Analysis of p53 mutants for transcriptional activity.

Raycroft, Loretta; Schmidt, Juliann R.; Yoas, Karen; Hao, Mingming; Lozano, Guillermina

doi:10.1128/mcb.11.12.6067

Cited by 96 publications

(84 citation statements)

References 33 publications

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“…One tumour with a shifted band on exon 6 was unavailable for sequence, and although improbable, in this case we cannot exclude a silent polymorphism at codon 213 since the tumour was positively stained with anti-p53 antibody. We cannot speculate if every mutation encountered has the same prognostic value since each mutation alters the p53 conformation differently, leading to different biological properties and tumorigenic potential (Halevy et al, 1990;Raycroft et al, 1991;Mukhopadhyay & Roth, 1993).…”

Section: Discussionmentioning

confidence: 99%

p53 mutations and overexpression in locally advanced breast cancers

Faille

Crémoux²,

Jm³

et al. 1994

Br J Cancer

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Summary Alterations in the p53 gene were analysed in 39 patients with locally advanced breast cancers (LABCs) (stage III-IV) with inflammatory signs in most cases (UICC stage T4d = 32 patients) by molecular and immunohistochemical (IHC) approaches. All patients were included in the same therapy protocol. Using polymerase chain reaction (PCR) and a single-strand conformational polymorphism migration technique (SSCP), the presence of mutations in exons 2-11, covering the entire coding sequence of the p53 gene, was evaluated. Using the mouse specific anti-human p53 monoclonal antibody (PAb 1801), we also looked for overexpression of the p53 protein in tissue sections. In 16 cases shifted bands were reproducibly identified by PCR-SSCP, and all but one (localised to exon 10) were in exons 5-8, the usual mutational hotspots. Fifteen of these 16 samples were sequenced and 14 of the suspected mutations (36%) were confirmed. Most of them (12) were single nucleotide substitutions, and transitions were more frequent (eight cases) than transversions (four cases). Fourteen of the tumour samples were positively stained with the monoclonal antibody PAb 1801, 11 with nuclear staining only, two with mixed cytoplasmic and nuclear staining and one with cytoplasmic staining only. Staining patterns were very heterogeneous in terms of the percentage of positive cells (10-75%) and their distribution in the tissue section (isolated foci or dispersed cells). In 11 of the 14 mutated cases a positive immunostaining was observed. The presence of a p53 mutation was significantly associated with larger tumour diameter (X2 = 7.490, P = 0.0062) and the presence of clinical metastases (stage IV) (X2 = 10.113, P = 0.0015). A non-statistically significant trend of association was observed between p53 mutation, negative oestrogen receptors and lower response rate to therapy. Our results in this group of patients and the heterogeneity of the staining of tumour cells in tissue sections suggest that p53 mutations could be a late event in this non-familial form of breast cancer.

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Section: Discussionmentioning

confidence: 99%

p53 mutations and overexpression in locally advanced breast cancers

Faille

Crémoux²,

Jm³

et al. 1994

Br J Cancer

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“…The protein expressed by pMSV val135 contains an A to V change at amino acid 135, has a temperaturesensitive phenotype and is in a mutant conformation at 378C . Previous studies have indicated that at the non-permissive temperature, this mutant is defective for transcriptional activation (Raycroft et al, 1991;Jackson et al, 1995). No promoter activation was observed using the pMSV control vector.…”

Section: Distal and Proximal P53-binding Sites Permit Synergistic Tramentioning

confidence: 99%

Synergistic transcriptional activation of the MCK promoter by p53: tetramers link separated DNA response elements by DNA looping

et al. 1998

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The WAF1, Cyclin G and muscle creatine kinase (MCK) genes, all contain multiple copies of the consensus p53-binding element within their regulatory regions. We examined the role of these elements in transactivation of the muscle creatine kinase (MCK) gene by p53. The MCK promoter possesses distal (73182 to 73133) and proximal (7177 to 781) p53-binding elements within which residues 73182 to 73151 (distal) and 7176 to 7149 (proximal) show homology to the consensus p53-binding site. Using promoter deletion studies, we ®nd that both proximal and distal elements are required for high level, synergistic transcriptional activation in vivo. Electron microscopy indicates that p53-p53 interactions link proximal and distal p53-binding elements and cause looping out of intervening DNA, suggesting that this DNA sequence may be dispensable for synergy. This idea was con®rmed by progressive deletion of the DNA between p53-binding elements. Synergism persisted with spacing reduced to only 150 bp. Tetramerization-de®-cient p53 mutants were defective for transcriptional activation but still capable of synergy. Our results provide evidence for a model by which high level transcriptional activation of promoters with multiple p53 response elements is achieved.

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“…In vitro studies have shown that this p53 mutant binds poorly to a consensus DNA sequence recognized by wt p53 (Kern et al, 1991), and lacks wt p53 transactivation activity (Raycroft et al, 1991). Therefore, if it is functioning at the transcriptional level, it may regulate dierent target genes (Chen et al, 1992).…”

Section: Transduced P21mentioning

confidence: 99%

Expression of a p53 mutant in the epidermis of transgenic mice accelerates chemical carcinogenesis

et al. 1998

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To develop an in vivo model for studying the role of the p53 tumor suppressor in skin carcinogenesis, a murine p53 172H mutant (equivalent to human p53 175H ) was expressed in the epidermis of transgenic mice, utilizing a targeting vector based on the human keratin 1 gene (HK1.p53 m ). HK1.p53 m mice developed normally and did not exhibit an obvious epidermal phenotype or develop spontaneous tumors. However, these mice demonstrated an increased susceptibility to a two-stage chemical carcinogenesis protocol, with the rate of formation and number of papillomas being dramatically increased as compared to non-transgenic controls. The majority of papillomas in control mice regressed after termination of 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment, whereas p53 m papillomas progressed to carcinomas and metastases. In addition, more advanced malignancy, i.e., undierentiated spindle cell carcinomas, were exclusively observed in p53 m mice. Increased bromodeoxyuridine (BrdU) labeling, accompanied by decreased expression of p21, was observed in HK1.p53 m papillomas. In situ examination of centrosomes in HK1.p53 m papillomas also revealed marked abnormalities, with 75% of the cells containing 53 centrosomes/cell, whereas centrosome numbers in papillomas from control animals remained normal. These data suggest that the accelerated tumorigenesis observed in chemically-treated p53 m mice is most likely due to increased genomic instability resulting from an inhibition of G1 arrest and abnormal ampli®cation of centrosomes.

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Analysis of p53 mutants for transcriptional activity.

Abstract: The wild-type p53 protein functions to suppress

Cited by 96 publications

References 33 publications

p53 mutations and overexpression in locally advanced breast cancers

p53 mutations and overexpression in locally advanced breast cancers

Synergistic transcriptional activation of the MCK promoter by p53: tetramers link separated DNA response elements by DNA looping

Expression of a p53 mutant in the epidermis of transgenic mice accelerates chemical carcinogenesis

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