Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How vitamin C stops the big 'C'

11.09.2007
Nearly 30 years after Nobel laureate Linus Pauling famously and controversially suggested that vitamin C supplements can prevent cancer, a team of Johns Hopkins scientists have shown that in mice at least, vitamin C - and potentially other antioxidants - can indeed inhibit the growth of some tumors ¯ just not in the manner suggested by years of investigation.

The conventional wisdom of how antioxidants such as vitamin C help prevent cancer growth is that they grab up volatile oxygen free radical molecules and prevent the damage they are known to do to our delicate DNA. The Hopkins study, led by Chi Dang, M.D., Ph.D., professor of medicine and oncology and Johns Hopkins Family Professor in Oncology Research, unexpectedly found that the antioxidants’ actual role may be to destabilize a tumor’s ability to grow under oxygen-starved conditions. Their work is detailed this week in Cancer Cell.

“The potential anticancer benefits of antioxidants have been the driving force for many clinical and preclinical studies,” says Dang. “By uncovering the mechanism behind antioxidants, we are now better suited to maximize their therapeutic use.”

“Once again, this work demonstrates the irreplaceable value of letting researchers follow their scientific noses wherever it leads them,” Dang adds.

... more about:
»DNA »Dang »HIF-1 »Vitamin »damage »free radicals

The authors do caution that while vitamin C is still essential for good health, this study is preliminary and people should not rush out and buy bulk supplies of antioxidants as a means of cancer prevention.

The Johns Hopkins investigators discovered the surprise antioxidant mechanism while looking at mice implanted with either human lymphoma (a blood cancer) or human liver cancer cells. Both of these cancers produce high levels of free radicals that can be suppressed by feeding the mice supplements of antioxidants, either vitamin C or N-acetylcysteine (NAC).

However, when the Hopkins team examined cancer cells from cancer-implanted mice not fed the antioxidants, they noticed the absence of any significant DNA damage. “Clearly, if DNA damage was not in play as a cause of the cancer, then whatever the antioxidants were doing to help was also not related to DNA damage,” says Ping Gao, Ph.D, lead author of the paper.

That conclusion led Gao and Dang to suspect that some other mechanism was involved, such as a protein known to be dependent on free radicals called HIF-1 (hypoxia-induced factor), which was discovered over a decade ago by Hopkins researcher and co-author Gregg Semenza, M.D., Ph.D., director of the Program in Vascular Cell Engineering. Indeed, they found that while this protein was abundant in untreated cancer cells taken from the mice, it disappeared in vitamin C-treated cells taken from similar animals.

“When a cell lacks oxygen, HIF-1 helps it compensate,” explains Dang. “HIF-1 helps an oxygen-starved cell convert sugar to energy without using oxygen and also initiates the construction of new blood vessels to bring in a fresh oxygen supply.”

Some rapidly growing tumors consume enough energy to easily suck out the available oxygen in their vicinity, making HIF-1 absolutely critical for their continued survival. But HIF-1 can only operate if it has a supply of free radicals. Antioxidants remove these free radicals and stop HIF-1, and the tumor, in its tracks.

The authors confirmed the importance of this “hypoxia protein” by creating cancer cells with a genetic variant of HIF-1 that did not require free radicals to be stable. In these cells, antioxidants no longer had any cancer-fighting power.

Nick Zagorski | EurekAlert!
Further information:
http://www.jhmi.edu
http://www.cancercell.org/
http://www.hopkinsmedicine.org/hematology/faculty_staff/dang.html

Further reports about: DNA Dang HIF-1 Vitamin damage free radicals

More articles from Life Sciences:

nachricht Polymers Based on Boron?
18.01.2018 | Julius-Maximilians-Universität Würzburg

nachricht Bioengineered soft microfibers improve T-cell production
18.01.2018 | Columbia University School of Engineering and Applied Science

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Polymers Based on Boron?

18.01.2018 | Life Sciences

Bioengineered soft microfibers improve T-cell production

18.01.2018 | Life Sciences

World’s oldest known oxygen oasis discovered

18.01.2018 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>