Prognostic value of bax, bcl-2, and p53 staining in primary osteosarcoma

A Systematic Review of the Heterogenous Gene Expression Patterns Associated with Multidrug Chemoresistance in Conventional Osteosarcoma

Multidrug chemoresistance (MDR) remains the most significant obstacle to improving survival in osteosarcoma patients. Heterogeneous genetic alterations characterise the tumour microenvironment, and host molecular markers have been associated with MDR. This systematic review examines the genetic alterations of molecular biomarkers associated with multidrug chemotherapy resistance in genome-wide analysis of central high-grade conventional osteosarcoma (COS). We systematically searched MEDLINE, EMBASE, Web of Science, Wiley online library and Scopus. Only human studies involving genome-wide analysis were included, while candidate gene, in vitro and animal studies were excluded. The risk of bias of the studies was assessed using the Newcastle-Ottawa Quality Assessment Scale. The systematic search identified 1355 records. Following the screening, six studies were included in the qualitative analysis. There were 473 differentially expressed genes (DEGs) associated with chemotherapy response in COS. Fifty-seven of those were associated with MDR in osteosarcoma. The heterogeneous gene expressions were related to the mechanism of MDR in osteosarcoma. The mechanisms include drug-related sensitivity genes, bone remodelling and signal transduction. Complex, variable and heterogenous gene expression patterns underpin MDR in osteosarcoma. Further research is needed to identify the most relevant alterations for prognostication and to guide the development of possible therapeutic targets.

Up-regulation of LINC00619 promotes apoptosis and inhibits proliferation, migration and invasion while promoting apoptosis of osteosarcoma cells through inactivation of the HGF-mediated PI3K-Akt signalling pathway

This study is performed to evaluate the role of long noncoding RNA (lncRNA) LINC00619 in osteosarcoma through the PI3K-Akt signalling pathway by binding to HGF. Osteosarcoma and osteochondroma tissues from patients were collected. The relationship between lncRNA LINC00619 and HGF was proved by the dual-luciferase reporter gene assay. The expression patterns of lncRNA LINC00619 as well as the levels of proliferating cell nuclear antigen (PCNA), hepatocyte growth factor (HGF), phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), Bax, Bcl-2, alkaline phosphatase (ALP), and osteopontin (OPN) were detected by RT-qPCR and Western blot analysis. In addition, MTT assay, flow cytometry, scratch test, and Transwell assay were performed to assess the cell proliferation, cell cycle distribution, apoptosis, cell migration, and invasion in each group, respectively. Osteosarcoma tissues presented with elevated positive expression rate of HGF, up-regulated expression levels of PCNA, HGF, PI3K, Akt, Bcl-2, ALP and OPN, and down-regulated expressions of Bax and LINC00619. HGF was verified as a target gene of lncRNA LINC00619. LINC00619 was found to down-regulate the expressions of PCNA, HGF, PI3K, Akt, Bcl-2, ALP, and OPN in osteosarcoma cells. Up-regulation of lncRNA LINC00619 decreased cell growth, migration intensity, and invasion ability, but enhanced the apoptosis rate of osteosarcoma cells. Our findings suggest that lncRNA LINC00619 inhibits proliferation, migration and invasion and improves apoptosis of osteosarcoma cells through the inhibition of the activation of the HGF-dependent PI3K-Akt signalling pathway.

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.

PRMT5 promotes progression of endometrioid adenocarcinoma via ERα and cell cycle signaling pathways

Protein arginine methyltransferase 5 (PRMT5) has previously been reported to be upregulated in many malignant tumors. This study investigated the significance of PRMT5 in endometrial carcinoma (EC) and explored its function in tumorigenesis. Immunohistochemistry was performed to evaluate PRMT5 expression in 62 EC and 66 endometrial hyperplasia samples. The functions of PRMT5 were investigated by cell counting kit‐8, plate colony formation, wound healing, and transwell and flow cytometry assays. Quantitative reverse transcription‐polymerase chain reaction and western blotting were used to measure the expression of PRMT5, changes in estrogen receptor α (ERα), and related functional proteins. Coimmunoprecipitation was performed to examine the interaction of PRMT5 with ERα and its coactivator steroid receptor coactivator‐1 (SRC1). Compared to endometrial hyperplasia tissue, PRMT5 was overexpressed in endometrioid adenocarcinoma (EAC) but not overexpressed in mucinous EC. The main expression pattern of PRMT5 in EAC was cytoplasmic. However, the positive cases of endometrial hyperplasia showed both cytoplasmic and nuclear positivity in the endometrial glands or were mainly positive in stromal cells. Knockdown of PRMT5 significantly inhibited the growth and migration ability of EAC cells and promoted their apoptosis by regulating cyclin D1, c‐myc, p53, and Bcl2 proteins. Furthermore, PRMT5 could form a complex with ERα and SRC1 to promote the expression of ERα. In conclusion, PRMT5 plays a significant role in the progression of EAC by interacting with ERα and impacting the cell cycle signaling pathways.

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.

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.

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.

Mutant p53 gain of function can be at the root of dedifferentiation of human osteosarcoma MG63 cells into 3AB-OS cancer stem cells

Osteosarcoma is a highly metastatic tumor affecting adolescents, for which there is no second-line chemotherapy. As suggested for most tumors, its capability to overgrow is probably driven by cancer stem cells (CSCs), and finding new targets to kill CSCs may be critical for improving patient survival. TP53 is the most frequently mutated tumor suppressor gene in cancers and mutant p53 protein (mutp53) can acquire gain of function (GOF) strongly contributing to malignancy. Studies thus far have not shown p53-GOF in osteosarcoma. Here, we investigated TP53 gene status/role in 3AB-OS cells-a highly aggressive CSC line previously selected from human osteosarcoma MG63 cells-to evaluate its involvement in promoting proliferation, invasiveness, resistance to apoptosis and stemness. By RT-PCR, methylation-specific PCR, fluorescent in situ hybridization, DNA sequence, western blot and immunofluorescence analyses, we have shown that-in comparison with parental MG63 cells where TP53 gene is hypermethylated, rearranged and in single copy-in 3AB-OS cells, TP53 is unmethylated, rearranged and in multiple copies, and mutp53 (p53-R248W/P72R) is post-translationally modified and with nuclear localization. p53-R248W/P72R-knockdown by short-interfering RNA reduced the growth and replication rate of 3AB-OS cells, markedly increasing cell cycle inhibitor levels and sensitized 3AB-OS cells to TRAIL-induced apoptosis by DR5 up-regulation; moreover, it strongly decreased the levels of stemness and invasiveness genes. We have also found that the ectopic expression of p53-R248W/P72R in MG63 cells promoted cancer stem-like features, as high proliferation rate, sphere formation, clonogenic growth, high migration and invasive ability; furthermore, it strongly increased the levels of stemness proteins. Overall, the findings suggest the involvement of p53-R248W/P72R at the origin of the aberrant characters of the 3AB-OS cells with the hypothesis that its GOF can be at the root of the dedifferentiation of MG63 cells into CSCs.

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.

Prognostic significance of p53 expression in malignant bone tumors: a meta-analysis

Osteosarcoma and Ewing's sarcoma are the two most common primary malignant bone tumors, and findings of prognostic factors are important for clinicians to decide treatment options. High p53 expression has been implicated in tumor development and progression, but studies investigating the prognostic role of p53 overexpression in malignant bone tumors report conflicting findings. We performed a meta-analysis to assess the relationship between p53 overexpression and the survival of malignant bone tumors. A meta-analysis of 13 studies with a total of 703 patients was carried out to evaluate the association between p53 overexpression and overall survival (OS) and disease-free survival (DFS) in patients with malignant bone tumors. The pooled hazard ratio (HR) with its 95 % confidence interval (CI) was used as the effect size estimate. There was no between-study heterogeneity in both OS studies (I (2) = 0.0 %) and DFS studies (I(2) = 0.0 %). Overall, high p53 expression predicted both poor OS (HR 2.13, 95 % CI 1.81-2.52, P < 0.001) and poor DFS (HR 2.06, 95 % CI 1.58-2.69, P < 0.001) in patients with malignant bone tumors. Subgroup analyses by tumor types suggested that p53 expression predicted poor OS in both osteosarcoma patients (HR 2.15, 95 % CI 1.78-2.60, I (2) = 15.2 %, P < 0.001) and Ewing's sarcoma patients (HR 2.09, 95 % CI 1.47-2.97, I(2) = 0.0 %, P < 0.001). Besides, p53 expression also predicted poor DFS in both osteosarcoma patients (HR 2.38, 95 % CI 1.60-3.52, I(2) = 0.0 %, P < 0.001) and Ewing's sarcoma patients (HR 1.83, 95 % CI 1.28-2.63, I(2) = 0.0 %, P = 0.001). Egger's test also did not suggest evidence for publication bias in both OS studies (P = 0.615) and DFS studies (P = 0.258). High p53 expression indicates a poorer prognosis for patients with osteosarcoma and Ewing's sarcoma.

MicroRNA profiling with correlation to gene expression revealed the oncogenic miR-17-92 cluster to be up-regulated in osteosarcoma

Osteosarcomas are genetically complex tumors with abundant structural and numerical alterations. The molecular pathogenesis of the disease is, however, still poorly understood. Aside from various oncogenes and tumor suppressor genes, deregulated microRNAs (miRNAs) are known to influence tumor development and biology. We therefore investigated six well-established osteosarcoma cell lines (HOS58, U2-OS, Saos-2, MNNG/HOS, SJSA-1, and MG-63) for genome-wide miRNA expression (miRBase Version 15.0, http://www.mirbase.org/) and correlated our findings with gene expression. Cultured osteoblasts (hFOB 1.19) and mesenchymal stem cells (L87/4) were used as normal references. Focusing only on miRNAs that were deregulated in the majority of osteosarcoma cell lines, we identified several miRNAs with oncogenic and tumor suppressor properties, including various members of the oncogenic miR-17-92 cluster. In addition, several genes involved in differentiation (RGMB, LRRC17), cell cycle control (CCNE1), and apoptosis (LIMA1, CAMK2N1) were found to be deregulated in osteosarcoma cell lines, most likely due to altered miRNA expression patterns. Our findings indicate a crucial impact of deregulated miRNAs with consecutive changes in gene expression in osteosarcomas, which strongly suggests pathogenetic and potentially therapeutic implications.

PDGFs and PDGFRs in canine osteosarcoma: new targets for innovative therapeutic strategies in comparative oncology

Platelet derived growth factor receptor (PDGFR)α and PDGFRβ are tyrosine kinase receptors that are overexpressed in 70-80% of human osteosarcomas (OSAs) and may be suitable therapeutic targets for specific kinase inhibitors (TKIs). Canine OSA shows histopathological and clinical features similar to human OSA, and is considered an excellent model in comparative oncology. This study investigated PDGF-A, PDGF-B, PDGFRα and PDGFRβ expression in 33 canine OSA samples by immunohistochemistry and in seven primary canine OSA cell lines by Western blot and quantitative PCR analysis. Immunohistochemical data showed that PDGF-A and PDGF-B are expressed in 42% and 60% of the OSAs analysed, respectively, while PDGFRα and PDGFRβ were expressed in 78% and 81% of cases, respectively. Quantitative PCR data showed that all canine OSA cell lines overexpressed PDGFRα, while 6/7 overexpressed PDGFRβ and PDGF-A relative to a normal osteoblastic cell line. Moreover, in vitro treatment with a specific PDGFR inhibitor, AG1296, caused a dose- and time-dependent decrease in AKT phosphorylation. Collectively, these data show that PDGFRs/PDGFs are co-expressed in canine osteosarcomas, which suggests that an autocrine and/or paracrine loop is involved and that they play an important role in the aetiology of OSA. PDGFRs may be suitable targets for the treatment of canine OSA with a specific TKI.

Expression of molecular markers in the tumor and survival prognosis in osteosarcoma

Immunohistochemical study of p53, VEGF, Flt-1/VEGFR1 Ab-1, EGFR, HER-2/neu, Bax, and Cox-2 expression in osteosarcomas was carried out in 40 patients aged 16-70 years. Expression of p53 was detected in 27.5% tumors, VEGF in 15%, Flt-1/VEGFR1 Ab-1 in 97.5%, EGFR in 52.5%, HER-2/neu in 32.5%, Bax in 77.8%, and Cox-2 in 32.3% tumors. Multifactorial analysis showed that the expression of HER-2/neu (p=0.004), p53 (p=0.01), and Cox-2 (p=0.04) in osteosarcomas significantly correlated with unfavorable prognosis for overall survival, while HER-2/neu (p=0.02) and Cox-2 (p=0.003) with relapse-free survival. Analysis of HER-2/neu, p53, and Cox-2 expression in the primary tumor should be taken into consideration in the treatment of patients with osteosarcoma.

Molecular prognosticators of complex karyotype soft tissue sarcoma outcome: a tissue microarray-based study

BACKGROUND

Molecular markers are currently being utilized as sensitive prognosticators of cancer patient outcome. We sought to identify prognostic biomarkers for complex karyotype soft tissue sarcoma (STS).

MATERIALS AND METHODS

A large (n = 205) clinically annotated tissue microarray (TMA) was constructed and immunostained for several tumor-related markers. Staining was scored via an automated Ariol image analysis system; data were statistically analyzed to evaluate the correlation of clinicopathological and molecular variables with overall survival (OS) and local recurrence.

RESULTS

Multivariable analysis identified older age [hazard ratio (HR) 1.62, P < 0.0001], nonextremity location (HR 2.95, P = 0.001), high tumor grade (HR 2.5, P = 0.02), and increased matrix metalloproteinase (MMP) 2 expression (HR 1.74, P = 0.04) as predictors for poor OS. Similarly, older age (HR 1.51, P = 0.008), nonextremity location (HR 4.09, P = 0.001), and increased MMP2 expression (HR 6.28, P = 0.006) were all found to correlate with shorter local recurrence-free interval. High nuclear p53 expression was associated with shorter STS local recurrence-free interval, with a trend toward significance.

CONCLUSIONS

Data presented indicate that a clinically annotated TMA can be utilized to identify STS-related prognostic markers. Specifically, MMP2 and nuclear p53 should be further evaluated for their potential inclusion in complex karyotype STS staging systems.

Immunohistochemical Estimates of Angiogenesis, Proliferative Activity, p53 Expression, and Multiple Drug Resistance Have No Prognostic Impact in Osteosarcoma: A Comparative Clinicopathological Investigation

Purpose. To investigate angiogenesis, multiple drug resistance (MDR) and proliferative activity as prognostic variables in patients suffering from osteosarcoma. Methods. Histologic biopsies from 117 patients treated in the period from 1972 through 1999 were immunohistologically investigated regarding angiogenesis (CD34), proliferative activity (MIB-1), and the expression of p53 and MDR (P-glycoprotein (Pgp); clones JSB-1, C494, and MRK16). Quantitative and semiquantitative scores of immunoreactive cells were analyzed statistically along with retrospectively obtained clinicopathologic variables. Results. Chemotherapy reduced the rate of amputations (P = .00002). The Pgp was overexpressed (score ≥2) in 48% of the primary, diagnostic biopsies, and high Pgp correlated with high Pgp in postsurgical specimens (P = .003). In contrast, no such associations were disclosed for estimates of angiogenesis (P = .64) and p53 (P > .32), whereas the MIB-1 index was reduced in the post-chemotherapy specimens (P = .02). The overall, disease-specific survival was 47%, increasing to 54% in patients receiving pre-operative chemotherapy. Statistical analyses showed prognostic impact exclusively by patient age and type of osteosarcoma. Discussion. The studied series of patients documented already prior to the chemotherapy era, a rather excellent survival and estimates of angiogenesis, proliferation, p53, and Pgp expressions, did not demonstrate sufficient power to serve as predictors of treatment response or survival.

The etiology of osteosarcoma

Studies to determine the etiology of osteosarcoma involve epidemiologic and environmental factors and genetic impairments. Factors related to patient characteristics include age, gender, ethnicity, growth and height, genetic and familial factors, and preexisting bone abnormalities. Rapidly proliferating cells may be particularly susceptible to oncogenic agents and mitotic errors which lead to neoplastic transformation. Genetic aberrations that accompany osteosarcoma have received increasing recognition as an important factor in its etiology. Osteosarcoma tumor cells exhibit karyotypes with a high degree of complexity which has made it difficult to determine whether any recurrent chromosomal aberrations characterize osteosarcoma. Although extremely rare, osteosarcoma has occasionally been observed in several members of the same family. No other clinical abnormalities in the proband or the affected members were reported. Pathologic examination of the tumors revealed no unusual features. Genetic testing was not available in most of these reports. The patients generally responded to conventional therapy. A genetic predisposition to osteosarcoma is found in patients with hereditary retinoblastoma, characterized by mutation of the retinoblastoma gene RB1 on chromosome 13q14. The Rothmund-Thomson syndrome is an autosomal recessive disorder with a heterogeneous clinical profile. Patients may have a few or multiple clinical features including skin rash, small stature, skeletal dysplasias, sparse or absent scalp hair, eyebrows or eyelashes, juvenile cataracts, and gastrointestinal disturbance including chronic emesis and diarrhea; its molecular basis is the mutation in the RECQL4 gene in a subset of cases. The Li-Fraumeni syndrome is an autosomal dominant disorder characterized by a high risk of developing osteosarcoma and has been found in up to 3% of children with osteosarcoma. It is associated with a germline mutation of the p53, a suppressor gene. The following three criteria must be met for a diagnosis of Li-Fraumeni syndrome: (1) A proband diagnosed with sarcoma when younger than 45 years; (2) A first-degree relative with any cancer diagnosed when younger than 45 years; (3) Another first- or second-degree relative of the same genetic lineage with any cancer diagnosed when younger than 45 years or sarcoma diagnosed at any age. A second recessive p53 oncogene on chromosome 17p13.1 may also play a role in the development and progression of osteosarcoma. Osteosarcoma has also been associated with solitary or multiple osteochondroma, solitary enchondroma or enchondromatosis (Ollier's disease), multiple hereditary exostoses, fibrous dysplasia, chronic osteomyelitis, sites of bone infarcts, sites of metallic prostheses and sites of prior internal fixation. Ionizing radiation is a well-documented etiologic factor. Osteosarcoma has also been associated with the use of intravenous radium and Thorotrast. Exposure to alkylating agents may also contribute to its development ,and it is apparently independent of the administration of radiotherapy.

Biomarkers in Osteosarcoma

Osteosarcoma is the most common primary tumor of bone and accounts for approximately 19% of all malignant tumors of bone. It is the third most common malignant tumor in teenagers. More than twenty years ago, the advent of a multidisciplinary approach that combined multi-agent chemotherapy and limb-sparing surgery greatly improved the survival rate of patients with osteosarcoma. Unfortunately, since that time, survival rates have not dramatically improved. To date, the most powerful predictors of outcome have remained the ability to detect metastatic disease at diagnosis and the histopathologic response of the tumor to preoperative chemotherapy. Presently, 80% of patients who do not have distant metastases at initial diagnosis will become long-term survivors. Unfortunately, this means that approximately 20% of patients who do not present with metastases at diagnosis will not survive. This group of patients appears to be resistant to current treatment as attempts to intensify therapy after surgery for patients with a poor histopathologic response has not significantly improved survival rates. It is these patients that are in the greatest need of additional clinically relevant markers for prognosis and who can be most helped by molecular analysis. While steady progress has been made in the identification of genetic alterations in osteosarcoma, no individual molecular marker has thus far been demonstrated to have a better prognostic significance in the treatment of osteosarcomas than the current clinical markers. Thus there is clearly a need to employ new comprehensive analysis technologies to develop significantly more informative classification systems and to identify new therapeutic targets.