Pilot study: transduction of primary paraganglioma chromaffin tumour cells with inducible c-MYC drives cell proliferation.

Succinate dehydrogenase (SDH) gene variants are the most common cause of the neuroendocrine tumour hereditary paraganglioma, which is associated with an over 20% metastasis risk as well as significant morbidity. There are currently no relevant human tumour cell lines or mouse models, and molecular understanding of downstream tumourigenic pathways is still rudimentary despite over two decades of concerted effort worldwide. These tumours generally show extremely slow in vivo doubling times (4-12 years), presumably existing in a primarily semi-quiescent state with little cell cycling or DNA replication. This characteristic makes deriving a useful tumour cell line impractical. A better alternative would be a cell line in which cell proliferation can be turned on and off at will, allowing expansion to generate sufficient cell numbers and experimentation once tumour cells have returned to their natural semi-quiescent state. The closest models currently available, highly-proliferating rat and mouse adrenal paraganglioma cell lines, are molecularly unrelated to SDH tumours. In this pilot study, we investigated whether primary SDH-derived paraganglioma tumour cells can be made to proliferate in vitro. We successfully transduced primary paraganglioma tumour cells with a lentiviral construct, using the proven strategy of c-MYC¬T58A (c-MYC) controlled by a Tet-On doxycycline-inducible expression system. We present the first evidence that primary paraganglioma chromaffin cells can be induced to proliferate in vitro, even in later passage cultures. Without any prior selection for chromaffin tumour cells, passaged cultures were obtained with over 80% synaptophysin-expressing chromaffin tumour cells, suggesting that this highly promising strategy deserves further exploration.