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The Egyptian Journal of Hospital Medicine (April 2012) Vol., 47: 176 – 189
176
Gene polymorphisms of the DNA Repairing Genes APE1 and XRCC1 among
Smoking Lung Cancer Egyptians Rezk Ahmed Abd-ellateef Elbaz, Salim Abd-elhady Habib, Maha Ebraheem Esmael Ebraheem, Gamal Kamel EL-
Ebidy, Lamiaa Mohamed Mahmoud Ramadan and Ahmed Settin. Genetic unit, Children Hospital; Mansoura University, Biochemistry department, Faculty of science, Domiatta;
Mansoura University, Oncology Center; Mansoura University, Gastroenterology Center; Mansoura University,
Ministry of health Laboratories, Mansoura
Abstract
Lung cancer is the leading cause of cancer-related mortality worldwide and is thus a major public health
problem. DNA base damage or losses caused by endogenous and exogenous agents occur constantly at a
high frequency in human cells. The removal or repair of damaged bases is an important mechanism in
protecting the integrity of the genome.
APE1 (Apurinic/Apyrimidinic Endonuclease 1) and XRCC1 (X-ray cross-complementing group1) are
DNA repair proteins that play important roles in the base excision repair (BER) pathway. The focus of
this work is limited to the association between polymorphisms in the DNA repair genes, (APE1
Asp148Glu (2197 T→G) and XRCC1 Arg399Gln (28152 G→A) genotypes), cigarette smoking and lung
cancer. This study has included 131 cases affected with lung cancers include; 33cases with small cell
carcinoma (25.2%) and 98 cases with non-small cell carcinoma (74.8%).
They were recruited from oncology Center, Mansoura University, Egypt; in the period between April
2008 to March 2010. For comparison, a negative control group including 150 healthy individuals
randomly selected from blood donors. Controls were selected by random sampling cancer-free individuals
without a past history of cancer, who visited Mansoura University hospitals and provided peripheral
blood between April 2008 and March 2010.
DNA was extracted from the whole peripheral blood using generation DNA purification capture column
kit (Gentra system, USA) and genotyping for APE1 Glu148Asp and XRCC1 Arg399Gln polymorphisms
was performed by a PCR--CTPP (PCR with confronting two-pair primers) method.
The collected data were organized and statistically analyzed using SPSS statistical computer package
version 10 software. we observed that, There were no significant differences in the frequencies of the
APE1 Asp148Glu (2197 T→G) polymorphism of all genotypes and alleles in all lung cancer cases
compared to all healthy controls. Also, there were no significant differences in the frequencies of all
genotypes and alleles in lung cancer cases compared to controls of all smoking status. While, in former
smoking individuals; significant difference in the frequency of the mutant GG genotype in lung cancer
cases compared to controls (p-value=0.003).
We observed that, There were no significant differences in the frequencies of the XRCC1 Arg399Gln
(28152 G→A) polymorphism of all genotypes and alleles in all lung cancer cases compared to all healthy
controls. Also, there were no significant differences in the frequencies of all genotypes and alleles in lung
cancer cases compared to controls of all smoking status. While, in never smoking individuals; significant
difference in the frequency of the mutant AA genotype in lung cancer cases compared to controls
(p-value=0.0004).
Keywords; Gene, polymorphisms, DNA Repairing Genes, APE1, XRCC1, Lung Cancer.
Gene polymorphisms of the DNA Repairing Genes APE1 and XRCC1…..
177
Introduction
Lung cancer is the leading cause of cancer-
related mortality worldwide (Edwards et al.,
2005) and is thus a major public health problem.
DNA base damage or losses caused by
endogenous and exogenous agents occur
constantly at a high frequency in human cells.
The removal or repair of damaged bases is an
important mechanism in protecting the integrity
of the genome. Oxidized DNA bases and
alkylated DNA bases can be removed and
replaced with the correct ones in a localized
burst of DNA synthesis by DNA base excision
repair pathway, which mobilizes an array of
proteins (Fortini et al., 2003). These proteins
play an important role in repairing immediate
DNA base damage caused by exposure to
environmental agents and endogenous reactive
oxygen species (ROS) as well as alkylating
species (Christmann et al., 2003).
Defects in DNA repair can give rise to
hypersensitivity to carcinogens and the
accumulation of DNA lesions in the genome,
and lead to the development of cancer. Cigarette
smoke contains many carcinogens and reactive
oxygen species that can induce various types of
DNA damage (Hecht, 2002). Although cigarette
smoking is a major risk factor in the
development of lung cancer, only 10% to 15%
of all smokers develop lung cancer, suggesting
that variation in individual susceptibility to
tumorigenesis of lung cancer (Mattson et al.,
1987; Shields & Harris, 2000 and Shields,
2002). Susceptibility differences may be
inherited in genes encoding for the metabolism
of carcinogens or DNA repair molecules, which
are essential in protecting the genomic integrity
of the cells (Caporaso et al.,1991; Goode et al.,
2002 and Spitz et al., 2003).
A single nucleotide polymorphism (SNP) is a
common genetic variation. Some SNPs may
have a functional impact on health outcome and
contribute to the overall population risk of
cancer. SNPs in DNA repair genes have been
suggested to be risk factors for lung cancer but
the current available results have been
inconsistent (Kiyohara et al., 2002).
One of the DNA repair pathways is the DNA
base excision repair pathway, which repairs the
DNA damage caused by oxidation and
alkylation and thus protects cells against the
toxic effects of endogenous and exogenous
agents (Hoeijmakers, 2001 and Fleck & Nielsen,
2004). DNA damage induced by reactive oxygen
species (ROS) may be repaired by the base
excision repair (BER) pathway (Mandal et al.,
2012).
Specifically, the damaged bases of purine and
pyrimidine are recognized and excised by
specific DNA glycosylases, leaving abasic sites.
Apurinic/ apyrimidinic endonuclease (APE) then
incise the DNA 5'-to the abasic sites; further
repair proceeds to short-patch (when the gap is
only one nucleotide) or long-patch (when the
gap is two or more nucleotides) sub-pathways of
base excision repair (Krokan et al., 2000). The
major human APE, APE1 (also known as APE,
APEX, HAP1, and REF-1), plays a central role
in the base excision repair pathway. APE1 is
also known as a transcriptional co-activator for
numerous transcription factors involved in
cancer development (Bhakat et al., 2009) and is
considered as a promising tool for anticancer
Rezk Elbaz et al
178
therapy (Tell et al., 2010). As a member of APE,
it initiates repair of apurinic/apyrimidinic sites in
DNA produced either spontaneously
hydrolyzing the 5'-phosphodiester bond of the
apurinic/apyrimidinic site or after enzymatic
removal of damaged bases. The repair activity of
APE1 serves to protect the cell from the
apurinic/apyrimidinic sites that can accumulate
in DNA via endogenous and exogenous sources.
In addition to APE activity, it can also act as a
3'-phosphodiesterase, initiating repair of DNA
strands breaks with 3'-blocking damage, which
are produced either directly by reactive oxygen
species or indirectly through the enzymatic
removal of damaged bases (Izumi et al., 2000
and Fortini et al., 2003).
XRCC1, one of more than twenty genes that
participate in the base excision repair pathway,
has multiple roles in repairing DNA base
damage and single-strand DNA breaks
(Thompson & West, 2000). Inconsistent results
have been reported regarding the associations
between the Arg399Gln (exon 10)
polymorphism of XRCC1 and either functional
significance or the risk of tobacco associated
cancers (Ratnasinghe et al., 2001; Butkiewicz
et al., 2001; David-Beabes & London, 2001
and Park et al., 2002). We studied the
association between genetic variation of DNA
base excision repair pathway genes (APE1 and
XRCC1), smoking and lung cancer.
Material and methods
Studied patients:
This study has included 131 cases affected
with lung cancers include; 33cases with small
cell carcinoma (25.2%) and 98 cases with non-
small cell carcinoma (74.8%). They were
recruited from oncology Center, Mansoura
University, Egypt; in the period between April
2008 to March 2010.
For comparison, a negative control group
including 150 healthy individuals randomly
selected from blood donors. Controls were
selected by random sampling cancer-free
individuals without a past history of cancer,
who visited Mansoura University hospitals and
provided peripheral blood between April 2008
and March 2010. They were confirmed not to
have cancer by the hospital-based cancer
registry system by the end of 2010.
Genotyping procedure:
DNA was extracted from the whole peripheral
blood using generation DNA purification
capture column kit (Gentra system, USA) and
genotyping for APE1 Glu148Asp and XRCC1
Arg399Gln polymorphisms was performed by
a PCR-CTPP (PCR with confronting two-pair
primers) method (Hamajima et al., 2000).
For the APE1 Glu148Asp (2197 T to G)
polymorphism, extracted DNA was amplified
with the four primers by `Ampli Taq Gold'
(Perkin-Elmer, Foster City, CA); F1, 50-CCT
ACG GCA TAG GTG AGA CC-30; R1, 50-
TCC TGA TCA TGC TCC TCC-30; F2, 50-
TCT GTT TCA TTT CTA TAG GCG AT-30;
and R2, 50-GTC AAT TTC TTC ATG TGC
CA-30 . PCR conditions were 1-min
denaturation at 95_C followed by 30 cycles of
95_C for 1 min, 60_C for 1 min, and 72_C for 1
min, with a 5-min extension at 72_C. Primer
pairs F1 and R1 for the G allele (148Glu), F2
Gene polymorphisms of the DNA Repairing Genes APE1 and XRCC1…..
179
and R2 for the T allele (148Asp) produced allele-specific bands of 167- and 236-bp,
respectively, as well as a 360-bp common band.
For XRCC1 Arg399Gln (28152 G to A),
extracted DNA was amplified with the four
primers by `Ampli Taq Gold' (Perkin-Elmer,
Foster City, CA); F1, 50-TCC CTG CGC CGC
TGC AGT TTC T-30; R1, 50-TGG CGT GTG
AGG CCT TAC CTC C-30; F2, 50-TCG GCG
GCT GCC CTC CCA-30; and R2, 50-AGC
CCT CTG TGA CCT CCC AGG C-30. PCR
conditions were 1-min denaturation at 94_C
followed by 30 cycles of 94_C for 1 min, 59_C
for 1 min, and 72_C for 1 min, with a 10-min
extension at 72_C. Primer pairs F1 and R1 for
the G allele (399Arg) and F2 and R2 for the A
allele (399Gln) produced allele-specific bands of
447- and 222-bp, respectively, as well as a 630-
bp common band.
Statistical analysis:
The collected data were organized and
statistically analyzed using SPSS statistical
computer package version 10 software.
Statistical measurements included:
1- : Descriptive data included mean
and standard deviation of variables of cases.
2- Genotype frequency and percentage frequency
by counting subjects with certain genotype
polymorphisms and dividing by the number of
total studied subjects either cases or controls.
3- Allele frequency and percentage frequency by
counting subjects with certain allele
polymorphisms (2 for each subject) and dividing
by the number of studied chromosomes.
Results
The Descriptive data of the studied lung cancer
cases and healthy controls are shown in table
(1). The average age of the lung cancer patients
was 55.2 ± 10.5 while that of the control group
was 51.5 ± 11.5
Table (1): Descriptive data of the studied lung cancer cases and healthy controls.
Cases n(%) Controls n (%)
Total: 131 150
Sex:
Male 92 (70.2) 140 (93)
Female 39 (29.8) 10 (7)
Age at diagnosis(years):
<=49 years 34 (26) 60 (40)
50-59 years 47 (35.9) 48 (32)
>=60 years 50 (38.1) 42 (28)
Mean age + SD 55.2 + 10.5 51.5 + 11.5
Diagnosis:
Small cell carcinoma 33 (25.2) -
Non-small cell carcinoma 98 (74.8) -
Smoking status:
Never smokers 37 (28.2) 8 (5.3)
Former smokers 11 (8.4) 15 (10)
Current smokers 83 (63.4) 127 (84.7)
n= number of studied cases, (%) = percentage of studied cases.
The genotype and allele distributions of the APE1 Asp148Glu (2197 T→G) polymorphism in lung cancer cases
and controls were shown in table (2). Between cases and control groups displayed no significant differences in the
frequencies of all genotypes and alleles (p-value>0.05).
Rezk Elbaz et al
180
Table (2): Frequencies of APE1 Asp148Glu (2197 T→G) genotypes and allelic polymorphisms in
lung cancer cases compared to healthy controls.
Total
APE genotypes Individual Alleles
Asp/Glu
(TG)
N (%)
Asp/Asp
(TT)
N (%)
Glu/Glu
(GG)
N (%)
T
N (%)
G
N (%)
Controls 37 (24.7) 92(61.3) 21 (14.0) 221(73.65) 79 (26.35)
Cases 48 (36.6) 68(51.9) 15 (11.5) 184 (70.2) 78 (29.8)
p -value 0.129 0.377 0.621 0.773 0.6452
N= number; %= percentage; *p=< 0. 05 significant;
**p=<0.001 highly significant.
There were no significant differences in the frequencies of all genotypes and alleles in lung cancer cases
compared to controls of all smoking status. While, in former smoking individuals; significant difference in
the frequency of the mutant GG genotype in lung cancer cases compared to controls (p-value=0.003) as
shown in table (3).
Table (3): Frequencies of APE1 Asp148Glu (2197 T→G) genotypes and allelic polymorphisms
in lung cancer cases compared to healthy controls in the smoking status.
Smoking status
APE genotypes Individual Alleles
Asp/Glu
(TG)
N (%)
Asp/Asp
(TT)
N (%)
Glu/Glu
(GG)
N (%)
T
N (%)
G
N (%)
Never Controls 2 (25) 5 (62.5) 1 (12.5) 12(75) 4(25)
Cases 14(37.8) 20(54.1) 3 (8.1) 54(73) 20(27)
p -value 0.106 0.437 0.332 0.869 0.781
Former Controls 5 (33.3) 6 (40) 4 (26.7) 17(56.7) 13(43.3)
Cases 5 (45.5) 5 (45.5) 1 (9) 15(68.2) 7(31.8)
p -value 0.169 0.552 0.003* 0.303 0.184
Current Controls 30(23.6) 81(63.8) 16(12.6) 192(75.6) 62(24.4)
Cases 29(34.9) 43(51.8) 11(13.3) 115(69.3) 51(30.7)
p -value 0.139 0.264 0.890 0.601 0.396
N= number; %= percentage; *p=< 0. 05 significant;
**p=<0.001 highly significant.
The Egyptian Journal of Hospital Medicine (April 2012) Vol., 47: 176 – 189
181
Figure (1): PCR amplification for APE1 Asp148Glu (2197 T→G) polymorphisms using PCR-CTPP
method; lane M: DNA size marker, lanes 1, 3, 5:
Asp/Asp (TT) genotype lanes 4, 7: Asp/Glu (TG)
genotype and lanes 2, 6: Glu/Glu (GG) genotype.
Figure (2): PCR amplification for XRCC1 Arg399Gln (28152 G→A) polymorphisms using PCR-CTPP
method; lane M: DNA size marker, lanes 2, 6, 7:
Arg/Arg (GG) genotype, lanes 1, 5: Arg/Gln (GA)
genotype and lanes 3, 4: Gln/Gln (AA) genotype.
Table (4): Frequencies of XRCC1 Arg399Gln (28152 G→A) genotypes and allelic polymorphisms in
lung cancer cases compared to healthy controls.
Total
XRCC1 polymorphism Individual Alleles
Arg/Gln (GA)
N (%)
Arg/Arg
(GG)
N (%)
Gln/Gln
(AA)
N (%)
G
N (%)
A
N (%)
Controls 139 (92.7) 7 (4.7) 4 (2.7) 153 (51) 147 (49)
Cases 122 (93.1) 6 (4.6) 3 (2.3) 134 (51.1) 128 (48.9)
p -value 0.975 0.975 0.858 1 1
N= number; %= percentage; *p=< 0. 05 significant;
**p=<0.001 highly significant.
There were no significant differences in the frequencies of all genotypes and alleles in all lung cancer cases
compared to all healthy controls as shown in table (4).
Table (5): Frequencies of XRCC1 Arg399Gln (28152 G→A) genotypes and allelic polymorphisms in
lung cancer cases compared to healthy controls in the smoking status.
Smoking status
XRCC1 genotypes Individual Alleles
Arg/Gln (GA)
N (%)
Arg/Arg
(GG)
N (%)
Gln/Gln
(AA)
N (%)
G
N (%)
A
N (%)
Never Controls 7 (87.5) 0 (0) 1 (12.5) 7(43.75) 9(56.25)
Cases 36(97.3) 1 (2.7) 0 (0) 38(51.4) 36(48.6)
p -value 0.471 0.100 0.0004** 0.433 0.455
Former Controls 15 (100) 0 (0) 0 (0) 15(50) 15(50)
Cases 11 (100) 0 (0) 0 (0) 11(50) 11(50)
p -value 1 1 1 1 1
Current Controls 117(92.1) 7 (5.5) 3(2.4) 131(51.6) 123(48.4)
Cases 75 (90.4) 5 (6) 3 (3.6) 85(51.2) 81(48.8)
p -value 0.899 0.882 0.624 0.964 0.964
Rezk Elbaz et al
182
N= number; %= percentage; *p=< 0. 05 significant;
**p=<0.001 highly significant.
In table (5) there were no significant differences in the frequencies of all genotypes and alleles in lung cancer
cases compared to controls of all smoking status. While, highly significant differences were found in the frequency
of the mutant AA genotype, in never smoking lung cancer cases compared to controls (p-value=0.0004).
Discussion
DNA repair systems act to maintain genomic
integrity in the face of environmental insults,
cumulative effects of age, and general DNA
replication errors. Tobacco smoke contains an
array of potent chemical carcinogens and
reactive oxygen species that may produce
DNA bulky adducts, cross-links, oxidative or
base DNA damage, and DNA strand breaks.
Among the several major DNA repair
pathways that operate on specific types of
damaged DNA by cigarette smoking, base-
excision repair (BER) is involved in repair of
DNA base damage and single strand
breaks(Berwick and Vineis, 2000). APE1 is an
essential enzyme in the base excision repair
pathway, which is the primary mechanism for
the repair of endogenous DNA damage
resulting from cellular metabolisms, including
those resulting from reactive oxygen species,
methylation, deamination, and hydroxylation
(Hoeijmakers, 2001). It is estimated that 2,000
to 10,000 apurinic/apyrimidinic sites arise per
day in mammalian cell grown under normal
physiologic conditions (Lindahl, 1993).
XRCC1, one of more than twenty genes that
participate in the base excision repair pathway,
has multiple roles in repairing DNA base
damage and single-strand DNA breaks
(Thompson and West,2000).
Inconsistent results have been reported
regarding the associations between the
Arg399Gln (exon 10) polymorphism of
XRCC1 and either functional significance or
the risk of tobacco associated cancers (Park et
al., 2002). XRCC1 is thought to play a role in
the multistep base excision repair pathway
where “non-bulky” base adducts produced by
methylation, oxidation, reduction, or
fragmentation of bases by ionizing radiation or
oxidative damage are removed (Yu et al.,
1999). Although the specific function of
XRCC1 has not been identified, it is believed
that XRCC1 complexes with DNA ligase III
via a BRCT domain in its COOH terminus and
with DNA polymerase b in its NH2 terminus
to repair gaps left during base excision repair
(Lunn et al., 1999).
In the current study, the genotype and allele
distributions of the APE1 Asp148Glu (2197
T→G) polymorphism in lung cancer cases and
controls were shown in table (2). Between
cases and control groups displayed no
significant differences in the frequencies of all
genotypes and alleles (p-value>0.05). These
results were in consistent with that of
Taiwanese (Yen et al., 2009); Japanese
populations (Ito et al., 2004); African-
Americans populations (Chang et al., 2009);
Chinese populations (Shen et al., 2005);
Taiwanese populations (Lo et al., 2009);
Latinos populations (Chang et al., 2009);
Caucasian populations (Popanda et al., 2004);
The Egyptian Journal of Hospital Medicine (April 2012) Vol., 47: 176 – 189
183
and Caucasian populations (Zienolddiny et al.,
2006).
In the present study, we found the frequency
of the mutant G allele (rare-allele) of the APE1
Asp148Glu (2197 T→G) polymorphism in the
Egyptian total lung cancer cases was (30%),
this result is consistent with that of Caucasians
populations (31%) (Zienolddiny et al., 2006).
However, the frequencies of the same allele
were reported in other studies on several
populations, as following, Latinos populations
(36%) (Chang et al., 2009); Afro-Americans
populations (39%) (Chang et al., 2009);
Taiwanese populations (39%) (Lo et al.,
2009); Caucasian populations (45%) (Popanda
et al., 2004); Chinese populations (49%) (Shen
et al., 2005) and Japanese populations (42%)
(Ito et al., 2004).
The frequency of the mutant G allele (rare-
allele) of the APE1 Asp148Glu (2197 T→G)
polymorphism in the Egyptian total healthy
controls was (26%), while, in Caucasians
populations was (37%) (Zienolddiny et al.,
2006); in Afro-Americans populations was
(38%) (Chang et al., 2009); in Taiwanese
populations was (39%) (Lo et al., 2009); in
Japanese populations was (39%) (Ito et al.,
2004 ); in Chinese populations was (40%)
(Shen et al., 2005); in Latinos populations was
(42%) (Chang et al., 2009) and in Caucasian
populations was (49%) (Popanda et al., 2004).
We found the frequency of the mutant GG
genotype (rare-alleles) of the APE1
Asp148Glu (2197 T→G) polymorphism in the
Egyptian total lung cancer cases was (11.5%),
this result is consistent with that of Latinos
populations (12.4%) (Chang et al., 2009) and
lower than that of Japanese populations (18%)
(Ito et al., 2004); Caucasian populations
(19.4%) (Popanda et al., 2004); Taiwanese
populations (16.32%) (Lo et al., 2009). Afro-
Americans populations (15.7%) (Chang et al.,
2009); Chinese populations (21.8%) (Shen et
al., 2005) and Caucasian populations (23.3%)
(Zienolddiny et al., 2006).
And the frequency of the mutant GG
genotype (rare-alleles) of the APE1
Asp148Glu (2197 T→G) polymorphism in the
Egyptian total healthy controls of this study
was (14%), which agree with that of Japanese
populations (14.3%) (Ito et al., 2004); Afro-
Americans populations (14.6%) (Chang et al.,
2009) and Chinese populations (13.3%) (Shen
et al., 2005); but lower than that of Taiwanese
populations (16.34%) (Lo et al., 2009);
Latinos populations (18.7%) (Chang et al.,
2009); Caucasian populations (23.2%)
(Popanda et al., 2004); and Caucasian
populations (29.5%) (Zienolddiny et al.,
2006).
Generally, the differences in allele or
genotype frequencies detected among these
studies might be due to ethnic variation,
heterogeneity of studied populations and
different sample sizes.
The present results were in consistent with
that of White Americans (Cote et al., 2009);
Afro-Americans (Cote et al., 2009); Chinese
populations (Ratnasinghe et al., 2001); Korean
populations (Park et al., 2002); Japanese
populations (Ito et al., 2004); Chinese
populations (Zhang et al., 2005); Caucasian
populations (Zhou et al., 2003); Chinese
populations (Chen et al., 2002); Caucasian
Rezk Elbaz et al
184
populations (Hung et al., 2005); Latinos
(Chang et al., 2009); Afro-Americans (Chang
et al., 2009); Chinese populations (Shen et al.,
2005); Caucasian populations (Popanda et al.,
2004) and Caucasian populations (Zienolddiny
et al., 2006).
The frequency of the mutant A allele rare-
allele XRCC1 Arg399Gln (28152 G→A)
polymorphism in the Egyptian total lung
cancer cases was (48.9%), however that of
Caucasian populations was (36.7%) (Popanda
et al., 2004); in White Americans was
(35.05%) (Cote et al., 2009); in Caucasian
populations was (35.75%) (Zhou et al., 2003);
in Caucasian populations was (35.6%) (Hung
et al., 2005); in Chinese populations was
(28.35%) (Zhang et al., 2005); in Afro-
Americans was (15.2%) (Cote et al., 2009); in
Chinese populations was (26.2%)
(Ratnasinghe et al., 2001); in Korean
populations was (28.35%) (Park et al., 2002);
in Japanese populations was (26.45%) (Ito et
al., 2004); in Latinos was (31.4%) (Chang et
al., 2009); in Chinese populations was (24.3%)
(Chen et al., 2002); in African-Americans was
(15.15%) (Chang et al., 2009); in Chinese
populations was (20.2%) (Shen et al., 2005)
and in Caucasian populations was (33.95%)
(Zienolddiny et al., 2006).
The frequency of the mutant A allele rare-
allele XRCC1 Arg399Gln (28152 G→A)
polymorphism in the Egyptian total healthy
controls was (49%). However, in Caucasian
populations was (38.75%) (Popanda et al.,
2004); in White Americans was (35.95%)
(Cote et al., 2009); in Black Americans was
(15.7%) (Cote et al., 2009); in Chinese
populations (24.55%) (Ratnasinghe et al.,
2001); in Korean populations was (22.2%)
(Park et al., 2002); in Japanese populations
was (24.6%) (Ito et al., 2004); in Chinese
populations was (27.9%) (Zhang et al., 2005);
in Caucasian populations was (33.5%) (Zhou
et al., 2003); in Chinese populations was
(24.75%) (Chen et al., 2002); in Caucasian
populations was (34.75%) (Hung et al., 2005);
in Latinos was (26.7%) (Chang et al., 2009); in
Afro-Americans was (13.7%) (Chang et al.,
2009); in Chinese populations was (26.05%)
(Shen et al., 2005) and in Caucasian
populations was (35.6%) (Zienolddiny et al.,
2006).
The frequency of the mutant AA genotype
(rare-alleles) of the XRCC1 Arg399Gln
(28152 G→A) polymorphism in the Egyptian
total lung cancer cases was (2.3%), this result
was consistent with that of Afro-Americans
(1.6%) (Chang et al., 2009) and that of
Chinese populations (3.4%) (Shen et al.,
2005); however, that of Korean populations
was (8.8%) (Park et al., 2002), which was
agree with that of Caucasian populations (9%)
(Zienolddiny et al., 2006)
The frequency of the mutant AA genotype
(rare-alleles) of the XRCC1 Arg399Gln
(28152 G→A) polymorphism in the Egyptian
total healthy controls was (2.7%), this result
was consistent with that of African-Americans
(2.1%) (Chang et al., 2009) and that of
Chinese populations (3.5%) (Shen et al.,
2005); while, that of Japanese populations
(5.8%) (Ito et al., 2004); that of Korean
populations was (4.4%) (Park et al., 2002),
which was agree with that of Black Americans
The Egyptian Journal of Hospital Medicine (April 2012) Vol., 47: 176 – 189
185
(4.1%) (Cote et al., 2009); that of Caucasian
populations was (13.1%) (Zienolddiny et al.,
2006), which was agree with that of Caucasian
populations (12.9%) (Hung et al., 2005); that
of Caucasian populations was (11.5%) (Zhou
et al., 2003), which was agree with that of
White Americans (11.3%) (Cote et al., 2009).
The differences in allele or genotype
frequencies detected among these studies
might be due to ethnic variation, heterogeneity
of studied populations and different sample
sizes.
The risk for lung cancer among smokers is
thought to increase with cumulative tobacco
exposure (Ruano-Ravina et al., 2003), and
genetic susceptibility to lung cancer may
depend on the level of exposure to tobacco
smoke (Nakachi et al., 1991 and Vineis, 1997).
Therefore, we examined further gene-
environment interaction between tobacco
smoke exposure and the polymorphisms of
APE1 and XRCC1.
When the subjects were divided into three
groups according to the smoking status, we
found that, the frequency of the mutant GG
genotype of the APE1 Asp148Glu (2197
T→G) polymorphism in the former smokers
had a statistically significant difference (p-
value=0.003) regarding decreased risk of lung
cancer, where the frequency of the lung cancer
cases was lower than that of the healthy
controls, while, current and never smokers did
not, table (3). While, in Japanese populations
the frequency of the mutant GG genotype of
the APE1 Asp148Glu (2197 T→G)
polymorphism in the current smokers had a
statistically significant difference (p-
value=0.044) regarding risk of lung cancer,
while, former and never smokers did not (Ito
et al., 2004); in Taiwanese populations the
frequency of the mutant GG genotype in the
heavy smokers had a statistically significant
difference (p-value=0.026) regarding
decreased risk of lung cancer, where the
frequency of the lung cancer cases was lower
than that of the healthy controls, while, never
and light smokers did not (Lo et al., 2009) and
Chinese populations the frequency of the
mutant GG genotype in the male heavy
smokers had a statistically highly significant
difference (p-value=0.0003) regarding highly
risk of lung cancer, while, male light smokers
did not (Shen et al., 2005).
On the other hand, the frequency of the
mutant AA genotype of the XRCC1
Arg399Gln (28152 G→A) polymorphism in
the never smokers had a statistically highly
significant difference (p-value=0.0004)
regarding highly decreased risk of lung cancer,
where the frequency of the lung cancer cases
was lower than that of the healthy controls,
while, current and former smokers did not,
table (5). While, there were no significant
differences in frequencies of the mutant AA
genotype of the XRCC1 Arg399Gln (28152
G→A) polymorphism of all smoking status in
Caucasian populations (Zhou et al., 2003); in
Japanese populations (Ito et al., 2004) and in
Caucasian populations (Hung et al., 2005).
In conclusion, the frequency of the mutant GG
genotype of the APE1 Asp148Glu (2197 T→G)
polymorphism in the former smokers had a
statistically significant difference regarding
decreased risk of lung cancer, where the
Rezk Elbaz et al
186
frequency of the lung cancer cases was lower
than that of the healthy controls, while, current
and never smokers did not, whereas, the
frequency of the mutant AA genotype of the
XRCC1 Arg399Gln (28152 G→A)
polymorphism in the never smokers had a
statistically highly significant difference
regarding highly decreased risk of lung cancer,
where the frequency of the lung cancer cases
was lower than that of the healthy controls,
while, current and former smokers did not.
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الملخص العربي
بين المدخنين المصابين بسرطان الرئة من المصريين APE1 and XRCC1تعدد اشكال الجين لجينات اصالح الحامض النووي
يرزق أحمد عبد اللطيف الباز وسالم عبد الهادي حبيب ومها إبراهيم إسماعيل إبراهيم وجمال كامل العبيد ولمياء محمد محمود رمضان وأحمد ستين
1, وحدة الوراثة، مستشفى األطفال، جامعة المنصورة
2 ,قسم الكيمياء الحيوية، كلية العلوم بدمياط، جامعة المنصورة
3, مركز األورام، جامعة المنصورة
4, مركز جراحة الجهاز الهضمي، جامعة المنصورة
5 .معامل وزارة الصحة بالمنصورة
تلف الحمض النووي الناجم عن عوامل . ن الرئة من االسباب المؤدية الى الوفاة ولذلك فهو يمثل مشكلة صحية رئيسية عامةيعد سرطا
.داخلية وخارجية يحدث باستمرار بنسب مرتفعة في الخاليا البشرية
ك من خالل مسارات مختلفة منها مسار اإلصالح ازالة أو إصالح القواعد التالفة من االليات الهامة للحفاظ على سالمة الجينوم البشري وذل
. الذي يزيل قواعد معينة غير صحيحة أو تالفة, (BER)باستئصال القاعدة
APE1 وXRCC1 هما من بروتينات إصالح الحمض النووي التي تلعب دوراً هاماً في طريقة اإلصالح باستئصال القاعدة(BER . )
APE1 and)بين التغير الجيني لجينات الحامض النووي في طريقة اإلصالح باستئصال القاعدة في هذه الدراسة قمنا بدراسة العالقة
XRCC1) حالة سرطان الخاليا 33حالة مصابة بسرطان الرئة تشمل؛ 131وقد شملت هذه الدراسة .و التدخين و سرطان الرئة
في الفترة , مصر, جامعة المنصورة, تجميعهم من مركز األورامتم (. ٪84,9)حالة سرطان الخاليا غير الصغيرة 89و( ٪25,2)الصغيرة
.2010إلى مارس 2009ما بين إبريل
هذه المجموعة الضابطة . من االشخاص األصحاء عشوائياً من المتبرعين بالدم 150للمقارنة، تم اختيار مجموعة ضابطة سلبية، وتشمل
ممن زاروا , طان، إلى جانب عدم وجود تاريخ مرضي عائلي للسرطان لديهمتم اختيارها بناًء على خلو هؤالء األشخاص من السر
.2010إلى مارس 2009مستشفيات جامعة المنصورة في الفترة من إبريل
Gentra)من عينات الدم الطرفي الكامل باستخدام عمود التقاط، وتنقية جيل الحمض النووي DNAتم استخالص الحمض النووي
system, USA) kit، والتنميط الجيني لتعدد األشكال الجينية لـ(APE1 Asp148Glu (2197 T→G) and XRCC1
Arg399Gln (28152 G→A)) التسلسلية في وجود زوجين من البادئات المتقابلة تفاعالت البلمرة ، تم إنجازها باستخدام طريقة
(PCR-CTPP .)مج وقد تم تحليل البيانات والنتائج إحصائياً باستخدام برناSPSS 10اإلحصائي اإلصدار.
لم يكن هناك اختالف كبير في جميع الترددات لكل الطرز واألليالت في APE1 Asp148Glu (2197 T→G)وكانت النتائج بالنسبة لـ
.مجموع الحاالت المصابة بسرطان الرئة مقارنة باألصحاء
ط الجينية و األليالت في حاالت االصابة بسرطان الرئة مقارنة مع لم تكن هناك ايضا اختالفات كبيرة في الترددات من جميع االنما
في GGبينما في االفراد المدخنين السابقين الحظنا وجود اختالف كبير في النمط الجيني المتحول . الضوابط في كل حاالت التدخين
.(p-value=0.003)حاالت االصابة بسرطان الرئة مقارنة مع الضوابط حيث كانت
لم يكن هناك اختالف كبير في جميع الترددات لكل الطرز واألليالت XRCC1 Arg399Gln (28152 G→A)ا أنه بالنسبة لـ وجدن
.في مجموع الحاالت المصابة بسرطان الرئة مقارنة باألصحاء
بة بسرطان الرئة مقارنة مع ولم تكن هناك ايضا اختالفات كبيرة في الترددات من جميع االنماط الجينية و األليالت في حاالت االصا
بينما في االفراد الغير مدخنين الحظنا وجود اختالف كبير جدا في النمط. الضوابط في كل حاالت التدخين
.(p-value=0.0004)في حاالت االصابة بسرطان الرئة مقارنة مع الضوابط حيث كانت AAالجيني المتحول