Tao Xiao

miR-125b suppresses the proliferation and migration of osteosarcoma cells through down-regulation of STAT3.

There is accumulating evidence that microRNAs are involved in multiple processes in development and tumor progression. Abnormally expressed miR-125b was found to play a fundamental role in several types of cancer; however, whether miR-125b participates in regulating the initiation and progress of osteosarcoma still remains unclear. Here we demonstrate that miR-125b is frequently down-regulated in osteosarcoma samples and human osteosarcoma cell lines. The ectopic restoration of miR-125b expression in human osteosarcoma cells suppresses proliferation and migration in vitro and inhibits tumor formation in vivo. We further identified signal transducer and activator of transcription 3 (STAT3) as the direct and functional downstream target of miR-125b. Interestingly, we discovered that the expression of miR-125b is regulated by STAT3 at the level of transcription. STAT3 binds to the promoter region of miR-125b in vitro and serves as a transactivator. Taken together, our findings point to an important role in the molecular etiology of osteosarcoma and suggest that miR-125b is a potential target in the treatment of osteosarcoma.

Microarray expression profile of long noncoding RNAs in human osteosarcoma.

Long noncoding RNAs (lncRNAs) are pervasively transcribed and have a critical role in genome regulation. Alterations in the expression of several lncRNAs have been observed in some types of cancers; however, the contributions of lncRNAs to osteosarcoma remain unknown. Here, we describe the expression profile of lncRNAs in osteosarcomas compared with paired adjacent noncancerous tissue using microarray analysis. In our study, 25,733 lncRNAs were expressed in osteosarcoma; 403 lncRNAs were consistently over-regulated and 798 lncRNAs were consistently under-regulated in all samples analyzed (⩾2.0-fold, p<0.05). Quantitative real-time polymerase chain reaction (PCR) was used to validate six over-regulated and four under-regulated lncRNAs. Bioinformatic analysis (gene ontology analysis, pathway analysis and network analysis) was used for further research. Pathway analysis indicated that 32 pathways corresponded to under-regulated transcripts and that 34 pathways corresponded to over-regulated transcripts (p-value cut-off is 0.05). Our results are the first to reveal differentially expressed lncRNAs in osteosarcoma and suggest that lncRNAs may be novel candidate biomarkers for the diagnosis of osteosarcoma and potential targets for therapy.

Screening for Metastatic Osteosarcoma Biomarkers with a DNA Microarray

OBJECTIVE The aim of this study was to screen for possible biomarkers of metastatic osteosarcoma (OS) using a DNA microarray. METHODS We downloaded the gene expression profile GSE49003 from Gene Expression Omnibus database, which included 6 gene chips from metastatic and 6 from non-metastatic OS patients. The R package was used to screen and identify differentially expressed genes (DEGs) between metastatic and non-metastatic OS patients. Then we compared the expression of DEGs in the two groups and sub-grouped into up-regulated and down-regulated, followed by functional enrichment analysis using the DAVID system. Subsequently, we constructed an miRNA-DEG regulatory network with the help of WebGestalt software. RESULTS A total of 323 DEGs, including 134 up-regulated and 189 down-regulated, were screened out. The up-regulated DEGs were enriched in 14 subcategories and most significantly in cytoskeleton organization, while the down-regulated DEGs were prevalent in 13 subcategories, especially wound healing. In addition, we identified two important miRNAs (miR-202 and miR-9) pivotal for OS metastasis, and their relevant genes, CALD1 and STX1A. CONCLUSIONS MiR-202 and miR-9 are potential key factors affecting the metastasis of OS and CALD1 and STX1A may be possible targets beneficial for the treatment of metastatic OS. However, further experimental studies are needed to confirm our results.

TIMP2 deficient mice develop accelerated osteoarthritis via promotion of angiogenesis upon destabilization of the medial meniscus

Vascular invasion into the normally avascular articular surface is a hallmark of advanced osteoarthritis (OA). In this study, we demonstrated that the expression of tissue inhibitor of metalloproteinases-2 (TIMP2), an anti-angiogenic factor, was present at high levels in normal articular chondrocytes, and was drastically decreased shortly after destabilization of the medial meniscus (DMM). We also investigated the anti-angiogenic properties of TIMP2 via knockout. We hypothesized that the loss of TIMP2 could accelerate osteoarthritis development via promotion of angiogenesis. Loss of TIMP2 led to increased periarticular vascular formation 1 month post DMM, compared to wild-type mice, and did so without altering the expression pattern of matrix metalloproteinases and vascular endothelial growth factors. The increased vascularization eventually resulted in a severe degeneration of the articular surface by 4 months post DMM. Our findings suggest that reduction of TIMP2 levels and increased angiogenesis are possible primary events in OA progression. Inhibiting or delaying angiogenesis by TIMP2 expression or other anti-angiogenic therapies could improve OA prevention and treatment.

Hypoxia-inducible factor-1 expression predicts osteosarcoma patients' survival: a meta-analysis.

Osteosarcoma, the most common primary bone malignancy, is characterized by easily relapsing and metastasizing. Hypoxia-inducible factor-1 (HIF-1) plays an essential role in tumorigenesis, affecting tumor metabolism, differentiation, angiogenesis, proliferation and metastasis, and has been found to be associated with survival in patients with osteosarcoma. The possible prognostic value of HIF-1 was investigated in many studies, but the results were inconsistent. We therefore conducted a meta-analysis to elucidate the correlation of HIF-1 expression, analyzed by immunohistochemistry in osteosarcoma tissues, with prognosis. The association degree was assessed by calculation of the hazard ratio (HR) and risk ratio (RR) with corresponding 95% confidence intervals (CIs). Follow-up information was available for 486 patients from 7 studies. The results showed that high HIF-1 expression was associated with a worse prognosis when compared to low or undetectable HIF-1 expression, with an HR of 3.67 (95% CI 2.24-5.99; p<0.001) for overall survival (OS) and an RR of 3.72 (95% CI 2.26-6.13; p<0.001) for OS. The RR of 2.55 for disease-free survival (DFS) did not show any obvious relationship between a high level of HIF-1 and DFS (95% CI 0.95-6.87; p = 0.064). The stability of this result was tested by sensitivity analysis and no significant change was detected. This meta-analysis suggests that HIF-1 is an effective prognostic biomarker to predict OS in patients with osteosarcoma.

Prognostic Role of MicroRNA-126 for Survival in Malignant Tumors: A Systematic Review and Meta-Analysis

Background. Increasing studies found that miR-126 expression may be associated with the prognosis of cancers. Here, we performed a meta-analysis to assess the prognostic role of miR-126 in different cancers. Methods. Eligible studies were identified by searching in PubMed, Embase, the Cochrane Library, CNKI, and Wan Fang databases up to March 2015. Pooled hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were calculated to investigate the correlation between miR-126 and survival of cancers. Results. Thirty studies including a total of 4497 participants were enrolled in this meta-analysis. The pooled results showed that high level of miR-126 was a predictor for favorable survival of carcinomas, with pooled HR of 0.77 (95% CI 0.64–0.93) for OS, 0.64 (95%CI 0.48–0.85) for DFS, and 0.70 (95% CI 0.50–0.98) for PFS/RFS/DSS. However, high level of circulating miR-126 predicted a significantly worse OS in patients with cancer (HR = 1.65, 95% CI 1.09–2.51). Conclusions. Our results indicated that miR-126 could act as a significant biomarker in the prognosis of various cancers.

Prognostic Role of MicroRNA-200c-141 Cluster in Various Human Solid Malignant Neoplasms

The miR-200 family has emerged recently as a noticeable marker for predicting cancer prognosis and tumor progression. We aimed to review the evidence of miR-200c-141 genomic cluster as prognostic biomarkers in cancers. The results suggested that high level of miR-200c had no significant impact on OS (HR = 1.14 [0.77–1.69], P = 0.501) and DFS/PFS (HR = 0.72 [0.45–1.14], P = 0.161). Stratified analyses revealed that high miR-200c expression was significantly related to poor OS in serum/plasma (HR = 2.12 [1.62–2.77], P = 0.000) but not in tissues (HR = 0.89 [0.58–1.37], P = 0.599). High miR-200c expression was significantly associated with favorable DFS/PFS in tissues (HR = 0.56 [0.43–0.73], P = 0.000) but worse DFS/PFS in serum/plasma (HR = 1.90 [1.08–3.36], P = 0.027). For miR-141, we found that high miR-141 expression predicted no significant impact on OS (HR = 1.18 [0.74–1.88], P = 0.482) but poor DFS/PFS (HR = 1.11 [1.04–1.20], P = 0.003). Similarly, subgroup analyses showed that high miR-141 expression predicted poor OS in serum/plasma (HR = 4.34 [2.30–8.21], P = 0.000) but not in tissues (HR = 1.00 [0.92–1.09], P = 0.093). High miR-141 expression was significantly associated with worse DFS/PFS in tissues (HR = 1.12 [1.04–1.20], P = 0.002) but not in serum/plasma (HR = 0.90 [0.44–1.83], P = 0.771). Our findings indicated that, compared to their tissue counterparts, the expression level of miR-200c and miR-141 in peripheral blood may be more effective for monitoring cancer prognosis. High miR-141 expression was better at predicting tumor progression than survival for malignant tumors.

Comment on Korsten et al.: Operative or conservative treatment in patients with Rockwood type III acromioclavicular dislocation: a systematic review and update of current literature

To the Editor, In this systematic review, Korsten et al. [1] reviewed the current literature and presented an overview of the outcome of conservative versus operative treatment of Rockwood type III dislocations. They found that the objective and subjective shoulder function outcome was better in the operative group, especially in young adults, though the rate of complications and radiographic abnormalities were higher. The rehabilitation time was shorter in the conservative group, however the cosmetic outcome was worse. It is a very valuable study. Nevertheless, there are some questions we would like to ask related to this article. To begin with, the investigators calculated the results of subjective shoulder function, complications, osteoarthritis, calcification and cosmetic outcome by using SPSS version 20.0. However, they did not provide the concrete statistical methods for these comparisons, which might reduce its credibility. We are wondering how to calculate these results such as 3.13 versus 2.77 (p = 0.406) and so on. To solve these potential problems, we suggest that a meta-analysis should be conducted to compare the subjective shoulder function, complications, osteoarthritis, calcification and cosmetic outcome between operative and conservative groups. Furthermore, there was a slip of the pen in the subgroup analysis section. They clarified that “Four studies reported the deformities and cosmetic outcomes [1, 13, 14, 25]”. With careful reading, we think that the “25” should be replaced by “26”. Finally, the investigators did not compare the outcomes of the objective shoulder function in the studies, which we consider as the most important outcome of AC joint injuries. Therefore, we suggest that at a minimum the investigators should describe the details of objective shoulder function in different studies. We agree that physically active young adults seem to have a slight advantage in outcome when treated operatively. In our opinion, more randomized clinical trials with long-term follow-up should be conducted to provide evidence for the best treatment in patients with Rockwood type III AC dislocations.

Letter regarding Wen X.Y. et al. entitled “Matrix metalloproteinase 2 expression and survival of patients with osteosarcoma: a meta-analysis”

Dear Editor, In a recent issue of Tumor Biology, Xiaoyang Wen and his workmates published an article [1] entitled “Matrix metalloproteinase 2 expression and survival of patients with osteosarcoma: a meta-analysis”. In this study, the investigators performed a meta-analysis to derive a precise estimate of the prognostic role of MMP2 expression in patients with osteosarcoma. The investigators concluded that osteosarcoma patients with high MMP2 expression have poorer prognosis compared with those with low MMP2 expression. However, we have several opinions that we would like to raise to the investigators. Firstly, the investigators just searched three electronic databases (PubMed, EMBASE, and Wanfang databases). The small number of required papers would be an important limitation of the review. We hope that more electronic databases can be systematically searched. In the same time, the investigators had not focused specifically on the issue of the completeness of the search strategy report for databases. They just described the retrieval strategy by using the keywords such as, “osteosarcoma” or “osteosarcomas”, and “MMP2” or “matrix metalloproteinase-2”. We suggest that the investigators should provide us the details of the retrieval strategy and the flowchart of selection. Secondly, in the results section, the investigators just provide us a forest plot to clarify the prognostic role of MMP2 expression in patients with osteosarcoma. Inexplicably, what dose the forest plot and the RR value mean. In our opinion, the investigators should clarify its prognostic role with forest plots of 5-year overall survival (OS) rate and 5-year disease free survival (DFS) rate. Thirdly, the investigators included five cohort studies [2–6] including 297 patients with osteosarcoma. However, the investigators did not provide us any characteristics of these eligible studies. We suggest that the investigators should provide us its characteristics in tables to make us read the metaanalysis well. Finally, the investigators did not follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). As a minor suggestion, adding PRISMA checklist some summery could make this manuscript better. Moreover, more studies with larger sample size are needed to get a more precise estimate of the prognostic role of MMP2 expression in osteosarcoma.

Letter regarding article by Kortram et al.: Risk factors for infectious complications after open fractures: a systematic review and meta-analysis

Dear Editor, We read with great interest the article entitled, Risk factors for infectious complications after open fractures: a systematic review and meta-analysis by Kortram et al. [1]. The authors focused on the risk factors for infectious complications following open fractures. They performed a systematic research of 116 studies and found that there were a lot of statistically significant risk factors for the development of infectious complications after open fractures. The conclusion of this study is valuable and instructive for clinical practice. In spite of the remarkable value of the study, it prompted several queries for the authors. Firstly, the authors mentioned that a variety of databases were used in this study, which, however, were not enough. It would make the outcomes more convincing if the authors included other databases, like clinicaltrials.gov, BIOSIS previews, and NLM Gateway in order to obtain more literature. Besides, the protocol of manual searches should be carefully set out in this meta-analysis. Essential literature would be neglected if the manual search protocol was incomplete, while unpublished data like gray literature should be included as well. Secondly, the potential significance of language bias as a limitation should be considered, if only literature written in English was obtained. Thirdly, high-energy open fractures should be taken into consideration as one of the key factors in trauma-related factors. In Ovaska’s study [2], he demonstrated that infectious complications of high energy fractures were rather common, and particularly, infectious complications rates following open ankle fractures were very high. Consistently, in Dickens’s study [3], he reported that infection rates in high-energy open calcaneal fractures were high. Notably, soft tissue problems predisposed to infections [2, 4]. Moreover, oedema, blisters, and skin problems should be considered as trauma-related factors, which may play an important role in infectious complications after open fractures. Finally, funnel plots were not shown in the meta-analysis. It would be better if the publication biases of all included studies were assessed by funnel plots, Begg’s test, and Egger’s test. Thankfully, the authors made a great contribution in supplying us with a systematic review and meta-analysis of risk factors for infectious complications following open fractures, which could be a valuable reference for clinicians and potentially serve as a guideline to construct prediction models of infection following open fractures. However, in view of the retrospective nature of numerous studies and other limitations, large multi-centre randomized controlled trials or prospective cohort studies should be performed independently in the future in order to assess the risk factors of open fractures.