Expression and Amplification of Cellular Oncogenes in Human Developing Placenta and Neoplastic Trophoblastic Tissue

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Abstract
To confirm the expression of cellular oncogenes during normal development, their differential RNA levels in developing human placenta have been studied using radioactive probes such as ?‐abl, ?‐erbA, ?‐fms, ?‐mos, ?‐myc, N‐ras and ?‐src. The c‐tnos and N‐ras genes are expressed and amplified at high levels especially in term placenta, while c‐abl, and c‐erbA are expressed constantly during development. These findings indicate that c‐mos and N‐ras genes may be closely linked to normal differentiation, although c‐abl and c‐erbA may participate in overall developmental processes. In contrast, transcripts of c‐myc and c‐src are enhanced at first trimester and decreased sequentially thereafter, showing that these genes may play a role in early proliferation. Expression patterns of c‐fms gene are same as that of c‐myc and c‐src except reeleva‐tion at term. In addition, to characterize the effect of cellular oncogene expression has been also examined in hydatidiform mole and tumor cells such as BeWo and choriocarcinoma. All cellular oncogenes examined in this study were significantly overexpressed. Thus, our results suggest that cellular oncogene activation may be strongly associated with neoplastic change of trophoblast.