Expression of laminin-2 by normal and neoplastic rat C cells during the development of medullary thyroid carcinoma.
Medullary thyroid carcinoma (MTC) originates from C cells, which secrete calcitonin (CT), their specific marker. C cells are located in contact with the basement membrane (BM) of the thyroid follicles, which is partly made up of the laminin-2 isoform synthesized by thyrocytes. During oncogenesis, proliferation of the C cells, invading the centre of the follicles, leads to a break in their normal contact with the BM. As specific interactions of cells with BM components, especially laminins, are important for proliferation and differentiation, we investigated the relationships of normal and neoplastic C cells with laminin in the Wag/Rij rat model of human MTC. Immunocytochemical studies showed a progressive loss of the laminin layer underlying the hyperplastic C cell nodules around the large dedifferentiated tumours. The alpha2, beta1 and gamma1 chains of the laminin-2 isoform were synthesized and secreted by rat MTC 6-23 cell cultures and the tumours induced by subcutaneous injection of these cells. In situ hybridization combined with anti-CT immunocytochemistry showed a low expression of alpha2 mRNA on differentiated C cells and thyrocytes, but an overexpression on immunonegative spontaneous MTC and induced intrathyroid tumours. The high level of alpha2 gene expression, together with tumour dedifferentiation, suggests a relationship with malignancy.
Lekmine
F
F
Laboratoire d'Endocrinologie Cellulaire et Evolution, URA 1116 CNRS, Université Paris-Sud, Orsay, France.
Feracci
H
H
Milhaud
G
G
Treilhou-Lahille
F
F
Jeanne
N
N
D000818:Animals; D001485:Basement Membrane / Q000378:metabolism / Q000473:pathology; D018276:Carcinoma, Medullary / Q000378:metabolism* / Q000473:pathology; D017931:DNA Primers / Q000737:chemistry; D004195:Disease Models, Animal; D005260:Female; D017403:In Situ Hybridization; D007797:Laminin / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013961:Thyroid Gland / Q000378:metabolism* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology
D017931:DNA Primers; D007797:Laminin; D012333:RNA, Messenger; C102645:laminin alpha 2