Uncover the mystery of "cell immorality".

Uncovering the mystery of "cell immorality", from "The Heffreck Limits" to the "End Reproduction Problem", back in the 1950s, scientists learned from a woman with cervical cancer, Herita Lax, the story of Hela, a cell line that is now probably used in biomedical laboratories around the world, and made us realize that human cells can indeed survive in in-body laboratories.
the early 20th century, most scientists believed in the ability of cells to live forever.
, a French surgeon who won the 1912 Nobel Prize in Physiology or Medicine, firmly believes that all cells in the human body have the ability to live forever, and that they can divide and multiply indefinitely as long as the environment and nutrients are right.
, however, not everyone agrees.
In 1961, an American anatomist, Hefferick, found that normal human cells could only divide about 60 times under in vitro culture conditions, then enter the aging phase and eventually die, known as the "Heffreck limit", thus refuting Carrel's argument that "normal cells are immortal."
the "Heffreck Limit" was eventually linked to chromosomal telomeres discovered in the 1930s, revealing the mystery of "cell immorality".
telomeres are a special complex structure formed by the repeated sequence of DNA at the end of chromosomes, which is essential for chromosomes to maintain their structural integrity and stability.
In the 1970s and 1980s, scientists realized that, because of the particularity of the DNA replication mechanism of genetic material, the ends of pro-generation chromosome DNA must be lost in children because they could not be copied, known as the "end replication problem", which inevitably led to the constant deterioration of chromosomal telomeres and instability of chromosomes, which in turn led to cell aging or death.
this is the so-called "telomere hypothesis" of cell aging, which also explains the aforementioned "heffreck limit" problem.
, telomeres seem to be the key to uncovering the secrets behind the "Heffreck limit" and "cell immorality".
between 1975 and 1977, American scientist Elizabeth Blackburn discovered that telomere DNA is a sequence of hundreds of repetitions made up of extremely short DNA sequences.
, for example, telomere DNA in humans and mice is a repeat sequence of TTAGGG.
1985, Blackburn and her Doctoral student Carol finally found telomerase involved in the extension of telomere DNA - a mystery that was finally solved.
telomerase is able to synthesize the telomere DNA sequence TTAGGG through a subtle mechanism, add it to the end of the chromosome, maintain the length of the telomere DNA, and solve the "end replication problem".
In normal human cells, telomerase activity is quite tightly regulated, and telomerase activity can only be detected in certain cells that need to be continuously divided, such as hematopoietic stem cells and reproductive cells, while differentiated mature cells generally no longer need to divide, telomerase activity has been lost.
, if differentiated cells are cultured in-body, they will inevitably reach the "Hefferick limit" and enter the aging phase and eventually die.
, cancer cells, as immoral cells in a sense, must break through the "Hefferick limit" to solve the "DNA end replication problem."
In the process of cell cancer, the absence of various anti-cancer genes and the activation of cancer genes, although the cancer cells can be the car to release the brakes, add throttle, let it move forward quickly, but if every kilometer of walking, car tires (cell DNA) to wear, it will always have tire scrapping, can not move forward one day.
, "evil" cancer cells choose to increase telomerase expression and reactivate telomerase activity.
about 90 percent of all types of cancer cells chose this strategy, as did Hela cells.
the study of telomerase, to a certain extent, ignited people to extend life, and even the pursuit of long-lived enthusiasm and hope, thinking that found a human life "switch."
many studies targeting mice have shown that the expression of telomerase TTERT does extend their lifespan to some extent, but also increases the risk of cancer.
multicellular higher animals, including us humans, are undoubtedly highly complex metabolic systems.
China Science Daily 2017.2.10 Source: Science And Technology Daily.