This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wirth, P. J. Articles by Evarts, R. P. Search for Related Content PubMed PubMed Citation Articles by Wirth, P. J. Articles by Evarts, R. P.

Coordinate Polypeptide Expression during Hepatocarcinogenesis in Male F-344 Rats: Comparison of the Solt-Farber and Reddy Models¹

Laboratory of Experimental Carcinogenesis, National Cancer Institute, Bethesda, Maryland 20892 [P. J. W., R. P. E.]; and Department of Pathology, Northwestern University Medical School, Chicago, Illinois 60611 [M. S. R.]

The Solt-Farber resistant hepatocyte (RH) and Reddy (dietary peroxisome proliferator) hepatocarcinogenesis protocols were utilized to induce both preneoplastic and neoplastic nodules in male F-344 rats. Total cellular polypeptides from normal liver, ciprofibrate (CP)-induced and RH nodules were analyzed for both qualitative and quantitative changes using computer-assisted, high resolution two-dimensional polyacrylamide gel electrophoresis. Approximately 800–1000 cytosolic and 1000–1200 particulate polypeptides were readily separated and detected using an ultrasensitive silver stain. The two-dimensional polyacrylamide gel electrophoresis patterns were very similar for each tissue with respect to both the number of polypeptides detected and the overall patterns. Three cytosolic polypeptides, E, 6.90/47; F, 6.90/46; and G, 6.50/28 (designated pI/M_r x 10^-3), and two particulate polypeptides, B, 5.90/43; and D, 5.70/21; were detected in CP nodules but not in normal liver. Polypeptides B and D were also detected in RH nodules. No qualitative polypeptide differences were detected among the individual preneoplastic or individual neoplastic CP nodules or between preneoplastic and neoplastic CP nodules. Numerous quantitative changes in both known markers for hepatocarcinogenesis and in as yet unidentified polypeptides were noted. In RH nodules the Ya subunit of glutathione-S-transferase B (GST-B) and the Yb subunit of GST-A were increased 2-4-fold as compared to normal liver or in replicating liver following a 70% partial hepatectomy, while in CP nodules the Yb subunit was unaltered and the Ya subunit increased 4-fold as compared to normal. The Yp subunits of GST-P were increased from almost nondetectable levels in normal liver to one of the most abundant cytosolic polypeptides in RH nodules. In contrast, the Yp subunits were not detected in any of the CP nodules either on the two-dimensional polyacrylamide gel electrophoresis gels themselves or following Western transfer and immunoblot analysis with antibody against GST-P. Two additional polypeptide spots, which may represent Yc charge shift variants, appeared at the same molecular weight as the constitutively expressed Yc subunit of GST-B but shifted one charge unit each toward the acidic region in CP nodules. DT-diaphorase which was increased 2-3-fold in RH nodules was unaltered in CP nodules. In addition to these changes in known markers, 34 (22 cytosolic and 12 particulate) polypeptides were significantly increased while 27 (12 cytosolic and 15 particulate) polypeptides were decreased during CP-induced hepatocarcinogenesis. In all cases the magnitude and direction of changes were the same in both late preneoplastic and neoplastic nodules generated by CP administration with the exception of six cytosolic polypeptides. Polypeptides 622, 629, and 721 were increased in preneoplastic nodules and were increased to a greater extent in neoplastic nodules. Conversely, polypeptides 557, 876, and 887 were progressively decreased during the transition from preneoplastic to neoplastic lesions in CP nodules. Of these quantitative changes associated with CP-induced hepatocarcinogenesis three cytosolic and eight particulate polypeptides were coordinately modulated in transformations produced either by CP or RH regimens as compared to normal liver.

¹ A preliminary report of this work has been presented at the 76th Annual Meeting of the American Association for Cancer Research, Los Angeles, CA, May 7–10, 1986 (35). This work was supported in part by NIH grants GM-23750 and CA-36130 [M. S. R.].

² To whom requests for reprints should be addressed, at National Cancer Institute, Building 37, Room 3C28, Bethesda, MD 20892.

Received 10/31/86. Revised 1/23/87. Accepted 3/ 4/87.