The Role of MicroRNA in Ovarian Cancer

Ovarian cancer is often diagnosed at a later stage. This means it is harder to treat and carries a worse prognosis. Knowing more about the ways in which ovarian cancer starts can help guide research into better detection and treatment. One area of research focuses on microRNA and its role in ovarian cancer. This knowledge could offer a major breakthrough in understanding this disease.

What is microRNA?

MicroRNA is the name of a molecule family that helps cells control the types and amounts of proteins they make. At its most basic, microRNA is involved in turning genes on and off. The process of genes turning on and making proteins is called gene expression.^1,2

MicroRNA is found in many cell types. It also circulates throughout the body and can be found in bodily fluids, including blood. It may be a biomarker in a number of diseases.^1,2

How is microRNA linked to ovarian cancer?

Originally, doctors thought ovarian cancer started from changes in cells on the surface of the ovaries. Now, research suggests that it may actually start in the surface tissue of the fallopian tubes, kickstarted by a certain type of microRNA.³

Most high-grade serous ovarian cancers (HGSOC) start in the fallopian tube because of changes in the epithelial (surface) cells. HGSOC is the deadliest type of ovarian cancer. An important study found that MiR-181a, a type of microRNA, seems to be a strong reason these fallopian tube cells become cancer.^3,4

Cells with high levels of miR-181a were found to be a possible biomarker for early-stage high-grade serous ovarian cancer (HGSOC). Cells with high amounts of miR-181a were also found to turn into ovarian cancer by turning off 2 other important genes.^2,4

When genes in a cell are unstable, that cell is more likely to become cancerous. MicroRNA miR-181a transforms fallopian tube cells by turning off RB1 and stimulator-of-interferon-genes (STING). This encourages cells with high instability to multiply.³

In another study, higher levels of miR-181a were linked to faster recurrence and worse outcomes in ovarian cancer. The same study showed that while microRNA changed fallopian tube cells into cancer cells, it also suppressed the immune system. This is why the immune response did not detect the cancer cells and try to get rid of them.⁴

How can microRNA help detect and treat ovarian cancer?

MicroRNAs are generally stable in serum and plasma, which are parts of blood. This means that if a microRNA is found to be linked with the earliest stages of ovarian cancer – like miR-181a seems to be – it might help doctors find early ovarian cancer sooner. More research on microRNAs and the blood of those with early-stage ovarian cancer is needed, but these early results are promising.^3,4

A better understanding of microRNA and its role in ovarian cancer could also help improve treatment. Plus, miR-181a helps regulate a protein called STING. STING is important in immunity. For the immune system to control cancer cells, the tumors need to be seen by the immune system. If these tumors were more visible to the immune system, targeting this interaction might make cancer cells more responsive to treatment.^3,4

MiR-181a has also been linked to worse outcomes in other cancers, including breast, prostate, and lung cancers. More research needs to be done to fulfill the early promise of these studies.