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Pituitary tumor transforming gene 1 (PTTG1) recently cloned from human testis is a potent oncogene and is highly expressed in all the tumors analyzed to date. However, primary structure of PTTG1 and the cell types that express PTTG1 in tumors remained undescribed. We have used the reverse transcriptase-polymerase chain reaction technique to clone PTTG1 from ovarian tumors. Nucleotide sequencing of the PTTG1 cDNAs from various ovarian tumors showed identity with that of the human testis PTTG1. To determine the cell types that express PTTG1 in normal and tumor tissues, we performed in situ hybridization using digoxigenin-labeled cRNA as a probe. Our studies revealed a high level of expression of PTTG1 mRNA in both seminomatous and non-seminomatous testicular tumors; epithelial, sex-cord and stromal cell, and germ cell tumors of the ovary; and invasive ductal, ductal in situ and infiltrating ductal carcinoma of the breast. In normal tissues, expression of PTTG1 mRNA was very low or undetectable except in testis, where PTTG1 mRNA was found to be localized to spermatocytes and spermatids. Tumors that expressed high levels of PTTG1 mRNA also exhibited high levels of expression of basic fibroblast growth factor (bFGF), suggesting a correlation between PTTG1 and bFGF expression, and further suggesting that the PTTG1 protein may be involved in tumor angiogenesis and mitogenesis.
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