Cancer News Information

The comparison between the different types of cancerous tissues with the normal with regard to genomic instability, shortening of the telomere and the expression status of telomerase indicates that the telomere problem is intricately associated with malignancy. It has become so significant in the cancer etiology studies that the measure of the length of telomere has been used as one of the routinely used biomarkers to understand the telomere dysfunctioning and the associated risk of cancer. There are enough evidences available to implicate the telomere length with cancer and hence it can be targeted for successful therapeutic approaches.

Pre-existing knowledge

There are available literatures to suggest that the telomere shortening and telomerase absence share a direct correlationship with increased cell divisions and as a result the cells senesce with a fixed number of multiplications. It has been suggested that crossing a threshold limit of shortened telomere length results in telomere repeat loss which is regarded as DNA damage cue and hence the decision to withdraw from cell cycle and resultant apoptosis. Accordingly, the role of the telomeres has been implicated to that of a biological clock determining the multiplicative lifespan of the cells. The study by the group of Bodnar further confirmed this theory when they introduced telomerase catalytic units into human fibroblasts lacking in telomerase and found elongation of the telomeres with an enhanced ability to replicate. The imposed restriction of cell cycle in these cells is maintained primarily by the tumor suppressors Rb and p53 which recognizes the DNA damage and halts its progression. It has been found that the cells transformed with viral agents like E1 or SV40T could bypass such regulation and undergo additional cycles of division although not indefinitely. Besides, the telomeres have been found to be active both in the germ line and stem cells but that in the somatic cells it isn't so.

Cancer diagnostics based on telomeres

Telomeres have now found its way into the field of cancer prediction and diagnostics. Recent advances in the field have made them more efficient and precise tools for use in that purpose. In a very recent work, it was proposed that repeats of single stranded DNA molecules C circles that constitute the telomeres can be highly significant in cancer prediction. It was found that higher positive C circles were observed in ALT positive human cells. The formation of diagnostic tools based on telomerases is likely to be more in use in the future.

Association between telomerase activity and cancer cases

Biopsies of 12 different types of human cancers demonstrated the existence of telomerase activity. Clinical data from patients with metastatic or primary cases of cancer indicates a dormant stage before an aggressive progression towards metastatic growth. Some studies have implicated the activity of telomerase with cancer dormancy. Recently, it was found that 73% of lung carcinoma patients (stages III and IV) and 72% of colon cancer patients have active telomerase by Gauthier and his colleagues. Stage IV breast cancer patients revealed similar results. Therefore, telomerase activity detection is a good indicator of cancer progression. While the telomerase-/- cells provides valuable insights into the stage of cancer dormancy, the positive cells can be useful in the prediction of the recurrence of the disease. On a more generalized form it has now been accepted that the shortening of the telomere limits the life of the normal cells and the telomerase activity can overcome this imposition of replicative restriction and make them immortalized. It becomes imperative to study the underlying mechanisms of the regulation of telomerase in order to target them in cancer cases.

Telomerase activation and cancer

Telomerase has become a hot target for cancer related therapeutic interventions considering the fact that it is expressed only poorly in normal cells while is required at an enhanced levels for the maintenance of telomeres for rapid cell proliferation that is associated with cancer progression.

However, with these pieces of evidences there may be high apprehensions regarding the use of telomerase activity enhancing supplements with respect to the increase in chances of cancer. The regulatory mechanism of telomerase activity is still very paltry to suggest a one-on-one relationship between cancer progression and the need of telomerase activity. Reports are also now accumulating for anti-aging related telomerase activity increment without increasing the cancer chances. According to a very recent report published in the EMBO Molecular Medicine, a group of researchers from Spain demonstrated that telomerase can be manipulated to increase longevity without the risk of cancer. There are also other arguments that favor the safe and effective use of telomerase activators. Scientists are of the opinion that although telomerase is needed for the maintenance of the rapid growth and proliferation of cancers, it has often been found to be mutated in a plethora of human cancers which are arguably more aggressive than the rest. Therefore, there needs to be valid comparison of the roles of the mutated and normal telomerase activity from the viewpoint of cancer regulation. There are also suggestions that the telomerase in the first place would try to maintain a healthy DNA away from damage that is not susceptible to cancer. Researchers are of the opinion that infact the activation of telomerase can be used to prevent cancer. Therefore, the active use of telomerase stimulators is quite valid and worth a try given the promise it holds in the rejuvenation of youth and the alleviation of a number of age and non-age related disorders in humans.