Purification and characterization of the extracellular region of human receptor tyrosine kinase like orphan receptor 2 (ROR2)

Expression of Wnt5a and ROR2, Components of the Noncanonical Wnt-Signaling Pathway, is Associated with Tumor Differentiation in Hepatocellular Carcinoma

BACKGROUND

Wnt5a is the key ligand of the noncanonical Wnt pathway, and receptor tyrosine kinase-like orphan receptor 2 (ROR2) is a receptor associated with Wnt5a. The association between the noncanonical Wnt-signaling pathway and carcinogenesis in hepatocellular carcinoma (HCC) is unclear. This study investigated the significance of ROR2 expression in HCC.

METHODS

The study examined ROR2 expression in liver cancer cell lines. Immunohistochemical staining of ROR2 was performed on 243 resected HCC specimens. The study investigated ROR2 expression and its association with clinicopathologic factors and prognosis.

RESULTS

Findings showed that ROR2 was expressed in well-differentiated Huh7 and HepG2 cells, but not in poorly differentiated HLE and HLF cells. Expression of ROR2 was positive in 147 (60.5%) and negative in 96 (39.5%) HCC specimens. A significant association was shown between ROR2 negativity and high alpha-fetoprotein (AFP) level (P = 0.006), poor differentiation (P = 0.015), and Wnt5a negativity (P = 0.024). The 5-year overall survival (OS) rate for the ROR2-negative group (64.2 %) tended to be worse than for the ROR2-positive group (73.8%), but the difference was not significant (P = 0.312). The 5-year OS rate was 78.7% for the ROR2+Wnt5a+ group, 71.3 % for the ROR2+Wnt5a- group, 80.8% for the ROR2-Wnt5a+ group, and 60.5 % for the ROR2-Wnt5a- group. The OS in the ROR2-Wnt5a- group was significantly poorer than in the ROR2+Wnt5a+ group (P = 0.030). The multivariate analysis showed that Wnt5a-ROR2- was an independent prognostic factor (hazard ratio, 2.058; 95% confidence interval, 1.013-4.180; P = 0.045).

CONCLUSIONS

The combination of ROR2 and Wnt5a may be a prognostic indicator for HCC. The Wnt5a/ROR2 signal pathway may be involved in the differentiation of HCC. This pathway may be a new therapeutic target for HCC.

A ROR2 coding variant is associated with craniofacial variation in domestic pigeons

Vertebrate craniofacial morphogenesis is a highly orchestrated process that is directed by evolutionarily conserved developmental pathways.1,2 Within species, canalized development typically produces modest morphological variation. However, as a result of millennia of artificial selection, the domestic pigeon displays radical craniofacial variation within a single species. One of the most striking cases of pigeon craniofacial variation is the short-beak phenotype, which has been selected in numerous breeds. Classical genetic experiments suggest that pigeon beak length is regulated by a small number of genetic factors, one of which is sex linked (Ku2 locus).3-5 However, the genetic underpinnings of pigeon craniofacial variation remain unknown. Using geometric morphometrics and quantitative trait locus (QTL) mapping on an F2 intercross between a short-beaked Old German Owl (OGO) and a medium-beaked Racing Homer (RH), we identified a single Z chromosome locus that explains a majority of the variation in beak morphology in the F2 population. Complementary comparative genomic analyses revealed that the same locus is strongly differentiated between breeds with short and medium beaks. Within the Ku2 locus, we identified an amino acid substitution in the non-canonical Wnt receptor ROR2 as a putative regulator of pigeon beak length. The non-canonical Wnt pathway serves critical roles in vertebrate neural crest cell migration and craniofacial morphogenesis.6,7 In humans, ROR2 mutations cause Robinow syndrome, a congenital disorder characterized by skeletal abnormalities, including a widened and shortened facial skeleton.8,9 Our results illustrate how the extraordinary craniofacial variation among pigeons can reveal genetic regulators of vertebrate craniofacial diversity.