Chemokine CXCL13 is overexpressed in the tumour tissue and in the peripheral blood of breast cancer patients.

The abilities of chemokines in orchestrating cellular migration are utilised by different (patho-)biological networks including malignancies. However, except for CXCR4/CXCL12, little is known about the relation between tumour-related chemokine expression and the development and progression of solid tumours like breast cancer. In this study, microarray analyses revealed the overexpression of chemokine CXCL13 in breast cancer specimens. This finding was confirmed by real-time polymerase chain reaction in a larger set of samples (n = 34) and cell lines, and was validated on the protein level performing Western blot, ELISA, and immunohistochemistry. Levels of CXCR5, the receptor for CXCL13, were low in malignant and healthy breast tissues, and surface expression was not detected in vitro. However, we observed a strong (P = 0.0004) correlation between the expressions of CXCL13 and CXCR5 in breast cancer tissues, indicating a biologically relevant role of CXCR5 in vivo. Finally, we detected significantly elevated serum concentrations of CXCL13 in patients with metastatic disease (n = 54) as compared with controls (n = 44) and disease-free patients (n = 48). In conclusion, CXCL13 is overexpressed within breast cancer tissues, and increased serum levels of this cytokine can be found in breast cancer patients with metastatic disease pointing to a role of CXCL13 in the progression of breast cancer, suggesting that CXCL13 might serve as a useful therapeutic target and/or diagnostic marker in this malignancy.

Multifocal distribution of pulmonary capillary haemangiomatosis.

AIMS: We investigated a case of pulmonary capillary haemangiomatosis, a rare condition, to determine the extent of the pathological changes within the lungs. Systematic histological sampling has not previously been performed in this condition. METHODS AND RESULTS: A 52-year-old woman with a history of ischaemic cardiomyopathy suffered from repeated respiratory infections, which were attributed to chronic pulmonary congestion. She died suddenly of fulminant pulmonary thromboembolism. An autopsy was performed and lung tissue was sampled at multiple sites. Beside passive congestion, the lungs showed well-circumscribed areas containing proliferations of small capillaries infiltrating the pulmonary septa and the walls of otherwise normal blood vessels and bronchi. The most severely affected areas were found to be in the periphery of both lower lobes. A diagnosis of pulmonary capillary haemangiomatosis was made. CONCLUSIONS: This is the first case of pulmonary capillary haemangiomatosis in which systematic histological sampling has been performed. Mapping of lesions disclosed the multifocal distribution of pulmonary capillary haemangiomatosis in this patient.

A new method for histological microdissection utilizing an ultrasonically oscillating needle: demonstrated by differential mRNA expression in human lung carcinoma tissue.

Molecular analysis of microdissected tissue samples is used for analyzing tissue heterogeneity of histological specimens. We have developed a rapid one-step microdissection technique, which was applied for the selective procurement of tissue areas down to a minimum of 10 cell profiles. The special features of our microdissection system consist of an ultrasonically oscillating needle and a piezo-driven micropipette. The validity of this technique is demonstrated in human lung large-cell carcinoma by real-time quantitative reverse transcriptase-polymerase chain reaction assays of vimentin, cyclin D1, and carcinoembryonic antigen after linear RNA amplification. mRNA expression values of microdissected samples scattered around those of bulk tumor tissue and showed differential mRNA expression between samples of tumor parenchyma and supportive stromal cells for vimentin and carcinoembryonic antigen as confirmed by immunohistochemistry. In conclusion, this procedure requires simple equipment, is easily performed, and delivers microdissected tissue samples of oligocellular clusters suitable for further molecular analysis.

Esophageal cancer: the mode of lymphatic tumor cell spread and its prognostic significance.

PURPOSE: Data on skip metastases and their significance are lacking for esophageal cancer. This issue is important to determine the extent of lymphadenectomy for esophageal resection. In this study we examined the lymphatic spread in esophageal cancer by routine histopathology and by immunohistochemistry. PATIENTS AND METHODS: A total of 1,584 resected lymph nodes were obtained from 86 patients with resected esophageal carcinoma and evaluated by routine histopathology. Additionally, frozen tissue sections of 540 lymph nodes classified as tumor-free by routine histopathology were screened for micrometastases by immunohistochemistry with the monoclonal antibody Ber-EP4. The lymph nodes were mapped according to the mapping scheme of the American Thoracic Society modified by Casson et al. RESULTS: Forty-four patients (51%) had pN1 disease, and 61 patients (71%) harbored lymphatic micrometastases detected by immunohistochemistry. Skip metastases detected by routine histopathology were present in 34% of pN1 patients. Skipping of micrometastases detected by immunohistochemistry was found in 66%. The presence of micrometastases was associated with a significantly decreased relapse-free and overall survival (56.0 v 10.0 months and > 64 v 15 months, P <.0001 and P =.004, respectively). Cox regression analysis revealed the independent prognostic influence of micrometastases in lymph nodes. Lymph node skipping had no significant independent prognostic influence on survival. CONCLUSION: Histopathologically and immunohistochemically detectable skip metastases are a frequent event in esophageal cancer. Only extensive lymph node sampling, in conjunction with immunohistochemical evaluation, will lead to accurate staging. An improved staging system is essential for more individualized adjuvant therapy.

The effect of repeated ozone exposures on inflammatory markers in bronchoalveolar lavage fluid and mucosal biopsies.

The aim of this study was to investigate the cellular and biochemical events associated with repeated exposures to ozone. Twenty-three healthy subjects underwent single exposures to 200 ppb ozone and to filtered air (FA), as well as repeated exposures to 200 ppb ozone on 4 consecutive days, each for 4 h of intermittent exercise. Bronchoalveolar lavage was performed and mucosal biopsies were taken 20 h after the single or the last of the repeated exposures. As compared with FA, the single exposure to ozone caused a decrease in FEV(1), an increase in the percentages of neutrophils and lymphocytes, the concentrations of total protein, IL-6, IL-8, reduced glutathione, urate, and ortho-tyrosine in BAL fluid (BALF), but no changes in the cellular composition of biopsy. After the repeated exposure, the effect on lung function was abolished and differential cell counts in BALF were not significantly different from those after FA. However, the concentrations of total protein, IL-6, IL-8, reduced glutathione, and ortho-tyrosine were still increased. IL-10 could only be detected in BALF after repeated ozone exposures. Furthermore, macroscopic scores for bronchitis, erythema, and hypervulnerability of airway mucosa were increased, as well as numbers of neutrophils in bronchial mucosal biopsies. Our data demonstrate that airway inflammation persists after repeated ozone exposure, despite attenuation of some inflammatory markers in BALF and adaptation of lung function.

Association of impaired phosphatidylinositol 3-kinase activity in GLUT1-containing vesicles with malinsertion of glucose transporters into the plasma membrane of fibroblasts from a patient with severe insulin resistance and clinical features of Werner syndrome.

The purpose of this study was to examine the molecular mechanism responsible for the defective insulin-stimulated glucose transport in cultured fibroblasts from a patient (VH) with clinical features of Werner syndrome and severe insulin resistance. Thus, in cells derived from VH, the subcellular distribution, structure, functional activity, as well as plasma membrane insertion of GLUT1 glucose transporters were analyzed. Furthermore, the insulin signal transduction pathway leading to activation of phosphatidylinositol (PI) 3-kinase as well as components of GLUT1-containing membrane vesicles were characterized. In fibroblasts derived from VH, GLUT1 glucose transporters were overexpressed by 8-fold in plasma membranes (PM) and by 5-fold in high density microsomes, respectively. Exofacial photolabeling revealed that only 14% of the overexpressed PM-GLUT1 transporters were properly inserted into the plasma membrane. The complementary DNA structure of the patient's insulin receptor and the GLUT1 glucose transporter, the intrinsic activity of plasma membrane glucose transporters, the tyrosine phosphorylation, as well as the protein expression of insulin receptor substrate-1/2 and p85 alpha/beta- and p110 alpha/beta-subunits of PI 3-kinase were normal. However, insulin-stimulated association of the p85 subunit of PI 3-kinase was defective in fibroblasts derived from VH compared to those from controls, and this defect was associated with a reduced IRS-1-dependent activation of PI 3-kinase by 50.2% and 63.6% after incubation for 5 and 10 min with 100 nmol/L insulin, respectively. Furthermore, immunodetection of small GTP-binding Rab proteins in subcellular membrane fractions indicated a decreased expression of Rab4 in total cellular homogenates as well as in high density microsomes by 70% and 58%, respectively. After preparation of GLUT1-containing vesicles, Rab4 was not detected to be a component of these vesicles. Analysis of the PI 3-kinase in GLUT1-containing membrane vesicles revealed insulin-dependent targeting of the p85 subunit to the vesicles immunoadsorbed from VH and control fibroblasts. Importantly, the association of the p85 subunit as well as the p85-immunoprecipitable PI 3-kinase activity were markedly reduced in GLUT1-vesicles derived from the patient. In conclusion, impaired PI 3-kinase activity in GLUT1-containing membrane vesicles derived from fibroblasts of VH is associated with a defective docking and/or fusion process of glucose transporters with the plasma membrane and thus might contribute to the molecular defect causing insulin resistance in this patient.

Angiogenesis, angiogenic growth factors, and cell adhesion molecules are upregulated in chronic pancreatic diseases: angiogenesis in chronic pancreatitis and in pancreatic cancer.

Recent epidemiologic evidence suggests that patients with chronic pancreatitis (CP) have an increased risk of developing pancreatic carcinoma (PCA). In spite of numerous similarities in both diseases, mechanisms for progression from CP to PCA are poorly understood. We hypothesized that enhanced angiogenesis might play a pivotal role in the etiology and histopathology of both CP and PCA, and thus form a possible link between precancer and carcinoma. In surgical specimens of 18 patients with CP, 10 with PCA, and 18 controls, absolute numbers of blood vessels and relative blood vessel density were assessed after immunostaining of endothelial cells for von Willebrand factor and PECAM-1 (platelet/ endothelial cell adhesion molecule-1). Furthermore, the expression of cell adhesion molecules ICAM-1 (intercellular adhesion molecule-1) and VCAM-1 (vascular cell adhesion molecule-1) and of VEGF (vascular endothelial growth factor) was investigated in all specimens. Both CP and PCA exhibited areas of high vascular density ("hot spots"). The mean number of blood vessels in these areas in PCA was 132.2+/-16.8 per mm2, and in CP, 99.2+/-7.4 per mm2. The mean vessel count in controls was 25.1+/-5.1. Relative vessel density was increased in both PCA (41.3+/-3.5%) and CP (30.6+/-2.6%) versus controls (8.0+/-0.8%). Both absolute vessel count and relative vessel density were significantly higher (p<0.05) in PCA than in CP. Enhanced expression of ICAM-1 in CP and PCA was seen in ductal cells in CP and cancer cells. In controls, ICAM-1 and VCAM-1 were expressed only at low levels in endothelial cells. VCAM-1 was strongly expressed in acinar cells as well as in ductal cells. In CP and PCA, VEGF was strongly expressed in ductal cells in CP as well as in cancer cells. We show for the first time that angiogenic activity is increased in both CP and PCA. Based on this study, we suggest that antiangiogenesis might be a novel target for prevention or therapy in chronic pancreatic diseases.

[Effect of various forms of metastatic lymph node involvement on prognosis of squamous epithelial carcinomas of the upper aerodigestive tract]. / Einfluss verschiedener Formen des metastatischen Lymphknotenbefalls auf die Prognose von Plattenepithelkarzinomen im oberen Aerodigestivtrakt.

BACKGROUND: Based on a new histo-morphological rating scheme, we assessed the impact on patient prognosis of lymph node metastasis of squamous cell carcinoma (SCC) in the head/neck area. Special attention was given to possible capsular rupture. METHOD: In a retrospective study, 111 patients with squamous cell carcinoma of the head and neck with concomitant cervical lymph node metastases were evaluated to determine the importance of lymph node capsular rupture on the occurrence of disseminated disease, loco-regional recurrence as well as survival rate. To cover the broad morphological spectrum of cervical metastatic disease, a newly developed scheme (differentiating seven different histo-morphological types of lymph node metastasis) was applied. On the basis of this scheme, every single metastatic lymph node received a score from one to seven. These single scores were then added to obtain a total score for every individual patient. These total scores were then divided into four groups. RESULTS: Synthesis of histo-morphological pattern of metastasis in combination with the number of metastatic lymph nodes showed highest concordance/significance in respect of disseminated disease (p = 0.0029), local recurrence (p = 0.0008) and regional lymph node metastasis (p = 0.0000) as well as survival rate (p = 0.0000). CONCLUSION: The newly introduced histological scheme seems to provide more accuiate and detailed information on the prognosis of SCC in the head and neck area.

Survival and cardiovascular pathology of heterozygous Watanabe heritable hyperlipidaemic rabbits treated with pravastatin and probucol on a low-cholesterol (0.03%)-enriched diet.

This study was aimed at determining the effects of a combined pravastatin and probucol regimen on survival and vascular pathology of heterozygous Watanabe heritable hyperlipidaemic (WHHL) rabbits fed a low-cholesterol (0.03%)-enriched diet. Pravastatin monotherapy preceded the combined treatment. In animals receiving pravastatin and the enriched diet (verum group; n = 6), mean total serum cholesterol levels were consistently lowered at a dosage of 5 mg/kg pravastatin and with the combined treatment. Survival was increased (median 45 vs 25 months), while coronary atherosclerosis was less obstructive and altered to a more fibrous type than in controls (n = 8). The extent of aortic lesions, as determined by the relative plaque volume, was not related to survival in either group. However, aortic plaque types in verum group animals revealed less severe stages with a different composition and architecture, with a lower relative content of macrophage-derived foam cells and necrosis and a higher relative content of extracellular matrix. There was also a thicker fibrous cap than in control animals of similar age. Our data reveal a beneficial effect on survival of heterozygous WHHL rabbits when lipid-lowering and antioxidative treatment are combined. This appears to be due both to reduced coronary atherosclerosis and to a different, more stable type of atherosclerotic disease in this animal model.

Effects of pravastatin on cholesterol metabolism of cholesterol-fed heterozygous WHHL rabbits.

1. We administered the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor pravastatin at a daily dose of 1 mg kg(-1) body weight to cholesterol-fed (0.03%) heterozygous Watanabe heritable hyperlipidaemic rabbits, an animal model for heterozygous familial hypercholesterolaemia. 2. After 12 months of cholesterol treatment, immunohistochemistry with the monoclonal antibody 9D9 was used to detect hepatic low density lipoprotein (LDL) receptors, which were quantified by densitometry. In addition we determined LDL receptor mRNA by competitive reverse transcriptase polymerase chain reaction. The cholesterol precursor lathosterol and the plant sterol campesterol were analysed by gas-liquid chromatography. 3. The drug reduced total plasma cholesterol levels by 51% (P=0.04), when compared to the control group. Unexpectedly, hepatic LDL receptor density and mRNA showed no significant differences between the groups. Total plasma levels of lathosterol and campesterol also revealed no significant differences between the groups, if expressed relative to plasma cholesterol. 4. The findings suggest that mechanisms other than induced hepatic LDL receptors are responsible for the cholesterol-lowering effect of pravastatin in this animal model. We propose a reduced cholesterol absorption efficiency compatible with similar campesterol levels between both groups observed in our study.

LDL receptor activity in human leukocyte subtypes: regulation by insulin.

OBJECTIVES: LDL receptors of leukocytes play a key role in lipoprotein uptake, immunoregulation and the pathogenesis of atherosclerosis. Numerous studies with different methods of low reliability yielded conflicting results of its regulation in leukocyte subtypes. DESIGN AND METHODS: LDL receptors of human leukocytes were measured with use of the monoclonal antibody C-7. Specific C-7 binding was detected by FACS analysis using phycoerythrin-anti-mouse-IgG. Parallel incubations with FITC-labelled anti-LEU 4 (CD 3), anti-LEU 12 (CD 19) and anti-MY 4 (CD 14) antibodies were used to distinguish C-7 binding of specific cell types (T-, B-lymphocytes and monocytes). RESULTS: In contrast to monocytes, T and B-lymphocytes freshly isolated from healthy blood donors had no detectable binding capacity for C-7. After 24 and 48 h incubation of cells in a lipid-free medium, lymphocytes acquired some C-7 binding, albeit still much less than monocytes. Incubation with insulin for 24 h in a concentration of 0.5 microgram/mL led to an increase in C-7 binding for monocytes (up to 180%). Saturation experiments with the ligand suggests an increase in the number of receptors. In contrast the same insulin concentration inhibited C-7 binding of B- and T-lymphocytes by 35%. CONCLUSIONS: FACS analysis using monoclonal antibodies seems to be a feasible method for the investigation of lipid metabolism in leukocytes. The LDL receptor expression and its regulation by insulin differs in circulating monocytes and lymphocytes.

Prognostic value of immunohistochemically identifiable tumor cells in lymph nodes of patients with completely resected esophageal cancer.

BACKGROUND: Current methods of disease staging often fail to detect small numbers of tumor cells in lymph nodes. Metastatic relapse may arise from these few cells. METHODS: We studied 1308 lymph nodes from 68 patients with esophageal cancer without overt metastases who had undergone radical en bloc esophagectomy. A total of 399 lymph nodes obtained from 68 patients were found to be free of tumor by routine histopathological analysis and were studied further for isolated tumor cells by immunohistochemical analysis with the monoclonal anti-epithelial-cell antibody Ber-EP4. This antibody did not stain lymph nodes from 24 control patients without carcinoma. RESULTS: Of the 399 "tumor free" lymph nodes, 67 (17 percent), obtained from 42 of the 68 patients, contained Ber-EP4-positive tumor cells. Fifteen of 30 patients who were considered free of lymph-node metastases by histopathological analysis had such cells in their lymph nodes, and 5 of the 15 had small primary tumors. Ber-EP4-positive cells found in "tumor free" nodes were independently predictive of significantly reduced relapse-free survival (P=0.008) and overall survival (P=0.03). They predicted relapse both in patients without nodal metastases (P=0.01) and in those with regional lymph-node involvement (P=0.007). All 12 patients whose lymph nodes were negative on both histopathological and immunohistochemical analysis and who were available for follow-up survived without recurrence. The presence of micrometastatic tumor cells in bone marrow had no additional prognostic value. CONCLUSIONS: Immunohistochemical examination of lymph nodes may improve the pathological staging of esophageal cancer.

Early lymphatic tumor cell dissemination in pancreatic cancer: frequency and prognostic significance.

Tumor relapse occurs frequently in patients with ductal pancreatic head cancer despite the absence of residual tumor detectable at primary surgery. Therefore it has to be assumed that current tumor staging procedures fail to detect minimal amounts of disseminated tumor cells present in secondary organs, which might be the seed for subsequent metastatic relapse. We evaluated lymph nodes from 18 patients without overt metastases who had undergone radical tumor resection (R0 resection). Lymph nodes judged as "tumor-free" by routine histopathology were further examined for the presence of single tumor cells using immunohistochemistry with the antiepithelial monoclonal antibody Ber-EP4. Sixteen of 37 "tumor-free" lymph nodes (43.2%), obtained from 13 of 18 patients (72.2%), displayed Ber-EP4+ tumor cells. Twelve of these 18 patients presented at pT2 stage. Nine of 12 patients (75%) staged as pN0 had these cells. Two of six pN1 patients had no Ber-EP4+ in histopathologically tumor-free lymph nodes. Using multivariate Cox's regression analysis, the presence of Ber-EP4+ cells in "tumor-free" lymph nodes was an independent factor for a significantly reduced relapse-free survival (p = 0.006) and overall survival (p = 0.01). Remarkably, all patients who were restaged as lymph node negative by both histopathology and immunohistochemistry survived the observation period without recurrence. The frequent occurrence of disseminated tumor cells in patients with pancreatic cancer and their prognostic impact support the need for a refined staging system of excised lymph nodes, which should include immunohistochemical examination. Thus patients with a minimal residual tumor load who might benefit from an adjuvant therapy could be selected.

[Atherosclerosis. Formal pathogenesis, classification and functional significance]. / Atherosklerose. Formale Pathogenese, Klassifikation und funktionelle Bedeutung.

Atherosclerosis and its complications determine the majority of deaths in the western world, followed by malignant tumors. The present work introduces a classification of stages of atherosclerotic disease based on relevant pathogenic and therapeutic concepts, elaborated by H. Stary. At the present, we are able to relate different lesion types to a time course and partly to interferences between participating cell populations as well as to special pathogenic stimuli. From the therapeutic view, this knowledge is fundamental for preventive as well as interventional strategies like gene therapy. Distinct atherosclerotic plaques reveal a different composition and architecture, which may account for the variable risk for further complications of lesions showing the same size and degree of stenosis. In combination with an advanced clinical and diagnostic characterization of atherosclerotic lesions, the present concept might contribute to a better and differential therapy of atherosclerosis.

Effects of low-dose pravastatin sodium on plasma cholesterol levels and aortic atherosclerosis of heterozygous WHHL rabbits fed a low cholesterol (0.03%) enriched diet for one year.

The aim of this study was to evaluate the cholesterol-lowering and antiatherosclerotic effect of the HMG-CoA reductase inhibitor pravastatin sodium at a dosage comparable to human therapy. Twelve heterozygous WHHL rabbits (13 months old) were fed 100 g per day of a low cholesterol (0.03%) enriched diet for 12 months. Six of these animals also received pravastatin sodium at a daily dose of 1 mg/kg body weight (verum group). In the verum group, total plasma cholesterol levels were lower by 47%(P < 0.05) and relative aortic plaque volume (% ratio of total plaque volume to the aortic lumen) was reduced by 78% (P < 0.05), when compared to the control group. Plaque composition was analysed at 30 cross-sectional levels of the entire aortic wall using a grid window. Compared to the control group, the plaque type, in terms of architecture and composition, was altered as follows: lesions in the verum group had no confluent atheromatous cores and showed a pattern of a diffuse mixture of the main plaque components with a decreased relative content of necrosis (-44%) and an increased relative content of smooth muscle cells (+19%), whereas the relative content of macrophage-derived foam cells and collagen were nearly unaffected. Furthermore, a similar plaque volume and type was observed in animals with comparable cholesterol profiles. There was no histologic evidence for structurally damaging effects of pravastatin sodium on the arterial wall. We conclude that pravastatin sodium reduces total plasma cholesterol levels in this animal model, thereby leading to smaller plaques and a different plaque type.

Expression and prognostic significance of immunoregulatory molecules in esophageal cancer.

Major histocompatibility complex molecules (HLA), the co-stimulatory molecule B7 and the intercellular adhesion molecule 1 (ICAM-1) are key molecules involved in T cell-mediated immune surveillance. We aimed at assessing the expression pattern of these immunoregulatory molecules on primary esophageal carcinomas and evaluating their prognostic significance. Representative samples of primary tumors were obtained from 53 patients who had undergone radical en bloc esophagectomy without residual tumor. Cryostat sections of these tumors were stained with monoclonal antibodies (MAbs) directed against either HLA class I, HLA class II, B7 or ICAM-1. The median follow-up was 19 months (range, 6-43). We found that HLA class I expression was deficient on 27 tumors, while a significant neo-expression of HLA class II, B7 and ICAM-1 (> or =25% positive tumor cells) was observed on 17, 29 and 25, tumors, respectively. Kaplan-Meier analyses revealed a significant beneficial influence on relapse-free survival for patients with tumors expressing HLA class I, HLA class II and B7. Cox's regression analyses demonstrated that co-expression of HLA class I and ICAM-1 was a significant and independent predictor of a reduced risk of developing tumor recurrence, whereas expression of ICAM-1 on HLA class I negative tumors was correlated with an increased risk of tumor relapse.

Organ- and tissue-specific expression of the low density lipoprotein receptor. Rapid quantitation by competitive reverse transcriptasepolymerase chain reaction.

A rapid and sensitive method of quantifying very low-abundant mRNA species by competitive reverse transcriptase-polymerase chain reaction (cRT-PCR) is presented. For each analysis, a defined amount of total cellular RNA is co-reverse transcribed and co-amplified with a titration series of in vitro synthesized RNA from a clone of the mRNA which carries an internal deletion. The equivalence point, which defines the number of specific mRNA molecules in the sample, can be determined using ethidium bromide stained gels of the reaction products. We present here three examples of the application of this new technique to the quantification of the low abundant mRNA for the low density lipoprotein (LDL) receptor. First, the regulation of LDL receptor mRNA expression by the HMG-CoA reductase inhibitor, pravastatin, has been analysed in vitro, in a human gastric tumour cell line. Second, LDL receptor mRNA from various bovine tissues has been quantified. Third, the expression of LDL receptor mRNA in human tissues originating from colorectal carcinoma and corresponding tumour-tree margins of surgical specimens has been measured.

Transfer of lipoprotein(a) and LDL into aortic intima in normal and in cholesterol-fed rabbits.

To study the relative atherogenic potential of lipoprotein(a) [Lp(a)], the transfer of Lp(a) and LDL into the arterial wall was compared in normal rabbits, cholesterol-fed rabbits, and normal rabbits in which the plasma concentration of Lp(a) before injection of labeled lipoproteins was increased by an intravenous mass injection of 45 mg Lp(a). Aorta was removed either 60 minutes or 180 minutes after intravenous injection of a mixed preparation of human 125I-Lp(a) and 131I-LDL; intimal clearance was calculated as radioactivity in aortic intima/inner media divided by the average concentration of the appropriate radioactivity in plasma and by the length of the exposure time. The intimal clearance of labeled Lp(a) and LDL in the aortic arch after 60 minutes of exposure was 87 +/- 9 and 47 +/- 7 nL.cm-2.h-1 (n = 9) in normal rabbits and 82 +/- 14 and 62 +/- 10 nL.cm-2.h-1 (n = 10) in cholesterol-fed rabbits; after 180 minutes of exposure, the intimal clearance of labeled Lp(a) and LDL was 62 +/- 14 and 84 +/- 21 nL.cm-2.h-1 (n = 6) and 30 +/- 6 and 47 +/- 12 nL.cm-2.h-1 (n = 4) in cholesterol-fed and Lp(a)-injected rabbits, respectively. Linear regression analysis showed positive associations between intimal clearance of the two lipoproteins in all four groups of rabbits in the aortic arch, the thoracic aorta, and the abdominal aorta. Aortic immunoreactivity of human apolipoprotein(a) was detected in the intima in association with fatty streak lesions, predominantly within the cytoplasm of foam cells. These results suggest that Lp(a) is transferred into the aortic intima by a mechanism similar to that for LDL and that Lp(a) can be taken up by intimal foam cells; however, Lp(a) and LDL may be metabolized differently upon entrance into the arterial wall.

Increased LDL receptor mRNA expression in colon cancer is correlated with a rise in plasma cholesterol levels after curative surgery.

It is currently under debate whether the low serum cholesterol levels that are frequently observed in cancer patients represent a risk factor for/or, rather, are a consequence of the tumour. We postulate that malignant tumours are directly involved in an increased catabolism of cholesterol-rich low-density lipoprotein (LDL) particles. In a prospective study of 25 patients with colorectal carcinoma, we measured intraindividual shifts in serum cholesterol levels after surgery, and the expression of LDL-receptor mRNA in surgically removed specimens. A significant rise in plasma cholesterol levels was observed in patients 3 and 12 months after curative surgery, but not after non-curative surgery. In human colon carcinoma tissues LDL receptor mRNA expression, as determined by competitive reverse-transcriptase-polymerase-chain reaction, was found to be significantly increased when compared to tissues from the tumour-free margin (median values, 1.2 x 10(6) vs. 2.0 x 10(5) molecules/micrograms total cellular RNA, respectively, n = 17). The extent of LDL-receptor mRNA expression positively correlated to the percentage rise of plasma cholesterol levels 3 months (n = 7, r = 0.8763) and 12 months (n = 6, r = 0.9181) after curative surgery. This finding provides in vivo evidence that the tumour tissue itself contributes to decreased plasma cholesterol levels in patients suffering from colorectal carcinomas. It supports the hypothesis that low cholesterol levels in cancer patients are a consequence, and not the cause, of the malignancy.