Overexpression of protein kinase Cdelta enhances cisplatin-induced cytotoxicity correlated with p53 in gastric cancer cell line.
OBJECTIVE
An important issue in cancer therapy is to investigate the mechanism for cellular sensitivity to anticancer agents such as cisplatin. Cisplatin is one of the DNA-damaging agents and several factors including p53 are related to the sensitivity to cisplatin in cancer. Protein kinase C (PKC) delta is known as a positive regulator for cisplatin-induced cell death. In our present study, we examined whether overexpression of PKCdelta and p53 increases the sensitivity of the human gastric cancer cell line, MKN28, which has a mutation of p53 gene, to cisplatin.


METHODS
Cell viability and DNA content were measured in MKN28 with adenovirus-mediated expression of PKCdelta and p53 after exposure to cisplatin. In addition, the active form of caspase-3 was detected by Western blotting.


RESULTS
Overexpression of exogenous PKCdelta did not induce cell death in MKN28 but inhibited cell growth at 1 microg/ml cisplatin as compared to that by cisplatin alone. Moreover, overexpression of both wild-type p53 and exogenous PKCdelta in MKN28 increased cisplatin-induced cell death in MKN28.


CONCLUSIONS
These results suggest that PKCdelta, in cooperation with p53, possibly regulates cisplatin-induced caspase-3-mediated cell death in gastric cancer.
Iioka
Yoshihiko
Y
Third Department of Surgery, Tokyo Medical University, Tokyo, Japan.
Mishima
Kenji
K
Azuma
Nakanobu
N
Tsuchida
Akihiko
A
Takagi
Yu
Y
Aoki
Tatsuya
T
Saito
Ichiro
I
D000256:Adenoviridae / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D051745:Protein Kinase C-delta; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D000970:Antineoplastic Agents; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin