Further, various TGF target genes were observed to be downregulated such as that promote tumor cell metastases [26]. counter stain nucleus.(7.71 MB TIF) pone.0000660.s004.tif (7.3M) GUID:?8274FC2A-B74C-4210-A43B-D876419CDD8F Figure S5: Wound healing assay in control MCF7 (A) and PC3 cells (B) or in cells transiently transfected with SMAR1. Images represent control cells and SMAR1 siRNA transfected cells at 0 hr and after 24 hr of RO4927350 transfection.(7.66 MB TIF) pone.0000660.s005.tif (7.3M) GUID:?A184C805-801F-4A15-B49F-13533DCD2433 Table S1: Percent population shift towards G1/S and G2/M phase in Doxorubicin (0.5 M) treated with and without siRNA (100 nM) compared to control untreated synchronized 293 cells.(0.03 MB DOC) pone.0000660.s006.doc (26K) GUID:?DFF4BEF6-2EA8-45F5-91EA-9F6D144EDB99 Video S1: Time lapse video showing migration of control B16F1 cells.(1.61 MB MOV) pone.0000660.s007.mov (1.5M) GUID:?3142F4B8-36E6-41BE-96D9-FC07F33B344A Video S2: Time lapse video showing migration of SMAR1 stable B16F1 cells.(1.62 MB MOV) pone.0000660.s008.mov (1.5M) GUID:?8F019871-7B5B-43C8-A40B-B88C1D6ABAF5 Video S3: Time lapse video showing migration of SMAR1 siRNA treated B16F1 cells.(1.60 MB MOV) pone.0000660.s009.mov (1.5M) GUID:?EE4FBDA0-0F7A-4279-82B8-DD6D112AB20A Abstract Tumor suppressor SMAR1 interacts and stabilizes p53 through phosphorylation at its serine-15 residue. We show that SMAR1 transcription is regulated by p53 through its response element present in the SMAR1 promoter. Upon Doxorubicin induced DNA damage, acetylated p53 is recruited on SMAR1 promoter that allows activation of its transcription. Once SMAR1 is induced, cell cycle arrest is observed that is correlated to increased phospho-ser-15-p53 and decreased p53 acetylation. Further we demonstrate that SMAR1 expression is drastically reduced during advancement of human breast cancer. This was correlated with defective p53 expression in breast cancer where acetylated p53 is sequestered into the heterochromatin region and become inaccessible to activate SMAR1 promoter. In a recent report we have shown that SMAR1 represses Cyclin D1 transcription through recruitment of HDAC1 dependent repressor complex at the MAR site of Cyclin D1 promoter. Here we show that downmodulation of SMAR1 in high grade breast carcinoma is correlated with upregulated Cyclin D1 expression. We also established that SMAR1 inhibits tumor cell migration and metastases through inhibition of TGF signaling and its downstream target genes including and various focal adhesion molecules. Thus, we report that SMAR1 plays a central role in coordinating p53 RO4927350 and TGF pathways in human breast cancer. Introduction Nuclear matrix and matrix binding proteins maintain chromatin architecture that is altered Speer3 in cancer [1]. MAR (Matrix Attachment Region) binding proteins (MARBPs) like p53, Ku, PARP, SATB1, Cux/CDP RO4927350 are involved in regulation of various physiological processes that include cell cycle progression, DNA damage-repair, apoptosis etc. [2]. Among these MARBPs, p53 is frequently mutated in more than 50% human cancer patients [3]. Some of RO4927350 these specific mutations allow p53 to bind to MAR sequences with higher affinity, distort double strand DNA and thus affect transcription [4]. DNA damage and other stress induce p53 mediated cell cycle arrest, apoptosis and cellular senescence through post-translational modification of p53 like phosphorylation, acetylation, sumoylation etc. that play role in regulating the stability and transcriptional activity of p53 [5]C[7]. Whereas N-terminal phosphorylation is important for stabilization, C-terminal acetylation regulates the DNA binding properties of p53 by interfering with its nuclear import-export, degradation and tetramerization [8]. Dual acetylation of p53 at K373/382 is required for its transactivation function and transient or prolonged acetylation decides the cell fate towards either cell cycle arrest or apoptosis [9], [10]. Other cell cycle regulatory proteins include various Cyclins and Cyclin dependent kinase (cdk) complex that are aberrantly expressed in cancer. Among all Cyclins, Cyclin D1 expression is one of the hallmarks of breast cancer progression and is considered as a positive diagnostic marker [11], [12]. Various growth factors such as IGF I, IGF II, TGF-, retinoic acid etc. induce Cyclin D1 expression [13]C[16]. Apart from these growth factors, oncogenic signals mediated by and that are involved in cellular transformation also activate Cyclin D1 [17], [13], [18], [19]. Tumor growth and its.
