55366

LGR4

leucine-rich repeat containing G protein-coupled receptor 4;LGR4;leucine-rich repeat containing G protein-coupled receptor 4

G protein-coupled receptor 48|leucine-rich repeat-containing G-protein coupled receptor 4

11p14-p13

protein-coding

BACKGROUND AND OBJECTIVE: GPR48 regulates invasion and metastasis of cancer cells by linking Gs protein to stimulate intracellular signaling pathway and affect actin filament aggregation and the activity of matrix metalloproteinase. This study was to explore the effects of GPR48 short hairpin RNA (shRNA) on GPR48 expression, and invasion and metastasis of cervical carcinoma cell line HeLa. METHODS: Plasmids containing two different sequences of human GPR48 mRNA coding region were constructed and transfected into HeLa cells. HeLa cell clones with stable small interfering RNA (siRNA) expression were screened by neomycin resistance. The expression of GPR48 was detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. In vitro invasive activity was measured by Boyden chamber experiment. GPR48 shRNA-transfected or untransfected HeLa cells were inoculated subcutaneously into nude mice to observe tumor growth and lung metastasis. RESULTS: Compared with that in negative shRNA-transfected cells, GPR48 mRNA expression in GPR48 shRNA-transfected cells was downregulated by more than 80% and the number of HeLa cells infiltrated Boyden chamber membrane was decreased (94.4 +/- 15.7 vs. 28.3 +/- 1.5 and 17.6 +/- 1.5, p < 0.01). The depletion of endogenous GPR48 suppressed in vivo metastasis: the number of lung metastases was significantly larger in negative shRNA group than in GPR48 shRNA groups (7.3 +/- 1.8 vs. 1.3 +/- 0.3 and 1.5 +/- 0.4, p < 0.01). CONCLUSION: GPR48 shRNA can inhibit in vitro invasion and in vivo metastasis of HeLa cells efficiently.

A reduced expression level of the cyclin-dependent kinase inhibitor p27(Kip1) is associated with increased tumor malignancy and poor prognosis in individuals with various types of cancer. To investigate the basis for this relation, we applied microarray analysis to screen for genes differentially expressed between p27(+/-) and parental (p27(+/+)) HCT116 human colon carcinoma cells. expression of the gene for G protein-coupled receptor 48 (GPR48) was increased in the p27(+/-) cells. Forced expression of GPR48 increased both in vitro invasive activity and lung metastasis potency of HCT116 cells. In contrast, depletion of endogenous GPR48 by RNA interference reduced the invasive potential of HeLa and Lewis lung carcinoma cells not only in vitro but also in vivo. Moreover, GPR48 expression was significantly associated with lymph node metastasis and inversely correlated with p27 expression in human colon carcinomas. GPR48 may thus play an important role in invasiveness and metastasis of carcinoma and might therefore represent a potential prognostic marker or therapeutic target.