Current treatment of osteosarcoma

Practical issues with high dose methotrexate therapy

Methotrexate (MTX) is an antifolate cytotoxic medication used to treat certain types of cancer and at lower doses for rheumatic diseases. MTX has many serious adverse effects, such as myelosuppression, hepatic, renal and pulmonary disorders. For safe and effective use of high dose methotrexate (HDMTX) certain precautions should be followed. We present this case study with short review to briefly summarize the important practical issues related to HDMTX therapy.

Overexpression of cytoplasmic β-catenin inhibits the metastasis of the murine osteosarcoma cell line LM8

Background

Previously, we found that treatment of LM8 murine osteosarcoma cells with genistein, an isoflavone found in soy, increased the cellular level of β-catenin and decreased its invasive and motile potential. The purpose of this study is to investigate whether the expression of β-catenin in LM8 cells is associated with metastatic potential in nude mice. To this end, we used untreated and genistein-treated LM8 cells.

Methods

LM8 cells were treated for 3 days with or without 50 μM genistein and harvested by trypsinization. Untreated (the control group) and genistein-treated (the genistein group) cells were subcutaneously inoculated into the backs of male nude mice. After 25 days of inoculation, the tumors, lungs, and livers were excised, fixed in 10% formalin, and embedded in paraffin. The sections of formalin-fixed, paraffin-embedded lungs and livers were stained with hematoxylin-eosin (H&E) to confirm the absence or presence of metastatic tumors. The expression of β-catenin within the primary tumor was immunohistochemically examined.

Results

All mice in the control group (n = 8) exhibited large primary tumors, while in the genistein group (n = 8), one mouse showed no tumor formation and the remaining seven mice exhibited smaller primary tumors compared with the control group. The tumor mass of the genistein group was 23% of that of the control group. In the control group, multiple metastatic tumors were found in the lung and/or liver and the metastatic incidence was 100% in the lung and 87.5% in the liver. Six of seven tumor-bearing mice in the genistein group developed no metastatic tumors in the lung or liver, and this group was termed the genistein/metastasis(-) subgroup. Positive β-catenin immunostaining was observed in the cytoplasm of tumor cells, and the β-catenin-labeling index was higher in the genistein/metastasis(-) subgroup than in the control group. The intensity of cytoplasmic β-catenin immunostaining was stronger in the genistein/metastasis(-) subgroup compared with the control group, and the β-catenin-labeling score was 1.9-times higher in the former subgroup than in the latter group.

Conclusions

Overexpression of cytoplasmic β-catenin in LM8 cells causes inhibition of the growth of primary tumors and loss of the metastatic potential to the lung and liver.

Exosome-formed synthetic microRNA-143 is transferred to osteosarcoma cells and inhibits their migration

MicroRNAs (miRNAs) have emerged as potential anticancer agents, but their clinical application is limited by the lack of an effective delivery system to tumors. Exosomes are small vesicles that play important roles in intercellular communication. Here, we show that synthetic miR-143 introduced into cells is released enveloped in exosomes and that the secreted exosome-formed miR-143 is transferred to osteosarcoma cells. The delivery of exosome-formed miR-143 significantly reduced the migration of osteosarcoma cells. The delivery efficiency of exosome-formed miR-143 was less than that achieved with lipofection, but the migratory potential of osteosarcoma cells was similarly inhibited after both strategies. Our results suggest that exosomes can deliver synthetic miR-143 and are a potentially efficient and functional delivery system.

Mifamurtide in metastatic and recurrent osteosarcoma: a patient access study with pharmacokinetic, pharmacodynamic, and safety assessments

PURPOSE

This non-randomized, patient-access protocol, assessed both safety and efficacy outcomes following liposomal muramyl-tripeptide-phosphatidylethanolamine (L-MTP-PE; mifamurtide) in patients with high-risk, recurrent and/or metastatic osteosarcoma.

METHODS

Patients received mifamurtide 2 mg/m(2) intravenously twice-weekly ×12 weeks, then weekly ×24 weeks with and without chemotherapy. Serum concentration-time profiles were collected. Adverse events within 24 hours of drug administration were classified as infusion-related adverse events (IRAE); other AEs and overall survival (OS) were assessed.

RESULTS

The study began therapy in January 2008; the last patient completed therapy in October 2012. Two hundred five patients were enrolled; median age was 16.0 years and 146/205 (71%) had active disease. Mifamurtide serum concentrations declined rapidly in the first 30 minutes post-infusion, then in a log-linear manner 2-6 hours post-dose; t1/2 was 2 hours. There were no readily apparent relationships between age and BSA-normalized clearance, half-life, or pharmacodynamic effects, supporting the dose of 2 mg/m(2) mifamurtide across the age range. Patients reported 3,679 IRAE after 7,482 mifamurtide infusions. These were very rarely grade 3 or 4 and most commonly included chills + fever or headache + fatigue symptom clusters. One- and 2-year OS was 71.7% and 45.9%. Patients with initial metastatic disease or progression approximated by within 9 months of diagnosis (N = 40) had similar 2-year OS (39.9%) as the entire cohort (45.9%)

CONCLUSIONS

Mifamurtide had a manageable safety profile; PK/PD of mifamurtide in this patient access study was consistent with prior studies. Two-year OS was 45.9%. A randomized clinical trial would be required to definitively determine impact on patient outcomes.

Osteosarcoma

Osteosarcoma is a malignant tumor that primarily affects the long bones but can also involve other bones in the body.  It has a bimodal distribution with peaks in the second decade of life and late adulthood.  This chapter will highlight the clinical presentation, diagnosis, and treatment of osteosarcoma.

Effects of naproxen on cell proliferation and genotoxicity in MG-63 osteosarcoma cell line

The purpose of this study was to determine the efficacy of naproxen, a nonsteroidal anti-inflammatory drug, on the MG-63 human osteosarcoma cell line. MG-63 cells were exposed to naproxen in a wide range of concentrations of 0.03, 0.05, 0.1, 0.42, 0.83, and 1.67 mg/ml for 72 h. The activity of naproxen was assessed by the following assays: cell morphology; 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method; terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay; comet assay; and acridine orange and monodansylcadaverine (MDC) staining. Naproxen exerted a significant inhibitory effect on MG-63 cell proliferation, in a concentration-dependent manner, in all treatment groups compared with untreated cells. An increase in frequency of DNA damage, apoptotic bodies, apoptotic cells, and autophagic vacuoles was observed in MG-63-treated cells. Although future studies are needed, these findings suggest that naproxen may lead to improvements in treatment of patients with osteosarcoma.

Mifamurtide for high-grade, resectable, nonmetastatic osteosarcoma following surgical resection: a cost-effectiveness analysis

OBJECTIVES

Mifamurtide is an immune macrophage stimulant that when added to standard chemotherapy has demonstrated survival benefit for newly diagnosed osteosarcoma. The objectives of this study were to investigate the cost-effectiveness of adding mifamurtide to standard three- or four-agent chemotherapy for high-grade, resectable, nonmetastatic osteosarcoma following surgical resection and the issues of obtaining robust cost-effectiveness estimates for ultra-orphan drugs, given the shortage of data.

METHODS

An economic evaluation was conducted from the perspective of the UK's National Health Service as part of the manufacturer's submission to the National Institute for Health and Care Excellence. The disease process was simplified to a transition through a series of health states, modeled by using a Markov approach. Data to inform the model were derived from patient-level data of Study INT-0133, published literature, and expert opinion. The final efficacy measure was life-years gained (LYG), and utilities were used to obtain quality-adjusted life-years (QALYs).

RESULTS

For a 60-year time frame and a discount rate of 3.5% for outcomes, patients receiving mifamurtide benefited from an average additional 1.57 years of life and 1.34 QALYs, compared with patients receiving chemotherapy alone, giving an incremental cost-effectiveness ratio (ICER) of £58,737 per LYG and £68,734 per QALY. Because treatment effects were both substantial in restoring health and sustained over a very long period, the National Institute for Health and Care Excellence changed its guidance to allow a discount of 1.5% for outcomes to be applied in these special circumstances. By using this discount factor, it was found that patients receiving mifamurtide had an average additional 2.58 years of life and 2.20 QALYs compared with patients receiving chemotherapy alone, resulting in an ICER of £35,765 per LYG and £41,933 per QALY.

CONCLUSION

Mifamurtide's ICER is cost-effective compared with that of other orphan and ultra-orphan drugs, for which prices and corresponding cost-effectiveness estimates are high.

Capsaicin induces apoptosis in MG63 human osteosarcoma cells via the caspase cascade and the antioxidant enzyme system

Osteosarcoma is the most common malignant bone tumor in children and adolescents. This aggressive cancer mostly occurs in the long bones. Therefore, novel therapeutic approaches, such as biological therapies and gene therapy, are required to efficiently treat osteosarcoma. Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) has been demonstrated to inhibit the growth of several types of cancer cells and a number of studies have shown that osteosarcoma may be vulnerable to biological therapies. However, little is known regarding the therapeutic effects of capsaicin on osteosarcoma. This study investigated the effects of capsaicin on MG63 human osteosarcoma cells, in addition to elucidating the regulatory signaling pathways underlying the effects of capsaicin, the caspase cascade and the antioxidant enzyme system. The MG63 cell line was treated with various concentrations of capsaicin. Cells were analyzed using MTT and flow cytometry, and the presence of DNA fragmentation was evaluated using TUNEL assay. Results showed capsaicin induced apoptosis in MG63 cells. Thus, capsaicin exhibited an anticancer effect in osteosarcoma cells.

MicroRNAs in osteosarcoma: diagnostic and therapeutic aspects

MicroRNAs (miRNAs) are small RNA molecules, which can interfere with the expression of several genes and act as gene regulator. miRNAs have been proved as a successful diagnostic and therapeutic tool in several cancers. In this review, the differential expression of miRNAs in osteosarcoma and their possibility to be used as diagnostic and therapeutic tools have been discussed. Osteosarcoma is the most common primary bone tumor that mainly affects children and adolescents. The current treatment of osteosarcoma remains difficult, and osteosarcoma causes many deaths because of its complex pathogenesis and resistance to conventional treatments. Several studies demonstrated that the differential expression patterns of miRNAs are a promising tool for the diagnosis and treatment of osteosarcoma. Although some aspect of the mechanism of action of miRNAs in controlling osteosarcoma has been identified (e.g., targeting the Notch signaling pathway), it is far beyond to the clear understanding of miRNA targets in osteosarcoma. Identification of the specific target of miRNAs may aid molecular targets for drug development and future relief of osteosarcoma.

Proteomics and NF-κB: an update

The transcription factor NF-κB was discovered in 1986 and since then has been extensively studied in relation to cancer research and inflammatory or autoimmune diseases due to its important roles in the regulation of apoptosis and inflammation as well as innate and adaptive immunity. Although much is known about NF-κB signaling, novel NF-κB functions in different diseases are still being uncovered, together with its target proteins, interaction partners and regulators of its activation cascade. Proteomic approaches are particularly suited to the discovery of new proteins involved in distinct signal transduction cascades. This review provides an update on and extension of a recent review that summarized a number of proteomic approaches to NF-κB signaling. The studies discussed here utilized innovative techniques and offer several new hypotheses on the role of NF-κB in physiological and pathophysiological processes, which open new avenues for research on NF-κB in the future.

Understanding the Biology of Bone Sarcoma from Early Initiating Events through Late Events in Metastasis and Disease Progression

The two most common primary bone malignancies, osteosarcoma (OS), and Ewing sarcoma (ES), are both aggressive, highly metastatic cancers that most often strike teens, though both can be found in younger children and adults. Despite distinct origins and pathogenesis, both diseases share several mechanisms of progression and metastasis, including neovascularization, invasion, anoikis resistance, chemoresistance, and evasion of the immune response. Some of these processes are well-studies in more common carcinoma models, and the observation from adult diseases may be readily applied to pediatric bone sarcomas. Neovascularization, which includes angiogenesis and vasculogenesis, is a clear example of a process that is likely to be similar between carcinomas and sarcomas, since the responding cells are the same in each case. Chemoresistance mechanisms also may be similar between other cancers and the bone sarcomas. Since OS and ES are mesenchymal in origin, the process of epithelial-to-mesenchymal transition is largely absent in bone sarcomas, necessitating different approaches to study progression and metastasis in these diseases. One process that is less well-studied in bone sarcomas is dormancy, which allows micrometastatic disease to remain viable but not growing in distant sites – typically the lungs – for months or years before renewing growth to become overt metastatic disease. By understanding the basic biology of these processes, novel therapeutic strategies may be developed that could improve survival in children with OS or ES.

EMT transcription factors: implication in osteosarcoma

The primary malignant bone tumor, osteosarcoma, is a deadly disorder. Its etiology is complex, and treatment is mostly obscure. The transcription factors (TFs) involved in epithelial to mesenchymal transition (EMT) have significant role in osteosarcoma. A number of evidence suggests that overexpression of EMT-TFs, such as Twist, Snails and Zebs, is involved in complex pathogenesis of osteosarcoma. Recent research studies have showed some extent of promise in osteosarcoma treatment by targeting these EMT-TFs. However, success in research on osteosarcoma-EMT-TFs axis is just in primary stage, and a long way to go. Targeting Twist, Snail or Zeb by specific molecules or chemotherapeutic agents may provide a new dimension in osteosarcoma treatment by controlling metastasis.

The overexpression of BAMBI and its involvement in the growth and invasion of human osteosarcoma cells

The pseudoreceptor BAMBI (bone morphogenetic protein and activin membrane-bound inhibitor), formerly known as NMA, is an inhibitor of the TGF-β signaling pathway. BAMBI exhibits structural homology to TGF-βRI but lacks an intracellular kinase domain. In most of the high-grade carcinomas, the degree of BAMBI expression is abnormally increased, which leads to the proliferation and metastasis of tumor cells. Recent studies have reported that BAMBI is involved in the Wnt-β-catenin pathway that regulates the proliferation and metastasis of tumor cells. However, little is known about the role of BAMBI and β-catenin in human osteosarcoma. Given the above background, we examined the role of BAMBI in the pathophysiology of osteosarcoma. Using immunohistochemical staining and western blot analysis, the degree of the expression of BAMBI and β-catenin was significantly higher in osteosarcoma specimens compared with normal tissues. With the overexpression of BAMBI, mediated by adenovirus, the degree of invasion and migration was significantly increased and the proliferation of U2-OS osteosarcoma cells was stimulated. Transwell analysis showed that BAMBI increased the invasion of osteosarcoma cells and upregulated the secretion of matrix metalloproteinases (MMPs), which was demonstrated by gelatin zymography. Fluorescence-activated cell sorting (FACS) analysis showed a significant arrest in cell cycle progression at G0/G1 in osteosarcoma cells transfected with siRNA targeting BAMBI. With the overexpression of BAMBI, mediated by the adenovirus, however, there was a decrease in the number of cells at G0/G1. Consistent with the findings that cell growth was increased, BAMBI promoted the transition from G0/G1 to G2/M in the osteosarcoma cells. Our results suggest that BAMBI plays a key role in the pathogenesis and progression of osteosarcoma by regulating the expression of β-catenin and other signaling molecules via the pathways involved in the regulation of the cell cycle. This relationship between BAMBI and its involvement in the regulation of the cell cycle would provide a possibility that the BAMBI may be a new target for gene therapy.

Gene delivery in a mouse xenograft of a retargeted retrovirus to a solid 143B osteosarcoma

BACKGROUND

Osteosarcomas are the most common primary bone malignancies found in children and adolescents. An optimized system was developed for efficient retroviral gene delivery into solid 143B osteosarcoma tumors in mice using a retargeted Env. In these studies, the viral Env CP was isolated from an in vitro screen of a library of feline leukemia virus Env randomized in the receptor-binding domain and maintained high titer on human 143B osteosarcoma cell line.

FINDINGS

The vector developed to express the random Env libraries encoded the drug selectable marker neo. To adapt this for studies in live animals, the murine based vector was modified to express the luciferase gene. The bicistronic vector developed expressed both the CP Env and luciferase in the presence of either the MPMV CTE or a WPRE element. Virus bearing the CP FeLV Env variant maintained high titers after concentration allowing for direct visualization of delivery of the luciferase gene in subcutaneous 143B osteosarcoma tumors.

CONCLUSION

This system serves as a proof-of-concept for the use of novel FeLV Env pseudotyped MLV particles for in vivo gene delivery. Gene delivery and expression of lucerifase from viral particles bearing the CP Env was readily detected in live mice after a single round of intratumor injection.

Reoxygenation using a novel CO2 therapy decreases the metastatic potential of osteosarcoma cells

Osteosarcoma is the most common primary solid malignant bone tumor. Despite substantial improvements in surgery and chemotherapy, metastasis remains a major cause of fatal outcomes, and the molecular mechanisms of metastasis are still poorly understood. Hypoxia, which is common in malignant tumors including osteosarcoma, increases expressions of hypoxia inducible factor (HIF)-1α, matrix metalloproteinase (MMP)-2 and MMP-9, and can induce invasiveness. As we previously showed a novel transcutaneous CO2 application to decrease HIF-1α expression and induce apoptosis in malignant fibrous histiocytoma, we hypothesize that transcutaneous CO2 application could suppress metastatic potential of osteosarcoma by improving hypoxic conditions. Here, we examined the effects of transcutaneous CO2 application on apoptosis, and development of pulmonary metastasis using a highly metastatic osteosarcoma cell line, LM8. Transcutaneous CO2 application significantly decreased tumor growth and pulmonary metastasis in LM8 cells. Apoptotic activity increased, and intratumoral hypoxia was improved with decreased expressions of HIF-1α, MMP-2 and MMP-9, significantly, in the CO2-treated tumors. In conclusion, we found that transcutaneous CO2 application can induce tumor cell apoptosis and might suppress pulmonary metastasis by improvement of hypoxic conditions with decreased expressions of HIF-1α and MMPs in highly metastatic osteosarcoma cell. These findings strongly indicate that this novel transcutaneous CO2 therapy could be a therapeutic breakthrough for osteosarcoma patients.

Metastatic osteosarcoma to the stomach and ascending colon in a pediatric patient causing gastrointestinal hemorrhage

Osteosarcoma metastasis to the gastrointestinal tract is a rare phenomenon (Horiuchi A, Watanabe Y, Yoshida M, et al.: Metastatic osteosarcoma in the jejunum with intussusception: report of a case. Surg Today 2007;37:440-2). Gastrointestinal metastases may cause intussusception, bowel obstruction, or hemorrhage (Horiuchi A, Watanabe Y, Yoshida M, et al.: Metastatic osteosarcoma in the jejunum with intussusception: report of a case. Surg Today 2007;37:440-2; Chondramohan K, Somanathan T, Kusamakumary P: Metastatic osteosarcoma causing intussusception. J Pediatr Surg 2003;38(E44):1-3; Hung GY, Chiou TJ, Hsieh YL, et al.: Intestinal metastasis causing intussusception in a patient treated for osteosarcoma with history of multiple metastases: a case report. Jpn J Clin Oncol 2001;31:165-167). We report a case of a 17 year old male with osteosarcoma metastatic to the stomach and ascending colon, causing significant chronic gastrointestinal hemorrhage. Surgical resection was performed due to persistent, symptomatic anemia. The patient is free of recurrent hemorrhage at 24months after metastectomy. Resection of gastrointestinal metastases of osteosarcoma offers good palliation of chronic hemorrhage related to these lesions.

The Current and Future Therapies for Human Osteosarcoma

Osteosarcoma (OS) is the most common non-hematologic malignant tumor of bone in adults and children. As sarcomas are more common in adolescents and young adults than most other forms of cancer, there are a significant number of years of life lost secondary to these malignancies. OS is associated with a poor prognosis secondary to a high grade at presentation, resistance to chemotherapy and a propensity to metastasize to the lungs. Current OS management involves both chemotherapy and surgery. The incorporation of cytotoxic chemotherapy into therapeutic regimens escalated cure rates from <20% to current levels of 65-75%. Furthermore, limb-salvage surgery is now offered to the majority of OS patients. Despite advances in chemotherapy and surgical techniques over the past three decades, there has been stagnation in patient survival outcome improvement, especially in patients with metastatic OS. Thus, there is a critical need to identify novel and directed therapy for OS. Several Phase I trials for sarcoma therapies currently ongoing or recently completed have shown objective responses in OS. Novel drug delivery mechanisms are currently under phase II and III clinical trials. Furthermore, there is an abundance of preclinical research which holds great promise in the development of future OS-directed therapeutics. Our continuously improving knowledge of the molecular and cell-signaling pathways involved in OS will translate into more effective therapies for OS and ultimately improved patient survival. The present review will provide an overview of current therapies, ongoing clinical trials and therapeutic targets under investigation for OS.

Multiple receptor tyrosine kinases promote the in vitro phenotype of metastatic human osteosarcoma cell lines

The survival rate for osteosarcoma patients with localized disease is 70% and only 25% for patients with metastases. Therefore, novel therapeutic and prognostic tools are needed. In this study, extensive screening and validation strategies identified Axl, EphB2, FGFR2, IGF-1R and Ret as specific receptor tyrosine kinases (RTKs) that are activated and promote the in vitro phenotype of two genetically different metastatic osteosarcoma cell lines. Initial phosphoproteomic screening identified twelve RTKs that were phosphorylated in 143B and/or LM7 metastatic human osteosarcoma cells. A small interfering RNA (siRNA) screen demonstrated that siRNA pools targeting ten of the twelve RTKS inhibited the in vitro phenotype of one or both cell lines. To validate the results, we individually tested the four siRNA duplexes that comprised each of the effective siRNA pools from the initial screen. The pattern of phenotype inhibition replicated the pattern of mRNA knockdown by the individual duplexes for seven of the ten RTKs, indicating the effects are consistent with on-target silencing. Five of those seven RTKs were further validated using independent approaches including neutralizing antibodies (IGF-1R), antisense-mediated knockdown (EphB2, FGFR2, and Ret) or small molecule inhibitors (Axl), indicating that those specific RTKs promote the in vitro behavior of metastatic osteosarcoma cell lines and are potential therapeutic targets for osteosarcoma. Immunohistochemistry demonstrated that Axl is frequently activated in osteosarcoma patient biopsy samples, further supporting our screening and validation methods to identify RTKs that may be valuable targets for novel therapies for osteosarcoma patients.

The glycogen synthase kinase-3β/nuclear factor-kappa B pathway is involved in cinobufagin-induced apoptosis in cultured osteosarcoma cells

Cinobufagin, a major component of cinobufacini (huachansu), is an important cardenolidal steroid. Several studies have suggested that cinobufagin has potent anti-cancer effects. The present study examines the apoptosis-inducing activity and the underlying mechanism of action of cinobufagin in osteosarcoma (OS) cells. Our results showed that cinobufagin potently inhibited the proliferation of U2OS, MG63 and SaOS-2 cells. Significant increases in G2/M cell-cycle arrest and apoptosis in OS cells were also observed. The expression levels of several apoptotic proteins were assessed after cinobufagin treatment in U2OS cells. Among them, xIAP, cIAP-1, survivin and Bcl-2 levels decreased remarkably, while the levels of Bax and cleaved-PARP increased. Furthermore, we validated the inhibition of GSK-3β/NF-κB signaling following cinobufagin treatment. Western blots showed a decrease in nuclear p65 protein expression after exposure to different concentrations of cinobufagin, while the phosphorylation of GSK-3β was simultaneously increased. Transduction with constitutively active forms of GSK-3β could protect against the downregulation of p65 and upregulation of cleaved-PARP that are induced by cinobufagin treatment. However, combined treatment with cinobufagin and SB216367 resulted in a significant reduction in p65 and an increase in cleaved-PARP in U2OS cells. Altogether, these results show that cinobufagin is a promising agent for the treatment of OS. These studies are the first to reveal the involvement of the GSK-3β/NF-κB pathway in cinobufagin-induced apoptosis.

Critical role of heat shock protein 27 in bufalin-induced apoptosis in human osteosarcomas: a proteomic-based research

Bufalin is the primary component of the traditional Chinese herb "Chan Su". Evidence suggests that this compound possesses potent anti-tumor activities, although the exact molecular mechanism(s) is unknown. Our previous study showed that bufalin inhibited growth of human osteosarcoma cell lines U2OS and U2OS/MTX300 in culture. Therefore, this study aims to further clarify the in vitro and in vivo anti-osteosarcoma effects of bufalin and its molecular mechanism of action. We found bufalin inhibited both methotrexate (MTX) sensitive and resistant human osteosarcoma cell growth and induced G2/M arrest and apoptosis. Using a comparative proteomics approach, 24 differentially expressed proteins following bufalin treatment were identified. In particular, the level of an anti-apoptotic protein, heat shock protein 27 (Hsp27), decreased remarkably. The down-regulation of Hsp27 and alterations of its partner signaling molecules (the decrease in p-Akt, nuclear NF-κB p65, and co-immunoprecipitated cytochrome c/Hsp27) were validated. Hsp27 over-expression protected against bufalin-induced apoptosis, reversed the dephosphorylation of Akt and preserved the level of nuclear NF-κB p65 and co-immunoprecipitated Hsp27/cytochrome c. Moreover, bufalin inhibited MTX-resistant osteosarcoma xenograft growth, and a down-regulation of Hsp27 in vivo was observed. Taken together, bufalin exerted potent anti-osteosarcoma effects in vitro and in vivo, even in MTX resistant osteosarcoma cells. The down-regulation of Hsp27 played a critical role in bufalin-induced apoptosis in osteosarcoma cells. Bufalin may have merit to be a potential chemotherapeutic agent for osteosarcoma, particularly in MTX-resistant groups.

Genistein inhibits cell invasion and motility by inducing cell differentiation in murine osteosarcoma cell line LM8

Background

One of the problems associated with osteosarcoma is the frequent formation of micrometastases in the lung prior to diagnosis because the development of metastatic lesions often causes a fatal outcome. Therefore, the prevention of pulmonary metastases during the early stage of tumor development is critical for the improvement of the prognosis of osteosarcoma patients. In Japan, soy is consumed in a wide variety of forms, such as miso soup and soy sauce. The purpose of this study is to investigate the effect of genistein, an isoflavone found in soy, on the invasive and motile potential of osteosarcoma cells.

Methods

LM8 cells were treated for 3 days with various concentrations of genistein. The effect of genistein on cell proliferation was determined by DNA measurement in the cultures and 5-bromo-2’-deoxyuridine (BrdU) incorporation study. The assays of cell invasion and motility were performed using the cell culture inserts with either matrigel-coated membranes or uncoated membranes in the invasion chambers. The expression and secretion of MMP-2 were determined by immunohistochemistry and gelatin zymography. The subcellular localization and cellular level of β-catenin were determined by immunofluorescence and Western blot. For examining cell morphology, the ethanol-fixed cells were stained with hematoxylin-eosin (H&E). The expression of osteocalcin mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR).

Results

Genistein dose-dependently inhibits cell proliferation. Genistein-treated cells were less invasive and less motile than untreated cells. The expression and secretion of MMP-2 were lower in the genistein-treated cultures than in the untreated cultures. β-Catenin in untreated cells was located in the cytoplasm and/or nucleus, while in genistein-treated cells it was translocated near to the plasma membrane. The level of β-catenin was higher in genistein-treated cells than in untreated cells. Treatment of LM8 cells with genistein induced morphological changes, markedly decreased the formation of multilayer masses of cells, and markedly increased the expression of osteocalcin mRNA.

Conclusions

Genistein decreased invasive and motile potential by inducing cell differentiation in LM8 cells. Genistein may be useful as an anti-metastatic drug for osteosarcoma through its differentiation-inducing effects.

MDM2 inhibitor Nutlin-3a suppresses proliferation and promotes apoptosis in osteosarcoma cells

Restoring p53 activity by inhibiting the interaction between p53 and the mouse double minutes clone 2 (MDM2) offers an attractive approach to cancer therapy. Nutlin-3a is a small-molecule inhibitor that inhibits MDM2 binding to p53 and subsequent p53-dependent DNA damage signaling. In this study, we determined the efficacy of Nutlin-3a in inducing p53-mediated cell death in osteosarcoma (OS) cell lines both in vivo and in vitro. Targeted disruption of the p53-MDM2 interaction by Nutlin-3a stabilizes p53 and selectively activates the p53 pathway only in OS cells with wild-type p53, resulting in a pronounced anti-proliferative and cytotoxic effect due to G1 cell cycle arrest and apoptosis both in vitro and in vivo. p53 dependence of these alternative outcomes of Nutlin-3a treatment was shown by the abrogation of these effects when p53 was knocked-down by small interfering RNA. These data suggest that the disruption of p53-MDM2 interaction by Nutlin-3a might be beneficial for OS patients with MDM2 amplification and wt p53 status.

A population pharmacokinetic/pharmacodynamic model of methotrexate and mucositis scores in osteosarcoma

Methotrexate, when used in high doses (12 g/m²) in the treatment of osteosarcoma, shows wide between-subject variability (BSV) in its pharmacokinetics. High-dose methotrexate is associated with severe toxicity; therefore, therapeutic drug monitoring (TDM) is carried out to guide rescue therapy and monitor for nephrotoxicity. Mucositis is a commonly encountered dose-limiting toxicity that often leads to delays in subsequent courses of chemotherapy. This, in turn, results in a reduction in the dosing intensity, which is essential in the treatment of osteosarcoma. The aims of this study were to develop a population pharmacokinetic (PK) model from TDM using physiologically relevant covariates and to investigate the correlation between mucositis scores and methotrexate pharmacokinetics. In total, 46 osteosarcoma patients (30 men and 16 women; age, 4-51 years) were recruited, and blood samples were collected for routine TDM once every 24 hours. Mucositis scores, graded according to the National Cancer Institute Common Toxicity Criteria, were recorded for 28 of the patients (18 men and 10 women; age, 8-51 years) predose and postdose. A population PK model was developed in NONMEM VI. A 2-compartment PK model was chosen, and clearance (CL) was divided into filtration and secretion/metabolism components. All parameters were scaled with body weight, and, in addition, total CL was scaled with age- and sex-adjusted serum creatinine. Between-subject variability was modeled for all parameters, and between-occasion variability was included in CL. For a typical 70 kg man of 18 years or older, the parameter estimates for the final model were CL(filt) = 2.69 L/h/70 kg, CL(sec) = 10.9 L/h/70 kg, V₁ = 74.3 L/70 kg, Q = 0.110 L/h/70 kg, and V₂ = 4.10 L/70 kg. Sequential pharmacodynamic modeling consisted of mucositis scores as 5-point ordered categorical data. A significant linear relationship between individual area under the curve (AUC) and mucositis score probability was found, and the probability of having mucositis score ≥ 1 increased with increasing AUC and was almost 50% at the average cumulative AUC after 2 consecutive methotrexate doses.

MicroRNA Involvement in Osteosarcoma

Osteosarcoma (OS) is the most common primary malignant bone tumor, usually arising in the long bones of adolescents and young adults. While our knowledge of the molecular pathogenesis of OS has increased in recent years, we are still far from a comprehensive understanding of the molecular mechanisms of the disease, such as its tumorigenesis, specific mediators of disease progression, occurrence of chemoresistance, and development of metastasis. After the recent discovery of microRNAs (miRNAs), their critical roles in molecular biological processes have been of great interest in the cancer research field, including research on sarcomas. MiRNAs are highly conserved noncoding RNAs which play important roles as oncogenic or suppressive genes to simultaneously regulate multiple targets. Recent genome-wide screening using miRNA expression profiles has identified specific miRNA expression patterns that are associated with the biological and clinical properties of cancers. Additionally, miRNAs and their target genes or proteins can be potential novel biomarkers or therapeutic targets for cancer. However, there are several challenges that must be addressed in order to translate miRNA-based therapeutics to the clinical setting. In this review, we summarize the current understanding of the roles that miRNAs play in OS, and highlight their potential as biomarkers or therapeutic targets.

S100A7 promotes the migration and invasion of osteosarcoma cells via the receptor for advanced glycation end products

Osteosarcoma is the most common malignant tumor of bone in childhood and adolescence. Despite intensive research for new therapies, the outcome in patients with metastasis remains extremely poor. S100 proteins are involved in the proliferation, cell cycle progression and metastasis of numerous malignant tumors, including osteosarcoma. In the present study, we identified S100A7 as a candidate to promote the migration of osteosarcoma cells. S100A7 promoted the migration and invasion of osteosarcoma cells as assayed in vitro. An in vitro pull-down assay revealed the binding of the recombinant S100A7 protein with its putative receptor, the receptor for advanced glycation end products (RAGE). The downregulation of RAGE by a specific siRNA markedly suppressed the migration and invasion of osteosarcoma cells. Furthermore, the matrix metalloproteinase activity of osteosarcoma cells was enhanced by S100A7 and suppressed by the downregulation of RAGE. These results indicate that S100A7 promotes the migration and invasion of osteosarcoma cells through RAGE. The S100A7-RAGE axis may thus be a new target for preventing the invasion and/or metastasis of osteosarcoma.

High dose methotrexate chemotherapy: pharmacokinetics, folate and toxicity in osteosarcoma patients

AIMS

To investigate the relationships between pretreatment folate concentrations, MTX pharmacokinetics and acute toxicities following high dose methotrexate (HD MTX) therapy.

METHODS

MTX and its major extracellular metabolite 7-OH-MTX were measured in eight serum samples per HD MTX cycle in 65 consecutive osteosarcoma patients (288 cycles) and AUC (area under the blood concentration-time curve) was calculated. Pretreatment concentrations of folate in serum (S) and erythrocytes (ER) were determined. Hepatic, renal and haematological toxicities, assessed by routine laboratory parameters, as well as mucositis were graded according to National Cancer Institute Common Terminology Criteria for adverse events (CTCAE v.3.0). Dermatitis and pleuritis were reported as occurred or not.

RESULTS

S- and ER-folate pretreatment concentrations increased significantly with increasing number of HD MTX cycles (P < 0.001). ER-folate pretreatment concentrations were higher among males (median 610 nmol l⁻¹, 95% CI 550, 680) compared with females (median 465 nmol l⁻¹, 95% CI 430, 520, P < 0.001), but showed no correlation with MTX or 7-OH-MTX pharmacokinetics. We found correlations between alanine aminotransferase peak concentration (ALAT(max) ) and clearance of MTX (P < 0.001), gender (P < 0.001), age (P < 0.001) and 7-OH-MTX concentrations (P < 0.001), the latter being the main factor influencing ALAT(max) .

CONCLUSION

Our results suggest that 7-OH-MTX is involved in the development of HD MTX hepatic toxicity and that young female patients are most affected.

Overexpression of ZEB1 relates to metastasis and invasion in osteosarcoma

BACKGROUND

This study aimed to investigate the expression of ZEB1 in osteosarcoma tissues and to discuss the relationship between ZEB1 expression and osteosarcoma metastasis.

METHODS

Using RT-PCR and Western blotting, the mRNA and protein expressions of ZEB1 in the osteosarcoma and normal bone tissues were detected. Using the RNA interference technique, the expression of ZEB1 in the human osteosarcoma MG-63 cell line was downregulated, and the changes in the invasion of MG-63 cells were examined.

RESULTS

The positive mRNA expression rate of ZEB1 in the osteosarcoma tissues was significantly higher than that in normal bone tissue (P < 0.05). The protein expression level of ZEB1 in the sarcoma tissues from patients with positive lung metastasis was significantly higher than that from patients without lung metastasis (P < 0.05). After the transfection of ZEB1 siRNA into the MG-63 cells, the protein expression of ZEB1 was significantly reduced (P < 0.05), and the number of cells that passed through the Transwell chamber was significantly lower than that in the non-transfected control group as well as the transfected control group (P < 0.05).

CONCLUSIONS

The overexpression of ZEB1 in osteosarcoma may be related to the carcinogenesis and development as well as metastasis and invasion 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.

High-throughput genotyping in osteosarcoma identifies multiple mutations in phosphoinositide-3-kinase and other oncogenes

BACKGROUND

The identification of new genes that are mutated in osteosarcomas is critical to developing a better understanding of the molecular pathogenesis of this disease and discovering new targets for therapeutic development.

METHODS

The authors identified somatic nonsynonymous coding mutations in oncogenes associated with human cancers and hotspot mutations from tumor suppressor genes that were either well described in the literature or observed multiple times in human cancer sequencing efforts. Then, 961 mutations in 89 genes were systematically characterized across 98 osteosarcoma tumor samples and cell lines. All identified mutations were replicated on an independent platform using homogeneous mass extend matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

In total, 14 mutations were identified in at least 1 osteosarcoma tumor sample or cell line. Some of the genetic changes identified were in tumor suppressor genes previously identified as altered in osteosarcoma: p53 (arginine→histidine at codon 273 [R273H], R→cysteine at codon 723 [R273C], and tyrosine→C at codon 163 [Y163C]) and retinoblastoma 1 (RB1) (glutamic acid→* at codon 137 [E137*]). Notably, multiple mutations were identified in phosphoinositide-3-kinase (PI3K), catalytic, alpha polypeptide (PIK3CA) (H1047R, E→lysine at codon 545 [E545K], and H→proline at codon 701 [H701P]) that were not observed previously in osteosarcoma. In addition, mutations in v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) (glycine→serine at codon 12 [G12S]); cubilin (CUBN) (isolucine→valine at codon 3189 [I3189V]; observed in 2 separate tumor samples); cadherin 1, type 1, epithelial (CDH1) (alanine→threonine at codon 617 [A617T]; observed in 2 separate tumor samples); catenin (cadherin-associated protein), beta 1, 88 kDa (CTNNB1) (asparagine→S at codon 287 [N287S]); and fibrous sheath CABYR binding protein (FSCB) (S→leucine at codon 775 [S775L]) were observed.

CONCLUSIONS

In this largest mutational profiling of osteosarcoma to date, the authors identified for the first time several mutations involving the PI3K pathway, adding osteosarcoma to the growing list of malignancies with PI3K mutations. In addition, they initiated a mutational map detailing DNA sequence changes across a variety of osteosarcoma subtypes and offered new candidates for therapeutic targeting.

Snail-1 regulates VDR signaling and inhibits 1,25(OH)-D₃ action in osteosarcoma

Previous research has shown that vitamin D could suppress proliferation, migration and invasion of cancers, but the effects of vitamin D may be related to the expression of Snail-1, which could inhibit the expression of the vitamin-D gene receptor (VDR). Snail-1 is overexpressed in osteosarcoma, this study was conducted to determine whether inhibiting Snail-1 could increase the role of vitamin D as an anti- osteosarcoma agent. We used stable transfection of the SaOS₂ cell line as in vitro model to study the effect of 1,25(OH)-D₃, which is the most active metabolite of vitamin D. The in vitro antiproliferative, pro-apoptotic and inhibiting of invasion effects were examined. The effects of 1,25(OH)-D₃ on the expression of β-catenin signaling pathways were also studied. Then in vivo antiproliferative effect of 1,25(OH)-D₃ was also detected in nude mice injected with either mock-infected or Snail-1 SaOS₂ cells. We found that inhibition of Snail-1 signaling by transfection could increase the expression of VDR, enhance the anti-proliferative activity of 1,25(OH)-D₃ in osteosarcoma cells, and induce apoptosis and lower invasion in vitro. The effect of 1,25(OH)-D₃ was also associated with decreased expression of β-catenin signaling, which is related to VDR signaling. In vivo, the effect of antiproliferative was higher in mice injected with either Snail-1-infected cells than with mock-infected cells. Our findings suggest that canonical Snail-1/VDR/β-catenin signaling reflects an important underlying mechanism of osteosarcoma progression. Therefore, strategies to suppress Snail-mediated signaling may lead to the better action of 1,25(OH)-D₃ as an anti osteosarcoma treatment.

Targeted therapies in bone sarcomas: current approach and future directions

INTRODUCTION

Bone sarcomas are rare malignancies and once advanced, there is limited response to current chemotherapeutic regimens. Targeted therapies could have substantial impact on these diseases.

AREAS COVERED

Specific molecular targets of bone sarcomas are reviewed along with the various targeted therapies that have potential to change the outcome of these chemotherapy resistant diseases.

EXPERT OPINION

There are promising pathways identified that targeted inhibitors could provide better treatment options for metastatic bone sarcomas. There is a strong need for continued Phase II and III clinical trials investigating these molecularly targeted therapies.

MicroRNA-143 regulates human osteosarcoma metastasis by regulating matrix metalloprotease-13 expression

Pulmonary metastases are the main cause of death in patients with osteosarcoma, however, the molecular mechanisms of metastasis are not well understood. To detect lung metastasis-related microRNA (miRNA) in human osteosarcoma, we compared parental (HOS) and its subclone (143B) human osteosarcoma cell lines showing lung metastasis in a mouse model. miR-143 was the most downregulated miRNA (P < 0.01), and transfection of miR-143 into 143B significantly decreased its invasiveness, but not cell proliferation. Noninvasive optical imaging technologies revealed that intravenous injection of miR-143, but not negative control miRNA, significantly suppressed lung metastasis of 143B (P < 0.01). To search for miR-143 target mRNA in 143B, microarray analyses were performed using an independent RNA pool extracted by two different comprehensive miR-143-target mRNA collecting systems. Western blot analyses revealed that MMP-13 was mostly protein downregulated by miR-143. Immunohistochemistry using clinical samples clearly revealed MMP-13-positive cells in lung metastasis-positive cases, but not in at least three cases showing higher miR-143 expression in the no metastasis group. Taken together, these data indicated that the downregulation of miR-143 correlates with the lung metastasis of human osteosarcoma cells by promoting cellular invasion, probably via MMP-13 upregulation, suggesting that miRNA could be used to develop new molecular targets for osteosarcoma metastasis.

Epigenetic regulation of apoptosis and cell cycle in osteosarcoma

The role of genetic mutations in the development of osteosarcoma, such as alterations in p53 and Rb, is well understood. However, the significance of epigenetic mechanisms in the progression of osteosarcoma remains unclear and is increasingly being investigated. Recent evidence suggests that epigenetic alterations such as methylation and histone modifications of genes involved in cell cycle regulation and apoptosis may contribute to the pathogenesis of this tumor. Importantly, understanding the molecular mechanisms of regulation of these pathways may give insight into novel therapeutic strategies for patients with osteosarcoma. This paper serves to summarize the described epigenetic mechanisms in the tumorigenesis of osteosarcoma, specifically those pertaining to apoptosis and cell cycle regulation.

The role of Fas/FasL in the metastatic potential of osteosarcoma and targeting this pathway for the treatment of osteosarcoma lung metastases

Pulmonary metastases remain the main cause of death in patients with Osteosarcoma (OS). In order to identify new targets for treatment, our laboratory has focused on understanding the biological properties of the tumor microenvironment that contribute to or interfere with metastasis. Dysfunction of the Fas/FasL signaling pathway has been implicated in tumor development, and progression. Here we describe the status of Fas expression in murine nonmetastatic K7 and metastatic K7M2 cells and human nonmetastatic SAOS and LM2 and metastatic LM6 OS cells. We demonstrated that Fas expression correlates inversely with metastatic potential. Pulmonary metastases from patients were uniformly Fas- supporting the importance of Fas expression to the metastatic potential. Since FasL is constitutively expressed in the lung, our data suggests that Fas+ tumor cells undergo apoptosis and are cleared from the lung. By contrast, Fas- tumor cells evade this host defense mechanism and form lung metastases. We confirmed these findings by blocking the Fas pathway using Fas Associated Death Domain Dominant-Negative (FDN). Fas+ cells transfected with FDN were not sensitive to FasL, showed delayed clearance and formed lung metastases. Fas+ cells were also able to form lung metastases in FasL-deficient mice. Using our mouse model systems, we demonstrated that aerosol treatment with liposomal 9-Nitrocamptothecin and Gemcitabine (chemotherapeutic agents known to upregulate Fas expression) increased Fas expression and induced tumor regression in wild type mice. Lung metastases in FasL deficient mice did not respond to the treatment. We conclude that Fas is an early defense mechanism responsible for clearing invading Fas+ tumor cells from the lung. Fas- cells or cells with a nonfunctional Fas pathway evade this defense mechanism and form lung metastases. Therapy that induces Fas expression may therefore be effective in patients with established OS lung metastases. Aerosol delivery of these agents is an ideal way to target treatment to the lung.

Inhibition of tumors cell growth in osteosarcoma-bearing SD rats through a combination of conventional and metronomic scheduling of neoadjuvant chemotherapy

AIM

To investigate whether a combination of conventional and metronomic scheduling of chemotherapy could enhance and extend the effectiveness of chemotherapy against osteosarcoma.

METHODS

A total of 110 osteosarcoma-bearing SD rats were randomly divided into four groups, three of which were given conventional, metronomic or combination scheduling of chemotherapy, and the remaining one served as a control. Tumor volumes were measured every week during the treatment period of 8 weeks. At the end of treatment, tumors were removed from the rats and weighed. Expression of VEGFA in tumors was determined using Western blot assays.

RESULTS

As indicated by the tumor volume, conventional and metronomic schedules showed similar trends in tumor growth curves, and both of them lost their inhibitory effect in the sixth week, whereas the combination schedule maintained effectiveness until the end of treatment. Statistical significance with tumor volumes and weights was found among the groups (P<0.001), with combination scheduling being the most effective (P<0.001). Western blot indicated that all the therapy groups had significantly decreased expression of VEGFA (P<0.01), and the combination scheduling group had the lowest VEGFA expression.

CONCLUSION

Combination of conventional and metronomic scheduling of chemotherapy could be a promising treatment for osteosarcoma. Antiangiogenesis contributed to the effect of combination scheduling.

The expression and significance of IDH1 and p53 in osteosarcoma

Background

To detect the expression of isocitrate dehydrogenase 1 (IDH1) and transformation-related protein 53 (p53) in osteosarcoma and analyze the correlation between them and the clinico-pathological features.

Methods

The expressions of IDH1 and p53 were detected in human osteosarcoma cell lines (MG-63 and U2OS) by immunocytochemistry, Real-time PCR and Western Blotting. The expressions of IDH1 and p53 in formalin-fixed paraffin-embedded tissue sections from 44 osteosarcoma patients were determined by immunohistochemistry, and the correlation between them and clinicopagthological features were analyzed. None of these patients received chemotherapy prior to surgery.

Results

IDH1 is detected in osteosarcoma cell lines and biopsies. IDH1 expresses higher in U2OS cells with wild type p53 than in MG-63 cells with mutation p53. IDH1 correlates with histological Rosen grade and metastasis negatively. P53 correlates with histological Rosen grade, metastasis and overall survival in clinical osteosarcoma biopsies. Osteosarcoma patients with High IDH1 expression have a very high p53 expression.

Conclusion

IDH1 may correlate with p53 and be a candidate biomarker for osteosarcoma correlate with histological Rosen grade and metastasis.

Comparative proteomics analysis of human osteosarcomas and benign tumor of bone

We conducted comparative proteomic analysis of osteosarcoma, with hopes of identifying the specific protein markers of osteosarcoma and improve the understanding of tumorigenesis and progression of osteosarcoma. Proteins extracted from osteosarcoma tissue and benign bone tumors, including osteoblastoma, chondroblastoma, and giant cell tumor of bone, were examined using two-dimensional gel electrophoresis followed by mass spectrometry analysis and database searches. We also validated the expression levels of interesting proteins by Western blotting assay and immunohistochemical staining. Intensity alterations of 30 spots were detected in osteosarcoma, and 18 of these spots were finally identified, including 12 up-regulated proteins and 6 down-regulated ones. The up-regulated proteins include VIM, TUBA1C, ZNF133, EZR, ACTG1, TF, and so on. The six down-regulated proteins include ADCY1, ATP5B, TUBB, RCN3, ACTB, and YWHAZ. Subsequent immunohistochemical staining and Western blotting assay for TUBA1C and ZNF133 in osteosarcoma samples confirmed the observation obtained by proteomic analysis. Our results suggest that these identified proteins may be potential biomarkers for osteosarcoma tumorigenesis and therapeutics. Aberrant expression of cytoskeletal- and microtubule-associated proteins in osteosarcoma may provide an advantage for tumor invasion and metastasis by affecting the stability of microtubule, which consequently influences the prognosis of patients.

Rapid selection and proliferation of CD133+ cells from cancer cell lines: chemotherapeutic implications

Cancer stem cells (CSCs) are considered a subset of the bulk tumor responsible for initiating and maintaining the disease. Several surface cellular markers have been recently used to identify CSCs. Among those is CD133, which is expressed by hematopoietic progenitor cells as well as embryonic stem cells and various cancers. We have recently isolated and cultured CD133 positive [CD133(+)] cells from various cancer cell lines using a NASA developed Hydrodynamic Focusing Bioreactor (HFB) (Celdyne, Houston, TX). For comparison, another bioreactor, the rotary cell culture system (RCCS) manufactured by Synthecon (Houston, TX) was used. Both the HFB and the RCCS bioreactors simulate aspects of hypogravity. In our study, the HFB increased CD133(+) cell growth from various cell lines compared to the RCCS vessel and to normal gravity control. We observed a (+)15-fold proliferation of the CD133(+) cellular fraction with cancer cells that were cultured for 7-days at optimized conditions. The RCCS vessel instead yielded a (−)4.8-fold decrease in the CD133(+)cellular fraction respect to the HFB after 7-days of culture. Interestingly, we also found that the hypogravity environment of the HFB greatly sensitized the CD133(+) cancer cells, which are normally resistant to chemo treatment, to become susceptible to various chemotherapeutic agents, paving the way to less toxic and more effective chemotherapeutic treatment in patients. To be able to test the efficacy of cytotoxic agents in vitro prior to their use in clinical setting on cancer cells as well as on cancer stem cells may pave the way to more effective chemotherapeutic strategies in patients. This could be an important advancement in the therapeutic options of oncologic patients, allowing for more targeted and personalized chemotherapy regimens as well as for higher response rates.

Effect of troglitazone on tumor growth and pulmonary metastasis development of the mouse osteosarcoma cell line LM8

Background

Osteosarcoma often develops micrometastases in the lung prior to diagnosis, causing a fatal outcome. Therefore, the prevention of pulmonary metastases is critical for the improvement of the prognosis of patients with osteosarcoma. The purpose of this study was to investigate whether troglitazone (TGZ) is considered as possible therapeutics in the treatment of growth and metastasis of osteosarcoma.

Methods

LM8 cells were treated for 3 days with various concentrations of TGZ. The effect of TGZ on cell proliferation was determined by DNA measurement in the cultures and 5-bromo-2'-deoxyuridine incorporation study. The assay of cell invasion and motility was performed using either the Matrigel-coated cell culture inserts or the uncoated cell culture inserts in the invasion chambers. The effect of TGZ on Akt signaling was assessed by Western blot analysis of Akt and p-Akt. The effects of oral administration of either TGZ (TGZ group) or ethanol (control group) on the growth of primary tumor and the development of pulmonary metastasis were examined in nude mice implanted with LM8 cells on their backs. The expression and activity of matrix metalloproteinase 2 (MMP-2) within the tumor were determined by immunohistochemistry and zymography. The microvessel density (MVD) within the tumor was determined by immunohistochemistry for CD34.

Results

TGZ dose-dependently inhibits cell proliferation. TGZ-treated cells were less invasive and less motile than untreated cells. The activity of MMP-2 secreted by TGZ-treated cells was lower than that secreted by untreated cells. TGZ decreased the level of p-Akt. The primary tumor mass was smaller in the TGZ group than in the control group. The TGZ group had less metastatic tumors in the lung compared with the control group. The expression and activity of MMP-2 within the tumor of the TGZ group were lower than those of the control group. The MVD within the tumor of the TGZ group was lower than that of the control group.

Conclusions

Inhibition of Akt signaling by TGZ may decrease the secretion of MMP-2, resulting in the decrease of invasiveness and motility in LM8 cells. Treatment of tumor-bearing mice with TGZ decreases the expression and activity of MMP-2 within the tumor, and inhibits primary tumor growth and pulmonary metastasis development. TGZ may offer a new approach in chemotherapy for osteosarcoma.

Anti-osteosarcoma effects and mechanisms of 4-O-amino-phenol-4‘-demethylepipodophyllotoxin ether

The purpose of this study was to investigate the anti-osteosarcoma effects and mechanisms of 4-O-amino-phenol-4′-demethylepipodophyllotoxin ether (ODE), a new derivative of podophyllotoxin. The results showed that ODE inhibited proliferation of K562, OS-9901, CNE, BGC-823 and Tca-8113 cells in a time- and concentration-dependent manner as determined by microculture tetrazolium (MTT) assay. OS-9901 and K562 cells treated with ODE for 24h showed cell cycle arrest at G2/M and a parallel decrease in G0/G1 and S phase as detected by flow cytometry (FCM). Meanwhile, a fraction of cells with hypodiploid DNA content representing apoptosis were detected by FCM. Morphology observation also revealed typical apoptotic features, including shrinkage of cellular and nuclear membranes, condensed heterochromatin around the nuclear periphery and cytoplasmic vacuolation in OS-9901 cells. Under a confocal laser scanning microscope, intracellular Ca2+ and Mg2+ concentrations were greatly increased whereas the pH value, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were markedly reduced in OS-9901 cells after treatment with ODE. Taken together, these results suggest that the anti-osteosarcoma mechanisms of ODE are attributed to apoptosis through increasing intracellular Ca2+ and Mg2+ concentrations, and reducing pH value, MMP and ROS.

Reduced argininosuccinate synthetase is a predictive biomarker for the development of pulmonary metastasis in patients with osteosarcoma

Pulmonary metastasis is the most significant prognostic determinant for osteosarcoma, but methods for its prediction and treatment have not been established. Using oligonucleotide microarrays, we compared the global gene expression of biopsy samples between seven osteosarcoma patients who developed pulmonary metastasis within 4 years after neoadjuvant chemotherapy and curative resection, and 12 patients who did not relapse. We identified argininosuccinate synthetase (ASS) as a gene differentially expressed with the highest statistical significance (Welch's t test, P = 2.2 x 10(-5)). Immunohistochemical analysis of an independent cohort of 62 osteosarcoma cases confirmed that reduced expression of ASS protein was significantly correlated with the development of pulmonary metastasis after surgery (log-rank test, P < 0.05). Cox regression analysis revealed that ASS was the sole significant predictive factor (P = 0.039; hazard ratio, 0.319; 95% confidence interval, 0.108-0.945). ASS is one of the enzymes required for the production of a nonessential amino acid, arginine. We showed that osteosarcoma cells lacking ASS expression were auxotrophic for arginine and underwent G(0)-G(1) arrest in arginine-free medium, suggesting that an arginine deprivation therapy could be effective in patients with osteosarcoma. Recently, phase I and II clinical trials in patients with melanoma and hepatocellular carcinoma have shown the safety and efficacy of plasma arginine depletion by stabilized arginine deiminase. Our data indicate that in patients with osteosarcoma, reduced expression of ASS is not only a novel predictive biomarker for the development of metastasis, but also a potential target for pharmacologic intervention.

Gingival Osteogenic Melanoma in Two Dogs

Osteogenic melanoma is a rare variant of metaplastic malignant melanoma in human medicine and appears to be a similarly rare variant in dogs. Two dogs with oral malignant melanoma with neoplastic bone formation are reported in this study. Both tumors were characterized by malignant melanocytes that transitioned into neoplastic bone at the deep margins of the neoplasm. Immunohistochemical analysis revealed S100- and Melan-A–positive neoplastic cells adjacent to, and occasionally embedded within, an osteoid and chondroblastic matrix. Scattered clusters of neoplastic cells were also positive for osteocalcin. The findings indicate that in dogs, as in humans, neoplastic melanocytes have metaplastic potential and can be osteogenic.

Posterior-Only Approach For Total En Bloc Spondylectomy For Malignant Primary Spinal Neoplasms: Anatomic Considerations and Operative Nuances

MALIGNANT PRIMARY SPINAL tumors are rare tumors that are locally invasive and can metastasize. The majority of these tumors have a poor response rate to chemotherapy and conventional radiotherapy. Studies have shown that long-term survival and the potential for cure is best achieved with en bloc surgical excision of these tumors with negative surgical margins. Total en bloc spondylectomy involves removal of vertebral segment(s) in whole to achieve wide tumor excision. Total en bloc spondylectomy can be performed through staged or combined anterior and posterior approaches, or from a posterior-only approach. The posterior-only approach offers the advantage of achieving complete tumor excision and circumferential spinal reconstruction in a single setting. In this report, we discuss the operative management of malignant primary vertebral tumors using the posterior-only approach for total en bloc spondylectomy. The oncological considerations and surgical nuances that allow for safe but aggressive surgical excision of primary spinal tumors to achieve favorable oncological and neurological outcomes are highlighted.