Molecular and clinicopathologic characterization of pediatric histiocytoses.

The spectrum of somatic mutations in pediatric histiocytoses and their clinical implications are not fully characterized, especially for non-Langerhans cell histiocytosis (-LCH) subtypes. A cohort of 415 children with histiocytosis from the French histiocytosis registry was reviewed and analyzed for BRAFV600E . Most BRAFWT samples were analyzed by next-generation sequencing (NGS) with a custom panel of genes for histiocytosis and myeloid neoplasia. Of 415 case samples, there were 366 LCH, 1 Erdheim-Chester disease, 21 Rosai-Dorfman disease (RDD), 21 juvenile xanthogranuloma (JXG, mostly with severe presentation), and 6 malignant histiocytosis (MH). BRAFV600E was the most common mutation found in LCH (50.3%, n = 184). Among 105 non-BRAFV600E -mutated LCH case samples, NGS revealed mutations as follows: MAP2K1 (n = 44), BRAF exon 12 deletions (n = 26), and duplications (n = 8), other BRAF V600 codon mutation (n = 4), and non-MAP-kinase pathway genes (n = 5). Wild-type sequences were identified in 17.1% of samples. BRAFV600E was the only variant significantly correlated with critical presentations: organ-risk involvement and neurodegeneration. MAP-kinase pathway mutations were identified in seven RDD (mostly MAP2K1) and three JXG samples, but most samples were wild-type on NGS. Finally, two MH samples had KRAS mutations, and one had a novel BRAFG469R mutation. Rarely, we identified mutations unrelated to MAP-kinase pathway genes. In conclusion, we characterized the mutational spectrum of childhood LCH and clinical correlations of variants and subtypes. Variants responsible for JXG and RDD were not elucidated in more than half of the cases, calling for other sequencing approaches.

CDKN2A Depletion Causes Aneuploidy and Enhances Cell Proliferation in Non-Immortalized Normal Human Cells.

Aneuploidy is a common feature of cancer cells and may contribute to cellular transformation and cancer development. In this study, we found that significant down-regulation of CDKN2A, CHEK2, CDCA8, TP53BP1, and CCNDBP1 led to chromosome imbalances in two diploid non-immortalized human cell lines; however, only CDKN2A inhibition enhanced cell proliferation and additionally up-regulated three cell cycle control genes: CDCA8, AURKA, and CCND. These results confirm that CDKN2A is a tumor suppressor gene driving human cancer development by inducing cell aneuploidy and cell cycle up-regulation.

Expression of cystic fibrosis transmembrane conductance regulator in the human distal lung.

The determination of the expression of cystic fibrosis transmembrane conductance regulator (CFTR) in the lung is essential for a full understanding of the normal lung physiology and the pathogenesis of the lung disease in cystic fibrosis (CF). However, studies on the expression of CFTR in the distal adult human lung have yielded conflicting results despite functional evidence of expression of CFTR in bronchiolar and alveolar epithelial cells. We used 2 high-affinity monoclonal anti-CFTR antibodies, MAb24-1 and MAb13-1, to determine the expression of CFTR in samples of bronchiolar and alveolar tissues obtained from the same non-CF individuals. CFTR immunostaining was detected in the epithelium of bronchiolar and alveolar tissues. The staining pattern was similar with both antibodies. In bronchioles, CFTR labeling was present mostly in ciliated cells; in alveoli, CFTR labeling was detected in both type I and type II cells. We conclude that CFTR is expressed in human bronchiolar and alveolar epithelial cells. The potential importance of CFTR expression in alveoli should be further investigated, particularly with respect to the CF lung disease and the physiology of the alveolar region.