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

Ubiquitination in lipid metabolism reprogramming: implications for pediatric solid tumors

Pediatric solid tumors represent a significant subset of childhood cancers, accounting for approximately 60% of new diagnoses. Despite advancements in therapeutic strategies, survival rates remain markedly disparate between high-income and resource-limited settings, underscoring the urgent need for novel and effective treatments. Lipid metabolic reprogramming is a fundamental hallmark of cancer, driving tumor progression, therapeutic resistance, and immune evasion through enhanced fatty acid uptake, increased de novo lipid synthesis, and activated fatty acid β-oxidation (FAO). Ubiquitination, a dynamic post-translational modification mediated by the ubiquitin-proteasome system (UPS), plays a crucial role in regulating lipid metabolism by modulating the stability and activity of key metabolic enzymes and transporters involved in cholesterol and fatty acid pathways. This review comprehensively examines the complex interplay between ubiquitination and lipid metabolic reprogramming in pediatric solid tumors. It delineates the mechanisms by which ubiquitination influences cholesterol biosynthesis, uptake, efflux, and fatty acid synthesis and oxidation, thereby facilitating tumor growth and survival. Furthermore, the review identifies potential UPS-mediated therapeutic targets and explores the feasibility of integrating ubiquitination-based strategies with existing treatments. By targeting the UPS to disrupt lipid metabolism pathways, novel therapeutic avenues may emerge to enhance treatment efficacy and overcome resistance in pediatric oncology. This synthesis of current knowledge aims to provide a foundation for the development of innovative, precision medicine approaches to improve clinical outcomes for children afflicted with solid tumors.

Hsa_circ_0000073 promotes lipid synthesis of osteosarcoma through hsa-miR-1184/ FADS2 pathway

PURPOSE

Osteosarcoma is one of the leading causes of cancer mortality in children and teenagers. Dysregulation of lipid metabolism has been reported to involve tumor progression. Our previous evidence has revealed that circular RNA hsa_circ_0000073 enhanced the proliferation and metastasis of osteosarcoma cells. However, the effect of hsa_circ_0000073 on the lipid metabolism of osteosarcoma remains unclear. In this paper, we focused on the effect of hsa_circ_0000073 in lipid metabolism and investigated a network among hsa_circ_0000073/ miR-1184 /FADS2 in osteosarcoma, which provides a new idea to treat osteosarcoma.

METHODS

The osteosarcoma and its adjacent tissue samples were collected for further validation. qRT-PCR or western blot was employed to detect the expression of hsa_circ_0000073, miR-1184, and FADS2 in OS cells and tissues. Microarray analysis, mass spectrometry, metabolomics analysis, and bioinformatics analysis were used to explore the potential function and target gene of hsa_circ_0000073. Oil red o, Nile red staining, and Triglyceride content assay were adopted to confirm the effect of hsa_circ_0000073 on the lipid metabolism of OS. Dual-luciferase reporter assays and RNA immunoprecipitation were applied to construct and validate the ceRNA network of hsa_circ_0000073. The xenograft mouse model was taken to verify the effect of hsa_circ_0000073 on lipid metabolism in vivo.

RESULTS

The results confirmed that hsa_circ_0000073 was raised in the tumor tissues more than its adjacent tissue. Moreover, the higher expression of hsa_circ_0000073 was associated with worse survival rates, advanced clinical stage, large tumor size, and metastasis. After hsa_circ_0000073 silence, the gene chip and metabolomics result implied that hsa_circ_0000073 expression is positively correlated with a 91 genes signature and 78 metabolites in MG-63 and Saos-2 cells. The bioinformatics analysis indicated that hsa_circ_0000073 might involve in the biological processes of lipid metabolism. Further loss and gain of function experiments affirmed that hsa_circ_0000073 could impact cell lipid synthesis. Mechanically, hsa_circ_0000073 favored the expression of FADS2 genes by sponging miR-1184. Consistent with these observations, silencing of hsa_circ_0000073 inhibited lipid synthesis in vivo xenograft mouse model.

CONCLUSIONS

Our study revealed that hsa_circ_0000073 contributed to the lipid synthesis of osteosarcoma by decreasing the expression of miR-1184, thereby increasing FADS2, which provides new insights into treating osteosarcoma.

Functional role of MicroRNA/PI3K/AKT axis in osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor that occurs in children and adolescents, and the PI3K/AKT pathway is overactivated in most OS patients. MicroRNAs (miRNAs) are highly conserved endogenous non-protein-coding RNAs that can regulate gene expression by repressing mRNA translation or degrading mRNA. MiRNAs are enriched in the PI3K/AKT pathway, and aberrant PI3K/AKT pathway activation is involved in the development of osteosarcoma. There is increasing evidence that miRNAs can regulate the biological functions of cells by regulating the PI3K/AKT pathway. MiRNA/PI3K/AKT axis can regulate the expression of osteosarcoma-related genes and then regulate cancer progression. MiRNA expression associated with PI3K/AKT pathway is also clearly associated with many clinical features. In addition, PI3K/AKT pathway-associated miRNAs are potential biomarkers for osteosarcoma diagnosis, treatment and prognostic assessment. This article reviews recent research advances on the role and clinical application of PI3K/AKT pathway and miRNA/PI3K/AKT axis in the development of osteosarcoma.

Circ_0018909 knockdown inhibits the development of pancreatic cancer via the miR‐545‐3p/FASN axis and reduces macrophage polarization to M2

Multiple circular RNAs (circRNAs) were proven to regulate the development of pancreatic cancer. However, the action of circ_0018909 in pancreatic cancer was still unclear. The expression of circ_0018909, microRNA-545-3p (miR-545-3p), and fatty acid synthase (FASN) was measured using quantitative reverse-transcriptase PCR (qRT-PCR). Cell growth, cell cycle arrest, apoptotic cells, metastasis, and epithelial to mesenchymal transition (EMT) were determined using EdU assay, flow cytometry, wound-healing assay, transwell invasion, and western blotting, respectively. The expression of the macrophage markers, including CD80, MCP-1, iNOS, and IL-6 (M1 markers), as well as CD206 and CD163 (M2 markers), was analyzed using qRT-PCR. Circ_0018909 knockdown dramatically depressed cell growth, migration, invasion, EMT, and elevated the number of apoptotic cells in pancreatic cancer cells, and repressed tumor growth in mice. Moreover, we proved that the absence of miR-545-3p rescued the action of circ_0018909 downregulation on cell growth, metastasis, apoptosis, and EMT in pancreatic cancer cells. MiR-545-3p bound to FASN and FASN overexpression hindered the impacts of miR-545-3p on the progression of pancreatic cancer. Besides this, our data demonstrated that circ_0018909 induced polarization from M0 macrophages to M2 macrophages. Circ_0018909 knockdown retarded the development of pancreatic cancer by modulating miR-545-3p to regulate FASN expression.

Combined bezafibrate, medroxyprogesterone acetate and valproic acid treatment inhibits osteosarcoma cell growth without adversely affecting normal mesenchymal stem cells

Drug repurposing is a cost-effective means of targeting new therapies for cancer. We have examined the effects of the repurposed drugs, bezafibrate, medroxyprogesterone acetate and valproic acid on human osteosarcoma cells, i.e., SAOS2 and MG63 compared with their normal cell counterparts, i.e. mesenchymal stem/stromal cells (MSCs). Cell growth, viability and migration were measured by biochemical assay and live cell imaging, whilst levels of lipid-synthesising enzymes were measured by immunoblotting cell extracts. These drug treatments inhibited the growth and survival of SAOS2 and MG63 cells most effectively when used in combination (termed V-BAP). In contrast, V-BAP treated MSCs remained viable with only moderately reduced cell proliferation. V-BAP treatment also inhibited migratory cell phenotypes. MG63 and SAOS2 cells expressed much greater levels of fatty acid synthase and stearoyl CoA desaturase 1 than MSCs, but these elevated enzyme levels significantly decreased in the V-BAP treated osteosarcoma cells prior to cell death. Hence, we have identified a repurposed drug combination that selectively inhibits the growth and survival of human osteosarcoma cells in association with altered lipid metabolism without adversely affecting their non-transformed cell counterparts.

Exploring a role for fatty acid synthase in prostate cancer cell migration

Fatty acid synthase (FASN) is commonly overexpressed in prostate cancer and associated with tumour progression. FASN is responsible for de novo synthesis of the fatty acid palmitate; the building block for protein palmitoylation. A functional role for FASN in regulating cell proliferation is widely accepted. We recently reported that FASN activity can also mediate prostate cancer HGF-mediated cell motility. Moreover, we found that modulation of FASN expression specifically impacts on the palmitoylation of RhoU. Findings we will describe here. We now report that loss of FASN expression also impairs HGF-mediated cell dissociation responses. Taken together our results provide compelling evidence that FASN activity directly promotes cell migration and supports FASN as a potential therapeutic target in metastatic prostate cancer.

Fatty Acid Synthase: An Emerging Target in Cancer

In recent years, lipid metabolism has garnered significant attention as it provides the necessary building blocks required to sustain tumor growth and serves as an alternative fuel source for ATP generation. Fatty acid synthase (FASN) functions as a central regulator of lipid metabolism and plays a critical role in the growth and survival of tumors with lipogenic phenotypes. Accumulating evidence has shown that it is capable of rewiring tumor cells for greater energy flexibility to attain their high energy requirements. This multi-enzyme protein is capable of modulating the function of subcellular organelles for optimal function under different conditions. Apart from lipid metabolism, FASN has functional roles in other cellular processes such as glycolysis and amino acid metabolism. These pivotal roles of FASN in lipid metabolism make it an attractive target in the clinic with several new inhibitors currently being tested in early clinical trials. This article aims to present the current evidence on the emergence of FASN as a target in human malignancies.

Trastuzumab-modified DM1-loaded nanoparticles for HER2+ breast cancer treatment: an in vitro and in vivo study

BACKGROUND

Emtansine (DM1) is a highly potent anti-microtubule agent that has shown promising results for breast cancer treatment, but side effects limit its widespread clinical use. In this research, a new nano-drug was developed to integrate DM1 agent with antibody targeting.

METHODS

A system of novel nanoparticles (NPs) DM1-NPs-trastuzumab (DM1-NPs-Tmab) of DM1 combined with (anti-HER2 antibody, Herceptin®, Trastuzumab) was developed for HER2⁺ breast cancer treatment, and its physical characterization and antitumor biological activity were investigated.

RESULTS

DM1-NPs-Tmab-targeted HER2⁺ breast cancer cells specifically were developed. Compared with naked DM1 and Herceptin, DM1-NPs-Tmab showed greater toxicity on HER2⁺ cancer cells and blocked the HER2-PI3K/Akt cell activation pathway. DM1-NPs-Tmab inhibited tumor growth by 88% and had less toxic effects in vivo than non-targeting DM1 when administered to MDA-MB-453 xenograft bearing mice.

CONCLUSION

DM1-NPs-Tmab shows superior anti-tumor efficacy than free Herceptin or DM1. DM1-NPs-Tmab is a potential promising formulation for targeting biotherapy of HER2⁺ tumors.

An Essential Role for the Tumor-Suppressor Merlin in Regulating Fatty Acid Synthesis

Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder characterized by the development of multiple tumors in the central nervous system, most notably schwannomas, and meningiomas. Mutational inactivation of the NF2 gene encoding the protein Merlin is found in most sporadic and inherited schwannomas, but the molecular mechanisms underlying neoplastic changes in schwannoma cells remain unclear. We report here that Nf2-deficient cells display elevated expression levels of key enzymes involved in lipogenesis and that this upregulation is caused by increased activity of Torc1. Inhibition or knockdown of fatty acid synthase (FASN), the enzyme that catalyzes the formation of palmitic acid from malonyl-CoA, drove NF2-deficient cells into apoptosis. Treatment of NF2-mutant cells with agents that inhibit the production of malonyl-CoA reduced their sensitivity to FASN inhibitors. Collectively, these results suggest that the altered lipid metabolism found in NF2-mutant cells renders them sensitive to elevated levels of malonyl-CoA, as occurs following blockade of FASN, suggesting new targeted strategies in the treatment of NF2-deficient tumors. Cancer Res; 77(18); 5026-38. ©2017 AACR.

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.

MicroRNA-195 inhibits the proliferation and invasion of pancreatic cancer cells by targeting the fatty acid synthase/Wnt signaling pathway

Emerging evidence suggests that microRNAs are critical regulators of cancer development and progression. MicroRNA-195 has been reported as a cancer-related microRNA in many human cancers. However, the role of microRNA-195 in pancreatic cancer remains largely unknown. Here, we show that microRNA-195 is downregulated in pancreatic cancer tissues and cell line. Also, we show that overexpression of microRNA-195 inhibits the proliferation and invasion of pancreatic cancer cells, whereas suppression of microRNA-195 promotes proliferation and invasion. We show that microRNA-195 directly targets the fatty acid synthase enzyme and negatively regulates the expression of fatty acid synthase. Also, we show that fatty acid synthase expression is inversely correlated with microRNA-195 expression in pancreatic cancer tissues. Moreover, our results show that microRNA-195 inhibits Wnt signaling in pancreatic cancer cells. By restoring fatty acid synthase expression, we were able to reverse the antitumor effects of microRNA-195 in pancreatic cancer cells. Taken together, our findings show that microRNA-195 inhibits pancreatic cancer cell proliferation and invasion by regulating the fatty acid synthase/Wnt signaling pathway, suggesting a tumor suppressive role for microRNA-195 in the development and progression of pancreatic cancer. Thus, inhibiting fatty acid synthase by microRNA-195 may serve as a novel therapeutic approach for the treatment of pancreatic cancer.

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.

MicroRNA-1207-5p inhibits hepatocellular carcinoma cell growth and invasion through the fatty acid synthase-mediated Akt/mTOR signalling pathway

Fatty acid synthase (FASN) has emerged as a unique oncologic target for the treatment of cancers, including hepatocellular carcinoma (HCC). However, effective inhibitors of FASN for cancer treatment are lacking. MicroRNAs (miRNAs) have emerged as novel and endogenic inhibitors of gene expression. In the present study, we aimed to investigate the role of miR‑1207‑5p in HCC and the regulation of FASN through miR‑1207‑5p. The expression of miR-1207-5p was markedly reduced in HCC tissues and cell lines as detected with real‑time quantitative polymerase chain reaction (qPCR). Overexpression of miR-1207-5p significantly suppressed the cell growth and invasion of HCC cells. By contrast, inhibition of miR‑1207‑5p exhibited an opposite effect. Bioinformatics analysis showed that FASN is a predicted target of miR‑1207‑5p which was validated by dual‑luciferase reporter assay, qPCR and western blot analysis. Overexpression of miR‑1207‑5p inhibited the Akt/mTOR signalling pathway, and promotion of this pathway was noted following inhibition of miR‑1207‑5p. Rescue experiments showed that the restoration of FASN expression partially reversed the inhibitory effect of miR‑1207‑5p on cell growth, invasion and Akt phosphorylation. In conclusion, our study suggests that miR‑1207‑5p/FASN plays an important role in HCC, and provides novel insight into developing new inhibitors for FASN for therapeutic interventions for HCC.

Molecular Pathways: Fatty Acid Synthase

Therapies that target tumor metabolism represent a new horizon in anticancer therapies. In particular, cancer cells are dependent on the generation of lipids, which are essential for cell membrane synthesis, modification of proteins, and localization of many oncogenic signal transduction enzymes. Because fatty acids are the building blocks of these important lipids, fatty acid synthase (FASN) emerges as a unique oncologic target. FASN inhibitors are being studied preclinically and beginning to transition to first-in-human trials. Early generation FASN inhibitors have been studied preclinically but were limited by their pharmacologic properties and side-effect profiles. A new generation of molecules, including GSK2194069, JNJ-54302833, IPI-9119, and TVB-2640, are in development, but only TVB-2640 has moved into the clinic. FASN inhibition, either alone or in combination, holds promise as a novel therapeutic approach for patients with cancer.

Inhibition of the mevalonate pathway affects epigenetic regulation in cancer cells

The mevalonate pathway provides metabolites for post-translational modifications such as farnesylation, which are critical for the activity of RAS downstream signaling. Subsequently occurring regulatory processes can induce an aberrant stimulation of DNA methyltransferase (DNMT1) as well as changes in histone deacetylases (HDACs) and microRNAs in many cancer cell lines. Inhibitors of the mevalonate pathway are increasingly recognized as anticancer drugs. Extensive evidence indicates an intense cross-talk between signaling pathways, which affect growth, differentiation, and apoptosis either directly or indirectly via epigenetic mechanisms. Herein, we show data obtained by novel transcriptomic and corresponding methylomic or proteomic analyses from cell lines treated with pharmacologic doses of respective inhibitors (i.e., simvastatin, ibandronate). Metabolic pathways and their epigenetic consequences appear to be affected by a changed concentration of NADPH. Moreover, since the mevalonate metabolism is part of a signaling network, including vitamin D metabolism or fatty acid synthesis, the epigenetic activity of associated pathways is also presented. This emphasizes the far-reaching epigenetic impact of metabolic therapies on cancer cells and provides some explanation for clinical observations, which indicate the anticancer activity of statins and bisphosphonates.

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.

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.

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.

Role of abnormal lipid metabolism in development, progression, diagnosis and therapy of pancreatic cancer

There is growing evidence that metabolic alterations play an important role in cancer development and progression. The metabolism of cancer cells is reprogrammed in order to support their rapid proliferation. Elevated fatty acid synthesis is one of the most important aberrations of cancer cell metabolism. An enhancement of fatty acids synthesis is required both for carcinogenesis and cancer cell survival, as inhibition of key lipogenic enzymes slows down the growth of tumor cells and impairs their survival. Based on the data that serum fatty acid synthase (FASN), also known as oncoantigen 519, is elevated in patients with certain types of cancer, its serum level was proposed as a marker of neoplasia. This review aims to demonstrate the changes in lipid metabolism and other metabolic processes associated with lipid metabolism in pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic neoplasm, characterized by high mortality. We also addressed the influence of some oncogenic factors and tumor suppressors on pancreatic cancer cell metabolism. Additionally the review discusses the potential role of elevated lipid synthesis in diagnosis and treatment of pancreatic cancer. In particular, FASN is a viable candidate for indicator of pathologic state, marker of neoplasia, as well as, pharmacological treatment target in pancreatic cancer. Recent research showed that, in addition to lipogenesis, certain cancer cells can use fatty acids from circulation, derived from diet (chylomicrons), synthesized in liver, or released from adipose tissue for their growth. Thus, the interactions between de novo lipogenesis and uptake of fatty acids from circulation by PDAC cells require further investigation.