Recently, we observed 12,882 new single nucleotide polymorphisms (SNPs) associated with cutaneous melanoma (CM) risk in 103 patients and 103 controls, using large-scale genotyping with microarrays. CREB1 c.303 + 373G>A, involved in melanogenesis and located in regulatory sequence of mRNA processing (splicing), was selected for further analyses. An in silico analysis showed that referred SNP may alters the binding sites of splicing regulatory proteins, such as SF1 and hnRNP A1. However, the role of this SNP in the risk, aggressiveness and prognosis of CM is unknown. Verify whether the distinct genotypes of CREB1 c.303 + 373G>A influence the CM risk and prognosis, clinicopathological aspects, and CREB1, SF1 and HNRNPA1 mRNA levels.
Genomic DNA of 262 patients and 280 controls was analyzed by RT-PCR. Patients were treated with conventional procedures. Gene expressions were determined by qPCR using total RNA of 56 controls. Chi-square, logistic regression model, Mann-Whitney and Student’s t tests analyzed the differences between groups. Progression-free survival (PFS) and overall survival (OS) times were calculated using Kaplan-Meier and Cox regression analyses.
CREB1 GA or AA genotypes were more frequent in CM patients than in controls (72.0% vs. 61.1%, P = 0.02). Carriers of the genotypes were under 1.61-fold increased risk of CM (95% CI: 1.07-2.41) than others. An excess of CREB1 AA variant genotype was seen in patients with Breslow’s thickness higher than 1.5mm (28.2% vs. 18.5%, P = 0.04) and high Clark’s level (26.2% vs. 13.3%, P = 0.02). The median of follow-up of CM patients was 76 months; no association of referred SNP and patients’ PFS and OS was observed in this study. Individuals with CREB1 GA or AA genotypes presented higher mRNA expression of CREB1 (0.94 vs. 0.60 arbitrary units (UAs), P = 0.007), SF1 (1.33 vs. 1.05 UAs, P = 0.03) and HNRNPA1 (0.77 vs. 0.57 UAs, P = 0.02) than those with GG wild-type genotype.
Our data suggest, for the first time, that CREB1 c.303 + 373G>A SNP is an important hereditary factor for the risk and aggressiveness of CM, possibly due to variation of the splicing factors.
Clinical trial identification
Legal entity responsible for the study
University of Campinas
Foundation for protection of research in the state of São Paulo (FAPESP)
All authors have declared no conflicts of interest.