Overexpression of IGF-1 During Early Development Expands the Number of Mammary Stem Cells and Primes them for Transformation. Academic Article uri icon


  • Insulin-like growth factor I (IGF-1) has been implicated in breast cancer due to its mitogenic and anti-apoptotic effects. Despite substantial research on the role of IGF-1 in tumor progression, the relationship of IGF-1 to tissue stem cells, particularly in mammary tissue, and the resulting tumor susceptibility has not been elucidated. Previous studies with the BK5.IGF-1 transgenic (Tg) mouse model reveals that IGF-1 does not act as a classical, post-carcinogen tumor promoter in the mammary gland. Pre-pubertal Tg mammary glands display increased numbers and enlarged sizes of terminal end buds, a niche for mammary stem cells (MaSCs). Here we show that MaSCs from both wild-type (WT) and Tg mice expressed IGF-1R and that overexpression of Tg IGF-1 increased numbers of MaSCs by undergoing symmetric division, resulting in an expansion of the MaSC and luminal progenitor (LP) compartments in pre-pubertal female mice. This expansion was maintained post-pubertally and validated by mammosphere assays in vitro and transplantation assays in vivo. The addition of recombinant IGF-1 promoted, and IGF-1R downstream inhibitors decreased mammosphere formation. Single-cell transcriptomic profiles generated from 2 related platforms reveal that IGF-1 stimulated quiescent MaSCs to enter the cell cycle and increased their expression of genes involved in proliferation, plasticity, tumorigenesis, invasion, and metastasis. This study identifies a novel, pro-tumorigenic mechanism, where IGF-1 increases the number of transformation-susceptible carcinogen targets during the early stages of mammary tissue development, and "primes" their gene expression profiles for transformation.

published proceedings

  • Stem Cells

altmetric score

  • 1.25

author list (cited authors)

  • Luo, L., Santos, A., Konganti, K., Hillhouse, A., Lambertz, I. U., Zheng, Y., ... Fuchs-Young, R. S.

citation count

  • 4

complete list of authors

  • Luo, Linjie||Santos, Andres||Konganti, Kranti||Hillhouse, Andrew||Lambertz, Isabel U||Zheng, Yuanning||Gunaratna, Ramesh T||Threadgill, David W||Fuchs-Young, Robin S

publication date

  • March 2022