Associations between polymorphisms in the IL-4 and IL-4 receptor genes and urinary carcinomas: a meta-analysis

Abstract

To evaluate the association between polymorphisms of interleukin-4 (IL-4) and IL-4 receptor (IL-4R) genes and risk of renal cell cancer (RCC), bladder cancer (BC), and prostate cancer (PC) based on meta-analysis. PubMed, Web of Science and SpecilalSCI^TM were searched for studies published up to May 2014 that reported the association between IL-4 or IL-4R and RCC, BC or PC risk. Odds ratio (OR)/Hazard ratio (HR) and 95% confidence interval (CI) were analyzed to evaluate the association. Meta-analysis showed that the IL-4R polymorphism rs1805010 was associated with increased RCC risk (CC/CT vs. TT: OR=1.266, 95% CI 1.09-1.472, P=0.002). The IL-4 haplotypes, IL4-589T and IL4-33T, were associated with higher survival rate of the patients comparted with the haplotype IL-4-589C-33C (P<0.05). The IL-4 polymorphism rs2243250 was associated with an increased risk of developing multiple BCs (OR=2.52, P=0.033). The IL-4 polymorphisms rs2243228, rs2243250, and rs22272480 were significantly associated with PC risk (rs2243228 CC vs. CA/AA: OR=0.27, 95% CI 0.09-0.84, P=0.03; rs2243350 TT vs. CT/CC: OR=2.16, 95% CI 1.06-4.40, P=0.03, CC vs. CT/TT: OR=1.31, 95% CI 1.05-1.65, P=0.02; rs2227284 TT vs. GT/GG: OR=1.98, 95% CI 1.30-3.00, P=0.001). In addition, IL-4 polymorphism rs2070874 was associated with PC mortality. Three polymorphisms (rs2070874, rs1805015, and rs1801275) were not associated with RCC, BC, and PC. The IL-4R polymorphism rs1805015 might be associated with RCC risk. IL-4 rs2243250 carriers had increased risk of developing multiple BCs. IL-4 polymorphisms rs2243228, rs2243250, rs2227284, and rs2070874 were associated with PC risk or mortality.

Introduction

The cancer incidence is increasing worldwide. It has been estimated that a total of 14.1 million new cases and 8.2 million deaths caused by cancers occurred in 2012 (http://globocan.iarc.fr/Pages/fact_sheets_cancer.aspx). According to the human development index, it is predicted that cancer cases will have been increasing from 12.7 million in 2008 to 22.2 million by 2030 [1]. Cancers are multifactorial diseases involved in complicated interactions of genetic and environment factors [2]. Gene mutation is one of the most important risk factors of cancer. Single nucleotide polymorphisms (SNPs) contribute to carcinogenesis in various ways, such as affecting the function of cytokines involved in immune responses and inflammatory reaction, influencing the binding of nuclear factors with target genes, and inhibiting apoptosis [3,4].

Interleukin-4 (IL-4), a member of the α-helical cytokine family, is produced by activated CD4+ T cells, basophils, and mast cells. IL-4 is the central differentiation factor driving Th2 development, eliminating extracellular pathogens, and inhibiting Th1 differentiation. Therefore, IL-4 plays an important role in surveillance and elimination of transformed cells [5]. Numerous epidemiologic studies have examined the association of IL-4 gene polymorphisms with cancer risk. For example, the IL-4 -590C>T (rs2243250) polymorphism on the promoter region [6] contributed to threefold higher transcriptional activity both in vitro and in vivo [7]. This SNP has been explored in several types of carcinomas such as oral cancer [8], colorectal cancer [9], and lung cancer [10].

IL-4 receptor (IL-4R) is a heterodimeric complex that can bind to the Th2 cytokines IL-4 and IL-13 [11]. High level expression of IL-4R has been observed in colorectal carcinoma [12]. In addition, polymorphisms of IL-4R were involved in the etiology of various cancers, including pancreatic cancer and cervical cancer [13,14]. In the present study, a systematic meta-analysis was conducted to explore the role of IL-4 and IL-4R polymorphisms in the pathogenesis of RCC, BC and PC.

Methods

Literature search

Eligible studies up to May 2014 were independently identified and extracted by two investigators from the database of NCBI PubMed, Web of Science and SpecilalSCI^TM. Discrepancies in data interpretation were resolved by discussion, review of the studies, and consultation with two cancer research experts when necessary. The keywords used for literature search are as follows: (IL-4 OR Interleukin-4 OR IL4) AND (SNP OR mutation OR variant OR polymorphism) AND (prostate OR renal OR kidney OR bladder) AND (carcinoma OR cancer OR tumor). The search was not limited to English language articles. In addition, studies cited in the reference lists were also identified by a manual search.

Studies included in our meta-analysis meet the following inclusion criteria: i) studies about SNP(s) of IL-4 and/or IL-4R; ii) patients with renal cancer, prostate cancer or bladder cancer; iii) sufficient genotype distributions for cases and controls so that an odds ratio (OR) with 95% confidence interval (CI) can be assessed. Studies without the number of genotype, but having OR and 95% CI, were also included in the meta-analysis. Of studies published the same case series, we selected the most recent ones with the largest sample size.

Statistical analysis

Pooled OR and 95% CI were used to estimate the strength of association between the SNPs of IL-4 and IL-4R and cancer risk.

Heterogeneity was evaluated by a χ²-based Q statistic. Statistical significance was determined as P value less than 0.05. When P value was above 0.05, OR was pooled using the fixed-effect model, otherwise the random effect model was used. The statistical significance of OR was analyzed by Z test and P value less than 0.05 was considered statistically significant.

Results

Database of meta-analysis

A total of 166 publications were identified after initial screening based on the above criteria. Among these, 15 articles were subjected to further examination after reading the titles and abstracts. Two studies were excluded from the meta-analysis as one published in Spanish and another one that used smaller sample size of cancer patients than other studies. Finally, 13 articles (Figure 1) including five studies of renal cancer [11,15-18], four studies about bladder cancer [19-22], and four studies of prostate cancer were included in this meta-analysis [23-26].

Figure 1.

A flow diagram of the selection and disposition of published studies on the association of IL-4 and IL-4R polymorphisms with cancer risks.

Quantitative analysis of IL-4 polymorphisms

Polymorphism IL-4 C-590T (rs2243250) was identified in two studies of RCC (747 RCC patients and 797 controls) and two studies of BC (954 BC patients and 1245 controls). For RCC cases, the fixed model was used to analyze the patterns of CC vs. CT/TT, CC/CT vs. TT and T vs. C as heterogeneity was not identified in these studies (I²=0%, Table 1). No significant differences were observed between RCC patients and controls (P=0.238, P=0.345 and P=0.165). For BC cases, the random model was used to analyze the three patterns as heterogeneity was identified (I²=71.2%, 92.5% and 92.1%). No significant differences were observed between BC patients and controls (P=0.558, 0.313 and 0.319).

Table 1.

The association between polymorphisms in the IL-4/IL-4 receptor gene and urinary carcinomas

SNP	Carcinoma	Pattern	OR/HR (95% CI)	P	Reference
IL-4
rs2243228	PC	CCvs. CA/AA	0.27 (0.09-0.84)	0.03	[25]
rs2243250	PC	TT vs. CT/CC	2.16 (1.06-4.40)	0.03	[26]
		CC vs. CT/TT	1.31 (1.05-1.65)	0.02	[26]
rs2227284	PC	TT vs. GT/GG	1.98 (1.30-3.00)	0.001
rs2070874#	PC	CC vs. CT/TT	2.16 (1.27-3.67)	0.005	[24]
			1.27 (1.04-1.56)	0.011
IL-4R
rs1805010	RCC	CC vs. CT/TT	1.266 (1.09-1.472)	0.002	[12,16,17]
rs2243250*	BC	T vs. C	2.80 (1.08-7.27)	0.031	[21]

Note: The non-significant difference between SNPs of IL-4/IL-4R and cancer was not shown.

^#This study was a cohort study and the significant difference in different population (Seattle and Swedish).

^*This SNP was associated with the developing multiple BC.

Quantitative analysis of IL-4R polymorphisms

Polymorphisms IL-4R rs1805010, rs1805015, and rs1801275 were identified in three studies of RCC, two studies of BC, and one study of PC. A total of 813 RCC patients and 879 controls were in included in the studies of IL-4R rs1805010 polymorphism. A total of RCC 620 patients and 623 controls were included in the IL-4R rs1805015 polymorphism, and 1626 RCC patients and 1758 controls were included in the IL-4R rs1801275 polymorphism. The fixed model was used to analyze the rs1805010 polymorphism because heterogeneity was not identified in the pattern of CC vs. CT/TT (I²=21.4%, Table 1). Heterogeneity was identified in the pattern of CC/CT vs. TT (I²=84%) and T vs. C (I²=84.1%). Significant differences were observed in the pattern of CC vs. CT/TT between RCC patients and controls (OR 1.266, 95% CI 1.09-1.472, P=0.002), while no significant was identified in the patterns of CC/CT vs. TT (P=0.866) and C vs. T (P=0.972). The random model was used to analyze the rs1801275 polymorphism because heterogeneity was identified in the patterns of AA vs. AG/GG (I²=58.8%), AA/AG vs. GG (I²=32.7%) and A vs. G (I²=56.7%). No significant differences were identified in the patterns of AA vs. AG/GG (P=0.581), AA/AG vs. GG (P=0.669) and A vs. G (P=0.483).

A total of 1440 bladder carcinoma patients and 1762 controls were included in the studies of IL-4R rs1801275 polymorphism. The random model was used to analyze the rs1801275 polymorphism because heterogeneity was identified in the patterns of of AA vs. AG/GG (I²=65%) and A vs. G (I²=39.6%). The fixed model was used to analyze the pattern of AA/AG vs. GG (I²=0%) because heterogeneity was identified. No significant differences were identified in the patterns of AA vs. AG/GG (P=0.554), AA/AG vs. GG (P=0.23) and A vs. G (P=0.795).

Other polymorphisms of IL-4 and IL-4R

The IL-4R rs1805015 polymorphism was investigated in one study including 620 RCC patients and 623 controls [15]. No significant differences of the genotype distribution of TT, CT, and TT (P=0.125), and the C allele (P=0.942) were observed between RCC patients and controls. In addition, a cross-sectional single-center study including 80 metastatic RCC patients showed that the promoter region of IL-4 haplotype (IL4-589T and IL4-33T) was highly associated with the survival rate of RCC patients [18]. The median overall survival decreased 3.5-fold (P<0.05) in heterozygote patients carrying IL-4 haplotype -589T-33T and -589C-33C (3.78 months) compared with homozygote patients carrying IL-4 haplotype -589C-33C (13.44 months).

In a study of the rs1805015 polymorphism, no significant differences of the genotype distribution (TT, CT and TT) (P=0.376) and the C allele (P=0.787) were identified between 816 bladder carcinoma patients and 1140 controls [19]. However, a case-control study showed that IL-4 rs2243250 carriers had an increased risk of developing multiple bladder carcinomas in the pattern T vs. C (OR 2.80 05% CI 1.08-7.27), P= 0.031) [20].

In a case-control study of the IL-4 rs2243228 polymorphism, no significant differences of the pattern of CC vs. CA/AA (OR=0.27, 95% CI 0.09-0.84, P=0.03) were observed between prostate carcinoma patients and 1351 controls [24]. Significant differences of the genotype distribution of IL-4 polymorphisms rs2243250 and rs2227284 were identified between 825 prostate carcinoma cases and 732 controls [25]. For each polymorphism, ORs of two allele were 1.32 (95% CI 1.08-1.61) and 1.26 (95% CI 1.07-1.48), respectively. The rs2243250 polymorphism was significantly associated with cancer risk in the patterns of TT vs. CT/CC (OR=2.16, 95% CI 1.06-4.40, P=0.03) and CC vs. CT/TT (OR=1.31, 95% CI 1.05-1.65, P=0.02), whereas rs2227284 was significantly associated with cancer risk only for TT vs. GT/GG (OR=1.98, 95% CI 1.30-3.00, P=0.001). In the included cohort study, another IL-4 polymorphism rs2070874 was also associated with the mortality of prostate cancers in different populations (CC vs. CT/TT for the Seattle Cohort: HR=2.16, 95% CI 1.27-3.67, P=0.005; For Swedish Cohort: HR=1.27, 95% CI 1.04-1.56, P=0.011) [23].

Discussion

IL-4 and IL-4R play essentials roles in the development of a many carcinomas. Numerous studies have investigated the association between IL-4 or IL-4R polymorphisms and cancer risk or mortality. In the present study, we performed a meta-analysis including 13 studies to review the association between IL-4 or IL-4R polymorphisms and risk of RCC, bladder carcinoma, and prostate carcinoma.

Our meta-analysis revealed that the IL-4 C-590T variant (polymorphism rs2243250) was not associated with RCC risk, which is not consistent with previous report in which polymorphism rs2243250 was associated with increased RCC risk (TT vs. CC/CT: OR=1.43, 95 % CI 1.05-1.95, P=0.022) [27]. This discrepancy might be explained by the fact that our meta-analysis included larger population and was based on two studies conducted in China and Spain, respectively. Carcinogenesis is a complex process in which many genes and environmental factors are involved. Therefore, the association of IL-4 polymorphism rs2243250 should be further studied and interpreted with cautions. Regarding the IL-4R polymorphisms, only rs1805010 was associated with significantly decreased RCC risk in the pattern of CC vs. CT/TT. The underlying mechanism of the association of IL-4R polymorphism rs1805010 with decreased RCC was not fully understood. The recent study reported that IL-4R blockade abrogates satellite cells, leading to rhabdomyosarcoma fusion and preventing tumor establishment in muscle-related cancers [28]. In addition, it has also been reported that IL-mediated significant antitumor effects in animal model of human head and neck squamous cell carcinoma [29]. While the association of other polymorphisms of IL-4 and IL-4R with cancer risk was not found in the present study, the survival rate of patients with homozygote for IL4 haplotype -589C-33C was significantly longer than other patients. Probable explanation is that IL4 polymorphisms was in strong linkage with KIF3A that plays a key role in the metastasis of tumor cells and genetic inactivation of KIF3A in mice inhibited renal ciliogenesis and caused polycystic kidney disease [30,31].

No significant association of IL-4 and IL-4R polymorphisms with bladder carcinoma risk was identified in the present meta-analysis. However, IL-4 polymorphism rs2243250 had a strong association with developing multiple carcinomas in bladder cancer patients. This may be explained by the fact that IL-4 promotes the expansion of Th2 cells in bladder cancer patients and leads to the suppression of Th1 responses [32]. The generation of effector cytotoxic T lymphocytes was required to suppress tumors by lysing cancer cells and subsequently decreasing immune surveillance against tumors [32,33]. In addition, patients with the IL-4-590 T allele seem to have a higher production of IL-4 [34], which may induce immunosuppression against tumors (Th1 inhibition). Therefore, IL-4 may be involved in cancer cell escape from lymphocyte killing and the development of multiple tumors in bladder urothelium [35].

To the best of our knowledge, this is the first comprehensive meta-analysis investigating the association of IL-4 and IL-4R polymorphisms and prostate carcinoma. Recently, four IL-4 polymorphisms were found to be associated with prostate carcinoma. Three polymorphisms (rs2243228, rs2243250 and rs2227284) were associated with cancer risk and the polymorphism rs2070874 was associated with cancer mortality. The growth of prostate cancer cells depends mainly on hormones, notably androgen. IL-4 may be involved in androgen-independent tumor progression [36-39].

When interpreting the results of the present meta-analysis, several limitations should be considered. First, a limited numbers of studies on the association of IL-4 and IL-4R polymorphisms and RCC, bladder carcinoma, and prostate carcinoma were available, practically in prostate carcinoma. Studies of these polymorphisms in a large number of European countries were not available, especially for RCC. Third, the literature searches were carried out in only three databases (NCBI PubMed, Web of Science and SpecilalSCI^TM), which may miss some important studies in other languages and database.

In summary, our results suggest that the IL-4R polymorphism rs1805015 is associated with RCC risk. IL-4 rs2243250 carriers had an increased risk of developing multiple bladder carcinomas. IL-4 polymorphisms rs2243228, rs2243250, rs2227284, and rs2070874 were associated with prostate cancer risk and mortality. Given the limitations mentioned above, we encourage more studies to further study the association of IL-4 and IL-4R polymorphisms with cancers, which will also contribute to our understanding of the role of IL-4 and IL-4R in carcinogenesis.

Disclosure of conflict of interest

None.