Stem cell-like origins of ovarian cancer identified

The source of stem cell-like cells that can give rise to ovarian cancer in mice has been found, reports a study in the journal Nature. The findings may be important in understanding the origins of the most common form of human ovarian cancer, if the same cells can be found in women.

'Sources of cells that make ovarian tumours are not really known', said Dr Grigori Enikolopov of Cold Spring Harbour Laboratory, New York, who co-led the study. 'We demonstrated that a stem cell population sits in a portion of the ovary called the hilum [...] and that these cells are easily transformed into tumor cells'.

Ninety percent of human ovarian cancers arise from the ovarian epithelium - a layer of cells that line the ovaries. However the specific cells responsible for this type of cancer have been difficult to pinpoint, as most patients are diagnosed at advanced stages of the disease.

Researchers discovered cells in the hilum region of the ovaries in mice that showed stem cell-like properties and the ability to repair the ovarian epithelium when it ruptures during ovulation.

The idea that mutated stem cells can seed cancers is known as the cancer stem cell hypothesis. Building on this theory, the team studied the stem cells of the hilum and found they could be transformed into tumour cells by inactivating two genes known to often be mutated in human ovarian cancer. The genetically manipulated stem cells were transplanted into eight mice; seven of which went on to develop ovarian tumours.

Professor Alexander Nikitin of Cornell University, New York, who co-led the study, told Cancer Research UK (CRUK): 'We now know where these cells are located in mice, so we can look in humans in those areas'.

If these stem cells can be found in women, 'it could have important implications, particularly in explaining why the oral contraceptive pill lowers the risk of this cancer developing', added Dr James Brenton, an ovarian cancer researcher based at the CRUK Cambridge Research Institute, who was not involved in the study. 'If we could understand that, we could be on the way to developing other drugs to prevent the disease - a very exciting prospect'.