ABSTRACT
MCF2/DBL is an X-linked proto-oncogene encoding a protein with a yet undetermined function. It can be activated in vitro by loss of 5' sequences in NIH3T3 bioassays; in vivo, deletion of the gene has been found in some hemophilia B patients. PCR analysis of its expression in mouse tissues shows a restriction to the gonads and tissues of neuroectodermal origin. It also identifies an exon encoding 42 amino acids that is alternatively spliced in murine, but not human testis.
Subject(s)
Protein-Tyrosine Kinases/genetics , Proto-Oncogene Proteins/genetics , Proto-Oncogenes , X Chromosome , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , Cosmids , Exons , Gene Expression , Guanine Nucleotide Exchange Factors , Humans , Kinetics , Male , Mice , Molecular Sequence Data , Organ Specificity , Polymerase Chain Reaction/methods , Proto-Oncogene Mas , RNA Splicing , RNA, Messenger/genetics , Restriction Mapping , Sequence Homology, Nucleic Acid , Testis/physiologyABSTRACT
A mouse cDNA clone from the ubiquitous glycolysis enzyme Gapdh was isolated from a testis library and sequenced. The gene presents abnormalities indicating that it is a pseudogene. It is expressed as a 1.9 kb minor transcript.
Subject(s)
Glyceraldehyde-3-Phosphate Dehydrogenases/genetics , Pseudogenes , Animals , Base Sequence , Cloning, Molecular , DNA/genetics , Male , Mice , Molecular Sequence Data , Open Reading Frames , Sequence Homology, Nucleic Acid , Testis/enzymologyABSTRACT
A tumorigenicity assay was performed using DNA extracted from the human mammary carcinoma cell line MCF-7. Seven nude mouse tumors were obtained and were analyzed for the presence of human sequences and known activated oncogenes. The c-erbB.2/neu gene was identified in two tumors and two ras oncogenes in two other tumors. In order to characterize the mechanism of activation of the c-erbB.2/neu oncogene, we isolated and analyzed this gene from one of the tumors. The cloned gene did not present any rearrangement. c-erbB.2/neu transcripts from the nude mice tumors were of normal size. In one case overexpression was observed.
Subject(s)
Breast Neoplasms/genetics , Proto-Oncogenes , Tumor Cells, Cultured/cytology , Animals , Blotting, Southern , Breast Neoplasms/pathology , Cell Line , Cloning, Molecular , Cosmids , DNA, Neoplasm/genetics , DNA, Neoplasm/isolation & purification , Female , Humans , Mice , Mice, Nude , Neoplasm Transplantation , Nucleic Acid Hybridization , Protein-Tyrosine Kinases/genetics , Proto-Oncogene Proteins/genetics , Receptors, Thyroid Hormone , Restriction Mapping , Transplantation, HeterologousABSTRACT
A system of tumor transplantation has been developed to select metastatic variants of B16 in mutants of the C57BL/6J black strain of mice. The effects of transplantation into nonagouti a/a and mutant recipients on the production of melanin and on the metastatic potential of tumors were investigated. Transplantation of the pigmented B16 melanoma from a nonagouti black a/a host to a yellow mutant Ay/a recipient resulted in an achromic and metastatic variant melanoma, designated YB16. The amelanotic phenotype occurred consistently after more than ten passages through yellow mice and simultaneously with an increase in the incidence of pulmonary metastases. When YB16 was transplanted back to the nonagouti black a/a host, a second variant, MB16, characterized by its variable pigmentation, was obtained. Pigmented and/or entirely achromic tumors were observed. MB16 was dramatically more metastatic than B16 and YB16 when injected s.c. or i.v. Metastases in the lungs were pigmented and/or achromic. The properties of tumor cells derived from artificially induced metastases were investigated after s.c. and i.v. injections. Whereas the metastatic cells expressed a potent ability to generate metastases when injected s.c., no differences in the incidence of metastases, as compared to the metastatic potential of cells of parental origin, were observed after i.v. injection. In the MB16 variant, there appeared to be an inverse relationship between differentiation (production of melanins) and malignancy. Our results demonstrate that differentiation and metastatic behaviour are dependent on specific mutations in the host environment which generate a pool of tumor cells from which highly metastatic variants can be selected.
