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J Bertholon

Publications and source records attributed to J Bertholon.

9 recordsLinked to original sources
PubMed2000

A novel SMAD4 gene mutation in seminoma germ cell tumors.

Transforming growth factor (TGF)-beta is known as an antiproliferative factor in the majority of mammalian cells, including stem germ cells. Lack of TGF-beta-induced growth inhibition has been associated with disruptions of TGF-beta receptors and SMADs. In the present study, we performed a mutational analysis of the TGF-beta signaling system, including TGF-beta receptor type I and type II and SMADs (SMAD1-SMAD7), in 20 seminoma germ cell tumors. Using reverse transcription-PCR, single-strand conformational polymorphism, and sequencing analysis, the COOH-terminal domain of SMAD4 was found to be mutated: a single thymine was inserted between nt 1521 and 1522 in 2 of 20 tumors analyzed. This addition of a thymine creates a frameshift and a new stop signal at codon 492, which leads to premature termination of the encoded protein. Such a mutation potentially abrogates signaling from TGF-beta as well as the other TGF-beta family members, including activin and bone morphogenetic protein, which all use the SMAD pathway. Immunohistological analysis confirmed the loss of expression of SMAD4 protein in the seminoma tissues with the insertional mutation. To our knowledge, this is the first description of a novel SMAD4 insertional mutation in seminoma testicular germ cell tumors. This mutational inactivation of SMAD4/COOH-terminal domain may cause TGF-beta unresponsiveness. It could thus provide a basis for understanding the potential role of the TGF-beta system in germ cell tumorigenesis.

Amino Acid Sequence↗
PubMed1998

Variability of Ha-ras (codon 12) proto-oncogene mutations in diverse thyroid cancers.

Structural alterations to proto-oncogene sequences may be involved in the pathogenesis of human thyroid neoplasms. We studied 128 thyroid tumours (35 benign and 93 malignant) for ras gene point mutations in three different codons (12, 13 and 61) using a restriction fragment length polymorphism technique and direct sequencing of double-stranded DNA on polymerase chain-reaction-amplified tumour DNA. We found a high frequency of ras mutation for the Ha-ras codon 12 in follicular adenomas (7 of 35), particularly in atypical adenomas (5 of 17), in follicular carcinomas (6 of 19), with a high percentage for Hurthle cell carcinomas (6 of 11), and in papillary carcinomas (4 of 66). Point mutations for other ras genes in different codons studied were weak to absent. No mutation was found in undifferentiated carcinomas (n = 8). The predominant amino acid substitution both in the adenomas and in the differentiated tumours was glycine to valine (GGC to GTC) at position 12 of the Ha-ras gene. Our results obtained on a large series confirm the frequent occurrence of Ha-ras codon 12 gene mutations both in adenomas and in carcinomas. The frequency of ras mutations is linked to the geographical origin of the population studied and varies (0-85%) from one cancer type to another according to published data. Therefore, these mutations are merely an expression of cellular transformation.

Adenocarcinoma, Follicular↗
PubMed1986

Mortality experience in a polyamide-polyester factory.

Chemical workers have become increasingly concerned about the presence of carcinogens in their occupational environment. As a result, a number of studies of excess cancer mortality have been undertaken in groups of workers with well-characterized exposures. This paper reports the results of one such study carried out in a polyamide-polyester factory in France. A retrospective cohort design was chosen to evaluate the effect of exposure to phthalates, nickel catalyzers, and other chemicals in the work environment. Only a slight excess of cancers, marginally related to exposure category yet not significantly related to length of exposure, was found. The cohort, however, was young but stable, and a continued follow-up is therefore both feasible and justifiable, since it is likely to yield important information about the potential hazards associated with the tergal polymer industry.

Chemical Industry↗