Novel surface expression of reticulocalbin 1 on bone endothelial cells and human prostate cancer cells is regulated by TNF-alpha.
An unbiased cDNA expression phage library derived from bone-marrow endothelial cells was used to identify novel surface adhesion molecules that might participate in metastasis. Herein we report that reticulocalbin 1 (RCN1) is a cell surface-associated protein on both endothelial (EC) and prostate cancer (PCa) cell lines. RCN1 is an H/KDEL protein with six EF-hand, calcium-binding motifs, found in the endoplasmic reticulum. Our data indicate that RCN1 also is expressed on the cell surface of several endothelial cell lines, including human dermal microvascular endothelial cells (HDMVECs), bone marrow endothelial cells (BMEC), and transformed human bone marrow endothelial cells (TrHBMEC). While RCN1 protein levels were highest in lysates from HDMVEC, this difference was not statistically significant compared BMEC and TrHBMEC. Given preferential adhesion of PCa to bone-marrow EC, these data suggest that RCN1 is unlikely to account for the preferential metastasis of PCa to bone. In addition, there was not a statistically significant difference in total RCN1 protein expression among the PCa cell lines. RCN1 also was expressed on the surface of several PCa cell lines, including those of the LNCaP human PCa progression model and the highly metastatic PC-3 cell line. Interestingly, RCN1 expression on the cell surface was upregulated by tumor necrosis factor alpha treatment of bone-marrow endothelial cells. Taken together, we show cell surface localization of RCN1 that has not been described previously for either PCa or BMEC and that the surface expression on BMEC is regulated by pro-inflammatory TNF-alpha.
Center for Translational Cancer Research and Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, USA. crcooper@udel.edu
Carlton R
CR
Cooper
Bianca
B
Graves
Freddie
F
Pruitt
Hassan
H
Chaib
Jill E
JE
Lynch
Andrew Koemeter
AK
Cox
Linda
L
Sequeria
Kenneth L
KL
van Golen
Angelo
A
Evans
Kirk
K
Czymmek
Rebecca S
RS
Bullard
Carlton D
CD
Donald
Katia
K
Sol-Church
James D
JD
Gendernalik
Babette
B
Weksler
Mary C
MC
Farach-Carson
Jill A
JA
Macoska
Robert A
RA
Sikes
Kenneth J
KJ
Pienta
D015153:Blotting, Western; D001842:Bone and Bones / Q000166:cytology*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism*; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D019151:Peptide Library; D011471:Prostatic Neoplasms / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002135:Calcium-Binding Proteins; D019151:Peptide Library; C000597745:RCN1 protein, human; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C078865:reticulocalbin