NUPR1 acts as a pro-survival factor in human bone marrow-derived mesenchymal stem cells and is induced by the hypoxia mimetic reagent deferoxamine

Iron-Related Genes and Proteins in Mesenchymal Stem Cell Detection and Therapy

Mesenchymal stem cells (MSCs) are located in various tissues of the body. These cells exhibit regenerative and reparative properties, which makes them highly valuable for cell-based therapy. Despite this, majority of MSC-related studies remain to be translated for regular clinical use. This is partly because there are methodical challenges in pre-administration MSC labelling, post-administration detection and tracking of cells, and in retention of maximal therapeutic potential in-vivo. This calls for exploration of alternative or adjunctive approaches that would enable better detection of transplanted MSCs via non-invasive methods and enhance MSC therapeutic potential in-vivo. Interestingly, these attributes have been demonstrated by some iron-related genes and proteins.Accordingly, this unique forward-looking article integrates the apparently distinct fields of iron metabolism and MSC biology, and reviews the utility of iron-related genes and iron-related proteins in facilitating MSC detection and therapy, respectively. Effects of genetic overexpression of the iron-related proteins ferritin, transferrin receptor-1 and MagA in MSCs and their utilisation as reporter genes for improving MSC detection in-vivo are critically evaluated. In addition, the beneficial effects of the iron chelator deferoxamine and the iron-related proteins haem oxygenase-1, lipocalin-2, lactoferrin, bone morphogenetic protein-2 and hepcidin in enhancing MSC therapeutics are highlighted with the consequent intracellular alterations in MSCs. This review aims to inform both regenerative and translational medicine. It can aid in formulating better methodical approaches that will improve, complement, or provide alternatives to the current pre-transplantation MSC labelling procedures, and enhance MSC detection or augment the post-transplantation MSC therapeutic potential.

Advances in Hypoxia-Inducible Factor-1α Stabilizer Deferoxamine in Tissue Engineering

Deferoxamine (DFO) is an iron chelator with FDA approval for the clinical treatment of iron excess. As a well-established stabilizer of hypoxia-inducible factor-1α (HIF-1α), DFO can efficiently upregulate HIF-1α and relevant downstream angiogenic factors, leading to accelerated vascularization. Moreover, as increasing studies have focused on DFO as a hypoxia-mimetic agent in recent years, it has been shown that DFO exhibited multiple functions, including stem cell regulation, immunoregulation, provascularization, and pro-osteogenesis. On the contrary, DFO can bind excess iron ions in wounds of chronic inflammation, while serving as an antioxidant with the characteristic of removing reactive oxygen species. Collectively, these characteristics make DFO a potent modulator in tissue engineering for increasing tissue integration of biomaterials in vivo and facilitating wound healing. This review outlines the activity of DFO as a representative hypoxia-mimetic agent in cells as well as the evolution of its application in tissue engineering. It can be concluded that DFO is a medication with tremendous promise and application value in future trends, which can optimize biomaterials and existing tissue engineering techniques for tissue regeneration.

The Role of HIF-1α in Bone Regeneration: A New Direction and Challenge in Bone Tissue Engineering

The process of repairing significant bone defects requires the recruitment of a considerable number of cells for osteogenesis-related activities, which implies the consumption of a substantial amount of oxygen and nutrients. Therefore, the limited supply of nutrients and oxygen at the defect site is a vital constraint that affects the regenerative effect, which is closely related to the degree of a well-established vascular network. Hypoxia-inducible factor (HIF-1α), which is an essential transcription factor activated in hypoxic environments, plays a vital role in vascular network construction. HIF-1α, which plays a central role in regulating cartilage and bone formation, induces vascular invasion and differentiation of osteoprogenitor cells to promote and maintain extracellular matrix production by mediating the adaptive response of cells to changes in oxygen levels. However, the application of HIF-1α in bone tissue engineering is still controversial. As such, clarifying the function of HIF-1α in regulating the bone regeneration process is one of the urgent issues that need to be addressed. This review provides insight into the mechanisms of HIF-1α action in bone regeneration and related recent advances. It also describes current strategies for applying hypoxia induction and hypoxia mimicry in bone tissue engineering, providing theoretical support for the use of HIF-1α in establishing a novel and feasible bone repair strategy in clinical settings.

HIF-1α Regulates Bone Homeostasis and Angiogenesis, Participating in the Occurrence of Bone Metabolic Diseases

In the physiological condition, the skeletal system's bone resorption and formation are in dynamic balance, called bone homeostasis. However, bone homeostasis is destroyed under pathological conditions, leading to the occurrence of bone metabolism diseases. The expression of hypoxia-inducible factor-1α (HIF-1α) is regulated by oxygen concentration. It affects energy metabolism, which plays a vital role in preventing bone metabolic diseases. This review focuses on the HIF-1α pathway and describes in detail the possible mechanism of its involvement in the regulation of bone homeostasis and angiogenesis, as well as the current experimental studies on the use of HIF-1α in the prevention of bone metabolic diseases. HIF-1α/RANKL/Notch1 pathway bidirectionally regulates the differentiation of macrophages into osteoclasts under different conditions. In addition, HIF-1α is also regulated by many factors, including hypoxia, cofactor activity, non-coding RNA, trace elements, etc. As a pivotal pathway for coupling angiogenesis and osteogenesis, HIF-1α has been widely studied in bone metabolic diseases such as bone defect, osteoporosis, osteonecrosis of the femoral head, fracture, and nonunion. The wide application of biomaterials in bone metabolism also provides a reasonable basis for the experimental study of HIF-1α in preventing bone metabolic diseases.

The role of NUPR1 in response to stress and cancer development

Stress contributes to the development of many human diseases, including cancer. Based on the source of stress, it can be divided into external stress, such as environmental carcinogens, chemicals, and radiation, and internal stress, like endoplasmic reticulum (ER) stress, hypoxia, and oxidative stress. Nuclear Protein 1 (NUPR1, p8 or Com-1) is a small, highly basic transcriptional regulator that participates in regulating a variety of cellular processes including DNA repair, ER stress, oxidative stress response, cell cycle, autophagy, apoptosis, ferroptosis and chromatin remodeling. A large number of studies have reported that NUPR1 expression can be stimulated rapidly in response to various stresses. Thus, NUPR1 is also known as a stress-response gene. Since the role of NUPR1 in breast cancer was identified in 1999, an increasing number of studies sought to reveal its function in cancer. High expression of NUPR1 has been identified in oral squamous cell carcinoma, breast cancer, lung cancer, multiple myeloma, liver cancer and renal cancer. In this review, we summarize current studies of NUPR1 in response to multiple external stressors and internal stressors, and its role in mediating stressors to cause different cell signaling responses. In addition, this review discusses the function of NUPR1 in carcinogenesis, tumorigenesis, metastasis, and cancer therapy. Thus, this review gives a comprehensive insight into the role of NUPR1 in mediating signals from stress to different cell responses, and this process plays a role in the development of cancer.

Insight in Hypoxia-Mimetic Agents as Potential Tools for Mesenchymal Stem Cell Priming in Regenerative Medicine

Hypoxia-mimetic agents are new potential tools in MSC priming instead of hypoxia incubators or chambers. Several pharmaceutical/chemical hypoxia-mimetic agents can be used to induce hypoxia in the tissues: deferoxamine (DFO), dimethyloxaloylglycine (DMOG), 2,4-dinitrophenol (DNP), cobalt chloride (CoCl2), and isoflurane (ISO). Hypoxia-mimetic agents can increase cell proliferation, preserve or enhance differentiation potential, increase migration potential, and induce neovascularization in a concentration- and stem cell source-dependent manner. Moreover, hypoxia-mimetic agents may increase HIF-1α, changing the metabolism and enhancing glycolysis like hypoxia. So, there is clear evidence that treatment with hypoxia-mimetic agents is beneficial in regenerative medicine, preserving stem cell capacities. These agents are not studied so wildly as hypoxia but, considering the low cost and ease of use, are believed to find application as pretreatment of many diseases such as ischemic heart disease and myocardial fibrosis and promote cardiac and cartilage regeneration. The knowledge of MSC priming is critical in evaluating safety procedures and use in clinics. In this review, similarities and differences between hypoxia and hypoxia-mimetic agents in terms of their therapeutic efficiency are considered in detail. The advantages, challenges, and future perspectives in MSC priming with hypoxia mimetic agents are also discussed.

NUPR1 participates in YAP-mediate gastric cancer malignancy and drug resistance via AKT and p21 activation

OBJECTIVES

To assess nuclear protein 1 (NUPR1) level in human gastric cancer (GC) cells, explore the effects of NUPR1 on GC progression, and investigate the possible regulatory mechanism.

METHODS

Immunohistochemistry (IHC), Immunoblot and quantitative PCR assays were conducted to detect the NUPR1 level in human GC tissues and corresponding normal tissues. Also, NUPR1 expression level correlates with clinical features of GC patients. 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT), transwell assays, Immunoblot assays, and flow cytometry (FCM) assays were used to evaluate the effects of NUPR1 on the proliferation, invasion, epithelial-mesenchymal transformation (EMT) and apoptosis of GC cells in vitro. Immunoblot assays were performed to detect the potential mechanism in NUPR1-mediated drug resistance.

KEY FINDINGS

We found the expression of NUPR1 was upregulated in human gastric cancer tissues and correlated with the clinical features including tumour size, tumour stage and, lymph node metastasis. We further noticed that the depletion of NUPR1 inhibited the invasion and EMT of gastric cancer cells and stimulated the apoptosis. In doxorubicin-resistant gastric cancer cells, yes-associated protein (YAP) activation was up-regulated, and YAP could regulate the expression of NUPR1 to affect drug-resistance. We further provided the evidence that overexpression of NUPR1 reversed the effect of YAP knockdown on cell malignancy and drug resistance via regulating AKT and p21 pathway.

CONCLUSIONS

Our findings indicated the involvement of NUPR1 in the progression of gastric cancer and elucidated its molecular mechanism in regulating drug resistance.

Iron depletion with deferoxamine protects bone marrow-derived mesenchymal stem cells against oxidative stress-induced apoptosis

Bone marrow mesenchymal stem cells (BM-MSCs) are multipotent cells with self-renewal properties, making them an ideal candidate for regenerative medicine. Recently, numerous studies show that about more than 99% of transplanted cells are destroyed because of the stressful microenvironment. Meanwhile, in the target organs, iron overload can produce oxidative stress introducing it as the most important stress factor. The present study was aimed at increasing BM-MSCs' viability against oxidative stress microenvironment using iron depletion by deferoxamine (DFO). Mesenchymal stem cells are isolated and characterized from rat bone marrow. Then, the sensitivity of BM-MSCs against H2O2-induced oxidative stress was evaluated through half of the inhibitory concentration (IC50) estimation by using MTT assay. The maximum non-inhibitory concentration of DFO on BM-MSCs was determined. The next step was the comparison between DFO pre-treated BM-MSCs and untreated cells against H2O2-induced apoptosis. BM-MSCs were identified with morphologic and flow cytometry analysis. IC50 of H2O2 was determined as 0.55 mM at 4 h. Also, the maximum non-inhibitory concentration of DFO was ascertained as 5 μM at 48 h. Our results demonstrated that pretreatment with DFO significantly potentiates BM-MSCs against H2O2-induced oxidative stress which was confirmed by MTT assay, AO/EB double staining, DAPI staining, and activated caspase 3 quantification as well as western blot test. Expression of cleaved caspase 3 and pAKT/AKT ratio obviously demonstrated DFO can resist the cells against cytotoxicity. These findings may help to develop better stem cell culture medium for MSC-based cell therapy. Moreover, regulation of cell stress can be used in practical subjects.

Hypoxia and autophagic response of obese adult rat adipocytes which differ in nutritional state during childhood

The prevalence of obesity in adults is increasing worldwide, which is problematic since obesity is associated with degenerative diseases. Nowadays Indonesia is facing an interesting phenomenon since there are adults who have been obese since childhood and others who conversely were undernourished while young. The biological differences of these two types of obesities are not well understood. This study aims to analyse the difference in the size and number of visceral adipocytes, HIF-1α, HIF-2α and MAP1LC3A/LC3 in obese adult rat groups that were undernourished at a young age compared to groups who were normal or even already fat from childhood. We analyzed Hif-1α, Hif-2α, Lc3 mRNA by RT-qPCR; HIF-1α, HIF-2α, MAP1LC3A/LC3 protein level by ELISA. The HIF-1α and HIF-2α protein level of visceral adipocytes derived from the group of rat which were undernourished while young increased significantly compared to the group which was overnourished. The visceral adipocytes of the group which was overnourished since childhood showed an increase in Hif-2α mRNA level. The Lc3 mRNA of the rat group which were undernourished since young increased significantly compared to rat group which was obese since childhood.

MicroRNA-325-3p prevents sevoflurane-induced learning and memory impairment by inhibiting Nupr1 and C/EBPβ/IGFBP5 signaling in rats

Endoplasmic reticulum stress-induced neuronal apoptosis contributes to neurotoxicity observed after sevoflurane exposure. However, the molecular mechanism underlying the resulting learning and memory impairments remains unknown. Here, we investigated the roles of miR-325-3p and Nupr1 in sevoflurane-induced learning and memory impairments in neonatal rats and HCN-2 human cortical neuronal cells. We found that in both neonatal rats and HCN-2 cells, sevoflurane exposure impairs learning and memory in neonatal rats and increases expression of Nupr1, the endoplasmic reticulum stress marker proteins C/EBPβ and IGFBP5, and the apoptosis-related protein markers cleaved-Caspase-3 and Bax. Using bioinformatics tools to identify microRNAs that bind to Nupr1, we found that miR-325-3p is downregulated in hippocampal neurons exposed to sevoflurane. Moreover, Nupr1 knockdown and miR-325-3p overexpression improved the rats’ performance in learning and memory tests and reduced sevoflurane-induced apoptosis in vitro and in vivo. These results suggest that miR-325-3p blocks sevoflurane-induced learning and memory impairments by inhibiting Nupr1 and the downstream C/EBPβ/IGFBP5 signaling axis in neonatal rats. MiR-325-3p may therefore be a useful therapeutic target in sevoflurane-induced neurotoxicity.

Quercetin induced NUPR1-dependent autophagic cell death by disturbing reactive oxygen species homeostasis in osteosarcoma cells

Osteosarcoma is a primary bone aggressive cancer, affecting adolescents worldwide. Quercetin (a natural polyphenolic compound) is a polyphenolic flavonoid compound found in a variety of plants. It has been demonstrated to exert cytostatic activity against a variety of human cancer, including the human osteosarcoma. However, its efficacy in the treatment of osteosarcoma and the underlying antitumor mechanism has not been fully elucidated yet. In this study, we exposed MG-63 cells to different concentrations of quercetin (50, 100 and 200 µM) for 24 h. Here, we show that quercetin increased autophagic flux in the MG-63 cells, as evidenced by the upregulation of LC3B-II/LC3B-I and downregulation of P62/SQSTM1. Moreover, the autophagy inhibitor Bafilomycin A1 or genetic blocking autophagy with ATG5 knockdown decreased quercetin-induced cell death, indicating quercetin triggered autophagic cell death in MG-63 cells. Specifically, quercetin increased NUPR1 expression and activated of NUPR1 reporter activity, which contributed to the expression of autophagy-related genes and subsequent initiated autophagic cell death in osteosarcoma cells. Importantly, the increased expression NUPR1 were tightly related to the disturbance of reactive oxygen species (ROS) homeostasis, which could be prevented by inhibiting intracellular ROS with NAC. Finally, NAC also abolished quercetin-induced autophagic cell death in vivo. Taken together, these data demonstrate that quercetin induces osteosarcoma cell death via inducing excessive autophagy, which is mediated through the ROS-NUPR1 pathway. Quercetin application may be a promising and practical strategy for osteosarcoma treatment in clinical practice.