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