Inhibition of fatty acid synthase suppresses osteosarcoma cell invasion and migration via downregulation of the PI3K/Akt signaling pathway in vitro

Regulation of fatty acid synthase on tumor and progress in the development of related therapies

ABSTRACT

Fatty acid synthase (FASN) is an essential molecule in lipid metabolic pathways, which are crucial for cancer-related studies. Recent studies have focused on a comprehensive understanding of the novel and important regulatory effects of FASN on malignant biological behavior and immune-cell infiltration, which are closely related to tumor occurrence and development, immune escape, and immune response. FASN-targeting antitumor treatment strategies are being developed. Therefore, in this review, we focused on the effects of FASN on tumor and immune-cell infiltration and reviewed the progress of related anti-tumor therapy development.

Functional Role of RBP in Osteosarcoma: Regulatory Mechanism and Clinical Therapy

Malignant bone neoplasms can be represented by osteosarcoma (OS), which accounts for 36% of all sarcomas. To reduce tumor malignancy, extensive efforts have been devoted to find an ideal target from numerous candidates, among which RNA-binding proteins (RBPs) have shown their unparalleled competitiveness. With the special structure of RNA-binding domains, RBPs have the potential to establish relationships with RNAs or small molecules and are considered regulators of different sections of RNA processes, including splicing, transport, translation, and degradation of RNAs. RBPs have considerable significant roles in various cancers, and experiments revealed that there was a strong association of RBPs with tumorigenesis and tumor cell progression. Regarding OS, RBPs are a new orientation, but achievements in hand are noteworthy. Higher or lower expression of RBPs was first found in tumor cells compared to normal tissue. By binding to different molecules, RBPs are capable of influencing tumor cell phenotypes through different signaling pathways or other axes, and researches on medical treatment have been largely inspired. Exploring the prognostic and therapeutic values of RBPs in OS is a hotspot where diverse avenues on regulating RBPs have achieved dramatical effects. In this review, we briefly summarize the contribution of RBPs and their binding molecules to OS oncogenicity and generally introduce distinctive RBPs as samples. Moreover, we focus on the attempts to differentiate RBP's opposite functions in predicting prognosis and collect possible strategies for treatment. Our review provides forwards insight into improving the understanding of OS and suggests RBPs as potential biomarkers for therapies.

Non-coding RNAs in metabolic reprogramming of bone and soft tissue sarcoma: Fundamental mechanism and clinical implication

Sarcomas, comprising approximately 1% of human malignancies, show a poor response to treatment and easy recurrence. Metabolic reprogramming play an important role in tumor development in sarcomas. Accumulating evidence shows that non-coding RNAs (ncRNAs) participate in regulating the cellular metabolism of sarcomas, which improves the understanding of the development of therapy-resistant tumors. This review addresses the regulatory roles of metabolism-related ncRNAs and their implications for sarcoma initiation and progression. Dysregulation of metabolism-related ncRNAs is common in sarcomas and is associated with poor survival. Emerging studies show that abnormal expression of metabolism-related ncRNAs affects cellular metabolism, including glucose, lipid, and mitochondrial metabolism, and leads to the development of aggressive sarcomas. This review summarizes recent advances in the roles of dysregulated metabolism-related ncRNAs in sarcoma development and stemness and describes their potential to serve as biological biomarkers for disease diagnosis and prognosis prediction, as well as therapeutic targets for treating refractory sarcomas.

Tanshinone IIA Inhibits Osteosarcoma Growth through a Src Kinase-Dependent Mechanism

Introduction

Osteosarcoma is a malignant tumor associated with high mortality rates due to the toxic side effects of current therapeutic methods. Tanshinone IIA can inhibit cell proliferation and promote apoptosis in vitro, but the exact mechanism is still unknown. The aims of this study are to explore the antiosteosarcoma effect of tanshinone IIA via Src kinase and demonstrate the mechanism of this effect.

Materials and Methods

Osteosarcoma MG-63 and U2-OS cell lines were stable transfections with Src-shRNA. Then, the antiosteosarcoma effect of tanshinone IIA was tested in vitro. The protein expression levels of Src, p-Src, p-ERK1/2, and p-AKt were detected by Western blot and RT-PCR. CCK-8 assay and BrdU immunofluorescence assay were used to detect cell proliferation. Transwell assay, cell scratch assay, and flow cytometry were used to detect cell invasion, migration, and cell cycle. Tumor-bearing nude mice with osteosarcoma were constructed. The effect of tanshinone IIA was detected by tumor HE staining, tumor inhibition rate, incidence of lung metastasis, and X-ray.

Results

The oncogene role of Src kinase in osteosarcoma is reflected in promoting cell proliferation, invasion, and migration and in inhibiting apoptosis. However, Src has different effects on cell proliferation, apoptosis, and cell cycle regulation among cell lines. At a cellular level, the antiosteosarcoma effect of tanshinone IIA is mediated by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways. At the animal level, tanshinone IIA played a role in resisting osteosarcoma formation by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways.

Conclusion

Tanshinone IIA plays an antiosteosarcoma role in vitro and in vivo and inhibits the progression of osteosarcoma mediated by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways.

iTRAQ-based proteomic analysis of the molecular mechanisms and downstream effects of fatty acid synthase in osteosarcoma cells

Background

Fatty acid synthase (FASN) is a lipogenic enzyme that participates in tumor progression. We previously showed that FASN is dysregulated in OS malignancy, but the molecular mechanism(s) of these effects remained unclear.

Methods

We examined differentially expressed proteins (DEPs) in FASN‐silenced osteosarcoma 143B cells and their parental cells by isobaric tags for relative and absolute quantitation (iTRAQ). Differentially expressed proteins were classified using GO and KEGG analysis. The association between FASN and heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1) was confirmed using qPCR, Western blot, and immunohistochemistry. The function of HNRNPA1 in osteosarcoma was determined using CCK‐8, colony formation, wound healing, transwell migration, and invasion assays.

Results

Among the 4971 identified proteins, 567 DEPs (325 upregulated and 242 downregulated) were identified. The top 10 upregulated proteins comprised HIST1H2AB, INA, INTS5, MTCH2, EIF1, MAPK1IP1L, PXK, RPS27, PM20D2, and ZNF800, while the top 10 downregulated proteins comprised NDRG1, CNTLN, STON2, GDF7, HECTD3, HBB, TPM1, PPP4R4, PTTG1IP, and PLCB3. Bioinformatic analysis indicated that the DEPs were related to cellular processes, metabolic processes, biological regulation, binding, and catalytic activity. HNRNPA1 was dysregulated in FASN‐silenced 143B and HOS cells. qPCR, Western blot, and immunohistochemistry showed that FASN expression positively correlates with HNRNPA1 expression. Further studies indicated that HNRNPA1 correlates with OS diagnosis and prognosis. And HNRNPA1 silence inhibits the proliferation, migration, and invasion in OS cells.

Conclusion

HNRNPA1 acts as targets downstream of FASN and potential biomarker and oncogene in OS.

Identification of the fatty acid synthase interaction network via iTRAQ-based proteomics indicates the potential molecular mechanisms of liver cancer metastasis

Background

Fatty acid synthase (FASN) is highly expressed in various types of cancer and has an important role in carcinogenesis and metastasis. To clarify the mechanisms of FASN in liver cancer invasion and metastasis, the FASN protein interaction network in liver cancer was identified by targeted proteomic analysis.

Methods

Wound healing and Transwell assays was performed to observe the effect of FASN during migration and invasion in liver cancer. Isobaric tags for relative and absolute quantitation (iTRAQ)-based mass spectrometry were used to identify proteins interacting with FASN in HepG2 cells. Differential expressed proteins were validated by co-immunoprecipitation, western blot analyses and confocal microscopy. Western blot and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were performed to demonstrate the mechanism of FASN regulating metastasis.

Results

FASN knockdown inhibited migration and invasion of HepG2 and SMMC7721 cells. A total of, 79 proteins interacting with FASN were identified. Additionally, gene ontology term enrichment analysis indicated that the majority of biological regulation and cellular processes that the FASN-interacting proteins were associated with. Co-precipitation and co-localization of FASN with fascin actin-bundling protein 1 (FSCN1), signal-induced proliferation-associated 1 (SIPA1), spectrin β, non-erythrocytic 1 (SPTBN1) and CD59 were evaluated. Knockdown of FASN in liver cancer reduced the expression of FSCN1, SIPA1, SPTBN1 and CD59. Furthermore, inhibition of FASN, FSCN1 or SPTBN1 expression in liver cancer resulted in alterations of epithelial–mesenchymal transition (EMT)-associated markers E-cadherin, N-cadherin, vimentin and transcription factors, Snail and Twist, at the mRNA level, and changes in matrix metallopeptidase (MMP)-2 and MMP-9 protein expression.

Conclusion

The results suggested that the FASN-interacting protein network produced by iTRAQ-based proteomic analyses may be involved in regulating invasion and metastasis in liver cancer by influencing EMT and the function of MMPs.

Tizanidine hydrochloride exhibits a cytotoxic effect on osteosarcoma cells through the PI3K/AKT signaling pathway

Objectives

α2-adrenergic receptors are reportedly involved in cancer cell proliferation, invasion, and apoptosis through regulation of diverse molecules, which implies that it contributes to tumor progression. However, the functional significance of α2-adrenergic receptors in osteosarcoma (OS) is unclear. Tizanidine hydrochloride (THC), an α2-adrenergic receptor agonist, is often used to alleviate symptoms of spasticity. This study investigated the functional implications of THC treatment on human OS cells and the underlying mechanisms of resulting changes.

Methods

The proliferation of U2 OS cells was assessed by Cell Counting Kit-8; the migration and invasion capacities of U2 OS cells were then analyzed by transwell assay. Moreover, apoptosis in U2 OS cells was evaluated by flow cytometry and western blot analyses. Additionally, expression levels of key proteins in the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway were measured.

Results

THC inhibited the proliferation, migration, and invasion of U2 OS cells, but promoted apoptosis within these cells. Expression levels of p-AKT, p-mTOR, and p-P70S6K were reduced by exposure to THC, suggesting involvement of PI3K/AKT signaling in THC-induced cytotoxicity within OS cells.

Conclusions

THC may play a novel role in OS cell cytotoxicity, and these findings suggest a potent therapeutic strategy for OS treatment.

Anoikis resistant mediated by FASN promoted growth and metastasis of osteosarcoma

The pulmonary metastasis of osteosarcoma (OS) occurs commonly, which resulted from anoikis resistant (AR) of tumor cells as reported by previous studies, but the exact roles of AR in osteosarcoma were not fully studied. Our previous investigations showed fatty acid synthase (FASN) was relating to clinical features of patients with OS. In this study, we aim to explore the functions of FASN in the AR OS cells in vitro and in vivo and study the downstream effectors of FASN. In the present study, we used our established cell model to study the AR. We revealed that AR promoted cell proliferation and migration as determined by colony formation assay and transwell assay. In addition, AR assisted tumor growth in vivo. In the AR cells, the expression of FASN was higher. Thus, we constructed lentiviruses to silence or overexpress FASN in four cell lines to study functions of FASN. Silence of FASN reduced cell colonies and migration while overexpression of FASN increased colonies and migration in suspended cells. Loss of functions of FASN induced cell apoptosis in suspended OS cells while gain of function of FASN suppressed apoptosis as determined by flow cytometry. We found the levels of p-ERK1/2 and Bcl-xL declined when FASN was silenced while they increased when FASN was overexpressed. In addition, results showed that the levels of FASN and its potential related molecules (p-ERK1/2 and Bcl-xL) increased in 143B-AR and MG-63-AR cells. In vivo study showed that inhibition of FASN decreased pulmonary metastasis of OS. In conclusion, we showed that anoikis resistant and FASN as two interactional factors facilitated the progress of osteosarcoma.

De Novo Fatty Acid Synthesis-Driven Sphingolipid Metabolism Promotes Metastatic Potential of Colorectal Cancer

Metastasis is the most common cause of death in colorectal cancer patients. Fatty acid synthase (FASN) and sphingosine kinase-1 and -2 (SPHK1 and 2) are overexpressed in many cancers, including colorectal cancer. However, the contribution of FASN-mediated upregulation of sphingolipid metabolism to colorectal cancer metastasis and the potential of these pathways as targets for therapeutic intervention remain unknown. This study determined that sphingosine kinases (SPHK) are overexpressed in colorectal cancer as compared with normal mucosa. FASN expression significantly correlated with SPHK2 expression in data sets from The Cancer Genome Atlas (TCGA) and a colorectal cancer tumor microarray. FASN, SPHK1, and SPHK2 colocalized within invadopodia of primary colorectal cancer cells. Moreover, FASN inhibition decreased SPHK2 expression and the levels of dihydrosphingosine 1-phosphate (DH-S1P) and sphingosine 1-phosphate (S1P) in colorectal cancer cells and tumor tissues. Inhibition of FASN using TVB-3664 and sphingolipid metabolism using FTY-720 significantly inhibited the ability of primary colorectal cancer cells to proliferate, migrate, form focal adhesions, and degrade gelatin. Inhibition of the FASN/SPHK/S1P axis was accompanied by decreased activation of p-MET, p-FAK, and p-PAX. S1P treatment rescued FASN-mediated inhibition of these proteins, suggesting that FASN promotes metastatic properties of colorectal cancer cells, in part, through an increased sphingolipid metabolism. These data demonstrate that upregulation of the FASN/SPHK/S1P axis promotes colorectal cancer progression by enhancing proliferation, adhesion, and migration. IMPLICATIONS: This study provides a strong rationale for further investigation of the interconnection of de novo lipogenesis and sphingolipid metabolism that could potentially lead to the identification of new therapeutic targets and strategies for colorectal cancer.

Let-7a inhibits osteosarcoma cell growth and lung metastasis by targeting Aurora-B

Purpose

Accumulating studies showed that the expression of microRNAs (miRNAs) was dysregulated in osteosarcoma (OS). In this study, we sought to investigate the effect of let-7a on OS progression and its potential molecular mechanism.

Patients and methods

Quantitative real-time PCR (qRT-PCR) was performed to evaluate the expression level of let-7a and Aurora-B (AURKB) in OS tissues and cells. The OS cells were treated with let-7a mimic, let7a inhibitor, negative mimic and Lv-AURKB combined with let-7a. The ability of cell proliferation, migration and invasion was measured using Cell Counting Kit-8 (CCK-8) and wound-healing and transwell invasion assays. The protein of AURKB, NF-κβp65, MMP2 and MMP9 was measured by Western blot analysis. Xenograft model was performed to investigate the effects of let-7a on tumor growth and metastasis. The lung metastasis was measured by counting the metastatic node using H&E staining.

Results

Let-7a expression was significantly underexpressed in OS cell lines and tissues compared with human osteoblast cell lines, hFOB1.19, and adjacent normal bone tissues. Exogenous let-7a inhibited the viability, migratory and invasive ability of OS cells in vitro. In addition, the overexpression of AURKB in OS cells could partly rescue let-7a-mediated tumor inhibition. Also, the overexpression of let-7a inhibited OS cell growth and lung metastasis in vivo. Furthermore, the results showed that let-7a could decrease the expression of NF-κβp65, MMP2 and MMP9 proteins by targeting AURKB in OS cells.

Conclusion

Let-7a inhibits the malignant phenotype of OS cells by targeting AURKB at least partially. Targeting let-7a and AURKB/NF-κβ may be a novel therapeutic strategy for the treatment of OS.

Ginsenoside Rg1 Promotes the Migration of Olfactory Ensheathing Cells via the PI3K/Akt Pathway to Repair Rat Spinal Cord Injury

The aim of this study was to determine the effects of ginsenoside Rg1 on the migration of olfactory ensheathing cells (OECs) in vitro, and its influence on the therapeutic efficacy of OECs transplanted in vivo for the treatment of spinal cord injury (SCI). Primary cultured and purified OECs (prepared from rats) were treated with ginsenoside Rg1. The wound healing test indicated that ginsenoside Rg1 promoted the migration of OECs. Real-time RT-PCR demonstrated that ginsenoside Rg1 upregulated the expression of migration-related factors of OECs, including matrix metalloproteinases-2 (MMP-2), MMP-9, and neural cell adhesion molecule 1 (NCAM1). Moreover, Western blot analysis indicated that ginsenoside Rg1 significantly promoted the migration of OECs via the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. An SCI rat model was induced in vivo using a revised Allen's method. The Basso, Beattie, and Bresnahan (BBB) scores and histological analysis demonstrated that OECs, which were treated with ginsenoside Rg1, exhibited significant improvement in SCI compared with both the control group and the OEC group. Thus, ginsenoside Rg1 may represent a novel treatment target for SCI.

The stromal cell-derived factor 1/C-X-C chemokine receptor type 4 axis is important in neutrophil migration caused by cardiopulmonary bypass in children

OBJECTIVES

Acute lung injury caused by cardiopulmonary bypass (CPB) is characterized by massive neutrophil migration to the lungs. Neutrophil migration may be closely related to stromal cell-derived factor 1 (SDF-1)/C-X-C chemokine receptor Type 4 (CXCR4) axis activation, which plays an essential role in modulating the trafficking of neutrophils. We investigated the changes in the expression of SDF-1/CXCR4 axis components before and after CPB as well as the role of the axis in driving the migration of neutrophils in patients with congenital heart disease.

METHODS

Fifteen children undergoing elective open-heart surgery under CPB (CPB group) and 15 children undergoing minimally invasive ultrasound-guided closure of a ventricular septal defect (control group) were enrolled in this non-randomized clinical trial. Neutrophil CXCR4 expression was evaluated using quantitative reverse transcription polymerase chain reaction and flow cytometry. An enzyme-linked immunosorbent assay was used to measure plasma SDF-1 levels. The migration characteristics of neutrophils under 8 different combinations designated A-H were assayed with and without a specific CXCR4 antagonist, AMD3100, to evaluate the functional significance of the SDF-1/CXCR4 axis.

RESULTS

Both CXCR4 gene and protein expressions were elevated in the CPB group compared with the control group after CPB (0.81 ± 0.55 vs 1.76 ± 1.32; P < 0.05, 1.96 ± 0.86 vs 2.65 ± 0.79; P < 0.05), and plasma SDF-1 levels were also increased in the former compared with the latter (197.84 ± 19.96 pg/ml vs 539.13 ± 99.83 pg/ml; P < 0.05). The in vitro experiments showed that plasma isolated post-CPB exhibited the strongest chemotactic effect on neutrophils. The CPB group showed a higher chemotaxis index, which serves as a marker for the effects of plasma on neutrophils, than that for the control group after CPB (37.38 ± 9.39 vs 13.61 ± 2.59; P < 0.05). In addition, the CXCR4 antagonist AMD3100 significantly abrogated the increase in neutrophil migration in the CPB group.

CONCLUSIONS

Exposure to CPB, which activates the SDF-1/CXCR4 axis, using an antagonist to prevent neutrophil trafficking, may be a beneficial therapy for the related complications.

Downregulation of HADH promotes gastric cancer progression via Akt signaling pathway

HADH is a key enzyme in fatty acid oxidation. The aim of this study was to identify the role of HADH in gastric cancer. We analyzed the expression of HADH in 102 pairs of gastric cancer samples. Western blot analysis revealed that HADH was decreased in stage I/II gastric cancer samples compared to matched adjacent normal gastric tissue, and its expression was further decreased in stage III/IV samples. Importantly, the reduced expression of HADH was associated with increased expression of p-Akt and reduced expression of PTEN in the gastric carcinoma tumor samples. To determine the significance of HADH downregulation in gastric cancer progression, we tested the impact of HADH knockdown or overexpression on the migration and invasion of the gastric cancer cells using a transwell assay. Knockdown of HADH significantly promoted gastric cancer cell migration and invasion, which was associated with increased expression of p-Akt. The PI3K inhibitor LY294002 inhibited HADH shRNA induced migration/invasion, and abolished the upregulation of p-Akt. By contrast, HADH overexpression inhibited the migration and invasion of MKN45 cells. Herein, for the first time, we demonstrate that downregulation of HADH promotes gastric cancer progression via activation of Akt signaling pathway.

Microwave-Assisted Synthesis of Imidazo[4,5-f][1,10]phenanthroline Derivatives as Apoptosis Inducers in Chemotherapy by Stabilizing Bcl-2 G-quadruplex DNA

Herein, a series of imidazo[4,5-f][1,10] phenanthroline derivatives RPIP (PIP = imidazo [4,5-f][1,10] phenanthroline, R = NO₂, 1; CF₃, 2; Cl, 3; OH, 4) have been synthesized in yields of 82.3–94.7% at 100 °C under the irradiation of microwave. MTT assay has been utilized to evaluate the inhibitory activity (IC₅₀) of these compounds against the growth of various tumor cells, and the results revealed that these compounds, especially 1, exhibited excellent inhibitory activity against the growth of A549 cells with IC₅₀ of 15.03 μM. Moreover, it’s also confirmed that 1 can penetrate into the membrane of tumor cells and distribute in mitochondria when observed under microscopy, resulting apoptosis of tumor cells. The further studies showed that 1 can bind to bcl-2 G-quadruplex DNA, which demonstrated by the increase of melting point of bcl-2 G4 DNA in the presence of 1, as well as electronic titration and emission spectra. In a word, this kind of compound may develop as a potential apoptosis inducer in cancer chemotherapy via binding and stabilizing to the bcl-2 G-quadruplex DNA.

Blocking fatty acid synthase inhibits tumor progression of human osteosarcoma by regulating the human epidermal growth factor receptor 2/phosphoinositide 3-kinase/protein kinase B signaling pathway in xenograft models

Previous studies have demonstrated that fatty acid synthase (FASN) is overexpressed in osteosarcoma (OS) cells and tissues and, therefore, knockdown of FASN may inhibit OS cell proliferation, migration and invasion via regulation of the human epidermal growth factor receptor 2 (HER2)/phosphoinositide 3-kinase (PI3K)/protein kinase B(Akt) signaling pathway in vitro. However, the tumor microenvironment has a crucial role in the determination of tumor malignant phenotype. The aim of the present study was to investigate the effect of knockdown of FASN on OS progression and the potential molecular mechanism in nude mice with orthotopic tumor implants in vivo. Results demonstrated that the knockdown of FASN markedly suppressed the growth and metastasis of OS, at least partially, by blocking the HER2/PI3K/Akt signal pathway in mice with intratibial 143B OS xenografts. These results suggest that the FASN/HER2/PI3K/Akt signaling pathway may be a potential therapeutic target for OS management.

Transcription factor NF‑YA promotes a malignant phenotype by upregulating fatty acid synthase expression

Recent studies have revealed that increased expression of the alpha subunit of nuclear transcription factor Y (NF‑YA) is associated with the malignant phenotype of various tumors. However, whether elevated expression of NF‑YA promotes a malignant phenotype in osteosarcoma (OS), and the molecular mechanisms underlying this predicted effect is currently unknown. In the present study, small hairpin RNA (shRNA)‑mediated knockdown of endogenous NF‑YA significantly inhibited the migration and invasion capabilities of OS cells in vitro, whereas ectopic expression of NF‑YA increased the migration and invasion capabilities of these cells. In addition, the induction of upregulated NF‑YA expression on the malignant phenotype of OS cells was attenuated by silencing fatty acid synthase (FASN) expression. Furthermore, the expression level of FASN was increased by upregulating NF‑YA, while decreased FASN expression was observed following NF‑YA silencing in OS cells. The results of the present study suggest that NF‑YA may promote a malignant phenotype in OS cells, in part, by activating the FASN signaling pathway, which may represent a promising target for the management of OS.

Inactivation of fatty acid synthase impairs hepatocarcinogenesis driven by AKT in mice and humans

BACKGROUND & AIMS

Cumulating evidence underlines the crucial role of aberrant lipogenesis in human hepatocellular carcinoma (HCC). Here, we investigated the oncogenic potential of fatty acid synthase (FASN), the master regulator of de novo lipogenesis, in the mouse liver.

METHODS

FASN was overexpressed in the mouse liver, either alone or in combination with activated N-Ras, c-Met, or SCD1, via hydrodynamic injection. Activated AKT was overexpressed via hydrodynamic injection in livers of conditional FASN or Rictor knockout mice. FASN was suppressed in human hepatoma cell lines via specific small interfering RNA.

RESULTS

Overexpression of FASN, either alone or in combination with other genes associated with hepatocarcinogenesis, did not induce histological liver alterations. In contrast, genetic ablation of FASN resulted in the complete inhibition of hepatocarcinogenesis in AKT-overexpressing mice. In human HCC cell lines, FASN inactivation led to a decline in cell proliferation and a rise in apoptosis, which were paralleled by a decrease in the levels of phosphorylated/activated AKT, an event controlled by the mammalian target of rapamycin complex 2 (mTORC2). Downregulation of AKT phosphorylation/activation following FASN inactivation was associated with a strong inhibition of rapamycin-insensitive companion of mTOR (Rictor), the major component of mTORC2, at post-transcriptional level. Finally, genetic ablation of Rictor impaired AKT-driven hepatocarcinogenesis in mice.

CONCLUSIONS

FASN is not oncogenic per se in the mouse liver, but is necessary for AKT-driven hepatocarcinogenesis. Pharmacological blockade of FASN might be highly useful in the treatment of human HCC characterized by activation of the AKT pathway.

A New Paradigm to Mitigate Osteosarcoma by Regulation of MicroRNAs and Suppression of the NF-κB Signaling Cascade

Osteosarcoma (OS) is one of the most common malignant primary bone tumors and NF-κB appears to play a causative role, but the mechanisms are poorly understood. OS is one of the pleomorphic, highly metastasized and invasive neoplasm which is capable to generate osteoid, osteoclast and osteoblast matrix. Its high incidence has been reported in adolescent and children. Cell signal cascade is the pivotal functional mechanism acquired during the differentiation, proliferation, growth and survival of the cells in neoplasm including OS. The major limitation to the success of chemotherapy in OS is the development of multidrug resistance (MDR). Answers to all such queries might come from the knock-in experiments in which the combined approach of miRNAs with NF-κB pathway is put into use. Abnormal miRNAs can modulate several epigenetical switching as a hallmark of number of diseases via different cell signaling. Studies on miRNAs have opened up the new avenues for both the diagnosis and treatment of cancers including OS. Collectively, through the present study an attempt has been made to establish a new systematic approach for the investigation of microRNAs, biophysiological factors and their target pairs with NF-κB to ameliorate oncogenesis with the “bridge between miRNAs and NF-κB”. The application of NF-κB inhibitors in combination with miRNAs is expected to result in a more efficient killing of the cancer stem cells and a slower or less likely recurrence of cancer.

PI3K/Akt signaling in osteosarcoma

Osteosarcoma (OS) is the most common nonhematologic bone malignancy in children and adolescents. Despite the advances of adjuvant chemotherapy and significant improvement of survival, the prognosis remains generally poor. As such, the search for more effective anti-OS agents is urgent. The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is thought to be one of the most important oncogenic pathways in human cancer. An increasing body of evidence has shown that this pathway is frequently hyperactivated in OS and contributes to disease initiation and development, including tumorigenesis, proliferation, invasion, cell cycle progression, inhibition of apoptosis, angiogenesis, metastasis and chemoresistance. Inhibition of this pathway through small molecule compounds represents an attractive potential therapeutic approach for OS. The aim of this review is to summarize the roles of the PI3K/Akt pathway in the development and progression of OS, and to highlight the therapeutic potential of targeting this signaling pathway. Knowledge obtained from the application of these compounds will help in further understanding the pathogenesis of OS and designing subsequent treatment strategies.

A New Paradigm to Mitigate Osteosarcoma by Regulation of MicroRNAs and Suppression of the NF-κB Signaling Cascade

Osteosarcoma (OS) is one of the most common malignant primary bone tumors and NF-κB appears to play a causative role, but the mechanisms are poorly understood. OS is one of the pleomorphic, highly metastasized and invasive neoplasm which is capable to generate osteoid, osteoclast and osteoblast matrix. Its high incidence has been reported in adolescent and childevrepen. Cell signal cascade is the pivotal functional mechanism acquired during the differentiation, proliferation, growth and survival of the cells in neoplasm including OS. The major limitation to the success of chemotherapy in OS is the development of multidevrepug resistance (Mdevrep). Answers to all such queries might come from the knock-in experiments in which the combined approach of miRNAs with NF-κB pathway is put into use. Abnormal miRNAs can modulate several epigenetical switching as a hallmark of number of diseases via different cell signaling. Studies on miRNAs have opened up the new avenues for both the diagnosis and treatment of cancers including OS. Collectively, through the present study an attempt has been made to establish a new systematic approach for the investigation of microRNAs, biophysiological factors and their target pairs with NF-κB to ameliorate oncogenesis with the "bridge between miRNAs and NF-κB". The application of NF-κB inhibitors in combination with miRNAs is expected to result in a more efficient killing of the cancer stem cells and a slower or less likely recurrence of cancer.

Ribosomal protein S3 regulates GLI2-mediated osteosarcoma invasion

It has been reported that GLI2 promotes proliferation, migration, and invasion of mesenchymal stem cell and osteosarcoma cells. To examine the molecular mechanisms of GLI2-mediated osteosarcoma metastasis, we performed a microarray analysis. The gene encoding ribosomal protein S3 (RPS3) was identified as a target of GLI2. Real-time PCR revealed that RPS3 was upregulated in osteosarcoma cell lines compared with normal osteoblast cells. Knockdown of GLI2 decreased RPS3 expression, whereas forced expression of a constitutively active form of GLI2 upregulated the expression of RPS3. RPS3 knockdown by siRNA decreased the migration and invasion of osteosarcoma cells. Although forced expression of constitutively active GLI2 increased the migration of human mesenchymal stem cells, knockdown of RPS3 reduced the up-regulated migration. In contrast, forced expression of RPS3 increased migration and invasion of osteosarcoma cells. Moreover, reduction of migration by GLI2 knockdown was rescued by forced expression of RPS3. Immunohistochemical analysis showed that RPS3 expression was increased in primary osteosarcoma lesions with lung metastases compared with those without. These findings indicate that GLI2-RPS3 signaling may be a marker of invasive osteosarcoma and a therapeutic target for patients with osteosarcoma.

LY294002 inhibits the malignant phenotype of osteosarcoma cells by modulating the phosphatidylinositol 3‑kinase/Akt/fatty acid synthase signaling pathway in vitro

Increasing evidence suggests that fatty acid synthase (FASN) is crucial in the carcinogenesis of various types of tumor. In addition, the phosphatidylinositol 3‑kinase (PI3K)/Akt signaling pathway, which is closely associated with cellular metabolism, affects cancer biology. However, whether the malignant phenotype of osteosarcoma (OS) cells is regulated by the PI3K/Akt/FASN signaling pathway and how the PI3K family specific inhibitor, 2‑(4‑morpholinyl)‑8‑phenyl‑chromone (LY294002) affects the malignant phenotype of OS cells remains to be elucidated. In the present study, U2‑OS and MG‑63 cells were treated with LY294002 and subsequently western blot analysis was used to examine Akt, p‑Akt and FASN protein expression. Additionally, FASN mRNA was detected by reverse transcription quantitative polymerase chain reaction. MTT and fluorescence‑activated cell sorting assays were used to assess proliferation and apoptosis. Migration and invasion were investigated using wound healing and transwell invasion assays. The results demonstrated that LY294002 suppressed the PI3K/Akt/FASN signaling pathway. However, the malignant phenotypes of OS cells mentioned above were significantly inhibited. The present results indicated that LY294002 inhibits the malignant phenotype of OS cells via modulation of the PI3K/Akt/FASN signaling pathway in vitro and may be a new therapeutic strategy for the management of OS.

Annexin A5 inhibits diffuse large B-cell lymphoma cell invasion and chemoresistance through phosphatidylinositol 3-kinase signaling

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma worldwide. Although patient outcomes have significantly improved to a greater than 40% cure rate by the combinatorial cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) chemotherapy, which is widely used, resistance to the CHOP regimen continues to pose a problem in managing or curing DLBCL. While it promotes the malignancy and chemo-resistance in certain types of cancer, Annexin A5 is negatively correlated with those in other cancers, including DLBCL. In the present study, we explored the effects of Annexin A5 on DLBCL cell invasion and chemoresistance to CHOP. Stable overexpression and knockdown of Annexin A5 were performed in Toledo and Pfeiffer human DLBCL cell lines. Overexpression of Annexin A5 in both cell lines significantly decreased cell invasion, matrix metalloproteinase-9 (MMP-9) expression/activity, phosphatidylinositol 3-kinase (PI3K) activity/Akt phosphorylation, and cell survival against CHOP-induced apoptosis. On the other hand, knockdown of Annexin A5 markedly increased cell invasion, MMP-9 expression/activity, PI3K activity/Akt phosphorylation, and CHOP-induced apoptosis in the DLBCL cell lines, which was abolished by selective PI3K inhibitor BKM120. In conclusion, our study provides the first in vitro evidence that Annexin A5 inhibits DLBCL cell invasion, MMP-9 expression/activity, and chemoresistance to CHOP through a PI3K-dependent mechanism; it provides new insight not only into the biological function of Annexin A5, but also into the molecular mechanisms underlying DLBCL progression and chemoresistance.

Annexin A5 promotes invasion and chemoresistance to temozolomide in glioblastoma multiforme cells

Glioblastoma multiforme (GBM) is the prevalent and most fatal brain tumor in adults. Invasion and a high rate of recurrence largely contribute to the poor prognosis of GBM. The current standard therapy for GBM includes surgery with maximum feasible resection, radiotherapy, and treatment with chemotherapeutic agent temozolomide. Annexin A5 reportedly promotes progression and chemoresistance in a variety of cancers. In the present study, we explored the effects of annexin A5 on GBM cell invasion and chemoresistance to temozolomide. Stable overexpression and knockdown of annexin A5 were performed in both U-87 MG and U-118 MG human GBM cell lines. Overexpression of annexin A5 in both cell lines significantly increased cell invasion, matrix metalloproteinase-2 (MMP-2) expression/activity, Akt phosphorylation at serine 473, and the half maximal inhibitory concentration (IC50) values of temozolomide and markedly decreased temozolomide-induced apoptosis, all of which were abolished by selective PI3K inhibitor BKM120. On the other hand, knockdown of annexin A5 markedly decreased cell invasion, MMP-2 expression/activity, Akt phosphorylation at serine 473, and the IC50 values of temozolomide and significantly increased temozolomide-induced apoptosis. In conclusion, our study provides the first evidence that annexin A5 promotes GBM cell invasion, MMP-2 expression/activity, and chemoresistance to temozolomide through a PI3K-dependent mechanism. It adds new insights not only into the biological function of annexin A5 but also into the molecular mechanisms underlying GBM progression and chemoresistance.

Protective effect of proanthocyanidins on anoxia-reoxygenation injury of myocardial cells mediated by the PI3K/Akt/GSK-3β pathway and mitochondrial ATP-sensitive potassium channel

The aim of the present study was to examine the protective effect of proanthocyanidins anoxia-reoxygenation injury of myocardial cells and its association with phosphatidylinositol-3-kinase/Akt and glycogen synthase kinase (PI3K/Akt/GSK)-3β and ATP-sensitive potassium channels. Neonatal rat myocardial cells were cultured and an anoxia-reoxygenation model was established following pretreatment with various drugs. The experiment was divided into five groups according to an experimental scheme. An MTT assay was used to examine the cell survival, and reactive oxygen species (ROS) levels and apoptosis were detected by flow cytometry. Myocardial apoptosis was also examined by terminal deoxynucleotidyl transferase dUTP nick end labeling staining and western blot analysis was employed to detect the expression levels of caspase-3, p-Akt and p-glycogen synthase kinase (GSK)-3β. The results revealed that myocardial cells in the anoxia-reoxygenation group (A/R) exhibited reduced survival rates, increased ROS levels and enhanced caspase-3 expression, as compared with the control group (CN; P<0.05). However, the increase in p-Akt and p-GSK-3β expression was not significantly different. In the proanthocyanidin pretreatment group (PC) the myocardial cell survival rate was increased, ROS levels were reduced, caspase-3 expression was decreased and p-Akt and p-GSK-3β expression levels were significantly increased as compared with the A/R group (P<0.05). Blockade of the PIK3/Akt channel by LY294002 eliminated the protective effects of proanthocyanidins and induced a significant decrease in p-Akt protein and p-GSK-3β expression levels as compared with the PC group. The inhibitor of mitochondrial ATP-sensitive potassium (mitoKATP) channels, 5-HD, also significantly suppressed the protective effects of proanthocyanidins, but had no evident impact on p-Akt and p-GSK-3β expression as compared with the PC group. In conclusion, pretreatment with proanthocyanidins had a protective effect on rat myocardial cell anoxia/reoxygenation injury. This effect is associated with the activation of the PI3K/Akt/GSK-3β signaling pathway and the opening of mitoKATP channels, which may have important roles downstream of PI3K.

Endothelin A receptor antagonism enhances inhibitory effects of anti-ganglioside GD2 monoclonal antibody on invasiveness and viability of human osteosarcoma cells

Endothelin-1 (ET-1)/endothelin A receptor (ETAR) signaling is important for osteosarcoma (OS) progression. Monoclonal antibodies (mAbs) targeting ganglioside GD2 reportedly inhibit tumor cell viability independent of the immune system. A recent study suggests that ganglioside GD2 may play an important role in OS progression. In the present study, we for the first time explored the effects of anti-GD2 mAb alone or in combination with ETAR antagonist on OS cell invasiveness and viability. Human OS cell lines Saos-2, MG-63 and SJSA-1 were treated with control IgG (PK136 mAb, 50 µg/mL), anti-GD2 14G2a mAb (50 µg/mL), selective ETAR antagonist BQ123 (5 µM), or 14G2a (50 µg/mL)+BQ123 (5 µM). Cells with knockdown of ETAR (ETAR-shRNA) with or without 14G2a mAb treatment were also tested. Cells treated with selective phosphatidylinositide 3-kinase (PI3K) inhibitor BKM120 (50 µM) were used as a positive control. Our results showed that BQ123, ETAR-shRNA and 14G2a mAb individually decreased cell invasion and viability, matrix metalloproteinase-2 (MMP-2) expression and activity, PI3k activity, and phosphorylation at serine 473 (ser473) of Akt in OS cells. 14G2a mAb in combination with BQ123 or ETAR-shRNA showed significantly stronger inhibitory effects compared with each individual treatment. In all three cell lines tested, 14G2a mAb in combination with BQ123 showed the strongest inhibitory effects. In conclusion, we provide the first in vitro evidence that anti-ganglioside GD2 14G2a mAb effectively inhibits cell invasiveness, MMP-2 expression and activity, and cell viability in human OS cells. ETAR antagonist BQ123 significantly enhances the inhibitory effects of 14G2a mAb, likely mainly through inhibiting the PI3K/Akt pathway. This study adds novel insights into OS treatment, which will serve as a solid basis for future in vivo studies on the effects of combined treatment of OS with anti-ganglioside GD2 mAbs and ETAR antagonists.

Inhibition of fatty acid synthase suppresses U-2 OS cell invasion and migration via downregulating the activity of HER2/PI3K/AKT signaling pathway in vitro

FASN plays an important role in the malignant phenotype of various tumors. Our previous studies show that inhibition FASN could induce apoptosis and inhibit proliferation in human osteosarcoma (OS) cell in vivo and vitro. The aim in this study was to investigate the effect of inhibition FASN on the activity of HER2/PI3K/AKT axis and invasion and migration of OS cell. The expression of FASN, HER2 and p-HER2(Y1248) proteins was detected by immunohistochemistry in OS tissues from 24 patients with pulmonary metastatic disease, and the relationship between FASN and p-HER2 as well as HER2 was investigated. The results showed that there was a positive correlation between FASN and HER2 as well as p-HER2 protein expression. The U-2 OS cells were transfected with either the FASN specific RNAi plasmid or the negative control RNAi plasmid. FASN mRNA was measured by RT-PCR. Western blot assays was performed to examine the protein expression of FASN, HER2, p-HER2(Y1248), PI3K, Akt and p-Akt (Ser473). Migration and invasion of cells were investigated by wound healing and transwell invasion assays. The results showed that the activity of HER2/PI3K/AKT signaling pathway was suppressed by inhibiting FASN. Meanwhile, the U-2OS cells migration and invasion were also impaired by inhibiting the activity of FASN/HER2/PI3K/AKT. Our results indicated that inhibition of FASN suppresses OS cell invasion and migration via down-regulation of the "HER2/PI3K/AKT" axis in vitro. FASN blocker may be a new therapeutic strategy in OS management.