Pristimerin enhances recombinant adeno-associated virus vector-mediated transgene expression in human cell lines in vitro and murine hepatocytes in vivo / 中西医结合学报

<p><b>OBJECTIVE</b>In the present study, we systemically evaluated the ability of two bioactive compounds from traditional Chinese medicine, celastrol and pristimerin, to enhance recombinant adeno-associated virus (rAAV) serotype vector-mediated transgene expression both in human cell lines in vitro, and in murine hepatocytes in vivo.</p><p><b>METHODS</b>Human cell lines were infected with rAAV vectors with either mock treatment or treatment with celastrol or pristimerin. The transgene expression, percentage of nuclear translocated viral genomes and the ubiquitination of intracellular proteins were investigated post-treatment. In addition, nonobese diabetic/severe combined immunodeficient gamma (NSG) mice were tail vain-injected with rAAV vectors and co-administered with either dimethyl sulfoxide, celastrol, pristimerin or a positive control, bortezomib. The transgene expression in liver was detected and compared over time.</p><p><b>RESULTS</b>We observed that treatment with pristimerin, at as low as 1 μmol/L concentration, significantly enhanced rAAV2 vector-mediated transgene expression in vitro, and intraperitoneal co-administration with pristimerin at 4 mg/(kg·d) for 3 d dramatically facilitated viral transduction in murine hepatocytes in vivo. The transduction efficiency of the tyrosine-mutant rAAV2 vectors as well as that of rAAV8 vectors carrying oversized transgene cassette was also augmented significantly by pristimerin. The underlying molecular mechanisms by which pristimerin mediated the observed increase in the transduction efficiency of rAAV vectors include both inhibition of proteasomal degradation of the intracellular proteins and enhanced nuclear translocation of the vector genomes.</p><p><b>CONCLUSION</b>These studies suggest the potential beneficial use of pristimerin and pristimerin-containing herb extract in future liver-targeted gene therapy with rAAV vectors.</p>

The roles of traditional Chinese medicine in gene therapy / 中西医结合学报

The field of gene therapy has been increasingly studied in the last four decades, and its clinical application has become a reality in the last 15 years. Traditional Chinese medicine (TCM), an important component of complementary and alternative medicine, has evolved over thousands of years with its own unique system of theories, diagnostics and therapies. TCM is well-known for its various roles in preventing and treating infectious and chronic diseases, and its usage in other modern clinical practice. However, whether TCM can be applied alongside gene therapy is a topic that has not been systematically examined. Here we provide an overview of TCM theories in relation to gene therapy. We believe that TCM theories are congruent with some principles of gene therapy. TCM-derived drugs may also act as gene therapy vehicles, therapeutic genes, synergistic therapeutic treatments, and as co-administrated drugs to reduce side effects. We also discuss in this review some possible approaches to combine TCM and gene therapy.

Cytotoxic genes from traditional Chinese medicine inhibit tumor growth both in vitro and in vivo / 中西医结合学报

<p><b>OBJECTIVE</b>Little effort has been made to study the protein-encoding genes isolated from traditional Chinese medicine (TCM) drugs, and the delivery of these genes into malignant cells through recombinant adeno-associated virus (rAAV) vectors has not been attempted.</p><p><b>METHODS</b>We synthesized the cDNAs of five known cytotoxic proteins isolated from TCM drugs and the FLAG epitope-tagged cDNAs were subcloned into a rAAV plasmid vector. The protein expression was confirmed by Western blot assay. Various cancer cell lines were transfected with the above plasmids and cell growth was monitored both in vitro and in vivo. The best cytotoxic gene was further packaged into rAAV vectors, under the control of a liver cancer-specific promoter. The liver tumor growth was then monitored following intratumor administration of the rAAV vectors.</p><p><b>RESULTS</b>The expression plasmids, encoding individual potential cytotoxic genes tagged with FLAG epitope, were successfully generated and sequenced. Among these genes, trichosanthin (TCS) gene yielded the most promising results for the inhibition of cancer cell growth in vitro. The over-expressed TCS functioned as a type I ribosome-inactivating protein, followed by inducing apoptosis that is associated with the Bcl-PARP signaling pathway. Furthermore, intratumor injection of rAAV vectors containing the TCS gene significantly inhibited the growth of human hepatocellular carcinoma tumors in a murine xenograft model.</p><p><b>CONCLUSION</b>Our studies suggest that the use of TCM cytotoxic genes is a useful therapeutic strategy for treating human cancers in general, and liver tumors in particular.</p>