Med Oncol (2014) 31:955 DOI 10.1007/s12032-014-0955-y
ORIGINAL PAPER
EYA1 expression in gastric carcinoma and its association with clinicopathological characteristics: a pilot study Parvaneh Nikpour • Modjtaba Emadi-Baygi Elaheh Emadi-Andani • Shima Rahmati
•
Received: 21 February 2014 / Accepted: 30 March 2014 / Published online: 12 April 2014 Ó Springer Science+Business Media New York 2014
Abstract As the second most frequent cause of cancer death, gastric cancer is a common disease worldwide. Most of the patients are being diagnosed in the stage that conventional treatments are not effective, and invasion and metastases lead to death. So, identification of novel molecular markers to improve early diagnosis, prognosis and treatment of the gastric cancer is a necessity. EYA1 is a member of EYA family which their deregulation has been demonstrated in several types of cancer. The aim of this study was to assess EYA1 gene expression in tissues of the gastric cancer patients and to investigate its correlation with clinicopathological parameters. A total of 60 tumor and non-tumor gastric specimens were evaluated for EYA1 gene expression using quantitative real-time PCR. The EYA1 expression decreased significantly in gastric tumor Elaheh Emadi-Andani and Shima Rahmati have contributed equally to this work. P. Nikpour Pediatric Inherited Diseases Research Center, Isfahan University of Medical Sciences, Isfahan, Iran P. Nikpour (&) Department of Genetics and Molecular Biology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran e-mail: [email protected] P. Nikpour E. Emadi-Andani Child Growth and Development Research Center, Isfahan University of Medical Sciences, Isfahan, Iran M. Emadi-Baygi S. Rahmati Department of Genetics, Faculty of Basic Sciences, Shahrekord University, Shahrekord, Iran M. Emadi-Baygi Research Institute of Biotechnology, Shahrekord University, Shahrekord, Iran
tissues compared with adjacent normal tissues. We further showed that there was a negative correlation between the EYA1 gene expression levels, tumor size, lymphatic invasion and distant metastasis. In conclusion, EYA1 might be used as a potential biomarker for monitoring gastric carcinoma progression rate. Further studies to determine the mechanism of action of EYA1 is needed to unravel the role of this gene in gastric cancer pathogenesis. Keywords Metastasis
Gastric cancer Gene expression EYA1
Introduction As the second most frequent cause of cancer death, gastric cancer is a common disease worldwide, with a frequency that varies greatly across different geographic locations [1]. In Iran, especially in northwest, gastric cancer is the major cause of cancer-related mortality, especially in men [2]. The disease does not respond to common treatments very well, most of patients are being diagnosed in the stage that conventional treatments are not effective and invasion and metastases lead to death [3]. Five-year survival of the patients with advanced gastric cancer is about 20 %; but if the surgery is possible before metastases, it would be 90 % [4]. So, it is necessary to elucidate molecular mechanisms and identify novel molecular markers to improve early diagnosis, prognosis and treatment of the gastric cancer. Vertebrates encode four EYA proteins (EYA1–4) that are characterized by a conserved C-terminal 271 amino acid domain, commonly referred to as the EYA domain (ED) [5]. These proteins are both transcriptional activators [6] and tyrosine phosphates [7]. The EYA proteins are implicated in several processes such as organ development
123
955 Page 2 of 5
[6], DNA damage repair and cell survival in the response to DNA damage [8], stem cell survival promotion [9], angiogenesis and cancer metastasis [10]. Deregulation of EYAs has been reported in several malignancies. EYA4 is over-expressed in malignant peripheral nerve sheath tumors (MPNST) [11] but hypermethylated in esophageal adenocarcinoma, colon and colorectal cancers [12–14]. Frequent deletion of the EYA3 gene in pancreatic ductal adenocarcinomas has been observed [15]. EYA2 overexpression has been shown in ovarian cancers [16], lung adenocarcinoma [17] and breast cancers [18]. However, methylation of EYA2 promoter has been reported in colorectal cancer [14]. EYA1 mRNA levels have also been shown to be overexpressed in Wilms’ tumors [19] and a subset of leukemia patients [20]. EYA1 gene shows hyper-methylation in both EBV? and EBVgastric cancers [21]. To our knowledge, there is no study concerning with the expression profiling of EYA1 gene in gastric cancer. Therefore, in the current study, we aimed to assess EYA1 gene expression in tumor and adjacent non-tumor tissues of the gastric carcinoma patients and to investigate its correlation with clinical parameters. Our results showed that EYA1 expression decreased significantly in gastric tumor tissues. We further showed that there was a negative correlation between the EYA1 gene expression levels, tumor size, lymphatic invasion and distant metastasis, but not with other clinicopathological features of gastric tumors.
Subjects, materials and methods
Med Oncol (2014) 31:955
transcriptase (Fermentas, Vilnius, Lithuania) and random hexamer primers (TAG Copenhagen). Quantitative real-time PCR Quantification of EYA1 gene expression was performed by quantitative real-time RT-PCR. Specific primers to amplify the EYA1 gene were as follows: 50 -TAACGGACAGGAC CTAAGCA-30 and 50 -TTTCTCATCCAgTCCACACC-30 . Primers for TBP, as a reference gene, were described before [25]. The PCR mixture, using Maxima SYBR Green/ROX qPCR master mix (Fermentas, Vilnius, Lithuania), was run on the Rotor-gene 6000 (Qiagen, Hilden, Germany). The conditions of the PCR amplification included an initial denaturation at 95 °C for 10 min, followed by 45 amplification cycles consisting of denaturation at 95 °C for 25 s, annealing for 30 s at 56 °C and 55 °C for EYA1 and TBP genes, respectively, and finally an extension at 72 °C for 30 s. For each sample, measurements were taken at least in triplicate. The identity of PCR fragments was further confirmed by agarose gel electrophoresis. The 2DDCt method was used for relative gene expression analysis. Statistical analyses Statistical analyses were performed using SPSS version 16.0. Paired t test or one-way ANOVA with post hoc multiple comparisons was used for the analysis of the differences between groups. A p value of \0.05 was considered statistically significant.
Subjects Results Sixty paired tumor and non-tumor gastric tissue samples were collected from Iran Tumoural Bank (Tehran, Iran) as described previously [22–24]. The experimental design conformed to the Code of Ethics of the World Medical Association (Declaration of Helsinki) and was approved by the Ethics Committee of Isfahan University of Medical Sciences. Prior to participation, all patients provided written informed consent to the Iran Tumoural Bank. Total RNA isolation and cDNA synthesis Extraction of total cellular RNA from tumor and adjacent non-tumor tissue specimens was performed using Qiazol reagent and the RNeasy Mini kit, according to the manufacturer’s instruction (Qiagen, Hilden, Germany). The quality and the concentration of the extracted RNAs were assessed by agarose gel electrophoresis and optical density at 260 nm, respectively. Two micrograms of the extracted RNA was used for cDNA synthesis using MMLV reverse
123
Optimization of PCR amplification In order to gain a specific amplicon for EYA1 gene, optimization was done for both conventional and real-time PCR reactions. Based on a study by Farabaugh et al. [18] that showed the expression of EYA1 in MCF-7 breast cancer cell line, we carried out the optimization of PCR conditions on MCF-7 cell line. Agarose gel electrophoresis of PCR products of EYA1 was showed a specific band with the expected size (117 bp). Also, melting curve analysis of real-time PCR showed that a single product without primer dimers was amplified (data not shown). Expression of EYA1 gene in gastric tissue specimens To analyze the EYA1 gene expression profile in gastric tissues, we carried out quantitative real-time PCR in sixty paired tumor and adjacent non-tumor tissues of the gastric
Med Oncol (2014) 31:955
Page 3 of 5 955 Table 1 Relationship between EYA1 expression levels and clinicopathological parameters of gastric cancer samples Characteristics
Numbers (%)
EYA1 relative expression (mean ± SEM)
Gender
0.41
Male
18 (60)
3.77 ± 0.33
Female
12 (40)
3.64 ± 0.51
C70
15 (50)
3.66 ± 0.25
\70
15 (50)
3.77 ± 0.51
9 (30)
4.16 ± 0.39
21 (70)
3.53 ± 0.36
Mx
15 (50)
2.27 ± 0.78
M0
11 (36.6)
2.00 ± 0.87
M1
4 (13.3)
1.50 ± 0.92
16 (55.17)
4.04 ± 0.37
13 (44.82)
3.13 ± 0.43
Age (years)
0.42
N classification N0 N1–N3
0.15
M classification
Fig. 1 Relative expression of EYA1 in gastric tumor samples compared to their paired non-tumor adjacent tissues. Asterisk represents a statistically significant difference (p = 0.03), and bold horizontal lines represent mean values
carcinoma patients using specific primers for both EYA1 and TBP (as internal control) genes. The results of realtime qRT-PCR experiments demonstrated that the relative expression of the EYA1 gene is significantly decreased in tumor tissues compared with adjacent non-tumor tissues (p = 0.03, Fig. 1). EYA1 expression and clinicopathological factors in gastric carcinoma Next, we investigated the correlation of EYA1 relative gene expression with the selected clinicopathological status of patients with gastric carcinoma (Table 1). The level of EYA1 transcript was downregulated in tumors with a larger size (p = 0.03), with lymphatic invasion (p = 0.04) and with distant metastasis (p = 0.01). However, there was no significant correlation between the expression levels of EYA1 and age, gender, grades or histological classifications.
Discussion Eyes absent (EYA) genes encode dual-functional transactivator-phosphatase proteins. Domains of EYA proteins (the N-terminal transactivation-threonine phosphatase and the C-terminal tyrosine phosphatase domains) are the cause of dual functionality of these proteins [9, 26]. EYA proteins are the transcriptional activators in a conserved
Lymphatic invasion Negative Positive
0.01
0.04
Tumor size (cm)
0.03
C5
20 (68.7)
3.41 ± 0.37
\5
9 (31.3)
4.44 ± 0.39
Grade I
10 (33.3)
4.00 ± 0.44
Grade II
8 (26.6)
3.73 ± 0.25
Tumor grades
Grade III
p value
0.36
12 (40)
3.47 ± 0.59
Diffuse
15 (50)
4.15 ± 0.38
Intestinal
15 (50)
3.28 ± 0.40
Tumor types
0.06
Bold values are statistically significant (p \ 0.05)
regulatory network that plays an important role during development of multiple embryonic organs [27–29]. EYA proteins also involve in other processes such as innate immunity, DNA damage repair, photoperiodism, angiogenesis and cancer metastasis [29]. EYA1 is one of the members of the EYA family. This gene is a human homolog of the Drosophila ‘eyes absent’ gene (EYA) and was therefore called EYA1 [9, 30]. To our knowledge, the expression profile of EYA1 gene in gastric cancer has not been previously investigated. Our pilot study showed that the relative expression of EYA1 gene is significantly decreased in tumor tissues compared with adjacent non-tumor tissues (p = 0.03). Furthermore, the level of EYA1 transcript was downregulated in tumors with a larger size (p = 0.03), with lymphatic invasion (p = 0.05) and with distant metastasis (p = 0.01), and there was no significant correlation between the expression levels of EYA1 and age, gender, grades or histological classification of gastric tumors.
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Med Oncol (2014) 31:955
Until now, deregulation of EYA1 gene has been reported in different cancer types. Increased expression of EYA1 as well as loss of a portion of chromosome 2 (2q37), encoding a microRNA (miR562) that regulates EYA1, has been reported in Wilm’ tumors [19, 31]. In another study by Albino et al. [32], increased expression of EYA1 was detected in stroma-poor neuroblastic tumors. In 2010, Miller et al. [33] showed that EYA1 expresses at increased levels in malignant peripheral nerve sheath tumors (MPNSTs) relative to normal Schwann cells. In contrast to the previous reports based on the tendency for EYA1 to be oncogenic, a study by Matsusaka et al. [21] demonstrated that EYA1 is often methylated and deregulated in both EBV? and EBV-/high gastric tumors. Furthermore, Forster et al. [34] also showed that there is a negative correlation between EYA1 gene expression and metastatic event status during 5 years in gastric tumors. Our results are in accord with Matsusaka et al. and Forster et al. studies [21, 34]. The controversy between different reports may be interpreted as the result of context-dependent expression of EYAs proteins [29, 35] or compensating roles of other EYA genes [29, 36].
Conclusion In summary, this is the first study describing EYA1 gene expression profile in gastric cancer. Our results showed that the gene is underexpressed in gastric tumor samples, and it negatively correlates with tumor size, lymphatic invasion and distant metastasis. Considering these results, this gene might be used as a potential biomarker for monitoring gastric carcinoma progression rate. Further studies to determine the mechanism of action of EYA1 is needed to unravel the role of this gene in gastric cancer pathogenesis. Acknowledgements This study was supported by a research Grant to PN from Isfahan University of Medical Sciences, Isfahan, Iran. Conflict of interest of interest.
The authors declare that they have no conflict
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Med Oncol (2014) 31:955 23. Nikpour P, Emadi-Baygi M, Mohhamad-Hashem F, Maracy MR, Haghjooy-Javanmard S. MSI1 overexpression in diffuse type of gastric cancer. Pathol Res Pract. 2013;209(1):10–3. 24. Nikpour P, Emadi-Baygi M, Mohammad-Hashem F, Maracy MR, Haghjooy-Javanmard S. Differential expression of ZFX gene in gastric cancer. J Biosci. 2012;37(1):85–90. 25. Nikpour P, Mowla SJ, Jafarnejad SM, Fischer U, Schulz WA. Differential effects of nucleostemin suppression on cell cycle arrest and apoptosis in the bladder cancer cell lines 5637 and SW1710. Cell Prolif. 2009;42(6):762–9. 26. Jemc J, Rebay I. Identification of transcriptional targets of the dual-function transcription factor/phosphatase eyes absent. Dev Biol. 2007;310(2):416–29. 27. Pignoni F, Hu B, Zavitz KH, Xiao J, Garrity PA, Zipursky SL. The eye-specification proteins So and Eya form a complex and regulate multiple steps in Drosophila eye development. Cell. 1997;91(7):881–91. 28. Chen R, Amoui M, Zhang Z, Mardon G. Dachshund and eyes absent proteins form a complex and function synergistically to induce ectopic eye development in Drosophila. Cell. 1997;91(7):893–903. 29. Tadjuidje E, Hegde RS. The eyes absent proteins in development and disease. Cell Mol Life Sci. 2012;70(11):1897–913. 30. Abdelhak S, Kalatzis V, Heilig R, Compain S, Samson D, Vincent C, et al. A human homologue of the Drosophila eyes absent
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ORIGINAL PAPER
EYA1 expression in gastric carcinoma and its association with clinicopathological characteristics: a pilot study Parvaneh Nikpour • Modjtaba Emadi-Baygi Elaheh Emadi-Andani • Shima Rahmati
•
Received: 21 February 2014 / Accepted: 30 March 2014 / Published online: 12 April 2014 Ó Springer Science+Business Media New York 2014
Abstract As the second most frequent cause of cancer death, gastric cancer is a common disease worldwide. Most of the patients are being diagnosed in the stage that conventional treatments are not effective, and invasion and metastases lead to death. So, identification of novel molecular markers to improve early diagnosis, prognosis and treatment of the gastric cancer is a necessity. EYA1 is a member of EYA family which their deregulation has been demonstrated in several types of cancer. The aim of this study was to assess EYA1 gene expression in tissues of the gastric cancer patients and to investigate its correlation with clinicopathological parameters. A total of 60 tumor and non-tumor gastric specimens were evaluated for EYA1 gene expression using quantitative real-time PCR. The EYA1 expression decreased significantly in gastric tumor Elaheh Emadi-Andani and Shima Rahmati have contributed equally to this work. P. Nikpour Pediatric Inherited Diseases Research Center, Isfahan University of Medical Sciences, Isfahan, Iran P. Nikpour (&) Department of Genetics and Molecular Biology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran e-mail: [email protected] P. Nikpour E. Emadi-Andani Child Growth and Development Research Center, Isfahan University of Medical Sciences, Isfahan, Iran M. Emadi-Baygi S. Rahmati Department of Genetics, Faculty of Basic Sciences, Shahrekord University, Shahrekord, Iran M. Emadi-Baygi Research Institute of Biotechnology, Shahrekord University, Shahrekord, Iran
tissues compared with adjacent normal tissues. We further showed that there was a negative correlation between the EYA1 gene expression levels, tumor size, lymphatic invasion and distant metastasis. In conclusion, EYA1 might be used as a potential biomarker for monitoring gastric carcinoma progression rate. Further studies to determine the mechanism of action of EYA1 is needed to unravel the role of this gene in gastric cancer pathogenesis. Keywords Metastasis
Gastric cancer Gene expression EYA1
Introduction As the second most frequent cause of cancer death, gastric cancer is a common disease worldwide, with a frequency that varies greatly across different geographic locations [1]. In Iran, especially in northwest, gastric cancer is the major cause of cancer-related mortality, especially in men [2]. The disease does not respond to common treatments very well, most of patients are being diagnosed in the stage that conventional treatments are not effective and invasion and metastases lead to death [3]. Five-year survival of the patients with advanced gastric cancer is about 20 %; but if the surgery is possible before metastases, it would be 90 % [4]. So, it is necessary to elucidate molecular mechanisms and identify novel molecular markers to improve early diagnosis, prognosis and treatment of the gastric cancer. Vertebrates encode four EYA proteins (EYA1–4) that are characterized by a conserved C-terminal 271 amino acid domain, commonly referred to as the EYA domain (ED) [5]. These proteins are both transcriptional activators [6] and tyrosine phosphates [7]. The EYA proteins are implicated in several processes such as organ development
123
955 Page 2 of 5
[6], DNA damage repair and cell survival in the response to DNA damage [8], stem cell survival promotion [9], angiogenesis and cancer metastasis [10]. Deregulation of EYAs has been reported in several malignancies. EYA4 is over-expressed in malignant peripheral nerve sheath tumors (MPNST) [11] but hypermethylated in esophageal adenocarcinoma, colon and colorectal cancers [12–14]. Frequent deletion of the EYA3 gene in pancreatic ductal adenocarcinomas has been observed [15]. EYA2 overexpression has been shown in ovarian cancers [16], lung adenocarcinoma [17] and breast cancers [18]. However, methylation of EYA2 promoter has been reported in colorectal cancer [14]. EYA1 mRNA levels have also been shown to be overexpressed in Wilms’ tumors [19] and a subset of leukemia patients [20]. EYA1 gene shows hyper-methylation in both EBV? and EBVgastric cancers [21]. To our knowledge, there is no study concerning with the expression profiling of EYA1 gene in gastric cancer. Therefore, in the current study, we aimed to assess EYA1 gene expression in tumor and adjacent non-tumor tissues of the gastric carcinoma patients and to investigate its correlation with clinical parameters. Our results showed that EYA1 expression decreased significantly in gastric tumor tissues. We further showed that there was a negative correlation between the EYA1 gene expression levels, tumor size, lymphatic invasion and distant metastasis, but not with other clinicopathological features of gastric tumors.
Subjects, materials and methods
Med Oncol (2014) 31:955
transcriptase (Fermentas, Vilnius, Lithuania) and random hexamer primers (TAG Copenhagen). Quantitative real-time PCR Quantification of EYA1 gene expression was performed by quantitative real-time RT-PCR. Specific primers to amplify the EYA1 gene were as follows: 50 -TAACGGACAGGAC CTAAGCA-30 and 50 -TTTCTCATCCAgTCCACACC-30 . Primers for TBP, as a reference gene, were described before [25]. The PCR mixture, using Maxima SYBR Green/ROX qPCR master mix (Fermentas, Vilnius, Lithuania), was run on the Rotor-gene 6000 (Qiagen, Hilden, Germany). The conditions of the PCR amplification included an initial denaturation at 95 °C for 10 min, followed by 45 amplification cycles consisting of denaturation at 95 °C for 25 s, annealing for 30 s at 56 °C and 55 °C for EYA1 and TBP genes, respectively, and finally an extension at 72 °C for 30 s. For each sample, measurements were taken at least in triplicate. The identity of PCR fragments was further confirmed by agarose gel electrophoresis. The 2DDCt method was used for relative gene expression analysis. Statistical analyses Statistical analyses were performed using SPSS version 16.0. Paired t test or one-way ANOVA with post hoc multiple comparisons was used for the analysis of the differences between groups. A p value of \0.05 was considered statistically significant.
Subjects Results Sixty paired tumor and non-tumor gastric tissue samples were collected from Iran Tumoural Bank (Tehran, Iran) as described previously [22–24]. The experimental design conformed to the Code of Ethics of the World Medical Association (Declaration of Helsinki) and was approved by the Ethics Committee of Isfahan University of Medical Sciences. Prior to participation, all patients provided written informed consent to the Iran Tumoural Bank. Total RNA isolation and cDNA synthesis Extraction of total cellular RNA from tumor and adjacent non-tumor tissue specimens was performed using Qiazol reagent and the RNeasy Mini kit, according to the manufacturer’s instruction (Qiagen, Hilden, Germany). The quality and the concentration of the extracted RNAs were assessed by agarose gel electrophoresis and optical density at 260 nm, respectively. Two micrograms of the extracted RNA was used for cDNA synthesis using MMLV reverse
123
Optimization of PCR amplification In order to gain a specific amplicon for EYA1 gene, optimization was done for both conventional and real-time PCR reactions. Based on a study by Farabaugh et al. [18] that showed the expression of EYA1 in MCF-7 breast cancer cell line, we carried out the optimization of PCR conditions on MCF-7 cell line. Agarose gel electrophoresis of PCR products of EYA1 was showed a specific band with the expected size (117 bp). Also, melting curve analysis of real-time PCR showed that a single product without primer dimers was amplified (data not shown). Expression of EYA1 gene in gastric tissue specimens To analyze the EYA1 gene expression profile in gastric tissues, we carried out quantitative real-time PCR in sixty paired tumor and adjacent non-tumor tissues of the gastric
Med Oncol (2014) 31:955
Page 3 of 5 955 Table 1 Relationship between EYA1 expression levels and clinicopathological parameters of gastric cancer samples Characteristics
Numbers (%)
EYA1 relative expression (mean ± SEM)
Gender
0.41
Male
18 (60)
3.77 ± 0.33
Female
12 (40)
3.64 ± 0.51
C70
15 (50)
3.66 ± 0.25
\70
15 (50)
3.77 ± 0.51
9 (30)
4.16 ± 0.39
21 (70)
3.53 ± 0.36
Mx
15 (50)
2.27 ± 0.78
M0
11 (36.6)
2.00 ± 0.87
M1
4 (13.3)
1.50 ± 0.92
16 (55.17)
4.04 ± 0.37
13 (44.82)
3.13 ± 0.43
Age (years)
0.42
N classification N0 N1–N3
0.15
M classification
Fig. 1 Relative expression of EYA1 in gastric tumor samples compared to their paired non-tumor adjacent tissues. Asterisk represents a statistically significant difference (p = 0.03), and bold horizontal lines represent mean values
carcinoma patients using specific primers for both EYA1 and TBP (as internal control) genes. The results of realtime qRT-PCR experiments demonstrated that the relative expression of the EYA1 gene is significantly decreased in tumor tissues compared with adjacent non-tumor tissues (p = 0.03, Fig. 1). EYA1 expression and clinicopathological factors in gastric carcinoma Next, we investigated the correlation of EYA1 relative gene expression with the selected clinicopathological status of patients with gastric carcinoma (Table 1). The level of EYA1 transcript was downregulated in tumors with a larger size (p = 0.03), with lymphatic invasion (p = 0.04) and with distant metastasis (p = 0.01). However, there was no significant correlation between the expression levels of EYA1 and age, gender, grades or histological classifications.
Discussion Eyes absent (EYA) genes encode dual-functional transactivator-phosphatase proteins. Domains of EYA proteins (the N-terminal transactivation-threonine phosphatase and the C-terminal tyrosine phosphatase domains) are the cause of dual functionality of these proteins [9, 26]. EYA proteins are the transcriptional activators in a conserved
Lymphatic invasion Negative Positive
0.01
0.04
Tumor size (cm)
0.03
C5
20 (68.7)
3.41 ± 0.37
\5
9 (31.3)
4.44 ± 0.39
Grade I
10 (33.3)
4.00 ± 0.44
Grade II
8 (26.6)
3.73 ± 0.25
Tumor grades
Grade III
p value
0.36
12 (40)
3.47 ± 0.59
Diffuse
15 (50)
4.15 ± 0.38
Intestinal
15 (50)
3.28 ± 0.40
Tumor types
0.06
Bold values are statistically significant (p \ 0.05)
regulatory network that plays an important role during development of multiple embryonic organs [27–29]. EYA proteins also involve in other processes such as innate immunity, DNA damage repair, photoperiodism, angiogenesis and cancer metastasis [29]. EYA1 is one of the members of the EYA family. This gene is a human homolog of the Drosophila ‘eyes absent’ gene (EYA) and was therefore called EYA1 [9, 30]. To our knowledge, the expression profile of EYA1 gene in gastric cancer has not been previously investigated. Our pilot study showed that the relative expression of EYA1 gene is significantly decreased in tumor tissues compared with adjacent non-tumor tissues (p = 0.03). Furthermore, the level of EYA1 transcript was downregulated in tumors with a larger size (p = 0.03), with lymphatic invasion (p = 0.05) and with distant metastasis (p = 0.01), and there was no significant correlation between the expression levels of EYA1 and age, gender, grades or histological classification of gastric tumors.
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Until now, deregulation of EYA1 gene has been reported in different cancer types. Increased expression of EYA1 as well as loss of a portion of chromosome 2 (2q37), encoding a microRNA (miR562) that regulates EYA1, has been reported in Wilm’ tumors [19, 31]. In another study by Albino et al. [32], increased expression of EYA1 was detected in stroma-poor neuroblastic tumors. In 2010, Miller et al. [33] showed that EYA1 expresses at increased levels in malignant peripheral nerve sheath tumors (MPNSTs) relative to normal Schwann cells. In contrast to the previous reports based on the tendency for EYA1 to be oncogenic, a study by Matsusaka et al. [21] demonstrated that EYA1 is often methylated and deregulated in both EBV? and EBV-/high gastric tumors. Furthermore, Forster et al. [34] also showed that there is a negative correlation between EYA1 gene expression and metastatic event status during 5 years in gastric tumors. Our results are in accord with Matsusaka et al. and Forster et al. studies [21, 34]. The controversy between different reports may be interpreted as the result of context-dependent expression of EYAs proteins [29, 35] or compensating roles of other EYA genes [29, 36].
Conclusion In summary, this is the first study describing EYA1 gene expression profile in gastric cancer. Our results showed that the gene is underexpressed in gastric tumor samples, and it negatively correlates with tumor size, lymphatic invasion and distant metastasis. Considering these results, this gene might be used as a potential biomarker for monitoring gastric carcinoma progression rate. Further studies to determine the mechanism of action of EYA1 is needed to unravel the role of this gene in gastric cancer pathogenesis. Acknowledgements This study was supported by a research Grant to PN from Isfahan University of Medical Sciences, Isfahan, Iran. Conflict of interest of interest.
The authors declare that they have no conflict
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