Activin receptors (ActRs) and
gonadotropin receptor
mRNA expression were investigated in 18 human ovarian
epithelial neoplasms. Northern blot analysis showed the presence of 3.0-kb type Ia ActR, 6.0- and 3.0-kb type IIa ActR, and 5.0-kb type IIb ActR
mRNA transcripts in total
RNA prepared from the
cancer tissues. One
carcinoma showed two major transcripts of a
follicle-stimulating hormone receptor (FSH-R) gene, 4.1 and 2.4 kb, whereas the other two
carcinomas showed two major transcripts of the
luteinizing hormone/
human chorionic gonadotropin receptor (LH-R) gene, 5.4 and 2.4 kb. These results were further analyzed by studying the corresponding PCR-amplified FSH and LH-R
cDNA obtained by reverse transcription of total
RNA. Expression of FSH-R
mRNA was confirmed in about half of the
cancer tissues. The size of the FSH-R reverse transcription-PCR product was the same as in normal ovarian follicles. Similarly, expression of LH-R
mRNA was also detected in about half of the
cancers. Normal ovaries and
cancer tissues were homogenized, and
activin concentrations were measured in extracts.
Activin levels in normal ovarian tissue were around 0.59 +/- 0.01 ng/mg
protein (mean +/- SE; n = 5), and
activin production was detected in every
cancer tissue, except one--serous
adenocarcinoma. The findings in this study demonstrated that
activin and ActRs are present in and synthesized by human ovarian
epithelial neoplasms. Thus,
activin seems to be available as an autocrine/paracrine factor in
epithelial neoplasms and may contribute to the expression of FSH-R, although the roles of
activin and
gonadotropin in
tumorigenesis has yet to be defined.