Telomerase-The New Tree of Life?
For years scientists have thought that aging was under the control of a "biological clock"-a cellular function regulating growth and programming cell death. Normal cells divide only a certain number of times before they die. But a puzzle to scientists has been that cancer cells have the peculiar ability to divide indefinitely; they are immortal. Now scientists at Geron Corporation and the Cold Spring Harbor Laboratory suggest that the term "biological fuse" may be more descriptive than "biological clock."1 The biological "fuses" are called telomeres-repeating DNA fragments found at the ends of chromosomes. In normal cells, the fuse bums slowly until it bums out, then the cell dies. In cancer cells, the fuse appears to be relengthened so it never completely bums out. An enzyme called telomerase, identified in cancer cells, appears to be responsible for the relengthening of telomeres.
Chromosomes are large segments of DNA covered with protective proteins. The DNA in the chromosomes are the informational libraries of the cell. The complete DNA library in a cell is called the genome. It appears that the molecular "fuses," the repeating telomere DNA fragments, protect the ends of the chromosomes and the DNA from degradation, end-to-end fusion and rearrangement. The human telomere sequence was found to be TTAGGG.2 This telomere sequence is the binding and initiation site for DNA polymerase, the enzyme responsible for copying (replicating) the DNA chain just before cell division. The DNA polymerase first sits down on the end telomere sequence, and then begins copying the DNA at the next telomere sequence up the DNA chain. By so doing, the copied (daughter) DNA is shorter by one telomere sequence than the starting (parent) DNA. Subsequent DNA replications (subsequent cell divisions) continue to shorten the DNA until eventually the last telomere sequence is used up, the DNA becomes unstable and the cell dies. In cancer cells the end telomere sequences are continually replaced by the enzyme telomerase.
Could telomerase one day become the anti-aging enzyme, the "fountain of youth" sought after by humans ever since the fall? Have we finally stumbled upon the cure for cancer? Could we design an enzyme inhibitor (more specifically, a telomerase inhibitor) that will allow cancer cells to die and, thus, effect a "cure"?3
As Christians we should also be concerned with the theological implications of a potential "fountain of youth," a new "tree of life." From Genesis we learn that death came into the world because of sin.4 Once sin entered the world, evil was known.5 God put Adam and Eve outside the Garden of Eden, not only to have them toil for their food but also to cut off their access to the tree of life.6
But humans in their fallen state desire to regain eternal life in the flesh all the while rejecting God's grace for eternal life in the spirit. They do not want to submit to God's plan for eternal life because it requires them to acknowledge the existence of God and of their own sin, to ask God for forgiveness and to turn from their wicked ways.
As Daniel prophesied, in these last days, knowledge is greatly increasing.7 Will humans be able to increase the days of their lives by this new knowledge of the telomere and telomerase? To achieve this, there are many practical problems to overcome, but it may one day be possible. To those who do not know Christ, this increased lifespan will be highly sought after. But the Christian's goal is described by the Apostle Paul: "To live is Christ, and to die is gain."8
Donald Clark received his Ph.D. in Physical Biochemistry from Louisiana State University in 1972. He is currently the Vice President of Development and Medical Affairs at Houston Biotechnology Incorporated in The Woodlands, TX.
1. "Telomerase May Be Key to Cancer and Aging, NCI Funds $2 Million, Five- Year Collaboration, " Genetic Engineering News, Sept. 15, 1995, Vol. 15, No.16, pp. 1, 13,35.
2. T represents a thymidine nucleotide, A an adenosine nucleotide and