1) was detected by flow-cytometry and angiotensin-II levels by EIA.

RESULTS

Captopril reduced in a concentration-dependent way both the strong constitutive TF activity (983.2±55.2 vs. 686.7±135.1U/5×10(5) cells with 10μg/ml captopril) and antigen (32.3±5.9 vs. 13.2±6.6ng/ml) in MDA-MB-231. Similar results were observed with enalapril. AT1 was present on cell membrane and losartan, a competitive inhibitor of AT1, reduced TF expression to a degree similar as that exerted by ACE inhibitors. Moreover, captopril and losartan downregulated the constitutive mRNA TF expression by ~35%. Similar results were observed with anti-AT1 and angiotensin II antibodies. In addition, the constitutive VEGF antigen and mRNA levels were reduced in the presence of captopril or losartan, and an anti-VEGF antibody downregulated cell TF activity by ~40%.

CONCLUSIONS

These results could, at least in part, contribute to the discussion about the possible effects of ACE inhibitors and AT1 receptor antagonists in malignancy, and offer new clues to support their use for tumor control.

Critical review of cancer risk associated with angiotensin receptor blocker therapy

The role of drugs in new cancer occurrence and cancer-related death is a major concern. Recently, a meta-analysis raised the possibility that angiotensin receptor blockers (ARBs) might have an adverse effect on patients. This generated a significant debate until the publication of two further meta-analyses, neither of which demonstrated an increased risk of new cancer occurrence or cancer-related death with the use of ARBs in patients with hypertension, heart failure, and/or nephropathy. This illustrates that the results of meta-analyses should be interpreted cautiously and critically as bias, such as selection bias, might lead to erroneous conclusions. Overall, the bulk of evidence today indicates that ARBs are not associated with increased cancer risk.

Angiotensin receptor blockade and risk of cancer in type 2 diabetes mellitus: a nationwide case-control study

PURPOSE

The objective of this case-control study was to evaluate the risk of malignancy in diabetic patients who received angiotensin receptor blockers (ARBs).

PATIENTS AND METHODS

A total of 21,750 new diabetic patients who started antihypertensive treatment were identified from the Taiwan National Health Insurance claims database during the period from July 1, 2000, to December 31, 2000. As of December 31, 2007, patients with incident cancer were included as cases and up to four age- and sex-matched controls were selected by risk-set sampling. Logistic regression models were applied to estimate the odds ratios (ORs) and 95% CIs between ARB use and cancer incidence, adjusted for other types of antihypertensive drugs, insulin, oral hypoglycemic agents, statins, and underlying diseases.

RESULTS

Among the 1,281 patients with incident cancer and 5,104 controls, 333 (26.0%) and 1,341 (26.3%), respectively, received ARBs (OR, 0.98; 95% CI, 0.85 to 1.14). There was no statistically significant association between the effect of ARBs as a class and cancer incidence after adjustment for covariates (OR, 0.94; 95% CI, 0.80 to 1.10). Among the individual ARBs, losartan decreased the risk (OR, 0.78; 95% CI, 0.63 to 0.97) and candesartan (OR, 1.79; 95% CI, 1.05 to 3.06) and telmisartan (OR, 1.54; 95% CI, 0.97 to 2.43) possibly increased the risk of occurrence of malignancy.

CONCLUSION

The results did not show an effect of ARBs as a class on increasing cancer incidence in patients with diabetes. However, there was a negative association of losartan but a positive one of candesartan and telmisartan with the overall occurrence of cancer. The underlying mechanism certainly requires further investigation.

Angiotensin receptor blockers and angiogenesis: clinical and experimental evidence

Angiotensin II type 1 receptor antagonists [ARBs (angiotensin receptor blockers)] are indicated for BP (blood pressure)-lowering, renal protection and cardioprotection in patients unable to tolerate ACEIs (angiotensin-converting enzyme inhibitors). A recent meta-analysis revealed an association between ARBs and tumour development, possibly due to enhancement of angiogenesis. However, published evidence is conflicting on the effects of ARBs on angiogenesis or the expansion of the existing vascular network. ARBs have been shown to exert primarily anti-angiogenic effects in basic science studies of cancer, retinopathy, peripheral artery disease and some models of cardiovascular disease. In animal and cellular models of myocardial infarction and stroke, however, ARB administration has been associated with robust increases in vascular density and improved recovery. The aim of the present review is to examine the angiogenic effects of ARBs in animal and cellular models of relevant disease states, including proposed molecular mechanisms of action of ARBs and the clinical consequences of ARB use.

Losartan inhibits collagen I synthesis and improves the distribution and efficacy of nanotherapeutics in tumors

The dense collagen network in tumors significantly reduces the penetration and efficacy of nanotherapeutics. We tested whether losartan--a clinically approved angiotensin II receptor antagonist with noted antifibrotic activity--can enhance the penetration and efficacy of nanomedicine. We found that losartan inhibited collagen I production by carcinoma-associated fibroblasts isolated from breast cancer biopsies. Additionally, it led to a dose-dependent reduction in stromal collagen in desmoplastic models of human breast, pancreatic, and skin tumors in mice. Furthermore, losartan improved the distribution and therapeutic efficacy of intratumorally injected oncolytic herpes simplex viruses. Finally, it also enhanced the efficacy of i.v. injected pegylated liposomal doxorubicin (Doxil). Thus, losartan has the potential to enhance the efficacy of nanotherapeutics in patients with desmoplastic tumors.

Angiotensin-2 receptors (AT1-R and AT2-R), new prognostic factors for renal clear-cell carcinoma?

Background:

The growth factor Angiotensin-2 signals through Angiotensin receptor type 1 (AT1-R) in a broad range of cell types and tumours and through the type-2 receptor (AT2-R) in a more restricted group of cell types. Although numerous forms of cancer have been shown to overexpress AT1-R, expression of AT1-R and AT2-R by human renal clear-cell carcinoma (RCCC) is not well understood. In this study, the expression of both angiotensin receptors was quantified in a retrospective series of RCCC and correlated with prognostic factors.

Methods:

Angiotensin receptor type 1 and AT2-R expressions were quantified on tumour tissues by immunohistochemistry (IHC), western blot and quantitative reverse transcriptase PCR (qRT–PCR). IHC results were correlated to Fuhrman's grade and patient progression-free survival (PFS).

Results:

A total of 84 RCCC were analysed. By IHC, AT1-R and AT2-R were expressed to a greater level in high-grade tumours (AT1-R: P<0.001, AT2-R: P<0.001). Univariate analysis showed a correlation between PFS and AT1-R or AT2-R expression (P=0.001). By multivariate analysis, only AT2-R expression correlated with PFS (HR 1.021, P=0.006) and cancer stage (P<0.001). By western blot, AT1-R and AT1-R were also found to be overexpressed in higher Fuhrman's grade (P<0.01 and P=0.001 respectively). By qRT–PCR, AT1-R but not AT2-R mRNA were downregulated (P=0.001 and P=0.118, respectively).

Conclusion:

Our results show that AT1-R and AT2-R proteins are overexpressed in the most aggressive forms of RCCC and that AT2-R expression correlates with PFS. AT1-R or AT2-R blockage could, therefore, offer novel directions for anti-RCCC therapy.

The renin-angiotensin system and cancer: old dog, new tricks

For cancers to develop, sustain and spread, the appropriation of key homeostatic physiological systems that influence cell growth, migration and death, as well as inflammation and the expansion of vascular networks are required. There is accumulating molecular and in vivo evidence to indicate that the expression and actions of the renin-angiotensin system (RAS) influence malignancy and also predict that RAS inhibitors, which are currently used to treat hypertension and cardiovascular disease, might augment cancer therapies. To appreciate this potential hegemony of the RAS in cancer, an expanded comprehension of the cellular actions of this system is needed, as well as a greater focus on translational and in vivo research.

Angiogenesis and melanoma

Angiogenesis occurs in pathological conditions, such as tumors, where a specific critical point in tumor progression is the transition from the avascular to the vascular phase. Tumor angiogenesis depends mainly on the release by neoplastic cells of growth factors specific for endothelial cells, which are able to stimulate the growth of the host's blood vessels. This article summarizes the literature concerning the relationship between angiogenesis and human melanoma progression. The recent applications of antiangiogenic agents which interfere with melanoma progression are also described.