Suppression of ovarian carcinoma cell growth in vivo by the interferon-inducible plasma membrane protein, phospholipid scramblase 1.
Phospholipid scramblase 1 (PLSCR1) is an IFN-inducible, endofacial plasma membrane protein that has been proposed to mediate accelerated transbilayer movement of plasma membrane phospholipids in cells exposed to elevated cytoplasmic [Ca (2+)]. The marked transcriptional up-regulation of this gene by IFN in a wide variety of cell types suggested that PLSCR1 might also contribute to biological effects associated with IFN. To study the potential contribution of cellular PLSCR1 to the antiproliferative and tumor-suppressive activities of IFN, PLSCR1 cDNA was stably expressed in the human ovarian cancer cell line HEY1B, and the growth of these cells was compared with matched vector transfected controls both in vitro and in vivo. Whereas we detected no difference in either growth rate or morphology between PLSCR1-transfected cells and vector controls during in vitro culture in serum, when these cells were implanted s.c. into athymic nude mice, we observed a marked suppression of tumor development from cells transfected to express elevated levels of PLSCR1. Tumors from the PLSCR1-transfected cells were greatly reduced in size, showed increased infiltration of leukocytes and macrophages, and appeared to undergo differentiation to a more uniform and spindle-shaped morphology that markedly contrasted the highly undifferentiated and pleiomorphic cell shape normally observed for HEY1B cells in vitro or for vector-transfected control HEY1B cells both in vitro and in vivo. These data suggest that the up-regulation of PLSCR1 expression in tumor cells exposed to IFN may contribute to the observed tumor-suppressive action of this cytokine.
Silverman
Robert H
RH
Department of Cancer Biology, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA. silverr@ccf.org
Halloum
Ammar
A
Zhou
Aimin
A
Dong
Beihua
B
Al-Zoghaibi
Fahad
F
Kushner
David
D
Zhou
Quansheng
Q
Zhao
Ji
J
Wiedmer
Therese
T
Sims
Peter J
PJ
D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D008264:Macrophages / Q000473:pathology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D009504:Neutrophils / Q000473:pathology; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D049294:Phospholipid Transfer Proteins; D014162:Transfection; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D018076:DNA, Complementary; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins