A protein called ABCB5 in colorectal cancers that increases treatment resistance and recurrence of the tumour has been identified by scientists at the Children's Hospital Boston.
The results indicated that eliminating ABCB5-expressing cells is crucial for successful colorectal cancer treatment.
The researchers studied ABCB5 expression in both normal and cancerous colorectal tissue specimens and discovered that it is present at levels 23 times greater in cancerous tissue than in healthy colorectal tissue.
To understand ABCB5's role in treatment resistance, the team examined biopsies gathered from colorectal cancer patients both before and after treatment with 5-fluorouracil (5-FU), a standard chemotherapeutic for this tumor.
They found that the percentage of cells expressing ABCB5 increased more than five fold after treatment.
Using a mouse model of colorectal cancer, the researchers also found that cells expressing ABCB5 were markedly resistant to 5-FU.
Knocking down ABCB5 expression both blocked the growth of these cells and restored their sensitivity to the drug, showing that ABCB5 is not only a marker of treatment resistance but actually drives it.
The study was reported online in the journal Cancer Research on June 7, 2011.