Protein kinase C (PKC) is a family of serine-threonine kinases that regulate many cellular processes including proliferation and survival. Previous evidence has shown that PKC is involved in the control of human medullary thyroid carcinoma (MTC) proliferation and survival by modulating apoptosis, with a mechanism that implicates PKCβII isoform and translocation in different subcellular compartments. In this study, we investigated the role of PKCδ signaling in the proliferation of a human MTC cell line, the TT cells. We found that pharmacological inhibition of the PKCδ pathway with Rottlerin reduces caspase 3/7 activity. Using a shRNA vector system, which provides more than 90% gene expression inhibition, we found that cell proliferation is greater in PKCδ-defective-TT cells than in mock-transfected cells, this difference being significant after 3 days. In addition, we found that PKCδ silencing reduces STAT5(Y694-699) phosphorylation but not AKT(Ser473) and p70S6K(T389) phosphorylation, all downstream targets of PKC pathway involved in cell growth, cell cycle and proliferation. Moreover, we demonstrated that PKCδ silencing increased human VEGF secretion after 4 days. These observations indicate for the first time that PKCδ pathway plays an important role in the growth control and VEGF secretion of human MTC cells.
PKCδ plays an important in regulating human medullary thyroid carcinoma cell viability
MOLE', Daniela;GENTILIN, Erica;GAGLIANO, Teresa;TAGLIATI, Federico;AMBROSIO, Maria Rosaria;DEGLI UBERTI, Ettore;ZATELLI, Maria Chiara
2013
Abstract
Protein kinase C (PKC) is a family of serine-threonine kinases that regulate many cellular processes including proliferation and survival. Previous evidence has shown that PKC is involved in the control of human medullary thyroid carcinoma (MTC) proliferation and survival by modulating apoptosis, with a mechanism that implicates PKCβII isoform and translocation in different subcellular compartments. In this study, we investigated the role of PKCδ signaling in the proliferation of a human MTC cell line, the TT cells. We found that pharmacological inhibition of the PKCδ pathway with Rottlerin reduces caspase 3/7 activity. Using a shRNA vector system, which provides more than 90% gene expression inhibition, we found that cell proliferation is greater in PKCδ-defective-TT cells than in mock-transfected cells, this difference being significant after 3 days. In addition, we found that PKCδ silencing reduces STAT5(Y694-699) phosphorylation but not AKT(Ser473) and p70S6K(T389) phosphorylation, all downstream targets of PKC pathway involved in cell growth, cell cycle and proliferation. Moreover, we demonstrated that PKCδ silencing increased human VEGF secretion after 4 days. These observations indicate for the first time that PKCδ pathway plays an important role in the growth control and VEGF secretion of human MTC cells.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
