Context: Researchers at the Indian Institute of Technology Madras have identified a specific microRNA (miRNAs) called ‘miR-155’ that is over-expressed in tongue cancer. 

Findings of Research:

  • The research team has shown that knocking out miR-155 causes - 
    • death of cancer cells 
    • arrests the cell cycle  
    • regresses tumour size in animal models 
    • reduces cell viability and colony formation in bench top assays.


The finding could help develop molecular strategies to manipulate miR-155 expression to develop therapeutics for tongue cancer.


  • Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. 
  • RNA and DNA are nucleic acids, and, along with lipids, proteins and carbohydrates, constitute the four major macromolecules essential for all known forms of life.


  • MicroRNAs (miRNAs) are short non‐coding RNAs containing 20–24 nucleotides that participate in virtually all biological pathways in animals.
  • They have been found to play important roles in many cancers, in carcinogenesis (start of cancer), malignant transformation and metastasis — the development of secondary cancer. 
  • The miRNAs associated with cancer are called ‘Oncomirs’.” 
    • Many of the Oncomirs affect cancer by suppressing the performance of tumour-suppressing agents. 
    • Some of them can prevent the growth and spread of cancer cells and yet others prevent tumour growth itself
    • miRNA manipulation is being combined with conventional cancer treatment methods such as chemotherapy, radiotherapy and immunotherapy.
    • The miRNAs affect cancer growth through inhibiting or enhancing the functions of certain proteins.

Macro molecules: 

Macromolecules are very large molecules that are formed by the polymerization of smaller molecules called monomers. They are typically composed of thousands of atoms or more.

Biological macromolecules are large molecules, necessary for life, that are built from smaller organic molecules. 

There are four major classes of biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids); each is an important cell component and performs a wide array of functions. Combined, these molecules make up the majority of a cell’s dry mass (recall that water makes up the majority of its complete mass).

Carbohydrates are an essential part of our diet; grains, fruits, and vegetables are all natural sources of carbohydrates. Carbohydrates provide energy to the body, particularly through glucose, a simple sugar that is a component of starch and an ingredient in many staple foods.

Lipids include a diverse group of compounds that are largely nonpolar in nature. This is because they are hydrocarbons that include mostly nonpolar carbon–carbon or carbon–hydrogen bonds. Non-polar molecules are hydrophobic (“water fearing”), or insoluble in water. Lipids perform many different functions in a cell. Cells store energy for long-term use in the form of fats. Lipids also provide insulation from the environment for plants and animals.

Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. 

Proteins may be structural, regulatory, contractile, or protective; they may serve in transport, storage, or membranes; or they may be toxins or enzymes. Each cell in a living system may contain thousands of proteins, each with a unique function. Their structures, like their functions, vary greatly.

Nucleic acids (DNA and RNA) are the most important macromolecules for the continuity of life. They carry the genetic blueprint of a cell and carry instructions for the functioning of the cell.



Image Source: The Hindu