We established two in vitro culture systems that have enabled us to study regulation of expression of differentiated functions in hepatocytes in vitro and to determine how transformation alters the expression of differentiated functions in hepatocytes in vitro. The two systems are (1) a long term culture system for primary hepatocytes in which the cells are maintained in a chemically-defined medium supplemented with dimethylsulfoxide and (2) a series of SV40-immortalized hepatocyte cell lines that retain the ability to express liver-specific functions at liver-like levels. During the current funding period, we have extended the system to include primary hepatocytes that synthesize DNA, spontaneously transformed SV40 hepatocyte cell lines, ras-transformed SV40 immortalized hepatocyte cell lines, tumor cell lines and two systems for studying suppression of the transformed phenotype. We have made several important findings. first, we have transformed SV40-immortalized hepatocytes with activated c-Ha ras and shown that ras-transformation caused marked changes in the morphology and growth properties of the immortal cells but did not decrease transcription of albumin or expression of several other liver-specific genes. However, the albumin enhancer was unable to function in ras-transformed hepatocytes. Differentiation at the level of albumin transcription was maintained in ras-transformed cells, but the underlying molecular mechanism driving albumin transcription was altered by transformation. Second, we determined that TGFbeta1 suppresses the transformed phenotype in ras- transformed hepatocytes by regulating alpha1beta1 integrin expression.
The specific aims of this proposal, which are logical extensions of the work ongoing in our laboratory, are (1) to continue to characterize the methods used by the hepatocytes and hepatocyte cell lines in our system to transcribe albumin; (2) to further examine suppression of the transformed phenotype by TGFbeta1 and alpha1 integrin; (3) to continue to define what viral and cellular DNA sequences can immortalize, transform, or suppress transformation of hepatocytes; to continue to determine what changes in oncogene and growth factor expression accompany transformation of hepatocytes; and (4) to determine the effect of site of inoculation (in vivo cellular environment) on growth, tumorigenicity, morphology and gene expression of transformed hepatocyte cell lines and tumor cell lines. We will continue to use in vitro hepatocyte systems to study differences in gene expression that occur during the process of transformation and to unravel the cellular and molecular mechanisms underlying these changes.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA023931-16
Application #
3166266
Study Section
Pathology B Study Section (PTHB)
Project Start
1978-09-01
Project End
1998-05-31
Budget Start
1993-08-01
Budget End
1994-05-31
Support Year
16
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Pennsylvania State University
Department
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Starkey, Jason L; Chiari, Estelle F; Isom, Harriet C (2009) Hepatitis B virus (HBV)-specific short hairpin RNA is capable of reducing the formation of HBV covalently closed circular (CCC) DNA but has no effect on established CCC DNA in vitro. J Gen Virol 90:115-26
Heipertz Jr, Richard A; Starkey, Jason L; Miller, Thomas G et al. (2009) trans-Complementation of HBV rtM204I mutant replication by HBV wild-type polymerase. Virology 388:57-67
Shan, Weiwei; Palkar, Prajakta S; Murray, Iain A et al. (2008) Ligand activation of peroxisome proliferator-activated receptor beta/delta (PPARbeta/delta) attenuates carbon tetrachloride hepatotoxicity by downregulating proinflammatory gene expression. Toxicol Sci 105:418-28
Heipertz Jr, Richard A; Miller, Thomas G; Kelley, Colleen M et al. (2007) In vitro study of the effects of precore and lamivudine-resistant mutations on hepatitis B virus replication. J Virol 81:3068-76
Bilello, John P; Cable, Edward E; Isom, Harriet C (2003) Expression of E-cadherin and other paracellular junction genes is decreased in iron-loaded hepatocytes. Am J Pathol 162:1323-38
Bilello, J P; Cable, E E; Myers, R L et al. (2003) Role of paracellular junction complexes in baculovirus-mediated gene transfer to nondividing rat hepatocytes. Gene Ther 10:733-49
Abdelhamed, Ayman M; Kelley, Colleen M; Miller, Thomas G et al. (2003) Comparison of anti-hepatitis B virus activities of lamivudine and clevudine by a quantitative assay. Antimicrob Agents Chemother 47:324-36
Iocca, Heather A; Isom, Harriet C (2003) Tumor necrosis factor-alpha acts as a complete mitogen for primary rat hepatocytes. Am J Pathol 163:465-76
Stoehr, Stephanie A; Isom, Harriet C (2003) Gap junction-mediated intercellular communication in a long-term primary mouse hepatocyte culture system. Hepatology 38:1125-35
Malecki, Elise A; Cable, Edward E; Isom, Harriet C et al. (2002) The lipophilic iron compound TMH-ferrocene [(3,5,5-trimethylhexanoyl)ferrocene] increases iron concentrations, neuronal L-ferritin, and heme oxygenase in brains of BALB/c mice. Biol Trace Elem Res 86:73-84

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