Combination Suicide Gene Delivery with an Adeno-Associated Virus Vector Encoding Inducible Caspase-9 and a Chemical Inducer of Dimerization Is Effective in a Xenotransplantation Model of Hepatocellular Carcinoma

Abstract

Current treatment approaches for hepatocellular carcinoma (HCC) have a narrow therapeutic index and alternate modes of treatment are thus required. We have utilized a gene delivery vector containing inducible caspase 9 (iCasp9) gene, which is a synthetic analogue based on the mammalian caspase 9 and fused to a human FK506 binding protein that allows its conditional dimerization to a synthetic, small molecule [chemical inducer of dimerization, AP20187] and results in target cell apoptosis. In our studies, we have tested these synthetic vectors based on an adeno-associated virus platform for their potential anti-tumorigenic effect in human HCC cells in vitro and in a HCC tumor model developed in nude mice. Our data demonstrates that the iCasp9-AP20187 bioconjugate is able to trigger terminal effectors of cellular apoptosis and presents a viable approach for the potential treatment of HCC.

AAV6 Vexosomes Mediate Robust Suicide Gene Delivery in a Murine Model of Hepatocellular Carcinoma

“…48,49 We have recently developed a AAV2-based, iCasp9-based suicide gene therapy as an alternative approach to treat HCC. 20 Due to the fact that frequency of high titer neutralizing antibodies to AAV2 in the general population can be as high as $70%, 50 we wished to evaluate an alternate AAV6 serotype for its potential in delivering the iCasp9 suicide gene. Interestingly, the AAV6 serotype can efficiently target liver cells, including Huh7 cells.…”

“…Conventional AAV vectors were generated as described previously. 10 Briefly, AAV293 cells, expanded in 15 cm 2 dishes (n = 40), were cotransfected using polyethylenimine (PEI; Polysciences, Warrington, PA, USA) with an equimolar concentration of plasmids carrying the rep/cap plasmid (p.AAVR2/C6), an inducible caspase 9 transgene (p.AAV-CBa-iCasp9) 20 and adenoviral helper plasmids (p.Helper). Transfected cultures were maintained in IMDM, supplemented with 10% FBS.…”

“…We have recently demonstrated the potential of a AAV2-mediated inducible caspase 9 (iCasp9) gene delivery in a hepatocellular carcinoma (HCC) model. 20 In the current study, we have evaluated the potential of exosome-associated AAV6 vectors (exo-AAV6 or AAV6 vexosomes) for their ability to deliver a suicide gene efficiently in an in vitro hepatic cancer model (Huh7 cells), as well as its therapeutic potential in the xenograft mice model of HCC.…”

Delivery of cancer therapies by synthetic and bio-inspired nanovectors

“…Interestingly, displaying the TRAIL protein on the surface of nanovectors has also demonstrated efficient TRAIL-mediated cell death induction of circulating tumor cells in different studies [242][243][244]. An alternative is the use of inducible suicide genes, an elegant example being the vectorization by adenoviral vectors [245] and AAVs [246] of the AP20187-dependent inducible version of caspase 9, activated after AP20187 treatment. Another example is the AAV vectorization of a CRISPR system targeting telomeres to induce tumor cell death [211].…”

The Application of the CRISPR/Cas9 System in the Treatment of Hepatitis B Liver Cancer

“… 73 We can perform genome-wide screening using CRISPR-mediated genome editing to identify inhibitors or critical drivers such as the lncRNA 74 of liver tumor formation, and then develop strategies to suppress or reduce related factors to treat patients with liver cancer. 73 , 75 , 76 …”