Expulsion of micronuclei containing amplified genes contributes to a decrease in double minute chromosomes from malignant tumor cells
INTERNATIONAL JOURNAL OF CANCER
Authors: Ji, Wei; Bian, Zehua; Yu, Yang; Yuan, Chao; Liu, Yang; Yu, Lisa; Li, Chunxiang; Zhu, Jing; Jia, Xueyuan; Guan, Rongwei; Zhang, Chunyu; Meng, Xiangning; Jin, Yan; Bai, Jing; Yu, Jingcui; Lee, Ki-Young; Sun, Wenjing; Fu, Songbin
Abstract
Double minute chromosomes (DMs) are a hallmark of gene amplification. The relationship between the formation of DMs and the amplification of DM-carried genes remains to be clarified. The human colorectal cancer cell line NCI-H716 and human malignant primitive neuroectodermal tumor cell line SK-PN-DW are known to contain many DMs. To examine the amplification of DM-carried genes in tumor cells, we performed Affymetrix SNP Array 6.0 analyses and verified the regions of amplification in NCI-H716 and SK-PN-DW tumor cells. We identified the amplification regions and the DM-carried genes that were amplified and overexpressed in tumor cells. Using RNA interference, we downregulated seven DM-carried genes, (NDUFB9, MTSS1, NSMCE2, TRIB1, FAM84B, MYC and FGFR2) individually and then investigated the formation of DMs, the amplification of the DM-carried genes, DNA damage and the physiological function of these genes. We found that suppressing the expression of DM-carried genes led to a decrease in the number of DMs and reduced the amplification of the DM-carried genes through the micronuclei expulsion of DMs from the tumor cells. We further detected an increase in the number of H2AX foci in the knockdown cells, which provides a strong link between DNA damage and the loss of DMs. In addition, the loss of DMs and the reduced amplification and expression of the DM-carried genes resulted in a decrease in cell proliferation and invasion ability. What's new? Double-minute chromosomes (DMs) are a hallmark of gene amplification and a major cytogenetic characteristic of malignant tumor cells. The function of DMs and DM-carried genes, however, remains to be clarified. Here, the authors identified amplification regions containing DM-carried genes that were themselves amplified and overexpressed in human malignant tumor cells. Knocking down the DM-carried amplified genes individually, they found that suppression of such oncogenes reduced the number of DMs, the amplification of these DM-carried genes, and cellular function. DNA damage and expulsion of micronuclei containing these DM-carried amplified genes may contribute to the decrease of DMs in tumor cells.
UBE2I promotes metastasis and correlates with poor prognosis in hepatocellular carcinoma
CANCER CELL INTERNATIONAL
Authors: Yang, Hao; Gao, Shan; Chen, Jing; Lou, Weiyang
Abstract
Background A comprehensive investigation of ubiquitin-conjugating enzyme E2I (UBE2I) in cancer is still insufficiency. In this study, we aimed to analyze its role and mechanism in cancer by combination of bioinformatic analysis and experimental validation. Methods The expression profile of UBE2I in human cancers were obtained using GEPIA. Kaplan-Meier plotter was used to assess the prognostic values of UBE2I in diverse types of cancer. ROC curve analysis was employed to determine the diagnostic role of UBE2I in hepatocellular carcinoma (HCC). The expression differences based on various clinicopathological features was evaluated by UALCAN. Wound healing assay and transwell invasion assay were used to detected the effects of UBE2I on migration and invasion of HCC cells, respectively. The miRNA regulatory mechanism of UBE2I was successively investigated by binding prediction, expression analysis, survival analysis and dual-luciferase reporter assay. The correlation of UBE2I mRNA expression and UBE2I promoter methylation level was assessed using cBioPortal. STRING was finally introduced to perform co-expression analysis and enrichment analysis for UBE2I. Results UBE2I was upregulated in HCC, correlated with cancer progression and poor prognosis of HCC. We also found a significant diagnostic value of UBE2I in HCC. Functional experiments revealed that knockdown of UBE2I significantly inhibited HCC migration and invasion. Further research on mechanism suggested that loss of inhibition of hsa-miR-195-3p and dysregulation of UBE2I promoter methylation might account for UBE2I overexpression in HCC. Analysis of UBE2I-invovled regulatory network identified six key genes (NSMCE2, SAE1, UBA2, RANGAP1, SUMO1 and SUMO2) whose expression linked to poor prognosis in HCC. Conclusions In conclusion, UBE2I may be a promising therapeutic target and biomarker in cancer, especially HCC.