Prognostic significance of VDR, DKK-1, and DKK-4 expression in colorectal cancer

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e15047 Introduction: Inactivation of the vitamin D receptor (VDR) and up-regulation of its down-stream molecules, Dickkopf-1 (DKK-1) and DKK-4 are implicated in the aggressive progression of colorectal adenocarcinomas (CRC). In this study, the expression of these molecules was evaluated in sporadic CRCs, and their expression levels were assessed for correlation with patient prognosis. Methods: By the qRT-PCR, 98 CRCs and matching normal tissues were analyzed for expression of VDR, DKK-1, and DKK-4 at the mRNA level. These levels were normalized to b-actin expression and calculated as ratios of copy numbers. The expression levels were assessed for correlation with clinicopathological features and for their prognostic importance. The survival probabilities were estimated by the Kaplan-Meier method. Results: VDR expression was 1.5 times lower in CRCs (53 of 98, 54%) than in their corresponding normal tissues. Expression of DKK-1 was found in 51 of 98 (52%) of the CRCs and in 29 of 98 (29%) of the normal tissues. Expression of DKK-4 was found in only 14 of 98 (14%) of the CRCs and in none of the normal tissues. VDR expression was 2.0 fold lower in tumors that exhibited metastasis, and poor differentiation and in large tumors ( > 5) cm as compared to tumors without metastasis, well or moderately differentiated tumors and tumors of small size (< 5 cm), respectively. In contrast, increased (3-fold) expression of DKK-1 and DKK-4 was observed in tumors with distant and/or nodal metastases as compared to tumors without such metastases. Expression of DKK-1 was higher in tumors with poor differentiation and in large tumors. There was an inverse relationship between VDR and DKK-4 expression. Survival analyses suggested that CRCs expressing DKK-1 (log rank, P = 0.046) and those with decreased or lack of expression of VDR (log rank, P = 0.043) were associated with poor patient survival. There was, however, no prognostic value for DKK-4 expression (log rank P=0.624). Conclusions: These findings suggest that, for CRCs, increased expression of DKK-1 and reduced or lack of expression of VDR, are associated with aggressiveness and with a poor prognosis for patients. These results provide evidence augmenting the VDR-DKK- pathway may represent a rational therapeutic strategy in colorectal carcinoma. No significant financial relationships to disclose.