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Modulation of apoptosis by endogenous Bcl-xL expression in MKN-45 human gastric cancer cells
S Kondo1, Y Shinomura, S Kanayama
1Second Department of Internal Medicine, Osaka University Medical School, Suita, Japan.
Abstract:
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.
Insights
Targeting Bcl-xL protein with antisense oligonucleotides or Bak overexpression enhances apoptosis in gastric cancer cells. This suggests Bcl-xL is a key regulator of cancer cell death.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Biology
Background:
- Endogenous Bcl-xL protein plays a crucial role in regulating apoptosis in malignant cells.
- Understanding Bcl-xL's function is vital for developing targeted cancer therapies.
Purpose of the Study:
- To investigate the role of endogenous Bcl-xL in modulating apoptosis of malignant cells.
- To determine if inhibiting Bcl-xL enhances cancer cell death.
Main Methods:
- Administration of bcl-x-antisense oligonucleotides to decrease Bcl-xL protein levels in MKN-45 gastric cancer cells.
- Overexpression of Bak protein, which inhibits Bcl-xL's anti-apoptotic function, via transfection.
- Flow cytometry to analyze apoptotic cell death rates.
Main Results:
- Decreased Bcl-xL protein levels led to increased apoptosis induced by serum deprivation or Fas-antibody.
- Bak-overexpressing cells exhibited enhanced apoptosis and sensitization to chemotherapy drugs (5-fluorouracil, cisplatin).
- Antisense treatment significantly increased apoptosis compared to control and sense/nonsense treatments.
Conclusions:
- Inhibiting endogenous Bcl-xL expression, through antisense oligonucleotides or Bak overexpression, sensitizes MKN-45 gastric cancer cells to apoptosis.
- Bcl-xL is an important modulator of apoptosis in cancer cells, representing a potential therapeutic target.