Magnesium inhibits the calcification of the extracellular matrix in tendon-derived stem cells via the ATP-P2R and mitochondrial pathways

Mechanical Force Induces Osteogenic Differentiation of Murine Induced Pluripotent Stem Cells via TGF-β Signalling

OBJECTIVES

Mechanical forces are pivotal in regulating various cellular responses, particularly in periodontal ligament and bone. However, the effects of mechanical force are contingent upon several factors, including force types, duration, magnitude and the differentiation stage of the cells. The present study investigated the impact of intermittent compressive force (ICF) on osteogenic differentiation in murine gingiva-derived induced pluripotent stem cells (miPS).

MATERIALS AND METHODS

Adherent retinoic acid-treated miPS were subjected to ICF in a serum-free medium for 24 h. Real-time polymerase chain reaction, western blot analysis and immunofluorescence staining were employed to evaluate mRNA and protein expression patterns. In vitro mineralisation was assessed using alizarin red S staining.

RESULTS

Our findings revealed that ICF treatment induced the expression of osteogenic markers, including Runx2, Col1a1, Opn and Dlx5. Furthermore, ICF promoted the release of extracellular adenosine triphosphate (ATP) at 24 h. Pretreatment with ICF increased in vitro mineralisation, while ATP priming did not enhance mineralisation in adherent retinoic acid-treated miPS. A TGF-β inhibitor attenuated the ICF-upregulated Runx2, Col1a1, Opn and Dlx5 as well as the ICF-induced in vitro mineralisation.

CONCLUSION

Collectively, our results suggest that ICF can induce osteogenic differentiation of adherent retinoic acid-treated miPS, mediated through TGF-β signalling. Eventually, such information could be of value in controlling iPS responses during regenerative treatment applications.

Ectopic calcifications in the musculoskeletal field: the basis for preventive and curative pharmacological strategies

Ectopic calcifications occur in tendons, ligaments, entheses, muscles, and fasciae, and are often associated with pain and inflammation. In clinical settings, these calcifications are commonly treated by physical therapy and/or surgical interventions. However, there is not enough understanding of pharmacological treatments as primary cures, supportive therapy to physical or surgical treatment, or even preventive measures to avoid or diminish the development of ectopic calcifications. Here, we summarize preclinical and clinical evidence for pharmacological candidates for treatment/prevention of ectopic calcification in the context of painful syndromes in the musculoskeletal field. Specifically, we discuss the potential mechanisms of nonsteroidal anti-inflammatory drugs, corticosteroids, H2-receptor blockers, bisphosphonates, minocycline, biologics, ACTH analogues, colchicine, calcium channel blockers, vitamins K2 and D, magnesium, zinc, curcumin, and phytates. Given that ectopic calcification is sometimes paradoxically associated with reduced bone mineralization, it appears particularly reasonable to employ strategies that can both inhibit ectopic calcification and promote bone mineralization, such as bisphosphonates and the combination of vitamin K2 and vitamin D, along with other supplements such as magnesium and zinc. Future studies need to test whether differential therapeutic approaches are needed in different phases of the disease and whether different mechanisms of ectopic calcification require different therapeutic strategies. A precondition for such approaches is further clinical and/or imaging delineation and differentiation of various types and phases of calcific diseases. Finally, it is essential to ensure that anti-calcification effects of new treatment strategies do not harm bone formation and skeletal mineralization.

Advancements in biomaterials and scaffold design for tendon repair and regeneration

Tendon injuries present a significant clinical challenge due to their limited natural healing capacity and the mechanical demands placed on these tissues. This review provides a comprehensive evaluation of the current strategies and advancements in tendon repair and regeneration, focusing on biomaterial innovations and scaffold design. Through a systematic literature search of databases such as PubMed, Scopus, and Web of Science, key studies were analyzed to assess the efficacy of biocompatible materials like hydrogels, synthetic polymers, and fiber-reinforced scaffolds in promoting tendon healing. Emphasis is placed on the role of collagen fiber architecture, including fiber diameter, alignment, and crimping, in restoring the mechanical strength and functional properties of tendons. Additionally, the review highlights emerging techniques such as electrospinning, melt electrowriting, and hybrid textile methods that allow for precise scaffold designs mimicking native tendon structures. Cutting-edge approaches in regenerative medicine, including stem cell therapies, bioelectronic devices, and bioactive molecules, are also explored for their potential to enhance tendon repair. The findings underscore the transformative impact of these technologies on improving tendon biomechanics and functional recovery. Future research directions are outlined, aiming to overcome the current limitations in scaffold mechanical properties and integration at tendon-bone and tendon-muscle junctions. This review contributes to the development of more effective strategies for tendon regeneration, advancing both clinical outcomes and the field of orthopedic tissue engineering.

Pathological calcification in canine tendon-derived cells is modulated by extracellular ATP

Tendon calcification is a commonly associated with degenerative tendinopathy of the Achilles tendons in dogs. It is characterised by the formation of calcific deposits and is refractory to treatment, often re-forming after surgical removal. Little is known about its pathogenesis and therefore the aims of this study were to develop an in vitro model of canine tendon calcification and use this model to investigate mechanisms driving calcification. Cells from the canine Achilles tendon were cultured with different calcifying media to establish which conditions were best able to induce specific, cell-mediated calcification. Once optimum calcification conditions had been established, the effect of ATP treatment on calcification was assessed. Results revealed that 2 mM di-sodium phosphate combined with 2 mM calcium chloride provided the optimum calcifying conditions, increasing calcium deposition and expression of osteogenic-related genes similar to those observed in tendon calcification in vivo. ATP treatment inhibited calcification in a dose-dependent manner, reducing calcium deposition and increasing cell viability, while osteogenic-related genes were no longer upregulated. In conclusion, the in vitro model of canine tendon calcification developed in this study provides the ability to study mechanisms driving tendon calcification, demonstrating that ATP plays a role in modulating tendon calcification that should be explored further in future studies.

Compound-composed Chinese medicine of Huachansu triggers apoptosis of gastric cancer cells through increase of reactive oxygen species levels and suppression of proteasome activities

BACKGROUND

Huachansu (HCS), a known Chinese patent drug extracted from the Chinese toad skin, is frequently used for the treatment of various advanced cancers, especially gastric cancer, due to the good therapeutic effect. However, it is rather difficult to clarify the active substances and molecular mechanisms involved owing to the lack of appropriate research strategies. We recently proposed the concept and research ideas of compound-composed Chinese medicine formula.

PURPOSE

To discover compound-composed Chinese medicine from Huachansu and to explore its mechanism of action in inducing apoptosis of gastric cancer cells.

METHOD

Network pharmacology combined with serum pharmacochemistry was utilized to screen the predominant active constituents from HCS against gastric cancer. Then, the compound-composed Chinese medicine of HCS (CCMH) was prepared according to their relative contents in serum. The pharmacological effects and potential mechanisms for CCMH were investigated by assays for cell viability, cell cycle, apoptosis, mitochondrial membrane potential (MMP), proteomics, reactive oxygen species (ROS), N-Acetylcysteine (NAC) antagonism, proteasome activity, and western blot.

RESULTS

CCMH was comprised of arenobufagin (11.14%), bufalin (18.67%), bufotalin (7.33%), cinobufagin (16.67%), cinobufotalin (16.74%), gamabufotalin (8.45%), resibufogenin (12.03%), and telocinobufagin (8.97%). CCMH evidently induced proliferation inhibition, cell cycle arrest, apoptosis, and MMP collapse in gastric cancer cells, possessing the better activities than HCS. Proteomic analysis showed that CCMH influenced ROS pathway, ubiquitin proteasome system, and PI3K/Akt and MAPK signaling pathways. CCMH markedly enhanced intracellular ROS levels in gastric cancer cells, which was reversed by NAC. Accordingly, NAC antagonized the apoptosis-inducing effect of CCMH. Significantly decreased proteasome 20S activity by CCMH was observed in gastric cancer cells. CCMH also regulated the expression of key proteins in PI3K/Akt and MAPK signaling pathways.

CONCLUSION

CCMH possesses more significant apoptotic induction effects on gastric cancer cells than HCS, which is achieved primarily through suppression of proteasome activities and increase of ROS levels, followed by regulating PI3K/Akt and MAPK signaling pathways. Network pharmacology combined with serum pharmacochemistry is an effective strategy for discovering compound-composed Chinese medicine from traditional Chinese medicine, which can help clarify the pharmacological substances and mechanisms of action for traditional Chinese medicine.

Bie-Jia-Ruan-Mai-Tang, a Chinese Medicine Formula, Inhibits Retinal Neovascularization in Diabetic Mice Through Inducing the Apoptosis of Retinal Vascular Endothelial Cells

Proliferative diabetic retinopathy (PDR) is one of the main complications of diabetes, mainly caused by the aberrant proliferation of retinal vascular endothelial cells and the formation of new blood vessels. Traditional Chinese medicines possess great potential in the prevention and treatment of PDR. Bie-Jia-Ruan-Mai-Tang (BJ), a Chinese medicine formula, has a good therapeutic effect on PDR clinically; however, the mechanism of action involved remains unclear. Therefore, we investigated the effect of BJ on PDR through in vitro and in vivo experiments. A diabetic mouse model with PDR was established by feeding a high-fat–high-glucose diet combined with an intraperitoneal injection of streptozotocin (STZ), while high-glucose-exposed human retinal capillary endothelial cells (HRCECs) were employed to mimic PDR in vitro. The in vivo experiments indicated that BJ inhibited the formation of acellular capillaries, decreased the expression of VEGF, and increased the level of ZO-1 in diabetic mice retina. In vitro experiments showed that high glucose significantly promoted cell viability and proliferation. However, BJ inhibited cell proliferation by cycle arrest in the S phase, thus leading to apoptosis; it also increased the production of ROS, decreased the mitochondrial membrane potential, reduced the ATP production, and also reduced the expressions of p-PI3K, p-AKT, and Bcl-xL, but increased the expressions of Bax and p-NF-κB. These results suggest that BJ induces the apoptosis of HRCECs exposed to high glucose through activating the mitochondrial death pathway by decreasing the PI3K/AKT signaling and increasing the NF-κB signaling to inhibit the formation of acellular capillaries in the retina, thus impeding the development of PDR.

Noncoding RNAs in the Glycolysis of Ovarian Cancer

Energy metabolism reprogramming is the characteristic feature of tumors. The tumorigenesis, metastasis, and drug resistance of ovarian cancer (OC) is dependent on energy metabolism. Even under adequate oxygen conditions, OC cells tend to convert glucose to lactate, and glycolysis can rapidly produce ATP to meet their metabolic energy needs. Non-coding RNAs (ncRNAs) interact directly with DNA, RNA, and proteins to function as an essential regulatory in gene expression and tumor pathology. Studies have shown that ncRNAs regulate the process of glycolysis by interacting with the predominant glycolysis enzyme and cellular signaling pathway, participating in tumorigenesis and progression. This review summarizes the mechanism of ncRNAs regulation in glycolysis in OC and investigates potential therapeutic targets.

Two-Step Approach Using Degradable Magnesium to Inhibit Surface Biofilm and Subsequently Kill Planktonic Bacteria

Bacterial infection remains a great risk in medical implantation surgery. In this paper, we found that degradable metals may be a feasible alternative option of antibacterial implantation materials. It is known that the spalling mechanism of magnesium (Mg) during degradation leads to Mg ions-induced alkaline environment, which is harmful to planktonic bacteria. In this study, we showed that alkaline pH environment is almost harmless to those adhesive bacteria protected in well-formed biofilms. Moreover, experimental results demonstrated that the biofilm formed in the place where Mg spalls are destroyed, releasing the covered bacteria to be planktonic in the alkaline environment. As a result, the colonization of biofilms continues to shrink during the degradation of Mg. It implies that if degradable metal is employed as implantation material, even if bacterial infection occurs, it may be possibly cured without second surgery.

Tendon Extracellular Matrix Assembly, Maintenance and Dysregulation Throughout Life

In his Lissner Award medal lecture in 2000, Stephen Cowin asked the question: "How is a tissue built?" It is not a new question, but it remains as relevant today as it did when it was asked 20 years ago. In fact, research on the organization and development of tissue structure has been a primary focus of tendon and ligament research for over two centuries. The tendon extracellular matrix (ECM) is critical to overall tissue function; it gives the tissue its unique mechanical properties, exhibiting complex non-linear responses, viscoelasticity and flow mechanisms, excellent energy storage and fatigue resistance. This matrix also creates a unique microenvironment for resident cells, allowing cells to maintain their phenotype and translate mechanical and chemical signals into biological responses. Importantly, this architecture is constantly remodeled by local cell populations in response to changing biochemical (systemic and local disease or injury) and mechanical (exercise, disuse, and overuse) stimuli. Here, we review the current understanding of matrix remodeling throughout life, focusing on formation and assembly during the postnatal period, maintenance and homeostasis during adulthood, and changes to homeostasis in natural aging. We also discuss advances in model systems and novel tools for studying collagen and non-collagenous matrix remodeling throughout life, and finally conclude by identifying key questions that have yet to be answered.

Extracellular Nucleotides Regulate Arterial Calcification by Activating Both Independent and Dependent Purinergic Receptor Signaling Pathways

Arterial calcification, the deposition of calcium-phosphate crystals in the extracellular matrix, resembles physiological bone mineralization. It is well-known that extracellular nucleotides regulate bone homeostasis raising an emerging interest in the role of these molecules on arterial calcification. The purinergic independent pathway involves the enzymes ecto-nucleotide pyrophosphatase/phosphodiesterases (NPPs), ecto-nucleoside triphosphate diphosphohydrolases (NTPDases), 5′-nucleotidase and alkaline phosphatase. These regulate the production and breakdown of the calcification inhibitor—pyrophosphate and the calcification stimulator—inorganic phosphate, from extracellular nucleotides. Maintaining ecto-nucleotidase activities in a well-defined range is indispensable as enzymatic hyper- and hypo-expression has been linked to arterial calcification. The purinergic signaling dependent pathway focusses on the activation of purinergic receptors (P1, P2X and P2Y) by extracellular nucleotides. These receptors influence arterial calcification by interfering with the key molecular mechanisms underlying this pathology, including the osteogenic switch and apoptosis of vascular cells and possibly, by favoring the phenotypic switch of vascular cells towards an adipogenic phenotype, a recent, novel hypothesis explaining the systemic prevention of arterial calcification. Selective compounds influencing the activity of ecto-nucleotidases and purinergic receptors, have recently been developed to treat arterial calcification. However, adverse side-effects on bone mineralization are possible as these compounds reasonably could interfere with physiological bone mineralization.

Role of Biomaterials and Controlled Architecture on Tendon/Ligament Repair and Regeneration

Engineering synthetic scaffolds to repair and regenerate ruptured native tendon and ligament (T/L) tissues is a significant engineering challenge due to the need to satisfy both the unique biological and biomechanical properties of these tissues. Long-term clinical outcomes of synthetic scaffolds relying solely on high uniaxial tensile strength are poor with high rates of implant rupture and synovitis. Ideal biomaterials for T/L repair and regeneration need to possess the appropriate biological and biomechanical properties necessary for the successful repair and regeneration of ruptured tendon and ligament tissues.

99mTC-sestamibi breast imaging: Current status, new ideas and future perspectives

Here we proposed the most recent innovations in the use of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi for the management of breast cancer patients. To this end, we reported the recent discoveries concerning: a) the implementation of both instrumental devices and software, b) the biological mechanisms involved in the ⁹⁹mTc-sestamibi uptake in breast cancer cells, c) the evaluation of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi as predictive markers of metastatic diseases. In this last case, we also reported preliminary data about the capability of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi to identify breast cancer lesions with high propensity to form bone metastatic lesions due to the presence of Breast Osteoblast-Like Cells.

High concentration magnesium inhibits extracellular matrix calcification and protects articular cartilage via Erk/autophagy pathway

The significant cytopathological changes of osteoarthritis are chondrocyte hypertrophy, proteoglycan loss, extracellular matrix (ECM) calcification, and terminally, the replacement of cartilage by bone. Meanwhile, magnesium ion (Mg²⁺ ), as the second most abundant divalent cation in the human body, has been proved to inhibit the ECM calcification of hBMSCs (human bone marrow stromal cells), hVSMCs (Human vascular smooth muscle cells), and TDSCs (tendon-derived stem cells) in vitro studies. The ATDC5 cell line, which holds chondrocyte characteristics, was used in this study as an in vitro subject. We found that Mg²⁺ can efficiently suppress the ECM calcification and downregulate both hypertrophy and matrix metalloproteinase-related genes. Meanwhile, Mg²⁺ inhibits the formation of autophagy by inhibiting Erk phosphorylation signaling and lowers the expression of LC3, and eventually effectively reduces the formation of ECM calcification in vitro. In this study, we also used destabilization of the medial meniscus (DMM)-induced osteoarthritis (OA) animal model to further confirm the protective effect of Mg²⁺ on articular cartilage. Compared with the control group (saline-injected), continuous intra-articular magnesium chloride (MgCl₂ ) injection can significantly alleviate the severity of cartilage calcification in OA animal model. Immunofluorescence staining also revealed that saline-injected DMM group had a higher positive rate of LC3 expression in cartilage chondrocytes, compared with MgCl₂ -injected DMM group. In general, Mg²⁺ can significantly downregulate the hypertrophic gene Runx2, MMP13, and Col10α1, upregulate the chondrogenic genes Sox9 and Col1α1, inhibit the Erk phosphorylation signaling, reduce the expression of autophagy protein LC3, and effectively inhibit the ECM calcification of ATDC5. In vivo study also proved that intra-articular injection of Mg²⁺ protected knee cartilage by inhibiting the autophagy formation.

Distribution and Morphological Measurement of Bony Spurs on the Coracoid Process in a Chinese Population

Background

There are few studies on distributions or morphological measurements for bony spurs form at the attachment points of the ligaments and tendons on the coracoid process. The aim of this study was to investigate their most common sites and morphological characteristics, and to propose possible reasons.

Material/Methods

Scapulae with bony spurs on the coracoid process were selected from 377 intact and dry Chinese scapulae. The distribution, height, and transverse and longitudinal diameter of the bony spurs were measured in each coracoid process.

Results

We selected 71 scapulae, 36 left and 35 right, that had bony spurs, from 377 scapulae. The bony spurs were most commonly located at the attachment point of the superior transverse scapular ligament (STSL) (31, 23.66%), while the trapezoid ligament (TL) accounted for the smaller proportion (8, 6.11%). The TSL was the highest, with the minimum transverse and longitudinal diameter, while the TL had the greatest transverse and longitudinal diameters. Only the TSL and TL had a statistically significant difference between the left and the right bony spur regarding the longitudinal diameter (P<0.05).

Conclusions

Bony spurs are more likely to form at the attachment points of ligaments and tendons on the coracoid process, which has a greater risk of traction injuries or attachment points avulsion fractures.

Targeting the PI3K/Akt/mTOR signaling pathway by pterostilbene attenuates mantle cell lymphoma progression

Mantle cell lymphoma (MCL) is an aggressive and mostly incurable B-cell malignancy with frequent relapses after an initial response to standard chemotherapy. Therefore, novel therapies are urgently required to improve MCL clinical outcomes. In this study, MCL cell lines were treated with pterostilbene (PTE), a non-toxic natural phenolic compound primarily found in blueberries. The antitumor activity of PTE was examined by using the Cell Counting Kit-8, apoptosis assays, cell cycle analysis, JC-1 mitochondrial membrane potential assay, western blot analysis, and tumor xenograft models. PTE treatment induced a dose-dependent inhibition of cell proliferation, including the induction of cell apoptosis and cell cycle arrest at the G0/G1 phase. Moreover, the PI3K/Akt/mTOR pathway was downregulated after PTE treatment, which might account for the anti-MCL effects of PTE. Synergistic cytotoxicity was also observed, both in MCL cells and in xenograft mouse models, when PTE was administered in combination with bortezomib (BTZ). The antitumor effects of PTE shown in our study provide an innovative option for MCL patients with poor responses to standardized therapy. It is noteworthy that the treatment combining PTE with BTZ warrants clinical investigation, which may offer an alternative and effective MCL treatment in the future.

High magnesium prevents matrix vesicle-mediated mineralization in human bone marrow-derived mesenchymal stem cells via mitochondrial pathway and autophagy

Magnesium, as a physiological calcium antagonist, plays a vital role in the bone metabolism and the balance between magnesium and calcium is crucial in bone physiology. We recently demonstrated that matrix mineralization in human bone marrow-derived mesenchymal stem cells (hBMSCs) can be suppressed by high Mg²⁺ . However, a complete understanding of the mechanisms involved still remains to be elucidated. As mitochondrial calcium phosphate granules depletion manifests concurrently with the appearance of matrix vesicles (MVs) and autophagy are associated with matrix mineralization, we studied the effect of high extracellular Mg²⁺ on these pathways. Our results first demonstrated that high Mg²⁺ has a significant inhibitory effect on the generalization of extracellular mineral aggregates and the expression of collagen 1 along which the mineral crystals grow. Transmission electron microscope results showed that less amount of MVs were observed inside hBMSCs treated with high Mg²⁺ and high Mg²⁺ inhibited the release of MVs. In addition, high Mg²⁺ significantly suppressed mitochondrial Ca²⁺ accumulation. Autophagy is promoted as a response to osteogenesis of hBMSCs. High Mg²⁺ inhibited the level of autophagy upon osteogenesis and autophagy inhibitor 3-MA significantly suppressed mineralization. Exogenous ATP can reverse the inhibitory effect of high Mg²⁺ by increasing the level of autophagy. Taken together, our results indicate that high Mg²⁺ may modulate MVs-mediated mineralization via suppressing mitochondrial Ca²⁺ intensity and regulates autophagy of hBMSCs upon osteogenesis, resulting in decreased extracellular mineralized matrix deposition. Our results contribute to the understanding of the role of magnesium homeostasis in osteoporosis and the design of magnesium alloys.

DCZ3301, a novel cytotoxic agent, inhibits proliferation in diffuse large B-cell lymphoma via the STAT3 pathway

Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoma in adults, characterized by a rapidly increasing painless mass. A novel compound, DCZ3301, was synthesized that exerted direct cytotoxicity against DLBCL cell lines. The effects of DCZ3301 on DLBCL cells in vitro and in vivo and the associated mechanisms were investigated. DCZ3301 inhibited the viability of DLBCL cell lines, even in the presence of protumorigenesis cytokines. Additionally, the compound induced apoptosis and cell cycle arrest at the G2/M phase by reducing mitochondrial membrane potential. DCZ3301 exerted an antitumor effect through modulation of Akt, extracellular signal-regulated kinases 1/2 (ERK1/2) and janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathways. Furthermore, DCZ3301 downregulates STAT3 phosphorylation by inhibiting Lck/Yes-related novel protein tyrosine kinase (Lyn) activation in DLBCL. A synergistic cytotoxic effect on DLBCL cells was observed upon combination of DCZ3301 with panobinostat. In vivo, intraperitoneal injection of xenograft mice with DCZ3301 resulted in reduced tumor volume. Our preliminary results collectively support the utility of the small-molecule inhibitor DCZ3301 as an effective novel therapeutic option for DLBCL that requires further clinical evaluation.

Magnesium Counteracts Vascular Calcification: Passive Interference or Active Modulation?

Over the last decade, an increasing number of studies report a close relationship between serum magnesium concentration and cardiovascular disease risk in the general population. In end-stage renal disease, an association was found between serum magnesium and survival. Hypomagnesemia was identified as a strong predictor for cardiovascular disease in these patients. A substantial body of in vitro and in vivo studies has identified a protective role for magnesium in vascular calcification. However, the precise mechanisms and its contribution to cardiovascular protection remain unclear. There are currently 2 leading hypotheses: first, magnesium may bind phosphate and delay calcium phosphate crystal growth in the circulation, thereby passively interfering with calcium phosphate deposition in the vessel wall. Second, magnesium may regulate vascular smooth muscle cell transdifferentiation toward an osteogenic phenotype by active cellular modulation of factors associated with calcification. Here, the data supporting these major hypotheses are reviewed. The literature supports both a passive inorganic phosphate-buffering role reducing hydroxyapatite formation and an active cell-mediated role, directly targeting vascular smooth muscle transdifferentiation. However, current evidence relies on basic experimental designs that are often insufficient to delineate the underlying mechanisms. The field requires more advanced experimental design, including determination of intracellular magnesium concentrations and the identification of the molecular players that regulate magnesium concentrations in vascular smooth muscle cells.

Pterostilbene Inhibits Human Multiple Myeloma Cells via ERK1/2 and JNK Pathway In Vitro and In Vivo

Multiple myeloma (MM) is the second most common malignancy in the hematologic system, which is characterized by accumulation of plasma cells in bone marrow. Pterostilbene (PTE) is a natural dimethylated analog of resveratrol, which has anti-oxidant, anti-inflammatory and anti-tumor properties. In the present study, we examined the anti-tumor effect of PTE on MM cell lines both in vitro and in vivo using the cell counting kit (CCK)-8, apoptosis assays, cell cycle analysis, reactive oxygen species (ROS) generation, JC-1 mitochondrial membrane potential assay, Western blotting and tumor xenograft models. The results demonstrated that PTE induces apoptosis in the H929 cell line and causes cell cycle arrest at G0/G1 phase by enhancing ROS generation and reducing mitochondrial membrane potential. The anti-tumor effect of PTE may be caused by the activation of the extracellular regulated protein kinases (ERK) 1/2 and c-Jun N-terminal kinase (JNK) signaling pathways. Additionally, mice treated with PTE by intraperitoneal injection demonstrated reduced tumor volume. Taken together, the results of this study indicate that the anti-tumor effect of PTE on MM cells may provide a new therapeutic option for MM patients.

High glucose induces the expression of osteopontin in blood vessels in vitro and in vivo

Osteopontin (OPN) is involved in mineral metabolism and the inflammatory response while diabetes mellitus is associated with severe and extensive vascular calcification. Therefore, we speculated that OPN could be a key factor in the calcification and dysfunction of blood vessels exposed to high glucose. To identify the relationship between high glucose and OPN, we used high glucose medium to stimulate smooth muscle cells (SMCs) and vascular endothelial cells (VECs) in vitro and diabetic rats for in vivo analyses. As assessed by flow cytometry and western blots, SMC and VEC apoptosis levels increased with high glucose. Potassium and calcium uptake by cells were also increased with high glucose. These findings demonstrated the relationship between mineral metabolism and high glucose. Western blot and quantitative real time polymerase chain reaction analyses demonstrated that OPN increased in vitro with high glucose stimulation. The inflammatory factor ICAM1 and the inhibitory phosphorylation of endothelial nitric-oxide synthase (eNOS) (Thr495) were also upregulated by high glucose. In contrast, the anti-inflammatory factor Nrf2 and the activating phosphorylation of eNOS (Ser1177) were downregulated. Similar to the change of OPN, phosphorylated P38 was increased with high glucose. SB203580, an inhibitor of P38 phosphorylation, downregulated the expression of OPN and related inflammatory factors. Additionally, OPN was increased in the aortas and plasma of diabetic rats. In conclusion, our findings demonstrate that high glucose can induce the expression of OPN, which may be a key factor in the calcification and dysfunction of the vascular wall in diabetes.