Abstract 2932: Role of P53 in the negative regulatory function of PIAS3 with STAT3 in lung cancer

Abstract

Abstract Constitutive activation of Signal Transducers and Activators of Transcription 3 (STAT3) and p53 mutations both play an important role in lung cancer pathogenesis. We have demonstrated a negative inhibitory role of Protein Inhibitor of Activated STAT3 (PIAS3) in STAT3 signaling (Kluge et al 2009 and Dabir et al. 2009) in lung cancer. Recent data suggests that p53 plays a role in oncogenic STAT3 signaling. We sought to determine the biochemical interaction between PIAS3, STAT3 and p53 at both protein and DNA levels in p53 wild-type (A549 and H1666), mutant (Calu1) and p53 null (H358) non-small cell lung cancer (NSCLC) lines. We demonstrate that PIAS3 binds to STAT3 under Epidermal Growth Factor (EGF) stimulation in p53 WT cell lines but not so significantly in p53 mutant cell lines. ChIP studies with PIAS3 antibody showed p53/PIAS3 binding to DNA under EGF stimulation. We observed in vivo binding of PIAS3 to the promoter region of RNSP1 (target of p53) in A549 (p53 WT) cells by Promoter Tiling Array. Our initial data suggests that PIAS3 negative regulatory effect on STAT3 is more prominent in p53 WT cells. Indeed, transfection of WT cells with a PIAS3 construct results in a significant decrease in STAT3 transcriptional activity in all cells but more significantly in WT cells. Knockdown of p53 using sh-p53 lentivirus construct tagged with GFP in p53 WT cells shows that it partially negates the effects of PIAS3 on STAT3 suggesting at least a partial requirement of WT p53 for full PIAS3 effects on STAT3 signaling. However our data suggests that PIAS3 induces apoptosis as demonstrated by TUNEL assay and changes of Bcl2 family members irrespective of p53 status suggesting that its growth inhibitory effects are p53 independent. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2932. doi:10.1158/1538-7445.AM2011-2932