Detection of CTCs in cervical cancer using a conditionally replicative adenovirus targeting telomerase-positive cells

Abstract

Circulating tumor cells (CTCs) are newly discovered biomarkers of cancers. Although many systems detect CTCs, a gold standard has not yet been established. We analyzed CTCs in uterine cervical cancer patients using an advanced version of conditionally replicative adenovirus targeting telomerase-positive cells, which was enabled to infect coxsackievirus-adenovirus receptor-negative cells and to reduce false-positive signals in myeloid cells. Blood samples from cervical cancer patients were hemolyzed and infected with the virus and then labeled with fluorescent anti-CD45 and anti-pan cytokeratin antibodies. GFP (+)/CD45 (−) cells were isolated and subjected to whole-genome amplification followed by polymerase chain reaction analysis of human papillomavirus (HPV) DNA. CTCs were detected in 6 of 23 patients with cervical cancers (26.0%). The expression of CTCs did not correlate with the stage of cancer or other clinicopathological factors. In 5 of the 6 CTC-positive cases, the same subtype of HPV DNA as that of the corresponding primary lesion was detected, indicating that the CTCs originated from HPV-infected cancer cells. These CTCs were all negative for cytokeratins. The CTCs detected by our system were genetically confirmed. CTCs derived from uterine cervical cancers had lost epithelial characteristics, indicating that epithelial marker-dependent systems do not have the capacity to detect these cells in cervical cancer patients.

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