It is written in Ecclesiastes, “To every thing there is a season . . . A time to be born, and a time to die.”
So it is with the cells of our body; so it is not for cancer cells.
Each cell is born with a finite, predetermined life span.
Some cells are meant to live for just a few hours, others (such as our brain cells) to survive all our lives.
In addition, as cells undergo subtle changes as part of the normal aging process and experience the wear and tear of life in the body, some accumulate sufficient damage that requires their removal and replacement.
In order to maintain just the right balance of cells at all times, our bodies have developed an elaborate biological system.
This system clears out defective cells, eliminates diseased ones, and removes older ones to make room for new ones.
The system actually operates inside each cell that is to be eliminated. When a cell’s “time is up,” a large network of molecules within the cell, which had been maintained in an inactive, or “locked-down” state, is liberated.
This set in motion a cascade of chemical reactions that cause the cell’s various internal parts to dissolve, leading to cell suicide; the cell breaks into smaller units that are carted off by scavenger immune cells.
To ensure that the process of cell suicide never fails, Mother Nature has programmed it into our genes – that is, the DNA of nearly every living cell has within it the potential to take a dagger to the heart of that very cell.
The process is called “programmed cell death,” or apoptosis. In Greek, apoptosis means “falling off” or “dropping off,” as in leaves from a tree or petals from a flower.
Apoptosis is rarely mentioned in mainstream media reports on science and medicine.
This is unfortunate, because apoptosis plays a pivotal role during the development of animals and in their health and disease. For example, when a tadpole metamorphoses into a frog, its tail disappears because the tail cells undergo apoptosis.
To sculpt the fingers and toes of the developing human fetus out of an amorphous mound of tissue, the cells between the individual digits undergo apoptosis and fade away.
When a virus infects us, it survives in our bodies by living inside certain cells; to rid the body of the virus, our immune system forces the infected cells to undergo apoptosis, taking the virus down with them. Slowly debilitating diseases of the nervous system, such as Parkinson’s disease and Alzheimer’s disease, are characterized by the progressive loss of nerve cells in the brain, which undergo premature apoptosis.
Why is apoptosis so important to cancer?
The answer is that cancer cells have a diminished ability to undergo apoptosis. That is, they resist the signals that tell a normal cell to die. They ignore their programmed life span and fail to commit suicide when they are old; they live on in the face of injury after wear and tear; they resist the immune system’s attempt to delete them.
Cancer cells can do all these things because they have an altered genetic program of apoptosis wrought by changes (mutations) in their DNA.
The result is that, inside a cancer cell, the programmed cell death apparatus is in perpetual lockdown. If left to their own devices, most cancer cells in any tumor would fail to die and the tumor mass would keep growing.
Fortunately, cancer cells’ resistance to apoptosis is relative; many cancers will undergo apoptosis when targeted by anticancer treatments.
As we know, some cancers are more successfully treated than others.
Curable cancers (for example, testicular cancer and Hodgkin lymphoma) rapidly undergo apoptosis upon treatment; whereas those that are difficult to cure fail to undergo total apoptosis in response to treatment (treatment resistance is explained in later).
Causing the death of cancers through apoptosis is a major goal of cancer therapies and of course the main desire of cancer patients.
In sum, the capacity to die exists within all cells.
In nature, life and death are equally important and must be in balance.
Normal cells obey the internal commands of their predetermined life span or the external cues of the body and commit suicide when so directed.
Cancer cells disregard these signals and resist apoptosis.
They have acquired an inability to die; the goal of cancer treatments is to overcome this barrier to their destruction.
