Stagnancy of ten-year cervical cancer (CC) incidence in the U.S., despite screening advancements, suggests the need for new CC screening technologies. This study in preclinical CC models evaluated a diagnostic plasmid that induces expression of a reporter (secreted embryonic alkaline phosphatase, SEAP) through the control of cancer-specific promoter sequence (inhibitor of differentiation 1, Id1). The plasmid (pId1-SEAP) was used to transfect CC cells in vitro and characterize SEAP production based on Id1 expression. Western Blot and immunohistochemistry were used to establish Id1 expression in cell models and human tissues. Timed transfections in various conditions were used to correlate Id1 and SEAP expression. CC cell lines expressed increased normalized baseline Id1 (HeLa 3.0 ± 0.13, SiHa 2.9 ± 0.27, both P < 0.0001) compared to non-cancer 3T3 fibroblasts (1.0 ± 0.0). Normal cervical tissues had a mean Id1 staining value of 3E4 ± 3E4, while early- and late-stage CC tissues had increased mean Id1 staining (3E5 ± 1E5 P < 0.0001 and 2E5 ± 1E5 P = 0.0002, respectively). HeLa and SiHa lines produced increased normalized SEAP (0.63 ± 0.25 and 0.50 ± 0.10, P < 0.05) compared to 3T3 cells, both with pId1-SEAP (0.16 ± 0.058). As few as 12,500 pId1-SEAP transfected HeLa cells resulted in increased SEAP (3E4 ± 3E3 P = 0.004) compared to background (1E4 ± 4E2). SiHa xenograft ex vivo tumor transfected with 25 µg/µL pId1-SEAP produced significantly greater SEAP (21.7 ± 8.6, P = 0.0003) relative to muscle transfected in the same conditions (0.94 ± 0.24). pId1-SEAP can transfect CC cells to produce SEAP proportionally to endogenous Id1 expression, demonstrating its potential for additional studies in CC models.
Eli et al. (Sun,) studied this question.