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High resolution human leukocyte antigen (HLA) class I and class II allele typing in Mexican mestizo women with sporadic breast cancer: case-control study

  • David Cantú de León1Email author,
  • Delia Pérez-Montiel2,
  • Verónica Villavicencio3,
  • Alejandro García Carranca4,
  • Alejandro Mohar Betancourt5,
  • Victor Acuña-Alonzo6,
  • Alberto López-Tello7,
  • Gilberto Vargas-Alarcón8,
  • Rodrigo Barquera6,
  • Neng Yu9,
  • Edmond J Yunis10 and
  • Julio Granados7
BMC Cancer20099:48

DOI: 10.1186/1471-2407-9-48

Received: 07 October 2008

Accepted: 05 February 2009

Published: 05 February 2009

Abstract

Background

The development of breast cancer is multifactorial. Hormonal, environmental factors and genetic predisposition, among others, could interact in the presentation of breast carcinoma. Human leukocyte antigen (HLA) alleles play an important role in immunity (cellular immunity) and may be important genetic traits. HLAAllele-specific interaction has not been well established. Recently, several studies had been conducted in order to do so, but the results are controversial and in some instances contradictory.

Methods

We designed a case-control study to quantify the association of HLA class I and II genes and breast cancer. HLA typing was performed by high resolution sequence-specific oligotyping after DNA amplification (PCR-SSOP) of 100 breast cancer Mexican mestizo patients and 99 matched healthy controls.

Results

HLA-A frequencies that we were able to observe that there was no difference between both groups from the statistical viewpoint. HLA-B*1501 was found three times more common in the case group (OR, 3.714; p = 0.031). HLA-Cw is not a marker neither for risk, nor protection for the disease, because we did not find significant statistical differences between the two groups. DRB1*1301, which is expressed in seven cases and in only one control, observing an risk increase of up to seven times and DRB1*1602, which behaves similarly in being present solely in the cases (OR, 16.701; 95% CI, 0.947 – 294.670). DQ*0301-allele expression, which is much more common in the control group and could be protective for the presentation of the disease (OR, 0.078; 95% CI, 0.027–0.223, p = 0.00001).

Conclusion

Our results reveal the role of the MHC genes in the pathophysiology of breast cancer, suggesting that in the development of breast cancer exists a disorder of immune regulation. The triggering factor seems to be restricted to certain ethnic groups and certain geographical regions since the relevant MHC alleles are highly diverse. This is the first study in Mexican population where high resolutions HLA typing has been performed in order to try to establish an association with malignancy.

Background

Breast cancer is a common neoplasm around the world with almost 1 million cases diagnosed every year, it is also considered the most frequent malignant neoplasm in developed countries, globally accounts for 18% of all female cancers [1]. In Mexico, this neoplasm occupies second place, preceded only by cancer of the cervix, which occupies 10.6% of all tumors and 16.4% of all tumors in women. It is considered that the combination of cervico-uterine cancer and breast cancer corresponds to 49% of all neoplasms in Mexican women [2].

Multiple factors are associated with an increase in breast cancer development, including age, family history, exposure to hormones (endo – as well as exogenous), diet, benign mammary disease, and environmental and genetic factors. The majority of these factors moderately increase the risk of developing cancer. It is estimated that at least 50 and up to 80% of women who develop breast cancer do not possess predisposing factors in addition to gender and age [3].

According to Rodríguez-Cuevas et al. [4], in Mexico from 1993 – 1995, 29,075 new cases of breast cancer were reported, of which 45.5% presented at the age of < 50 years; it is noteworthy that the most affected age group was that of 40 – 49 years, corresponding to 29.5% of all tumors. When a comparison was carried out with studies reported by other authors, it was found that in Mexico, this disease presented at least one decade prior to presentation in European countries or in the U.S. On conducting a comparative evaluation with other Latin American countries such as Venezuela [5], we found that the percentage of women < 50 years of age with a diagnosis of breast cancer is similar to that of Mexico. Thus, we concluded that Latin American women have the tendency to develop this type of neoplasm at an earlier age [4, 5].

This observation is similar to that for Japanese women, in whom 46.5% of women with this disease were aged < 50 years [6]. It appears that environmental or dietary factors are not responsible for this behavior, because reports in the literature evaluating Hispanic patients residing in Los Angeles, California, or in the U.S. state of New Mexico show a percentage of presentation (38 – 39%) similar to that of ages of women living in Mexico or other Latin American countries [7]. According to this information, it is possible that there is (are) some factor(s) that make(s) women present this disease when no other risk factor is found.

One of the predisposing factors can be genes located within the major histocompatibility complex (MHC) region; the association between human leukocyte antigen (HLA) gene products with a disease does not necessarily reflect the direct involvement of these molecules in the disease process [8], and because many genes can be in linkage disequilibrium with other MHC genes, this possible association could be due solely to a closely associated gene.

The HLA system involvement in the development of cancer is poorly understood; nonetheless, it is widely recognized that MHC genetic variations lead to greater susceptibility to neoplasm development [9]. Neoplastic cells express a number of genes not expressed by their normal counterpart, and also some peptides of some proteic products of these HLA molecule-associated genes [10].

The role of oncogene – and tumor suppressor gene-acquired changes is widely recognized; similarly, there is growing evidence suggesting that the immune system plays a protector role in tumorigenesis [11, 12]. In patients with cancer, HLA peptide complex-stimulated T-cell responses are not sufficiently effective for eliminating tumor cells. Loss of HLA expression or deregulation has been reported in a great variety of tumors, including breast cancer [13]; changes in the expression of these antigens have been associated with poor prognosis. Notwithstanding this, in tumoral tissue class I antigen expression is rarely lost in its entirety [14]. Such changes connote the possibility that this represents mechanisms by which neoplastic cells escape cell-mediated immunological surveillance – due to their being poor targets for cytotoxic T-cells – allowing for tumor dissemination and metastasis [15].

If immunological surveillance is important during tumorigenesis, certain individuals who inherit specific HLA class I alleles, which are highly polymorphic, such as DRB or DQB, can be more susceptible to developing tumors, or contrariwise, more resistant to the growth of these [13, 14].

In breast cancer, the study of HLA is reduced; the greatest number of studies is conducted on HLA class I expression. These studies have shown that up to 80% of tumors exhibit partial or total loss of HLA class I antigens [16, 17], while other tumors such as cervix, larynx, melanoma, colon, and pancreas demonstrate a loss of up to 40 – 50% [1820]. Evaluation has arrived at the field of prognosis; for example, in the study of Gudmundsdottir et al. [21], the authors showed that a cohort of 187 patients with clinical stages I and II, mixed HLA class I expression exhibited an increase in the probability of late recurrence and a greater probability of death (odds ratio [OR] = 3.42; p = 0.014) due to the disease in patients with negative auxiliary lymph nodes in comparison with patients demonstrating total negativity or positivity, especially after 5 years.

The first evaluation of HLA class II and their alleles was carried out by Chaudhuri et al. [13] in a group of 173 patient with breast cancer and 215 Caucasian-origin controls, showing the presence of the DRB3*0201/*0202 allele in 55% of cases and in 40.9% of controls (p = 0.0072) as risk factor. At the same time, the authors concluded that DQB*03032 and DRB1*11 alleles represent resistance factors toward the disease. HLA polymorphisms appear to be responsible for the immune response variations in different individuals to different antigens and can contribute to susceptibility to the disease, specifically to non virus-related tumors, because breast cancer frequency in Mexico is high, thus considered a health problem, and the disease is present in any age group, with the characteristic of presenting at an earlier age than in other countries, and with the evidence that between 50 and 80% [1, 3] of patients do not present the classical risk factors of the disease; therefore, it is necessary to investigate whether there is loss of control of the immune system regarding the tumor cell in this group of sick persons that allows neoplastic growth. At present, there are no reports of HLA system alleles in Mexican mestizo female population with breast cancer.

Methods

Subjects

We developed a case-control study at the National Institute of Cancerology (Instiuto Nacional de Cancerología de México, INCan) in Mexico City. A case was defined as a Mexican mestizo female patient with at least two previous generations born in Mexico, in whom breast cancer confirmed by histopathology has been diagnosed, who has been treated at the INCan Breast Tumor Service. A control was defined as a Mexican mestizo female patient who has at least two previous generations born in Mexico, from open population, without a family history of any type of cancer, with emphasis placed on breast, colon, ovary, and prostate cancer, without a history of autoimmune diseases, who has been submitted to breast and/or radiological exploration that discard pathology at this level according to patient age. We applied a clinical history oriented toward determination of personal and familial antecedents-of-interest; in the case of obtaining no response being or the response being positive, the patient was excluded from the study.

Determination of the absence of mammary pathology was performed according to patient age, with the following American Cancer Society (ACS) guidelines for detection of early breast cancer [22]: a) In women < 40 years of age, a clinical examination was conducted exclusively; in the case of requiring further evaluation, the patient was discarded as a control and excluded from the study, and b) in women aged > 40 years, we carried out a clinical examination as well as a mammographic study and breast ultrasound (US) to determine mammary pathology. In the case of obtaining an abnormal result or requiring further examination, the patient was discarded as a control.

The study was evaluated and approved by the Scientific and Ethical Committee of the Instituto Nacional de Cancerología de México, and all patients who were evaluated provided informed consent for radiographic studies, the taking of blood samples, and evaluation of genetic material. This study was performed in collaboration and with the technical and methodological support of the American Red Cross in Nedham Massachusetts, USA.

HLA typing

Genomic DNA was obtained from peripheral blood leukocytes and extracted by standard techniques [23, 24].

Amplification of genomic DNA

HLA-DQA1 and – DQB1 typing were amplified by PCR and hybridized to sequence specific oligonucleotide probes. Primers used for HLA-DQ amplification included DQAAMP-A,-B, DQBAMP-A, and -B. These were synthesized in a DNA-SM automated synthesizer (Beckman, Palo Alto, CA, USA). These typing techniques were approved by the 12th International Histocompatibility Workshop.

Dot blot hybridization

Five percent of the amplified DNA was denatured in 0.4 mol/L NaOH for 10 min, neutralized in 1 mol/L of ammonium acetate, and transferred to a Hybond-N membrane (Amersham, Bucks, UK). The filters were prehybridized at 42°C for 30 min in a solution containing 6× SSPE (30× SSPE: 4.5 mol/L NaCl, 0.3 mol/L NaH2PO4, 30 mmol/L EDTA, pH = 7.4), 5× Denhard solution (2% bovine serum albumin, 2% polyvinylpyrrolidone 40, 2% Ficoll 400), 0.1% Lauryl-sarcosine, and 0.02% SDS. Then, the oligonucleotide probes labeled with Digoxygenin dideoxy- Uridine-Triphosphate (Dig-11-ddUTP) were added and hybridized at 42°C for 3 h. The filters were washed twice in 2× SSPE, 0.1% SDS at room temperature for 10 min, once in TMAC solution [50 mmol/L Tris-HCl (pH = 8.0), 3 mol/L tetramethylammonium chloride, 2 mmol/L EDTA, 0.1% SDS] at room temperature for 10 min, and twice at 60°C for 10 min. Dots were revealed using the Dig Nucleic Acid Detection Kit (Boehringer Mannheim Biochemical, Mannheim, Germany).

Statistical analysis

HLA-A, HLA-B, HLA-C, allele and haplotype frequencies were estimated using the Arlequin program version 2.000 [25]. Significance of two-locus linkage disequilibrium (LD) was determined using Popgene program version 1.31 [26]. Odds ratio (OR) was calculated as per Haldane modified Woolf's formula [27]. OR = [(a + 0.5) (d + 0.5)/(b + 0.5) (c + 0.5)] where, a and b are the number of patients and controls positive for a given allele respectively, while c and d represent the number of patients and controls negative for the allele, respectively. The corrected P value was calculated using Bonferroni's inequality method [28] as, P corrected = 1- (1-p)n, where n = number of comparisons.

Association between HLA haplotype and breast cancer was examined using statistical analysis from a 2 × 2 table according to the method described by Svejgaard and Ryder [29].

Results

During the study period, we included 100 patients who fulfilled inclusion and exclusion criteria with a confirmed diagnosis of breast cancer. Similarly, we obtained 99 samples of healthy control subjects.

Age of patients with breast cancer ranged from 27 – 82 years (average age, 50.4 ± 12.8 years); distribution was normal. Seventy two cases did not present a familiar history of breast cancer, and in 28 cases, there was at least one first-degree family member with this neoplasm type; average age at menarche was 12.8 years. Seventy one percent of women used no family planning method, while use of oral hormones or another hormonal-therapy type was present only in 29 patients; the remainder of patients utilized some other family planning method. History of smoking as a risk factor was present in only 16% of patients.

Locally advanced and advanced clinical stages were the most frequent (64%) stages in comparison with early stages. It is noteworthy that in 15% of cases, it was not possible to determine the clinical stage because the patients had been care for previously at another hospital. It was possible to determine tumor size in 89 cases, with an average of 5.2 cm (standard deviation [SD] ± 3.49; range, 1 – 17 cm); in addition, it was possible to determine the distribution of clinical lymph node status in 94 patients, the most frequent lymph node status being N1 with 46 cases, and the second most frequent, N0 with 23 patients, according to the Tumor-Node-Metastasis (TNM) lymph node staging description.

As expected due to neoplasm frequency, distribution by histological type obtained 94 cases of infiltrating ductal carcinoma and only six cases of infiltrating lobular carcinoma. Concerning differentiation degree, we found poorly differentiated carcinoma in 56% of cases, while moderately and well differentiated presented in 38 and 6% of cases, respectively. Distribution of differentiation degree with respect to the Scarff-Bloom-Richardson Index exhibited the presence of high-grade tumors in 67% of patients; the hormonal receptors of these tumors were distributed as follows: Positive estrogenic receptors in 54 cases; negative estrogenic receptors in 45 cases; positive pregestational receptors in 29 cases, and negative pregestational receptors in 70 cases. In one case, it was not possible to conduct hormonal receptor determination. Patient clinical characteristics were shown, as well as those of the neoplasms in Table 1.
Table 1

Patient Clinical Characteristics and Neoplasm Characteristics

  

n

Age

50.4 +/- 12.8 (Mean +/- SD)

 

Menarche

12.8 (Median)

 

Family history

Positive

28

 

Negative

72

Family planning

Positive for hormonal

29

 

Negative

71

Tobbaco

Positive

16

Clinical stage

I

8

 

IIa

13

 

IIb

23

 

IIIa

19

 

IIIb

13

 

IV

9

 

No classified

15

Tumor size

5.2 +/- 3.49 (Mean +/- SD)

 

Nodal status

N0

26

 

N1

46

 

N2

21

 

N3

1

 

Missing

6

Histology

Ductal

94

 

Lobular

6

Grade

Well differentiated

6

 

Moderately

38

 

Poorly

56

Hormone receptor status

Estrogen positive

54

 

Estrogen negative

45

 

Progesterone positive

29

 

Progesterone negative

70

At the moment of performing the present study, 61 patients were found without evidence of disease, while 39 cases presented disease recurrence (data not shown, in that this was not the objective of the present work).

Table 2 shows the different HLA classes I and II alleles studied in the group of cases, as well as their genetic frequencies. Table 3 depicts the different HLA classes I and II alleles studied in the control group of patients, as well as the genetic frequencies of these.
Table 2

Frequencies (g.f) of HLA-A,-B, Cw, DRB1 and – DQB1 in Cases.

-A

n

g.f

-B

n

g.f

-Cw

n

g.f

-DRB1

n

g.f

-DQB1

n

ggg.f g.f

0201

39

0.224

1501

13

0.074

0401

34

0.195

0802

27

0.155

0300

54

0.310

2402

25

0.143

3501

13

0.074

0702

29

0.167

0407

22

0.126

0302

30

0.172

0206

20

0.114

4002

11

0.063

0102

16

0.092

1406

14

0.080

0402

29

0.167

3101

16

0.091

5101

9

0.051

0701

13

0.075

0404

12

0.069

0200

18

0.103

6801

8

0.045

5201

9

0.051

0602

11

0.063

0301

12

0.069

0501

10

0.057

1101

8

0.045

3905

9

0.051

0303

9

0.052

0701

11

0.063

0602

6

0.034

6803

7

0.040

3512

8

0.046

0304

8

0.046

1301

7

0.040

0603

5

0.029

0101

7

0.040

0801

8

0.046

1203

7

0.040

1602

7

0.040

0601

5

0.029

0301

5

0.028

3517

7

0.040

1502

7

0.040

1501

6

0.034

0600

4

0.023

2601

5

0.028

3906

6

0.034

0801

6

0.034

0102

6

0.034

0303

4

0.023

3201

5

0.028

4801

6

0.034

0305

6

0.034

1402

5

0.029

0202

2

0.011

2902

5

0.028

0702

5

0.029

1509

5

0.029

0403

4

0.023

0503

2

0.011

3001

4

0.023

3801

5

0.029

1202

4

0.023

0410

4

0.023

0502

1

0.006

6802

3

0.017

4403

4

0.023

0802

4

0.023

1502

4

0.023

0201

1

0.006

2425

2

0.011

5001

4

0.023

1601

4

0.023

0402

3

0.017

0604

1

0.006

2501

2

0.011

1402

4

0.023

0202

3

0.017

1302

3

0.017

   

3301

2

0.011

3514

4

0.023

1604

2

0.011

1101

3

0.017

   

3010

1

0.005

4402

3

0.017

0803

2

0.011

0411

3

0.017

   

0302

1

0.005

1530

3

0.017

0509

1

0.005

0401

2

0.011

   

2301

1

0.005

1302

3

0.017

1801

1

0.005

0101

2

0.011

   

6805

1

0.005

3508

3

0.017

1701

1

0.005

1104

2

0.011

   

2201

1

0.005

4006

2

0.011

0501

1

0.005

1305

2

0.011

   

7401

1

0.005

3908

2

0.011

   

0405

2

0.011

   

3131

1

0.005

1515

2

0.011

   

1503

1

0.005

   

6901

1

0.005

4101

2

0.011

   

1601

1

0.005

   

3002

1

0.005

1801

2

0.011

   

1448

1

0.005

   

0205

1

0.005

4501

2

0.011

   

1404

1

0.005

   

2403

1

0.005

3503

2

0.011

   

1202

1

0.005

   
   

2705

2

0.011

   

0302

1

0.005

   
   

3905

2

0.011

   

0103

1

0.005

   
   

4008

1

0.005

   

1001

1

0.005

   
   

other

18

0.114

   

1401

1

0.005

   

N = 174.

Table 3

Frequencies (g.f) of HLA-A,-B,-Cw,-DRB1 and – DQB1 in controls.

-A

n

g.f

-B

n

g.f

-Cw

n

g.f

-DRB1

n

g.f

-DBQ1

n

g.f

0201

41

0.220

3905

19

0.102

0702

40

0.215

0407

33

0.177

0302

51

0.274

2402

31

0.166

3512

14

0.075

0401

36

0.194

0802

25

0.134

0301

43

0.231

6801

19

0.102

4002

13

0.069

0304

16

0.086

0404

15

0.081

0402

28

0.151

3101

13

0.069

5101

11

0.059

0102

15

0.081

1406

15

0.081

Dqbx

21

0.113

AX

11

0.059

3501

11

0.059

Cwx

13

0.070

Drx

13

0.070

0501

12

0.065

0206

10

0.053

3906

10

0.053

0701

9

0.048

0701

12

0.065

0202

10

0.054

6803

8

0.03

BX

10

0.053

0602

8

0.043

1602

11

0.059

0201

6

0.032

3002

6

0.032

3514

6

0.032

0801

7

0.038

1501

7

0.038

0602

5

0.027

0301

6

0.032

4005

6

0.032

0802

7

0.038

1104

7

0.038

0603

3

0.016

3301

5

0.026

0702

6

0.032

0303

5

0.027

0301

6

0.032

0502

2

0.011

1101

4

0.021

4801

5

0.026

0501

4

0.022

0102

6

0.032

0303

2

0.011

0101

4

0.021

1402

5

0.026

1502

4

0.022

1402

5

0.027

0604

1

0.005

6802

4

0.021

5201

4

0.021

0305

3

0.016

0403

4

0.022

0601

1

0.005

2301

3

0.016

3543

4

0.021

1203

3

0.016

0101

3

0.016

0304

1

0.005

2601

3

0.016

0801

4

0.021

0202

3

0.016

0401

3

0.016

   

2902

3

0.016

1501

4

0.021

0306

3

0.016

1001

3

0.016

   

3201

3

0.016

3517

3

0.016

1601

2

0.010

0804

2

0.010

   

6805

2

0.010

1515

3

0.016

1402

2

0.010

0411

2

0.010

   

3001

2

0.010

1801

3

0.016

1509

2

0.010

0801

2

0.010

   

0204

1

0.005

3902

3

0.016

0704

2

0.010

1407

1

0.005

   

0224

1

0.005

3508

2

0.010

0401

1

0.005

1201

1

0.005

   

0205

1

0.005

4901

2

0.010

   

1302

1

0.005

   

6601

1

0.005

1401

2

0.010

   

1304

1

0.005

   

0102

1

0.005

1516

2

0.010

   

1502

1

0.005

   

2425

1

0.005

5301

2

0.010

   

0405

1

0.005

   

2301/05

1

0.005

3701

2

0.010

   

1102

1

0.005

   
   

4402

2

0.010

   

0809

1

0.005

   

2402/25

1

0.005

4501

2

0.010

   

1305

1

0.005

   
   

1302

2

0.010

   

1301

1

0.005

   
   

1517

2

0.010

         
   

3502

2

0.010

         
   

Other

20

0.107

         

N = 186.

In Table 4, we found alleles with the highest genetic HLA-A frequencies that were detected; we were able to observe that there was no difference between both groups from the statistical viewpoint, although we noted a tendency for risk in one of these (*0206), as well as one for protection in the other (*6801), after correction for multiple comparisons for the number of alleles of HLA-A locus (n = 11), the risk was not significant (Pc = 0.45). It is worthwhile mentioning that the following four alleles were the most frequent in both groups: HLA-A*0201; -*2402; -*0206, and -*3101. In addition, also depicted in this Table are high-resolution HLA-B typifications with greatest genetic frequency compared – if only one exhibited a statistically significant difference for the risk factor, on finding this with a three times greater frequency in the case group in comparison with the control group HLA-B*1501 (OR, 3.714; p = 0.031). After correction for multiple comparisons for the number of alleles of HLA-B locus (n = 17), the risk was not significant (Pc = 0.30).
Table 4

Risk assessment among different loci of HLA class I

 

CASES

N = 174

CONTROLS

N = 186

   

Locus

n

g.f

n

g.f

P

OR

C195%

HLA-A

       

0201

39

0.224

41

0.220

0.96

1.022

0.621–1.68

2402

25

0.143

31

0.166

0.648

0.839

0.473–1.48

0206

20

0.114

10

0.053

0.056

2.286

1.038–5.033*

3101

16

0.091

13

0.069

0.565

1.348

0.628–2.890

6801

8

0.045

19

0.102

0.068

0.424

0.180–0.995

HAL-B

       

1501

13

0.075

4

0.021

0.031

3.714

1.187–11.619+

3501

13

0.075

11

0.059

0.704

1.285

0.560–2.949

4002

11

0.063

13

0.069

0.966

0.898

0.391–2.062

5101

9

0.052

11

0.059

0.939

0.868

0.351–2.148

5201

9

0.052

4

0.021

0.21

2.482

0.750–8.211

HLA-Cw

       

0401

34

0.195

36

0.194

0.929

1.012

0.6–1.706

0702

29

0.167

40

0.215

0.302

0.73

0.430–1.241

0102

16

0.092

15

0.081

0.846

1.154

0.553–2.412

0701

13

0.075

9

0.048

0.411

1.588

0.661–3.814

0602

11

0.063

8

0.043

0.535

1.502

0.589–3.825

* Pc = 0.45. +Pc = 0.30.

HLA-Cw is a scarcely studied gene in this neoplasm type; we are able to say that at least in this group of women obtained from an ethnically similar population, HLA-Cw is not a marker for, nor a risk for, nor protection for the disease, because we did not find differences between the two groups.

In Table 5, we can observe HLA-DR distribution, in which we are able to identify two alleles that on being expressed comprise an associated risk factor for presenting the disease, such as DRB1*1301, which is expressed in seven cases and in only one control, observing an risk increase of up to seven times; notwithstanding this, it is important to mention that the confidence interval (CI) is very broad, which can be a reflection of its low genetic frequency (genetic frequency [g.f.] = 0.040) and DRB1*1602, which behaves similarly in being present solely in the cases (in seven of these) (OR, 16.701; 95% CI, 0.947 – 294.670), after correction for multiple comparisons for the number of alleles of HLA-DRB1 locus (n = 11), the risk was not significant (Pc = 0.24). Regarding HLA- DQ, we found two alleles of this gene associated with the disease, such as DQ*0302 with a g.f. of 0.454 in the group of cases, and a g.f. of 0.274 in the control group (OR, 2.201;95% CI,1.419–3.415), after correction for multiple comparisons for the number of alleles of HLA-DQ locus (n = 8), the risk was statistically significant (Pc = 0.0007). However, the allele commanding the majority of attention is DQ*0301-allele expression, which is much more common in the control group (g.f., of 0.231) being a protector presentation of the disease. This relationship is sustained after corrections for multiple comparisons (Pc = 0.00008) for HLA-DQB1 (n = 8).
Table 5

Risk assessment among different loci of HLA class II

 

CASES

N = 174

CONTROLS

N = 186

   

Locus

n

g.f

n

g.f

P

OR

C195%

HLA-DRB1

       

0802

27

0.155

25

0.134

0.682

1.183

0.657–2.130

0407

22

0.126

33

0.177

0.231

0.671

0.374–1.204

1406

14

0.080

15

0.081

0.851

0.998

0.467–2.132

1301

7

0.040

1

0.005

0.06

7.754

0.944–63.689

1602

7

0.040

0

0

0.025

16.701

0.947–294.670*

HLA-DQB1

       

0302

79

0.454

51

0.274

0.0001

2.201

1.419–3.415**

0402

29

0.167

28

0.151

0.784

1.129

0.641–1988

0202

18

0.103

10

0.054

0.118

2.031

0.910–4.531

0301

4

0.022

43

0.231

0.00001

0.078

0.027–0.223***

0201

2

0.011

0

0

0.524

5.406

0.258–113.402

0303

1

0.005

2

0.011

0.954

0.532

0.048–5.918

* Pc = 0.24. **Pc = 0.0007 ***Pc = 00008

Haplotypes were deduced both the results are highly heterogenic (data not show) therefore not conclusions could be drawn or associations performed.

Discussion

The origin of malignant neoplasms is multifactorial [1]; nevertheless, there are certain factors that can increase not only the risk for appearance of the disease, but even more so that the tumor would continue to grow and would produce distal disease or metastasis. Thus, if immunological surveillance is an important mechanism in the tumor genesis process, certain individuals who inherit specific HLA class II alleles can be resistant or more susceptible to tumor presentation [13]. The results of different works show few reproducible results because there are important differences in the expression of the different HLAs, depending on the geographical area to which reference is made [34]. This is due to that the frequency of presentation of the different HLA alleles is determined by the dominant pathogens of each geographic region in particular, and because these genes are highly polymorphic.

Breast cancer has exhibited an increase in incidence in recent years, it is the tumor second only to lung cancer as cause of death by cancer in females, and is the number one cause of death by cancer in women 15 – 54 years of age worldwide [31]. In Mexico, breast cancer is a very frequent tumor; thus, study of this disease and the factors that predispose its presentation is of prime importance for identification of at-risk groups, which translates into a more precise evaluation for each woman [5].

To date, few studies have been conducted to attempt to determine the association and impact that these represent in the risk of presenting breast cancer and the different HLA, especially HLA class II, and some studies lack sufficient power due to a reduced number of studied cases [33].

In 2005 Lavado et al. [34], compared 132 women with breast cancer and 382 healthy controls in the Spanish region of Málaga. They performed HLA-A,-B, -Cw, -DR, and -DQ typification. The most important differences were found in the HLA-B locus, where the HLA-B7 allele was present with greater frequency in the group of sick patients than in the control group (p = 0.0019; 95% CI, 1.337 – 3.409; Relative risk [RR], 2.135), explaining that in this geographical zone an environmental agent can be found (whether viral or bacterial) that can be associated with breast cancer. Our study reveals a significantly increased frequency of HLA-B*1501 in cancer patients in comparison to healthy controls (OR = 3.714; CI95%, 1.187–11.619, p = 0.031) but not in other HLA-B alleles.

Gopalkrishnan et al. [36], in a group of women from India, evaluated low- or intermediate-resolution gene expression of HLA-A,-B, and -C, finding the following two alleles as candidates for markers associated in risk modulation for breast cancer in Eastern Indian women: Alleles HLA-B*40 and -B*08, the first as a factor for early development of the disease, presenting in 16% of cases vs. 9.0% of controls (OR, 2.2; 95% CI, 1.15 – 4.34; p = 0.02), and the second, found to be a protector. These protective or high risk alleles even though were frequent in our population (HLA-B*40 g.f.= 0.080 and -B*08 g.f. = 0.046) associations were not statistically significant neither for risk not for protection to the development of the neoplasm.

We found HLA-DQB1*0302 to be protective as well as HLA-DQB1*0301 but not associated with age, which is contrary to what was reported by Chaudhuri et al. [13] in 2000, where he reports two important negative associations for the development of breast cancer at an early age, both of HLA class II: DRB*11, which was found expressed in 35 controls and only in six cases (p < 0.0001). These results reflect, at least in the patient group, that inheritance of the alleles of these genes (DQB*03032 and DRB1*11) represent alleles resistant to the presentation of early-age breast cancer.

Positive association of specific HLA class II alleles in any malignant-tumor type reflects the specific role of these molecules in the promotion of chronic inflammation. HLA expression suggests that immune-system evasion of certain cellular populations could be responsible for promoting survival of the neoplasm, thus rendering it necessary to continue evaluating these markers in different populations and to include greater numbers of patients to confirm the different associations and risks between alleles and haplotypes and to determine whether there are others that could be catalogued as risk factors for development of the neoplasm, and at a determined moment whether the fact that some allele, alleles, or haplotypes are found expressed consistently in some group of individuals affords the power to utilize HLA class II typifications as prognostic factors, at the present moment few authors had performed characterization of HLA in latin population, we could say this is the first attempt to characterize a Mexican mestizo population in order to try to find associations between HLA and breast cancer.

Conclusion

The results obtained by our group demonstrate the role of genetics in the multifactorial pathophysiology of breast malignant neoplasms. It also reveals the role of the MHC genes in the pathophysiology, suggesting that in the development of breast cancer exists a disorder of immune regulation.

Nevertheless, this triggering factor (MHC genes) seems to be restricted to certain ethnic groups as well as certain geographical regions since these relevant MHC alleles are highly diverse and confirms the relevance of HLA-DR alleles in the genetic susceptibility to develop this specific type of malignant disease.

Abbreviations

HLA: 

human leukocyte antigen

MHC: 

Major histocompatibility

ACS: 

American cancer society

PCR: 

Polymerase chain reaction

Declarations

Authors’ Affiliations

(1)
Department of Gynecologic Oncology, Instituto Nacional de Cancerología de México
(2)
Department of Pathology, Instituto Nacional de Cancerologia
(3)
Division of Surgery, Insituto Nacional de Cancerología
(4)
Laboratory of Virus and Cancer, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México
(5)
Instituto Nacional de Cancerologia, Unidad de investigacion biomedica
(6)
Molecular Genetics Laboratory, ENAH
(7)
Instituto Nacional de Ciencias Médicas y Nutrición " Salvador Zubirán ", Immunology and Rehumatology Department
(8)
Department of Physiology, Instituto Nacional de Cardiología "Ignacio Chavez"
(9)
American Red Cross Blood Services, New England Region
(10)
Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute

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  38. Pre-publication history

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© Cantú de León et al; licensee BioMed Central Ltd. 2009

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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