3,3'-Diselenodipropionic acid (DSePA) induces reductive stress in A549 cells triggering p53-independent apoptosis: A novel mechanism for diselenides

Nanomaterials-Induced Redox Imbalance: Challenged and Opportunities for Nanomaterials in Cancer Therapy

Cancer cells typically display redox imbalance compared with normal cells due to increased metabolic rate, accumulated mitochondrial dysfunction, elevated cell signaling, and accelerated peroxisomal activities. This redox imbalance may regulate gene expression, alter protein stability, and modulate existing cellular programs, resulting in inefficient treatment modalities. Therapeutic strategies targeting intra- or extracellular redox states of cancer cells at varying state of progression may trigger programmed cell death if exceeded a certain threshold, enabling therapeutic selectivity and overcoming cancer resistance to radiotherapy and chemotherapy. Nanotechnology provides new opportunities for modulating redox state in cancer cells due to their excellent designability and high reactivity. Various nanomaterials are widely researched to enhance highly reactive substances (free radicals) production, disrupt the endogenous antioxidant defense systems, or both. Here, the physiological features of redox imbalance in cancer cells are described and the challenges in modulating redox state in cancer cells are illustrated. Then, nanomaterials that regulate redox imbalance are classified and elaborated upon based on their ability to target redox regulations. Finally, the future perspectives in this field are proposed. It is hoped this review provides guidance for the design of nanomaterials-based approaches involving modulating intra- or extracellular redox states for cancer therapy, especially for cancers resistant to radiotherapy or chemotherapy, etc.

Post-radiation treatment of 3,3'-diselenodipropionic acid augments cell kill by modulating DNA repair and cell migration pathways in A549 cells

Aim of the present study was to test whether ionizing radiation (IR) treatment along with 3,3'-diselenodipropionic acid (DSePA), a redox active organodiselenide achieved better tumor control by suppressing the growth and migration of lung cancer cells. The results indicated that post-IR (2 Gy) treatment of DSePA (5 μM) led to a significantly higher cell death as compared to that of DSePA and IR treatments separately. Importantly, combinatorial treatment also showed reduction in the proportion of cancer stem cells and the clonogenic survival of A549 cells. The mechanistic studies indicated that combinatorial treatment although exhibited reductive environment (marked by decrease in ROS and increase of GSH/GSSG) at early time points (2-6 h postradiation), slowed DNA repair, inhibited epithelial-mesenchymal transition (EMT)/cell migration and induced significant level of apoptosis. DSePA mediated suppression of ATM/DNAPKs/p53 (DNA damage response signaling) and Akt/G-CSF (EMT) pathways appeared to be the major mechanism responsible for its radio-modulating activity. Finally, the combined treatment of IR (2 Gy × 4) and DSePA (0.1-0.25 mg/kg body weight daily through oral gavage) showed a significantly higher tumor suppression of the A549 xenograft as compared to that of DSePA and IR treatments separately in the mouse model. In conclusion, post-IR treatment of DSePA augmented cell kill by inhibiting DNA repair and cell migration in A549 cells.

Inhibition of HAdV-14 induced apoptosis by selenocystine through ROS-mediated PARP and p53 signaling pathways

BACKGROUND

Human Adenovirus (HAdV) can cause severe respiratory symptoms in people with low immunity and there is no targeted treatment for adenovirus infection. Anti-adenoviral drugs have high clinical significance for inhibiting adenovirus infection. Selenium (Se) plays an important role in anti-oxidation, redox signal transduction, and redox homeostasis. The excellent biological activity of Se is mainly achieved by being converted into selenocystine (SeC). Se participates in the active sites of various selenoproteins in the form of SeC. The ability of SeC to resist the virus has raised high awareness due to its unique antioxidative activity in recent years. The antiviral ability of the SeC was determined by detecting the infection rate of the virus in the cells.

METHODS

The experiment mainly investigated the antiviral mechanism of SeC by locating the virus in the cell, detecting the generation of ROS, observing the DNA status of the cell, and monitoring the mitochondrial membrane potential.

RESULTS

In the present study, SeC was designed to resist A549 cells infections caused by HAdV-14. SeC could prevent HAdV-14 from causing cell apoptosis-related to DNA damage. SeC significantly inhibited ROS generation and protect the cells from oxidative damage induced by ROS against HAdV-14. SeC induced the increase of antiviral cytokines such as IL-6 and IL-8 by activating the Jak2 signaling pathway, and repaired DNA lesions by suppressing ATR, p53, and PARP signaling pathways.

CONCLUSION

SeC might provide an effective selenium species with antiviral properties for the therapies against HAdV-14.

3,3'-Diselenodipropionic acid immobilised gelatin gel: a biomimic catalytic nitric oxide generating material for topical wound healing application

Nitric oxide (NO) plays a pivotal role in the wound healing process and promotes the generation of healthy endothelium. In this work, a simple method has been developed for fabricating a diselenide grafted gelatin gel, which reduces NO donors such as S-nitroso-N-acetylpenicillamine (SNAP) by glutathione peroxidase-like mechanism to produce NO. Briefly, the process involved covalently conjugating 3,3'-diselenodipropionic acid (DSePA) with gelatin via carbodiimide coupling. The resulting gelatin-DSePA conjugate (G-Se-Se-G) demonstrated NO production upon incubation with SNAP and glutathione (GSH) with the flux of 4.8 ± 0.6 nmol cm^-2 min^-1 and 1.6 ± 0.1 nmol cm^-2 min^-1 at 10 min and 40 min, respectively. The G-Se-Se-G recovered even after 5 days of incubation with the reaction mixture retaining catalytic activity up to 74%. Subsequently, G-Se-Se-G was suspended (5% w/v) in water with lecithin (6% w/w of gelatin) and F127 (3% w/w of gelatin) to prepare gel through temperature dependant gelation method. The fabricated G-Se-Se-G gel exhibited desirable rheological characteristics and excellent mechanical stability under storage conditions and did not cause any significant toxicity in normal human keratinocytes (HaCaT) and fibroblast cells (WI38) up to 50 μg ml^-1 of selenium equivalent. Finally, mice studies confirmed that topically applied G-Se-Se-G gel and SNAP promoted faster epithelization and collagen deposition at the wound site. In conclusion, the development of a biomimetic NO generating gel with sustained activity and biocompatibility was achieved.

Effect of 3,3'-diselenodipropionic Acid on Dextran Sodium Sulfate-Induced Ulcerative Colitis in Mice

3,3'-Diselenodipropionic acid (DSePA), a synthetic organoselenium compound, has received considerable attention because of its antioxidant properties and safety. Its protective effect against dextran sodium sulfate (DSS)-induced mouse ulcerative colitis (UC) and the role of T helper 17 (Th17) cell proliferation were investigated. Fifty C57BL/6 male mice were randomly assigned to one of five groups: control (Con), DSePA, DSS, low-dose DSePA (LSe), and high-dose DSePA (HSe). Mice in the DSS, LSe, and HSe groups drank 2% DSS to induce UC, and received normal saline, 1 and 2 mg/mL DSePA solution by intraperitoneal injection, respectively. The DSePA group only received 2 mg/mL DSePA solution. After 5 weeks, DSS challenge induced UC in the mice, which manifested as decreased body weight, shortened colon length, the loss of goblet cells, activated proliferating cells, and multiple signs of intestinal lesions by histological observation, all of which were reversed to varying degrees by DSePA administration. DSS upregulated the colonic protein expression of the macrophage marker F4/80 and proinflammatory cytokines (IL-1β, IL-6, and TNFα), whereas DSePA administration downregulated the expression of these factors. DSS upregulated the mRNA expression of retinoic acid receptor-related orphan receptor γt (RORγt, mainly expressed in Th17 cells), IL-17A, and IL-17F and the levels of IL-17A and IL-17F in the colon, whereas DSePA administration decreased them. No difference was observed between the Con group and the DSePA group without DSS induction. Thus, DSePA administration ameliorated DSS-induced UC by regulating Th17-cell proliferation and the secretion of proinflammatory cytokines.

Diselenide-derivative of 3-pyridinol targets redox enzymes leading to cell cycle deregulation and apoptosis in A549 cells

The aim of present study was to understand the mechanism of action of 2,2'-diselenobis(3-pyridinol) or DISPOL in human lung cancer (A549) cells. A549 cells were treated with 10 µM (∼IC₅₀) of DISPOL for varying time points to corelate the intracellular redox changes with its cytotoxic effect. The results indicated that DISPOL treatment led to a time dependant decrease in the basal level of reactive oxygen species (ROS). Additionally, DISPOL treatment elevated the ratio of reduced (GSH) and oxidised (GSSG) glutathione by upregulating gamma-glutamylcysteine ligase (γ-GCL) involved in GSH biosynthesis and inhibiting the activities of redox enzymes responsible for GSH utilization and recycling, such as glutathione-S-transferase (GST) and glutathione reductase (GR). Molecular docking analysis suggests putative interactions of DISPOL with GST and GR which could account for its inhibitory effect on these enzymes. Further, DISPOL induced reductive environment preceded G1 arrest and apoptosis as evidenced by decreased expression of cell cycle genes (Cyclin D1 and Cyclin E1) and elevation of p21 and apoptotic markers (cleaved caspase 3 and cleaved PARP). The combinatorial experiments involving DISPOL and redox modulatory agents such as N-acetylcysteine (NAC) and buthionine sulfoximine (BSO) indeed confirmed the role of reductive stress in DISPOL-induced cell death. Finally, Lipinski's rule suggests attributes of drug likeness in DISPOL. Taken together, DISPOL exhibits a novel mechanism of reductive stress-mediated cell death in A549 cells that warrants future exploration as anticancer agent.

Selenium metabolism and regulation of immune cells in immune-associated diseases

Selenium, as one of the essential microelements, plays an irreplaceable role in metabolism regulation and cell survival. Selenium metabolism and regulation have great effects on physiological systems especially the immune system. Therefore, selenium is tightly related to various diseases like cancer. Although recent research works have revealed much about selenium metabolism, the ways in which selenium regulates immune cells' functions and immune-associated diseases still remain much unclear. In this review, we will briefly introduce the regulatory role of selenium metabolism in immune cells and immune-associated diseases.

Gelatin-lecithin-F127 gel mediated self-assembly of curcumin vesicles for enhanced wound healing

Curcumin, a principal component of Curcuma longa, has a long history of being used topically for wound healing. However, poor aqueous solubility of curcumin leads to poor topical absorption. Recently, gelatin based gel has been reported to overcome this issue. However, the release of curcumin from gelatin gel in the bioavailable or easily absorbable form is still a challenge. The present study reports the development of a composite gel prepared from gelatin, F127 and lecithin using temperature dependant gelation and loading of curcumin within it. Notably, the composite gel facilitated the release of curcumin entrapped within vesicles of ~400 nm size. Further, the composite gel exhibited increase in the storage modulus or gel strength, stability, pore size and hydrophobicity as compared to only gelatin gel. Finally, wound healing assay in murine model indicated that curcumin delivered through composite gel showed a significantly faster healing as compared to that delivered through organic solvent. This was also validated by histopathological and biochemical analysis showing better epithelization and collagen synthesis in the group dressed with curcumin containing composite gel. In conclusion, composite gel facilitated the release of bioavailable or easily absorbable curcumin which in turn enhanced the wound healing.

Unravelling the molecular interaction of diselenodipropionic acid (DSePA) with human serum albumin (HSA)

DSePA, a pharmacologically efficient selenium compound shows strong binding with extracellular carrier protein, Human Serum Albumin.