Because the relationship between epithelial cells and the microenvironment is complex, the success of these strategies will undoubtedly be dependent on stage of epithelial cell transformation.
However, other factors were also thought to be involved in senescence of human epithelial cells because several kinds of epithelial cells were unable to be immortalised by telomerase activation alone (Kiyono et al, 1998; Kyo et al, 2003).
Initial attempts at primary culture of breast tumours met with limited success because of overgrowth of epithelial cells with stromal fibroblasts, aptly described as 'weeds in the tissue culturist's garden' [ 24].
The redistribution of meprinβ to the basolateral membrane of MDCK cells upon Ca2+-switch-induced depolarization is of interest, because the polarization status of epithelial cells is perturbed in diverse pathological conditions, including ischaemic disease, inflammation and cancer.
This difference, apparently explains why oncolytic virotherapy works well in xenograft models but very poorly in patients because the tight junctions of epithelial cells shield the adenovirus receptor.
This difficulty is mainly because of the rarity of epithelial cells in endometriotic tissues as well as to their shorter life span due to two barriers against their in vitro growth.
9 BPH seems to be closely related with prostate cancer, because both diseases involve overgrowth of epithelial cells.
In this context, the study of Sca-1-enriched cells [ 19] may not be comparable with that of SP cells, because SP cells comprise 0.2 0.45% of epithelial cells while Sca-1 cells are 100 times more common, comprising 20% of the total mammary epithelial population.
The extent of dense tissue might also simply raise cancer risk because such tissue has more epithelial cells and thus a higher risk of transformation, and because there is more communication of epithelial cells with connective tissue, which produces hormones and growth factors (Polyak and Kalluri, 2010).
We assume that the cell density in epithelial layer stays near a standard value because the detailed mechanism of the proliferation of epithelial cells is still unknown.
