Supplementary Material for: PNAS-2: A Novel Gene Probably Participating in Leukemogenesis

Objective:As₄S₄ is an effective drug for the treatment of acute promyelocytic leukemia but its mechanism of action remains largely unknown. In a previous study, we identified PNAS-2, a human apoptosis-related protein gene, using gene expression profiling. In this study, we tried to clarify the role of PNAS-2 in apoptosis and leukemogenesis. Methods: NB4 and U937 leukemia cell lines and serial clinical samples were studied. RNA interference (RNAi) and RNA overexpression were used to address the potential role of PNAS-2 in apoptosis. PNAS-2 expression was examined using Northern blot in multiple tissues, and real-time PCR was applied to analyze PNAS-2 expression in various patient samples. Results: Functional analyses of PNAS-2 by RNAi and RNA overexpression indicate PNAS-2 is an anti-apoptosis gene. PNAS-2 expression is significantly increased in de novo or relapsed acute leukemia, but in patients in complete remission PNAS-2 levels decrease to levels comparable to those found in normal controls. In carcinomas, PNAS-2 expression was not upregulated, indicating that PNAS-2 overexpression was specific for leukemia. Conclusion: Based on the preliminary data, we suggest that the PNAS-2 gene functions as an anti-apoptotic gene and probably participates in leukemogenesis.