London: Drug-resistant cancer cells act like cars in a traffic jam -- when one route is blocked, they find an alternative path and continue to grow, scientists say.
The discovery may help extend the usefulness of drugs by targeting drug resistance in tumours, the researchers said.
An international team which was studying a cancer drug, called cetuximab, found that cancerous cells use a trick to evade treatment -- they change their route when one way is blocked just like cars in a traffic jam, the BBC reported.
Cetuximab, used to treat colorectal, head and neck and some lung cancers, targets a protein called epidermal growth factor receptor (EGFR), which drives tumour growth.
Experiments showed that when patients took cetuximab, the cancerous cells replaced the EGFR route with one involving a different protein -- ERBB2 -- and continued to grow.
Lead researcher Dr Pasi Janne, of the Dana-Farber Cancer Institute in Boston, said: "ERBB2 activates a critical signalling pathway that is not normally blocked by cetuximab, and in this way subverts cetuximab`s function.
"Because ERBB2 isn`t affected by cetuximab, this is an easy way for cancers to become resistant to the drug."
The researchers said several drugs which target ERBB2 had already been approved so "the findings from the current study can be used to design potential clinical therapies".
However, they cautioned that there are likely to be other ways that cancers can develop resistance.
Henry Scowcroft, science information manager at Cancer Research UK, said: "Unfortunately, patients` tumours can become resistant to treatment, and understanding why this happens is a major challenge in cancer research.
"This new study is a great example of how researchers are uncovering the molecular tricks cancer cells use to evade treatment, and finding out how to stop them doing so.
"Research like this gives us tremendous optimism that we are on the cusp of a real revolution in cancer, although there`s a lot more work to do to make this a reality."
The new study was published in the Science Translational Medicine journal.