Dataset Information

Dysfunction of the TP53 tumor suppressor gene in lymphoid malignancies.

ABSTRACT: Mutations of the TP53 gene and dysregulation of the TP53 pathway are important in the pathogenesis of many human cancers, including lymphomas. Tumor suppression by p53 occurs via both transcription-dependent activities in the nucleus by which p53 regulates transcription of genes involved in cell cycle, DNA repair, apoptosis, signaling, transcription, and metabolism; and transcription-independent activities that induces apoptosis and autophagy in the cytoplasm. In lymphoid malignancies, the frequency of TP53 deletions and mutations is lower than in other types of cancer. Nonetheless, the status of TP53 is an independent prognostic factor in most lymphoma types. Dysfunction of TP53 with wild-type coding sequence can result from deregulated gene expression, stability, and activity of p53. To overcome TP53 pathway inactivation, therapeutic delivery of wild-type p53, activation of mutant p53, inhibition of MDM2-mediated degradation of p53, and activation of p53-dependent and -independent apoptotic pathways have been explored experimentally and in clinical trials. We review the mechanisms of TP53 dysfunction, recent advances implicated in lymphomagenesis, and therapeutic approaches to overcoming p53 inactivation.

SUBMITTER: Xu-Monette ZY

PROVIDER: S-EPMC3335376 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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Dysfunction of the TP53 tumor suppressor gene in lymphoid malignancies.

Xu-Monette Zijun Y ZY Medeiros L Jeffrey LJ Li Yong Y Orlowski Robert Z RZ Andreeff Michael M Bueso-Ramos Carlos E CE Greiner Timothy C TC McDonnell Timothy J TJ Young Ken H KH

Blood 20120124 16

Mutations of the TP53 gene and dysregulation of the TP53 pathway are important in the pathogenesis of many human cancers, including lymphomas. Tumor suppression by p53 occurs via both transcription-dependent activities in the nucleus by which p53 regulates transcription of genes involved in cell cycle, DNA repair, apoptosis, signaling, transcription, and metabolism; and transcription-independent activities that induces apoptosis and autophagy in the cytoplasm. In lymphoid malignancies, the frequ ...[more]

PMID: 22275381

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Project description:Several reports indicate a commonly deleted chromosomal region independent from, and distal to the TP53 locus in a variety of human tumors. In a previous study, we reported a similar finding in a rat tumor model for endometrial carcinoma (EC) and through developing a deletion map, narrowed the candidate region to 700 kb, harboring 19 genes. In the present work real-time qPCR analysis, Western blot, semi-quantitative qPCR, sequencing, promoter methylation analysis, and epigenetic gene expression restoration analyses (5-aza-2'-deoxycytidine and/or trichostatin A treatments) were used to analyze the 19 genes located within the candidate region in a panel of experimental tumors compared to control samples.Real-time qPCR analysis suggested Hic1 (hypermethylated in cancer 1), Inpp5k (inositol polyphosphate-5-phosphatase K; a.k.a. Skip, skeletal muscle and kidney enriched inositol phosphatase) and Myo1c (myosin 1c) as the best targets for the observed deletions. No mutation in coding sequences of these genes was detected, hence the observed low expression levels suggest a haploinsufficient mode of function for these potential tumor suppressor genes. Both Inpp5k and Myo1c were down regulated at mRNA and/or protein levels, which could be rescued in gene expression restoration assays. This could not be shown for Hic1.Innp5k and Myo1c were identified as the best targets for the deletions in the region. INPP5K and MYO1C are located adjacent to each other within the reported independent region of tumor suppressor activity located at chromosome arm 17p distal to TP53 in human tumors. There is no earlier report on the potential tumor suppressor activity of INPP5K and MYO1C, however, overlapping roles in phosphoinositide (PI) 3-kinase/Akt signaling, known to be vital for the cell growth and survival, are reported for both. Moreover, there are reports on tumor suppressor activity of other members of the gene families that INPP5K and MYO1C belong to. Functional significance of these two candidate tumor suppressor genes in cancerogenesis pathways remains to be investigated.

Dataset Information

Dysfunction of the TP53 tumor suppressor gene in lymphoid malignancies.

Publications

Dysfunction of the TP53 tumor suppressor gene in lymphoid malignancies.

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