Mitochondria are important integrators of cellular function and therefore affect the homeostatic balance of the cell. Besides their important role in producing adenosine triphosphate through oxidative phosphorylation, mitochondria are involved in the control of cytosolic calcium concentration, metabolism of key cellular intermediates, and Fe/S cluster biogenesis and contributed to programmed cell death. Mitochondria are also one of the major cellular producers of reactive oxygen species (ROS). Several human pathologies, including neurodegenerative diseases and cancer, are associated with mitochondrial dysfunction and increased ROS damage. This article reviews how dysfunctional mitochondria contribute to Alzheimer's disease, Parkinson's disease, Huntington's disease, and several human cancers.

Brain tumors are the leading cause of death in children. Establishing an accurate diagnosis and therapy is critical for patient management. This study evaluated the clinical utility of GlioSeq, a next-generation sequencing (NGS) assay, for the diagnosis and management of pediatric and young adult patients with brain tumors. Between May 2015 and March 2017, 142 consecutive brain tumors were tested using GlioSeq v1 and subset using GlioSeq v2. Out of 142 samples, 63% were resection specimens and 37% were small stereotactic biopsies. GlioSeq sequencing was successful in 100% and 98.6% of the cases for the detection of mutations and copy number changes, and gene fusions, respectively. Average turnaround time was 8.7 days. Clinically significant genetic alterations were detected in 95%, 66.6%, and 66.1% of high-grade gliomas, medulloblastomas, and low-grade gliomas, respectively. GlioSeq enabled molecular-based stratification in 92 (65%) cases by specific molecular subtype assignment (70, 76.1%), substantiating a neuropathologic diagnosis (18, 19.6%), and diagnostic recategorization (4, 4.3%). Fifty-seven percent of the cases harbored therapeutically actionable findings. GlioSeq NGS analysis offers rapid detection of a wide range of genetic alterations across a spectrum of pediatric brain tumors using formalin-fixed, paraffin-embedded specimens and facilitates integrated molecular-morphologic classification and personalized management of pediatric brain tumors.

Desmoplastic melanomas (DMs) are often challenging to diagnose and ancillary tests, such as immunohistochemistry, have limitations. One challenge is distinguishing DM from benign desmoplastic melanocytic neoplasms. In this study, we explored the utility of next-generation sequencing data in the diagnosis of DMs versus desmoplastic Spitz nevi (DSN) and desmoplastic nevi (DN). We sequenced 47 cases and retrieved 12 additional previously sequenced clinical cases from our dermatopathology database. The 59 total cases were comprised of 21 DMs, 25 DSN, and 13 DN. The DMs had the highest tumor mutation burden at 22 mutations/megabase (m/Mb) versus the DSN (6 m/Mb) and DN (8 m/Mb). Truncating mutations in NF1 resulting in a loss-of-function were exclusive to the DM cohort, identified in 8/21 (38%) cases. Importantly, missense mutations in NF1 were nonspecific and seen with similar frequency in the different cohorts. Other mutations exclusive to the DMs included truncating mutations in TP53, CDKN2A, and ARID2. Among the DSN, 17/25 (68%) had an HRAS mutation or receptor tyrosine kinase fusion consistent with other Spitz tumors. Two cases in the DN cohort had missense mutations in BRAF without additional progression mutations and 2 other cases had mutations in GNAQ, supporting a diagnosis of a sclerosing blue nevus. The remainder of the DN had nonspecific mutations in various signaling pathways with few progression mutations. Overall, our study provides preliminary data that next-generation sequencing data may have the potential to serve as an ancillary diagnostic tool to help differentiate malignant and benign desmoplastic melanocytic neoplasms.

Background Patients with regionally advanced melanoma were treated with neoadjuvant ipilimumab in a previously reported study (Tarhini et al, PLOS One 2014). MicroRNA (miRNA) expression profiles of tumors of treated patients were investigated for their therapeutic predictive value. Methods Patients were treated with ipilimumab (10 mg/kg IV every 3 weeks x2 doses) bracketing surgery. Tumor specimens were obtained at baseline and following ipilimumab at definitive surgery (week 6-8). MiRNA expression profiling was performed on the tumor biopsies of 30 patients using Affymetrix miRNA array (v.4). Significance Analysis of Microarrays (SAM) was performed to test the association of each differentially expressed miRNA molecule with outcome. Targets of the selected miRNAs were obtained from miRTarBase (http://mirtarbase.mbc.nctu.edu.tw). Functional annotation analysis of the list of miRNA target genes were performed using DAVID (https://david.ncifcrf.gov). The FDR method was used to adjust for multiple testing in SAM and the functional analysis. Results An expression profile consisting of a 4-miRNA signature was associated with improved progression free survival. The signature consisted of miR-34c (previously reported to suppress cancer growth and invasion), miR-711 (reported as a prognostic marker in cutaneous T-cell lymphomas and to target and suppress Heat Shock Protein 70 highly expressed in melanoma), miR-641 (activates MAPK by targeting NF1 and cooperates with its host gene AKT2 in human cancer) and miR-22 (reported to function as a tumour suppressor). Functional annotation analysis of target genes for the 4-miRNA signature was statistically significantly enriched for various cancer-related pathways including regulation of cell proliferation (GO:0042147), regulation of apoptosis (GO:0042981), MAPK signaling pathway (hsa04010) and positive regulation of T cell activation (GO:0050870). Conclusions MiRNA expression profiling identified a 4-miRNA signature that is significantly associated with PFS in advanced melanoma patients treated with neoadjuvant ipilimumab. Preliminary results show that targets of these 4 miRNAs are biologically relevant and important. These findings warrant further investigation in relation to ipilimumab and other immunotherapeutics. Citation Format: Ahmad Tarhini, Priyanka Vallabhaneni, Theofanis Floros, William A. LaFramboise, Panayiotis V. Benos, Lucas Santana dos Santos. A tumor and immune related miRNA signature predicts progression-free survival of melanoma patients treated with ipilimumab. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 473.

We describe a pediatric patient with an intra-axial tumor; histopathologic examination of the resected specimen was unable to establish a precise diagnosis. While the initial targeted next-generation sequencing (NGS) panel was also nondiagnostic, genomic DNA methylation profiling indicated that the tumor was an astroblastoma, MN1-altered. A more comprehensive NGS panel was then run, which confirmed an MN1-BEND2 fusion. This case displays the limitations and pitfalls of a histological and immunohistochemical-based diagnosis in a case of an infrequently encountered pediatric brain tumor. Furthermore, it highlights the growing need for performing DNA methylation, paired with a comprehensive NGS panel, to ensure an accurate diagnosis in modern surgical neuropathology.