Role of microchromosome maintenance protein 5 in promoting malignant progression and its mechanism in glioblastoma / 中华神经医学杂志

Objective:To investigate the role of microchromosome maintenance protein 5 (MCM5) in promoting malignant progression and its mechanism in glioblastoma.Methods:(1) Three freshly excised brain tissues from non-tumor patients and 3 grading IV glioblastoma tissues were collected in our hospital from September 2020 to September 2021; mass spectrometry and quantitative proteomic analysis were performed to screen differentially expressed proteins for functional enrichment analysis. (2) The target protein MCM5, which was highly expressed in glioblastoma, was screened on the basis of proteomics, and its expression in glioblastoma was verified using The Cancer Genome Atlas (TCGA) database and further validated at the mRNA level in the collected clinical specimens. (3) U251 cells were divided into negative control group, knockdown group-1 (si-1 group) and knockdown group-2 (si-2 group) by siNRA transfection. The regulation role of MCM5 in malignant phenotype of glioblastoma was detected by CCK-8 assay, clone formation assay, 5-ethynyl-2'-deoxyuridine (EdU)staining, Transwell invasion assay and flow cytometry. (4) The transcriptome data of glioma patients from TCGA database were used to explore the possible molecular mechanisms of MCM5 regulation in the malignant process of glioblastoma by gene set enrichment analysis (GSEA) algorithm.Results:(1) In clinical samples of glioblastoma, 322 up-regulated proteins and 94 down-regulated proteins were screened out; MCM5 was highly expressed in these 3 glioblastoma samples. (2) Based on TCGA database, results of 163 patients with glioblastoma and 207 patients with non-tumor brain tissues showed that MCM5 expression was statistically up-regulated in glioblastoma ( t=3.340, P<0.001). Real-time quantitative PCR results of 3 glioblastoma tissues and 3 non-tumor brain tissues clinically collected in our hospital also indicated that significantly increased MCM5 expression in glioblastoma was noted as compared with that in the non-tumor brain tissues ( t=3.876, P<0.001). (3) As compared with the negative control group, the si-1 and si-2 groups had significantly decreased MCM5 mRNA and protein expressions, significantly lower proliferation rate 5 d after inoculation, statistically decreased number of cell clones, significantly decreased proportion of EdU positive cells, and significantly increased proportion of cells at G1 phase, and significantly impaired migration ability ( P<0.05). (4) GSEA analysis showed that mRNA in MCM5 high expression group was enriched in DNA damage repair gene, E2F target gene, MYC target gene, epithelial-mesenchymal transformation (EMT), nterleukin 6-Janus kinase-signal transduction and transcription activation factor 3 (IL6-JAK-STAT3), interferon, KRAS, NOTCH, transforming growth factor-β (TGF-β), Wnt/β-Catenin and other characteristic genes. Conclusion:MCM5 is highly expressed in glioblastoma, and MCM5 regulates the malignant progression of glioblastoma through multiple mechanisms including E2F, MYC, EMT, and Wnt/β-Catenin.

New evidence for nucleolar dominance in hybrids of Drosophila arizonae and Drosophila mulleri

Drosophila mulleri (MU) and D. arizonae (AR) are cryptic species of the mulleri complex, mulleri subgroup, repleta group. Earlier cytogenetic studies revealed that these species have different regulatory mechanisms of nucleolar organizing activity. In these species, nucleolar organizing regions are found in both the X chromosome and the microchromosome. In the salivary glands of hybrids between MU females and AR males, there is an interspecific dominance of the regulatory system of the D. arizonae nucleolar organizer involving, in males, amplification and activation of the nucleolar organizer from the microchromosome. The authors who reported these findings obtained hybrids only in that cross-direction. More recently, hybrids in the opposite direction, i.e., between MU males and AR females, have been obtained. The purpose of the present study was to evaluate, in these hybrids, the association of the nucleoli with the chromosomes inherited from parental species in order to cytogenetically confirm the dominance patterns previously described. Our results support the proposed dominance of the AR nucleolar organizer activity over that of MU, regardless of cross-direction.

A Bisatellited Supernumerary Marker Chromosome Associated With Recurrent Miscarriages.

(RSAs) revealed the presence of a supernumerary, metacentric, bisatellited microchromosome marker in the male partner. His karyotype was 47,XY,+mar. Molecular analysis revealed the marker to be an idic 14 or 22 (q11-12). We herein discuss two aspects with respect to the presence of the marker: firstly, the karyotype-phenotype relationship in the carrier as well as the possibility of the marker causing abnormality in the next generation and, secondly, the possible role of the marker in the causation of RSAs.