The relationship between 1H-NMR mobile lipid intensity and cholesterol in two human tumor multidrug resistant cell lines (MCF-7 and LoVo).
The high resolution proton nuclear magnetic resonance (1H-NMR) spectra of two different cell lines exhibiting multidrug resistance (MDR) as demonstrated by the expression of the well-known energy-driven, membrane-bound 170 kDa P-glycoprotein pump known as Pgp were investigated. In particular, the mobile lipid (ML) profile, and the growth and biochemical characteristics of MCF-7 (human mammary carcinoma) and LoVo (human colon adenocarcinoma) sensitive and resistant tumor cells were compared. The results indicate that both MCF-7 and LoVo resistant cells have a higher ML intensity than their respective sensitive counterparts. However, since sensitive and resistant cells of each pair grow in the same manner, variations in growth characteristics do not appear to be the cause of the ML changes as has been suggested by other authors in non-resistant tumor cells. In order to investigate further the origin of the ML changes, lipid analyses were conducted in sensitive and resistant cell types. The results of these experiments show that resistant cells of both cell types have a greater amount of esterified cholesterol and saturated cholesteryl ester and triglyceride fatty acid than their sensitive counterparts. From a thorough analysis of the data obtained in this paper utilizing numerous techniques including biological, biophysical and biochemical ones, it is hypothesized that cholesterol and triglyceride play a pivotal role in inducing changes in NMR ML signals. The importance of these lipid variations in MDR is discussed in view of the controversy regarding the origin of ML signals and the paramount role played by the Pgp pump in resistance.
Laboratoria di Ultrastrutture, Istituto Superiore di Sanità, Rome, Italy. santini@iss.it
M T
MT
Santini
R
R
Romano
G
G
Rainaldi
P
P
Filippini
E
E
Bravo
L
L
Porcu
A
A
Motta
A
A
Calcabrini
S
S
Meschini
P L
PL
Indovina
G
G
Arancia
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000737:chemistry; D002453:Cell Cycle; D002784:Cholesterol / Q000737:chemistry*; D002788:Cholesterol Esters / Q000737:chemistry; D018432:Drug Resistance, Multiple; D005227:Fatty Acids / Q000032:analysis; D005231:Fatty Acids, Unsaturated / Q000032:analysis; D005456:Fluorescent Dyes; D006801:Humans; D008055:Lipids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D010078:Oxazines; D010743:Phospholipids / Q000032:analysis; D014280:Triglycerides / Q000737:chemistry; D014407:Tumor Cells, Cultured
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002788:Cholesterol Esters; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D005456:Fluorescent Dyes; D008055:Lipids; D010078:Oxazines; D010743:Phospholipids; D014280:Triglycerides; D002784:Cholesterol; C044808:nile red