Protein kinase Cdelta overexpression enhances radiation sensitivity via extracellular regulated protein kinase 1/2 activation, abolishing the radiation-induced G(2)-M arrest.
Protein kinase C (PKC) has been widely implicated in regulation ofcell growth/cell cycle progression and apoptosis. However,the role of PKCdelta in radiosensitivity and cell cycle regulation remains unclear. Overexpression of PKCdelta increased Ca2+-independent PKC activity without altering other PKC isoforms (PKCalpha, -beta1, -epsilon, and -zeta), and extracellular regulated protein kinase (ERK) 1/2 activity was also increased in PKCdelta-specific manner. A clonogenic survival assay showed that PKCdelta-overexpressed cells had more radiosensitivity and pronounced induction of apoptosis than control cells. Flow cytometric analysis revealed that PKCdelta made the cells escape from radiation-induced G(2)-M arrest. Moreover, p53 and p21(Waf) induction by radiation were higher in PKCdelta-overexpressed cells than control cells, and PKCdelta-mediated apoptosis was reduced, when radiation-induced ERK1/2 activity was inhibited by PD98059. Furthermore, PKCdelta antisense and rottlerin, PKC inhibitor-abrogated PKCdelta-mediated radiosensitivity and reduced ERK1/2 activity to the control vector level. These results demonstrated that PKCdelta overexpression enhanced radiation-induced apoptosis and radiosensitivity via ERK1/2 activation, thereby abolishing the radiation-induced G(2)-M arrest and finally apoptosis.
Lee
Yoon-Jin
YJ
Laboratory of Radiation Effect, Korea Cancer Center Hospital, Seoul 139-706, Korea.
Soh
Jae-Won
JW
Dean
Nicholas M
NM
Cho
Chul-Koo
CK
Kim
Tae-Hwan
TH
Lee
Su-Jae
SJ
Lee
Yun-Sil
YS
D016475:3T3 Cells; D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D016375:Antisense Elements (Genetics); D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects; D001578:Benzopyrans / Q000494:pharmacology; D003114:Colony-Forming Units Assay; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016195:G2 Phase / Q000502:physiology* / Q000528:radiation effects; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology* / Q000528:radiation effects; D010750:Phosphoproteins / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D051745:Protein Kinase C-delta; D011836:Radiation Tolerance / Q000502:physiology
D000098:Acetophenones; D016375:Antisense Elements (Genetics); D001578:Benzopyrans; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D010750:Phosphoproteins; C085746:rottlerin; C497259:Prkcd protein, mouse; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases