Endogenous osteonectin/SPARC/BM-40 expression inhibits MDA-MB-231 breast cancer cell metastasis.

Craniofacial Developmental Biology and Regeneration Branch and Gene Therapy and Therapeutics Branch, National Institute of Dental and Craniofacial Research, NIH, Bethesda, Maryland 20892-4370, USA.
Cancer Research (Impact Factor: 9.28). 09/2005; 65(16):7370-7. DOI: 10.1158/0008-5472.CAN-05-0807
Source: PubMed

ABSTRACT Skeletal metastases occur with high incidence in patients with breast cancer and cause long-term skeletal morbidity. Osteonectin (SPARC, BM-40) is a bone matrix factor that is an in vitro chemoattractant for breast and prostate cancer cells. Increased expression of osteonectin is found in malignant breast tumors. We infected MDA-231 breast cancer cells with an adenovirus expressing osteonectin to examine the role of osteonectin expression in breast cancer cells and its effect on metastasis, in particular to bone. Expression of osteonectin did not affect MDA-231 cell proliferation, apoptosis, migration, cell aggregation, or protease cleavage of collagen IV. However, in vitro invasion of these osteonectin-infected cells through Matrigel and colony formation on Matrigel was decreased. Interestingly, high osteonectin expression in MDA-231 cells inhibited metastasis in a dose-dependent manner to many different organs including bone. The reduction in metastasis may be due to decreased platelet-tumor cell aggregation, because exogenous osteonectin inhibited platelet aggregation in vitro and the high osteonectin expression in MDA-231 cells reduced tumor cell-induced thrombocytopenia in vivo compared with control-infected cells. These studies suggest that high endogenous expression of osteonectin in breast cancer cells may reduce metastasis via reduced invasive activity and reduced tumor cell-platelet aggregation.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The laminin-binding integrin α3β1 is highly expressed in epidermal keratinocytes where it regulates both cell-autonomous and paracrine functions that promote wound healing and skin tumorigenesis. However, roles for α3β1 in regulating gene expression programs that control the behaviors of immortalized or transformed keratinocytes remain underexplored. In the current study, we used a microarray approach to identify genes that are regulated by α3β1 in immortalized keratinocytes. α3β1-responsive genes included several that are involved in extracellular matrix proteolysis or remodeling, including fibulin-2 and SPARC. However, α3β1-dependent induction of specific target genes was influenced by the genetic lesion that triggered immortalization, as α3β1-dependent fibulin-2 expression occurred in cells immortalized by either SV40 large T antigen or p53-null mutation, while α3β1-dependent SPARC expression occurred only in the former cells. Interestingly, qPCR arrays did not reveal strong patterns of α3β1-dependent gene expression in freshly isolated primary keratinocytes, suggesting that this regulation is acquired during immortalization. p53-null keratinocytes transformed with oncogenic RasV12 retained α3β1-dependent fibulin-2 expression, and RNAi-mediated knockdown of fibulin-2 in these cells reduced invasion, although not their tumorigenic potential. These findings demonstrate a prominent role for α3β1 in immortalized/transformed keratinocytes in regulating fibulin-2 and other genes that promote matrix remodeling and invasion.Journal of Investigative Dermatology accepted article preview online, 02 April 2014; doi:10.1038/jid.2014.166.
    Journal of Investigative Dermatology 04/2014; 134(9). DOI:10.1038/jid.2014.166 · 6.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Communication between the cell and its surrounding environment, consisting of proteinaceous (non-living material) and extracellular matrix (ECM), is important for bio-physiological and chemical signaling. This signaling results in a range of cellular activities, including cell division, adhesion, differentiation, invasion, migration, and angiogenesis. The ECM non-structural secretory glycoprotein called "secreted protein, acidic and rich in cysteine (SPARC), plays a significant role in altering cancer cell activity and the tumor's microenvironment (TME). However, the role of SPARC in cancer research has been the subject of controversy. This review mainly focuses on recent advances in understanding the contradictory nature of SPARC in relation to ECM assembly, cancer cell proliferation, adhesion, migration, apoptosis and tumor growth.
    Carcinogenesis 03/2014; DOI:10.1093/carcin/bgu072 · 5.27 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In cancer cells, the epithelial-mesenchymal transition (EMT) confers the ability to invade basement membranes and metastasize to distant sites, establishing it as an appealing target for therapeutic intervention. Here, we report a novel function of the master metabolic kinase AMPK in suppressing EMT by modulating the Akt-MDM2-Foxo3 signaling axis. This mechanistic link was supported by the effects of siRNA-mediated knockdown and pharmacological activation of AMPK on epithelial and mesenchymal markers in established breast and prostate cancer cells. Exposure of cells to OSU-53, a novel allosteric AMPK activator, as well as metformin and AICAR, was sufficient to reverse their mesenchymal phenotype. These effects were abrogated by AMPK silencing. Phenotypic changes were mediated by Foxo3a activation, insofar as silencing or overexpressing Foxo3a mimicked the effects of AMPK silencing or OSU-53 treatment on EMT, respectively. Mechanistically, Foxo3a activation led to the transactivation of the E-cadherin gene and repression of genes encoding EMT-inducing transcription factors. OSU-53 activated Foxo3a through two Akt-dependent pathways, one at the level of nuclear localization by blocking Akt- and IKKβ-mediated phosphorylation, and a second at the level of protein stabilization via cytoplasmic sequestration of MDM2, an E3 ligase responsible for Foxo3a degradation. The suppressive effects of OSU-53 on EMT had therapeutic implications illustrated by its ability to block invasive phenotypes in vitro and metastatic properties in vivo. Overall, our work illuminates a mechanism of EMT regulation in cancer cells mediated by AMPK, along with preclinical evidence supporting a tractable therapeutic strategy to reverse mesenchymal phenotypes associated with invasion and metastasis.
    Cancer Research 07/2014; 74(17). DOI:10.1158/0008-5472.CAN-14-0135 · 9.28 Impact Factor

Full-text (2 Sources)

Available from
Jul 16, 2014

Similar Publications