2001 Fiscal Year Final Research Report Summary
Intracellular signal pathway of heat-induced apoptosis in human lung cancer cell lines
| Project/Area Number |
12671334
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Thoracic surgery
|
|---|
| Research Institution | Osaka Medical College |
|---|
Principal Investigator |
OTSUKI Yoshinori Osaka Medical College, Faculty of Medicine Professor, 医学部, 教授 (50140166)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TOKITSU Kousuke Osaka Medical College, Faculty of Medicine Assistant, 医学部, 助手 (60257855)
HASHIMOTO Takahiko Osaka Medical College, Faculty of Medicine Assistant, 医学部, 助手 (90340570)
SHIBATA Masa-aki Osaka Medical College, Faculty of Medicine Associate Professor, 医学部, 助教授 (10319543)
|
|---|
| Project Period (FY) |
2000 – 2001
|
| Keywords | Apoptosis / heat-shock / intracellular Ca^<2+> concentrations / human lung cancer cells / p53 / caspase family / Intracellular Ca^<2+> chelator / Ca^<2+>-ATPase inhibitor |
|---|
| Research Abstract |
This study was designed to detect heat-induced apoptosis in non-small human lung cancer cells with two different histological types and to elucidate its signaling. We analyzed the chronological changes in intracellular Ca^<2+> concentrations ([Ca^<2+>]_i) during heat-induced apoptosis in human lung cancer cell lines LK-2 (squamous cell carcinoma) and LU65A Gage cell carcinoma). In LK-2 cells, increased [Ca^<2+>]_i levels were maintained at levels between 250-350 nM 9 h after heat-shock. Treatment with BAPTA, an intracellular Ca^<2+> chelator, prior to heat-shock decreased the fequency of heat-induced apoptosis in LK-2, while thapsigargin, a selective endoplasmic reticulum Ca^-ATPase inhibitor did not change the number of apoptotic cells, regardless of the presence or absence of Ca^<2+>-supplemented medium. In LU65A cells, treatment with BAPTA or thapsigargin did not alter the apoptotic rates. Western blotting demonstrated that although expression of Bax and Bcl-2 were not changed by heat-shock, P53 expession was elevated in LK-2, but not LU65A cells. Immunohistochemistry showed that p53 was localized predominantly in the cytoplasmic of LK-2 cells, suggesting that p53 protein is not functional in LK-2. Heat-shock also elevated caspases 3, 8 and 9 activity in both cell lines. We conclude that a temporal increase in [Ca^<2+>]_i is the important initiating factor in hyperthermia-induced apoptosis in LK-2 cells and that, in these two lung cancer cell lines, apoptosis may occur through 'cross-talk' between P53-independent mitochondrial and death receptor pathways.
|
