Identification and Functional Analysis of A Novel Candidate Oncogene RAP2B in Lung Cancer

Background and objective RAP2B is one of the 50 novel candidate genes cloned from the differential expression cDNA libraries constructed in lung cancer cells. Though RAP2B contains conserved domain and belongs to Ras superfamily, the function of RAP2B in carcinogenesis is still poorly understood. The aim of this study is to explore the roles of RAP2B gene in carcinogenesis. Methods RT-PCR was applied to examine transcriptional status of RAP2B in the tumor and corresponding adjacent tissues collected from 27 patients with lung squamous cell carcinoma.RAP2B expression plasmid was constructed and transfected into Rat1 cells to evaluate the in vitro transformation ability through colony formation assay. Reporter gene assay was performed to reveal the relationship between RAP2B gene and NF-kappaB pathway. Results About 67% (18/27) of tumor tissues show higher mRNA expression than that in the corresponding adjacent normal tissues. Typical transforming focus formation was observed in Rat1 cells which were transfected with RAP2B gene. The reporter gene assay data showed that RAP2B activated NF-kappaB pathway more than 3 folds compared with the mock vector. Conclusion RAP2B may be a novel candidate oncogene that plays important roles in carcinogenesis through activation of NF-kappaB pathway.