Mapping Data

Experiment

• Experiment
  TEXT-QTL
• Chromosome
  7
• Reference
  J:97671 Lancaster M, et al., Modifiers of mammary tumor progression and metastasis on mouse chromosomes 7, 9, and 17. Mamm Genome. 2005 Feb;16(2):120-6
• ID
  MGI:3579326

Genes

Gene	Assay Type
D7Mit246	PCR
Mmtp1	visible phenotype

Notes

• Experiment
  Previously identified loci showing suggestive linkage to modification of mammary tumors induced by the mouse mammary tumor virus polyomavirus middle T antigen (MMTV-PyVT) were studied further using chromosome substitution strains (CSSs). Separate lines were created using I/LnJ or NZB/BlNJ as the donor strain for mouse Chromosomes 7, 9, 17, and 19 and FVB/NJ as the recipient strain. The following consomic lines were investigated: FVB/NJ-Chr 7^I/LnJ, FVB/NJ-Chr 9^I/LnJ, FVB/NJ-Chr 9^NZB/BlNJ, FVB/NJ-Chr17^NZB/BlNJ, and FVB/NJ-Chr 19^NZB/BlNJ.
  
  Each CSS strain was crossed to the transgenic FVB/N-Tg(MMTV-PyVT)634Mul/J to observe modification of tumor latency. Only the chromosome 7 congenic, FVB/NJ-Chr 7^I/LnJ, when crossed to FVB/N-Tg(MMTV-PyVT)634Mul/J showed acceleration of mammary tumor progression, or decreased tumor latency. This finding confirms the previously identified suggestive mammary tumor modifier on mouse Chromosome 7 near D7Mit246 (15 cM). This locus is named Mmtp1 (modifier of mammary tumor progression 1). The FVB/NJ-Chr 7^I/LnJ CCS also exhibits reduced tumor mass, confirming the presence of a previously identified QTL named Mmtg3 (modifier of mammary tumor growth 3) at 3 cM. Mmtg3 is believed to be separate and distinct from Mmtp1.
  
  The chromosome 9 consomic line FVB/NJ-Chr 9^I/LnJ exhibits a 20% decrease in mammary tumor burden compared to control strain FVB/N-Tg(MMTV-PyVT)634Mul/J. These animals also exhibit decreased number and size of metastatic pulmonary tumors when crossed to FVB/NJ-Tg(MMTV-PyVT)634Mul/J. This result supports the existence of a previously mapped suggestive locus near D9Mit207 (33 cM) and is designated Mmtp3 (modifier of mammary tumor progression 3). The FVB/NJ-Chr 9^NZB/BlNJ consomic line shows stronger association with the number and size of metastatic pulmonary tumors compared to the FVB/NJ-Chr 9^I/LnJ consomic line.
  
  The chromosome 17 consomic line FVB/NJ-Chr 17^NZB/BlNJ exhibits a 44% decrease in mammary tumor burden compared to control strain FVB/N-Tg(MMTV-PyVT)634Mul/J. This locus may be the same as a previously identified tumor growth modifier near D17Mit81 (16.4 cM) and is designated Mmtp2 (modifier of mammary tumor progression 2). Mmtp2 is also associated with decreased number and size of metastatic pulmonary tumors.
  
  The chromosome 19 consomic line FVB/NJ-Chr 19^NZB/BlNJ exhibits a26%decrease in mammary tumor burden compared to control strain FVB/N-Tg(MMTV-PyVT)634Mul/J. The number and size of pulmonary metastases is also reduced in consomic animals and confirms the presence of a previously identified QTL named Mtes1 (metastasis efficiency suppressor gene 1) at 4 cM.