SP cell populations with stem phenotypes have higher tumorigenic potentials.

<p>Various cell populations with stem phenotypes were transplanted orthotopically at different dilutions (24000, 10000, 6000, 3000, 1000, 500, 200, 50, or 25 cells/fat pad) with 1∶1 Matrigel™ into mouse mammary fat pads. Tumor volumes were calculated every alternate day for 6 weeks. When tumor growth was below 10 mm³, mice were necropsied following guideline and tumors were excised and analyzed. (<b>A</b>) Results indicated that fewer SP cells were needed to form tumors than ALDH1⁺cells, suggesting heterogeneities in tumorigenicity. A characteristic that might be related to these heterogeneities was levels of cytokines/chemokines produced by the differing cell populations. (<b>B</b>) ALDH1⁺ and ALDH1⁻ did not show consistent differences in tumor formation. (<b>C</b>) Volumes of tumors formed from 6000 cells of SP, non-SP, ALDH1⁺ and ALDH1⁻ cell populations showed that SP grew faster than non-SP, ALDH1⁺ and ALDH1⁻ cells.