Visit our Expo - Redox and Inflammation signaling 2012

Session XIV : Transcriptional and translational control Poster XIV, 74
Importance of the coordinate expression of PKC" and Ets1 for breast cancer cells
Martina Vetter 1 , Dario Schunke 1 , Paul N. Span 2 , Fred Sweep 2 , Henrike Ronneburg 1 ,
H.-J. Holzhausen 3 , Angela Dittmer 1 , Christoph Thomssen 1 and Jürgen Dittmer 1
1 Clinic for Gynecology, University of Halle, Germany, 2 Department of Chemical
Endocrinology, Radboud University Nijmegen Medical Centre, Nijmegen, Germany,
3 Institute for Pathology, University of Halle, Germany
Protein kinase C" (PKC") and the transcription factor Ets1 are often associated with
advanced tumor progression. We have previously shown that PKC" is able to
phosphorylate Ets1 and to increase its transcriptional activity. By using RNA interference
we could now show that PKC" also positively influences Ets1 expression in a variety of
cancer cell lines. One major way by which PKC" regulates Ets1 expression is by
increasing Ets1 protein stability. The relationship between PKC" and Ets1 was confirmed
by the finding that, in primary breast cancers, Ets1 expression correlates with that of
PKC". In searching for similar effects of PKC" and Ets1 we found that the response of
MDA-MB-231 cells to mithramycin or UV-light were similarly affected by PKC"- and
Ets1-specific siRNAs, whereas only PKC"-specific siRNA modulated cell morphology
and anchorage-independent growth. In an effort to identify PKC" and Ets1-responsive
genes by microarray analysis we found that the RNA levels of thirty-two genes were
similarly affected by both the PKC"- and Ets1-specific siRNAs. Among those genes were
MMP1 and MMP9 known to be regulated by Ets1 as well as the Ets1 co-activators SP100
and AML-1. Another responder gene was Rho-GDI#, an inhibitor of Rho-GTPases some
of which are important regulators of cellular migration. In MDA-MB-231 cells, PKC"- or
Ets1-specific siRNA downregulated both the RNA- as well as the protein level of Rho-
GDI#. In primary breast cancer, expression of Rho-GDI#, but not of Rho-GDI" and Rho-
GDI$, correlated with the levels of PKC" and Ets1 suggesting that there is a general link
between PKC"/Ets1 and Rho-GDI# in breast cancer cells. Interestingly, expression of
Vav1, another Rho-regulating protein which cooperates with Rho-GDI# in T-cells to
activate NFAT, was found to correlate with Rho-GDI#, PKC" and Ets1 expression. The
importance of Rho-GDI# and Vav1 in breast cancer cells is currently under investigation.
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