An association between inflammation and cancer has long been recognized, but the cause and effect relationship linking the two remains unclear. Myc is a pleiotropic transcription factor that is overexpressed in many human cancers and instructs many extracellular aspects of the tumor tissue phenotype, including remodeling of tumor stroma and angiogenesis. Here we show in a beta-cell tumor model that activation of Myc in vivo triggers rapid recruitment of mast cells to the tumor site-a recruitment that is absolutely required for macroscopic tumor expansion. In addition, treatment of established beta-cell tumors with a mast cell inhibitor rapidly triggers hypoxia and cell death of tumor and endothelial cells. Inhibitors of mast cell function may therefore prove therapeutically useful in restraining expansion and survival of pancreatic and other cancers.

Based on the high incidence of loss of heterozygosity for loci on chromosome 17p in the vicinity of the p53 locus in human breast tumors, we investigated the frequency and effects of mutations in the p53 tumor suppressor gene in mammary neoplasia. We examined the p53 gene in 20 breast cancer cell lines and 59 primary breast tumors. Northern blot analysis, immunoprecipitation, and nucleotide sequencing analysis revealed aberrant mRNA expression, overexpression of protein, and point mutations in the p53 gene in 50% of the cell lines tested. A multiplex PCR assay was developed to search for deletions in the p53 genomic locus.

Genetic alpha-tryptase deficiency is common and varies strikingly between ethnic groups. Because beta-tryptases are implicated in allergic disorders, inherited differences in alpha/beta-genotype may affect disease susceptibility, severity and response to tryptase inhibitor therapy.

Research in the last 3 years has made it increasingly clear that a large variety of human tumors contain mutated p53 tumor suppressor genes (reviewed in ref. 1). Since mutations are most often distributed over at least 5 exons (exons 5-9) spanning 2.9 kb of coding sequence, faster methods for scanning the region have been developed. ~2)A popular method for detection of point mutations and deletions in the p53 gene is single-stranded conformation polymorphism (SSCP). (2'3) The technique is based on altered migration speeds through solid supports of singlestranded DNA fragments carrying mutations. The altered migration of DNA is presumably caused by differences in the conformation of single-stranded DNA. The method depends heavily on experimental conditions that optimize migration differences of the conformation polymorphs. Thus, adding glycerol to the polyacrylamide, reducing the temperature, increasing the length of the run, and so forth result in a greater level of reproducibility. ~2' 3~ In spite of these modifications, reproducibility and resolution present recurrent problems using polyacrylamide as a gel support, presenting the need for novel polymers for this purpose. There is also a need to develop a simple nonradioactive technique for screening for mutations in the p53 gene in the clinical laboratory. A gel electrophoresis technique that takes advantage of differences in mobility of wild-type and mutation-bearing DNA fragments could prove useful for this purpose. Double-stranded DNA as heteroduplexes (HTX) migrate at different rates compared to DNA as homoduplexes in solid supports. (4's~ These differences can be visualized easily by staining with ethidium bromide. However, the resolution ability of polyacrylamide gel supports for detection of the two species varies with the sequence of the DNA fragments. ~4' s~In an effort to improve the sensitivity levels of the radioactive SSCP analysis, and to resolve the nonradioactive duplexes, we began to experiment with other polymers. We tested polyacrylamide, Hydrolink-D5000, and Hydrolink-MDE under identical experimental conditions with and without 10% glycerol. We found that Hydrolink-MDE (AT Biochem, Malvern, PA), a vinyl polymer, gave improved resolution of bands as well as reproducibility in the detection of both single-stranded DNA in SSCP and of DNA duplexes in the HTX analyses. Because the SSCP analysis is unable to detect mutations that do not result in polymorphs with altered migrations, a combination of SSCP analysis with HTX analysis might provide more reliable results than either one alone.Human mammary tumors were analyzed by SSCP for mutations in p53 exons 5-9 using 5% polyacrylamide. ~6) A cell line derived from normal breast tissue (HBL-100) was used as a negative control, whereas breast tumor cell lines served as positive controls (SKBR3 and HS578 for exon 5, T47D for exon 6, MW for exon 7, and BT474 for exon 8). The colon cancer cell line, SW480 was used as a positive control for mutation in exon 9 of the p53 gene. It should be noted that thes...