Abstract
A factor has been isolated from weanling rat liver which stimulates in vivo hepatic DNA synthesis in a dose dependent manner when injected into 40% hepatectomized rats. The factor has been partially purified by successive steps, involving ethanol precipitation, ultrafiltration through an Amicon PM 30 membrane, and finally fast protein liquid chromatography, resulting in a 38,000-fold increase in specific activity over that in the original cytosol. The factor contains a few bands in the molecular weight range of 14,000–50,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Active fractions from fast protein liquid chromatography (F150), when injected into 40% hepatectomized rats, increased hepatic DNA synthesis 3-fold over the background stimulation due to the hepatectomy. The response was dose dependent over a range from 1.76 µg to 6.8 µg per 200-g (body weight) rat. Mitotic and labeling indexes confirmed that F150 stimulates both replicative DNA synthesis and cell proliferation. The factor is heat and neuraminidase resistant, trypsin sensitive, organ specific, but not species specific.
Footnotes
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↵1 This study was supported by a research project grant from the Veterans Administration, Project Grant AM-29961 from the NIH, Bethesda, MD, and Grant 885/02 16544 from Consiglio Nazionale delle Ricerche, Italy.
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↵2 To whom requests for reprints should be addressed, at Veterans Administration Hospital, Building 6, Circle Drive, Pittsburgh, PA 15240.
- Received November 19, 1986.
- Revision received April 1, 1987.
- Revision received July 21, 1987.
- Accepted July 31, 1987.
- ©1987 American Association for Cancer Research.
Volume 47, Issue 21
