Ki-67 and MCM6 labeling indices are correlated with overall survival in anaplastic oligodendroglioma, IDH1-mutant and 1p/19q-codeleted: a multicenter study from the French POLA network
BRAIN PATHOLOGY
Authors: Rouget, Celso; Hergalant, Sbastien; Lardenois, Emilie; Lacomme, Stphanie; Houlgatte, Rmi; Carpentier, Catherine; Dehais, Caroline; Rech, Fabien; Taillandier, Luc; Sanson, Marc; Appay, Romain; Colin, Carole; Figarella-Branger, Dominique; Battaglia-Hsu, Shyue-Fang; Gauchotte, Guillaume; Desenclos, Christine; Sevestre, H.; Menei, Philippe; Rousseau, A.; Cruel, T.; Lopez, S.; Mihai, M., I; Petit, A.; Seizeur, R.; Quintin-Roue, I; Adam, C.; Parker, F.; Elmer, S.; Loiseau, H.; Bekaert, L.; Chapon, F.; Ricard, D.; Godfraind, C.; Khallil, T.; Cazals-Hatem, D.; Faillot, T.; Gaultier, C.; Tortel, M. C.; Carpiuc, I; Richard, P.; Lahiani, W.; Aubriot-Lorton, H.; Ghiringhelli, F.; Maurage, C-A; Le Rhun, E.; Gueye, E. M.; Labrousse, F.; Ducray, F.; Meyronet, D.; Chinot, O.; Bauchet, L.; Rigau, V; Beauchesne, P.; Campone, M.; Loussouarn, D.; Fontaine, D.; Vandenbos-Burel, F.; Le Floch, A.; Roger, P.; Blechet, C.; Fesneau, M.; Carpentier, A.; Idbaili, A.; Delattre, I. Y.; Mokhtari, K.; Bielle, F.; Harndi, S.; Polivka, M.; Milin, S.; Colin, P.; Diebold, M. D.; Chiforeanu, D.; Vauleon, E.; Langlois, O.; Laquerriere, A.; Forest, F.; Motso-Fotso, M. L.; Andraud, M.; Runavot, G.; Lhermitte, B.; Noel, G.; Gaillard, S.; Villa, C.; Desse, N.; Rousselot-Denis, C.; Zemmoura, I; Cohen-Moyal, E.; Uro-Coste, E.; Dhermain, F.
Abstract
Anaplastic oligodendroglioma (AO), IDH-mutant and 1p/19q codeleted (IDHmut+/1p19qcodel), is a high-grade glioma with only limited prognostic markers. The primary objective of this study was to evaluate, by immunohistochemistry, the prognostic value of two proliferation markers, MCM6 and Ki-67, in a large series of IDHmut+/1p19qcodel AO included in the POLA ("Prise en charge des Oligodendrogliomes Anaplasiques") French national multicenter network. We additionally examined the transcriptome obtained from this series to understand the functional pathways dysregulated with the mRNA overexpression of these two markers. The labeling indices (LI) of MCM6 and Ki-67 were obtained via computer-assisted color image analyses on immunostained AO tissues of the cohort (n = 220). Furthermore, a subgroup of AO (n = 68/220) was used to perform transcriptomic analyses. A high LI of either MCM6 (>= 50%) or Ki-67 (>= 15%) correlated with shorter overall survival, both in univariate (P = 0.013 and P = 0.004, respectively) and multivariate analyses (P = 0.027; multivariate Cox model including age, mitotic index, MCM6 and Ki-67). MCM6 and Ki-67 LI also correlated with overall survival in an additional retrospective cohort of 30 grade II IDHmut+/1p19qcodel oligodendrogliomas. The prognostic value of MCM6 mRNA level was confirmed in The Cancer Genome Atlas (TCGA) IDHmut+/1p19qcodel gliomas. The transcriptomic approach revealed that high transcriptional expressions of MCM6 and MKI67 were both linked positively with cell cycle progression, DNA replication, mitosis, pro-neural phenotype as well as neurogenesis, and negatively with microglial cell activation, immune response, positive regulation of myelination, oligodendrocyte development, beta-amyloid binding and postsynaptic specialization. In conclusion, the overexpression of MCM6 and/or Ki-67 is independently associated to shorter overall survival in IDHmut+/1p19qcodel AO. These two easy-to-use and cost-effective markers could thus be used concurrently in routine pathology practice. Additionally, the transcriptomic analyses showed that AO with high proliferation index have down-regulated immune response and lower microglial cells activation, and bears pro-neural phenotype.
Comprehensive Analysis of Replication Origins in Saccharomyces cerevisiae Genomes
FRONTIERS IN MICROBIOLOGY
Authors: Wang, Dan; Gao, Feng
Abstract
DNA replication initiates from multiple replication origins (ORIs) in eukaryotes. Discovery and characterization of replication origins are essential for a better understanding of the molecular mechanism of DNA replication. In this study, the features of autonomously replicating sequences (ARSs) in Saccharomyces cerevisiae have been comprehensively analyzed as follows. Firstly, we carried out the analysis of the ARSs available in S. cerevisiae S288C. By evaluating the sequence similarity of experimentally established ARSs, we found that 94.32% of ARSs are unique across the whole genome of S. cerevisiae S288C and those with high sequence similarity are prone to locate in subtelomeres. Subsequently, we built a non-redundant dataset with a total of 520 ARSs, which are based on ARSs annotation of S. cerevisiae S288C from SGD and then supplemented with those from OriDB and DeOri databases. We conducted a largescale comparison of ORIs among the diverse budding yeast strains from a population genomics perspective. We found that 82.7% of ARSs are not only conserved in genomic sequence but also relatively conserved in chromosomal position. The non-conserved ARSs tend to distribute in the subtelomeric regions. We also conducted a pan-genome analysis of ARSs among the S. cerevisiae strains, and a total of 183 core ARSs existing in all yeast strains were determined. We extracted the genes adjacent to replication origins among the 104 yeast strains to examine whether there are differences in their gene functions. The result showed that the genes involved in the initiation of DNA replication, such as orc3, mcm2, mcm4, mcm6, and cdc45, are conservatively located adjacent to the replication origins. Furthermore, we found the genes adjacent to conserved ARSs are significantly enriched in DNA binding, enzyme activity, transportation, and energy, whereas for the genes adjacent to non-conserved ARSs are significantly enriched in response to environmental stress, metabolites biosynthetic process and biosynthesis of antibiotics. In general, we characterized the replication origins from the genome-wide and population genomics perspectives, which would provide new insights into the replication mechanism of S. cerevisiae and facilitate the design of algorithms to identify genome-wide replication origins in yeast.