miRNA Let-7

• Scientists have identified a single, small strand of microRNA, or miRNA, that plays a critical role in fighting cancer.
• The team at the University of Massachusetts-Amherst in the US found that the microRNA, called let-7, also has the ability to recognise and remember tumour cells like T-cells.
  • This cellular memory is the basis for how vaccines work.

ABOUT MIRNA

• These are short non‐coding Ribonucleic Acids (RNAs) containing 20–24 nucleotides.
• It is a single-stranded small RNA molecule.
• It plays a role in the regulation of gene expression and gene silencing.
• It is present naturally in plants, animals and some viruses.

MECHANISM

• T-cells, which are white blood cells that specialise in fighting both pathogens, think of the common cold, and altered cells of the organism itself, like tumor cells

• When the T-cells recognise foreign antigens in our bodies, they turn into killer T-cells and attack whatever the pathogen may be, from the sniffles to Covid, or even cancer.
  • After the killer T-cells have won their battle, most of them die.
• However a few survive and transform into memory cells and form an elite task force called the ‘memory pool’.
  • They remember what that particular antigen looked like, so that they can be on the lookout for the next time it invades the body.
  • But, cancerous tumour cells work by tricking the killer T-cells, turning them off before they can attack and create a memory pool, leaving the cancer to metastasize unchecked.

ABOUT LET-7

• A tiny piece of miRNA, let-7 is highly expressed in memory cells.
• The more let-7 a cell has, the less chance that it will be tricked by cancerous tumour cells, and the greater chance it has of turning into a memory cell.

Let-7 miRNA has been handed down the evolutionary tree since the dawn of animal life.