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Human tissue kallikreins (hKs) are aberrantly expressed in many cancer types, including ovarian cancer. All of the hKs are being evaluated as potential biomarkers for cancer diagnosis and/or prognosis. Although there is evidence implicating some hKs in tumor suppression and others in tumor promotion, there had not been a systematic survey of the effects of multiple hKs in a series of cancer cell lines. In this study, we examined the expression of 6 hKs (hK5, 6, 8,10, 13, 14) in five ovarian cancer cell lines. These cell lines were also characterized by their ability to invade through matrigel and grow in soft agar. In addition, hK expression was correlated to the survival times of nude mice inoculated intraperitoneally with the respective cell lines. Our results showed that there was no detectable kallikrein expression from ES-2 and OVCA429, while the other three cell lines, Caov-3, OVCAR-3 and C13, were found to express multiple kallikreins. Both hK negative cell lines, ES-2 and OVCA429, were able to form colonies in soft-agar and were highly invasive through Matrigel. In contrast, none of three kallikrein-expressing cell lines were able to demonstrate anchorage independent growth or invade through Matrigel. Combined with recently published xenograft data in mice, the strong association between the less aggressive tumor phenotype and the expression of hKs in ovarian cancer cells suggests that some of the kallikreins may be involved in inhibiting tumor development and, therefore, represent therapeutic opportunities in the treatment of ovarian cancer.

[Proc Amer Assoc Cancer Res, Volume 47, 2006]