A clonal derivative of mammary epithelial cell line COMMA-D retains stem cell characteristics of unique morphological and functional heterogeneity.
The COMMA-D cell line derived from mammary epithelial cells of midpregnant mice was shown previously to be heterogeneous as determined by phase-contrast microscopy, immunocytochemical staining, DNA content, and oncogenic potential (K.D. Danielson et al. (1984) Proc. Natl. Acad. Sci. USA 81, 3756; D. Medina et al. (1986) J. Natl. Cancer Inst. 76, 1143). Clonal subpopulations of COMMA-D cells have now been isolated by both transfection and selection using a dominant-selectable gene transfer vector and by limiting dilution. Despite their clonal origin, these subpopulations in many cases retained the heterogeneity of the parental COMMA-D line. Of 18 clonal lines assayed, only 5 were able to express beta-casein mRNA. Pooled populations of G418-resistant cells expressed substantially higher levels of beta-casein mRNA than the clonal lines. One of the expressing clonal lines, BNW-7, was characterized further, using immunocytochemical techniques. Approximately 10% of BNW-7 cells expressed casein under the appropriate hormonal and cell-substratum conditions by indirect immunofluorescent staining. Casein immunoperoxidase staining of BNW-7 cells on floating collagen gels revealed that casein-producing cells were localized in small alveolar structures, which were formed in a non-hormone-dependent fashion. The cells in these alveolar structures were cuboidal with basally located nuclei, expressed keratin intermediate filament proteins preferentially, and comprised approximately 18% of the total cells. Cells elsewhere on the surface of the gel displayed a flattened morphology, and expressed vimentin intermediate filament proteins preferentially. A proportion of COMMA-D cells, therefore, appeared to have some of the characteristics of mammary stem cells, and retained the ability to differentiate and form phenotypically heterogeneous cell populations in vitro.
Campbell
S M
SM
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.
Taha
M M
MM
Medina
D
D
Rosen
J M
JM
D000818:Animals; D002364:Caseins / Q000235:genetics; D002460:Cell Line; D002999:Clone Cells; D004247:DNA / Q000235:genetics; D004587:Electrophoresis, Agar Gel; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D005260:Female; D005455:Fluorescent Antibody Technique; D006651:Histocytochemistry; D007124:Immunoenzyme Techniques; D007633:Keratins / Q000096:biosynthesis; D008321:Mammary Glands, Animal / Q000166:cytology* / Q000502:physiology; D051379:Mice; D009693:Nucleic Acid Hybridization; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology; D014162:Transfection; D014746:Vimentin / Q000096:biosynthesis
D002364:Caseins; D012333:RNA, Messenger; D014746:Vimentin; D007633:Keratins; D004247:DNA