Frequent LOH at chromosome 12q22-23 and Apaf-1 inactivation in glioblastoma

Mass spectrometry-based iTRAQ analysis of serum markers in patients with pancreatic cancer

Early biomarkers for pancreatic cancer (PC) detection are required in order to improve patient outcomes. The present study aimed to identify serum biomarkers for PC diagnosis using proteomics, unveil the underlying pathological mechanisms and provide reliable data for the early diagnosis of PC. Isobaric tags for relative and absolute quantification and two-dimensional-liquid chromatography-tandem mass spectometry were used to compare serum samples from patients with PC and healthy individuals. Mascot and Scaffold were used for raw data processing, and Panther for gene ontology (GO) analysis. Igenuity^® Pathway Analysis (IPA) was utilized to assess canonical pathways and protein-protein interactions. In total, 76 differentially expressed proteins were identified. The candidate protein DNA repair protein 50 (RAD50) was elevated in patients with PC compared with healthy individuals. In addition, transforming growth factor-β1 (TGF-β1) and apoptotic protease activating factor 1 (APAF-1) were downregulated in PC. GO analysis revealed that the extracellular matrix was increased in PC, as well as receptor function and enzyme regulation; additionally, reduced nucleic acid binding transcription factor activity was observed. IPA analysis demonstrated that the significantly altered canonic pathways were liver X receptor/retinoid X receptor (RXR) activation, the production of nitric oxide and reactive oxygen species in macrophages, the coagulation system, acute phase response signaling and lipopolysaccharide/interleukin-1 mediated inhibition of RXR function. To conclude, RAD50, TGF-β1 and APAF1 are candidate biomarkers for the diagnosis of early PC. The results from the present study could help identify future therapeutic drugs for PC.

Molecular alterations in glioblastoma: potential targets for immunotherapy

Glioblastoma is the most common and deadly brain tumor, possibly arising from genetic and epigenetic alterations in normal astroglial cells. Multiple cytogenetic, chromosomal, and genetic alterations have been identified in glioblastoma, with distinct expression of antigens (Ags) and biomarkers that may alter therapeutic potential of this aggressive cancer. Current therapy consists of surgical resection, followed by radiation therapy and chemotherapy. In spite of these treatments, the prognosis for glioblastoma patients is poor. Although recent studies have focused on the development of novel immunotherapeutics against glioblastoma, little is known about glioblastoma-specific immune responses. A better understanding of the molecular interactions among glioblastoma tumors, host immune cells, and the tumor microenvironment may give rise to novel integrated approaches for the simultaneous control of tumor escape pathways and the activation of antitumor immune responses. This review provides a detailed overview concerning genetic alterations in glioblastoma, their effects on Ag and biomarker expression, and the future design of chemoimmunotherapeutics against glioblastoma.

Frequent promoter hypermethylation of RASSF1A and CASP8 in neuroblastoma

Background

Epigenetic alterations and loss of heterozygosity are mechanisms of tumor suppressor gene inactivation. A new carcinogenic pathway, targeting the RAS effectors has recently been documented. RASSF1A, on 3p21.3, and NORE1A, on 1q32.1, are among the most important, representative RAS effectors.

Methods

We screened the 3p21 locus for the loss of heterozygosity and the hypermethylation status of RASSF1A, NORE1A and BLU (the latter located at 3p21.3) in 41 neuroblastic tumors. The statistical relationship of these data was correlated with CASP8 hypermethylation. The expression levels of these genes, in cell lines, were analyzed by RT-PCR.

Results

Loss of heterozygosity and microsatellite instability at 3p21 were detected in 14% of the analyzed tumors. Methylation was different for tumors and cell lines (tumors: 83% in RASSF1A, 3% in NORE1A, 8% in BLU and 60% in CASP8; cell lines: 100% in RASSF1A, 50% in NORE1A, 66% in BLU and 92% in CASP8). In cell lines, a correlation with lack of expression was evident for RASSF1A, but less clear for NORE1A, BLU and CASP8. We could only demonstrate a statistically significant association between hypermethylation of RASSF1A and hypermethylation of CASP8, while no association with MYCN amplification, 1p deletion, and/or aggressive histological pattern of the tumor was demonstrated.

Conclusion

1) LOH at 3p21 appears in a small percentage of neuroblastomas, indicating that a candidate tumor suppressor gene of neuroblastic tumors is not located in this region.

2) Promoter hypermethylation of RASSF1A and CASP8 occurs at a high frequency in neuroblastomas.