The expression of claudins 1, 2, 3, 4, 5 and 7 was studied in prostate adenocarcinoma and compared to that of non-neoplastic epithelium and Gleason score of the tumors. Additionally, RT-PCR was performed for claudins 2 and 5 in three cases. Strong immunoreactivity of claudins 1, 3, 4 and 7 was seen in prostate adenocarcinoma while expression of claudins 2 and 5 was weaker. In relation to non-neoplastic glands, expression of claudins 2 and 5 was diminished. There was a significant association between the Gleason score and claudin 1 and 5 expression, these claudins were more strongly expressed in tumours with a lower Gleason score. A combined lowered claudin expression was associated with a high Gleason score and a poor prognosis. According to the results, there is a strong claudin expression in prostate adenocarcinoma, especially for claudins 3 and 4. In contrast, claudin 2 was low in neoplastic cells compared to non-neoplastic epithelium, suggesting downregulation of synthesis or altered metabolism/ assembly of this protein during carcinoma development. The association of lowered claudin 1 and 5 expression and lowered overall claudin expression with tumours of a higher Gleason score suggest that claudins may modulate the histologic features of these tumors and in this way influence their biological behaviour.
We investigated the expression of claudins 1, 3-7 and transcriptional factor twist in a set of testicular germ cell tumors. The material consisted of 17 seminomas, 13 teratomas, 9 teratocarcinomas, 20 embryonal carcinomas and 9 mixed germ cell tumors. They were immunostained with antibodies to claudins 1, 3-7 and twist. As expected, all claudins were variably present in germ cell tumors with epithelial elements or differentiation, but the intensity of expression varied depending on the claudin type. Mesenchymal elements in teratomatous tumors remained negative for claudins. Expression of different claudins was less intense and inconsistent in other types of germ cell tumors. Choriocarcinomatous elements in germ cell tumors expressed relatively strongly claudin 4 and weaker positivity for claudins 5-7, while claudins 1 and 3 were negative. Seminomas showed expression only for claudins 5 and 7. The transcriptional factor twist was most strongly expressed in seminoma followed by embryonal carcinoma. Twist expression was inversely associated with several claudins (claudins 1, 3, 4 and 6). Germ cell tumors vary in their expression of claudins 1-7. Twist expression was inversely associated with several claudins, suggesting that it takes part in the downregulation of claudins in testicular tumors.
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