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| |  AACR: Another Link Between Cox-2 Expression and Breast Cancer By Cameron Johnston Special to DG News
NEW ORLEANS, LA -- March 29, 2001 -- A direct connection exists between the over-expression of cycloxygenase-2 (COX-2) and HER2/Neu, a receptor protein tyrosine kinase that has been associated with a poor prognosis in women with breast cancer, research shows. Although the study was small and involved only 25 women, 15 who were HER2/Neu-positive and 10 who were HER2/Neu-negative, the findings are yet another indication of the importance of COX-2 expression in a number of cancers, including colon and gynecologic cancers. The study results, which were presented at the annual meeting of the American Association for Cancer Research (AACR) on Wednesday (March 28) raise the possibility that COX-2 over-expression may be what researchers term a "down-stream target" for HER2/Neu-mediated tumorogenesis. That is to say that for women who have HER2/Neu-positive breast cancer (approximately 30 percent of all breast cancers over-express this protein), COX-2 might be similarly over-expressed. This finding leaves the door open to studies that would determine whether treatment with COX-2 inhibitors might somehow affect tumor progression. In the study presented at the AACR it was found that two-thirds of the women who had either infiltrative ductal carcinoma or lobular carcinoma over-expressed both COX-2 and HER/2. Eighty percent of women with mucinous carcinoma were both HER2- and COX2-negative, and only 20 percent of the women with this form of cancer were HER2-negative, but over-expressed COX2. At the same time, only 16 percent of the women with infiltrative ductal carcinoma who were estrogen receptor positive also expressed COX-2, while three-quarters of those who had lobular carcinoma were estrogen receptor-positive and over-expressed COX-2. While the numbers were small, this means that 10 out of 12 women with either ductal, lobular or infiltrating cancers over-expressed both COX-2 and HER2/Neu. COX-2 is over-expressed in HER2/Neu positive cancers regardless of tumor type, concluded principal investigator Dr. Janet Harmon, an investigator with Pharmacia Corp, which funded the research. Furthermore, HER2/Neu-negative cancers seem to express COX-2 less frequently than those that are HER2-positive. The correlation between estrogen receptor status and COX2 expression remains to be seen, although there is a correlation between estrogen receptor status and HER2/Neu expression. The presence of the HER2/Neu protein and COX2 were expressed on the same cells, so this is not a case of some cells expressing one, but not the other, the investigators noted. Co-investigators in the study were based at WCP Pathology Inc., and New York Presbyterian Hospital, both in New York City.
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