Downregulation of DACT-2 by Promoter Methylation and its Clinicopathological Significance in Prostate Cancer

Abstract

Backgrounds : Dapper homolog (DACT) 2, a member of DACT gene family, is frequently down-regulated in various malignancies and linked to tumor progression. However, the regulatory mechanism of DACT-2 expression and its biological role in human prostate cancer (PCa) remains elusive. Here, we investigated the expression and an epigenetic change of DACT-2 in prostate cancer, and determined if these findings were correlated with clinicopathologic characteristics of PCa. Methods : The expression profile of DACT-2 of was detected by qRT-PCR, Western blotting, and immunohistochemistry in four prostate cell lines (RWPE-1, LNCaP, PC-3 and DU145), 56 cases of frozen prostate tissues (forty-seven primary prostate carcinomas, nine paired noncancerous and cancerous prostate tissues) and a tissue microarray sets including 100 paraffin-embedded prostate samples (3 normal tissues, 2 cases of adjacent tissues and 95 cases of cancer). Subsequently, the regulatory mechanism of DACT-2 down-regulation was investigated through methylation-specific PCR (MSP) and bisulfite sequencing (BSP). The role of DACT-2 in prostate cancer cell migration and invasion was respectively examined by wound healing and transwell assay. After 5-aza-2'-deoxycytidine treatment of prostate cancer cells, qRT-PCR was used to detect whether the expression of DACT-2 gene mRNA in the cells recovered. Results : Immunohistochemical results shown that the DACT-2 protein was strongly (3+) expressed in the cytoplasm of all 5 noncancerous tissues and 12.7% (12/95) prostate cancer (PCa) tissues. Whereas 68.4% (65/95) PCa samples and 18.9% (18/95) PCa tissues respectively displayed weakly (1+) expressed and moderately (2+) expressed. In addition, DACT-2 expression was negatively associated with Gleason score in tumor specimens ( p =0.029). What's more, down-regulation and promoter methylation of DACT-2 were observed in 68.1% (32/47) frozen PCa tissues and all three prostate cancer cell lines. And, the expression of DACT-2 mRNA was restored by the treatment of demethylated drug 5-aza-2'-deoxycytidine in all prostate cancer lines. Prostate cancer cells invasion and migration were significantly suppressed by ectopic expression of DACT-2 in vitro . Conclusions : Our study provides evidence that DACT-2 may be a useful biomarker for distinguishing prostate tumor tissues from non-cancerous samples and a potential target for epigenetic silencing in primary prostate Cancer.

Diagnostic value of DACT-2 methylation in serum of prostate cancer patients

“…It is hypothesized that DACT-2 may be a potential tumor suppressor gene involved in tumor progression. Our previous studies have also confirmed that DACT-2 is downregulated by methylation in both prostate cancer cells and prostate cancer tissues (24). However, it is unclear whether the presence of DACT-2 gene methylation is present in the serum of patients with PCa.…”

Epigenetically silenced DACT3 promotes tumor growth via affecting Wnt/beta-catenin signaling and supports chidamide plus azacitidine therapy in acute myeloid leukemia

“…Previous studies have found that, the expression of DACT1 or DACT2 was reduced in various solid tumors, and was identified as a tumor suppressor genes [26,27,79]. It has been reported that DACT3 is transcriptionally inhibited and is a negative regulator of the Wnt/β-catenin signaling pathway in colorectal cancer [30].…”

“…Mechanisms of DACT down-regulation are proved to be associated with epigenetic regulation in these tumors, including promoter methylation and histone modification. Furthermore, DACT is recognized as a tumor suppressor of Wnt/β-catenin pathway [25][26][27]. However, the role and epigenetic regulation mechanism of DACT family members are different in various tumors.…”

The Role of DACT Family Members in Tumorigenesis and Tumor Progression

“…Additionally, the expression level of DACT2 was significantly reduced in primary esophageal cancer samples compared with adjacent normal esophageal mucosa, and further statistical analysis showed that the frequency of DACT2 silencing significantly correlated with differentiation and prognosis of ESCC [49][50][51]. Moreover, the decreased expression of DACT2 is closely correlated with the invasion, metastasis, occurrence, and development of gastric cancer, prostate, and papillary thyroid cancer [52][53][54][55]. Similarly, based on our findings, DACT2 was significantly down-expressed in glioma tissues compared with normal brain tissues and the paired adjacent tissues [16].…”