Negative Role Of A20in Hepatocarcinoma Tumorigenesis And Metastasis

Part I: Negative Role of A20in Hepatocarcinoma Tumorigenesis andMetastasisBackground＆Aims: Inflammation is critical in tumorigenesis. The NFκB signaling isone of the most important passways for inflammation and it can promotehepatocarcinoma development by maintain liver inflammatory responses. A20plays acritical role in inhibiting NFκB activation through its ubiquitin-editing activity. Manyreports have identified A20as a crucial tumor suppressor in various lymphomas.However, the role of A20in liver tumor is not clear.Methods: Using clinical samples from patients with hepatocellular carcinoma (HCC),HCC cell lines and the Alb-Cre-A20fl/flmice, we evaluated the molecular functions ofA20in HCC tumorigenesis and metastasis.Results: In tumor tissue-chip assay, expression of A20was positively associated with thedisease-free and total survival and negatively associated with tumor size, stage,metastasis and AFP levels. Further study found that A20was involved in downregulationof migration and invasion via increasing Twist1, and suppressed tumorigenesis ofhepatoma cells in mice via inhibition of NFκB. Hepatocytes lacking A20in micedeveloped tumors earlier and larger than wildtype mice in mouse tumorigenetic model.Conclusions: These findings reveal that A20plays a negative role in tumor metastasisand tumorigenesis and may serve as a good prognosis for HCC. Part II: CD133/Prominin-1Mediated Autophagy Beneficial forHepatoma Cell SurvivalBackground＆Aims: CD133/Prominin-1is a pentaspan transmembrane protein. In manytumors, it has been used as a membrane biomarker of cancer stem cells. However itsfunction is not very clear. The purpose of this study was to discover the functions ofCD133in hepatocarcinoma cells.Methods: Hepatoma cells were treated with CD133mAb in both of complete medium(CM) and low glucose medium (LGM) to see the effect of CD133mAb on cells’ growth,survival, and autophagy. And the effect of CD133on autophagy was determined byoverexpression or knockdown in hepatoma cells.Results: The results showed that targeting CD133with CD133mAb resulted in cell deathespecially in LGM condition, because of downregulation of autophagy. CD133translocated from membrane into cytoplasm in LGM. Expression of CD133improvedautophagy while silencing CD133attenuated autophagy in hepatoma cells, and CD133was shown to be associated with autophagosome and lysosome by immunofluorescenceduring the glucose starvation. Moreover, knockdown of CD133in Huh-7cells inhibitedcell proliferation and xenograft tumor formation in the NOD/SCID mice. Huh-7shCD133cells obviously died fast than Huh-7con cells in the glucose starvation.Conclusions: The findings showed that CD133was beneficial for cell survival throughpromotion of autophagy, which may be necessary for cancer stem cells to survive intumor microenvironment.