Amplification of the BCAS2 gene at chromosome 1p13.3-21 in human primary breast cancer.
ABSTRACT BCAS2 is a novel gene isolated from breast cancer cell line by differential display technique. Previously we reported that BCAS2 gene is localized on chromosome 1p13.3-21 and is up-regulated by gene amplification in breast cancer cell lines MCF-7 and BT-20. In this study, we investigated the amplification of the BCAS2 gene in a series of 104 gynecological primary tumors by means of Southern blot analysis. The BCAS2 gene was amplified in two of 60 primary breast cancer tissues, whereas no amplification was detected in any of endometrial (0/26) and cervical (0/18) tumor tissues. Gene amplification was also not detected in a series of pancreatic (0/9) and gastric (0/6) cancer cell lines. An enhanced green fluorescent protein assay revealed that BCAS2 protein seems to be translocated into the nucleus. Although frequent deletions of the proximal region of chromosome 1p13.3-21 have been found in primary breast cancer, our results support first evidence of amplification within this region and indicate that BCAS2 gene codes for a nuclear protein.
SourceAvailable from: Dharmendra Bhargava[Show abstract] [Hide abstract]
ABSTRACT: Background: The overexpression of oestrogen-related receptor-β (ERRβ) in breast cancer patients is correlated with improved prognosis and longer relapse-free survival, and the level of ERRβ mRNA is inversely correlated with the S-phase fraction of cells from breast cancer patients. Methods: Chromatin immunoprecipitation (ChIP) cloning of ERRβ transcriptional targets and gel supershift assays identified Breast Cancer Amplified Sequence 2 and Follistatin as two important downstream genes that help to regulate tumourigenesis. Confocal microscopy, co-immunoprecipitation (CoIP), western blotting and quantitative real-time PCR confirmed the involvement of ERRβ in oestrogen signalling. Results: Overexpressed ERRβ induced Follistatin-mediated apoptosis in breast cancer cells, and E-cadherin expression was also enhanced through upregulation of Follistatin. However, this anti-proliferative signalling function was challenged by ERRβ-mediated BCAS2 up-regulation, which inhibited Follistatin transcription through the down-regulation of β-catenin/TCF4 recruitment to the Follistatin promoter. Interestingly, ERRβ-mediated up-regulation of BCAS2 down-regulated the major G1-S transition marker Cyclin D1, despite the predictable oncogenic properties of BCAS2. Interpretation: Our study provides the first evidence that ERRβ, which is a coregulator of ER also acts as a potential tumour suppressor molecule in breast cancer. Our current report also provides novel insights into the entire cascade of ERRβ signalling events, which may lead to BCAS2-mediated blockage of the G1/S transition and inhibition of the epithelial to mesenchymal transition through Follistatin-mediated regulation of E-cadherin. Importantly, MMP7, which is a classical mediator of metastasis and E-cadherin cleavage, was also restricted as a result of ERRβ-mediated Follistatin overexpression.British Journal of Cancer 01/2014; 110(8)::2144-58. DOI:10.1038/bjc.2014.53 · 4.82 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Pso4 is an evolutionarily conserved protein that has been implicated in a variety of cellular processes including RNA splicing and resistance to agents that cause DNA inter-strand cross-links. Here we show that the hPso4 complex is required for timely progression through S phase and transition through the G2/M checkpoint, and it functions in the repair of DNA lesions that arise during replication. Notably, hPso4 depletion results in delayed resumption of DNA replication after hydroxyurea -induced stalling of replication forks, reduced repair of spontaneous and HU-induced DNA double strand breaks, and increased sensitivity to a Poly (ADP-ribose) polymerase (PARP) inhibitor. Furthermore, we show that hPso4 is involved in the repair of DSBs repair by homologous recombination probably by regulating the BRCA1 protein levels and the generation of single-strand DNA (ssDNA) at DSBs. Together, our results demonstrate that hPso4 participates in cell proliferation and the maintenance of genome stability by regulating HR. The involvement of hPso4 in the recombinational repair of DSBs provides an explanation for the sensitivity of Pso4-deficient cells to DNA inter-strand cross-links.Journal of Biological Chemistry 03/2014; 289(20). DOI:10.1074/jbc.M113.520056 · 4.60 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: The PSO4 core complex is composed of PSO4/PRP19/SNEV, CDC5L, PLRG1 and BCAS2/SPF27. Besides its well-defined functions in pre-mRNA splicing, the PSO4 complex has been recently shown to participate in the DNA damage response. However, the specific role for the PSO4 complex in the DNA damage response pathways is still not clear. Here, we show that both BCAS2 and PSO4 subunits of the PSO4 complex directly interact and co-localize with RPA. Depletion of BCAS2 or PSO4 impairs the recruitment of ATRIP to DNA damage sites and compromises CHK1 activation and RPA2 phosphorylation. Moreover, we demonstrate that both the RPA1-binding ability of BCAS2 and the E3 ligase activity of PSO4 are required for efficient accumulation of ATRIP at DNA damage sites and the subsequent CHK1 activation and RPA2 phosphorylation. Our results suggest that the PSO4 complex functionally interacts with RPA and plays an important role in the DNA damage response.Journal of Biological Chemistry 01/2014; DOI:10.1074/jbc.M113.543439 · 4.60 Impact Factor