Epigenetic changes reshape Dicer enzyme function in cancer and reproduction

Activation of a specific part of the Dicer enzyme can change its shape in a way that affects its critical role in proper cell division, with implications for both cancer biology and fertility, according to researchers at The University of Texas MD Anderson Cancer Center.

The study, published in Nature Communications and led by Swathi Arur, Ph.D., professor of Genetics, fills a major gap in understanding how the Dicer enzyme is regulated. The results open new avenues for studying how small epigenetic changes – which turn genes on or off without altering their sequence – and other disruptions in these pathways can affect Dicer's role in a way that can contribute to both cancer progression and infertility.

"These findings expand the implications of Dicer regulation beyond germline biology by suggesting that epigenetic modifications can tune its shape and the proteins it recruits, creating a potential mechanism for disease," Arur said. "In cancer, where DICER1 dysfunction is already linked to altered cell identity and tumor progression, this raises the possibility that irregular epigenetic activity could reshape these networks in ways that promote cancer." 

What is Dicer and how does it relate to fertility and cancer?

Dicer is an enzyme required for proper cell division and for female germ cells to mature into ovum that can reproduce. Additionally, low levels of Dicer are associated with poor overall survival across multiple cancer types, suggesting it may play a tumor-suppressive role. Germ-line mutations in DICER1, the gene responsible for Dicer, also lead to various hereditary cancer syndromes.

However, little is known about how Dicer activity is controlled. Therefore, the researchers examined the role of Dicer in vivo during egg development in C. elegans models.

What did the researchers find out about Dicer in the models?

In C. elegans, Dicer is known to work with partner proteins to produce a type of small RNA required for egg development and reproduction.

The researchers found that a specific region of Dicer must be activated to achieve this. They identified the short DNA sequence GRARR, which is rich in arginine, as a key control site necessary for Dicer to function properly.

When this region is activated, Dicer recruits partner proteins and generates small RNAs for development. When the sequence is mutated or altered, which happens in cancer, Dicer function is affected, showing that Dicer regulation is a coordinated effort across the different parts that together control cell division and fertility.

What is the key takeaway?

Understanding how Dicer is regulated and involved in processes that affect cell division and reproduction helps researchers understand how DICER1 mutations and Dicer dysfunction contribute to infertility and cancer biology, highlighting potential targets to improve outcomes for patients.