RNA Editing and Cancer Formation
The discovery of a new mechanism of liver cancer
Introduction 🧬
What’s this article about?
- Recent scientific breakthrough: a mechanism of liver cancer formation involving RNA editing
- How this breakthrough relates to molecular genetics: involves protein synthesis’ transcription phase, control mechanisms and mutations
- Future research implications: mitigating the development of cancerous hepatocytes by bolstering natural RNA editing
But first, some background…
What is cancer?
Cancer occurs when cells uncontrollably divide. Some cancers form solid masses of tissues called tumours.
What is RNA editing?
During transcription, the RNA polymerase complex synthesizes a strand of pre-mRNA that is complementary to a template strand of DNA. In eukaryotes, pre-mRNA is transformed into mature mRNA through modifications, including the removal of introns carried out by spliceosome complexes.
Scientific Breakthrough 💡
Researchers studied whether the pre-mRNA encoding a protein known as coatomer subunit ɑ (COPA) was edited in cancerous liver tissues. They found that cells contained both edited and unedited versions of COPA. If unedited COPA (COPA WT) was predominant, the cell was more likely to become cancerous. If edited COPA (COPA I164V) was predominant, the cell could suppress a certain molecular signalling pathway which can trigger excessive cell division leading to cancer.
RNA editing is a post-transcriptional control mechanism in eukaryotes. During the editing process, ADAR2 (an RNA editing enzyme) binds to COPA’s pre-mRNA between exon 6 and intron 6. ADAR2’s enzymatic activity results in a missense mutation as valine replaces isoleucine as the 164th amino acid in the polypeptide chain created during translation. Isoleucine’s mRNA codons (AUU, AUC and AUA) and valine’s mRNA codons (GUU, GUC and GUA) are very similar.
Implications of Scientific Breakthrough 💭
Liver cancer rates have more than tripled since 1980. Researchers are working to strengthen natural RNA editing mechanisms to make edited COPA predominant in hepatocytes and thus prevent the development of liver cancer. Researchers also hope to extend their findings to “cancer-suppressing processes mediated by RNA editing in the cell” for other cell types.
