Two new previously unrecognized types of breast cells identified--WHY important?

[Lani]

this should remind everyone that there is much more still unknown about normal breasts and breast cancer than is known.

This is not reassuring to many and I try to offer hope---but in many ways it should be hope reaffirming.

Until we recognized these kinds of cells we could not look for them and study them and see if we can target the abnormalities which cause breast cancer so that we might even prevent it.

If you think they are running out of options for you, just remember there are new discoveries daily and some involve already approved drugs or even non-drugs.

These cells have sat there since the dawn of time, but only now were they recognized. If you don't look, you won't find. Let's hope they keep on looking

Nat Cell Biol. 2013 Apr 21. doi: 10.1038/ncb2725. [Epub ahead of print]
Notch2 genetic fate mapping reveals two previously unrecognized mammary epithelial lineages.
Sale S, Lafkas D, Artavanis-Tsakonas S.
Source
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Abstract
Notch signalling is implicated in stem and progenitor cell fate control in numerous organs. Using conditional in vivo genetic labelling we traced the fate of cells expressing the Notch2 receptor paralogue and uncovered the existence of two previously unrecognized mammary epithelial cell lineages that we term S (Small) and L (Large). S cells appear in a bead-on-a-string formation and are embedded between the luminal and basal/myoepithelial layers in a unique reiterative pattern, whereas single or paired L cells appear among ductal and alveolar cells. Long-term lineage tracing and functional studies indicate that S and L cells regulate ipsi- and contralateral spatial placement of tertiary branches and formation of alveolar clusters. Our findings revise present models of mammary epithelial cell hierarchy, reveal a hitherto undescribed mechanism regulating branching morphogenesis and may have important implications for identification of the cell-of-origin of distinct breast cancer subtypes.
PMID: 23604318