title: Resistance of malignant trophoblast cells to both the anti-proliferative and anti-invasive effects of transforming growth factor-beta.
abstract: Human placental trophoblast invasion of the uterus is a highly controlled event. We had shown that transforming growth factor-beta (TGF-beta) produced in the pregnant uterus controls invasiveness and reduces proliferation of first trimester placental trophoblasts in vitro. The anti-invasive effect of TGF-beta was due, at least in part, to induction of tissue inhibitor of metalloproteinases (TIMP)-1. In the present study we compared the effects of TGF-beta on proliferation ([3H]-TdR incorporation) and invasiveness (3-day Matrigel invasion assay) of JAR and JEG-3 choriocarcinoma cells vs normal first trimester human trophoblast cells. Transcripts of type IV collagenases (72- and 92-kDa enzymes, i.e., gelatinases A and B) and their inhibitors (TIMP-1 and TIMP-2) in these cells were measured by Northern analysis, and secretion of gelatinases and plasminogen activators (PAs) was evaluated by gel zymography. The results revealed that: (a) TGF-beta inhibited invasiveness and proliferation of normal trophoblast but not JAR and JEG-3 choriocarcinoma cells; (b) gelatinase A mRNA, expressed by the normal trophoblast and JAR cells, was upregulated in the presence of TGF-beta; (c) gelatinase B mRNA was not detected in the total RNA preparations of treated or untreated normal trophoblast or choriocarcinoma cells; (d) TGF-beta significantly upregulated the levels of TIMP-1 mRNA in the normal trophoblasts, but this transcript was very low in treated as well as untreated choriocarcinoma cells; TGF-beta also upregulated the 3.5-kb TIMP-2 message in the normal trophoblast; (e) gelatin zymography revealed a distinct band of approximately 68-kDa (gelatinase A) in the conditioned media of normal trophoblast and JAR cells; however, TGF-beta did not change the level of secretion of this gelatinase; and (f) the normal trophoblast also exhibited significant PA secretion (casein zymography) which was reduced in the presence of TGF-beta. PA secretion by the malignant trophoblast cells was low and unaffected by TGF-beta. These findings suggest that choriocarcinoma cells may become refractory to the mechanisms which control normal trophoblast proliferation and invasiveness. Concurrent resistance to antiproliferative and anti-invasive molecules such as TGF-beta may be highly relevant to tumor progression.
authors.affiliation: Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada.
authors.forename: C H
authors.initials: CH
authors.lastname: Graham
authors.forename: I
authors.initials: I
authors.lastname: Connelly
authors.forename: J R
authors.initials: JR
authors.lastname: MacDougall
authors.forename: R S
authors.initials: RS
authors.lastname: Kerbel
authors.forename: W G
authors.initials: WG
authors.lastname: Stetler-Stevenson
authors.forename: P K
authors.initials: PK
authors.lastname: Lala
mesh_terms: D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002822:Choriocarcinoma / Q000378:metabolism* / Q000473:pathology; D017364:Collagenases / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D005260:Female; D018093:Gelatinases / Q000235:genetics / Q000378:metabolism; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism; D009361:Neoplasm Invasiveness; D010960:Plasminogen Activators / Q000187:drug effects; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D019716:Tissue Inhibitor of Metalloproteinase-2; D019714:Tissue Inhibitor of Metalloproteinases; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014327:Trophoblasts / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D006023:Glycoproteins; D011506:Proteins; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D016212:Transforming Growth Factor beta; D019716:Tissue Inhibitor of Metalloproteinase-2; D010960:Plasminogen Activators; D017364:Collagenases; D018093:Gelatinases; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9