Effects of lycopene on protein expression in human primary prostatic epithelial cells.

Clinical trials and animal studies have suggested that lycopene, the red carotenoid found in tomatoes, might be useful for the prevention of prostate cancer in the diet or as a dietary supplement through a variety of chemoprevention mechanisms. As most mechanism of action studies have used prostate cancer cells or males with existing prostate cancer, we investigated the effects of lycopene on protein expression in human primary prostatic epithelial cells. After treatment with lycopene at a physiologically relevant concentration (2 µmol/L) or placebo for 48 hours, the primary prostatic epithelial cells were lysed and fractionated using centrifugation into cytosolic/membrane and nuclear fractions. Proteins from lycopene-treated and placebo-treated cells were trypsinized and derivatized for quantitative proteomics using isobaric tags for relative and absolute quantitation (iTRAQ) reagent. Peptides were analyzed using two-dimensional microcapillary high-performance liquid chromatography-tandem mass spectrometry to identify proteins that were significantly upregulated or downregulated following lycopene exposure. Proteins that were most affected by lycopene were those involved in antioxidant responses, cytoprotection, apoptosis, growth inhibition, androgen receptor signaling, and the Akt/mTOR cascade. These data are consistent with previous studies suggesting that lycopene can prevent cancer in human prostatic epithelial cells at the stages of cancer initiation, promotion, and/or progression.

MicroRNA conjugated gold nanoparticles and cell transfection.

While the importance of microRNAs (miRNAs) in cancer treatment or manipulation of genetic expression has been increasingly recognized for developing miRNA-based therapies, the controlled delivery of miRNAs into specific cells constitutes a challenging task. This report describes preliminary findings from an investigation of the conjugation of gold nanoparticles with miRNAs (miRNA-AuNPs) and their cell transfection. The immobilization of miRNAs on the AuNPs was detected, and the surface stability was substantiated by gel electrophoresis assessment of the highly charged characteristics of miRNA-AuNPs and their surface-exchange inactivity with a highly charged surfactant. The miRNA-AuNPs were tested in cell transfection using multiple myeloma cells, demonstrating efficient knockdown in the functional luciferase assay. The findings have important implications for understanding the mechanistic details of cell transfection involving miRNA-conjugated nanoparticles as biosensing or targeting probes.

Role for microRNAs in regulating glucocorticoid response and resistance in multiple myeloma.

Glucocorticoids (GCs) are widely used in the treatment of hematological malignancies such as multiple myeloma. However, the development of resistance to GCs limits their clinical utility. Response to GCs is dependent on an active glucocorticoid receptor, GR-α, expressed at wild-type levels in the GC-sensitive cell line (MM.1S). GC-resistant derivative cell lines MM.1Re and MM.1RL display significant downregulation of GR-α transcripts. In this study, we report that a luciferase reporter containing the 3'-UTR of GR-α is significantly repressed in MM.1R cells when compared to MM.1S cells, suggesting that one or several microRNAs that are upregulated in MM.1R maybe in part responsible for the downregulation of the GR-α transcript. To examine posttranscriptional mechanisms of GR regulation, we examined miRNAs that have complimentary binding sites in the 3'-UTR of GR-α and found miR-130b, miR-181a, and miR-636 to be differentially expressed between GC-sensitive and GC-resistant MM.1 cell lines. Overexpression of miR-130b in MM.1S cells results in decreased expression of endogenous GR protein and decreased activity of the luciferase reporter. In addition, in MM.1S cells, the downstream GC response of glucocorticoid-induced leucine zipper induction is decreased by the overexpression of miR-130b, and further miR-130b inhibits GC-induced apoptosis and causes resistance to GCs.

Steroid receptor and microRNA regulation in cancer.

PURPOSE OF REVIEW: Steroid hormone receptors (SHR) are crucial regulators of disease and the basis for clinical intervention in cancers. Recent evidence confirms that microRNAs (miRNAs) impact the pathobiology of hormone-regulated malignancies. Therefore, elucidating miRNA regulation of SHR expression and modulation of miRNAs by SHRs may provide diagnostic biomarkers or therapeutic targets. RECENT FINDINGS: Estrogen receptor status has been established as a key factor in breast cancer prognosis and treatment. Recent studies detail the interactions between estrogen receptor and miRNAs in cancers. New evidence indicates involvement of miRNAs in the regulation of androgen receptor, progesterone receptor, glucocorticoid receptor in hormone responsive cancers. Several miRNAs regulate the expression of the SHRs, while other miRNAs are themselves regulated by SHR signaling in cancer. SUMMARY: Cancers have distinct miRNA expression profiles that contribute to the pathobiology of the disease. In hormone-responsive cancers, the regulatory interactions between the SHR and miRNA may contribute to disease progression. The miRNA regulation of estrogen receptor in cancer has been established in estrogen-dependent cancers. The role of miRNAs in regulating progesterone receptor, androgen receptor and glucocorticoid receptor is under investigation with new insights emerging. These interactions can provide prognostic utility as well as the potential for therapeutic intervention in the future.

A collection of bioconductor methods to visualize gene-list annotations.

BACKGROUND: Gene-list annotations are critical for researchers to explore the complex relationships between genes and functionalities. Currently, the annotations of a gene list are usually summarized by a table or a barplot. As such, potentially biologically important complexities such as one gene belonging to multiple annotation categories are difficult to extract. We have devised explicit and efficient visualization methods that provide intuitive methods for interrogating the intrinsic connections between biological categories and genes. FINDINGS: We have constructed a data model and now present two novel methods in a Bioconductor package, "GeneAnswers", to simultaneously visualize genes, concepts (a.k.a. annotation categories), and concept-gene connections (a.k.a. annotations): the "Concept-and-Gene Network" and the "Concept-and-Gene Cross Tabulation". These methods have been tested and validated with microarray-derived gene lists. CONCLUSIONS: These new visualization methods can effectively present annotations using Gene Ontology, Disease Ontology, or any other user-defined gene annotations that have been pre-associated with an organism's genome by human curation, automated pipelines, or a combination of the two. The gene-annotation data model and associated methods are available in the Bioconductor package called "GeneAnswers " described in this publication.