Interferon-alpha enhances sensitivity of human osteosarcoma U2OS cells to doxorubicin by p53-dependent apoptosis

Identification of Potential Therapeutic Targets and Immune Cell Infiltration Characteristics in Osteosarcoma Using Bioinformatics Strategy

Osteosarcoma is one of the most aggressive malignant bone tumors worldwide. Although great advancements have been made in its treatment owing to the advent of neoadjuvant chemotherapy, the problem of lung metastasis is a major obstacle in the improvement of survival outcomes. Thus, the aim of the present study is to screen novel and key biomarkers, which may act as potential prognostic markers and therapeutic targets in osteosarcoma. We utilized the robust rank aggregation (RRA) method to integrate three osteosarcoma microarray datasets downloaded from the Gene Expression Omnibus (GEO) database, and we identified the robust differentially expressed genes (DEGs) between primary and metastatic osteosarcoma tissues. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to explore the functions of robust DEGs. The results of enrichment analysis showed that the robust DEGs were closely associated with osteosarcoma development and progression. Immune cell infiltration analysis was also conducted by CIBERSORT algorithm, and we found that macrophages are the most principal infiltrating immune cells in osteosarcoma, especially macrophages M0 and M2. Then, the protein–protein interaction network and key modules were constructed by Cytoscape, and 10 hub genes were selected by plugin cytoHubba from the whole network. The survival analysis of hub genes was also carried out based on the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database. The integrated bioinformatics analysis was utilized to provide new insight into osteosarcoma development and metastasis and identified EGR1, CXCL10, MYC, and CXCR4 as potential biomarkers for prognosis of osteosarcoma.

Integrated Analysis of DEAD-Box Helicase 56: A Potential Oncogene in Osteosarcoma

Background: Osteosarcoma is a solid tumor common in the musculoskeletal system. The DEAD-box helicase (DDX) families play an important role in tumor genesis and proliferation. Objective:To screen potential molecular targets in osteosarcoma and elucidate its relationship with DDX56. Methods: We employed the Gene Expression Omnibus and The Cancer Genome Atlas datasets for preliminary screening. DDX56 expression was measured by RT-qPCR in three osteosarcoma cell lines. Biological roles of DDX56 were explored by Gene ontology, Kyoto Encyclopedia of Genes and Genomes and Ingenuity Pathway Analysis. Cell proliferation, cycle, and apoptosis assays were performed using Lentivirus™ knockdown technique. Results: It was found that DDX56 expression was regularly upregulated in osteosarcoma tissue and cell lines, while DDX56 knockdown inhibited cell proliferation and promoted cell apoptosis. Conclusions: The findings suggest DDX56 as a potential therapeutic target for the treatment of osteosarcoma.

Loss of Runx2 sensitises osteosarcoma to chemotherapy-induced apoptosis

BACKGROUND

Osteosarcoma (OS) is the most common bone malignancy in the paediatric population, principally affecting adolescents and young adults. Minimal advancements in patient prognosis have been made over the past two decades because of the poor understanding of disease biology. Runx2, a critical transcription factor in bone development, is frequently amplified and overexpressed in OS. However, the molecular and biological consequences of Runx2 overexpression remain unclear.

METHODS

si/shRNA and overexpression technology to alter Runx2 levels in OS cells. In vitro assessment of doxorubicin (doxo)-induced apoptosis and in vivo chemosensitivity studies. Small-molecule inhibitor of c-Myc transcriptional activity was used to assess its role.

RESULTS

Loss of Runx2 sensitises cells to doxo-induced apoptosis both in vitro and in vivo. Furthermore, in conjunction with chemotherapy, decreasing Runx2 protein levels activates both the intrinsic and extrinsic apoptotic pathways. Transplanted tumour studies demonstrated that loss of endogenous Runx2 protein expression enhances caspase-3 cleavage and tumour necrosis in response to chemotherapy. Finally, upon doxo-treated Runx2 knockdown OS cells there was evidence of enhanced c-Myc expression and transcriptional activity. Inhibition of c-Myc under these conditions resulted in decreased activation of apoptosis, therefore insinuating a role for c-Myc in dox-induced activation of apoptotic pathways.

CONCLUSIONS

Therefore, we have established a novel molecular mechanism by which Runx2 provides a chemoprotective role in OS, indicating that in conjunction to standard chemotherapy, targeting Runx2 may be a new therapeutic strategy for patients with OS.

Strategy to enhance efficacy of doxorubicin in solid tumor cells by methyl-β-cyclodextrin: Involvement of p53 and Fas receptor ligand complex

Doxorubicin (DOX) is one of the preferred drugs for treating breast and liver cancers. However, its clinical application is limited due to severe side effects and the accompanying drug resistance. In this context, we investigated the effect on therapeutic efficacy of DOX by cholesterol depleting agent methyl-β-cyclodextrin (MCD), and explored the involvement of p53. MCD sensitizes MCF-7 and Hepa1–6 cells to DOX, Combination of MCD and marginal dose of DOX reduces the cell viability, and promoted apoptosis through induction of pro-apoptotic protein, Bax, activation of caspase-8 and caspase-7, down regulation of anti-apoptotic protein Bcl-2 and finally promoting PARP cleavage. Mechanistically, sensitization to DOX by MCD was due to the induction of FasR/FasL pathway through p53 activation. Furthermore, inhibition of p53 by pharmacological inhibitor pifithrin-α (PFT-α) or its specific siRNA attenuated p53 function and down-regulated FasR/FasL, thereby preventing cell death. Animal experiments were performed using C57BL/6J mouse isografted with Hepa1–6 cells. Tumor growth was retarded and survival increased in mice administered MCD together with DOX to as compared to either agent alone. Collectively, these results suggest that MCD enhances the sensitivity to DOX for which wild type p53 is an important determinant.

Translational biology of osteosarcoma

For the past 30 years, improvements in the survival of patients with osteosarcoma have been mostly incremental. Despite evidence of genomic instability and a high frequency of chromothripsis and kataegis, osteosarcomas carry few recurrent targetable mutations, and trials of targeted agents have been generally disappointing. Bone has a highly specialized immune environment and many immune signalling pathways are important in bone homeostasis. The success of the innate immune stimulant mifamurtide in the adjuvant treatment of non-metastatic osteosarcoma suggests that newer immune-based treatments, such as immune checkpoint inhibitors, may substantially improve disease outcome.

Ocotillol Enhanced the Antitumor Activity of Doxorubicin via p53-Dependent Apoptosis

The use of doxorubicin (Dox) was severely constrained by dose-dependent side effects, which might be attenuated by combining a “sensitizer” to decrease its cumulative dosage. In this study, it was investigated whether ocotillol could enhance the antiproliferation activity of Dox. MTT assays and xenograft tumor model were firstly conducted to evaluate the effect of ocotillol on the antitumor activity of Dox. Flow cytometry and Hoechst staining assays were then performed to assess cell apoptosis. Western blot and real-time PCR were finally used to detect the expression of p53 and its target genes. Our results showed ocotillol to enhance Dox-induced cell death in p53 wild-type cancer cells. Compared with Dox alone, Dox with ocotillol (Dox-O) could induce much more cell apoptosis and activate p53 to a much greater degree, which in turn markedly increased expression of proapoptosis genes. The enhanced cytotoxic activity was partially blocked by pifithrin-α, which might be through attenuating the increased apoptosis. Furthermore, ocotillol significantly increased the antitumor activity of Dox in A549 xenograft tumor in nude mice. These findings indicated that ocotillol could potentiate the cytotoxic effect of Dox through p53-dependent apoptosis and suggested that coadministration of ocotillol with Dox might be a potential therapeutic strategy.

Hypoxia-induced cytotoxic drug resistance in osteosarcoma is independent of HIF-1Alpha

Survival rates from childhood cancer have improved dramatically in the last 40 years, such that over 80% of children are now cured. However in certain subgroups, including metastatic osteosarcoma, survival has remained stubbornly poor, despite dose intensive multi-agent chemotherapy regimens, and new therapeutic approaches are needed. Hypoxia is common in adult solid tumours and is associated with treatment resistance and poorer outcome. Hypoxia induces chemotherapy resistance in paediatric tumours including neuroblastoma, rhabdomyosarcoma and Ewing’s sarcoma, in vitro, and this drug resistance is dependent on the oxygen-regulated transcription factor hypoxia inducible factor-1 (HIF-1). In this study the effects of hypoxia on the response of the osteosarcoma cell lines 791T, HOS and U2OS to the clinically relevant cytotoxics cisplatin, doxorubicin and etoposide were evaluated. Significant hypoxia-induced resistance to all three agents was seen in all three cell lines and hypoxia significantly reduced drug-induced apoptosis. Hypoxia also attenuated drug-induced activation of p53 in the p53 wild-type U2OS osteosarcoma cells. Drug resistance was not induced by HIF-1α stabilisation in normoxia by cobalt chloride nor reversed by the suppression of HIF-1α in hypoxia by shRNAi, siRNA, dominant negative HIF or inhibition with the small molecule NSC-134754, strongly suggesting that hypoxia-induced drug resistance in osteosarcoma cells is independent of HIF-1α. Inhibition of the phosphoinositide 3-kinase (PI3K) pathway using the inhibitor PI-103 did not reverse hypoxia-induced drug resistance, suggesting the hypoxic activation of Akt in osteosarcoma cells does not play a significant role in hypoxia-induced drug resistance. Targeting hypoxia is an exciting prospect to improve current anti-cancer therapy and combat drug resistance. Significant hypoxia-induced drug resistance in osteosarcoma cells highlights the potential importance of hypoxia as a target to reverse drug resistance in paediatric osteosarcoma. The novel finding of HIF-1α independent drug resistance suggests however other hypoxia related targets may be more relevant in paediatric osteosarcoma.

Synergistic cytotoxic effects of inorganic phosphate and chemotherapeutic drugs on human osteosarcoma cells

Novel therapeutic approaches are required for the treatment of osteosarcoma. Combination chemotherapy is receiving increased attention in order to identify compounds that may increase the therapeutic index of clinical anticancer drugs. In this regard, naturally occurring molecules with antitumor activity and with limited toxicity to normal tissues have been suggested as possible candidates for investigation of their synergistic efficacy in combination with antineoplastic drugs. Inorganic phosphate (Pi) is an essential nutrient for living organisms. Relevantly, Pi has emerged as an important signaling molecule capable of modulating multiple cellular functions by altering signal transduction pathways, gene expression and protein abundance in many cell types. Previously, we showed that Pi inhibits proliferation and aggressiveness of U2OS human osteosarcoma cells and that Pi is capable of inducing sensitization of osteosarcoma cells to doxorubicin in a p53-dependent manner. In this study, we extended the role of Pi in the chemosensitivity of osteosarcoma cells to other anticancer drugs. Specifically, we report and compare the antiproliferative effects of a combination between Pi and doxorubicin, Taxol^® and 5-fluorouracil (5-FU) treatments. We found that Pi increases the antiproliferative response to both Taxol and doxorubicin to a similar extent. On the other hand, Pi did not potentiate the anticancer effects induced by 5-FU. These effects were paralleled by apoptosis induction and were cell cycle-dependent. The clinical significance of our data and their potential therapeutic applications for improving osteosarcoma treatment are discussed.

Inorganic phosphate enhances sensitivity of human osteosarcoma U2OS cells to doxorubicin via a p53-dependent pathway

Osteosarcoma is the most common malignant primary bone tumor in children and adolescents. The clinical outcome for osteosarcoma remains discouraging despite aggressive surgery and intensive radiotherapy and chemotherapy regimens. Thus, novel therapeutic approaches are needed. Previously, we have shown that inorganic phosphate (Pi) inhibits proliferation and aggressiveness of human osteosarcoma U2OS cells identifying adenylate cyclase, beta3 integrin, Rap1, ERK1/2 as proteins whose expression and function are relevantly affected in response to Pi. In this study, we investigated whether Pi could affect chemosensitivity of osteosarcoma cells and the underlying molecular mechanisms. Here, we report that Pi inhibits proliferation of p53-wild type U2OS cells (and not of p53-null Saos and p53-mutant MG63 cells) by slowing-down cell cycle progression, without apoptosis occurrence. Interestingly, we found that Pi strongly enhances doxorubicin-induced cytotoxicity in U2OS, and not in Saos and MG63 cells, by apoptosis induction, as revealed by a marked increase of sub-G1 population, Bcl-2 downregulation, caspase-3 activation, and PARP cleavage. Remarkably, Pi/doxorubicin combination-induced cytotoxicity was accompanied by an increase of p53 protein levels and of p53 target genes mdm2, p21 and Bax, and was significantly reduced by the p53 inhibitor pifithrine-alpha. Moreover, the doxorubicin-induced cytotoxicity was associated with ERK1/2 pathway inhibition in response to Pi. Altogether, our data enforce the evidence of Pi as a novel signaling molecule capable of inhibiting ERK pathway and inducing sensitization to doxorubicin of osteosarcoma cells by p53-dependent apoptosis, implying that targeting Pi levels might represent a rational strategy for improving osteosarcoma therapy.

Regulation of interferon pathway in 2-methoxyestradiol-treated osteosarcoma cells

Background

Osteosarcoma is a bone tumor that often affects children and young adults. Although a combination of surgery and chemotherapy has improved the survival rate in the past decades, local recurrence and metastases still develop in 40% of patients. A definite therapy is yet to be determined for osteosarcoma. Anti- tumor compound and a metabolite of estrogen, 2-methoxyestradiol (2-ME) induces cell death in osteosarcoma cells. In this report, we have investigated whether interferon (IFN) pathway is involved in 2-ME-induced anti-tumor effects in osteosarcoma cells.

Methods

2-ME effects on IFN mRNA levels were determined by Real time PCR analysis. Transient transfections followed by reporter assays were used for investigating 2-ME effects on IFN-pathway. Western blot analyses were used to measure protein and phosphorylation levels of IFN-regulated eukaryotic initiation factor-2 alpha (eIF-2α).

Results

2-ME regulates IFN and IFN-mediated effects in osteosarcoma cells. 2 -ME induces IFN gene activity and expression in osteosarcoma cells. 2-ME treatment induced IFN-stimulated response element (ISRE) sequence-dependent transcription and gamma-activated sequence (GAS)-dependent transcription in several osteosarcoma cells. Whereas, 2-ME did not affect IFN gene and IFN pathways in normal primary human osteoblasts (HOB). 2-ME treatment increased the phosphorylation of eIF-2α in osteosarcoma cells. Furthermore, analysis of osteosarcoma tissues shows that the levels of phosphorylated form of eIF-2α are decreased in tumor compared to normal controls.

Conclusions

2-ME treatment triggers the induction and activity of IFN and IFN pathway genes in 2-ME-sensitive osteosarcoma tumor cells but not in 2-ME-resistant normal osteoblasts. In addition, IFN-signaling is inhibited in osteosarcoma patients. Thus, IFN pathways play a role in osteosarcoma and in 2-ME-mediated anti-proliferative effects, and therefore targeted induction of IFN signaling could lead to effective treatment strategies in the control of osteosarcoma.

Review of therapeutic strategies for osteosarcoma, chondrosarcoma, and Ewing's sarcoma

The most prevalent forms of bone cancer are osteosarcoma, chondrosarcoma, and Ewing’s sarcoma. Although chemotherapy and radiotherapy have replaced traditional surgical treatments, survival rates have undergone only marginal improvements. Current knowledge of the molecular pathways involved in each type of cancer has led to better approaches in cancer treatment. A number of cell signaling molecules are involved in tumorigenesis, and specific targets have been identified based on these signal transducers. This review highlights some of the important cellular pathways and potential therapeutic targets, tumor site-specific irradiation techniques, and novel drug delivery systems used to administer these drugs.

IGF1R-targeted therapy and its enhancement of doxorubicin chemosensitivity in human osteosarcoma cell lines

Type-I insulin-like growth factor receptor (IGF1R) and its signaling play an important role in osteosarcomagenesis, tumor progression, and chemoresistance. The purpose of this study was to investigate both the effect and mechanisms of IGF1R inhibition by tyrphostin AG1024 in the presence or absence of doxorubicin in a panel of six osteosarcoma cell lines and a self-established doxorubicin-resistant cell line. We are the first to indicate that targeting IGF1R together with doxorubicin achieved additive anti-osteosarcoma growth effect, accompanied with increased apoptosis, cytotoxicity, and dual cell cycle arrests. In conclusion, IGF1R inhibition can enhance doxorubicin chemotherapy in some osteosarcoma cell lines.

Molecular alterations as target for therapy in metastatic osteosarcoma: a review of literature

Treating metastatic osteosarcoma (OS) remains a challenge in oncology. Current treatment strategies target the primary tumour rather than metastases and have a limited efficacy in the treatment of metastatic disease. Metastatic cells have specific features that render them less sensitive to therapy and targeting these features might enhance the efficacy of current treatment. A detailed study of the biological characteristics and behaviour of metastatic OS cells may provide a rational basis for innovative treatment strategies. The aim of this review is to give an overview of the biological changes in metastatic OS cells and the preclinical and clinical efforts targeting the different steps in OS metastases and how these contribute to designing a metastasis directed treatment for OS.

Interferon-α/β receptor as a prognostic marker in osteosarcoma

BACKGROUND

A large-scale randomized trial of adjuvant interferon-α therapy for patients with osteosarcoma has been initiated as a joint protocol by the European and American Osteosarcoma Study Group. Because the expression of functional interferon-α/β receptor is necessary for interferon-α agents to interact with osteosarcoma cells, we examined the expression of interferon-α/β receptor in a series of osteosarcoma specimens.

METHODS

Forty patients with high-grade resectable osteosarcoma, from whom surgical specimens had been obtained at the time of biopsy, were included in this retrospective study. Biopsy specimens were immunohistochemically stained with anti-interferon-α/β receptor antibodies. Survival was estimated with the Kaplan-Meier method. The Cox proportional hazards model was used for multivariate analysis to determine the independent prognostic factors. Furthermore, we used Holm and Benjamini-Hochberg procedures to adjust for multiple comparisons in setting the level of significance. The median follow-up period was five years and two months (range, four to 195 months).

RESULTS

The expression of interferon-α/β receptor was positive in eighteen (45%) of the forty patients with high-grade osteosarcoma. American Joint Committee on Cancer surgical stage IIA, a good histologic response to chemotherapy, and expression of interferon-α/β receptor correlated significantly with better disease-free survival (p < 0.05). Multivariate analysis showed that interferon-α/β receptor expression alone retained its power to predict an improved prognosis (p = 0.042). There were no significant variables after corrections for multiple comparisons.

CONCLUSIONS

Interferon-α/β receptor may be a useful marker for assessing tumor prognosis in patients with osteosarcoma and may play an important role in tumor progression. These findings are encouraging and support the ongoing clinical trials of adjuvant interferon-α therapy by the multinational Osteosarcoma Study Group. Our pilot study was based on a small sample size, and larger trials are needed to confirm this finding.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.

Osteosarcoma treatment: state of the art

Osteosarcoma (OS) is a class of cancer originating from bone, mainly afflicting children or young adults. It is the second highest cause of cancer-related death in these age groups, mainly due to development of often fatal metastasis, usually in the lungs. Survival for these patients is poor despite the aggressive use of surgery, chemotherapy, and/or radiotherapy. Thus, new effective drugs and other forms of therapy are needed. This article reviews the biology and the state of the art management of OS. New experimental drugs and potential therapies targeting molecular pathways of OS are also discussed.

Interferon-alpha restrains growth and invasive potential of hepatocellular carcinoma induced by hepatitis B virus X protein

AIM: To investigate the effects of interferon-alpha (IFN-α) to restrain the growth and invasive potential of hepatocellular carcinoma (HCC) induced by hepatitis B virus (HBV) X protein.

METHODS: The pcDNA3.1-HBx plasmid was transfected into Chang cells by Lipofectamine in vitro, and Chang/HBx was co-cultured with IFN-α. Cell survival growth curve and clonogenicity assay were used to test the growth potential of Chang/pcDNA3.1, Chang/HBx and IFN-α-Chang/HBx in vitro. Growth assay in nude mice was used to detect the growth potential of Chang/pcDNA3.1, Chang/HBx and IFN-α-Chang/HBx in vivo. Wound healing and transwell migration assays were used to detect the invasive ability of Chang/pcDNA3.1, Chang/HBx and IFN-α-Chang/HBx.

RESULTS: Compared with CCL13 cells transfected with pcDNA3.1, CCL13 with stable expression of hepatitis B virus X protein showed the characteristics of malignant cells with high capability of growth and invasion by detecting their growth curves, colony forming efficiency, wound healing , transwell migration assays and growth assays in nude mice. Its capability of growth and invasion could be controlled by IFN-α.

CONCLUSION: IFN-α can restrain the growth and invasive potential of HCC cells induced by HBx protein, which has provided an experimental basis for IFN-α therapy of HCC.