Resistance to therapy is the main limitation of current treatment of aggressive cancers such as malignant melanoma. Insurgence of resistance relates to the capability of tumour cells to circumvent the stress induced by the treatment. In order to survive, cancer cells develop a series of adaptation mechanisms through rewiring fundamental processes. Among those, reprogramming of mRNA translation favours the expression of proteins essential for tumour development.
Researchers from the University of Liège have been studying the contribution of wobble tRNA modification in cancer development through regulation of selective mRNA translation for a few years, uncovering their central role in tumour initiation and metastatic potential.
Modification of certain tRNA molecules at the wobble position regulates selective mRNA translation and impact on protein expression. The GIGA-ULiège team discovered that melanoma that carry the BRAF(V600E) mutation – found in more than 50 per cent of the melanoma patients – are addicted to enzymes modifying wobble uridine tRNAs (U34-tRNA).
The research showed that wobble uridine tRNA modification enzymes are upregulated in melanoma clinical samples and very lowly expressed in melanocytes, the normal melanin-producing cells. Inhibition of this family of enzymes led to a very strong and specific cell death in BRAF(V600E) melanoma, but had no effect on melanocytes. This very specific effect led researchers to postulate that these enzymes may play an important role in melanoma development.
Growing melanoma tumours adapt their metabolism and use glucose as a source of energy. The researchers demonstrated that U34-tRNA enzymes are key for the expression of proteins involved in glucose metabolism.
Using melanoma patients derived samples, researchers found that U34-tRNA enzymes are essential to sustain glucose metabolism. Therefore, the inhibition of these enzymes prevents glucose metabolism in melanoma cells, and limits their energy income. As a consequence, the growth and survival of melanoma cells is strongly reduced after inhibition of U34-tRNA enzymes. Acquired resistance to targeted therapy, which strongly limits the clinical benefit of the treatment of malignant melanoma, is prevented by the inhibition of U34-tRNA enzymes. In other words, the inhibition of these enzymes synergises with targeted therapies to block malignant melanoma growth.
This work revealed the clinical potential of U34-tRNA enzymes inhibition for the treatment of human malignant melanoma, a disease that remains extremely difficult to treat. Further research will be necessary to firmly establish the real clinical benefit of this approach and to develop therapeutic tools that could achieve this goal.