Functional structural domain synthesis of anti-pancreatic carcinoma pectin-like polysaccharide RN1.

The great structural and functional diversity supports polysaccharides as favorable candidates for new drug development. Previously we reported that a drug candidate pectin-like natural polysaccharide, RN1 might target galectin-3 (Gal-3) to impede pancreatic cancer cell growth in vivo. However, the quality control of polysaccharide-based drug research faces great challenges due to the heterogeneity. A potential solution is to synthesize structurally identified subfragments of this polysaccharide as alternatives. In this work, we took RN1 as an example, and synthesized five subfragments derived from the putative repeating units of RN1. Among them, pentasaccharide 4 showed an approximative binding affinity to Gal-3 in vitro, as well as an antiproliferative activity against pancreatic BxPC-3 cells comparable to that of RN1. Further, we scaled up pentasaccharide 4 to gram-scale in an efficient synthetic route with a 6.9 % yield from D-galactose. Importantly, pentasaccharide 4 significantly suppressed the growth of pancreatic tumor in vivo. Based on the mechanism complementarity of galactin-3 inhibitor and docetaxel, the combination administration of pentasaccharide 4 and docetaxel afforded better result. The result suggested pentasaccharide 4 was one of the functional structural domains of polysaccharide RN1 and might be a leading compound for anti-pancreatic cancer new drug development.

Isoquercitrin attenuates the progression of non-alcoholic steatohepatitis in mice by modulating galectin-3-mediated insulin resistance and lipid metabolism.

BACKGROUND: Non-alcoholic steatohepatitis (NASH) is a global health problem with no effective treatment. Isoquercitrin (IQ) alters hepatic lipid metabolism and inhibits adipocyte differentiation. The underlying regulatory mechanisms of IQ in regulating insulin resistance (IR) and lipid metabolism remain unclear. PURPOSE: This study was aimed at investigating the effects of IQ on NASH and deciphering whether the underlying mechanisms are via modulation of galectin-3 mediated IR and lipid metabolism. METHODS: IR-HepG2 cell lines were used to demonstrate the ability of IQ to modulate galectin-3-mediated glucose disposal and lipid metabolism. A 20-week high-fat diet (HFD)-induced NASH model was established in C57BL/6J mice, and the protective effect of IQ on lipid disposal in the liver was verified. Further, the mRNA and protein levels of glucose and lipid metabolism were investigated, and lysophosphatidylcholine (LPC) and acylcarnitine (AC) profiling were performed to characterize the changes in endogenous substances associated with mitochondrial function and lipid metabolism in serum and cells. Furthermore, the pharmacokinetic features of IQ were explored in a rat model of NASH. RESULTS: IQ restored liver function and ameliorated inflammation and lipid accumulationin NASH model mice. Notably, significant regulation of the proteins included fatty acid-generating and transporting, cholesterol metabolism enzymes, nuclear transcription factors, mitochondrial metabolism, and IR-related enzymes was noted to be responsible for the therapeutic mechanisms of IQ against experimental NASH. Serum lipid metabolism-related metabolomic assay confirmed that LPC and AC biosynthesis mostly accounted for the therapeutic effect of IQ in mice with NASH and that IQ maintained the homeostasis of LPC and AC levels. CONCLUSION: This is the first study showing that IQ protects against of NASH by modulating galectin-3-mediated IR and lipid metabolism. The mechanisms responsible for liver protection and improved lipid metabolic disorder by IQ may be related to the suppression of IR and regulation of mitochondrial function and lipid metabolism. Galectin-3 down-regulation represents a potentially novel approach for the treatment and prevention of NASH.

The model polysaccharide potato galactan is actually a mixture of different polysaccharides.

Commercially-supplied potato galactan (PG) is widely used as a model polysaccharide in various bioactivity studies. However, results using this galactan are not always consistent with the stated composition. Here, we assessed its composition by fractionating this commercial PG and purified its primary components: PG-A, PG-B and PG-Cp with weight-averaged molecular weights of 430, 93, and 11.3 kDa, respectively. PG-Cp consists of free ß-1,4-galactan chains, whereas PG-A and PG-B are type I rhamnogalacturonans with long ß-1,4-galactan side chains of up to 80 Gal residues and short ß-1,4-galactan side chains of 0 to 3 Gal residues that display a "trees in lawn" pattern. Structures of these polysaccharides correlate well with their activities in terms of galectin-3 binding and gut bacterial growth assays. Our study clarifies the confusion related to commercial PG, with purified fractions serving as better model polysaccharides in bioactivity investigations.

Design, Synthesis, and Anticancer Activity of a Selenium-Containing Galectin-3 and Galectin-9N Inhibitor.

Galectins are soluble ß-D-galactoside-binding proteins whose implication in cancer progression and disease outcome makes them prominent targets for therapeutic intervention. In this frame, the development of small inhibitors that block selectively the activity of galectins represents an important strategy for cancer therapy which is, however, still relatively underdeveloped. To this end, we designed here a rationally and efficiently novel diglycosylated compound, characterized by a selenoglycoside bond and the presence of a lipophilic benzyl group at both saccharide residues. The relatively high binding affinity of the new compound to the carbohydrate recognition domain of two galectins, galectin 3 and galectin 9, its good antiproliferative and anti-migration activity towards melanoma cells, as well as its anti-angiogenesis properties, pave the way for its further development as an anticancer agent.

The Complex Biological Effects of Pectin: Galectin-3 Targeting as Potential Human Health Improvement?

Galectin-3 is the only chimeric representative of the galectin family. Although galectin-3 has ubiquitous regulatory and physiological effects, there is a great number of pathological environments where galectin-3 cooperatively participates. Pectin is composed of different chemical structures, such as homogalacturonans, rhamnogalacturonans, and side chains. The study of pectin's major structural aspects is fundamental to predicting the impact of pectin on human health, especially regarding distinct molecular modulation. One of the explored pectin's biological activities is the possible galectin-3 protein regulation. The present review focuses on revealing the structure/function relationship of pectins, their fragments, and their biological effects. The discussion highlighted by this review shows different effects described within in vitro and in vivo experimental models, with interesting and sometimes contradictory results, especially regarding galectin-3 interaction. The review demonstrates that pectins are promissory food-derived molecules for different bioactive functions. However, galectin-3 inhibition by pectin had been stated in literature before, although it is not a fully understood, experimentally convincing, and commonly agreed issue. It is demonstrated that more studies focusing on structural analysis and its relation to the observed beneficial effects, as well as substantial propositions of cause and effect alongside robust data, are needed for different pectin molecules' interactions with galectin-3.

Tanshinone IIA alleviates cardiac hypertrophy through m6A modification of galectin-3.

Cardiac hypertrophy results from the adaptive response of the myocardium to pressure overload on the heart. Tanshinone IIA (Tan IIA) is the major active compound extracted from Salvia miltiorrhiza Bunge, which possesses various pharmacological benefits. In the present study, the effect and mechanism of action of Tan IIA on cardiac hypertrophy were studied. Ang II-induced and transverse aortic constriction (TAC)-induced cardiomyocyte hypertrophy models were used to evaluate the effect of Tan IIA. An adenoviral vector system was utilized to overexpress galectin-3. The results revealed that Tan IIA significantly inhibited Ang II-induced hypertrophy in vitro and TAC-induced cardiac hypertrophy in vivo. Furthermore, Tan IIA notably inhibited the expression of galectin-3. Rescue experiments indicated that galectin-3 overexpression reversed the effects of Tan IIA, which further validated the interaction between Tan IIA and galectin-3. Additionally, Tan IIA suppressed alkB homolog 5, RNA demethylase (ALKBH5)-mediated N6-methyladenosine (m6A) modification of galectin-3. In summary, the results of the present study indicated that Tan IIA attenuates cardiac hypertrophy by targeting galectin-3, suggesting that galectin-3 plays a critical role in cardiac hypertrophy and represents a new therapeutic target.

Human Sensory Neuron-like Cells and Glycated Collagen Matrix as a Model for the Screening of Analgesic Compounds.

Increased collagen-derived advanced glycation end-products (AGEs) are consistently related to painful diseases, including osteoarthritis, diabetic neuropathy, and neurodegenerative disorders. We have recently developed a model combining a two-dimensional glycated extracellular matrix (ECM-GC) and primary dorsal root ganglion (DRG) that mimicked a pro-nociceptive microenvironment. However, culturing primary cells is still a challenge for large-scale screening studies. Here, we characterized a new model using ECM-GC as a stimulus for human sensory-like neurons differentiated from SH-SY5Y cell lines to screen for analgesic compounds. First, we confirmed that the differentiation process induces the expression of neuron markers (MAP2, RBFOX3 (NeuN), and TUBB3 (ß-III tubulin), as well as sensory neuron markers critical for pain sensation (TRPV1, SCN9A (Nav1.7), SCN10A (Nav1.8), and SCN11A (Nav1.9). Next, we showed that ECM-GC increased c-Fos expression in human sensory-like neurons, which is suggestive of neuronal activation. In addition, ECM-GC upregulated the expression of critical genes involved in pain, including SCN9A and TACR1. Of interest, ECM-GC induced substance P release, a neuropeptide widely involved in neuroinflammation and pain. Finally, morphine, the prototype opiate, decreased ECM-GC-induced substance P release. Together, our results suggest that we established a functional model that can be useful as a platform for screening candidates for the management of painful conditions.

Pectic polysaccharide from Smilax china L. ameliorated ulcerative colitis by inhibiting the galectin-3/NLRP3 inflammasome pathway.

Ulcerative colitis (UC) is an inflammatory bowel disease that affects the colon and rectum. Although galectin-3 (Gal-3) has been reported to play a proinflammatory role in UC, it is unknown whether pectic polysaccharide, a Gal-3 inhibitor in tumor metastasis, can alleviate UC by inhibiting Gal-3. The aim of this study was to investigate the anti-inflammatory effects and underlying mechanisms of SCLP, a pectic polysaccharide purified from Smilax china L. in our previous work, on dextran sulfate sodium-induced UC in BALB/c mice. The results showed that SCLP could significantly improve symptoms, alleviate histopathological damage and reduce the secretion of inflammatory mediators in mice with UC. Analysis of the anti-colitis mechanisms indicated that SCLP could inhibit the Gal-3/NLRP3 inflammasome/IL-1ß pathway by suppressing the expression of Gal-3 and the interaction of Gal-3 and NLRP3. Our results suggested that SCLP could be a promising candidate for prevention and treatment of UC.

Modified citrus pectin prevents isoproterenol-induced cardiac hypertrophy associated with p38 signalling and TLR4/JAK/STAT3 pathway.

Modified citrus pectin (MCP) is a specific inhibitor of galectin-3 (Gal-3) that is regarded as a new biomarker of cardiac hypertrophy, but its effect is unclear. The aim of this study is to investigate the role and mechanism of MCP in isoproterenol (ISO)-induced cardiac hypertrophy. Rats were injected with ISO to induce cardiac hypertrophy and treated with MCP. Cardiac function was detected by ECG and echocardiography. Pathomorphological changes were evaluated by the haematoxylin eosin (H&E) and wheat germ agglutinin (WGA) staining. The hypertrophy-related genes for atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and ß-myosin heavy chain (ß-MHC), and the associated signal molecules were analysed by qRT-PCR and western blotting. The results show that MCP prevented cardiac hypertrophy and ameliorated cardiac dysfunction and structural disorder. MCP also decreased the levels of ANP, BNP, and ß-MHC and inhibited the expression of Gal-3 and Toll-like receptor 4 (TLR4). Additionally, MCP blocked the phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3), but it promoted the phosphorylation of p38. Thus, MCP prevented ISO-induced cardiac hypertrophy by activating p38 signalling and inhibiting the Gal-3/TLR4/JAK2/STAT3 pathway.

Gentianella acuta prevents acute myocardial infarction induced by isoproterenol in rats via inhibition of galectin-3/TLR4/MyD88/NF-кB inflammatory signalling.

Gentianella acuta (G. acuta), as a folk medicine, was used to treat heart disease by the Ewenki people in Inner Mongolia. However, the effect of G. acuta on acute myocardial infarction (AMI) is not clear. To explore the mechanisms of G. acuta on isoproterenol (ISO)-induced AMI, rats were administered G. acuta for 28 days, then injected intraperitoneally with ISO (85 mg/kg) on days 29 and 30. An electrocardiogram helped to evaluate the myocardial injury. Serum lactate dehydrogenase (LDH), creatinine kinase (CK) and aspartate aminotransferase (AST) levels were evaluated, and haematoxylin eosin, Masson's trichrome staining and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) staining were used to detect myocardial histological changes. Radioimmunoassay was used to measure serum tumour necrosis factor alpha (TNFα) and interleukin (IL)-6. An enzyme-linked immunosorbent assay kit was used to analyse serum galectin-3 (Gal-3) levels. Immunohistochemistry, Western blotting and reverse transcription polymerase chain reaction were used to examine relevant molecular events. The results revealed that pre-treatment with G. acuta decreased the elevation in the ST segment; reduced serum LDH, CK and AST levels; alleviated cardiac structure disorder; and reduced inflammatory infiltration, abnormal collagen deposition and cardiomyocyte apoptosis that were induced by ISO. Furthermore, pre-treatment with G. acuta inhibited serum Gal-3 levels and Gal-3 expression in heart tissue, and also impeded TLR4/MyD88/NF-кB signalling activation, which ultimately prevented the expression of inflammatory cytokines. The study indicated that pre-treatment with G. acuta protects against ISO-induced AMI, and the protective role may be related to inhibiting Gal-3/TLR4/MyD88/NF-кB inflammatory signalling.

Roles of galectin­3 in the tumor microenvironment and tumor metabolism (Review).

Galectin­3 is expressed in various tissues and plays an important role in the tumor microenvironment (TME). Galectin­3 has been found to be overexpressed in a variety of cancers and is associated with tumor progression and metastasis. Over the past decades, emerging evidence has suggested that the TME may induce galectin­3 expression to maintain cellular homeostasis and promote cell survival. Furthermore, galectin­3 regulates immune cell function to promote tumor­driven immunosuppression through several mechanisms. In the TME, intracellular and extracellular galectin­3 has different functions. In addition, it has been reported that galectin­3 is associated with glycolysis and mitochondrial metabolism in tumors, and it is involved in the regulation of relevant signaling pathways, thus promoting cancer cell survival via adapting to the TME. The aim of the present review was to summarize the current knowledge on galectin­3 production and its function in the TME, its effect on TME immunosuppression, its association with tumor metabolism and relevant signaling pathways, and to report common types of cancer in which galectin­3 is highly expressed, in order to ensure a comprehensive understanding of the critical effects of galectin­3 on tumor progression and metastasis.

Low methyl-esterified pectin protects pancreatic ß-cells against diabetes-induced oxidative and inflammatory stress via galectin-3.

Insufficient intake of dietary fibers in Western societies is considered a major contributing factor in the high incidence rates of diabetes. The dietary fiber pectin has been suggested to be beneficial for management of both Diabetes Type 1 and Type 2, but mechanisms and effects of pectin on insulin producing pancreatic ß-cells are unknown. Our study aimed to determine the effects of lemon pectins with different degree of methyl-esterification (DM) on ß-cells under oxidative (streptozotocin) and inflammatory (cytokine) stress and to elucidate the underlying rescuing mechanisms, including effects on galectin-3. We found that specific pectins had rescuing effects on toxin and cytokine induced stress on ß-cells but effects depended on the pectin concentration and DM-value. Protection was more pronounced with low DM5 pectin and was enhanced with higher pectin-concentrations. Our findings show that specific pectins might prevent diabetes by making insulin producing ß-cells less susceptible for stress.

Galectin-3 inhibition attenuates doxorubicin-induced cardiac dysfunction by upregulating the expression of peroxiredoxin-4.

Doxorubicin (DOX) is a highly efficient chemotherapeutic drug limited by its cardiotoxicity. Galectin-3 (Gal-3) overexpression is associated with several cardiovascular diseases. In this study, the in vivo models of DOX-treated rats and the in vitro model of DOX-treated H9C2 cells were used. DOX induced cardiac injury and dysfunction accompanied with the upregulation of Gal-3 at the end of the experiment, while inhibition of Gal-3 with modified citrus pectin (MCP) exhibited a dramatic improvement in cardiac function of the DOX-treated rats, as manifested by increased left ventricular systolic pressure and ±dp/dtmax and decreased left ventricular end-diastolic pressure. The plasma levels of myocardial injury markers such as lactate dehydrogenase, creatine kinase, creatine kinase-MB, and cardiac troponin I were decreased after MCP treatment. In parallel, MCP attenuated myocardial tissue markers of oxidative stress such as hydrogen peroxide and malondialdehyde restored the activities of superoxide dismutase, catalase, and glutathione peroxidase and upregulated antioxidant peroxiredoxin-4 (Prx-4). To further verify the role of Prx-4, it was downregulated by siRNA-mediated knockdown in H9C2 cells. MCP could not reverse DOX-induced oxidative stress in Prx-4-knock-down cells. In conclusion, Gal-3 mediated DOX-induced cardiotoxicity and Gal-3 inhibition attenuated DOX-induced cardiac dysfunction by upregulating the expression of Prx-4 to reduce myocardial oxidative stress.

Galectin-3 expression and secretion by tumor-associated macrophages in hypoxia promotes breast cancer progression.

Tumor-associated macrophages (TAMs) have been shown to be associated with poor prognosis of cancer and are predominately localized in the hypoxia regions of tumor. We demonstrated in this study that hypoxia increases the synthesis and secretion of galectin-3 by TAMs. The increased expression of galectin-3 in TAMs was seen to be associated with nucleation of transcription factor NF-κB through generation and activation of ROS and promoted tumor growth and metastasis in vitro and in mice through multiple molecular mechanisms. It was found that the TAMs-mediated promotion of tumor growth and metastasis in hypoxia was inhibited by administration of macrophage-depletion agent clodronate liposomal (CL) or galectin-3 inhibitor modified citric pectin (MCP) in orthotopic syngeneic mammary adenocarcinoma model and metastasis model. Co-administration of anti-angiogenesis agent sorafenib or bevacizumab with CL and MCP showed to cause stronger inhibition of tumor growth and metastasis than administration of each agent alone. These results indicate that hypoxia-induced galectin-3 expression and secretion from TAMs promotes tumor growth and metastasis. Targeting the actions of galectin-3 in hypoxia may be a potential therapeutic strategy for cancer treatment.

Modified citrus pectin ameliorates myocardial fibrosis and inflammation via suppressing galectin-3 and TLR4/MyD88/NF-κB signaling pathway.

Myocardial fibrosis (MF) plays a key role in the development and progression of heart failure (HF) with limited effective therapies. Galectin-3 (Gal-3) is a biomarker associated with fibrosis and inflammation in patients with HF. The Gal-3 inhibitor modified citrus pectin (MCP) protects against cardiac dysfunction, though the underlying mechanism remains unclear. The aim of this study was to investigate the effect and mechanism of MCP on MF using an isoproterenol (ISO)-induced rat model of HF. Cardiac function was analyzed by echocardiography and electrocardiography. Histopathological changes in the heart tissue were assessed by hematoxylin-eosin and Masson trichrome staining. The mRNA and protein expression levels of signaling molecules and pro-inflammatory cytokines were monitored by immunohistochemistry, western blot, qRT-PCR and ELISA analyses. The results demonstrated that MCP ameliorated cardiac dysfunction, decreased myocardial injury and reduced collagen deposition. Furthermore, MCP downregulated the expression of Gal-3, TLR4 and MyD88, thereby inhibiting NF-κB-p65 activation. MCP also decreased the expression of IL-1ß, IL-18 and TNF-α, which have been implicated in the pathogenesis of HF. These inhibitory effects were observed on day 15 and continued until day 22. Taken together, these results suggest that MCP ameliorates cardiac dysfunction through inhibiting inflammation and MF. These effects may be through downregulating Gal-3 expression and suppressing activation of the TLR4/MyD88/NF-κB signaling pathway. The present study supports the use of Gal-3 as a therapeutic target for the treatment of MF after myocardial infarction.

Plant-derived saccharides and their inhibitory potential on metastasis associated cellular processes of pancreatic ductal adenocarcinoma cells.

This study intends to investigate the inhibitory potential of different plant derived saccharides on cell migration and adhesion of pancreatic ductal adenocarcinoma (PDAC) cells to microvascular liver endothelium, particularly considering the role of transmembranous galectin-3. PDAC cell lines PancTu1 and Panc1 were characterized by considerable (transmembranous) galectin-3 (Gal3) expression. SiRNA mediated Gal3 knockdown as well as treatment with differentially processed pectins and arabinogalactan-proteins (AGPs) did not impact on cell migration of either PDAC cell line. In contrast, Gal3 knockdown reduced adhesion of PDAC cells to the liver endothelial cell line TMNK-1 being more pronounced in Panc1 cells. Similarly, plant derived substances did not impact cell adhesion of PancTu1 cells while partially hydrolyzed citrus pectin (MCP), pectinase-treated MCP (MCPPec) and partially hydrolized AGP (AGPTFA) clearly diminished adhesive properties of Panc1 cells. MCPPec or AGPTFA could not further intensify the adhesion reducing effect of galectin-3 knockdown, indicating that these plant derived polysaccharides are able to inhibit PDAC cell adhesion to liver endothelial cells in a galectin-3 dependent manner. Overall, these data suggest an inhibitory potential of plant derived processed saccharides which have undergone chemical modification in impairing PDAC cell adhesion to liver endothelium.

Effects of Belapectin, an Inhibitor of Galectin-3, in Patients With Nonalcoholic Steatohepatitis With Cirrhosis and Portal Hypertension.

BACKGROUND & AIMS: Increased levels of galectin 3 have been associated with nonalcoholic steatohepatitis (NASH) and contribute to toxin-induced liver fibrosis in mice. GR-MD-02 (belapectin) is an inhibitor of galectin 3 that reduces liver fibrosis and portal hypertension in rats and was safe and well tolerated in phase 1 studies. We performed a phase 2b, randomized trial of the safety and efficacy of GR-MD-02 in patients with NASH, cirrhosis, and portal hypertension. METHODS: Patients with NASH, cirrhosis, and portal hypertension (hepatic venous pressure gradient [HVPG] ≥ 6 mm Hg) from 36 centers were randomly assigned, in a double-blind manner, to groups that received biweekly infusions of belapectin 2 mg/kg (n = 54), 8 mg/kg (n = 54), or placebo (n = 54) for 52 weeks. The primary endpoint was change in HVPG (Δ HVPG) at the end of the 52-week period compared with baseline. Secondary endpoints included changes in liver histology and development of liver-related outcomes. RESULTS: We found no significant difference in ΔHVPG between the 2 mg/kg belapectin group and placebo group (-0.28 mm HG vs 0.10 mm HG, P = 1.0) or between the 8 mg/kg belapectin and placebo group (-0.25 mm HG vs 0.10 mm HG, P = 1.0). Belapectin had no significant effect on fibrosis or nonalcoholic fatty liver disease activity score, and liver-related outcomes did not differ significantly among groups. In an analysis of a subgroup of patients without esophageal varices at baseline (n = 81), 2 mg/kg belapectin was associated with a reduction in HVPG at 52 weeks compared with baseline (P = .02) and reduced development of new varices (P = .03). Belapectin (2 mg/kg) was well tolerated and produced no safety signals. CONCLUSIONS: In a phase 2b study of 162 patients with NASH, cirrhosis, and portal hypertension, 1 year of biweekly infusion of belapectin was safe but not associated with significant reduction in HVPG or fibrosis compared with placebo. However, in a subgroup analysis of patients without esophageal varices, 2 mg/kg belapectin did reduce HVPG and development of varices. ClinicalTrials.gov number: NCT02462967.

Pectin-rich extracts from olives inhibit proliferation of Caco-2 and THP-1 cells.

Three olive modified pectin extracts have been produced by heat and acid treatment of the major by-product of olive oil production. Their effect on proliferation of the colon carcinoma Caco-2 and the leukemia monocytic THP-1 cell lines has been studied in order to determine possible anti-tumor properties. All extracts inhibited proliferation at some of the concentrations ranging from 1 to 10 mg ml-1. Interestingly none of the extracts inhibited the growth of confluent Caco-2 cells, showing the specificity of the antiproliferative effect for the transformed Caco-2 phenotype. All the extracts inhibited agglutination of red blood cells by galectin-3, a lectin involved in tumor growth, metastasis, and immune cell regulation that has been proposed as a mediator of the anti-tumor effects of modified pectins. In addition, activation of caspase-3 in THP-1 cells indicates that treatment with the pectin-rich extracts triggers apoptosis. These results point to a possible use as health-promoting food ingredients or supplements.

Disruption of galectin-3 and galectin-3 binding protein (G3BP) interaction by dietary pectic polysaccharides (DPP) - Arrest of metastasis, inhibition of proliferation and induction of apoptosis.

Galectin-3 and galectin-3 binding proteins (G3BP) are implicated as key players in metastasis. In the current study, we evaluated the effect of pectic polysaccharides on galectin-3 and G3BP mediated metastasis in vitro (cells) and in vivo (tissues). In vitro study (double immunostaining) confirms the presence of galectin-3 on the cell surface and G3BP in the interlinking region of the cells confirming the role of G3BP in bridging galectin-3 molecules. Dietary carrot (Daucus carota) pectic polysaccharide (CRPP) blocked the expression of galectin-3 and G3BP more effectively (80%), whereas the expressions were reduced to 60% upon treatment with swallow root (Decalepis hamiltonii) pectic polysaccharide (SRPP), ß­carotene and deferoxamine (antiproliferative drug). Ginger (Gingiber officinale) pectic polysaccharide (GRPP) showed only 20% reduction. CRPP reduced 80% of tumor incidence followed by cyclophosphamide - a chemotherapeutic drug (77%), SRPP (67%) and GRPP (45%). Further 3-5 folds reduction in galectin-3/G3BP expression followed by infiltration of macrophages into the deeper layer of the skin by CRPP and SRPP suggested the anticancer property via immunomodulation. Surface Plasmon Resonance (SPR) studies confirm galectin-3 and G3BP interaction, which are disrupted during the treatment with dietary pectic polysaccharides (DPP) (Supplementary Scheme-1). Overall data demonstrate the role of DPPs as potential anticancer alternatives.

Pectasol-C Modified Citrus Pectin targets Galectin-3-induced STAT3 activation and synergize paclitaxel cytotoxic effect on ovarian cancer spheroids.

Here we sought to determine the relationship between STAT3 activity and Galectin-3 (Gal-3) and to investigate the cytotoxic effect of PectaSol-C Modified Citrus Pectin (Pect-MCP) as a specific competitive inhibitor of Galectin-3 (Gal-3) in combination with Paclitaxel (PTX) to kill the ovarian cancer cell SKOV-3 multicellular tumor spheroid (MCTS). To this order, SKOV-3 cells in 2D and 3D cultures were treated with exogenous Gal-3 for the assessment of STAT3 activity. Two-way ANOVA main effect and IC50 of each drug Paclitaxel (PTX) and Pect-MCP or in combination were obtained from MTT assay results. The phosphorylated STAT3 levels, migration, invasion, integrin mRNA and p-AKTser473 levels were assessed in the absence or presence of each drug alone or in combination. Gal-3 expression levels were assessed in human serous ovarian cancer (SOC) specimens and its correlation with different integrin mRNA levels was further assessed. Our results showed that Gal-3 expression level was significantly increased in MCTS compared to monolayer SKOV-3 cells which triggered STAT3 phosphorylation. Moreover, Pect-MCP synergized with PTX to kill SKOV3 MCTS through abrogation of STAT3 activity and reduced expression of its downstream target HIF-1α, reduced integrin mRNA levels, and subsequently decreased AKT activity. There were higher expression levels of Gal-3 in human high-grade SOC specimens compared to the normal ovary and borderline SOC which positively and significantly correlated with α5, ß2 and ß6 integrin mRNA levels. Together, these results revealed for the first time that Pect-MCP could be considered as a potential drug to enhance the PTX effect on ovarian cancer cells MCTS through inhibition of STAT3 activity.