Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:Breast tumors are characterized into different subtypes based on their surface marker expression, which affects their prognosis and treatment. For example, triple negative breast cancer cells (ER-/PR-/Her2-) show reduced susceptibility towards radiotherapy and chemotherapeutic agents. Poly (ADP-ribose) polymerase (PARP) inhibitors have shown promising results in clinical trials, both as single agents and in combination with other chemotherapeutics, in several subtypes of breast cancer patients. PARP1 is involved in DNA repair, apoptosis, and transcriptional regulation and an understanding of the effects of PARP inhibitors, specifically on metabolism, is currently lacking. Here, we have used NMR-based metabolomics to probe the cell line-specific effects of PARP inhibitor and radiation on metabolism in three distinct breast cancer cell lines. Our data reveal several cell line independent metabolic changes upon PARP inhibition, including an increase in taurine. Pathway enrichment and topology analysis identified that nitrogen metabolism, glycine, serine and threonine metabolism, aminoacyl-tRNA biosynthesis and taurine and hypotaurine metabolism were enriched after PARP inhibition in the three breast cancer cell lines. We observed that the majority of metabolic changes due to radiation as well as PARP inhibition were cell line dependent, highlighting the need to understand how these treatments affect cancer cell response via changes in metabolism. Finally, we observed that both PARP inhibition and radiation induced a similar metabolic response in the HCC1937 (BRCA mutant cell line), but not in MCF-7 and MDAMB231 cells, suggesting that radiation and PARP inhibition share similar interactions with metabolic pathways in BRCA mutant cells. Our study emphasizes the importance of differences in metabolic responses to cancer treatments in different subtypes of cancers.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Recent studies have identified clinical subtypes of breast tumors that arise from different cell types and have different outcomes in response to chemotherapy. Tumors derived from basal epithelium have a poorer prognosis than tumors derived from luminal epithelium. To gain insight into differences underlying this disparity, we treated cell lines derived from basal epithelium (immortalized human mammary epithelial cells) and those derived from luminal epithelium (MCF-7 and ZR-75-1) with two chemotherapeutics commonly used in the treatment of breast cancer. Treatment doses for doxorubicin (DOX) and 5-fluorouracil (5FU) were selected to cause comparable cytotoxicity across all four cell lines. The predominant gene expression in each of the four cell lines was a general stress response, but distinct gene expression patterns were observed depending upon cell type. Both cell types up-regulated DNA damage response genes such as p21waf1, but the response in the luminal cells was much more dramatic and included many p53-regulated genes. Luminal cell lines down-regulated a large number of cell cycle regulators and other genes involved in cellular proliferation, while basal cell lines down-regulated a smaller set of genes, many of which are involved in cellular differentiation. These results were compared to gene expression data from tumor samples collected before and after treatment with DOX or 5FU/mitomycin C. Similarities between the in vitro and in vivo responses validate this model for studying gene expression responses to chemotherapy in these cell types. Understanding cell-type specific responses to chemotherapeutics will help in tailoring treatment to patients based upon tumor characteristics. Keywords = breast cancer Keywords = chemotherapy Keywords = gene expression Keywords = microarray Keywords = stress response Keywords: time-course