Characterization of Int-5, a locus associated with early events in mammary carcinogenesis.
Three chemically-induced precancerous mammary hyperplasias, independently isolated in BALB/c mice, all contained mouse mammary tumor virus (MMTV) proviral DNA integrated into a common region in chromosomal DNA, designated Int-5 (Formerly Int-H, Gray et al., 1986). This site was cloned from a hyperplastic outgrowth (D2) into lambda phage. A 1.7 Kb Hind III DNA fragment, which flanks the 5' end of the MMTV insert, was generated from the cloned Int-5 region. This fragment was used as probe (IH-2) to localize Int-5 to mouse chromosome 9. The IH-2 sequence was highly conserved in DNA of several mammalian species including man, in three other widely divergent vertebrate phyla, and in C. elegans. The Int-5 region, containing 5.6 Kb 5' and 12.8 Kb 3' to the MMTV integration site in D2, was cloned in EMBL-3 from a BALB/c genomic DNA library. cDNA complementary to poly A+ lactating mammary gland RNA, annealed with Sst-1 fragments spanning most of the BALB/c Int-5 clone. The highest level of Int-5 specific poly A+ mRNA was detected in D2 tumor. Lactating mammary gland and D2 hyperplastic alveolar nodule contained 5-fold less Int-5 RNA while liver contained 8-fold less Int-5 RNA. Int-5 cDNA (IH-3) annealed with two RNA species of approximately 3.3 and 4.0 Kb. These data are consistent with the hypothesis that Int-5 contains an oncogene, different from any other previously described, involved in early events in some models of chemical carcinogenesis.
Morris
V L
VL
Department of Microbiology and Immunology, University of Western Ontario, London, Canada.
Rao
T R
TR
Kozak
C A
CA
Gray
D A
DA
Lee Chan
E C
EC
Cornell
T J
TJ
Taylor
C B
CB
Jones
R F
RF
McGrath
C M
CM
D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis; D015342:DNA Probes; D008325:Mammary Neoplasms, Experimental / Q000235:genetics* / Q000382:microbiology; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D009693:Nucleic Acid Hybridization; D012313:RNA / Q000032:analysis; D015183:Restriction Mapping
D015342:DNA Probes; D012313:RNA; D004247:DNA