Protein protein interaction of p53 and p73 with YY1 in human hepatocellular carcinoma

Introduction: We have previously described a relevant role of the p53 family members in tumorigenesis, therapeutic response and prognosis of hepatocellular carcinoma (HCC). Since protein interaction networks play a key role in signaling pathways of different tumor entities we used the LUMIER-assay (LUminescence-based Mammalian IntERactome mapping) which is a high-throughput technology to identify protein protein interactions of the p53 family in HCC. Methods and results: First we established the LUMIER-assay in Hep3B cells to be able to map protein interaction networks in liver cells and apply it to the p53 and p73 pathway. A set of relevant proteins from extrinsic and intrinsic apoptosis signaling pathways, cell cycle and proliferation control was selected using the Ingenuity Pathway Analysis System and the BIOGRID database. Selected proteins were transiently expressed in Hep3B cells using GATEWAY-compatible ORF clones. Positive interactions were further analysed and verified by co-immunoprecipitations.Among the protein protein interactions newly identified, the interaction of p53 with YY1 (Ying Yang 1) and the interaction of p73 with YY1 was most notable. YY1 is known as a transcription factor and as a negative regulator of p53. YY1 overexpression stimulates p53 ubiquitination and degradation through direct physical interaction with p53 and Hdm2. The direct interaction of YY1 and p73 has not been described so far and may be relevant for hepatocarcinogenesis. We are investigating the influence of YY1 on p73 levels and induction of apoptosis of HCC cells. Conclusion: We have adapted LUMIER technology to map protein protein interactions of p53 and p73 in hepatocellular carcinoma cell lines. First results have revealed so far undescribed direct interaction of YY1 and p73 which plays a relevant role in hepatocarcinogenesis.

hepatocellular carcinoma - p53 - p73 - protein protein interaction