Abstract 3822: Targeting TPX2 arrested cell cycle progression, raised multinuclearity, ploidy, and suppresses tumorigenicity in hepatocellular carcinoma cells

Background: Hepatocellular carcinoma (HCC) remains one of the most difficult cancers to treat, with chemotherapies being relatively ineffective. Therefore, a better knowledge of molecular hepatocarcinogenesis will provide the opportunity for designed targeted therapy. TPX2 (targeting protein for Xklp2) are overexpressed as a consequence of oncogenic alterations, and they are likely to alter the proper regulation of chromosome segregation in cancer cells. Attacking the machinery that is responsible for mitotic genes involved chromosome instability in cancer cell is one of the most successful strategies of clinical therapy. For this reason, we consider that the targeting TPX2 of investigation in chromosome segregation and its consequential events could provide the novel therapeutic strategies for cancer. Methods: In human tissue approving, IHC stain addressed the molecular significant of TPX2 in HCC tissue microarray. RNAi was used to knockdown TPX2 protein expression. Clonogenic assay, immunostaining, double thymidine block, image-cytometry analysis, and xenografts mouse model were analyzed its role in tumor cell growth, multinuclearity, ploidy, cell cycle progression and tumorigenicity. RT-PCR, Western blotting were used to analyze anti-cancer mechanism in TPX2 targeting. Results: In this study, TPX2 protein up-expression was present in 16 (42%) of 38 primary HCCs, and associated with high stage, distant metastatic HCCs and poor prognosis (lower 5-year survival). Knockdown of TPX2 inhibited cancer cells growth and result in down-regulation of cyclin A, cyclin E and CDK2 proteins. Targeting TPX2 caused in tested liver cancer cell lines a rising impaired chromosomal instability resulting in multinuclearity and increased poly-ploidy content fraction cells. An image-cytometry analysis revealed a cell cycle progression arrest after TPX2 inhibition. Correlation between down-regulation protein level of genes related to chromosomal segregation such as securin, seprase, Aurora A, Aurora B, cyclin B1 and cyclin B2 and cell ploidy increasing, indicating mitotic phase progression failure and loss the balance of genomic instability. In vitro tumor spheroids assay and in vivo xenografts mouse model showed a therapeutic opportunity in our findings. Conclusion: Our findings suggest that targeting TPX2 deregulates chromosome segregation genes, thereby arrested cell cycle progression, raised multinuclearity, ploidy, and suppresses tumorigenicity in liver cancer cells and suggesting TPX2 as a potential therapeutic target for HCC. Grants support: This work was supported by the grants from Ministry of Science and Technology, Taiwan (MOST103-2320-B-075B-001-MY3 to Hung-Wei Pan), Kaohsiung Veterans General Hospital Research Program, Taiwan (VGHKS103-G01-4, VGHKS104-G01-1 to Hung-Wei Pan, VGHKS103-040 to Chao-Wen Hsu) Citation Format: Hung-Wei Pan, Chao-Wen Hsu, Yu-Chia Chen, Tony Wu. Targeting TPX2 arrested cell cycle progression, raised multinuclearity, ploidy, and suppresses tumorigenicity in hepatocellular carcinoma cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3822.