The pathological response to DNA damage does not contribute to p53-mediated tumour suppression.

The p53 protein has a highly evolutionarily conserved role in metazoans as 'guardian of the genome', mediating cell-cycle arrest and apoptosis in response to genotoxic injury. In large, long-lived animals with substantial somatic regenerative capacity, such as vertebrates, p53 is an important tumour suppressor--an attribute thought to stem directly from its induction of death or arrest in mutant cells with damaged or unstable genomes. Chemotherapy and radiation exposure both induce widespread p53-dependent DNA damage. This triggers potentially lethal pathologies that are generally deemed an unfortunate but unavoidable consequence of the role p53 has in tumour suppression. Here we show, using a mouse model in which p53 status can be reversibly switched in vivo between functional and inactive states, that the p53-mediated pathological response to whole-body irradiation, a prototypical genotoxic carcinogen, is irrelevant for suppression of radiation-induced lymphoma. In contrast, delaying the restoration of p53 function until the acute radiation response has subsided abrogates all of the radiation-induced pathology yet preserves much of the protection from lymphoma. Such protection is absolutely dependent on p19(ARF)--a tumour suppressor induced not by DNA damage, but by oncogenic disruption of the cell cycle.

Oncogene-dependent tumor suppression: using the dark side of the force for cancer therapy.

Cancers arise by an evolutionary process that involves the protracted acquisition by somatic cells of suites of interlocking mutations that uncouple proliferation, survival, migration, and damage responses from the mechanisms (selective pressures) that normally restrain or restrict them in time and space. The relative rareness of cancer cells within the soma, in the face of huge numbers of available cell targets, substantial rates of mutation, and an abundance of proto-oncogenes and tumor suppressor gene targets, indicates that the evolutionary space available to incipient tumor cells is highly restricted. The principal way in which this is achieved is through intrinsic tumor suppression pathways-innate growth arrest and apoptotic programs that fulfill an essentially analogous functional role to checkpoints in the cell cycle machinery by antagonizing the tumorigenic potential of oncogenic mutations. Using switchable transgenic and knockin mouse models, it is possible to identify these various tumor suppressor programs and establish where, when, how, and why they act to forestall neoplasia in each tissue type and, consequently, how and why their failure leads to cancer.

Greek Cypriot allele and genotype frequencies for Amplitype PM-DQA1 and D1S80 loci.

A sample from the Greek Cypriot population was typed at seven forensically important PCR-based loci: LDLR, GYPA, HBGG, D7S8, GC, HLA-DQA1, and D1S80. The results showed that all loci meet Hardy-Weinberg expectations and that there is no evidence for association of alleles between loci. Allelic frequency distributions at all loci, except HLA-DQA1 and two D1S80 alleles, were similar to those of U.S. Caucasians. Greek Cypriot population databases have been created and can be used for forensic analyses to estimate the frequency of a multiple locus DNA profile.

Median cleft lip, polydactyly, syndactyly and toe anomalies in a non-Indian infant.

A case is reported of a child who presented with a median cleft of the lip and alveolus with polydactyly, a complex form of syndactyly and multiple toe anomalies. This is the fifth case to be reported with these features and the second case to be reported in a non-Indian patient. Our case is characterised by unique features, consisting of a complexity of hand anomalies in association with other facial anomalies such as median alveolar cleft, epicanthus, fusion of the tongue to the floor of the mouth and rare big toe anomalies.