Strategies for the targeted delivery of therapeutics for osteosarcoma

Clemastine and hyperthermia enhance sensitization of osteosarcoma cells for apoptosis

Clemastine is an antagonist of histamine H1 receptor may provide benefits in the treatment of osteosarcoma (OS). In the current study, we used hyperthermia approach to sensitize OS cells to clemastine-mediated cell death. Osteosarcoma U-2 OS and Saos-2 cells were treated with clemastine at 37°C, followed by 42°C for 2 h, and released at 37°C for 6 h. The impact of clemastine and hyperthermia on OS cell survival and autophagy-mediated cell death was investigated. Exposure of U-2 OS and Saos-2 cells to clemastine and hyperthermia (42°C) inhibited dose-dependent clemastine-mediated cell survival by increasing cell apoptosis. Hyperthermia and clemastine exposure modulated inflammatory and unfolded protein response (UPR) signaling differentially in U-2 OS and Saos-2 cells. Exposure of U-2 OS and Saos-2 cells to hyperthermia and clemastine inhibited AKT/mTOR and induced expression of the autophagy biomarkers LC3B II and LC3-positive puncta formation. The inhibition of autophagy by 3-methyladenine blocked hyperthermia and clemastine-mediated induction of LC3B II, LC3-positive puncta formation, and OS cell apoptosis. These results indicate that clemastine and hyperthermia sensitize OS cell lines by inducing increased autophagic cell death. Collectively, our data suggest that hyperthermia along with antihistamine therapy may provide an improved approach for the treatment of OS.

Hypermethylated PODN represses the progression of osteosarcoma by inactivating the TGF-β/Smad2/3 pathway

BACKGROUND

PODN is reported to be an promising biomarker for prognosis of osteosarcoma (OS), while the specific function of PODN has not been explored in OS. This study is designed to explore the function and underlying mechanism of PODN in OS.

METHODS

The mRNA expression of PODN was determined using qRT-PCR. Protein levels of PODN, DNMT1, DNMT3A, DNMT3B, TGF-β1, Smad2/3 and p-Smad2/3 were detected using western blot. The methylation of PODN was determined with methylation-specific PCR. Moreover, CCK-8 assay and colony formation assay were used for assessing the proliferation of OS cells. Transwell assay was used to evaluate migration and invasion abilities of OS cells. Immunohistochemical staining was performed to determine the protein expression of Ki67 and PODN in tumor tissues. For constructing a xenograft tumor model, MG-63 cells were introduced into the right side of the mouse back via subcutaneous injection.

RESULTS

PODN was lowly expressed and was hypermethylated in OS tissues and cells. PODN overexpression prevented OS cells from proliferating, migrating and invading, and inhibited tumorigenesis in xenograft mice. After PODN overexpression, protein levels of TGF-β1 and p-Smad2/3 were decreased in OS cells. Meantime, the suppressive effects of PODN overexpression on proliferation, migration and invasion of OS cells as well as mouse tumorigenesis were partly counteracted by TGF-β1 overexpression.

CONCLUSIONS

PODN overexpression inactivated the TGF-β/Smad2/3 pathway to suppress OS development in vitro and in vivo.

Posttranscriptional inhibition of γ-adducin promotes the proliferation and migration of osteosarcoma cells

OBJECTIVE

The expression of cytoskeleton-related protein γ-adducin (ADD3) was abnormally reduced in some tumors. Functional experiments demonstrated that it could inhibit the malignant progression of lung cancer and glioma, whereas the involvement of ADD3 in osteosarcoma was not clear. This study aimed to investigate the role of ADD3 in osteosarcoma and its upstream regulatory mechanisms.

METHODS

ADD3 was knocked down by siRNA transfection and the expression level of ADD3 was determined using quantitative real-time PCR assay and Western blot. CCK-8 assay and colony formation were performed to detect the capacity of cell proliferation. Transwell assay and PI and Annexin V-FITC staining were used to determine cell migration and apoptosis, respectively. Luciferase reporter experiment was performed to investigate the interaction between ADD3 and miR-23b-3p.

RESULTS

Based on gene silencing assays, we showed that knockdown of ADD3 suppressed apoptosis and promoted the proliferation and migration of osteosarcoma cells, revealing inhibitory effects of ADD3 in osteosarcoma. Luciferase reporter gene assays confirmed that miR-23b-3p could bind to the 3'-UTR of ADD3. Upregulation of miR-23b-3p not only inhibited the expression of ADD3, but also released the tumor suppressive role of ADD3 on the proliferation and migration of osteosarcoma cells.

CONCLUSIONS

Our study found that ADD3 functioned as a tumor suppressor gene during osteosarcoma development. The abnormal upregulation of miR-23b-3p targeted the expression of ADD3 and resulted in accelerated osteosarcoma cell proliferation and migration. Thus, the miR-23b-3p/ADD3 axis contributes to the development of osteosarcoma and ADD3 is a key driver of malignancy.

LINC00174 Facilitates Cell Proliferation, Cell Migration and Tumor Growth of Osteosarcoma via Regulating the TGF-β/SMAD Signaling Pathway and Upregulating SSH2 Expression

Osteosarcoma (OS), a frequent malignant tumor which mainly occurs in the bone. The roles of long noncoding RNAs (lncRNAs) have been revealed in cancers, including OS. LncRNA long intergenic non-protein coding RNA (LINC00174) has been validated as an oncogene in several cancers. However, the role of LINC00174 in OS has not been explored. In our research, loss-of-function assays were conducted to explore the function of LINC00174 in OS cells. Then, we explored the downstream pathway of LINC00174 in OS cells. Bioinformatics, RNA pull-down and RIP experiments investigated the downstream mechanism of LINC00174 in OS cells. Finally, in vivo assays clarified the effect of LINC00174 on tumorigenesis. We found that LINC00174 was upregulated in OS tissues and cells. LINC00174 knockdown repressed OS cell growth. Mechanistically, LINC00174 knockdown suppressed the TGF-β/SMAD pathway. LINC00174 interacted with miR-378a-3p, and slingshot protein phosphatase 2 (SSH2) 3′UTR was targeted by miR-378a-3p in OS cells. Rescue assays showed that SSH2 upregulation or miR-378a-3p inhibition counteracted the inhibitory effect of LINC00174 depletion in OS cell growth. Additionally, LINC00174 depletion suppressed tumor growth in mice. In conclusion, LINC00174 promotes OS cellular malignancy and tumorigenesis via the miR-378a-3p/SSH2 axis and the TGF-β/SMAD pathway, which might provide a novel insight for OS treatment.

Berberine and Cisplatin Exhibit Synergistic Anticancer Effects on Osteosarcoma MG-63 Cells by Inhibiting the MAPK Pathway

Berberine (BBR) has been reported to have potent anticancer activity and can increase the anticancer effects of chemotherapy drugs. The present study aims to investigate whether BBR and cisplatin (DDP) exert synergistic effects on the osteosarcoma (OS) MG-63 cell line. In the present study, MG-63 cells were treated with BBR and DDP alone or in combination. The effects of these therapeutics on cell viability, colony formation, migration, invasion, nuclear morphology, apoptosis, and the cell cycle, as well as their role in regulating the expression of proteins related to apoptosis, the cell cycle, and the mitogen-activated protein kinase (MAPK) pathway, were determined. The results demonstrated that BBR or DDP significantly inhibited the proliferation of MG-63 cells in a dose- and time-dependent manner. The combination treatment of BBR and DDP exerted a prominent inhibitory effect on proliferation and colony formation. Furthermore, the results showed that the combination treatment of BBR and DDP enhanced the inhibition of cell migration and invasion and reversed the changes in nuclear morphology. The results showed that the combination treatment of BBR and DDP induced apoptosis and cell cycle arrest in the G0/G1 phase. Mechanistically, the combination treatment of BBR and DDP inhibited the expression of MMP-2/9, Bcl-2, CyclinD1, and CDK4, enhanced the expression of Bax and regulated the activity of the MAPK pathway. Collectively, our data suggest that the combination therapy of BBR and DDP markedly enhanced OS cell death.

Sterically stabilized recombined HDL composed of modified apolipoprotein A-I for efficient targeting toward glioma cells

Reconstituted high density lipoprotein (rHDL) has been regarded as a promising brain-targeting vehicle for anti-glioma drugs under the mediation of apolipoprotein A-I (apoA-I). However, some stability issues relating to drug leakage and consequent reduced targeting efficiency in the course of discoidal rHDL (d-rHDL) circulating in blood hinder its broad application. The objective of the study was to develop a novel stabilized d-rHDL by replacing cholesterol and apoA-I with mono-cholesterol glutarate (MCG) modified apoA-I (termed as mA) and to evaluate its allosteric behavior and glioma targeting. MCG was synthesized through esterifying the hydroxyl of cholesterol with glutaric anhydride and characterized by FI-IR and 1H NMR. d-rHDL assembled with mA (termed as m-d-rHDL) presented similar properties such as minute particle size and disk-like appearance resembling nascent HDL. Morphological transformation observation and in vitro release plots convinced that the modification of cholesterol could effectively inhibit the remolding of d-rHDL. The uptake of m-d-rHDL by LCAT-pretreated bEND.3 cells was significantly higher than that of d-rHDL, thereby serving as another proof for the capability of m-d-rHDL in enhancing targeting property. Besides, apoA-I anchoring into m-d-rHDL played a critical role in the endocytosis process into bEND.3 cells and C6 cells, which implied the possibility of traversing blood brain barrier and accumulating in the brain and glioma. These results suggested that the modification toward cholesterol to improve the stability of d-rHDL is advantageous, and that this obtained m-d-rHDL revealed great potential for realization of suppressing the remolding of d-rHDL in the brain-targeted treatment of glioma for drug delivery.

Circular RNA Circ-03955 Promotes Epithelial-Mesenchymal Transition in Osteosarcoma by Regulating miR-3662/Metadherin Pathway

Osteosarcoma is the most common primary malignant tumor, especially in children and adolescents. Circular RNAs (circRNAs) are found to play roles in the progression of osteosarcoma. However, the exact functions of circRNAs in osteosarcoma development still need to be clarified. We obtained differentially expressed circRNAs and miRNAs from a GSE99671 data set (GEO database). The gene co-expression network of ceRNAs and osteosarcoma-related genes was analyzed using the STRING database. qRT-PCR was used to detect the expression of circ-03955 and miR-3662. Transwell assays and flow cytometry were performed to detect phenotypic changes in cell function. A xenograft tumor model was established using BALB/c nude mice. Dual luciferase activity and RNA immunoprecipitation assays were performed to assess the relationship between circ-03955, miR-3662, and metadherin (MTDH). Immunohistochemistry, immunofluorescence, and Western blotting were used to assess protein expression levels. Circ-03955 was significantly upregulated, and miR-3662 was downregulated in osteosarcoma. Circ-03955 silencing inhibited the growth and metastasis of osteosarcoma. Mechanism analysis revealed that circ-03955 could bind to miR-3662, and the latter could target MTDH, leading to its suppressed expression and facilitating epithelial-mesenchymal transition (EMT). All these findings demonstrate that the presence of circ-03955 promotes EMT in osteosarcoma by acting as miR-3662 sponge-mediated MTDH expression.

Caffeine citrate enhanced cisplatin antitumor effects in osteosarcoma and fibrosarcoma in vitro and in vivo

Background

While multiagent chemotherapy has dramatically improved the prognosis of sarcoma, the novel chemotherapeutics have hardly developed over the past 30 years. Caffeine can induce apoptosis, delays in cell cycle progression and can enhance the cytocidal effects of anti-cancer agents. Citrate has been reported to enhance the cytocidal effect of cisplatin in gastric cancer in vitro. However its effect in sarcoma cells had not been reported.

Methods

This study was designed to evaluate whether the addition of caffeine, citrate, or caffeine citrate to cisplatin improved its cytocidal effect (cell survival, proliferation, and apoptosis) on human osteosarcoma (HOS), human fibrosarcoma (HT1080) and murine osteosarcoma (LM8) cell lines. We also tested the various combinations in a mouse heterotopic transplantation model in vivo. In cell survival assay, combination index (CI) of caffeine citrate was calculated as a combination of anhydrous caffeine and citric acid, and the synergy was evaluated (CI < 1.0).

Results

In all cell lines, cisplatin combined with caffeine citrate significantly reinforced the anticancer effect compared with cisplatin alone, combination of cisplatin and anhydrous caffeine, and combination of cisplatin and citric acid. Moreover, CI was < 1.0 in all conditions. The anticancer agent reinforcement effect of caffeine citrate was synergy of anhydrous caffeine and citric acid. In cell proliferation and cell cycle assay revealed that caffeine citrate had most strong effect as a combination drug than caffeine and citric acid in inducing G0/G1 cell-cycle arrest with subsequent suppressed cell proliferation. In mitochondrial depolarization and caspase 3/7 activity assay revealed that caffeine citrate had most strong effect as a combination drug than caffeine and citric acid in apoptosis associated with decreased mitochondrial membrane potential. In vivo, three different drug concentrations were tested, and cisplatin combined with caffeine citrate was found to have the strongest antitumor effect.

Conclusions

This is the first report demonstrating that caffeine citrate has a significantly greater potentiating effect on cisplatin than adding either caffeine or citric acid. The combination of cisplatin with caffeine citrate is a novel treatment that might hold promise for improving the outcome of osteosarcoma and fibrosarcoma, which up till now has generally not responded well to chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5891-y) contains supplementary material, which is available to authorized users.

Non-Viral Delivery System and Targeted Bone Disease Therapy

Skeletal systems provide support, movement, and protection to the human body. It can be affected by several life suffering bone disorders such as osteoporosis, osteoarthritis, and bone cancers. It is not an easy job to treat bone disorders because of avascular cartilage regions. Treatment with non-specific drug delivery must utilize high doses of systemic administration, which may result in toxicities in non-skeletal tissues and low therapeutic efficacy. Therefore, in order to overcome such limitations, developments in targeted delivery systems are urgently needed. Although the idea of a general targeted delivery system using bone targeting moieties like bisphosphonates, tetracycline, and calcium phosphates emerged a few decades ago, identification of carrier systems like viral and non-viral vectors is a recent approach. Viral vectors have high transfection efficiency but are limited by inducing immunogenicity and oncogenicity. Although non-viral vectors possess low transfection efficiency they are comparatively safe. A number of non-viral vectors including cationic lipids, cationic polymers, and cationic peptides have been developed and used for targeted delivery of DNA, RNA, and drugs to bone tissues or cells with successful consequences. Here we mainly discuss such various non-viral delivery systems with respect to their mechanisms and applications in the specific targeting of bone tissues or cells. Moreover, we discuss possible therapeutic agents that can be delivered against various bone related disorders.

Glucose-Regulated Protein 94 Modulates the Response of Osteosarcoma to Chemotherapy

Background

Osteosarcoma (OS) is the most common and most aggressive primary solid malignant bone tumor in children and young adults and has high rates of recurrence and metastasis. The endoplasmic reticulum (ER) stress pathway is important in regulating the chemo-responsiveness of cancer. However, the role of glucose-regulated protein 94 (GRP94) in regulating the response of OS to chemotherapy has never been explored.

Methods

In this study, two OS cell lines, MG63 and 143B cells, were used to evaluate the mechanism by which GRP94 modulates the response of osteosarcoma to chemotherapy. GRP94-knockdown (GRP94-KD) OS cells were generated using short hairpin RNAs, and the response to chemotherapy was assessed using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cell apoptosis was quantified with propidium iodide (PI) staining and flow cytometry.

Results

Silencing of GRP94 in MG63 and 143B cells did not influence the growth and migration of the cells, but reduced the colony formation. GRP94-KD OS cells were more resistant to paclitaxel, gemcitabine, and epirubicin treatments than cells transfected with the scrambled control, and more cells transfected with the scrambled control underwent apoptosis after paclitaxel, gemcitabine, and epirubicin treatments than GRP94-KD cells.

Conclusions

Therefore, GRP94 silencing may increase the resistance of MG63 and 143B cells to paclitaxel, gemcitabine, and epirubicin treatments by inhibiting the induction of apoptosis. Thus, GRP94 may be a key biomarker for the chemotherapeutic response of OS.

Global analysis of osteosarcoma lipidomes reveal altered lipid profiles in metastatic versus nonmetastatic cells

Osteosarcoma (OS) is the most common form of primary bone cancer in humans. The early detection and subsequent control of metastasis has been challenging in OS. Lipids are important constituents of cells that maintain structural integrity that can be converted into lipid-signaling molecules and are reprogrammed in cancerous states. Here, we investigate the global lipidomic differences in metastatic (143B) and nonmetastatic (HOS) human OS cells as compared with normal fetal osteoblast cells (FOB) using lipidomics. We detect 15 distinct lipid classes in all three cell lines that included over 1,000 lipid species across various classes including phospholipids, sphingolipids and ceramides, glycolipids, and cholesterol. We identify a key class of lipids, diacylglycerols, which are overexpressed in metastatic OS cells as compared with their nonmetastatic or nontumorigenic counterparts. As a proof of concept, we show that blocking diacylglycerol synthesis reduces cellular viability and reduces cell migration in metastatic OS cells. Thus, the differentially regulated lipids identified in this study might aid in biomarker discovery, and the synthesis and metabolism of specific lipids could serve as future targets for therapeutic development.

Chinese Herbal Medicine for Osteosarcoma in the Mouse: A Systematic Review and Meta-Analysis

OBJECTIVE

To summarize and critically assess the inhibitory effects of Chinese herbal medicine (CHM) on tumor volume and tumor weight for the treatment of osteosarcoma (OS) in mouse models.

METHODS

PubMed, Embase, Web of Science, China Knowledge Resource Integrated Database (CNKI), Wanfang Database, VIP Database, and Chinese BioMedical (CBM) were searched since their inception dates to March 10, 2016. Two reviewers independently selected the controlled studies estimating effects of CHM on mouse OS by administration in vivo. A pair-wise meta-analysis was performed. Twenty-five studies with adequate randomization were included in the systematic review.

RESULTS

CHM may significantly inhibit OS growth in mice, as assessed using the tumor weight [20 studies, n=443; 290 for CHM and 153 for the control: pooled mean difference (MD)=-2.90; 95% confidence interval (Cl): -3.50 to -2.31: P<0.01], tumor volume (16 studies, n=382; 257 for CHM and 125 for the control; pooled MD =-2.57; 95% Cl: -3.33 to -1.80; P<0.01) and tumor growth inhibition rate.

CONCLUSION

CHM could significantly inhibit the growth of OS in mouse models, which might be supportive for the design of preclinical and clinical trials in future.

miR‑23b‑3p promotes the apoptosis and inhibits the proliferation and invasion of osteosarcoma cells by targeting SIX1

Osteosarcoma (OS) is the most common primary malignant bone tumor and the third most common cancer that occurs during childhood and adolescence. Increasing evidence has suggested that microRNA (miR)‑23b‑3p has an important role in OS tumorigenesis; however, the underlying molecular mechanisms remain unknown. The aim of the present study was to investigate the expression levels of miR‑23b‑3p and sine oculis homeobox homolog 1 (SIX1) in OS tissues and cell lines (MG‑63, SaOS‑2 and U2OS), as well as to observe the effects of miR‑23b‑3p on U2OS cell viability, cell cycle, apoptosis and invasive ability. The results revealed that the expression levels of miR‑23b‑3p were significantly decreased in OS tissues and cell lines compared with tumor‑adjacent normal tissues and a non‑cancerous human fetal osteoblastic cell line (hFOB1.19). To investigate the underlying mechanisms of miR‑23b‑3p in OS tumorigenesis and progression, human U2OS cell lines over‑ or under expressing miR‑23b‑3p were established. The effects of miR‑23b‑3p on U2OS cell viability, cell cycle, apoptosis and invasion properties were determined by performing Cell Counting Kit‑8, flow cytometry and Transwell invasion assays. miR‑23b‑3p was revealed to suppress cell viability, proliferation and invasion, and to enhance the levels of cell apoptosis. Furthermore, SIX1 mRNA and protein expression levels in OS tissues and cell lines were significantly upregulated when compared with tumor‑adjacent normal tissues and hFOB 1.19 cells, which suggested that SIX1 expression levels may be inversely associated with miR‑23b‑3p levels in OS. Luciferase reporter system analysis demonstrated that miR‑23b‑3p binds to the SIX1 3'‑untranslated region. miR‑23b‑3p downregulation contributed to SIX1 upregulation, which facilitated the potentiation of cyclin D1 and vascular endothelial growth factor‑C expression levels, as well as the inhibition of caspase‑3 expression. Collectively, these results suggested that miR‑23b‑3p is downregulated and SIX1 is upregulated in OS cells, and that miR‑23b‑3p inhibition may suppress the proliferation and invasion of OS cells, and contribute to cell apoptosis via negative regulation of SIX1. miR‑23b‑3p/SIX1 may therefore represent a potential target for the treatment of OS.

Nanomedicines for Pediatric Cancers

Chemotherapy protocols for childhood cancers are still problematic due to the high toxicity associated with chemotherapeutic agents and incorrect dosing regimens extrapolated from adults. Nanotechnology has demonstrated significant ability to reduce toxicity of anticancer compounds. Improvement in the therapeutic index of cytostatic drugs makes this strategy an alternative to common chemotherapy in adults. However, the lack of nanomedicines specifically for pediatric cancer care raises a medical conundrum. This review highlights the current state and progress of nanomedicine in pediatric cancer and discusses the real clinical challenges and opportunities.

Combination of electroporation delivered metabolic modulators with low-dose chemotherapy in osteosarcoma

BACKGROUND

Osteosarcoma accounts for roughly 60% of all malignant bone tumors in children and young adults. The five-year survival rate for localized tumors after surgery and chemotherapy is approximately 70% whilst it drastically reduces to 15-30% in metastatic cases. Metabolic modulation is known to increase sensitivity of cancers to chemotherapy. A novel treatment strategy in Osteosarcoma is needed to battle this devastating malady.

RESULTS

Electroporation-delivered metabolic modulators were more effective in halting the cell cycle of Osteosarcoma cells and this negatively affects their ability to recover and proliferate, as shown in colony formation assays. Electroporation-delivered metabolic modulators increase the sensitivity of Osteosarcoma cells to chemotherapy and this combination reduces their survivability.

CONCLUSION

This novel treatment approach highlights the efficacy of electroporation in the delivery of metabolic modulators in Osteosarcoma cells, and increased sensitivity to chemotherapy allowing for a lower dose to be therapeutic.

METHODS

Metabolic modulations of two Osteosarcoma cell lines were performed with clinically available modulators delivered using electroporation, and its combination with low-dose Cisplatin. The effects of Dicholoroacetic acid, 2-Deoxy-D-glucose and Metformin on cell cycle and recovery of Osteosarcoma cells were assessed. Their sensitivity to chemotherapy was also assessed when treated in combination with electroporation-delivered metabolic modulators.

Bisphosphonate conjugation for bone specific drug targeting

Bones provide essential functions and are sites of unique biochemistry and specialized cells, but can also be sites of disease. The treatment of bone disorders and neoplasia has presented difficulties in the past, and improved delivery of drugs to bone remains an important goal for achieving effective treatments. Drug targeting strategies have improved drug localization to bone by taking advantage of the high mineral concentration unique to the bone hydroxyapatite matrix, as well as tissue-specific cell types. The bisphosphonate molecule class binds specifically to hydroxyapatite and inhibits osteoclast resorption of bone, providing direct treatment for degenerative bone disorders, and as emerging evidence suggests, cancer. These bone-binding molecules also provide the opportunity to deliver other drugs specifically to bone by bisphosphonate conjugation. Bisphosphonate bone-targeted therapies have been successful in treatment of osteoporosis, primary and metastatic neoplasms of the bone, and other bone disorders, as well as refining bone imaging. In this review, we focus upon the use of bisphosphonate conjugates with antineoplastic agents, and overview bisphosphonate based imaging agents, nanoparticles, and other drugs. We also discuss linker design potential and the current state of bisphosphonate conjugate research progress. Ongoing investigations continue to expand the possibilities for bone-targeted therapeutics and for extending their reach into clinical practice.

Metformin inhibits the proliferation and metastasis of osteosarcoma cells by suppressing the phosphorylation of Akt

Metformin (Met) is a therapeutic agent for the treatment of type 2 diabetes mellitus. There is evidence that Met may reduce the risk of cancer in patients with type 2 diabetes mellitus by inhibiting tumor cell growth, prolonging the overall survival time in patients with various types of malignancy. However, the function and mechanism of Met have not been fully elucidated in osteosarcoma (OS). The present study evaluated the anti-proliferative effect of Met on MG63 and U2OS OS cells, identifying that it acted in a dose- and time-dependent manner. Met also inhibited OS cell migration and invasion, potentially by regulating the epithelial-mesenchymal transition in OS cells. Mechanistically, Met was demonstrated to partly exert these functions through the suppression of Akt phosphorylation, which was associated with increased phosphatase and tensin (PTEN) expression. Silencing PTEN prevented the Met-induced inhibition of the growth and metastasis of OS cells. As Met has anti-proliferative and anti-metastatic effects on OS cells it is a potential candidate, in combination with other chemotherapeutic agents, for use in the treatment of OS.

MicroRNA-192 inhibits the proliferation, migration and invasion of osteosarcoma cells and promotes apoptosis by targeting matrix metalloproteinase-11

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression during stem cell growth, proliferation and differentiation. miRNAs are also involved in the development and progression of a number of cancer types, including osteosarcoma (OS). miR-192 is significantly downregulated in various tumors, including lung, bladder and rectal cancer. miR-192 expression is associated with the migration and invasion of OS cells. However, the expression of miR-192 and its effects on the development of OS have not been reported. In the present study, the involvement of miR-192 and its molecular mechanisms in the development of OS was investigated. The results indicate that miR-192 expression was significantly downregulated in OS tissues compared with non-tumor tissues (P<0.05). Next, a miR-192 agomir was transfected into the OS cell line MG-63 to upregulate miR-192. The effects of miR-192 overexpression were then investigated by examining cell proliferation, apoptosis, migration and invasion. Matrix metalloproteinase (MMP)-11 belongs to a family of nine or more highly homologous Zn²⁺-endopeptidases. It was demonstrated that the mRNA and protein expression of MMP-11 were upregulated in OS tissues compared with non-tumor tissues (P<0.05). MMP-11 was predicted by TargetScan and miRanda as a miR-192 target, which was confirmed by western blotting and dual-luciferase assays. Finally, it was demonstrated that the overexpression of miR-192 was able to downregulate MMP-11 expression and reduce proliferation, migration and invasion, and promote apoptosis in OS cells. Together, these data indicate that miR-192 may be a tumor suppressor that inhibits the progression and invasion of OS by targeting MMP-11. Therefore, miR-192 may be useful for the diagnosis and treatment of OS.

MicroRNAs for osteosarcoma in the mouse: a meta-analysis

Osteosarcoma (OS) is the most common primary malignant bone carcinoma with high morbidity that happens mainly in children and young adults. As the key components of gene-regulatory networks, microRNAs (miRNAs) control many critical pathophysiological processes, including initiation and progression of cancers. The objective of this study is to summarize and evaluate the potential of miRNAs as targets for prevention and treatment of OS in mouse models, and to explore the methodological quality of current studies. We searched PubMed, Web of Science, Embase, Wan Fang Database, VIP Database, China Knowledge Resource Integrated Database, and Chinese BioMedical since their beginning date to 10 May 2016. Two reviewers separately screened the controlled studies, which estimate the effects of miRNAs on osteosarcoma in mice. A pair-wise analysis was performed. Thirty six studies with enough randomization were selected and included in the meta-analysis. We found that blocking oncogenic or restoring decreased miRNAs in cancer cells could significantly suppress the progression of OS in vivo, as assessed by tumor volume and tumor weight. This meta-analysis suggests that miRNAs are potential therapeutic targets for OS and correction of the altered expression of miRNAs significantly suppresses the progression of OS in mouse models, however, the overall methodological quality of studies included here was low, and more animal studies with the rigourous design must be carried out before a miRNA-based treatment could be translated from animal studies to clinical trials.

FKBP14 overexpression contributes to osteosarcoma carcinogenesis and indicates poor survival outcome

The FK506-binding protein 14 (FKBP14) is a subfamily of immunophilins, has been implicated in various biochemical processes. However, its effects on the primary malignant bone tumor, osteosarcoma, are unclear. Here, we reported that FKBP14 may be an oncogene as it overexpressed in osteosarcoma tissues and cell lines, and FKBP14 expression was correlated with metastases, recurrence, tumor maximum diameter and poor survival time. FKBP14 was associated with the biological pathways including cell cycle, apoptosis and metastasis. Furthermore, we detected FKBP14 knockdown induced cell cycle arrest, apoptosis, invasion and adhesion in vitro. FKBP14 knockdown decreased the protein levels of PCNA, CDK1 and CCNB1 that promotes cell cycle, increased Bax, caspase-3 and caspase-7 protein involved in promoting cell apoptosis, and increased KIF4A expression as well as decreased SMC4 and TMEM33 proteins that contribute to cell invasion and adhesion. In addition, FKBP14 knockdown also caused a significant inhibition in tumor growth in vivo. Then, we found that the protein RhoA was identified as a binding partner of FKBP14. Taken together, FKBP14 may act as an oncogene in osteosarcoma via suppressing apoptosis and promoting invasion and adhesion in osteosarcoma carcinogenesis. FKBP14 may be a prognostic factor and potential target for osteosarcoma treatment.

Evaluation of Apoptosis and Autophagy Inducing Potential of Berberis aristata, Azadirachta indica, and Their Synergistic Combinations in Parental and Resistant Human Osteosarcoma Cells

Cancer is a multifactorial disease and hence can be effectively overcome by a multi-constituently therapeutic strategy. Medicinal plant extracts represent a perfect example of such stratagem. However, minimal studies have been done till date that portray the effect of extraction techniques on the phyto-constituent profile of plant extracts and its impact on anticancer activity. In the present study, we have evaluated the anticancer potential of methanolic extracts of Berberis aristata root and Azadirachta indica seeds prepared by various extraction techniques in human osteosarcoma (HOS) cells. Soxhlation extract of B. aristata (BAM-SX) and sonication extract of A. indica (AIM-SO) were most effective in inducing apoptosis in parental drug sensitive, as well as resistant cell type developed by repeated drug exposure. Generation of reactive oxygen species and cell cycle arrest preceded caspase-mediated apoptosis in HOS cells. Interestingly, inhibition of autophagy enhanced cell death suggesting the cytoprotective role of autophagy. Combination studies of different methanolic extracts of BAM and AIM were performed, among which, the combination of BAM-SO and AIM-SO (BAAISO) was found to show synergism (IC₅₀ 10.27 µg/ml) followed by combination of BAM-MC and AIM-MC (BAAIMC) with respect to other combinations in the ratio of 1:1. BAAISO also showed synergism when it was added to cisplatin-resistant HOS cells (HCR). Chromatographic profiling of BAM-SX and AIM-SO by high performance thin layer chromatography resulted in identification of berberine (R_f 0.55), palmitine (R_f 0.50) in BAM-SX and azadirachtin A (R_f 0.36), azadirachtin B (R_f 0.56), nimbin (R_f 0.80), and nimbolide (R_f 0.43) in AIM-SO. The cytotoxic sensitivity obtained can be attributed to the above compounds. Our results highlight the importance of extraction technique and subsequent mechanism of action of multi-constituential B. aristata and A. indica against both sensitive and drug refractory HOS cells.

Long non-coding RNAs in osteosarcoma

Long non-coding RNAs (lncRNAs) with more than 200 nuleotides, have been explored to participate in various cancer types including osteosarcoma (OS), which is the most common kind of primary bone tumors with high morbidity in infants and adolescents. These oncogenic or tumor suppressive lncRNAs regulate OS pathogenesis, such as cell growth, proliferation, invasion, migration, metastasis and cell apoptosis, serve as independent prognostic biomarkers or play a significant role in multidrug resistance (MDR) in OS cells. In this review, we attempt to dissect the participation of lncRNAs in pathogenesis of OS and their potential clinical values, and also provide an outlook for viable biomarkers and therapeutic targets in OS.

Comparative proteomic investigation of metastatic and non-metastatic osteosarcoma cells of human and canine origin

Osteosarcoma is the most common bone cancer in dogs and people. In order to improve clinical outcomes, it is necessary to identify proteins that are differentially expressed by metastatic cells. Membrane bound proteins are responsible for multiple pro-metastatic functions. Therefore characterizing the differential expression of membranous proteins between metastatic and non-metastatic clonal variants will allow the discovery of druggable targets and consequently improve treatment methodology. The objective of this investigation was to systemically identify the membrane-associated proteomics of metastatic and non-metastatic variants of human and canine origin. Two clonal variants of divergent in vivo metastatic potential from human and canine origins were used. The plasma membranes were isolated and peptide fingerprinting was used to identify differentially expressed proteins. Selected proteins were further validated using western blotting, flow cytometry, confocal microscopy and immunohistochemistry. Over 500 proteins were identified for each cell line with nearly 40% of the proteins differentially regulated. Conserved between both species, metastatic variants demonstrated significant differences in expression of membrane proteins that are responsible for pro-metastatic functions. Additionally, CD147, CD44 and vimentin were validated using various biochemical techniques. Taken together, through a comparative proteomic approach we have identified several differentially expressed cell membrane proteins that will help in the development of future therapeutics.

Long non-coding RNAs for osteosarcoma in the mouse: a meta-analysis

Osteosarcoma, one of the most common primary bone malignances, is a leading cause of cancer death among children and adolescents. Recently, growing studies have found that long non-coding RNAs (lncRNAs) can interfere with the expression of various genes, and participate in the occurrence and development of malignancies. The purpose of this study is to evaluate the potential functions of lncRNAs as diagnostic biomarkers and therapeutic targets for osteosarcoma in mice, thus to direct the strict design for the future preclinical experiments and clinical trials. We systematically searched PubMed, Web of Science, Embase, China Knowledge Resource Integrated Database, VIP, Chinese BioMedical and Wan Fang Database from their initiation date to June 20, 2017. Two researchers independently screened the literatures and withdrew the data, which used the tumor volume and tumor weight as the outcome measures. A total of 10 studies were included, and the results of this meta-analysis revealed that lncRNAs could serve as the diagnostic biomarkers and therapeutic targets for osteosarcoma; and progression of osteosarcoma in mice could be inhibited via rescuing the abnormally expressed lncRNAs. It is necessary to carry out more rigorous basic experiments before lncRNAs can be further investigated in the clinical trials and used in future clinical practices.

Homeodomain-containing gene 10 inhibits cell apoptosis and promotes cell invasion and migration in osteosarcoma cell lines

Homeodomain-containing gene 10 (HOXC10) belongs to the homeobox family, which encodes a highly conserved family of transcription factors that plays an important role in morphogenesis in all multicellular organisms. Altered expressions of HOXC10 have been reported in several malignancies. This study was aimed to reveal the expression profile of HOXC10 in osteosarcoma and evaluated whether HOXC10 is a molecular target for cancer therapy. We found that HOXC10 was up-regulated in osteosarcoma tissues compared with bone cyst specimens from The Cancer Genome Atlas database. Osteosarcoma MG63 cells were infected with HOXC10 shRNA expressing vector, and 143B cells were infected with HOXC10 expressing vector. We found that reduced expression of HOXC10 markedly impaired the ability of proliferation, invasion, and migration, and promoted cell apoptosis in vitro and in vivo. Up-regulated expression of HOXC10 promoted the proliferation, invasion, and migration, and inhibited apoptosis of 143B cells. Additionally, HOXC10 regulated apoptosis and migration via modulating expression of Bax/Bcl-2, caspase-3, MMP-2/MMP-9, and E-cadherin in both MG63 and 143B cells and in vivo. These results indicated that HOXC10 might be a diagnostic marker for osteosarcoma and could be a potential molecular target for the therapy of osteosarcoma.

The dynamic role of autophagy and MAPK signaling in determining cell fate under cisplatin stress in osteosarcoma cells

Osteosarcoma (OS) is an aggressive bone malignancy commonly observed in children and adolescents. Sub-optimal therapy for years has irretrievably compromised the chances of OS patient survival; also, lack of extensive research on this rare disease has hindered therapeutic development. Cisplatin, a common anti-tumor drug, is currently an integral part of treatment regime for OS along with methotrexate and doxorubicin. However, toxicity issues associated with combination module impede OS therapy. Also, despite the proven benefits of cisplatin, acquisition of resistance remains a concern with cisplatin-based therapy. This prompted us to investigate the molecular effects of cisplatin exposure and changes associated with acquired resistance in OS cells. Cisplatin shock was found to activate MAPK signaling and autophagy in OS cells. An activation of JNK and autophagy acted as pro-survival strategy, while ERK1/2 triggered apoptotic signals upon cisplatin stress. A crosstalk between JNK and autophagy was observed. Maximal sensitivity to cisplatin was obtained with simultaneous inhibition of both autophagy and JNK pathway. Cisplatin resistant cells were further developed by repetitive drug exposure followed by clonal selection. The resistant cells showed an altered signaling circuitry upon cisplatin exposure. Our results provide valuable cues to possible molecular alterations that can be considered for development of improved therapeutic strategy against osteosarcoma.

Down regulation of human positive coactivator 4 suppress tumorigenesis and lung metastasis of osteosarcoma

Osteosarcoma is a kind of primary malignant bone tumor with the highest incidence and an extraordinarily poor prognosis and early pulmonary metastasis formation as a frequent occurrence. Transcriptional positive coactivator 4 (PC4) has multiple functions in DNA replication, transcription, repair and chromatin organization, even in tumorigenesis. However, the precise function of PC4 in osteosarcoma is still unclear and controversial. In this paper we found PC4 was upregulated in patient-derived osteosarcoma tissues compared to normal. Moreover, higher expression of PC4 was correlated with poorer overall survival and advanced clinicopathological tumor staging. Down regulation of PC4 in the highly metastatic osteosarcoma cells reduced the malignant behaviors in vitro and in vivo. Analyzing the downstream genes affected obviously by shPC4 with RNA sequencing, we found knocking down PC4 will inhibit the propensity for lung metastasis through transcriptional suppression of MMPs pathways. Taken together, PC4 may be an attractive therapeutic strategy for osteosarcoma, especially in preventing lung metastasis formation.

Biosynthesized Protein-Capped Silver Nanoparticles Induce ROS-Dependent Proapoptotic Signals and Prosurvival Autophagy in Cancer Cells

In recent years, the use of silver nanoparticles (AgNPs) in biomedical applications has shown an unprecedented boost along with simultaneous expansion of rapid, high-yielding, and sustainable AgNP synthesis methods that can deliver particles with well-defined characteristics. The present study demonstrates the potential of metal-tolerant soil fungal isolate Penicillium shearii AJP05 for the synthesis of protein-capped AgNPs. The particles were characterized using standard techniques, namely, UV-visible spectroscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The anticancer activity of the biosynthesized AgNPs was analyzed in two different cell types with varied origin, for example, epithelial (hepatoma) and mesenchymal (osteosarcoma). The biological NPs (bAgNPs) with fungal-derived outer protein coat were found to be more cytotoxic than bare bAgNPs or chemically synthesized AgNPs (cAgNPs). Elucidation of the molecular mechanism revealed that bAgNPs induce cytotoxicity through elevation of reactive oxygen species (ROS) levels and induction of apoptosis. Upregulation of autophagy and activation of JNK signaling were found to act as a prosurvival strategy upon bAgNP treatment, whereas ERK signaling served as a prodeath signal. Interestingly, inhibition of autophagy increased the production of ROS, resulting in enhanced cell death. Finally, bAgNPs were also found to sensitize cells with acquired resistance to cisplatin, providing valuable insights into the therapeutic potential of bAgNPs. To the best of our knowledge, this is the first study that provides a holistic idea about the molecular mechanisms behind the cytotoxic activity of protein-capped AgNPs synthesized using a metal-tolerant soil fungus.

Near-Infrared Light Responsive Folate Targeted Gold Nanorods for Combined Photothermal-Chemotherapy of Osteosarcoma

Folate-targeted gold nanorods (GNRs) are proposed as selective theranostic agents for osteosarcoma treatment. An amphiphilic polysaccharide based graft-copolymer (INU-LA-PEG-FA) and an amino derivative of the α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide functionalized with folic acid (PHEA-EDA-FA), have been synthesized to act as coating agents for GNRs. The obtained polymer-coated GNRs were characterized in terms of size, shape, zeta potential, chemical composition, and aqueous stability. They protected the anticancer drug nutlin-3 and were able to deliver it efficiently in different physiological media. The ability of the proposed systems to selectively kill tumor cells was tested on U2OS cancer cells expressing high levels of FRs and compared with human bronchial epithelial cells (16HBE) and human dermal fibroblasts (HDFa). The property of the nanosystems of efficiently controlling drug release upon NIR laser irradiation and of acting as an excellent hyperthermia agent as well as Two Photon Luminescence imaging contrast agents was demonstrated. The proposed folate-targeted GNRs have also been tested in terms of chemoterapeutic and thermoablation efficacy on tridimensional (3-D) osteosarcoma models.

Biomarkers of Osteosarcoma, Chondrosarcoma, and Ewing Sarcoma

Osteosarcoma is the most frequent malignant bone neoplasm, followed by chondrosarcoma and Ewing sarcoma. The diagnosis of bone neoplasms is generally made through histological evaluation of a biopsy. Clinical and radiological features are also important in aiding diagnosis and to complete the staging of bone cancer. In addition to these, there are several non-specific serological or specific molecular markers for bone neoplasms. In bone tumors, molecular markers increase the accuracy of the diagnosis and assist in subtyping bone tumors. Here, we review these markers and discuss their role in the diagnosis and prognosis of the three most frequent malignant bone neoplasms, namely osteosarcoma, chondrosarcoma, and Ewing sarcoma.

Identification of candidate drugs for the treatment of metastatic osteosarcoma through a subpathway analysis method

Osteosarcoma (OS) is the third most frequent type of cancer in adolescents and represents >56% of all bone tumors. In addition, metastatic OS frequently demonstrates resistance to conventional chemotherapy; thus, the development of novel therapeutic agents for the treatment of patients with metastatic OS is warranted. In the present study, the metabolic mechanisms underlying OS metastasis were investigated using a subpathway analysis method and lead to the identification of candidate drugs for the treatment of metastatic OS. Using the GSE14827 microarray dataset from the Gene Expression Omnibus database, 546 differentially expressed genes were identified between samples from patients with OS who did or did not develop metastatic OS. Furthermore, nine significantly enriched metabolic subpathways were identified, which may be involved in OS metastasis. Finally, using an integrated analysis of metastatic OS-associated subpathways and drug-affected subpathways, 98 small molecule drug candidates capable of targeting the metastatic OS-associated subpathways were identified. This method identified existing anti-cancer drugs, including semustine, in addition to predicting potential drugs, such as lansoprazole, for the treatment of metastatic OS. Transwell and wound healing assays demonstrated that lansoprazole reduced the invasiveness and migration of U2OS cells. These small molecule drug candidates identified through a bioinformatics approach may provide insights into novel therapy options for the treatment of patients with metastatic OS.

Osteosarcoma Overview

Osteosarcoma (OS) is the most common primary malignancy of bone and patients with metastatic disease or recurrences continue to have very poor outcomes. Unfortunately, little prognostic improvement has been generated from the last 20 years of research and a new perspective is warranted. OS is extremely heterogeneous in both its origins and manifestations. Although multiple associations have been made between the development of osteosarcoma and race, gender, age, various genomic alterations, and exposure situations among others, the etiology remains unclear and controversial. Noninvasive diagnostic methods include serum markers like alkaline phosphatase and a growing variety of imaging techniques including X-ray, computed tomography, magnetic resonance imaging, and positron emission as well as combinations thereof. Still, biopsy and microscopic examination are required to confirm the diagnosis and carry additional prognostic implications such as subtype classification and histological response to neoadjuvant chemotherapy. The current standard of care combines surgical and chemotherapeutic techniques, with a multitude of experimental biologics and small molecules currently in development and some in clinical trial phases. In this review, in addition to summarizing the current understanding of OS etiology, diagnostic methods, and the current standard of care, our group describes various experimental therapeutics and provides evidence to encourage a potential paradigm shift toward the introduction of immunomodulation, which may offer a more comprehensive approach to battling cancer pleomorphism.

miR-10b promotes invasion by targeting KLF4 in osteosarcoma cells

OBJECTIVE

Osteosarcoma is a common malignancy with high rate of metastasis. miR-10b has been reported to be expressed in many types of tumors abnormally and be associated with cancer carcinogenesis and progression. But the function of miR-10b in osteosarcoma is still unknown. So this study was aimed to investigate the role of miR-10b in osteosarcoma development.

METHODS

miR-10b expression in osteosarcoma tissues and osteosarcoma cells were detected using real time PCR. The effects of miR-10b on osteosarcoma cells proliferation, apoptosis, migration and invasion were detected using CCK-8 assay, flow cytometry, wound-healing assay and transwell assay, respectively. The relationship between miR-10b and KLF4 was evaluated using dual-luciferase assay, correlation analysis.

RESULTS

miR-10b was highly expressed in osteosarcoma tissues and osteosarcoma cells. Furthermore, inhibition of miR-10b in osteosarcoma cells depressed the cells proliferation, migration and invasion but promoted cells apoptosis. In addition, KLF4 was down-regulated by miR-10b and miR-10b expression was negatively related to KLF4 expression in osteosarcoma tissue, miR-10b participated in the process of osteosarcoma cells invasion by regulating KLF4 expression.

CONCLUSION

miR-10b is overexpressed in osteosarcoma and KLF4 is the direct target gene of miR-10b. Furthermore, miR-10b promotes osteosarcoma cells progression by downregulating KLF4 expression. These results suggest that miR-10b functions as an oncomiR and play an important role in osteosarcoma cellular processes at least partially through regulating KLF4; miR-10b may be a therapeutic target for osteosarcoma treatment.

TRIM59 is upregulated and promotes cell proliferation and migration in human osteosarcoma

Osteosarcoma is a prevalent type of cancer and has a high metastatic ability, particularly for metastasis to the lungs. Effective treatment strategies have improved, however, the detailed molecular mechanism underlying the onset of this malignancy remains to be fully elucidated. The current study investigated the role of the tripartite motif (TRIM) family protein TRIM59 in osteosarcoma growth and metastasis. It was identified that TRIM59 was overexpressed in clinical osteosarcoma tissues and cultured osteosarcoma cell lines. In addition, the MTT assay demonstrated that in U2OS and MG63 cells, knockdown of TRIM59 by specific siRNA inhibited proliferation, whereas overexpression of TRIM59 promoted cell proliferation. Furthermore, overexpression of TRIM59 significantly increased the U2OS cell migrative and invasive abilities in a Transwell chamber assay. In addition, TRIM59 was able to negatively regulate the protein levels of P53 without significantly affecting the mRNA levels in U2OS and MG63 cells. These data suggest the oncogenic abilities of TRIM59 in osteosarcoma, which promote osteosarcoma cell proliferation, migration and invasion.

CXCR4-targeted near-infrared imaging allows detection of orthotopic and metastatic human osteosarcoma in a mouse model

CXCR4 is expressed at primary and metastatic sites of osteosarcoma. We developed a novel CXCR4-targeted near-infrared (NIR) fluorescent imaging agent (referred to as CXCR4-IR-783). The binding to representative osteosarcoma cells (F5M2 and F4 for high- and low- CXCR4 expression) was examined. CXCR4-IR-783 fluorescence was also examined in a mouse xenograft model of human osteosarcoma using NIR fluorescence microscopy and a Kodak in-vivo multispectral system. Pulmonary metastases in mice bearing osteosarcoma xenografts were detected by micro CT, ¹⁸F-PET scan and NIR imaging scan. Briefly, the binding of CXCR4-IR-783 was significantly higher in F5M2 than in F4 cells. Intense NIR fluorescence signals were detected in osteosarcoma xenografts, with signal/background ratio at 4.87 in mice bearing the F5M2 cell. At 4 weeks after F5M2 cell inoculation, metastatic lesions in the lungs were detectable using CXCR4-IR-783 and micro-CT scan, but not with ¹⁸F-FDG PET scan. In conclusion, CXCR4-IR-783 is a promising tool for detection of high CXCR4-expressing osteosarcoma, and particularly for its metastatic lesions.

Mitogen-activated protein kinase 7 promotes cell proliferation, migration and invasion in SOSP-M human osteosarcoma cell line

PURPOSE

Osteosarcoma (OS) is the most common primary bone tumor and has low cure rates. Our study aimed to evaluate the roles of mitogen-activated protein kinase 7 (MAPK7) in cell proliferation, migration and invasion using the SOSP-M human OS cell line as an in vitro model.

METHODS

SOSP-M cells were transfected with PCDNA3.1-MAPK7 and siRNA-MAPK7 plasmids using Lipofectamine 2000. Quantitative real-time polymerase chain reaction (RT-PCR) was performed to determine the relative expression level of MAPK7 and Western blot analysis was carried out to determine the expression level of ERK5 protein. Then MTT, scratch wound healing and Matrigel transwell assays were used to investigate the roles of MAPK7 expression in the proliferation, migration and invasion, respectively, of SOSP-M cells in vitro.

RESULTS

RT-PCR analysis showed that the expression level of MAPK7 increased significantly after transfection with PCDNA3.1-MAPK7 plasmid compared with the blank group, while it decreased significantly after transfection with siRNA-MAPK7 plasmid. Similar results for ERK5 expression were obtained by Western blot analysis. In addition, the cell proliferation rate, cell migration rate and invasive cell number in the PCDNA3.1-MAPK7 transfection group increased significantly compared with the blank group, while they decreased significantly in the siRNA-MAPK7 transfection group.

CONCLUSIONS

Our results indicate that overexpression of MAPK7 in human OS cells could promote cell proliferation, migration and invasion, whereas knockdown of MAPK7 expression had the opposite effect. All the results suggest that MAPK7 may serve as a potent target for drug development.

Leukemia inhibitory factor promotes tumor growth and metastasis in human osteosarcoma via activating STAT3

The leukemia inhibitory factor (LIF) has been demonstrated to be an oncogene and participated in multiple procedures during the initiation and progression of many human malignancies. However, the role of LIF in osteosarcoma is still largely unknown. Here, we performed a series of in vitro and in vivo experiments to investigate the expression and biological functions of LIF in osteosarcoma. Compared to that in the non-cancerous tissues, LIF was significantly overexpressed in a panel of 68 osteosarcoma samples (p < 0.0001). Moreover, the overexpression of LIF was significantly correlated with advanced tumor stage, larger tumor size, and shorter overall survival. In addition, knockdown of LIF notably suppressed the proliferation and invasion of osteosarcoma via blocking the STAT3 signal pathway; in contrast, treatment with the recombinant LIF protein significantly promoted the growth and invasion of osteosarcoma through enhancing the phosphorylation of STAT3, which can be partially neutralized by the STAT3 inhibitor, HO-3867. In conclusion, we demonstrated that LIF was frequently overexpressed in osteosarcoma, which could promote the growth and invasion through activating the STAT3 pathway. Our findings proposed that LIF might be a potent therapeutic target for osteosarcoma.

Sunitinib malate (SU-11248) reduces tumour burden and lung metastasis in an intratibial human xenograft osteosarcoma mouse model

Osteosarcoma is a rare type of cancer that commonly occurs as a primary bone tumour in children and adolescents and is associated with a poor clinical outcome. Despite complex treatment protocols, including chemotherapy combined with surgical resection, the prognosis for patients with osteosarcoma and metastases remains poor and more effective therapies are required. In this study, we evaluated the therapeutic efficacy of sunitinib malate, a wide-spectrum tyrosine kinase inhibitor, in a preclinical mouse model of osteosarcoma. Sunitinib significantly inhibited proliferation, provoked apoptosis and induced G2/M cell cycle arrest in the human osteosarcoma cell lines SaOS-2 and 143B in vitro. Importantly, sunitinib treatment significantly reduced tumour burden, microvessel density and suppressed pulmonary metastasis in a 143B cell-derived intratibial osteosarcoma model in SCID mice. Sunitinib significantly decreased primary tumor tissue proliferation and reduced tumor vasculature. Our study indicates that sunitinib has potential for effective treatment of metastasizing osteosarcoma and provides the framework for future clinical trials with sunitinib alone or in combination with conventional and other novel therapeutics aiming at increased treatment efficacy and improved patient outcome.

Overexpression of Long Non-Coding RNA HOTAIR Promotes Tumor Growth and Metastasis in Human Osteosarcoma

Human osteosarcoma usually presented a high tendency to metastatic spread and caused poor outcomes, however, the underlying mechanism was still largely unknown. In the present study, using a series of in vitro experiments and an animal model, we investigated the roles of HOX antisense intergenic RNA (HOTAIR) during the proliferation and invasion of osteosarcoma. According with our results, HOTAIR was commonly overexpressed in osteosarcoma, which significantly correlated with advanced tumor stage, highly histological grade and poor prognosis. In vitro and in vivo experiments demonstrated that knockdown of HOTAIR could notably suppress cellular proliferation, inhibit invasion and decrease the secretion of MMP2 and MMP9 in osteosarcoma. Collectively, our results suggested that HOTAIR might be a potent therapeutic target for osteosarcoma.

Astrocyte elevated gene-1 (AEG-1) promotes osteosarcoma cell invasion through the JNK/c-Jun/MMP-2 pathway

Osteosarcoma is the most common primary malignant bone tumour in children and adolescents and is characterised by high malignant and metastatic potentials. However, the molecular mechanism underlying this invasiveness remains unclear. In this study, we determined that PD98059 and SP600125, the two mitogen-activated protein kinase (MAPK) family inhibitors, decreased the osteosarcoma cell U2OS-AEG-1 migration and invasion that was enhanced by astrocyte elevated gene-1 (AEG-1) in an in vitro wound-healing and Matrigel invasion assay independently of cell viability. These findings indicate that AEG-1 promoted osteosarcoma cell invasion is relevant to the MAPK pathways. The up-regulation of AEG-1 increased the levels of phosphor-c-Jun N-terminal kinase (JNK) and phosphor-c-Jun; however, there were no marked changes in the levels of phosphor-extracellular regulated kinase (ERK) 1/2 or phosphor-c-Fos due to the activation of AEG-1 in U2OS. SP600125 (a JNK inhibitor) decreased phosphor-c-Jun and MMP-2 in U2OS-AEG-1, while PD98059 (a ERK1/2 inhibitor) had no influence on the levels of phosphor-c-Jun or MMP-2 in U2OS-AEG-1. Further study revealed that the down-regulation of phosphor-c-Jun not only obviously decreased the MMP-2 protein level and the MMP-2 transcriptional activity that were up-regulated by AEG-1 in Western-blot and luciferase reporter assays, but also inhibited the migration and invasion abilities of the U2OS-AEG-1 cells, which suggests that AEG-1 mediated U2OS invasion at least partially via the JNK/c-Jun/MMP-2 pathway. Consistent with these observations, immunohistochemical (IHC) staining revealed that AEG-1 expression was associated with the protein levels of phosphor-c-Jun and MMP-2 in needle biopsy paraffin-embedded archival human osteosarcoma tissues. Taken together, our findings suggest that AEG-1 plays a crucial role in the aggressiveness of osteosarcoma via the JNK/c-Jun/MMP-2 pathway.

Overexpression of smad7 blocks primary tumor growth and lung metastasis development in osteosarcoma

PURPOSE

Osteosarcoma is the main malignant primary bone tumor in children and adolescents for whom the prognosis remains poor, especially when metastasis is present at diagnosis. Because transforming growth factor-β (TGFβ) has been shown to promote metastasis in many solid tumors, we investigated the effect of the natural TGFβ/Smad signaling inhibitor Smad7 and the TβRI inhibitor SD-208 on osteosarcoma behavior.

EXPERIMENTAL DESIGN

By using a mouse model of osteosarcoma induced by paratibial injection of cells, we assessed the impact of Smad7 overexpression or SD-208 on tumor growth, tumor microenvironment, bone remodeling, and metastasis development.

RESULTS

First, we demonstrated that TGFβ levels are higher in serum samples from patients with osteosarcoma compared with healthy volunteers and that TGFβ/Smad3 signaling pathway is activated in clinical samples. Second, we showed that Smad7 slows the growth of the primary tumor and increases mice survival. We furthermore demonstrated that Smad7 expression does not affect in vitro osteosarcoma cell proliferation but affects the microarchitectural parameters of bone. In addition, Smad7-osteosarcoma bone tumors expressed lower levels of osteolytic factors such as RANKL, suggesting that Smad7 overexpression affects the "vicious cycle" established between tumor cells and bone cells by its ability to decrease osteoclast activity. Finally, we showed that Smad7 overexpression in osteosarcoma cells and the treatment of mice with SD208 inhibit the development of lung metastasis.

CONCLUSION

Taken together, these results demonstrate that the inhibition of the TGFβ/Smad signaling pathway may be a promising therapeutic strategy against tumor progression of osteosarcoma, specifically against the development of lung metastasis.

High CD49f expression is associated with osteosarcoma tumor progression: a study using patient-derived primary cell cultures

Overall prognosis for osteosarcoma (OS) is poor despite aggressive treatment options. Limited access to primary tumors, technical challenges in processing OS tissues, and the lack of well-characterized primary cell cultures has hindered our ability to fully understand the properties of OS tumor initiation and progression. In this study, we have isolated and characterized cell cultures derived from four central high-grade human OS samples. Furthermore, we used the cell cultures to study the role of CD49f in OS progression. Recent studies have implicated CD49f in stemness and multipotency of both cancer stem cells and mesenchymal stem cells. Therefore, we investigated the role of CD49f in osteosarcomagenesis. First, single cell suspensions of tumor biopsies were subcultured and characterized for cell surface marker expression. Next, we characterized the growth and differentiation properties, sensitivity to chemotherapy drugs, and anchorage-independent growth. Xenograft assays showed that cell populations expressing CD49f(hi) /CD90(lo) cell phenotype produced an aggressive tumor. Multiple lines of evidence demonstrated that inhibiting CD49f decreased the tumor-forming ability. Furthermore, the CD49f(hi) /CD90(lo) cell population is generating more aggressive OS tumor growth and indicating this cell surface marker could be a potential candidate for the isolation of an aggressive cell type in OSs.

Understanding the role of Notch in osteosarcoma

The Notch pathway has been described as an oncogene in osteosarcoma, but the myriad functions of all the members of this complex signaling pathway, both in malignant cells and nonmalignant components of tumors, make it more difficult to define Notch as simply an oncogene or a tumor suppressor. The cell-autonomous behaviors caused by Notch pathway manipulation may vary between cell lines but can include changes in proliferation, migration, invasiveness, oxidative stress resistance, and expression of markers associated with stemness or tumor-initiating cells. Beyond these roles, Notch signaling also plays a vital role in regulating tumor angiogenesis and vasculogenesis, which are vital aspects of osteosarcoma growth and behavior in vivo. Further, osteosarcoma cells themselves express relatively low levels of Notch ligand, making it likely that nonmalignant cells, especially endothelial cells and pericytes, are the major source of Notch activation in osteosarcoma tumors in vivo and in patients. As a result, Notch pathway expression is not expected to be uniform across a tumor but likely to be highest in those areas immediately adjacent to blood vessels. Therapeutic targeting of the Notch pathway is likewise expected to be complicated. Most pharmacologic approaches thus far have focused on inhibition of gamma secretase, a protease of the presenilin complex. This enzyme, however, has numerous other target proteins that would be expected to affect osteosarcoma behavior, including CD44, the WNT/β-catenin pathway, and Her-4. In addition, Notch plays a vital role in tissue and organ homeostasis in numerous systems, and toxicities, especially GI intolerance, have limited the effectiveness of gamma secretase inhibitors. New approaches are in development, and the downstream targets of Notch pathway signaling also may turn out to be good targets for therapy. In summary, a full understanding of the complex functions of Notch in osteosarcoma is only now unfolding, and this deeper knowledge will help position the field to better utilize novel therapies as they are developed.

Review of the molecular pathogenesis of osteosarcoma

Treating the osteosarcoma (OSA) remains a challenge. Current strategies focus on the primary tumor and have limited efficacy for metastatic OSA. A better understanding of the OSA pathogenesis may provide a rational basis for innovative treatment strategies especially for metastases. The aim of this review is to give an overview of the molecular mechanisms of OSA tumorigenesis, OSA cell proliferation, apoptosis, migration, and chemotherapy resistance, and how improved understanding might contribute to designing a better treatment target for OSA.

Surface proteomic analysis of osteosarcoma identifies EPHA2 as receptor for targeted drug delivery

BACKGROUND

Osteosarcoma (OS) is the most common bone tumour in children and adolescents. Despite aggressive therapy regimens, treatment outcomes are unsatisfactory. Targeted delivery of drugs can provide higher effective doses at the site of the tumour, ultimately improving the efficacy of existing therapy. Identification of suitable receptors for drug targeting is an essential step in the design of targeted therapy for OS.

METHODS

We conducted a comparative analysis of the surface proteome of human OS cells and osteoblasts using cell surface biotinylation combined with nano-liquid chromatography - tandem mass spectrometry-based proteomics to identify surface proteins specifically upregulated on OS cells. This approach generated an extensive data set from which we selected a candidate to study for its suitability as receptor for targeted treatment delivery to OS. First, surface expression of the ephrin type-A receptor 2 (EPHA2) receptor was confirmed using FACS analysis. Ephrin type-A receptor 2 expression in human tumour tissue was tested using immunohistochemistry. Receptor targeting and internalisation studies were conducted to assess intracellular uptake of targeted modalities via EPHA2. Finally, tissue micro arrays containing cores of human OS tissue were stained using immunohistochemistry and EPHA2 staining was correlated to clinical outcome measures.

RESULTS

Using mass spectrometry, a total of 2841 proteins were identified of which 156 were surface proteins significantly upregulated on OS cells compared with human primary osteoblasts. Ephrin type-A receptor 2 was highly upregulated and the most abundant surface protein on OS cells. In addition, EPHA2 was expressed in a vast majority of human OS samples. Ephrin type-A receptor 2 effectively mediates internalisation of targeted adenoviral vectors into OS cells. Patients with EPHA2-positive tumours showed a trend toward inferior overall survival.

CONCLUSION

The results presented here suggest that the EPHA2 receptor can be considered an attractive candidate receptor for targeted delivery of therapeutics to OS.

Expression of c-FLIP in pulmonary metastases in osteosarcoma patients and human xenografts

OBJECTIVE(S)

We have previously shown that Fas expression inversely correlates with the metastatic potential of osteosarcoma (OS) to the lung. FasL is constitutively expressed in the lung microenvironment and eliminates Fas(+) OS cells leaving Fas(-) cells to form metastases. Absence of FasL in the lung epithelium or blocking the Fas-signaling pathway interfered with this clearance mechanism allowing Fas(+) cells to remain and form lung metastases. We also demonstrated that while the majority of patient OS lung metastases were Fas(-), 10-20% of the lesions contained Fas(+) cells, suggesting that these cells were not sensitive to FasL-induced apoptosis. The expression of c-FLIP, an inhibitor of the Fas pathway, has been associated with tumor development, progression, and resistance to chemotherapy. We therefore evaluated the expression of c-FLIP in OS patient tumor specimens and human xenograft lung metastases.

METHODS

OS patient tissues, which included both primary and metastatic lesions, were evaluated for the expression of c-FLIP. In addition, tumors from human OS xenografts were examined for c-FLIP expression.

RESULTS

c-FLIP expression was significantly higher in the lung metastases than in the primary tumors.

CONCLUSION(S)

c-FLIP may play an important role in the metastatic potential of OS to the lung. Inhibition of c-FLIP may be a future therapeutic target.

Targeting JNK-interacting-protein-1 (JIP1) sensitises osteosarcoma to doxorubicin

Osteosarcoma (OS) is the most common primary malignant bone tumour in children and adolescents. Despite aggressive therapy, survival outcomes remain unsatisfactory, especially for patients with metastatic disease or patients with a poor chemotherapy response. Chemoresistance contributes to treatment failure. To increase the efficacy of conventional chemotherapy, essential survival pathways should be targeted concomitantly. Here, we performed a loss-of-function siRNA screen of the human kinome in SaOS-2 cells to identify critical survival kinases after doxorubicin treatment. Gene silencing of JNK-interacting-protein-1 (JIP1) elicited the most potent sensitisation to doxorubicin. This candidate was further explored as potential target for chemosensitisation in OS. A panel of OS cell lines and human primary osteoblasts was examined for sensitisation to doxorubicin using small molecule JIP1-inhibitor BI-78D3. JIP1 expression and JIP1-inhibitor effects on JNK-signalling were investigated by Western blot analysis. JIP1 expression in human OS tumours was assessed by immunohistochemistry on tissue micro arrays. BI-78D3 blocked JNK-signalling and sensitised three out of four tested OS cell lines, but not healthy osteoblasts, to treatment with doxorubicin. Combination treatment increased the induction of apoptosis. JIP1 was found to be expressed in two-thirds of human primary OS tissue samples. Patients with JIP1 positive tumours showed a trend to inferior overall survival. Collectively, JIP1 appears a clinically relevant novel target in OS to enhance the efficacy of doxorubicin treatment by means of RNA interference or pharmacological inhibition.