Lysophospholipids increase interleukin-8 expression in ovarian cancer cells

Objectives. We have previously described that bioactive lysophospholipids-l ysophosphatidic acid (LPA), sphingosine l-phosphate (S1P), and sphingosylph osphorylcholine (SPC)-are present in ascitic fluids from patients with ovar ian cancer. To understand the role of these lipids in ovarian cancer, we in vestigated the effects of these lipids on interleukin-8 (IL-8) production i n ovarian cancer cells. IL-8 is a proinflammatory and proangiogenic factor, which is potentially involved in ovarian cancer development. Methods. The Clontech PCR-Select cDNA subtraction method (Clontech Laborato ries, Inc., Pale Alto, CA) was used to identify genes potentially regulated by LPA in HEY and OCC1 ovarian cancer cell lines. Northern blot analysis w as used to confirm and examine IL-8 mRNA regulation by lysolipids. Enzyme-l inked immunosorbent assay (ELISA) was used for detecting secreted IL-8, Results. We describe here that LPA, S1P, and SPC increased mRNA levels (2- to 7-fold) and protein secretion (2- to 12-fold) of IL-8 from ovarian cance r cells (HEY, OCC1, and SKOV3) in vitro. These regulations were both dose- and time-dependent. All three lipids increased the stability IL-8 mRNA in H EY cells. In contrast to malignant ovarian cancer cells, immortalized human ovarian epithelial cells did not respond to any of these lipids to increas e the secretion of IL-8, although these cells secreted similar basal levels of IL-8 (310 pg/ml/10,000 cells). Two breast cancer cell lines (MCF7 and T 47D) secreted lower basal levels of IL-8 (48-80 pg/ml/10,000 cells), compar ed with ovarian cancer cells (200-500 pg/ml/10,000 cells). MCF7 cells respo nded to LPA, but not S1P and SPC, by increasing the secretion of IL-8, T47D and MCF10A, an immortalized breast cell line, did not respond to LPA, S1P, or SPC to increase IL-S secretion. Conclusions. LPA, S1P, and SPC regulate the mRNA and protein levels of the proinflammatory and proangiogenic factor IL-8 in ovarian cancer cells, The pathological significance of these regulations in ovarian cancer remains to be further investigated. (C) 2001Academic Press.