Galectin 1 expression is associated with tumor invasion and metastasis in stage IB to IIA cervical cancer

Overexpression of galectin2 (LGALS2) predicts a better prognosis in human breast cancer

BACKGROUND

Galectins (LGALS) are a family of carbohydrate-binding proteins, and LGALS family members have shown prognostic roles in various types of cancers. However, the prognostic significance of some LGALS family members has not been studied in breast malignancy.

METHODS

The prognostic value of LGALS family mRNA expression in breast cancer patients was investigated according to distinct clinicopathological features (including lymph node, intrinsic subtype, pathological grade, HER2, and TP53 status) using the Kaplan-Meier plotter database. Quantitative real-time polymerase chain reaction and western blotting were used to detect the mRNA and protein expression of LGALS in breast cancer and normal breast cells. The aberrant expression of specific LGALS and its correlation with breast cancer outcomes remains elusive. In the present analysis, we comprehensively explored an immunohistochemistry-based map of protein expression profiles in normal tissues, cancer, and cell lines from the widely available Human Protein Atlas (HPA) database. Immunohistochemistry was applied to evaluate the expression of LGALS between cancer and normal tissues.

RESULTS

Our results showed that overexpression of LGALS2 mRNA were correlated with satisfactory overall survival among all breast cancer patients. Furthermore, LGALS2 and LGALS4 expression correlated with a better overall survival (OS) in grade III breast cancer patients; LGALS2 also predicted a better OS in basal-like subtype patients, luminal B patients, HER2-overexpressing patients, TP53 mutated and wild breast cancer patients. Notably, the mRNA and protein expression levels of LGALS2 were decreased in cancer cells compared with normal cells (P<0.05). Furthermore, LGALS2 expression in immunostaining score was lower in cancer tissues than in normal tissues (P<0.005).

CONCLUSION

In conclusion, LGALS2 has potential as a valuable biomarker for envisaging a satisfactory prognosis in patients with breast tumours, particularly those with luminal and basal B types, all stages and grade III tumours.

The multifaceted role of Matricellular Proteins in health and cancer, as biomarkers and therapeutic targets

The extracellular matrix (ECM) is composed of a mesh of proteins, proteoglycans, growth factors, and other secretory components. It constitutes the tumor microenvironment along with the endothelial cells, cancer-associated fibroblasts, adipocytes, and immune cells. The proteins of ECM can be functionally classified as adhesive proteins and matricellular proteins (MCP). In the tumor milieu, the ECM plays a major role in tumorigenesis and therapeutic resistance. The current review encompasses thrombospondins, osteonectin, osteopontin, tenascin C, periostin, the CCN family, laminin, biglycan, decorin, mimecan, and galectins. The matrix metalloproteinases (MMPs) are also discussed as they are an integral part of the ECM with versatile functions in the tumor stroma. In this review, the role of these proteins in tumor initiation, growth, invasion and metastasis have been highlighted, with emphasis on their contribution to tumor therapeutic resistance. Further, their potential as biomarkers and therapeutic targets based on existing evidence are discussed. Owing to the recent advancements in protein targeting, the possibility of agents to modulate MCPs in cancer as therapeutic options are discussed.

Evaluating the Role of Galectins in Clathrin-Independent Endocytosis

Galectin-3 is a chimeric galectin involved in diverse intracellular and extracellular functions. Galectin-3 is synthesized in the cytoplasm and then released extracellularly by a poorly understood non-canonical secretion mechanism. As a result, it can play important roles both inside and outside the cell. One important extracellular role of galectin-3 is in modulating clathrin-independent endocytosis (CIE), a form of cellular internalization that is still not well understood. CIE, unlike clathrin-mediated endocytosis, has neither defined signaling sequences nor cytoplasmic machinery. As a result, extracellular interactions like the galectin-glycan interactions are thought to directly drive changes in CIE. This chapter discusses the methods designed to study the role of galectin-glycan interactions in CIE, which have provided us with insight into the functions of galectin-3 and cell surface glycans during CIE cargo internalization. These methods include media supplementation for metabolic glycoengineering, antibody internalization assays, lectin panels to assay changes in glycan patterns, exogenous galectin-3 supplementation, galectin-3 secretion assays, and in vitro assays to monitor the effect of galectins on CIE.

Activated fibroblasts enhance cancer cell migration by microvesicles-mediated transfer of Galectin-1

Cancer-associated fibroblasts (CAFs) are one of the main components of the stromal compartment in the tumor microenvironment (TME) and the crosstalk between CAFs and cancer cells is essential for tumor progression and aggressiveness. Cancer cells mediate an activation process, converting normal fibroblasts into CAFs, that are characterized by modified expression of many proteins and increased production and release of microvesicles (MVs), extracellular vesicles generated by outwards budding from the cell membrane. Recent evidence underlined that the uptake of CAF-derived MVs changes the overall protein content of tumor cells. In this paper, we demonstrate that tumor activated fibroblasts overexpress Galectin-1 (Gal-1) and consequently release MVs containing increased levels of this protein. The uptake of Gal-1 enriched MVs by tumor cells leads to the upregulation of its intracellular concentration, that strongly affects cancer cell migration, while neither proliferation nor adhesion are altered. Accordingly, tumor cells co-cultured with fibroblasts silenced for Gal-1 have a reduced migratory ability. The present work reveals the key role of an exogenous protein, Gal-1, derived from activated fibroblasts, in cancer progression, and contributes to clarify the importance of MVs-mediated protein trafficking in regulating tumor-stroma crosstalk.

Novel chlorophyll a derivatives with ester-linked galactose fragments for photodynamic therapy and fluorescence diagnostics of cancer

In the present work, a number of chlorophyll [Formula: see text] derivatives were synthetized with galactose fragments with an ester bond between macrocycle and carbohydrate fragments. It showed that synthesized compounds fluoresce intensely inside HeLa cells, which enable these compounds to be considered as potential diagnostic agents and indicates their ability to remain in the cell in an unassociated photoactive state — a necessary condition for the realization of a photodynamic action. It was determined that while all conjugates had comparable photoinduced toxicities, the conjugate with phorbin macrocycle fragment had a much lower dark toxicity, which corresponds to the trends noted earlier. In terms of a therapeutic window, conjugate significantly exceeds similar derivatives of chlorin [Formula: see text] and is the most promising for further research.

Schwann Cell Stimulation of Pancreatic Cancer Cells: A Proteomic Analysis

Schwann cells (SCs), the glial component of peripheral nerves, have been identified as promoters of pancreatic cancer (PC) progression, but the molecular mechanisms are unclear. In the present study, we aimed to identify proteins released by SCs that could stimulate PC growth and invasion. Proteomic analysis of human primary SC secretome was performed using liquid chromatography–tandem mass spectrometry, and a total of 13,796 unique peptides corresponding to 1,470 individual proteins were identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment were conducted using the Database for Annotation, Visualization, and Integrated Discovery. Metabolic and cell–cell adhesion pathways showed the highest levels of enrichment, a finding in line with the supportive role of SCs in peripheral nerves. We identified seven SC-secreted proteins that were validated by western blot. The involvement of these SC-secreted proteins was further demonstrated by using blocking antibodies. PC cell proliferation and invasion induced by SC-conditioned media were decreased using blocking antibodies against the matrix metalloproteinase-2, cathepsin D, plasminogen activator inhibitor-1, and galectin-1. Blocking antibodies against the proteoglycan biglycan, galectin-3 binding protein, and tissue inhibitor of metalloproteinases-2 decreased only the proliferation but not the invasion of PC cells. Together, this study delineates the secretome of human SCs and identifies proteins that can stimulate PC cell growth and invasion and therefore constitute potential therapeutic targets.

Recognition Sites for Cancer-targeting Drug Delivery Systems

BACKGROUND

Target-homing drug delivery systems are now gaining significant attention for use as novel therapeutic approaches in antitumor targeting for cancer therapy. Numerous targeted drug delivery systems have been designed to improve the targeting effects because these systems can display a range of favorable properties, thus, providing suitable characteristics for clinical applicability of anticancer drugs, such as increasing the solubility, and improving the drug distribution at target sites. The majority of these targeting systems are designed with respect to differences between cancerous and normal tissues, for instance, the low pH of tumor tissues or overexpressed receptors on tumor cell membranes. Due to the growing number of targeting possibilities, it is important to know the tumor-specific recognition strategies for designing novel, targeted, drug delivery systems. Herein, we identify and summarize literature pertaining to various recognition sites for optimizing the design of targeted drug delivery systems to augment current chemotherapeutic approaches.

OBJECTIVE

This review focuses on the identification of the recognition sites for developing targeted drug delivery systems for use in cancer therapeutics.

METHODS

We have reviewed and compiled cancer-specific recognition sites and their abnormal characteristics within tumor tissues (low pH, high glutathione, targetable receptors, etc.), tumor cells (receptor overexpression or tumor cell membrane changes) and tumor cell organelles (nuclear and endoplasmic reticular dysregulation) utilizing existing scientific literature. Moreover, we have highlighted the design of some targeted drug delivery systems that can be used as homing tools for these recognition sites.

RESULTS AND CONCLUSION

Targeted drug delivery systems are a promising therapeutic approach for tumor chemotherapy. Additional research focused on finding novel recognition sites, and subsequent development of targeting moieties for use with drug delivery systems will aid in the evaluation and clinical application of new and improved chemotherapeutics.

Galectin-1 Overexpression Activates the FAK/PI3K/AKT/mTOR Pathway and Is Correlated with Upper Urinary Urothelial Carcinoma Progression and Survival

Galectin-1 (GAL1) is a β-galactoside-binding protein involved in multiple aspects of tumorigenesis. However, the biological role of GAL1 in upper tract urothelial carcinoma (UTUC) has not been entirely understood. Herein, we investigated the oncological effects of GAL1 expression in tumor specimens and identified related gene alterations through molecular analysis of GAL1. Clinical parameter data and tumor specimens were collected from 86 patients with pT3N0M0 UTUC who had undergone radical nephroureterectomy. We analyzed the difference in survival by using Kaplan-Meier analyses and Cox proportional regression models and in GAL1 expression by using immunohistochemical (IHC) methods. Public genomic data from the Cancer Genome Atlas (TCGA) and GSE32894 data sets were analyzed for comparison. Using four urothelial carcinoma (UC) cell lines (BFTC-909, T24, RT4, and J82) as in vitro models, we evaluated the functions of GAL1 in UC cell growth, invasiveness, and migration and its role in downstream signaling pathways. The study population was classified into two groups, GAL1-high (n = 35) and GAL1-low (GAL1 n = 51), according to IHC interpretation. Univariate analysis revealed that high GAL1 expression was significantly associated with poor recurrence-free survival (RFS; p = 0.028) and low cancer-specific survival (CSS; p = 0.025). Multivariate analysis revealed that GAL1-high was an independent predictive factor for RFS (hazard ratio (HR) 2.43; 95% confidence interval (CI) 1.17-5.05, p = 0.018) and CSS (HR 4.04; 95% CI 1.25-13.03, p = 0.019). In vitro studies revealed that GAL1 knockdown significantly reduced migration and invasiveness in UTUC (BFTC-909) and bladder cancer cells (T24). GAL1 knockdown significantly reduced protein levels of matrix metalloproteinase-2 (MMP-2) and MMP-9, which increased tissue inhibitor of metalloproteinase-1 (TIMP-1) and promoted epithelial-mesenchymal transition (EMT). Through gene expression microarray analysis of GAL1 vector and GAL1-KD cells, we identified multiple significant signaling pathways including p53, Forkhead box O (FOXO), and phosphoinositide 3-kinase/protein kinase B (PI3K/AKT). We validated microarray results through immunoblotting, thus proving that downregulation of GAL1 reduced focal adhesion kinase (FAK), p-PI3K, p-AKT, and p-mTOR expression. We concluded that GAL1 expression was highly related to oncological survival in patients with locally advanced UTUC. GAL1 promoted UC invasion and metastasis by activating the FAK/PI3K/AKT/mTOR pathway.

Effects of Galectin-1 on Biological Behavior in Cervical Cancer

Background: We previously revealed that the expression of galectin-1 (LGALS1) was significantly reduced after neoadjuvant chemotherapy treatment in cervical cancer patients. The objective of this study is to investigate the effects of LGALS1 expression on biological behaviors of cervical cancer cells.

Methods: Immunohistochemistry and immunocytochemistry were performed to detect the expression of LGALS1 in cervical cancer tissues and cells (SiHa and C33A). Western blot analysis was performed to evaluate the efficacy of lentivirus-mediated upregulation or downregulation of LGALS1 in cervical cancer cells. Cell viability and proliferation were detected by CCK-8 and BrdU assays, respectively. Annexin V-FITC/PI apoptosis detection kit was employed to measure the apoptosis of cervical cancer cells. Transwell invasion and migration assays were also conducted to explore the invasive and migratory capabilities of cervical cancer cells. The expression of apoptosis- (Bcl-2 and Bax), invasion- (MMP-2 and MMP-9), and migration-related (Fascin and Ezrin) proteins, were detected by Western blot analysis. Xenograft mouse model of cervical cancer was generated to explore whether LGALS1 overexpression could promote tumor growth in vivo.

Results: LGALS1 was overexpressed in cervical cancer tissues and cell lines compared to that in normal cervical tissues and epithelium cells. Upregulation of LGALS1 significantly promoted the cell proliferation, inhibited cell apoptosis, and enhanced the migratory and invasive abilities of both SiHa and C33A cells, whereas downregulation of LGALS1 led to the opposite results. The level of Bcl-2, MMP-2, MMP-9, Fascin, and Erzin expression was significantly upregulated in cervical cancer cells with LGALS1 overexpression, while converse results were obtained in LGALS1 knockdown cancer cells. In vivo study also showed that LGALS1 overexpression facilitated tumor growth of cervical cancer cells.

Conclusion: Overexpression of LGALS1 significantly promoted and enhanced the aggressive features of cervical cancer both in vitro and in vivo, which may be associated with high expression of Bcl-2, MMP-2, MMP-9, Fascin, and Erzin proteins.

Human Galectin-1 and Its Inhibitors: Privileged Target for Cancer and HIV

Galectin 1(Gal-1), a β-galactoside binding mammalian lectin of 14KDa, is implicated in many signalling pathways, immune responses associated with cancer progression and immune disorders. Inhibition of human Gal-1 has been regarded as one of the potential therapeutic approaches for the treatment of cancer, as it plays a major role in tumour development and metastasis by modulating various biological functions viz. apoptosis, angiogenesis, migration, cell immune escape. Gal-1 is considered as a biomarker in diagnosis, prognosis and treatment condition. The overexpression of Gal-1 is well established and seen in many types of cancer progression like osteosarcoma, breast, lung, prostate, melanoma, etc. Gal-1 greatly accelerates the binding kinetics of HIV-1 to susceptible cells, leading to faster viral entry and a more robust viral replication by specific binding of CD4 cells. Hence, the Gal-1 is considered a promising molecular target for the development of new therapeutic drugs for cancer and HIV. The present review laid emphasis on structural insights and functional role of Gal-1 in the disease, current Gal-1 inhibitors and future prospects in the design of specific Gal-1 inhibitors.

Increased Galectin-1 Expression in Thymic Epithelial Tumors

INTRODUCTION

Thymic epithelial tumors (TET) are rare malignancies with a paucity of data on biology and therapeutics. Galectin-1 is a member of the β-galactoside binding protein family and has been shown to mediate tumor growth via modulation of immune cell function. This study examined galectin-1 expression in TET.

PATIENTS AND METHODS

A tissue microarray of 68 patients with TET and 8 benign thymus controls were stained for galectin-1 expression and scored by a pathologist blinded to patient clinical and pathologic data. Galectin-1 expression +1 or greater staining intensity was considered positive. Clinical and pathologic data were abstracted from institutional databases. Expression of galectin-1 in thymic tumor was compared to benign thymus controls and correlated with pertinent clinical and pathologic data.

RESULTS

Galectin-1 expression was higher in TET compared to benign thymus controls (65% vs. 0%). No significant association between galectin-1 expression and the development of recurrent disease, paraneoplastic syndromes, or overall survival was noted.

CONCLUSION

Galectin-1 is overexpressed in the majority of TET. Detection of galectin-1 may differentiate benign from neoplastic thymic processes. Additional studies are needed to assess the role of galectin-1 in the development of TET.

The Role of Galectins in Tumor Progression, Treatment and Prognosis of Gynecological Cancers

Galectins are the member of soluble proteins that bind with β-galactoside containing glycans. These proteins have been considered to be associated in various important events such as different types of cancers. It has been found that galectins could contribute to neoplastic transformation or regulate cell growth, cell apoptosis, and immune cells, causing tumor invasion, progression, metastasis and angiogenesis. Somehow, galectins are also found to exert a protective effect on cancer in a tissue-dependent way. These glycans binding proteins have been shown to be involved in the regulation of different tumor suppressor genes and oncogenes with their possible roles in human cancers. Objective of the current review is to summarize the role of galectin-1, -3 -7, and -9 in tumorigenesis of gynecological cancers. Galectin protein may be a potential therapeutic target in gynecological malignancies due to reported radio- and chemo- sensitivities, immunotherapeutic, anti-angiogenic and anti-proliferative activities. This review considers the evidence for the future research that how galectins may be important in the progression and treatment of gynecological cancers along with its potent use as a novel prognostic marker.

Galectin-1 gene silencing inhibits the activation and proliferation but induces the apoptosis of hepatic stellate cells from mice with liver fibrosis

Liver fibrosis is a serious threat to human health, and there is currently no effective clinical drug for treatment of the disease. Although Galectin-1 is effective, its role in liver function, inflammation, matrix metalloproteinases and the activation of hepatic stellate cells (HSCs) remains to be elucidated. The aim of the present study was to elucidate the effect of Galectin-1 on the activation, proliferation and apoptosis of HSCs in a mouse model of liver fibrosis. Following successful model establishment and tissue collection, mouse HSCs (mHSCs) were identified and an mHSC line was constructed. Subsequently, to determine the role of Galectin-1 in liver fibrosis, the expression levels of transforming growth factor (TGF)-β1, connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA) pre- and post-transfection were evaluated by reverse transcription-quantitative polymerase chain reaction and western blot analyses. In addition, the effects of Galectin-1 on the biological behavior and mitochondrial function of mHSCs were determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry and a scratch test. It was first observed that the expression levels of Galectin-1, TGF-β1, CTGF and α-SMA were downregulated by silencing the gene expression of Galectin-1. Additionally, silencing the gene expression of Galectin-1 inhibited cell cycle progression, proliferation and migration but induced the apoptosis of mHSCs from mice with liver fibrosis. Furthermore, the in vivo experimental results suggested that silencing the gene expression of Galectin-1 improved liver fibrosis. Collectively, it was concluded that silencing the gene expression of Galectin-1 ameliorates liver fibrosis and that functionally suppressing Galectin-1 may be a future therapeutic strategy for liver fibrosis.

Knockdown of BRCC3 exerts an anti‑tumor effect on cervical cancer in vitro

Cervical cancer is a serious malignancy that affects the health of females. In the present study, the association between breast cancer type 1 susceptibility protein/breast cancer type 2 susceptibility protein-containing complex subunit 3 (BRCC3) and cervical cancer was investigated. Reverse transcription-quantitative polymerase chain reaction and western blotting were performed to determine BRCC3 mRNA and protein expression levels in cervical cancer tissues and cells, in addition to the expression levels of proteins associated with the epithelial-mesenchymal transition (EMT) process in HeLa and SiHa cells. Cell Counting Kit-8, Transwell and wound healing assays were performed to determine the cell viability, invasion and migration abilities of cervical cancer cells, respectively. The results of the present study revealed that BRCC3 expression was significantly increased in cervical cancer tissues, which was also revealed to be associated with the clinical stages and pathological grades of cervical cancer exhibited by patients, in addition to the survival time. Furthermore, BRCC3 expression levels were enhanced in HeLa, SiHa and C-33A cervical cancer cells. BRCC3 interference in HeLa and SiHa cells was revealed to suppress cell viability, invasion and migration abilities via upregulation of E-cadherin expression levels and downregulation of Vimentin, matrix metalloproteinase (MMP)-2, MMP-9, snail family transcriptional repressor (Snai)1 and Snai2 expression levels. In conclusion, the expression levels of BRCC3 were revealed to be increased in cervical cancer tissues, which were positively associated with clinical features of cervical cancer. Furthermore, BRCC3 interference inhibited the cell viability, invasion and migration abilities of HeLa and SiHa cells via regulation of EMT progression and expression levels of Snai family members. In addition, the results of the present study suggested that BRCC3 represents an oncogene associated with cervical cancer, and may also represent a novel therapeutic biomarker for the diagnosis, treatment and prognosis of patients with cervical cancer.

Upregulation of LGALS1 is associated with oral cancer metastasis

Background

Oral cancer metastasis is a devastating process that contributes to poor prognosis and high mortality, yet its detailed underlying mechanisms remain unclear. Here, we aimed to evaluate metastasis-specific markers in oral cancer and to provide comprehensive recognition concerning functional roles of the specific target in oral cancer metastasis.

Methods

Lectin, galactoside-binding, soluble, 1 (LGALS1) was identified by secretomic analysis. LGALS1 expression of patient samples with oral cancer on the tissue microarray were examined by immunochemical (IHC) staining. Small interfering RNA (siRNA)-mediated knockdown of LGALS1 revealed the role of LGALS1 in oral cancer metastasis in vitro and in vivo.

Results

LGALS1 was observed to be upregulated in highly invasive oral cancer cells, and elevated LGALS1 expression was correlated with cancer progression and lymph node metastasis in oral cancer tissue specimens. Functionally, silencing LGALS1 resulted in suppressed cell growth, wound healing, cell migration, and cell invasion in oral cancer cells in vitro. Knockdown of LGALS1 in highly invasive oral cancer cells dramatically inhibited lung metastasis in an in vivo mouse model. Mechanistic studies suggested p38 mitogen-activated protein kinase (MAPK) phosphorylation, upregulated MMP-9, and mesenchymal phenotypes of epithelial-mesenchymal transition (EMT) in highly invasive oral cancer cells, whereas siRNA against LGALS1 resulted in the inactivation of p38 MAPK pathway, downregulated MMP-9, and EMT inhibition.

Conclusions

These findings demonstrate that elevated LGALS1 is strongly correlated with oral cancer progression and metastasis, and that it could potentially serve as a prognostic biomarker and an innovative target for oral cancer therapy.

The Role of Galectins in Cervical Cancer Biology and Progression

Cervical cancer is one of the malignant tumors with high incidence and high mortality among women in developing countries. The main factors affecting the prognosis of cervical cancer are the late recurrence and metastasis and the effective adjuvant treatment, which is radiation and chemotherapy or combination therapy. Galectins, a family containing many carbohydrate binding proteins, are closely involved in the occurrence and development of tumor. They are involved in tumor cells transformation, angiogenesis, metastasis, immune escape, and sensitivity against radiation and chemotherapy. Therefore, galectins are deemed as the targets of multifunctional cancer treatment. In this review, we mainly focus on the role of galectins, especially galectin-1, galectin-3, galectin-7, and galectin-9 in cervical cancer, and provide theoretical basis for potential targeted treatment of cervical cancer.

Distinct cargo-specific response landscapes underpin the complex and nuanced role of galectin-glycan interactions in clathrin-independent endocytosis

Clathrin-independent endocytosis (CIE) is a form of endocytosis that lacks a defined cytoplasmic machinery. Here, we asked whether glycan interactions, acting from the outside, could be a part of that endocytic machinery. We show that the perturbation of global cellular patterns of protein glycosylation by modulation of metabolic flux affects CIE. Interestingly, these changes in glycosylation had cargo-specific effects. For example, in HeLa cells, GlcNAc treatment, which increases glycan branching, increased major histocompatibility complex class I (MHCI) internalization but inhibited CIE of the glycoprotein CD59 molecule (CD59). The effects of knocking down the expression of galectin 3, a carbohydrate-binding protein and an important player in galectin-glycan interactions, were also cargo-specific and stimulated CD59 uptake. By contrast, inhibition of all galectin-glycan interactions by lactose inhibited CIE of both MHCI and CD59. None of these treatments affected clathrin-mediated endocytosis, implying that glycosylation changes specifically affect CIE. We also found that the galectin lattice tailors membrane fluidity and cell spreading. Furthermore, changes in membrane dynamics mediated by the galectin lattice affected macropinocytosis, an altered form of CIE, in HT1080 cells. Our results suggest that glycans play an important and nuanced role in CIE, with each cargo being affected uniquely by alterations in galectin and glycan profiles and their interactions. We conclude that galectin-driven effects exist on a continuum from stimulatory to inhibitory, with distinct CIE cargo proteins having unique response landscapes and with different cell types starting at different positions on these conceptual landscapes.

Predictive role of galectin-1 and integrin α5β1 in cisplatin-based neoadjuvant chemotherapy of bulky squamous cervical cancer

Although galectin-1 and integrin α5β1 confer chemoresistance to certain types of cancer, whether their expression predicts the response to cisplatin-based neoadjuvant chemotherapy (NACT) in squamous cervical cancer remains unclear. Paired tumor samples (pre- and post-chemotherapy) were obtained from 35 bulky squamous cervical cancer patients treated with cisplatin-based NACT and radical hysterectomy at our hospital between January 2007 and August 2014. The expression of galectin-1 and integrin α5β1 in tumor cells and stromal cells was analyzed by immunohistochemistry. The correlation between galectin-1/integrin α5β1 and apoptosis-associated markers was investigated by using the The Cancer Genome Atlas (TCGA) RNA-sequencing data. Seventeen patients were identified as chemotherapy responders and 18 as non-responders. Galectin-1 and integrin α5β1-positive immunostaining was more frequently observed in stromal cells than its in tumor cells. The expression of galectin-1 and integrin α5β1 in stromal and tumor cells was significantly down-regulated in postchemotherapy cervical cancer tissues. High levels of galectin-1 and integrin α5β1 in stromal were associated with a negative chemotherapy response in squamous cervical cancer patients treated with cisplatin-based NACT. Additionally, the expression of galectin-1 and integrin α5 correlated negatively with caspase 3/caspase 8 by using the TCGA RNA-sequencing data. Galectin-1 and integrin α5β1 expression in stromal may serve as a prediction of the responses to cisplatin-based NACT for patients with bulky squamous cervical cancer. Galectin-1 and integrin α5β1 may be implicated in the development of chemoresistance in cervical cancer via suppressing apoptosis.

The involvement of E6, p53, p16, MDM2 and Gal-3 in the clinical outcome of patients with cervical cancer

High-risk human papilloma virus (HPV) is the leading cause of cervical cancer. HPV oncogenes are responsible for the development of malignancy, and the E6 oncoprotein that HPV expresses induces the degradation of tumour suppressor protein p53 (p53). This degradation leads to the upregulation of p16; however, unidentified proteins may also serve a role in the development and progression of cervical cancer. Therefore, the aim of the present study was to analyse the expression levels of E6, p53, p16, MDM2 proto-oncogene (MDM2) and galectin-3 (gal-3) in cervical cancer specimens. A total of 250 cervical cancer tissue slides were used. The expression of E6, p53, p16, MDM2 and gal-3 was analysed with immunohistochemical methods and a semi-quantitative scoring. SPSS software was used for the statistical evaluation of staining results and survival analysis of patients with cervical cancer. Cervical cancer specimens demonstrated significantly increased E6 staining with advanced T-status and increased International Federation of Gynecology and Obstetrics classification. E6, p53 and p16 demonstrated significantly different expression levels in squamous epithelial tissue compared with adenocarcinomas. MDM2 and gal-3 demonstrated positively correlated expression levels in cervical cancer. In addition, gal-3 expression was correlated with poor prognosis in p16-negative cases. A negative correlation between the expression of E6 and a mutated form of p53 was also identified in cervical cancer. p53 mutation was demonstrated to be common in cervical cancer, and gal-3 and MDM2 appeared to act in a combined manner in this type of tumour. As gal-3 is overexpressed in the cervical cancer tissue of patients with poor prognosis, the use of gal-3 inhibitors should be investigated in future studies.

Inhibitory effects of FKBP14 on human cervical cancer cells

The FK506-binding protein 14 (FKBP14), which belongs to a subfamily of immunophilins, has been implicated in various biochemical processes. However, its effects on human cervical cancer remain to be elucidated. The present study aimed to determine the exact role of FKBP14 in human cervical cancer cell proliferation, cell cycle progression, apoptosis, invasion and migration. Cell proliferation was measured by Cell Counting Kit‑8 assay. Flow cytometry was conducted to determine the effects of FKBP14 on cell cycle progression and apoptosis. Cell invasion and migration were determined by Transwell assay. The results of the present study demonstrated that silencing FKBP14 expression using short hairpin (sh)RNA suppressed proliferation, invasion and migration of HeLa and C‑33A cells, and also induced apoptosis and cell cycle arrest. Furthermore, silencing FKBP14 expression decreased the protein expression levels of B‑cell lymphoma 2 (Bcl‑2), matrix metalloproteinase (MMP)2 and MMP9, and increased the levels of caspase‑3 and Bcl‑2‑associated X protein in FKBP14 shRNA‑infected HeLa and C‑33A cells. In conclusion, FKBP14 may act as an oncogene through suppressing apoptosis and promoting motility in human cervical carcinogenesis; therefore, it may be considered a potential therapeutic target for the treatment of cervical cancer.

Overexpression of ezrin and galectin-3 as predictors of poor prognosis of cervical cancer

The aim of this study was to explore the correlation of ezrin and galectin-3 expressions with prognosis in cervical cancer. The immunohistochemical method was applied to detect ezrin and galectin-3 expressions in normal cervix tissues (n=30), cervicitis tissues (n=28), cervical intraepithelial neoplasia (CIN) tissues (classified as I-III, n=89), and cervical carcinoma tissues (n=84). Follow-up was conducted for 5 to 78 months to analyze the correlation of protein expressions with prognosis. Ezrin and galectin-3 expressions in cervical cancer were significantly higher than in normal cervix, cervicitis and CIN (all P<0.05), and expressions in CIN were significantly higher than in normal cervix and cervicitis (both P<0.05). The expressions of ezrin and galectin-3 were both related with histological grade, deep myometrial invasion and lymph node metastasis (all P<0.05). Spearman analysis showed that ezrin expression was positively correlated with galectin-3 expression in cervical cancer (r=0.355, P<0.05). The survival rate of patients with high expressions of ezrin and galectin-3 was significantly lower than those with low expressions of proteins (both P<0.05). The expressions of ezrin and galectin-3, histological grade, depth of stromal invasion, and lymph node metastasis are risk factors affecting the survival rate of patients with cervical cancer. The expressions of ezrin and galectin-3 were correlated with the development of cervical cancer, and overexpressions of those proteins were indicative of poor prognosis in patients with cervical cancer.

Galectin-1 induces invasion and the epithelial-mesenchymal transition in human gastric cancer cells via non-canonical activation of the hedgehog signaling pathway

Galectin-1 (Gal-1) has been reported to be an independent prognostic indicator of poor survival in gastric cancer and overexpression of Gal-1 enhances the invasiveness of gastric cancer cells. However, the downstream mechanisms by which Gal-1 promotes invasion remains unclear. Moreover, the function of Gal-1 in the epithelial-mesenchymal transition (EMT) in gastric cancer has not yet been elucidated. In this study, we observed Gal-1 expression was upregulated and positively associated with metastasis and EMT markers in 162 human gastric cancer tissue specimens. In vitro studies showed Gal-1 induced invasion, the EMT phenotype and activated the non-canonical hedgehog (Hh) pathway in gastric cancer cell lines. Furthermore, our data revealed that Gal-1 modulated the non-canonical Hh pathway by increasing the transcription of glioma-associated oncogene-1 (Gli-1) via a Smoothened (SMO)-independent manner, and that upregulation of Gal-1 was strongly associated with gastric cancer metastasis. We conclude that Gal-1 promotes invasion and the EMT in gastric cancer cells via activation of the non-canonical Hh pathway, suggesting Gal-1 could represent a promising therapeutic target for the prevention and treatment of gastric cancer metastasis.

The Role of Galectin-1 in Cancer Progression, and Synthetic Multivalent Systems for the Study of Galectin-1

This review discusses the role of galectin-1 in the tumor microenvironment. First, the structure and function of galectin-1 are discussed. Galectin-1, a member of the galectin family of lectins, is a functionally dimeric galactoside-binding protein. Although galectin-1 has both intracellular and extracellular functions, the defining carbohydrate-binding role occurs extracellularly. In this review, the extracellular roles of galectin-1 in cancer processes are discussed. In particular, the importance of multivalent interactions in galectin-1 mediated cellular processes is reviewed. Multivalent interactions involving galectin-1 in cellular adhesion, mobility and invasion, tumor-induced angiogenesis, and apoptosis are presented. Although the mechanisms of action of galectin-1 in these processes are still not well understood, the overexpression of galectin-1 in cancer progression indicates that the role of galectin-1 is significant. To conclude this review, synthetic frameworks that have been used to modulate galectin-1 processes are reviewed. Small molecule oligomers of carbohydrates, carbohydrate-functionalized pseudopolyrotaxanes, cyclodextrins, calixarenes, and glycodendrimers are presented. These synthetic multivalent systems serve as important tools for studying galectin-1 mediated cancer cellular functions.

Role of galectin-1 in urinary bladder urothelial carcinoma cell invasion through the JNK pathway

Human galectin-1 is a member of the galectin family, proteins with conserved carbohydrate-recognition domains that bind galactoside. Galectin-1 is highly expressed in various tumors and participates in various oncogenic processes. However, detailed descriptions of the function of galectin-1 in urinary bladder urothelial carcinoma have not been reported. Our previous cohort investigation showed that galectin-1 is associated with tumor invasiveness and is a possible independent prognostic marker of urinary bladder urothelial carcinoma. The present study aimed to clarify the relevance of galectin-1 expression level to tumor progression and invasion. In order to decipher a mechanism for the contribution of galectin-1 to the malignant behavior of urinary bladder urothelial carcinoma, two bladder cancer cell lines (T24 and J82) were established with knockdown of galectin-1 expression by shRNA. Bladder cancer cells with LGALS1 gene silencing showed reduced cell proliferation, lower invasive capability, and lower clonogenicity. Extensive signaling pathway studies indicated that galectin-1 participated in bladder cancer cell invasion by mediating the activity of MMP9 through the Ras-Rac1-MEKK4-JNK-AP1 signaling pathway. Our functional analyses of galectin-1 in urinary bladder urothelial carcinoma provided novel insights into the critical role of galectin-1 in tumor progression and invasion. These results revealed that silencing the galectin-1-mediated MAPK signaling pathway presented a novel strategy for bladder cancer therapy.

Systems-level effects of ectopic galectin-7 reconstitution in cervical cancer and its microenvironment

Background

Galectin-7 (Gal-7) is negatively regulated in cervical cancer, and appears to be a link between the apoptotic response triggered by cancer and the anti-tumoral activity of the immune system. Our understanding of how cervical cancer cells and their molecular networks adapt in response to the expression of Gal-7 remains limited.

Methods

Meta-analysis of Gal-7 expression was conducted in three cervical cancer cohort studies and TCGA. In silico prediction and bisulfite sequencing were performed to inquire epigenetic alterations. To study the effect of Gal-7 on cervical cancer, we ectopically re-expressed it in the HeLa and SiHa cervical cancer cell lines, and analyzed their transcriptome and SILAC-based proteome. We also examined the tumor and microenvironment host cell transcriptomes after xenotransplantation into immunocompromised mice. Differences between samples were assessed with the Kruskall-Wallis, Dunn’s Multiple Comparison and T tests. Kaplan–Meier and log-rank tests were used to determine overall survival.

Results

Gal-7 was constantly downregulated in our meta-analysis (p < 0.0001). Tumors with combined high Gal-7 and low galectin-1 expression (p = 0.0001) presented significantly better prognoses (p = 0.005). In silico and bisulfite sequencing assays showed de novo methylation in the Gal-7 promoter and first intron. Cells re-expressing Gal-7 showed a high apoptosis ratio (p < 0.05) and their xenografts displayed strong growth retardation (p < 0.001). Multiple gene modules and transcriptional regulators were modulated in response to Gal-7 reconstitution, both in cervical cancer cells and their microenvironments (FDR < 0.05 %). Most of these genes and modules were associated with tissue morphogenesis, metabolism, transport, chemokine activity, and immune response. These functional modules could exert the same effects in vitro and in vivo, even despite different compositions between HeLa and SiHa samples.

Conclusions

Gal-7 re-expression affects the regulation of molecular networks in cervical cancer that are involved in diverse cancer hallmarks, such as metabolism, growth control, invasion and evasion of apoptosis. The effect of Gal-7 extends to the microenvironment, where networks involved in its configuration and in immune surveillance are particularly affected.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2700-8) contains supplementary material, which is available to authorized users.

Sulforaphane-cysteine suppresses invasion via downregulation of galectin-1 in human prostate cancer DU145 and PC3 cells

Our previous study showed that sulforaphane (SFN) inhibits invasion in human prostate cancer DU145 cells; however, the underlying mechanisms were not profoundly investigated. In the present study, we found that sulforaphane-cysteine (SFN-Cys), as a metabolite of SFN, inhibits invasion and possesses a novel mechanism in prostate cancer DU145 and PC3 cells. The scratch and Transwell assays showed that SFN-Cys (15 µM) inhibited both migration and invasion, with cell morphological changes, such as cell shrinkage and pseudopodia shortening. The cell proliferation (MTS) assay indicated that cell viability was markedly suppressed with increasing concentrations of SFN‑Cys. Furthermore, the Transwell assay showed that inhibition of SFN‑Cys‑triggered invasion was tightly linked to the sustained extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Western blot analysis revealed that SFN-Cys downregulated galectin-1 protein, an invasion‑related protein, and that the galectin‑1 reduction could be blocked by ERK1/2 inhibitor PD98059 (25 µM). Moreover, immunofluorescence staining showed that the expression level of galectin-1 protein was significantly reduced in the cells treated with SFN‑Cys. Hence, SFN‑Cys‑inhibited invasion resulted from the sustained ERK1/2 phosphorylation and ERK1/2‑triggered galectin-1 downregulation, suggesting that galectin-1 is a new SFN-Cys target inhibiting invasion apart from ERK1/2, in the treatment of prostate cancer.

Galectin-1 expression is associated with tumour immunity and prognosis in gingival squamous cell carcinoma

AIMS

Galectin-1 (Gal-1) is a β-galactoside-binding protein that overexpresses in cancer and plays pivotal roles in tumour progression. Gal-1 regulates angiogenesis and invasiveness, and suppresses tumour immunity by inducing T cell apoptosis. Several studies have examined the relationship between Gal-1 and tumour immunosuppression in vivo, but they have not examined the clinicopathological relationship between Gal-1 expression and apoptotic T cell number in human tissue. In this study, we investigated the association between Gal-1 expression and apoptotic T cells of gingival squamous cell carcinoma (GSCC), as well as other clinicopathological factors.

METHODS

Immunohistochemical investigation of 80 GSCC specimens using anti-Gal-1, anti-CD3, anti-CD4, anti-CD8, anti-CD34, antipodoplanin and anticleaved caspase-3 (CC-3) antibodies was performed. Relative expression levels of CD3 and CC-3, as well as CD8 and CC-3 were assessed simultaneously by double immunostaining. Gal-1 expression and T cell apoptosis were evaluated in 6 high-power fields (3 in the tumour and 3 in the stroma).

RESULTS

Gal-1 expression in GSCC was significantly correlated with T cell infiltration (p=0.036), and apoptosis of CD3+ and CD8+ T cells (p<0.001). Moreover, Gal-1 expression was significantly correlated with lymph node metastasis (p=0.021), histological differentiation (p<0.001) and overall survival rate (p=0.021).

CONCLUSIONS

These findings suggest that Gal-1 plays an important role in immune escape of GSCC cells, and Gal-1 expression level may be a useful clinicopathological prognostic marker for GSCC.

Proteomic analysis of hepatocellular carcinoma HepG2 cells treated with platycodin D

Platycodin D (PD), a triterpenoid saponin isolated from Platycodonis Radix, is a famous Chinese herbal medicine that has been shown to have anti-proliferative effects in several cancer cell lines. The aim of this study was to determine the changes in cellular proteins after the treatment of hepatocellular carcinoma HepG2 cells with PD using proteomics approaches. The cell viability was determined using the MTT assay. The proteome was analyzed by two-dimensional difference gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Western blot analysis was used to confirm the expression of changed proteins. Our results showed that PD inhibited the proliferation of HepG2 cells in concentration- and time-dependent manners. Sixteen proteins were identified to be up-regulated in PD-treated HepG2 cells, including ATP5H, OXCT1, KRT9, CCDC40, ERP29, RCN1, ZNF175, HNRNPH1, HSP27, PA2G4, PHB, BANF1, TPM3, ECH1, LGALS1, and MYL6. Three proteins (i.e., RPS12, EMG1, and KRT1) decreased in HepG2 cells after treatment with PD. The changes in HSP27 and PHB were further confirmed by Western blotting. In conclusion, our results shed new lights on the mechanisms of action for the anti-cancer activity of PD.

Interaction of the Oncofetal Thomsen-Friedenreich Antigen with Galectins in Cancer Progression and Metastasis

Aberrant glycosylation of cell membrane proteins is a universal feature of cancer cells. One of the most common glycosylation changes in epithelial cancer is the increased occurrence of the oncofetal Thomsen–Friedenreich disaccharide Galβ1–3GalNAc (T or TF antigen), which appears in about 90% of cancers but is rarely seen in normal epithelium. Over the past few years, increasing evidence has revealed that the increased appearance of TF antigen on cancer cell surface plays an active role in promoting cancer progression and metastasis by interaction with the β-galactoside-binding proteins, galectins, which themselves are also frequently overexpressed in cancer and pre-cancerous conditions. This review summarizes the current understanding of the molecular mechanism of the increased TF occurrence in cancer, the structural nature, and biological impact of TF interaction with galectins, in particular galectin-1 and -3, on cancer progression and metastasis.

Galectin-1 inhibitors and their potential therapeutic applications: a patent review

INTRODUCTION

Galectins have affinity for β-galactosides. Human galectin-1 is ubiquitously expressed in the body and its expression level can be a marker in disease. Targeted inhibition of galectin-1 gives potential for treatment of inflammatory disorders and anti-cancer therapeutics.

AREAS COVERED

This review discusses progress in galectin-1 inhibitor discovery and development. Patent applications pertaining to galectin-1 inhibitors are categorised as monovalent- and multivalent-carbohydrate-based inhibitors, peptides- and peptidomimetics. Furthermore, the potential of galectin-1 protein as a therapeutic is discussed along with consideration of the unique challenges that galectin-1 presents, including its monomer-dimer equilibrium and oxidized and reduced forms, with regard to delivering an intact protein to a pathologically relevant site.

EXPERT OPINION

Significant evidence implicates galectin-1's involvement in cancer progression, inflammation, and host-pathogen interactions. Conserved sequence similarity of the carbohydrate-binding sites of different galectins makes design of specific antagonists (blocking agents/inhibitors of function) difficult. Key challenges pertaining to the therapeutic use of galectin-1 are its monomer-dimer equilibrium, its redox state, and delivery of intact galectin-1 to the desired site. Developing modified forms of galectin-1 has resulted in increased stability and functional potency. Gene and protein therapy approaches that deliver the protein toward the target are under exploration as is exploitation of different inhibitor scaffolds.

The luteotrophic function of galectin-1 by binding to the glycans on vascular endothelial growth factor receptor-2 in bovine luteal cells

The corpus luteum (CL) is a temporary endocrine gland producing a large amount of progesterone, which is essential for the establishment and maintenance of pregnancy. Galectin-1 is a β-galactose-binding protein that can modify functions of membrane glycoproteins and is expressed in the CL of mice and women. However, the physiological role of galectin-1 in the CL is unclear. In the present study, we investigated the expression and localization of galectin-1 in the bovine CL and the effect of galectin-1 on cultured luteal steroidogenic cells (LSCs) with special reference to its binding to the glycans on vascular endothelial growth factor receptor-2 (VEGFR-2). Galectin-1 protein was highly expressed at the mid and late luteal stages in the membrane fraction of bovine CL tissue and was localized to the surface of LSCs in a carbohydrate-dependent manner. Galectin-1 increased the viability in cultured LSCs. However, the viability of LSCs was decreased by addition of β-lactose, a competitive carbohydrate inhibitor of galectin-1 binding activity. VEGFR-2 protein, like galectin-1, is also highly expressed in the mid CL, and it was modified by multi-antennary glycans, which can be recognized by galectin-1. An overlay assay using biotinylated galectin-1 revealed that galectin-1 directly binds to asparagine-linked glycans (N-glycans) on VEGFR-2. Enhancement of LSC viability by galectin-1 was suppressed by a selective inhibitor of VEGFR-2. The overall findings suggest that galectin-1 plays a role as a survival factor in the bovine CL, possibly by binding to N-glycans on VEGFR-2.

Galectin-1, -3 and -9 Expression and Clinical Significance in Squamous Cervical Cancer

Galectins are proteins that bind β-galactoside sugars and provide a new type of potential biomarkers and therapeutic targets in cancer. Galectin-1, -3 and -9 have become the focus of different research groups, but their expression and function in cervical cancer is still unclear. The aim of this study was to determine the phenotype of galectin-1, -3 and -9 expressing cells and the association with clinico-pathological parameters in cervical cancer. Galectin expression was scored in tumor cells, tumor epithelium infiltrating immune cells and stromal cells in squamous cervical cancer (n = 160). Correlations with clinico-pathological parameters and survival were studied according to the REMARK recommendations. We additionally investigated whether the galectins were expressed by tumor cells, fibroblasts, macrophages and T cells. Galectin-1 and -9 were both expressed by tumor cells in 11% of samples, while 84% expressed galectin-3. Strong galectin-1 expression by tumor cells was an independent predictor for poor survival (hazard ratio: 8.02, p = 0.001) and correlated with increased tumor invasion (p = 0.032) and receiving post-operative radiotherapy (p = 0.020). Weak and positive tumor cell galectin-3 expression were correlated with increased and decreased tumor invasion, respectively (p = 0.012). Tumor cell expression of galectin-9 showed a trend toward improved survival (p = 0.087). The predominant immune cell type expressing galectin-1, -3 and -9 were CD163⁺ macrophages. Galectin-1 and -3 were expressed by a minor population of T cells. Galectin-1 was mainly expressed by fibroblasts in the tumor stroma. To conclude, while tumor cell expression of galectin-9 seemed to represent a beneficial response, galectin-1 expression might be used as a marker for a more aggressive anti-cancer treatment.

Study of galectins in tumor immunity: strategies and methods

During the past decade, a better understanding of the cellular and molecular mechanisms underlying tumor immunity has provided the appropriate framework for the development of therapeutic strategies for cancer immunotherapy. Under this complex scenario, galectins have emerged as promising molecular targets for cancer therapy responsible of creating immunosuppressive microenvironments at sites of tumor growth and metastasis. Galectins, expressed in tumor, stromal, and endothelial cells, contribute to thwart the development of immune responses by favoring the expansion of T regulatory cells and contributing to their immunosuppressive activity, driving the differentiation of tolerogenic dendritic cells, limiting T cell viability, and maintaining T cell anergy. The emerging data promise a future scenario in which the selective blockade of individual members of the galectin family, either alone or in combination with other therapeutic regimens, will contribute to halt tumor progression by counteracting tumor-immune escape. Here we describe a selection of methods used to investigate the role of galectin-1 in tumor-immune escape.

Galectins: Double-edged Swords in the Cross-roads of Pregnancy Complications and Female Reproductive Tract Inflammation and Neoplasia

Galectins are an evolutionarily ancient and widely expressed family of lectins that have unique glycan-binding characteristics. They are pleiotropic regulators of key biological processes, such as cell growth, proliferation, differentiation, apoptosis, signal transduction, and pre-mRNA splicing, as well as homo- and heterotypic cell-cell and cell-extracellular matrix interactions. Galectins are also pivotal in immune responses since they regulate host-pathogen interactions, innate and adaptive immune responses, acute and chronic inflammation, and immune tolerance. Some galectins are also central to the regulation of angiogenesis, cell migration and invasion. Expression and functional data provide convincing evidence that, due to these functions, galectins play key roles in shared and unique pathways of normal embryonic and placental development as well as oncodevelopmental processes in tumorigenesis. Therefore, galectins may sometimes act as double-edged swords since they have beneficial but also harmful effects for the organism. Recent advances facilitate the use of galectins as biomarkers in obstetrical syndromes and in various malignancies, and their therapeutic applications are also under investigation. This review provides a general overview of galectins and a focused review of this lectin subfamily in the context of inflammation, infection and tumors of the female reproductive tract as well as in normal pregnancies and those complicated by the great obstetrical syndromes.

Galectin expression in cancer diagnosis and prognosis: A systematic review

Galectins are a family of proteins that bind to specific glycans thereby deciphering the information captured within the glycome. In the last two decades, several galectin family members have emerged as versatile modulators of tumor progression. This has initiated the development and preclinical assessment of galectin-targeting compounds. With the first compounds now entering clinical trials it is pivotal to gain insight in the diagnostic and prognostic value of galectins in cancer as this will allow a more rational selection of the patients that might benefit most from galectin-targeted therapies. Here, we present a systematic review of galectin expression in human cancer patients. Malignant transformation is frequently associated with altered galectin expression, most notably of galectin-1 and galectin-3. In most cancers, increased galectin-1 expression is associated with poor prognosis while elevated galectin-9 expression is emerging as a marker of favorable disease outcome. The prognostic value of galectin-3 appears to be tumor type dependent and the other galectins require further investigation. Regarding the latter, additional studies using larger patient cohorts are essential to fully unravel the diagnostic and prognostic value of galectin expression. Furthermore, to better compare different findings, consensus should be reached on how to assess galectin expression, not only with regard to localization within the tissue and within cellular compartments but also regarding alternative splicing and genomic variations. Finally, linking galectin expression and function to aberrant glycosylation in cancer cells will improve our understanding of how these versatile proteins can be exploited for diagnostic, prognostic and even therapeutic purposes in cancer patients.

Galectins in cancer: carcinogenesis, diagnosis and therapy

A major breakthrough in the field of medical oncology has been the discovery of galectins and their role in cancer development, progression and metastasis. In this review article we have condensed the results of a number of studies published over the past decade in an effort to shed some light on the unique role played by the galectin family of proteins in neoplasia, and how this knowledge may alter the approach to cancer diagnosis as well as therapy in the future. In this review we have also emphasized the potential use of galectin inhibitors or modulators in the treatment of cancer and how this novel treatment modality may affect patient outcomes in the future. Based on current pre-clinical models we believe the use of galectin inhibitors/modulators will play a significant role in cancer treatment in the future. Early clinical studies are underway to evaluate the utility of these promising agents in cancer patients.

Galectin-4 serves as a prognostic biomarker for the early recurrence / metastasis of hepatocellular carcinoma

Galectin-4 is a multifunctional lectin found at both intracellular and extracellular sites. It could serve as a tumor suppressor intracellularly and promote tumor metastases extracellularly during colorectal cancer development. However, galectin-4 expression and its prognostic value for patients with hepatocellular carcinoma (HCC) have not been well investigated. Here we report that galectin-4 was significantly downregulated in early recurrent/metastatic HCC patients, when compared to non-recurrent/metastatic HCC patients. Low expression of gelectin-4 was well associated with larger tumor size, microvascular invasion, malignant differentiation, more advanced TNM stage, and poor prognosis. Cancer cell migration and invasion could be significantly reduced through overexpression of galectin-4, but upregulated by knocking down of galectin-4 in vitro. Moreover, the serum galectin-4 level could be significantly elevated solely by hepatitis B virus infection. Combined with clinicopathological features, the higher serologic level of galectin-4 was well associated with more aggressive characteristics of HCC. Taken together, galectin-4 expression closely associates with HCC progression and might have potential use as a prognostic biomarker for HCC patients.

Vascular endothelial growth factor C enhances cervical cancer cell invasiveness via upregulation of galectin-3 protein

Vascular endothelial growth factor C (VEGF-C) promotes cervical cancer metastasis, while the detailed mechanism remains obscure. Recent evidence shows that galectin-3 (Gal-3), a glycan binding protein, interacts with the VEGF receptors and reinforces their signal transduction. In this study, we investigated the role of Gal-3 in VEGF-C-induced cervical cancer cell invasion. On cervical carcinoma cell line SiHa cells, silencing of Gal-3 expression with specific siRNA largely impaired VEGF-C-enhanced cell invasion. Treatment with VEGF-C for 12-48 h enhanced Gal-3 protein expression, which was inhibited by the addition of NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC). Moreover, the silencing of NF-κB subunit p65 expression with specific siRNA attenuated VEGF-C-enhanced Gal-3 expression, suggesting that NF-κB is the key intermediate. Under VEGF-C stimulation, an enhanced interaction between VEGF receptor-3 (VEGF-R3) and Gal-3 was found, which may possibly lead to VEGF-R3 activation since exogenous Gal-3 induced VEGF-R3 phosphorylation in a dose- and time-dependent manner. In conclusion, our findings implied that VEGF-C enhanced cervical cancer invasiveness via upregulation of Gal-3 protein through NF-κB pathway, which may shed light on potential therapeutic strategies for cervical cancer therapy.

Galectin-1 has potential prognostic significance and is implicated in clear cell renal cell carcinoma progression through the HIF/mTOR signaling axis

BACKGROUND

Metastatic clear cell renal cell carcinoma (ccRCC) patients have <9% 5-year survival rate, do not respond well to targeted therapy and eventually develop resistance. A better understanding of molecular pathways of RCC metastasis is the basis for the discovery of novel prognostic markers and targeted therapies.

METHODS

We investigated the biological impact of galectin-1 (Gal-1) in RCC cell lines by migration and invasion assays. Effect of Gal-1 expression on the mitogen-activated protein kinase pathway was assessed by proteome array.

RESULTS

Increased expression of Gal-1 increased cell migration while knocking down Gal-1 expression by siRNA resulted in reduced cellular migration (P<0.001) and invasion (P<0.05). Gal-1 overexpression increased phosphorylation of Akt, mTOR and p70 kinase. Upon hypoxia and increased HIF-1α, Gal-1 increased in a dose-dependent manner. We also found miR-22 overexpression resulted in decreased Gal-1 and HIF-1α. Immunohistochemistry analysis showed that high Gal-1 protein expression was associated with larger size tumor (P=0.034), grades III/IV tumors (P<0.001) and shorter disease-free survival (P=0.0013). Using the Cancer Genome Atlas data set, we found that high Gal-1 mRNA expression was associated with shorter overall survival (41 vs 78 months; P<0.01).

CONCLUSIONS

Our data suggest Gal-1 mediates migration and invasion through the HIF-1α-mTOR signaling axis and is a potential prognostic marker and therapeutic target.

Intracellular galectins in cancer cells: potential new targets for therapy (Review)

Dysregulation of galectin expression is frequently observed in cancer tissues. Such an abnormal expression pattern often correlates with aggressiveness and relapse in many types of cancer. Because galectins have the ability to modulate functions that are important for cell survival, migration and metastasis, they also represent attractive targets for cancer therapy. This has been well-exploited for extracellular galectins, which bind glycoconjugates expressed on the surface of cancer cells. Although the existence of intracellular functions of galectins has been known for many years, an increasing number of studies indicate that these proteins can also alter tumor progression through their interaction with intracellular ligands. In fact, in some instances, the interactions of galectins with their intracellular ligands seem to occur independently of their carbohydrate recognition domain. Such findings call for a change in the basic assumptions, or paradigms, concerning the activity of galectins in cancer and may force us to revisit our strategies to develop galectin antagonists for the treatment of cancer.

Hierarchical and selective roles of galectins in hepatocarcinogenesis, liver fibrosis and inflammation of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents a global health problem. Infections with hepatitis B or C virus, non-alcoholic steatohepatitis disease, alcohol abuse, or dietary exposure to aflatoxin are the major risk factors to the development of this tumor. Regardless of the carcinogenic insult, HCC usually develops in a context of cirrhosis due to chronic inflammation and advanced fibrosis. Galectins are a family of evolutionarily-conserved proteins defined by at least one carbohydrate recognition domain with affinity for β-galactosides and conserved sequence motifs. Here, we summarize the current literature implicating galectins in the pathogenesis of HCC. Expression of "proto-type" galectin-1, "chimera-type" galectin-3 and "tandem repeat-type" galectin-4 is up-regulated in HCC cells compared to their normal counterparts. On the other hand, the "tandem-repeat-type" lectins galectin-8 and galectin-9 are down-regulated in tumor hepatocytes. The abnormal expression of these galectins correlates with tumor growth, HCC cell migration and invasion, tumor aggressiveness, metastasis, postoperative recurrence and poor prognosis. Moreover, these galectins have important roles in other pathological conditions of the liver, where chronic inflammation and/or fibrosis take place. Galectin-based therapies have been proposed to attenuate liver pathologies. Further functional studies are required to delineate the precise molecular mechanisms through which galectins contribute to HCC.