Potential molecular mechanisms underlying the effect of arsenic on angiogenesis

In vitro and in vivo investigations on arsenic-induced cartilage degeneration in osteoarthritis

Heavy metals found in the environment, including arsenic (As) pose significant risks to human health and present a risk factor for osteoarthritis (OA). This study researched the impact of As on cartilage degeneration by focusing on the role of As in causing OA in mice. We employed chemical inhibition and inductively coupled plasma mass spectrometry analyses to identify the effect of As on chondrocytes as well as studying its accumulation in organs after oral administration in mice. Additionally, the study examined the effect of intra-articular As treatment on the levels of crucial catabolic factors, namely Hif-2α (Epas1) and Zip8 (Slc39a8), during OA progression. Mice that were administered As orally in conjunction with surgically induced joint instability, had heightened cartilage destruction compared to wild-type mice. Quantitative analysis revealed a significant increase in Hif-2α and Zip8 mRNA expression (p = 0.0352,0.0004 respectively) and protein expression (p = 0.0101,0.008 respectively) post oral administration. Our findings illustrated the role of As in influencing crucial cellular functions that are triggered by reactive oxygen species. These events consequently activate the Akt/Hif-2α/NF-κB pathways, leading to disruptions in articular cartilage homeostasis. This study provides a comprehensive understanding of the impact of As on the development of osteoarthritis.

Current Advances of Nanomedicines Delivering Arsenic Trioxide for Enhanced Tumor Therapy

Arsenic trioxide (ATO) is one of the first-line chemotherapeutic drugs for acute promyelocytic leukemia. Its anti-cancer activities against various human neoplastic diseases have been extensively studied. However, the clinical use of ATO for solid tumors is limited, and these limitations are because of severe systemic toxicity, low bioavailability, and quick renal elimination before it reaches the target site. Although without much success, several efforts have been made to boost ATO bioavailability toward solid tumors without raising its dose. It has been found that nanomedicines have various advantages for drug delivery, including increased bioavailability, effectiveness, dose-response, targeting capabilities, and safety as compared to traditional drugs. Therefore, nanotechnology to deliver ATO to solid tumors is the main topic of this review, which outlines the previous and present medical applications of ATO. We also summarised ATO anti-cancer mechanisms, limitations, and outcomes of combinatorial treatment with chemo agents. As a result, we strongly recommend conducting pre-clinical and clinical studies of ATO, especially nano-system-based ones that might lead to a novel combination therapy for cancer treatment with high efficacy, bioavailability, and low toxicity for cancer patients.

Human endothelial cells promote arsenic-transformed lung epithelial cells to induce tumor growth and angiogenesis through interleukin-8 induction

Arsenic exposure is associated with lung cancer. Angiogenesis is essential for tumor development. However, the role and mechanism of human vascular endothelial cells in tumor growth and angiogenesis induced by arsenic-transformed bronchial epithelial (As-T) cells remain to be elucidated. In this study, we found that endothelial cells significantly increased As-T cell-induced tumor growth compared to those induced by As-T cells alone. To understand the molecular mechanism, we found that endothelial cells co-cultured with As-T cells or cultured in conditioned medium (CM) prepared from As-T cells showed much higher cell migration, proliferation, and tube formation compared to those co-cultured with BEAS-2B (B2B) cells or cultured in CM from B2B. We identified that higher levels of intracellular interleukin 8 (IL-8) were secreted by As-T cells, which activated IL-8/IL-8R signaling to promote endothelial cells migration and tube formation. IL-8 silencing and knockout (KO) in As-T cells, or IL-8 neutralizing antibody dramatically suppressed endothelial cell proliferation, migration, tube formation in vitro, and tumor growth and angiogenesis in vivo, suggesting a key role of IL-8 in As-T cells to induce angiogenesis via a paracrine effect. Finally, blocking of IL-8 receptors C-X-C chemokine receptor type 1 (CXCR1) and CXCR2 with neutralizing antibodies and chemical inhibitors inhibited tube formation, indicating that IL-8Rs on endothelial cells are necessary for As-T cell-induced angiogenesis. Overall, this study reveals an important molecular mechanism of arsenic-induced carcinogenesis, and suggests a new option to prevent and treat arsenic-induced angiogenesis.

Therapeutic Potential of Exosomal circRNA Derived from Synovial Mesenchymal Cells via Targeting circEDIL3/miR-485-3p/PIAS3/STAT3/VEGF Functional Module in Rheumatoid Arthritis

Background

Synovial inflammation and its associated activation of angiogenesis play critical roles in rheumatoid arthritis (RA). Exosomes, as carriers of genetic information including circular RNAs (circRNAs), have been explored as delivery vehicles for therapeutic molecules. However, the effects of synovial mesenchymal stem cells (SMSCs)-derived exosomal circRNAs and their mechanisms of action in RA progression remain unclear.

Methods

SMSCs-derived exosomes (SMSCs-Exos) were administered to a co-culture of RA fibroblast-like synoviocytes (RA-FLS) and human dermal microvascular endothelial cells (HDMECs) in vitro as well as to a collagen-induced arthritis (CIA) mouse model in vivo. Their effects on VEGF expression and angiogenic activity in vitro and the therapeutic efficacy in vivo were evaluated. Exosomes from circEDIL3-overexpressing SMSCs (Ad-circEDIL3-SMSCs-Exos) were used to further determine the role of circEDIL3 in SMSCs-Exo-based therapy.

Results

Both SMSCs-Exos and Ad-circEDIL3-SMSCs-Exos significantly downregulated the expression of VEGF induced by the IL-6/sIL-6R complex in the supernatants of RA-FLS and HDMECs co-culture as well as in the cell lysate of co-cultured RA-FLS, and the extent of reduction was more pronounced in the latter. Subsequent experiments showed that angiogenic activity was significantly downregulated by SMSCs-Exos and Ad-circEDIL3-SMSCs-Exos due to reduced VEGF expression. CircEDIL3 functioned as a sponge for miR-485-3p, which targeted PIAS3. PIAS3 is known to suppress STAT3 activity and reduce downstream VEGF. Injection of SMSCs-Exos or Ad-circEDIL3-SMSCs-Exos reduced synovial VEGF and consequently ameliorated arthritis severity in the CIA mouse model.

Conclusion

The intracellular transfer of circEDIL3 by SMSCs-Exos may be a potential novel therapeutic strategy for RA.

Angiogenesis is Inhibited by Arsenic Trioxide Through Downregulation of the CircHIPK3/miR-149-5p/FOXO1/VEGF Functional Module in Rheumatoid Arthritis

Angiogenesis is a crucial event in the pathogenesis of rheumatoid arthritis (RA). Arsenic trioxide (ATO, As₂O₃) has been reported to inhibit synovial angiogenesis via the vascular endothelial growth factor (VEGF)-centered functional module. However, the exact mechanisms of ATO on VEGF modulation remain unclear. Circular RNAs (circRNAs) are emerging as important regulators in RA, and the detailed mechanisms remain largely unknown. Here, we reported a circRNA (circHIPK3), the expression of which was significantly increased in RA fibroblast-like synoviocytes (RA-FLS) after TNF-α induction. Moreover, VEGF content in the supernatants of a RA-FLS and human dermal microvascular endothelial cell (HDMEC) co-culture as well as in RA-FLS co-cultured was significantly elevated in accordance with circHIPK3 levels. This increased VEGF expression may significantly upregulate endothelial tube formation and transwell migration, as well as microvessel sprouting in the ex vivo aortic ring assay. CircHIPK3 was further illustrated to be a sponge for the forkhead box transcription factor O1 (FOXO1)-targeting miR-149-5p, leading to the changing expression of the downstream VEGF. These networked factors mainly form a functional module regulating angiogenesis in RA-FLS, and the expression of this functional module could be significantly downregulated by ATO with a consistently reduced vascularity in vitro. In the collagen-induced arthritis (CIA) mice model, an intra-articular injection of the adeno-associated virus-si-circHIPK3 or ATO was demonstrated to alleviate the synovial VEGF expression and arthritis severity respectively. Thus, we elucidate a previously unknown mechanism between circRNAs and RA, and ATO has a significant protective effect on RA-FLS and CIA synovium via its inhibition of the angiogenic functional module of circHIPK3/miR-149-5p/FOXO1/VEGF, suggesting great potential for the combination therapy of ATO with circHIPK3 silencing.

The Effects on Angiogenesis of Relevant Inorganic Chemotherapeutics

Angiogenesis is a key process allowing the formation of blood vessels. It is crucial for all the tissues and organs, ensuring their function and growth. Angiogenesis is finely controlled by several mechanisms involving complex interactions between pro- or antiangiogenic factors, and an imbalance in this control chain may result in pathological conditions. Metals as copper, zinc and iron cover an essential role in regulating angiogenesis, thus therapies having physiological metals as target have been proposed. In addition, some complexes of heavier metal ions (e.g., Pt, Au, Ru) are currently used as established or experimental anticancer agents targeting genomic or non-genomic targets. These molecules may affect the angiogenic mechanisms determining different effects that have been only poorly and non-systematically investigated so far. Accordingly, in this review article, we aim to recapitulate the impact on the angiogenic process of some reference anticancer drugs, and how it is connected to the overall pharmacological effects. In addition, we highlight how the activity of these drugs can be related to the role of biological essential metal ions. Overall, this may allow a deeper description and understanding of the antineoplastic activity of both approved or experimental metal complexes, providing important insights for the synthesis of new inorganic drugs able to overcome resistance and recurrence phenomena.

Mechanistic effects of arsenic trioxide on acute promyelocytic leukemia and other types of leukemias

Acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia characterized with a translocation between promyelocytic leukemia gene (PML) on chromosome 15 and retinoic acid receptor alpha gene (RARα) on chromosome 17. Transcription of this fusion gene results in PML/RARα fusion protein blocking expression of critical genes involved in differentiation of myeloid cells through interaction with RAR element. PML/RARα fusion protein prevents normal function of PML and RARα as well as inhibiting apoptosis. Arsenic trioxide (ATO) is an important agent for the treatment of relapsed and newly diagnosed APL. ATO induces apoptosis, autophagy, and partial cellular differentiation as well as inhibiting cell growth and angiogenesis. Recognition of signaling pathways and molecular mechanisms induced by ATO can be effective for discovering novel treatment strategies to target leukemia cells. Also, it can be developed for the treatment of a variety of cancer cells. This review provides a perspective on anticancerous effects of ATO on APL and leukemia cells.