[Hormone excretion and peroxisomes of human immortalized extravillous trophoblast cells (TCL-2) derived from first-trimester placenta]

We studied the hormone excretion of human immortalized extravillous trophoblast cells (TCL-2, first-trimester cells) and determined whether peroxisomes are present in TCL-2. The results of TCL-2 were compared with those of TCL-1 (third-trimester cells). Morphologically, TCL-2 cells were fibroblast-like, and the growth rate of TCL-2 was slower than that of TCL-1 during 3 days culture. Progesterone was detected in the medium of TCL-2, and its concentration was approximately one-tenth of that in TCL-1. The activity of the peroxisomal marker enzyme catalase was detected in the TCL-2 homogenate, and it was about one-third the level of that in TCL-1. Fatty acyl-CoA oxidase activity was detected in TCL-2, and it was about one-seventh the level of that in TCL-1. On the other hand, human chorionic gonadotropin (hCG) was detected in the medium of TCL-2, and its concentration after 3 days of culture was about 2-fold that in TCL-1. Using the diaminobenzidine (DAB) method, peroxisomes were found in TCL-2, but only a very small amount of catalase was detected. These results indicate that human immortalized extravillous trophoblast cells (TCL-2) synthesize, secrete hCG and progesterone, and may contain peroxisomes. Because extravillous trophoblast cells are difficult to obtain from the first-trimester placenta, TCL-2 cells are useful for the study of the physiologic functions (including peroxisomal function) of first-trimester cells.

Effects of WY-14643 on peroxisomal enzyme activity and hormone secretion in immortalized human trophoblast cells

In our previous report, clofibric acid increased both the enzyme activities of peroxisomes (catalase and fatty acyl-CoA oxidase) and the secretion of progesterone in immortalized human extravillous trophoblast cells (TCL-1) (F. Hashimoto et al., Biochem. Pharm., 68, 313 (2004)). WY-14643 is reported to be stronger inducer of peroxisomes in rodents than clofibric acid. Therefore, the effects of WY-14643 on the activities of peroxisomal enzymes and hormone secretion in TCL-1 were studied. After incubation for 3 d with WY-14643, WY-14643 (>/=0.15 mM) suppressed the rate of increase in DNA and protein. The specific activities of catalase were increased by 0.1 mM WY-14643. The specific activities of fatty acyl-CoA oxidase were hardly changed by WY-14643. The concentration of progesterone in the medium was increased by 0.1 mM WY-14643, but human chorionic gonadotropin was decreased by 0.2 mM WY-14643. After a discontinuous Nycodenz-density gradient centrifugation of the light mitochondrial fraction of the cells, catalase activity was distributed in lower density fractions than cytochrome-c oxidase (a mitochondria marker enzyme) activity, but the distribution was not changed by WY-14643. These results suggest that WY-14643 inhibits the proliferation of trophoblast cells. The density of peroxisomes in human trophoblast cells is lower than that of mitochondria, and it is not affected by WY-14643. WY-14643 may increase the progesterone secretion. Effects of WY-14643 on metabolism of human trophoblast cells are different from those of clofibric acid.