Objective: To establish human choriocarcinoma JeG-3 cell line resistant to floxuridine (FUDR) and describe the characteristics of this FUDR-resistant subline. The thymidylate synthase (TS) expression level in FUDR-resistant subline was also discussed.
Methods: The FUDR-resistant sub-line JeG-3/FUDRA was established by intermitted exposure to grads increased FUDR. Reversed microscope was used to observe the morphological changes in FUDR-resistant sub-line. Population doubling time was calculated and compared based on the growth curve of these two cell lines, cell cycles and chromosomal ploidy were assayed with flow cytometry methods. The chemo-luminescence assay was used to detect the hormone secretion by two kinds of cell lines. The resistant index (RI) was measured by cell counting kit-8 (CCK-8) assay. Quantitative RT-PCR was used to detect the mRNA expression level of TS and we also detected the TS mRNA expression level in different doses exposed subline.
Results: The RI of JeG-3/FUDRA was 31.62. Compared with the JeG-3 cell, the FUDR-resistant cell line had gross changes in morphological, cell growth, cell cycles and chromosomal numbers. The ability of human chorionic gonadotrop (hCG) and progesterone secretion was lower in JeG-3/FUDRA subline. The trend of TS mRNA expression was: while exposed to low concentration of FUDR, the TS mRNA expression level was downregulated, then followed the increasing dose of the drug, the expression level of TS mRNA ascended gradually. When the terminal concentration was reached, the expression level of TS mRNA in JeG-3/FUDRA subline was higher than that of JeG-3 cell line (P < 0.05).
Conclusions: We established the FUDR-resistant subline of JeG-3 successfully. The TS mRNA expression level is stage-related to the different concentration and different phase in FUDR exposure. Our data suggested that TS mRNA expression level may not be used as a biomarker to predict the chemosensitivity in FUDR-based chemotherapy.