Promoter polymorphisms in TGFB1 and IL10 genes influence tumor dendritic cells infiltration, development and prognosis of colorectal cancer.

Background: Anti-inflammatory cytokines such as interleukin (IL)-10 and transforming growth factor (TGF)-β1 have a complex role in the development of colorectal cancer (CRC). Dendritic cells (DCs) are the cellular component of the inflammatory microenvironment in the tumor and infiltration of tumors by DCs is associated with better prognosis and fewer metastases.

Methods: In the present study, we explored the role of two single nucleotide polymorphisms (SNPs) in the promoter regions of TGFB1 and IL10 genes and their associations with infiltrating DCs in CRC.A case-control study was designed. Genotyping was performed via the polymerase chain reaction-restriction fragment length polymorphism method and DC infiltration was determined immunohistochemically.

Results: For the TGFΒ1 -509C/T SNP, we found that the T allele was less frequent in patients than in controls (p = 0.031) and the TT-genotype had a 2.74-fold lower risk for CRC than the CC-genotype (odds ratio = 0.365, 95% confidence interval = 0.15-0.88, p = 0.015). Additionally, the TT carriers had the shortest median survival (14.4 months) (p = 0.045). The C-allele genotypes had a significantly longer survival compared to TT carriers (p = 0.018). The CC genotype was associated with a lower cellular density of CD11c in the invasive margin of the tumor (p = 0.033), whereas there was an opposite finding for CD83+ DCs (p = 0.037). Carriers of A-allele genotypes of the IL10 -1080A/G SNP had significantly lower CD83+ cells (p = 0.046) in the tumor invasive margin.

Conclusions: The T-allele of the TGFB1 -509C/T SNP might be a protective factor for development of CRC, although, in the course of the disease, this variant allele might be associated with more unfavorable prognosis of the patients.