In a study of ovarian cancer cells taken from patients, scientists from Georgia Institute of Technology have confirmed that metastasizing cancer cells have a different molecular structure from primary tumor cells and display genetic signatures consistent with epithelial-to-mesenchymal transition. Although histologic examination of 14 matched sets of primary ovary and metastatic omentum ovarian tissue taken from 7 cancer patients found no morphologic distinction between the matched sets of primary and metastatic samples, gene expression profiling (Affymetrix, U133) clearly distinguished two classes of metastatic samples, reported the researchers.
One class displayed expression patterns statistically indistinguishable from primary samples isolated from the same patients, while a second class displayed expression patterns significantly different from primary samples, said the researchers. Further analysis focusing on genes previously associated with epithelial-to-mesenchymal transition clearly distinguished the primary from metastatic samples in all but one patient.
The study results were published in the Journal of Ovarian Research.1
New Chemotherapies Needed
Although previous laboratory studies in cell cultures and animals suggested that metastasizing cancer cells undergo a major molecular change as they leave the primary tumor site and travel to distant sites, making them more resistance to chemotherapy that is effective on the primary tumor, there was no confirmation that this epithelial-to-mesenchymal transition process took place in human tissue samples.
The researchers concluded that their results are consistent with a role of epithelial-to-mesenchymal transition in most, if not all, ovarian cancer metastases and demonstrate that identical morphologies between primary and metastatic cancer samples are insufficient to negate a role of epithelial-to-mesenchymal transition in the metastatic process.
In a statement, Benedict Benigno, MD, one of the study authors and Director of Gynecological Oncology at Northside Hospital in Atlanta, said, “These results clearly indicate that metastasizing ovarian cancer cells are very different from those comprising the primary tumor and will likely require new types of chemotherapy if we are going to improve the outcome of these patients.” ■
Disclosure: For full disclosures of the study authors, visit www.ovarianresearch.com.
1. Lili LN, Matyunina LV, Walker LD, et al: Molecular profiling supports the role of epithelial-to-mesenchymal transition (EMT) in ovarian cancer metastasis. J Ovarian Res. July 10, 2013 (early release online).