INTRODUCTION
Luis Muñoz Fernández
This is the first of a series of five articles in which we will deal with a highly topical topic that has a great scientific, medical, social, economic and human impact: the so-called “personalized medicine” or “precision medicine”, its scope and expectations, as well as its reality in Aguascalientes. We will do it in a language accessible to the non-specialized public, without incurring in excessive simplifications that distort the message we wish to convey.
The origin of personalized medicine, which many consider a revolutionary change in the approach with which doctors are going to practice their profession from now on, can be traced back to the second half of the 20th century with the accelerated development of molecular biology. : the study and understanding of the phenomena that occur at the deepest or molecular levels of living matter. This story began in 1953 with the discovery of the structure of deoxyribonucleic acid, known to all as DNA, the molecule that carries genetic information that regulates the life of cells.
In the early 1990s, the Human Genome Project began, a multinational initiative with the aim of identifying and reading the information contained in genes, those portions of DNA with the instructions for making proteins, those responsible for carrying out the highly varied functions of our cells, including those having to do with specialized tasks: muscle contraction, transmission of nerve impulses, synthesis of carrier proteins such as albumin or hemoglobin, blood coagulation factors, antibodies that defend us from microbes, insulin that regulates glucose metabolism, cell division, etc.
All these functions take place within the cell cycle, the path that the cells of our body follow from their birth to their death, in addition to the division or multiplication of cells, of enormous importance for the subject at hand. The entire cell cycle is tightly regulated by various molecules or chemical substances that prevent or repair errors capable of causing disease or death. These regulatory molecules interact with one another through chain chemical reactions that scientists call signaling pathways.
Let’s give an example: for a cell to divide in two, it needs to receive a chemical signal that we call growth factor. This substance reaches the cell in question and makes contact with a specific molecule called the growth factor receptor, which can be on the cell surface (the cell membrane), inside it (the cytoplasm) and, in some cases, inside the cell. The very nucleus of the cell, the place where genetic information is stored. From the union between the growth factor and its receptor, a series of chemical reactions are triggered that will lead to cell multiplication: the cell (mother) will divide into two cells (daughters).
Ultimately, the presence of all those chemical substances that regulate cell life depends on the correct expression of the genetic information included in the DNA (the genes). Any factor or circumstance that alters the expression of genes (mutations, fusions, translocations, amplifications, etc.) can ruin the proper functioning of cells and, therefore, of our entire organism.
The DNA molecule is very delicate, which is why it remains inside the cell nucleus and each cell only reads the part of the information it needs to carry out its function. A neuron will read only the instructions necessary to synthesize neurotransmitters. A beta cell from the pancreas will not do what a neuron does, because its function is very different, and it will only use that part of the genome with the instructions to make insulin. And so for each of the cells, tissues and organs that make up our body.
Unlike the ancient anatomists, whose investigations revealed the structure of the human body as a whole (bones, muscles, arteries, veins, organs, etc.), today’s molecular biologists focus on cells and painstakingly “dissect” the cells. molecular signaling pathways, which has opened up the possibility of manipulating them to our advantage and thus treating hitherto incurable diseases. From knowledge of the human genome and from these other contributions of molecular biology, personalized medicine has emerged, which is the topic we will continue writing about in the coming weeks.
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