Association of Four Interleukin-8 Polymorphisms (-251 A>T, +781 C>T, +1633 C>T, +2767 A>T) with Ovarian Cancer Risk: Focus on Menopausal Status and Endometriosis-Related Subtypes

Abstract

Interleukin-8 (IL-8) is involved in the regulation of inflammatory processes and carcinogenesis. Single-nucleotide polymorphisms (SNPs) within the IL-8 gene have been shown to alter the risks of lung, gastric, or hepatocellular carcinomas. To date, only one study examined the role of IL-8 SNPs in ovarian cancer (OC), suggesting an association between two IL-8 SNPs and OC risk. In this study, we investigated four common IL-8 SNPs, rs4073 (-251 A>T), rs2227306 (+781 C>T), rs2227543 (+1633 C>T), and rs1126647 (+2767 A>T), using the restriction fragment length polymorphism (PCR-RFLP) technique. Our study included a cohort of 413 women of Central European descent, consisting of 200 OC patients and 213 healthy controls. The most common (73.5%) histological type was high-grade serous OC (HGSOC), whereas 28/200 (14%) patients had endometriosis-related (clear cell or endometrioid) OC subtypes (EROC). In postmenopausal women, three of the four investigated SNPs, rs4073 (-251 A>T), rs2227306 (+781 C>T), and rs2227543 (+1633 C>T), were associated with OC risk. Furthermore, we are the first to report a significant relationship between the T allele or TT genotype of SNP rs1126647 (+2767 A>T) and the EROC subtype (p = 0.02 in the co-dominant model). The TT homozygotes were found more than twice as often in EROC compared to other OC subtypes (39% vs. 19%, p = 0.015). None of the examined SNPs appeared to influence OC risk in premenopausal women, nor were they associated with the aggressive HGSOC subtype or the stage of disease at the initial diagnosis.

Keywords: IL-8; endometriosis-related cancer; interleukin-8; ovarian cancer; postmenopause; single-nucleotide polymorphism.

Figure A1

Age distributions of OC cases and controls.

Figure A2

Image of the fragment analyzer electropherograms for representative samples with IL-8 rs4073 (−251 A>T) genotypes A/A (top panel), A/T (middle panel), and T/T (bottom panel). Mfe I restriction fragments were separated with capillary electrophoresis using the Fragment Analyzer™ Automated CE System and the DNF-905 dsDNA Kit. The presence of a fragment at 524 bp suggests the presence of the T/T genotype, while fragments at 449 bp and 75 bp suggest the presence of the A/A genotype. With the A/T genotype, all fragments (524 bp, 449 bp, and 75 bp) are present. UM—upper marker, LM—lower marker.

Figure A3

Image of the fragment analyzer electropherograms for representative samples with IL-8 rs2227306 (+781 C>T) genotypes C/C (top panel), C/T (middle panel), and T/T (bottom panel). EcoR I restriction fragments were separated with capillary electrophoresis using the Fragment Analyzer™ Automated CE System and the DNF-905 dsDNA Kit. The presence of a fragment at 203 bp suggests the presence of the T/T genotype, while fragments at 184 bp and 19 bp suggest the presence of the C/C genotype. With the C/T genotype, all fragments (203 bp, 184 bp, and 19 bp) are present. UM—upper marker, LM—lower marker.

Figure A4

Image of the fragment analyzer electropherograms for representative samples with IL-8 rs2227543 (+1633 C>T) genotypes C/C (top panel), C/T (middle panel), and T/T (bottom panel). NIa III restriction fragments were separated with capillary electrophoresis using the Fragment Analyzer™ Automated CE System and the DNF-905 dsDNA Kit. The presence of a fragment at 397 bp suggests the presence of the T/T genotype, while fragments at 234 bp and 163 bp suggest the presence of the C/C genotype. With the C/T genotype, all fragments (397 bp, 234 bp, and 163 bp) are present. UM—upper marker, LM—lower marker.

Figure A5

Image of the fragment analyzer electropherograms for representative samples with IL-8 rs1126647 (+2767 A>T) genotypes T/T (top panel), A/A (middle panel), and A/T (bottom panel). BstZ17I restriction fragments were separated with capillary electrophoresis using the Fragment Analyzer™ Automated CE System and the DNF-905 dsDNA Kit. The presence of a fragment at 222 bp suggests the presence of the A/A genotype, while fragments at 198 bp and 24 bp suggest the presence of the T/T genotype. With the A/T genotype, all fragments (222 bp, 198 bp, and 24 bp) are present. UM—upper marker, LM—lower marker.