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Production and characterization of tumor-degenerating factor
Abstract:
Degenerative changes of human tumor cells or continuous cell lines occur when they are cocultured with human embryonic fibroblasts. The present study confirmed that the degenerative changes of the target cells were due to a factor secreted from the human fibroblast culture, because the culture supernatant of human fibroblast caused the same degenerative changes as those induced by the coculture. This factor was termed "tumor-degenerating factor" (TDF). TDF was produced in the fibroblast culture as early as the 1st day and increased gradually up to the 8th day. TDF induced the degenerative changes in human KB cells, HeLa cells, FL cells, and PLC/PRF/5 cells but not in human WiDr cells or in fibroblasts. Also, it did not induce the degenerative changes in various murine cells, bovine cells, rabbit cells, or monkey cells, suggesting that TDF has species specificity. Furthermore, human leukocyte interferon enhanced the activity of TDF. TDF with the specific activity of 2.9 U/mg protein was purified by several chromatographies. At a final recovery rate of 14.6%, the specific activity was increased to 9,010 U/mg protein. Its molecular weight was estimated about 26,500-30,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. TDF was relatively stable to heat treatment.
Insights
Human embryonic fibroblasts secrete a tumor-degenerating factor (TDF) that causes degenerative changes in human tumor cells. This factor exhibits species specificity and is enhanced by human leukocyte interferon.
Area of Science:
- Cell Biology
- Biochemistry
- Oncology
Background:
- Coculturing human tumor cells with human embryonic fibroblasts leads to degenerative changes in the tumor cells.
- These degenerative changes are attributed to a soluble factor released by the fibroblasts.
Purpose of the Study:
- To identify and characterize the factor responsible for tumor cell degeneration.
- To investigate the properties and specificity of this tumor-degenerating factor (TDF).
Main Methods:
- Analysis of fibroblast culture supernatant for tumor cell-degrading activity.
- Testing TDF's effect on various human and non-human cell lines.
- Purification of TDF using chromatography and molecular weight estimation via SDS-PAGE.
- Assessing TDF stability and enhancement by human leukocyte interferon.
Main Results:
- A tumor-degenerating factor (TDF) was identified in human fibroblast culture supernatant.
- TDF induced degenerative changes in several human tumor cell lines (KB, HeLa, FL, PLC/PRF/5) but not in WiDr cells or fibroblasts.
- TDF demonstrated species specificity, affecting only human cells.
- Human leukocyte interferon enhanced TDF activity.
- Purified TDF had a specific activity of 9,010 U/mg protein and a molecular weight of approximately 26,500-30,000 Da.
- TDF was found to be relatively heat-stable.
Conclusions:
- Human embryonic fibroblasts produce a heat-stable, species-specific tumor-degenerating factor (TDF).
- TDF holds potential for cancer research and therapeutic development.
- Interferon's ability to enhance TDF activity warrants further investigation.