A 20-year retrospective analysis of CT-based pre-operative identification of pulmonary metastases in patients with osteosarcoma: A single-center review

Predictors of pulmonary metastases on chest computed tomography in children and adolescents with osteosarcoma-tips for qualifying patients for thoracotomy

BACKGROUND

Osteosarcoma is the most common primary malignant bone tumour in children and adolescents. Lungs are the most frequent and often the only site of metastatic disease. The presence of pulmonary metastases is a significant unfavourable prognostic factor. Thoracotomy is strongly recommended in these patients, while computed tomography (CT) remains the gold imaging standard. The purpose of our study was to create tools for the CT-based qualification for thoracotomy in osteosarcoma patients in order to reduce the rate of useless thoracotomies.

METHODS

Sixty-four osteosarcoma paediatric patients suspected of lung metastases on CT and their first-time thoracotomies (n = 100) were included in this retrospective analysis. All CT scans were analysed using a compartmental evaluation method based on the number and size of nodules. Calcification and location of lung lesions were also analysed. Inter-observer reliability between two experienced radiologists was assessed. The CT findings were then correlated with the histopathological results of thoracotomies. Various multivariate predictive models (logistic regression, classification tree and random forest) were built and predictors of lung metastases were identified.

RESULTS

All applied models proved that calcified nodules on the preoperative CT scan best predict the presence of pulmonary metastases. The rating of the operated lung on the preoperative CT scan, dependent on the number and size of nodules, and the total number of nodules on this scan were also found to be important predictors. All three models achieved a relatively high sensitivity (72-92%), positive predictive value (81-90%) and accuracy (74-79%). The positive predictive value of each model was higher than of the qualification for thoracotomy performed at the time of treatment. Inter-observer reliability was at least substantial for qualitative variables and excellent for quantitative variables.

CONCLUSIONS

The multivariate models built and tested in our study may be useful in the qualification of osteosarcoma patients for metastasectomy through thoracotomy and may contribute to reducing the rate of unnecessary invasive procedures in the future.

Primary Multi-Systemic Metastases in Osteosarcoma: Presentation, Treatment, and Survival of 83 Patients of the Cooperative Osteosarcoma Study Group

BACKGROUND

To evaluate patient and tumour characteristics, treatment, and their impact on survival in patients with multi-systemic metastases at initial diagnosis of high-grade osteosarcoma. Precedure: Eighty-three consecutive patients who presented with multi-systemic metastases at initial diagnosis of high-grade osteosarcoma were retrospectively reviewed. In cases of curative intent, the Cooperative Osteosarcoma Study Group recommended surgical removal of all detectable metastases in addition to complete resection of the primary tumour and chemotherapy.

RESULTS

Eighty-three eligible patients (1.8%) were identified among a total of 4605 individuals with high-grade osteosarcoma. Nine (10.8%) of these achieved complete surgical remission, of whom seven later had recurrences. The median follow-up time was 12 (range, 1-165) months for all patients. Actuarial event-free survival after 1, 2, and 5 years was 9.6 ± 3.2%, 1.4 ± 1.4%, and 1.4 ± 1.4%, and overall survival was 54.0 ± 5.6%, 23.2 ± 4.9%, and 8.7 ± 3.3%. In univariate analyses, elevated alkaline phosphatase before chemotherapy, pleural effusion, distant bones as metastatic sites, and more than one bone metastasis were negative prognostic factors. Among treatment-related factors, the microscopically complete resection of the primary tumour, a good response to first-line chemotherapy, the macroscopically complete resection of all affected tumour sites, and local treatment (surgery ± radiotherapy) of all bone metastases were associated with better outcomes. Tumour progression under first-line treatment significantly correlated with shorter survival times.

CONCLUSION

The outlook for patients with multi-systemic primary metastases from osteosarcoma remains very poor. The utmost importance of surgical resection of all tumour sites was confirmed. For unresectable bone metastases, radiotherapy might be considered. In the patient group studied, standard chemotherapy was often insufficiently effective. In the case of such advanced disease, alternative treatment options are urgently required.

Improving survival after pulmonary metastasectomy for sarcoma: analysis of prognostic factors

BACKGROUND

Metastatic sarcoma confers a grave prognosis to patients and poses a management dilemma for clinicians. Pulmonary metastasectomy is frequently performed for the recurrence of sarcomatous tumours in the lung, but the evidence-base is poor. No guidelines exist to inform clinicians on appropriate patient selection and surgical technique.

AIM

This review aims to establish and analyse the most important prognostic factors for survival post pulmonary metastasectomy for recurrent sarcoma. We summarise the key tumour, peri-operative and patient characteristics that should guide surgical management.

METHODS

A comprehensive search of the literature utilising OVID Medline and PubMed databases was conducted to identify all relevant research within the past 15 years. We evaluated all articles that specifically studied sarcoma patients (both bone and soft tissue).

CONCLUSION

Disease-free interval and tumour burden remain important prognostic factors, while tumour grade is likely not significant. VATS is a safe and viable alternative to thoracotomy without sacrificing survival outcomes. No single peri-operative characteristic provides useful prognostic information in isolation.

The Role of a Multidisciplinary Team in the Diagnosis and Treatment of Bone and Soft Tissue Sarcomas: A Single-Center Experience

Bone and soft tissue sarcomas with complex and varied clinical, imaging, and pathological characteristics cannot be diagnosed and treated by a single discipline, as each discipline has some limitations. This study aimed to explore the role of a multidisciplinary team (MDT) in the diagnosis and treatment of bone and soft tissue sarcomas over the past four consecutive years. The subjects were 269 patients discussed during MDT meetings at a Bone and Soft Tissue Sarcomas Center in South China. The diagnosis, relapse diagnosis, unplanned resection, management of pulmonary nodules, and treatment of refractory and advanced tumors were compared to similar data provided in the literature to (i) determine whether the MDT significantly affected the diagnosis and treatment of bone and soft tissue sarcomas, and (ii) explore trends in the types of patients with bone and soft tissue sarcomas and treatment decision-making since the establishment of the MDT. Results revealed that the MDT significantly improved preoperative diagnostic accuracy for patients with bone and soft tissue sarcomas; the accuracy of diagnosis and relapse diagnosis by the MDT reached 95.42% and 100%, respectively. After an MDT discussion, the positive pathology rate for extended resection after unplanned resection was 81.2%. The overall accuracy of the MDT in determining the nature of pulmonary nodules was 87.1-91.9%. For patients presenting with pulmonary nodules in osteosarcoma, no statistically significant difference in survival was shown between cases discussed by the MDT and those without an MDT discussion (p = 0.5751). Collectively, the MDT can play a positive role in accurate preoperative diagnosis, relapse diagnosis, the decision to extend resection after an unplanned resection, and the diagnostic accuracy of pulmonary nodules.

Prognostic impact of pulmonary nodules diagnosed at initial presentation in patients with osteosarcoma

BACKGROUND

Resection of all lung metastases in patients with osteosarcoma improves survival. The increased computed tomography (CT) scan quality allows detecting smaller nodules. We aimed to evaluate the prognostic impact of those nodules that do not meet the classical criteria for lung metastases.

METHODS

A central radiology review (CRR) on lung CT scans performed during the treatment of patients included in OS2006 trial and treated with a high-dose methotrexate-based chemotherapy from 2007 to 2013 was realized in three centers.

RESULTS

At trial enrollment, among 77 patients, six (8%) had nodules meeting the trial's criteria for metastatic disease, 46 (60%) were classified as having localized disease, and 25 (32%) as having doubtful nodules. After CRR, 218 nodules were found at diagnosis (all in patients classified as "metastatic or doubtful" and 13 patients classified as "localized") (median two nodules per patient [1-52]). The 5-year event-free survival/overall survival (EFS/OS) of patients with at least one nodule versus no nodule were similar (67.7%/79.2% vs. 81.8%/91%). After histological analysis, two of 46 (4.3%) "localized" and eight of 25 (32.0%) "doubtful" patients were re-classified as "metastatic," whereas there was no change in patients initially "metastatic." The 5-year OS of confirmed histological metastatic versus nonmetastatic patients were different (56% vs. 92%, p < .01).

CONCLUSION

Central review of lung CT scan increased the detection of nodules in osteosarcoma. Patients with small lung nodules classified as doubtful had a quite similar outcome as those with a localized disease. However, patients with confirmed metastatic nodules have a poorer prognosis, even if considered as "localized" at diagnosis.

Metastatic Progression of Osteosarcomas: A Review of Current Knowledge of Environmental versus Oncogenic Drivers

Simple Summary

Osteosarcomas are heterogeneous bone tumors with complex genetic and chromosomic alterations. The numerous patients with metastatic osteosarcoma have a very poor prognosis, and only those who can have full surgical resection of the primary tumor and of all the macro metastasis can survive. Despite the recent improvements in prediction and early detection of metastasis, big efforts are still required to understand the specific mechanisms of osteosarcoma metastatic progression, in order to reveal novel therapeutic targets.

Abstract

Metastases of osteosarcomas are heterogeneous. They may grow simultaneously with the primary tumor, during treatment or shortly after, or a long time after the end of the treatment. They occur mainly in lungs but also in bone and various soft tissues. They can have the same histology as the primary tumor or show a shift towards a different differentiation path. However, the metastatic capacities of osteosarcoma cells can be predicted by gene and microRNA signatures. Despite the identification of numerous metastasis-promoting/predicting factors, there is no efficient therapeutic strategy to reduce the number of patients developing a metastatic disease or to cure these metastatic patients, except surgery. Indeed, these patients are generally resistant to the classical chemo- and to immuno-therapy. Hence, the knowledge of specific mechanisms should be extended to reveal novel therapeutic approaches. Recent studies that used DNA and RNA sequencing technologies highlighted complex relations between primary and secondary tumors. The reported results also supported a hierarchical organization of the tumor cell clones, suggesting that cancer stem cells are involved. Because of their chemoresistance, their plasticity, and their ability to modulate the immune environment, the osteosarcoma stem cells could be important players in the metastatic process.

Prognostic significance of the ratio of surgically resected to radiologically detected lung nodules in patients with metastatic osteosarcoma

The factors that affect the prognosis of patients' metastatic osteosarcoma are still poorly understood. In this study, we investigated a new prognostic factor, the ratio of surgically resected to radiologically detected osteosarcoma lung nodules (SR/RD), which may have predictive value.

PATIENTS AND METHODS

Data from patients with metastatic osteosarcoma who underwent metastasectomy between January 2009 and December 2020, in a single center, were reviewed. The relationships between survival and the SR/RD ratio, timing of lung metastases, number of nodules, laterality, and presence of tumor necrosis at first metastasectomy were investigated.

RESULTS

Among the 125 metastatic osteosarcoma patients, 80 patients had an SR/RD ratio ≤1. The median duration of follow-up was 72 months, ranging from 6 to 118 months. The five-year overall survival (OS) and postmetastasectomy event-free survival (EFS) for all patients were 36.5% and 18.1%, respectively. The five-year OS of patients with a low SR/RD ratio was 49.6% and that of patients with a high SR/RD ratio was 11.8 (P = 0.001). The two-year postmetastasectomy EFS rates of the high and low ratio groups were 24.1% and 9.4%, respectively (P = 0.001). The SR/RD ratio, number of nodules, and tumor necrosis had significant effects on OS and postmetastasectomy EFS in univariate analysis. A Cox proportional hazard model demonstrated that tumor necrosis and an SR/RD ratio >1 were associated with OS (HR = 1.8 and 2.01) and postmetastasectomy EFS (HR = 1,69 and 1.97).

CONCLUSIONS

A high SR/RD ratio of greater than 1 and poor tumor necrosis were significantly associated with poor survival among patients with metastatic osteosarcoma who had lung metastasectomy. The high SR/RD ratio may be a surrogate outcome for incomplete metastatic tumor resection.

The diagnosis of pulmonary metastases on chest computed tomography in primary bone sarcoma and musculoskeletal soft tissue sarcoma

The lungs are the commonest site of metastasis for primary high-grade bone and soft tissue sarcoma, but current guidelines on the management of pulmonary nodules do not specifically cater for this group of patients. The current article reviews the literature from the past 20 years that has reported the CT features of pulmonary metastases in the setting of known primary bone and soft tissue sarcoma, with emphasis on osteosarcoma, chondrosarcoma, and trunk and extremity soft tissue sarcoma, the aim being to aid radiologists who report chest CT of musculoskeletal sarcoma patients in deciding which lesions should be considered metastatic, which lesions are indeterminate and require follow-up, and which lesions are of no concern.

What Effect Do Pulmonary Micronodules Detected at Presentation in Patients with Osteosarcoma Have on 5-Year Overall Survival?

For osteosarcoma, staging criteria, prognosis estimates, and surgical recommendations have not yet changed to reflect increasingly sensitive computed tomography (CT) imaging. However, the frequent identification of micronodules (<5 mm) on presentation leaves clinicians in a difficult position regarding the need to biopsy, resect, or follow the lesions and whether to consider the patient metastatic or non-metastatic. Our objective was to compare the 5-year overall survival rates of patients with osteosarcoma with non-surgically resected lung micronodules on presentation to patients without micronodules to guide community oncologists faced with this common dilemma. We collected data retrospectively on all newly diagnosed osteosarcoma patients, aged less than 50, treated at Rush University Hospital over 25 years without pulmonary nodules >10 mm or pulmonary surgical intervention. Kaplan–Meier curves showed there was no difference in 5-year overall survival in patients with any size nodule <5 mm compared to patients with no nodules. Additionally, our study showed a survival advantage for those who presented with 0 or 1 nodule (90%) compared to ≥2 nodules (53%). Our data suggest surgery may not be necessary for singular nodules <5 mm identified on presentation, and that these patients behave more like “localized” patients than metastatic patients.

Radiologic Assessment of Osteosarcoma Lung Metastases: State of the Art and Recent Advances

The lung is the most frequent site of osteosarcoma (OS) metastases, which are a critical point in defining a patient’s prognosis. Chest computed tomography (CT) represents the gold standard for the detection of lung metastases even if its sensitivity widely ranges in the literature since lung localizations are often atypical. ESMO guidelines represent one of the major references for the follow-up program of OS patients. The development of new reconstruction techniques, such as the iterative method and the deep learning-based image reconstruction (DLIR), has led to a significant reduction of the radiation dose with the low-dose CT. The improvement of these techniques has great importance considering the young-onset of the disease and the strict chest surveillance during follow-up programs. The use of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT is still controversial, while volume doubling time (VDT) and computer-aided diagnosis (CAD) systems are recent diagnostic tools that could support radiologists for lung nodules evaluation. Their use, well-established for other malignancies, needs to be further evaluated, focusing on OS patients.

Utility of fast non-local means (FNLM) filter for detection of pulmonary nodules in chest CT for pediatric patient

PURPOSE

This study was aimed to evaluate the utility based on imaging quality of the fast non-local means (FNLM) filter in diagnosing lung nodules in pediatric chest computed tomography (CT).

METHODS

We retrospectively reviewed the chest CT reconstructed with both filtered back projection (FBP) and iterative reconstruction (IR) in pediatric patients with metastatic lung nodules. After applying FNLM filter with six h values (0.0001, 0.001, 0.01, 0.1, 1, and 10) to the FBP images, eight sets of images including FBP, IR, and FNLM were analyzed. The image quality of the lung nodules was evaluated objectively for coefficient of variation (COV), contrast to noise ratio (CNR), and point spread function (PSF), and subjectively for noise, sharpness, artifacts, and diagnostic acceptability.

RESULTS

The COV was lowest in IR images and decreased according to increasing h values and highest with FBP images (P < 0.001). The CNR was highest with IR images, increased according to increasing h values and lowest with FBP images (P < 0.001). The PSF was lower only in FNLM filter with h value of 0.0001 or 0.001 than in IR images (P < 0.001). In subjective analysis, only images of FNLM filter with h value of 0.0001 or 0.001 rarely showed unacceptable quality and had comparable results with IR images. There were less artifacts in FNLM images with h value of 0.0001 compared with IR images (p < 0.001).

CONCLUSION

FNLM filter with h values of 0.0001 allows comparable image quality with less artifacts compared with IR in diagnosing metastatic lung nodules in pediatric chest CT.

Thoracoscopy vs thoracotomy for the management of metastatic osteosarcoma: A Pediatric Surgical Oncology Research Collaborative Study

Complete surgical resection of pulmonary metastatic disease in patients with osteosarcoma is crucial to long-term survival. Open thoracotomy allows palpation of nodules not identified on imaging but the impact on survival is unknown. The objective of this study was to compare overall survival (OS) and pulmonary disease-free survival (DFS) in children who underwent thoracotomy vs thoracoscopic surgery for pulmonary metastasectomy. A multi-institutional collaborative group retrospectively reviewed 202 pediatric patients with osteosarcoma who underwent pulmonary metastasectomy by thoracotomy (n = 154) or thoracoscopy (n = 48). Results were analyzed by Kaplan-Meier survival estimates and multivariate Cox proportional hazard regression models. With median follow-up of 45 months, 135 (67.5%) patients had a pulmonary relapse and 95 (47%) patients were deceased. Kaplan-Meier analysis showed no significant difference in 5-year pulmonary DFS (25% vs 38%; P = .18) or OS (49% vs 42%, P = .37) between the surgical approaches of thoracotomy and thoracoscopy. In Cox regression analysis controlling for other factors impacting outcome, there was a significantly increased risk of mortality (HR 2.11; P = .027; 95% CI 1.09-4.09) but not pulmonary recurrence (HR 0.96; P = .90; 95% CI 0.52-1.79) with a thoracoscopic approach. However, in the subset analysis limited to patients with oligometastatic disease, thoracoscopy had no increased risk of mortality (HR 1.16; P = .62; 0.64-2.11). In conclusion, patients with metastatic osteosarcoma and limited pulmonary disease burden demonstrate comparable outcomes after thoracotomy and thoracoscopy for metastasectomy. While significant selection bias in these surgical cohorts limits the generalizability of the conclusions, clinical equipoise for a randomized clinical trial in patients with oligometastatic disease is supported.

Distinction and Potential Prediction of Lung Metastasis in Patients with Malignant Primary Osseous Spinal Neoplasms

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

The aim of this study was to develop and validate a nomogram for the prediction of lung metastasis in patients with malignant primary spinal tumors.

SUMMARY OF BACKGROUND DATA

In patients with malignant primary spinal tumors, lung metastasis is usually found by computed tomography (CT) and is considered to be an essential factor affecting the prognosis and survival.

METHODS

We retrospectively collected 580 malignant primary osseous spinal neoplasms patients from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015. The least absolute shrinkage and selection operator (LASSO) and multivariate logistic analysis were used to identify independent factors. These prognostic factors were included in the nomograms. The nomograms were validated based on its calibration, discrimination, and clinical utility. The overall survival of the patients was analyzed using the Kaplan-Meier method and the survival differences were tested by the log-rank test.

RESULTS

We randomly divided all these patients (n = 580) into a training cohort (n = 408) and a validation cohort (n = 172). The results showed that the risk of lung metastasis was independently influenced by histologic type, use of surgery, clinical T stage, clinical N stage, and tumor extension (all P < 0.05). The nomogram consisted of five clinical features and provided good calibration and discrimination in the training and validation cohort, with an area under the curve of 0.858 and 0.811, respectively. Decision curve analysis showed that the nomogram was clinically useful. The Kaplan-Meier curves showed a significant difference between the higher and lower risk of lung metastasis groups (P < 0.001).

CONCLUSION

Nomograms were developed to predict the risk of lung metastasis in patients with malignant primary spinal tumors. The nomogram showed favorable discrimination and calibration values, which may help optimize treatment decision-making for patients.

LEVEL OF EVIDENCE

4.

Association of high PDPN expression with pulmonary metastasis of osteosarcoma and patient prognosis

Podoplanin (PDPN) is an important positive regulator of platelet aggregation and functions as a lymphatic endothelial marker. PDPN has been observed to be expressed in human tumor tissues and various cancer cell lines. In the present study, PDPN expression in patients with primary osteosarcoma was assessed at the mRNA and protein levels, and the associations between PDPN expression and pulmonary metastasis (PM) and prognosis were examined. Reverse transcription-quantitative PCR (RT-qPCR) analysis was used to detect the expression levels of PDPN in primary osteosarcoma tissues and paired normal bone tissues (n=20 pairs). In addition, immunohistochemical analysis of PDPN expression was performed in 168 paraffin-embedded osteosarcoma tissue specimens and 23 matched normal tissues. The RT-qPCR results revealed higher mRNA expression levels of PDPN in patients with PM compared with patients without PM. Further survival analyses identified Enneking stage and PM as two independent prognostic indicators. Finally, univariate analysis revealed that high PDPN protein expression was significantly associated with Enneking stage and PM in patients with osteosarcoma.

Pulmonary Metastasectomy in Pediatric Solid Tumors

Metastatic disease and the complications of treating metastatic disease are the primary causes of mortality in children with solid malignancies. Nearly 25% of children with solid tumors have metastatic disease at initial diagnosis and another 20% develop metastases during or after treatment. The most common location of these metastases is the lung. The role of surgery in metastatic disease depends greatly on the histology of the primary. In general, tumors that are refractory to adjuvant therapies are most appropriate for pulmonary metastasectomy. This article will summarize the indications for metastasectomy in pediatric solid tumors and discuss the ongoing debate over the technique of metastasectomy in osteosarcoma.

Minimally Invasive Approaches to Pediatric Solid Tumors

Over the last decade, driven in part by the favorable adult experience and a crescendoing number of case series and retrospective reports in the pediatric surgical literature, minimally invasive surgical (MIS) approaches are increasingly used as adjunctive or definitive surgical treatments for an ever-expanding list of pediatric tumors. Although most current treatment protocols lack surgical guidelines regarding the use of MIS, this growing body of MIS literature provides a framework for the development of multicenter trial groups, prospective registries, and further centralization of subspecialist services. This article highlights the current available data on MIS approaches to a variety of pediatric malignancies.

Bone morphogenetic protein and activin membrane-bound inhibitor suppress bone cancer progression in MG63 and SAOS cells via regulation of the TGF-β-induced EMT signaling pathway

Bone cancer is one of the most common tumor types that occurs in bones and their affiliated tissues. The prognosis remains poor due to the limited number of effective therapeutic targets. Downregulation of bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) has been observed in human cancer cells and BAMBI reconstitution can inhibit growth and metastasis of human cancer cells. In the present study, a potential mechanism mediated by BAMBI in osteosarcoma cells was investigated. The data demonstrated that BAMBI reconstitution suppressed the cell growth, migration and invasion of the osteosarcoma cell lines SAOS2 and MG63. Alterations to the epithelial-to-mesenchymal transition (EMT) marker expression were observed in BAMBI-treated osteosarcoma SAOS2 and MG63 cells. The apoptosis rate of SAOS2 and MG63 cells induced by cisplatin were increased in BAMBI-treated osteosarcoma SAOS2 and MG63 cells via downregulation of the anti-apoptosis genes P16, P21 and B-cell lymphoma 2. The potential mechanism investigated indicated that BAMBI administration downregulated the transforming growth factor-β (TGF-β) signaling pathway, whilst knockdown of BAMBI upregulated the TGF-β signaling pathway in SAOS2 and MG63 cells. Reconstitution of BAMBI in SAOS2 and MG63 cells resulted in a notable reduction of TGF-β-induced EMT, cell growth, migration and invasion in vitro. In conclusion, the results demonstrated that BAMBI reconstitution inhibited growth and invasiveness of osteosarcoma, as well as promoted the apoptotic sensibility, which indicated that the TGF-β-induced EMT signaling pathway may be regarded as a potential target for osteosarcoma therapy.

Pulmonary metastases in children: are we operating unnecessarily?

OBJECTIVE

to determine, in pediatric patients with malignant neoplasms, the characteristics of pulmonary nodules identified on computed tomography, as well as the possibility of differentiating benign lesions from metastases.

METHODS

we conducted a retrospective study of patients submitted to pulmonary resections of nodules diagnosed as metastases in a period of seven years. We compared computed tomography and surgery findings, as well as results of anatomopathological examinations.

RESULTS

we studied nine patients submitted to 11 surgical interventions. Among the studied variables, only nodule size greater than 12.5mm proved to be statistically significant to predict malignancy.

CONCLUSION

among the tomographic characteristics of pulmonary nodules in children with malignant neoplasms, only the size of the lesion was a predictor of malignancy.

Effect of Period 2 on the proliferation, apoptosis and migration of osteosarcoma cells, and the corresponding mechanisms

Period 2 (per2) is a core circadian clock gene. Dysregulation of the per2 gene has been identified in a number of types of human cancer and may be associated with a poor prognosis. To confirm the influence of per2 gene on MNNG/HOS human osteosarcoma cells, small interfering (si)RNA against per2 or plasmids containing per2 were transfected into MNNG/HOS cells, and the proliferation, apoptosis and migration were observed. The present study demonstrated that per2 knockdown significantly enhanced MNNG/HOS cell proliferation and migration and protected MNNG/HOS cells from apoptosis. Per2 overexpression inhibited MNNG/HOS cell proliferation and migration and promoted apoptosis. Furthermore, the protein expression of phosphorylated (p)-protein kinase B (Akt) and Bcl-2 were inhibited in per2-overexpressing cells, while the expression of p27, p21 and cleaved caspase-3 was promoted. In contrast, the expression of p-Akt and Bcl-2 was promoted in per2-knockdown cells, and p27, p21 and cleaved caspase-3 were decreased. This initial study may provide an alternative therapeutic strategy for the treatment of osteosarcoma.

Peroxiredoxin-1 promotes cell proliferation and metastasis through enhancing Akt/mTOR in human osteosarcoma cells

Osteosarcoma is characterized by high propensity for metastasis, especially to the lung, which is the main cause of death. Peroxiredoxin-1 (PRDX1) plays significant roles in multiple processes of initiation and progression of tumorogenesis. However, whether PRDX1 participates in metastasis of osteosarcoma remains unknown. Here, we demonstrate that PRDX1 overexpressed in osteosarcoma tissues comparing to adjacent non-tumor tissues. Two independent cohorts of patients showed high level of PRDX1 correlated with clinicopathological features such as larger tumor size and advanced tumor metastasis stage. While patients with high PRDX1 level have poor prognosis. Notably, expression level of PRDX1 especially increased in lung lesion of osteosarcoma patients, indicating that PRDX1 may promote lung metastasis. Ectopic expression of PRDX1 promotes osteosarcoma cell migration and metastasis in vitro and in vivo, whereas knockdown of PRDX1 expression suppresses cell metastatic behaviors such as invasion and migration. Furthermore, we found that PRDX1 promotes cells metastasis through enhancing Akt/mTOR signal pathway. Taken together, our findings prove the important role of PRDX1 in the molecular etiology of osteosarcoma and suggest that PRDX1 may be a novel prognostic biomarker and therapeutic target for osteosarcoma.