Aberrant content of sialic acids (Sias) has been observed in various human cancer types in different organs. Sias have been implicated in cancerous transformation, invasiveness and metastasis, and in the escaping of cancer cells from immune surveillance. Indeed, Sias are commonly regarded as important biomarkers to distinguish cancer cells from their healthy counterparts. However, scarce and not exhaustive investigations have been performed on Sia content in testicular cancers and, in particular, in seminoma, one of the most common malignant testicular tumors. Hence, the aim of this study was to investigate the content and distribution of Sias with different glycosidic linkage, namely α2,3 and α2,6 galactose- or N-acetyl-galactosamine-linked Sias and polymeric Sia (polySia), in the germinal and stromal components of human testes affected by seminoma compared to normal testicular tissue. Structural changes in seminoma tissue were examined using hematoxylin-eosin staining. α2,3 and α2,6 linked Sias were evaluated by lectin histochemistry (Maackia amurensis agglutinin (MAA) and Sambucus nigra agglutinin (SNA)), while confocal immunofluorescence was used for polySia detection. Histopathological findings in seminoma tissue included loss of seminiferous tubules replaced by clusters of uniform polygonal cells with a clear cytoplasm, bundles of fibrotic tissue, numerous microvessels and some atrophic tubules. The content of α2,3 and α2,6 linked Sias was lost in almost all seminoma components respect to normal tissue, with the exception of microvessels in which it was higher. On the contrary, polySia level was increased in all the seminoma components compared to normal testicular tissue. Our findings suggest that an aberrant content of different Sias might have important and differential roles in seminoma development and progression. In particular, polySia might be implicated in seminoma progression by promoting cancer invasiveness and regulating the cross-talk between cancer cells, reactive stroma and vessels. Thus, the possibility that polySia might represent an important biomarker for seminoma deserves further investigation.

中文翻译：

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人睾丸精原细胞中唾液酸的特征和分布。

唾液酸（Sias）含量异常已在不同器官的各种人类癌症类型中观察到。Sias与癌症的转化，侵袭和转移以及免疫监视逃避癌细胞有关。实际上，Sias通常被认为是区分癌细胞与健康细胞的重要生物标志物。然而，对于睾丸癌，尤其是精原细胞瘤（最常见的恶性睾丸肿瘤之一）中的Sia含量，已经进行了很少且不详尽的研究。因此，本研究的目的是研究具有不同糖苷键的Sias的含量和分布，即α2,3和α2,6半乳糖或N-乙酰基半乳糖胺连接的Sias和聚合Sia（polySia），与正常睾丸组织相比，精原细胞瘤感染的人睾丸生发和基质成分的表达 使用苏木精-伊红染色检查精原细胞组织的结构变化。通过凝集素组织化学（Maackia amurensis凝集素（MAA）和黑接骨木（Sambucus nigra）凝集素（SNA））对α2,3和α2,6连接的Sias进行了评估，而共聚焦免疫荧光检测了polySia。精液瘤组织的组织病理学发现包括：由具有透明细胞质的均匀多角形细胞簇代替的生精小管丢失，纤维化组织束，大量微血管和一些萎缩性小管。相对于正常组织，几乎所有精原细胞成分中都丢失了α2,3和α2,6连接的Sias的含量，但微血管含量更高。反之，与正常睾丸组织相比，所有精原细胞成分的polySia水平均升高。我们的发现表明，不同Sias含量异常可能在精原细胞瘤的发生和发展中起着重要而又不同的作用。尤其是，polySia可能通过促进癌症浸润并调节癌细胞，反应性基质和血管之间的串扰而参与精原细胞瘤的发展。因此，polySia可能代表精原细胞瘤重要生物标志物的可能性值得进一步研究。polySia可能通过促进癌症浸润并调节癌细胞，反应性基质和血管之间的串扰而参与精原细胞瘤的发展。因此，polySia可能代表精原细胞瘤重要生物标志物的可能性值得进一步研究。polySia可能通过促进癌症浸润并调节癌细胞，反应性基质和血管之间的串扰而参与精原细胞瘤的发展。因此，polySia可能代表精原细胞瘤重要生物标志物的可能性值得进一步研究。