Aberrant Expressions And Functions Of STAT3 And Wnt Signaling Pathway In Hepatocellular Carcinoma & Expression Of The Antibacterial Peptide Gene Of Chinese Silkworm Bombyx Mori In Eukaryotic System

Hepatocellular carcinoma (HCC) is the major primary malignant tumor in the human liver, but the molecular changes leading to liver cell transformation remain largely unknown. We selected STATS (signal transducer and activator of transcription), P -catenin and TCF4 as research objects. We studied the inappropriate expression and functions of them in HCC so as to try to search the way to treat the HCC.To understand the effect of STAT3 on the HCC, we overexpressed STATS to cause inappropriate activation and used the dominant negative form of STATS to lead to STATS absence. Studies demonstrated that the migration inhibition of BEL-7402 cells in response to IL-6 cytokine was dependent on STATS activation and STATS mediated the inhibitory effect of 11-6 on the liver cancer cell migration. Constitutive activation of STATS was present in BEL-7402 cells.Immuno-histochemistry, RT-PCR and Western blot analysis were carried out to examine the high expression of P -catenin and TCF4 in HCC tissues and HCC cell lines. We found the TCF4 mRNA was high expressed in HCC cell line for the first time. Functional importance of ?-catenin and TCF4 for the Wnt signaling pathway was determined by TOP luciferase reporter assays. The results suggested that TCF4 is the predominant TCP factor present in liver cancer cells and inappropriate activation of Wnt pathway maybe play an important role in the development of HCC.We showed that P -cateninSSTA overexpression stimulated tumor cell proliferation and the dominant negative TCF4 expression inhibited evidently the growth and migration ability of BEL-7402. Wnt pathway governed cellular proliferation by regulating cyclinDl protein level. These results indicated that specifically disrupting the ?-catenin-TCF4 complex could be useful in treating liver cancers and TCF4 may be an effective therapeutic molecule for suppressing growth of hepatocellular cancers.There would be certain crosstalk between STATS pathway and Wnt pathway. We demonstrated that endogenous P -catenin could be coimmunoprecipitated with endogenous STATS in HepG2 cell, and the immunoprecipitates were down-regulatedwith the increase of cell density. As transcriptional factors, no synergized activation of the two pathways was detected.Cecropins are a family cytokines of small, antibacterial peptides from insects. It is potentially to be a new generation of antibacterial and antitumor drugs. We used the baculoviruses system expressing the nature antibacterial peptide gene and the synthesized CMlV-like gene of Chinese silkworm Bombyx mori. The results showed that C-terminal amidation was important for antibacterial peptide's function. We provided good materials to study the mechanism of their antibacterial and antitumor activity.