Angiotensin II promotes the progression of human gastric cancer

Valsartan as a prophylactic treatment against breast cancer development and niche activation: What molecular sequels follow chronic AT-1R blockade?

AIMS

Transactivation of insulin-growth-factor-receptor (IGF-1R) by angiotensin-II-type-1-receptor (AT-1R) was only demonstrated in vascular-smooth-muscle cells and has never been tested in breast-cancer (BC). This investigation addressed the impact of chronic AT-1R blockade by valsartan (Val) on possible concurrent AT-1R/IGF-1R signaling inhibition, regressing BC-tumor-microenvironment (TME) cellular components activation, and hindering BC development.

MAIN METHODS

The effect of different Val doses (10, 20, 40 & 80 mg/kg/day for 490 days) was tested on dimethylbenz(a)anthracene (DMBA)-induced progesterone-promoted-BC in rats. The influence on intratumoral/circulating angiotensin-II (ANG-II) levels and AT-1R/Mas-R immunofluorescent-expression were assessed. The potential AT-1R/IGF-1R crosstalk within TME-BC-stem-cells (BCSCs) and cancer-associated-fibroblasts (CAFs) was evaluated by fluorescently marking these cells and locating the immunofluorescently-stained AT-1R/IGF-1R in them using confocal-laser-microscopy and further quantified by flow cytometry. In addition, the molecular alterations following blocking AT-1R were inspected including determining Src; crucial for IGF-1R transactivation by AT-1R, Notch-1; IGF-IR transcriptional-regulator, and PI3K/Akt &IL-6/STAT expression. Further, the suppression of CSCs' capabilities to maintain pluripotency, stemness features, epithelial-to-mesenchymal-transition (EMT), and angiogenesis was evaluated by assessing NANOG gene, aldehyde-dehydrogenase (ALDH), N-cadherin and vascular-endothelial-growth-factor (VEGF), respectively. Furthermore, the proliferative marker; Ki-67, was detected by immunostaining, and tumors were histologically graded using Elston-Ellis-modified-Scarff-Bloom-Richardson method.

KEY FINDINGS

Prophylactic Val significantly reduced tumor size, prolonged latency, reduced tumor histopathologic grade, decreased circulating/intratumoral-ANG-II levels, increased Mas-R, and decreased AT1R expression. AT-1R/IGF-1R were co-expressed with a high correlation coefficient on CAFs/BCSCs. Moreover, Val significantly attenuated IGF-1R transactivation and transcriptional regulation via Src and Notch-1 genes' downregulation and reduced Src/IGF-IR-associated PI3K/Akt and IL-6/STAT3 signaling. Further, Val significantly decreased intratumoral NANOG, ALDH, N-cadherin, VEGF, and Ki-67 levels.

SIGNIFICANCE

Chronic Val administration carries a potential for repurposing as adjuvant or conjunct therapy for patients at high risk for BC.

The renin-angiotensin-aldosterone system (RAAS) signaling pathways and cancer: foes versus allies

The renin-angiotensin-aldosterone system (RAAS), is an old system with new fundamental roles in cancer biology which influences cell growth, migration, death, and metastasis. RAAS signaling enhances cell proliferation in malignancy directly and indirectly by affecting tumor cells and modulating angiogenesis. Cancer development may be influenced by the balance between the ACE/Ang II/AT1R and the ACE2/Ang 1-7/Mas receptor pathways. The interactions between Ang II/AT1R and Ang I/AT2R as well as Ang1-7/Mas and alamandine/MrgD receptors in the RAAS pathway can significantly impact the development of cancer. Ang I/AT2R, Ang1-7/Mas, and alamandine/MrgD interactions can have anticancer effects while Ang II/AT1R interactions can be involved in the development of cancer. Evidence suggests that inhibitors of the RAAS, which are conventionally used to treat cardiovascular diseases, may be beneficial in cancer therapies.Herein, we aim to provide a thorough description of the elements of RAAS and their molecular play in cancer. Alongside this, the role of RAAS components in sex-dependent cancers as well as GI cancers will be discussed with the hope of enlightening new venues for adjuvant cancer treatment.

Repurposed Drugs in Gastric Cancer

Gastric cancer (GC) is one of the major causes of death worldwide, ranking as the fifth most incident cancer in 2020 and the fourth leading cause of cancer mortality. The majority of GC patients are in an advanced stage at the time of diagnosis, presenting a poor prognosis and outcome. Current GC treatment approaches involve endoscopic detection, gastrectomy and chemotherapy or chemoradiotherapy in an adjuvant or neoadjuvant setting. Drug development approaches demand extreme effort to identify molecular mechanisms of action of new drug candidates. Drug repurposing is based on the research of new therapeutic indications of drugs approved for other pathologies. In this review, we explore GC and the different drugs repurposed for this disease.

The effect of AT1R-1166A/C and AT2R-1675A/G polymorphisms on susceptibility to preeclampsia: A systematic review and meta-analysis

BACKGROUND

The aim of this meta-analysis is to investigate the association between Angiotensin II type 1 receptor (AT1R)-1166A/C, Angiotensin II type 2 receptor (AT2R)-1675A/G polymorphisms and susceptibility to preeclampsia (PE).

METHODS

Online databases, including Web of Science, PubMed, EMBASE, CINAHL, CENTRAL, Scopus, Lilacs/SciELO, and Chinese National Knowledge Infrastructure, China Wan Fang, China Science and Technology Journal Database, were used to perform the literature search up to April 2022. The odds ratio (OR) and 95% confidence interval (CI) were used as effect size. The data was analyzed by Stata 15.0 software.

RESULTS

According to the inclusion and exclusion criteria, a total of 22 case-control studies were identified, including 3524 cases and 6308 controls. Our meta-analysis showed that the AT1R -1166 A/C allele was significantly associated with susceptibility to PE (A vs C: OR = 0.82, 95% CI: 0.69-0.96, P = .013), and there was significant difference in recessive gene model (AA vs AC + CC: OR = 0.81, 95% CI: 0.67-0.97, P = .021). However, no association was found between AT2R-1675A/G polymorphism and susceptibility to PE.

CONCLUSION

our meta-analysis suggested that AT1R-1166A/C polymorphism had an association with susceptibility to PE, but AT2R-1675A/G polymorphism had no association with susceptibility to PE.

Roles of G Protein-Coupled Receptors (GPCRs) in Gastrointestinal Cancers: Focus on Sphingosine 1-Shosphate Receptors, Angiotensin II Receptors, and Estrogen-Related GPCRs

It is well established that gastrointestinal (GI) cancers are common and devastating diseases around the world. Despite the significant progress that has been made in the treatment of GI cancers, the mortality rates remain high, indicating a real need to explore the complex pathogenesis and develop more effective therapeutics for GI cancers. G protein-coupled receptors (GPCRs) are critical signaling molecules involved in various biological processes including cell growth, proliferation, and death, as well as immune responses and inflammation regulation. Substantial evidence has demonstrated crucial roles of GPCRs in the development of GI cancers, which provided an impetus for further research regarding the pathophysiological mechanisms and drug discovery of GI cancers. In this review, we mainly discuss the roles of sphingosine 1-phosphate receptors (S1PRs), angiotensin II receptors, estrogen-related GPCRs, and some other important GPCRs in the development of colorectal, gastric, and esophageal cancer, and explore the potential of GPCRs as therapeutic targets.

Comprehensive landscape of the renin-angiotensin system in Pan-cancer: a potential downstream mediated mechanism of SARS-CoV-2

Background: SARS-CoV-2, the cause of the worldwide COVID-19 pandemic, utilizes the mechanism of binding to ACE2 (a crucial component of the renin-angiotensin system [RAS]), subsequently mediating a secondary imbalance of the RAS family and leading to severe injury to the host. However, very few studies have been conducted to reveal the mechanism behind the effect of SARS-CoV-2 on tumors.

Methods: Demographic data extracted from 33 cancer types and over 10,000 samples were employed to determine the comprehensive landscape of the RAS. Expression distribution, pretranscriptional and posttranscriptional regulation and posttranslational modifications (PTMs) as well as genomic alterations, DNA methylation and m6A modification were analyzed in both tissue and cell lines. The clinical phenotype, prognostic value and significance of the RAS during immune infiltration were identified.

Results: Low expression of AGTR1 was common in tumors compared to normal tissues, while very low expression of AGTR2 and MAS1 was detected in both tissues and cell lines. Differential expression patterns of ACE in ovarian serous cystadenocarcinoma (OV) and kidney renal clear cell carcinoma (KIRC) were correlated with ubiquitin modification involving E3 ligases. Genomic alterations of the RAS family were infrequent across TCGA pan-cancer program, and ACE had the highest alteration frequency compared with other members. Low expression of AGTR1 may result from hypermethylation in the promoter. Downregulation of RAS family was linked to higher clinical stage and worse survival (as measured by disease-specific survival [DSS], overall survival [OS] or progression-free interval [PFI]), especially for ACE2 and AGTR1 in KIRC. ACE-AGTR1, a classical axis of the RAS family related to immune infiltration, was positively correlated with M2-type macrophages, cancer-associated fibroblasts (CAFs) and immune checkpoint genes in most cancers.

Conclusion: ACE, ACE2, AGT and AGTR1 were differentially expressed in 33 types of cancers. PTM of RAS family was found to rely on ubiquitination. ACE2 and AGTR1 might serve as independent prognostic factors for LGG and KIRC. SARS-CoV-2 might modify the tumor microenvironment by regulating the RAS family, thus affecting the biological processes of cancer.

Angiotensin II enhances the proliferation of Natural Killer/T-cell lymphoma cells via activating PI3K/Akt signaling pathway

The present study was to determine the roles of Angiotensin (Ang) II in the growth of lymphoma in nude mice and the proliferation and viability of the human Natural Killer/T (NK/T)-cell lymphoma cell line SNK-6, and the activation of downstream signaling pathway. Lymphoma samples and corresponding normal tissues were obtained from lymphoma patients. Proliferation of SNK-6 cells was detected by CCK8 or MTT assay. The levels of Ang II and its receptor Ang II type 1 receptor (AT1R) were higher in lymphoma tissues than those in control tissues. Ang II increased the lymphoma volume and size in nude mice, the proliferation and viability and the proliferating cell nuclear antigen (PCNA) and Ki67 levels of SNK-6 cells. Losartan, an antagonist of AT1R, reduced lymphoma volume and size in nude mice, and the proliferation and viability and the PCNA and Ki67 levels of SNK-6 cells. The levels of phosphorylated phosphatidylinositol 3-kinase (p-PI3K) and phosphorylated protein kinase B (p-Akt) were increased by Ang II and then reduced by losartan in SNK-6 cells. The proliferation and viability of SNK-6 cells were increased by Ang II, but these increases were inhibited by PI3K inhibitor wortmannin and Akt inhibitor MK2206. The increases of PCNA and Ki67 induced by Ang II were inhibited by wortmannin or MK2206 in SNK-6 cells. These results indicate that Ang II/AT1R is activated in lymphoma, and Ang II promotes the progression of lymphoma in nude mice and the proliferation and viability of SNK-6 cells via activating PI3K/Akt signaling pathway.

Unraveling the Molecular Nexus between GPCRs, ERS, and EMT

G protein-coupled receptors (GPCRs) represent a large family of transmembrane proteins that transduce an external stimulus into a variety of cellular responses. They play a critical role in various pathological conditions in humans, including cancer, by regulating a number of key processes involved in tumor formation and progression. The epithelial-mesenchymal transition (EMT) is a fundamental process in promoting cancer cell invasion and tumor dissemination leading to metastasis, an often intractable state of the disease. Uncontrolled proliferation and persistent metabolism of cancer cells also induce oxidative stress, hypoxia, and depletion of growth factors and nutrients. These disturbances lead to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and induce a cellular condition called ER stress (ERS) which is counteracted by activation of the unfolded protein response (UPR). Many GPCRs modulate ERS and UPR signaling via ERS sensors, IRE1α, PERK, and ATF6, to support cancer cell survival and inhibit cell death. By regulating downstream signaling pathways such as NF-κB, MAPK/ERK, PI3K/AKT, TGF-β, and Wnt/β-catenin, GPCRs also upregulate mesenchymal transcription factors including Snail, ZEB, and Twist superfamilies which regulate cell polarity, cytoskeleton remodeling, migration, and invasion. Likewise, ERS-induced UPR upregulates gene transcription and expression of proteins related to EMT enhancing tumor aggressiveness. Though GPCRs are attractive therapeutic targets in cancer biology, much less is known about their roles in regulating ERS and EMT. Here, we will discuss the interplay in GPCR-ERS linked to the EMT process of cancer cells, with a particular focus on oncogenes and molecular signaling pathways.

Synthesis and Evaluation of [18F]FEtLos and [18F]AMBF3Los as Novel 18F-Labelled Losartan Derivatives for Molecular Imaging of Angiotensin II Type 1 Receptors

Losartan is widely used in clinics to treat cardiovascular related diseases by selectively blocking the angiotensin II type 1 receptors (AT₁Rs), which regulate the renin-angiotensin system (RAS). Therefore, monitoring the physiological and pathological biodistribution of AT₁R using positron emission tomography (PET) might be a valuable tool to assess the functionality of RAS. Herein, we describe the synthesis and characterization of two novel losartan derivatives PET tracers, [¹⁸F]fluoroethyl-losartan ([¹⁸F]FEtLos) and [¹⁸F]ammoniomethyltrifluoroborate-losartan ([¹⁸F]AMBF₃Los). [¹⁸F]FEtLos was radiolabeled by ¹⁸F-fluoroalkylation of losartan potassium using the prosthetic group 2-[¹⁸F]fluoroethyl tosylate; whereas [¹⁸F]AMBF₃Los was prepared following an one-step ¹⁸F-¹⁹F isotopic exchange reaction, in an overall yield of 2.7 ± 0.9% and 11 ± 4%, respectively, with high radiochemical purity (>95%). Binding competition assays in AT₁R-expressing membranes showed that AMBF₃Los presented an almost equivalent binding affinity (K_i 7.9 nM) as the cold reference Losartan (K_i 1.5 nM), unlike FEtLos (K_i 2000 nM). In vitro and in vivo assays showed that [¹⁸F]AMBF₃Los displayed a good binding affinity for AT₁R-overexpressing CHO cells and was able to specifically bind to renal AT₁R. Hence, our data demonstrate [¹⁸F]AMBF₃Los as a new tool for PET imaging of AT₁R with possible applications for the diagnosis of cardiovascular, inflammatory and cancer diseases.

Evaluating the benefits of renin-angiotensin system inhibitors as cancer treatments

G-protein-coupled receptors (GPCRs) are the largest and most diverse group of cellular membrane receptors identified and characterized. It is estimated that 30 to 50% of marketed drugs target these receptors. The angiotensin II receptor type 1 (AT1R) is a GPCR which signals in response to systemic alterations of the peptide hormone angiotensin II (AngII) in circulation. The enzyme responsible for converting AngI to AngII is the angiotensin-converting enzyme (ACE). Specific inhibitors for the AT1R (more commonly known as AT1R blockers or antagonists) and ACE are well characterized for their effects on the cardiovascular system. Combined with the extensive clinical data available on patient tolerance of AT1R blockers (ARBs) and ACE inhibitors (ACEIs), as well as their non-classical roles in cancer, the notion of repurposing this class of medications as cancer treatment(s) is explored in the current review. Given that AngII-dependent AT1R activity directly regulates angiogenesis, remodeling of vasculature, pro-inflammatory responses, stem cell programming and hematopoiesis, and electrolyte balance; the modulation of these processes with pharmacologically well characterized medications could present a valuable complementary treatment option for cancer patients.

Targeting G protein-coupled receptors in cancer therapy

As basic research into GPCR signaling and its association with disease has come into fruition, greater clarity has emerged with regards to how these receptors may be amenable to therapeutic intervention. As a diverse group of receptor proteins, which regulate a variety of intracellular signaling pathways, research in this area has been slow to yield tangible therapeutic agents for the treatment of a number of diseases including cancer. However, recently such research has gained momentum based on a series of studies that have sought to define GPCR proteins dynamics through the elucidation of their crystal structures. In this chapter, we define the approaches that have been adopted in developing better therapeutics directed against the specific parts of the receptor proteins, such as the extracellular and the intracellular domains, including the ligands and auxiliary proteins that bind them. Finally, we also briefly outline how GPCR-derived signaling transduction pathways hold great potential as additional targets.

Protective effect of angiotensin Ⅱ type 1 receptor antagonist against gastric mucosal lesions in rats with cerebral hemorrhage and acute stress gastric mucosal injury

AIM

To analyze the protective effect of angiotensin Ⅱ AT1 receptor blocker (ARB) against gastric mucosal lesions in rats with intracerebral hemorrhage combined with acute stress mucosal injury.

METHODS

Thirty-six healthy male Sprague-Dawley rats were selected from our laboratory Animal Center and randomly divided into either a treatment group (18 rats) or a control group (18 rats). After intracerebral hemorrhage was induced in rats, the treatment group was given telmisartan, and the control group was given equal amount of normal saline. Serum norepinephrine (NE) and epinephrine (E) contents were detected and the gastric mucosal ulcer index (UI) was calculated. Immunohistochemistry was used to detect proliferative cell nuclear antigen (PCNA) in rat gastric mucosa (proliferative cell nuclei). Apoptotic cells were detected by transferase-mediated dUTP nick end labeling (TUNEL).

RESULTS

There was no significant difference in the scores of cerebral apoplexy between the treatment group and the control group (P > 0.05). After 1, 3, and 5 d of treatment, serum E and NE levels in the treatment group were significantly lower than those in the control group (P < 0.05). The UI values of the treatment group on days 1, 3, and 5 were 3.86 ± 1.14, 20.19 ± 1.28, and 13.86 ± 1.25, respectively, which were significantly lower than those of the control group (6.03 ± 1.16, 24.03 ± 1.31, and 17.10 ± 1.28, respectively; P < 0.05). After 1, 3, and 5 d of treatment, the number of PCNA positive cells in the treatment group was significantly higher than that of the control group, while the number of apoptotic cells was significantly lower than that in the control group (P < 0.05).

CONCLUSION

ARB can reduce serum contents of NE and E in rats with intracerebral hemorrhage, decrease apoptotic cells in the gastric mucosa, and increase the number of proliferating cells, thus exerting a therapeutic effect against acute stress gastric mucosal lesions.

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.

Angiotensin receptor blocker use and gastro-oesophageal cancer survival: a population-based cohort study

BACKGROUND

Angiotensin receptor blockers (ARBs; including candesartan, losartan, olmesartan and valsartan) are widely used to treat hypertension, heart failure and diabetic neuropathy. There is considerable pre-clinical evidence that ARBs can reduce cancer progression, particularly for gastric cancer. Despite this, epidemiological studies have yet to assess the impact of ARB use on gastro-oesophageal cancer survival.

AIM

To investigate the association between post-diagnosis ARB use and gastro-oesophageal cancer survival.

METHODS

We selected a cohort of patients with newly-diagnosed gastro-oesophageal cancer between 1998 and 2012 from English cancer registries. We linked to prescription and clinical records from the Clinical Practice Research Datalink, and to death records from the Office for National Statistics. We used time-dependant Cox-regression models to calculate hazard ratios (HRs) comparing gastro-oesophageal cancer-specific mortality between post-diagnosis ARB users and non-users, after adjusting for demographics, comorbidities and post-diagnosis aspirin or statin use.

RESULTS

Our cohort included 5124 gastro-oesophageal cancer patients, of which 360 used ARBs, and 3345 died due to their gastro-oesophageal cancer during follow-up. After adjustment, ARB users had moderately lower risk of gastro-oesophageal cancer mortality than the non-users (HR = 0.83, 95% CI 0.71-0.98). There was evidence of a dose-response relationship with the lowest HRs observed among patients receiving at least 2 years of prescriptions (HR = 0.42, 95% CI 0.25-0.72).

CONCLUSIONS

In this large population-based gastro-oesophageal cancer cohort, we found moderately reduced cancer-specific mortality among ARB users. However, confirmation in further independent epidemiological studies with sufficient staging information is required.

Telmisartan Induces Osteosarcoma Cells Growth Inhibition and Apoptosis Via Suppressing mTOR Pathway

Osteosarcoma (OS) is a commonly occurring primary malignant bone cancer with serious impact and high mortality, yet effective and safe therapy method not available. The aim of the present study was to elucidate the antitumor effect of telmisartan on human osteosarcoma cells in vitro and its underlying mechanism. The proliferation effect of osteosarcoma cell lines U2OS was examined by Cell Counting Kit-8. The invasive and migratory capabilities were determined by transwell invasion and migration assay. The percentage of apoptotic cells were detected by flow cytometric analysis and proteins related to apoptosis including Bax, Bcl-2 and Cleaved Caspase-3 were examined by western blotting. The expressions of mammalian target of rapamycin (mTOR) signaling relevant molecules were detected by western blot assay. Telmisartan treatment caused dose-dependent and time-dependent inhibition of proliferation and inducing anti-migration, anti-invasiveness and apoptosis of U2OS cells. The induction of apoptosis was confirmed concurring with the altered expression of proteins associated with the apoptosis. Mechanistically, telmisartan suppresses mTOR activation. Telmisartan can impede the growth, invasion, migration and induce the apoptosis of U2OS cell probably through inhibiting the mTOR signaling pathway activation. Thus, telmisartan is a potential drug for the prevention and treatment of human osteosarcomal cancer.

Adenovirus-Mediated Angiotensin II Type 2 Receptor Overexpression Inhibits Tumor Growth of Prostate Cancer In Vivo

The renin-angiotensin system (RAS) plays important roles in tumorigenesis and is involved with several hallmarks of cancer. Evidence shows that angiotensin II (AngII) type 1 receptor (AT1R) blockers may be associated with improved outcome in prostate cancer patients. Furthermore, our previous studies indicate that increased expression of Ang II type 2 receptor (AT2R) alone induced apoptosis in human prostate cancer lines, an effect that did not require Ang II. This study aimed to investigate the effects of AT2R on tumor growth in vivo and we hypothesized that AT2R over-expression would inhibit proliferation and induce apoptosis in vivo. Human prostate cancer DU145 xenograft mouse model was used to assess the effect of AT2R on tumor growth in vivo. Mice bearing a palpable tumor were chosen and divided randomly into three treatment groups: AT2R, GFP, and PBS. Then we directly injected into the xenograft tumors of the mice every three days with recombinant adenoviruses encoding AT2R (Ad5-CMV-AT2R-EGFP), EGFP (Ad5-CMV-EGFP) and PBS, respectively. The tumor sizes of the tumor bearing mice were then measured. Immunohistochemical Ki-67 staining and TUNEL assay were performed to examine the inhibitory effect of AT2R on tumor cell proliferation. The results showed that AT2R overexpression can inhibit tumor growth of prostate cancer in vivo by inhibiting proliferation and inducing apoptosis of tumor cells. GADD45A is involved in the AT2R-induced antitumor activity. This suggests that AT2R is a potentially useful gene for prostate gene therapy.