Renin angiotensin system and its role in biomarkers and treatment in gliomas

Deep DNA sequencing of MGMT, TP53 and AGT in Mexican astrocytoma patients identifies an excess of genetic variants in women and a predictive biomarker

PURPOSE

Astrocytomas are a type of malignant brain tumor with an unfavorable clinical course. The impact of AGT and MGMT somatic variants in the prognosis of astrocytoma is unknown, and it is controversial for TP53. Moreover, there is a lack of knowledge regarding the molecular characteristics of astrocytomas in Mexican patients.

METHODS

We studied 48 Mexican patients, men and women, with astrocytoma (discovery cohort). We performed DNA deep sequencing in tumor samples, targeting AGT, MGMT and TP53, and we studied MGMT gene promoter methylation status. Then we compared our findings to a cohort which included data from patients with astrocytoma from The Cancer Genome Atlas (validation cohort).

RESULTS

In the discovery cohort, we found a higher number of somatic variants in AGT and MGMT than in the validation cohort (10.4% vs < 1%, p < 0.001), and, in both cohorts, we observed only women carried variants AGT variants. We also found that the presence of either MGMT variant or promoter methylation was associated to better survival and response to chemotherapy, and, in conjunction with TP53 variants, to progression-free survival.

CONCLUSIONS

The occurrence of AGT variants only in women expands our knowledge about the molecular differences in astrocytoma between men and women. The increased prevalence of AGT and MGMT variants in the discovery cohort also points towards possible distinctions in the molecular landscape of astrocytoma among populations. Our findings warrant further study.

Inhibition of the angiotensin II type 2 receptor AT2R is a novel therapeutic strategy for glioblastoma

Glioblastoma (GBM) is an aggressive malignant primary brain tumor with limited therapeutic options. We show that the angiotensin II (AngII) type 2 receptor (AT₂R) is a therapeutic target for GBM and that AngII, endogenously produced in GBM cells, promotes proliferation through AT₂R. We repurposed EMA401, an AT₂R antagonist originally developed as a peripherally restricted analgesic, for GBM and showed that it inhibits the proliferation of AT₂R-expressing GBM spheroids and blocks their invasiveness and angiogenic capacity. The crystal structure of AT₂R bound to EMA401 was determined and revealed the receptor to be in an active-like conformation with helix-VIII blocking G-protein or β-arrestin recruitment. The architecture and interactions of EMA401 in AT₂R differ drastically from complexes of AT₂R with other relevant compounds. To enhance central nervous system (CNS) penetration of EMA401, we exploited the crystal structure to design an angiopep-2-tethered EMA401 derivative, A3E. A3E exhibited enhanced CNS penetration, leading to reduced tumor volume, inhibition of proliferation, and increased levels of apoptosis in an orthotopic xenograft model of GBM.

Alterations in Gene Expression of Renin-Angiotensin System Components and Related Proteins in Colorectal Cancer

MATERIALS AND METHODS

Quantitative expression of the RNA of these 17 genes in normal and cancerous tissues obtained using chip arrays from the public functional genomics data repository, Gene Expression Omnibus (GEO) application, was compared statistically.

RESULTS

Expression of four genes, AGT (angiotensinogen), ENPEP (aminopeptidase A) MME (neprilysin), and PREP (prolyl endopeptidase), was significantly upregulated in CRC specimens. Expression of REN (renin), THOP (thimet oligopeptidase), NLN (neurolysin), PRCP (prolyl carboxypeptidase), ANPEP (aminopeptidase N), and MAS1 (Mas receptor) was downregulated in CRC specimens.

CONCLUSIONS

Presuming gene expression parallel protein expression, these results suggest that increased production of the angiotensinogen precursor of angiotensin (ANG) peptides, with the reduction of the enzymes that metabolize it to ANG II, can lead to accumulation of angiotensinogen in CRC tissues. Downregulation of THOP, NLN, PRCP, and MAS1 gene expression, whose proteins contribute to the ACE2/ANG 1-7/Mas axis, suggests that reduced activity of this RAS branch could be permissive for oncogenicity. Components of the RAS may be potential therapeutic targets for treatment of CRC.

The Therapeutic Potential of Targeting the Angiotensin Pathway as a Novel Therapeutic Approach to Ameliorating Post-Surgical Adhesions

BACKGROUND

Post-surgical adhesion is a common complication after abdominal or pelvic surgeries. Despite improvements in surgical techniques or the application of physical barriers, little improvements have been achieved. It causes bowel obstruction, pelvic pain, and infertility in women and has an adverse effect on the quality of life. Renin-Angiotensin System (RAS) is traditionally considered as a blood pressure regulator. However, recent studies also indicate that the RAS plays a vital role in other processes, including oxidative stress, fibrosis, proliferation, inflammation, and the wound healing process. Angiotensin II (Ang II) is the main upstream effector of the RAS that can bind to the AT1 receptor (ATIR). A growing body of evidence has revealed that targeting Angiotensin-Converting Enzyme Inhibitors (ACEIs), Angiotensin II type 1 Receptor Blockers (ARBs), and Direct Renin Inhibitors (DRIs) can prevent post-surgical adhesions. Here we provide an overview of the therapeutic effect of RAS antagonists for adhesion.

METHODS

PubMed, EMBASE, and the Cochrane library were reviewed to identify potential agents targeting the RAS system as a potential approach for post-surgical adhesion.

RESULTS

Available evidence suggests the involvement of the RAS signaling pathway in inflammation, proliferation, and fibrosis pathways as well as in post-surgical adhesions. Several FDA-approved drugs are being used for targeting the RAS system. Some of them are being tested in different models to reduce fibrosis and improve adhesion after surgery, including Telmisartan, valsartan, and enalapril.

CONCLUSION

Identification of the pathological causes of post-surgical adhesion and the potential role of targeting Renin-Angiotensin System may help prevent this problem. Based on the pathological function of RAS signaling after surgeries, the administration of ARBs may be considered as a novel and efficient approach to prevent postsurgical adhesions. Pre-clinical and clinical studies should be carried out to have better information on the clinical significance of this therapy against post-surgical adhesion formation.

Captopril inhibits Matrix Metalloproteinase-2 and extends survival as a temozolomide adjuvant in an intracranial gliosarcoma model

BACKGROUND

Captopril is a well-characterized, FDA-approved drug that has demonstrated promise as a repurposed oncology therapeutic. Captopril's known anti-cancer effects include inhibition of Matrix Metalloproteinase-2 (MMP-2), an endopeptidase which selectively breaks down the extracellular matrix to promote cell migration. MMP-2 is a known therapeutic target in gliomas, tumors with significant clinical need. Using an aggressive gliosarcoma model, we assessed captopril's effects on MMP-2 expression in vitro and in vivo as well as its efficacy as an adjuvant in combination therapy regimens in vivo.

METHODS

Following captopril treatment, MMP-2 protein expression and migratory capabilities of 9 L gliosarcoma cells were assessed in vitro via western blots and scratch wound assays, respectively. Rats were intracranially implanted with 9 L gliosarcoma tumors, and survival was assessed in the following groups: control; captopril (30 mg/kg/day); temozolomide (TMZ) (50 mg/kg/day), and captopril+TMZ. In vivo experiments were accompanied by immunohistochemistry for MMP-2 from brain tissue.

RESULTS

In vitro, captopril decreased MMP-2 protein expression and reduced migratory capacity in 9 L gliosarcoma cells. In a gliosarcoma animal model, captopril decreased MMP-2 protein expression and extended survival as a TMZ adjuvant relative to untreated controls, captopril monotherapy, and TMZ monotherapy groups (27.5 versus 14 (p < 0.001), 16 (p < 0.001), and 23 (p = 0.018) days, respectively).

CONCLUSIONS

Captopril decreases gliosarcoma cell migration, which may be mediated by reduction in MMP-2 protein expression. Captopril provided a survival advantage as a TMZ adjuvant in a rat intracranial gliosarcoma model. Captopril may represent a promising potential adjuvant to TMZ therapy in gliosarcoma as a modulator of the MMP-2 pathway.

Women in Neurosurgery: First Neurosurgeon in Latin America and Current Mexican Leaders

BACKGROUND

History has taught us that Mexican culture has been largely supported by women, despite gender prejudice from the society. Neurosurgery has not been the exception. Therefore, we investigated the challenges and influence of female neurosurgeons in Mexico.

METHODS

We conducted a review of the literature and an analysis of the internal database of the Mexican Society of Neurological Surgery focusing on 3 topics: 1) the historical presence of women and gender inequality in Mexico; 2) the life and legacy of the woman who became the first neurosurgeon in Mexico and in Latin America; and 3) the participation of women in neurosurgery in the past 3 decades.

RESULTS

In Latin America, the first woman in neurosurgery was María Cristina García-Sancho, who completed her neurosurgical training in 1951. Currently, women represent 6.2% of the total members of the Mexican Society of Neurological Surgery (MSNS). This percentage is still low, although data collected in this study suggest that it might increase in the next few years because 16.7% of Board Directors of the MSNS are women, the next elected president is a female neurosurgeon, and 14.5% of neurosurgery residents are women.

CONCLUSIONS

Although a steady increase has occurred of women in neurosurgery in Mexico, there is still work to do, especially to overcome the barriers related to the old assumptions of the cultural and social roles of women.

Sex differences exist in brain renin-angiotensin system-regulating aminopeptidase activities in transplacental ethyl-nitrosourea-induced gliomas

INTRODUCTION

The renin angiotensin system (RAS) is emerging as an important target for the treatment of glioma. We had described that the local RAS is involved in vivo in tumor growth in the rat model of experimental C6 glioma implanted at the subcutaneous region, through the modification of several proteolytic regulatory enzymes of aminopeptidase type.

METHODS

We analyze RAS-regulating aminopeptidase activities in plasma and brain tissue of control male and female rats and rats with transplacental ethylnitrosourea-induced gliomas.

RESULTS

No differences were found either the mean total number of tumors per animal or the tumor volume between male and female animals. However, we have found increased levels in aspartyl aminopeptidase in both males and females and of aminopeptidase B only in males. On the contrary, decreased levels were found in aminopeptidase N and insulin-regulated aminopeptidase activities in both males and females, whereas aminopeptidase A only decreased in females. Decreased levels of aminopeptidase N, aminopeptidase B and insulin-regulated aminopeptidase were also shown in plasma of only female rats.

CONCLUSIONS

Under the complexity of RAS cascade, the changes found suggest the predominant actions of angiotensin III against a decreased action of angiotensin II and angiotensin IV. We conclude that angiotensin peptides are involved in tumor growth in this rat model of glioma and that their role in tumor growth can be analyzed through their corresponding proteolytic regulatory enzymes, which make them new and attractive therapeutic targets beyond the use or angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs).

The therapeutic potential of renin-angiotensin system inhibitors in the treatment of pancreatic cancer

Pancreatic cancer is among the most lethal malignancies with poor prognosis and patients become chemoresistant to current therapies, supporting further investigations to identify new therapeutic regimens in the treatment of this condition. Preclinical and clinical studies now appear to support the role of the renin-angiotensin system (RAS) in the regulation of tumor growth, angiogenesis, and metastasis in different malignancies including pancreatic cancer. These studies suggest that RAS blockers; Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs); could have anti-carcinogenic effects and improve clinical outcomes in the management of pancreatic cancer. Here we provided an overview of ACE inhibitors and ARBs as a potential therapeutic option in the treatment of pancreatic cancer.

ACE2: the molecular doorway to SARS-CoV-2

The angiotensin-converting enzyme 2 (ACE2) is the host functional receptor for the new virus SARS-CoV-2 causing Coronavirus Disease 2019. ACE2 is expressed in 72 different cell types. Some factors that can affect the expression of the ACE2 are: sex, environment, comorbidities, medications (e.g. anti-hypertensives) and its interaction with other genes of the renin-angiotensin system and other pathways. Different factors can affect the risk of infection of SARS-CoV-2 and determine the severity of the symptoms. The ACE2 enzyme is a negative regulator of RAS expressed in various organ systems. It is with immunity, inflammation, increased coagulopathy, and cardiovascular disease. In this review, we describe the genetic and molecular functions of the ACE2 receptor and its relation with the physiological and pathological conditions to better understand how this receptor is involved in the pathogenesis of COVID-19. In addition, it reviews the different comorbidities that interact with SARS-CoV-2 in which also ACE2 plays an important role. It also describes the different factors that interact with the virus that have an influence in the expression and functional activities of the receptor. The goal is to provide the reader with an understanding of the complexity and importance of this receptor.

A Systems-Based Map of Human Brain Cell-Type Enriched Genes and Malignancy-Associated Endothelial Changes

Changes in the endothelium of the cerebral vasculature can contribute to inflammatory, thrombotic, and malignant disorders. The importance of defining cell-type-specific genes and their modification in disease is increasingly recognized. Here, we develop a bioinformatics-based approach to identify normal brain cell-enriched genes, using bulk RNA sequencing (RNA-seq) data from 238 normal human cortex samples from 2 independent cohorts. We compare endothelial cell-enriched gene profiles with astrocyte, oligodendrocyte, neuron, and microglial cell profiles. Endothelial changes in malignant disease are explored using RNA-seq data from 516 lower-grade gliomas and 401 glioblastomas. Lower-grade gliomas appear to be an "endothelial intermediate" between normal brain and glioblastoma. We apply our method for the prediction of glioblastoma-specific endothelial biomarkers, providing potential diagnostic or therapeutic targets. In summary, we provide a roadmap of endothelial cell identity in normal and malignant brain, using a method developed to resolve bulk RNA-seq into constituent cell-type-enriched profiles.

The effect of renin-angiotensin system blockers on spinal cord dysfunction and imaging features of spinal cord compression in patients with symptomatic cervical spondylosis

BACKGROUND CONTEXT

Cervical spondylosis may lead to spinal cord compression, poor vascular perfusion, and ultimately, cervical myelopathy. Studies suggest a neuroprotective effect of renin-angiotensin system (RAS) inhibitors in the brain, but limited data exist regarding their impact on the spinal cord.

PURPOSE

To investigate whether RAS blockers and other antihypertensive drugs are correlated with preoperative functional status and imaging markers of cord compression in patients with symptomatic cervical spondylosis.

STUDY DESIGN

Retrospective observational study.

PATIENT SAMPLE

Individuals with symptomatic degenerative cervical stenosis who underwent surgery.

OUTCOME MEASURES

Imaging features of spinal cord compression and functional status (modified Japanese Orthopedic Association [mJOA] and Nurick grading scales).

METHODS

Two hundred sixty-six operative patients with symptomatic degenerative cervical stenosis were included. Demographic data, comorbidities, antihypertensive medications, and functional status (including mJOA and Nurick grading scales) were collected. We evaluated canal compromise, cord compromise, surface area of T2 signal cord change, and pixel intensity of signal cord change compared with normal cord on T2-weighted magnetic resonance imaging sequences.

RESULTS

Of 266 patients, 41.7% were women, 58.3% were men; median age was 57.2 years; 20.6% smoked tobacco; 24.7% had diabetes mellitus. One hundred forty-nine patients (55.8%) had hypertension, 142 (95.3%) of these were taking antihypertensive medications (37 angiotensin-II receptor blockers [ARBs], 44 angiotensin-converting enzyme inhibitors, and 61 other medications). Patients treated with ARBs displayed a higher signal intensity ratio (ie, less signal intensity change in the compressed cord area) compared with untreated patients without hypertension (p=.004). Patients with hypertension had worse preoperative mJOA and Nurick scores than those without (p<.001). In the multivariate analysis, ARBs remained an independent beneficial factor for lower signal intensity change (p=.04), whereas hypertension remained a risk factor for worse preoperative neurological status (p<.01).

CONCLUSIONS

In our study, patients with hypertension who were treated with RAS inhibitors had decreased T2-weighted signal intensity change than untreated patients without hypertension. Patients with hypertension also had worse preoperative functional status. Prospective case-control studies may deepen understanding of RAS modulators in the imaging and functional status of chronic spinal cord compression.

Therapeutic Targeting of Cancer Stem Cells in Human Glioblastoma by Manipulating the Renin-Angiotensin System

Patients with glioblastoma (GB), a highly aggressive brain tumor, have a median survival of 14.6 months following neurosurgical resection and adjuvant chemoradiotherapy. Quiescent GB cancer stem cells (CSCs) invariably cause local recurrence. These GB CSCs can be identified by embryonic stem cell markers, express components of the renin-angiotensin system (RAS) and are associated with circulating CSCs. Despite the presence of circulating CSCs, GB patients rarely develop distant metastasis outside the central nervous system. This paper reviews the current literature on GB growth inhibition in relation to CSCs, circulating CSCs, the RAS and the novel therapeutic approach by repurposing drugs that target the RAS to improve overall symptom-free survival and maintain quality of life.

PTB-AS, a Novel Natural Antisense Transcript, Promotes Glioma Progression by Improving PTBP1 mRNA Stability with SND1

Glioma, the most common primary malignancy in the brain, has high recurrence and lethality rates, and thus, elucidation of the molecular mechanisms of this incurable disease is urgently needed. Poly-pyrimidine tract binding protein (PTBP1, also known as hnRNP I), an RNA-binding protein, has various mechanisms to promote gliomagenesis. However, the mechanisms regulating PTBP1 expression are unclear. Herein, we report a novel natural antisense noncoding RNA, PTB-AS, whose expression correlated positively with PTBP1 mRNA. We found that PTB-AS significantly promoted the proliferation and migration in vivo and in vitro of glioma cells. PTB-AS substantially increased the PTBP1 level by directly binding to its 3' UTR and stabilizing the mRNA. Furthermore, staphylococcal nuclease domain-containing 1 (SND1) dramatically increased the binding capacity between PTB-AS and PTBP1 mRNA. Mechanistically, PTB-AS could mask the binding site of miR-9 in the PTBP1-3' UTR; miR-9 negatively regulates PTBP1. To summarize, we revealed that PTB-AS, which maintains the PTBP1 level through extended base pairing to the PTBP1 3' UTR with the assistance of SND1, could significantly promote gliomagenesis.

Angiotensin-converting enzyme insertion/deletion gene polymorphisms and the risk of glioma in an Algerian population

Introduction

Just recently, it has been established that the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism is linked to the pathogenesis and to the evolution of human cancers. Therefore, the present study was concerned with the investigation of an eventual association between glioma and I/D polymorphism of the ACE gene.

Methods

The expression of ACE gene was detected by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis in 36 Algerian patients with glioma and 195 healthy controls.

Results

In glioma cases, allelic frequencies and genotypes distribution of the ACE I/D polymorphism were different from controls cases. ACE DD genotype were highly presented in glioma cases (63.9%) than controls (33.8%) and conferred 3.64-fold risk for predisposition in glioma cases (vs ID genotype, p<0.001). Recessive model (ACE II + ID genotypes vs DD) was associated with a 72% reduced risk of glioma (OR = 0.28, 95% CI: 0.13-0.60, p <0.001). Per copy D allele frequency was found higher in glioma cases (79.2%) than in controls (63.3 %), OR = 2.20, 95% CI: 1.20 - 4.03, p = 0.009.

Conclusion

The obtained data showed that the presence of the D allele might be a risk factor for the development of glioma. Further studies considering different ethnic groups with large samples are required to confirm this finding.

Angiotensinogen rs5050 germline genetic variant as potential biomarker of poor prognosis in astrocytoma

Introduction

Renin-angiotensin system (RAS) in brain cancer represents a scarcely explored field in neuro-oncology. Recently, some pre- and clinical studies have reported that RAS components play a relevant role in the development and behavior of gliomas. The angiotensinogen (AGT) rs5050 genetic variant has been identified as a crucial regulator of the transcription of AGT mRNA, which makes it a logical and promising target of research. The aim of this study was to determine the relationship between the AGT rs5050 genetic variant in blood with prognosis in astrocytoma.

Methods

A prospective pilot study was performed on forty-eight astrocytoma patients, who received the standard-of-care treatment. Blood samples were taken prior to surgery and DNA was sequenced using Ion Torrent next-generation sequencing and analyzed by Ion Reporter software. Descriptive, bivariate, multivariate, and survival analyses were performed using SPSS v21, STATA 12 and GraphPad Prism 7.

Results

Median follow-up was 41 months (range 1–48). Survival analysis showed a significant difference between the rs5050 genotypes (p = .05). We found lower survival rates in individuals with the GG-genotype of rs5050 AGT compared to patients with the TT- and TG-genotype (2 months vs. 11.5 months, respectively [p = .01]). In bivariate and multivariate analyses, GG-genotype was negatively associated with survival.

Conclusions

In patients with astrocytoma, AGT rs5050 GG-genotype was associated with poor prognosis. We propose this germline genetic variant as a complementary biomarker, which can be detected practically and safely in blood samples or saliva.

S-Nitrosocaptopril prevents cancer metastasis in vivo by creating the hostile bloodstream microenvironment against circulating tumor cells

A perfect microenvironment facilitates the activated circulating tumor cells (CTCs) to spark the adhesion-invasion-extravasation metastatic cascade in their premetastatic niche. Platelet-CTC interaction contributes to the progression of tumor malignancy by protecting CTCs from shear stress and immunological assault, aiding CTCs entrapment in the capillary bed, enabling CTCs to successfully exit the bloodstream and enter the tissue, inducing epithelial-mesenchymal-like transition (EMT), and assisting in the establishment of metastatic foci. To prevent the cascade from sparking, we show that, the multifunctional S-nitrosocaptopril (CapNO) acts on both CTCs and platelets to interrupt platelet/CTCs interplay and adhesion to endothelium, thus inhibiting CTC-based pulmonary metastasis in vivo. The activated platelets cloak cancer HT29 cells, resulting in HT29-exhibiting platelet biomarkers CD61 and P-selectin positive. CapNO inhibits both sialyl Lewis^x (Slex) expression on HT29 and ADP-induced activation of platelets through P-selectin- and GPIIb/IIIa-dependent mechanisms, confirmed by the corresponding antibody assay. CapNO inhibits platelet- or interleukin (IL)-1β-mediated adhesion between HT29 and endothelial cells, and micrometastatic formation in the lungs of immunocompetent syngeneic mouse models. CapNO have also shown the effects of vasodilation, anticoagulation, inhibition of matrix metalloproteinase-2 (MMP2) expression on cancer cells, and inhibition of cell adhesion molecules (CAMs) expression on vascular endothelium. Due to a series of the beneficial effects of CapNO, CTCs remain exposed to the hostile bloodstream environment and are vulnerable to death induced by shear stress and immune elimination. This new discovery provides a basis for CapNO used for cancer metastatic chemoprevention, and might suggest regulation of the CTCs bloodstream microenvironment as a new avenue for cancer metastatic prevention.

Involvement of the renin-angiotensin system in the progression of severe hand-foot-and-mouth disease

BACKGROUND

Hand-foot-and-mouth disease (HFMD) is generally considered as a mild exanthematous disease to infants and young children worldwide. HFMD cases are usually mild and self-limiting but for few cases leads to complicated severe clinical outcomes, and even death. Previous studies have indicated that serum Ang II levels in patients with H7N9 infection were related to the severity of infection. However, the mechanisms underlying the pathogenesis of severe HFMD remain unclear. This study was undertaken to clarify the role of the renin-angiotensin system (RAS) in the progression of severe HFMD.

METHODS

In the present study, 162 children including HFMD patients and healthy controls were recruited. The data was analyzed by time-series fashion. Concentrations of angiotensin II (Ang II) and noradrenaline (NA) in serum of patients were measured with ELISA. We established a mouse model for enterovirus 71 (EV71) infection and determined concentrations of Ang II, NA in tissue lysates at 3, 5 and 7 days post infection (dpi).

RESULTS

The concentrations of Ang II and NA in serum of the HFMD patients with mild or severe symptoms were significantly higher than that in healthy controls. Additionally, the concentrations of Ang II and NA in serum of severe cases were significantly higher than those mild cases and the increased concentrations of Ang II and NA showed the same time trend during the progression of HFMD in the severe cases. Furthermore, the concentrations of Ang II and NA in target organs of EV71-infected mice including brains, skeletal muscle, and lungs were increased with the progression of EV71 infection in mice. Histopathological alterations were observed in the brains, skeletal muscle and lungs of EV71-infected mice.

CONCLUSION

Our study suggested that activation of the RAS is implicated in the pathogenesis of severe HFMD.