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The molecular pathogenesis of gastroenteropancreatic (GEP) neuroendocrine tumours (NETs) remains to be elucidated. High-mobility group A (HMGA) proteins play important roles in the regulation of transcription, differentiation, and neoplastic transformation. In this study, the expression of HMGA1 and HMGA2 was studied in 55 GEP NETs. Overexpression of HMGA1 and 2 was frequently detected in GEP NETs compared with normal tissues. Nuclear immunostaining of HMGA1 and 2 was observed in GEP NETs (38 of 55, 69%; 40 of 55, 73%, respectively). High-mobility group A2 expression increased from well-differentiated NET (WNET) to well-differentiated neuroendocrine carcinoma (WNEC) and poorly differentiated NEC (PNEC) (P<0.005) and showed the highest level in stage IV tumours (P<0.01). In WNECs, the expression of HMGA1 and 2 was significantly higher in metastatic tumours than those without metastasis (P<0.05). Gastroenteropancreatic NETs in foregut showed the highest level of HMGA1 and 2 expressions. MIB-1 labelling index (MIB-1 LI) correlated with HMGA1 and 2 overexpression (R=0.28, P<0.05; R=0.434, P<0.001; respectively) and progressively increased from WNETs to WNECs and PNECs (P<0.001). Let-7 expression was addressed in 6 normal organs, 30 tumour samples, and 24 tumour margin non-tumour tissues. Compared with normal tissues, let-7 downregulation was frequent in NETs (19 of 30, 63%). Higher expression of HMGA1 and 2 was frequently observed in tumours with let-7 significant reduction (53, 42%, respectively). The reverse correlation could be detected between HMGA1 and let-7 (P<0.05). Our findings suggested that HMGA1 and 2 overexpression and let-7 downregulation might relate to pathogenesis of GEP NETs. [ABSTRACT FROM AUTHOR]

Augmented expression of members of the heat shock protein 70 (Hsp70) family are frequently observed in various human cancers. In this study, we examined applicability of laser scanning cytometer (LSC) to evaluate the level of Hsp72, which is the member constitutively expressed and significantly induced after heat shock, in human tumour cell lines. The relative nuclear content of Hsp72 measured by LSC correlated well with the relative intracellular content determined by Western blotting (R = 0.906). Furthermore, there was a close relationship between the relative nuclear content of Hsp72 measured by LSC and the colony-forming ability in soft agar, one of the malignant characteristics of tumour cells (R = 0.880). These results indicate that LSC measurement is useful for predicting the degree of malignancy of cancer cells, as it is reliable, faster than Western blotting and more objective and quantitative than visual measurements. [ABSTRACT FROM AUTHOR]

In human and canine cancers, the inactivation of p53 protein as well as p53 gene mutation and MDM2 overexpression result in centrosome amplification that in turn contributes to chromosomal instability. To explore the usefulness of the detection of centrosome amplification as a surrogate marker of dysfunction in the p53 pathway, we systematically analysed centrosome amplification, p53 overexpression, p53 gene mutation and MDM2 overexpression in canine tumours. Centrosome amplification was detected in 16 of 51 (31%) naturally developing tumours in dogs. All the tumour specimens with aberrations in the p53 pathway, including p53 overexpression, p53 gene mutation or MDM2 overexpression, showed centrosome amplification, suggesting that the detection of centrosome amplification could serve as a preliminary surrogate marker of dysfunction in the p53 pathway. [ABSTRACT FROM AUTHOR]