Project description:The cyclin D1 oncogene encodes the regulatory subunit of a holoenzyme that phosphorylates and inactivates the Rb protein and promotes progression through G1 to S phase of the cell cycle. Several prostate cancer cell lines and a subset of primary prostate cancer samples have increased cyclin D1 protein expression. However, the relationship between cyclin D1 expression and prostate tumor progression has yet to be clearly characterized. This study examined the effects of manipulating cyclin D1 expression in either human prostatic epithelial or stromal cells using a tissue recombination model. The data showed that overexpression of cyclin D1 in the initiated BPH-1 cell line increased cell proliferation rate, but did not elicit tumorigenicity in vivo. However, overexpression of cyclin D1 in Normal Prostate Fibroblasts (NPF) that were subsequently recombined with BPH-1 did induce malignant transformation of the epithelial cells. The present study also showed that recombination of BPH-1 + cyclin D1 overexpressing fibroblasts (NPF cyclin D1) resulted in permanent malignant transformation of epithelial cells (BPH-1 NPF-cyclin D1 cells) similar to that seen with Carcinoma Associated Fibroblasts (CAFs). Microarray analysis showed that the expression profiles between CAFs and NPF cyclin D1 cells were highly concordant including cyclin D1 upregulation. These data indicated that the tumor-promoting activity of cyclin D1 may be tissue-specific. Keywords: cyclin D1; stromal-epithelial interactions; prostate cancer; cDNA microarray
Project description:Cyclin D1 belongs to the core cell cycle machinery1, and it is frequently overexpressed in human cancers2. The full repertoire of cyclin D1 functions in normal development and in cancer cells is currently unknown. To address this question, here we introduce a novel approach that allows one to determine the set of cyclin D1-interacting proteins (D1 “interactome”) and cyclin D1-bound genomic fragments (D1 “cistrome”) in essentially any mouse organ, at any point of development or at any stage of cancer progression. Using this approach, we detected several novel tissue-specific interactors of cyclin D1. A significant number of these partners represent proteins involved in transcription. We show, using genome-wide location analysis3, that cyclin D1 occupies promoters of a very large number of genes in the developing mouse, where it binds in close proximity to transcription start sites. Bioinformatics analyses of cyclin D1-bound genomic segments in the developing embryo revealed DNA recognition sequences for several transcription factors. By querying SAGE libraries4, promoter CpG content5 and gene expression profiles of cyclin D1-null organs, we demonstrate that cyclin D1 binds promoters of highly expressed genes, and that it functions to activate or to repress gene expression in vivo. Analyses of cyclin D1 transcriptional targets reveal that cyclin D1 contributes to cell proliferation by upregulating genes required for S-phase entry and progression. Hence, cyclin D1 plays a broad transcriptional regulatory function in vivo during normal mouse development.
Project description:Cyclin D1 belongs to the core cell cycle machinery1, and it is frequently overexpressed in human cancers2. The full repertoire of cyclin D1 functions in normal development and in cancer cells is currently unknown. To address this question, here we introduce a novel approach that allows one to determine the set of cyclin D1-interacting proteins (D1 “interactome”) and cyclin D1-bound genomic fragments (D1 “cistrome”) in essentially any mouse organ, at any point of development or at any stage of cancer progression. Using this approach, we detected several novel tissue-specific interactors of cyclin D1. A significant number of these partners represent proteins involved in transcription. We show, using genome-wide location analysis3, that cyclin D1 occupies promoters of a very large number of genes in the developing mouse, where it binds in close proximity to transcription start sites. Bioinformatics analyses of cyclin D1-bound genomic segments in the developing embryo revealed DNA recognition sequences for several transcription factors. By querying SAGE libraries4, promoter CpG content5 and gene expression profiles of cyclin D1-null organs, we demonstrate that cyclin D1 binds promoters of highly expressed genes, and that it functions to activate or to repress gene expression in vivo. Analyses of cyclin D1 transcriptional targets reveal that cyclin D1 contributes to cell proliferation by upregulating genes required for S-phase entry and progression. Hence, cyclin D1 plays a broad transcriptional regulatory function in vivo during normal mouse development.
Project description:The chromosomal translocation t(11;14)(q13;q32) leading to cyclin-D1 over-expression plays an essential role in the development of mantle cell lymphoma (MCL), an aggressive tumor that remains incurable with current therapies. Cyclin-D1 has been postulated as an effective therapeutic target, but its evaluation has been hampered by our incomplete understanding of its oncogenic functions and by the lack of valid MCL murine models. To address these issues, we generated a cyclin-D1-driven mouse model whereby cyclin-D1 expression can be externally regulated. These mice developed lymphomas capable of recapitulating most features of human MCL. We found that cyclin-D1 inactivation was not sufficient to induce lymphoma regression in vivo. However, using a combination of in vitro and in vivo assays, we identified a novel pro-survival cyclin-D1 function in MCL cells. Specifically, we demonstrate that cyclin-D1 sequestrates the pro-apoptotic protein BAX, thereby favoring BCL2 anti-apoptotic function. Accordingly, cyclin-D1 inhibition sensitized the lymphoma cells to apoptosis through BAX release. Thus, genetic or pharmacologic targeting of cyclin-D1 combined with a pro-apoptotic BH3 mimetic synergistically killed murine lymphomas and human MCL cells. Our study identifies a novel role of cyclin-D1 in deregulating apoptosis and highlights the potential benefit of simultaneously targeting cyclin-D1 and survival pathways in patients with MCL.
Project description:Cyclin D1 belongs to the core cell cycle machinery1, and it is frequently overexpressed in human cancers2. The full repertoire of cyclin D1 functions in normal development and in cancer cells is currently unknown. To address this question, here we introduce a novel approach that allows one to determine the set of cyclin D1-interacting proteins (D1 âinteractomeâ) and cyclin D1-bound genomic fragments (D1 âcistromeâ) in essentially any mouse organ, at any point of development or at any stage of cancer progression. Using this approach, we detected several novel tissue-specific interactors of cyclin D1. A significant number of these partners represent proteins involved in transcription. We show, using genome-wide location analysis3, that cyclin D1 occupies promoters of a very large number of genes in the developing mouse, where it binds in close proximity to transcription start sites. Bioinformatics analyses of cyclin D1-bound genomic segments in the developing embryo revealed DNA recognition sequences for several transcription factors. By querying SAGE libraries4, promoter CpG content5 and gene expression profiles of cyclin D1-null organs, we demonstrate that cyclin D1 binds promoters of highly expressed genes, and that it functions to activate or to repress gene expression in vivo. Analyses of cyclin D1 transcriptional targets reveal that cyclin D1 contributes to cell proliferation by upregulating genes required for S-phase entry and progression. Hence, cyclin D1 plays a broad transcriptional regulatory function in vivo during normal mouse development. We wished to determine whether cyclin D1 functioned to positively or negatively regulate transcription of the target genes (identified by chip-on-chip) in vivo. To address this question, we asked how expression of cyclin D1-bound genes changes when cyclin D1 has been knocked-out. We dissected retinas from eyes of cyclin D1-/- or wild-type neonates, isolated RNA and hybridized it onto Affymetrix expression arrays.