Doxycycline-inducible expression of SPARC/Osteonectin/BM40 in MDA-MB-231 human breast cancer cells results in growth inhibition

Dhanesuan, N., Sharp, J.A., Blick, T., Price, J.T., & Thompson, E.W. (2002) Doxycycline-inducible expression of SPARC/Osteonectin/BM40 in MDA-MB-231 human breast cancer cells results in growth inhibition. Breast Cancer Research and Treatment, 75(1), pp. 73-85.

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SPARC (secreted protein acidic and rich in cysteine)/BM40/Osteonectin is a matricellular protein with multiple effects on cell behaviour. In vitro, its major known functions are anti-adhesive and anti-proliferative, and it is associated with tissue remodelling and cancer in vivo. SPARC is overexpressed in many cancers, including breast cancer, and the effects of SPARC seem to be cell type-specific. To study the effects of SPARC on breast cancer, we transfected SPARC into the MDA-MB-231 BAG, human breast cancer cell line using the Tet-On inducible system. By western analysis, we found low background levels in the MDA-MB-231 BAG and clone X parental cells, and prominent induction of SPARC protein expression after doxycycline treatment in SPARC transfected clones X5, X21, X24 and X75. Induction of SPARC expression did not affect cell morphology or adhesiveness to collagens type I and IV, but it slowed the rate of proliferation in adherent cultures. Cell cycle analysis showed that SPARC slowed the progression to S phase. Doxycycline induction of SPARC also slowed the rate of monolayer wound closure in the cultured wound healing assay. Thymidine inhibition of proliferation abrogated this effect, confirming that it was due to anti-proliferation rather than inhibition of migration. Consistent with this, we were unable to detect any differences in migration and Matrigel outgrowth analysis of doxycycline-stimulated cells. We conclude that SPARC is inhibitory to human breast cancer cell proliferation, and does not stimulate migration, in contrast to its stimulatory effects reported for melanoma (proliferation and migration) and glioma (migration) cells. Similar growth repression by SPARC has been reported for ovarian cancer cells, and this may be a common feature among carcinomas.

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ID Code: 71743
Item Type: Journal Article
Refereed: Yes
Additional Information: Cited By (since 1996):54
Export Date: 6 May 2014
Source: Scopus
Additional URLs:
Keywords: Adhesion, Doxycycline, Proliferation SPARC, Tet-On
DOI: 10.1023/A:1016536725958
ISSN: 1573-7217
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Deposited On: 16 May 2014 04:21
Last Modified: 16 May 2014 04:21

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