Sigma 2 receptors as potential biomarkers of proliferation in breast cancer.
sigma 1 and sigma 2 receptors have been shown to exist in a number of rodent and human tumor cell lines. Although their expression is heterogeneous and their function is unknown, sigma receptors have been proposed as potential targets for diagnostic tumor-imaging agents. In this study, the density of sigma 2 receptors in proliferative (P) and quiescent (Q) cells of the mouse mammary adenocarcinoma, line 66, was examined. Scatchard analyses of sigma 2 receptors were performed on membrane preparations of 66 P cells from 3-day cultures and 66 Q cells from 7-, 10-, and 12-day cultures. The Scatchard studies revealed that 66 P cells had approximately 10 times more sigma 2 receptors/cell than the 66 Q cells from 10-day cultures. Although > 97% of the cells were quiescent after 7 days in culture, the maximum differential in the sigma 2 expression between 66 P and 66 Q cells was not attained until these cells had been in culture for 10 days. These data suggest that ligands labeled with positron-emitting or single photon-emitting radionuclides, which selectively bind sigma 2 receptors, have the potential to noninvasively assess the proliferative status of human breast tumors.
Mach
R H
RH
Department of Radiology, Bowman Gray School of Medicine, Winston-Salem, North Carolina 27157, USA.
Smith
C R
CR
al-Nabulsi
I
I
Whirrett
B R
BR
Childers
S R
SR
Wheeler
K T
KT
D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002455:Cell Division; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D017480:Receptors, sigma / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D014408:Biomarkers, Tumor; D017480:Receptors, sigma