Apoptosis signal-regulating kinase 1 is involved in brain-derived neurotrophic factor (BDNF)-enhanced cell motility and matrix metalloproteinase 1 expression in human chondrosarcoma cells

The stimulation of exosome generation by visfatin polarizes M2 macrophages and enhances the motility of chondrosarcoma

Chondrosarcoma is a malignant bone tumor that arises from abnormalities in cartilaginous tissue and is associated with lung metastases. Extracellular vesicles called exosomes are primarily used as mediators of intercellular signal transmission to control tumor metastasis. Visfatin is an adipokine reported to enhance tumor metastasis, but its relationship with exosome generation in chondrosarcoma motility remains undetermined. Our results found that overexpressing visfatin augments the production of exosomes from chondrosarcoma cells. Visfatin-treated chondrosarcoma exosomes educate macrophage polarization towards the M2 but not M1 phenotype. Interestingly, M2 macrophages polarized by exosomes return to chondrosarcoma cells to facilitate cell motility. According to these findings, chondrosarcoma cells emit more exosomes when treated with visfatin. The stimulation of exosome generation by visfatin polarizes M2 macrophages and enhances the motility of chondrosarcoma.

New advances in the treatment of chondrosarcoma under the PD-1/PD-L1 pathway

ABSTRACT

Bone sarcomas encompass a group of spontaneous mesenchymal malignancies, among which osteosarcoma, Ewing sarcoma, chondrosarcoma, and chordoma are the most common subtypes. Chondrosarcoma, a relatively prevalent malignant bone tumor that originates from chondrocytes, is characterized by endogenous cartilage ossification within the tumor tissue. Despite the use of aggressive treatment approaches involving extensive surgical resection, chemotherapy, and radiotherapy for patients with osteosarcoma, chondrosarcoma, and chordoma, limited improvements in patient outcomes have been observed. Furthermore, resistance to chemotherapy and radiation therapy has been observed in chondrosarcoma and chordoma cases. Consequently, novel therapeutic approaches for bone sarcomas, including chondrosarcoma, need to be uncovered. Recently, the emergence of immunotherapy and immune checkpoint inhibitors has garnered attention given their clinical success in various diverse types of cancer, thereby prompting investigations into their potential for managing chondrosarcoma. Considering that circumvention of immune surveillance is considered a key factor in the malignant progression of tumors and that immune checkpoints play an important role in modulating antitumor immune effects, blockers or inhibitors targeting these immune checkpoints have become effective therapeutic tools for patients with tumors. One such checkpoint receptor implicated in this process is programmed cell death protein-1 (PD-1). The association between PD-1 and programmed cell death ligand-1 (PD-L1) and cancer progression in humans has been extensively studied, highlighting their remarkable potential as biomarkers for cancer treatment. This review comprehensively examines available studies on current chondrosarcoma treatments and advancements in anti-PD-1/PD-L1 blockade therapy for chondrosarcoma.

Hypoxia-regulated exosomes mediate M2 macrophage polarization and promote metastasis in chondrosarcoma

Chondrosarcoma is a primary malignant bone tumor. Traditional therapy is not very effective, and it is prone to metastasis in the late stage. The tumor microenvironment (TME) plays a key role in the progression and metastasis of chondrosarcoma, and hypoxia is one of the key factors in the formation of TME. However, the detailed mechanism of how hypoxia affects tumor progression and metastasis in chondrosarcoma is still not fully understood. In this study, we focused on the mechanism of interaction between hypoxic chondrosarcoma cells (SW1353) and macrophages. Our results suggest that hypoxia enhances the release of exosomes from chondrosarcoma cells. These hypoxia-induced exosomes promoted macrophage polarization towards the M2 phenotype, characterized by the expression of CD163 and CD206, but not the M1 phenotype, characterized by CD86 expression. Further analysis revealed that M2 macrophages polarized by exosomes expressed arginase-1 and feedback to chondrosarcoma cells to promote migration. These results suggest that chondrosarcoma cells secrete more exosomes in a hypoxic microenvironment, and these hypoxia-derived exosomes induce the polarization of macrophages into an M2 phenotype, ultimately promoting the metastatic behavior of chondrosarcoma cells.

Anti-tumor activity of polysaccharides extracted from Pinus massoniana pollen in colorectal cancer- in vitro and in vivo studies

The prevalence and mortality rate of colorectal cancer (CRC) have been increasing dramatically worldwide. Pinus massoniana pollen, a well-known natural food, is one of the most commonly consumed traditional medicines in China. P. massoniana pollen polysaccharides (PPPS) have antitumor effects, but it remains unclear whether they can inhibit CRC. Here, we have demonstrated that PPPS inhibited CRC cell proliferation effectively, induced morphology changes, triggered apoptosis by upregulating key apoptosis-related proteins, and arrested the cell cycle at the G0/G1 phase. Moreover, PPPS markedly inhibited CRC cell metastasis by downregulating MMP-9 and inhibiting epithelial-mesenchymal transition. In vivo, PPPS exhibited potent antitumor activity and no observable toxicity in BALB/c nude mice bearing HCT-116 tumors. Most strikingly, PPPS pre-treatment dramatically inhibited the growth of incipient tumors, although not as effectively as in the PPPS-Ther group. Thus, our results suggest that PPPS can be a potential anti-CRC agent, paving the way for developing complex carbohydrates for tumor prevention and treatment.

Selective striatal cell loss is ameliorated by regulated autophagy of the cortex

AIMS

The harmful cellular environment leads to brain damage, and each brain subregion exhibits a differential vulnerability to its effects. This study investigated the causes of selectively striatal cell loss in systemic 3-nitropropionic acid (3-NP) infused mice.

MAIN METHODS

This study was performed in the neuronal cell line, primary neuron, cultured mouse brain, and mice brain tissues. The 3-NP solution was delivered using an osmotic mini-pump system for 7 days. ROS in brain tissue were detected and evaluated with the signals of CM-H2DCFDA for total cellular ROS and MitoSOX Red for mitochondrial ROS. Cellular ROS and the functional status of mitochondria were assessed with a detection kit and analyzed using flow cytometry. To quantify oxidative damaged DNA, apurinic/apyrimidinic (AP) site numbers in DNA were measured. The protein expression level was assessed using Western blotting, and immunohistochemistry was performed. Cleaved caspase-3 activities were measured by using an enzyme-linked immunosorbent assay (ELISA) kit.

KEY FINDINGS

By 3-NP, mitochondrial dysfunction was higher in the striatum than in the cortex, and mitochondria-derived ROS levels were higher in the striatum than in the cortex. However, autophagy that may restore the energy depletion resulting from mitochondrial dysfunction occurred comparably less in the striatum than in the cortex. Inhibition of ASK1 by NQDI1 regulates MAPK signaling, apoptosis, and autophagy. Regulated autophagy of the cortex improved non-cell autonomously striatal damaged condition.

SIGNIFICANCE

This study illustrated that the different vulnerabilities of the brain subregions, striatum or cortex, against 3-NP are rooted in different mitochondria-derived ROS amounts and autophagic capacity.

BDNF promotes activation of astrocytes and microglia contributing to neuroinflammation and mechanical allodynia in cyclophosphamide-induced cystitis

BACKGROUND

Patients with interstitial cystitis/bladder pain syndrome (IC/BPS) often grieve over a low quality of life brought about by chronic pain. In our previous studies, we determined that neuroinflammation of the spinal dorsal horn (SDH) was associated with mechanisms of interstitial cystitis. Moreover, it has been shown that brain-derived neurotrophic factor (BDNF) participates in the regulation of neuroinflammation and pathological pain through BDNF-TrkB signaling; however, whether it plays a role in cyclophosphamide (CYP)-induced cystitis remains unclear. This study aimed to confirm whether BDNF-TrkB signaling modulates neuroinflammation and mechanical allodynia in CYP-induced cystitis and determine how it occurs.

METHODS

Systemic intraperitoneal injection of CYP was performed to establish a rat cystitis model. BDNF-TrkB signaling was modulated by intraperitoneal injection of the TrkB receptor antagonist, ANA-12, or intrathecal injection of exogenous BDNF. Mechanical allodynia in the suprapubic region was assessed using the von Frey filaments test. The expression of BDNF, TrkB, p-TrkB, Iba1, GFAP, p-p38, p-JNK, IL-1β, and TNF-α in the L6-S1 SDH was measured by Western blotting and immunofluorescence analysis.

RESULTS

BDNF-TrkB signaling was upregulated significantly in the SDH after CYP was injected. Similarly, the expressions of Iba1, GFAP, p-p38, p-JNK, IL-1β, and TNF-α in the SDH were all upregulated. Treatment with ANA-12 could attenuate mechanical allodynia, restrain activation of astrocytes and microglia and alleviate neuroinflammation. Besides, the intrathecal injection of exogenous BDNF further decreased the mechanical withdrawal threshold, promoted activation of astrocytes and microglia, and increased the release of TNF-α and IL-1β in the SDH of our CYP-induced cystitis model.

CONCLUSIONS

In our CYP-induced cystitis model, BDNF promoted the activation of astrocytes and microglia to release TNF-α and IL-1β, aggravating neuroinflammation and leading to mechanical allodynia through BDNF-TrkB-p38/JNK signaling.

Differential Expression of Nerve Growth Factor (NGF) and Brain Derived Neurotrophic Factor (BDNF) in Different Regions of Normal and Preeclampsia Placentae

Background: Our recent study indicates differential protein levels of neurotrophins and angiogenic factors in various regions of the normotensive and preeclampsia (PE) placenta. These changes may be in a response to differential mRNA expression of neurotrophins.Methods: This study examines the mRNA levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in different regions of the placenta in normotensive control (NC) women and women with PE. Thirty NC women and forty one women with PE (18 delivered at term [T-PE] and 23 delivered preterm [PT-PE]) were included in the study. Placental samples were taken from four regions: central basal (CM), central chorionic (CF), peripheral basal (PM), and peripheral chorionic (PF). The mRNA levels of neurotrophins were measured by quantitative real-time PCR.Results: The BDNF mRNA levels were higher in peripheral fetal region as compared to peripheral basal region in NC (p < 0.05) group, PE group (p < 0.05) and term PE group (p < 0.01). The BDNF mRNA levels were lower in the central basal region of preterm PE group (p < 0.05) as compared to the NC group.Conclusion: The present study indicates that NGF and BDNF are expressed differentially across various regions of the placenta. This has implications for selection of the sampling site in the placenta while carrying out placental studies.

An update on current and future treatment options for chondrosarcoma

Introduction: Human chondrosarcomas (CS; a malignant cartilage-forming bone tumor) respond poorly to chemotherapy and radiation treatment, resulting in high morbidity and mortality rates. Expanded treatment options are urgently needed. Areas covered: This article updates our 2014 review, in which we evaluated the CS treatments available at that time and potential treatment options under investigation. Since then, advances in research findings, particularly from Chinese herbal medicines, may be bringing us closer to more effective therapies for CS. In particular, promising findings have been reported from research targeting platelet-derived growth factor receptor. Expert opinion: Few treatment options exist for CS; chemotherapy is not even an option for unresectable disease, in which 5-year survival rates are just 2%. New information about the multitude of genes and signaling pathways that encourage CS growth, invasion and metastasis are clarifying how certain signaling pathways and plant-derived active compounds, especially molecularly-targeted therapies that inhibit the PDGF receptor, interfering with these biological processes. This review summarizes discoveries from the last 5 years and discusses how these findings are fueling ongoing work into effectively dealing with the disease process and improving the treatment of CS.

CCN6-mediated MMP-9 activation enhances metastatic potential of human chondrosarcoma

Chondrosarcomas are primary malignant bone tumors that have a poor prognosis. WNT1-inducible signaling pathway protein-3 (WISP-3, also termed CCN6) belongs to the CCN family of proteins and is implicated in the regulation of various cellular functions, such as cell proliferation, differentiation, and migration. It is unknown as to whether CCN6 affects human chondrosarcoma metastasis. We show how CCN6 promotes chondrosarcoma cell migration and invasion via matrix metallopeptidase-9 (MMP)-9 expression. These effects were abolished by pretreatment of chondrosarcoma cells with PI3K, Akt, mTOR, and NF-κB inhibitors or short interfering (si)RNAs. Our investigations indicate that CCN6 facilitates metastasis through the PI3K/Akt/mTOR/NF-κB signaling pathway. CCN6 and MMP-9 expression was markedly increased in the highly migratory JJ012(S10) cell line compared with the primordial cell line (JJ012) in both in vitro and in vivo experiments. CCN6 knockdown suppressed MMP-9 production in JJ012(S10) cells and attenuated cell migration and invasion ability. Importantly, CCN6 knockdown profoundly inhibited chondrosarcoma cell metastasis to lung. Our findings reveal an important mechanism underlying CCN6-induced metastasis and they highlight the clinical significance between CCN6 and MMP-9 in regard to human chondrosarcoma. CCN6 appears to be a promising therapeutic target in chondrosarcoma metastasis.

Matrix metalloproteinases-2 (MMP-2) and matrix metalloproteinases -9 (MMP-9) are differentially expressed in different regions of normal and preeclampsia placentae

Matrix metalloproteinases (MMPs) are involved in the extracellular matrix (ECM) remodeling during human placentation and parturition and have been shown to be associated with oxidative stress. Placental regional changes in oxygen availability and oxidative stress indices may influence regional differences in expression of MMPs. This study examines the protein and mRNA levels of MMP-2 and MMP-9 in different regions of the placenta in normotensive control (NC) women and women with preeclampsia (PE). Fifty-two NC women and 43 women with PE (18 delivered at term [T-PE] and 25 delivered preterm [PT-PE]) were recruited. Placental samples were taken from four regions: central basal (CM), central chorionic (CF), peripheral basal (PM), and peripheral chorionic (PF). MMP protein and mRNA levels were measured by ELISA and quantitative real time PCR, respectively. MMP-2 protein levels were higher in all the placental regions (P < 0.05) from PT-PE group as compared to the respective regions from the NC and T-PE groups. MMP-9 mRNA levels were higher in CM region as compared to CF and PM regions (P < 0.05) in the NC group and compared to CF and PF regions (P < 0.05) in the T-PE group. The MMP-9 mRNA levels were lower in the CF region in the PT-PE and T-PE groups (P < 0.05) as compared to the NC group. Elevated levels of MMP-2 protein levels were observed in all regions of PT-PE placenta possibly influencing the degradation of placental ECM. Lower mRNA expression of MMP-9 both in PT-PE and T-PE may contribute to a disturbed placental vascularization.

ASK family and cancer

Cancer is a major problem in public health and is one of the leading causes of mortality worldwide. Many types of cancer cells exhibit aberrant cellular signal transduction in response to stress, which often leads to oncogenesis. Mitogen-activated protein kinase (MAPK) signal cascades are one of the important intracellular stress signaling pathways closely related to cancer. The key molecules in MAPK signal cascades that respond to various types of stressors are apoptosis signal-regulating kinase (ASK) family members; ASK1, ASK2 and ASK3. ASK family members are activated by a wide variety of stressors, and they regulate various cellular responses, such as cell proliferation, inflammation and apoptosis. In this review, we will discuss both the oncogenic and anti-oncogenic roles of the ASK family members in various contexts of cancer development with deeper insights into the involvement of ASK family members in cancer pathology.

Brain-derived neurotrophic factor promotes VEGF-C-dependent lymphangiogenesis by suppressing miR-624-3p in human chondrosarcoma cells

Chondrosarcoma is the second most common primary malignancy of bone, and one of the most difficult bone tumors to diagnose and treat. It is well known that increased levels of vascular endothelial growth factor-C (VEGF-C) promote active tumor lymphangiogenesis and lymphatic tumor spread to regional lymph nodes. Brain-derived neurotrophic factor (BDNF) is known to promote metastasis in human chondrosarcoma cells. Knowing more about the mechanism of BDNF in VEGF-C expression and lymphangiogenesis in human chondrosarcoma would improve our understanding as how to prevent chondrosarcoma angiogenesis and metastasis, which currently lacks effective adjuvant treatment. Here, we found that BDNF expression was at least 2.5-fold higher in the highly migratory JJ012(S10) cell line as compared with the primordial cell line (JJ012). In addition, VEGF-C expression and secretion was markedly increased in JJ012(S10) cells. Conditioned medium from JJ012(S10) cells significantly promoted migration and tube formation of human lymphatic endothelial cells (LECs), whereas knockdown of BDNF attenuated LEC migration and tube formation by suppressing VEGF-C production in JJ012(S10) cells. Mechanistic investigations indicated that BDNF facilitated VEGF-C-dependent lymphangiogenesis through the MEK/ERK/mTOR signaling pathway. We also showed that microRNA (miR)-624-3p expression was negatively regulated by BDNF via the MEK/ERK/mTOR cascade. Importantly, BDNF knockdown profoundly inhibited tumor-associated lymphangiogenesis in vivo. Further analyses identified that BDNF promoted tumor lymphangiogenesis by downregulating miR-624-3p in human chondrosarcoma tissues. In conclusion, this study is the first to reveal the mechanism underlying BDNF-induced lymphangiogenesis. We suggest that BDNF may serve as a promising therapeutic target for the restriction of VEGF-C-mediated tumor lymphangiogenesis and lymphatic metastasis.

Thioredoxin plays a key role in retinal neuropathy prior to endothelial damage in diabetic mice

Diabetes is a chronic metabolic syndrome that results in changes in carbohydrate, lipid and protein metabolism. With diabetes for a long time, it increases the risk of diabetic retinopathy (DR) and long-term morbidity and mortality. Moreover, emerging evidence suggests that neuron damage occurs earlier than microvascular complications in DR patients, but the underlying mechanism is unclear. We investigated diabetes-induced retinal neuropathy and elucidated key molecular events to identify new therapeutic targets for the clinical treatment and prevention of DR. For in vivo studies, a high-fat diet and streptozotocin (STZ) injection were used to generate the diabetes model. Hematoxylin-eosin staining was used for morphological observations and measurements of the outer nuclear layer thickness. Electroretinography (ERG) was used to assess retinal function. For in vitro studies, Neuro2a cells were incubated in normal (5.5 mM) and high-glucose (30 mM) conditions. Flow cytometry assays were performed to analyze apoptosis. Additionally, real-time PCR and Western blotting analyses were carried out to determine gene and protein expression in vitro and in vivo. Taken together, the results indicated that retinal neuropathy occurred prior to endothelial damage induced by diabetes, and thioredoxin (Trx) plays a key role in this process. This underlying mechanism may be related to activation of the Trx/ASK1/p-p38/Trx-interacting protein pathway.

The regulatory and signaling mechanisms of the ASK family

Apoptosis signal-regulating kinase 1 (ASK1) was identified as a MAP3K that activates the JNK and p38 pathways, and subsequent studies have reported ASK2 and ASK3 as members of the ASK family. The ASK family is activated by various intrinsic and extrinsic stresses, including oxidative stress, ER stress and osmotic stress. Numerous lines of evidence have revealed that members of the ASK family are critical for signal transduction systems to control a wide range of stress responses such as cell death, differentiation and cytokine induction. In this review, we focus on the precise signaling mechanisms of the ASK family in response to diverse stressors.

A heteromeric molecular complex regulates the migration of lung alveolar epithelial cells during wound healing

Alveolar type II epithelial cells (ATII) are instrumental in early wound healing in response to lung injury, restoring epithelial integrity through spreading and migration. We previously reported in separate studies that focal adhesion kinase-1 (FAK) and the chemokine receptor CXCR4 promote epithelial repair mechanisms. However, potential interactions between these two pathways were not previously considered. In the present study, we found that wounding of rat ATII cells promoted increased association between FAK and CXCR4. In addition, protein phosphatase-5 (PP5) increased its association with this heteromeric complex, while apoptosis signal regulating kinase-1 (ASK1) dissociated from the complex. Cell migration following wounding was decreased when PP5 expression was decreased using shRNA, but migration was increased in ATII cells isolated from ASK1 knockout mice. Interactions between FAK and CXCR4 were increased upon depletion of ASK1 using shRNA in MLE-12 cells, but unaffected when PP5 was depleted. Furthermore, we found that wounded rat ATII cells exhibited decreased ASK1 phosphorylation at Serine-966, decreased serine phosphorylation of FAK, and decreased association of phosphorylated ASK1 with FAK. These changes in phosphorylation were dependent upon expression of PP5. These results demonstrate a unique molecular complex comprising CXCR4, FAK, ASK1, and PP5 in ATII cells during wound healing.

Peripheral vascular reactivity and serum BDNF responses to aerobic training are impaired by the BDNF Val66Met polymorphism

Besides neuronal plasticity, the neurotrophin brain-derived neurotrophic factor (BDNF) is also important in vascular function. The BDNF has been associated with angiogenesis through its specific receptor tropomyosin-related kinase B (TrkB). Additionally, Val66Met polymorphism decreases activity-induced BDNF. Since BDNF and TrkB are expressed in vascular endothelial cells and aerobic exercise training can increase serum BDNF, this study aimed to test the hypotheses: 1) Serum BDNF levels modulate peripheral blood flow; 2) The Val66Met BDNF polymorphism impairs exercise training-induced vasodilation. We genotyped 304 healthy male volunteers (Val66Val, n = 221; Val66Met, n = 83) who underwent intense aerobic exercise training on a running track three times/wk for 4 mo. We evaluated pre- and post-exercise training serum BDNF and proBDNF concentration, heart rate (HR), mean blood pressure (MBP), forearm blood flow (FBF), and forearm vascular resistance (FVR). In the pre-exercise training, BDNF, proBDNF, BDNF/proBDNF ratio, FBF, and FVR were similar between genotypes. After exercise training, functional capacity (V̇o2 peak) increased and HR decreased similarly in both groups. Val66Val, but not Val66Met, increased BDNF (interaction, P = 0.04) and BDNF/proBDNF ratio (interaction, P < 0.001). Interestingly, FBF (interaction, P = 0.04) and the FVR (interaction, P = 0.01) responses during handgrip exercise (HG) improved in Val66Val compared with Val66Met, even with similar responses of HR and MBP. There were association between BDNF/proBDNF ratio and FBF (r = 0.64, P < 0.001) and FVR (r = -0.58, P < 0.001) during HG exercise. These results show that peripheral vascular reactivity and serum BDNF responses to exercise training are impaired by the BDNF Val66Met polymorphism and such responsiveness is associated with serum BDNF concentrations in healthy subjects.

MicroRNA‑10b suppresses the migration and invasion of chondrosarcoma cells by targeting brain‑derived neurotrophic factor

MicroRNAs (miRs) can lead to mRNA degradation or inhibit protein translation through directly binding to the 3'‑untranslational region (UTR) of their target mRNAs. Deregulation of miR‑10b has been reported to be associated with chondrosarcoma. However, the role of miR‑10b in chondrosarcoma cell migration and invasion, as well as the underlying mechanisms, has not been investigated. In the present study, it was demonstrated that miR‑10b was notably downregulated in the JJ012 and SW1353 chondrosarcoma cell lines compared with the TC28a2 normal chondrocyte line. Treatment with DNA demethylating agent 5‑aza‑2'‑deoxycytidine and histone deacetylase inhibitor 4‑phenylbutyric acid, or transfection with miR‑10b mimics promoted the expression of miR‑10b, which further suppressed the migratory and invasive capacities of JJ012 chondrosarcoma cells. Moreover, brain‑derived neurotrophic factor (BDNF) was identified as a novel target of miR‑10b, and its protein expression level was negatively regulated by miR‑10b in JJ012 cells. Furthermore, overexpression of BDNF reversed the inhibitory effect of miR‑10b upregulation on the migration and invasion of JJ012 cells. In addition, the data suggest that matrix metalloproteinase 1 (MMP1) may be involved in the miR‑10b/BDNF‑mediated chondrosarcoma cell migration and invasion in JJ012 cells. In conclusion, these findings suggest that miR‑10b/BDNF may serve as a potential therapeutic target for chondrosarcoma.

Regional changes of placental vascularization in preeclampsia: a review

Preeclampsia is characterized by vascular dysfunction and results in maternal and fetal morbidity and mortality. The placenta plays a critical role in the growth and development of the fetus, and recent studies indicate that placental architecture, oxygen availability, and oxidative stress indices vary across different regions of the placenta. Our earlier studies have reported altered maternal angiogenesis and differential placental gene expression and methylation patterns of angiogenic factors in women with preeclampsia when compared with normotensive women. We have also demonstrated lower maternal and placental neurotrophin (NT) levels in women with preeclampsia. Studies suggest that oxidative stress is associated with proteases like matrix metalloproteinases (MMPs) and growth factors like NTs and angiogenic factors known to be involved in the process of angiogenesis. Recently, we have reported regionwise differential oxidative stress, antioxidant enzyme activity, and NT levels in placenta from normotensive control women and women with preeclampsia. The current review describes the regional changes in the placenta and highlights the role of placental oxidative stress in influencing regional differences in the expression of angiogenic factors, MMPs, and NTs. This review discusses the need for further research on various growth factors and proteins involved in the process of placental development across different regions of the placenta. This would help to understand whether regional differences in these factors affect the growth and development of the fetus.

The downregulation of thioredoxin accelerated Neuro2a cell apoptosis induced by advanced glycation end product via activating several pathways

Thioredoxin (Trx), a 12 kDa protein, has different functions in different cellular environments, playing important anti-oxidative and anti-apoptotic roles and regulating the expression of transcription factors. Advanced glycation end products (AGEs) are a heterogeneous group of irreversible adducts from glucose-protein condensation reactions and are considered crucial to the development of diabetic nephropathy, retinopathy, neurodegeneration and atherosclerosis. The aim of this study was to use a Trx inhibitor to investigate the effects and mechanism of Trx down-regulation on AGE-induced Neuro2a cell apoptosis. Neuro2a cells were cultured in vitro and treated with different conditions. The apoptosis and proliferation of Neuro2a cells were detected using flow cytometry, DNA-Ladder and CCK8 assays. Rho 123 was used to detect the mitochondrial membrane potential. ROS generation and caspase3 activity were detected using a DCFH-DA probe and micro-plate reader. Western blotting and real-time PCR were used to detect the expression of proteins and genes. We found that the down-regulation of thioredoxin could accelerate AGE-induced apoptosis in Neuro2a cells. A possible underlying mechanism is that the down-regulation of thioredoxin stimulated the up-regulation of ASK1, p-JNK, PTEN, and Txnip, as well as the down-regulation of p-AKT, ultimately increasing ROS levels and caspase3 activity.

p38MAPK activation mediates tumor necrosis factor-α-induced apoptosis in glioma cells

Gliomas are a type of heterogeneous primary central nervous system tumor, which arise from the glial cells; these types of tumor generally respond poorly to surgery, radiation and conventional chemotherapy. Tumor necrosis factor‑α (TNF‑α) has been suggested to produce an antitumor effect by binding to specific receptors on the tumor cell membrane to induce apoptosis. TNF‑α is known to activate a number of signaling pathways, including extracellular signal‑regulated protein kinase, c‑Jun N‑terminal kinase (JNK), p38 mitogen‑activated protein kinase (p38MAPK), nuclear factor‑κB and caspase cascades, depending on the cell type. However, the involvement of p38MAPK signaling in TNF‑α‑induced apoptosis in glioma cells remains unclear. In the current study, the role of p38MAPK in TNF‑α‑induced apoptosis in rat glioma C6 cells was investigated. TNF‑α was observed to induce cell apoptosis and the phosphorylation of p38MAPK in C6 cells. In addition, the inhibition of p38MAPK markedly reduced TNF‑α‑induced apoptosis, while JNK inhibition did not affect apoptosis. Furthermore, p38MAPK transfection altered the cell cycle of glioma cells and increased the rate of apoptosis. It also led to an increase in the level of soluble TNF‑α in the culture supernatant and membrane TNF receptor I levels in tumor cells. In conclusion, the results of the current study demonstrated that the activation of p38MAPK mediates TNF‑α‑induced apoptosis in glioma C6 cells, suggesting p38MAPK as a potential target for glioma therapy.

Brain-derived neurotrophic factor increases vascular endothelial growth factor expression and enhances angiogenesis in human chondrosarcoma cells

Chondrosarcomas are a type of primary malignant bone cancer, with a potent capacity for local invasion and distant metastasis. Brain-derived neurotrophic factor (BDNF) is commonly upregulated during neurogenesis. The aim of the present study was to examine the mechanism involved in BDNF-mediated vascular endothelial growth factor (VEGF) expression and angiogenesis in human chondrosarcoma cells. Here, we knocked down BDNF expression in chondrosarcoma cells and assessed their capacity to control VEGF expression and angiogenesis in vitro and in vivo. We found knockdown of BDNF decreased VEGF expression and abolished chondrosarcoma conditional medium-mediated angiogenesis in vitro as well as angiogenesis effects in vivo in the chick chorioallantoic membrane and Matrigel plug nude mouse models. In addition, in the xenograft tumor angiogenesis model, the knockdown of BDNF significantly reduced tumor growth and tumor-associated angiogenesis. BDNF increased VEGF expression and angiogenesis through the TrkB receptor, PLCγ, PKCα, and the HIF-1α signaling pathway. Finally, we analyzed samples from chondrosarcoma patients by immunohistochemical staining. The expression of BDNF and VEGF protein in 56 chondrosarcoma patients was significantly higher than in normal cartilage. In addition, the high level of BDNF expression correlated strongly with VEGF expression and tumor stage. Taken together, our results indicate that BDNF increases VEGF expression and enhances angiogenesis through a signal transduction pathway that involves the TrkB receptor, PLCγ, PKCα, and the HIF-1α. Therefore, BDNF may represent a novel target for anti-angiogenic therapy for human chondrosarcoma.