Activation of protein kinase Calpha signaling prevents cytotoxicity and mutagenicity following lead acetate in CL3 human lung cancer cells.
Protein kinase C (PKC) family of serine/threonine protein kinases is sensitive signaling transducers in response to lead acetate (Pb) that could transmit phosphorylation cascade for proliferation and de-differentiation of neural cells. However, little is known as to the impact of PKC on Pb genotoxicity. Here we investigate whether Pb activates the conventional/classical subfamily of PKC (cPKC) signaling to affect cytotoxicity and mutagenicity in CL3 human non-small-cell lung adenocarcinoma cells. Pb specifically promoted membrane localization of the alpha isoform of PKC in CL3 cells. Pb also elicited Raf-1 activation as measured by the induction of phospho-Raf-1S338 and the dissociation from the Raf-1 kinase inhibitor protein. Inhibition of cPKC activity using Gö6976 or depletion of PKCalpha by introducing specific small interfering RNA blocked the induction of phospho-Raf-1S338, phospho-MKK1/2 and phospho-ERK1/2 in cells exposed to Pb. Intriguingly, declining PKCalpha enhanced the Pb cytotoxicity and revealed the Pb mutagenicity at the hprt gene. The results suggest that PKCalpha is obligatory for activation of the Raf-1-MKK1/2-ERK1/2 signaling module and plays a defensive role against cytotoxicity and mutagenicity following Pb exposure. Results obtained in this study also support our previous report showing that ERK1/2 activity is involved in preventing Pb genotoxicity.
Wang
Chun-Yu
CY
Molecular Carcinogenesis Laboratory, Institute of Biotechnology & Department of Life Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan.
Lin
Yun-Wei
YW
Yang
Jia-Ling
JL
D000230:Adenocarcinoma / Q000378:metabolism; D045744:Cell Line, Tumor; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000187:drug effects / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D016296:Mutagenesis / Q000187:drug effects*; D009153:Mutagens / Q000633:toxicity*; D009942:Organometallic Compounds / Q000633:toxicity*; D010766:Phosphorylation / Q000187:drug effects; D051571:Protein Kinase C-alpha / Q000187:drug effects* / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D019908:Proto-Oncogene Proteins c-raf / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction
D009153:Mutagens; D009942:Organometallic Compounds; D007041:Hypoxanthine Phosphoribosyltransferase; D019908:Proto-Oncogene Proteins c-raf; D051571:Protein Kinase C-alpha; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C008261:lead acetate