You, YWen, RPathak, RLi, ALi, WSt Clair, DHauer-Jensen, MZhou, DLiang, Y2014-12-022014You, Y, R Wen, R Pathak, A Li, W Li, D St Clair, M Hauer-Jensen, D Zhou, and Y Liang. 2014. “Latexin sensitizes leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway.” Cell Death & Disease 5 (10): e1493. doi:10.1038/cddis.2014.443. http://dx.doi.org/10.1038/cddis.2014.443.2041-4889http://nrs.harvard.edu/urn-3:HUL.InstRepos:13454792Leukemia is a leading cause of cancer death. Recently, the latexin (Lxn) gene was identified as a potential tumor suppressor in several types of solid tumors and lymphoma, and Lxn expression was found to be absent or downregulated in leukemic cells. Whether Lxn functions as a tumor suppressor in leukemia and what molecular and cellular mechanisms are involved are unknown. In this study, the myeloid leukemogenic FDC-P1 cell line was used as a model system and Lxn was ectopically expressed in these cells. Using the protein pull-down assay and mass spectrometry, ribosomal protein subunit 3 (Rps3) was identified as a novel Lxn binding protein. Ectopic expression of Lxn inhibited FDC-P1 growth in vitro. More surprisingly, Lxn enhanced gamma irradiation-induced DNA damages and induced cell-cycle arrest and massive necrosis, leading to depletion of FDC-P1 cells. Mechanistically, Lxn inhibited the nuclear translocation of Rps3 upon radiation, resulting in abnormal mitotic spindle formation and chromosome instability. Rps3 knockdown increased the radiation sensitivity of FDC-P1, confirming that the mechanism of action of Lxn is mediated by Rps3 pathway. Moreover, Lxn enhanced the cytotoxicity of chemotherapeutic agent, VP-16, on FDC-P1 cells. Our study suggests that Lxn itself not only suppresses leukemic cell growth but also potentiates the cytotoxic effect of radio- and chemotherapy on cancer cells. Lxn could be a novel molecular target that improves the efficacy of anti-cancer therapy.en-USJournal Article2014-12-0210.1038/cddis.2014.443