In the course of a project aimed to clarify the molecular mechanisms by which phorbol 12-myristate 13-acetate (PMA)-activated forms of protein kinase C (PKC) promote growth arrest in an MCF-7 cell line, we found that the PKCδ inhibitor Rottlerin was able by itself to block cell proliferation. In the current study, we investigated further the antiproliferative response to Rottlerin. Western blotting analysis of cytoplasmic/nuclear extracts showed that the drug did not prevent either extracellular signal-regulated kinase (ERK) activation by PMA or Akt phosphorylation, but did interfere with the NFκB activation process (both basal and PMA-stimulated), by lowering the levels of phospho-IκBα and preventing p65 nuclear migration. The growth arrest evoked by Rottlerin was not mediated by cell-cycle inhibitors p21 and p27 but was accompanied by a dramatic fall in the cyclin-D1 protein, the levels of which were not altered by the pan-PKC inhibitor GF 109203X, thus excluding a PKC-mediated mechanism in the Rottlerin effect. The parallel drop in cyclin-D1 mRNA suggested a down-regulation of the gene caused by the inhibition of nuclear factor-kappa B (NFκB), which occurs via a PKC-, Akt-, ERK- and mitochondrial uncoupling-independent mechanism. We provide preliminary evidence that the interference on the NFκB activation process likely occurs at the level of calcium/calmodulin-dependent protein kinase II (CaMKII), a known Rottlerin target. Indeed the drug prevented calcium-induced CaMKII autophosphorylation which, in turn, led to decreased NFκB activation.

Torricelli, C., Fortino, V., Capurro, E., Valacchi, G., Brandani, A., Muscettola, M.M., et al. (2008). Rottlerin inhibits the nuclear factor kappaB/cyclin-D1 cascade in MCF-7 breast cancer cells. LIFE SCIENCES, 82(11-12), 638-643 [10.1016/j.lfs.2007.12.020].

Rottlerin inhibits the nuclear factor kappaB/cyclin-D1 cascade in MCF-7 breast cancer cells

TORRICELLI, CLAUDIA;BRANDANI, ADRIANA;MUSCETTOLA, MARIA MICHELA;MAIOLI, EMANUELA
2008-01-01

Abstract

In the course of a project aimed to clarify the molecular mechanisms by which phorbol 12-myristate 13-acetate (PMA)-activated forms of protein kinase C (PKC) promote growth arrest in an MCF-7 cell line, we found that the PKCδ inhibitor Rottlerin was able by itself to block cell proliferation. In the current study, we investigated further the antiproliferative response to Rottlerin. Western blotting analysis of cytoplasmic/nuclear extracts showed that the drug did not prevent either extracellular signal-regulated kinase (ERK) activation by PMA or Akt phosphorylation, but did interfere with the NFκB activation process (both basal and PMA-stimulated), by lowering the levels of phospho-IκBα and preventing p65 nuclear migration. The growth arrest evoked by Rottlerin was not mediated by cell-cycle inhibitors p21 and p27 but was accompanied by a dramatic fall in the cyclin-D1 protein, the levels of which were not altered by the pan-PKC inhibitor GF 109203X, thus excluding a PKC-mediated mechanism in the Rottlerin effect. The parallel drop in cyclin-D1 mRNA suggested a down-regulation of the gene caused by the inhibition of nuclear factor-kappa B (NFκB), which occurs via a PKC-, Akt-, ERK- and mitochondrial uncoupling-independent mechanism. We provide preliminary evidence that the interference on the NFκB activation process likely occurs at the level of calcium/calmodulin-dependent protein kinase II (CaMKII), a known Rottlerin target. Indeed the drug prevented calcium-induced CaMKII autophosphorylation which, in turn, led to decreased NFκB activation.
Torricelli, C., Fortino, V., Capurro, E., Valacchi, G., Brandani, A., Muscettola, M.M., et al. (2008). Rottlerin inhibits the nuclear factor kappaB/cyclin-D1 cascade in MCF-7 breast cancer cells. LIFE SCIENCES, 82(11-12), 638-643 [10.1016/j.lfs.2007.12.020].
File in questo prodotto:
File Dimensione Formato  
rottlerin 2008.pdf

non disponibili

Tipologia: PDF editoriale
Licenza: NON PUBBLICO - Accesso privato/ristretto
Dimensione 425.4 kB
Formato Adobe PDF
425.4 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/25900
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo