Characterization of an In Vitro Human Breast Epithelial Organoid System
Annual rept. 1 Aug 97-31 Jul 98
MICHIGAN STATE UNIV EAST LANSING
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We have characterized organoids formed by two types of normal human breast epithelial cells HBEC on Matrigel. The results show that mammary gland-like structures can be formed in one day after inoculation of right number and ratio of Type I and Type II HBEC. These organoids later may form ductal and actively proliferating terminal end bud-like structures. The two cell types that formed organoids in Matrigel for months can be recovered as actively growing monolayer culture, on plastic, which then can be used to form organoids again. Thus, a monolayer-organoid-monolayer-organoid cycle is able to preserve HBEC for a long time, reaffirming stem cell nature of Type I HBEC. Our study also reveals that a low level of telomerase activity was present in both Type I and Type II HBEC and their SV40 transformed clones at early passages. However, this innate telomerase activity appears not sufficient for immortalization and can be easily activated in transformed Type I cells at late passages which became immortal at high frequency 1011. In contrast, Type II transformed clones with extended lifespan seem to lack the ability of telomerase activation and rarely became immortal 110. These results provide a basis for high susceptibility of Type I cells to neoplastic transformation.
- Anatomy and Physiology
- Medicine and Medical Research