London, Sep 30 (IANS): Researchers from the University of Liverpool have found that the human ageing processes may hinder cancer development.

Ageing is one of the biggest risk factors for cancer. However, the biological mechanisms behind this link are still unclear, the study said in a paper published in the journal Aging Cell.

In an effort to better understand the biological mechanisms researchers compared how genes differentially expressed with age and genes differentially expressed in cancer among nine human tissues.

Normally, a healthy cell can divide in a controlled manner. In contrast, senescent or 'sleeping' cells have lost their ability to divide.

As we age, the number of senescent cells in our bodies increase, which then drive many age-related processes and diseases.

"Our results highlight the complex relationship between ageing, cancer and cellular senescence and suggest that in most human tissues ageing processes and senescence act in tandem while being detrimental to cancer," said study researcher Joao Pedro De Magalhaes from the University.

Genetic mutations triggered by things such as UV exposure can sometimes cause cells to replicate uncontrollably -- and uncontrolled cell growth is cancer.

Cells are often able to detect these mutations and in response go to sleep to stop them dividing.

The researchers found that in most of the tissues examined, ageing and cancer gene expression 'surprisingly' changed in the opposite direction.

These overlapping gene sets were related to several processes, mainly cell cycle and the immune system.

Moreover, cellular senescence changed in the same direction as ageing and in the opposite direction of cancer signatures.

The researchers believe the changes in ageing and cellular senescence might relate to a decrease in cell proliferation, while cancer changes shift towards an increase in cell division.

"One of the reasons our bodies have evolved to have senescent cells is to suppress cancers. But then it seems that senescent cells accumulate in aged human tissues and may contribute to ageing and degeneration," De Magalhaes said.

"Our work challenges the traditional view concerning the relationship between cancer and ageing and suggest that ageing processes may hinder cancer development," De Magalhaes added.