A large number of hDAF transgenic pigs to be used for xenotransplantation research were generated by using sperm-mediated gene transfer (SMGT). The efficiency of transgenesis obtained with SMGT was much greater than with any other method. In the experiments reported, up to 80% of pigs had the transgene integrated into the genome. Most of the pigs carrying the hDAF gene transcribed it in a stable manner (64%). The great majority of pigs that transcribed the gene expressed the protein (83%). The hDAF gene was transmitted to progeny. Expression was stable and found in caveolae as it is in human cells. The expressed gene was functional based on in vitro experiments performed on peripheral blood mononuclear cells. These results show that our SMGT approach to transgenesis provides an efficient procedure for studies involving large animal models.SMGT ͉ hyperacute rejection ͉ swine

Evidence of the involvement of cyclin gene alterations in human cancer is growing. In this study, we sought to determine the pattern of expression of cyclin D1 and cyclin E in normal and malignant thyroid cells. Quiescent rat thyroid cells in culture, induced to synthesize DNA by thyrotropin (TSH), expressed cyclin D1 gene after 6 hr and cyclin E gene with a peak at 18 hr from the stimulus; K‐ras‐transformed rat thyroid cells, which grew without addition of hormones necessary for normal cell proliferation, expressed elevated levels of cyclin D1 and cyclin E, compared with normal differentiated thyroid cells. Human benign and malignant thyroid tumors and their relative normal tissues were then analyzed. Neither major genetic alterations nor amplifications for cyclin D1 and cyclin E genes were found by Southern blot analysis in genomic DNAs extracted from all types of thyroid tumors. Moreover, statistical analyses of densitometric values from Northern blots did not show increased levels of cyclin D1 and E mRNAs in the tumor samples, compared with normal thyroid. Immunohistochemical analyses of formalin‐fixed, paraffin‐embedded sections of tissues with specific antibodies revealed a prevalent cytoplasmic cyclin E staining in the thyroid tissues analyzed. Cyclin D1, instead, was present in the cytoplasm of normal thyroids and adenomas, but in 31% of thyroid papillary carcinomas analysed, it was overexpressed, with a localization in the nucleus. Our in vivo observations suggest that unlike cyclin E, elevated nuclear cyclin D1 expression defines a subset of thyroid papillary carcinomas, and might be a contributory factor to thyroid tumorigenesis. Int. J. Cancer 76:806–811, 1998.© 1998 Wiley‐Liss, Inc.

Sensitivity to transforming growth factor-b is impaired in thyroid tumours. Similar to Mad -Mother Against Decapentaplegic-(Smad)4 is frequently altered in cancers, but its involvement in this system is unknown. We analysed 56 thyroid tumours of various histotypes for Smad4 mutations by PCR-SSCP and sequencing, linking them to Smad4 reactivity as examined by immunohistochemistry (IHC), and 29 of them also for abnormalities in RNA expression due to alternative splicing. In all, 15/56 cases (27%), both benign and malignant lesions, harbour alterations of Smad4 coding sequence. We found several novel intragenic mutations (13 missense, two silent, one frameshift and one large insertion-deletion), with high incidence in the linker region. A subset of mutated tumours failed to express Smad4 protein by IHC. We have also detected four alternatively spliced tumourassociated Smad4 isoforms, lacking portions of the linker region, and three more due to unreported internal exonexon rearrangements. Smad4 is both frequently mutated and deregulated by aberrant splicing in thyroid tumours and these alterations may contribute as an early event to thyroid tumorigenesis.

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