General initial thoughts

The ability of cancer cell lines to remain immortal is comprehensively based on the balance between activation of cancer-promoting genes and suppression of cancer-preventing genes. The same mechanism must hold true for human immortality: there is a need to activate (so called) immortality promoting genes and suppress genes that code against it. Inducing or suppressing genes is currently achieved through virus-vectors, or transposons.

We propose that immortality-promoter and immortality-suppressor genes already exist in our genome. These have not yet been described in detail although some attempts have been made with regards to germ-line immortalisation.

During transcription, at the stage of pre-initiation, there needs to be an understanding and study of the different ratios of initiators vs repressors, as well as an understanding of which DNA region is to be targeted. This is a basic initial step. From there follows the stage of initiation, the regulation of which should be easy compared to the previous stage.

Mathematical exploration

The exact point (conception? morphogenesis? birth?) of theoretical divergence from the current pathway A or 'death pathway', to pathway B which does not lead to death, can be described with Bifurcation Theory, in particular global bifurcations (homoclinic, infinite period or a blue sky catastrophe). Bifurcation theory studies any changes that happen to the qualitative or topological structure of vector fields or to the solutions of a family of differential equations. In order to start the mathematical calculation it is necessary to know the parameters involved in the process, for example:

1. The concentration of each promoter (CP)

2. The concentration of each repressor (CR)

3. The in-vivo physiological activity of each promoter (AP)

4. The in-vivo activity of each repressor (AR)

5. The DNA segment location of intervention {LI -LI(n)}, as there could be many DNA locations

6. The level and activity of acetylation parameters (ACP)

7. The level and activity of methylation parameters (AMP)

8. Other parameters or constants

In practice we could look at:

1. Activation of DNA segments that transcribe for 'non-death pathway molecules' (NDPM)

2. De-activation of DNA segments that transcribe for 'death-pathway molecules'(DPM)

3. Increase transcription factors of NDPM

4. Decrease transcription factors of DPM

Once we know the parameters involved in the process, we will be able to describe the process mathematically and start an exploration of ways to influence these parameters in order to force the process to operate in the desired direction.

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Existing technology can help in a variety of ways. Below are some current examples:

* How to transfer genes into cells:

Targeted gene delivery via ultrasound microbubbles, which contain the gene and transactivating transcriptional activator peptide. This method is an effective vehicle for gene transfection (Ren J, Xu C, Zhou Z et al. A novel ultrasound microbuble carrying gene and Tat peptide: preparation and characterization. Acad Radiol 2009;12:1457-65). So, when/if the genese that are relevant to immortality are discovered, these can be delivered into the stem cell using this method, among others.

* Nanotechnology

Silver nanowires can attach themselves onto the DNA chain and influence some of its caracteristics, such the vibration properties of deoxyribose (Ban G, Dong RX, Li K et al. Preperation of DNA silver nanowire and its Raman spectra. Guang Pu Xue Guang Pu Fen Xi 2009 29(2):402-5). This is an example of how nanotechnology can directly influence the DNA molecule and attempt to modify its properties. This may be a useful tool in forcing the DNA to operate in a certain beneficial direction.

Another way of influencing DNA is with single-walled carbon nanotubes (SWCNT). It has been shown that exquisitely pure SWCNT can be used in DNA-based nanostructuring (Muller K, Malik S, Richert C. Sequence-specifically addressable hairpin DNA_singe-walled carbon nanotube complexes for nanoconstruction. ACS Nano 2010 Jan 19 (Epub).

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An example of how it may be possible for cells to acquire immortality

 

It is known that during immortalisation and subsequent carcinogenesis, certain cells (human mammary epithelial cells - HMEC), overcome two distinct proliferation barriers (Novak P, Jensen TJ, Garbe JC, Stampfer MR, Futscher BW. Stepwise DNA methylation changes are linked to escape from defined proliferation barriers and mammary epithelial cell immortalization. Cancer Res. 2009;69(12):5251-8). The first barrier called stasis can be overcome by loss of expression of the p16(INK4A) gene. Once this barrier is overcome, HMEC continue to proliferate, albeit becoming genomically unstable. The second barrier is telomere attrition which can be overcome through acquisition of telomerase expression, which leads to true immortalisation and malignancy. The above steps coincide with changes in DNA methylation processes. Although the final result is not only immortalisation, but unfortunately also malignancy, nevertheless the above process may help explain how immortalisation may be acquired. It remains to be seen how the two processes of immortalisation and carcinogenesis can be separated and how the former can be achieved without the latter. Be that as it may, the current way of viewing cancer can be challenged: Cancer could be seen as a manifestation of our inherent ability of living forever, but it lacks suitable regulatory mechanisms and therefore it results in an unregulated tumour instead of an immortal intelligent organism. One of the main reasons why cancer has not been evolutionarily selected out is that because cancer cells keeps re-setting to zero and are therefore immortal. The putative Pereq mechanism could operate on the same basis.

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Transposons: Potentially useful?

 

Transposons are divided into DNA transposons and retrotransposons (these form at least 45% of the human genome). A particular class of retrotransposons are called LINE (long interspersed nuclear elements) and are a form of non-LTR retrotransposons. These are important in DNA shuffling, i.e. in rearranging DNA and helping it maintain its plasticity. Thus, it may be possible to use existing transposons (including LINE) to activate parts of DNA that may have relevance in the ELPIs theory (i.e. activate genes that may code for putative immortality proteins). It has been shown that stem cells contain activated retrotransposon LINE elements and this may be the basis of their self-renewal properties.

 

Certain transposons in bacteria carry genes that express not only their own transposase but also confer antibiotic resistance. It just happens that this resistance is not beneficial to us. But genes that confer resistance to, say, oxidation or glycation will be beneficial. So, if this is the case, it may not be impossible to use transposons carrying genes that prove beneficial (as they confer resistance which may be useful to us). 

 

Also, on occasions LINE1 insert a copy of mDNA but this is not expressed. If we could artificially force it to express what would be the result? It is known that certain transposons are intact and capable of moving within the DNA but are kept inactive by epigenetic mechanisms such as DNA methylation and chromatin remodelling. On the other hand, certain transposons are themselves capable of causing epigenetic silencing. Thus, manipulation of transposon activity may result in useful gene regulation.

 

Transposons can sometimes destroy genes. But if this is the case, they could possibly also destroy ageing-promoting genes. On the other hand, they can also result in the formation of new genes through exon shuffling (the juxtaposition of two previously unrelated exons, through transposition) (Pray L. Transposons:the jumping genes.2008 Nature Education 1(1). These new genes increase genetic diversity. We can thus hypothesize that it may be the case that new genes can be created, which can have benefits in attaining extreme longevity. Retrotransposons can rarely result in non-functional new genes, which nevertheless can become active under certain selective evolutionary circumstances. Some of these genes are found on the X chromosome but their expression ceases during spermatogenesis, However, retrotransposons can re-activate these silent genes and make them functional again.(http://biol.lfl.cuni.ez/ucebnice/en/repetitive_dna.htm).

 

 

Several methods of delivering transposons onto the DNA are being developed. For example, a hybrid vector system has been developed, consisting of an HIV-1 derived lentiviral vector with Sleeping Beauty (SB) transposon and transposase expression cassettes, which allows genomic integration of SB, devoid of the HIV-1 long terminal elements. This resulted in transcripitionally active genes with minimal insertional mutagenesis (Vink CA, Gaspar HB, Gabriel R et al. Sleeping Beauty transposition from nonintegrating lentivirus. Mol Ther 2009 17(7):1197-1204).