Effect of ploidy, recruitment, environmental factors, and tamoxifen treatment on the expression of sigma-2 receptors in proliferating and quiescent tumour cells.
Recently, we demonstrated that sigma-2 receptors may have the potential to be a biomarker of tumour cell proliferation (Mach et al (1997) Cancer Res 57: 156-161). If sigma-2 receptors were a biomarker of tumour cell proliferation, they would be amenable to detection by non-invasive imaging procedures, thus eliminating many of the problems associated with the flow cytometric measures of tumour cell proliferation presently used in the clinic. To be a good biomarker of tumour cell proliferation, the expression of sigma-2 receptors must be essentially independent of many of the biological, physiological, and/or environmental properties that are found in solid tumours. In the investigation reported here, the mouse mammary adenocarcinoma lines, 66 (diploid) and 67 (aneuploid), 9L rat brain tumour cells, and MCF-7 human breast tumour cells were used to study the extent and kinetics of expression of sigma-2 receptors in proliferative (P) and quiescent (Q) tumour cells as a function of species, cell type, ploidy, pH, nutrient depletion, metabolic state, recruitment from the Q-cell compartment to the P-cell compartment, and treatment with tamoxifen. In these experiments, the expression of sigma-2 receptors solely reflected the proliferative status of the tumour cells. None of the biological, physiological, or environmental properties that were investigated had a measurable effect on the expression of sigma-2 receptors in these model systems. Consequently, these data suggest that the proliferative status of tumours and normal tissues can be non-invasively assessed using radiolabelled ligands that selectively bind sigma-2 receptors.
Al-Nabulsi
I
I
Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Mach
R H
RH
Wang
L M
LM
Wallen
C A
CA
Keng
P C
PC
Sten
K
K
Childers
S R
SR
Wheeler
K T
KT
D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology*; D014408:Biomarkers, Tumor / Q000032:analysis; D001932:Brain Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D002455:Cell Division; D005260:Female; D006801:Humans; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D011003:Ploidies; D051381:Rats; D017480:Receptors, sigma / Q000032:analysis / Q000096:biosynthesis*; D013629:Tamoxifen / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D017480:Receptors, sigma; D013629:Tamoxifen