Identification of twenty-two candidate markers for human osteogenic sarcoma

Role of non-coding RNAs and exosomal non-coding RNAs in retinoblastoma progression

Retinoblastoma (RB) is a rare aggressive intraocular malignancy of childhood that has the potential to affect vision, and can even be fatal in some children. While the tumor can be controlled efficiently at early stages, metastatic tumors lead to high mortality. Non-coding RNAs (ncRNAs) are implicated in a number of physiological cellular process, including differentiation, proliferation, migration, and invasion, The deregulation of ncRNAs is correlated with several diseases, particularly cancer. ncRNAs are categorized into two main groups based on their length, i.e. short and long ncRNAs. Moreover, ncRNA deregulation has been demonstrated to play a role in the pathogenesis and development of RB. Several ncRNAs, such as miR-491-3p, miR-613,and SUSD2 have been found to act as tumor suppressor genes in RB, but other ncRNAs, such as circ-E2F3, NEAT1, and TUG1 act as tumor promoter genes. Understanding the regulatory mechanisms of ncRNAs can provide new opportunities for RB therapy. In the present review, we discuss the functional roles of the most important ncRNAs in RB, their interaction with the genes responsible for RB initiation and progression, and possible future clinical applications as diagnostic and prognostic tools or as therapeutic targets.

ARHGEF3 Associated with Invasion, Metastasis, and Proliferation in Human Osteosarcoma

Background

Osteosarcoma is a malignant bone tumor composed of mesenchymal cells producing osteoid and immature bone. This study is aimed at developing novel potential prognostic biomarkers and constructing a miRNA-mRNA network for progression in osteosarcoma.

Method

GSE70367 and GSE70414 were obtained in the Gene Expression Omnibus (GEO) database. GEO software and the GEO2R calculation method were used to analyze two gene profiles. The coexpression of differentially expressed miRNAs (DEMs) and genes (DEGs) was identified and searched for in the FunRich database for pathway and ontology analysis. Cytoscape was utilized to construct the mRNA-miRNA network. Survival analysis of identified miRNAs and mRNAs was performed by utilizing the Kaplan-Meier Plotter. Besides, expression levels of DEMs and target mRNAs were verified by performing quantitative real-time PCR (qRT-PCR) and Western blot (WB).

Results

Six differentially expressed microRNAs (DEMs) were identified, and 8 target genes were selected after screening. By using the KM Plotter software, miRNA-124 and ARHGEF3 were obviously associated with the overall survival of patients with osteosarcoma. Furthermore, ARHGEF3 was found downregulated in osteosarcoma cells by performing qRT-PCR and WB experiments. Results also showed that downregulated ARHGEF3 may associate with invasion, metastasis, and proliferation.

Conclusions

By using microarray and bioinformatics analysis, DEMs were selected, and a complete miRNA-mRNA network was constructed. ARHGEF3 may act as a therapeutic and prognostic target of osteosarcoma.

Association between common polymorphisms in ERCC gene and prognosis of osteosarcoma in patients treated with chemotherapy: a meta-analysis

Purpose

Some previous studies have sought to investigate the roles of excision repair cross complementation group 1 (ERCC1), ERCC2, ERCC4, and ERCC5 gene polymorphisms in the prognosis of osteosarcoma patients. However, their results were inconclusive. Here, we performed a meta-analysis to determine the strength of the association between eight polymorphisms in the ERCC genes (rs11615, rs3212986, rs2298881, rs13181, rs1799793, rs1800067, rs2296147, and rs1047768) and prognosis of osteosarcoma patients treated with chemotherapy.

Materials and methods

We retrieved the relevant studies from PubMed, Embase, and Web of Science in human osteosarcoma published prior to July 2017. Primary outcomes included overall survival (OS) and event-free survival, expressed by hazard ratios (HRs) with their corresponding 95% CIs. STATA software (version 12.0) was utilized to perform data synthesis.

Results

A total of 13 eligible follow-up studies involving 2,303 patients met all the inclusion criteria, conducted in two populations of ethnic descent: 11 Asians and two Caucasians. In the present meta-analysis, we demonstrated that the homozygous variant genotypes in ERCC2 rs1799793 and ERCC5 rs2296147 were significantly associated with OS in osteosarcoma (TT vs GG for rs1799793: HR = 0.62, 95% CI = 0.41-0.93, P_{heterogeneity} = 0.310, I² = 15.3%, P = 0.020; TT vs CC for rs2296147: HR = 0.42, 95% CI = 0.23-0.78, P_{heterogeneity} = 0.708, I² = 0.0%, P = 0.006). In addition, no evidence of association was observed between prognosis in osteosarcoma and ERCC1 rs11615, ERCC1 rs3212986, ERCC1 rs2298881, ERCC2 rs13181, ERCC4 rs1800067, and ERCC5 rs1047768 polymorphisms.

Conclusion

Our meta-analysis indicated that TT genotype in the ERCC2 rs1799793 and ERCC5 rs2296147 might prolong the survival time of patients with osteosarcoma, suggesting that the rs1799793 and rs2296147 polymorphisms can be used as predictors for prognosis of osteosarcoma patients treated with chemotherapy.

Aberrant promoter methylation status is associated with upregulation of the E2F4 gene in breast cancer

E2F4 is an important basal transcription factor with the potential to promote tumor growth. Its upregulation in various types of cancer has been linked to numerous genetic factors; however, the nature of the involvement of epigenetic mechanisms, including DNA methylation, remains elusive. In the present study, E2F4 expression profiles were determined in 100 paired breast tumor and control samples, through RT-qPCR using the SYBR^® green method. Furthermore, the E2F4 promoter methylation status in each of these samples was assessed using methylation specific PCR, in order to evaluate its impact on gene expression. A two-fold increase in E2F4 gene expression was observed in the breast tumors compared with in their respective controls (P=0.022); of these tumors, ~72% were under-methylated. The change in methylation status was also significantly higher (P<0.001) in the tumor samples. Methylation status was negatively correlated (r=-30) with E2F4 expression profiles, indicating that a decrease in methylation may promote higher expression of E2F4. The two study cohorts (>45 and ≤45 years) had comparable methylation profiles, though they had significantly decreased methylation status compared with controls. Various histo-pathological types also have different methylation profiles, indicating the presence of a tissue specific methylation signature. The results of the present study demonstrated that E2F4 methylation status can have a notable influence on its expression, and that it may have prognostic value in breast carcinogenesis.

The prognostic value of PCNA expression in patients with osteosarcoma: A meta-analysis of 16 studies

BACKGROUND

Numerous studies have attempted to determine the prognostic role of proliferating cell nuclear antigen (PCNA) expression in patients with osteosarcoma with no consistent conclusion. We performed this meta-analysis to systematically elucidate the association in a more precise manner.The purpose of this meta-analysis is to determine the prognostic role of PCNA in patients with osteosarcoma.

METHODS

A systematic search of relevant studies was performed in 6 electronic databases including PubMed, Embase, Web of Science, Wanfang database, China National Knowledge Internet (CNKI) database, and Chinese Biological Medical (CBM) Database (up to March 1, 2016) with the following keywords: (PCNA OR proliferating cell nuclear antigen) AND (osteosarcoma OR osteogenic tumor). A manual search of references on relevant articles was also conducted by 2 investigators independently. We performed a comprehensive evaluation of the correlation between PCNA expression and overall survival (OS) or disease-free survival (DFS) by calculating relative ratios (RR) and their corresponding 95% confidence intervals (CI) using STATA software. A fixed- or random-effect model was chosen based on the between-study heterogeneity.

RESULTS

In total, 16 studies with 691 osteosarcoma patients were included in this meta-analysis. PCNA overexpression was found in approximately 57.31% of the patients with osteosarcoma. The meta-analysis suggested that PCNA overexpression in osteosarcoma patients is associated with low OS, but not significantly with DFS (RR = 1.82, 95% CI 1.53-2.18, P = .000; RR = 1.15, 95% CI 0.91-1.44, P = 0.234). Sensitivity analysis for OS and DFS showed no significant difference and the pooled RRs were stable when the included studies were removed one by one. Similar results were also obtained for subgroup analysis based on different follow-ups and cutoffs to determine PCNA expression.

CONCLUSION

The findings from this meta-analysis indicate that PCNA overexpression is an effective biomarker for poor prognosis in patients with osteosarcoma for OS. Hence, more large-scale studies are still needed to further warrant this conclusion.

MiR-613 suppresses retinoblastoma cell proliferation, invasion, and tumor formation by targeting E2F5

Retinoblastoma is a common intraocular malignancy that occurs during childhood. MicroRNAs play critical roles in the regulation of retinoblastoma initiation and progression, and aberrant expression of miR-613 had been reported in various types of cancer. However, the role and mechanism of its function in retinoblastoma are still unclear. In this study, we found that miR-613 was downregulated in retinoblastoma tissues and cell lines. Overexpression of miR-613 suppressed retinoblastoma cell proliferation, migration, and invasion and induced cell cycle arrest in vitro. Additionally, overexpressed miR-613 also inhibited tumor formation of retinoblastoma cells in vivo. We further identified E2F5 as a direct target of miR-613. Reintroduction of E2F5 without 3'-untranslated region reversed the inhibitory effects of miR-613 on cell proliferation and invasion. Our data collectively indicate that miR-613 functions as a tumor suppressor in retinoblastoma through downregulating E2F5, supporting the targeting of the novel miR-613/E2F5 axis as a potentially effective therapeutic approach for retinoblastoma.

Aberrant Promoter Methylation at CpG Cytosines Induce the Upregulation of the E2F5 Gene in Breast Cancer

Purpose

The promoter methylation status of cell cycle regulatory genes plays a crucial role in the regulation of the eukaryotic cell cycle. CpG cytosines are actively subjected to methylation during tumorigenesis, resulting in gain/loss of function. E2F5 gene has growth repressive activities; various studies suggest its involvement in tumorigenesis. This study aims to investigate the epigenetic regulation of E2F5 in breast cancer to better understand tumor biology.

Methods

The promoter methylation status of 50 breast tumor tissues and adjacent normal control tissues was analyzed. mRNA expression was determined using SYBR® green quantitative polymerase chain reaction (PCR), and methylation-specific PCR was performed for bisulfite-modified genomic DNA using E2F5-specific primers to assess promoter methylation. Data was statistically analyzed.

Results

Significant (p<0.001) upregulation was observed in E2F5 expression among tumor tissues, relative to the control group. These samples were hypo-methylated at the E2F5 promoter region in the tumor tissues, compared to the control. Change in the methylation status (Δmeth) was significantly lower (p=0.022) in the tumor samples, indicating possible involvement in tumorigenesis. Patients at the postmenopausal stage showed higher methylation (75%) than those at the premenopausal stage (23.1%). Interestingly, methylation levels gradually increased from the early to the advanced stages of the disease (p<0.001), which suggests a putative role of E2F5 methylation in disease progression that can significantly modulate tumor biology at more advanced stage and at postmenopausal age (Pearson's r=0.99 and 0.86, respectively). Among tissues with different histological status, methylation frequency was higher in invasive lobular carcinoma (80.0%), followed by invasive ductal carcinoma (46.7%) and ductal carcinoma in situ (20.0%).

Conclusion

Methylation is an important epigenetic factor that might be involved in the upregulation of E2F5 gene in tumor tissues, which can be used as a prognostic marker for breast cancer.

Association of GRM4 gene polymorphisms with susceptibility and clinicopathological characteristics of osteosarcoma in Guangxi Chinese population

Osteosarcoma is the most frequent malignant primary bone tumor. GRM4 is expressed in human osteosarcoma cells, and high expression of mGluR4 in osteosarcoma tissues is related to poor prognosis. The aim of this study was to investigate the association between polymorphism of the GRM4 gene and the susceptibility to osteosarcoma in a Chinese population. In a case-control study, we investigated polymorphisms in the GRM4 gene (rs2229901, rs733457, and rs1906953) with a real-time quantitative polymerase chain reaction (PCR) assay (TaqMan). The study was conducted with 126 Chinese patients with osteosarcoma and 168 Chinese subjects in a control group. Unconditional logistic regression was used to analyze the correlation between single nucleotide polymorphisms (SNPs) and osteosarcoma risk. Different survival rates of different genotypic patients with osteosarcoma were analyzed through Kaplan-Meier. There were statistically significant differences in the distributions of the rs1906953 genotypes between the cases and control group (P = 0.034). However, there was no remarkable difference in the three genotypes of GRM4 gene rs2229901 locus between the patient group and control group (P = 0.369). Survival analysis for rs1906953 showed that the median survival time of osteosarcoma patients with the CC genotype was significantly shorter compared to the CT and TT genotypes; patients carrying CC genotype have apparently got a decrease in their recurrence-free survival time in comparison with patients carrying TT genotype. Our data suggest that GRM4 gene polymorphism is closely related to the morbidity and metastasis of osteosarcoma in a Chinese population.

Association between GSTP1 polymorphisms and prognosis of osteosarcoma in patients treated with chemotherapy: a meta-analysis

Objective

The aim of this study was to evaluate the relationship between GSTP1 polymorphisms and prognosis of osteosarcoma in patients treated with chemotherapy, by performing a meta-analysis.

Methods

The studies of effects of GSTP1 gene polymorphisms on osteosarcoma survival after chemotherapy were collected. STATA (version 12.0) was used to perform data synthesis.

Results

Six studies involving 898 participants were included. A meta-analysis was performed on studies in GSTP1 313A>G(rs1695) assessing the association between tumor response and the polymorphisms in GSTP1 (AA vs AG, AA vs GG), the pooled odds ratios (ORs) were 2.06 (95% confidence interval [CI]: 1.48–2.86, P=0.628, I²=0.0%). There was significant association between the polymorphisms in GSTP1 (AA vs AG, AA vs GG) and the events that happened, the pooled ORs were 1.86 (95% CI: 1.14–3.06, P=0.034, I²=58.6%), and there was significant association between the polymorphisms in GSTP1 (AA vs AG, AA vs GG) and survival times (overall survival and progression-free survival) in osteosarcoma patients treated with chemotherapy, and the pooled ORs were 2.14 (95% CI: 1.51–3.04, P=0.675, I²=0.0%) and 2.77 (95% CI: 1.56–4.91, P=0.347, I²=9.3%), respectively. Two studies assessed the association of polymorphisms in GSTP1 I105V (IIe/IIe vs IIe/Val, IIe/IIe vs Val/Val) with overall survival in human osteosarcoma. The pooled ORs were 1.20 (95% CI: 0.64–2.27, P=0.010, I²=73.5%). The study showed an insignificant difference in overall survival for the polymorphisms in GSTP1 (IIe/IIe vs IIe/Val, IIe/IIe vs Val/Val).

Conclusion

This meta-analysis indicated that GSTP1 polymorphisms might influence osteosarcoma risk and suggests that GSTP1 polymorphisms may be an important risk factor for osteosarcoma.

Large-scale tag/PCR-based gene expression profiling

An intriguing enigma in molecular biology is how genes within a single genome are differentially expressed in different cell types of a multicellular organism, or in response to different developmental or environmental queues in a single cell type. Quantification of transcript levels on a genome-wide scale, often termed transcript profiling, provides a powerful approach to identifying protein-coding and non-coding RNAs functionally relevant to a given biological process. Indeed, transcriptome analysis has been a key area of biological inquiry for decades and successfully produced discoveries in a multitude of processes and disease states, and in an increasingly large number of organisms. The evolution of technologies with increasing levels of informational content, ranging from hybridization-based technologies such as Northern blot analysis and microarrays to tag/polymerase chain reaction (PCR)- and sequence-based technologies including differential display and SAGE, along with the next-generation sequencing, has provided hope for revealing the molecular details of biological systems as they respond to change. This review is an overview of selected high throughput tag/PCR-based methods for genome-wide expression profiling amenable to high-throughput automated operation in any standard laboratory.

The association of MDM2 c.346G>A genetic variant with the risk of osteosarcoma in Chinese

Previous studies suggest that the MDM2 gene is one of the most important candidate genes for influencing the risk of osteosarcoma. This study aims to investigate the potential association of MDM2 c.346G>A genetic variant with the risk of osteosarcoma in Chinese. A total of 738 subjects were recruited in this study. The genotypes of MDM2 c.346G>A genetic variant were detected by the created restriction site-polymerase chain reaction. Our data suggest that the MDM2 c.346G>A genetic variant is associated with the increased risk of osteosarcoma in the homozygote comparison (AA vs. GG: odds ratio [OR]=2.36, 95% confidence interval [CI] 1.30-4.28, χ2=8.35, p=0.004), recessive model (AA vs.

GA/GG

OR=2.32, 95% CI 1.30-4.13, χ2=8.50, p=0.004), and allele comparison (A vs. G: OR=1.27, 95% CI 1.01-1.60, χ2=4.34, p=0.037). Results from this study indicated that the allele-A and genotype-AA of MDM2 c.346G>A genetic variant could be an increased risk factor for the susceptibility to osteosarcoma and might be used as a potential molecular marker for evaluating the risk of osteosarcoma.

The association of glutathione S-transferase polymorphisms in patients with osteosarcoma: evidence from a meta-analysis

Osteosarcoma is a life-threatening malignancy that often occurs in teenagers. Numerous studies have reported glutathione S-transferase polymorphisms are associated with osteosarcoma, but the results are inconclusive, partially because the sample size in each of published studies is relatively small. Therefore, we performed a meta-analysis of the published studies to estimate the association more accurately. To preciously examine the association between the glutathione S-transferase polymorphisms and osteosarcoma, we undertook a meta-analysis of six case-control studies. The association between the glutathione S-transferase polymorphisms and osteosarcoma risk was assessed by odds ratios together with their 95% confidence intervals using a fixed-effects model or random-effects model. In addition, hazard ratio was used to measure the relationship between glutathione S-transferase polymorphisms and prognosis in patients with osteosarcoma. We found that there was significant association between the polymorphisms in GSTT1 or GSTM3 (AA versus BB) and osteosarcoma risk. In addition, there is no evidence of association on GSTM1, GSTT1, GSTP1 (IIe/IIe versus IIe/Val) or GSTP1 (IIe/IIe versus Val/Val) polymorphisms with prognosis in osteosarcoma. In conclusion, the GSTT1 and GSTM3 polymorphisms might influence osteosarcoma risk.

Association between CTLA-4 genetic polymorphisms and susceptibility to osteosarcoma in Chinese Han population

Osteosarcoma (OS) is the most common malignant primary bone tumor in the world. The cytotoxic T-lymphocyte antigen-4 gene (CTLA-4) is an important candidate gene for influencing the development of OS. This study aimed to investigate the potential association of CTLA-4 genetic polymorphisms with OS risk in Chinese Han population. A total of 415 OS patients and 431 healthy controls were enrolled in this study. The created restriction site-polymerase chain reaction (CRS-PCR) and DNA sequencing methods were used to detect the genotyping of CTLA-4 c.75G[C and c.326G[A genetic polymorphisms. We observed that the genotypes/alleles of c.75G[C and c.326G[A genetic polymorphisms were statistically associated with the increased risk of OS (for c.75G[C, CC versus (vs.) GG: OR 1.72, 95% CI 1.09–2.74; C vs. G: OR 1.30, 95% CI 1.06–1.60; for c.326G[A, AA vs. GG: OR 2.12, 95% CI 1.31–3.42; A vs. G: OR 1.31, 95% CI 1.07–1.61). The allele-C/genotype-CC of c.75G[C and allele-A/genotype-AA of c.326G[A may contribute to OS susceptibility. These data indicate that CTLA-4 genetic polymorphisms are potentially related to OS risk in Chinese Han population, and might be used as molecular markers for evaluating the risk of OS.

Quantitative assessment of the association of COX-2 (Cyclooxygenase-2) immunoexpression with prognosis in human osteosarcoma: a meta-analysis

Background

Numerous studies examining the relationship between Cyclooxygenase-2 (COX-2) immunoexpression and clinical outcome in osteosarcoma patients have yielded inconclusive results.

Methods

We accordingly conducted a meta-analysis of 9 studies (442 patients) that evaluated the correlation between COX-2 immunoexpression and clinical prognosis (death). Pooled odds ratios (OR) and risk ratios (RR) with 95% confidence intervals (95% CI) were calculated using the random-effects or fixed-effects model.

Results

Meta–analysis showed no significant association between COX-2 positivity and age, gender, tumor location, histology, stage, metastasis or 90% necrosis. Conversely, COX-2 immunoexpression was associated with overall survival rate (RR=2.12; 95% CI: 1.10–3.74; P=0.009) and disease-free survival rate (RR=1.63; 95% CI: 1.17–2.28; P=0.004) at 2 years. Sensitivity analysis performed by omitting low quality studies showed that the pooled results were stable.

Conclusions

COX-2 positivity was associated with a lower 2-year overall survival rate and disease-free survival rate. COX-2 expression change is an independent prognostic factor in patients with osteosarcoma.

Glutathione S-transferase P1 and DNA polymorphisms influence response to chemotherapy and prognosis of bone tumors

Osteosarcoma is the most common primary bone malignancy in children and adolescents, and its clinical outcome is poor. We evaluated the influence of GSTP1, ERCC1 and ERCC2 polymorphisms on response to chemotherapy among osteosarcoma patients, and the significnace of these genes for prognosis. A total of 187 patients with osteosarcoma were administered methotrexate, cisplatin/adriamycin, actinomycin D, cyclophosphamide, or vincristine. GSTP1, ERCC1 and ERCC2 polymorphisms were genotyped by PCR-RFLP assay. The results showed the average survival time of 187 patients were 38.4 months. Some 97 patients showed response to neoadjuvant chemotherapy. The GSTP1 Val and ERCC2 A/A genotypes had significantly higher rates of response to chemotherapy, with adjusted OR (95% CI) of 2.19 (1.15-6.21) and 2.88 (1.14-13.3). Individuals with the ERCC2 A/A genotype were likely to have a lower risk of death from oseosarcoma, and the adjusted HR was 0.32 (0.13-0.95). Our study indicated that GSTP1 and ERCC2 Lys751Gln polymorphisms might be candidate pharmacogenomic factors to be explored in the future to identify osteosarcoma patients who might benefit from chemotherapy.

Predictive potential of glutathione S-transferase polymorphisms for prognosis of osteosarcoma patients on chemotherapy

OBJECTIVE

To evaluate the predictive value of glutathione S-transferase (GST) gene polymorphisms for the prognosis of osteosarcoma patients receiving chemotherapy.

METHODS

A total of 159 patients were included in our study between January 2005 and December 2007., with follow-up until January 2012. Genotyping was based upon the duplex polymerase-chain-reaction with the PCR-CTPP method.

RESULTS

At the time of diagnosis, 15.4% of the patients presented with metastasis, while 22.3% developed metastasis during follow-up. At the time of final analysis on January 2012, the median follow-up was 45.5 months. Patients with null GSTM1 and GSTT1 had a higher event free survival rate than non-null genotype, but no significant association was found between the two genotypes and prognosis of osteosarcoma. Individuals with GSTP1 Val/Val genotype tended to live shorter than with the IIe/IIe genotype, and we found a significantly higher risk of death from osteosarcoma (adjusted HR=2.35, 95% CI=1.13-4.85).

CONCLUSION

The GSTP1 gene polymorphism may have an important role in the prognosis of osteosarcoma patients with chemotherapy. Further analyses with larger samples and more genes encoding metabolizing and DNA repair enzymes are warranted.

Association analysis between genetic variants of MDM2 gene and osteosarcoma susceptibility in Chinese

Osteosarcoma (OS) is the most common pediatric bone malignancy worldwide. The MDM2 gene is an important candidate gene for influencing the susceptibility to OS. The objective of this study aimed to detect the potential association between MDM2 genetic variants and OS susceptibility in Chinese Han population. We recruited 415 OS patients and 431 cancer-free controls in this case-control study. The c.44C>T and c.1002T>C genetic variants in MDM2 gene were investigated using created restriction site-polymerase chain reaction (CRS-PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP), respectively. We found that the genotypes/alleles of c.44C>T and c.1002T>C were statistically associated with the increased risk of OS (for c.44C>T, TT versus (vs.) CC: OR = 2.43, 95% CI 1.49-3.95, p < 0.001; T vs. C: OR = 1.36, 95% CI 1.11-1.67, p = 0.003; for c.1002T>C, CC vs. TT: OR = 2.38, 95% CI 1.37-4.13, p = 0.002; C vs. T: OR = 1.27, 95% CI 1.02-1.56, p = 0.030). The T allele and TT genotype of c.44C>T and C allele and CC genotype of c.1002T>C could be increased risk factors for the susceptibility to OS. Results from this study suggest that MDM2 genetic variants are potentially related to OS susceptibility in Chinese Han population, and might be used as molecular markers for assessing OS susceptibility.

Survivin-specific small interfering RNAs enhance sensitivity of glioma U-87MG cells to paclitaxel by promoting apoptosis

A survivin siRNA expression vector was transfected into glioma U-87MG cells and these cells were then treated with paclitaxel. The results showed that survivin-specific siRNA combined with paclitaxel treatment synergistically inhibited glioma U-87MG cell proliferation and promoted apoptosis. This treatment also inhibited the expression of the cell cycle regulatory proteins, survivin, cyclinD1, c-Myc and CDK4 and enhanced the sensitivity of U-87MG cells to paclitaxel.

Glutathione S-transferase polymorphisms in osteosarcoma patients

BACKGROUND

Osteosarcoma is the most common malignant bone tumor in children and adolescents. Multidrug resistance and poor clinical outcome are the problems that still affect osteosarcoma patients. The glutathione S-transferase supergene family includes several genes that encode enzymes involved in the detoxification of many xenobiotic agents, including carcinogens and anticancer drugs. The polymorphisms in these genes have already been associated both with cancer susceptibility and anticancer drugs resistance.

OBJECTIVES

This study aims to investigate the genotype frequencies of GSTM1, GSTT1 and GSTM3 genes in 80 osteosarcoma patients and 160 normal control participants, and also the influence of these polymorphisms in the clinical outcome of osteosarcoma patients.

METHODS

GSTM1 and GSTT1 deletion polymorphisms were examined through a multiplex-PCR and the GSTM3 polymorphism of three base pair-deletion at intron 6 using PCR-restriction fragments length polymorphism method.

RESULTS

We found that GSTM1 null genotype is correlated to poor clinical outcome characterized by the increased lung relapse occurrence [odds ratio (OR)=2.71, P=0.036], while the presence of at least one GSTM1 allele is associated with a good response to treatment and better survival (OR=4.28, P=0.020 and hazards ratio=4.09, P=0.0078, respectively). The GSTT1 null genotype was correlated with a better overall survival (hazards ratio=7.15, P=0.0247), whereas GSTM3*B allele was associated with metastasis at diagnosis (OR=2.83, P=0.028).

CONCLUSION

The findings of this study suggest that GST polymorphisms may have a role in treatment response and osteosarcoma progression.

A potential oncogenic role of the commonly observed E2F5 overexpression in hepatocellular carcinoma

AIM: To explore the expression pattern of E2F5 in primary hepatocellular carcinomas (HCCs) and elucidate the roles of E2F5 in hepatocarcinogenesis.

METHODS: E2F5 expression was analyzed in 120 primary HCCs and 29 normal liver tissues by immunohistochemistry analysis. E2F5-small interfering RNA was transfected into HepG2, an E2F5-overexpressed HCC cell line. After E2F5 knockdown, cell growth capacity and migrating potential were examined.

RESULTS: E2F5 was significantly overexpressed in primary HCCs compared with normal liver tissues (P = 0.008). The E2F5-silenced cells showed significantly reduced proliferation (P = 0.004). On the colony formation and soft agar assays, the number of colonies was significantly reduced in E2F5-silenced cells (P = 0.004 and P = 0.009, respectively). E2F5 knockdown resulted in the accumulation of G0/G1 phase cells and a reduction of S phase cells. The number of migrating/invading cells was also reduced after E2F5 knockdown (P = 0.021).

CONCLUSION: To our knowledge, this is the first evidence that E2F5 is commonly overexpressed in primary HCC and that E2F5 knockdown significantly repressed the growth of HCC cells.

Comparative proteomic analysis of osteosarcoma cell and human primary cultured osteoblastic cell

To identify new biomarkers that facilitate the accurate early diagnosis of osteosarcoma and that may possibly include novel therapeutic candidates, we performed a proteomic approach to compare osteosarcoma cells and human primary cultured osteoblastic cells. Image analysis of silver-stained 2-DE gels revealed that the level of 12 protein spots was significantly different between the two groups of samples (p < .004). After mass spectroscopic identification and database searches, we found that in osteosarcoma cells, the level of HSP70, actin capping protein, ATP synthase, Mthsp75, UQCRC1, Ras-related nuclear protein, UCH-L1, and PRDX4 was elevated. However, the level of pyruvate dehydrogenase E1, Prohibitin, and Annexin V was decreased. Subsequent Western blot analyses of UQCRC1, UCH-L1, and PRDX4 in osteosarcoma tissues confirmed the results obtained by the proteomic analyses. These identified proteins may be potential molecular targets for osteosarcomatous diagnostics and therapeutics.

Reversal of multi-drug resistance by pSUPER-shRNA-mdr1 in vivo and in vitro

AIM: To explore the possibility of reversing multi-drug resistance (MDR) to HepG2/mdr1 in vitro and in vivo with RNA interference (RNAi).

METHODS: HepG2/mdr1 was obtained by cloning the whole gene mdr1 into HepG2 cells. shRNA targeting sequence was designed to be homologous to the P-gp encoding MDR1 mRNA consensus sequence. pSUPER-shRNA/mdr1 was constructed using the enzyme-digested technique. HepG2/mdr1 cells were transfected with vectors of pSUPER-shRNA/mdr1 to measure their efficacy by real-time PCR for mdr1 mRNA, flow cytometry (FCM) for P-gp expression, and Rhodamine efflux, MTT method for HepG2/mdr1 function, respectively. In vivo, mice tumors were treated by injecting pSUPER-shRNA/mdr1 in situ and into intra-abdominal cavity. Tumors were collected to create cell suspension and cryosections after chemothearpy with adiramycin and mytomycin. The cell suspension was incubated in RPMI-1640 supplemented with G418 to screen stable cells for appreciating the reversal of MDR. Cryosections were treated with immunohistochemistry technique to show the effectiveness of transfection and the expression of P-gp.

RESULTS: pSUPER-shRNA/mdr1 was successfully constructed, which was confirmed by sequencing. The MDR phenotype of HepG2/mdr1 was decreased significantly in vitro transfection. HepG2/mdr1 showing its MDR was reversed notably in P-gp expression (11.0% vs 98.2%, P < 0.01). Real-time PCR showed that mRNA/mdr1 was lower in test groups than in control groups (18.73 ± 1.33 vs 68.03 ± 2.21, P < 0.001). Compared with HepG2, the sensitivity of HepG2/mdr1 and HepG2/mdr1-dsRNA cells to ADM was decreased by 1.64 times and 15.6 times, respectively. The accumulation of DNR in positive groups was decreased evidently. In vivo, the p-gp expression in positive groups was significantly lower than that in control groups (65.1% vs 94.1%, P < 0.05). The tumor suppressing rate in test groups was 57.8%. After chemotherapy, the growth rate in test groups was lower than that in control groups (700.14 ± 35.61 vs 1659.70 ± 152.54, P < 0.05). Similar results were also observed under fluorescence microscope, and confirmed by Image-Pro Plus 4.5 analysis.

CONCLUSION: pSUPER-shRNA/mdr1 vector system allows simple, stable and durable nonviral knockdown of P-gp by RNAi in malignant cells and animals to restore their sensitivity to adriamycin.

Severe suppression of Frzb/sFRP3 transcription in osteogenic sarcoma

Deciphering the molecular basis of cancer is critical for developing novel diagnostic and therapeutic strategies. To better understand the early molecular events involving osteogenic sarcoma (OGS), we have initiated a program to identify potential tumor suppressor genes. Expression profiling of total RNA from ten normal bone cell lines and eleven OGS-derived cell lines by microarray showed 135-fold lower expression of FRZB/sFRP3 mRNA in OGS cells compared to bone cells; this down-regulation of Frzb/sFRP3 mRNA expression was found to be serum-independent. Subsequently, fourteen OGS biopsy specimens showed nine-fold down-regulation of Frzb/sFRP3 mRNA expression compared to expression in eight normal bone specimens as determined by microarray. FRZB /sFRP3 protein level was also found to be at a very low level in 4/4 OGS cell lines examined. Quantitation by RT-PCR indicated approximately 70% and approximately 90% loss of Frzb/sFRP3 mRNA expression in OGS biopsy specimens and OGS-derived cell lines respectively, compared to expression in bone (p<0.0001). Hybridization experiments of a cDNA microarray containing paired normal and tumor specimens from nineteen different organs did not show any significant difference in the level of Frzb/sFRP3 mRNA expression between the normal and the corresponding tumor tissues. Exogenous expression of FRZB/sFRP3 mRNA in two OGS-derived cell lines lacking endogenous expression of the mRNA produced abundant mRNA from the exogenous gene, eliminating degradation as a possibility for very low level of FRZB/sFRP3 mRNA in OGS specimens. Results from PCR-based experiments suggest that the FRZB/sFRP3 gene is not deleted in OGS cell lines, however, karyotyping shows gross abnormalities involving chromosome 2 (location of the FRZB gene) in five of twelve OGS-derived cell lines. Together, these data suggest a tumor-suppressive potential for FRZB/sFRP3 in OGS.

Knockdown of Stat3 expression using RNAi inhibits growth of laryngeal tumors in vivo

AIM

To study the effect of pSilencer1.0-U6-siRNA-stat3 on the growth of human laryngeal tumors in nude mice.

METHODS

Hep2 cells were transplanted into nude mice, then at the time of tumor formation, growth rates were observed. After the tumor formed, pSilencer1.0-U6-siRNA-stat3 was injected. Tumor volumes were calculated, and growth curves were plotted. Representative histological sections were taken from mice bearing transplantation tumors in both treated and control groups, and stat3, pTyr-stat3, Bcl-2, cyclin D1, and survivin expression were detected by Western blotting. survivin mRNA levels were detected by Northern blotting, hematoxylin and eosin staining and terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) assay to confirm the apoptosis of tumors.

RESULTS

In nude mice, pSilencer1.0-U6-siRNA-stat3 significantly suppressed the growth of tumors compared with controls (P<0.01). It suppressed stat3 expression, and downregulated BcL2, cyclin D1, and survivin expression within the tumor. This significantly induced apoptosis of the tumors.

CONCLUSION

pSilencer1.0-U6-siRNA-stat3 was able to inhibit the growth of transplanted human laryngeal tumors in nude mice and induce apoptosis.

Down-regulation of signal transducer and activator of transcription 3 expression using vector-based small interfering RNAs suppresses growth of human prostate tumor in vivo

PURPOSE

Signal transducer and activator of transcription 3 (Stat3) is constitutively activated in a variety of cancers and it is a common feature of prostate cancer. Thus, Stat3 represents a promising molecular target for tumor therapy. We applied a DNA vector-based Stat3-specific RNA interference approach to block Stat3 signaling and to evaluate the biological consequences of Stat3 down-modulation on tumor growth using a mouse model.

EXPERIMENTAL DESIGN

To investigate the therapeutic potential of blocking Stat3 in cancer cells, three small interfering RNAs (siRNA; Stat3-1, Stat3-2, and Stat3-3) specific for different target sites on Stat3 mRNA were designed and used with a DNA vector-based RNA interference approach expressing short hairpin RNAs to knockdown Stat3 expression in human prostate cancer cells in vitro as well as in vivo.

RESULTS

Of the three equivalently expressed siRNAs, only Stat3-3 and Stat3-2, which target the region coding for the SH2 domain and the coiled-coil domain, respectively, strongly suppressed the expression of Stat3 in PC3 and LNCaP cells. The Stat3-1 siRNA, which targeted the DNA-binding domain, exerted no effect on Stat3 expression, indicating that the gene silencing efficiency of siRNA may be dependent on the local structure of Stat3 mRNA. The Stat3 siRNAs down-regulated the expression of Bcl-2 (an anti-apoptotic protein), and cyclin D1 and c-Myc (cell growth activators) in prostate cancer cells. Inhibition of Stat3 and its related genes was accompanied by growth suppression and induction of apoptosis in cancer cells in vitro and in tumors implanted in nude mice.

CONCLUSIONS

These data indicate that Stat3 signaling is a promising molecular target for prostate cancer therapy and that vector-based Stat3 siRNA may be useful as a therapeutic agent for treatment of prostate cancer.

Identification of drug-regulated genes in osteosarcoma cells

The introduction of systemic chemotherapy improved significantly the prognosis of osteosarcoma. Despite this success, approximately 30-40% of patients will relapse. Cytotoxic drugs have been shown to induce apoptosis in the target cells independent of their primary effects. The underlying molecular mechanisms and the intracellular mediators, however, are still largely unknown. Therefore, the purpose of our study was to identify drug-regulated genes in osteosarcoma cells useful as prognostic factors and for the development of new therapeutic strategies. Using suppressive subtractive hybridization (SSH) the gene expression pattern of untreated Saos-2 cells was compared to cells treated with cisplatin, methotrexate and doxorubicin, respectively. We identified 8 genes that are regulated >2-fold in drug-treated osteosarcoma cell lines. Expression of ferritin light chain, rhoA, inosine monophosphatdgehydrogenase II, ribonucleotide reductase M2, pro2000 and pro1859 were increased after drug treatment, whereas prohibitin and alpha-actinin expressions were significantly downregulated. Differential expression of the identified genes was verified by Northern blot analysis of 3 different osteosarcoma cell lines. In addition, the effects on chemosensitivity of 4 selected genes was analyzed by overexpression of recombinant constructs in Saos-2 cells and subsequent quantification of drug-induced apoptosis. Overexpression of prohibitin and rhoA reduced significantly drug sensitivity to approximately 52% and 59% indicating a crucial role in the modulation of drug-induced cell death.

The human homolog of yeast SEP1 is a novel candidate tumor suppressor gene in osteogenic sarcoma

The hSEP1 gene is the human homolog of yeast SEP1. Yeast SEP1 is a multifunctional gene that regulates a variety of nuclear and cytoplasmic functions including homologous recombination, meiosis, telomere maintenance, RNA metabolism and microtubule assembly. The function of hSEP1 is not known. We show loss or reduced expression of hSEP1 messenger RNA (mRNA) in three of four primary osteogenic sarcoma (OGS)-derived cell lines and in eight of nine OGS biopsy specimen. In addition, we find a heterozygous missense mutation (Valine(1484)>Alanine) at a conserved amino acid in the primary OGS-derived cell line U2OS. Importantly, we identified a homozygous missense mutation involving a CG-dinucleotide leading to a change in a conserved amino acid, aspartic acid(1137) >asparagine, in the primary OGS-derived cell line, TE85. hSEP1 mRNA expression was nearly undetectable in TE85 and low in U2OS cell lines. None of these mutations were identified in 20 normal samples consisting of bone, cartilage and fibroblast. The hSEP1 gene is located in chromosome 3 at 3q25-26.1 between markers D3S1309 and D3S1569. An adjacent locus defined by the polymorphic markers D3S1212 and D3S1245 has previously been reported to undergo loss of heterozygosity (LOH) at a >70% frequency in OGS and claimed to harbor an important tumor suppressor gene in osteosarcoma. The homozygous mutation in the hSEP1 mRNA in TE85 cell line suggest that this gene itself is subject to LOH. Taken together, these results suggest that hSEP1 acts as a tumor suppressor gene in OGS.

Etiology of osteosarcoma

Although the prognosis and quality of life of patients with osteosarcoma were improved significantly during the past decades, the pathogenesis and etiology of this disease remain obscure. Significant interest and effort in this cancer led to the identification of numerous etiologic agents. Several chemical agents such as beryllium, viruses such as FBJ, subsequently found to contain the src-oncogene, and radiation were shown to be potent inducers of osteosarcoma. Paget's disease, electrical burn, or trauma all are thought to be other factors that may contribute to the pathogenesis. More recently, patients with hereditary diseases such as Rothmund-Thomson syndrome, Bloom syndrome, and Li-Fraumeni syndrome were found to have an increased risk of having osteosarcoma develop. During the past few years, the molecular analysis brought a wealth of new information with numerous genes that were associated with osteosarcoma and its clinical disease progression. They can be categorized into self-sufficiency in growth signals, insensitivity to growth inhibitory signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and tissue evasion and metastasis. Although the understanding of these processes in osteosarcoma still is incomplete, it may have the potential to significantly affect the patient care in the future.

Phenotypic silencing of cytoplasmic genes using sequence-specific double-stranded short interfering RNA and its application in the reverse genetics of wild type negative-strand RNA viruses

BACKGROUND

Post-transcriptional gene silencing (PTGS) by short interfering RNA has opened up new directions in the phenotypic mutation of cellular genes. However, its efficacy on non-nuclear genes and its effect on the interferon pathway remain unexplored. Since directed mutation of RNA genomes is not possible through conventional mutagenesis, we have tested sequence-specific 21-nucleotide long double-stranded RNAs (dsRNAs) for their ability to silence cytoplasmic RNA genomes.

RESULTS

Short dsRNAs were generated against specific mRNAs of respiratory syncytial virus, a nonsegmented negative-stranded RNA virus with a cytoplasmic life cycle. At nanomolar concentrations, the dsRNAs specifically abrogated expression of the corresponding viral proteins, and produced the expected mutant phenotype ex vivo. The dsRNAs did not induce an interferon response, and did not inhibit cellular gene expression. The ablation of the viral proteins correlated with the loss of the specific mRNAs. In contrast, viral genomic and antigenomic RNA, which are encapsidated, were not directly affected.

CONCLUSIONS

Synthetic inhibitory dsRNAs are effective in specific silencing of RNA genomes that are exclusively cytoplasmic and transcribed by RNA-dependent RNA polymerases. RNA-directed RNA gene silencing does not require cloning, expression, and mutagenesis of viral cDNA, and thus, will allow the generation of phenotypic null mutants of specific RNA viral genes under normal infection conditions and at any point in the infection cycle. This will, for the first time, permit functional genomic studies, attenuated infections, reverse genetic analysis, and studies of host-virus signaling pathways using a wild type RNA virus, unencumbered by any superinfecting virus.