Powerhouse of cells 'hyperactive in cancer'

In collaboration with the Press Association

New US research suggests that the way cancer cells produce energy may be different than previously thought, and that an already available drug could kill tumours by depriving them of their power supply.

Mitochondria are the 'powerhouses' of normal cells - they create chemical energy used to fuel the cell.

It's thought that cancer cells mostly generate energy in a different, more inefficient, process that doesn't use mitochondria, known as the Warburg Effect.

It's been debated for decades how much cancer cells also depend on their mitochondria for their energy.

Earlier work by the same team suggests that the inefficient 'Warburg' energy production actually takes place in the normal cells that surround a tumour, rather than in cancer cells themselves. And this process then provides fuel for mitochondria in cancer cells, feeding the growth and spread of tumours spread.

They've coined this the "Reverse Warburg Effect," the opposite of the existing paradigm.

In the new research, published in the journal Cell Cycle, Professor Michael Lisanti at Thomas Jefferson University took tissues samples from breast cancer patients and showed that that tumour cells have increased mitochondrial activity, whereas other nearby cells do not.

Dr Lisanti said: "We and others have now shown that cancer is a 'parasitic disease' that steals energy from the host - your body - but this is the first time we've shown in human breast tissue that cancer cell mitochondria are calling the shots and could ultimately be manipulated in our favour."

The researchers also suggest that the disease could potentially be tackled by blocking this process with chemicals that interfere with mitochondria, such as metformin, an off-patent generic drug currently used to treat diabetes.

The team also looked at the activity of genes in more than 2,000 human breast cancer samples to compare the activity of mitochondria in cancer cells with their activity in normal cells. 

They found that human breast cancer cells had increased levels of mitochondrial activity, whereas surrounding tissues had little or no mitochondrial activity.

Dr Lisanti said: "Mitochondria are the 'Achilles heel' of tumour cells and we believe that targeting mitochondrial metabolism has broad implications for both cancer diagnostics and therapeutics, and could be exploited in the pursuit of personalised cancer medicine."

Dr Patrick Pollard, a Cancer Research UK cancer metabolism expert at the University of Oxford, said the work showed how important research into cancer energy metabolism was. 

"This study suggests that some breast cancer cells can hijack nutrients from neighbouring cells and metabolise them through their own mitochondria – the powerhouse of most normal cells - giving the cancer a strong growth advantage. 

"Results of studies like this vary at the moment. But this work highlights the importance for us to keep increasing our understanding of metabolism in normal cells compared to cancer cells, which may help to define new routes to therapy for some breast cancers,” he added.

Copyright Press Association 2011

References

  • Whitaker-Menezes D, & et al. (2011). Hyperactivation of oxidative mitochondrial metabolism in epithelial cancer cells in situ: Visualizing the therapeutic effects of metformin in tumor tissue Cell Cycle, 10 (23), 4047-4064 : 10.4161/cc.10.23.18151