New system for accurate telomere profiling in less than 3 hours

Date:
August 25, 2020
Source:
National University of Singapore
Summary:
A novel assay can be used to rapidly determine telomere
dysregulation in cancers and age-related diseases in clinical
settings. This helps clinicians to make faster diagnosis and plan
targeted treatments for patients.



FULL STORY ==========================================================================
The plastic tips attached to the ends of shoelaces keep them from fraying.

Telomeres are repetitive DNA (deoxyribonucleic acid) sequences that
serve a similar function at the end of chromosomes, protecting its
accompanying genetic material against genome instability, preventing
cancers and regulating the aging process.


==========================================================================
Each time a cell divides in our body, the telomeres shorten, thus
functioning like a molecular "clock" of the cell as the shortening
increases progressively with aging. An accurate measure of the quantity
and length of these telomeres, or "clocks," can provide vital information
if a cell is aging normally, or abnormally, as in the case of cancer.

To come up with an innovative way to diagnose telomere abnormalities,
a research team led by Assistant Professor Cheow Lih Feng from the NUS Institute for Health Innovation & Technology (iHealthtech) has developed
a novel method to measure the absolute telomere length of individual
telomeres in less than three hours. This unique telomere profiling method
can process up to 48 samples from low amounts (<1 ng) of DNA.

Their work was published in the journal Science Advances on 21 August
2020.

"Our innovation could greatly enhance the speed of diagnosis and
simultaneously provide critical telomere information for age-related
diseases and cancers.

Such a clinically reliable tool that is able to provide accurate telomere profiling will allow for precision therapy and targeted treatments for patients," explained Asst Prof Cheow, who is also from the NUS Department
of Biomedical Engineering.

Overcoming the limitations of conventional telomere tests Conventional
methods for telomere measurements in clinical settings are often
time-consuming and require skilled operators. These methods are also
lacking in precise information on individual telomere lengths and
quantities required to accurately diagnose, or determine telomere abnormalities.



==========================================================================
To overcome the major technical impediments in performing telomere
profiling, Asst Prof Cheow and his team have developed a unique system
called Single Telomere Absolute-length Rapid (STAR) assay.

Using this method, individual telomere molecules are first distributed
into thousands of nanolitre chambers in a microfluidic chip. Real-time polymerase chain reaction (PCR) of single telomere molecules is then
performed across all the chambers in a massively parallel manner. The
PCR amplification kinetics in each nanolitre chamber reflects the
telomere repeat number, which directly correlate to the length of a
single telomere molecule.

Using the STAR assay, the researchers can accurately determine the
telomere maintenance mechanism in cancer cells and obtain a high level
of detailed information in the measurements. Patients who have cancers activated by the Alternative Lengthening of Telomere (ALT) pathway --
such as certain sarcomas (cancer of connective tissues) and gliomas
(cancer of brains) -- are often shown to have poor prognosis that is
linked to longer than average telomere length and a high percentage of critically short telomeres. In addition, their cancer cells also were
found to possess extra copies of telomere molecules.

To test the invention, the NUS iHealthtech team collaborated with Dr Amos
Loh from the Department of Paediatric Surgery at KK Women's and Children's Hospital (KKH). The team chose to work with KKH to validate the assay as telomere alteration mechanisms like ALT are best studied in tumours like sarcomas, and neuronal tumours like gliomas and neuroblastoma that have a higher incidence among children. The validation has proven the STAR assay
to be effective in diagnosing the ALT status in paediatric neuroblastoma,
which can serve as a useful prognosis indicator for this cancer.

Cancer cells utilise a modified mechanism to abnormally modify and
maintain the length of their telomeres, as a means to allow them to
grow continually.

Mechanisms like ALT are exploited particularly by cancers like
neuroblastoma.

Neuroblastoma is a cancer that arises from nerves in various parts of the
body and is the most common solid malignant tumour in children. It is also responsible for a disproportionate number of childhood deaths from cancer.



========================================================================== "Previously less recognised in patients, telomere abnormalities
like ALT have been recently identified to be a new risk marker in neuroblastoma. Since neuroblastoma with telomere abnormalities have
poorer outcomes, this new method of measuring telomeres can now
facilitate simpler and more rapid identification of ALT in patients
to more accurately define their disease prognosis," said Dr Amos Loh,
Senior Consultant, who is from KKH's Department of Paediatric Surgery.

The development of the STAR assay is supported by the National Medical
Research Council.

Enabling effective treatment strategies for patients Asst Prof
Cheow shared, "The combination of rapid workflow, scalability and single-molecule resolution makes our system unique in enabling the
use of telomere length distribution as a biomarker in disease and population-wide studies. It will be particularly useful for diagnosing
telomere maintenance mechanisms within clinical time scales, to determine personalised, therapeutic or preventive strategies for patients."
The NUS iHealthtech team is looking to extend their research and apply
the STAR assay platform for use in hospital settings, to facilitate the diagnosis of aging-related diseases.


========================================================================== Story Source: Materials provided by
National_University_of_Singapore. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Yongqiang Luo, Ramya Viswanathan, Manoor Prakash Hande, Amos
Hong Pheng
Loh, Lih Feng Cheow. Massively parallel single-molecule telomere
length measurement with digital real-time PCR. Science Advances,
2020; 6 (34): eabb7944 DOI: 10.1126/sciadv.abb7944 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200825110748.htm

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