Adherence to osteopontin via alphavbeta3 suppresses phorbol ester-mediated apoptosis in MCF-7 breast cancer cells that overexpress protein kinase C-alpha.

  • John D Noti
  • Published 2000 in International journal of oncology

Abstract

Overexpression of protein kinase C-alpha in MCF-7 breast cancer cells (MCF-7-PKC-alpha cells) results in anchorage-independent growth and increased tumorigenicity of these cells in nude mice. MCF-7-PKC-alpha cells, unlike their parental MCF-7 cells, are sensitized to apoptosis by phorbol esters. When adhered to osteopontin, a bone matrix protein, MCF-7-PKC-alpha cells were resistant to phorbol ester mediated apoptosis. Fluorescence-activated cell sorting revealed that osteopontin receptors, alphavbeta3 and alphavbeta5, are expressed on MCF-7-PKC-alpha cells and that both are used to adhere to osteopontin. Addition of an RGD-containing peptide inhibited survival of MCF-7-PKC-alpha cells exposed to phorbol ester and adhered to osteopontin. This indicated that an integrin was involved in the cell death suppression signal. Whereas, anti-alphavbeta5 antibody did not reduce survival of MCF-7-PKC-alpha cells adhered to osteopontin, anti-alphavbeta3 antibody could efficiently block suppression of apoptosis. Phorbol ester also induced increased expression of alphavbeta3 on MCF-7-PKC-alpha cells by upregulating expression of a second species of beta3 mRNA. This study suggests that breast cancer cells that have metastasized to bone may have a survival advantage resulting from interaction of alphavbeta3 on these cells with the bone protein osteopontin.

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@article{Noti2000AdherenceTO, title={Adherence to osteopontin via alphavbeta3 suppresses phorbol ester-mediated apoptosis in MCF-7 breast cancer cells that overexpress protein kinase C-alpha.}, author={John D Noti}, journal={International journal of oncology}, year={2000}, volume={17 6}, pages={1237-43} }