BackgroundDicer is aberrantly expressed in several types of cancers. Applying real-time PCR, we detected the expression of Dicer mRNA in normal mucosa (n = 162), primary colorectal cancer (CRC) (n = 162) and liver metastasis (n = 37), and analysed the relationship between Dicer expression and clinicopathological features. We also correlated the expression of Dicer mRNA to the miRNA expression of miR-141, miR-200a, miR-200b, mir-200c and miR-429 in liver metastases.MethodsRT-PCR and qPCR were used to analyse the Dicer expression in normal mucosa, primary tumour and liver metastasis by using the High Capacity cDNA Reverse Transcription Kit and TaqMan™® Gene Expression assays for Dicer and GAPDH. RT-PCR and qPCR were used to detect miRNA expression in liver metastases by utilizing TaqMan® MicroRNA Reverse Transcription Kit and TaqMan® miRNA Assays. Statistical analyses were performed with STATISTICA.ResultsDicer expression in rectal cancer (3.146 ± 0.953) was higher than in colon cancer (2.703 ± 1.204, P = 0.018). Furthermore the Dicer expression was increased in primary tumours (3.146 ± 0.952) in comparison to that in normal mucosa from rectal cancer patients (2.816 ± 1.009, P = 0.034) but this is not evident in colon cancer patients. Dicer expression in liver metastases was decreased in comparison to that of either normal mucosa or primary tumour in both colon and rectal cancers (P < 0.05). Patients with a high Dicer expression in normal mucosa had a worse prognosis compared to those with a low Dicer expression, independently of gender, age, tumour site, stage and differentiation (P < 0.001, RR 3.682, 95% CI 1.749 - 7.750). In liver metastases, Dicer was positively related to miR-141 (R = 0.419, P = 0.015).ConclusionDicer is up-regulated in the early development of rectal cancers. An increased expression of Dicer mRNA in normal mucosa from CRC patients is significantly related to poor survival independently of gender, age, tumour site, stage and differentiation.

Abstract. MAC30 is highly expressed in several types of tumors including colorectal cancers, however, its clinicopathological and biological significance in colorectal cancers is currently not known. The aim of our study was to investigate MAC30 expression in distant normal mucosa, adjacent normal mucosa, primary tumors and metastases of colorectal cancer, and to determine the relationship between MAC30 expression and clinicopathological and biological variables. MAC30 expression was immunohistochemically examined in distant normal mucosa (n=54), adjacent normal mucosa (n=123), primary tumors (n=217) and lymph node metastases (n=56) from colorectal cancer patients. MAC30 cytoplasmic expression was increased from distant normal mucosa to primary tumor and to metastasis (p<0.0001-0.04). Furthermore, 40% primary and 37% metastatic tumors showed stronger cytoplasmic expression of MAC30 at the tumor invasive margins compared to inner tumor areas. Strong cytoplasmic expression of MAC30 in the metastasis was related to a poor prognosis (p=0.04). MAC30 cytoplasmic expression was positively related to expression of proliferating cell nuclear antigen (p=0.04), p53 (p=0.04), nucleoporin 88 (p=0.001), legumain (p=0.004) and particularly interesting new cysteine-histidine rich protein (p=0.004). However, MAC30 expression in the nucleus and stroma did not have any clinicopathological and biological significance (p>0.05). In conclusion, MAC30 protein may play a role in development of colorectal cancer, and can be considered as a prognostic factor.

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MSI was not a prognostic factor in the Swedish patients included in this study. Clinicopathological variables associated with RIZ mutations might be a consequence of the MSI characteristics.

Polymorphism in SULT1A1 may predispose to colorectal cancer and GSTP1 may be a biological indicator of prognosis in the patients.