DanStem > Staff
Ole William Petersen
Morphogenesis and Differentiation Program
Section VI. Building 18.4
Panum, Building: 18.4.14
2200 København N
My research has been focused primarily on the understanding of the morphogenesis and differentiation of normal and neoplastic human breast tissue.
A major advance of investigating human tissue were the sampling of tissue from patients and the development of culture based model systems. The strategy has been to characterize primary cultures at the individual cell level by means of various forms of cytochemistry and imaging and compare the cellular phenotypes with sections of the tissue of origin with a view to tracking the cells outside the tissue, but putting them in the right context. In the lab we have characterized cancer cells, peritumoral cells and normal epithelial and stromal cells. To obtain a detailed view of individual cultured cells from the samples, it was initially necessary to characterize them in monolayer cultures. Also, to be able in the long run to dissect the requirements for growth and differentiation of the cells at the molecular level, early on we took advantage of the rapidly emerging field of serum-free culture technology to devise hormone- and extracellular matrix-defined culture conditions in favour of traditional serum-containing and conditioned media compositions and feederlayers. A major conclusion from these early investigations was that normal epithelial structures generally give rise to two-cell islets composed of a central zone epithelial cells and peripheral zone of myoepithelial cells while tumor cell islets are composed of only epithelial cells which frequently stained with NADPH-diaphorase. Also, we could reproducibly expand normal breast epithelium and a subset of breast cancers which paved the way for the first cell lines established under serum-free conditions from both non-malignant and malignant breast tissue (HMT-3522 and HMT3909). These technological achievements allowed us to ask questions about the growth factor control of myoepithelial differentiation, the lineage affiliation of estrogen receptor positive breast epithelial cells and differences in polarization of sialomucin between normal breast epithelial cells and cancer cells. In addition, a milestone experiment was the long-term EGF-deprivation from the HMT-3522 (S1) cells carried out by Dr. Per Briand at the Danish Cancer Society which resulted first in the formation of the growth autonomous S2 subline and eventually in the spontaneously tumorigenic T4.2 cells which in turn offered a unique opportunity to study normal and abnormal morphogenesis on an identical genetic background.
Creating the Correct Context:
Having a firm grip of the cellular phenotypes and their culture requirements, our ambition then was to interrogate the complexity of the normal breast and breast cancer to an extend which would allow the recapitulation in culture of their typical histological appearance. Fundamentally, this could be achieved only in three dimensions with the use of gelled extracellular matrices. In collaboration with Dr. Mina J. Bissell, at Lawrence Berkeley National Laboratory we discovered that normal breast epithelial cells from primary cultures and non-malignant cell lines all had the inherent information to recapitulate acinus-like structures if embedded in a constituted basement membrane (EHS gel). Equally importantly, breast cancer cells and cancer cell lines failed to sense the microenvironment to organize similar structures (Petersen et al. PNAS, 1992). Since then we have been able to dissect the criteria and signalling for correct acinus morphogenesis, and the role of integrins, in particular beta 1 and beta 4 integrin in reversion of tumor cell-like to normal cell-like morphogenesis (Weaver, Petersen et al. JCB 1997). Together with Lone Rønnov-Jessen at the August Krogh Institute we discovered TGF-beta singnalling as the mechanism of myofibroblast generation in breast cancer from resident unactivated fibroblasts and the function of myofibroblastic cells as scaffold for breast tumor formation and morphogenesis (Rønnov-Jessen and Petesen, Lab Invest, 1993, Rønnov-Jessen, Petersen et al., JCI, 1995). Recently, we have determined the importance of myoepithelial cells in formation of correct polarity in the breast, and further that the myoepithelial cells isolated from breast tumors are deficient in this function. We showed that this defect was due to an inability to make laminin 1 (Gudjonsson et al. JCS, 2002). In a paper in Genes and Development we identified a candidate progenitor cell for terminal duct lobular unit morphogenesis and differentiation (Gudjonsson et al. G&D, 2002). Finally, we have identified one of the few genes induced in tumor cells as a consequence of reciprocal interaction in three-dimension with fibroblasts (Nielsen et al. Genomics 2002).
Major sourches of funding:
The Danish Cancer Society (grant #00 252 110 9210)
The Danish Medical Research Council (grant #22-02-0197)
The Novo Nordisk Foundation
The John and Birthe Meyer Foundation
EU 5Th Frammework (grant #HPRN-CT-2002-00246)
NIH (grant # CA064786