Heat shock protein 70 (Hsp70) subtype expression in neuroendocrine tissue and identification of a neuroendocrine tumour-specific Hsp70 truncation.
In order to identify neuroendocrine tumour-specific protein expression, we generated monoclonal antibodies (mAbs) with a tumour-related reaction pattern using a human insulinoma as immunogen. One of the generated mAbs (mAb 1D4) exhibited striking immunoreactivity against various neuroendocrine tumours without staining pancreatic islets of Langerhans. Furthermore, mAb 1D4 immunostained a characteristic subtype of hypothalamic neurones. Using two-dimensional (2-D) gel electrophoresis, mAb 1D4 immunoblotting and mass spectrometry, heat shock protein 70 (Hsp70) isoforms were identified as the mAb 1D4-specific antigen. In hypothalamic tissue, the presence of two different Hsp70 isoforms (Hsp70-8 and Hsp70-1) was revealed by 2-D gel immunoblots and consecutive mass spectrometric peptide analysis. In contrast, insulinoma and other neuroendocrine tumours displayed solely Hsp70-8 expression. Moreover, the tumour-specific presence of an additional mAb 1D4 immunoreactive protein of 40 kDa was observed in eight out of eight tested neuroendocrine tumours. For this variant, exclusively, peptides derived from the C terminus excluding the 299 amino-terminal residues were detected. In cultured tumour-derived fibroblasts, expression of the truncated Hsp70-8 subtype was not present. In conclusion, we have demonstrated a neuroendocrine tumour-specific expression pattern of Hsp70 isoforms and identified an as yet unknown N-terminally truncated Hsp70-8 variant.
Zierhut
B
B
Department of Medicine III, Division of Clinical Endocrinology and Metabolism, University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
Mechtler
K
K
Gartner
W
W
Daneva
T
T
Base
W
W
Weissel
M
M
Niederle
B
B
Wagner
L
L
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D002276:Carcinoid Tumor / Q000378:metabolism / Q000473:pathology; D015180:Electrophoresis, Gel, Two-Dimensional; D018840:HSP70 Heat-Shock Proteins / Q000145:classification / Q000378:metabolism*; D006801:Humans; D007340:Insulinoma / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D013058:Mass Spectrometry; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D018358:Neuroendocrine Tumors / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D010673:Pheochromocytoma / Q000378:metabolism / Q000473:pathology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
D000911:Antibodies, Monoclonal; D018840:HSP70 Heat-Shock Proteins; D011993:Recombinant Fusion Proteins