Polycyclic Hydrocarbons and Carcinogenesis

410 Pages·1985·6.14 MB·English

by  Ronald G. Harvey (Eds.)

ACS S Y M P O S I UM SERIES 283
Polycyclic Hydrocarbons
and Carcinogenesis
Ronald G. Harvey, EDITOR
1 University of Chicago
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1 Developed from a symposium sponsored by
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American Chemical Society, Washington, D.C. 1985
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
Library of Congress Cataloging in Publication Data
Polycyclic hydrocarbons and carcinogenesis.
(ACS symposium series, ISSN 0097-6156; 283)
"Developed from a symposium sponsored by the
Division of Organic Chemistry at the 188th Meeting of
the American Chemical Society, Philadelphia,
Pennsylvania, August 26-31, 1984."
Includes bibliographies and index.
1 1. Polycyclic aromatic hydrocarbons—Physiological
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0 effect—Congresses. 2. Polycyclic aromatic
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83.f hCyodnrgorceasrsebso.n s—Congresses. 3. Carcinogenesis—
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5-0 I. Harvey, Ronald G., 1927- . II. American
8 Chemical Society. Division of Organic Chemistry.
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1 III. American Chemical Society. Meeting (188th: 1984:
k- Philadelphia, Pa.) IV. Series.
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21/ RC268.7.P64P65 1985 616.99'4071 85-13384
10 ISBN 0-8412-0924-3
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e: Copyright © 1985
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n American Chemical Society
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PRINTED IN THE UNITED STATES OF AMERICA
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
ACS Symposium Series
M. Joan Comstock, Series Editor
Advisory Board
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3.f Robert Baker Robert Ory
28 U.S. Geological Survey USDA, Southern Regional
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5- Research Center
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1 Martin L. Gorbaty
bk- Exxon Research and Engineering Co. Geoffrey D. Parfitt
1/ Carnegie-Mellon University
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10. Roland F. Hirsch James C. Randall
oi: U.S. Department of Energy Phillips Petroleum Company
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98 Herbert D. Kaesz Charles N. Satterfield
9, 1 University of California—Los Angeles Massachusetts Institute of Technology
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Jul Rudolph J. Marcus W. D. Shults
ate: Office of Naval Research Oak Ridge National Laboratory
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on Charles S. Tuesday
ati Vincent D. McGinniss General Motors Research Laboratory
blic Battelle Columbus Laboratories
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Donald E. Moreland National Institute of
USDA, Agricultural Research Service Environmental Health
W. H. Norton C. Grant Willson
J. T. Baker Chemical Company IBM Research Department
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
FOREWORD
The ACS SYMPOSIUM SERIES was founded in 1974 to provide a
medium for publishing symposia quickly in book form. The
format of the Series parallels that of the continuing ADVANCES
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00 IN CHEMISTRY SERIES except that, in order to save time, the
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3.f papers are not typeset but are reproduced as they are submitted
28 by the authors in camera-ready form. Papers are reviewed under
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5- the supervision of the Editors with the assistance of the Series
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1 Advisory Board and are selected to maintain the integrity of the
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02 lished papers are not accepted. Both reviews and reports of
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In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
PREFACE
THE ENVIRONMENTAL ORIGIN OF MANY HUMAN CANCERS is gaining
increasing acceptance. Significant levels of cancer-causing agents are
commonly present in polluted air, automobile exhaust, tobacco smoke, and
many common foods. Direct evidence concerning the role of chemical
carcinogens in the etiology of human cancer is difficult to obtain due to
necessary restrictions on human experimentation. However, there is a
1 mounting volume of indirect evidence that supports the importance of
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pr chemical agents as causative factors.
3.
8 Epidemiological studies show wide variation in the incidences of various
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5- types of cancers in different populations. These geographic differences are
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19 often dramatic. For example, the incidence of female breast cancer is
bk- particularly high in the United States and relatively low in Japan. On the
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2 other hand, the occurrence of stomach cancer in these two countries is
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0. approximately reversed, being exceptionally high in Japan and relatively low
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oi: in the United States. These differences appear to be related more to diet and
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5 | lifestyle factors than to inherent genetic differences. Thus, the cancer profile
98 of the Japanese population in Hawaii shows a marked shift in the relative
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9, incidence of breast and stomach cancer away from the levels in Japan
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y toward those in the United States. In general the cancer patterns of migrant
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e: J populations tend to shift toward those patterns characteristic of the new
Dat environment.
on Carcinogenesis research has demonstrated the tumorigenic activities of a
cati large number of chemical substances in experimental animals. These include
ubli molecules of diverse chemical classes, organic and inorganiC., and natural
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products as well as compounds synthesized in the laboratory or produced by
industry.
Man has served as the unintentional guinea pig for the identification of
some major classes of carcinogens. These include the polycyclic aromatic
hydrocarbons (PAH), or polyarenes, which have been identified as the active
components of soot, which was recognized by the London surgeon Percivall
Pott two centuries ago as responsible for cancer of the scrotum in chimney
sweeps. Subsequently, polycyclic hydrocarbons have been implicated as
agents responsible for skin cancer in other occupations such as shale oil
distillation and mule spinning in the cotton industry.
The carcinogenicity of aromatic amines, such as benzidine and 2-naph-
thylamine, was first recognized by Rehn in the 1890s as an occupational
hazard in the German dyestuffs industry. Compounds in this class induce
vn
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
tumors in man predominantly in the urinary bladder. The nitrosamines,
another major class of carcinogens, were first recognized as such by their
induction of tumors in the livers of workmen in the chemical industry who
were using N-nitrosodimethylamine as a solvent.
Polycyclic aromatic hydrocarbons hold a unique place in carcinogenesis
research. The first pure compounds recognized as carcinogens more than 50
years ago were the PAH benzo[a]pyrene and dibenz[tf,/z]anthracene. Because
only certain polyarenes exhibit tumorigenic activity and the level of activity
is highly dependent upon molecular structure (e.g., number of fused rings,
molecular shape, and presence of methyl or other groups in particular
molecular regions), the PAH are ideally suited to studies of structure-activity
relationships. The polycyclic hydrocarbons are also exceptional in their
ability to induce various types of tumors selectively, dependent upon their
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00 mode of administration and other experimental conditions. Thus, oral
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3. administration of 10 mg of 7,12-dimethylbenz[tf]anthracene to female
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2 Sprague-Dawley rats was shown by Huggins to elicit mammary tumors with
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85- 100% incidence. Intravenous injection of a lipid emulsion of the same
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k-1 hydrocarbon to male or female Long-Evans rats selectively induced
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1/ leukemia with similarly high incidence. In contrast, intramuscular injection
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0 of this hydrocarbon into the legs of Long-Evans rats gave predominantly
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10. local sarcomas at the site of injection. Other malignancies may be induced by
oi: PAH under appropriate experimental conditions. PAH-induced tumors are
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5 | widely employed as standards in experimental oncology.
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1 Polycyclic aromatic hydrocarbons' potential importance in human
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1 cancer is strongly suggested by their environmental occurrence and their
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ate: potent hepatocarcinogenic aflatoxins. The environmental prevalence of PAH
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n is largely a consequence of PAH formation as products of combustion of
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ati fossil fuels and other organic matter. Although human populations are
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bli chronically exposed to low levels of polyarenes, individual levels of exposure
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and occupation.
Research in PAH carcinogenesis has made major advances in the past
decade. Most notable has been identification of diol epoxide metabolites as
the active forms of benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene, and
other carcinogenic PAH. This finding has stimulated enormous research
activity and opened the way to determination of the detailed molecular
mechanism of action of this important class of carcinogenic molecules.
The symposium upon which this book is based brought together leading
investigators concerned with the mechanisms of carcinogenesis of PAH at
the molecular level. The individual chapters in this book are not merely
verbatim reports of the symposium proceedings but rather critical reviews of
symposium topics with extensive references to investigations in other
laboratories. Since the pertinent literature references are scattered in journals
viii
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
in diverse fields ranging from synthetic and theoretical chemistry to oncology
and molecular biology, it has been difficult for nonspecialists to keep abreast
of recent advances. This book provides a convenient summary of current
developments that cuts across these diverse academic disciplines.
Several additional chapters on relevant topics that could not be
included in the symposium due to time limitations are also included in this
volume. Chapter 10 presents a unified theoretical treatment of the covalent
binding to DNA of the reactive diol epoxide metabolite of benzo[tf]pyrene
implicated as the active form of this hydrocarbon. Chapter 15 on the in vitro
metabolic activation of nitro polycyclic aromatic hydrocarbons is the first
review of this very active area of investigation. Interest in this topic has been
stimulated by the discovery that nitration of pyrene and other PAH by
1 oxides of nitrogen occurs in the atmosphere to form nitro-PAH derivatives
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pr0 which are often highly mutagenic. Chapter 14 on the carcinogenic metabo
3. lites of arylamines and arylamides reviews the large body of literature on the
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0 mechanism of carcinogenesis of this important class of PAH compounds.
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98 Since nitro-PAH are reducible by bacterial enzymes to polycyclic arylamines
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k- and the fused aromatic ring systems of both these classes of PAH
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1/ compounds may undergo activation to diol epoxide derivatives, multiple
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1 overlapping mechanistic pathways exist for the metabolic activation of
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oi: 1 unsubstituted PAH and their nitro- and amino-substituted derivatives,
d compounding the mechanistic complexity.
85 | This book is expected to be of interest to investigators active in all
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9, 1 aspects of carcinogenesis research as well as to graduate students, educators,
y 1 and others seeking an introduction to this important field of research.
Jul It is hoped that this volume will contribute toward the ultimate
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bli Additional support for the symposium was provided by the U.S.
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American Chemical Society for his personal contribution toward making
this project a success and my wife Helene for her support and understanding
throughout this project. Any opinions, findings, conclusions, or recommen
dations expressed herein are those of the authors and do not necessarily
reflect the views of the U.S. Department of Energy.
RONALD G. HARVEY
University of Chicago
Chicago, Illinois
March 22, 1985
IX
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
1
Polycyclic Aromatic Hydrocarbon Carcinogenesis
An Introduction
ANTHONY DIPPLE
LBI-Basic Research Program, Chemical and Physical Carcinogenesis Laboratory, National Cancer
Institute, Frederick Cancer Research Facility, Frederick, MD 21701
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0 Since polycyclic aromatic hydrocarbons are widely
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28 sources of the world, it is essentially impossible
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98 substances on a daily basis. It is particularly
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k- important, therefore, that the mechanism of action
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02 tion provides a general background on experimental
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doi: fionrv ohlyvderdo cianr btohnes .d iscIotv earlys ot htarta cpeosl ytchey ckleiyc asrtoempast ic
5 | hydrocarbons are the carcinogenic components of
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9 complex mixtures such as soots and tars and the
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9, more recent discovery that bay region dihydrodiol
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Jul bons that initiate the carcinogenic process.
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ati Pott, surgeon to St. Bartholomew's Hospital in London, that scrotal
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the fields of chemical carcinogenesis in general and polycyclic
aromatic hydrocarbon carcinogenesis in particular. This observa­
tion was followed a century later by von Volkmann's reports of
occupational skin cancers in workers in the coal tar industry in
Germany (_2), and by the early 1900fs it was widely recognized that
soot [produced by the inefficient combustion of coal and containing
up to 40% coal tar (3)], coal tar [produced by the destructive
distillation of coal], and pitch [the residue after distilling
coal tar] are all carcinogenic for man. At that time, it was
conceivable that a single carcinogenic substance might be respon­
sible for all the known occupational cancers (j4), but attempts to
characterize the carcinogens in these complex combustion and pyro-
lysis products had to await the development of an experimental
system for determining carcinogenic activity. It was not until
0097-6156/85/ 0283-0001 $06.00/0
© 1985 American Chemical Society
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
2 POLYCYCLIC HYDROCARBONS AND CARCINOGENESIS
1915 that such a system was developed by Yamagiwa and Ichikawa (5)
who succeeded in producing malignant skin tumors in rabbits by the
persistent topical application of coal tar. Three years later
Tsutsui (6) produced tumors in mice by repeated application of
tars to the skin, and this particular assay, which was quickly
adopted in other laboratories, has proved to be of lasting value
and is still used frequently today.
The series of events which then led to the identification of
certain polycyclic aromatic hydrocarbons as the first pure chemical
carcinogens has been described in depth by Sir Ernest Kennaway
(_7), a key participant in the discovery, and only a brief outline
of this exciting story is included herein. In 1921, Bloch and
Dreifuss (8) in Switzerland had established that the carcinogen in
coal tar was of high boiling point, was free of nitrogen and sul­
phur, formed a stable picrate, and was probably a complex hydrocar­
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0 bon. Kennaway pursued these leads after joining what is now the
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ch Institute of Cancer Research in London in 1922, and, amongst a
83. number of notable studies on carcinogenic tars, he demonstrated
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0 that pyrolyses of isoprene or acetylene in an atmosphere of hydro­
85- gen gave rise to carcinogenic distillates, thereby proving that
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1 carcinogenic activity resided in some compound containing only
bk- carbon and hydrogen (9).
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2 A second vital observation was made when Mayneord, a physicist,
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1 joined in the research effort and decided to examine the conspicu­
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1 ous fluorescence of the many carcinogenic distillates present in
oi: Kennawayfs laboratory. He found that most of the carcinogenic
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5 | tars exhibited a common fluorescence spectrum (A max 400, 418
98 and 440 nm) but, in subsequent studies with Hieger, none of the
9, 1 hydrocarbons available at that time exhibited these spectral char­
1 acteristics (_7). The spectrum of benz[ajanthracene was found to
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e: ogenic preparations but this similarity directed Kennawayfs atten­
at tion to Clar's report of the synthesis of dibenz[a_,h]anthracene
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n (10). Tumors were obtained when this hydrocarbon was repeatedly
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ati painted on to mice and thus it was established that the properties
ublic nsetcreuscstaurrye otfo ae lisciint glteu mpourrse icnh eamniicmaall s cowmeproeu ncdo n(t1a1i)n.e d within the
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Since the spectrum of dibenz [a_,hjanthracene was not identical
to that of the carcinogenic tars, carcinogenic activity obviously
was not confined to a unique chemical structure and indeed Cook,
who had joined this research effort in 1929, soon synthesized a
number of new hydrocarbons, and many of these were carcinogenic.
The outstanding problem of the carcinogen in the tars was ultimate­
ly resolved by a massive experiment beginning with the distillation
of 2 tons of gas-works pitch. Thereafter, by fractional distilla­
tion, differential extractions, fractional crystallization and by
following the fluorescence spectrum and carcinogenic activity of
the various fractions, Cook, Hewett and Hieger (12) were able to
obtain gram quantities of a crystalline material which was carcino­
genic and exhibited the fluorescence which had been associated
with carcinogenic activity. This material was resolved into three
separate substances, perylene and two unknown isomers of perylene
which were identified by structure-determining syntheses as benzo-
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.
1. DIPPLE Polycyclic Aromatic Hydrocarbon Carcinogenesis 3
[ajpyrene and benzo[ejpyrene. Benzo[ajpyrene was the source of
both carcinogenic activity and the characteristic fluorescence of
the carcinogenic tars. This finding completed a remarkable episode
of research during which the carcinogenic activity (or, at least,
some of the of the carcinogenic activity) associated with complex
materials like soots and coal tars came to be attributed to a
specific chemical component, benzo[ajpyrene.
Human Exposure
The carcinogenic activity of soots, tars and oils in man is beyond
dispute (13-16) and, in addition to the skin cancers which were
noted initially, there have also been several reports indicating
that higher incidences of respiratory tract and upper gastrointes­
tinal tract tumors are associated with occupational exposures to
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0 these carcinogens (summarized in refs. 13-16). While present day
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ch working conditions are drastically improved over those of the 19th
83. century, contemporary studies [for example on Danish chimney
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0 sweeps (17)] continue to find increased cancer risks associated
85- with exposure to these polycyclic aromatic hydrocarbon-containing
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1 materials. Nevertheless, because any given hydrocarbon is but
bk- one component of these complex occupational carcinogens, the posi­
21/ tion taken by Working Groups of the International Agency for
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1 Research on Cancer over the last ten years (13-16) is that indivi­
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1 dual hydrocarbons, such as benzo[ajpyrene, have not been proven to
oi: be carcinogens for man. This lack of direct proof of their carcin­
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5 | ogenicity for man should not be overinterpreted. It does not
8 imply that the human race Is resistant to these potent experimental
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9, 1 carcinogens and most carcinogenesis researchers adopt the view-point
1 that, until proof to the contrary is obtained, chemicals found to
uly be carcinogens in animals should be regarded as probable carcinogens
e: J for man. The polycyclic aromatic hydrocarbons have to be regarded
at in this way since some of them are very potent experimental
D
n carcinogens and the metabolism and DNA binding products of benzo[a]
atio pyrene in human cells and tissues are very similar to those seen
c in susceptible experimental animals (reviewed in 16). Some inves­
ubli tigators believe that the hydrocarbons are proven skin carcinogens
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and probable respiratory tract carcinogens for man (18).
The presence of polycyclic aromatic hydrocarbons in the
environment is of obvious concern and, apart from specific occupa­
tional environments, human exposure to these compounds derives
from combustion products released into the atmosphere. Estimates
of the total annual benzo[a]pyrene emissions in the United States
range from 900 tons (19) to about 1300 tons (20). These totals
are derived from heat and power generation (37-38%), open-refuse
burning (42-46%), coke production (15-19%) and motor vehicle
emissions (1-1.5%) (19,20). Since the vast majority of these
emissions are from stationary sources, local levels of air pol­
lution obviously vary. Benzo[ajpyrene levels of less than
1 ug/1,000 m^ correspond to clean air (20). At this level,
it can be estimated that the average person would inhale about
0.02 ug of benzo[ajpyrene per day, and this could increase
to 1.5 pg/day in polluted air (21).
In Polycyclic Hydrocarbons and Carcinogenesis; Harvey, R.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1985.