Cancer is rampant in almost every part of the human body.Tumors attack the brain and viscera, muscles and bones.Some are subliminal, and some are menacing.The appearance of a tumor in human tissue means that normal function is destroyed, the building will collapse, and the chaos will be chaos.The biological mechanism of the human body is so perfect, sophisticated and wonderful, but all this has undergone frustrating changes due to cancer.Wherever cancers show up, they always appear as alien life forms, sneaking into the human body and setting out on a journey of destruction within the human body.However, this is just an illusion: the truth is far more complicated and interesting.

Tumors are not foreign enemies to invade.They are of the same family as the substances that make up human tissue.Tumors are also a nightmare built by human cells. They erode biological order and destroy biological functions. If they are invincible all the way, they will cause the entire complex life system to collapse. How are cells assembled into human tissue?Presumably there must be some highly skilled architects supervising groups of workers taking their positions, forming normal or vicious organizations?In fact, such a role of calling the shots and mobilizing cell arrangements does not exist.The complexity of human tissue stems from each of the building blocks—the individual cells themselves.Change happens from the bottom up.

Both normal and tumor cells know their mission.Each cell carries its own program that tells it when to grow, when to divide, and how to join forces with other cells to build organs and tissues.Our bodies are extremely complex societies of highly autonomous cells.As a completely independent entity, each cell has its own characteristics. It is in this area that we find an astonishing degree of coordination, and at the same time, great risks.How wonderful it is that countless cells work together to create a unified, coordinated human body!And yet, what dangers are living beings in the absence of a chief architect overseeing them all!With trillions of workers fully autonomous, chaos is inevitable.Normally, the cells behave well, are enthusiastic about public welfare, and the human body is in order.But occasionally, inside an organ or tissue, a cell stands alone.At this time, the disaster that people are afraid of—cancer is coming.

Before people realize it, most tumors have grown into behemoths with billions or more cells.Cells within a tumor differ greatly from their normal behavior in many ways, such as shape, growth characteristics, and metabolism.The sudden appearance of such a large group of weird cells shows that there is a phenomenon of collective defection, and millions of normal cells have been thrown under the command of the tumor body overnight. However, this is again an illusion.Tumor formation is a protracted process, often lasting decades.All tumor cells are direct descendants of the same ancestor, an ancestor that lived many years before the tumor body manifested itself.This deviant and wanton cell started its own unique growth path in a certain tissue of the human body.Henceforth, it is its own internal programs, not the needs of the surrounding cell population, that determine its expansion behavior.

So, instead of millions of new recruits, there is a single initiator who produces a huge, consistent descendant of the rebellion.Like their rebellious ancestors, the billions of cells in a tumor have no interest in the healthy growth of surrounding tissue.Like their ancestors, they have a purpose: grow quickly, fission quickly, and expand infinitely. The chaos created by these cells shows how dangerous it is to let every cell in the body have its own way.However, for 600 million years, not only the human body, but all complex multicellular organisms have been constructed in this way.With this in mind, we recognize that cancer is not a modern scourge, but a peril shared by all multicellular organisms from ancient times to the present.In fact, considering the trillions of cells in the human body, it is a miracle that cancer does not appear frequently in our long journey of life.In vivo blueprint

To understand how tumors grow, we must understand the cells that make up tumors.Why did the pure individual cells behave uncharacteristically and act recklessly?In a nutshell, normal cells or cancer cells, how do they know when to start growing?Do cells have self-awareness?If the answer is no, what are the complex decision-making mechanisms inside human cells that determine whether a cell grows, sleeps or dies? The focus of this book is on the internal mechanisms possessed by normal human cells.This mechanism tells cells how and when to grow and join forces with other cells to create highly functional human tissues.The programs carried by different cells reflect the complex biological schemes and blueprints for their respective behaviors.As we shall see, this internal program changes when cancer develops.Only by understanding the normal and defective states of this program can we understand the dynamics that drive cancer cells.

There are hundreds of types of cells in the human body.Different kinds of cells aggregate to form different tissues and organs.Given the variability among individual cells, we might suspect that there are huge populations of programs in the human body, since each cell carries a different program, each indicative of a unique ability to grow and build tissue.Intuition leads us astray.In fact, despite the different appearances of cells in different parts of the body—whether it be the brain, muscles, liver or kidneys—they are remarkably similar, carrying surprisingly identical blueprints. This identity can be traced to their common origin.Like tumor cells, normal human cells originate from a common progenitor.They belong to a big family and have a blood relationship with each other. Through repeated growth and division, fertilized eggs have changed from a single cell to trillions of cells, forming the entire human body.The number of cells in an adult human body—more than tens of trillions—is far beyond people's imagination.

The blueprints that guide the cells of the human body are first seen in an early fertilized egg and passed down from generation to generation.Virtually all human descendant cells inherit this blueprint unchanged.But even though trillions of cells share the same set of behavioral norms, they still look and act very differently.There is a surprising disconnect between the cells' common internal blueprint and their alien exterior.Appearances, it seems, can't tell us much about the internal programs that guide the trajectory of a cell's life. How could a single, common plan make such a difference?Over the past few decades, people have found a simple answer: the complex master plan carried by human cells contains far more information than a single cell can possibly utilize.Single cells are selective about the common blueprint they possess.Read some specific information from a huge information base to design its own behavior.This selective reading makes every cell in the body unique, distinct from its relatives, close or distant.

The egg begins to divide shortly after fertilization, and its two daughters continue the process.The subsequent embryonic development process is the crazy growth and division of cells.The first few generations of cells produced by the fertilized egg look remarkably similar; they coalesce tightly into an undifferentiated, homorooted cluster of cells, forming a tiny berry.As the embryo progresses, the offspring of these cells begin to show differences.They begin to differentiate into members of muscle, brain or blood cell populations.This process of choosing different destinies—the process of differentiation—is the core secret of human development, and it is also a mystery entangled in the minds of researchers.

A cell in one corner of the embryo read the genetic instructions to produce hemoglobin and grew into a red blood cell; a cell elsewhere took the information to make digestive enzymes and became part of a pancreas; another cell learned how to release Electrical signals, become part of the brain. The decision that embryonic cells selectively read gene content to select for tuned traits is not the only important decision a cell has to make.In its genetic blueprint, it still needs to consider another crucial issue: when to start growing, dividing, and when to stop and rest. These instructions about growth are still important not only in the early days, but also for a long time in the future.Inside most mature tissues, cells are constantly being metabolized.In fact, the ability of a mature tissue to maintain normal architecture depends on successive mechanisms whereby the occasional loss of predecessor cells is compensated by the growth of numerous candidates.If there are too few candidates, the organization will wither and fail.If there are too many candidates, the tissue expands beyond its normal limits, perhaps distorting into a tumor.It is important to moderately control cell expansion, a task that occurs throughout an organism's lifetime.

To understand cancer, we have to understand how the internal blueprints of normal cells tell them when to reproduce, and we have to understand how the blueprints of cancer cells are messed up.The root of cancer lies in this blueprint.The number of genes has been debated.The most accurate estimate is somewhere between 70,000 and 100,000.The gene pool composed of these genes is called the overall blueprint of the human genome. The word blueprint implies precision, rigor, and meticulousness.A well-thought-out blueprint prevents chaos.Biologists have long been aware of the existence of such blueprints, even though they knew little about the inner workings of cells at the time.Originally associated with whole organisms, blueprints were later discovered to be integral to the survival of single cells as well. In the middle of the 19th century, the Austrian monk Gregor Mendel (Gregor Mendel) established the principle of organism genetics.He focuses on the transmission of genetic traits in plants of the genus Pisum—flower color, seed traits, for example.His research results were lost for a time, and it was thanks to three geneticists that they could be rediscovered in the early 20th century.What came to be known as Mendel's laws of inheritance are based on a few simple concepts.First, all complex organisms, from peas to humans, pass genes from parent to offspring by the same genetic mechanism.Second, the traits of an organism can theoretically be decomposed into the combination of a large number of independent traits, such as the color and shape of pea flowers, the color of human eyeballs, or the height of human beings.Again, every trait can be traced to the effect of certain invisible packets of information passed from parent to child through sexual reproduction.Efficient transmission of these packets of information enables offspring to acquire traits remarkably similar to their parents. Such packets of information are called genes; each human gene is charged with the function of building up a human trait.As we learn more about genes, it becomes clear that all areas of the human body, down to the inner workings of single cells that are invisible to the naked eye, are determined by the genes an individual inherits from his or her parents.It shows that the so-called overall blueprint is the great confluence of genes. We already know that blueprint genes are not stored in a single central warehouse in the human body.Instead, each of the trillions of cells carries a complete copy of the entire blueprint.This simple fact forces us to reconsider how genes organize their interiors in complex organisms: genes directly control the behavior of individual cells.Under the manipulation of its own genes, single cells, along with all other cells, create the form and function of an organism.The complexity of the whole organism thus represents the sum of the behavior of all the individual cells in the body.That is, the genome that dominates cellular activity is the same genome that controls an organism's appearance and behavior. There has long been controversy surrounding the number of distinct packets of information—an individual's genes—that make up a human's genetic blueprint.The most accurate estimate is somewhere between 70,000 and 100,000.The gene pool composed of these genes is called the overall blueprint of the human genome. The fact that the genome is divided into distinct genetic divisions has several consequences.As mentioned earlier, a cell can selectively draw volumes—different genes—from the shelf in its gene pool to read.Also, since packets are passed from parent to child, they are independent of each other.This better explains why we inherit certain genes from our parents.The gene pool of the fertilized egg is a mix of the genes each of the previous parents had. However, the description of genes as packets of information is still unsatisfactory because the imagination lacks a material basis.Sooner or later we have to dabble in the material content of genes.Like other components of an organism, a gene is a physical entity, so it necessarily manifests itself as identifiable molecules. Since 1944, we have known that the physical expression of genes is the DNA (deoxyribonucleic acid) molecule. DNA molecules carry genetic information.Their structure is very simple: each DNA molecule is a double helix made up of two strands coiled around each other.Each chain is a long polymer composed of a single component arranged end-to-end in a longitudinal direction. For the convenience of discussion, this single component can be called a base. There are four kinds of DNA bases - A, C, G, T". The important thing is that these four bases can be combined arbitrarily. The sequence of bases determines the information content of DNA. Bases can be arranged and combined indefinitely. Correspondingly, The DNA chain can be as long as tens of millions of bases. Intercepting a fragment from such a long chain is a specific base sequence, such as ACCGGT.-CAAGTTTCAGAG. Modern gene technology enables us to discover bases through the process of "DNA sequencing" Sequence. So far, from bacteria, worms, flies to Homo sapiens, people have determined tens of millions of base sequences of different organisms. The variety of DNA base sequences means that, in theory, DNA molecules are large enough to hold any information, biological or otherwise.At first glance, the information-carrying capacity provided by the combination of only four letters is very limited, but in fact, four letters are more than enough.The three characters of Morse code (dot "·", dash "one", space "'), and the two characters of computer binary code (0 and 1) also have unlimited information storage capacity. The DNA double helix actually carries two sets of genetic information, one on each of the two strands that are coiled around each other.Since the epoch-making discovery of James Watson and Francis Crick in 1953, we have known that an A in one strand of the double helix always corresponds to a T in the opposite strand; a C necessarily corresponds to g.The sequence ACCGGTCAA on one strand will thus be intertwined with the complementary sequence TGGCCAGTT on the other strand. The sequence on the other strand can be deduced from the base sequence of one strand, so the information carried by one strand is also reflected in the other strand, although it appears as a complementary language.This store of information has many benefits, the most important of which is that the spiral can thus be replicated.Especially as shown in Figure 1.1, each of the two parts can be used as an independent template to replicate a new complementary sequence, and the new sequence wraps its own template.As a result, the two double helix daughters are identical to each other and to their parent double helix. When cells grow and divide, the duplication of base sequence shows its importance.In the process, a mother cell imparts to its future daughter cells the ability to make precise copies of its own DNA helix.Mother-to-child transmission allows the genetic information contained in the DNA of the original fertilized egg to be passed on successively during hundreds of rounds of cell division to the billions of offspring cells that eventually form the adult human body. So how does the abstract concept of genes relate to the physical structure of DNA molecules?The DNA double helices contained in the chromosomes of cells are often hundreds of millions of base pairs in length.These long chains of bases can be divided into different parts according to their information divisions, and each division constitutes a gene.An ordinary human gene consists of tens of thousands of DNA bases.Within the four-letter base sequence, certain punctuation marks mark the end of a gene.In English, the beginning of a sentence is a space followed by a capital letter; the beginning of a gene is a special short sequence of several thousand bases.Similarly, English sentences end with a period, and the tail of the gene also has its unique base sequence that acts as a punctuation mark.On the helical chain, after the end of a gene and before the punctuation sequence that marks the beginning of the next gene, there is often a sequence consisting of several thousand bases, which is a meaningless genetic noise. The entire information content of the human genome consists of a DNA sequence consisting of 3 billion base pairs, which can be divided into 70,000 to 100,000 regions representing different genes.Working in different combinations in our cells, these genes create our incredibly complex structure, including the brain, a highly sophisticated organ. The story of genes, DNA double helix, and base sequence provides a golden key to our understanding of human beings, and even all life forms on earth.But we're here to focus on just one small piece of that complex ensemble, human cancer.We can ignore the difficult question of how genes instruct cells to assemble into tissues and organs, and focus on the smaller question of how genes influence the growth behavior of individual cells. So we narrowed our sights to a small set of genes that control the growth of individual cells.These genes will lead us directly to the heart of the cancer problem, they will reveal the origin of cancer, and one day, they will also point us to the bright road to defeat cancer.