Download 1@ , \:a. - Cancer Research

[CANCERRESEARCH34, 2835—284
1, November 1974]
On the Origin of the Genes for Neoplasia: G. H. A. Clowes
Memorial Lecture'
Howard M. Temin
McArdle Laboratory, University of Wisconsin,Madison, Wisconsin53706
NORMAL CELL
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4..-@CELLDNA
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c::@ CANCERGENES)
CANCER CELL
Chart
1. The origin of the genes for cancer.
A cancer cell has in its
DNA (zig-zag line) genes for cancer (oval).
virions
contain
RNA
and
a DNA polymerase.
I shall
particularly deal with the two groups of avian ribodeoxy
viruses, the avian leukosis-sarcoma viruses and the reticulo
endotheliosis viruses. I shall then present our current ideas
about
the origin of these ribodeoxyviruses
and indicate
why I
believe that this origin provides a model for the formation in
normal
V
for cancer.
Ribodeoxyviruses
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t
cells of the genes
Ribodeoxyvirus is the name of a large group of animal
viruses (20). Virions of ribodeoxyviruses have a diameter of
about 100 nm and consist of an envelope surrounding an
internal core with no clearly observable symmetry. The
envelope consists of a lipid bilayer and external glycoproteins.
4
The core contains a ribonucleoprotein
particle consisting of 60
to 70 S RNA, basic proteins, and a DNA polymerase.
The ribodeoxyvirus
group includes viruses such as RSV,2
mouse mammary tumor virus, mouse leukemia virus, and
visna virus. As will be discussed below for avian ribodeoxy
viruses, the various ribodeoxyviruses differ very much in their
effects on infected cells and organisms.
Introduction
RSV
The question I am going to discuss is, “How
is the genome
RSV is the prototype ribodeoxyvirus. It, as well as all of the
of a normal cell changed into the genome of a cancer cell?― other avian ribodeoxyviruses (7), have C-type morphology;
This question is distinct from the questions of how the that is, the central core is not eccentrically located. RSV is a
biochemistry of a cancer cell differs from that of a normal cell member of the avian leukosis-sarcoma group of viruses as
or how the genes for cancer are expressed in a cancer cell. The shown by the antigenicity of its core proteins (the group
question of the origin of cancer genes can be formalized as in specific basic proteins and the group-specific DNA polymer
ase) and by the nucleotide sequence of its RNA. It causes rapid
Chart 1.
Before considering this question, I shall discuss some
characteristics
1 Presented
of ribodeoxyviruses,
at
the
1974
meeting
of
that
the
is, viruses whose
American
Association
for
Cancer Research in Houston, Texas. The work in my laboratory was
supported
by USPHS Research Grant CA-07175 from the National
Cancer Institute and Research Grant VC-7 from the American Cancer
appearance of sarcomas after injection into sensitive birds. In
cell culture,
it causes rapid cell transformation
with alterations
in cell morphology and cell multiplication. These alterations
occur within 2 or 3 days and can involve all of the cells in
a culture. The cell properties converted by infection with RSV
include the serum requirement for cell multiplication,
the rate
Society. I formerly held Research Career Development Award CA-8182
from the National Cancer Institute and now am an American Cancer
Society Research Professor.
2The abbreviations
used are:
Rous-associated
virus-O.
RSV,
Rous
sarcoma
virus;
NOVEMBER 1974
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RAV-O,
2835
@1@
H.M. Temin
of hyaluronic acid synthesis and the amount of the enzyme
hyaluronic acid synthetase, the control of glycolysis, the rate
of glucose transport, the concentration of cyclic 3', 5'-AMP,
the production of plasminogen activator, and some surface
properties.
Variants of RSV exist that are altered in the type of
neoplastic transformation that they cause, the morphology of
the transformed
cells, the temperature
stability of the
neoplastic transformation (mutants temperature sensitive for
transformation), and the presence or absence of neoplastic
transformation (td or NT mutants) (see review in Ref. 20). All
of these genetically different viruses appear to have very
similar virions. Therefore, the existence of these different virus
variants indicates that the RSV genome consists of two parts:
one part contains the genes specifying the virion proteins and,
therefore, the virion structure; the other part contains the
genes for neoplastic transformation (Chart 2).
These genes are RNA in RSV virions. When RSV causes
cancer, these genes are transcribed into DNA and integrated
with the cell DNA forming new DNA genes for neoplastic
transformation, as diagramed in Chart 3. This assertion, called
the DNA provirus hypothesis, is supported by many lines of
evidence. The most conclusive is the isolation from cells
infected by RSV of infectious DNA containing the informa
tion for production of RSV and for neoplastic transformation.
The infectious RSV DNA was first reported by Hill and
Hillova (8) in 197 1. We have confirmed and extended their
results (Table 1). The data in this table indicate that DNA
purified from either chicken or rat cells infected with RSV can
cause the production
of new virus and morphological
transformation in recipient chicken cells. The amount of DNA
required to cause transformation in one-half of the treated
cultures was 0. 1 pg. The infectious material was shown to be
DNA by its sensitivity to treatment with DNase and its
resistance to treatment with alkali, RNase, and Pronase.
This description makes it clear that RSV is extremely
efficient at causing tumors and forming cancer genes. There is
no progression in the sense used in cancer research in
RSV-induced transformation of chicken cells. All of the cancer
genes appear to be present soon after infection.
However, RSV is not a natural virus. It does not persist in
nonlaboratory
populations. RSV is a laboratory creature,
passaged and preserved by virologists.
RAV-O
RAV-O is another avian leukosis virus. Its virions contain
the same group-specific antigens and DNA polymerase as do
RSV virions, and its RNA has nucleotide sequences homolo
gous to most of the nucleotide sequences in Rous sarcoma and
other avian leukosis virus RNA (13, 14). However, RAV-O
causes no disease in infected chickens. Crittenden found no
increase in the incidence of leukemia in chickens either
naturally or artificially infected with RAV-O (L. B. Critten
den, personal communication).
RAV.O is a natural virus, in contrast to RSV which is a
laboratory virus. However, RAV-O is maintained in chicken
populations, not as a virus but as a provirus or cellular genes.
The existence of RAV-O as cellular genes in chickens is most
clearly shown by the experiments of Crittenden et a!. (4)
2836
RSV RNA GENOME
VIRION GENES, CANCER GENES
ED
Chart 2. The genome of RSV. This genome is RNA in the vision and
DNA in infected cells.
NORMAL CELL + RSV
(@Ws@
PROVIRUS)
CANCER CELL
Chart
3. The mechanism
of neoplastic
transformation
by RSV. The
provirus is indicated by a heavy zig-zag line. Other symbols are as in
Chart 1.
Table 1
Infectious DNA for RSV
DNA was extracted by a modified Marmur procedure from
Ch(RSV)a and from rat cells infected with B77 avian sarcoma virus, but
producing no virus. Serial 2-fold dilutions of DNA were added to
quadruplicate cultures of chicken embryo fibroblasts previously treated
with DEAE-dextran. Foci were scored after 8 to 14 days, and 50%
infectious
doses were calculated.
Other samples of DNA were treated
as
indicated before infection. Data from paper of Cooper and Temin (3).
infectious
dose
Donor DNA50%
(ag)Ch(RSV)0.1Ch(RSV)-DNase>10Ch(RSV)-alkali1.0Ch(RSV)-RNase,
salt0.1Ch(RSV)-Pronase0.1R(B77V)0.1
low
a Ch(RSV), chicken cells infected with and producing RSV.
diagramed in Chart 4. Crittenden et a!. showed that a cross of
two chickens that did not produce RAV-O yielded progeny
that could produce RAV-O. The two parental chickens did not
produce RAV-O for different reasons. One did not carry the
gene for RAV-O production (V), while the other was resist
ant to the spread of RAV-O (tvb').
While most of the nucleotide sequences of RAV-O RNA are
the same as those of RSV RNA, some are different. Some
nucleotide sequences in RSV RNA are not present in RAV-O
RNA. This is most clearly established by experiments of
Neiman et a!. (14), who showed by competition hybridization
that RSV RNA contained some nucleotide sequences that
were not competed by RAV-O RNA.
The genes for RAV-O are present in some chicken cells as
DNA. This can be shown by nucleic acid hybridization (10,
13) or more definitively by infectious DNA assay (Table 2).
These experiments demonstrate that the RAV-O genome is
present in cells as DNA and that the RAV-O genome does not
contain genes for transformation, only the genes for virus
production.
Therefore, the RAV-O genome (Chart 5) is
simpler than the RSV genome (Chart 2). The RAV-O genome
contains genes for virion proteins, but it does not contain
genes for transformation.
CANCER
RESEARCH
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VOL.
34
Origin of the Genes for Neoplasia
@
@\@@@tvb8
@@@tvbr
No RAV—O
NoRAV—O
RAV—O
Crittenden, Smith,Weiss,Sarma
‘974
Chart 4. The genetic transmission in chickens of the potential to
produce RAV-O. V, genes for RAV-O; tvl/, gene for sensitivity to
Subgroup B avian leukosis-sarcoma viruses; tvb', alielic gene for
resistance to Subgroup B avianleukosis-sarcomaviruses.
young chickens and selecting virus that caused rapid produc
tion of myeloblastosis (2).
Rous-associated virus-A is by the same criteria another avian
leukosis virus. In animals, it causes some leukosis (chicken
leukemia) with a low frequency. These leukemias appear only
after a high rate of virus production for a long time, that is,
after a long latent period. In cell culture, Rous-associated
virus-A causes no transformation of fibroblasts or of reticulo
endothelial cells. It is, therefore, a weakly transforming virus.
Rous-associated virus-A is a natural virus. It is passed from
infected hens to their eggs by infection by virions (5). The
infected hens do not develop leukemia in all cases, and when
they do it is after they have laid many infected eggs. Thus,
Rous-associated virus-A persists in nonlaboratory populations
of chickens.
Reticuloendotheliosis
Table 2
Infectious DNA for RA V.0
DNA was extracted and assayed as described in the legend of Table 1
from Ch(RSV)a, Ch(RAV-O) or from Cli. One day after treatment with
Ot and Ch(RAV-O) DNA'S, pheasant cells were added. After 1 week,
the supernatants were assayed for sedimentable DNA polymerase or
uridine-3 H-labeled particles. RSV production was assayed on chicken
cells. Data from papers of Cooper and Temin (Ref. 3 ; G. M. Cooper and
H. M. Temin. Infectious DNA from Cells Infected with Rous Sarcoma
Virus, Reticuloendotheliosis Virus, or Rous-associated Virus—O.Cold
Spring Harbor Symp. Quant. Biol., in press).
doseVirusTransformationCh(RSV)0.10.1Ch(RAV-O)0.2>1001>10>10
infectious
Donor DNA50%
Viruses
Reticuloendotheliosis viruses form another group of avian
ribodeoxyviruses. They share with the avian leukosis-sarcoma
viruses the general characteristics of ribodeoxyviruses and even
C-type morphology. They differ from the avian leukosis
sarcoma viruses in the nature of their envelope glycoproteins,
their core basic proteins, and their DNA polymerase and in the
nucleotide sequence of their 60 to 70S RNA.
After injection into young fowl, reticuloendotheliosis
viruses may cause rapid death as a result of an acute infection
with necrosis of the spleen and liver, or reticuloendotheliosis,
which is a proliferation of primitive mesenchymal elements
(17). The acute disease is mimicked in cell culture of
fibroblasts where these viruses cause rapid appearance of a
strong cytopathic effect. A chronic infection without cell
death or transformation is then established (23).
Like the avian leukosis viruses, the reticuloendotheliosis
a Ch(RSV), chicken cells producing RSV; Ch(RAV-O),
chicken cells
producing RAV-O; Cli, chicken cells not producing virus.
RAV—OGENOME
VIRION GENES
chart 5. The genome of RAV-O. The genome consists of RNA in
visionsand of DNA in infected cells.
Other Avian Leukosis Viruses
Avian myeloblastosis virus is another avian leukosis virus. Its
virions contain the same core group-specific antigens and DNA
polymerase as do RSV and RAV-O virions, and its RNA has
nucleotide sequences similar to those of the RNA's of other
avian leukosis viruses. On injection into susceptible chickens,
avian myeloblastosis virus causes rapid appearance of myelo
blastosis, a myeloid leukemia of chickens. In cell culture, it
can infect fibroblasts with virus production, but there is no
transformation. However, it can cause rapid transformation of
embryonic reticuloendothelial
and muscle cells (12). There
fore, avian myeloblastosis virus is a cell-dependent, strongly
transforming virus. Again, as in the case of the strongly
viruses replicate through a DNA intermediate. As shown by
the data in Table 3, DNA. isolated from cells infected with
reticuloendotheliosis viruses can cause formation of plaque
forming virus in sensitive cells.
Nucleic acid hybridization is another way to demonstrate
the DNA intermediate of reticuloendotheliosis viruses. Sixty S
Table 3
Infectious DNA for reticuloendotheliosis
viruses
DNA was extracted and assayed as described in the legend of Table 1
from Ch(TDSNVY' j@either the acute (3 DAI) or the chronic (14 DAI)
phase of infection
and from Ch spleen(REV-T).
Virus production
was
measured by assay of supernatants for cytopathic effect on chicken and
duck fibroblasts.
Data from paper of Cooper and Temin (3).
infectious dose
Donor DNA50%
(pg)Ch(TDSNV)
DAI0.1Ch(TDSNV)
3
DAI0.1Ch 14
spleen(REV-T)0.2Ch(TDSNV)-DNase>10Ch(TDSNV)-RNase,
salt0.1Ch(TDSNV)-alkali1.0Oi(TDSNV)-l.71
low
g CsCl/cucm0.05
transforming RSV, avian myeloblastosis virus is a laboratory
a Ch(TDSNV),
chicken fibroblasts
producing
Trager duck spleen
necrosis virus; DA!, days after infection; Ch spleen(REV-T),
chicken
virus. It was selected by passing virus from myeloblastosis in
spleen cells producing reticuloendotheiosis
virus (strain T).
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2837
H. M. Temin
@
RNA was isolated from purified reticuloendotheliosis
virus
virions, labeled with ‘
25 and annealed to DNA from infected
cells (Chart 6). Most of the RNA became RNase resistant,
indicating that most of the nucleotide sequences of the RNA
were present
as DNA in infected
cells.
RNA Viruses and Cancer
Our discussion of these avian RNA viruses with different
degrees of pathogenesis allows us to formulate criteria for
whether an RNA virus can modify a cell genome to cause
neoplasia. As can be seen in Table 4, the viruses that cause
neoplasia contain cancer genes. The more efficient the viruses
are at causing
neoplastic
transformation,
the
more
cancer
genes they contain. The viruses that do not cause transforma
tion, like RAV-O and Trager duck spleen necrosis virus, do not
contain genes for cancer. Rous-associated virus-A, which has a
low efficiency of causing cancer, apparently has only some of
the genes for cancer (1 1, 14).
Ui
F@4
0
m
>-
a0
z
However, this formulation provides an answer only to a
special case of the question posed in Chart 1. When the
strongly transforming RNA viruses cause cancer, they do so as
described for RSV in Chart 3, that is, by synthesizing in cells
the genes for cancer coded in the viral genome. However, this
formulation does not tell us how the genes for cancer are
formed when there is no overt evidence of a strongly
transforming RNA tumor virus.
Possible Mechanisms of Carcinogenesis
A number of hypotheses can be proposed to explain the
creation of the genes for cancer in normal cells (Chart 7). [The
infection mechanism discussed above (Chart 3) is the fourth
one.] In all the hypotheses the cancer cells contain the genes
for neoplastic transformation. The hypotheses differ as to
whether or not these genes are present in normal cells and,
therefore, the nature of the genetic changes in carcinogenesis.
In a mutation hypothesis, a normal cell does not contain
genes for cancer. During carcinogenesis, these appear by
mutation.
In a differentiation hypothesis, normal cells contain the
genes for cancer in an inactive form. During carcinogenesis,
these genes are activated so that their phenotypic expression
leads to the formation of a cancer cell. The oncogene
hypothesis is a special case of a differentiation hypothesis (6,
9). In the oncogene hypothesis, as in all other differentiation
hypotheses, the genes for cancer are present in normal cells in
an inactive form and become active during carcinogenesis. The
i0
N
NORMAL CELL
@
) CANCER CELL
MUTATION
,ww\,'-f\,\
>
DIFFERENTiATION
@
cot (molesec/
Chart 6. Hybridization
liter)
of Trager duck spleen necrosis virus (TDSNV)
@
I 2 S I-labeled
@
virus-infected and uninfected cells. TDSNV ‘
25I-labeled RNA (3000
cpm) was hybridized to DNA from uninfected chickens (Ch DNA), an
uninfected Pekin duck (P. Du DNA), and TDSNV-infected chicken
RNA
to
DNA's
from
Trager
duck
spleen
ONCOGENE
necrosis
INFECTION
cells ICh(TDSNV) DNA I . After different times of hybridization,
the
extent of hybridization
was determined
by RNase A and RNase T,
digestion. The RNase-resistant cpm (200 cpm) were subtracted before
the calculation
of percentage
of hybridization.
Data from
paper
Kang and Temin (10).
of
,@w%,%A@,#\
>
,W'1s.@,\
>
PROTOVIRUS
,w@v',w'
Chart 7. Hypotheses
>
of possible genetic
mechanisms
of carcinogene
515.Symbols as in Charts 1 and 3.
Table 4
Formation of neoplasiaby RNA viruses
This table summarizes
the data discussed
in the preceding
part of the text.
to cause
neoplasiaPresence
VirusAbility
virusRSV++4*Avian
myeloblastosis virus
virus-A1*
±bRAV-O00Trager
Rous-associated
of cancer
genes in
±4*a
duck spleen necrosis virus00
a Hypothesized.
b Lai et a!. (1 1); Neiman
2838
et al.(14).
CANCER RESEARCH VOL. 34
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Origin of the Genes for Neoplasia
oncogene hypothesis differs from other differentiation hy
potheses in that the oncogene hypothesis proposes that the
genes for cancer are those of a strongly transforming RNA
tumor virus. Therefore, in the oncogene hypothesis these genes
for cancer are associated with the genes for an RNA tumor
virus virion.
The protovirus hypothesis is a special case of a mutation
hypothesis (20). In the protovirus hypothesis, normal cells do
not have the genes for neoplastic transformation. These genes
appear by variational processes during carcinogenesis. The
protovirus hypothesis differs from other mutation hypotheses
by postulating that the genetic variations leading to the
formation of the genes for cancer occur in a part of the normal
cell genome involved in DNA to RNA to DNA information
transfer.
Some data can be secured relating to these hypotheses by
asking what genes for cancer are present in normal cells. When
DNA was extracted from normal cells, as it was extracted for
the experiments described in Tables 1, 2, and 3, and added to
other normal chicken cells, we found no transformation or
virus production (Table 2). This experiment indicates that
normal, nonvirus-producing chicken cells do not contain genes
for neoplastic transformation.
In addition, it shows that
normal, nonvirus-producing chicken cells do not contain genes
for a complete provirus.
Therefore, the genes for RAV-O in normal chickens
discussed above (Chart 4) are for a defective or incomplete
provirus of RAV-O. Some genetic change must occur for the
cells to start producing RAV-O. This genetic change is
reflected in the ability of the DNA from RAV-O-producing
chicken cells to transfer the ability to produce RAV-O and the
lack of ability of DNA from chicken cells not producing virus
to transfer the ability to produce RAV-O.
These experiments are not consistent with simple differenti
ation hypotheses, including the oncogene hypothesis. These
results, however, do not rule out more complex differentiation
hypotheses in which there are several genes for cancer and
these genes are present in normal cells in an unlinked form.
The Protovirus Hypothesis
Now, I shall consider the protovirus hypothesis for cancer in
more detail. This hypothesis states that genes for neoplastic
transformation arise in an organism as a result of misevolution
of a normal system of DNA to RNA to DNA information
transfer.
At present, there is no evidence directly testing this
hypothesis. There is, however, evidence consistent with a
protovirus
hypothesis
for the origin of ribodeoxyviruses.
This
hypothesis states that ribodeoxyviruses arise as a result of
misevolution of normal cellular genes. The evidence comes
from experiments involving nucleic acid hybridization and
study of DNA polymerase relationships.
When
nucleic
acid hybridization
experiments,
like those
described in Chart 6, were carried out between RNA's from a
reticuloendotheliosis virus or from RAV-O and DNA from a
variety of fowl, different extents of hybridization were found
(Table
5). The distribution
of sequences
of RAV-O
RNA in
DNA paralleled the closeness of the relationship of the fowl to
chickens. There was most hybridization to chicken DNA; less
to pheasant, quail, and turkey DNA; and none to duck DNA.
Endogenous sequences of reticuloendotheliosis virus RNA in
fowl DNA were found to the extent of about 10% in all of the
gallinaceous birds, but none were found in duck DNA.
In addition to these nucleotide sequence homologies
between virus RNA and cell DNA, there are serological
relationships between the DNA polymerases of both reticulo
endotheliosis
and avian leukosis-sarcoma
viruses and the DNA
polymerases of normal cells. An example of these relationships
is seen in the data in Chart 8, which indicate that
reticuloendotheliosis virus DNA polymerases specifically bind
antibody made to the chicken large DNA polymerase.
In addition to these relationships, there are a large number
of other homologies between the genes of avian ribodeoxy
viruses and chicken cells and the genes of mammalian
ribodeoxyviruses and mammalian cells. (See Refs. 21 and 22
for a more complete
discussion
of these relationships.)
These data indicate that the avian ribodeoxyviruses are
related to the class Ayes, especially to the order Galliformes.
The avian leukosis-sarcoma viruses apparently are an offshoot
from the genus Gallus. However, it cannot yet be determined
from which fowl the reticuloendotheliosis viruses evolved (2 1,
22).
To explain these relationships between ribodeoxyviruses
and cells, I have postulated an evolution, described in Chart 9,
in which successive DNA to RNA to DNA information
Table 5
Endogenousvirus-specificnucleotide sequencesin DNA of different fowl
Hybridization was performed as described in the legend to Chart 6 with ‘
25I-labeled 60S
RNA's from Trager duck spleen necrosis virus (2200 cpm) or RAV-0 (3000 cpm) and DNA
from livers of the indicated fowl or calf thymus DNA. Background counts of 135 cpm were
subtracted before calculation of percentages of hydridization. Data from paper of Kang and
Temin (10).
DNAChickenPheasantQuailTurkeyDuckCalf
of
RNA-' 2 5
thymusTrager
@Source
spleenba101010<2<2necrosis
duck
virusRAV-O55201510<1<1
@
a RNA-' 2 5 hybridized at a C0 t of 8 X 10@ moles-sec/liter. Only the saturation value is
given.
NOVEMBER
1974
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2839
@1@
H. M. Temin
transfer system is involved in differentiation
(19, 21).
IgG-L
and in evolution
>-
I—
Summary and Conclusions
>
I—
C-)
There are two groups of avian ribodeoxyviruses, the avian
leukosis-sarcoma viruses and the reticuloendotheliosis viruses.
Virions of these viruses contain RNA, and the viruses replicate
through a DNA intermediate. There is wide variation from
none to great among these viruses in their ability to cause
z
C-)
0 4
+
20
+
+
5
10
\j@vWW\
+
15
DNA POLYMERASE(p
g)
Chart
8. Antibody-blocking
activity
\JW@fW\
of DNA polymerases for
antibody
against chicken large DNA polymerase
(IgG-L). Antibody
against chicken large DNA polymerase
(4 @zg)was incubated in 25 @zl
4,
VV'VWvt\
with the indicated amounts of reticuloendotheliosis virus (strain T)
(REV-fl, chicken embryo large (CH-L), Trager duck spleen necrosis
virus (TDSNV), chicken embryo small (CH-S), rat liver large (RL-L),
RSV-RAV-O, and Escherichia co/i I DNA polymerases. After 20 min,
the mixtures were heated to inactivate the DNA polymerases. (The E.
co/i DNA polymerase had been previously inactivated.)
Partially
purified chicken embryo large DNA polymerase
was added to the
+
viruses. Zig-zag line, DNA; straight line, RNA. The increasing
and curvature indicate the evolution of viral genes.
against
chicken
embryo
large DNA polymerase
and was
called 0% blocking. The percentage of blocking was calculated as the
percentage
of increase in activity after preincubation
.
VVV@@W\
with the indicated
‘1'
DNA polymerases. Data from work of Mizutani and Temin (15). The
apparent better blocking by reticuloendotheliosis virus (strain T) DNA
polymerase than by the homologous chicken embryo large DNA
polymerase is the result of the impurity of the chicken embryo large
DNA polymerase
preparation.
transfers
to
thickness
\vAvt\A/W\
incubation mixtures. After 30 mm of further incubation, the DNA
polymerase activity remaining was assayed with activated calf thymus
DNA as a template•primer.The DNA polymerase activity remaining in
the sample incubated without antibody was set at 100%. Eighty % of
the chicken embryo large DNA polymerase was neutralized by the 4 @g
of antibody
VIRUS
Chart 9. The protovirus hypothesis for the origin of ribodeoxy
4
VvWvV\
4,
lead
changes
in the
cell
genome.
These
changes
result in the accumulation and alteration of nucleic acid
sequences until the genome of an infectious virus is produced.
The virus then exists apart from the cell and can infect other
organisms.
I postulate a similar process for the formation of the genes
for cancer. As a result of misevolution or variation in
successive DNA to RNA to DNA information transfers, the
genes for cancer are produced (Chart 10).
Strongly transforming viruses, like RSV, arise as a result of
recombination between the new genetic elements described in
Charts 9 and 10 (1 , 18). This recombination creates a virus
genome containing genes for virions and for neoplastic
transformation. The cancer genes exist before the cancer virus.
The formation of Kirsten murine sarcoma virus may be an
example of this process (16).
The cellular system of DNA to RNA to DNA information
transfer does not exist to cause formation of ribodeoxyviruses
or the genes for cancer. I have postulated that this information
2840
4,
\/WWvA\
4,
4,
@vWWV\
4,
\A@A/\
Chart 10. The protovirus hypothesis for the origin of the genes for
cancer. Zig-zag line, DNA; straight line, RNA. The increasing thickness
and curvature indicate the evolution of cancer genes. Oval, cancer
genes.
CANCER
RESEARCH
VOL. 34
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Origin of the Genes for Neoplasia
cancer. The viruses that cause cancer seem to have genes for
cancer. Carcinogenesis by these strongly transforming viruses
involves the formation in infected cells of genes for cancer
copied from the viral genome. Normal chicken cells do not
contain infectious DNA for transformation
or for virus
production. Therefore, there is not an inactive provirus of a
strongly transforming virus in normal chicken cells.
The protovirus hypothesis for cancer states that the
genes for neoplastic transformation arise in an organism as a
result of misevolution of a normal system of DNA to RNA to
DNA information transfer. The protovirus hypothesis for the
origin of ribodeoxyviruses states that ribodeoxyviruses arise as
a result of misevolution of normal cellular genes. There is
evidence from experiments involving nucleic acid hybridiza
tion and study of DNA polymerase relationships for the
protovirus hypothesis for the origin of ribodeoxyviruses.
REFERENCES
1. Altaner, C., and Temin, H. M. Carcinogenesis by RNA Sarcoma
Viruses. XII. A Quantitative Study of Infection of Rat Cells in
Vitro by Avian Sarcoma Viruses. Virology, 40: 118—134, 1970.
2. Beard, J. W. Avian Virus Growths and Their Etiologic Agents.
Advan. Cancer Res., 7: 1—127,1963.
3. Cooper, G. M., and Temin, H. M. Infectious Rous Sarcoma Virus
and Reticuloendotheliosis Virus DNA. J. Virol., in press.
4. Crittenden, L. B., Smith, A. J., Weiss, R. A., and Sarma, P. S. Host
Gene Control of Endogenous Avian Leukosis Virus Production.
Virology,57: 128—138,1974.
5. Di Stefano, H. S., and Dougherty, R. M. Mechanisms for
Congenital Transmissions of Avian Leukosis Virus. J. Nati. Cancer
Inst., 37: 869—883,1966.
6. Gross, L. Facts and Theories on Viruses Causing Cancer and
Leukemia. Proc. Natl. Acad. Sci. U. S., 71: 2013—2017, 1974.
7. Hanafusa, H. Avian RNA Tumor Viruses. In: Cancer—ACompre
hensive Treatise, in press.
8. Hifi, M., and Hillova, J. RNA and DNA Forms of the Genetic
Material of C-Type Viruses and the Integrated State of the DNA
Form in the Cellular Chromosome Biochim. Biophys. Acta, 355.
7—48,1974.
9. Huebner, R. J., and Todaro, G. J. Oncogenes of RNA Tumor
NOVEMBER
Viruses as Determinants of Cancer. Proc. Natl. Acad. Sci. U. S., 64:
1087—1094,
1969.
10. Kang, C.-Y., and Temin, H. M. Reticuloendotheliosis Virus Nucleic
Acid Sequencesin Cellular DNA. J. Virol., in press.
11. Lai, M. M. C., Duesberg, P. H., Horst, J., and Vogt, P. K. Avian
Tumor Virus RNA: A Comparison of Three Sarcoma Viruses and
Their Transformation-Defective Derivatives by Oligo-nucleotide
Fingerprinting and DNA-RNA Hybridization. Proc. Nat!. Aced.
Sci. U. S., 70: 2266—2270, 1973.
12. Moscovici, C., Moscovici, M. G., and Zanetti, M. Transformation of
Chick Fibroblast Cultures with Avian Myeloblastosis Virus. J.
Cellular Physiol., 73: 105—108,1969.
13. Nieman, P. E. Measurement of Endogenous Leukosis Virus
Nucleotide Sequences in the DNA of Normal Avian Embryos by
RNA-DNA Hybridization. Virology, 53: 196—204,1973.
14. Nieman, P. E., Wright, S. E., McMillin,C., and MacDonnell, D.
Nucleotide Sequence Relationships of Avian RNA Tumor Viruses:
Measurement of the Deletion in a Transformation-Defective
Mutant of Rous Sarcoma Virus. J. Virol., 13: 837—846,1974.
15. Mizutani, S., and Temin, H. M. Specific Serological Relationships
Among Partially Purified DNA Polymerases of Avian Leukosis
Sarcoma Viruses, Reticuloendotheliosis Viruses, and Avian Cells. J.
Virol.,
13:1020—1029,
1974.
16. Scolnick, E. M., Rands, E., Williams,D., and Parks, W. P. Studies
on the Nucleic Acid Sequences of Kirsten Sarcoma Virus: A Model
for Formation of a Mammalian RNA-Containing Sarcoma Virus. J.
Virol., 12: 458—463, 1973.
17. Taylor, H. W., and Olson, L. D. Chronological Study of the T-Virus
in Chicks. I. Development of Lesions. Avian Diseases, I 7:
782—794,1973.
18. Temin, H. M. Malignant Transformation of Cells by Viruses.
Perspectives Biol. Med., 14: 11—26,1970.
19. Temin, H. M. The Protovirus Hypothesis. J. Nail. Cancer Inst., 46:
hI—Vu!, 1971.
20. Temin, H. M. Cellular and Molecular Biology of RNA Tumor
Viruses, Especially Avian Leukosis-Sarcoma Viruses and Their
Relatives. Advan. Cancer Res., 19: 47—104,1974.
21. Temin, H. M. On The Origin of RNA Tumor Viruses. Ann. Rev.
Genet.,
inpress.
22. Temin, H. M. On the Origin of RNA Tumor Viruses. Harvey
Lectures, in press.
23. Temin, H. M.,and Kassner,V. K. Replication of Reticuloendothei
osis Viruses in Cell Culture:
291—297,1974.
Acute Infection.
J. Virol., 13:
1974
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2841
On the Origin of the Genes for Neoplasia: G. H. A. Clowes
Memorial Lecture
Howard M. Temin
Cancer Res 1974;34:2835-2841.
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