IL-10 promoter polymorphisms influence tumour development in cutaneous malignant melanoma

Cutaneous malignant melanoma (CMM) is the most serious cutaneous malignancy. CMM patients often develop an immune response to their tumours. Conflicting evidence suggests that IL-10 may contribute to tumour escape from the immune response, but may also have an anti-tumour effect. To distinguish between these models and to determine whether genotypes associated with differential IL-10 expression confer susceptibility to and/or influence prognosis in CMM, 165 CMM patients and 158 controls were genotyped for IL-10 promoter SNPs by ARMS-PCR. The IL-10--1082 AA low expression genotype was increased in incidence among CMM patients (P = 0.04). In addition, IL-10 genotypes showed significant associations with three of four prognostic indicators examined; IL-10--1082 GG (P = 0.02) and -1082, -819 and -592 compound high expression (P = 0.03) genotypes were associated with horizontal (non-invasive) tumour growth; IL-10--1082 AA low expression genotype was associated with more advanced (Stage II-IV) disease (P = 0.04); finally, the IL-10--1082 AA (P = 0.005) and compound low expression (P = 0.009) genotypes were significantly increased in frequency among patients with thicker primary Vertical growth phase tumours. These results indicate that genotypes associated with high levels of IL-10 expression in vitro are protective in CMM, while low expression genotypes are a risk factor for more advanced/poorer prognosis disease and may confer susceptibility to CMM. Although the influence of IL-10 on melanoma development is likely to be complex, these results support recent findings that IL-10 has an anti-tumour effect in CMM, possibly via inhibition of angiogenesis.