Cancer Stem Cells in Metastatic Head and Neck Cutaneous Squamous Cell Carcinoma Express Components of the Renin-Angiotensin System

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.

Development of CAR-NK Cells Targeting cSCC-Specific Antigens for Precision Immunotherapy

Cutaneous squamous cell carcinoma (cSCC), a non-melanoma skin cancer that is frequently diagnosed, is distinguished by its propensity for aggressive behavior, frequent poor response to standard therapy, and capacity to metastasize to distant areas. Utilizing the body's natural immune defense mechanisms, particularly through the use of chimeric antigen receptor (CAR) technology, is receiving increasing attention in the dynamic field of oncological therapies. Although T cells have received most of the attention, this strategy has proven to be highly effective in battling some blood-related malignancies. However, there are considerable challenges when using this method in the context of solid tumors. The innate immune system's natural killer (NK) cells are essential parts because they have the ability to detect and destroy cancer cells. CAR-NK cells are a very promising approach because they combine the natural cytotoxic properties of natural killer (NK) cells with the precise targeting skills of chimeric antigen receptor (CAR) technology. With the use of this integrated strategy, the intrinsic diversity of cutaneous squamous cell carcinoma (cSCC) tumors may be successfully targeted, increasing treatment effectiveness and lowering the risk of tumor recurrence. This tactic is improved by the development of dual-specificity chimeric antigen receptors (CARs), which fully resolve the antigen presentation heterogeneity among tumor cells. In conclusion, the use of CAR-NK cells that precisely target cSCC-specific antigens has the potential to drastically transform therapy approaches for cSCC as well as other difficult solid tumors as oncological research advances. In order to create chimeric antigen receptor (CAR)-natural killer (NK) cells that particularly target antigens linked to cutaneous squamous cell carcinoma (cSCC), the goal of this protocol is to present a detailed method. The ultimate objective is to lay the groundwork for the development of precision immunotherapy.

Cancer stem cells of head and neck squamous cell carcinoma; distance towards clinical application; a systematic review of literature

Head and neck squamous cell carcinoma (HNSCC) is the major pathological type of head and neck cancer (HNC). The disease ranks sixth among the most common malignancies worldwide, with an increasing incidence rate yearly. Despite the development of therapy, the prognosis of HNSCC remains unsatisfactory, which may be attributed to the resistance to traditional radio-chemotherapy, relapse, and metastasis. To improve the diagnosis and treatment, the targeted therapy for HNSCC may be successful as that for some other tumors. Nanocarriers are the most effective system to deliver the anti-cancerous agent at the site of interest using passive or active targeting approaches. The system enhances the drug concentration in HCN target cells, increases retention, and reduces toxicity to normal cells. Among the different techniques in nanotechnology, quantum dots (QDs) possess multiple fluorescent colors emissions under single-source excitation and size-tunable light emission. Dendrimers are the most attractive nanocarriers, which possess the desired properties of drug retention, release, unaffecting by the immune system, blood circulation time enhancing, and cells or organs specific targeting properties. In this review, we have discussed the up-to-date knowledge of the Cancer Stem Cells of Head and Neck Squamous Cell Carcinoma. Although a lot of data is available, still much more efforts remain to be made to improve the treatment of HNSCC.

Cancer Metastasis and Treatment Resistance: Mechanistic Insights and Therapeutic Targeting of Cancer Stem Cells and the Tumor Microenvironment

Cancer metastasis and treatment resistance are the main causes of treatment failure and cancer-related deaths. Their underlying mechanisms remain to be fully elucidated and have been attributed to the presence of cancer stem cells (CSCs)-a small population of highly tumorigenic cancer cells with pluripotency and self-renewal properties, at the apex of a cellular hierarchy. CSCs drive metastasis and treatment resistance and are sustained by a dynamic tumor microenvironment (TME). Numerous pathways mediate communication between CSCs and/or the surrounding TME. These include a paracrine renin-angiotensin system and its convergent signaling pathways, the immune system, and other signaling pathways including the Notch, Wnt/β-catenin, and Sonic Hedgehog pathways. Appreciation of the mechanisms underlying metastasis and treatment resistance, and the pathways that regulate CSCs and the TME, is essential for developing a durable treatment for cancer. Pre-clinical and clinical studies exploring single-point modulation of the pathways regulating CSCs and the surrounding TME, have yielded partial and sometimes negative results. This may be explained by the presence of uninhibited alternative signaling pathways. An effective treatment of cancer may require a multi-target strategy with multi-step inhibition of signaling pathways that regulate CSCs and the TME, in lieu of the long-standing pursuit of a 'silver-bullet' single-target approach.

Renal Denervation Influences Angiotensin II Types 1 and 2 Receptors

The sympathetic and renin-angiotensin systems (RAS) are two critical regulatory systems in the kidney which affect renal hemodynamics and function. These two systems interact with each other so that angiotensin II (Ang II) has the presynaptic effect on the norepinephrine secretion. Another aspect of this interaction is that the sympathetic nervous system affects the function and expression of local RAS receptors, mainly Ang II receptors. Therefore, in many pathological conditions associated with an increased renal sympathetic tone, these receptors' expression changes and renal denervation can normalize these changes and improve the diseases. It seems that the renal sympathectomy can alter Ang II receptors expression and the distribution of RAS receptors in the kidneys, which influence renal functions.

Cancer stem cells and tumor heterogeneity: Deciphering the role in tumor progression and metastasis

Tumor heterogeneity, in principle, reflects the variation among different cancer cell populations. It can be termed inter- or intra-tumoral heterogeneity, respectively, based on its occurrence in various tissues from diverse patients or within a single tumor. The intra-tumoral heterogeneity is one of the leading causes of cancer progression and treatment failure, with the cancer stem cells (CSCs) contributing immensely to the same. These niche cells, similar to normal stem cells, possess the characteristics of self-renewal and differentiation into multiple cell types. Moreover, CSCs contribute to tumor growth and surveillance by promoting recurrence, metastasis, and therapeutic resistance. Diverse factors, including intracellular signalling pathways and tumor microenvironment (TME), play a vital role in regulating these CSCs. Although a panel of markers is considered to identify the CSC pool in various cancers, further research is needed to discriminate cancer-specific CSC markers in those. CSCs have also been found to be promising therapeutic targets for cancer therapy. Several small molecules, natural compounds, antibodies, chimeric antigen receptor T (CAR-T) cells, and CAR-natural killer (CAR-NK) cells have emerged as therapeutic tools for specific targeting of CSCs. Interestingly, many of these are in clinical trials too. Despite being a much-explored avenue of research for years, and we have come to understand its nitty-gritty, there is still a tremendous gap in our knowledge concerning its precise genesis and regulation. Hence, a concrete understanding is needed to assess the CSC-TME link and how to target different cancer-specific CSCs by designing newer tools. In this review, we have summarized CSC, its causative, different pathways and factors regulating its growth, association with tumor heterogeneity, and last but not least, discussed many of the promising CSC-targeted therapies for combating cancer metastasis.

Insights Into Vascular Anomalies, Cancer, and Fibroproliferative Conditions: The Role of Stem Cells and the Renin-Angiotensin System

Cells exhibiting embryonic stem cell (ESC) characteristics have been demonstrated in vascular anomalies (VAs), cancer, and fibroproliferative conditions, which are commonly managed by plastic surgeons and remain largely unsolved. The efficacy of the mTOR inhibitor sirolimus, and targeted therapies that block the Ras/BRAF/MEK/ERK1/2 and PI3KCA/AKT/mTOR pathways in many types of cancer and VAs, further supports the critical role of ESC-like cells in the pathogenesis of these conditions. ESC-like cells in VAs, cancer, and fibroproliferative conditions express components of the renin-angiotensin system (RAS) – a homeostatic endocrine signaling cascade that regulates cells with ESC characteristics. ESC-like cells are influenced by the Ras/BRAF/MEK/ERK1/2 and PI3KCA/AKT/mTOR pathways, which directly regulate cellular proliferation and stemness, and interact with the RAS at multiple points. Gain-of-function mutations affecting these pathways have been identified in many types of cancer and VAs, that have been treated with targeted therapies with some success. In cancer, the RAS promotes tumor progression, treatment resistance, recurrence, and metastasis. The RAS modulates cellular invasion, migration, proliferation, and angiogenesis. It also indirectly regulates ESC-like cells via its direct influence on the tissue microenvironment and by its interaction with the immune system. In vitro studies show that RAS inhibition suppresses the hallmarks of cancer in different experimental models. Numerous epidemiological studies show a reduced incidence of cancer and improved survival outcomes in patients taking RAS inhibitors, although some studies have shown no such effect. The discovery of ESC-like cells that express RAS components in infantile hemangioma (IH) underscores the paradigm shift in the understanding of its programmed biologic behavior and accelerated involution induced by β-blockers and angiotensin-converting enzyme inhibitors. The findings of SOX18 inhibition by R-propranolol suggests the possibility of targeting ESC-like cells in IH without β-adrenergic blockade, and its associated side effects. This article provides an overview of the current knowledge of ESC-like cells and the RAS in VAs, cancer, and fibroproliferative conditions. It also highlights new lines of research and potential novel therapeutic approaches for these unsolved problems in plastic surgery, by targeting the ESC-like cells through manipulation of the RAS, its bypass loops and converging signaling pathways using existing low-cost, commonly available, and safe oral medications.

Treatment of glioblastoma with re-purposed renin-angiotensin system modulators: Results of a phase I clinical trial

Glioblastoma is the most common and most aggressive primary brain cancer in adults. Standard treatment of glioblastoma consisting of maximal safe resection, adjuvant radiotherapy and chemotherapy with temozolomide, results in an overall median survival of 14.6 months. The aggressive nature of glioblastoma has been attributed to the presence of glioblastoma stem cells which express components of the renin-angiotensin system (RAS). This phase I clinical trial investigated the tolerability and efficacy of a treatment targeting the RAS and its converging pathways in patients with glioblastoma. Patients who had relapsed following standard treatment of glioblastoma who met the trial criteria were commenced on dose-escalated oral RAS modulators (propranolol, aliskiren, cilazapril, celecoxib, curcumin with piperine, aspirin, and metformin). Of the 17 patients who were enrolled, ten completed full dose-escalation of the treatment. The overall median survival was 19.9 (95% CI:14.1-25.7) months. Serial FET-PET/CTs showed a reduction in both tumor volume and uptake in one patient, an increase in tumor uptake in nine patients with decreased (n = 1), unchanged (n = 1) and increased (n = 7) tumor volume, in the ten patients who had completed full dose-escalation of the treatment. Two patients experienced mild side effects and all patients had preservation of quality of life and performance status during the treatment. There is a trend towards increased survival by 5.3 months although it was not statistically significant. These encouraging results warrant further clinical trials on this potential novel, well-tolerated and cost-effective therapeutic option for patients with glioblastoma.

The Role of the Renin-Angiotensin System in the Cancer Stem Cell Niche

Cancer stem cells (CSCs) drive metastasis, treatment resistance, and tumor recurrence. CSCs reside within a niche, an anatomically distinct site within the tumor microenvironment (TME) that consists of malignant and non-malignant cells, including immune cells. The renin-angiotensin system (RAS), a critical regulator of stem cells and key developmental processes, plays a vital role in the TME. Non-malignant cells within the CSC niche and stem cell signaling pathways such as the Wnt, Hedgehog, and Notch pathways influence CSCs. Components of the RAS and cathepsins B and D that constitute bypass loops of the RAS are expressed on CSCs in many cancer types. There is extensive in vitro and in vivo evidence showing that RAS inhibition reduces tumor growth, cell proliferation, invasion, and metastasis. However, there is inconsistent epidemiological data on the effect of RAS inhibitors on cancer incidence and survival outcomes, attributed to different patient characteristics and methodologies used between studies. Further mechanistic studies are warranted to investigate the precise effects of the RAS on CSCs directly and/or the CSC niche. Targeting the RAS, its bypass loops, and convergent signaling pathways participating in the TME and other key stem cell pathways that regulate CSCs may be a novel approach to cancer treatment.

A Platform for Integrating and Sharing Cancer Stem Cell Data

Advancements in cancer research and treatment have highlighted the need for standardization and sharing of cancer stem cell (CSC) data to facilitate research transparency and to promote collaboration within the scientific community. Although previous applications have attempted to gather and disseminate these data, currently no platform organizes the heterogeneous CSC information into a harmonized project-based framework. The aim of our platform, ReMeDy, is to provide an intelligent informatics solution integrating diverse CSC characteristics, outcomes information, and omics data across clinical, preclinical and in vitro studies. These heterogeneous data streams are organized within a multi-modular framework, subjected to a stringent validation by using standardized ontologies, and stored in a searchable format. To test usefulness of our approach for capturing diverse data related to CSCs, we integrated data from 52 publicly-available CSC projects. We validated the robustness of the platform, by efficiently organizing diverse data elements, and demonstrated its potential for promoting future knowledge discovery driven by aggregation of published data. Next steps include expanding number of uploaded CSC projects and developing additional data visualization tools. The platform is accessible through https://remedy.mssm.edu/.

Cathepsins B, D, and G Are Expressed in Metastatic Head and Neck Cutaneous Squamous Cell Carcinoma

Aim

We have previously demonstrated the presence of two cancer stem cell (CSC) subpopulations within metastatic head and neck cutaneous squamous cell carcinoma (mHNcSCC) expressing components of the renin-angiotensin system (RAS), which promotes tumorigenesis. Cathepsins B, D and G are enzymes that constitute bypass loops for the RAS. This study investigated the expression and localization of cathepsins B, D, and G in relation to CSC subpopulations within mHNcSCC.

Methods

Immunohistochemical staining was performed on mHNcSCC tissue samples from 20 patients to determine the expression and localization of cathepsins B, D, and G. Immunofluorescence staining was performed on two of these mHNcSCC tissue samples by co-staining of cathepsins B and D with OCT4 and SOX2, and cathepsin G with mast cell markers tryptase and chymase. Western blotting and quantitative reverse transcription polymerase chain reaction (RT-qPCR) were performed on five mHNcSCC samples and four mHNcSCC-derived primary cell lines, to determine protein and transcript expression of these three cathepsins, respectively. Enzyme activity assays were performed on mHNcSCC tissue samples to determine whether these cathepsins were active.

Results

Immunohistochemical staining demonstrated the presence of cathepsins B, D and G in in all 20 mHNcSCC tissue samples. Immunofluorescence staining showed that cathepsins B and D were localized to the CSCs both within the tumor nests and peri-tumoral stroma (PTS) and cathepsin G was localized to the phenotypic mast cells within the PTS. Western blotting demonstrated protein expression of cathepsin B and D, and RT-qPCR demonstrated transcript expression of all three cathepsins. Enzyme activity assays showed that cathepsin B and D to be active.

Conclusion

The presence of cathepsins B and D on the CSCs and cathepsin G on the phenotypic mast cells suggest the presence of bypass loops for the RAS which may be a potential novel therapeutic target for mHNcSCC.

Colon adenocarcinoma-derived cells possessing stem cell function can be modulated using renin-angiotensin system inhibitors

The cancer stem cell (CSC) concept proposes that cancer recurrence and metastasis are driven by CSCs. In this study, we investigated whether cells from colon adenocarcinoma (CA) with a CSC-like phenotype express renin-angiotensin system (RAS) components, and the effect of RAS inhibitors on CA-derived primary cell lines. Expression of RAS components was interrogated using immunohistochemical and immunofluorescence staining in 6 low-grade CA (LGCA) and 6 high-grade CA (HGCA) tissue samples and patient-matched normal colon samples. Primary cell lines derived from 4 HGCA tissues were treated with RAS inhibitors to investigate their effect on cellular metabolism, tumorsphere formation and transcription of pluripotency genes. Immunohistochemical and immunofluorescence staining showed expression of AT2R, ACE2, PRR, and cathepsins B and D by cells expressing pluripotency markers. β-blockers and AT2R antagonists reduced cellular metabolism, pluripotency marker expression, and tumorsphere-forming capacity of CA-derived primary cell lines. This study suggests that the RAS is active in CSC-like cells in CA, and further investigation is warranted to determine whether RAS inhibition is a viable method of targeting CSCs.

The Renin-Angiotensin System in the Tumor Microenvironment of Glioblastoma

Simple Summary

Glioblastoma (GB) is the most aggressive brain cancer in humans. Patient survival outcomes have remained dismal despite intensive research over the past 50 years, with a median overall survival of only 14.6 months. We highlight the critical role of the renin–angiotensin system (RAS) on GB cancer stem cells and the tumor microenvironment which, in turn, influences cancer stem cells in driving tumorigenesis and treatment resistance. We present recent developments and underscore the need for further research into the GB tumor microenvironment. We discuss the novel therapeutic targeting of the RAS using existing commonly available medications and utilizing model systems to further this critical investigation.

Abstract

Glioblastoma (GB) is an aggressive primary brain tumor. Despite intensive research over the past 50 years, little advance has been made to improve the poor outcome, with an overall median survival of 14.6 months following standard treatment. Local recurrence is inevitable due to the quiescent cancer stem cells (CSCs) in GB that co-express stemness-associated markers and components of the renin–angiotensin system (RAS). The dynamic and heterogeneous tumor microenvironment (TME) plays a fundamental role in tumor development, progression, invasiveness, and therapy resistance. There is increasing evidence showing the critical role of the RAS in the TME influencing CSCs via its upstream and downstream pathways. Drugs that alter the hallmarks of cancer by modulating the RAS present a potential new therapeutic alternative or adjunct to conventional treatment of GB. Cerebral and GB organoids may offer a cost-effective method for evaluating the efficacy of RAS-modulating drugs on GB. We review the nexus between the GB TME, CSC niche, and the RAS, and propose re-purposed RAS-modulating drugs as a potential therapeutic alternative or adjunct to current standard therapy for GB.

Expression of Components of the Renin-Angiotensin System by Cancer Stem Cells in Renal Clear Cell Carcinoma

This study investigated the expression of components of the renin-angiotensin system (RAS) by cancer stem cells (CSCs) we have recently demonstrated in renal clear cell carcinoma (RCCC). Fifteen RCCC tissue samples underwent immunohistochemical staining for components of the RAS: renin, pro-renin receptor (PRR), angiotensin-converting enzyme (ACE), angiotensin-converting enzyme 2 (ACE2), and angiotensin II receptor 2 (AT2R). Immunofluorescence co-staining or double immunohistochemical staining of these components of the RAS with stemness-associated markers OCT4 or KLF4 was performed on two of the samples. Protein and transcript expression of these components of the RAS in six RCCC tissue samples was investigated using western blotting and reverse transcription quantitative polymerase chain reaction (RT-qPCR), respectively. In addition, angiotensin II receptor 1 (AT1R) was investigated using RT-qPCR only. Immunohistochemical staining demonstrated expression of renin, PRR, and ACE2 in 11, 13, and 13 out of 15 RCCC samples, respectively, while AT2R was expressed in all 15 samples. ACE was detected in the endothelium of normal vasculature only. Double immunohistochemical staining demonstrated localization of ACE2, but not renin, to the KLF4+ CSCs. Immunofluorescence staining showed localization of PRR and AT2R to the OCT4+ CSCs. Western blotting confirmed protein expression of all components of the RAS except renin. RT-qPCR demonstrated transcript expression of all components of the RAS including AT1R, but not AT2R, in all six RCCC tissue samples. This study demonstrated expression of PRR, ACE2, and AT2R by the CSCs within RCCC. Further studies may lead to novel therapeutic targeting of CSCs by manipulation of the RAS in the treatment of this aggressive cancer.