We report expression of the wt1 (Wilms' tumor) gene by cultured human melanoma cells. Using RNA polymerase chain reaction analysis, wt1 transcripts were detected in 7 of 9 melanoma cell lines but not in 5 normal melanocyte strains. In Northern blot analysis, steady-state wt1 mRNA levels were found in 2 of 4 melanoma lines but not in normal melanocytes. Sequence analysis of the wt1 cDNA expressed by melanoma cell line WM 902-B revealed the presence of 4 previously published splice variants but no evidence for mutations in the coding region. Previous work has shown that WT1 modulates transcription after binding to the early growth response (EGR)-1 sites present in the platelet-derived growth factor (PDGF)-A chain promoter; the PDGF-A chain gene is known to be expressed by various melanoma cell lines. Based on these findings, we studied the relationship of wt1 and PDGF-A chain gene expression in melanoma cell lines. Co-expression of the wt1 and the PDGF-A chain genes was observed in 2 melanoma cell lines with mutated p53 but not in 2 melanoma cell lines with wild-type p53; this result is consistent with a previous report showing that, in the context of absent or mutated p53, WT1 acts as a transcriptional activator, whereas in the presence of wild-type p53 it acts as a repressor.

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The morphologic findings in mildly active colonic Crohn's disease (CD) include crypt disarray, patchy edema, and small lymphoid aggregates with neutrophils, sometimes associated with aphthous ulcers. We describe four patients with CD whose colonic biopsies focally showed a lymphocytic colitis morphology, and one patient with CD whose biopsies showed a collagenous colitis morphology. The lymphocytic and collagenous colitis patterns of injury preceded the eventual clinical pathologic diagnosis of CD in four patients. Colonoscopic abnormalities were found in four patients. The lymphocytic colitis pattern was focal, involving some biopsy fragments, whereas other biopsy fragments were normal or had minimal nonspecific inflammation. In one patient, moderate numbers of neutrophils were admixed with the lymphoplasmacytic infiltrates. The presence of colonoscopic abnormalities, focal changes, and moderate admixed neutrophils could assist in the distinction from lymphocytic or collagenous colitis, both of which are colonoscopically normal, usually diffuse, and devoid of, or contain only a sparse number of, neutrophils. A limited number of biopsy fragments may be incorrectly interpreted as lymphocytic or collagenous colitis. The temporal relationships suggest that these morphologic patterns precede typical active CD.

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