Cancer is the second leading cause of death worldwide (after cardiovascular diseases) with approximately 9.6 million deaths in 2018, about 70 % of which occurred in low- and middle-income countries including Pakistan. It has been reported by the World Health Organization (WHO) that tobacco use contributes to about 22% of cancer-related deaths. Further studies have reported the correlation of the use of cell phone for a minimum of 3 hours per day with chances of having brain cancer.
Several treatments have been discovered to cure cancer but due to the potential of cancer cells to resist chemotherapy in addition to the side effects chemotherapy has on a person, research is still being conducted.
The reason to learn about cancer metabolism is due to the reprogramming of metabolic pathways within a cancer cell as it adapts to changes in the environment for its survival. If the metabolism of cancer cells (which is being studied while this article was written) is understood, maybe we can find new ways to tackle the disease.
There are three ways to describe cancer metabolism:
Cancer consists of cancerous cells that divide faster and thus, require anabolic processes for the growth of their biomass. Lipids or fats are required for cell membrane structure, proteins for cellular structure, cytoskeleton, and enzymatic activities and also, nucleic acids, like DNA, to store genetic information of a cell. To fulfill the need for cancerous cells to divide faster, processes are required to construct these biopolymers quickly. The precursors to construct such giants are supplied by intermediate products of cellular respiration process that occurs in the mitochondria (powerhouse), plus the glycolysis process. That’s correct, the process which provides us with energy!
In order to build up large molecules, cancerous cells need energy by breaking down large molecules, mainly glucose and glutamine. Glucose is absorbed upon response by the cancer cell, which produces transporters and enzymes, to extract energy from glucose. Glutamine (essential amino acid) is also absorbed by cancer cells and used to generate energy.
Oxidation and Reduction
Each cancer cell inside the tumor may face stress due to lack of nutrients or oxygen as they keep on growing. This may cause difficulty in sustaining cells within a tumor and thereby, free radicals could accumulate and damage DNA. Cancer cells have developed a strategy to cope with it by producing proteins that neutralize those free radicals.
Cells within a tumor do not just require mutations for cancer to progress. There is another method of change in the genetic product without having mutations and this is known as ‘Epigenetics’. Cancer cells contain mutant enzymes which modify certain metabolites. This results in changes in gene expression, due to the modified metabolite acting on enzyme controlling epigenetic machinery.
In short, the inclusion of metabolic profiling of cancer cells will not just be able to diagnose a patient with cancer but could also aid in the determination of the severity of the disease and ways of curing it. Each metabolic pathway is examined to deduce a treatment, without harming normal cells because most pathways are similar to normal cells.