Abstract
We previously reported that the intronic tagSNP +357G/C in the metastasis suppressor HTPAP is associated with metastasis and prognosis of hepatocellular carcinoma (HCC). The aim of this study was to investigate whether SNPs in the HTPAP promoter modulate HTPAP expression and prognosis of HCC. Genomic DNA from 572 microdissected HCCs were genotyped by pyrosequencing and verified by direct sequencing. Haplotype blocks were analyzed. Reporter plasmids were constructed and transfected into HCC cell lines. Transcriptional activities of plasmids were analyzed by dual-luciferase reporter systems. HTPAP expression was measured by real-time quantitative PCR, western blots, and tissue microarrays. Invasion was assessed by Matrigel assays. The prognostic values of HTPAP promoter SNPs in HCC were evaluated by Kaplan-Meier and Cox regression analyses. We identified six SNPs, including -1053A/G and +64G/C, in the HTPAP promoter. The SNPs were in complete linkage disequilibrium, resulting in three promoter haplotypes (promoter I:-1053AA/+64GG, promoter II: -1053AG/+64GC, and promoter III: -1053GG/+64CC). Promoter I manifested the highest luciferase index (p<0.005). However, no significant difference was observed between promoters II and III. We consistently found that HTPAP mRNA and protein levels were significantly higher in promoter I than that of promoter II+III (p<0.001). Invasion was increased in HCC cells transfected with promoters II+III compared to those transfected with promoter I (p<0.05). The HTPAP promoter II+III haplotype was associated with significantly increased metastasis compared to that of promoter I (p = 0.023). The postoperative five-year overall survival of patients with promoters II+III was lower than that of patients with promoter I (p = 0.006). Multivariate analysis showed that the promoter II+III haplotype was an adverse prognostic marker in HCC. The genetic variants at loci –1053 and +64 of the HTPAP promoter affect the expression of HTPAP, which might be a novel determinant and target for HCC prognosis.
Highlights
We previously identified the HTPAP gene, known as PPAPDC1B, as a suppressor of cancer invasion and metastasis in hepatocellular carcinoma (HCC) [1,2,3,4,5]
Among six single-nucleotide polymorphisms (SNPs) in full-length HTPAP, we found that the tagSNP +357G/C may be involved in the regulation of gene expression and metastatic potential of HCC
We found that the intronic tagSNP +357G/C was significantly associated with metastasis and prognosis of hepatocellular carcinoma
Summary
We previously identified the HTPAP gene, known as PPAPDC1B, as a suppressor of cancer invasion and metastasis in hepatocellular carcinoma (HCC) [1,2,3,4,5]. We recently found that a SNP at locus 2443 and related haplotypes in the osteopontin (OPN) promoter region are novel prognostic factors for HCC These polymorphisms significantly increased the promoter activity and expression level of OPN, contributing to HCC progression and metastasis [13]. We investigated whether the other five SNPs, including the two genetic variants in the HTPAP promoter, affected gene expression and tumor metastasis in HCC. The roles that these SNPs play in HCC remain unknown. We investigated the potential associations of specific genotypes in the promoter region of HTPAP with tumor metastasis, recurrence, and clinical prognosis in hepatocellular carcinoma
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
