Association of the OCTN1/1672T variant with increased risk for colorectal cancer in young individuals and ulcerative colitis patients

Abstract

Ulcerative colitis (UC) is associated with colorectal cancer. Chronic inflammation may also play a role in the pathogenesis of sporadic colorectal cancer (SCC), particularly in younger patients (<55 years). We evaluated whether single nucleotide polymorphisms of the OCTN1 and OCTN2 genes are associated with UC, SCC, and with UC cases with cancer progression (UCCP). We evaluated the OCTN1 and OCTN2 polymorphisms in 200 patients with UC, 59 patients with UCCP, 200 patients with SCC, and 200 controls (HC). IL-8 expression was also assessed by real-time polymerase chain reaction (PCR). Additionally, we transfected human colon carcinoma Caco2 cells, homozygous for OCTN1/1672T variant, with the OCTN1/1672C allele and NF-κB activity was evaluated by luciferase based reporter assay and IL-8 mRNA expression by real-time PCR. OCTN2 polymorphisms did not present a significant association with any group of patients compared to normal controls. Conversely, homozygosity for the OCTN1/1672T variant was significantly associated with UC (P = 0.047 vs. HC), with UCCP (UCCP vs. HC, P < 0.001), and with SCC developing in early age (<55 years) (P = 0.021 vs. HC). Importantly, IL-8 mRNA expression was higher in UC and UCCP patients homozygous for the OCTN1 1672T variant compared to the other genotypes. Moreover, in Caco2 cells transfection of the OCTN1/1672C variant reduced the activity of the proinflammatory factor NF-κB. Our data demonstrate that OCTN1 could have a role in modulating the severity of chronic inflammation associated with SCC in early age and in UC patients, and that its polymorphisms may help to predict malignant progression of IBD.