Burton JB et al. (2008) Adenovirus-mediated gene expression imaging to directly detect sentinel lymph node metastasis of prostate cancer. Nat Med 14: 882–888

Lymph node status in prostate cancer is an important predictor of outcome, but currently, no reliable, noninvasive methods exist to detect lymph node metastasis. Now, researchers at the University of California, Los Angeles, describe the use of an adenovirus vector to allow direct imaging of metastasis in sentinel lymph nodes. Their study used a mouse xenograft model of human prostate cancer.

Burton et al. developed adenovirus vectors that express optical and PET reporter genes under the control of an amplified PSA promoter to permit prostate-specific imaging. Adenoviruses preferentially infiltrate the lymphatic system, so injection of these vectors into the forepaws of mice bearing human prostate tumors derived from the aggressive LAPC-9 cell line allowed specific bioluminescent and PET imaging of metastatic lymph nodes. PET detected nodes 2.5 mm in diameter. Peritumoral virus injection, in a manner analogous to the lymphoscintigraphy technique, permitted visualization of PET signals both from the tumor and from metastases within the draining axillary lymph node.

The authors conclude that lymphangiography using the adenoviral gene transfer technique promises to facilitate accurate, noninvasive detection of lymph node metastasis. In addition, one of the reporter genes carried by the vector, the herpes simplex thymidine kinase gene, has also previously been shown to sensitize tumor cells to ganciclovir, which opens up the possibility of using these adenoviral vectors for both diagnostic imaging and suicide gene therapy.