In USA, at least 4% of full term boys are cryptorchid. This is one component of a testicular dysgenesis syndrome (TDS). TDS originates during fetal development, but frequently is first detected years later as testicular cancer, defective spermatogenesis, and cysts/adenomas of the excurrent ducts. Testicular cancer, the most common potentially malignant tumor in young men, is 3-11X more likely in those born cryptorchid. Our long-term goal is to delineate molecular mechanisms underlying cryptorchidism and transformation of testicular cells into precancerous cells. Cryptorchidism can be inherited, but in humans no individual gene alteration is associated with >5% of cases. There is increasing acceptance that endocrine disrupter agents (EDAs) frequently are causative for cryptorchidism and predispose for testicular cancer. Understanding how EDAs act epigenetically to block expressions of genes for testicular descent has been hampered by low prevalence of non-experimental cryptorchidism. This project overcomes that obstacle. We propose study of a population of Sitka Black-Tailed Deer (SBTD) on the Aliulik Peninsula of Kodiak Island, AK, documented to have 76% cryptorchidism (91% bilateral, BCO). This population is not genetically different from unaffected populations in other locales. We hypothesize that: (1) this extraordinarily high incidence of cryptorchidism in SBTD is due to in utero exposure of fetuses to an estrogenic EDA which alters expression of genes crucial in testicular programming and descent; and (2) TDS syndrome in SBTD will mimic that in humans, making results translatable to humans.
Specific Aims are:
Aim 1. Genes and Gene Expression in SBTD. Study gene expression and protein accumulation in samples of testes and gubernacular remnants from BCO and non- cryptorchid (NCO) adults. Initial focus on genes for InsIS and LGR8/Great; then AR plus ERa. Compare sequences of genes dysregulated in BCO deer with those in NCO deer to detect genetic mutations. Microsatellite DNA analyses will characterize each animal's genetic background.
Aim 2. Estrogenic molecules in SBTD and potential EDA vectors. Direct chemical analysis might detect and quantify culprit estrogenic EDA, if any, affecting gene expression. Assay with MCF-7 cells should detect action of estrogenic EDA and, hence, allow characterization of epigenetic dysregulation of InsIS, Great, AR, and/or ER genes after exposure to EDA. Results will clarify the interaction of genetics and EDAs as cause of cryptorchidism. ? ? ?
| Veeramachaneni, D N Rao (2012) Ultrastructural evaluation of semen to assess effects of exposure to toxicants. Toxicol Pathol 40:382-90 |
| Veeramachaneni, D N Rao (2008) Impact of environmental pollutants on the male: effects on germ cell differentiation. Anim Reprod Sci 105:144-57 |
| Amann, R P; Veeramachaneni, D N R (2007) Cryptorchidism in common eutherian mammals. Reproduction 133:541-61 |
