Human granulosa cell (GC)-
tumors are assumed to arise from ovarian GCs but to what extent they resemble normal human GCs is not well established. We examined whether a prominent feature of normal GCs, expression of the major gap junctional
protein connexin 43 (
Cx43), was retained in 14 human GC-
tumor samples. Immunohistochemistry revealed areas of strong staining side by side with areas of weak and/or no staining. If present, cytoplasmic and membrane-associated
Cx43 staining occurred. In cells with reduced or absent
Cx43, another Cx was found, Cx32. Cx32, which is absent from non-
tumor GCs, was present in GC-
tumor cells co-expressed in part with
Cx43 at gap junctional plaques. Expression of Cx32 and
Cx43 was confirmed by RT-PCR and sequencing in the majority of
tumor samples. Thus GC-
tumor cells are characterized by a partial or complete loss of
Cx43 expression and expression of Cx32, which may be a marker for these rare
tumors. It is possible that the pattern of Cxs may contribute to
tumor formation and growth, as it may indicate aberrant and/or reduced cell-to-cell communication ability.