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(CANCER RESEARCH 52. 6348-6352. November 15. 1992]
Intrinsic Radiosensitivity of Normal Human Fibroblasts and
Lymphocytes afterHigh- and Low-Dose-Rate Irradiation1
Fady B. Geara,2 Lester J. Peters, K. Kian Ang, Jennifer L. Wike,
Susan S. Sivon, Roland Guttenberger,
David L. Callender, Edmond P. Malaise, and William A. Brock
Departments of Experimental Radiotherapy [F. B. G., J. L. W., S.
S. S., W. A. B.]. Clinical Radiotherapy [F. B. G., L. J. P., K. K.
A.], Head and Neck Surgery[D. L. C.], and Biomathematics ¡R.G.],
The University of Texas, M. D. Anderson Cancer Center, Houston,
Texas 77030, and Laboratoire de RadiobiologieCellulaire,
UnitéINSERM 247, Institut Gustave Roussy, 94805 Villejuif, France
¡E.P. M.]
ABSTRACT
The existence of heritable radiosensitivity syndromes and
clinicalobservations in radiotherapy patients suggests that human
cellular radiosensitivity differs among individuals. We report here
an in vitrostudy of radiosensitivity in 30 fÃ-broblast and 29
lymphocyte culturesobtained from cancer patients and controls. In
25 cases, both fibroblastsand lymphocytes were obtained from the
same donors. Fibroblasts werecultured from skin biopsy samples, and
peripheral T-cell lymphocytes
were cultured from blood. Clonogenic survival assays were
performed byusing high- and low-dose-rate irradiation; lymphocytes
were in ( >,,phase
and fibroblasts in confluent plateau phase. Various end points
werecalculated and compared (i.e., surviving fraction at 2 Gy,
initial slope ofthe survival curve, and doses resulting in 10 and
1% survival, respectively). Depending on the end point, the
coefficient of variation of thesurvival parameters ranged from 31
to 68% for lymphocytes and 21 to41% for fibroblasts following
high-dose-rate irradiation. Similar ranges»ere obtained after
low-dose-rate irradiation. Variance analysis per
formed on replicate assays in cultures derived from the same
patientshowed that variation due to technical or sampling errors
was significantly lower than variation between individuals (/' =
0.00034 and 0.014
for fibroblasts and lymphocytes, respectively). No correlation
was observed between the radiosensitivity of lymphocyte and
fibroblast cultures derived from the same donors. We conclude that
there is significant variation in normal cell radiosensitivity
among individuals. On theother hand, comparisons of lymphocyte and
fibroblast radiosensitivitiessuggest that tissue-specific
characteristics, such as differentiation sta
tus, may variably modulate radiosensitivity.
INTRODUCTION
As several previous reports have argued, the existence of
avariety of heritable syndromes expressing a radiosensitive
phe-notype is evidence for a genetic influence upon
radiosensitivity(1-4). The most striking example is AT,3 an
autosomal reces
sive disorder that causes immunological dysfunction, pronenessto
cancer, and an unusual susceptibility to radiation injury(5-10).
This increased sensitivity is found in all cells and tissues, both
in vivo (5, 9) and in vitro (6-8).
Clinical observations in radiotherapy patients with no
knowngenetic syndromes have revealed large individual differences
intissue reactions after treatment. This has been quantified
byTuresson (11), who studied normal tissue reactions in breast
Received 6/18/92; accepted 9/3/92.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.
1This investigation was supported by research grants from the
National CancerInstitute (CA-50192, CA-06294, and CA-16672), the
Association pour la Recherche sur le Cancer, the University Cancer
Foundation, and the Katharine M. Un-sworth Charitable Annuity Lead
Trust.
2 To whom requests for reprints should be addressed, at
Department of Radiotherapy, Box 97, The University of Texas M. D.
Anderson Cancer Center, 1515Holcombe Boulevard, Houston, TX
77030.
1The abbreviations used are: AT, ataxia telangiectasia: LDR.
low-dose rate;HDR, high-dose rate; SF2, survival at 2 Gy;
«,initial slope of the survival curve;DIO, DI, dose resulting in
10 and 1% survival, respectively; DO,dose resulting in 1log cell
kill; CV, coefficient of variation.
cancer patients following a given physical dose of
radiationadministered over a given period of time to the same
tissues.Long-term follow-up of these patients revealed wide
differencesin individual normal tissue responses, with some
patients experiencing minimal skin reactions and others
experiencing severe fibrosis and telangiectasia. These findings
further supportthe existence of a significant genetic component in
the determination of cellular and tissue radiosensitivity.
The ability to detect differences in radiosensitivity could
havean important impact upon clinical radiotherapy, since dose
limitations are based on acute and late toxicity, and the severity
ofearly and late effects cannot be predicted ahead of time.
Latetoxicity remains a major concern in radiotherapy planning,where
dose limits have been set based on the estimated probability of the
risk of injury for a given physical absorbed dosewithout regard to
individual variability of response. Therefore,identifying patients
who have a greater or lesser than averagerisk for complications
could allow for an adjustment of radiation dose. Such individual
adjustments could, theoretically, prevent complications in
"sensitive" patients and increase theprobability of cure in
"resistant" patients (4, 12).
Although the variability in radiosensitivity among
normalindividuals is not clearly documented, several studies have
compared the in vitro radiosensitivity of cultured cells derived
fromnormal individuals (3, 13-20; summarized in Table 1). Most
reports conclude that heterogeneity between individuals
doesexist, but the degree of variability reported is generally
small. Ithas been suggested that the use of LDR irradiation in
measuring cellular radiosensitivity may provide better
discrimination(13, 15, 21-23). The rationale is that, during LDR
irradiation,damage and repair take place at the same time, thus
amplifyingthe influence of different repair rates between cultures.
Anotheradvantage of LDR irradiation is that it results in simple
exponential survival curves that can be mathematically fit by using
alinear model, resulting in less error related to curve fitting
thanwith nonlinear data.
If individual heterogeneity in radiosensitivity exists for one
ormore cell types (e.g., fibroblasts or lymphocytes), and if
thesedifferences are due to genetic differences, then one may
expectthat individuals from whom, for example, sensitive
fibroblastcultures are derived, would also demonstrate sensitivity
in cultures from other normal cell types. This is indeed the case
forindividuals with AT, who show extraordinary radiosensitivity
invirtually all cell types tested. However, two studies in
apparently normal individuals found no correlation between the
radiosensitivity of cycling fibroblasts and resting peripheral
T-cell
lymphocytes (17, 18). This may be partly accounted for by
thefact that, in both studies, radiosensitivity was measured in
different phases of the cell cycle for each cell type. Also, one
ofthese studies (18), showed no significant differences in
D,0values between individuals for either fibroblasts or
lymphocytes, thus precluding any tests for correlation.
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l.\ IITKO NORMA! CKLL RADIOSKNSITIVITY
Table 1 Variation among individuals in normal cell
radiosensitivity, reportedin the literature, for fibroblasts (F)
and lymphocytes (L) in terms of coefficient
of variation of different radiosensitivity parametersItalic
numbers are calculated from the published data or graphs.
CVi
Authors (Ref.) Cell type n" SF2 010
Cox and Masson(16)Deschavanneet al.(14)Little
et al.(1)Littleétal.(19)Kushiro
et al. (18,27)Weeks
étal.(13)Banétal.(15)FFFFFLFFF»34702473222262151541202415.51811.65.92010914191114
" Number of cell strains studied.* Fibroblast cultures derived
from breast cancer patients.
In this study we investigated the degree of
radiosensitivityvariation in normal peripheral T-cell lymphocyte
and skin fi-broblast cultures derived from individuals with no
known radiosensitivity syndromes. This report focuses on variation
between individuals, the technical aspects of lymphocyte
andfibroblast survival measurement, comparison of HDR andLDR
irradiation, and comparison of the radiosensitivity of lymphocytes
and fibroblasts from the same individual.
MATERIALS AND METHODS
Patients. For peripheral T-cell lymphocyte cultures, a total of
33blood samples were obtained from 23 patients with head and
neckcancers, 2 patients with breast cancer, and 8 normal healthy
volunteers.For fibroblast cultures, 31 skin samples were obtained:
25 by punchbiopsy from the inside of the forearm (23 head and neck
cancer, and 2breast cancer patients), and 6 were skin samples from
mastectomyspecimens (Table 2). Repeat measurements were performed
on fourfibroblast cell strains (one derived from a patient and
three from controls) after HDR irradiation, and on two cell strains
after LDR irradiation (both derived from controls). For
lymphocytes, repeat measurements were performed on six blood
samples derived from the samedonor (Table 3).
Fibroblast Cultures and Radiosensitivity Measurements. After
obtaining informed consent, 6-mm punch biopsies of the skin were
takenunder local anesthesia. All chemical products were purchased
fromSigma Chemical Co. (St. Louis, MO) unless otherwise noted.
Subcutaneous fat was removed from the sample, and the remaining
tissue wasminced with scissors into 1- to 2-mm pieces, which were
disaggregatedfor 30 min by magnetically stirring in an enzyme
cocktail containing1% collagenase type III (Boehringer Mannheim
Biochemicals, Indianapolis, IN) and 1% trypsin (GIBCO, Grand
Island, NY) in calcium/magnesium-free Hanks' balanced salt
solution. Cells were spun down,
resuspended and counted, then inoculated into minimum
essentialmedium, supplemented with 15% fetal bovine serum,
antibiotics(100 Mg/ml penicillin, 50 Mg/ml streptomycin), and 5
mg/ml ampho-tericin B. All cultures were fed twice weekly with the
same medium, butwithout amphotericin B. After 2-3 weeks of
incubation, cells weretrypsinized (0.25% trypsin, 0.04% EDTA) and
subcultured.
Radiosensitivity was measured by clonogenic assay.
Contact-inhibited confluent fibroblast cultures (third passage)
were irradiated asmonolayers at different doses with the use of
both HDR and LDRirradiations. Cultures were trypsinized as
described above, counted, andthen inoculated into 100-mm culture
dishes, using five inoculum sizelevels for each dose point.
Lymphocyte Culture and Radiosensitivity Measurements. Peripheral
T-cell lymphocytes along with other mononuclear cells were
separated from blood samples by centrifugation on a Ficoll/Hypaque
density gradient (Becton Dickinson and Co., Lincoln Park, NJ).
Themononuclear cell layer was then removed, rinsed twice with
phosphatebuffered saline, and the lymphocytes were counted by using
a hemacy-
tometer. The lymphoblastoid cell line BL 3590 was used as a
source offeeder cells; it was maintained in RPMI media (JRH
Biosciences, Len-exa, KS) supplemented with 15% fetal calf serum,
200 Mg/mlglutamine,100 Mg/ml penicillin, and 50 mg/ml
streptomycin.
The limiting dilution assay for primary lymphocytes was used
tomeasure clonogenic survival of lymphocytes. It was a modification
ofthe method published by Trainor and Morley (24) and others (8,
17, 18,20, 25). After cell counts had been adjusted for the
expected platingefficiencies and surviving fractions, cells were
irradiated and then inoculated into 96-well, round-bottomed plates.
The media used was RPMI(GIBCO, Grand Island, NY) supplemented with
15% fetal calf serum,0.5% phytohemagglutinin (Wellcome Diagnostic,
United Kingdom),10 lU/ml recombinant human interleukin 2
(Boehringer Mannheim),100 Mg/ml penicillin, and 50 Mg/ml
gentamicin. One thousand lethallyirradiated feeder cells (50 Gy)
were added to each well to give a finalvolume of 100 Mi-
After incubation for 15 days, 28 n\ of a 0.5-mg/ml solution of
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
dissolved inphosphate-buffered saline was added to each well. The
3-(4,5-dimeth-ylthiazol-2-yl)-2,5-diphenyltetrazolium bromide,
which is converted toan insoluble dark blue formazan salt in
metabolically active cells, wasused to visualize lymphocyte
colonies.
Irradiations. HDR irradiations were performed at room
temperature by using a li7Cs source with a dose rate of 455
cGy/min. Fibro
blasts were irradiated as confluent monolayers and lymphocytes
wereirradiated in suspension. LDR irradiations, for both
lymphocytes andfibroblasts, were carried out at 37°Cin a 5% CO2,
humidified chamber,using a 137Cssource with a dose rate of 2.85
cGy/min.
Data Analysis. Fibroblast survival cunes generated with HDR
irradiations were fitted by using a linear-quadratic model (S =
e~aD~"D2).
The following parameters were calculated: «,SF2, O10, and
D¡.Radiosensitivity parameters for lymphocytes were obtained by a
si
multaneous fit of the data from all 12 dilutions. Our analysis
usedmaximum-likelihood principles that were adapted from a
publishedmethod of direct analysis (26). The parameters «,SF2, Dw,
and D¡weredetermined by the same methods as used for
fibroblasts.
Analyses of variance were performed for all data from different
individuals and from repeated measurements from the same
individuals.The variances for repeated measurements were pooled and
considered
Table 2 Sources of skin and blood samples used to generate
ßhroblastandlymphocyte cultures and measure radiosensitivity
LymphocytesRadiotherapy
patients beforetreatmentRadiotherapypatients with
severereactionsSkin
specimens frommastectomyNormalvolunteersTotalSuccessful
primaryculturesCompletedassaysSuccess
rate214833332988%Fibroblasts214631303097%
Table 3 Variance analysis for fibrohlast and lymphocyte SF2
after high- andlow-dose-rate irradiation for all cell strains and
repeated measurements
All P values showed the difference in variance to be highly
significant."
CelltypeFibroblastFibroblast''FibroblastFibroblast''DoserateHDRHDRLDRLDRn30272724m22»2215'15Varianceratio7.35.49.74.9P0.0000410.000340.0000580.0024OriginalCV(%)31.1625.7031.0722.34AdjustedCV(%)28.9523.2129.4218.14
Lymphocyte HDR 29 6 8.1 0.014 32.70 30.61" The adjusted CV is
derived from the original CV of all cell strains after
adjusting for the variance due to technical error in repeated
measurements, n.number of cell strains analyzed: m, number of
repeated measurements.
* Twenty-two repeat measurements performed in four cell
strains.' Analysis performed excluding three cell strains that
exhibited in vitro senes
cence.rfFifteen repeat measurements performed in two cell
strains.
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IN VITRO NORMAL CELL RADIOSENSITIVITY
to represent the reproducibility or experimental variation. The
ratio ofthe variance of all individuals to the pooled variance
would be 1 if allvariations between individuals were due only to
experimental variation.An F statistic was used to refute the null
hypothesis of equal variance.The adjusted CV was derived from the
variance that resulted aftersubtracting the pooled variance from
that obtained in all individuals.
RESULTS
Data Collection. From the 31 skin specimens collected, 30primary
fibroblast cultures were generated. Clonogenic survivalassays were
performed for all 30 cultures, using HDR and for27 cultures using
LDR irradiation.
Of the 33 lymphocyte cultures set up, 29 generated
évaluablelimiting dilution assay survival data after HDR
irradiation; theother 4 were not analyzable because of low
growth.
Fibroblast Radiosensitivity. Different sources of experimental
variability with regard to the culture and assay of fibroblastswere
investigated. While standardizing the fibroblast survivalassay, we
found that the normally linear relationship betweenthe number of
cells inoculated into a culture and the number ofresulting colonies
changed whenever the number of colonies ina culture exceeded 50-80,
above which fewer than the expectednumber of colonies appear. Fig.
1 illustrates this point from oneexperiment. This problem was
overcome by plating cells atseveral different densities, as shown
in Fig. 1, and using onlydata showing a linear relationship between
cell number andcolony formation. There was no systematic
relationship between control plating efficiencies and
radiosensitivity.
To estimate assay error, the variance in SF2 values frommultiple
assays performed in four cell strains was determined.The assay
variation was found to be significantly lower thanthat obtained in
all individuals (P = 0.000041). Table 3 showsthat the CV for SF2
for all individuals was 31.16%. After adjusting for technical
variation, the CV for differences amongindividuals was found to be
28.95%. The same analysis was alsoperformed by using LDR
irradiation in two fibroblast strains.The SF2 variance resulting
from repeat assays was also significantly lower than that obtained
in all individuals (P =0.000058). The adjusted CV was 29.42%,
whereas the originalCV was 31.07% (Table 3). Therefore, for both
HDR and LDRirradiations, differences among individuals are greater
than canbe accounted for by technical variation.
3000 6000 9000
Number of cells inoculated
Fig. 1. Comparison of the number of cells inoculated into a
100-mm culturedish with the number of fibroblast colonies formed.
Each dose point is representedby five different cell inoculum
sizes. As illustrated, the number of colonies decreased from that
expected when the number of cells increased, particularly
withlarger inoculum sizes. Only data that were linear with the
origin were selected forsurvival calculations.
flI os-
CV= 41%
0.5-,
CV= 21% CV= 22%
Fig. 2. Fibroblast radiosensitivity parameters (a, SF2, DIO, and
D,). The darkest columns represent three strains that exhibited
cell senescence. Diagonallystriped columns represent measurements
performed in fibroblast cultures derivedfrom surgical skin
specimens. Note that the SF2 distribution panel contains threemore
diagonally striped columns, which represent cultures in which we
measuredSF2 only.
Fig. 2 shows the survival results for all fibroblast strains,
aswell as the distributions for the low-dose (a, SF2) and
high-doseparameters (DÃŒO,DI) in rank order. The CVs were 41, 31,
21,and 22% for a, SF2, D10, and Z),, respectively (Table 4),
thusconfirming that the parameters associated with the
low-doseregion of the survival curve are the most useful for
identifyingindividual differences in radiosensitivity.
In our study, the use of LDR irradiation did not increasethe
observed radiosensitivity differences among individuals(Table
4).
Lymphocyte Radiosensitivity. Potential sources of experimental
variability were also examined for lymphocyte assays.The variance
due to technical and sampling errors in measuringSF2 was found to
be significantly lower than that observed in allindividuals (P =
0.014). The adjusted CV was 30.61%, whereasthe nonadjusted CV was
32.70% (Table 3). There was no systematic relationship between
control plating efficiencies andradiosensitivity.
a, SF2, DIO, and D¡all showed notable variation
amongindividuals (Fig. 3). As with the fibroblast assays,
comparisonbetween LDR and HDR assays in our study showed no
advantage for LDR in amplifying the differences among
individuals(Table 4).
Fibroblast versus Lymphocyte Radiosensitivity. As mentioned
above, previously published reports (17, 18) have shownno
correlation between the radiosensitivity of resting lymphocytes and
cycling fibroblasts derived from the same individuals.In the
present study, we compared the radiosensitivity of bothlymphocytes
and fibroblasts, in the G0 phase of the cell cycle.Of the 25
lymphocyte and fibroblast cultures, 16 were usable forthis
comparison. Comparison of the two cell types was made byusing both
SF2 and a. Fig. 4 shows a random association between the
radiosensitivity of the two cell types (r = 0.37,P = 0.152, and r =
0.30, P = 0.258 for SF2 and a, respectively).
DISCUSSION
The main purpose of this study was to investigate the degreeto
which normal cell radiosensitivity varies among individuals.The
existence of normal cell radiosensitivity variation from
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IN VITRO NORMAL TELL RADIOSENS1TIVITY
Table 4 Mean, SD, and CV for four radiosensitivity parameters(a,
SF2, BIO, and D¡,respectively)
LymphocytesParameter"aSF2Dio0iHDR
LDRHDR
LDRHDR
LDRHDR
LDRMean
±SD0.373
±0.2410.388 ±0.2240.374
±0.1230.401±0.1113.965
±1.0164.684 ±1.3076.786±
1.9448.780 ±3.131CV
(%)68
58332731283527FibroblastsMean
±SD0.573
±0.2260.507 +0.1360.291
±0.1020.350 ±0.1133.551
±0.9124.707 ±1.1286.125±
1.4299.392 ±2.428CV
(%)412731
3121
2422
23" All parameters were calculated by using a linear-quadratic
fit for both lympho
cytes and fibroblasts after HDR and LDR irradiations.
individual to individual may indicate that genetic diversity
playsa role in determining cellular radiosensitivity. In addition,
itwas our goal to compare the radiosensitivity of two normal
celltypes (e.g., fibroblasts and lymphocytes) in the same
individual.
The most important result of this study is the statistical
evidence for interindividual variation in lymphocyte and
fibro-blast radiosensitivity. The actual differences among
individualswere found to be significantly greater than variation
due totechnical or sampling errors. This is reflected by the
adjustedcoefficients of variation which were calculated after
analyzingthe variance of the whole group and the variance of the
repeatedmeasurements in several cell strains (Table 3). These
observations are in general agreement with those of most of the
published reports in which CVs ranged from 14 to 41% for
differentradiosensitivity end points (D0, D10, SF2) (Table 1). On
theother hand, Kushiro et al. (18) reported that normal
fibroblastand lymphocyte radiosensitivity showed no significant
interindividual variation in D10, D50, or D90. However, the CV of
theSF2 values listed in one of their publications (27) is 20%,
whichis comparable to what was found by others. Another
significantdifference between our study and others is that the
majority ofour study population was composed of cancer patients, a
groupthat may not represent the general population in this
regard.
A surprising observation in this study was that LDR irradiation
did not amplify the differences in the low-dose parametersof the
survival curves, as reported by others (13, 21). A
possibleexplanation may be that our LDR (2.85 cGy/min) is
higherthan what was used by others. Therefore, it is likely that
complete repair was not occurring during our LDR treatments.
Thiswas confirmed by allowing 24 h for the recovery of any
remaining potentially lethal damage after LDR irradiations, or
bytreating cells with dose rates of less than 1 cGy/min. In
thesecases, ßwas near zero and the «value was lower.4- 5
A lack of correlation between the radiosensitivity of
G0-phaseresting lymphocytes and plateau-phase fibroblasts from
thesame individuals underscores the importance of
tissue-specificeffects on the expression of radiosensitivity. Even
though wemeasured the radiosensitivity of cells in the same phase
of thecell cycle, our results are similar to those obtained by
others, inwhich resting lymphocytes were compared with cycling
fibroblasts (17, 18). This could be explained by the assumption
thata large number of genes influence radiosensitivity (28) and
thatsome of them exhibit differential expression in different
celltypes. Some of these genes may have an essential role in the
celland may therefore be expressed in all cell types. In this case,
any
4 F. B. Geara el al., unpublished observations.5 E. P. Malaise
et al., unpublished observations.
dysfunction in these genes would result in increased
radiosensitivity in virtually all cell types and tissues such as
that observed in individuals with homozygous AT genes. The role
thatdifferentiation plays in determining radiosensitivity,
however,will not be clearly understood until a number of such genes
havebeen identified and their expression studied in different
celltypes.
Cell-specific differences in radiosensitivity may also be
attributed to the difference in ratios of lymphocyte subtypes in
individuals. Blood contains a heterogeneous cell population,
especially with regard to the proportions of lymphocyte
subtypes.The notion of subset influence on radiosensitivity is
supportedby a recent report by Uckun et al. (29), showing that
CD3surface antigen expression is associated with cellular
radiore-sistance in some types of malignant T-lineage
lymphoblasticcells. Yet another possible reason could be the
potentially variable expression of programmed cell death by
different subsetsof T-lymphocytes. However, Nakamura et al. (30)
reported thatlymphocytes expressing the surface antigens CD4 or
CDSshowed no difference in their radiosensitivities. Their
studygroup, however, was composed of only normal individuals;
ingroups like ours, made up of cancer patients, large shifts
inlymphocyte-subtype ratios are possible.
Another potential source of variability in fibroblast
measurement is the role of cell senescence in radiosensitivity. All
cultures that became senescent exhibited increased
radiosensitivity. The development of in vitro senescence is highly
variable.
CV= 68% 0.5-
ÕÕra
B
3-
O
CV= 35%
Fig. 3. Lymphocyte radiosensitivity parameter (
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/A VITRO NORMAL CELL RADIOSENSITIVITY
unpredictable, and independent of plating efficiency, and
variesfrom one cell strain to another (31). Morphologically
senescentcells become larger with increasing filopodia density.
Theirgrowth rate decreases and plateau phase is reached at lower
celldensities, with open spaces between cells. Because of this
association between in vitro senescence and increased
radiosensitiv-ity, we performed an analysis excluding data derived
from thethree fibroblast cell strains that exhibited in vitro
senescence(Table 3). Little et al. reported no relationship between
fibroblast culture passage number and radiosensitivity (19), and
ourresults agree with their findings only until morphologically
senescent cells begin to appear.
In conclusion, it appears from this study that the
radiosensitivity of normal cells varies among individuals and that
thesedifferences are greater than can be accounted for by
samplingand methodology errors. These differences are likely due
tovariation in one or more genes that affect radiosensitivity.
However, differences among individuals in the sensitivity of one
celltype do not predict what will be found in other cell types.
Weassume that this means that differential gene expression
resultsin cell and tissue types with different arrays of active
genes thatinfluence radiosensitivity.
REFERENCES
1. Cleaver, J. E. How many human genetic disorders affect
cellular radiosensitivity? Cancer Cells (Cold Spring Harbor), /:
108-110, 1989.
2. Little, J. B., Nichols, W. W., Trailo, P., Nagasawa, H., and
Strong, L. C.Radiation sensitivity of cell strains from families
with genetic disorders predisposing to radiation-induced cancer.
Cancer Res., 49: 4705-4714, 1989.
3. Little. J. B., and Nove, J. Sensitivity of human diploid
fibroblast cell strainsfrom various genetic disorders to acute and
protracted radiation exposure.Radiât.Res., 123: 87-92. 1990.
4. Peters, L. J. Regaud Lecture: inherent radiosensitivity of
tumor and normaltissue cells as a predictor of human tumor
response. Radiother. Oncol., 17:177-190, 1990.
5. Abadir. k . and Hakami, N. Ataxia telangiectasia with cancer.
An Indicationfor reduced radiotherapy and chemotherapy doses. Br.
J. Radio!., 56: 343-345, 1983.
6. Arieti, C. F., and Harcourt, S. A. Survey of radiosensitivity
in a variety ofhuman cell strains. Cancer Res., 40: 926-932,
1980.
7. Blocher. I).. Sigut, D.. and Hannan, M. A. Fibroblasts from
ataxia telangiectasia (AT) and AT hétérozygotesshow an enhanced
level of residual DNAdouble-strand breaks after low dose-rate
^-irradiation as assayed by pulsedfield gel electrophoresis. Int.
J. Radiât.Biol. Relat. Stud. Phys. Chem. Med..60:791-802,
1991.
8. Cole, J., Arieti, C. F.. Green, M. H. L., Harcourt, S. A.,
Priestley, A.,Henderson, L., Cole, H., James, S. E., and Richmond,
F. Comparative human cellular radiosensitivity. II. The survival
following gamma-irradiation ofT-lymphocytes, T-lymphocyte lines,
lymphoblastoid cell-lines and fibroblastsfrom normal donors, from
ataxia telangiectasia patients, and ataxia telangiectasia
hétérozygotes.Int. J. Radiât.Biol. Relat. Stud. Phys. Chem.
Med.,54:929-943, 1988.
9. Hart, R. M.. Kilmer, B. F., Evans, R. G., and Park, C. H.
Radiotherapeuticmanagement of medulloblastoma in a pediatrie
patient with telangiectasia.Int. J. Radiât.Oncol. Biol. Phys., 13:
1237-1240, 1987.
10. Swift, M., Morrei!, D., Massey, R. B., and Chase, C. L.
Incidence of cancerin 161 families affected by
ataxia-telangiectasia. N. Engl. J. Med., 325:1831-1836, 1991.
11. Turesson, I. Individual variation and dose dependency in the
progression rate
of skin telangiectasia. Int. J. Radiât.Oncol. Biol. Phys., 19:
1569-1574,1990.
12. Peters, L. J. Significance of genetic variability in
radiosensitivity in clinicalradiotherapy. J. Jpn. Soc. Ther.
Radiol. Oncol., 2: 247-253, 1990.
13. Weeks, D. E., Paterson, M. C., Lange, K., Andrais, B.,
Davis, R. C., Yoder,F., and Gatti, R. A. Chronic y radiosensitivity
as an in vitro assay for hétérozygoteidentification of ataxia
telangiectasia. Radiât.Res., ¡28:90-99,1991.
14. Deschavanne, P. J., Debieu, D., Fértil,B., and Malaise, E.
P. Réévaluationofin vitro radiosensitivity of human fibroblasts
of different genetic origins. Int.J. Radiât.Biol. Relat. Stud.
Phys. Chem. Med., 50: 279-293, 1986.
15. Ban, S., Setlow, R. B., Bender, M. A., Ezaki, H., Hiroaka,
T.. Yamane, M.,Nishiki, M., Dohi, K., Awa, A. A., Miller, R. C.,
Parry, D. M., Mulvihill, J.J., and Heche. G. W. Radiosensitivity of
skin fibroblasts from atomic bombsurvivors with and without breast
cancer. Cancer Res., 50:4050-4055, 1990.
16. Cox, R., and Masson, W. K. Radiosensitivity in cultured
human fibroblasts.Int. J. Radial. Biol. Relat. Stud. Phys. Chem.
Med., 38: 575-576, 1980.
17. Green, M. H. L., Arlett, C. F., Cole, J., Harcourt, S. A.,
Priestley, A., Waugh,A. P. W., Stephens, G., Beare, D. M., Brown,
N. A. P., and Shun-shin, G. A.Comparative human cellular
radiosensitivity. III. Gamma-radiation survivalof cultured skin
fibroblasts and resting T-lymphocytes from the peripheralblood of
the same individual. Int. J. Radiât.Biol. Relat. Stud. Phys.
Chem.Med., 59: 749-765, 1991.
18. Kushiro, J. I., Nakamura, N., Kyoizumi, S., Nishiki, M.,
Dohi, K., andAkiyama, M. Absence of correlations between
radiosensitivities of humanT-lymphocytes in GO and skin fibroblasts
in log phase. Radiât.Res., /_.'.326-332, 1990.
19. Little, J. B., Nove, J., and Strong, L. C. Survival of human
diploid skinfibroblasts from normal individuals after
X-irradiation. Int. J. Radiât.Biol.Relat. Stud. Phys. Chem. Med.,
54: 899-910, 1988.
20. Nakamura, N., Sposto, R., Kushiro, J. I., and Akiyama, M. Is
interindividualvariation of cellular radiosensitivity real or
artificial? Radiât.Res., 125:326-330, 1990.
21. Gentner, N. E., Morrison, D. P., and Myers, D. K. Impact on
radiogeniccancer risk of persons exhibiting abnormal sensitivity to
ionizing radiation.Health Phys., 55: 415-425, 1988.
22. Steel, G. G., Down, J. D., Peacock, J. H., and Stephens, T.
C. Dose rateeffects and the repair of radiation damage. Radiother.
Oncol., 5: 321-331,1986.
23. Steel, G. G., Deacon, J. M., Duchesne. G. M., Horwich, A.,
Kelland, L. R.,and Peacock, J. H. The dose rate effect in human
tumor cells. Radiother.Oncol., 9:299-310, 1987.
24. Trainor, K. J., and Morley, A. A. Cloning of lymphocytes
from whole bloodby limiting dilution. J. Immunol. Methods, 65:
369-372, 1983.
25. Waugh, A. P. W., Beare, D. M., Arlett. C. F., Green, M. H.
L., and Cole. J.Comparative human cellular radiosensitivity. IV.
The increased sensitivity ofhuman neonatal cord blood lymphocytes
to -»-irradiationcompared withlymphocytes from children and
adults. Int. J. Radiât.Biol. Relat. Stud. Phys.Chem. Med., 59:
767-776, 1991.
26. Thames, H. D., Roseli, M. E., Tucker. S. L., Ang, K. K.,
Fisher, D. R., andTravis, E. L. Direct analysis of quanta!
radiation response data. Int. J. Radial.Biol. Relat. Stud. Phys.
Chem. Med., 49: 999-1009, 1986.
27. Kushiro, J. I., Nakamura, N., Kyoizumi, S., Nishiki, M.,
Dohi. K., andAkiyama, M. Absence of correlations between
radiosensitivities of humanT-lymphocytes in G0 and skin fibroblasts
in log phase. Radiation EffectsResearch Foundation, Japan.
Technical Report RERF TR 17-89, 1989.
28. Thacker, J., and Wilkinson, R. E. The genetic basis of
resistance to ionizingradiation damage in cultured mammalian cells.
Mutât.Res., 254: 135-142,1991.
29. Uckun, F. M., Ramsay, N. K. C., Haake. R., Kersey, J. H.,
and Song. C. W.Immunophenotype-radiation sensitivity associations
in T-lineage acute Kmphoblastic leukemia (ALL). Int. J.
Radiât.Oncol. Biol. Phys., 21:149. 1991.
30. Nakamura, N., Kusunoki, Y., and Akiyama, M. Radiosensitivity
of CD4 andCDS positive human T lymphocytes by an in vitro colony
formation assay.Radiation Effects Research Foundation. Japan.
Technical Report RERF TR16-89, 1989.
31. Martin, G. M., Curtis, A. S., and Epstein, C. J. Replicative
life-span ofcultivated human cells. Lab. Invest., 23: 86-92.
1970.
6352
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1992;52:6348-6352. Cancer Res Fady B. Geara, Lester J. Peters,
K. Kian Ang, et al. Lymphocytes after High- and Low-Dose-Rate
IrradiationIntrinsic Radiosensitivity of Normal Human Fibroblasts
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