Identification of Candidate Genes Associated with Breast Cancer Prognosis
DNA AND CELL BIOLOGY
Authors: Xu, Yun-Hua; Deng, Jun-Li; Wang, Li-Ping; Zhang, Hai-Bo; Tang, Lu; Huang, Ying; Tang, Jie; Wang, Shou-Man; Wang, Guo
Abstract
Breast cancer (BC) is the most malignant tumor in women. The molecular mechanisms underlying tumorigenesis still need to be further elucidated. It is necessary to investigate novel candidate genes involved in breast cancer progression and prognosis. In this study, we commit to explore candidate genes that associate with prognosis and therapy in BC by a comprehensive bioinformatic analysis. Four GEO datasets (GSE5764, GSE7904, GSE20711, and GSE29431) and the BC-related transcriptome data in TCGA database were downloaded and used to identify the differently expressed genes (DEGs). The function of DEGs was analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis. The protein-protein interaction (PPI) network of DEGs was constructed to identify hub genes. Prognostic candidate genes were identified through survival analysis. In addition, potential therapeutic targets were identified by constructed gene-drug interaction network through Comparative Toxicogenomics Database. A total of 547 DEGs (302 up and 245 down) were identified. Three core-subnetwork and 25 hub genes were identified in PPI network. Seven genes (namely COL12A1, QPRT, MRPL13, KRT14, KRT15, LAMB3, and MYBPC1) were identified as crucial prognostic candidate genes, which significantly associated with breast cancer overall survival. Furthermore, two representative candidate genes (COL12A1 and LAMB3) were optionally chosen for verification by reverse transcription and quantitative real-time polymerase chain reaction (RT-PCR). What's more, the gene-drugs interaction analysis indicates several antitumor drugs that could affect the expression of these prognostic markers, such as doxorubicin, cisplatin, and tamoxifen. These results identified seven crucial candidate genes that may serve as prognosis biomarkers and novel therapeutic targets of breast cancer, which may facilitate further understanding the molecular pathogenesis and providing potential therapeutic strategies for BC.
Mtbp haploinsufficiency in mice increases tumor metastasis
ONCOGENE
Authors: Iwakuma, T.; Tochigi, Y.; Van Pelt, C. S.; Caldwell, L. C.; Terzian, T.; Parant, J. M.; Chau, G. P.; Koch, J. G.; Eischen, C. M.; Lozano, G.
Abstract
Mdm2 inhibits the function of the p53 tumor suppressor. Mdm2 is overexpressed in many tumors with wild-type p53 suggesting an alternate mechanism of loss of p53 activity in tumors. An Mdm2-binding protein (MTBP) was identified using a yeast two-hybrid screen. In tissue culture, MTBP inhibits Mdm2 self-ubiquitination, leading to stabilization of Mdm2 and increased degradation of p53. To address the role of MTBP in the regulation of the p53 pathway in vivo, we deleted the Mtbp gene in mice. Homozygous disruption of Mtbp resulted in early embryonic lethality, which was not rescued by loss of p53. Mtbp(+/-) mice were not tumor prone. When mice were sensitized for tumor development by p53 heterozygosity, we found that the Mtbp(+/-)p53(+/-) mice developed significantly more metastatic tumors (18.2%) as compared to p53(+/-) mice (2.6%). Results of in vitro migration and invasion assays support the in vivo findings. Downmodulation of Mtbp in osteosarcoma cells derived from p53(+/-) mice resulted in increased invasiveness, and overexpression of Mtbp in Mtbp(+/-)p53(+/-) osteosarcoma cells inhibited invasiveness. These results suggest that MTBP is a metastasis suppressor. These results advance our understanding of the cellular roles of MTBP and raise the possibility that MTBP is a novel therapeutic target for metastasis.