Immortalized mouse mammary cells in vivo do not exhibit increased telomerase activity |
| |
Authors: | Jiang C; Juo L; Said TK; Thompson H; Medina D |
| |
Institution: | AMC Cancer Research Center, Denver, CO 80214, USA. |
| |
Abstract: | The acquisition of immortalization is an early and carefully documented
event in mouse mammary tumorigenesis. Activation of telomerase activity is
one hypothesis to explain the acquisition of immortalization. We examined
the activity of telomerase in well-defined immortalized, non- tumor cell
populations of mouse mammary tissue in vivo. The results indicated that
normal virgin and mid-pregnant mammary gland had low to moderate levels of
telomerase activity, respectively. In comparison with the levels detected
in pregnant mammary gland, telomerase activity was elevated in mammary
tumors in situ and in established mammary cell lines in vitro, both
tumorigenic and nontumorigenic; however, hyperplastic alveolar
preneoplastic mammary outgrowths and non- tumorigenic ductal outgrowths,
both in vivo immortalized populations, had telomerase activity <12% of
the levels detected in normal pregnant mammary gland. These results suggest
that elevated telomerase activity is not necessary for the immortalization
phenotype in in vivo mouse mammary cell populations and that elevated
telomerase activity occurs as a late event in mammary tumorigenesis.
Furthermore, the data suggest that low levels of telomerase activity are
characteristic for mouse mammary epithelial cells and not sufficient for
immortalization. These data suggest that other factors play more important
roles in the induction and/or maintenance of the immortalization state in
mammary cell populations.
|
| |
Keywords: | |
本文献已被 Oxford 等数据库收录! |
|