Pectin Abstracts 1

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Modified citrus pectin-monograph.
            (2000) Download
Modified citrus pectin (MCP), also known as fractionated pectin, is a complex polysaccharide obtained from the peel and pulp of citrus fruits. Modified citrus pectin is rich in galactoside residues, giving it an affinity for certain types of cancer cells. Metastasis is one of the most life-threatening aspects of cancer and the lack of effective anti-metastatic therapies has prompted research on MCP's effectiveness in blocking metastasis of certain types of cancers, including melanomas, prostate, and breast cancers.

The fibrosis marker galectin-3 and outcome in the general population.
            (de Boer et al., 2012) Download
OBJECTIVE: Galectin-3 is involved in fibrosis and inflammation and plays a role in heart failure, renal disease, obesity and cancer. We aimed to establish the relationship between galectin-3 and cardiovascular (CV) risk factors and mortality in the general population. DESIGN AND SUBJECTS: This study included 7968 subjects from the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) cohort, with a median follow-up of approximately 10 years. Plasma galectin-3 was measured in baseline samples. MAIN OUTCOME MEASURES: We investigated the relationships between galectin-3 levels, demographic characteristics and risk factors of CV disease. We determined the prognostic value for all-cause, CV and cancer mortality. RESULTS: The mean age of the population was 50 +/- 13 years. Mean blood pressure was 129/74 mmHg, mean cholesterol was 5.7 +/- 1.1 mmol L(-1) and median galectin-3 was 10.9 ng mL(-1) [interquartile range (IQR) 9.0-13.1]. Galectin-3 levels correlated with a wide range of risk factors of CV disease, including blood pressure, serum lipids, body mass index, renal function and N-terminal pro-B-type natriuretic peptide (P < 0.0001). We observed a strong association between galectin-3 and age. Furthermore, we found a gender interaction, with female subjects (n = 4001) having higher median galectin-3 levels (11.0 ng mL(-1) , IQR 9.1-13.4 vs. men (n = 3967) 10.7 ng mL(-1) , IQR 8.9-12.8; P < 0.0001), and galectin-3 levels in women more strongly correlated with risk factors of CV disease. After correction for the classical CV risk factors (smoking, blood pressure, cholesterol and diabetes), galectin-3 levels independently predicted all-cause mortality (hazard ratio per SD galectin-3 1.09, 95% CI 1.01-1.19; P = 0.036), but not CV and cancer mortality separately. CONCLUSIONS: Galectin-3 is associated with age and risk factors of CV disease, with a strong gender interaction for these correlations. Galectin-3 predicts all-cause mortality in the general population.

Galectin-3: a modifiable risk factor in heart failure.
            (de Boer et al., 2014) Download
Myocardial galectin-3 is upregulated upon cardiac stressors such as angiotensin II and pressure overload leading to cardiac remodeling and heart failure. The expression level of galectin-3 mirrors the progression and severity of heart failure and therefore, galectin-3 is being used as a biomarker for heart failure. However, as galectin-3 is causally involved in pathological myocardial fibrosis it has been suggested that galectin-3 also actively contributes to heart failure development. In this review we discuss how galectin-3 could be a target for therapy in heart failure. Currently, attempts are being made to target or inhibit galectin-3 using natural or pharmaceutical inhibitors with the aim to ameliorate heart failure. Available experimental evidence suggests that galectin-3 inhibition indeed may represent a novel tool to treat heart failure. A strong interaction with aldosterone, another strong pro-fibrotic factor, has been described. Clinical studies are needed to prove if galectin-3 may be used to install specific treatment regimens.

Galectin-3: an open-ended story.
            (Dumic et al., 2006) Download
Galectins, an ancient lectin family, are characterized by specific binding of beta-galactosides through evolutionary conserved sequence elements of carbohydrate-recognition domain (CRD). A structurally unique member of the family is galectin-3; in addition to the CRD it contains a proline- and glycine-rich N-terminal domain (ND) through which is able to form oligomers. Galectin-3 is widely spread among different types of cells and tissues, found intracellularly in nucleus and cytoplasm or secreted via non-classical pathway outside of cell, thus being found on the cell surface or in the extracellular space. Through specific interactions with a variety of intra- and extracellular proteins galectin-3 affects numerous biological processes and seems to be involved in different physiological and pathophysiological conditions, such as development, immune reactions, and neoplastic transformation and metastasis. The review attempts to summarize the existing information on structural, biochemical and intriguing functional properties of galectin-3.


 

Mechanical entrapment is insufficient and intercellular adhesion is essential for metastatic cell arrest in distant organs.
            (Glinskii et al., 2005) Download
In this report, we challenge a common perception that tumor embolism is a size-limited event of mechanical arrest, occurring in the first capillary bed encountered by blood-borne metastatic cells. We tested the hypothesis that mechanical entrapment alone, in the absence of tumor cell adhesion to blood vessel walls, is not sufficient for metastatic cell arrest in target organ microvasculature. The in vivo metastatic deposit formation assay was used to assess the number and location of fluorescently labeled tumor cells lodged in selected organs and tissues following intravenous inoculation. We report that a significant fraction of breast and prostate cancer cells escapes arrest in a lung capillary bed and lodges successfully in other organs and tissues. Monoclonal antibodies and carbohydrate-based compounds (anti-Thomsen-Friedenreich antigen antibody, anti-galectin-3 antibody, modified citrus pectin, and lactulosyl-l-leucine), targeting specifically beta-galactoside-mediated tumor-endothelial cell adhesive interactions, inhibited by >90% the in vivo formation of breast and prostate carcinoma metastatic deposits in mouse lung and bones. Our results indicate that metastatic cell arrest in target organ microvessels is not a consequence of mechanical trapping, but is supported predominantly by intercellular adhesive interactions mediated by cancer-associated Thomsen-Friedenreich glycoantigen and beta-galactoside-binding lectin galectin-3. Efficient blocking of beta-galactoside-mediated adhesion precludes malignant cell lodging in target organs.

Inhibition of prostate cancer bone metastasis by synthetic TF antigen mimic/galectin-3 inhibitor lactulose-L-leucine.
            (Glinskii et al., 2012) Download
Currently incurable, prostate cancer metastasis has a remarkable ability to spread to the skeleton. Previous studies demonstrated that interactions mediated by the cancer-associated Thomsen-Friedenreich glycoantigen (TF-Ag) and the carbohydrate-binding protein galectin-3 play an important role in several rate-limiting steps of cancer metastasis such as metastatic cell adhesion to bone marrow endothelium, homotypic tumor cell aggregation, and clonogenic survival and growth. This study investigated the ability of a synthetic small-molecular-weight nontoxic carbohydrate-based TF-Ag mimic lactulose-L-leucine (Lac-L-Leu) to inhibit these processes in vitro and, ultimately, prostate cancer bone metastasis in vivo. Using an in vivo mouse model, based on intracardiac injection of human PC-3 prostate carcinoma cells stably expressing luciferase, we investigated the ability of Lac-L-Leu to impede the establishment and growth of bone metastasis. Parallel-flow chamber assay, homotypic aggregation assay, modified Boyden chamber assay, and clonogenic growth assay were used to assess the effects of Lac-L-Leu on tumor cell adhesion to the endothelium, homotypic tumor cell aggregation, transendothelial migration, and clonogenic survival and growth, respectively. We report that daily intraperitoneal administration of Lac-L-Leu resulted in a three-fold (P < .05) decrease in metastatic tumor burden compared with the untreated control. Mechanistically, the effect of Lac-L-Leu, which binds and inhibits galectins by mimicking essential structural features of the TF-Ag, was associated with a dose-dependent inhibition of prostate cancer cell adhesion to bone marrow endothelium, homotypic aggregation, transendothelial migration, and clonogenic growth. We conclude that small-molecular-weight carbohydrate-based compounds targeting beta-galactoside-mediated interactions could provide valuable means for controlling and preventing metastatic prostate cancer spread to the skeleton.

Modified citrus pectin anti-metastatic properties: one bullet, multiple targets.
            (Glinsky and Raz, 2009) Download
In this minireview, we examine the ability of modified citrus pectin (MCP), a complex water soluble indigestible polysaccharide obtained from the peel and pulp of citrus fruits and modified by means of high pH and temperature treatment, to affect numerous rate-limiting steps in cancer metastasis. The anti-adhesive properties of MCP as well as its potential for increasing apoptotic responses of tumor cells to chemotherapy by inhibiting galectin-3 anti-apoptotic function are discussed in the light of a potential use of this carbohydrate-based substance in the treatment of multiple human malignancies.

Galectin-3, a marker of cardiac fibrosis, predicts incident heart failure in the community.
            (Ho et al., 2012) Download
OBJECTIVES: The aim of this study was to examine the relation of galectin-3 (Gal-3), a marker of cardiac fibrosis, with incident heart failure (HF) in the community. BACKGROUND: Gal-3 is an emerging prognostic biomarker in HF, and experimental studies suggest that Gal-3 is an important mediator of cardiac fibrosis. Whether elevated Gal-3 concentrations precede the development of HF is unknown. METHODS: Gal-3 concentrations were measured in 3,353 participants in the Framingham Offspring Cohort (mean age 59 years; 53% women). The relation of Gal-3 to incident HF was assessed using proportional hazards regression. RESULTS: Gal-3 was associated with increased left ventricular mass in age-adjusted and sex-adjusted analyses (p = 0.001); this association was attenuated in multivariate analyses (p = 0.06). A total of 166 participants developed incident HF and 468 died during a mean follow-up period of 11.2 years. Gal-3 was associated with risk for incident HF (hazard ratio [HR]: 1.28 per 1 SD increase in log Gal-3; 95% confidence interval [CI]: 1.14 to 1.43; p < 0.0001) and remained significant after adjustment for clinical variables and B-type natriuretic peptide (HR: 1.23; 95% CI: 1.04 to 1.47; p = 0.02). Gal-3 was also associated with risk for all-cause mortality (multivariable-adjusted HR: 1.15; 95% CI: 1.04 to 1.28; p = 0.01). The addition of Gal-3 to clinical factors resulted in negligible changes to the C-statistic and minor improvements in net reclassification improvement. CONCLUSIONS: Higher concentration of Gal-3, a marker of cardiac fibrosis, is associated with increased risk for incident HF and mortality. Future studies evaluating the role of Gal-3 in cardiac remodeling may provide further insights into the role of Gal-3 in the pathophysiology of HF.

Modified citrus pectin reduces galectin-3 expression and disease severity in experimental acute kidney injury.
            (Kolatsi-Joannou et al., 2011) Download
Galectin-3 is a beta-galactoside binding lectin with roles in diverse processes including proliferation, apoptosis, inflammation and fibrosis which are dependent on different domains of the molecule and subcellular distribution. Although galectin-3 is known to be upregulated in acute kidney injury, the relative importance of its different domains and functions are poorly understood in the underlying pathogenesis. Therefore we experimentally modulated galectin-3 in folic acid (FA)-induced acute kidney injury utilising modified citrus pectin (MCP), a derivative of pectin which can bind to the galectin-3 carbohydrate recognition domain thereby predominantly antagonising functions linked to this role. Mice were pre-treated with normal or 1% MCP-supplemented drinking water one week before FA injection. During the initial injury phase, all FA-treated mice lost weight whilst their kidneys enlarged secondary to the renal insult; these gross changes were significantly lessened in the MCP group but this was not associated with significant changes in galectin-3 expression. At a histological level, MCP clearly reduced renal cell proliferation but did not affect apoptosis. Later, during the recovery phase at two weeks, MCP-treated mice demonstrated reduced galectin-3 in association with decreased renal fibrosis, macrophages, pro-inflammatory cytokine expression and apoptosis. Other renal galectins, galectin-1 and -9, were unchanged. Our data indicates that MCP is protective in experimental nephropathy with modulation of early proliferation and later galectin-3 expression, apoptosis and fibrosis. This raises the possibility that MCP may be a novel strategy to reduce renal injury in the long term, perhaps via carbohydrate binding-related functions of galectin-3.

Galectin-3 as a multifunctional protein.
            (Krzeslak and Lipinska, 2004) Download
Galectin-3 is a 31 kDa member of a growing family of beta-galactoside-binding animal lectins. This protein is expressed in a variety of tissues and cell types and is mainly found in the cytoplasm, although, depending on cell type and proliferative state, a significant amount of this lectin can also be detected in the nucleus, on the cell surface or in the extracellular environment. Galectin-3 is secreted from cells by a novel and incompletely understood mechanism that is independent of the classical secretory pathway through the endoplasmic reticulum/Golgi network. Galectin-3 exhibits pleiotropic biological function, playing a key role in many physiological and pathological processes.

Inhibitory effect of modified citrus pectin on liver metastases in a mouse colon cancer model.
            (Liu et al., 2008) Download
AIM: To discuss the expression of glactin-3 in liver metastasis of colon cancer and its inhibition by modified citrus pectin (MCP) in mice. METHODS: Seventy-five Balb/c mice were randomly divided into negative control group (n = 15), positive control group (n = 15), low MCP concentration group (n = 15), middle MCP concentration group (n = 15) and high MCP concentration group (n = 15). CT26 colon cancer cells were injected into the subcapsule of mouse spleen in positive control group, low, middle and high MCP concentrations groups, except in negative control, to set up a colon cancer liver metastasis model. The concentration of MCP in drinking water was 0.0%, 0.0%, 1.0%, 2.5% and 5.0% (wt/vol), respectively. Liver metastasis of colon cancer was observed after 3 wk. Enzyme-linked immunosorbent assay (ELISA) was used to detect the concentration of galectin-3 in serum. Expression of galectin-3 in liver metastasis was detected by immunohistochemistry. RESULTS: Except for the negative group, the percentage of liver metastasis in the other 4 groups was 100%, 80%, 73.3% and 60%, respectively. The number of liver metastases in high MCP concentration group was significantly less than that in positive control group (P = 0.008). Except for the negative group, the median volume of implanted spleen tumor in the other 4 groups was 1.51 cm(3), 0.93 cm(3), 0.77 cm(3) and 0.70 cm(3), respectively. The volume of implanted tumor in middle and high MCP concentration groups was significantly smaller than that in positive control group (P = 0.019; P = 0.003). The concentration of serum galectin-3 in positive control and MCP treatment groups was significantly higher than that in the negative control group. However, there was no significant difference between them. Except for the negative control group, the expression of galectin-3 in liver metastases of the other 4 groups showed no significant difference. CONCLUSION: Expression of galetin-3 increases significantly in liver metastasis of colon cancer, which can be effectively inhibited by MCP.


 

Inhibition of galectin-3 reduces atherosclerosis in apolipoprotein E-deficient mice.
            (MacKinnon et al., 2013) Download
Atherosclerosis is a major risk factor for cardiovascular disease (CVD) and stroke. Galectin-3 is a carbohydrate-binding lectin implicated in the pathophysiology of CVD and is highly expressed within atherosclerotic lesions in mice and humans. The object of this present study was to use genetic deletion and pharmacological inhibition in a well-characterized mouse model of atherosclerosis to determine the role of galectin-3 in plaque development. Apolipoprotein-E/galectin-3 knockout mice were generated and fed a high-cholesterol "western" diet. Galectin-3 deletion had no consistent effect on the serum lipid profile but halved atherosclerotic lesion formation in the thoracic aorta (57% reduction), the aortic arch (50% reduction) and the brachiocephalic arteries. The aortic plaques were smaller, with reduced lipid core and less collagen. In apolipoprotein E-deficient (ApoE(-/-)) mice, there was a switch from high inducible nitric oxide expression in early lesions (6 weeks) to arginase-1 expression in later lesions (20 weeks), which was reversed in ApoE(-/-)/gal-3(-/-) mice. Administration of modified citrus pectin, an inhibitor of galectin-3, during the latter stage of the disease reduced plaque volume. We conclude that inhibiting galectin-3 causes decreased atherosclerosis. Strategies to inhibit galectin-3 function may reduce plaque progression and potentially represent a novel therapeutic strategy in the treatment of atherosclerotic disease.

Inhibition of spontaneous metastasis in a rat prostate cancer model by oral administration of modified citrus pectin.
            (Pienta et al., 1995) Download
BACKGROUND: Prostate cancer is the most common cancer diagnosed in U.S. men and remains incurable once it has metastasized. Many stages of the metastatic cascade involve cellular interactions mediated by cell surface components, such as carbohydrate-binding proteins, including galactoside-binding lectins (galectins). Modified citrus pectin (pH-modified), a soluble component of plant fiber derived from citrus fruit, has been shown to interfere with cell-cell interactions mediated by cell surface carbohydrate-binding galectin-3 molecules. PURPOSE: The aim of this study was to determine whether modified citrus pectin, a complex polysaccharide rich in galactosyl residues, could inhibit spontaneous metastasis of prostate adenocarcinoma cells in the rat. METHODS: The ability of modified citrus pectin to inhibit the adhesion of Dunning rat prostate cancer MAT-LyLu cells to rat endothelial cells was measured by 51Cr-labeling. Modified citrus pectin inhibition of MAT-LyLu cell anchorage-independent growth was measured by colony formation in agarose. The presence of galectin-3 in rat MAT-LyLu cells and human prostate carcinoma was demonstrated by immunoblotting and immunohistochemistry. One million MAT-LyLu cells were injected subcutaneously into the hind limb of male Copenhagen rats on day 0. Rats were given 0.0%, 0.01%, 0.1%, or 1.0% (wt/vol) modified citrus pectin continuously in their drinking water (from day 4 until necropsy on day 30). The number of MAT-LyLu tumor colonies in the lungs were counted. RESULTS: Compared with 15 or 16 control rats that had lung metastases on day 30, seven of 14 rats in the 0.1% and nine of 16 rats in the 1.0% modified citrus-pectin group had statistically significant (two-sided; P < .03 and P < .001, respectively) reductions in lung metastases. The lungs of the 1.0% modified citrus pectin-treated rats had significantly (two-sided; P < .05) fewer metastatic colonies than control groups (9 colonies +/- 4 [mean +/- SE] in the control group compared with 1 colony +/- 1 in the treated group). Modified citrus pectin had no effect on the growth of the primary tumors. In vitro, modified citrus pectin inhibited MAT-LyLu cell adhesion to rat endothelial cells in a time- and dose-dependent manner as well as their colony formation in semisolid medium. CONCLUSIONS: We present a novel therapy in which oral intake of modified citrus pectin acts as a potent inhibitor of spontaneous prostate carcinoma metastasis in the Copenhagen rat. IMPLICATIONS: Further investigations are warranted to determine the following: 1) the role of galectin-3 in normal and cancerous prostate tissues and 2) the ability of modified citrus pectin to inhibit human prostate metastasis in nude mice.

Modulation of the lung colonization of B16-F1 melanoma cells by citrus pectin.
            (Platt and Raz, 1992) Download
CONTEXT: Studies have shown that the galactoside-containing simple sugars and anti-galactoside-binding lectin antibodies may affect experimental tumor cell metastasis. However, the limited number of reagents used thus far necessitate further observations. PURPOSE: Natural citrus pectin (CP) and pH-modified CP (MCP), rich in galactose residues, were used to study the involvement of carbohydrates containing galactoside residues in cellular interaction in vitro and in lung colonization in vivo of B16-F1 melanoma cells. METHODS: B16-F1 melanoma cells were incubated with various concentrations of CP and MCP. Their ability to form homotypic aggregation in vitro and tumor lung colonization in vivo in 8-week-old female C57BL/6 mice was then analyzed. RESULTS: The CP binds to the surface of B16-F1 melanoma cells; this binding can be inhibited by lactose at a concentration of 0.15 M. Intravenous injection of the murine B16-F1 melanoma cells with the natural CP resulted in a significant increase (up to threefold) in the appearance of tumor colonies in the lung and in increased homotypic aggregation properties of the cells, while injection of MCP significantly decreased B16-F1 experimental metastasis (greater than 90%). CONCLUSIONS: Tumor galactoside-binding proteins mediate cellular recognition by linking oligosaccharides with terminal D-galactoside residues on adjacent cells. Successful interference with such a process with MCP may lead to a reduced ability to form tumor cell emboli and metastasis. IMPLICATIONS: These findings imply that the galactose-containing carbohydrate side chains of CP might mimic or compete with the natural ligand(s) of the tumor galactoside-binding protein (gal-lectin) and thus affect cellular interactions relevant for metastasis.


 

References

de Boer, RA, et al. (2012), ‘The fibrosis marker galectin-3 and outcome in the general population.’, J Intern Med, 272 (1), 55-64. PubMedID: 22026577
de Boer, RA, et al. (2014), ‘Galectin-3: a modifiable risk factor in heart failure.’, Cardiovasc Drugs Ther, 28 (3), 237-46. PubMedID: 24789662
Dumic, J, S Dabelic, and M Flogel (2006), ‘Galectin-3: an open-ended story.’, Biochim Biophys Acta, 1760 (4), 616-35. PubMedID: 16478649
Glinskii, OV, et al. (2005), ‘Mechanical entrapment is insufficient and intercellular adhesion is essential for metastatic cell arrest in distant organs.’, Neoplasia, 7 (5), 522-27. PubMedID: 15967104
Glinskii, OV, et al. (2012), ‘Inhibition of prostate cancer bone metastasis by synthetic TF antigen mimic/galectin-3 inhibitor lactulose-L-leucine.’, Neoplasia, 14 (1), 65-73. PubMedID: 22355275
Glinsky, VV and A Raz (2009), ‘Modified citrus pectin anti-metastatic properties: one bullet, multiple targets.’, Carbohydr Res, 344 (14), 1788-91. PubMedID: 19061992
Ho, JE, et al. (2012), ‘Galectin-3, a marker of cardiac fibrosis, predicts incident heart failure in the community.’, J Am Coll Cardiol, 60 (14), 1249-56. PubMedID: 22939561
Kolatsi-Joannou, M, et al. (2011), ‘Modified citrus pectin reduces galectin-3 expression and disease severity in experimental acute kidney injury.’, PLoS One, 6 (4), e18683. PubMedID: 21494626
Krzeslak, A and A Lipinska (2004), ‘Galectin-3 as a multifunctional protein.’, Cell Mol Biol Lett, 9 (2), 305-28. PubMedID: 15213811
Liu, HY, et al. (2008), ‘Inhibitory effect of modified citrus pectin on liver metastases in a mouse colon cancer model.’, World J Gastroenterol, 14 (48), 7386-91. PubMedID: 19109874
MacKinnon, AC, et al. (2013), ‘Inhibition of galectin-3 reduces atherosclerosis in apolipoprotein E-deficient mice.’, Glycobiology, 23 (6), 654-63. PubMedID: 23426722
(2000), ‘Modified citrus pectin-monograph.’, Altern Med Rev, 5 (6), 573-75. PubMedID: 11134980
Pienta, KJ, et al. (1995), ‘Inhibition of spontaneous metastasis in a rat prostate cancer model by oral administration of modified citrus pectin.’, J Natl Cancer Inst, 87 (5), 348-53. PubMedID: 7853416
Platt, D and A Raz (1992), ‘Modulation of the lung colonization of B16-F1 melanoma cells by citrus pectin.’, J Natl Cancer Inst, 84 (6), 438-42. PubMedID: 1538421