Genetic alterations in primary osteosarcoma from 54 children and adolescents by targeted allelotyping

Therapeutic potential of tyrosine-protein kinase MET in osteosarcoma

Osteosarcoma, the most prevalent primary bone tumor in children and young adults, can often be successfully treated with standard chemotherapy and surgery when diagnosed at an early stage. However, patients presenting with metastases face significant challenges in achieving a cure. Despite advancements in classical therapies over the past few decades, clinical outcomes for osteosarcoma have not substantially improved. Recently, there has been increased understanding of the biology of osteosarcoma, leading to the identification of new therapeutic targets. One such target is MET, a tyrosine kinase receptor for Hepatocyte Growth Factor (HGF) encoded by the MET gene. In vitro and in vivo studies have demonstrated that the HGF/MET pathway plays a crucial role in cancer growth, invasion, metastasis, and drug resistance across various cancers. Clinical trials targeting this pathway are already underway for lung cancer and hepatocellular carcinoma. Moreover, MET has also been implicated in promoting osteosarcoma progression. This review summarizes 3 decades' worth of research on MET's involvement in osteosarcoma and further explores its potential as a therapeutic target for patients with this disease.

In vivo self-assembly and delivery of VEGFR2 siRNA-encapsulated small extracellular vesicles for lung metastatic osteosarcoma therapy

The prognosis of lung metastatic osteosarcoma (OS) remains disappointing. siRNA-based gene silencing of VEGFR2 is a promising treatment strategy for lung metastatic OS, but there is a lack of safe and efficient delivery systems to encapsulate siRNAs for in vivo administration. This study presented a synthetic biological strategy that remolds the host liver with synthesized genetic circuits for efficient in vivo VEGFR2 siRNA delivery. After being taken-up by hepatocytes, the genetic circuit (in the form of a DNA plasmid) reprogrammed the liver to drive the autonomous intrahepatic assembly and encapsulation of VEGFR2 siRNAs into secretory small extracellular vesicles (sEVs), thus allowing for the transport of self-assembled VEGFR2 siRNAs towards the lung. The results showed that our strategy was superior to the positive medicine (Apatinib) for OS lung metastasis in terms of therapeutic efficacy and toxic adverse effects and may provide a feasible and viable therapeutic solution for lung metastatic OS.

Exploring the landscape of immunotherapy approaches in sarcomas

Sarcomas comprise a heterogenous group of malignancies, of more than 100 different entities, arising from mesenchymal tissue, and accounting for 1% of adult malignancies. Surgery, radiotherapy and systemic therapy constitute the therapeutic armamentarium against sarcomas, with surgical excision and conventional chemotherapy, remaining the mainstay of treatment for local and advanced disease, respectively. The prognosis for patients with metastatic disease is dismal and novel therapeutic approaches are urgently required to improve survival outcomes. Immunotherapy, is a rapidly evolving field in oncology, which has been successfully applied in multiple cancers to date. Immunomodulating antibodies, adoptive cellular therapy, cancer vaccines, and cytokines have been tested in patients with different types of sarcomas through clinical trials, pilot studies, retrospective and prospective studies. The results of these studies regarding the efficacy of different types of immunotherapies in sarcomas are conflicting, and the application of immunotherapy in daily clinical practice remains limited. Additional clinical studies are ongoing in an effort to delineate the role of immunotherapy in patients with specific sarcoma subtypes.

Engineering Novel 3D Models to Recreate High-Grade Osteosarcoma and its Immune and Extracellular Matrix Microenvironment

Osteosarcoma (OS) is the most common primary bone cancer, where the overall 5-year surviving rate is below 20% in resistant forms. Accelerating cures for those poor outcome patients remains a challenge. Nevertheless, several studies of agents targeting abnormal cancerous pathways have yielded disappointing results when translated into clinic because of the lack of accurate OS preclinical modeling. So, any effort to design preclinical drug testing may consider all inter-, intra-, and extra-tumoral heterogeneities throughout models mimicking extracellular and immune microenvironment. Therefore, the bioengineering of patient-derived models reproducing the OS heterogeneity, the interaction with tumor-associated macrophages (TAMs), and the modulation of oxygen concentrations additionally to recreation of bone scaffold is proposed here. Eight 2D preclinical models mimicking several OS clinical situations and their TAMs in hypoxic conditions are developed first and, subsequently, the paired 3D models faithfully preserving histological and biological characteristics are generated. It is possible to shape reproducibly M2-like macrophages cultured with all OS patient-derived cell lines in both dimensions. The final 3D models pooling all heterogeneity features are providing accurate proliferation and migration data to understand the mechanisms involved in OS and immune cells/biomatrix interactions and sustained such that engineered 3D preclinical systems will improve personalized medicine.

Targeting the VEGF Pathway in Osteosarcoma

Osteosarcoma is the most common primary tumor of the bones affecting mainly young adults. Despite the advances in the field of systemic anticancer therapy, the prognosis of relapsed of metastatic osteosarcoma patients remain dismal with very short survival. However, the better understanding of the pathophysiology of this subtype of sarcoma has led to the identification of new targeted agents with significant activity. In fact, increased angiogenesis plays a major role in the tumor growth and survival of osteosarcoma patients. Several targeted agents have demonstrated a significant anti-tumor activity including multi-kinase inhibitors. In this review, we will discuss the pathophysiology, rationale, and role of targeting angiogenesis via the VEGF pathway in patients with osteosarcoma with emphasis on the published clinical trials and future directions.

Osteosarcoma: a review of current and future therapeutic approaches

Osteosarcoma (OS) is the most common primary bone malignancy that affects children and young adults. OS is characterized by a high degree of malignancy, strong invasiveness, rapid disease progression, and extremely high mortality rate; it is considered as a serious threat to the human health globally. The incidence of OS is common in the metaphysis of long tubular bones, but rare in the spine, pelvis, and sacrum areas; moreover, majority of the OS patients present with only a single lesion. OS has a bimodal distribution pattern, that is, its incidence peaks in the second decade of life and in late adulthood. We examine historical and current literature to present a succinct review of OS. In this review, we have discussed the types, clinical diagnosis, and modern and future treatment methods of OS. The purpose of this article is to inspire new ideas to develop more effective therapeutic options.

Computer Navigation and 3D Printing in the Surgical Management of Bone Sarcoma

The long-term outcomes of osteosarcoma have improved; however, patients with metastases, recurrence or axial disease continue to have a poor prognosis. Computer navigation in surgery is becoming ever more commonplace, and the proposed advantages, including precision during surgery, is particularly applicable to the field of orthopaedic oncology and challenging areas such as the axial skeleton. Within this article, we provide an overview of the field of computer navigation and computer-assisted tumour surgery (CATS), in particular its relevance to the surgical management of osteosarcoma.

Therapeutic potential of targeting HSPA5 through dual regulation of two candidate prognostic biomarkers ANXA1 and PSAT1 in osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor that mostly affects young people's health. The prognosis of patients with unresectable or recurrent osteosarcoma still remains dismal. Based on gene integration analysis from GEO and TARGET databases by R language, the differentially expressed genes of osteosarcoma patients were identified. Biological molecular function analysis indicated that these genes were importantly enriched in the process of cell adhesion molecule binding. Gene significance highly-related to clinical traits of osteosarcoma was found by weighted gene co-expression network analysis. Additionally, receiver operating characteristic curve analysis was conducted to find prognostic markers in LASSO Cox regression model. Two candidate biomarkers, ANXA1 and PSAT1, for the prognosis of osteosarcoma were detected separately on the basis of WGCNA and LASSO model. Of note, their expression profiles were interrelated with an important therapeutic target HSPA5. In vitro pharmaceutical experiments were performed to explore the biological role and prognostic benefit of candidates. Suppression of HSPA5 effectively upregulated ANXA1 and inhibited PSAT1, resulting in osteosarcoma cell proliferation arrest and apoptosis. These findings suggest that HSPA5 serves as a core molecule for osteosarcoma therapy due to its bidirectional regulation of candidate prognostic biomarkers ANXA1 and PSAT1.

SFCE-RAPIRI Phase I Study of Rapamycin Plus Irinotecan: A New Way to Target Intra-Tumor Hypoxia in Pediatric Refractory Cancers

Simple Summary

More and more relapsing or refractory pediatric cancers are described to present hypoxic features linked to a worse outcome. Therefore, the aim of our phase I study RAPIRI was the targeting of the central node mTor/HIF-1α with rapamycin plus irinotecan and determine the appropriated dose of this combination. As expected, the tolerance was optimal across all dose levels and no maximum tolerated dose of both drugs was reached. The pharmacokinetics (PK) helped us to refine the doses to use in the future phase II trial and the importance of PK follow-up in such combination. We also confirmed in almost half of the interpretable patients for tumor response a non-progressive disease. All those observations additionally to the ancillary’s studies provide strong evidence to propose a next trial focusing on brain tumors and sarcomas and using biweekly 125 mg/m² irinotecan dose with a PK follow-up and a rapamycin dose of 1.5 mg/m²/day, reaching a blood concentration above 10 µg/L.

Abstract

Hypoxic environment is a prognostic factor linked in pediatric cancers to a worse outcome, favoring tumor progression and resistance to treatments. The activation of mechanistic Target Of Rapamycin (mTor)/hypoxia inducible factor (HIF)-1α pathway can be targeted by rapamycin and irinotecan, respectively. Therefore, we designed a phase I trial associating both drugs in pediatric refractory/relapsing solid tumors. Patients were enrolled according to a 3 + 3 escalation design with ten levels, aiming to determine the MTD (maximum tolerated dose) of rapamycin plus irinotecan. Rapamycin was administered orally once daily in a 28-day cycle (1 to 2.5 mg/m²/day), associating biweekly intravenous irinotecan (125 to 240 mg/m²/dose). Toxicities, pharmacokinetics, efficacy analyses, and pharmacodynamics were evaluated. Forty-two patients, aged from 2 to 18 years, were included. No MTD was reached. Adverse events were mild to moderate. Only rapamycin doses of 1.5 mg/m²/day reached over time clinically active plasma concentrations. Tumor responses and prolonged stable disease were associated with a mean irinotecan area under the curve of more than 400 min.mg/L. Fourteen out of 31 (45.1%) patients had a non-progressive disease at 8 weeks. Most of them were sarcomas and brain tumors. For the phase II trial, we can then propose biweekly 125 mg/m² irinotecan dose with a pharmacokinetic (PK) follow-up and a rapamycin dose of 1.5 mg/m²/day, reaching a blood concentration above 10 µg/L.

The potentiality of immunotherapy for sarcomas: a summary of potential predictive biomarkers

Sarcomas are rare and heterogeneous malignant tumors of mesenchymal origin. A total of 25-50% of patients treated with initial curative intent will develop as recurrent and metastatic disease. In the recurrent and metastatic setting, effect of chemotherapy is limited; therefore, more effective therapies are urgently desired. As a brake for activation of T cell, PD-1/PD-L1 plays a crucial role in the progression of tumor by altering status of immune surveillance. Some success has been acquired recently in the use of PD-1/PD-L1 inhibitors for the treatment of several solid tumors, for examples, non-small-cell lung cancer and melanoma. Immunotherapeutic strategies based on PD-1/PD-L1 for sarcomas have also been explored these years. As in other cancers, major challenges are identification of biomarkers to predict response for immunotherapy, optimization of patient's benefit and minimization of side effects. Therefore, we focused on potential biomarkers of immunotherapy for treatment of sarcomas in this review.

Cyclooxygenase-2 expression correlates with development, progression, metastasis, and prognosis of osteosarcoma: a meta-analysis and trial sequential analysis

Cyclooxygenase‐2 (COX‐2), a key enzyme in arachidonic acid metabolism, is involved in several cancers, including osteosarcoma. The prognostic significance of COX‐2 in osteosarcoma remains controversial. This study was to analyze the potential clinical and prognostic effects of COX‐2 protein expression in patients with osteosarcoma. Eligible articles were searched via online databases. The combined odds ratios (ORs) or hazard ratios (HRs) with their 95% confidence intervals (95% CIs) were calculated using the random‐effects model. Trial sequential analysis (TSA) was applied to analyze the required information size and determine the reliability of the evidence. Twenty‐three studies on COX‐2 expression were identified, which included a total of 1084 patients with malignant osteosarcoma and 247 patients with benign osteochondroma. COX‐2 protein expression in osteosarcoma was higher than in benign osteochondroma (OR = 7.66, P < 0.001). COX‐2 expression was not correlated with age, gender, tumor location, cancer histology, or necrosis (P > 0.1), but was significantly associated with tumor grade (high grade vs. low grade: OR = 4.81, P < 0.001), clinical stage (stage 3–4 vs. stage 1–2: OR = 4.89, P < 0.001), and metastasis (yes vs. no: OR = 3.53, P < 0.001). Based on TSA results, we suggest that additional studies are not required to examine osteosarcoma vs. benign osteochondroma, tumor grade, clinical stage, or metastasis. No heterogeneity was observed in these analyses. COX‐2 expression is linked to poor prognosis in metastasis‐free survival, overall survival, and relapse‐free survival, as indicated by multivariate analysis. Therefore, the expression of COX‐2 may correlate with the development, progression, metastasis, and poor prognosis of osteosarcoma.

P16 protein expression as a useful predictive biomarker for neoadjuvant chemotherapy response in patients with high-grade osteosarcoma: A systematic meta-analysis under guideline of PRISMA

BACKGROUND

Neoadjuvant chemotherapy for patients with high-grade osteosarcoma has highly improved the clinical survival. However, the prognostic and predictive role of P16 expression after neoadjuvant chemotherapy remains unclear. We first determined whether P16 expression can become a potential prognostic and predictive biomarker in high-grade osteosarcoma.

METHODS

This meta-analysis was conducted based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline. Eligible studies were pooled and the overall odds ratios (ORs) and hazard ratios (HRs) with the corresponding 95% confidence intervals (95% CIs) were calculated in this analysis.

RESULTS

Four studies involving a total of 527 patients with high-grade osteosarcoma receiving neoadjuvant chemotherapy were identified. We did not find that P16 expression was correlated with sex status, histologic subtype, and tumor site (P > .1). P16 expression was found to be significantly associated with a "good" response to neoadjuvant chemotherapy (OR = 4.69, P < .001). A significant relationship was observed between p16 expression and pathologic complete response after neoadjuvant chemotherapy using multivariate analysis (OR = 9.63, P = .001). The expression of the P16 was not associated with clinical outcomes in overall survival (OS) and disease-free survival (DFS) by multivariate analysis (OS: P = .448; DFS: P = .263).

CONCLUSIONS

The use of P16 expression could become a promising predictive biomarker of the response to neoadjuvant chemotherapy in the white population with high-grade osteosarcoma. However, it was not correlated with the prognosis of patients in OS and DFS. More clinical researches are very essential in Asians in the future.

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.

Metastatic osteosarcoma: a challenging multidisciplinary treatment

Osteosarcoma is the most common malignant bone tumor, currently treated with pre-and postoperative chemotherapy in association with the surgical removal of the tumor. About 15-20% of patients have evidence of metastases at diagnosis, mostly in the lungs. Patients with metastatic disease still have a very poor prognosis, with approximately 20-30% of long-term survivors, as compared with 65-70% of patients with localized disease. The optimum management of these patients has not been standardized yet due to several patterns of metastatic disease harboring different prognosis. Complete surgical resection of all sites of disease is mandatory and predictive of survival. Patients with multiple sites of disease not amenable to complete surgery removal should be considered for innovative therapeutic approaches because of poor prognosis.

Prognostic implications of RB1 tumour suppressor gene alterations in the clinical outcome of human osteosarcoma: a meta-analysis

Primary osteosarcoma is the most frequent malignant bone cancer in children and teenagers. Genetic alterations at the retinoblastoma 1 (RB1) gene has been implicated in the development and progression of human osteosarcoma. Here, we performed a meta-analysis to examine the impact of RB1 mutations on the survival of osteosarcoma patients, the risk of metastasis and the histological response of osteosarcoma to chemotherapy. A systemic review of the Medline, Embase, Scopus and Cochrane Library yielded 12 eligible studies with 491 patients for this study. Forest plots resulting from our meta-analyses illustrate that loss of RB1 function results in a 1.62-fold increase in the mortality rate for osteosarcoma patients (RR = 1.62, 95% CI: 1.23-2.13; Z = 3.44, P = 0.0006), a significant increase in osteosarcoma metastasis (OR = 3.95, 95% CI: 1.86-8.38; Z = 3.57; P = 0.0004), and a significant reduction in the histological response of osteosarcoma to chemotherapy (OR = 0.35; 95% CI: 0.13-0.94; Z = -2.08; P = 0.038). Additionally, the nearly symmetrical funnel plot (Egger's test, t = 1.15, P = 0.288) indicates absence of publication bias regarding the meta-analysis that examined the correlation of RB1 alterations with the survival rate for osteosarcoma patients. Our findings suggest that RB1 alterations may serve as a prognostic marker for the management of osteosarcoma patients.

Prognostic value of p53 alterations in human osteosarcoma: a meta analysis

Tumor suppressor gene p53 functions as the guardian of the human genome and mutations in p53 contribute to cancer development. However, studies that investigated the potential of p53 as a prognostic marker in osteosarcoma patients have yielded inconclusive results. Based on recommendation of the Cochrane Collaboration, this meta-analysis was conducted using data from the 17 published studies to evaluate the association of p53 alterations with clinical outcome of osteosarcoma patients. Different databases, including MEDLINE, PsycINFO, Scopus, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched. Prognostic value of p53 alterations was determined by risk ratio (RR). The data showed that p53-positive immunostaining tended to associate with decreased 2-year survival rates (RR, 1.94; 95% CI, 1.43 to 2.64; p < 0.0001, I(2) = 10%). However, the prediction value of RR was smaller with p53 expression than with p53 mutations. Moreover, patients who received neoadjuvant chemotherapy and surgery tended to have a stronger association between p53-positive staining and 2-year mortality compared to the patients treated with surgery only. However, p53-positive staining was not associated with 3-year (RR, 1.64; 95% CI, 0.84 to 3.20; P = 0.15; I(2) = 56%) and 5-year survival (RR, 1.25; 95% CI, 0.78 to 2.01; P = 0.36; I(2) = 70%). The data from the current study suggest that p53-positive osteosarcoma only predicted a decreased short-term survival rate, but not 3- or 5-year survival.

Osteosarcoma treatment - where do we stand? A state of the art review

Long-term outcome for patients with high-grade osteosarcoma has improved with the addition of systemic chemotherapy, but subsequent progress has been less marked. Modern, multiagent, dose-intensive chemotherapy in conjunction with surgery achieves a 5-year event-free survival of 60-70% in extremity localized, non-metastatic disease. A major, as yet unsolved, problem is the poor prognosis for metastatic relapse or recurrence, and for patients with axial disease. This article reviews the current state of the art of systemic osteosarcoma therapy by focusing on the experiences of cooperative osteosarcoma groups. Also, we shed light on questions and challenges posed by the aggressiveness of the tumor, and we consider potential future directions that may be critical to progress in the prognosis of high-grade osteosarcoma.

Role of Topoisomerases in Pediatric High Grade Osteosarcomas: TOP2A Gene Is One of the Unique Molecular Biomarkers of Chemoresponse

Currently, the treatment of pediatric high-grade osteosarcomas systematically includes one topoisomerase IIα inhibitor. This chemotherapy is usually adapted to the response to the neo-adjuvant therapy after surgery. The current and unique marker of chemoresponsiveness is the percentage of viable residual cells in the surgical resection. This late patient management marker has to be evaluated earlier in the therapeutic history of the patients on initial biopsy. Therefore, new biomarkers, especially those involved in the topoisomerase IIα inhibitor response might be good candidates. Therefore, our study was designed to target TOP1, TOP2A and TOP2B genes in 105 fresh-frozen diagnostic biopsies by allelotyping and real-time quantitative PCR. Our analyses in those pediatric osteosarcomas, homogeneously treated, highlighted the frequent involvement of topo-isomerase genes. The main and most important observation was the statistical link between the presence of TOP2A amplification and the good response to neo-adjuvant chemotherapy. Compared to adult cancers, the 17q21 amplicon, including TOP2A and ERBB2 genes, seems to be differentially implicated in the osteosarcoma chemoresponsiveness. Surprisingly, there is no ERBB2 gene co-amplification and the patients harboring TOP2A amplification tend to show a worse survival, so TOP2A analyses remain a preliminary, but a good molecular approach for the evaluation at diagnosis of pediatric osteosarcoma chemoresponsiveness.

Microsatellite instability in sarcoma: fact or fiction?

Microsatellite instability (MSI) is a unique molecular abnormality, indicative of a deficient DNA mismatch repair (MMR) system. Described and characterized in the colorectal cancer literature, the MSI-positive phenotype is predictive of disease susceptibility, pathogenesis, and prognosis. The clinical relevance of MSI in colorectal cancer has inspired similar inquisition within the sarcoma literature, although unfortunately, with very heterogeneous results. Evolving detection techniques, ill-defined sarcoma-specific microsatellite loci and small study numbers have hampered succinct conclusions. The literature does suggest that MSI in sarcoma is observed at a frequency similar to that of sporadic colorectal cancers, although there is little evidence to suggest that MSI-positive tumors share distinct biological attributes. Emerging evidence in Ewing sarcoma has demonstrated an intriguing mechanistic role of microsatellite DNA in the activation of key EWS/FLI-target genes. These findings provide an alternative perspective to the biological implications of microsatellite instability in sarcoma and warrant further investigation using sophisticated detection techniques, sensitive microsatellite loci, and appropriately powered study designs.

Mutations in the mitochondrial ATPase6 gene are frequent in human osteosarcoma

To explore the polymorphisms and mutations of mitochondrial ATPase6 gene in Chinese patients with osteosarcoma and their possible association with carcinogenesis, direct DNA sequencing method was used to detect the variants of the mitochondrial ATPase6 gene in 39 patients with osteosarcoma. We found mutations of the mitochondrial ATPase6 gene in 24/39 (61.5%) of the tested osteosarcoma samples, and identified 27 variant sites in ATPase6 coding regions. We did not detect any new polymorphisms in osteosarcoma, nor was there any association between variants and the three histopathological subtypes. These data demonstrated that mtDNA mutations within the ATPase6 gene are a frequent event in Chinese patients with osteosarcoma.

Targeted apc;twist double-mutant mice: a new model of spontaneous osteosarcoma that mimics the human disease

TWIST and adenomatosis polyposis coli (APC) are critical signaling factors in normal bone development. In previous studies examining a homogeneously treated cohort of pediatric osteosarcoma patients, we reported the frequent and concurrent loss of both TWIST and APC genes. On these bases, we created a related animal model to further explore the oncogenic cooperation between these two genes. We performed intercrosses between twist-null/+ and Apc1638N/+ mice and studied their progeny. The Apc1638N/+;twistnull/+ mice developed bone abnormalities observed by macroscopic skeletal analyses and in vivo imaging. Complementary histologic, cellular, and molecular analyses were used to characterize the identified bone tumors, including cell culture and immunofluorescence of bone differentiation markers. Spontaneous localized malignant bone tumors were frequently identified in Apc1638N/+;twist-null/+ mice by in vivo imaging evaluation and histologic analyses. These tumors possessed several features similar to those observed in human localized osteosarcomas. In particular, the murine tumors presented with fibroblastic, chondroblastic, and osteoblastic osteosarcoma histologies, as well as mixtures of these subtypes. In addition, cellular analyses and bone differentiation markers detected by immunofluorescence on tumor sections reproduced most murine and human osteosarcoma characteristics. For example, the early bone differentiation marker Runx2, interacting physically with hypophosphorylated pRb, was undetectable in these murine osteosarcomas, whereas phosphorylated retinoblastoma was abundant in the osteoblastic and chondroblastic tumor subtypes. These characteristics, similar to those observed in human osteosarcomas, indicated that our animal model may be a powerful tool to further understand the development of localized osteosarcoma.

Cause and consequences of genetic and epigenetic alterations in human cancer

Both genetic and epigenetic changes contribute to development of human cancer. Oncogenomics has primarily focused on understanding the genetic basis of neoplasia, with less emphasis being placed on the role of epigenetics in tumourigenesis. Genomic alterations in cancer vary between the different types and stages, tissues and individuals. Moreover, genomic change ranges from single nucleotide mutations to gross chromosomal aneuploidy; which may or may not be associated with underlying genomic instability. Collectively, genomic alterations result in widespread deregulation of gene expression profiles and the disruption of signalling networks that control proliferation and cellular functions. In addition to changes in DNA and chromosomes, it has become evident that oncogenomic processes can be profoundly influenced by epigenetic mechanisms. DNA methylation is one of the key epigenetic factors involved in regulation of gene expression and genomic stability, and is biologically necessary for the maintenance of many cellular functions. While there has been considerable progress in understanding the impact of genetic and epigenetic mechanisms in tumourigenesis, there has been little consideration of the importance of the interplay between these two processes. In this review we summarize current understanding of the role of genetic and epigenetic alterations in human cancer. In addition we consider the associated interactions of genetic and epigenetic processes in tumour onset and progression. Furthermore, we provide a model of tumourigenesis that addresses the combined impact of both epigenetic and genetic alterations in cancer cells.

Avaliação funcional dos pacientes portadores de sarcomas ósseos submetidos à tratamento cirúrgico utilizando a endoprótese total ou parcial, na substituição da extremidade distal do fêmur

OBJETIVO: O Osteosarcoma e o Sarcoma de Ewing são as principais neoplasias malignas primárias ósseas, que acometem indivíduos menores de 15 anos. O objetivo deste estudo é comparar, retrospectivamente, os resultados funcionais dos pacientes submetidos à ressecção da extremidade distal do fêmur e à reconstrução com endoprótese não convencional, total ou parcial, do joelho. MÉTODOS: Foram analisados 26 pacientes portadores de sarcomas ósseos da extremidade distal do fêmur, acompanhados no Centro Infantil Boldrini, no período de 1990 a 2003. Vinte e quatro eram portadores de Osteossarcoma e 2 de Sarcoma de Ewing. O sistema de avaliação foi o proposto por Enneking (1987), preconizado pela Musculoskeletal Tumor Society. Para a comparação das médias entre cada critério e também entre os escores finais, utilizou-se o teste de Wilcoxon, com erro alfa de 5%. RESULTADOS: A idade variou de 5 a 17 anos, média=11,9 anos. A predominância foi no sexo feminino (61,5%). Na avaliação funcional, a comparação entre as médias de cada critério, foi encontrada diferença estatisticamente significativa somente relacionada ao item estabilidade (p=0,0037). Nos demais critérios, não foi observado diferença estatisticamente significativa: movimento (p=0,7546), dor (p=0,4848), deformidade (p=0,8695), força (p=1,0000), atividade funcional (p=0,9127) e resultado funcional (p=0,5866). CONCLUSÕES: O escore final global da avaliação funcional não apresentou diferença estatisticamente significativa (p=0,6027). O tipo de endoprótese utilizado para reconstrução do fêmur não interferiu nos resultados funcionais dos pacientes.

Involvement of MET/TWIST/APC combination or the potential role of ossification factors in pediatric high-grade osteosarcoma oncogenesis

Dysregulated cell growth or differentiation due to misexpression of developmental critical factors seems to be a decisive event in oncogenesis. As osteosarcomas are histologically defined by malignant osteoblasts producing an osteoid component, we prospected in pediatric osteosarcomas treated with OS94 protocol the genomic status of several genes implied in ossification processes. In 91 osteosarcoma cases, we focused on the analysis of the fibroblast growth factor receptors (FGFRs) TWIST, APC, and MET by allelotyping, real-time quantitative polymerase chain reaction, gene sequencing, and protein polymorphism study. Our study supports the frequent role of TWIST, APC, and MET as osteosarcoma markers (50%, 62%, and 50%, respectively). TWIST and MET were mainly found to be deleted, and no additional APC mutation was identified. Surprisingly, FGFRs are abnormal in only < 30%. Most of these factors and their abnormalities seem to be linked more or less to one clinical subgroup, but the most significant correlation is the link of MET, TWIST, and APC abnormalities to a worse outcome and their combination within abnormal tumors. A wider cohort is mandatory to define more robust molecular conclusions, but these results are to be considered as the beginning of a more accurate basis for diagnosis, in search of targeted therapies, and to further characterize prognostic markers.

Comparative genomic hybridization analysis of abnormalities in chromosome 21 in childhood osteosarcoma

Osteosarcomas (OS) are aggressive tumors of the bone and often have a poor prognosis. The tumors exhibit karyotypes with a high degree of complexity, which has made it difficult to determine whether any recurrent chromosomal aberrations characterize OS. To address inherent difficulties associated with classical cytogenetic analysis, comparative genomic hybridization (CGH) was applied to OS tissue. Forty-one pediatric OS specimens were analyzed by a CGH technique: 24 female and 17 male patients, with a median age of 12 years and 4 months. Chromosomal abnormalities were highly diverse and variable, including gains of chromosome 1p, 2p, 3q, 5q, 5p, and 6p and losses of 14q (50% in 14q11.2), 15q, and 16p. A high level of losses of chromosome 21 was present (26/41 cases; P = 0.008), most often loss of the 21q11.2 approximately 21 region. These novel findings in chromosome 21 of pediatric OS tumors suggest that specific sequences mapping to these chromosomal regions are likely to play a role in the development of OS.

Frequent genomic abnormalities at TWIST in human pediatric osteosarcomas

The identification of genes as markers for chromosome aberrations in specific tumors might facilitate oncogenesis mechanism comprehension, cancer detection, prediction of clinical outcomes, and response to therapy. Previous physiologic and oncologic data identified the TWIST gene as a marker for mesodermal derivative and bone tissue differentiation, but its contribution to bone malignancies has not been investigated. In the present study, search for genomic alterations in high-grade pediatric osteosarcomas was focused on the 7p21 region, and more specifically on the TWIST gene. In a cohort of 74 patients, we observed by allelotyping that 31 of 68 informative tumors were rearranged at the TWIST locus. Among them, analysis by quantitative PCR (QPCR) revealed that, surprisingly, mostly deletions (22/68), but also amplifications (9/68), of the TWIST gene were detected. Furthermore, deletions at TWIST were statistically correlated to other molecular abnormalities, like alterations at the APC or c-kit loci, as well as to clinical features such as a poor outcome. This work shows that the TWIST gene seemed to be involved in high-grade pediatric osteosarcomas and is a new marker with a possible initial predictive value.

Prognostic Significance of Allelic Imbalance at the c-kit Gene Locus and c-kit Overexpression by Immunohistochemistry in Pediatric Osteosarcomas

Purpose

Since the recent development of biologic agents targeting oncogenes, increasing attention has been focused on determining the role of tyrosine kinase receptors in the pathogenesis of tumors. Our study was designed to investigate the status of region 4q12, which contains the candidate gene c-kit, and the expression of c-kit by immunohistochemistry (IHC).

Patients and Methods

Paired blood and biopsy specimens of 68 children treated for high-grade primary osteosarcomas were collected. Microsatellite analysis at two genomic sites containing c-kit gene was performed on paired DNA using a sensible fluorescent polymerase chain reaction technology. To confirm the DNA data, we studied c-kit protein expression by IHC in 56 available paraffin-embedded tumor tissues.

Results

The frequency of allelic imbalance (AI) at locus 4q12 was 39% in the overall population. In agreement with previous studies, we did not detect microsatellite instability, allowing us to hypothesize that this pathway is not implicated. Furthermore, the normal status at locus 4q12 was associated with a significantly better survival in the whole osteosarcoma population (P = .05). IHC overexpression of c-kit was concordant in all cases presenting an AI. However, normal status at locus 4q12 was correlated to an absence of c-kit protein expression in 19 (65.5%) of 29 informative cases.

Conclusion

Allelotyping of locus 4q12, which contains the c-kit gene, could help pediatric osteosarcoma prognostic screening and showed a strong correlation with overexpression of c-kit protein. These results allowed us to hypothesize that, in some cases, a mutation of c-kit gene could lead to a protein overexpression.

Prognostic Significance of Tumor Suppressor Gene Expression and Mutations in Human Osteosarcoma

Purpose: Various studies examining the relationship between tumor suppressor protein TP53 overexpression and/or TP53 gene mutations and the response to chemotherapy and clinical outcome in patients with osteosarcoma have yielded inconclusive results. The purpose of the current study was to evaluate the relation of TP53 status with response to chemotherapy and/or clinical outcome in osteosarcoma.

Experimental Design: We conducted a meta-analysis of 16 studies (n = 499 patients) that evaluated the correlation between TP53 status and histologic response to chemotherapy and 2-year survival. Data were synthesized in summary receiver operating characteristic curves and with summary likelihood ratios (LRs) and risk ratios.

Results: The quantitative synthesis showed that TP53 status is not a prognostic factor for the response to chemotherapy. The positive LR was 1.21 (95% confidence interval, 0.86–1.71), and the negative LR was 0.91 (95% confidence interval, 0.77–1.07). There was no significant between-study heterogeneity. TP53-positive status tended to be associated with a worse 2-year survival, but the overall results were not formally statistically significant. The association was formally significant in studies that clearly stated that measurements were blinded to outcomes (risk ratio, 2.05; 95% confidence interval, 1.23–3.44), and in studies using reverse transcription-PCR for evaluating TP53 alterations (risk ratio, 1.76; 95% confidence interval, 1.07–2.91).

Conclusions: TP53 status is not associated with the histologic response to chemotherapy in patients with osteosarcoma, whereas TP53 gene alterations may be associated with decreased survival.