4920

ROR2

BDB|BDB1|NTRKR2;receptor tyrosine kinase-like orphan receptor 2;ROR2;receptor tyrosine kinase-like orphan receptor 2

neurotrophic tyrosine kinase receptor-related 2|tyrosine-protein kinase transmembrane receptor ROR2

9q22

protein-coding

AIM: To investigate the expression and clinical significance of Wnt member 5a (Wnt5a) and receptor tyrosine kinase-like orphan receptor 2 (Ror2) in hepatocellular carcinoma (HCC). METHODS: In HCC tissues obtained from 85 patients, the protein expressions of Wnt5a, Ror2, beta-catenin, and Ki-67 via immunohistochemical staining using the Envision Plus System. The antibody binding was visualized with 3, 3-diaminobenzidine tetrahydrochloride (DAB) before brief counterstaining with Mayers hematoxylin. The degree of immunohistochemical staining was recorded using a semiquantitative and subjective grading system. The mRNA expression of Ror2 was examined by real-time reverse transcription polymerase chain reaction, including nineteen of the 85 HCC and three normal liver tissues. The ratios of Ror2 to the housekeeping gene GAPDH represented the normalized relative levels of Ror2 expression. To determine the prognostic factor, the outcome of the 82 patients was determined by reviewing their medical charts. The overall and disease-free survival rates were estimated using the Kaplan-Meier method and compared with the log-rank test. The prognostic analysis was carried out with univariate and multivariate Cox regressions models. RESULTS: Compared to nontumorous (hepatitis or cirrhotic) tissues, Ror2 mRNA expression was clearly decreased in HCC. Ror2 and Wnt5a protein expressions in the majority of HCC patients (63% and 77%, respectively) was significantly less in tumor tissues, as compared to adjacent nontumorous tissues, and this reduction was correlated with increasing serum alpha-fetoprotein and tumor stage. In 68% (58/85) of the HCC cases, the expression of beta-catenin in tumor tissues was either downregulated in the cellular membrane, upregulated in the cytoplasm, or both. Survival analysis indicated that Wnt5a and Ror2 protein expressions could be regarded as independent prognostic factors for HCC; HCC patients with decreased Wnt5a or Ror2 protein expression had a poorer prognosis than those with elevated Wnt5a and Ror2 expression (P = 0.016, P = 0.007, respectively). CONCLUSION: Wnt5a and Ror2 may serve as tumor suppressor genes in the development of HCC, and may serve as clinicopathologic biomarkers for prognosis in HCC patients.

Through subtraction of tumor-specific CpG methylation, we identified receptor tyrosine kinase-like orphan receptor 2 (ROR2) as a candidate tumor suppressor gene (TSG). ROR2 is a specific receptor or co-receptor for WNT5A, involved in canonical and non-canonical WNT signaling, with its role in tumorigenesis controversial. We characterized its functions and related cell signaling in common carcinomas. ROR2 was frequently silenced by promoter CpG methylation in multiple carcinomas including nasopharyngeal, esophageal, gastric, colorectal, hepatocellular, lung, and breast cancers, while no direct correlation of ROR2 and WNT5A expression was observed. Ectopic expression of ROR2 resulted in tumor suppression independent of WNT5A status, through inhibiting tumor cell growth and inducing cell cycle arrest and apoptosis. ROR2 further suppressed epithelial-mesenchymal transition and tumor cell stemness through repressing beta-catenin and AKT signaling, leading to further inhibition of tumor cell migration/invasion and increased chemo-sensitivity. Thus ROR2, as an epigenetically inactivated TSG, antagonizes both beta-catenin and AKT signaling in multiple tumorigenesis. Its epigenetic silencing could be a potential tumor biomarker and therapeutic target for carcinomas.