AAV vector integration sites in mouse hepatocellular carcinoma

Area of Science:

• Gene Therapy
• Oncology
• Molecular Biology

Background:

• Adeno-associated viruses (AAV) are widely explored as gene therapy vectors due to their low acute toxicity.
• Hepatocellular carcinoma (HCC) is a significant health concern, and understanding its etiology is crucial for prevention and treatment.

Purpose of the Study:

• To investigate the potential oncogenic effects of neonatal adeno-associated virus (AAV) vector administration.
• To identify the genomic integration sites of AAV in tumors and their potential role in hepatocellular carcinoma (HCC) development.

Main Methods:

• Neonatal injection of an AAV vector expressing b-glucuronidase into normal and MPS VII mice.
• Isolation and characterization of AAV proviruses from induced tumors.
• Analysis of the genomic region surrounding AAV integration sites, including gene expression profiling.

Main Results:

• Hepatocellular carcinoma (HCC) developed in both normal and MPS VII mice following neonatal AAV vector injection.
• AAV proviruses were consistently found integrated within a specific 6-kilobase region on chromosome 12 in four independent tumors.
• Overexpression of adjacent small nucleolar RNAs (snoRNAs) and microRNAs was observed in tumor tissues.

Conclusions:

• The identified locus on chromosome 12, encoding imprinted transcripts, snoRNAs, and microRNAs, is implicated in AAV-induced hepatocellular carcinoma (HCC).
• These findings raise significant safety concerns regarding the clinical application of AAV vectors, particularly in neonatal gene therapy settings.