Genre: Information/Explanation

Stem cells are notable for being fecund -- they continually generate new cells . So too do cancer cells , however . Indeed , stem cells and cancer cells are beginning to seem very close relations . In one recent study , adult stem cells ( those obtained from mature animals , rather than early embryos ) were found to develop into tumour cell lines when grown in the laboratory . A team from Spain collected stem cells from fat tissue and grew them in culture for eight months . Some developed into cells that generated cancers when injected into animals . In a second study , a Danish team found that permanently activating telomerase in similar stem cells also made them cancerous . Telomerase protects the ends of chromosomes , which usually wear away at every cell division . Telomerase can prolong the lifespan of a cultured cell line , but leaves it vulnerable to uncontrolled proliferation . Studies of certain cells obtained from breast cancers are also disturbing . These cells can seed new breast cancers , and look very much like stem cells . Finally , Carla Bender Kim and colleagues recently identified a ' pocket ' in the adult mouse lung containing stem cells . As well as providing new lung epithelial cells , these cells can be triggered to proliferate by cancer-causing mutations . These and other studies highlight the perils as well as the potential of cellular immortality . They also raise questions about the use of adult stem cells in therapy . Rubio D et al. Spontaneous human adult stem cell transformation . Cancer Res 2005 ; 65 ( 8 ) : 3035--9 . Burns JS et al. Tumorigenic heterogeneity in cancer stem cells evolved from long-term cultures of telomerase-immortalized human mesenchymal stem cells . Cancer Res 2005 ; 65 ( 8 ) : 3126--35 . Ponti D et al. Isolation and in vitro propagation of tumorigenic breast cancer cells with stem / progenitor cell properties . Cancer Res 2005 ; 65 ( 13 ) : 5506--11 . Bender Kim CF et al. Identification of bronchioalveolar stem cells in normal lung and lung cancer . Cell 2005 ; 121 ( 6 ) : 823--35 . Article appears in the following Wellcome Science subjects / article types Cancer | North America | Stem cells and cloning