Table Of ContentArchives of Toxicology, Supplement 10
Mouse Liver Tumors
Relevance to Human Cancer Risk
Symposium of the
European Society of Toxicology
Held in Rome, February 2-5, 1986
Edited by
P. L. Chambers, D. Henschler and ROesch
With 64 Figures
Springer-Verlag Berlin Heidelberg New York
London Paris Tokyo
PInuP L. CHAMBERS
University of Dublin, Department of Pharmacology and Therapeutics,
Trinity College, Dublin 2, Ireland
DIETRICH RENSCHLER
Institut fiir Toxikologie und Pharmakologie der Universitat Wiirzburg,
Versbacher LandstraBe 9,8700 Wiirzburg
FRANZ OESCH
Institut fUr Toxikologie der Universitat Mainz,
Obere Zahlbacher StraBe 67,6500 Mainz
ISBN-13 :978-3-540-17124-9 e-ISBN-13 :978-3-642-71617-1
DOl: 10.1007/978-3-642-71617-1
Library of Congress Cataloging in Publication Data.
European Society of Toxicology. Meeting (1986: Rome, Italy) Mouse liver tumors. (Archives of toxicology.
Supplement, 10) Includes index. 1. Liver-Tumors-Animal Models-Congresses. 2. Mice-Diseases-Congresses.
I. Chambers, P. L. (philip L.), 1931. II. Henschler, Dietrich. III. Oesch, Franz, 1938. [DNLM: 1. Liver
Neoplasms-congresses. 2. Mice-congresses. 3. Neoplasms, Experimental-congresses. Wi AR49GA v. 10/
WI 735 E89m 1986]
RA1190.E8 Suppl. vol. 10 615.9s 86-26133 [RC280.L5] [616.99'436]
ISBN-13:978-3-540-17124-9 (U.S.)
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Contents
Introduction
The Mouse in Safety Evaluation
J.DOULL ......... . 3
Liver Lesions in B6C3F1 Mice: The National Toxicology Program, Experience and Position
R. R. MARONPOT, J. K. HASEMAN, G. A. BOORMAN, S. E. EUSTIs, G. N. RAo, and J. E. HUFF. 10
Biology and Functional Properties of Mouse Liver Nodules
Invasiveness, Metastasis, and Transplantability of Mouse Liver Nodules
S. D. VESSEUNOVITCH . . . . . . . . . . . . . . . . . . . . . . . 29
Xenobiotic-Induced Peroxisome Proliferation: Role of Tissue Specificity and Species Differences
in Response in the Evaluation of the Implications for Human Health
J. K. REDDY and M. S. RAo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
The Role of Necrosis in Hepatocellular Proliferation and Liver Tumors
P. M. NEWBERNE, P. PuNYARIT, J. DE CAMARGO, and V. SUPHAKARN . . 54
Biological Markers Characterizing the Development of Preneoplastic and Neoplastic Lesions
in Rodent Liver
D. G. BEER and H. C. PrroT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Relationship Among the Histochemically Distinguishable Early Lesions in Multistep-Multistage
Hepatocarcinogenesis
E. SCHERER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
The Histopathology and Biochemistry of Phenobarbitone-Induced Liver Nodules in C3H Mice
S. D. GANGOLU, B. G. LAKE, and J. G. EVANS. . . . . . . . . . . . . . . . . . . . . . 95
Molecular Basis
Species Differences in Enzymes Controlling Reactive Epoxides
H. R. GLATT and F. OESCH. . . . . . . . . . . . . . . . .. 111
Species Differences of Glucuronidation and Sulfation in Relation to Hepatocarcinogenesis
K. W. BOCK and G. SCHIRMER . . . . . . . . . . . . . . . . . . . . . . . . .. 125
Glutathione S-Transferase Subunits in the Mouse and Their Catalytic Activities Towards Reactive
Electrophiles
J. D. HAYES, R. E. COULTHWAITE, P. K. STOCKMAN, A. J. HuSSEY, T. J. MANTLE, and C. R. WOLF 136
Species Differences in Biotransformation of and Peroxisome Proliferation due to Trichloro
ethylene
C. R. ELCOMBE, I. S. PRATT, and T. GREEN ....................... 147
The Distribution of Carcinogen Metabolizing Enzymes in the Mouse Liver: Comparison of
Parenchymal and Non-Parenchymal Cell Populations
P. STEINBERG, W. M. LAFRANCONI, and F. OESCH . . . . . . . . . . . . . . . . .. 148
Investigations on the Mechanism of Liver Tumour Induction by Peroxisome Proliferators
P. BENTLEY, F. BIERI, F. MITCHELL, F. WAECHTER, and W. STAUBLI ............ 157
DNA Damage and Repair in Mouse Liver
J. A. SWENBERG and T. R. FENNELL . . . . ................ 162
Individual Differences in DNA Repair Capacities in Man
F. OESCH, W. AULMANN, K. L. PLATT, and G. DOERJER. . ............... 172
Variables Influencing DNA-Binding in Mouse Liver
H.-G. NEUMANN . . . • . . • • . . • • • . • . 180
Pharmacokinetic Factors and Their Implication in the Induction of Mouse Liver Tumors by
Halogenated Hydrocarbons
H. M. BOLT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Comparative Study on the Indirect Methylation of Liver DNA Guanine by the 1-Carbon
Pool in Hepatotoxicity
R. C. SHANK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
Activation of a Cellular Proto-Oncogene in Spontaneous Liver Tumor Tissue of B6C3F1 Mouse
T. R. Fox, A. M. SCHUMANN, and P. G. WATANABE . . . . . . . . . . . . . . . . . . . 217
Modifying Factors
Nutritional and Dietary Influences on Liver Tumorigenesis in Mice and Rats
A. E. ROGERS, H. M. NIELDs, and P. M. NEWBERNE . . . . . . . . . . . . . . . . . . . 231
Anatomy, Function and Aging in the Mouse Liver
C. F. HOLLANDER, C. F. A. VAN BEZOOIJEN, and H. A. SOLLEVELD . . . . . . . . . . . . . 244
Sex Hormones and Neoplasia: Liver Tumors in Rodents
M. METZLER and G. H. DEGEN . . . . . . . . . . . . .......... 251
Sex Hormones and Neoplasia: Genotoxic Effects in Short Term Assays
G. H. DEGEN and M. METZLER ................. . ......... 264
Mouse and Human Liver Tumors
Pathogenesis of Experimental Liver Cancer Comparison with Humans
E. FARBER ..................................... 281
Author Index 289
Subject Index 291
Introduction
Mouse Liver Tumors
Arch. Toxico!. Supp!. 10, 3-9 (1987)
© Springer-Verlag 1987
The Mouse in Safety Evaluation
J. Doull
Department of Pharmacology, Toxicology and Therapeutics, University of Kansas, Medical Center,
Kansas City, Kansas, 66103 USA
Abstract. Several recent publications have reviewed the history, rationale and
experience concerning the use of mice as a test species in oncogenicity bioassay
programs. Conclusions from three of these publications will be discussed: The
Report of the International Expert Advisory Committee on the Relevance of
Mouse Liver Hepatoma to Human Carcinogenic Risk (from the Nutrition
Foundation), the Report of the NTP Ad Hoc Panel on Chemical Carcinogen
esis Testing and Evaluation (from the Board of Scientific Counselors of the
National Toxicology Program), and Chemical Carcinogens: Review of the
Science and its Associated Principles (from the Office of Science and Technol
ogy Policy). Using the recommendations from these and other groups regard
ing modification of the current testing protocols and alternative approaches
to evaluating the adverse health effects oflong-term, low-level exposure to en
vironmental chemicals, an effort will be made to predict some future develop
ments in this area of toxicology.
Key words: Nutrition Foundation Expert Panel - 'Ad hoc' Panel National
Toxicology Program - Office of Science Technology Policy - Chemical carci
nogens
The entire Western world and the majority of the developing countries rely
heavily on the results of animal tests to make decisions regarding the registration
and use of drugs, pesticides and other chemicals to which human populations may
be exposed. This is a difficult and demanding responsibility and the regulatory
authorities need the advice and support of a broad segment of society, including
the scientific community and the lay public. Epidemiologic data cannot be avail
able on new substances and, even for those compounds which have been in use
for some time, the data are often imprecise and of variable utility in decision mak
ing.
Abbreviations: FDA: Food and Drug Administration. EPA: Environmental Protection Agency.
NCI: National Cancer Institute. NCTR: National Center for Toxicologic Research. NTP: National
Toxicology Program. NIEHS: National Institute of Environmental Health Science. OSHA: Occupa
tional Safety and Health Administration.
4 J. Doul1
The use of experimental animals in risk evaluation has been widely accepted
since, when properly used, they serve as satisfactory surrogates for humans. The
appropriate management of risk, however, depends on the critical assessment and
a balanced interpretation of the available data. Some of the data obtained from
mice in recent years have been questioned by the regulatory authorities, industry
and the scientific community. Much of the controversy has arisen around the
mouse liver nodule which is sometimes the sole indicator of a compound's poten
tial risk. With the increasing concern among those responsible for using risk as
sessment and management in protecting public health and a desire to explore in
depth and sort out what is fact and what is fiction about the biology of mouse
liver, this conference included: the historical development of animal bioassays in
cluding the mouse, particularly the B6C3F1 hybrid, the biology and function of
mouse liver nodules, factors that influence proliferative lesions, the enzymatic
control of reactive control of reactive chemical species, oncogenes and DNA re
pair. The participants included scientists from government, industry and aca
demia who represent a cross-section of the best expertise available in Europe and
America and are working at the cutting edge of research in hepatology.
The first goal of this conference was to enable these experts to interact both
formally and informally in an atmosphere conducive to a frank and perceptive
exchange of ideas and data. This exchange between those who are involved in
morphologic and histochemical investigations and the biochemists and molecular
biologists should further the understanding about the nature and mechanisms of
hepatocellular cancer. The second goal of this conference was to focus on the
question of whether the mouse liver is or is not a useful tool for assessing risk and
protecting the public's health without penalizing industry incorrectly in its effort
to continue to provide useful drugs and chemicals essential to the continued de
velopment and maintenance of a high standard of living. Those who must regu
late the drugs and chemicals to which man is or may be exposed must do so in
the absence of complete information; hopefully, the results of this conference
should make a job a bit easier and more acceptable to all.
There have been several groups in the past few years that have examined the
validity of predicting human cancer risks on the basis of rodent studies, and in
most cases these groups have also considered the more specific issue of the mouse
liver tumor. In organizing this conference on the relevance of mouse liver tumors
to human risk, it was felt that a review of the recommendations and conclusions
of some of these groups would provide useful background information and a fo
cus for some of the problems areas.
During the summer of 1982, the Nutrition Foundation established an Interna
tional Expert Advisory Committee on the Relevance of Mouse Liver Hepatoma
to Human Carcinogenic Risk. The members of this committee included Dr.
Bridges from England, Dr. Munro from Canada, Dr. Kroes from The Nether
lands and Drs. Darby, Doull, Golberg, Paynter, Pitot, Squire and Williams from
the U.S. The report of this committee, which was issued in the fall of 1983, con
sisted of major sections describing the pathology of mouse liver neoplasms, the
factors which modify the spontaneous and induced incidence of this lesion, the
natural course of mouse hepatoma and a final section dealing with the regulatory
aspects and interpretation of mouse hepatoma data. Included in the report are
The Mouse in Safety Evaluation 5
discussions of the nomenclature, morphology and both the functional and bio
logic characteristics of mouse hepatomas. Data is also presented on the incidence
of mouse hepatoma in different strains, the interlaboratory variation in incidence
within a single strain (B6C3Fl) and a summary ofNCI and NTP data comparing
chemical induction of liver and other tumors in rats and mice.
With regard to the nomenclature of mouse liver hepatomas, the report distin
guishes between nodular hyperplasia, adenoma and hepatocellular carcinoma in
terms of morphology and both functional and biological characteristics. Al
though there are conflicting results and discordant conclusions in this area, the
committee felt that there is now fairly general agreement that some types of
mouse liver neoplasms are capable of metastasizing either spontaneously or ar
tificially by transplantation. The committee concluded that some nodular mouse
liver lesions with the morphological abnormalities associated with malignancy in
other organ systems also display functional and biological abnormalities indica
tive of a malignant character and that such lesions are appropriately diagnosed
as hepatocellular carcinomas. Other well-differentiated nodular lesions have been
shown to possess functional abnormalities and in some cases to be progressively
growing and transplantable. The bulk of evidence suggests that these lesions are
neoplasms, albeit less aggressive than the type that is morphologically more ab
normal, and the committee agreed that these lesions may be benign neoplasms
and that the designation of adenoma is appropriate. Whether or not the type A
hepatoma or adenoma is a precursor of hepatocellular carcinoma is less clear. The
report points out, however, that although the neoplastic nature of such nodules
may be equivocal, they are indicative of a neoplastic process in the liver. The com
mittee recognized that most of the current problems associated with the diagno
sis, interpretation and biological significance of mouse liver neoplasms stem from
the fact that the various steps in the carcinogenic process are not well understood.
However, they point out that since some of the newer approaches, such as the use
of recombinant DNA techniques, appear to be feasible for mouse hepatoma, it
is likely that many of these problems could be clarified in a reasonably short time
if such approaches were to be vigorously pursued.
During the initial meetings of this committee, a series of questions were devel
oped which it was felt should be addressed by toxicologists and those who use the
results of toxicologic bioassays. Several of these questions, such as those involv
ing the resolution of conflicting data sets and the appropriate use of negative
bioassay data, were beyond the scope of the charge to this committee, but two
of these questions were addressed. The first of these is "How reliable are rodent
tests in predicting carcinogenicity in man?", and the second is "What is the basis
for the use of sensitive strains exhibiting high natural incidence of liver and/or
lung tumors, for example, in carcinogenic bioassays?" In responding to the first
question, the committee pointed out that the concept of dose-response and the
argument that tests in animals, when properly qualified, are applicable to man
constitute well-established principles not only of toxicology but of biology in gen
eral. Another approach to this question is to ask "How reliable are mouse bioas
say tests in predicting carcinogenicity in the rat?". Using NCI data on 85 chemi
cals which produced neoplasia in at least 1 tissue of rats and/or mice, the commit
tee noted that the B6C3Fl mouse exhibited only liver tumors in 37 of these bioas-
