Low density lipoprotein receptors and polyamine levels in human colorectal adenocarcinoma

Abstract

The low density lipoprotein receptor (LDLR) is a cell surface protein that binds with LDL, providing the cell with cholesterol for new membrane synthesis. Rapidly growing cells have high numbers of LDLRs, and these proteins have also been detected in neoplastic samples of human colorectal mucosa. Polyamines, putrescine, spermidine, and spermine, play an important role in cellular growth, and studies on colorectal cancers have demonstrated higher polyamine levels in neoplastic mucosa samples than in surrounding mucosa. The aim of this study was to investigate LDLR and polyamine levels in the neoplastic tissue of 43 patients (28 males and 15 females) with colorectal adenocarcinoma, using enzymatic immunoassay and high performance liquid chromatography, respectively. Specimens of neoplastic mucosa were considered LDLR-positive or LDLR-negative when the amount of bound human anti-LDLR antibody detected was equal or higher or lower than the cut-off value (0.5 ng of bound anti-LDLR Ab/mg protein), respectively. Twenty-one subjects were LDLR-positive and 22 LDLR-negative. Polyamine levels (nmol/g tissue) were higher in LDLR-positive specimens; this increase was significant for total polyamines (P < 0.05). These findings, reporting the presence of increased polyamine content in LDLR-positive colorectal neoplastic specimens, suggest an association between LDLR levels and gastrointestinal neoplastic proliferative activity.

In vitro, high‐resolution 1H and 31P NMR based analysis of the lipid components in the tissue, serum, and CSF of the patients with primary brain tumors: one possible diagnostic view

“…Cholesterol is mainly transported as plasma lipoproteins in an esterified form (31)(32)(33)(34)(35)(36)(37)(38)(39) to the brain tissue. Rapidly proliferating tumor cells show high cholesterol uptake via receptor-mediated endocytosis and have been shown to exhibit enhanced LDL receptor activity and large amounts of LDL receptors on the surface of each cell (40)(41)(42)(43)(44). Due to this reason, higher amount of cholesterol and cholesterol esters aggregate in the tissue of gliomas.…”

Evaluation of the Aortic Root by MRI

“…Rapidly dividing cells express high levels of LDL receptors. [21][22][23] In the absence of normal LDL receptors, the growth of the ascending aorta may be arrested in these patients.…”

3-Hydroxy-3-methylglutaryl coenzyme A reductase activity and low-density lipoprotein receptor expression in diffuse-type and intestinal-type human gastric cancer

“…It is known that IT gastric cancer has a higher proliferative activity than DT gastric cancer, as demonstrated by the higher polyamine levels detected in IT compared with DT gastric cancer. 9 Moreover, the presence of LDLR has also been positively correlated with a higher polyamine content in colorectal cancer, 22 indicating its importance in cell proliferation and neoplastic transformation. It is known that IT gastric cancer develops in the areas of type III intestinal metaplasia, which present histological, biochemical, and functional features similar to those in colorectal mucosa.…”

“…14 Moreover, in the present study, the levels of LDLR protein were higher than the levels found in colorectal tumors, 17 in which the role of LDLR and its mRNA in colonic neoplastic growth has been extensively investigated. 17,[22][23][24][25] However, the distribution of LDLR in various normal human tissues and some solid tumors shows considerable variability. 12 Interestingly, among human tumors, only gastric carcinoma has higher 125 LDL binding than other tumors.…”