Abstract: Despite their much-heralded clinical potential, therapeutic cancer vaccines have thus far failed to achieve the necessary clinical benchmarks to allow their regulatory approval. In contrast, vaccination against infectious pathogens represents one of the biggest achievements of modern medicine, and in certain cases such as vaccines against the human papilloma virus or hepatitis B virus, vaccination may impact the development of cancer. To the extent that these two approaches differ as immunotherapy vs. immunoprevention, the challenge is to rethink the types of non-viral antigens that are currently being targeted in cancer vaccines. Immunological analysis suggests that the telomerase reverse transcriptase hTERT is a widely applicable target recognized by T lymphocytes and a prototype for a novel class of universal tumor antigens. Findings from initial clinical trials demonstrate that hTERT-specific immune responses can be safely induced in cancer patients. If the amplitude and duration of cellular immunity against hTERT can be optimized without toxicity in humans, then an opportunity exists to test hTERT vaccination as a way to reduce the risk of cancer recurrence in patients or even the risk of developing cancer in otherwise healthy individuals. ... Read more

Abstract: Typical cells are subject to the fate of replicative senescence -- a key mechanism of our aging process. Cancer cells and, to a certain extent, immune cells have a mechanism to replenish the lost sequence of the telomere and allow them to divide without the usual constraints of replicative senescence. ... Read more

Abstract: Each time a cell divides, the DNA sequence at the end of the chromosome, called the telomere, shortens by a small stretch. After the telomere has shortened to a certain point, the cell stops dividing, ages, and eventually dies. Telomerase is an enzyme that can add back what telomere has lost during cell division. The functions and dynamics of key components of telomerase are discussed. ... Read more

The ends of linear eukaryotic chromosomes are capped by telomeres, which consist of tandem repeats of TTAGGG. In human cells, the overall telomere length ranges from 15-20kb at birth, to less than 5kb in some individuals with chronic diseases. Telomeres ensure the integrity and stability of chromosomes. Each time a cell divides, the telomere is shortened a bit until it reaches a minimum length at which cells stop dividing and remain quiescent or die by triggering a p53- or RB (retinoblastoma)-mediated DNA damage response.

Telomere length is regulated by telomerase, the enzyme that adds the hexameric repeat TTAGGG back ... Read more

Dr. Richard M. Cawthon and colleagues from the University of Utah, Salt Lake City, UT have found for the first time in humans that the length of the telomere is related to longevity (Lancet 361:393-395, Feb. 1, 2003).

The researchers studied the telomere length from 143 individuals and their longevity. Study subjects of ages between 60 and 97 were generally healthy, unrelated individuals who donated their blood between 1982 and 1986.

They found that elderly individuals with longer telomeres lived five to six years longer than individuals with shorter telomeres. Those with shorter telomeres in blood DNA had a 3.18-fold higher mortality ... Read more

Carol Greider took a Ph.D. thesis project that no other students dared to touch: to prove a theory that the telomere does exist. Her daring deed paid off. Upon her graduation with a brilliant thesis under the guidance of Dr. Elizabeth Blackburn at UC, Berkeley, she was recruited by Nobel Laureate Dr. James Watson to the Cold Spring Harbor Laboratory. There, eventually promoted to full investigatorship, her continued research on telomere and telomerase has created one of the major research fields in cancer and aging.

Telomeres are at the end of linear chromosomes that are comprised of TTAGGG repeats. They are ... Read more

The length of the chromosome telomere has been associated with divisions and senescence of normal cells. Telomerase, the enzyme that adds nucleotides to the telomere, controls the telomere length. For instance, in stem cells and cancer cells, telomerase activity is abundant and replenishes the lost segments of the telomere during the normal cell divisions and therefore perpetuates the cell’s ability to grow and divide. Telomerase is comprised of an integral RNA component, which serves as the template for the synthesis of TTAGGG repeats, and protein components including the catalytic subunit hTERT (human telomerase reverse transcriptase). Normally, each time the cell ... Read more

Researchers have recently elucidated the 3-dimentional structure of telomerase, a molecule that plays a key role in such important areas as cancer, aging/longevity, immunology, and stem cells.

Each chromosome (containing a unit of the genome) has a telomere at each of its ends. Telomere, a stretch of DNA, protects the integrity and stability of the genome. A piece of telomere is “clipped” off each time a cell divides. Telomerase is the enzyme that makes more telomere to replenish the shortfall. When a person reaches adulthood, telomerase becomes inactive in most somatic cells (non-sex cells). Consequently, cells stop dividing and regeneration, and ... Read more