Chemotherapy is a key part of the standard treatment regimen for triple-negative breast cancer patients whose cancer lacks expression of oestrogen and progesterone receptors and the human epidermal growth factor receptor 2 (HER2).

While many patients respond well to chemotherapy, a significant fraction of those treated are resistant to chemotherapy or will develop recurrent tumours that are chemoresistant.

In this issue of JCI Insight, a research team led by Mercedes Rincon at the University of Vermont identified low expression of methylation-controlled J protein (MCJ) as a marker of poor response to chemotherapy.

The authors say "our study provides evidence that low expression of MCJ protein is associated with poor response to chemotherapy in human breast cancer, identifying MCJ as a new marker to predict chemotherapy response."

In a prospective study of 62 breast cancer patients, they demonstrated that MCJ expression correlates with pathological and clinical responses to neoadjuvant chemotherapy.

Further, by analysing a large clinical data set from breast cancer repositories, they found that breast cancer patients with low-MCJ-expressing tumours had reduced relapse-free survival.

Lastly, they examined a mammary tumour mouse model and showed that mice deficient in MCJ had larger tumours and increased chemoresistance.

Their study suggests that MCJ may be useful as a marker of chemotherapy response and could be a potential therapeutic target for breast cancer treatment.

Source: JCI Insight