A protein has been discovered that could suppress the growth of breast tumours, British researchers said last night.
Researchers at the University of Birmingham have pin-pointed the role of the Proline-Rich Homeodomain protein (PRH), which controls and regulates when genes are switched on or off.
Dr Padma Sheela Jayaraman, of the university’s Institute of Cancer and Genomic Sciences, said there was a lack of understanding about PRH’s role but that databases showed that the activity of the PRH gene decreased in large number of breast cancer patients with a poor prognosis.
However, because protein levels had not been recorded, it was not known if the amount of PRH protein was also lower in those patients.
For this study, which is published in the latest edition of Oncogenesis, the research team used a special staining process on breast cancer tissue removed during biopsy to observe the levels and location of PRH proteins in breast cancer cells.
They found changes in PRH proteins in tumour cells compared to normal cells that were consistent with the decreased activity of the PRH gene in the public database.
They also discovered that when PRH protein levels are reduced in a breast tumour, the cells are more able to divide, speeding up the progression of the tumour. In addition, the team identified some of the genes that are regulated by PRH and which specifically contribute to the increased cell division.
"We made the significant finding that high levels of PRH actually blocked the formation of the tumours, therefore our data suggests that PRH can block tumour formation in some breast cancers," said Dr Jayaraman.
"We propose that monitoring PRH protein levels or activity in patients with breast cancer could be particularly important for assessing their prognosis.
"In addition, since PRH is known to be important in multiple cell types, this work has important implications for other types of cancer.
"We are now working to investigate the importance of PRH in prostate cancer and in cancer of the bile duct, a type of liver cancer."
Kershaw et al. Proline-Rich Homeodomain protein (PRH/HHEX) is a suppressor of breast tumour growth. Oncogenesis June 2017; doi: 10.1038/oncsis.2017.42
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