Isovalerylspiramycin I suppresses non-small cell lung carcinoma growth through ROS-mediated inhibition of PI3K/AKT signaling pathway

Novel drugs are required for non-small cell lung cancer (NSCLC) treatment urgently. Repurposing old drugs as new treatments is a practicable approach with time and cost savings. Some studies have shown that carrimycin, a Chinese Food and Drug Administration (CFDA)-approved macrolide antibiotic, possesses potent anti-tumor effects against oral squamous cell carcinoma. However, its detailed component and underlying mechanisms in anti-NSCLC remain unknown. In our study, isovalerylspiramycin I (ISP-I) was isolated from carrimycin and demonstrated a remarkable anti-NSCLC efficacy in vitro and in vivo with a favorable safety profile. It has been proven that in NSCLC cell lines H460 and A549, ISP-I could induce G2/M arrest and apoptosis, which was mainly attributed to ROS accumulation and subsequently PI3K/AKT signaling pathway inhibition. Numerous downstream genes including mTOR and FOXOs were also changed correspondingly. An observation of NAC-induced reverse effect on ISP-I-leading cell death and PI3K/AKT pathway inhibition, emphasized the necessity of ROS signaling in this event. Moreover, we identified ROS accumulation and PI3K/AKT pathway inhibition in tumor xenograft models in vivo as well. Taken together, our study firstly reveals that ISP-I is a novel ROS inducer and may act as a promising candidate with multi-target and low biological toxicity for anti-NSCLC treatment.     

Dieckol exerts anticancer activity in human osteosarcoma (MG-63) cells through the inhibition of PI3K/AKT/mTOR signaling pathway

BackgroundOsteosarcoma (OS) is the most common malignant bone cancer with more metastasis and increased occurrence in children and teen-agers and being responsible for more number of morbidity and mortality worldwide.ObjectiveThe current exploration was planned study the in vitro anticancer actions of dieckol against human OS MG-63 cells via PI3K/AKT/mTOR signaling inhibition.MethodologyThe cytotoxicity of dieckol was scrutinized by MTT assay. Effects of dieckol on the ROS accumulation, apoptotic cell death, and MMP level in the MG-63 cells were studied by respective fluorescence staining assays. The levels of proliferative, inflammatory, and apoptotic markers in the dieckol treated MG-63 cells were scrutinized by marker specific kits. The expressions of PI3K, AKT, and mTOR was assayed by RT-PCR.ResultsThe MTT assay revealed that the dieckol dose dependently prevented MG-63 cells viability and the IC50 was found at 15 µM. Dieckol treatment effectively reduced the MMP level and improved the ROS generation and apoptosis in MG-63 cells. Dieckol also regulated the proliferative (cyclin D1), inflammatory (COX-2, IL-6, TNF-α, and NF-κB), and apoptotic (caspase-3, Bax, Bcl-2) markers in the MG-63 cells. The PI3K/AKT/mTOR signaling in the MG-63 cells were effectively inhibited by the dieckol treatment.ConclusionIn conclusion, our findings from this study recommends that the dieckol could be a talented anticancer candidate for the OS management in the future.     

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.     

PDGF-AA promotes cell-to-cell communication in osteocytes through PI3K/Akt signaling pathway

Osteocytes are the main sensitive cells in bone remodeling due to their potent functional cell pro-cesses from the mineralized bone matrix to the bone surface a...     

Mechanism of cell contact-mediated inhibition of natural killer activity

Natural killer cell activity is inhibited by primary cultures of monolayer cells. In this study, we analyzed the mechanism of the inhibition. Inhibited NK cells showed unaltered binding capacity to NK sensitive K562 cells. The orientation of the effector cells' actin-containing microfilaments, an event known to occur during the programming for the lysis stage in lytic conjugates, was unaffected by the inhibition. In single cell cytotoxicity experiments, the number of killer cells among conjugate-forming cells was reduced. The capacity of the inactivated NK cells to secrete cytotoxic factors upon stimulation with Con A was also impaired. Both NK-resistant inactivating target cells and NK-sensitive K562 cells were sensitive to the toxic factors secreted by NK cells. Thus, the results indicate that the target cell-mediated inactivation of NK cell is based on a block in the lethal hit stage, possibly due to reduced release of toxic factor(s) from the effector cells. The capacity of inactivated effector cells to mediate antibody-dependent cellular cytotoxicity was unimpaired, suggesting that the contact-mediated inhibition of cytotoxicity selectively affects NK cells.     

TLR3 regulates mycobacterial RNA-induced IL-10 production through the PI3K/AKT signaling pathway

Cytokine induction in response to Mycobacterium tuberculosis (Mtb) infection is critical for pathogen control, by (i) mediating innate immune effector functions and (ii) instructing specific adaptive immunity. IL-10 is an important anti-inflammatory cytokine involved in pathogenesis of tuberculosis (TB). Here, we show that TLR3, a sensor of extracellular viral or host RNA with stable stem structures derived from infected or damaged cells, is essential for Mtb-induced IL-10 production. Upon Mycobacterium bovis Bacillus Calmette–Guérin (BCG) infection, TLR3^−/− macrophages expressed lower IL-10 but higher IL-12p40 production, accompanied by reduced phosphorylation of AKT at Ser473. BCG-infected TLR3^−/− mice exhibited reduced IL-10 but elevated IL-12 expression compared to controls. Moreover, higher numbers of splenic Th1 cells and reduced pulmonary bacterial burden and tissue damage were observed in BCG-infected TLR3^−/− mice. Finally, BCG RNA induced IL-10 in macrophages via TLR3-mediated activation of PI3K/AKT. Our findings demonstrate a critical role of TLR3-mediated regulation in the pathogenesis of mycobacterial infection involving mycobacterial RNA, which induces IL-10 through the PI3K/AKT signaling pathway.     

PI3K/Akt信号传导通路与肿瘤

信号转导通路的异常激活是肿瘤细胞的发生、发展重要步骤,PI3K/Akt 信号通路在人类绝大多数恶性肿瘤中被异常激活,其在肿瘤的增殖、存活、细胞运动、抵抗凋亡、血管发生和转移以及对化疗耐药、放疗抗拒中发挥了重要作用.因此,通过对PI3K/Akt 通路的研究进一步了解肿瘤的发生、发展机制,并寻求抗肿瘤药物的新靶点,本文就 PI3K/Akt 信号转导通路的结构特点、与肿瘤发生、发展的关系及其时放化疗的影响作一综述.     

Hypoxia regulates human mast cell adhesion to fibronectin via the PI3K/AKT signaling pathway

ABSTRACT

A decrease in oxygen concentration is a hallmark of inflammatory reactions resulting from infection or homeostasis disorders. Mast cells interact with extracellular matrix and other cells by adhesion receptors. We investigated the effect of hypoxia on integrin-mediated mast cell adhesion to fibronectin. We found that it was mediated by the α5/β1 receptor and that hypoxia significantly upregulated this process. Hypoxia-mediated increases in mast cell adhesion occurred without increased surface expression of integrins, suggesting regulation by inside-out integrin signaling. Hypoxia also mediated an increase in phosphorylation of Akt, and PI3’kinase inhibitors abolished hypoxia-mediated mast cell adhesion. Hypoxia upregulates the function of integrin receptors by PI3’ kinase-dependent signaling. This process might be important for the location of mast cells at inflammatory sites     

Extract of Pleurotus pulmonarius suppresses liver cancer development and progression through inhibition of VEGF-induced PI3K/AKT signaling pathway

Liver cancer or hepatocellular carcinoma is one of the leading causes of cancer-related deaths. Conventional chemotherapies are limited by the development of drug resistance and various side effects. Because of its non-toxicity and potent biopharmacological activity, metabolites derived from mushrooms have received more attention in cancer therapy. Our previous studies have demonstrated the anticancer effects of polysaccharide-protein complexes derived from the Pleurotus mushrooms. The aim of this study was to investigate the underlying molecular mechanism of the anticancer activity of a hot water extract containing a polysaccharide-protein complex isolated from Pleurotus pulmonarius (PP) in liver cancer cells. Our results indicated that exposure of liver cancer cells to PP not only significantly reduced the in vitro cancer cell proliferation and invasion but also enhanced the drug-sensitivity to the chemotherapeutic drug Cisplatin. Both oral administration and intraperitoneal injection of PP significantly inhibited the tumor growth in xenograft BALB/c nude mice. PP triggered a marked suppression of the PI3K/AKT signaling pathway in liver cancer cells in vitro and in vivo, and overexpression of the constitutively active form of AKT, Myr-AKT, abrogated this effect and the inhibited proliferation and invasion by PP. Both western blot and ELISA results showed that PP-treated liver cancer cells had reduced expression and secretion of vascular endothelial growth factor (VEGF). Addition of recombinant human VEGF attenuated the inhibitory effects of PP on PI3K/AKT pathway and the cancer phenotypes. Our results demonstrated that PP suppressed the proliferation, invasion, and drug-resistance of liver cancer cells in vitro and in vivo, mediated by the inhibition of autocrine VEGF-induced PI3K/AKT signaling pathway. This study suggests the potential therapeutic implication of PP in the treatment of human liver cancer.     

Iron-saturated lactoferrin stimulates cell cycle progression through PI3K/Akt pathway

Iron binding lactoferrin (Lf) is involved in the control of cell cycle progression. However, the molecular basis underlying the effects of Lf on cell cycle control, as well as its target genes, remains incompletely understood. In this study, we have demonstrated that a relatively low level of ironsaturated Lf, Lf(Fe³⁺), can stimulate S phase cell cycle entry, and requires Akt activation in MCF-7 cells. Lf(Fe³⁺) immediately induced Akt phosphorylation at Ser473, which subsequently induced the phosphorylation of two G1-checkpoint Cdk inhibitors, p21^Cip/WAF1 and p27^kip1. The Lf(Fe³⁺)-induced phosphorylation of Cdk inhibitors impaired their nuclear import behavior, thereby inducing cell cycle progression. However, the treatment of cells with a PI3K inhibitor, LY294002, almost completely blocked Lf(Fe³⁺)-stimulated cell cycle progression. LY294002 treatment abrogated Lf(Fe³⁺)-induced Akt activation, and prevented the cytoplasmic localization of p27^kip1. Higher levels of p21^Cip/WAF1 were also detected in the cytoplasmic sub-cellular compartment as a measure of cellular response to Lf(Fe³⁺). Consequently, the degree of phosphorylation of retinoblastoma protein was enhanced in response to Lf(Fe³⁺). Therefore, we conclude that Lf(Fe³⁺), as a potential antagonist of Cdk inhibitors, can facilitate the functions of E2F during progression to S phase via the Akt signaling pathway.     

PI3K/Akt信号通路与肺纤维化

肺纤维化(pulmonary fibrosis)是进行性、致命性的疾病。其致病机制不明,治疗效果差。PI3K/Akt信号通路主要与细胞的生长、增殖、分化、凋亡及血管形成等有关。近年来,随着对PI3K/Akt信号通路的深入研究,发现其活化后可激活下游中的一些因子参与肺纤维化,且与其他通路协同作用促进肺纤维化的形成。因此该通路有可能成为治疗肺纤维化的新靶点。将PI3K/Akt信号通路参与肺纤维化形成的研究进展作一综述。     

Rhaponticin suppresses osteosarcoma through the inhibition of PI3K-Akt-mTOR pathway

Osteosarcoma is the frequent pediatric bone cancer where pediatric osteosarcoma incidences are more than 10% within the population. Most of the patients with osteosarcoma fall within the age of 15–30 years. Therefore, in this research, we examined the anticancer effect of Rhaponticin against the human osteosarcoma (MG-63) cells. The cytotoxicity of Rhaponticin on the MC3T3-E1 and MG-63 cells was examined through the MTT assay. The intracellular ROS accumulation, cell nuclear morphological alterations, apoptotic cell death and nuclear damages, and MMP status of Rhaponticin administered MG-63 cells were inspected by fluorescent staining techniques. The cell migration was assessed through scratch assay. The mRNA expressions of PI3K-Akt-mTOR signaling proteins were studied by RT-PCR analysis. Rhaponticin showed potent cytotoxicity, substantially inhibited the MG-63 cell growth, and displayed morphological alterations. However, rhaponticin did not affect the MC3T3-E1 cell viability. Rhaponticin administered MG-63 cells demonstrated augmented intracellular ROS accretion, weakened MMP, increased nuclear damages, and increased apoptosis. Rhaponticin effectively down-regulated the PI3K-Akt-mTOR signaling cascade in the MG-63 cells. These outcomes proved that the Rhaponticin can be a hopeful chemotherapeutic agent in the future to treat human osteosarcoma.     

Silencing of S-phase kinase-associated protein 2 enhances radiosensitivity of esophageal cancer cells through inhibition of PI3K/AKT signaling pathway

We investigated the effect of S-phase kinase-associated protein 2 (SKP2) on radiosensitivity of esophageal cancer (EC) cells. Expression of SKP2, PI3K, AKT, Bcl-2 and Bax were assayed in EC. EC cells were transfected with SKP2-siRNA/IGF-1 to detect expression of SKP2, PI3K, AKT, Bcl-2 and Bax. At last, the radiosensitivity of cells in different doses of X (0, 2, 4, 6, 8 Gy) irradiation and cell apoptosis were also detected. EC cells displayed a higher positive expression rate of SKP2, elevated mRNA and protein expression of SKP2, PI3K, AKT, Bcl-2 and Bax, as well as higher extent of PI3K and AKT phosphorylation. SKP2 silencing downregulated mRNA and protein expression of PI3K, AKT and Bcl-2 but increased p27 protein expression, and inhibited the cell survival rate while promoting cell apoptosis. Taken together, silencing SKP2 can inhibit the PI3K/AKT signaling pathway, thereby increasing the radiosensitivity of EC cells.