Expressions of p53, c-MYC, BCL-2 and apoptotic index in human osteosarcoma and their correlations with prognosis of patients

Investigation of cellular communication and signaling pathways in tumor microenvironment for high TP53-expressing osteosarcoma cells through single-cell RNA sequencing

Osteosarcoma (OS) stands as the most prevalent primary bone cancer in children and adolescents, and its limited treatment options often result in unsatisfactory outcomes, particularly for metastatic cases. The tumor microenvironment (TME) has been recognized as a crucial determinant in OS progression. However, the intercellular dynamics between high TP53-expressing OS cells and neighboring cell types within the TME are yet to be thoroughly understood. In our study, we harnessed the single-cell RNA sequencing (scRNA-seq) technology in combination with the computational tool-Cellchat, aiming to elucidate the intercellular communication networks present within OS. Through meticulous quantitative inference and subsequent analysis of these networks, we succeeded in identifying significant signaling pathways connecting high TP53-expressing OS cells with proximate cell types, namely Macrophages, Monocytes, Endothelial Cells, and PVLs. This research brings forth a nuanced understanding of the intricate patterns and coordination involved in the TME's intercellular communication signals. These findings not only provide profound insights into the molecular mechanisms underpinning OS but also indicate potential therapeutic targets that could revolutionize treatment strategies.

Osteosarcoma in Pediatric and Adult Populations: Are Adults Just Big Kids?

Malignant bone tumors are commonly classified as pediatric or adolescent malignancies, and clinical trials for these diseases have generally focused on these populations. Of primary bone cancers, osteosarcoma is among the most common. Osteosarcoma has a bimodal age distribution, with the first peak occurring in patients from 10 to 14 years old, and the second peak occurring in patients older than 65, with about 25% of cases occurring in adults between 20 and 59 years old. Notably, adult osteosarcoma patients have worse outcomes than their pediatric counterparts. It remains unclear whether age itself is a poor prognostic factor, or if inherent differences in tumor biology exist between age groups. Despite these unknowns, current treatment strategies for adults are largely extrapolated from pediatric studies since the majority of clinical trials for osteosarcoma treatments are based on younger patient populations. In light of the different prognoses observed in pediatric and adult osteosarcoma, we summarize the current understanding of the molecular etiology of osteosarcoma and how it may differ between age groups, hypothesizing why adult patients have worse outcomes compared to children.

MiR-4270 acts as a tumor suppressor by directly targeting Bcl-xL in human osteosarcoma cells

Chondrosarcomas and osteosarcomas are malignant bone tumors with a poor prognosis when unresectable or metastasized. Moreover, radiotherapy and chemotherapy could be ineffective. MiRNAs represent an alternative therapeutic approach. Based on high-throughput functional screening, we identified four miRNAs with a potential antiproliferative effect on SW1353 chondrosarcoma cells. Individual functional validations were then performed in SW1353 cells, as well as in three osteosarcoma cell lines. The antiproliferative and cytotoxic effects of miRNAs were evaluated in comparison with a positive control, miR-342-5p. The cytotoxic effect of four selected miRNAs was not confirmed on SW1353 cells, but we unambiguously revealed that miR-4270 had a potent cytotoxic effect on HOS and MG-63 osteosarcoma cell lines, but not on SaOS-2 cell line. Furthermore, like miR-342-5p, miR-4270 induced apoptosis in these two cell lines. In addition, we provided the first report of Bcl-xL as a direct target of miR-4270. MiR-4270 also decreased the expression of the anti-apoptotic protein Mcl-1, and increased the expression of the pro-apoptotic protein Bak. Our findings demonstrated that miR-4270 has tumor suppressive activity in osteosarcoma cells, particularly through Bcl-xL downregulation.

Impairment of rigidity sensing caused by mutant TP53 gain of function in osteosarcoma

Osteosarcoma (OS) is the most common primary malignant pediatric bone tumor and is characterized by high heterogeneity. Studies have revealed a wide range of phenotypic differences among OS cell lines in terms of their in vivo tumorigenicity and in vitro colony-forming abilities. However, the underlying molecular mechanism of these discrepancies remains unclear. The potential role of mechanotransduction in tumorigenicity is of particular interest. To this end, we tested the tumorigenicity and anoikis resistance of OS cell lines both in vitro and in vivo. We utilized a sphere culture model, a soft agar assay, and soft and rigid hydrogel surface culture models to investigate the function of rigidity sensing in the tumorigenicity of OS cells. Additionally, we quantified the expression of sensor proteins, including four kinases and seven cytoskeletal proteins, in OS cell lines. The upstream core transcription factors of rigidity-sensing proteins were further investigated. We detected anoikis resistance in transformed OS cells. The mechanosensing function of transformed OS cells was also impaired, with general downregulation of rigidity-sensing components. We identified toggling between normal and transformed growth based on the expression pattern of rigidity-sensing proteins in OS cells. We further uncovered a novel TP53 mutation (R156P) in transformed OS cells, which acquired gain of function to inhibit rigidity sensing, thus sustaining transformed growth. Our findings suggest a fundamental role of rigidity-sensing components in OS tumorigenicity as mechanotransduction elements through which cells can sense their physical microenvironment. In addition, the gain of function of mutant TP53 appears to serve as an executor for such malignant programs.

The mitotic regulator polo-like kinase 1 as a potential therapeutic target for c-Myc-overexpressing canine osteosarcomas

Osteosarcoma is the most common primary malignant bone tumour in dogs, characterized by a locally aggressive and highly metastatic behaviour. Despite the current standards of care, most dogs succumb to the disease, indicating the need for novel treatment strategies. Polo-like kinase 1 (PLK1) is dysregulated in a variety of human cancer types, including osteosarcoma, and induces c-Myc accumulation. The crosstalk between the two molecules coordinates cell proliferation, differentiation, self-renewal and apoptosis. Therefore, PLK1 has recently emerged as a potential therapeutic target, mainly in tumours overexpressing c-Myc. BI 2536 is a selective PLK1 inhibitor promoting mitotic arrest and apoptosis in a variety of cancer cells. This research aimed at evaluating PLK1 and c-Myc protein expression in 53 appendicular canine osteosarcoma (cOSA) samples and the in vitro effects of BI 2536 on a c-Myc and PLK1-overexpressing cOSA cell line (D17). PLK1 and c-Myc expression in cOSA samples showed no correlation with clinicopathological data. However, c-Myc overexpression was associated with a significantly reduced overall survival (p = .003). Western Blot and RT-qPCR assays revealed that D17 expressed high protein and transcript levels of both PLK1 and MYC. When treated with BI 2536 (range 2.5-15 nM) for 24 h, D17 showed a substantial decrease in cell growth, inducing apoptosis and G₂ /M cell cycle arrest. Interestingly, under BI 2536 treatment, D17 showed decreased c-Myc protein levels. Consistent with human OSA, these preliminary data outline the prognostic value of c-Myc expression in cOSA and highlight the potential role of PLK1 as an antiproliferative therapeutic target for tumours overexpressing c-Myc.

The roles of glycolysis in osteosarcoma

Metabolic reprogramming is of great significance in the progression of various cancers and is critical for cancer progression, diagnosis, and treatment. Cellular metabolic pathways mainly include glycolysis, fat metabolism, glutamine decomposition, and oxidative phosphorylation. In cancer cells, reprogramming metabolic pathways is used to meet the massive energy requirement for tumorigenesis and development. Metabolisms are also altered in malignant osteosarcoma (OS) cells. Among reprogrammed metabolisms, alterations in aerobic glycolysis are key to the massive biosynthesis and energy demands of OS cells to sustain their growth and metastasis. Numerous studies have demonstrated that compared to normal cells, glycolysis in OS cells under aerobic conditions is substantially enhanced to promote malignant behaviors such as proliferation, invasion, metastasis, and drug resistance of OS. Glycolysis in OS is closely related to various oncogenes and tumor suppressor genes, and numerous signaling pathways have been reported to be involved in the regulation of glycolysis. In recent years, a vast number of inhibitors and natural products have been discovered to inhibit OS progression by targeting glycolysis-related proteins. These potential inhibitors and natural products may be ideal candidates for the treatment of osteosarcoma following hundreds of preclinical and clinical trials. In this article, we explore key pathways, glycolysis enzymes, non-coding RNAs, inhibitors, and natural products regulating aerobic glycolysis in OS cells to gain a deeper understanding of the relationship between glycolysis and the progression of OS and discover novel therapeutic approaches targeting glycolytic metabolism in OS.

Quercetin and Methotrexate in Combination have Anticancer Activity in Osteosarcoma Cells and Repress Oncogenic MicroRNA-223

INTRODUCTION

Osteosarcoma (OS) is one of the most common bone neoplasms in adolescents. Notable short- and long-term toxic effects of OS chemotherapy regimens have been reported. Hence, new chemotherapeutic agents with the ability to potentiate OS chemotherapy drugs and protect non-tumorous tissues are required.

METHODS

Saos-2 cells were treated with Methotrexate (MTX) and Quercetin (Que) (a polyphenolic flavonoid with anti-tumor effects) alone and in combination. MTT assay was performed to investigate the cytotoxicity of the drugs. Moreover, apoptosis-involved genes, including miR-223, p53, BCL-2, CBX7, and CYLD expression were analyzed via qRT-PCR. Annexin V-FITC/PI kit was employed to assess the apoptosis rate.

RESULTS

The MTT results showed that Que increases MTX cytotoxicity on OS cells. The measured IC50s are 142.3 µM for QUE and 13.7 ng/ml for MTX. A decline in MTX IC50 value was observed from 13.7 ng/ml to 8.45 ng/ml in the presence of Que. Moreover, the mRNA expression outcomes indicated that the combination therapy significantly up-regulates the tumor suppressor genes, such as p53, CBX7, and CYLD, and declines anti-apoptotic genes BCL-2 and miR-223, which can lead to proliferation inhibition and apoptosis inducement. Furthermore, the apoptosis rate increased significantly from 6.03% in the control group to 38.35% in Saos-2 cells that were treated with the combination of MTX and Que.

CONCLUSION

Que, with the potential to boost the anticancer activity of MTX on Saos-2 cancer cells through proliferation inhibition and apoptosis induction, is a good candidate for combination therapy.

Tumor Suppressive Role of miR-342-5p and miR-491-5p in Human Osteosarcoma Cells

Osteosarcomas are the most common type of malignant bone tumor. These tumors are characterized by the synthesis of an osteoid matrix. Current treatments are based on surgery and combination chemotherapy. However, for metastatic or recurrent tumors, chemotherapy is generally ineffective, and osteosarcomas are sometimes unresectable. Thus, the use of microRNAs (miRNAs) may represent an attractive alternative for the development of new therapies. Using high-throughput functional screening based on impedancemetry, we previously selected five miRNAs with potential chemosensitizing or antiproliferative effects on chondrosarcoma cells. We validated the tumor-suppressive activity of miR-491-5p and miR-342-5p in three chondrosarcoma cell lines. Here, we carried out individual functional validation of these five miRNAs in three osteosarcoma cell lines used as controls to evaluate their specificity of action on another type of bone sarcoma. The cytotoxic effects of miR-491-5p and miR-342-5p were also confirmed in osteosarcoma cells. Both miRNAs induced apoptosis. They increased Bcl-2 homologous antagonist killer (Bak) protein expression and directly targeted Bcl-2 lymphoma-extra large (Bcl-xL). MiR-342-5p also decreased B-cell lymphoma-2 (Bcl-2) protein expression, and miR-491-5p decreased that of Epidermal Growth Factor Receptor (EGFR). MiR-342-5p and miR-491-5p show tumor-suppressive activity in osteosarcomas. This study also confirms the potential of Bcl-xL as a therapeutic target in osteosarcomas.

Molecular profiling of osteosarcoma in children and adolescents from different age groups using a next-generation sequencing panel

Osteosarcoma (OS) is a malignant bone tumor, with a peak of incidence in the second decade of life and possibly associated with the presence of germline mutations. Besides, clinicians have pointed to a second, rarer group of patients that develops OS before 10 years old. Here we access, through next-generation sequencing (NGS) strategy, the genetic alterations present in OS and blood samples from patients diagnosed before and during the second decade of life. A custom NGS panel, designed for the main alterations described in childhood and adolescence neoplasms, named Oncomine Childhood Cancer Research Assay (OCCRA©), was used. Of all 84 OS samples investigated, 42 (50%) presented some somatic variant, with TP53, MYC, CDK4, RB1 and PDGFRA genes harboring the most observed genetic variants. MYC CNVs were more frequent in tumors from patients diagnosed before 10 years old (X²₁= 5.18, p = 0.023). Additionally, patients diagnosed during the second decade of life presented a higher percentage of somatic and germline variants. Germline variants in TP53 and RB1 were found in 5 of the 11 (45.5%) patients analyzed. Clinical variables and tumor histopathological characteristics were also collected and correlated with our molecular findings.

The anti-osteosarcoma effect from panax notoginseng saponins by inhibiting the G0 / G1 phase in the cell cycle and affecting p53-mediated autophagy and mitochondrial apoptosis

Osteosarcoma is the most common primary bone malignancy, and current chemotherapy sessions against it often induce severe complications in patients. Thus, it is necessary to develop new and effective antineoplastic agents with fewer side effects. Panax notoginseng saponins (PNS) are the active components in panax notoginseng and were reported to be capable of inhibiting the growth of several tumors both in vitro and in vivo. However, its effects on osteosarcoma have not been studied yet, which is addressed in this study for the first time. Our results indicated that PNS can inhibit proliferation, invasion and migration of the osteosarcoma cells, while promoting their apoptosis simultaneously. Specifically, PNS caused an increase in mitochondrial membrane potential and the amount of reactive oxygen species. The cell cycle in osteosarcoma cells was arrested in the G0 / G1 phase after PNS treatment. The expression of p53 and other apoptosis-related mitochondrial proteins were promoted. Nevertheless, it was observed that autophagy became less active in osteosarcoma cells when PNS was administered. In a word, PNS were of potential therapeutic significance for osteosarcoma.

Severe cellular stress activates apoptosis independently of p53 in osteosarcoma

Apoptosis induced by doxorubicin, bortezomib, or paclitaxel, targeting DNA, 26S proteasome, and microtubules respectively, was assessed in two osteosarcoma cells, p53 wild-type U2OS and p53-null MG63 cells. Doxorubicin-induced apoptosis only occurred in U2OS, not in MG63. In contrast, bortezomib and paclitaxel could drive U2OS or MG63 toward apoptosis effectively, suggesting that apoptosis induced by bortezomib or paclitaxel is p53-independent. The expressions of Bcl2 family members such as Bcl2, Bcl-xl, and Puma could be seen in U2OS and MG63 cells with or without doxorubicin, bortezomib, or paclitaxel treatment. In contrast, another member, Bim, only could be observed in U2OS, not in MG63, under the same conditions. Bim knockdown did not affect the doxorubicin-induced apoptosis in U2OS, suggested that a BH3-only protein other than Bim might participate in apoptosis induced by doxorubicin. Using a BH3-mimetic, ABT-263, to inhibit Bcl2 or Bcl-xl produced a limited apoptotic response in U2OS and MG63 cells, suggesting that this BH3-mimetic cannot activate the Bax/Bak pathway efficiently. Significantly, ABT-263 enhanced doxorubicin- and bortezomib-induced apoptosis synergistically in U2OS and MG63 cells. These results implied that the severe cellular stress caused by doxorubicin or bortezomib might be mediated through a dual process to control apoptosis. Respectively, doxorubicin or bortezomib activates a BH3-only protein in one way and corresponding unknown factors in another way to affect mitochondrial outer membrane permeability, resulting in apoptosis. The combination of doxorubicin with ABT-263 could produce synergistic apoptosis in MG63 cells, which lack p53, suggesting that p53 has no role in doxorubicin-induced apoptosis in osteosarcoma. In addition, ABT-263 enhanced paclitaxel to induce moderate levels of apoptosis.

MiR-134, Mediated by IRF1, Suppresses Tumorigenesis and Progression by Targeting VEGFA and MYCN in Osteosarcoma

BACKGROUND

Osteosarcoma (OS) is a prevalent primary bone malignancy and its distal metastasis remains the main cause of mortality in OS patients. MicroRNAs (miRNAs) play critical roles during cancer metastasis.

OBJECTIVE

Thus, elucidating the role of miRNA dysregulation in OS metastasis may provide novel therapeutic targets.

METHODS

The previous study found a low miR-134 expression level in the OS specimens compared with paracancer tissues. Overexpression of miR-134 stable cell lines was established. Cell viability assay, cell invasion and migration assay and apoptosis assay were performed to evaluate the role of miR-134 in OS in vitro.

RESULTS

We found that miR-134 overexpression inhibits cell proliferation, migration and invasion, and induces cell apoptosis in both MG63 and Saos-2 cell lines. Mechanistically, miR-134 targets the 3'-UTR of VEGFA and MYCN mRNA to silence its translation, which was confirmed by luciferase-reporter assay. The real-time PCR analysis illustrated that miR-134 overexpression decreases VEGFA and MYCN mRNA levels. Additionally, the overexpression of VEGFA or MYCN can partly attenuate the effects of miR-134 on OS cell migration and viability. Furthermore, the overexpression of miR-134 dramatically inhibits tumor growth in the human OS cell line xenograft mouse model in vivo. Moreover, bioinformatic and luciferase assays indicate that the expression of miR-134 is regulated by Interferon Regulatory Factor (IRF1), which binds to its promoter and activates miR-134 expression.

CONCLUSION

Our study demonstrates that IRF1 is a key player in the transcriptional control of miR-134, and it inhibits cell proliferation, invasion and migration in vitro and in vivo via targeting VEGFA and MYCN.

Mechanisms of Resistance to Conventional Therapies for Osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumor, mainly occurring in children and adolescents. Current standard therapy includes tumor resection associated with multidrug chemotherapy. However, patient survival has not evolved for the past decades. Since the 1970s, the 5-year survival rate is around 75% for patients with localized OS but dramatically drops to 20% for bad responders to chemotherapy or patients with metastases. Resistance is one of the biological processes at the origin of therapeutic failure. Therefore, it is necessary to better understand and decipher molecular mechanisms of resistance to conventional chemotherapy in order to develop new strategies and to adapt treatments for patients, thus improving the survival rate. This review will describe most of the molecular mechanisms involved in OS chemoresistance, such as a decrease in intracellular accumulation of drugs, inactivation of drugs, improved DNA repair, modulations of signaling pathways, resistance linked to autophagy, disruption in genes expression linked to the cell cycle, or even implication of the micro-environment. We will also give an overview of potential therapeutic strategies to circumvent resistance development.

Targeting Molecular Mechanisms Underlying Treatment Efficacy and Resistance in Osteosarcoma: A Review of Current and Future Strategies

Osteosarcoma is the most common primary malignant bone tumour in children and adolescents. Due to micrometastatic spread, radical surgery alone rarely results in cure. Introduction of combination chemotherapy in the 1970s, however, dramatically increased overall survival rates from 20% to approximately 70%. Unfortunately, large clinical trials aiming to intensify treatment in the past decades have failed to achieve higher cure rates. In this review, we revisit how the heterogenous nature of osteosarcoma as well as acquired and intrinsic resistance to chemotherapy can account for stagnation in therapy improvement. We summarise current osteosarcoma treatment strategies focusing on molecular determinants of treatment susceptibility and resistance. Understanding therapy susceptibility and resistance provides a basis for rational therapy betterment for both identifying patients that might be cured with less toxic interventions and targeting resistance mechanisms to sensitise resistant osteosarcoma to conventional therapies.

SLC25A10 performs an oncogenic role in human osteosarcoma

Osteosarcoma is one of the most common primary malignant bone tumors in adolescents. It is associated with high risk of relapse and the outcomes of patients with high-grade osteosarcoma remain poor. Therefore, additional studies investigating the molecular mechanisms involved in tumor initiation, growth, migration and invasion of osteosarcoma are necessary. In the present study, the protein levels of solute carrier family 25 member 10 (SLC25A10) were increased in osteosarcoma tissue, compared with normal bone tissue. In patients with osteosarcoma, high expression levels of SLC25A10 were associated with poor clinicopathological parameters, including metastasis, clinical Enneking stage, relapse-free survival and overall survival rates. Short hairpin RNA knockdown of SLC25A10 significantly suppressed cell proliferation as determined by cell counting, MTT assay and cell colony formation assays. In addition, SLC25A10 knockdown caused an increase in apoptosis and a decrease in mitosis in osteosarcoma cells. Cyclin E1 (CCNE1) was positively regulated by SLC25A10, while P21 and P27 were negatively regulated by SLC25A10. Therefore, SLC25A10 may play an oncogenic role in human osteosarcoma, which could be mediated by CCNE1, P21 and P27.

Emerging next-generation sequencing-based discoveries for targeted osteosarcoma therapy

Osteosarcoma (OS) is the most common primary bone malignancy and is frequently lethal via metastasis to the lung. While surgical techniques and adjuvant chemotherapies have emerged to combat this deadly cancer, the 5-year survival rate has plateaued over the past four decades. Therapeutic progress has been notably poor because past technologies have not been able to reveal obscured OS biomarkers and targets. With the advent and implementation of large-scale next-generation sequencing (NGS) studies, various somatic mutations and copy number changes involved in OS progression and metastasis have surfaced. These findings have significantly expanded the amount of genome-informed pathways and candidate genes suitable for targeting in pre-clinical models. Furthermore, NGS analyses comparing primary and matched pulmonary metastatic tumor tissues have catalogued previously unknown prognostic biomarkers in OS. In this review, we delineate the most recent findings in NGS for OS therapy and how this technology has advanced personalized therapy.

A risk signature-based on metastasis-associated genes to predict survival of patients with osteosarcoma

Osteosarcoma (OS) is the most common primary solid malignant bone tumor, and its metastasis is a prominent cause of high mortality in patients. In this study, a prognosis risk signature was constructed based on metastasis-associated genes. Four microarrays datasets with clinical information were downloaded from Gene Expression Omnibus, and 256 metastasis-associated genes were identified by limma package. Further, a protein-protein interaction network was constructed, and survival analysis was performed using data from the Therapeutically Applicable Research to Generate Effective Treatments data matrix, identifying 19 genes correlated with prognosis. Six genes were selected by the least absolute shrinkage and selection operator regression for multivariate cox analysis. Finally, a three-gene (MYC, CPE, and LY86) risk signature was constructed, and datasets GSE21257 and GSE16091 were used to validate the prediction efficiency of the signature. The survival times of low- and high-risk groups were significantly different in the training set and validation set. Additionally, gene set enrichment analysis revealed that the genes in the signature may affect the cell cycle, gap junctions, and interleukin-6 production. Therefore, the three-gene survival risk signature could potentially predict the prognosis of patients with OS. Further, proteins encoded by CPE and LY86 may provide novel insights into the prediction of OS prognosis and therapeutic targets.

Biology and pathogenesis of human osteosarcoma

Osteosarcoma (OS) is a bone tumor of mesenchymal origin, most frequently occurring during the rapid growth phase of long bones, and usually located in the epiphyseal growth plates of the femur or the tibia. Its most common feature is genome disorganization, aneuploidy with chromosomal alterations, deregulation of tumor suppressor genes and of the cell cycle, and an absence of DNA repair. This suggests the involvement of surveillance failures, DNA repair or apoptosis control during osteogenesis, allowing the survival of cells which have undergone alterations during differentiation. Epigenetic events, including DNA methylation, histone modifications, nucleosome remodeling and expression of non-coding RNAs have been identified as possible risk factors for the tumor. It has been reported that p53 target genes or those genes that have their activity modulated by p53, in addition to other tumor suppressor genes, are silenced in OS-derived cell lines by hypermethylation of their promoters. In osteogenesis, osteoblasts are formed from pluripotent mesenchymal cells, with potential for self-renewal, proliferation and differentiation into various cell types. This involves complex signaling pathways and multiple factors. Any disturbance in this process can cause deregulation of the differentiation and proliferation of these cells, leading to the malignant phenotype. Therefore, the origin of OS seems to be multifactorial, involving the deregulation of differentiation of mesenchymal cells and tumor suppressor genes, activation of oncogenes, epigenetic events and the production of cytokines.

Prospects for the involvement of cancer stem cells in the pathogenesis of osteosarcoma

Osteosarcoma (OS) is one of the most common bone tumors in children and adolescents that cause a high rate of mortality in this age group and tends to be metastatic, in spite of chemotherapy and surgery. The main reason for this can be returned to a small group of malignant cells called cancer stem cells (CSCs). OS-CSCs play a key role in the resistance to treatment and relapse and metastasis through self-renewal and differentiation abilities. In this review, we intend to go through the different aspects of this malignant disease, including the cancer stem cell-phenotype, methods for isolating CSCs, signaling pathways, and molecular markers in this disease, and drugs showing resistance in treatment efforts of OS.

Targeting mutant TP53 as a potential therapeutic strategy for the treatment of osteosarcoma

Mutant TP53 is a promising therapeutic target in cancers. Considering the current challenges facing the clinical treatment of cancer, as well as the urgent need to identify novel therapeutic targets in osteosarcomas, we aimed to evaluate the clinical significance of mutant TP53 in osteosarcoma patients and to explore the therapeutic effect of targeting mutant TP53 in osteosarcomas. We performed a meta-analysis to investigate the relationship between mutant TP53 and the overall survival of patients with osteosarcoma. A CRISPR-Cas9 system and a TP53 inhibitor, NSC59984, were also used to specifically knock-out and inhibit mutant TP53 in the human osteosarcoma cell lines, KHOS, and KHOSR2. The meta-analysis demonstrated that mutations in the TP53 gene could be used to predict a poor 2-year survival in osteosarcoma patients. We also demonstrated that the expression of mutant TP53 in human osteosarcoma cell lines can be efficiently knocked-out using CRISPR-Cas9, and this decreased the proliferation, migration, and tumor formation activity of these osteosarcoma cells. Moreover, drug sensitivity to doxorubicin was increased in these TP53 knock-out osteosarcoma cells. NSC59984 also showed similar anti-tumor effects as CRISPR-Cas9 targeted TP53 in the osteosarcoma cells in vitro. We have also demonstrated that the knock-out or inhibition of mutant TP53 decreased the expression of the oncogene IGF-1R, anti-apoptotic proteins Bcl-2, and Survivin in osteosarcoma cells. Collectively, these results suggest that mutant TP53 is a promising therapeutic target in osteosarcomas. Therefore, further studies exploring novel strategies to target mutant TP53 may help improve the treatment outcomes of osteosarcoma patients in the clinic. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Super enhancer inhibitors suppress MYC driven transcriptional amplification and tumor progression in osteosarcoma

Osteosarcoma is the most common primary bone sarcoma that mostly occurs in young adults. The causes of osteosarcoma are heterogeneous and still not fully understood. Identification of novel, important oncogenic factors in osteosarcoma and development of better, effective therapeutic approaches are in urgent need for better treatment of osteosarcoma patients. In this study, we uncovered that the oncogene MYC is significantly upregulated in metastastic osteosarcoma samples. In addition, high MYC expression is associated with poor survival of osteosarcoma patients. Analysis of MYC targets in osteosarcoma revealed that most of the osteosarcoma super enhancer genes are bound by MYC. Treatment of osteosarcoma cells with super enhancer inhibitors THZ1 and JQ1 effectively suppresses the proliferation, migration, and invasion of osteosarcoma cells. Mechanistically, THZ1 treatment suppresses a large group of super enhancer containing MYC target genes including CDK6 and TGFB2. These findings revealed that the MYC-driven super enhancer signaling is crucial for the osteosarcoma tumorigenesis and targeting the MYC/super enhancer axis represents as a promising therapeutic strategy for treatment of osteosarcoma patients.

Expression of PIM-1 in salivary gland adenoid cystic carcinoma: Association with tumor progression and patients' prognosis

Pim-1 proto-oncogene, serine/threonine kinase (PIM-1) phosphorylates a series of substrates to exert its oncogenic function in numerous malignancies. The present study investigated the clinical significance of the PIM-1 protein, apoptosis status and apoptosis-associated proteins, including forkhead box O3a (FOXO3a), B cell lymphoma-2 (BCL-2) and BCL-2-associted agonist of cell death (BAD), were investigated in salivary gland adenoid cystic carcinoma (ACC) tissues. PIM-1 expression levels in 4 pairs of ACC tissues and corresponding normal salivary gland tissues were determined by western blot analysis. PIM-1, FOXO3a, BAD and BCL-2 expression levels in 60 ACC tissues were evaluated by immunohistochemistry (IHC). A terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling assay was performed to detect the apoptosis status of ACC tissues. PIM-1 was revealed to be highly expressed in ACC tissues compared with adjacent normal tissues. IHC staining results demonstrated high expression ratios of PIM-1, FOXO3a, BCL-2 and BAD [33.33% (20/60), 51.67% (31/60), 51.67% (31/60) and 55% (33/60)], respectively, and significant correlations between the expression of PIM-1 and FOXO3a and BCL-2 (P<0.05). Apoptotic rates were significantly associated with PIM-1, FOXO3a, BCL-2 and BAD expression levels (P<0.05). PIM-1 expression levels were significantly associated with tumor size, lymph node involvement, nerve invasion, distant metastasis and weakly associated with tumor node metastasis stage. Kaplan-Meier survival curves revealed that PIM-1 expression level was significantly associated with disease-free survival of patients with ACC (P=0.009). Cox regression multivariate analysis results revealed that histotype, distant metastasis and apoptotic rate were independent prognosis factors for ACC. Assessment of PIM-1 may be useful in investigating the malignant behaviors of ACC and predicting the outcome of patients with ACC.

Identification and analysis of key genes in osteosarcoma using bioinformatics

Osteosarcoma (OS) is an invasive malignant neoplasm of the bones. The present study identified and analyzed key genes associated with OS. Expression profiling of the dataset GSE49003, which included 6 metastatic and 6 non-metastatic OS cell lines and was obtained from the Gene Expression Omnibus, was performed. Following data preprocessing, the differentially expressed genes (DEGs) were selected using the limma package in R. Subsequently, bidirectional hierarchical clustering using the pheatmap package in R and an unpaired Students' t-test was performed for the DEGs. Based on the Search Tool for the Retrieval of Interacting Genes database and Cytoscape software, a protein-protein interaction (PPI) network for the DEGs was constructed. Using Database for Annotation, Visualization and Integrated Discovery software and the Kyoto Encyclopedia of Genes and Genomes Orthology Based Annotation System server, functional and pathway enrichment analyses were performed for the DEGs corresponding to the proteins of the network. In addition, the transcription factors (TFs) and CpG islands of the gene promoter were searched for using the TRANSFAC database and CpG Island Searcher software, respectively. A total of 323 DEGs were identified between the metastatic and non-metastatic samples. In the PPI network, upregulated epidermal growth factor receptor (EGFR) exhibits a high degree and was therefore highly interconnected with other proteins. Enrichment analysis revealed that EGFR was enriched in cytoskeleton organization, organic substance response and the signaling pathway of focal adhesion. The TFs early growth response 1, nuclear factor-κB complex subunits, peroxisome proliferator activated receptor α, signal transducer and activator of transcription 3 and MYC proto-oncogene were identified in the EGFR promoter region. Furthermore, multiple CpG islands, starting from the 400 bp of the EGFR promoter sequence, were predicted. Methylated modification of the CpG islands in the EGFR promoter may help to regulate EGFR expression. The TFs identified in the EGFR promoter may function in the progression of OS.

Meta-analysis of clinical significance of p53 protein expression in patients with osteosarcoma

AIM

The prognostic role of p53 protein expression in osteosarcoma has been reported, but the results remain conflicting.

MATERIALS & METHODS

The relevant literature databases were searched to get eligible articles published in English. The overall ORs or HRs and their corresponding 95% CIs were calculated.

RESULTS

The results indicated that p53 protein expression was not linked to age factor, gender, tumor grade, cancer metastasis and response to chemotherapy. p53 expression was significantly lower in osteogenic osteosarcoma than in nonosteogenic osteosarcoma (OR = 0.40; p = 0.006). p53 expression was associated with a poor prognosis of patients in overall survival (univariate analysis: HR: 2.49; p < 0.001 and multivariate analysis: HR: 2.92; p < 0.001).

CONCLUSION

p53 expression was correlated with pathological type and may become a useful prognostic biomarker in overall survival in osteosarcoma.

In vitro effect of microRNA-107 targeting Dkk-1 by regulation of Wnt/β-catenin signaling pathway in osteosarcoma

BACKGROUND

The aim of the study was to explore the effects of microRNA-107 (miR-107) by targeting Dkk-1 on osteosarcoma (OS) via the Wnt/β-catenin signaling pathway.

METHODS

OS and adjacent tissues were collected from 67 patients diagnosed with OS. Expressions of miR-107, Dkk-1, LRP5, β-catenin, and c-Myc were detected by the quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. The dual-luciferase reporter gene assay was performed to observe the relationship between miR-107 and Dkk-1.Transfected cells were divided into different investigating groups designated as Inhibitor, Mimic, siRNA, Inhibitor + siRNA, negative control (NC), and blank groups. qRT-PCR and Western blotting were used to detect expressions of miR-107, Dkk-1, β-catenin, Bcl-2, c-Myc, Caspase-3, and PARP. Cell counting kit-8 (CCK-8), flow cytometry (FCM), colony-formation efficiency (CFE), and subcutaneous tumorigenicity assays were all utilized for to determine cell proliferation, apoptosis, colony-forming, and tumorigenic abilities.

RESULTS

Dkk-1 is the target gene of miR-107. Decreased expressions of miR-107, LRP5, β-catenin, and c-Myc, and increased expressions of Dkk-1 were found in OS tissues. The Mimic and siRNA groups exhibited decreased proliferation rates, colony-forming abilities, and tumorigenicity and increased apoptosis rates, whereas the inhibitor group showed opposite trends when compared to the blank group. On the other hand, expressions of miR-107, LRP5, β-catenin, c-Myc, Caspase-3, and PARP were all elevated in the mimic group, whereas expressions of Dkk-1 and Bcl-2 were reduced; opposite trends were observed in the inhibitor group.

CONCLUSION

We conclude that miR-107 is likely to inhibit the occurrence and development of OS by down-regulating Dkk-1 via the Wnt/β-catenin signaling pathway, providing us with a new therapeutic target for the treatment of OS.

Recurrent Osteosarcoma Presenting as an Isolated Bone Marrow Relapse

Osteosarcoma (OS) is a malignant bone tumor which is found primarily in adolescents, with the distal femur as the most common location. OS with a jaw primary is present in only about 10% of cases and the risk of recurrence is considered to be decreased in the jaw versus other primary locations. We present a unique case of a patient with localized OS of the jaw with an isolated recurrence in her bone marrow almost 5 years after completion of initial treatment.

Rb deficiency accelerates progression of carcinoma of the urinary bladder in vivo and in vitro through inhibiting autophagy and apoptosis

Urinary bladder cancer is known as a common cancer diagnosed across the world and results in significant mortality and morbidity rates among patients. The retinoblastoma (Rb) protein, as a main tumor suppressor, controls cellular responses to potentially oncogenic stimulation. Rb phosphorylation could disrupt E2F complex formation, resulting in diverse transcription factor dysfunction. In our study, we investigated how Rb is involved in controlling urinary bladder cancer progression. The results indicate that Rb expression is reduced in mice with urinary bladder tumor, and its suppression leads to urinary bladder cancer progression in vivo and in vitro. Rb mutation directly results in tumor size with lower survival rate in vivo. Rb knockdown in vitro promoted bladder tumor cell proliferation, migration and invasion. Interestingly, Rb knockout and knockdown result in autophagy and apoptosis inhibition via suppressing p53 and caspase-3 signaling pathways, enhancing bladder cancer development in vitro and in vivo. These findings reveal that Rb deficiency accelerated urinary bladder cancer progression, exposing an important role of Rb in suppressing urinary bladder cancer for treatment in the future.

Ferulic acid promoting apoptosis in human osteosarcoma cell lines

OBJECTIVE

To explore the promoting apoptosis and antitumor activities of ferulic acid (FA) in human osteosarcoma and its potential mechanism.

METHODS

The SaOS-2 and MG63 osteosarcoma cell lines were opted to experiment and these cells were, respectively, cultured with various concentrations of FA (0 μM, 10 μM, 20 μM, 40 μM) for 72 hours at 37°C. The viabilities of the FA treated cells were monitored by MTT. Apoptosis cells were evaluated using annexin V/PI by flow cytometry. Apoptosis proteins caspase-3, procaspase-3, Bcl-2 and Bax were detected by western blot. Expressions of apoptotic genes Bcl-2 and Bax were quantified by qPCR.

RESULTS

The cell viabilities were critically declined in the concentration-dependent manner in FA groups (P < 0.01). The apoptosis cells were increased proportionately with the concentration of FA (P < 0.05). The procaspase-3 protein contents, and Bcl-2 mRNA and protein contents were significantly decreased while caspase-3 protein contents, and Bax mRNA and protein contents were concomitantly increased in the concentration-dependent manner in FA groups (P < 0.05). The response to FA by the SaOS-2 osteosarcoma cell was similar with the MG63 osteosarcoma cell (P > 0.05).

CONCLUSION

Ferulic acid could significantly descend osteosarcoma cell viability through the promoting apoptosis pathway in which FA activates both caspase-3 and Bax and inactivates Bcl-2.

MOXIBUSTION ALLEVIATES GASTRIC PRECANCEROUS LESIONS IN RATS BY PROMOTING CELL APOPTOSIS AND INHIBITING PROLIFERATION-RELATED ONCOGENES

Background:

It is well known that gastric mucosa dysplasia and intestinal metaplasia are gastric precancerous lesions (GPL). Moxibustion treatment of Liangmen (ST21) and Zusanli (ST36) alleviated the inflammatory response and dysplasia of gastric mucosa in our previous study. The purpose of this study was to further examine the underlying mechanism of moxibustion treatment of ST21 and ST36 on GPL.

Materials and Methods:

Sixty SD rats were divided into five groups and rats with GPL were treated with either moxibustion (ST), moxibustion (Sham), or vitacoenzyme. B-cell lymphoma 2 (bcl-2), tumor protein p53 (P53) and cellular Myc (C-MYC), which are related to cell apoptosis, proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), argyrophilic nucleolar organizer region proteins (Ag-NORs), which are associated with cell proliferation, and cell signaling proteins, nuclear factor kappa B (NF-κB), epidermal growth factor receptor (EGFR) and phosphorylated extracellular signal regulated kinase (p-ERK), were measured after moxibustion treatment.

Results:

Compared with Control group, gastric mucosa in GPL group showed abnormal mucosal proliferation and pathological mitotic figure, the mRNA expression of bcl-2, P53 and C-MYC increased significantly (P < 0.01), the protein expression of PCNA, VEGF, Ag-NORs and the activity of NF-κβ as well as EGFR/ERK signaling proteins also increased significantly (P < 0.01). Moxibustion treatment decreased gastric mucosal proliferation and pathological mitotic figure, down-regulated the mRNA expression of bcl-2, P53, C-MYC (P < 0.01), decreased the protein expression of PCNA, VEGF, Ag-NORs and the activity of NF-κβ as well as EGFR/ERK signaling proteins significantly (P < 0.01). But moxibustion treatment of Sham didn’t show the same effect on GPL.

Conclusion:

Moxibustion treatment inhibited cell apoptosis and reduced gastric mucosa dysplasia by inhibiting the expression of bcl-2, P53, C-MYC and decreased the activity of NF-κβ as well as EGFR/ERK signaling proteins.

Therapeutic aspects of c-MYC signaling in inflammatory and cancerous colonic diseases

Colonic inflammation is required to heal infections, wounds, and maintain tissue homeostasis. As the seventh hallmark of cancer, however, it may affect all phases of tumor development, including tumor initiation, promotion, invasion and metastatic dissemination, and also evasion immune surveillance. Inflammation acts as a cellular stressor and may trigger DNA damage or genetic instability, and, further, chronic inflammation can provoke genetic mutations and epigenetic mechanisms that promote malignant cell transformation. Both sporadical and colitis-associated colorectal carcinogenesis are multi-step, complex processes arising from the uncontrolled proliferation and spreading of malignantly transformed cell clones with the obvious ability to evade the host’s protective immunity. In cells upon DNA damage several proto-oncogenes, including c-MYC are activated in parelell with the inactivation of tumor suppressor genes. The target genes of the c-MYC protein participate in different cellular functions, including cell cycle, survival, protein synthesis, cell adhesion, and micro-RNA expression. The transcriptional program regulated by c-MYC is context dependent, therefore the final cellular response to elevated c-MYC levels may range from increased proliferation to augmented apoptosis. Considering physiological intestinal homeostasis, c-MYC displays a fundamental role in the regulation of cell proliferation and crypt cell number. However, c-MYC gene is frequently deregulated in inflammation, and overexpressed in both sporadic and colitis-associated colon adenocarcinomas. Recent results demonstrated that endogenous c-MYC is essential for efficient induction of p53-dependent apoptosis following DNA damage, but c-MYC function is also involved in and regulated by autophagy-related mechanisms, while its expression is affected by DNA-methylation, or histone acetylation. Molecules directly targeting c-MYC, or agents acting on other genes involved in the c-MYC pathway could be selected for combined regiments. However, due to its context-dependent cellular function, it is clinically essential to consider which cytotoxic drugs are used in combination with c-MYC targeted agents in various tissues. Increasing our knowledge about MYC-dependent pathways might provide direction to novel anti-inflammatory and colorectal cancer therapies.

Overexpression of KH-type splicing regulatory protein regulates proliferation, migration, and implantation ability of osteosarcoma

Osteosarcoma is a common malignant bone tumor in children and adolescents. The current 5-year survival rate is ~60% and that seems to be reaching a plateau. In order to improve treatment outcomes of osteosarcoma, a better understanding of tumorigenesis and underlying molecular mechanisms is required for searching out possible new treatment targets. This study aimed to identify the potential proteins involving the pathogenesis of osteosarcoma using a proteomics approach. Proteins extracted from primary cell culture of osteosarcoma (n=7) and osteoblasts of cancellous bone (n=7) were studied. Using 2-DE based proteomics and LC-MS/MS analysis, we successfully determined seven differentially expressed protein spots. Four upregulated proteins and three downregulated proteins were observed in this study in which KH-type splicing regulatory protein (KSRP) was selected for further exploration. KSRP was significantly upregulated in osteosarcoma cells compared to osteoblasts using western blot assay. In addition, immunohistochemistry demonstrated that KSRP was also highly expressed in osteosarcoma tissue of independent cases from the experimental group. More importantly, KSRP silencing of osteosarcoma cell lines significantly decreased cell proliferation, migration ability, as well as implantation and growth ability in chick chorioallantoic membrane assay. Taken together, these findings demonstrate, that KSRP plays important roles in regulatory controls of osteosarcoma pathogenesis and serves as a potentially therapeutic target of osteosarcoma.

Ablation of MCL1 expression by virally induced microRNA-29 reverses chemoresistance in human osteosarcomas

Osteosarcoma is a rare disease diagnosed as malignant bone tumor. It is generally refractory to chemotherapy, which contributes to its poor prognosis. The reversal of chemoresistance is a major clinical challenge to improve the prognostic outcome of osteosarcoma patients. We developed a tumor-specific replication-competent oncolytic adenovirus, OBP-301 (telomelysin) and assessed its synergistic effects with chemotherapeutic agents (cisplatin and doxorubicin) using human osteosarcoma cell lines and a xenograft tumor model. The molecular mechanism underlying the chemosensitizing effect of OBP-301 was evaluated in aspects of apoptosis induction. OBP-301 inhibits anti-apoptotic myeloid cell leukemia 1 (MCL1) expression, which in turn leads to chemosensitization in human osteosarcoma cells. The siRNA-mediated knockdown of MCL1 expression sensitized human osteosarcoma cells to common chemotherapeutic agents. We also found that upregulation of microRNA-29 targeting MCL1 via virally induced transcriptional factor E2F-1 activation was critical for the enhancement of chemotherapy-induced apoptosis in osteosarcoma cells. Telomerase-specific oncolytic adenovirus synergistically suppressed the viability of human osteosarcoma cells in combination with chemotherapeutic agents. The combination treatment also significantly inhibited tumor growth, as compared to monotherapy, in an osteosarcoma xenograft tumor model. Our data suggest that replicative virus-mediated tumor-specific MCL1 ablation may be a promising strategy to attenuate chemoresistance in osteosarcoma patients.

TP53 Mutations and Survival in Osteosarcoma Patients: A Meta-Analysis of Published Data

Several research groups have examined the association between TP53 mutations and prognosis in human osteosarcoma. However, the results were controversial. The purpose of this study was to evaluate the prognostic value of TP53 mutations in osteosarcoma patients. A meta-analysis was conducted with all eligible studies which quantitatively evaluated the relationship between TP53 mutations and clinical outcome of osteosarcoma patients. Eight studies with a total of 210 patients with osteosarcoma were included in this meta-analysis. The risk ratio (RR) with a 95% confidence interval (95% CI) was calculated to assess the effect of TP53 mutations on 2-year overall survival. The quantitative synthesis of 8 published studies showed that TP53 mutations were associated with 2-year overall survival in osteosarcoma patients. These data suggested that TP53 mutations had an unfavorable impact on 2-year overall survival when compared to the counterparts with wild type (WT) TP53 (RR: 1.79; 95% CI: 1.12 to 2.84; P = 0.01; I (2) = 0%). There was no between-study heterogeneity. TP53 mutations are an effective prognostic marker for survival of patients with osteosarcoma. However, further large-scale prospective trials should be performed to clarify the prognostic value of TP53 mutations on 3- or 5-year survival in osteosarcoma patients.

Hypoxia-induced apoptosis is blocked by adrenomedullin via upregulation of Bcl-2 in human osteosarcoma cells

Adrenomedullin (ADM), a multifunctional regulatory peptide, is potentially induced by hypoxia in physiological and pathological tissues, including many types of malignant tumors. Recent research has demonstrated that ADM expression is highly associated with the prognosis and disease severity of human osteosarcoma. However, the effect of ADM on the apoptosis of osteosarcoma cells and its possible mechanism remain to be elucidated. In the present study, we observed that mRNA and protein levels of ADM were increased in human osteosarcoma SOSP-F5M2 cells under a hypoxic microenvironment induced by cobalt chloride (CoCl2) in a time-dependent manner. Treatment with ADM significantly blunted hypoxic-induced apoptosis, evaluated by Hoechst 33342 staining and Annexin V-FITC/PI labeling. The expression of B-cell lymphoma-2 (Bcl-2) was increased by administration of ADM; meanwhile, this effect was reversed by exogenously adding U0126, a selective inhibitor of MEK or ADM22-52 (ADM-specific receptor antagonist). These results demonstrated that ADM acted as a survival factor to inhibit hypoxic-induced apoptosis via interacting with its receptors CRLR-RAMP (2,3) in osteosarcoma cells. The anti-apoptotic function of ADM was found to be mediated by upregulation of the expression of Bcl-2 partially through activation of the MEK/ERK1/2 signaling pathway. Therefore, targeting of the ADM/ADM acceptors/ERK1/2/Bcl-2 pathway may provide a potential strategy through which to induce the apoptosis of osteosarcoma cells.

Clinical next generation sequencing of pediatric-type malignancies in adult patients identifies novel somatic aberrations

Pediatric malignancies in adults, in contrast to the same diseases in children are clinically more aggressive, resistant to chemotherapeutics, and carry a higher risk of relapse. Molecular profiling of tumor sample using next generation sequencing (NGS) has recently become clinically available. We report the results of targeted exome sequencing of six adult patients with pediatric-type malignancies : Wilms tumor(n=2), medulloblastoma(n=2), Ewing's sarcoma( n=1) and desmoplastic small round cell tumor (n=1) with a median age of 28.8 years. Detection of druggable somatic aberrations in tumors is feasible. However, identification of actionable target therapies in these rare adult patients with pediatric-type malignancies is challenging. Continuous efforts to establish a rare disease registry are warranted.

Research progress on the multidrug resistance mechanisms of osteosarcoma chemotherapy and reversal

Osteosarcoma (OS) is the most common and aggressive primary malignant type of bone cancer in children and adolescents. Chemotherapy is one of the most important treatments for OS. Although cancer therapy has improved over the past few decades, survival outcomes for OS patients remain unsatisfactory. One of the primary reasons for the failure of current treatments is that patients with stage IV cancer often develop resistance to anticancer agents. This article will review multidrug resistance (MDR) mechanisms of OS and strategies for overcoming resistance.

MicroRNA-33b suppresses migration and invasion by targeting c-Myc in osteosarcoma cells

MicroRNAs have emerged as fundamental regulators in gene expression through silencing gene expression at the post-transcriptional and translational levels. Osteosarcoma is the most common type of primary malignant bone tumor and is characterized by complex genetic changes and resistance to conventional treatments. In our study, the role of miR-33b in the progression and metastasis of osteosarcoma was investigated. Our results showed that miR-33b was significantly downregulated in osteosarcoma tissue and cell lines. Overexpression of miR-33b significantly inhibited cell proliferation, migration, and invasion in the MG-63 osteosarcoma cell line. Moreover, we also showed that c-Myc was negatively regulated by miR-33b at the posttranscriptional level, via a specific target site within the 3′UTR. Overexpression of c-Myc impaired miR-33b-induced inhibition of proliferation and invasion in osteosarcoma cells. The expression of c-Myc was frequently downregulated in osteosarcoma tumors and cell lines and was inversely correlated with miR-33b expression. Thus, our findings suggest that miR-33b inhibits osteosarcoma cells migration and invasion by targeting the c-Myc gene, acting as tumor suppressor. The findings of this study contribute to current understanding of the functions of miR-33b in osteosarcoma.

Correlations of ezrin expression with pathological characteristics and prognosis of osteosarcoma: a meta-analysis

We conducted a meta-analysis to comprehensively evaluate the correlations of ezrin expression with pathological characteristics and the prognosis of osteosarcoma. The MEDLINE (1966–2013), the Cochrane Library Database, EMBASE, CINAHL, Web of Science (1945–2013), and the Chinese Biomedical Database were searched without language restrictions. Meta-analyses conducted using STATA software were calculated. Ten studies met the inclusion criteria, including 459 patients with osteosarcoma. Meta-analysis results illustrated that ezrin expression may be closely associated with the recurrence of osteosarcoma or metastasis in osteosarcoma. Our findings also demonstrated that patients with grade III-IV osteosarcoma showed a higher frequency of ezrin expression than those with histological grade I-II osteosarcoma. Furthermore, we found that patients with positive expression of ezrin exhibited a shorter overall survival than those with negative ezrin expression. The results also indicated that positive ezrin expression was strongly correlated with poorer metastasis-free survival. Nevertheless, no significant relationships were observed between ezrin expression and clinical variables (age and gender). In the current meta-analysis, our results illustrated significant relationships of ezrin expression with pathological characteristics and prognosis of osteosarcoma. Thus, ezrin expression could be a promising marker in predicting the clinical outcome of patients with osteosarcoma.

Proliferation index: a continuous model to predict prognosis in patients with tumours of the Ewing's sarcoma family

The prognostic value of proliferation index (PI) and apoptotic index (AI), caspase-8, -9 and -10 expression have been investigated in primary Ewing's sarcoma family of tumours (ESFT). Proliferating cells, detected by immunohistochemistry for Ki-67, were identified in 91% (91/100) of tumours with a median PI of 14 (range 0-87). Apoptotic cells, identified using the TUNEL assay, were detected in 96% (76/79) of ESFT; the median AI was 3 (range 0-33). Caspase-8 protein expression was negative (0) in 14% (11/79), low (1) in 33% (26/79), medium (2) in 38% (30/79) and high (3) in 15% (12/79) of tumours, caspase-9 expression was low (1) in 66% (39/59) and high (3) in 34% (20/59), and caspase-10 protein was low (1) in 37% (23/62) and negative (0) in 63% (39/62) of primary ESFT. There was no apparent relationship between caspase-8, -9 and -10 expression, PI and AI. PI was predictive of relapse-free survival (RFS; p = 0.011) and overall survival (OS; p = <0.001) in a continuous model, whereas AI did not predict outcome. Patients with tumours expressing low levels of caspase-9 protein had a trend towards a worse RFS than patients with tumours expressing higher levels of caspase-9 protein (p = 0.054, log rank test), although expression of caspases-8, -9 and/or -10 did not significantly predict RFS or OS. In a multivariate analysis model that included tumour site, tumour volume, the presence of metastatic disease at diagnosis, PI and AI, PI independently predicts OS (p = 0.003). Consistent with previous publications, patients with pelvic tumours had a significantly worse OS than patients with tumours at other sites (p = 0.028); patients with a pelvic tumour and a PI≥20 had a 6 fold-increased risk of death. These studies advocate the evaluation of PI in a risk model of outcome for patients with ESFT.

MicroRNA-29b-1 impairs in vitro cell proliferation, self‑renewal and chemoresistance of human osteosarcoma 3AB-OS cancer stem cells

Osteosarcoma (OS) is the most common type of bone cancer, with a peak incidence in the early childhood. Emerging evidence suggests that treatments targeting cancer stem cells (CSCs) within a tumor can halt cancer and improve patient survival. MicroRNAs (miRNAs) have been implicated in the maintenance of the CSC phenotype, thus, identification of CSC-related miRNAs would provide information for a better understanding of CSCs. Downregulation of miRNA-29 family members (miR-29a/b/c; miR-29s) was observed in human OS, however, little is known about the functions of miR-29s in human OS CSCs. Previously, during the characterization of 3AB-OS cells, a CSC line selected from human OS MG63 cells, we showed a potent downregulation of miR-29b. In this study, after stable transfection of 3AB-OS cells with miR-29b-1, we investigated the role of miR-29b-1 in regulating cell proliferation, sarcosphere-forming ability, clonogenic growth, chemosensitivity, migration and invasive ability of 3AB-OS cells, in vitro. We found that, miR-29b-1 overexpression consistently reduced both, 3AB-OS CSCs growth in two- and three-dimensional culture systems and their sarcosphere- and colony-forming ability. In addition, while miR-29b-1 overexpression sensitized 3AB-OS cells to chemotherapeutic drug-induced apoptosis, it did not influence their migratory and invasive capacities, thus suggesting a context-depending role of miR-29b-1. Using publicly available databases, we proceeded to identify potential miR-29b target genes, known to play a role in the above reported functions. Among these targets we analyzed CD133, N-Myc, CCND2, E2F1 and E2F2, Bcl-2 and IAP-2. We also analyzed the most important stemness markers as Oct3/4, Sox2 and Nanog. Real-time RT-PCR and western-blot analyses showed that miR-29b-1 negatively regulated the expression of these markers. Overall, the results show that miR-29b-1 suppresses stemness properties of 3AB-OS CSCs and suggest that developing miR-29b-1 as a novel therapeutic agent might offer benefits for OS treatment.

The tumor-suppressive microRNA-135b targets c-myc in osteoscarcoma

Osteosarcoma is the most common primary tumor of the bone. It leads to many deaths because of its rapid proliferation and metastasis. Recent studies have shown that microRNAs are important gene regulators that are involved in various cancer-related processes. In this study, we found that miR-135b was down-regulated in both osteoscarcoma patient tumor tissues and osteoscarcoma cell lines in comparison to paired adjacent non-tumor bone tissue. We observed that a lower level of miR-135b was associated with metastasis. The ectopic expression of miR-135b markedly suppressed osteoscarcoma cell proliferation, migration, and invasion. Conversely, the inhibition of miR-135b expression dramatically accelerated cell proliferation, migration, and invasion. The forced expression of miR-135b in osteosarcoma cells resulted in a significant reduction in the protein level of c-Myc and repressed the activity of a luciferase reporter that contained the 3′-untranslated region of the c-Myc mRNA. These effects were abolished by the mutation of the predicted miR-135b-binding site, which indicates that c-Myc may be a miR-135b target gene. Moreover, the ectopic expression of c-Myc partially reversed the inhibition of cell proliferation and invasion that was caused by miR-135b. These data therefore suggest that miR-135b may function as a tumor suppressor to regulate osteosarcoma cell proliferation and invasion through a mechanism that targets the c-Myc oncogene. These findings indicate that miR-135b may play a role in the pathogenesis of osteosarcoma.

Theranostic Profiling for Actionable Aberrations in Advanced High Risk Osteosarcoma with Aggressive Biology Reveals High Molecular Diversity: The Human Fingerprint Hypothesis

The survival of patients with advanced osteosarcoma is poor with limited therapeutic options. There is an urgent need for new targeted therapies based on biomarkers. Recently, theranostic molecular profiling services for cancer patients by CLIA-certified commercial companies as well as in-house profiling in academic medical centers have expanded exponentially. We evaluated molecular profiles of patients with advanced osteosarcoma whose tumor tissue had been analyzed by one of the following methods: 1. 182-gene next-generation exome sequencing (Foundation Medicine, Boston, MA), 2. Immunohistochemistry (IHC)/PCR-based panel (CARIS Target Now, Irving, Tx), 3.Comparative genome hybridization (Oncopath, San Antonio, TX). 4. Single-gene PCR assays, PTEN IHC (MDACC CLIA), 5. UT Houston morphoproteomics (Houston, TX). The most common actionable aberrations occur in the PI3K/PTEN/mTOR pathway. No patterns in genomic alterations beyond the above are readily identifiable, and suggest both high molecular diversity in osteosarcoma and the need for more analyses to define distinct subgroups of osteosarcoma defined by genomic alterations. Based on our preliminary observations we hypothesize that the biology of aggressive and the metastatic phenotype osteosarcoma at the molecular level is similar to human fingerprints, in that no two tumors are identical. Further large scale analyses of osteosarcoma samples are warranted to test this hypothesis.

Molecular mechanisms of chemoresistance in osteosarcoma (Review)

Due to the emergence of adjuvant and neoadjuvant chemotherapy, the survival rate has been greatly improved in osteosarcoma (OS) patients with localized disease. However, this survival rate has remained unchanged over the past 30 years, and the long-term survival rate for OS patients with metastatic or recurrent disease remains poor. To a certain extent, the reason behind this may be ascribed to the chemoresistance to anti-OS therapy. Chemoresistance in OS appears to be mediated by numerous mechanisms, which include decreased intracellular drug accumulation, drug inactivation, enhanced DNA repair, perturbations in signal transduction pathways, apoptosis- and autophagy-related chemoresistance, microRNA (miRNA) dysregulation and cancer stem cell (CSC)-mediated drug resistance. In addition, methods employed to circumvent these resistance mechanism have been shown to be effective in the treatment of OS. However, almost all the current studies on the mechanisms of chemoresistance in OS are in their infancy. Further studies are required to focus on the following aspects: i) Improving the delivery of efficacy through novel delivery patterns; ii) improving the understanding of the signal transduction pathways that regulate the proliferation and growth of OS cells; iii) elucidating the signaling pathways of autophagy and its association with apoptosis in OS cells; iv) utilizing high-throughput miRNA expression analysis to identify miRNAs associated with chemoresistance in OS; and v) identifying the role that CSCs play in tumor metastasis and in-depth study of the mechanism of chemoresistance in the CSCs of OS.

Pien Tze Huang induces apoptosis in multidrug‑resistant U2OS/ADM cells via downregulation of Bcl‑2, survivin and P-gp and upregulation of Bax

Pien Tze Huang (PZH) is a well-known traditional Chinese formula that was first prescribed by a royal physician in the Ming Dynasty. PZH has been used to treat various types of cancers including osteosarcoma. Previous studies have shown that PZH may effectively inhibit osteosarcoma cell growth in vivo and in vitro via induction of apoptosis and inhibition of migratory and invasive abilities. However, little is known regarding the effects of PZH on osteosarcomas that are resistant to chemotherapy, which has emerged as a major clinical problem. In the present study, the cellular effects of PZH on multidrug-resistant U2OS/ADM human osteosarcoma cells were investigated. Our results showed that PZH reduced cell viability in a dose- and time-dependent manner and arrested cells in the G2/M phase of the cell cycle, suggesting that PZH inhibits the proliferation of U2OS/ADM cells. Hoechst 33258 staining and Annexin V/propidium iodide double staining revealed typical nuclear features of apoptosis, and treatment with PZH increased the proportion of apoptotic Annexin V-positive cells in a dose-dependent manner. Further experiments demonstrated that apoptosis induction by PZH was accompanied by downregulation of Bcl-2 and survivin and upregulation of Bax. In addition, following treatment with PZH, intracellular Rhodamine 123 accumulation was increased and the expression of P-gp was significantly suppressed. Taken together, these results provide a possible molecular mechanism for the anticancer effect of PZH on U2OS/ADM cells and suggest that PZH may be a potent therapeutic agent for drug-resistant osteosarcoma.

A systematic review of p53 as a biomarker of survival in patients with osteosarcoma

Osteosarcoma is the most common malignant bone tumor, and the prognosis of patients with osteosarcoma is still unsatisfactory with low survival rates. There are many studies assessing the prognostic role of upregulated p53 in patients presenting osteosarcoma, and there is no consistent finding. To summarize the existing evidence about whether the presence of upregulated p53 was a biomarker of survival in patients with osteosarcoma, we performed a systematic review and meta-analysis of relevant publications. We assessed the effect of upregulated p53 on the 3-year overall survival and the 3-year disease-free survival by calculating the pooled odds ratio (OR) with corresponding 95% confidence interval (95%CI). Fifteen studies with a total of 609 patients with osteosarcoma were finally included into the systematic review and meta-analysis. Compared with osteosarcoma patients with low or undetectable p53, patients with upregulated p53 were obviously associated with decreased 3-year overall survival (OR = 0.29, 95 %CI 0.19-0.43, P < 0.001). In addition, patients with upregulated p53 were obviously associated with decreased 3-year disease-free survival (OR = 0.06, 95 %CI 0.02-0.23, P < 0.001). The results from the systematic review and meta-analysis highlight that p53 is an effective biomarker of survival in patients with osteosarcoma. In addition, more studies with a large sample size are needed to identify the effect of p53 expression in osteosarcoma patients.

Bcl-2 correlates with localization but not outcome in human osteosarcoma

bcl-2 is a member of the bcl-2 family that inhibits apoptosis, plays a crucial role in cell viability and is expressed in various types of tumors. With respect to inconsistent results in previous studies, the aim of the present study was to generate a clear hypothesis with regards to the value of bcl-2 expression as a predictive or prognostic factor in human osteosarcoma. The expression of bcl-2 was examined immunohistochemically in 49 patients with high-grade osteosarcoma and the results were correlated with localization, histological response to chemotherapy, survival and the occurrence of metastases. In patients with osteosarcoma, 21/49 cases (43%) were positive for bcl-2 expression and the remaining cases were negative. A significantly higher expression of bcl-2 was observed in central tumors located in the pelvis (83 vs. 37% positive; P<0.05). The bcl-2 expression status revealed no statistically significant correlation with response to chemotherapy, with 57% of patients with bcl-2-positive tumors showing a good response and 43% showing a poor response. No significant difference was observed when comparing survival or occurrence in bcl-2-positive and -negative tumors. In conclusion, the results of the present study indicate that, despite higher bcl-2 expression in central osteosarcoma, the expression in high-grade osteosarcoma is not a reliable prognostic or predictive marker.

Determination of the apoptotic index in osteosarcoma tissue and its relationship with patients prognosis

Background

Nowadays it remains a controversial issue whether a correlation exists between the apoptosis rate of tumor tissue and the prognosis of the patients. We aimed to explore the prognostic significance of apoptosis index of human osteosarcoma tissue.

Methods

The technique of terminal DNA breakpoints in situ 3 - hydroxy end labeling (TUNEL) was used to detect and analysis apoptosis index in 56 osteosarcoma specimens. The relationships between apoptosis index of tumor tissue and long term survival of patients as well as pathologic classification, tumor clinical stages, tumor size and level of serum alkaline phosphatase were analyzed.

Results

Our studies showed the cases with high apoptosis index had significantly longer survival time. Apoptosis index in osteosarcoma tissue was correlated with tumor size and level of serum alkaline phosphatase but not with pathologic classifications and clinical stages of tumor.

Conclusion

Our results demonstrated that apoptosis index of osteosarcoma tissue combined with serum alkaline phosphatase could used as valid indicators to predicate the malignant level and prognosis of osteosarcoma cases, which would contribute to enhance efficacy of clinical treatments for osteosarcoma.