title: Secretory expression of Par-4 SAC-HA2TAT following adeno-associated virus-mediated gene transfer induces apoptosis in HepG2 cells.
abstract: Prostate apoptosis response-4 (Par-4) is a tumor-suppressor protein that induces apoptosis in cancer cells, but not in normal cells. The cancer-specific pro-apoptotic action of Par-4 is encoded in its centrally located SAC domain. In this study, to further enhance the anti-cancer effect of Par-4 in order to overcome the limitations of peptide therapy, a recombinant adeno-associated virus was constructed using the following strategies: the secretory expression of therapeutic peptide, a HA2TAT-mediated cytosolic delivery technique, and an adeno-associated virus gene transfer system. To test the hypothesis that Par-4 has an additive bystander effect as an anti-cancer therapy, we designed a secretory protein by adding a secretory signal peptide NT4(Si) to the Par-4 SAC-HA2TAT peptide gene sequence [NT4(Si)-Par-4 SAC-HA2TAT]. The results indicated that, compared to the normal NIH3T3 cell line, AAV-NT4(Si)-Par-4 SAC-HA2TAT significantly suppressed cell growth and induced rapid cell death in HepG2 cells in a time-dependent manner through successful gene transfer and secretory expression of therapeutic peptide at 48 h post-transfection. In addition, the secretory properties of Par-4 may greatly increase its effectiveness in cancer therapy when delivered in vivo.
authors.affiliation: Department of Oncology, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
authors.forename: Tian-Jie
authors.initials: TJ
authors.lastname: Qin
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.forename: Shan-Xi
authors.initials: SX
authors.lastname: Liu
authors.forename: Guang-Xiao
authors.initials: GX
authors.lastname: Yang
authors.forename: Quan-Ying
authors.initials: QY
authors.lastname: Wang
authors.forename: Xin-Han
authors.initials: XH
authors.lastname: Zhao