Genetic alterations of the p14ARF -hdm2-p53 regulatory pathway in breast carcinoma.

TP53 is the most commonly mutated tumor suppressor gene in human cancers. The amplification and overexpression of HDM2 plays a role in tumorigenesis via inactivation of p53-dependent cell cycle arrest. p14ARF, an alternate transcript of the INK4A tumor suppressor locus, prevents hdm2-induced transcriptional silencing of p53 by binding hdm2. The role of this p14ARF-hdm2-p53 regulatory pathway in breast carcinoma is unknown. We hypothesized that p14ARF mutations and HDM2 gene amplification may be alternative mechanisms of p53 inactivation in breast cancer. Mutational analysis of TP53 (exons 5-9) and exon 1beta of pl4ARF was performed by PCR-SSCP and putative mutations were confirmed by sequencing. p14ARF mRNA expression was evaluated by RT-PCR and the presence of HDM2 gene amplification by differential PCR. Among the cell lines, 7/14 (50%) harbored TP53 mutations and 2/14 (14%) had a deletion ofp14ARF exon 1beta with no detectable p14ARF mRNA. None demonstrated HDM2 gene amplification. TP53 mutations were identified in 7/36 (19%) breast tumors and HDM2 amplification in 2/30 (7%) tumors. All the tumors contained an intact p14ARF exon 1beta with corresponding expression of the mRNA. Alterations in the various components of this regulatory pathway were identified in nine (64%) cell lines and 25% of the 36 breast cancers with TP53 mutation being the predominant aberration. Although p14ARF mutations and HDM2 gene amplification appear to be uncommon events in breast carcinoma, deregulation of this pathway may occur via alternative mechanisms in breast carcinogenesis.

A critical reappraisal of indications for fasciotomy after extremity vascular trauma.

OBJECTIVE: To critically reevaluate the indications for fasciotomy in vascular trauma of the extremities. DESIGN: Case-control study. SETTING: Level I trauma center. MATERIALS AND METHODS: One hundred sixty-three vascular injuries to the extremeties were analyzed. Fasciotomy as an adjunct to vascular repair was performed in 45 limbs (28%), based either on the nature of injury or measured compartment pressure of greater than 35 mm Hg. MAIN OUTCOME MEASURES: Need for fasciotomy or limb amputation. RESULTS: Fasciotomy was performed for 29.5% of isolated arterial injuries, 15.2% of isolated venous injuries, and 31.6% of combined arterial and venous injuries, and was not related to venous repair or ligation. Seven delayed fasciotomies were performed either for vascular repair failure (5 patients) or compartment syndrome (2 patients). The highest incidence was for popliteal vessel injury (arterial 57%, combined 61%). Of the 33 lower-extremity fasciotomies, 58% were for popliteal vessel injury. In 51 combined injuries of the lower extremity, only 7 (19%) of 38 patients with injury above the knee required fasciotomy, as compared with 8 (62%) of 13 with injury to the popliteal vessels (P<.001), with or without venous repair. There were 3 amputations, all resulting from vascular repair failure. CONCLUSIONS: The presence of a combined vascular injury or the need for venous ligation does not necessitate routine fasciotomy. The need for fasciotomy may be maximal for injuries to popliteal vessels.

Analysis of MTS1/CDK4 in female breast carcinomas.

Multiple factors, both environmental and genetic, are thought to play roles in breast carcinogenesis. The recently cloned multiple tumor suppressor gene (MTS1), the product of which interacts with CDK4 to regulate cell growth, has been found to be mutated with high frequency in a variety of cell lines as well as primary tumors of different histologic types. Using PCR-SSCP, we analyzed exons one (126 bp) and two (307 bp) of the MTS1 gene to determine the incidence of mutation in a population of 50 primary breast adenocarcinomas and corresponding normal tissue. Analysis of five breast tumor cell lines was also performed. We found no mutations in the MTS1 gene in the primary breast tumor samples. One cell line was found to have a homozygous deletion of the gene. Our results suggest that the MTS1 gene is not mutated with increased frequency in primary breast tumors, and thus may not play a major role in breast carcinogenesis.