Investigation of three new mouse mammary tumor cell lines as models for transforming growth factor (TGF)-beta and Neu pathway signaling studies: identification of a novel model for TGF-beta-induced epithelial-to-mesenchymal transition.
BACKGROUND
This report describes the isolation and characterization of three new murine mammary epithelial cell lines derived from mammary tumors from MMTV (mouse mammary tumor virus)/activated Neu + TbetaRII-AS (transforming growth factor [TGF]-beta type II receptor antisense RNA) bigenic mice (BRI-JM01 and BRI-JM05 cell lines) and MMTV/activated Neu transgenic mice (BRI-JM04 cell line).


METHODS
The BRI-JM01, BRI-JM04, and BRI-JM05 cell lines were analyzed for transgene expression, their general growth characteristics, and their sensitivities to several growth factors from the epidermal growth factor (EGF) and TGF-beta families (recombinant human EGF, heregulin-beta1 and TGF-beta1). The BRI-JM01 cells were observed to undergo a striking morphologic change in response to TGF-beta1, and they were therefore further investigated for their ability to undergo a TGF-beta-induced epithelial-to-mesenchymal transition (EMT) using motility assays and immunofluorescence microscopy.


RESULTS
We found that two of the three cell lines (BRI-JM04 and BRI-JM05) express the Neu transgene, whereas, unexpectedly, both of the cell lines that were established from MMTV/activated Neu + TbetaRII-AS bigenic tumors (BRI-JM01 and BRI-JM05) do not express the TbetaRII-AS transgene. The cuboidal BRI-JM01 cells exhibit a short doubling time and are able to form confluent monolayers. The BRI-JM04 and BRI-JM05 cell lines are morphologically much less uniform, grow at a much slower rate, and do not form confluent monolayers. Only the BRI-JM05 cells can form colonies in soft agar. In contrast, all three cell lines form colonies in Matrigel, although the BRI-JM04 and BRI-JM05 cell lines do so more efficiently than the BRI-JM01 cell line. All three cell lines express the cell surface marker E-cadherin, confirming their epithelial character. Proliferation assays showed that the three cell lines respond differently to recombinant human EGF and heregulin-beta1, and that all are growth inhibited by TGF-beta1, but that only the BRI-JM01 cell line undergoes an EMT and exhibits increased motility upon TGF-beta1 treatment.


CONCLUSIONS
We suggest that the BRI-JM04 and BRI-JM05 cell lines can be used to investigate Neu oncogene driven mammary tumorigenesis, whereas the BRI-JM01 cell line will be useful for studying TGF-beta1-induced EMT.
Receptor, Signaling and Proteomics Group, National Research Council, Biotechnology Research Institute, Montréal, Quebèc, Canada. anne.lenferink@cnrc-nrc.gc.ca
Anne E G
AE
Lenferink
Joanne
J
Magoon
Christiane
C
Cantin
Maureen D
MD
O'Connor-McCourt
D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D004847:Epithelial Cells; D015674:Mammary Neoplasms, Animal / Q000235:genetics; D008565:Membrane Proteins; D008648:Mesoderm; D051379:Mice / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D011991:Receptors, Virus; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes
D008565:Membrane Proteins; D017346:Protein Serine-Threonine Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta; D011991:Receptors, Virus; D016212:Transforming Growth Factor beta; C111417:Fam89b protein, mouse