ABSTRACT
p21 is induced by and mediates the effects of p53 in response to DNA damage arresting the cell in G1 or G2, by inhibiting multiple cyclin-cyclin-dependent kinases (CDK) or binding to proliferating-cell nuclear antigen (PCNA), respectively. To determine whether p21 mutants occur in tumors we examined DNA from 188 primary non-Hodgkin's B-cell lymphoma (NHL) tumors and 84 chronic myelogenous leukemia samples for mutational changes in the coding region of p21 by single-strand conformation polymorphism (SSCP) analysis and direct sequencing of polymerase chain reaction (PCR)-amplified DNA. We did not find mutations in the coding region in these two tumor types. We identified a polymorphic nucleotide change in codon 31 in which a transversion from C to A substituted amino acid arginine for serine. Three of 188 NHL tumors were homozygous for this change, but they were not identified in 84 CMLs or in 97 normal controls. On the other hand, in one CML case a transition from G to A in codon 64 substituted amino acid threonine for alanine. These data do not indicate that derangements in the coding region of p21 contribute to the initiation and/or progression of these tumors.
Subject(s)
Cyclin-Dependent Kinases/antagonists & inhibitors , Cyclin-Dependent Kinases/genetics , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics , Lymphoma, B-Cell/genetics , Base Sequence , Blast Crisis/genetics , DNA, Neoplasm/analysis , Genes, Tumor Suppressor , Humans , Molecular Sequence Data , MutationABSTRACT
A phase II trial of gallium nitrate (250-300 mg/m2/day for 7 consecutive days) was conducted in patients with metastatic melanoma. Therapy was well-tolerated, but only one of 31 evaluable patients experienced a partial regression. Further evaluation of gallium nitrate at this dose and schedule is not warranted in patients with malignant melanoma.
