Supplementary Figures S1-S7 - PDF file 476K, IHC staining of RBP2 protein in normal and cancerous human lung tissues (S1); Knockdown of RBP2 inhibits growth of lung cancer cell A549 (S2); RBP2 knockdown impairs formation of metastatic nodules in lungs of nude mice (S3); Construction of shRNA-resistant HA-tagged RBP2 plasmids (S4); The protein level of p21 is increased in gastric AGS cell line but decreased in lung cancer cells when RBP2 is depleted (S5); RBP2 knockdown effect on G1 cyclin gene expression and the efficiency of p27 depletion (S6); Successful expression of exogenous ITGB1 in RBP2-depeleted H1299 cells does not restore cell growth defect (S7)
ARTICLE ABSTRACTThe retinoblastoma binding protein RBP2 (KDM5A) is a histone demethylase that promotes gastric cancer cell growth and is enriched in drug-resistant lung cancer cells. In tumor-prone mice lacking the tumor suppressor gene RB or MEN1, genetic ablation of RBP2 can suppress tumor initiation, but the pathogenic breadth and mechanistic aspects of this effect relative to human tumors have not been defined. Here, we approached this question in the context of lung cancer. RBP2 was overexpressed in human lung cancer tissues where its depletion impaired cell proliferation, motility, migration, invasion, and metastasis. RBP2 oncogenicity relied on its demethylase and DNA-binding activities. RBP2 upregulated expression of cyclins D1 and E1 while suppressing the expression of cyclin-dependent kinase inhibitor p27 (CDKN1B), each contributing to RBP2-mediated cell proliferation. Expression microarray analyses revealed that RBP2 promoted expression of integrin-β1 (ITGB1), which is implicated in lung cancer metastasis. Mechanistic investigations established that RBP2 bound directly to the p27, cyclin D1, and ITGB1 promoters and that exogenous expression of cyclin D1, cyclin E1, or ITGB1 was sufficient to rescue proliferation or migration/invasion, respectively. Taken together, our results establish an oncogenic role for RBP2 in lung tumorigenesis and progression and uncover novel RBP2 targets mediating this role. Cancer Res; 73(15); 4711–21. ©2013 AACR.