Surprisingly, these microRNAs promoted, rather than inhibited, the expression of proteins

MicroRNAs play a role in cancer development and are thought to only inhibit protein expression
in dividing cells, such as tumor cells.
But a new study published in the journal ACS Central Science suggests that in human cell division and cancer cells, some of these tiny molecules can boost the expression of a specific gene, challenging conventional wisdom
.

Only a small fraction of nucleotides, microRNAs, or miRNAs for short, do not code for proteins
.
Instead, they largely reduce or inhibit protein production
by silencing the expression of certain genes.
One class of cellular mechanisms regulated by miRNAs are enzymes involved in mediating glycosylation, which is the addition of carbohydrates to certain proteins
.
In cancer cells, however, the process can be highly dysporealized, suggesting that miRNAs may be doing something unusual
.
So Lara Mahal and his colleagues set out to investigate how miRNAs work in the glycosylation process, and whether these molecules might work in
a new way.

Previously, researchers developed a fluorescence assay that analyzes how miRNAs interact with their targets and whether they increase or decrease the amount
of protein produced.
They used this method to study the regulation of the cancer-associated glycosylases ST6GAL1 and ST6GAL2 and found that for the former, miRNAs appeared to directly upregulate this process
in non-cancer human cells.
This challenges the current perception
that miRNAs only downregulate protein production.
They also detected miRNA-mediated upregulation in multiple cancer cell lines and observed the same results
.
The researchers say the work expands understanding of how miRNAs work, an important consideration for the use of miRNA-based therapies in current and future clinical trials
.