Old antihypertensives as novel antineoplastics: angiotensin-I-converting enzyme inhibitors and angiotensin II type 1 receptor antagonists

Angiotensin I-converting enzyme gene plays a crucial role in the pathology of carcinomas in colorectal cancer

Angiotensin I-Converting Enzyme (ACE, CD143) Gene plays a crucial role in the pathology of carcinomas in many cancers including colorectal cancer (CRC). However, the methylation of ACE was rarely reported. In this study, our purpose was to investigate the methylation status of ACE and explored its prognostic value in CRC. The expression of ACE was detected by quantitative real-time polymerase chain reaction (qRT-PCR) analysis while the methylation status of ACE was measured via methylation-specific polymerase chain reaction (MSP). The result demonstrated that ACE expression was up-regulated in tumour tissues and HT-29 cells compared with the controls. ACE was also confirmed to be hypomethylated in CRC. Next, we evaluated the influence of ACE hypomethylation on cell growth. It was proved to be a favourable factor for the cell proliferation, cell colony forming, but an inhibitor for the cell apoptosis of CRC cells according to MST assay, colony forming assay and flow cytometry assay. ACE hypomethylation was also considered to be related to the prognosis of CRC through Cox regression analysis. Taken together, the over-expression of ACE was regulated by its hypomethylation and the ACE hypomethylation might be an independent prognostic indicator in CRC.

Angiotensin-Converting Enzyme Gene Deletion Polymorphism is Associated with Lymph Node Metastasis in Colorectal Cancer Patients in a Chinese Population

Background

The purpose of this study was to assess the effect of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism on the risk of lymph node metastasis (LNM) in colorectal cancer (CRC) patients.

Material/Methods

We enrolled 146 CRC patients and 106 healthy controls in this study. ACE gene I/D polymorphism was genotyped by polymerase chain reaction (PCR). Hardy-Weinberg equilibrium (HWE) was used to assess the goodness of fit of the genotypes. χ² test was used to calculate the differences of genotype and allele distributions. Odds ratios (ORs) with corresponding 95% confidence intervals (95% CIs) were used to analyze the association between ACE I/D polymorphism and LNM in CRC patients.

Results

Insertion/deletion (ID) and deletion/deletion (DD) genotypes were frequently observed in CRC patients, but only DD genotype and D allele were related to the susceptibility of CRC (P=0.038, OR=2.158, 95%CI=1.039–4.480; P=0.026, OR=1.501, 95%CI=1.048–2.150). DD genotype and D allele also increased the risk of LNM in CRC patients (P=0.028, OR=2.844, 95%CI=1.107–7.038; P=0.026, OR=1.692, 95%CI=1.063–2.693).

Conclusions

DD genotype and D allele of ACE gene I/D polymorphism might increase the risk of LNM in CRC patients.

Potential of telmisartan in the treatment of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a common health problem in ageing men. This study was carried out to investigate the protective effect of telmisartan on testosterone-induced BPH in rats. Fifty-four male Wistar rats (200-250 g) were randomly divided into nine groups (n = 6) and orally treated for 28 consecutive days: group 1 - vehicle normal, olive oil (10 mL/kg); group 2 - BPH model control (10 mL/kg); groups 3-5 - telmisartan (5, 10 or 20 mg/kg, respectively); group 6 - pioglitazone (20 mg/kg); group 7 - celecoxib (20 mg/kg); group 8 - combination of telmisartan (5 mg/kg) and pioglitazone (20 mg/kg); group 9 - combination of telmisartan (5 mg/kg) and celecoxib (20 mg/kg). Animals in groups 2-9 were given testosterone propionate in olive oil (3 mg/kg) subcutaneously 15 min after pretreatments. On day 29, blood was collected for the estimation of serum testosterone and prostate-specific antigen (PSA). The prostates were excised, weighed and subjected to biochemical and histological studies. Testosterone injection induced significant increase in prostatic index, serum testosterone and PSA suggesting BPH as well as increased prostate oxidative stress which were ameliorated with the pretreatment of rats with telmisartan or co-administration of celecoxib and pioglitazone. Histological examination showed that testosterone disrupted the morphology of the prostate epithelial cells evidenced in the involution of the epithelial lining of the acini into the lumen indicating BPH which was reversed by telmisartan. Findings from this study showed that telmisartan alone or in combination with pioglitazone prevented the development of testosterone-induced prostatic hyperplasia.

Up-Regulation of Angiotensin-Converting Enzyme (ACE) Enhances Cell Proliferation and Predicts Poor Prognosis in Laryngeal Cancer

Background

The angiotensin-converting enzyme (ACE, CD143) gene plays a crucial role in the pathology of many cancers. Previous studies mostly focused on the gene polymorphism, but the other functions of ACE have rarely been reported. The purpose of this study was to investigate the expression of ACE and its biological function, as well as its prognostic value, in laryngeal cancer.

Material/Methods

The expression of ACE was detected by quantitative real-time polymerase chain reaction (qRT-PCR) analysis in 106 patients with laryngeal cancer and 85 healthy people. Then the cell proliferation was estimated after the cell lines Hep-2 were transfected with pGL3-ACE and empty vector, respectively. In addition, the relationship between ACE expression and clinicopathologic characteristics was analyzed. Finally, Kaplan-Meier analysis was used to evaluate the overall survival of patients with different ACE expression, while Cox regression analysis was conducted to reveal the prognostic value of ACE in laryngeal cancer.

Results

Our results demonstrate that ACE is over-expressed in laryngeal cancer and thus promotes cell proliferation. The up-regulation of ACE was significantly influenced by tumor stage and lymph node metastasis. Patients with high ACE expression had a shorter overall survival compared with those with low ACE expression according to Kaplan-Meier analysis. The ACE gene was also found to be an important factor in the prognosis of laryngeal cancer.

Conclusions

Our study shows that the ACE gene was up-regulated, which promoted the cell proliferation, and it could be an independent prognostic marker in laryngeal cancer.

Experimental and DFT characterization, antioxidant and anticancer activities of a Cu(II)-irbesartan complex: structure-antihypertensive activity relationships in Cu(II)-sartan complexes

The coordination compound of the antihypertensive ligand irbesartan (irb) with copper(II) (CuIrb) was synthesized and characterized by FTIR, FT-Raman, UV-visible, reflectance and EPR spectroscopies. Experimental evidence allowed the implementation of structural and vibrational studies by theoretical calculations made in the light of the density functional theory (DFT). This compound was designed to induce structural modifications on the ligand. No antioxidant effects were displayed by both compounds, though CuIrb behaved as a weak 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(·)) scavenger (IC50 = 425 μM). The measurements of the contractile capacity on human mesangial cell lines showed that CuIrb improved the antihypertensive effects of the parent medication. In vitro cell growth inhibition against prostate cancer cell lines (LNCaP and DU 145) was measured for CuIrb, irbesartan and copper(II). These cell lines have been selected since the angiotensin II type 1 (AT1) receptor (that was blocked by the angiotensin receptor blockers, ARB) has been identified in them. The complex exerted anticancer behavior (at 100 μM) improving the activity of the ligand. Flow cytometry determinations were used to determine late apoptotic mechanisms of cell death. Experimental and DFT characterization of an irbesartan copper(II) complex has been performed. The complex exhibits low scavenging activity against DPPH(·) and significant growth inhibition of LNCaP and DU 145 prostate cancer cell lines. Flow cytometry determinations were used to determine late apoptotic mechanisms of cell death. This compound improved the antihypertensive effect of irbesartan. This effect was observed earlier for the mononuclear Cu-candesartan complex, but not in structurally modified sartans forming dinuclear or octanuclear Cu-sartan compounds.

Candesartan attenuates angiogenesis in hepatocellular carcinoma via downregulating AT1R/VEGF pathway

Angiotensin II type 1 receptor (AT1R) was reported to express in many types of tumors, promoting tumor growth and angiogenesis. We herein examined AT1R expression in liver cancer and the potential antitumor effects of AT1R antagonist Candesartan in liver cancer. We found that AT1R expression was positively correlated with VEGF-A expression and microvascular density (MVD) in 40 HCC patients. Angiotensin II and Candesartan neither had effects on the proliferation of liver cancer cells in vitro. However, Angiotensin II upregulated AT1R protein expression and promoted production of VEGF-A in liver cancer cells in a dose-dependent manner. Candesartan was able to reverse this process in a dose-dependent manner. Moreover, Candesartan downregulated the expression of VEGF-A in SMMC-7721 bearing xenografts in mice and inhibited tumor growth and angiogenesis in vivo. Our data suggested that AT1R antagonist Candesartan might be useful to suppress liver cancer by inhibiting angiogenesis.

Renin-angiotensin system expression in the K562 human erythroleukaemic cell line

Local renin-angiotensin system (RAS) may affect leukaemic cell production within the bone marrow microenvironment.Angiotensin-converting enzyme (ACE), renin, and angiotensin could influence leukaemogenesis. In this study, mRNA expressions of the major RAS components (ACE, renin, and angiotensinogen) in K562 human erythroleukaemia cell line have been searched by Real Time quantitative polymerase chain reaction. K562 blasts are multipotential, haematopoietic malignant cells that spontaneously differentiate into recognisable progenitors of the erythrocyte, granulocyte and monocytic series.We observed significant expressions of ACE, renin, and angiotensinogen in K562 leukaemic blast cells.Therefore, K562 human erythroleukaemia cell line may serve as an in vitro model to elucidate the role of RAS in leukaemia and to test the effects of RAS-affecting drugs on leukaemic cellular proliferation.

Insertion/Deletion Polymorphism of the Angiotensin I-Converting Enzyme Gene in Patients with Breast Cancer and Effects on Prognostic Factors

The aims of the present study were to investigate the distribution of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene in breast cancer patients and the association between ACE genotypes and clinicopathologic features, as well as their effects on prognosis. We assessed the I/D polymophism of the ACE gene by using polymerase chain reaction from peripheral blood in breast cancer and healthy age-matched women. The clinicopathologic parameters of breast cancer patients were obtained from medical records. Of the 57 patients, 31 (54.4%) had DD, 24 (42.1%) had ID, and 2 (3.5%) had II genotypes. In control subjects, 33 (63.5%) had DD, 12 (23.1%) had ID, and 7 (13.4%) had II genotypes. The ID genotype was seen more commonly in breast cancer patients (p = .03). When the combination of ID and II genotypes was used as a reference group, the DD genotype was associated with negative hormone receptor status (p = .003), tumor size (p = .054), and lymph node involvement (p = .07) but not histologic high grade and c-erb B2 overexpression. These results suggest that the DD genotype may accompany poor prognostic factors and influence the tumor course.

Associations of the Insertion/Deletion Polymorphism in the ACE Gene and Risk of Gastric Cancer: A Meta-Analysis

BACKGROUND

Reported associations of ACE polymorphisms with gastric cancer have been inconsistent, prompting a meta-analysis of 12 published case-control studies where we estimated risk (odds ratio [OR]).

METHODS

We searched MEDLINE through PubMed and EMBASE for suitable articles that had case-control design with gastric cancer as outcome. In this meta-analysis, our overall findings were subjected to modifier analyses (outlier and sensitivity treatments). We also performed subgroup analysis based on ethnicity (German and Japanese) and histological subtype (intestinal and diffuse).

RESULTS

Significance of the protective effects among homozygote carriers of the II genotype (OR 0.54-0.63, P = 0.01-0.02) disappeared with outlier analysis (OR 0.81-0.88, P = 0.12-0.14). Among DD homozygotes, this treatment altered the direction of association from weak protection (OR 0.95-0.96, P = 0.79-0.82) to increased risk (OR 1.13-1.19, P = 0.14-0.16). No significant associations were observed among ID genotype carriers (OR 0.91-0.94, P = 0.69-0.72). Japanese pooled effects varied across the genotype comparisons (OR 0.93-1.06, P = 0.54-0.72). Sensitivity treatment demonstrated robustness of the II genotype, but not the other two, both in overall and subgroup analyses. Histological subtype analysis yielded protection from intestinal cancer across the comparisons (OR 0.38-0.71, P = 0.15-0.50) but variable results for the diffuse type (OR 0.59-1.32, P = 0.19-0.92).

CONCLUSION

In summary, carriers of the ACE II genotype appear to be protected from gastric cancer, regardless of ethnicity or tumor type.

Lack of any association between insertion/deletion (I/D) polymorphisms in the angiotensin-converting enzyme gene and digestive system cancer risk: a meta-analysis

OBJECTIVE

To investigate the association between the gene polymorphisms of angiotensin-converting enzyme (ACE) and digestive system cancer risk.

METHOD

A search was performed in Pubmed, Medline, ISI Web of Science and Chinese Biomedical (CBM) databases, covering all studies until Sep 1st, 2013. Statistical analysis was performed by using Revman5.2 and STATA 12.0.

RESULTS

A total of 15 case-control studies comprising 2,390 digestive system cancer patients and 9,706 controls were identified. No significant association was found between the I/D polymorphism and digestive cancer risk (OR =0.93, 95%CI = (0.75, 1.16), P =0.53 for DD+DI vs. II). In the subgroup analysis by ethnicity and cancer type, no significant associations were found for the comparison of DD+DI vs. II. Results from other comparative genetic models also indicated a lack of associations between this polymorphism and digestive system cancer risks.

CONCLUSIONS

This meta-analysis suggested that the ACE D/I polymorphism might not contribute to the risk of digestive system cancer.

Local Renin-Angiotensin system in normal hematopoietic and multiple myeloma-related progenitor cells

Objective: The prominent functions of the local renin-angiotensin system (RAS) in primitive hematopoiesis further support the hypothesis that local autocrine bone marrow RAS could also be active in neoplastic hematopoiesis. The aim of this study is to examine critical RAS elements in normal CD34+ hematopoietic stem cells and multiple myeloma (MM)-related progenitor cells.

Materials and Methods: The study group comprised the total bone marrow cells (CBM) of 10 hematologically normal people, the CD34+ stem cell samples (CD34+CBM) of 9 healthy donors for allogeneic peripheral stem cell transplantation, and the CD34+ stem cell samples (CD34+MM) of 9 MM patients undergoing autologous peripheral stem cell transplantation. We searched for the gene expression of the major RAS components in healthy hematopoietic cells and myeloma cells by quantitative real-time polymerase chain reaction analysis.

Results: RENIN, angiotensinogen (ANGTS), and angiotensin converting enzyme-I (ACE I) mRNA expression levels of CBM were significantly higher than those in myeloma patients (p=0.03, p=0.002, and p=0.0008, respectively). Moreover, RENIN and ANGTS mRNA expression levels were significantly higher in CD34+ stem cell samples of healthy allogeneic donors compared to those in myeloma patients (p=0.001 and p=0.01). However, ACE I expression levels were similar in CD34+CBM and CD34+MM hematopoietic cells (p=0.89).

Conclusion: Although found to be lower than in the CBM and CD34+CBM hematopoietic cells, the local RAS components were also expressed in CD34+MM hematopoietic cells. This point should be kept in mind while focusing on the immunobiology of MM and the processing of autologous cells during the formation of transplantation treatment protocols.

Olmesartan potentiates the anti-angiogenic effect of sorafenib in mice bearing Ehrlich's ascites carcinoma: role of angiotensin (1-7)

Local renin-angiotensin systems exist in various malignant tumor tissues; this suggests that the main effector peptide, angiotensin II, could act as a key factor in tumor growth. The underlying mechanisms for the anti-angiogenic effect of angiotensin II type 1 receptor blockers need to be further evaluated. The present study was carried out to investigate the anti-angiogenic effect of olmesartan alone or in combination with sorafenib, an angiotensin (1–7) agonist or an angiotensin (1–7) antagonist in Ehrlich's ascites carcinoma-bearing mice. The tumor was induced by intradermal injection of Ehrlich's ascites carcinoma cells into mice. Tumor discs were used to evaluate the microvessel density; the serum levels of vascular endothelial growth factor (VEGF) and serum insulin-like growth factor I (IGF-I); and their intratumoral receptors, VEGF receptor-2 and IGF-I receptor, respectively. All parameters were determined following the treatment course, which lasted for 21 days post-inoculation. Monotherapy with olmesartan and its combination with sorafenib resulted in a significant reduction in microvessel density and serum levels of VEGF and IGF-I, as well as their intratumoral receptors. In addition, the combination of olmesartan (30 mg/kg) with an angiotensin (1–7) agonist reduced the microvessel density, IGF-I serum levels and the levels of its intratumoral receptor. In conclusion, olmesartan reduced the levels of the angiogenesis markers IGF-I and VEGF and down-regulated the intratumoral expression of their receptors in a dose-dependent manner, and these effects were dependent on the angiotensin (1–7) receptor. These results suggest that olmesartan is a promising adjuvant to sorafenib in the treatment of cancer.

Local bone marrow renin-angiotensin system in primitive, definitive and neoplastic haematopoiesis

The locally active ligand peptides, mediators, receptors and signalling pathways of the haematopoietic BM (bone marrow) autocrine/paracrine RAS (renin-angiotensin system) affect the essential steps of definitive blood cell production. Haematopoiesis, erythropoiesis, myelopoiesis, formation of monocytic and lymphocytic lineages, thrombopoiesis and other stromal cellular elements are regulated by the local BM RAS. The local BM RAS is present and active even in primitive embryonic haematopoiesis. ACE (angiotensin-converting enzyme) is expressed on the surface of the first endothelial and haematopoietic cells, forming the marrow cavity in the embryo. ACE marks early haematopoietic precursor cells and long-term blood-forming CD34(+) BM cells. The local autocrine tissue BM RAS may also be active in neoplastic haematopoiesis. Critical RAS mediators such as renin, ACE, AngII (angiotensin II) and angiotensinogen have been identified in leukaemic blast cells. The local tissue RAS influences tumour growth and metastases in an autocrine and paracrine fashion via the modulation of numerous carcinogenic events, such as angiogenesis, apoptosis, cellular proliferation, immune responses, cell signalling and extracellular matrix formation. The aim of the present review is to outline the known functions of the local BM RAS within the context of primitive, definitive and neoplastic haematopoiesis. Targeting the actions of local RAS molecules could represent a valuable therapeutic option for the management of neoplastic disorders.

Polymorphism of angiotensin I-converting enzyme gene is related to oral cancer and lymph node metastasis in male betel quid chewers

OBJECTIVES

Angiotensin I-converting enzyme (ACE), a type I cell surface zinc metallopeptidase, is differentially expressed in several malignancies and plays a role in tumor cell proliferation, tumor cell migration, angiogenesis, and metastatic behavior. We aimed to investigate the effects of ACE gene (rs1799752) variants on oral cancer risk.

MATERIALS AND METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) 32 was used to measure ACE gene polymorphisms in 88 patients with oral precancerous lesion (OPL), 186 33 patients with oral cancer, and 120 control subjects without any oral lesions. All study subjects were male 34 betel quid chewers.

RESULTS

Patients with oral cancer or OPL had a higher frequency of the DD genotype than the control patients did. Oral cancer patients with the DD genotype had a significantly higher prevalence of lymph node metastases than patients with the II/ID genotype did. After adjusting for age, smoking, drinking, and betel quid chewing status, we found that individuals with the DD genotype of the ACE gene had a 5.46-fold and 3.13-fold higher risk of developing oral cancer or OPL, respectively, than those with the II genotype did. Furthermore, oral cancer patients with the DD genotype of the ACE gene had a 2.16-fold higher likelihood of lymph node metastasis.

CONCLUSION

Our data suggest that the ACE gene polymorphisms may be associated with increased susceptibility to OPL and oral cancer and lymph node metastasis from oral cancer.

The association between ACE polymorphism and risk of colorectal cancer in a Chinese population

OBJECTIVES

Angiotensin I-converting enzyme (ACE) plays crucial roles not only in the regulation of circulatory homeostasis but also in the pathology of carcinomas. An insertion-deletion (I/D) polymorphism in intron 16 of ACE gene was identified to be functional. We aimed to investigate the association between ACE I/D polymorphism and risk of colorectal cancer (CRC).

DESIGN AND METHODS

Using genomic DNA from 241 CRC patients and 299 control subjects, we genotyped the ACE I/D polymorphism using a polymerase chain reaction analysis.

RESULTS

We found that patients carrying the D allele were associated with an increased risk of developing poorly differentiated cancer and metastasis compared with those carrying the I allele (OR=1.54, 95%CI, 1.04-2.28; OR=1.56, 95%CI, 1.08-2.26, respectively), although no significant association was observed between cases and controls in overall analysis.

CONCLUSIONS

These findings indicate that the ACE I/D polymorphism is likely to play a role in CRC progression.

Insertion/deletion polymorphism of angiotensin I-converting enzyme gene is linked with chromophobe renal cell carcinoma

OBJECTIVES

To study the putative significance of angiotensin I-converting enzyme (ACE) in renal cell carcinoma (RCC). Recent evidence has suggested that a 287-base pair insertion (I)/deletion (D) polymorphism (rs4646994) of the angiotensin I-converting enzyme (ACE) might be associated with cancer risk and progression.

METHODS

The present case-control study accrued 383 subjects, including 210 with RCC and 173 age- and sex-matched healthy individuals without evidence or a history of cancer. Genomic DNA was extracted from the peripheral blood leukocytes. The ACE fragment containing the polymorphism was amplified using conventional polymerase chain reaction using specific primer pairs and subsequently genotyped using agarose gel electrophoresis.

RESULTS

Overall, a DD genotype and D allele were more frequently noted in the patients with RCC than in the controls (P = .042 and P = .045, respectively), and resulted from a greater frequency of DD and D in chromophobe RCC (P = .023 and P = .020, respectively). In contrast, the genotype and allele distribution of the controls and patients with papillary or clear cell RCC was similar. The II genotype was not observed in any patient with chromophobe RCC. On multivariate logistic regression analysis, the ACE genotype was an independent risk factor for chromophobe RCC (P = .012). Neither the ACE genotypes or alleles were associated with the tumor stage or grade.

CONCLUSIONS

The results of the present study have shown for the first time that the ACE insertion/deletion gene polymorphism rs4646994 might be linked with the development of chromophobe RCC. Neither the ACE genotypes nor the alleles were associated with RCC progression.

Angiotensin II receptor blockers and risk of cancer in patients with systemic hypertension

Recently, concerns have been raised that angiotensin II receptor blockers (ARBs) may be associated with an increased risk for cancer development. However, the relation between ARBs and cancer is still unclear. Therefore, a nationwide population-based study was conducted to investigate the possible influence of ARBs on the occurrence of new cancers in patients with hypertension by using the Taiwan National Health Insurance database. A total of 109,002 patients with newly diagnosed hypertension were identified from a cohort database of 1 million individuals from January 1, 1998, to December 31, 2006. Among them, 40,124 (36.8%) had received ARBs for hypertension. The end point was the development of any type of cancer before the end of 2007. During an average of 5.7 ± 2.6 years of follow-up, a total of 9,067 cases of new cancer occurrence were observed. The log-rank test showed that the occurrence rate of newly diagnosed cancers in the subjects receiving ARBs was significantly lower than those receiving treatment without ARBs (ARBs vs controls 3,082 vs 5,985, p <0.001). After adjusting for age, gender, co-morbidities, and medications for hypertension control, ARB use was found to be independently associated with a decreased risk for cancer occurrence (hazard ratio 0.66, 95% confidence interval 0.63 to 0.68, p <0.001). In conclusion, long-term use of ARBs is associated with a lower incidence of cancer occurrence, thereby suggesting that ARBs may prevent cancer development.

Expression and function of ATIP/MTUS1 in human prostate cancer cell lines

BACKGROUND

We have previously demonstrated Ang II type 2 (AT(2)-) receptor-mediated inhibition of EGF-induced prostate cancer cell growth in androgen-dependent (LNCaP) and independent (PC3) prostate cancer cell lines.

METHODS

To explore the signaling pathways involved in this inhibitory effect, we examined the interaction of the AT(2)-receptor with its novel regulatory partner ATIP using real time PCR, over-expression, siRNA and [(3)H]thymidine incorporation assays.

RESULTS

The results in human prostate cancer cell lines demonstrate the presence of ATIP in both cell lines examined, and suggest that (i) the AT(2)-receptor through an interaction with ATIP mediates an anti-growth factor effect in both androgen-dependent and androgen-independent cell lines; (ii) ATIP expression decreases as the rate of cell growth and androgen-independence increase; and (iii) EGF may act on cell growth in part by reducing the content of ATIP present in the cells.

CONCLUSIONS

The results support our earlier proposal in normal cell lines that ATIP is an important component of the cellular response to AT(2)-receptor activation. The results further suggest that a critical level of ATIP is required to mediate the effect of AT(2)-receptor activation to inhibit EGF mediated increases in cell growth. They also suggest that EGF may in part induce cell growth by suppressing the level of ATIP expression.

Review: Pathobiological aspects of the local bone marrow renin-angiotensin system: a review

The local haematopoietic bone marrow (BM) renin—angiotensin system (RAS) mediates pathobiological alterations of haematopoiesis in an autocrine/paracrine/intracrine fashion. Recent data further indicated the existence of angiotensin-converting enzyme (ACE) in human primitive lympho-haematopoietic cells, embryonic, foetal and adult haematopoietic tissues. Human umbilical cord blood cells also express renin, angiotensinogen, and ACE mRNAs. As ACE and other angiotensin peptides function in human haematopoietic stem cells (HSCs) throughout haematopoietic ontogeny and adulthood, local RAS could also have a function in HSC plasticity, and the development of haematological neoplastic disorders. The presence of ACE on leukaemic blast cells within leukaemic BM, on erythroleukaemic cells, ACE-expressing macrophages in lymph nodes of Hodgkin disease, renin activity in leukaemic blasts, angiotensin II as an autocrine growth factor for AML, increased renin gene activity during NUP98-HOXA9 enhanced blast formation, higher levels of BB9/ACE (+) AML isoforms, and altered JAK-STAT pathway as a link between RAS and leukaemia indicated the wide pathobiological aspects of local BM RAS. The comparable biological actions of local RASs throughout the human body (including myocardium, pancreas, pituitary gland, ovary and kidney) represent the true basis for the search of their prominence in tissue functions. Recent data and perspectives of the local BM RAS in health and disease are reviewed in this paper.

Telmisartan inhibits human urological cancer cell growth through early apoptosis

Angiotensin II receptor blockers (ARBs) are widely used as hypertensive therapeutic agents. In addition, studies have provided evidence that ARBs have the potential to inhibit the growth of several types of cancer cells. It was reported that telmisartan (a type of ARB) has peroxisome proliferator-activated receptor (PPAR)-γ activation activity. We previously reported that the PPAR-γ ligand induces growth arrest in human urological cancer cells through apoptosis. In this study, we evaluated the effects of telmisartan and other ARBs on cell proliferation in renal cell carcinoma (RCC), bladder cancer (BC), prostate cancer (PC) and testicular cancer (TC) cell lines. The inhibitory effects of telmisartan and other ARBs (candesartan, valsartan, irbesartan and losartan) on the growth of the RCC, BC, PC and TC cell lines was investigated using an MTT assay. Flow cytometry and Hoechst staining were used to determine whether the ARBs induced apoptosis. Telmisartan caused marked growth inhibition in the urological cancer cells in a dose- and time-dependent manner. Urological cancer cells treated with 100 μM telmisartan underwent early apoptosis and DNA fragmentation. However, the other ARBs had no effect on cell proliferation in any of the urological cancer cell lines. Telmisartan may mediate potent anti-proliferative effects in urological cancer cells through PPAR-γ. Thus, telmisartan is a potent target for the prevention and treatment of human urological cancer.

Does angiotensin II-aldosterone have a role in radiation-induced heart disease?

Radiation-induced heart disease (RIHD) is the potentially lethal side effect of radiation therapy. Clinical trials and epidemiologic studies show the adverse impact of RIHD on the outcome of long-term cancer survivors. However, what factors affect RIHD and how RIHD develop are not yet clear. On the other hand, as we all known, angiotensin II (Ang II) and aldosterone play a vital pathophysiological role in the common cardiovascular disease, including hypertension, atherosclerosis, heart failure, myocardial infarction and cardiac hypertrophy. The pathophysiology of these various syndromes is similar, starting by prior microvascular injury that leads to subsequent myocardium ischemia, all of which cause late fibrous scars. So the pathophysiology of RIHD is similar to the common heart diseases induced by angiotensin-aldosterone. But the effect of angiotensin-aldosterone on RIHD has little been studied. Thus, in the present hypothesis we suggest that angiotensin II-aldosterone plays an important pathophysical role in RIHD, which was confirmed by our pilot study.

Appearance of angiotensin II expression in non-basal epithelial cells is an early feature of malignant change in human prostate

BACKGROUND

Despite increasing interest in the renin-angiotensin system in cancer, little is known about angiotensin II (Ang II) expression in human prostate tumors.

METHODS

Using immunohistochemistry, we examined Ang II expression in prostate cancer (Gleason grades 2-5), benign prostatic hyperplasia (BPH), and high-grade prostatic intraepithelial neoplasia (HGPIN).

RESULTS

Ang II was present in proliferating neoplastic cells in HGPIN, in malignant cells in all grades of prostate cancer examined, in basal but not luminal epithelial cells in BPH, and in the cytoplasm of LNCaP, DU145, and PC3 prostate cancer cells.

CONCLUSIONS

The data establishes the presence of Ang II in pre-malignant and malignant prostate cells, suggests Ang II staining in non-basal epithelial cells is an early sign of malignant change, and supports suggestions that HGPIN and malignant prostate cells both arise from transformed basal cells. Using immunohistochemistry we examined Ang II expression in proliferative disorders of the prostate and concluded that Ang II staining in non-basal epithelial cells is evidence of early malignant change.

The gene polymorphism of the angiotensin I-converting enzyme correlates with tumor size and patient survival in colorectal cancer patients

We studied the putative significance of angiotensin I-converting enzyme (ACE) in colorectal cancer (CRC) biology. Local expression of ACE was investigated by quantitative reverse transcription-polymerase chain reaction and by immunohistochemistry in CRCs and adenomas. ACE insertion (I)/deletion (D) polymorphism was studied in 141 CRC patients and 189 controls. ACE mRNA was upregulated in CRCs compared to corresponding nonlesional tissues (2.5-fold; P = .009). ACE protein was more commonly expressed in adenomas [17 (81%)] and cancer epithelial cells [22 (100%)] than in corresponding non-neoplastic crypt and surface epithelium [2 (10%) and 2 (9%), respectively]. Thirty-seven CRC patients (26%) carried II genotype, 69 (49%) carried ID genotype, and 35 (25%) carried DD genotype. The distribution of the genotypes did not differ from that of controls. Female CRC patients more commonly carried the ID genotype and less frequently the II and DD genotypes compared with male patients (P = .033). Men heterozygous or homozygous for the D-allele had larger tumors compared to carriers of the II genotype (P < .01). Women homozygous for the D-allele lived longer than carriers of the ID and II genotypes. Our study shows that ACE is differentially expressed in CRCs and that gene polymorphism is associated with gender-specific differences in primary tumor size and patient survival.

The angiotensin II/angiotensin II receptor system correlates with nodal spread in intestinal type gastric cancer

We aimed to substantiate the putative significance of angiotensin II receptor type 1 (AT1R) and type 2 (AT2R) for gastric cancer biology by investigating the correlation of their expression with various clinicopathologic variables and patient survival. Local expression of AT1R, AT2R, and angiotensin-converting enzyme (ACE) was investigated by immunohistochemistry in tumor and corresponding nontumor specimens obtained from 100 patients with gastric cancer, and compared with the ACE insertion/deletion gene polymorphism. AT1R and AT2R were found in the tumor epithelial cells of 26 (26%) and 95 (95%) patients, respectively. AT1R was significantly more prevalent (P < 0.001) in intestinal type gastric cancer than in diffuse type gastric cancer. In intestinal type gastric cancer, its expression correlated with the N category (P = 0.009) and the International Union Against Cancer tumor stage (P = 0.024). AT1R+ intestinal type gastric cancers had a larger number of lymph node metastases (P = 0.026), a higher International Union Against Cancer tumor stage (P = 0.032), and a shorter survival time (P = 0.009) than AT1R- tumors. Multivariate analysis with lymph nodes as a dependent variable showed that AT1R status and ACE-I/D gene polymorphism are independent risk factors. Irrespective of the genotype, AT1R+ gastric cancers had a relative risk of lymph node metastases of 4.40 (95% confidence interval, 1.30-14.86). When the ACE genotype was included, the relative risk of having lymph node metastases increased considerably in AT1R+ tumors being heterozygous or homozygous for the ACE D allele (odds ratio, 19.00; 95% confidence interval, 1.45-248.24). Our study shows that AT1R and AT2R are expressed locally in gastric cancer and that the combination of AT1R expression and ACE I/D gene polymorphism correlates with nodal spread in intestinal type gastric cancer.

Over-expression of angiotensin-converting enzyme (CD 143) on leukemic blasts as a clue for the activated local bone marrow RAS in AML

Local bone marrow renin-angiotensin system (RAS) is an autocrine-paracrine system affecting hematopoiesis. Angiotensin II type 1a (AT1a) receptors are present on the CD34+ hematopoietic stem cells. Angiotensin II stimulates the proliferation of bone marrow and umbilical cord blood hematopoietic progenitors. There are preliminary data that local RAS might also be involved in leukemogenesis. ACE hyper-function may lead to the acceleration of negative hematopoietic regulator peptide, AcSDKP, metabolism, which in turn lowers its level in the bone marrow micro-environment, finally removing the anti-proliferative effect of AcSDKP on the hematopoietic cells and blasts. Renin expression could have a role on the leukemia development and angiotensin may act as an autocrine growth factor for acute myeloid leukemia (AML) cells. The aim of this study is to search ACE (CD 143) surface antigen by flow-cytometric analyses on the leukemic blast cells taken from the bone marrow of the patients with AML. Bone marrow aspiration materials and peripheral blood samples were obtained from 11 patients with AML (eight males, three females; aged 46 (range 26-67) years) and six patients with non-malignant hematological disorders (four males, two females; aged 56 (range 22-71) years). ACE (CD 143) surface antigen was shown to be over-expressed in leukemic myeloid blast cells. ACE is positively correlated with bone marrow blast count. Elucidation of the pathological activity of the local RAS-mediated regulation of the leukemogenesis is both pathobiologically and clinically important, since the angiotensin peptides represent a molecular target in the disease management.

Angiotensin II type 1 receptor antagonist candesartan as an angiogenic inhibitor in a xenograft model of bladder cancer

PURPOSE

There have been several studies on the antitumor activity of angiotensin II type 1 receptor (AT1R) antagonists. In this study, we evaluated the efficacy of the AT1R antagonist candesartan in bladder cancer.

EXPERIMENTAL DESIGN

For the study in vitro, human bladder cancer cells (KU-19-19) were cultured with or without angiotensin II and candesartan. Various cytokines and cell viability were analyzed. For the study in vivo, a tumor xenograft model was prepared in nude mice using KU-19-19 cells. Mice were given candesartan daily by oral gavage. Microvessel density, expression of vascular endothelial growth factor (VEGF), and apoptosis were assessed.

RESULTS

Candesartan did not induce direct toxicity in KU-19-19 cells, but VEGF and interleukin-8 were significantly lower in candesartan-treated cells (2.55 +/- 0.25 and 6.58 +/- 0.48 pg/10(3) cells) than in the angiotensin II-treated control cells (3.16 +/- 0.42 and 7.91 +/- 0.69 pg/10(3) cells). In mice, candesartan both at doses of 2 and 10 mg/kg/d significantly suppressed tumor growth in mice (35.4% and 33.5% reduction in tumor volume). Microvessel density was significantly decreased by candesartan (9.8 +/- 2.8 per field) compared with the control group (17.6 +/- 6.0 per field), and VEGF expression was significantly suppressed by this AT1R antagonist. However, candesartan did not induce apoptosis of cancer cells in the tumor.

CONCLUSIONS

Specific blockade of AT1R prevented bladder tumor growth by inhibiting angiogenesis. However, its antitumor effect was not due to direct toxicity. Because AT1R antagonists are widely used to treat hypertension, and a 2 mg/kg/d dose level of candesartan is clinically achievable, this AT1R antagonist could also be used to treat bladder cancer.

Association between the Polymorphism of the Angiotensin-Converting Enzyme Gene and Tumor Size of Breast Cancer in Premenopausal Patients

The association between the polymorphism of the angiotensin-converting enzyme (ACE) gene and breast cancer risk has been extensively studied, however, the studies about the prognostic factors and ACE gene polymorphism are limited in number. Our aims were to analyze the distribution of the insertion/deletion (I/D) polymorphism of the ACE gene in Turkish premenopausal patients with breast cancer, which is more aggressive than the postmenopausal counterpart, and to assess whether DD genotype is associated with poor prognostic factors. The DD genotype has been shown to be associated with the increased serum and tissue levels of ACE, compared to those in II and ID genotypes. ACE genotypes were determined by polymerase chain reaction in 44 Turkish premenopausal patients with breast cancer and in 46 age-matched healthy premenopausal women. ACE genotypes are distributed in patients and control subjects as follows; DD is present in 25 (56.8%), ID in 17 (38.6%), and II in 2 (4.5%) patients, and DD in 28 (60.9%), ID in 12 (26.1%), and II in 6 (13.0%) healthy subjects, respectively. D and I alleles were found in 76.1% and 23.9% of the patients, while 73.9% and 26.1% in healthy subjects, respectively. In breast cancer patients, no significant association was observed between the ACE genotypes and poor prognostic factors, such as negative hormone receptor status, histological grade, lymph node involvement, higher number of lymph node metastases, and c-erb B2 overexpression, except that tumor size greater than 2 cm is associated with DD genotype (p = 0.02). Thus, ACE may influence the local tumor growth of breast cancer in premenopausal patients.

The number of lymph node metastases in gastric cancer correlates with the angiotensin I-converting enzyme gene insertion/deletion polymorphism

PURPOSE

In the present study, we aimed to substantiate the putative significance of angiotensin I-converting enzyme (ACE) on gastric cancer biology by investigating the influence of its gene polymorphism on gastric cancer progression.

EXPERIMENTAL DESIGN

Genomic DNA was purified from peripheral blood mononuclear cells or tissue specimens. Amplified ACE gene fragments were separated on agarose gels. D or I alleles were identified by the presence of 190- or 490-bp fragments, respectively. Local expression of ACE was investigated by immunohistochemistry.

RESULTS

Twenty-four of 113 (21%) gastric cancer patients had the II, 57 (51%) the ID, and 32 (28%) the DD genotype. The distribution of the ACE genotypes did not differ significantly from the control group of 189 patients without gastric cancer. However, the ACE genotypes correlated with the number of lymph node metastases and the Unio Internationale Contra Cancrum (UICC) tumor stage. Patients with the II genotype had a highly significantly smaller number of lymph node metastases (P < 0.001) and a significantly lower UICC tumor stage (P = 0.01) than patients with the DD genotype. No correlation was found between tumor type, tumor location, local tumor growth, distant metastases, and the ACE genotype. The expression of ACE in gastric cancer was investigated by immunohistochemistry in 100 of 113 patients. ACE was expressed by endothelial cells in all (100%) specimens and by tumor cells in 56 (56%) specimens.

CONCLUSIONS

Our study shows that ACE is expressed locally in gastric cancer and that the gene polymorphism influences metastatic behavior.

Targeting multiple signaling pathways as a strategy for managing prostate cancer: multifocal signal modulation therapy

The aberrant behavior of cancer reflects upregulation of certain oncogenic signaling pathways that promote proliferation, inhibit apoptosis, and enable the cancer to spread and evoke angiogenesis. Theoretically, it should be feasible to decrease the activity of these pathways-or increase the activity of pathways that oppose them-with noncytotoxic agents. Since multiple pathways are dysfunctional in most cancers, and cancers accumulate new oncogenic mutations as they progress, the greatest and most durable therapeutic benefit will likely be achieved with combination regimens that address several targets. Thus, a multifocal signal modulation therapy (MSMT) of cancer is proposed. This concept has already been documented by researchers who have shown that certain combinations of signal modulators-of limited utility when administered individually-can achieve dramatic suppression of tumor growth in rodent xenograft models. The present essay attempts to guide development of MSMTs for prostate cancer. Androgen ablation is a signal-modulating measure already in standard use in the management of delocalized prostate cancer. The additional molecular targets considered here include the type 1 insulin-like growth factor receptor, the epidermal growth factor receptor, mammalian target of rapamycin, NF-kappaB, hypoxia-inducible factor-1alpha, hsp90, cyclooxygenase-2, protein kinase A type I, vascular endothelial growth factor, 5-lipoxygenase, 12-lipoxygenase, angiotensin II receptor type 1, bradykinin receptor type 1, c-Src, interleukin-6, ras, MDM2, bcl-2/bclxL, vitamin D receptor, estrogen receptor-beta, and PPAR-. Various nutrients and phytochemicals suspected to have potential utility in prostate cancer prevention and therapy, but whose key molecular targets are still unknown, might reasonably be incorporated into MSMTs for prostate cancer; these include lycopene, selenium, green tea polyphenols, genistein, and silibinin. MSMTs can be developed systematically by testing various combinations of signal-modulating agents, in concentrations that can feasibly be achieved and maintained clinically, on human prostate cancer cell lines; combinations that appear promising can then be tested in xenograft models and, ultimately, in the clinic. Some signal modulators can increase response to cytotoxic drugs by upregulating effectors of apoptosis. When MSMTs fail to raise the spontaneous apoptosis rate sufficiently to achieve tumor stasis or regression, incorporation of appropriate cytotoxic agents into the regimen may improve the clinical outcome.

Cancer, inflammation and the AT1 and AT2 receptors

The critical role of inappropriate inflammation is becoming accepted in many diseases that affect man, including cardiovascular diseases, inflammatory and autoimmune disorders, neurodegenerative conditions, infection and cancer.

This review proposes that cancer up-regulates the angiotensin II type 1 (AT1) receptor through systemic oxidative stress and hypoxia mechanisms, thereby triggering chronic inflammatory processes to remodel surrounding tissue and subdue the immune system. Based on current literature and clinical studies on angiotensin receptor inhibitors, the paper concludes that blockade of the AT1 receptor in synergy with cancer vaccines and anti-inflammatory agents should offer a therapy to regress most, if not all, solid tumours.

With regard to cancer being a systemic disease, an examination of supporting evidence for a systemic role of AT1 in relationship to inflammation in disease and injury is presented as a logical progression. The evidence suggests that regulation of the mutually antagonistic angiotensin II receptors (AT1 and AT2) is an essential process in the management of inflammation and wound recovery, and that it is an imbalance in the expression of these receptors that leads to disease.

In consideration of cancer induced immune suppression, it is further postulated that the inflammation associated with bacterial and viral infections, is also an evolved means of immune suppression by these pathogens and that the damage caused, although incidental, leads to the symptoms of disease and, in some cases, death.

It is anticipated that manipulation of the angiotensin system with existing anti-hypertensive drugs could provide a new approach to the treatment of many of the diseases that afflict mankind.