Detection of HPV RNA in Extracellular Vesicles from Neuroendocrine Cervical Cancer Cells

Background: Neuroendocrine carcinoma of the cervix (NECC) is an aggressive and rare type of cervical cancer. The five-year overall survival is low at 30% and there is no standardized therapy based on controlled trials for this type of tumour. Most are locally advanced or metastasized at the time of the diagnosis. Extracellular vesicles (EVs) could be a carrier of viral DNA/RNA, given their vital role in cellular communication. The content of EV derived from NECC cells has not been investigated due to the lack of cell line, and it is not known whether they contain human papillomaviruses (HPV) DNA/RNA or not. Methods: The presence of viral E7 DNA/RNA in EVs purified from a culture of a recently established NECC cell line, GUMC-395, was evaluated by using droplet digital polymerase chain reaction (ddPCR). These EVs were characterized using nanoparticle tracking analysis (NTA) for size distribution, transmission electron microscopy (TEM) for morphology, Western blot for CD63, and bioanalyser for RNA quantity and quality. Results: HPV16 viral-RNA, but not DNA, was detected in EVs from GUMC-395 using ddPCR. NTA identified EVs with a mean diameter of 105.0 nm, TEM confirmed normal morphological shape and size, and Western blot analysis confirmed the presence of EV-associated proteins CD63. The EVs were found to be enriched with small RNAs using a bioanalyser. Conclusions: HPV16 RNA is found in EVs from a neuroendocrine cervical cancer and could be involved in the pathogenesis of the disease and used as a diagnostic biomarker.