Question

Directions: Mitochondria are organelles that supply most of the energy that cells require. Recently, scientists have discovered that mitochondria are also important in apoptosis: programmed cell death or cell suicide. If a cell starts growing abnormally, this can trigger the death of the cell. It is a natural defense that we have against cancer. Some cancer cells have special proteins in their mitochondria that prevent this apoptosis and allow the cancer cells to survive.

Submission: Look for more information on this topic, and then write a short article for a newspaper that summarizes this recent research, and points out the potential applications.

Answer 1

The role of mitochondria in the initiation and progression of cancer has become a hot topic of debate among researchers. More or less, it is accepted that mitochondria does have a role in cancer development through their capability of replication [ since they have their own DNA] and energy production by respiration.

Mitochondria are the home of the Kreb's cycle and are aptly called the 'powerhouse' of cells for their role in producing ATP from food. By oxidizing the fat, protein and carbohydrates we consume as food, they creat energy rich molecules, the ATP , for the body. Each mitochondria contains only 37 genes.

Researchers at the United Mitochondrial Disease Foundation have reported that only 3% of genetic material per mitochondria is required to produce upto 90% of the body's ATP. This means that more than 95% of the mitochondrion can play other roles in regulating the metabolic pathway.

In the 1920s, Otto Warburg observed that cancer cells do not produce energy as efficiently as normal cells do. Rather, cancer cells produce most of their energy through an inefficient mechanism which results in fermentation of lactate into lactic acid. Glucose and glutamine metabolites are then diverted from producing ATP to a process that that promotes cell proliferation. Dr. Thomas Seyfried summed these observations as-

1. insufficient respiration initiates tumorigenesis and ultimately cancer

2. energy through glycolysis gradually compensates for insufficient energy through respiration.

3. cancer cells continue to ferment lactate in the presence of oxygen

4. respiratory insufficiency eventually becomes irreversible.

It is believed that respiratory insufficiency is the origin of cancer, and that the other initiation theories, like the Somatic Mutation Theory, arise either directly or indirectly from insufficient respiration

Mitochondria control several vital cellular parameters like regulation of energy production, modulation of redox status within cells, generation of ROS[ reactive oxygen species], contribution to cytosolic biosynthetic precursors like acetyl CoA and pyrimidines and initiation of apoptosis through the activation of the mitochondrial permeability transition pore and Cytochrome C. Changes in any of these parameters can shift the cell from a dormant state of differentiation to a proliferation state.

If the research is proved and a conclusive evidence is obtained as to the role of mitochondria in development of cancer, the approach to cancer treatment might change. The mitochondria may be the gateway to this approach.

Source : Townsend Letter

August/September 2018