BPA may up risk of breast cancer

PTI| Updated: Mar 07, 2014, 14:44 PM IST

Washington: BPA, a compound widely used in plastics such as food storage containers, may contribute to breast cancer by disrupting the genes that prevent the tumour from growing, Indian-origin researchers have found.

Researchers said their new study brings them closer to understanding how the commonly used synthetic compound bisphenol-A, or BPA, may promote breast cancer growth.

Subhrangsu Mandal, associate professor of chemistry/biochemistry, and Arunoday Bhan, a PhD student in Mandal's lab at the University of Texas at Arlington, looked at a molecule called RNA HOTAIR.

HOTAIR is an abbreviation for long, non-coding RNA, a part of DNA in humans and other vertebrates.

HOTAIR does not produce a protein on its own but, when it is being expressed or functioning, it can suppress genes that would normally slow tumour growth or cause cancer cell death.

High levels of HOTAIR expression have been linked to breast tumours, pancreatic and colorectal cancers, sarcoma and others, researchers said.

They found that when breast cancer and mammary gland cells were exposed to BPA in lab tests, the BPA worked together with naturally present molecules, including oestrogen, to create abnormal amounts of HOTAIR expression.

"We can't immediately say BPA causes cancer growth, but it could well contribute because it is disrupting the genes that defend against that growth," said Mandal, corresponding author on the research paper.

"Understanding the developmental impact of these synthetic hormones is an important way to protect ourselves and could be important for treatment," he said.

"We were surprised to find that BPA not only increased HOTAIR in tumour cells but also in normal breast tissue," said Bhan.

BPA has been widely used in plastics, such as food storage containers, the lining of canned goods and, until recently, baby bottles.

It belongs to a class of endocrine disrupting chemicals, or EDCs, which have been shown to mimic natural hormones.

These endocrine disruptors interfere with hormone regulation and proper function of human cells, glands and tissue.

Previous studies have linked BPA to problems with reproductive development, early puberty, obesity and cancers.

Under normal circumstances, oestrogen regulates HOTAIR, turning its expression on and off through interaction with molecules called oestrogen-receptors, or ERs, and oestrogen receptor-coregulators, or ER-coregulators.

The new study found that BPA disrupts the normal function of the ERs and the ER-coregulators when oestrogen was present and when it wasn't, potentially implicating it in tumour growth in a variety of cancers.