Xiaoyang Zhao, PhD, Nagy Habib, Professor. Imperial College London
Introduction: Hepatocellular carcinoma (HCC) represents the second cause of cancer related death worldwide. Given the high fatality of HCC, only 12% of patients are indicated for surgery leading to long term survival. C/EBPA, a liver transcription factor, plays a major role in regulating cell proliferation and hepatocyte function. C/EBPA functionally interacts with C/EBPB to change cell behavior. This study aims to elucidate the functional role of C/EBPA and C/EBPB in the pathogenesis of HCC.
Methods and Procedures: Hepatocytes were transfected with either saRNA or siRNA to increase or repress C/EBPA or C/EBPB. Differentiated and Undifferentiated HCC were represented by HepG2 vs. PLC/PRF/5 cells. Transcript/protein expression levels of C/EBPA & C/EBPB including downstream targets were analyzed by qRT-PCR/western blot. Effect of saRNA vs. siRNA on cell density was measured by Sulforhodamine B colorimetric (SRB) assay. Effect of saRNA vs. siRNA on cell proliferation was measured indirectly via activity of mitochondrial dehydrogenases (WST-assay).
Results: Only HepG2 cells responds to the increase in C/EBPA. C/EBPB levels prevents PLC/PRF/5 cells from responding to the increase in C/EBPA. C/EBPA and C/EBPB play diverse effects in different differentiated HCC. C/EBPA activation by saRNA enhanced the expression of P21 and Albumin in differentiated HepG2 cells but not in undifferentiated PLC/PRF/5 cells. This means P21 and Albumin may not be the downstream factor of C/EBPA in undifferentiated PLC/PRF/5 cells. There was no significant alteration in the expression of C/EBPB in both cell lines. C/EBPB suppression enhanced the expression of C/EBPA and P21 in differentiated HepG2 cells but not undifferentiated PLC/PRF/5 cells. C/EBPA enhancement had a better anti-proliferative effect in differentiated HCC.
Conclusion: The dynamic interaction between C/EBPA and C/EBPB is crucial in biology of HCC. Higher ratio of C/EBPA to C/EBPB lead to better cell cycle repression; metabolic genes activation and suppression of acute phase response genes. This was more relevant in differentiated HCC. p21 was the downstream factor regulated by C/EBPA promoting cell cycle suppression in differentiated HepG2 cells. An alternative network may be more relevant in PLC/PRF/5 cells. Albumin expression was upregulated by C/EBPA enhancement in well differentiated HepG2 cells. Undifferentiated PLC/PRF/5 cells therefore cannot rely on C/EBPA for reestablishing albumin expression. C/EBPA enhancement in well differentiated HepG2 cells had better anti-proliferative effect than undifferentiated PLC/PRF/5 cells.
Presented at the SAGES 2017 Annual Meeting in Houston, TX.
Abstract ID: 79552
Program Number: P452
Presentation Session: Poster (Non CME)
Presentation Type: Poster
