1999 Fiscal Year Final Research Report Summary
Apoptosis activated in fibrosarcoma growth
| Project/Area Number |
09671471
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Orthopaedic surgery
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| Research Institution | Gunma University |
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Principal Investigator |
WATANABE Hideomi Gunma Univ., Orthopedics, Lecturer, 医学部, 講師 (40231724)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAGISHI Kenji Gunma Univ., Orthopedics, Professor, 医学部, 教授 (70154763)
SHINOZAKI Tetsuya Gunma Univ., Orthopedics, Assistant, 医学部, 助手 (90251115)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Apoptosis / Fibrosarcoma / Cell cycle |
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| Research Abstract |
A protein-independent fibrosarcoma, Gc-4 PF, grows exponentially in a protein-free medium. The doubling time was similar to that of the serum-dependent parental clone, Gc-4 SD cultivated in the presence of fetal calf serum. The protein-free cultivation of Gc-4 PF cells concomitantly activates apoptotic phenotypes (one third total cell population), including typical morphology, high uptake of Hoechst 33342 dye, and cleavage of DNA to large fragments, as observed in protein-deprived Gc-4 SD cell previously. Gc-4 SD cells arrested in the GィイD20ィエD2/GィイD21ィエD2 phase in response to the protein-free condition. In contrast, Gc-4 PF cells did not reach GィイD20ィエD2/GィイD21ィエD2 arrest in the protein-free condition ; instead the durations of both GィイD20ィエD2/GィイD21ィエD2 and GィイD22ィエD2 phases were markedly reduced. The estimation of one cell cycle duration revealed that the cell division cycle was accelerated to 1.7 -fold. Then the growth kinetics was able to be verified quantitatively by both the cell division rate and apoptotic cell loss. Protein-free cultivation resulted in slight down-regulation of c-myc protein in both cell types, while the down-regulation of P34ィイD1cdc2ィエD1, shown clearly in Gc-4 SD cells, was avoided in Gc-4 PF cells. Interestingly, while the expression of p53 was not affected in Gc-4 SD cells in response to the protein-free condition, the suppressor gene product expression was suppressed markedly in Gc-4 PF cells. From these results Gc-4 PF cells may have acquired an ability to accelerate cell division by shortening the cell cycle duration to maintain a proper growth rate in response to intrinsic apoptosis activation with, at least in part, a suppression of p53 expression as well as an escape of down-regulation of P34ィイD1cdc2ィエD1.
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