COMPARISON OF PROLIFERATING CELL NUCLEAR ANTIGEN TO TRITIATED-THYMIDINE AS A MARKER OF PROLIFERATING HEPATOCYTES IN RATS

Citation
J. Foley et al., COMPARISON OF PROLIFERATING CELL NUCLEAR ANTIGEN TO TRITIATED-THYMIDINE AS A MARKER OF PROLIFERATING HEPATOCYTES IN RATS, Environmental health perspectives, 101, 1993, pp. 199-205
Citations number
30
Categorie Soggetti
Public, Environmental & Occupation Heath","Environmental Sciences
ISSN journal
00916765
Volume
101
Year of publication
1993
Supplement
5
Pages
199 - 205
Database
ISI
SICI code
0091-6765(1993)101:<199:COPCNA>2.0.ZU;2-C
Abstract
Proliferating cell nuclear antigen (PCNA), an endogenous nuclear prote in, has recently been used to identify replicating cells. PCNA was com pared to tritiated thymidine ([H-3].TdR), a reliable and accurate exog enous labeling agent, to ascertain if PCNA gives comparable results fo r quantitative cell proliferation. Male F344 rats were treated with a single dose of 500 mg/kg 4-acetylaminofluorene (4-AAF), a known liver mitogen. Rats (n = 5) were euthanized and necropsied at 6, 12, 18, 24, 36, 48, 96, or 192 hr after treatment. Two hours before necropsy, rat s were pulse-dosed with [H-3]-TdR (2 mCi/kg body weight). Livers were sectioned, autoradiography performed, and labeling indexes (LI), a mea surement of the percentage of S-phase hepatocytes, determined. One and a half years after the completion of this study, the archival paraffi n blocks of the liver tissue were sectioned and stained for PCNA by an immunohistochemical procedure. Immunocytochemical staining patterns o f proliferating cell nuclear antigen expression permitted the recognit ion of G(1), S, G(2),escent cells. PCNA LI, generated by scoring only cells exhibiting S-phase staining patterns, was compared to the pulse [H-3]-TdR LI for each animal. Similar periportal staining patterns of S-phase nuclei were detected by both markers. The [H-3]-TdR LI and the PCNA LI exhibited a peak at 24 hr of approximately the same magnitude . However, while the [H-3]-TdR LI had returned to near baseline at the 48-hr time point, the PCNA LI remained elevated until the 96-hr time point. This sustained elevation of the PCNA index cannot be explained at this time. Examination of all other time points revealed similar S- phase LI by either method. PCNA immunostaining allowed for the estimat ion of the growth fraction. A time-dependent alteration in the hepatic growth fraction curve was a consequence of 4-AAF treatment.