Abstract 2346: The expression of ASPP2 and its new isoform delta-ASPP2 in HCC

Purpose: Although full-length ASPP2 is necessary to stimulate p53-dependent apoptosis efficiently, the precise mechanisms and cell contexts that enable this function remain to be clarified. In recent study, we found a new ASPP2 isoform (ΔN-ASPP2) may play an important role in regulating the ASPP2-p53 axis. The present study was undertaken to investigate the expression of isoform of ASPP2 in liver tumor and it would be a domain negative regulation of ASPP2 and would be prognostic significance in HCC. Experimental Design: 120 HCC tissues and same amount of nonneoplastic liver tissues were analyzed for ASPP2 alone and ASPP2 plus ΔN-ASPP2 mRNA expression by real-time RT-PCR. The ΔN-ASPP2 mRNA was analyzed by RT-PCR and real-time RT-PCR with ΔN-ASPP2 specific forward primers. ASPP2 plus ΔN-ASPP2 P53 downstream effectors of the apoptotic and cell cycle arrest pathway (BAX and P21) were studied in 100 HCC specimens. Results: The expression of ASPP2 and ΔN-ASPP2 mRNA levels were highly variable in HCC tissues. There was no association between the ASPP2/ ΔN-ASPP2 mRNA level and the p53 status. Expression of full length ASPP2 in pairs were detected in 62 HCC and its adjacent tissue.ASPP2-full mRNA level is significant lower in HCC than that in the tumor surrounding tissue (P=0.0159). Expressions of ΔN-ASPP2 mRNA, ASPP2-total (ASPP2, ΔN-ASPP2 and 53BP2), BAX and P21 in pairs were compared between 72 of HCC and their adjacent tissue. The results showed that ΔN-ASPP2 mRNA (P=0.0435) is significantly higher and ASPP2-total (P=0.0212), BAX (P=0.0057) and P21 (P=0.002) are significantly lower in HCC than that in adjacent tissue. CONCLUSIONS: The high level ΔASPP2 which is in contrast to ASPP2 function and low level ASPP2-full which is a p53 activator in HCC would play an important role in tumor development and tumor senescence. Citation Format: Ying Shi, Kai Liu, Huiguo Ding, Fudong Lv, Charles Lopez, Ning Li, Dexi Chen. The expression of ASPP2 and its new isoform delta-ASPP2 in HCC. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2346. doi:10.1158/1538-7445.AM2014-2346