Hypoxia‐induced proliferation in mesenchymal stem cells and angiotensin II‐mediated PI3K/AKT pathway

Hypoxia could stimulate proliferation of mesenchymal stem cells (MSCs) under certain conditions. This study determined angiotensin II mechanisms and PI3K/AKT pathway in hypoxia‐induced proliferation of MSCs. Hypoxia (3% oxygen) induced cellular proliferation in mouse MSCs and upregulated endogenous angiotensin II and angiotensin‐converting enzyme in the cell culture and expression of AT1 receptors. The expressions of Sox2, not Oct4 and Rex1, were significantly increased by the hypoxia. The blockade of AT1 receptors, not AT2 receptors, depressed hypoxia induced the proliferative effects. Both hypoxia and exogenous angiotensin II activated p‐AKT. Moreover, AT1 receptor inhibitor blocked the effects of hypoxia‐mediated p‐AKT upregulation. The data demonstrated that the hypoxia at 3% oxygen level could induce mouse MSC proliferation, probably as a result of the activation of PI3K signalling pathways via AT1 receptors. Copyright © 2015 John Wiley & Sons, Ltd.     

Retracted: Long noncoding RNA BCAR4 promotes glioma cell proliferation via EGFR/PI3K/AKT signaling pathway

Long noncoding RNA Breast Cancer Antiestrogen Resistance 4 (BCAR4) has been identified to be oncogenic in several cancers. In our study, we demonstrated that BCAR4 expression was significantly upregulated in glioma tissues compared with paired nontumor tissues. In addition, higher BCAR4 level was associated with poor overall survival in patients with glioma. Besides, we also discovered that knockdown of BCAR4 inhibited cell proliferation, whereas BCAR4 overexpression promoted this process. Intriguingly, we proved a cellular transformation of normal human astrocyte cells (NHAs) in response to enforced expression of BCAR4. In addition, we revealed that BCAR4 affected cell proliferation in glioma cells by promoting cell cycle progression and inhibiting cell apoptosis. Mechanistically, we uncovered that BCAR4 activated PI3K/AKT signaling pathway in glioma through upregulating EGFR and interacting with it. Moreover, activating PI3K/AKT pathway could reverse the repressive effects caused by BCAR4 silence on the biological behaviors of glioma cells, whereas inhibition of this pathway rescued the impact of BACR4 upregulation in NHAs. These findings disclosed that BCAR4 contributes to glioma progression by enhancing cell growth via activating EGFR/PI3K/AKT pathway, providing potent evidence that BCAR4 could be an effective new target for treatment and prognosis of glioma patients.     

Retracted: GABARAP promotes bone marrow mesenchymal stem cells-based the osteoarthritis cartilage regeneration through the inhibition of PI3K/AKT/mTOR signaling pathway

Osteoarthritis (OA) is a degenerative disease of the cartilage prevalent in the middle-aged and elderly demographic. Direct transplantation of bone marrow mesenchymal stem cells (BMSCs) or stem cell-derived chondrocytes into the damaged cartilage is a promising therapeutic strategy for OA, but is limited by the poor survival and in situ stability of the chondrocytes. Autophagy is a unique catabolic pathway conserved across eukaryotes that maintains cellular homeostasis, recycles damaged proteins and organelles, and promotes survival. The aim of this study was to determine the role of the proautophagic γ-aminobutyric acid receptor-associated protein (GABARAP) on the therapeutic effects of BMSCs-derived chondrocytes in a rat model of OA, and elucidate the underlying mechanisms. Anterior cruciate ligament transection (ACLT) was performed in Sprague–Dawley rats to simulate OA, and the animals were injected weekly with recombinant human His6-GABARAP protein, BMSCs-derived differentiated chondrocytes (DCs) or their combination directly into the knee cartilage. The regenerative effects of GABARAP and/or DCs were determined in term of International Cartilage Repair Society scores and cartilage thickness. The combination treatment of DCs and GABARAP significantly increased the levels of the ECM proteins Col II and SOX9, indicating formation of hyaline-like cartilage, and decreased chondrocyte apoptosis and inflammation. DCs + GABARAP treatment also upregulated the mediators of the autophagy pathway and suppressed the PI3K/AKT/mTOR pathway, indicating a mechanistic basis of its therapeutic action.     

Retracted: Paeoniflorin promotes angiogenesis and tissue regeneration in a full-thickness cutaneous wound model through the PI3K/AKT pathway

The treatment of wounds remains a clinical challenge because of poor angiogenesis under the wound bed, and increasingly, the patients' need for functional and aesthetically pleasing scars. For the wound healing process, new blood vessels which can deliver nutrients and oxygen to the wound area are necessary. In this study, we investigated the pro-angiogenesis ability and mechanism in wound healing of paeoniflorin (PF), which is a traditional Chinese medicine. In our in vitro results, the ability for proliferation, migration and in vitro angiogenesis in human umbilical vein endothelial cells was promoted by coculturing with PF (1.25–5 μM). Meanwhile, molecular docking studies revealed that PF has excellent binding abilities to phosphatidylinositol-3-kinase (PI3K) and protein kinase B (AKT), and consistent with our western blot results, that PF suppressed PI3K and AKT phosphorylation. Furthermore, to investigate the healing effect of PF in vivo, we constructed a full-thickness cutaneous wound model in rats. PF stimulated the cellular proliferation status, collagen matrix deposition and remodeling processes in vitro and new blood vessel formation at the wound bed resulting in efficient wound healing after intragastric administration of 10 mg·kg⁻¹·day⁻¹ in vivo. Overall, PF performed the pro-angiogenetic effect in vitro and accelerating wound healing in vivo. In summary, the capacity for angiogenesis in endothelial cells could be enhanced by PF treatment via the PI3K/AKT pathway in vitro and could accelerate the wound healing process in vivo through collagen deposition and angiogenesis in regenerated tissue. This study provides evidence that application of PF represents a novel therapeutic approach for the treatment of cutaneous wounds.     

Simvastatin improves the homing of BMSCs via the PI3K/AKT/miR‐9 pathway

Bone marrow‐derived mesenchymal stem cells (BMSCs) have great therapeutic potential for many diseases. However, the homing of BMSCs to injury sites remains a difficult problem. Recent evidence indicates that simvastatin stimulates AKT phosphorylation, and p‐AKT affects the expression of chemokine (CXC motif) receptor‐4 (CXCR4). Therefore, simvastatin may improve the expression of CXCR4 in BMSCs, and microRNAs (miRs) may participate in this process. In this study, we demonstrated that simvastatin increased both the total and the surface expression of CXCR4 in BMSCs. Stromal cell‐derived factor‐1α (SDF?1α)‐induced migration of BMSCs was also enhanced by simvastatin, and this action was inhibited by AMD 3100(a chemokine receptor antagonist for CXCR4). The PI3K/AKT pathway was activated by simvastatin in this process, and LY294002 reversed the overexpression of CXCR4 caused by simvastatin. MiR‐9 directly targeted CXCR4 in rat BMSCs, and simvastatin decreased miR‐9 expression. P‐AKT affected the expression of miR‐9; as the phosphorylation of AKT increased, miR‐9 expression decreased. In addition, LY294002 increased miR‐9 expression. Taken together, our results indicated that simvastatin improved the migration of BMSCs via the PI3K/AKT pathway. MiR‐9 also participated in this process, and the phosphorylation of AKT affected miR‐9 expression, suggesting that simvastatin might have beneficial effects in stem cell therapy.     

IL‐17A promotes cell migration and invasion of glioblastoma cells via activation of PI3K/AKT signalling pathway

Glioblastomas (GBMs) are the most common of both benign and malignant primary brain tumours, in which the inflammatory and immunologic abnormalities are involved. Interleukin‐17A (IL‐17A) plays an important role in various inflammatory diseases and cancers. Several recent studies revealed that the expression of IL‐17A was overexpressed in human GBMs tissue. However, the accurate role of IL‐17A in GBMs remains unclear. In this study, we aimed to explore the effect of IL‐17A on cell migration and invasion of GBMs and the mechanism by which the effects occurred. We found that exogenous IL‐17A promoted significantly cell migration and invasion abilities in two GBMs cell lines (U87MG and U251) in a time‐dependent manner. In addition, the protein expressions of PI3K, Akt and MMP‐2/9 were increased in the GBMs cells challenged by IL‐17A. Furthermore, a tight junction protein ZO‐1 was down‐regulated but Twist and Bmi1 were up‐regulated. Treatment with a PI3K inhibitor (LY294002) significantly reduced the abilities of both migration and invasion in U87MG and U251 cells. LY294002 treatment also attenuated the IL‐17A causing increases of protein levels of PI3K, AKT, MMP‐2/9, Twist and the decreases of protein level of ZO‐1 in the U87MG and U251 cells. Taken together, we concluded that IL‐17A promotes the GBM cells migration and invasion via PI3K/AKT signalling pathway. IL‐17A and its related signalling pathways may be potential therapeutic targets for GBM.     

CHRDL2 promotes osteosarcoma cell proliferation and metastasis through the BMP-9/PI3K/AKT pathway

Various studies demonstrated that bone morphogenetic proteins (BMPs) and their antagonists contribute to the development of cancers. Chordin-like 2 (CHRDL2) is a member of BMP antagonists. However, the role and its relative mechanism of CHRDL2 in osteosarcoma remains unclear. In the present study, we demonstrated that the expression of CHRDL2 was significantly upregulated in osteosarcoma tissues and cell lines compared with adjacent tissues and human normal osteoblast. Inhibition of CHRDL2 decreased the proliferation and colony formation of osteosarcoma cells in vitro, as well as the migration and invasion. CHRDL2 overexpression induced the opposite effects. CHRDL2 can bind with BMP-9, thus decreasing BMP-9 expression and the combination to its receptor protein kinase ALK1. It was predicted that BMP-9 regulates PI3K/AKT pathways using gene set enrichment analysis. Inhibition of CHRDL2 decreased the activation of PI3K/AKT pathway, while overexpression of CHRDL2 upregulated the activation. Increasing the expression of BMP-9 reversed the effects of CHRDL2 overexpression on the activation of PI3K/AKT pathway, as well as the proliferation and metastasis of osteosarcoma cells. Take together, our present study revealed that CHRDL2 upregulated in osteosarcoma tissues and cell lines, and promoted osteosarcoma cell proliferation and metastasis through the BMP-9/PI3K/AKT pathway. CHRDL2 maybe an oncogene in osteosarcoma, as well as novel biomarker for the diagnosis of osteosarcoma.     

PLS3 predicts poor prognosis in pancreatic cancer and promotes cancer cell proliferation via PI3K/AKT signaling

Plastin-3 plays a key role in cancer cell proliferation and invasion, but its prognostic value in pancreatic cancer (PACA) remains poorly defined. In this study, we show that PLS3 messenger RNA is overexpressed in PACA tissue compared with normal tissue. We accumulated 207 cases of PACA specimens to perform immunohistochemical analysis and demonstrated that PLS3 levels correlate with T-classification (p < .001) and pathology (p < .001). Furthermore, overall survival rates (p < .001) in tumors with high PLS3 expression were poor, as assessed through Kaplan–Meier survival analysis. PLS3 was found to be an independent prognostic factor for PACA through multivariate Cox regression analysis. Moreover, we found that PLS3 enhances the proliferation and invasion of tumor cells as assessed through Cell Counting Kit-8, wounding healing assays, and Transwell assays. The upregulation of PLS3 also led to enhanced phosphatidylinositol-3 kinase/protein kinase B signaling in PACA cells. These data suggest that PLS3 is a biomarker to estimate PACA progression and represents a molecular target for PACA therapy.     

PI3K/AKT/mTOR信号通路及其在卵巢癌治疗中的应用

卵巢癌是女性生殖系统常见的恶性肿瘤,发病率居于妇科恶性肿瘤第三位,死亡率居于妇科恶性肿瘤之首。目前对卵巢癌的标准治疗包括肿瘤细胞减灭术及卡铂和紫杉醇的联合化疗。PI3K/AKT/mTOR信号通路在卵巢癌的细胞增殖、侵袭、细胞周期进展、血管生成及耐药中发挥重要作用,是卵巢癌中最常发生改变的细胞内途径。本文对PI3K/AKT/mTOR信号通路及其在卵巢癌增殖和进展中的影响、PI3K/AKT/mTOR信号通路抑制剂在卵巢癌中的治疗应用做简要综述。     

PI3K regulates the activation of NLRP3 inflammasome in atherosclerosis through part-dependent AKT signaling pathway

PI3K is a downstream target of multiple cell-surface receptors, which acts as a crucial modulator of both cell polarization and survival. PI3K/AKT signaling pathway is commonly involved in cancer, atherosclerosis, and other diseases. However, its role in cardiovascular diseases, especially in atherosclerosis, remains to be further investigated. To determine the effect of PI3K/AKT signaling pathway on cellular inflammatory response and oxidative stress, PI3K inhibitor (GDC0941) and AKT inhibitor (MK2206) were used. First, THP-1 cells were incubated with ox-LDL (100 µg/ml) to establish an in vitro atherosclerosis model. The inflammatory factors and foam cell formation were then evaluated to ascertain and compare the effects of PI3K and AKT inhibition. ApoE^−/− mice fed a high-fat diet were used to assess the roles of PI3K and AKT in aortic plaque formation. Our results showed that the inhibition of PI3K or AKT could suppress the activation of NLRP3, decreased the expression levels of p-p65/p65 and reduced the production of mitochondrial reaction oxygen species (mitoROS) in THP-1 cells. Inhibition of PI3K or AKT could also reduced atherosclerosis lesion and plaque area, and decreased the levels of NLRP3 and IL-1β in ApoE^−/− mice. The effect of PI3K inhibition was more significant than AKT. Therefore, PI3K inhibition can retard the progress of atherosclerosis. Besides, there may be other AKT-independent pathways that regulate the formation of atherosclerosis.     

Yak OXGR1 promotes fibroblast proliferation via the PI3K/AKT pathways

Oxoglutarate receptor 1 (OXGR1), as one of the intermediates in G protein-coupled receptors (GPCRs), plays a crucial role in the citric acid cycle receptor of α-ketoglutarate and metabolism. GPCR can control the cell proliferation by regulating the downstream signaling of G protein signaling pathways. The PI3K/AKT pathway transmits the downstream signals of GPCRs and receptor tyrosine kinases. However, the specific role of OXGR1 promoting cell proliferation and differentiation are still unknown. In current study, the over-expression vector and knockdown sequence of yak OXGR1 were transfected into yak fibroblasts, and the effects were detected by a series of assays. The results revealed that OXGR1 expression in yak lung parenchyma tissue was significantly higher than that of other tissues. In yak fibroblasts, the upregulated expression of OXGR1 resulted in activating the PIK3CG (downstream signal) of the PI3K/AKT1 pathway that can upregulated the expression of proliferation genes ( CDK1, PCNA, and CyclinD1) and promote cell proliferation. Conversely, the downregulated expression of OXGR1 inhibited cell proliferation via PI3K/AKT1 pathway. Cell cycle and cell proliferation assays demonstrated that over-expression of OXGR1 can enhanced the DNA synthesis and promoted yak fibroblasts proliferation. While the conversely, knockdown of OXGR1 can decreased DNA synthesis and inhibited cell proliferation. These results illustrated that changes of OXGR1 expression can trigger the fibroblasts proliferation via PI3K/AKT signaling pathway, which indicating that OXGR1 is a novel regulator for cell proliferation and differentiation. Furthermore, these results provide evidence supporting the functional role of GPCRs-PI3K-AKT1 and OXGR1 in cell proliferation.     

Ropivacaine inhibits proliferation and invasion and promotes apoptosis and autophagy in bladder cancer cells via inhibiting PI3K/AKT pathway

Application of a certain concentration of local anesthetics during tumor resection inhibits the progression of tumor. The effects of ropivacaine in bladder cancer (BC) have never been explored. We explored the effects of ropivacaine on the progression of BC in vitro and in vivo. CCK8 assay and EDU staining was conducted to examine cell proliferation. Flow cytometry and transwell assay were performed to evaluate apoptosis and invasion, respectively. Expression of light chain 3 (LC3) was observed through immunofluorescence. Furthermore, the xenograft tumor model of BC was built to detect the effects of ropivacaine in vivo. IHC and TUNEL assay were conducted to detect cell proliferation and apoptosis in vivo. Ropivacaine inhibited the proliferation of T24 and 5639 cells with the 50% inhibitory concentration (IC50) of 20.08 and 31.86 µM, respectively. Ropivacaine suppressed the invasion ability and induces the apoptosis of cells. Besides, ropivacaine triggers obvious autophagy in BC cells. Moreover, ropivacaine blocks the PI3K/AKT signal pathway in BC cells. The impact of ropivacaine on cell viability, motility, and autophagy was reversed by 740 Y-P, the activator of PI3K/AKT signal pathway. The in vivo experiments demonstrated that ropivacaine inhibited the proliferation and mobility of BC. Ropivacaine has anti-carcinoma effects in BC via inactivating PI3K/AKT pathway, providing a new theoretical reference for the use of local anesthetics in the treatment of BC.