RESUMO
BACKGROUND: Among the sex hormones, oestrogen may play a role in colorectal cancer, particularly in conjunction with oestrogen receptor-ß (ERß). The expression of ERß isoform variants and their correlations with familial adenomatous polyposis (FAP) syndrome and sporadic colorectal carcinomas are poorly described. METHODS: This study aimed to investigate the expression levels of the ERß1, ERß2, ERß4 and ERß5 isoform variants using quantitative RT-PCR (921 analyses) in FAP, normal mucosa, adenomatous polyps and sporadic colorectal carcinomas. RESULTS: Decreased expression of ERß isoforms was identified in sporadic polyps and in sporadic colorectal cancer as well as in polyps from FAP syndrome patients compared with normal tissues (p < 0.001). In FAP patients, ERß1 and ERß5 isoforms showed significant down-expression in polyps (p < 0.001) compared with matched normal tissues. However, no differences were observed when sporadic colorectal carcinomas were compared to normal mucosa tissues. These findings suggest an association of the ERß isoform variants in individuals affected by germline mutations of the APC gene. Progressively decreased expression of ERß was found in polyps at early stages of low-grade dysplasia, followed by T1-T2 and T3-T4 tumours (p < 0.05). In sporadic colorectal cancer, the loss of expression was an independent predictor of recurrence, and ERß1 and ERß5 expression levels were associated with better disease-free survival (p = 0.002). CONCLUSION: These findings may provide a better understanding of oestrogens and their potential preventive and therapeutic effects on sporadic colorectal cancer and cancers associated with FAP syndrome.
