Effects of osteopontin inhibition on radiosensitivity of MDA-MB-231 breast cancer cells.
Summary of "Effects of osteopontin inhibition on radiosensitivity of MDA-MB-231 breast cancer cells."
ABSTRACT:
BACKGROUND:
Osteopontin (OPN) is a secreted glycophosphoprotein that is overexpressed in various tumors, and high levels of OPN have been associated with poor prognosis of cancer patients. In patients with head and neck cancer, high OPN plasma levels have been associated with poor prognosis following radiotherapy. Since little is known about the relationship between OPN expression and radiosensitivity, we investigated the cellular and radiation induced effects of OPN siRNA in human MDA-MB-231 breast cancer cells.
METHODS:
MDA-MB-231 cells were transfected with OPN-specific siRNAs and irradiated after 24 h. To verify the OPN knockdown, we measured the OPN mRNA and protein levels using qRT-PCR and Western blot analysis. Furthermore, the functional effects of OPN siRNAs were studied by assays to assess clonogenic survival, migration and induction of apoptosis.
RESULTS:
Treatment of MDA-MB-231 cells with OPN siRNAs resulted in an 80% decrease in the OPN mRNA level and in a decrease in extracellular OPN protein level. Transfection reduced clonogenic survival to 42% (p = 0.008), decreased the migration rate to 60% (p = 0.15) and increased apoptosis from 0.3% to 1.7% (p = 0.04). Combination of OPN siRNA and irradiation at 2 Gy resulted in a further reduction of clonogenic survival to 27% (p < 0.001), decreased the migration rate to 40% (p = 0.03) and increased apoptosis to 4% (p < 0.005). Furthermore, OPN knockdown caused a weak radiosensitization with an enhancement factor of 1.5 at 6 Gy (p = 0.09) and a dose modifying factor (DMF10) of 1.1.
CONCLUSION:
Our results suggest that OPN knockdown improves radiobiological effects in MDA-MB-231 cells. Therefore, OPN seems to be an attractive target to improve the effectiveness of radiotherapy.
Affiliation
Journal Details
This article was published in the following journal.
Name: Radiation oncology (London, England)
ISSN: 1748-717X
Pages: 82
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20849637
- DOI: http://dx.doi.org/10.1186/1748-717X-5-82
Medical and Biotech [MESH] Definitions
Inflammatory Breast Neoplasms
Metastatic breast cancer characterized by EDEMA and ERYTHEMA of the affected breast due to LYMPHATIC METASTASIS and eventual obstruction of LYMPHATIC VESSELS by the cancer cells.
Carcinoma, Lobular
A infiltrating (invasive) breast cancer, relatively uncommon, accounting for only 5%-10% of breast tumors in most series. It is often an area of ill-defined thickening in the breast, in contrast to the dominant lump characteristic of ductal carcinoma. It is typically composed of small cells in a linear arrangement with a tendency to grow around ducts and lobules. There is likelihood of axillary nodal involvement with metastasis to meningeal and serosal surfaces. (DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1205)
Brca1 Protein
The phosphoprotein encoded by the BRCA1 gene (GENE, BRCA1). In normal cells the BRCA1 protein is localized in the nucleus, whereas in the majority of breast cancer cell lines and in malignant pleural effusions from breast cancer patients, it is localized mainly in the cytoplasm. (Science 1995;270(5237):713,789-91)
Mucin-1
Carbohydrate antigen elevated in patients with tumors of the breast, ovary, lung, and prostate as well as other disorders. The mucin is expressed normally by most glandular epithelia but shows particularly increased expression in the breast at lactation and in malignancy. It is thus an established serum marker for breast cancer.
Breast Neoplasms
Tumors or cancer of the human BREAST.
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