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Scientists create a new technique for early detection of colorectal cancer

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Posted June 29, 2015

Scientists at California Institute of Technology have developed a new method to detect colorectal cancer from tissue samples. This technique is already showing promise to be used in clinical settings for the early diagnosis of colorectal cancer in the near future.

Colorectal cancer is the third most prevalent cancer in the world and causes approximately 700,000 deaths every year. Starting treatment earlier increases possibility of survival, which makes new diagnosis technique even more valuable. Image credit: Blausen Medical Communications, Inc. via Wikimedia, CC BY 3.0

Colorectal cancer is the third most prevalent cancer in the world and causes approximately 700,000 deaths every year. Starting treatment earlier increases possibility of survival, which makes new diagnosis technique even more valuable. Image credit: Blausen Medical Communications, Inc. via Wikimedia, CC BY 3.0

Since this type of cancer is one of the most prevalent cancers worldwide and treating it in its early stages holds more promise for survival of the patient, new diagnosis techniques are extremely needed and cannot come soon enough.

In fact, colorectal cancer is the third most prevalent cancer in the world, it causes approximately 700,000 deaths every year. One of the major causes of death is metastasis, which appear because of late detection of the cancer. New technique should enable doctors to detect colorectal cancer earlier and easier. Ariel Furst, one of co-authors of the study, noted that current diagnosis techniques require a colorectal biopsy, which is about 300 milligrams.

This new setup, which is still experimental, only requires “about 500 micrograms of tissue, which could be taken with a syringe biopsy versus a punch biopsy”. This means, new technique is much less invasive, as one microgram is one thousandth of a milligram. It means that new method requires 600 times less tissue than conventional methods.

The research focused on a protein called DNMT1 as a possible indicator of a cancerous transformation. It is a methyltransferase, an enzyme responsible for the addition of a methyl group to one of DNA’s bases. It is a normal process. However, if the process goes awry, it can be an indicator of cancer, especially the development of tumours.

In normal conditions, DNMT1 maintains the normal methylation pattern set in the embryonic stages, copying that pattern from the parent DNA strand to the daughter strand. But in the case of cancer methylation goes into overdrive and causes what is called hypermethylation, which represses the genes that suppress the growth of tumours or express proteins that repair damaged DNA, which, in turn, leads to cancer.

Scientists used this knowledge to test new technique for detecting cancer in early stages. They devised an electrochemical platform to measure the activity of DNMT1 in crude tissue samples. Researchers used two arrays of gold electrodes embedded in Teflon blocks and separated by a thin spacer that formed a well for solution. Strands of DNA were attached to the lower electrodes and scientists added the broken-down contents of a tissue sample to the solution well.

Team gave some time for any DNMT1 in the tissue sample to methylate the DNA and then added a restriction enzyme that severed the DNA if no methylation had occurred. Then a current was applied to lower electrodes and the samples with DNMT1 activity passed the current clear through to the upper electrodes, where the activity could be measured. It seems to be an extremely complicated setup, but scientists say it is easier way for early cancer diagnosis.

Using this method scientists measured DNMT1 activity in 10 pairs of human tissue samples – each pair had tumour and healthy tissue samples. They consistently found higher DNMT1 activity in the tumorous tissue, which should mean that the technique is reliable. However, there was no correlation between cancer and the amount of DNMT1 – it was only the activity of it that indicated the cancer.

Catching cancer as early as possible is the major part of successful recovery of the patient. And this new method of detecting colorectal cancer can play a big role in developing very simple techniques of diagnosis. In fact, scientists say that the platform they created, after some improvements, could help create inexpensive, portable tests that could be used in the home to catch colorectal cancer in its earliest, most treatable stages. In other words, tests could be bought simply in drug stores and people could test themselves easily at the comfort of their own home.

Source: caltech.edu

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