Background: MicroRNA-125a is present in all animals with bilateral symmetry and displays
a conserved nucleotide sequence with a section of 11 bases including the seed region that is
identical in all considered species. It primarily downregulates the expression of LIN28, thereby promoting
cell differentiation and larval phase transitions in nematodes, mammals and insects.
Objective: In this review, we focus on the cellular control of miR-125a expression and its antiproliferative
Results: In mammalians, microRNA-125a is present in most adult organs and tissues in which it targets
proteins involved in the mitogenic response, such as membrane receptors, intracellular signal
transducers, or transcription factors, with the overall effect of inhibiting cell proliferation. Tissue levels
of miR-125a generally raise during differentiation but it is often downregulated in cancers, e.g.
colon, cervical, gastric, ovarian, lung, and breast cancers, osteosarcoma, neuroblastoma, glioblastoma,
medulloblastoma, retinoblastoma and hepatocellular carcinoma.
Conclusion: The antiproliferative activity of miR-125a, demonstrated in many cell types, together
with the notion that this miRNA is downregulated in several kinds of cancers, give a substantial support
to the concept that miR-125a plays an oncosuppressive role.