Objective: To explore the mechanism of long non-coding RNA POU3F3 (lncRNAPOU3F3) affecting temozolomide (TMZ)-resistance in high-grade glioma cells via regulating MGMT expression. Methods: Sixty cases of tissues from patients treated at the Department of Neurosurgery, Peking University International Hospital during January 2016 and January 2018 were collected for this study, including 12 cases from brain trauma patients (normal group), 30 cases from primary high-grade glioma patients (primary onset group) and 18 cases from recurrent high-grade glioma patients (recurrence group, accepted surgery+TMZ already). U251 cells were induced with TMZ at the concentration of 1, 2, 4 and 8 μg/ml and maintained normal growth for a week to construct TMZ-resistant U251cell line (U251 TMZ-resistance, U251-TR); and the normal control group was treated with equal volume of physiological saline. Reverse transcription polymerase chain reaction (qPCR) and Wb were used to detect the mRNA and protein expressions of POU3F3 and MGMT (methylguanine DNA methyltransferase) in normal brain tissues and glioma cells. Lentivirus transfection was used to construct U251 cell line with stable POU3F3 interference (U251-TR siPOU3F3); CCK-8 was used to detect TMZ IC50 value (the half maximal inhibitory concentration) in each group of U251 cells, and Wb was used to detect the expression of MGMT protein in each group of cells. Results: Compared with the normal group and primaryonset group, the expression of POU3F3 in recurrence group was significantly increased (P<0.01). The TMZ IC50 of U251-TR cells was significantly higher than that of U251 cells (P<0.01), and The TMZ IC50 of U251-TR siPOU3F3 cells was significantly lower than that of U251-TR cellsbut higher than that of U251 cells (all P<0.01). The protein and mRNA expressions of POU3F3 and MGMT in U251-TR cells were significantly higher than that in U251 cells (P<0.01), while those expressions in U251-TR siPOU3F3 cells were significantly lower than those in U251-TR cells (P<0.01).Conclusion: lncRNAPOU3F3 is the key factor to promote TMZ resistance in human high-grade gliomas cells, which may exert certain guiding significance in the clinical treatment for TMZ resistance.

Identification of genetic variants via high-throughput sequencing (HTS) technologies has been essential for both fundamental and clinical studies. However, to what extent the genome sequence composition affects variant calling remains unclear. In this study, we identified 63,897 multi-copy sequences (MCSs) with a minimum length of 300 bp, each of which occurs at least twice in the human genome. The 151,749 genomic loci (multi-copy regions, or MCRs) harboring these MCSs account for 1.98％of the genome and are distributed unevenly across chromosomes. MCRs containing the same MCS tend to be located on the same chromosome. Gene Ontology (GO) anal-yses revealed that 3800 genes whose UTRs or exons overlap with MCRs are enriched for Golgi-related cellular component terms and various enzymatic activities in the GO biological function cat-egory. MCRs are also enriched for loci that are sensitive to neocarzinostatin-induced double-strand breaks. Moreover, genetic variants discovered by genome-wide association studies and recorded indbSNP are significantly underrepresented in MCRs. Using simulated HTS datasets, we show that false variant discovery rates are significantly higher in MCRs than in other genomic regions. These results suggest that extra caution must be taken when identifying genetic variants in the MCRs via HTS technologies.