Modulation of apoptosis by endogenous Bcl-xL expression in MKN-45 human gastric cancer cells.
This study was designed to clarify the role of endogenous Bcl-xL expression in modulating apoptosis of malignant cells. Administration of bcl-x-antisense oligonucleotides decreased Bcl-xL protein levels in the MKN-45 human gastric cancer cell line. The decrease in Bcl-xL protein content resulted in increased cell death induced by serum deprivation or Fas-antibody administration. Flow cytometric analysis revealed that the increased apoptotic cell death was more prominent in bcl-x-antisense-treated cells as compared to control cells, bcl-x-sense-treated cells, or bcl-x-nonsense-treated cells. To inhibit the effect of intrinsic Bcl-xL protein, we overexpressed Bak, which binds Bcl-xL and inhibits the anti-apoptotic effect of Bcl-xL, by transfection into MKN-45 cells. Bak-overexpressing cells showed increased apoptotic cell death induced by Fas-antibody when compared to parent cells and MKN-neo-transfected cells. Bak-overexpressing cells also showed greater sensitization to 5-fluorouracil and cisplatin than parent cells and MKN-neo-transfected cells. In conclusion, we demonstrated that administration of bcl-x-antisense oligonucleotides or overexpression of Bak protein induces sensitization to apoptosis in MKN-45 gastric cancer cells, suggesting that endogenous Bcl-xL expression in cancer cells is an important modulator of apoptosis.
Kondo
S
S
Second Department of Internal Medicine, Osaka University Medical School, Suita, Japan.
Shinomura
Y
Y
Kanayama
S
S
Higashimoto
Y
Y
Kiyohara
T
T
Zushi
S
S
Kitamura
S
S
Ueyama
H
H
Matsuzawa
Y
Y
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics*; D002945:Cisplatin / Q000494:pharmacology; D016895:Culture Media, Serum-Free; D005472:Fluorouracil / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D009363:Neoplasm Proteins / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000502:physiology; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein; D019014:fas Receptor / Q000276:immunology / Q000502:physiology
D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; C494772:BAK1 protein, human; C494811:BCL2L1 protein, human; D016895:Culture Media, Serum-Free; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein; D019014:fas Receptor; D002945:Cisplatin; D005472:Fluorouracil