“Jumping Genes” may hold the Key to Curing Cancer

Genetic mutations within the DNA of our cells (which is essentially the genetic code governing the function of a cell) cause alterations that may change the entire nature of the cell. When such cells begin to multiply without inhibitions or control, it develops into cancer. This unbounded division can spread into different parts of the body and essentially invade healthy cells, preventing the body from functioning properly.

These genetic changes can affect various facets of a cell’s body. Some types remove a cells inhibitions against unbridled growth while others may alter the structure of important proteins, destroying their ability to function and keep the cells in proper shape.

Such mutations can be triggered by a number of environmental factors such as exposure to ultraviolet radiation (which is why the ozone hole is considered such a big deal) or it may be a purely spontaneous event during cell division where something goes wrong.

Some cancers also have a hereditary propensity: the ability to be passed from parent to child: Not the cancer itself but the cells with the potential to develop cancer.

What are Jumping Genes?

Jumping Genes are a fancy name for Transposable Elements or Transposons; sequences within our cells’ DNA that have the capacity to “jump” from one location to another within the genome.

Since their discovery, they were mostly dismissed by scientists and considered as “junk DNA”. Essentially unnecessary volume of DNA sequences that serves no purpose. However, recently, some stunning possibilities have come to light which may turn that perception on its head entirely.

Discovery

Barbara McClintock was an American Scientist and a Cytogeneticist who devoted an enormous amount of time to the study of chromosomes within Maize. It allowed her to develop techniques to visualize the chromosomes and she was also the one who theorized the meiotic process of genetic recombination.

In the 1940’s, she discovered the concept of transposition: a quality that Jumping genes exhibit. She developed extensive theories and attempted to perform demonstrations to show how these genes may be involved in inhibiting or allowing the expression of genes in the phenotype: that is the physical expression of a gene.

While her research on Transposable elements was initially met with skepticism by the scientific community, later the tide turned as many other discoveries were made, giving validation to her theories of genetic change and regulation.

In 1965, McClintock was the first person to suggest that these mobile elements might play a role in the regulation of gene expression.

Roy Britten and Eric Davidson further complimented this by adding that aside from regulating gene expression, TE’s might also play a role in distinguishing cell types, seeing as how all of our cells contain essentially the same DNA, yet are specialized in vastly different ways.

Superfamily of Transposons

Among distantly related taxonomic groups or species, research has found that Transposons are actually conserved. This indicates that there has to be some biological value to them. Otherwise there would be no reason for cells to conserve that information.

Drivers of Tumor Growth?

When it comes to cancer research, what researchers do is rifle through the genome in an attempt to locate altered sequences: Sequences where the DNA has mutated. Since “Jumping genes” until now were overlooked entirely in the sequencing process because they were considered to be Junk DNA, it has now been found that they are important drivers of tumor growth in many types of cancers.

Recent experiments indicated that these jumping genes, which are basically switches for gene expression, drive tumor growth by forcing cancer genes to remain switched on.

This breakthrough was conducted by scientists at the Washington University School of Medicine in St. Louis.

As part of the Cancer Genome Atlas Project, a total of 129 different Jumping genes were located by analysis of 7,769 tumor samples, collected from 15 different kinds of cancer. The jumping genes were found to have influence over 106 different cancer genes.

The tumor cells were collected from the brain, lung, skin, prostate, breast and colon. Among the total number of samples, it was found that in 3,864 samples, the jumping genes played an active role by acting as on-switches. This means nearly half of the total number of samples examined showed had transposons involved in driving tumor growth.

According to Ting Wang, Professor of Medicine in the Department of Genetics, typical genome sequencing is completely blind to the influence of jumping genes in cancer tumor growth.

Ting Wang further elaborated that the role jumping genes play in different types of cancers is not equal. They are more active in propagating some types of cancer tumors than others. He also added that the tumors influenced by these Transposable elements tended to be a lot more aggressive which if known in advance might enable doctors to attempt a more aggressive form of treatment.

The Jumping genes present in each type of tumor varied greatly. In lung squamous cell carcinoma samples, nearly 87 percent were prey to jumping genes, while in Gliomas only 12 percent had any influence from any kind of jumping genes.  One jumping gene was found to be specific to Melanoma.

FUTURE PROSPECTS

The obvious prospect of this breakthrough is obviously the discovery of new avenues for cancer treatment with a greater focus of the regulation of genes.

How the regulation of such genes can be controlled is a question yet to be answered. One of the prominent features of mutated DNA sequences which were switched on by jumping genes was the fact that it was in an open shape, leaving it more open to the influence of such transposons. This means that the section of the genome had lost some of its regulation properties and was open to manipulation.

The jumping genes act on such DNA and force them remain switched on.

If these sections of the genome are shut off then the jumping would not be able to keep them switched on which may essentially inhibit the growth of any tumor.

As already mentioned before, the study can assist doctors in making better treatment decisions for various types of cancers since cancerous tumors which are forcibly switched on by Jumping Genes are a  lot more aggressive than tumors which are not influenced by these transposable elements.

This isn’t the endgame for Transposable elements. There is still a lot of mystery to these sequences in our DNA and what purpose they actually serve. We are gradually finding out that there is more to them than meets the eye and they may hold the key to many more breakthroughs in the field of medical science.

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