6422

SFRP1

secreted frizzled-related protein 1;SFRP1;secreted frizzled-related protein 1

SARP-2|sFRP-1|secreted apoptosis-related protein 2

8p11.21

protein-coding

AIM: To identify the methylation of secreted frizzled-related protein 1 (SFRP1) in gastric cancer and to investigate the aberrant expression of SFRP1 and its correlation with the clinical pathological features of patients. METHODS: We determined SFRP1 methylation and SFRP1 mRNA expression in 3 gastric cancer cell lines SGC-7901, BGC-823, HGC-27, from 52 primary gastric cancer specimens and matched tumor adjacent tissue specimens by methylation-specific (MSP) PCR and RT-PCR respectively. Fishers exact test was used to analyze the statistical association between clinical pathological data and aberrant expression of SFRP1. RESULTS: In 3 cancer cell lines, BGC-823 and HGC-27 had methylated SFRP1 and lost SFRP1 mRNA expression. After treatment of BGC-823 and HGC-27 with the demethylating agent, 5-aza-2-deoxycytidine, SFRP1 was re-expressed. In 52 primary gastric cancer specimens and matched tumor adjacent tissue specimens, hypermethylation of SFRP1 was detected in 23 (44%) and 8 (15%) specimens respectively (chi(2) = 10.34, P < 0.01). Loss of SFRP1 expression was detected in 17(33%) and 6 (12%) specimens respectively (chi(2) = 6.75, P < 0.01). There was a significant correlation between SFRP1 hypermethylation and SFRP1 expression loss. SFRP1 expression was also correlated significantly with tumor stage and lymph node status, but not with patient sex, age and histological type. CONCLUSION: SFRP1 inactivation is a common and early event caused mainly by hypermethylation in gastric cancer. SFRP1 expression loss may be correlated with tumor metastasis in primary gastric cancer.

BACKGROUND: Secreted Frizzled-related protein 1 (sFRP1) is frequently silenced in many types of cancer, including hepatocellular carcinoma (HCC), leading to aberrant activation of Wnt signaling and thereby facilitating tumor development. In this study, we aimed to investigate whether restoration of sFRP1 affected HCC growth and metastasis. METHODS: We generated stable cell lines overexpressing sFRP1 in MHCC97-H cells, which naturally do not express detectable sFRP1 messenger RNA (mRNA) and have high metastatic properties. The effects of sFRP1 reexpression on tumor growth and metastasis were assessed in vitro and in vivo. It was also tested whether beta-catenin signaling mediated the function of sFRP1 in tumor progression. RESULTS: Overexpression of sFRP1 substantially diminished the proliferation and invasion potentials of MHCC97-H cells. Furthermore, sFRP1 expression significantly inhibited MHCC97-H xenograft growth and metastasis in vivo, which was accompanied by decreased angiogenesis and increased tumor cell apoptosis. Moreover, sFRP1 overexpression caused less expression of beta-catenin and its downstream effector genes cyclin D1 and matrix metalloproteinase (MMP)-2. CONCLUSION: Together these findings demonstrate that sFRP1 reconstitution suppresses tumor growth, angiogenesis, and metastasis in MHCC97-H xenografts, which may be associated with inactivation of beta-catenin signaling, thus providing a possible therapeutic strategy against HCC.

The secreted Frizzled-related protein 1 (SFRP1) is a Wingless-type (Wnt) antagonist that has been associated with various malignancies, including renal cell carcinomas (RCC). However, the functional significance of SFRP1 has never been investigated in metastatic RCC. Here, we investigated the role of this molecule in kidney cancer progression and metastasis. Using Wnt pathway-focused cDNA expression profiling in normal renal, primary RCC, and metastatic RCC cell lines, we identified that SFRP1 is up-regulated in metastatic RCC. SFRP1 overexpression in metastatic RCC was confirmed by immunostaining in renal tissues. We explored the molecular mechanisms underlying SFRP1 up-regulation by analyzing DNA methylation and histone modification patterns on SFRP1 promoter. We found that this gene is unmethylated/hypomethylated and enriched in activating histone modifications in metastatic RCC. To understand the functional significance of SFRP1 overexpression in metastatic RCC with regard to tumorigenesis, we used a small interfering RNA-mediated approach to knockdown the gene and monitored cellular proliferation, apoptosis, and metastatic behavior. Proliferation was unaltered and apoptosis increased on attenuation of SFRP1 expression. Also, SFRP1 depletion decreased the invasive potential of the metastatic RCC cell line, suggesting that the overexpression of this Wnt antagonist may be related to invasiveness and metastatic behavior in RCC. We investigated the molecular basis of the role of SFRP1 in invasion and metastasis and found that matrix metalloproteinase MMP10 is regulated by SFRP1. In conclusion, our data suggest that SFRP1 plays a role in the metastatic potential of RCC. The present findings may be important in the design of treatment modalities for metastatic RCC.