Ets1 is an effector of protein kinase Calpha in cancer cells.
PKCalpha and Ets1 are both associated with breast cancer progression. Our previous studies suggested that these proteins are likely to functionally interact with one another. Here, we show that attenuation of endogenous PKCalpha expression (siPalpha) by RNA interference leads to reduced Ets1 protein expression in a variety of cancer cells. Pulse-chase experiments and treatment with proteasome inhibitor MG-132 revealed that siPalpha interferes with both Ets1 protein synthesis and stability. The effect of siPalpha on Ets1 expression could be partially prevented by KN-93, suggesting that calcium/calmodulin-dependent kinase II (CaMKII), a modulator of Ets1 activity, may play a role in PKCalpha-dependent Ets1 regulation. In contrast, Ets1-regulating kinases ERK1/2 were not found to be involved in this process. To assess the importance of the PKCalpha/Ets1 interaction, we compared the biological responses of MDA-MB-231 cells to PKCalpha- and Ets1-specific siRNAs (siE1). While only siPalpha induced changes in cellular morphology and anchorage-independent growth, both siRNAs similarly affected cellular responses to the antitumor drug mithramycin A and to UV light. Microarray analyses further showed that the expression of a certain set of genes was equally affected by siPalpha and siE1. The data suggest that Ets1 serves as an effector for PKCalpha to fulfil certain functions in cancer cells.
Vetter
Martina
M
Universität Halle-Wittenberg, Universitätsklinik und Poliklinik für Gynäkologie, Ernst-Grube-Str. 40, 06097 Halle (Saale), Germany.
Blumenthal
Sibylle G
SG
Lindemann
Ralph K
RK
Manns
Joachim
J
Wesselborg
Sebastian
S
Thomssen
Christoph
C
Dittmer
Jürgen
J
D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D048430:Cell Shape; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009369:Neoplasms / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D008926:Plicamycin / Q000031:analogs & derivatives* / Q000494:pharmacology; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D034622:RNA Interference; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays
C494041:ETS1 protein, human; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D014157:Transcription Factors; C066851:mithramycin A; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D008926:Plicamycin