Epithelial-mesenchymal transition during the growth and involution of the prostate gland in wild ground squirrels (Spermophilus dauricus)

The prostate glands of wild ground squirrels display enlarged volume during the breeding season and shrunk size during the nonbreeding season, which enables the wild ground squirrel to be an ideal animal model for studying the mechanisms of prostate growth and involution. To clarify the possible mechanism underlying seasonal morphological changes of the prostate in wild ground squirrels, epithelial-mesenchymal transitions (EMT) were focused, and the expression of EMT-related genes was investigated in the current study. Histological results showed that the epithelial lumen enlarged in the breeding season, and the stromal cells expanded during the non-breeding season. Transcriptomic analysis showed 132 EMT-related genes expressed differentially in the prostate during breeding versus non-breeding seasons, indicating EMT might occur during the morphological changes of the prostate. To further confirm the EMT process, the immunolocalizations of EMT markers were inspected, which showed the positive staining of E-cadherin, Claudin-1, ZO1, β-catenin, N-cadherin, VIMENTIN, SLUG, and ZEB1 were presented in epithelial and/or stromal cells. The expressions of Cdh1, Cldn, Tjp1, Ctnnb1, and Snai2 increased in the prostate of the breeding season, while the expressions of Cdh2, Vim, and Zeb1 reduced in the prostate of the breeding season. Moreover, the expression levels of the epithelial marker Cdh1 and the mesenchymal markers Cdh2 and Vim were found to be positively or negatively correlated with prostate weight, respectively. In conclusion, the current results suggested that the EMT might be responsible for prostate growth and involution in the wild ground squirrel.