Caveolin-1 secreting LNCaP cells induce tumor growth of caveolin-1 negative LNCaP cells in vivo.
Caveolin-1 (Cav-1) was originally identified as a structural protein of caveolae, which is a plasma membrane domain that regulates a variety of signaling pathways involved in cell growth and migration. Here, we show that expression of Cav-1 in the Cav-1-deficient human prostate cancer cell line LNCaP both stimulates cell proliferation and promotes tumor growth in nude mice. Unexpectedly, Cav-1 expressing LNCaP (LNCaP(Cav-1)) cells injected into one side of a nude mouse promoted tumor growth of Cav-1 negative LNCaP cells injected on the contralateral side of the same animal. The LNCaP tumors were positive for Cav-1, however, this signal was not caused by migrated LNCaP(Cav-1) cells, but we show that this Cav-1 was secreted by the LNCaP(Cav-1) tumors. We demonstrate that conditioned media from LNCaP(Cav-1) cells contained Cav-1 that was associated with a lipoprotein particle ranging in size from 15 to 30 nm and a density similar to high density lipoprotein particle. These results suggest that LNCaP(Cav-1) cells secreting Cav-1 particle produce an endocrine factor that stimulates tumor growth.
Bartz
René
R
Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA.
Zhou
Jian
J
Hsieh
Jer-Tsong
JT
Ying
Yunshu
Y
Li
Weiping
W
Liu
Pingsheng
P
D000818:Animals; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism*; D002450:Cell Communication; D002465:Cell Movement; D049109:Cell Proliferation; D017077:Culture Media, Conditioned / Q000494:pharmacology; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009376:Neoplasms, Hormone-Dependent / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*
C495540:CAV1 protein, human; C495541:Cav1 protein, mouse; D051242:Caveolin 1; D017077:Culture Media, Conditioned