We must die every day; if not, we are inviting cancer!
You read the title right. It is the obstinate desire of some cells to live on that causes cancer, supposed to be one of the deadliest and most scaring diseases.
Let me explain.
In all advanced biological systems, which would include all plants and animals that we see around us and the humans, cells die all the time. In a healthy adult human body, about 330 billion (33,000 crore) or about one percent of cells, which comes to more than a kilogram in weight, die every day. At this rate, in about a hundred days, as many cells have been replaced as there are in the body.
Not all cells die that quick, and some live for many years. Some cells in the heart, brain and eyes last a lifetime. But living a life-time is an exception; death is the rule.
There is no mercy in the cellular world inside us
Cells are the basic unit of life. In the society of cells that makes a living being, suicide, mercy killing, murder: all means of death are enforced as required.
The most prominent method of killing of cells is given a tongue-twister name by scientists: apoptosis – the inherent programming of cells to kill themselves. In other words, cells are programmed to destroy themselves. This self-killing takes place by breaking down of cell parts, some parts turning into small vesicles for consumption by other cells or the cell eating up its own parts (called autophagy). It is so well programmed that the cell has no choice but to commit suicide when the time comes. (There are many other ways a cell can die, for example in fighting a pathogen or when attacked by a toxin. Let this article be confined to programmed cell death.)
The programming for death happens at the genetic level, but the whole body acts as a society and is programmed to enforce killing where required, and dispose of the dead cell in the best possible way.
The 2002 Nobel Prize for Medicine went to three scientists for studying programmed death in a tiny nematode (worm). They found out the exact number of cells that died regularly due to programmed death and which genes regulated the process. They, and their successors, have been able to pin-point the molecular mechanism that sets the suicide into action.
The programming for cell death can take very curious forms. In some small organisms, some of the cells that arise out of division of the parent cell are weaker by design, and they must die so that the others survives. The red cells in the blood are made to lose their living organelles so that they – the dead cells – carry out their function of transportation of oxygen.
Sometimes the other cells in the body conspire to block supply of nutrients to other cells so that they die – and this does not happen due to jealousy or conspiracy; this is the way they are programmed. A molecular signal that other parts of body send to the cells (that need to die) or disconnect their food supply (or something else), the target cells respond usually by committing suicide.
Unbelievable as it may sound, in many types of cell deaths (mostly due to external factors), the dying cells communicate the danger to the living ones.
The death of cells in a programmed way is necessary for not only constant rejuvenation of the body, but also differentiation of body parts in the womb and later. Without this programmed death of cells, the tissues that were formed in the womb would remain there, and we would retain a tangled body with ears glued to the body, eyes not opening, fingers bound by a net of tissue, and so on.
In some cases, cells are made to die en masse for the good of the organism as a whole, as in the case of annual leaf fall, loss of lizard’s tail to avoid a predator, and formation of nails.
The biological world is full of mass killings of cells. In higher plants, a huge number of cells in the trunk must die so that canals (called xylem) are created for flow of fluid up the trunk.
An extreme case of programmed cell death occurs during metamorphosis in insects. In them, the egg gives rise to a creepy larva which then turns into a very different looking pupa, which in turn converts itself into an insect – a totally different creature. During this transformation, an enormous number of cells die – they either convert into new types of cells or are consumed in the process or are thrown out as waste.
It is not known how cell death evolved among multi-cellular organisms. It is argued that this could have started as a defence mechanism, and also adopted as a part of evolution into more complex organisms.
There also is a yet-unexplored mechanism that sets the lifespan of the entire body – which is much more complex than a simple average (or sum, if you like to call it that way) of the lifespan of individual cells. An interplay of numerous physiological processes is involved, and it is likely that it matured during evolution from simple to complex living beings.
Whether it is evolutionary learning or something else, the same genetic material can behave in strange ways and how it behaves in a particular cell is guided by how the genes in the rest of the body behave. Genetics also interacts in curious ways with social phenomena. It is interesting to know that among highly social insects (such as ants and bees), workers die much sooner than some privileged classes though all arise from the same set of eggs.
So, from a purely biological perspective, death of the body should not look an unnatural, one-click affair. It must keep dying a daily death, without caring for the Shakespearean taunt, ‘cowards die many times before their deaths.’ Constant death is the secret of a living being’s health.
When certain cells revolt against the death warrant
It so happens that out of trillions of cells, some refuse to die. In a highly programmed society, this is taken as mutiny, and the system tries its best to crush it.
But what if some of them turn terrorists and organize themselves as strongly as LTTE or ISIS?
That leads to cancer!
Numerous cells in a biological being – take the example of the human body – keep dividing all the time. In most cases, the parent cell breaks into two or more cells, or it gives rise to new cells and – when time comes – kills itself. How many cells a parent cell would produce and in what time-span are so finely programmed and the programs are so well executed that a balance is maintained – and the body retains its health. However, sometimes a cell and its progenies turn rogue and keep dividing. Normally, an uncontrolled division in a body part would get limited by the space it gets or the nutrients it is supplied. If not, body’s defence mechanism would keep it in check. In fact, thousands of such occurrences take place every day in a healthy human body, and they do not cause even minor discomfort or pain.
Sometimes the rogues manage to outsmart the system to some extent, and produce lumps of tissues, called tumours. Even then, not much harm is done: most tumours are benign, and they grow at one place and stop growing after a period of time.
Problem comes when the multiplication goes haywire and the rogues start behaving like terrorists. They cause lumps or tumours that keep growing, their pieces breaking up and entering body fluids (blood and lymph), and reaching other body parts – where they repeat their unbridled growth. In some other cases, they do not produce lumps but keep dividing in body fluids, reaching different organs and multiplying there. That is what is called cancer.
Cancer, thus, is the result of certain cells refusing to die and continuing to multiplying. The cells so produced not only physically overwhelm the system, they produce biochemical changes that are harmful to the body. They can block nutrient and oxygen supply to organs while stealing the supplies for themselves, overload the system, stress the immune system, disrupt function of other cells… So varied is their damage potential that about a hundred diseases are associated with the term caner.
It is rare that a cancerous cell inherently wants to cause cancer. Just about five percent of cancers happen due to heredity while the rest occur due to external factors. Among the most well-known carcinogens are: radiation with ionising rays (e.g. X-rays), consumption of carcinogenic chemicals (e.g. smoking), being in contact with certain chemicals (e.g. benzene), and certain types of pathogens (e.g. H. pylori bacteria in stomach). Aging happens to be a big factor, and certain body parts are more prone to triggering carcinogenic processes (e.g. prostate gland in men, breast tissues in women).
Will the ultimate cure of cancer come through reverse programming?
When cells turn rogue, they are no less than tough terrorists with their own defence systems. They develop defences against body’s repair mechanisms, and even quickly develop resistance to cancer treatments. And the problem with very potent treatments is that they often damage healthy tissues or have serious side-effects – giving a huge tactical advantage to the rogues.
So, at a conceptual level, triggering of apoptosis (=programming to kill oneself) among malignant cells does provide an answer.
The Nobel Prize winning discovery mentioned above, suggested that triggering apoptosis in cancer cells would be a potent cure against all types of cancers. However, it has not found a practical application so far.
Viruses, too small to physically kill cells, are among the most cunning biological molecules. They enslave the cell’s molecules in a way that the apoptosis mechanism is triggered and the cell dies without a fuss. So, a way to simulate that type of suicide among the cells may be possible with the help of genetically programmed viruses. However, genetically manipulating viruses is an extremely risky proposition (COVID-19 might be the result of such a manipulation. Even if not, it indicates the dangers of genetic manipulation of microbes).
For some years, autophagy (or cells eating up a part of themselves, for cleaning purposes) was thought of as a potential treatment for cancer (and is still being pursued as a potential treatment of cancer). Studies have found that suppression of autophagy and malignancy were somehow correlated. But it has also been discovered that cancer cells can turn the tables when autophagy is induced in them: these cells eat up only their damaged parts – thus getting more potent!
If we develop cancers from the cellular tendency to keep multiplying, the opposite – tendency to die prematurely – leads to another set of equally serious diseases. The Alzheimer’s disease is one such disease. In Alzheimer, the self-eating (so, self-cleaning) mechanism in brain cells is upset, the cells accumulate filth, and death ensues. Scientists are studying whether this propensity to die can be inculcated in cancerous cells – but we are nowhere near a breakthrough.
May the cell die [an honourable death]!
This article does not seek to delve too deep into cellular or molecular mechanisms of cell death, or on how cancer could be cured. The idea is to stress that our body is an extremely complex biochemical soup, and its mechanisms are too complicated and interdependent. In this living system, however, the urge to live is not always a positive. If human body were a computer game, the aim is to live the programmed life and then die, and the dreaded disease called cancer happens when certain players (cells) wrongly aim to keep living.
*Manoj Pandey is a former civil servant. He does not like to call himself a rationalist, but insists on scrutiny of apparent myths as well as what are supposed to be immutable scientific facts. He maintains a personal blog, Th_ink
Disclaimer: The views expressed in this article are the personal opinion of the author and do not reflect the views of raagdelhi.com which does not assume any responsibility for the same.