P53 EXPRESSION IN PLACENTAS WITH HYDROPIC CHANGE AND HYDATIDIFORM MOLES

Hydatidiform moles result from abnormal fertilization and have been di vided into partial and complete forms based on morphologic, cytogeneti c, and clinical features, Little is known about their pathogenesis or malignant transformation. We applied an immunohistochemical marker for the p53 tumor suppressor gene product to placentas with hydropic chan ge and hydatidiform moles to determine whether abnormal p53 gene produ ct accumulation occurs in molar gestations, Ploidy of these placentas was determined by now cytometry and fluorescence ka situ hybridization . The mean percentages of p53-positive cells was determined by countin g 200 cytotrophoblastic and proliferating trophoblastic cells. The sta ining intensity tvas graded on a scale of 1+ (faint) to 3+ (strong). T he mean percentage of p53-positive cells for the placentas were as fol lows: 8.9% +/- 10.5 for hydropic change; 28.0% +/- 13.2 for partial mo le; and 41.0% +/- 19.6 for complete mole. There was a significant diff erence in p53 expression between hydropic change and partial mole (P = 0.05) and hydropic change and complete mole (P = 0.0008). Although th ere was a difference between partial mole and complete mole, this did not reach statistical significance (P = 0.15). Hydatidiform moles exhi bited 2+ to 3+ staining intensity, whereas hydropic placentas exhibite d weaker intensity (1-2+). The finding of p53 gene product overaccumul ation in partial and complete moles suggests that p53 gene mutations o r alternatively, post-transcriptional changes in the p53 gene product occur resulting in inactivation and stabilization of the protein. This may play a role in uncontrolled trophoblastic proliferation and neopl astic transformation.