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Thierry Soussi

Publications and source records attributed to Thierry Soussi.

27 records · Page 2Linked to original sources
PubMed2003

Serum p53 antibodies in patients with lung cancer: correlation with clinicopathologic features and smoking.

Abnormalities of p53 gene can lead to the production of p53 antibodies (p53-Abs) in the serum of cancer patients. This study was designed to investigate the prevalence of p53-Abs in 133 lung cancer patients and the distribution of these antibodies to clinicopathologic features and smoking status. Twenty five (18.8%) lung cancer patients were found to have p53-Abs. The presence of p53-Abs did not correlate with sex or age but showed frequent association with tumors of squamous cell carcinoma (31%) in comparison with adenocarcinoma (13.6%) (P=0.052). There was a statistically significant difference in the incidence of p53-Abs between early disease group (stage I-II) and the advanced group (stage III-IV) (P=0.036), however, there was no relationship between the presence of p53-Abs and overall survival. Interestingly, the frequent of p53-Abs was higher in smokers (27.1%) than in non-smokers (13.6%), though the difference was of borderline of statistical significance (P=0.061). These findings suggested that p53-Abs could be a potential biomarker for the study of individual with lung cancer.

Adenocarcinoma↗
PubMed2003

[p53 mutations and resistance to chemotherapy: a stab in the back for p73?].

p53 gene is a member of a multigene family that includes p53, p63 and p73. The association of p73 and p63 with cell transformation has been elusive as no genetic or epigenetic alteration of these genes has been uncovered yet. Recent work has shown clearly that p73 is an essential component of the signaling pathway that lead to apoptosis after DNA damage induced by cytotoxic agents use in cancer therapy. Furthermore, it has been established that a sub-category of mutant p53 is able to interact with p73 and inhibit its apoptotic activity. Such discovery will be important for a better understanding of the signaling pathway that lead to resistance to chemotherapy.

Apoptosis↗
PubMed2002

An endonuclease/ligase based mutation scanning method especially suited for analysis of neoplastic tissue.

Knowledge of inherited and sporadic mutations in known and candidate cancer genes may influence clinical decisions. We have developed a mutation scanning method that combines thermostable EndonucleaseV (Endo V) and DNA ligase. Variant and wild-type PCR amplicons are generated using fluorescently labeled primers, and heteroduplexed. Thermotoga maritima (Tma) EndoV recognizes and primarily cleaves heteroduplex DNA one base 3' to the mismatch, as well as nicking matched DNA at low levels. Thermus species (Tsp.) AK16D DNA ligase reseals the background nicks to create a highly sensitive and specific assay. The fragment mobility on a DNA sequencing gel reveals the approximate position of the mutation. This method identified 31/35 and 8/8 unique point mutations and insertions/deletions, respectively, in the p53, VHL, K-ras, APC, BRCA1, and BRCA2 genes. The method has the sensitivity to detect K-ras mutations diluted 1 : 20 with wild-type DNA, a p53 mutation in a 1.7 kb amplicon, and unknown p53 mutations in pooled DNA samples. EndoV/Ligase mutation scanning combined with PCR/LDR/Universal array proved superior to automated DNA sequencing for detecting p53 mutations in colon tumors. This technique is well suited for scanning low-frequency mutations in pooled samples and for analysing tumor DNA containing a minority of the unknown mutation.

Adenocarcinoma↗
PubMed2002

Monoclonal antibodies raised against Xenopus p53 interact with human p73.

The p53 tumor suppressor gene belongs to a multigene family that includes two paralogues, p63 and p73. The structure of the p63 and p73 genes is quite similar, but both have common activities with p53, such as DNA binding and transactivation. Both p53 and p73 bind to mdm2, but only p53 is degraded through the activity of mdm2. p63 neither binds to nor is degraded by mdm2 despite important conservation in the key interacting residues. Using a panel of monoclonal antibodies raised against human and Xenopus p53, we have been able to find several antibodies that cross-react strongly with human p73. These antibodies react both with exogenous p73 expressed in mammalian cells and with endogenous p73. Interestingly, all these antibodies react with the same epitope localized in the amino-terminus of p53, but have no cross-reaction with p63. This epitope corresponds to the exact mdm2 binding site to p53. These antibodies inhibit the interaction between either p53 or p73 and mdm2, and may be useful tools for the study of these proteins. Furthermore, our studies suggest that there exist specific spatial requirements for the interaction between p53 or p73 and mdm2.

Amino Acid Sequence↗
PubMed2002

The human BTG2/TIS21/PC3 gene: genomic structure, transcriptional regulation and evaluation as a candidate tumor suppressor gene.

BTG2/TIS21/PC3 protein is involved in the regulation of G1/S transition of the cell cycle by inhibiting pRb function, suggesting that BTG2/TIS21/PC3 regulation is critical for normal cell growth and proliferation. To understand the regulatory mechanisms for the expression of BTG2/TIS21/PC3 we cloned the human gene. Potential binding sites for several transcription factors were identified in the 5'-flanking region of the gene. Transient expression assays with BTG2/TIS21/PC3 promoter deletions and electrophoretic mobility shift analysis identified a major wild-type p53 response element located -74 to -122 relative to the start codon. This genomic fragment was sufficient to constitute a promoter element in the presence of p53. The BTG2/TIS21/PC3 gene is an antiproliferative gene which maps within a chromosomal segment (1q32) frequently altered in breast adenocarcinomas. However, no mutations of BTG2/TIS21/PC3 were detected in breast cancer cells, suggesting that the inactivation of this gene is not a frequent genetic event during breast carcinogenesis.

Base Sequence↗
PubMed2002

Targeted expression of oncogenic K-ras in intestinal epithelium causes spontaneous tumorigenesis in mice.

BACKGROUND & AIMS: Ras oncoproteins are mutated in about 50% of human colorectal cancers, but their precise role in tumor initiation or progression is still unclear. METHODS: This study presents transgenic mice that express K-ras(V12G), the most frequent oncogenic mutation in human tumors, under control of the murine villin promoter in epithelial cells of the large and small intestine. RESULTS: More than 80% of the transgenic animals displayed single or multiple intestinal lesions, ranging from aberrant crypt foci (ACF) to invasive adenocarcinomas. Expression of K-ras(V12G) caused activation of the MAP kinase cascade, and the tumors were frequently characterized by deregulated cellular proliferation. Unexpectedly, we obtained no evidence of inactivating mutations of the tumor suppressor gene Apc, the "gatekeeper" in colonic epithelial proliferation. However, spontaneous mutation of the tumor-suppressor gene p53, a frequent feature in the human disease, was found in 3 of 7 tumors that were tested. CONCLUSIONS: This animal model recapitulates the stages of tumor progression as well as a part of the genetic alterations found in human colorectal cancer. Furthermore, it indicates that activation of K-ras in concert with mutations in p53 may constitute a route to digestive tumor formation and growth, underlining the fact that the pathway to intestinal cancer is not necessarily a single road.

Animals↗
PubMed2002

[Immunochemistry and genotype analysis of tumors. Second part: What future for the molecular diagnosis of tumors?].

The twentieth century has witnessed the discovery of the various genetic alterations that drive a normal cell toward neoplasia. The challenge of the near future concerns the diagnostic of these alterations and their correlation with clinical parameters such as response to therapy or survival. It will be important to define, for each patient, a specific profile of the various alterations in order to improve and personalize the therapy. It is also essential to understand the various mechanisms of these alterations in order to develop new diagnostic procedures. Furthermore, the relation between genotype and phenotype is not straightforward and can be influence by various parameters such as the localization of the mutation, the alterations of other genes or the expression of modifier genes.

Genetic Techniques↗
PubMedDate not supplied

Lack of HIN-1 methylation defines specific breast tumor subtypes including medullary carcinoma of the breast and BRCA1-linked tumors.

Medullary carcinoma is a poorly differentiated breast cancer with a high histologic grade and a paradoxically good prognosis. It accounts for only 3 percent of all breast cancers except in BRCA-1 families, in which it can account for as many as 13 percent of cancers. To date, only histologic criteria have been used to define this tumor type. In an attempt to more clearly define the genetic pathway leading to this subtype of cancer, we recently demonstrated that nearly 100 percent of these carcinomas display p53 mutations. In the present study, we extended our analysis to include HIN-1, a candidate tumor suppressor that has been shown to be silenced by methylation in the majority of breast tumors. In striking contrast to unselected sporadic invasive ductal carcinoma, we show that medullary carcinomas do not display a high frequency of HIN-1 methylation (p less than 0.001). This feature is also found in BRCA-1 associated tumors that shared several histologic characteristics with medullary carcinomas of the breast. Medullary carcinoma of the breast should therefore be considered to be a unique entity defined by specific histologic and molecular traits.

Breast Neoplasms↗