Hypoxia Up-Regulates Galectin-3 in Mammary Tumor Progression and Metastasis

Interactions of SNPs in Folate Metabolism Related Genes on Prostate Cancer Aggressiveness in European Americans and African Americans

Background: Studies showed that folate and related single nucleotide polymorphisms (SNPs) could predict prostate cancer (PCa) risk. However, little is known about the interactions of folate-related SNPs associated with PCa aggressiveness. The study’s objective is to evaluate SNP–SNP interactions among the DHFR 19-bp polymorphism and 10 SNPs in folate metabolism and the one-carbon metabolism pathway associated with PCa aggressiveness. Methods: We evaluated 1294 PCa patients, including 690 European Americans (EAs) and 604 African Americans (AAs). Both individual SNP effects and pairwise SNP–SNP interactions were analyzed. Results: None of the 11 individual polymorphisms were significant for EAs and AAs. Three SNP–SNP interaction pairs can predict PCa aggressiveness with a medium to large effect size. For the EA PCa patients, the interaction between rs1801133 (MTHFR) and rs2236225 (MTHFD1), and rs1801131 (MTHFR) and rs7587117 (SLC4A5) were significantly associated with aggressive PCa. For the AA PCa patients, the interaction of DHFR-19bp polymorphism and rs4652 (LGALS3) was significantly associated with aggressive PCa. Conclusions: These SNP–SNP interactions in the folate metabolism-related genes have a larger impact than SNP individual effects on tumor aggressiveness for EA and AA PCa patients. These findings can provide valuable information for potential biological mechanisms of PCa aggressiveness.

HIF1A overexpression predicts the high lymph node metastasis risk and indicates a poor prognosis in papillary thyroid cancer

Objective

To investigate the value of Hypoxia-inducible factor 1 A (HIF1A) in predicting lymph node metastasis (LNM) stage and clinical outcomes of papillary thyroid cancer (PTC) patients.

Materials and methods

The HIF1A gene expression analysis in PTC was performed by bioinformatics approaches followed by evaluating its protein level using immunohistochemistry analysis. The role of HIF1A in predicting the LNM stage was evaluated by logistic regression analysis, nomogram construction, and receiver operating characteristic (ROC) analysis. We performed survival analyses to determine its prognostic value. Enrichment analysis was conducted, and immune cell infiltration and stromal content were evaluated to examine the underlying mechanism of HIF1A in PTC.

Results

HIF1A transcription and protein levels were significantly high in PTC tissue (P < 0.05). Its overexpression predicted high LNM risk and unfavorable prognosis for PTC patients (P < 0.05). Cox regression analysis revealed HIF1A as an independent prognostic biomarker for the disease-free interval (DFI) (P < 0.01). In addition, HIF1A was positively related to tumor-suppressive immunity but was negatively correlated with anti-tumor immunity. HIF1A upregulation was also associated with increased stromal content.

Conclusions

HIF1A overexpression is an independent predictor for worse DFI in PTC. The HIF1A expression may affect the prognosis of PTC patients through immune- and stroma-related pathways. Our study provides new insight into the role of HIF1A in PTC biology and clinical management.

Galectins and galectin-mediated autophagy regulation: new insights into targeted cancer therapy

Galectins are animal lectins with specific affinity for galactosides via the conserved carbohydrate recognition domains. Increasing studies recently have identified critical roles of galectin family members in tumor progression. Abnormal expression of galectins contributes to the proliferation, metastasis, epithelial-mesenchymal transformation (EMT), immunosuppression, radio-resistance and chemoresistance in various cancers, which has attracted cumulative clinical interest in galectin-based cancer treatment. Galectin family members have been reported to participate in autophagy regulation under physiological conditions and in non-tumoral diseases, and implication of galectins in multiple processes of carcinogenesis also involves regulation of autophagy, however, the relationship between galectins, autophagy and cancer remains largely unclear. In this review, we introduce the structure and function of galectins at the molecular level, summarize their engagements in autophagy and cancer progression, and also highlight the regulation of autophagy by galectins in cancer as well as the therapeutic potentials of galectin and autophagy-based strategies. Elaborating on the mechanism of galectin-regulated autophagy in cancers will accelerate the exploitation of galectins-autophagy targeted therapies in treatment for cancer.

Galectins as pivotal components in oncogenesis and immune exclusion in human malignancies

Galectins are galactoside-binding proteins, exerting numerous functions inside and outside the cell, particularly conferring adaptation to stress factors. For most of them, aberrant expression profiles have been reported in the context of cancer. Albeit not being oncogenic drivers, galectins can be harnessed to exacerbate the malignant phenotype. Their impact on disease establishment and progression is not limited to making cancer cells resistant to apoptosis, but is prominent in the context of the tumor microenvironment, where it fosters angiogenesis, immune escape and exclusion. This review focuses mainly on Gal-1, Gal-3 and Gal-9 for which the involvement in cancer biology is best known. It presents the types of galectin dysregulations, attempts to explain the mechanisms behind them and analyzes the different ways in which they favor tumour growth. In an era where tumour resistance to immunotherapy appears as a major challenge, we highlight the crucial immunosuppressive roles of galectins and the potential therapeutic benefits of combinatorial approaches including galectin inhibition.

Plasma galectins and metabolites in advanced head and neck carcinomas: evidence of distinct immune characteristics linked to hypopharyngeal tumors

Extra-cellular galectins 1, 3 and 9 (gal-1, -3 and -9) are known to act as soluble immunosuppressive agents in various malignancies. Previous publications have suggested that their expression is dependent on the metabolic status of producing cells and reciprocally that they can influence metabolic pathways in their target cells. Very little is known about the status of gal-1, -3 and -9 in patients bearing head and neck squamous cell carcinomas (HNSCC) and about their relationships with the systemic metabolic condition. This study was conducted in plasma samples from a prospective cohort of 83 HNSCC patients with advanced disease. These samples were used to explore the distribution of gal-1, -3 and -9 and simultaneously to profile a series of 87 metabolites assessed by mass spectrometry. We identified galectin and metabolic patterns within five disease categories defined according to the primary site and human papillomavirus (HPV) status (HPV-positive and -negative oropharyngeal carcinomas, carcinomas of the oral cavity, hypopharynx and larynx carcinomas). Remarkably, samples related to hypopharyngeal carcinomas displayed the highest average concentration of gal-9 (p = .017) and a trend toward higher concentrations of kynurenine, a potential factor of tumor growth and immune suppression. In contrast, there was a tendency toward higher concentrations of fatty acids in samples related to oral cavity. These observations emphasize the diversity of HPV-negative HNSCCs. Depending on their primary site, they evolve into distinct types of immune and metabolic landscapes that seem to be congruent with specific oncogenic mechanisms.

Galectin-3 as a biomarker in breast neoplasms: Mechanisms and applications in patient care

Galectin-3 is a member of the lectin family encoded by the LGALS3 gene on chromosome 14. It is secreted by a wide range of immune cells and mammary tumor cells. Through its activity on the tumor microenvironment, in particular on tumor-infiltrating leukocytes, galectin-3 improves the proliferation, survival, and colonizing ability of mammary neoplastic cells. Consequently, galectin-3 expression in the tumor microenvironment could worsen therapeutic outcomes of breast neoplasms and become a biomarker and a therapeutic target in combined immunotherapy in breast neoplasms. There is a limited amount of information that is available on galectin-3 in breast cancer in Africa. In this review, we analyze how galectin-3 influences the tumor microenvironment and its potential as a biomarker and therapeutic target in breast neoplasms. We aim to emphasize the significance of investigating galectin-3 in breast neoplasms in Africa based on the results of studies conducted elsewhere.

Modified citrus pectin inhibits breast cancer development in mice by targeting tumor-associated macrophage survival and polarization in hypoxic microenvironment

Large amounts of tumor-associated macrophages (TAM), which are predominately localized in hypoxia area of the tumor tissue, are associated with the malignant progression of the tumor. In the present study, we investigated the inhibitory effects of modified citrus pectin (MCP), a natural dietary polysaccharide, on the survival and polarization of TAM in relation to its inhibition on the growth and migration of breast cancer. M2 macrophages polarized from human monocyte THP-1 were chosen as a model for TAM. We showed that MCP (0.06%-1%) concentration-dependently suppressed the survival of TAM through inhibiting glucose uptake with a greater extent in hypoxia than in normoxia. Furthermore, MCP treatment decreased ROS level in TAM through its reducibility and inhibiting galectin-3 expression, leading to inhibition of glucose transporter-1 expression and glucose uptake. In addition, MCP suppressed M2-like polarization via inhibiting STAT3 phosphorylation. Moreover, the tumor-promoting effect of TAM could be restrained by MCP treatment as shown in human breast cancer MDA-MB-231 cells in vitro and in mouse breast cancer 4T1-luc orthotopic and metastasis models. In both tumor tissue and lung tissue of the mouse tumor models, the number of TAM was significantly decreased after MCP treatment. Taken together, MCP may be a promising agent for targeting TAM in tumor hypoxic microenvironment for breast cancer treatment.

Application of the anthraquinone drug rhein as an axial ligand in bifunctional Pt(IV) complexes to obtain antiproliferative agents against human glioblastoma cells

Octahedral Pt(IV) prodrugs are an effective way to combine cisplatin-like moieties and a second drug to obtain selective and stimuli responsive bifunctional antiproliferative compounds. Recently, two bifunctional Pt(IV) complexes have shown interesting in vitro and in vivo effects in glioblastoma, the most aggressive primary brain tumor. An interesting observation indicates that 4,5-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid (rhein) can inhibit in vivo glioma tumor progression. Furthermore, a prodrug in which cisplatin was combined with two molecules of rhein showed a potency higher than that of cisplatin toward cisplatin-resistant lung carcinoma cells. However, the high lipophilicity of this type of complex affects their solubility and bioavailability. To overcome these limits, in the present work, three Pt(IV) derivatives were obtained by differently linking one molecule of rhein and one acetato ligand at the axial position to a cisplatin core. The complexes proved to be similar to or more potent than the parent cisplatin and rhein, and the reference drug temozolomide on two human glioblastoma cell lines (U87-MG and T98G). They retained their activity under hypoxia and caused a significant reduction in the motility of both cell lines, which can be related to their ability to inhibit MMP2 and MMP9 matrix metalloproteinases. Finally, physicochemical and computational studies indicated that these Pt(IV) derivatives are more prone than rhein to cross the blood-brain barrier.

Anti-cancer impact of Hypericin in B-CPAP cells: Extrinsic caspase dependent apoptosis induction and metastasis obstruction

Thyroid cancer is the most common type of endocrine-related cancer. According to the literature, its incidence is not very high, but its rate increasing especially in developed countries. With this regard, finding approaches to prevent, and exert anti-tumor activity with the least side effects on the normal cells at the next step after diagnosis is demanded. Herbal medicine is a branch of integrative oncology that seems to be a practically beneficial goddess for cancer treatment in many cases. Here we utilized Hypericin (HYP) to investigate its anti-tumor (apoptotic and anti-metastatic) activity on B-CPAP (a thyroid cancer cell line) and cytotoxicity on TPC-1 (thyroid cancer cell line with wild type TP53) cell lines. To assess whether HYP may exert preventive and anti-tumor effects and does not have a potential side effect, we dubbed the experiments on the fibroblast cells (as a normal cell line). Cytotoxicity and kind of cellular death were examined by MTT and AnnexinV/PI respectively. Extrinsic/intrinsic apoptosis pathway induction was clarified by western blotting on pro/cleaved caspases 9, 8, and 3. According to our data HYP induces an extrinsic apoptosis pathway and no other types (necroptosis, necrosis, etc.) in B-CPAP cells. Moreover, CDH1 mRNA expression calculated to be up-regulated, and that of LGALS3 down-regulated in the B-CPAP cell line after treatment. Besides tumor cytotoxic activity, we suggest that HYP impedes with invasion and/or metastasis process.

Galectin-3: A factotum in carcinogenesis bestowing an archery for prevention

Cancer metastasis and therapy resistance are the foremost hurdles in oncology at the moment. This review aims to pinpoint the functional aspects of a unique multifaceted glycosylated molecule in both intracellular and extracellular compartments of a cell namely galectin-3 along with its metastatic potential in different types of cancer. All materials reviewed here were collected through the search engines PubMed, Scopus, and Google scholar. Among the 15 galectins identified, the chimeric gal-3 plays an indispensable role in the differentiation, transformation, and multi-step process of tumor metastasis. It has been implicated in the molecular mechanisms that allow the cancer cells to survive in the intravascular milieu and promote tumor cell extravasation, ultimately leading to metastasis. Gal-3 has also been found to have a pivotal role in immune surveillance and pro-angiogenesis and several studies have pointed out the importance of gal-3 in establishing a resistant phenotype, particularly through the epithelial-mesenchymal transition process. Additionally, some recent findings suggest the use of gal-3 inhibitors in overcoming therapeutic resistance. All these reports suggest that the deregulation of these specific lectins at the cellular level could inhibit cancer progression and metastasis. A more systematic study of glycosylation in clinical samples along with the development of selective gal-3 antagonists inhibiting the activity of these molecules at the cellular level offers an innovative strategy for primary cancer prevention.

Targeting galectins in T cell-based immunotherapy within tumor microenvironment

Over the past few years, tumor immunotherapy has emerged as an innovative tumor treatment and owned incomparable advantages over other tumor therapy. With unique complexity and uncertainty, immunotherapy still need helper to apply in the clinic. Galectins, modulated in tumor microenvironment, can regulate the disorders of innate and adaptive immune system resisting tumor growth. Considering the role of galectins in tumor immunosuppression, combination therapy of targeted anti-galectins and immunotherapy may be a promising tumor treatment. This brief review summarizes the expression and immune functions of different galectins in tumor microenvironment and discusses the potential value of anti-galectins in combination with checkpoint inhibitors in tumor immunotherapy.

Galectin-3 Expression in Pancreatic Cell Lines Under Distinct Autophagy-Inducing Stimulus

Hypoxia and nutrient deprivation are responsible for inducing malignant behavior in neoplastic cells. In these conditions, metabolic stress leads the cells to enhance their autophagic flux and to activate key molecules for homeostasis maintenance. Galectin-3 (Gal-3) is upregulated in pancreatic cancer and it is activated under the hypoxic atmosphere. We aimed to analyze the most effective autophagic-inducing conditions in pancreatic ductal adenocarcinoma cells and the effect exerted under these conditions in association with hypoxia on the Gal-3 expression. Gal-3 and the microtubule-associated protein light chain 3 beta (LC3) were accessed through western blot and immunofluorescence. Degradative vacuole quantification was analyzed by transmission electronic microscopy, and inhibition of Gal-3 was performed using siRNA. According to the analyses, the most effective conditions in the inducement of autophagy for PANC-1 and MIA PaCa-2 cells were nutritional deprivation and complete amino acid/glucose deprivation, respectively. PANC-1 cells presented higher Gal-3 when they were submitted to 24 h of nutritional deprivation alone and simultaneously nutritional and oxygen deprivation. Inhibition of Gal-3 causes a decrease of LC3 levels in all experimental conditions. These results confirm that Gal-3 is modulated by microenvironment factors and the possibility of Gal-3 participating in an adaptive response from PDAC cells to extreme conditions.

Tumor resistance mechanisms and their consequences on γδ T cell activation

Human γδ T lymphocytes are predominated by two major subsets, defined by the variable domain of the δ chain. Both, Vδ1 and Vδ2 T cells infiltrate in tumors and have been implicated in cancer immunosurveillance. Since the localization and distribution of tumor-infiltrating γδ T cell subsets and their impact on survival of cancer patients are not completely defined, this review summarizes the current knowledge about this issue. Different intrinsic tumor resistance mechanisms and immunosuppressive molecules of immune cells in the tumor microenvironment have been reported to negatively influence functional properties of γδ T cell subsets. Here, we focus on selected tumor resistance mechanisms including overexpression of cyclooxygenase (COX)-2 and indolamine-2,3-dioxygenase (IDO)-1/2, regulation by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/TRAIL-R4 pathway and the release of galectins. These inhibitory mechanisms play important roles in the cross-talk of γδ T cell subsets and tumor cells, thereby influencing cytotoxicity or proliferation of γδ T cells and limiting a successful γδ T cell-based immunotherapy. Possible future directions of a combined therapy of adoptively transferred γδ T cells together with γδ-targeting bispecific T cell engagers and COX-2 or IDO-1/2 inhibitors or targeting sialoglycan-Siglec pathways will be discussed and considered as attractive therapeutic options to overcome the immunosuppressive tumor microenvironment.

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.

Luteolin impairs hypoxia adaptation and progression in human breast and colon cancer cells

Hypoxia-inducible factors (HIFs) are the force which drives hypoxic cancer cells to a more aggressive and resistant phenotype in a number of solid tumors, including colorectal and breast cancer. Results from recent studies suggest a role for HIF-1 in immune evasion and cancer stem cell phenotype promotion, establishing HIF-1 as a potential therapeutic target. Thus, identifying new compounds that might inhibit HIF1 activity, or at least exert antiproliferative effects that are unaffected by HIF1-dependent adaptations, is an attractive goal for the management of hypoxic tumors. Here we show that the flavonoid luteolin exerts a significant cytotoxic effect on the colon cancer cell line HCT116 and the breast adenocarcinoma cell line MDA-MB231, by inducing both apoptotic and necrotic cell death, and that this effect is not impaired by HIF-1 activation. In these cells, luteolin also stimulates autophagy; however this seems to be part of a protective response, rather than contribute to the cytotoxic effect. Interestingly, luteolin induces a decrease in HIF-1 transcriptional activity. This is accompanied by a decrease in the levels of protein markers of stemness and invasion, and by a reduction of migratory capacity of the cells. Taken together, our results suggest that luteolin could be developed into a useful therapeutic agent aimed at hypoxic tumors.

Hypoxia‑induced galectin‑3 enhances RhoA function to activate the motility of tumor cells in non‑small cell lung cancer

Galectin-3 plays crucial roles in tumor progression. However, in non-small cell lung cancer (NSCLC), it remains unclear whether the hypoxic tumor microenvironment enhances galectin-3-induced cell motility. We investigated galectin-3 expression in NSCLC cells under hypoxia, and the possible molecular mechanisms by which galectin-3 influences tumor aggressiveness. Galectin-3 levels in NSCLC cell lines under hypoxia were assessed using reverse transcription PCR and western blotting. To clarify the role of endogenous galectin-3, the effect of galectin-3 knockdown in NSCLC cells was investigated using scratch and invasion assays. The expression and clinicopathological significance of galectin-3 in 57 patients with pN0M0 invasive pulmonary adenocarcinoma were investigated by immunohistochemistry. Both mRNA and protein levels of galectin-3 in the NSCLC cell lines A549 and LK-2 were upregulated by hypoxia. As revealed by scratch and invasion assays, the cell migratory and invasive activities were significantly increased under hypoxia, but were reduced by galectin-3 knockdown. Notably, addition of galectin-3 to the media did not improve the cell motility impaired by galectin-3 knockdown. To clarify the role of endogenous galectin-3 in the enhancement of tumor cell motility under hypoxia, we focused on the function of RhoA. RhoA level in the plasma membrane, but not in the cytoplasm, was increased under hypoxia and decreased by galectin-3 knockdown. RhoA activity was significantly enhanced under hypoxia and effectively inhibited by galectin-3 knockdown. In patients with pN0M0 invasive pulmonary adenocarcinoma, higher galectin-3 expression on tumor cells was significantly associated with tumor cell invasion into microvessels and tumor recurrence after surgery. These data demonstrate that in NSCLC cells under hypoxia, upregulated galectin-3 levels increase the localization of RhoA to the plasma membrane, thus enhancing RhoA activity, which is associated with aggressive cell motility. In pN0M0 invasive pulmonary adenocarcinoma, galectin-3 is a potential biomarker for predicting tumor recurrence after radical surgery.

Galectin-3 down-regulates antioxidant peroxiredoxin-4 in human cardiac fibroblasts: a new pathway to induce cardiac damage

Galectin-3 (Gal-3) is increased in heart failure (HF) and promotes cardiac fibrosis and inflammation. We investigated whether Gal-3 modulates oxidative stress in human cardiac fibroblasts, in experimental animal models and in human aortic stenosis (AS). Using proteomics and immunodetection approaches, we have identified that Gal-3 down-regulated the antioxidant peroxiredoxin-4 (Prx-4) in cardiac fibroblasts. In parallel, Gal-3 increased peroxide, nitrotyrosine, malondialdehyde, and N-carboxymethyl-lysine levels and decreased total antioxidant capacity. Gal-3 decreased prohibitin-2 expression without modifying other mitochondrial proteins. Prx-4 silencing increased oxidative stress markers. In Gal-3-silenced cells and in heart from Gal-3 knockout mice, Prx-4 was increased and oxidative stress markers were decreased. Pharmacological inhibition of Gal-3 with modified citrus pectin restored cardiac Prx-4 as well as prohibitin-2 levels and improved oxidative status in spontaneously hypertensive rats. In serum from 87 patients with AS, Gal-3 negatively correlated with total antioxidant capacity and positively correlated with peroxide. In myocardial biopsies from 26 AS patients, Gal-3 up-regulation paralleled a decrease in Prx-4 and in prohibitin-2. Cardiac Gal-3 inversely correlated with Prx-4 levels in myocardial biopsies. These data suggest that Gal-3 decreased Prx-4 antioxidant system in cardiac fibroblasts, increasing oxidative stress. In pathological models presenting enhanced cardiac Gal-3, the decrease in Prx-4 expression paralleled increased oxidative stress. Gal-3 blockade restored Prx-4 expression and improved oxidative stress status. In AS, circulating levels of Gal-3 could reflect oxidative stress. The alteration of the balance between antioxidant systems and reactive oxygen species production could be a new pathogenic mechanism by which Gal-3 induces cardiac damage in HF.

Diagnostic significance of CK19, galectin-3, CD56, TPO and Ki67 expression and BRAF mutation in papillary thyroid carcinoma

The aim of the present study was to examine the rate of BRAF mutation and the expression profiles of CK19, galectin-3, CD56, thyroid peroxidase (TPO) and Ki67 in papillary thyroid carcinoma (PTC) and papillary thyroid micro-carcinoma (PTMC). A total of 246 cases of thyroid disease were collected, including PTC, PTMC, nodular goiter (NG) and Hashimoto thyroiditis (HT). The results revealed that CK19 expression was 116/120 in PTC, 61/64 in PTMC, 2/34 in NG and 1/28 in HT. Galectin-3 positive expression was 115/120 in PTC, 60/64 in PTMC, 6/34 in NG and 4/28 in HT. TPO positive expression was 8/120 in PTC, 1/64 in PTMC, 30/34 in NG and 25/28 in HT. CD56-positive expression was 12/120 in PTC, 3/64 in PTMC, 33/34 in NG and 26/28 in HT. Ki67 labeling index was 2.52±0.46% in PTC (120 cases), 2.62±0.52% in PTMC (64 cases), 2.55±0.44% in NG (34 cases) and 2.58±0.48% in HT (28 cases). BRAF mutation rate was 93/120 in PTC, 47/64 in PTMC, 3/34 in NG and 2/28 in HT. These results suggested that expression patterns of CK19, galectin-3, CD56 and TPO and BRAF mutation exhibit diagnosis value in thyroid disease. However, Ki67-positive rate exhibits no notable diagnosis value in thyroid disease.

Ligand-free method to produce the anti-angiogenic recombinant Galectin-3 carbohydrate recognition domain

Galectin-3 (Gal3) is involved in many physiological processes related to tumor growth, such as promoting angiogenesis, cell migration/invasion, resistance to apoptosis and immune response modulation. Usually the overexpression of Gal3 is a poor prognostic marker for cancer patients. Recombinant Gal3 carbohydrate domain (Gal3C) has been proposed as a useful tool to inhibit angiogenesis. So far, all production protocols reported for Gal3C production have used proteolytic cleavage of full length Gal3 and/or affinity-based purification. This involves dialysis, a time consuming step used to eliminate the elution ligand, usually lactose. In this report, we describe an alternative method to produce human recombinant Gal3C in E. coli, purified with cationic exchange and size exclusion chromatography. The recombinant protein was characterized using circular dichroism and nuclear magnetic resonance, showing a beta sheet enriched well-folded globular structure. The average yield obtained was 26 mg/L of broth and the purity was above 99%. The anti-angiogenic activity was assessed in vitro and showed a reduction of 70% and 77% in endothelial cells tubule formation upon treatment with 10 and 20 μg/mL, respectively and also had no impact on cell viability. The method described here is more suitable for both laboratory and industrial production of the potential anti-tumor Gal3C.

Nova1 mediates resistance of rat pheochromocytoma cells to hypoxia-induced apoptosis via the Bax/Bcl-2/caspase-3 pathway

Neuro-oncological ventral antigen 1 (Nova1) is a well known brain-specific splicing factor. Several studies have identified Nova1 as a regulatory protein at the top of a hierarchical network. However, the function of Nova1 during hypoxia remains poorly understood. This study aimed to investigate the protective effect of Nova1 against cell hypoxia and to further explore the Bax/Bcl-2/caspase-3 pathway as a potential mechanism. During hypoxia, the survival rate of pheochromocytoma PC12 cells was gradually decreased and the apoptosis rate was gradually increased, peaking at 48 h of hypoxia. At 48 h after transfection of PC12 cells with pCMV-Myc-Nova1, the expression of Nova1 was significantly increased, with wide distribution in the cytoplasm and nucleus. Moreover, the survival rate was significantly increased and the apoptosis rate was significantly decreased. Additionally, the mRNA and protein expression levels of Bax and caspase-3 were significantly increased in the pCMV-Myc group and significantly decreased in the pCMV-Myc-Nova1 group, whereas that of Bcl-2 was significantly decreased in the pCMV-Myc group and significantly increased in the pCMV-Myc-Nova1 group. This study indicated that Nova1 could be linked to resistance to the hypoxia-induced apoptosis of PC12 cells via the Bax/Bcl-2/caspase-3 pathway, and this finding may be of significance for exploring novel mechanisms of hypoxia and the treatment of hypoxia-associated diseases.

Galectin-3 acts as an angiogenic switch to induce tumor angiogenesis via Jagged-1/Notch activation

Angiogenesis is a coordinated process tightly regulated by the balance between Delta-like-4 (DLL4) and Jagged-1 (JAG1) in endothelial cells. Here we show that galectin-3 (gal-3), a glycan-binding protein secreted by cancer cells under hypoxic conditions, triggers sprouting angiogenesis, assisted by hypoxic changes in the glycosylation status of endothelial cells that enhance binding to gal-3. Galectin-3's proangiogenic functions were found to be predominantly dependent on the Notch ligand JAG1. Differential direct binding to JAG1 was shown by surface plasmon resonance assay. Upon binding to Notch ligands, gal-3 preferentially increased JAG1 protein half-life over DLL4 and preferentially activated JAG1/Notch-1 signaling in endothelial cells. JAG1 overexpression in Lewis lung carcinoma cells accelerated tumor growth in vivo, but this effect was prevented in Lgals3-/- mice. Our findings establish gal-3 as a molecular regulator of the JAG1/Notch-1 signaling pathway and have direct implications for the development of strategies aimed at controlling tumor angiogenesis.

Galectin-3 is a non-classic RNA binding protein that stabilizes the mucin MUC4 mRNA in the cytoplasm of cancer cells

Pancreatic cancer cells express high levels of MUC1, MUC4 and MUC16 mRNAs that encode membrane-bound mucins. These mRNAs share unusual features such as a long half-life. However, it remains unknown how mucin mRNA stability is regulated. Galectin-3 (Gal-3) is an endogenous lectin playing important biological functions in epithelial cells. Gal-3 is encoded by LGALS3 which is up-regulated in pancreatic cancer. Despite the absence of a RNA-recognition motif, Gal-3 interacts indirectly with pre-mRNAs in the nucleus and promotes constitutive splicing. However a broader role of Gal-3 in mRNA fate is unexplored. We report herein that Gal-3 increases MUC4 mRNA stability through an intermediate, hnRNP-L which binds to a conserved CA repeat element in the 3′UTR in a Gal-3 dependent manner and also controls Muc4 mRNA levels in epithelial tissues of Gal3^−/− mice. Gal-3 interacts with hnRNP-L in the cytoplasm, especially during cell mitosis, but only partly associates with protein markers of P-Bodies or Stress Granules. By RNA-IP plus RNA-seq analysis and imaging, we demonstrate that Gal-3 binds to mature spliced MUC4 mRNA in the perinuclear region, probably in hnRNP-L-containing RNA granules. Our findings highlight a new role for Gal-3 as a non-classic RNA-binding protein that regulates MUC4 mRNA post-transcriptionally.

Clinical significance of galectin-3 in patients with adult acute myeloid leukemia: a retrospective cohort study with long-term follow-up and formulation of risk scoring system

Galectin-3 plays an increasingly important role in development and progression of tumor. However, little is known about the clinical impact of galectin-3 in non-acute promyelocytic leukemia (non-M3 AML). Peripheral blood of 298 patients with primary non-M3 AML and 30 normal donors was collected for measurement of galectin-3. Galectin-3 levels were significantly higher compared with the control group (p < .001). Patients with higher galectin-3 levels had lower CR rates (p = .001) and 1-year overall survival (OS) rates (p = .002). The Kaplan-Meier survival analysis showed that higher galectin-3 levels group had significantly shorter OS. Cox regression model revealed high galectin-3 level was an independent poor prognostic factor. A scoring system incorporating galectin-3 and other prognostic factors (age, WBC, karyotype, NPM1/FLT3-ITD, CEBPA^{double-mutation} and c-KIT, WT1) was formulated to predict prognosis. In conclusion, galectin-3 may be a reliable prognostic marker in AML patients. The multifactorial scoring system was more powerful than a single factor to predict clinical outcome.

The Two Faces of Galectin-3: Roles in Various Pathological Conditions

Galectin-3, a unique chimaera-type member of the lectin family, displays a wide range of activities. This versatile molecule is involved in fundamental biological processes, including cell proliferation, cell-cell adhesion, apoptosis and immune responses.

This review is aimed at providing a general overview of the biological actions and diverse effects of Galectin-3 in many pathological conditions, with a specific focus on autoimmunity, inflammation and tumour progression. We report herein that Galectin-3 exerts deleterious functions determined by promotion of tumour progression and liver inflammation or aggravation of T cell-mediated autoimmune diseases. On the other hand, Galectin-3 exhibits a protective role in metabolic abnormalities and primary biliary cirrhosis.

The paradoxical “yin and yang” functions of Galectin-3 depend not only on its tissue and cellular localization but also on its availability, glycosylation status and the expression level of its ligands.

Galectin-3 Determines Tumor Cell Adaptive Strategies in Stressed Tumor Microenvironments

Galectin-3 is a member of the β-galactoside-binding lectin family, whose expression is often dysregulated in cancers. While galectin-3 is usually an intracellular protein found in the nucleus and in the cytoplasm, under certain conditions, galectin-3 can be secreted by an yet unknown mechanism. Under stressing conditions (e.g., hypoxia and nutrient deprivation) galectin-3 is upregulated, through the activity of transcription factors, such as HIF-1α and NF-κB. Here, we review evidence that indicates a positive role for galectin-3 in MAPK family signal transduction, leading to cell proliferation and cell survival. Galectin-3 serves as a scaffold protein, which favors the spatial organization of signaling proteins as K-RAS. Upon secretion, extracellular galectin-3 interacts with a variety of cell surface glycoproteins, such as growth factor receptors, integrins, cadherins, and members of the Notch family, among other glycoproteins, besides different extracellular matrix molecules. Through its ability to oligomerize, galectin-3 forms lectin lattices that act as scaffolds that sustain the spatial organization of signaling receptors on the cell surface, dictating its maintenance on the plasma membrane or their endocytosis. Galectin-3 induces tumor cell, endothelial cell, and leukocyte migration, favoring either the exit of tumor cells from a stressed microenvironment or the entry of endothelial cells and leukocytes, such as monocytes/macrophages into the tumor organoid. Therefore, galectin-3 plays homeostatic roles in tumors, as (i) it favors tumor cell adaptation for survival in stressed conditions; (ii) upon secretion, galectin-3 induces tumor cell detachment and migration; and (iii) it attracts monocyte/macrophage and endothelial cells to the tumor mass, inducing both directly and indirectly the process of angiogenesis. The two latter activities are potentially targetable, and specific interventions may be designed to counteract the protumoral role of extracellular galectin-3.