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

The Solt-Farberresistanthepatocyte(RH) and Reddy(dietaryperoxisome proliferato!-) hepatocarcinogenesisprotocolswere utilized to induceboth preneoplasticand neoplasticnodules in male F-344 rats. Totalcellularpolypeptidesfromnormalliver,ciprofibrate(CP)-induced and RH nodules were analyzedfor both qualitativeand quantitative changesusingcomputer-assisted, high resolutiontwo-dimensional pol)acrylamidegel electrophoresis.Approximately800-1000 cytosolicand 1000-1200 pariculatepolypeptideswerereadilyseparatedanddetected usingan ultrasensitivesilverstain.The two-dimensional polyacrylamide gel electrophoresispatternswereverysimilarforeachtissuewithrespect to both the numberof polypeptidesdetectedand the overallpatterns. Three cytosolic poiypeptides,E, 6.90/47; F, 6.90/46; and G, 6.50/28 (designatedpI/Af,x 10~3),andtwo particularpolypeptides,B, 5.90/43; and D, 5.70/21; were detected in CP nodulesbut not in normalliver. PolypeptidesB andD werealso detectedin RH nodules.No qualitative polypeptidedifferencesweredetectedamongthe individual preneoplastic or individualneoplasticCP nodulesor betweenpreneoplasticand neo plasticCP nodules.Numerousquantitativechangesin bothknownmark ers forhepatocarcinogenesis andinas yet unidentifiedpolypeptideswere noted. In RH nodules the Ya subunitof glutathione-5-transferaseB (GST-B) and the Yb subunitof GST-A were increased2-4-fold as comparedto normalliveror in replicatingliverfollowinga 70%partial hepatectomy, whilein CP nodulesthe Yb subunitwas unalteredandthe Ya subunitincreased4-foldas comparedto normal.The Yp subunitsof GST-P wereincreasedfromalmostnondetectablelevels in normalliver to one of the most abundantcytosolicpolypeptidesin RH nodules.In contrast,the Yp subunitswere not detectedin any of the CP nodules either on the two-dimensional polyacrylamidegel electrophoresisgels themselvesor followingWesterntransferandimmunoblot analysiswith antibodyagainstGST-P. Two additionalpolypeptidespots, whichmay representYcchargeshiftvariants,appearedatthesamemolecularweight as the constitutivelyexpressed Yc subunitof GST-B but shifted one chargeuniteachtowardthe acidicregionin CP nodules.DT-diaphorase whichwasincreased2-3-fold inRH noduleswasunalteredinCPnodules. In additionto these changesin knownmarkers,34 (22 cytosolicand 12 particular)polypeptidesweresignificantlyincreasedwhile27 (12 cyto solic and15 part¡culate) polypeptidesweredecreasedduring< I'-induced hepatocarcinogenesis. Inall casesthemagnitudeanddirectionof changes werethesameinbothlate preneoplasticandneoplasticnodulesgenerated by CP administrationwith the exceptionof six cytosolicpolypeptides. Polypeptides622, 629, and721 wereincreasedin preneoplasticnodules andwereincreasedto a greaterextentin neoplasticnodules.Conversely, polypeptides557, 876, and887 wereprogressivelydecreasedduringthe transitionfrom preneoplasticto neoplasticlesions in CP nodules.Of thesequantitativechangesassociatedwithCP-inducedhepatocarcinogen esis threecytosolicandeight particularpolypeptideswerecoordinately Received 10/31/86; revised 1/23/87; accepted 3/4/87. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1A 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 andCA-36130[M.S. R.). 2To whom requests for reprints should be addressed, at National Cancer Institute, Building 37, Room 3C28, Bethesda, MD 20892. modulatedin transformations producedeitherby CP or RH regimensas comparedto normalliver.