Australasian Science: Australia's authority on science since 1938

Cancer Cause Also a Cure?

By Stephen Luntz

Patients with colorectal cancer show highly varied responses to chemotherapy and radiotherapy. The Garvan Institute is investigating the possibility that a gene called MCC might explain the differences.

“We’ve shown that MCC has an important role to play in a well-known phenomenon known as the DNA damage response,” says Dr Laurent Pangon. “Every cell in the body is regularly exposed to DNA damage from things like toxins, viruses or radiation.”

MCC is one of the genes that play a role in recognising DNA damage. “We know that 50% of our patient cohort had tumours with a defective MCC gene, which causes lack of expression,” Pangon says. “We have shown in cell lines that a shortage of MCC impairs the way that cells respond to damage. Therefore, this could give early tumours an advantage, allowing cancer to develop.”

However, Pangon and colleague Dr Maija Kohonen-Corish think that the lack of expression of MCC may not be all bad. “We believe that these patients might be more responsive to radiotherapy or some types of chemotherapy,” Pangon says. “That is because those therapies kill cancer cells by inducing DNA damage – and if the DNA damage response of the tumour is already defective, the therapies may work better.”

Pangon and Kohonen-Corish have yet to confirm the role of MCC in response to therapy, but Pangon says that if their theory proves sound then those who are unlikely to respond to treatment might at least be spared the side-effects, while in some cases alternatives might be found. The pair has established a large cohort of patients to study, but Pangon says that the numbers having each sort of treatment may not be large enough for definitive conclusions so they are seeking further subjects.

“We are not sure if MCC has a role in other cancers but we know that the integrity of the DNA damage pathway is important in the occurrence and treatment of other cancers, including breast cancer,” Pangon says. It is possible that in other cases the absence of a gene may allow cancer to occur but also increase the chances of successful treatment.