Rho GTPase-activating protein 35 rs1052667 polymorphism and osteosarcoma risk and prognosis

ARHGAP44 expression is associated with the metastasis of osteosarcoma and is a promising prognostic biomarker

Osteosarcoma (OS) is the most domain primary malignant bone tumor. Treatment resistances and metastases result in a decreasing 5-year overall survival rate of OS. However, Rho GTPase-activating protein 44 (ARHGAP44) has not been well studied in OS. The OS patient data were obtained from Therapeutically Applicable Research to Generate Effective Treatments and Gene Expression Omnibus databases. We utilized Survival and Survminer package for survival analysis based on Kaplan-Meier method. The association between ARHGAP44 expression with the prognosis of OS was determined by Wilcoxon rank-sum test and multivariate Cox regression analysis. The real-time polymerase chain reaction and western blotting were conducted to validate the results. Gene set enrichment analysis was done to find significant Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The OS sample ARHGAP44 expression level was significantly higher than that in normal samples, which was validated in cell lines. High ARHGAP44 expression was associated with metastasis of OS. The OS patients with high ARHGAP44 expression had worse prognosis compared with low ARHGAP44 expression OS patients. In total, 10 KEGG pathways significantly activated in high ARHGAP44 expression OS patients, such as Hedgehog signaling pathway, Steroid biosynthesis, and so on. In summary, high ARHGAP44 expression was closely correlated with the metastasis and poor prognosis of OS. ARHGAP44 was a potential prognostic biomarker for OS.

A Quest for New Cancer Diagnosis, Prognosis and Prediction Biomarkers and Their Use in Biosensors Development

Traditional techniques for cancer diagnosis, such as nuclear magnetic resonance, ultrasound and tissue analysis, require sophisticated devices and highly trained personnel, which are characterized by elevated operation costs. The use of biomarkers has emerged as an alternative for cancer diagnosis, prognosis and prediction because their measurement in tissues or fluids, such as blood, urine or saliva, is characterized by shorter processing times. However, the biomarkers used currently, and the techniques used for their measurement, including ELISA, western-blot, polymerase chain reaction (PCR) or immunohistochemistry, possess low sensitivity and specificity. Therefore, the search for new proteomic, genomic or immunological biomarkers and the development of new noninvasive, easier and cheaper techniques that meet the sensitivity and specificity criteria for the diagnosis, prognosis and prediction of this disease has become a relevant topic. The purpose of this review is to provide an overview about the search for new cancer biomarkers, including the strategies that must be followed to identify them, as well as presenting the latest advances in the development of biosensors that possess a high potential for cancer diagnosis, prognosis and prediction, mainly focusing on their relevance in lung, prostate and breast cancers.

p190RhoGAPs, the ARHGAP35- and ARHGAP5-Encoded Proteins, in Health and Disease

Small guanosine triphosphatases (GTPases) gathered in the Rat sarcoma (Ras) superfamily represent a large family of proteins involved in several key cellular mechanisms. Within the Ras superfamily, the Ras homolog (Rho) family is specialized in the regulation of actin cytoskeleton-based mechanisms. These proteins switch between an active and an inactive state, resulting in subsequent inhibiting or activating downstream signals, leading finally to regulation of actin-based processes. The On/Off status of Rho GTPases implicates two subsets of regulators: GEFs (guanine nucleotide exchange factors), which favor the active GTP (guanosine triphosphate) status of the GTPase and GAPs (GTPase activating proteins), which inhibit the GTPase by enhancing the GTP hydrolysis. In humans, the 20 identified Rho GTPases are regulated by over 70 GAP proteins suggesting a complex, but well-defined, spatio-temporal implication of these GAPs. Among the quite large number of RhoGAPs, we focus on p190RhoGAP, which is known as the main negative regulator of RhoA, but not exclusively. Two isoforms, p190A and p190B, are encoded by ARHGAP35 and ARHGAP5 genes, respectively. We describe here the function of each of these isoforms in physiological processes and sum up findings on their role in pathological conditions such as neurological disorders and cancers.

MicroRNA-638 expression change in osteosarcoma patients via PLD1 and VEGF expression

The present study aimed to investigate the function and mechanism of microRNA-638 (miR-638) in osteosarcoma. MiR-638 expression change in patients with osteosarcoma was detected by reverse transcription-quantitative polymerase chain reaction. Expression of miR-638 was observed to be downregulated in patients with osteosarcoma compared with the control group. In vitro, overexpression of miR-638 induced apoptosis, and inhibited cell proliferation and invasion of osteosarcoma cells. Overexpression of miR-638 induced Bcl-2 associated X and caspase-3 protein expression, and suppressed cyclin D1, phospholipase D1 (PLD1) and vascular endothelial growth factor (VEGF) protein expression in osteosarcoma. The promotion of PLD1 decreased the effects of miR-638 on osteosarcoma cell proliferation. In summary, it was demonstrated that miRNA-638 expression change in patients with osteosarcoma and an in vitro model via PLD1 and VEGF expression and miRNA-638 may be potential clinical indicators of osteosarcoma.

Characterization of potential driver mutations involved in human breast cancer by computational approaches

Breast cancer is the second most frequently occurring form of cancer and is also the second most lethal cancer in women worldwide. A genetic mutation is one of the key factors that alter multiple cellular regulatory pathways and drive breast cancer initiation and progression yet nature of these cancer drivers remains elusive. In this article, we have reviewed various computational perspectives and algorithms for exploring breast cancer driver mutation genes. Using both frequency based and mutational exclusivity based approaches, we identified 195 driver genes and shortlisted 63 of them as candidate drivers for breast cancer using various computational approaches. Finally, we conducted network and pathway analysis to explore their functions in breast tumorigenesis including tumor initiation, progression, and metastasis.

P190RhoGAP prevents mitotic spindle fragmentation and is required to activate Aurora A kinase at acentriolar poles

Assembly of the mitotic spindle is essential for proper chromosome segregation during mitosis. Maintenance of spindle poles requires precise regulation of kinesin- and dynein-generated forces, and improper regulation of these forces disrupts pole integrity leading to pole fragmentation. The formation and function of the mitotic spindle are regulated by many proteins, including Aurora A kinase and the motor proteins Kif2a and Eg5. Here, we characterize a surprising role for the RhoA GTPase-activating protein, p190RhoGAP, in regulating the mitotic spindle. We show that cells depleted of p190RhoGAP arrest for long periods in mitosis during which cells go through multiple transitions between having bipolar and multipolar spindles. Most of the p190RhoGAP-depleted cells finally achieve a stable bipolar attachment and proceed through anaphase. The multipolar spindle phenotype can be rescued by low doses of an Eg5 inhibitor. Moreover, we show that p190RhoGAP-depleted multipolar cells localize Aurora A to all the poles, but the kinase is only activated at the two centriolar poles. Overall, our data identify an unappreciated connection between p190RhoGAP and the proteins that control spindle poles including Aurora A kinase and Eg5 that is required to prevent or correct spindle pole fragmentation.

Genetic susceptibility to bone and soft tissue sarcomas: a field synopsis and meta-analysis

Background

The genetic architecture of bone and soft tissue sarcomas susceptibility is yet to be elucidated. We aimed to comprehensively collect and meta-analyze the current knowledge on genetic susceptibility in these rare tumors.

Methods

We conducted a systematic review and meta-analysis of the evidence on the association between DNA variation and risk of developing sarcomas through searching PubMed, The Cochrane Library, Scopus and Web of Science databases. To evaluate result credibility, summary evidence was graded according to the Venice criteria and false positive report probability (FPRP) was calculated to further validate result noteworthiness. Integrative analysis of genetic and eQTL (expression quantitative trait locus) data was coupled with network and pathway analysis to explore the hypothesis that specific cell functions are involved in sarcoma predisposition.

Results

We retrieved 90 eligible studies comprising 47,796 subjects (cases: 14,358, 30%) and investigating 1,126 polymorphisms involving 320 distinct genes. Meta-analysis identified 55 single nucleotide polymorphisms (SNPs) significantly associated with disease risk with a high (N=9), moderate (N=38) and low (N=8) level of evidence, findings being classified as noteworthy basically only when the level of evidence was high. The estimated joint population attributable risk for three independent SNPs (rs11599754 of ZNF365/EGR2, rs231775 of CTLA4, and rs454006 of PRKCG) was 37.2%. We also identified 53 SNPs significantly associated with sarcoma risk based on single studies.Pathway analysis enabled us to propose that sarcoma predisposition might be linked especially to germline variation of genes whose products are involved in the function of the DNA repair machinery.

Conclusions

We built the first knowledgebase on the evidence linking DNA variation to sarcomas susceptibility, which can be used to generate mechanistic hypotheses and inform future studies in this field of oncology.

Genetic variations in cancer-related significantly mutated genes and lung cancer susceptibility

Background

Cancer initiation and development are driven by key mutations in driver genes. Applying high-throughput sequencing technologies and bioinformatic analyses, The Cancer Genome Atlas (TCGA) project has identified panels of somatic mutations that contributed to the etiology of various cancers. However, there are few studies investigating the germline genetic variations in these significantly mutated genes (SMGs) and lung cancer susceptibility.

Patients and methods

We comprehensively evaluated 1655 tagged single nucleotide polymorphisms (SNPs) located in 127 SMGs identified by TCGA, and test their association with lung cancer risk in large-scale case-control study. Functional effect of the validated SNPs, gene mutation frequency and pathways were analyzed.

Results

We found 11 SNPs in 8 genes showed consistent association (P < 0.1) and 8 SNPs significantly associated with lung cancer risk (P < 0.05) in both discovery and validation phases. The most significant association was rs10412613 in PPP2R1A, with the minor G allele associated with a decreased risk of lung cancer [odds ratio = 0.91, 95% confidence interval (CI): 0.87-0.96, P = 2.3 × 10-4]. Cumulative analysis of risk score built as a weight sum of the 11 SNPs showed consistently elevated risk with increasing risk score (P for trend = 9.5 × 10-9). In stratified analyses, the association of PPP2R1A:rs10412613 and lung cancer risk appeared stronger among population of younger age at diagnosis and never smokers. The expression quantitative trait loci analysis indicated that rs10412613, rs10804682, rs635469 and rs6742399 genotypes significantly correlated with the expression of PPP2R1A, ATR, SETBP1 and ERBB4, respectively. From TCGA data, expression of the identified genes was significantly different in lung tumors compared with normal tissues, and the genes' highest mutation frequency was found in lung cancers. Integrative pathway analysis indicated the identified genes were mainly involved in AKT/NF-κB regulatory pathway suggesting the underlying biological processes.

Conclusion

This study revealed novel genetic variants in SMGs associated with lung cancer risk, which might contribute to elucidating the biological network involved in lung cancer development.

Anticancer effects of 10-hydroxycamptothecin induce apoptosis of human osteosarcoma through activating caspase-3, p53 and cytochrome c pathways

In order to evaluate the anticancer effect of 10-hydroxycamptothecin (HCPT) in terms of inducing the apoptosis of human osteosarcoma cells, its apoptosis-inducing molecular mechanisms were investigated. In the present study, the anticancer effects of HCPT were revealed to result in suppressed cell viability, increased cytotoxicity, the induction of apoptosis and an augmented apoptotic nucleolus of human osteosarcoma cells. MG-63 cells were cultured with HCPT (0, 20, 40 and 80 nM) for 24 and 48 h. An MTT assay and a lactate dehydrogenase assay were used to analyze the anticancer effect of HCPT on cell viability and cytotoxicity in MG-63 cells. MG-63 cell apoptosis, and caspase-9 and caspase-3 activity levels were evaluated using flow cytometry and an ELISA. Western blot analysis was used to detect the protein expression levels of p53, poly (ADP-ribose) polymerase-1 (PARP-1), cytochrome c and B cell lymphoma-2 (Bcl-2) in MG-63 cells. The anticancer effects of HCPT were demonstrated to significantly activate the protein expression of p53, PARP-1 and cytochrome c, and suppress Bcl-2 protein expression and promote the activity of caspase-9 and caspase-3 in human osteosarcoma cells. In conclusion, the anticancer effects of HCPT appear to induce the apoptosis of human osteosarcoma cells through the activation of the caspase-3, p53 and cytochrome c pathways.

Apurinic/apyrimidinic endonuclease 1 regulates angiogenesis in a transforming growth factor β-dependent manner in human osteosarcoma

Angiogenesis plays an important role in tumor growth and metastasis and has been reported to be inversely correlated with overall survival of osteosarcoma patients. It has been shown that apurinic/apyrimidinic endonuclease 1 (APE1), a dually functional protein possessing both base excision repair and redox activities, is involved in tumor angiogenesis, although these mechanisms are not fully understood. Our previous study showed that the expression of transforming growth factor β (TGFβ) was significantly reduced in APE1-deficient osteosarcoma cells. Transforming growth factor β promotes cancer metastasis through various mechanisms including immunosuppression, angiogenesis, and invasion. In the current study, we initially revealed that APE1, TGFβ, and microvessel density (MVD) have pairwise correlation in osteosarcoma tissue samples, whereas TGFβ, tumor size, and MVD were inversely related to the prognosis of the cohort. We found that knocking down APE1 in osteosarcoma cells resulted in TGFβ downregulation. In addition, APE1-siRNA led to suppression of angiogenesis in vitro based on HUVECs in Transwell and Matrigel tube formation assays. Reduced secretory protein level of TGFβ of culture medium also resulted in decreased phosphorylation of Smad3 of HUVECs. In a mouse xenograft model, siRNA-mediated silencing of APE1 downregulated TGFβ expression, tumor size, and MVD. Collectively, the current evidence indicates that APE1 regulates angiogenesis in osteosarcoma by controlling the TGFβ pathway, suggesting a novel target for anti-angiogenesis therapy in human osteosarcoma.

NFKB1 -94ins/del ATTG polymorphism increases osteosarcoma risk in a Chinese Han population

Osteosarcoma is one of the most common bone malignancies. The Nuclear factor-κB1 (NFKB1) gene plays an important role in the pathogenesis of osteosarcoma. The objective of this study aimed to detect the potential association between NFKB1 -94 ins/del ATTG polymorphism and osteosarcoma susceptibility in Chinese Han population. We recruited 220 osteosarcoma patients and 222 cancer-free controls in this case-control study. The NFKB1 -94 ins/del ATTG polymorphism by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Patients with ID genotype and II genotype showed higher risk of osteosarcoma than individuals with DD genotype (OR=1.54, 95% CI 1.00-2.44, P=0.05; OR=1.72, 95% CI 1.01-2.93, P=0.04), respectively. Subjects with ID or II genotype also showed increased risk of osteosarcoma (OR=1.60, 95% CI 1.04-2.47, P=0.03). In addition, I allele was significantly associated with osteosarcoma risk (OR=1.31, 95% CI 1.01-1.71, P=0.04). We also found that this polymorphism was significantly associated with advanced osteosarcoma risk (OR=3.43, 95% CI 1.61-7.36, P=0.001) and metastatic osteosarcoma risk (OR=2.33, 95% CI 1.22-5.03, P=0.01). In conclusion, our findings indicate that osteosarcoma is associated with the NFKB1 promoter -94ins/del ATTG polymorphism.