Alteration of the cytoplasmic/nuclear expression pattern of galectin-3 correlates with prostate carcinoma progression

Tumor-Intrinsic Galectin-3 Suppresses Melanoma Metastasis

Melanoma poses a poor prognosis with high mortality rates upon metastasis. Exploring the molecular mechanisms governing melanoma progression paves the way for developing novel approaches to control melanoma metastasis and ultimately enhance patient survival rates. Extracellular galectin-3 (Gal-3) has emerged as a pleiotropic promoter of melanoma metastasis, exerting varying activities depending on its interacting partner. However, whether intracellular Gal-3 promotes melanoma aggressive behavior remains unknown. In this study, we explored Gal-3 expression in human melanoma tissues as well as in murine melanoma models to examine its causal role in metastatic behavior. We found that Gal-3 expression is downregulated in metastatic melanoma tissues compared with its levels in primary melanomas. Enforced silencing of Gal-3 in melanoma cells promoted migration, invasion, colony formation, in vivo xenograft growth, and metastasis and activated canonical oncogenic signaling pathways. Moreover, loss of Gal-3 in melanoma cells resulted in upregulated the expression of the prometastatic transcription factor NFAT1 and its downstream metastasis-associated proteins, matrix metalloproteinase 3, and IL-8. Overall, our findings implicate melanoma intracellular Gal-3 as a major determinant of its metastatic behavior and reveal a negative regulatory role for Gal-3 on the expression of NFAT1 in melanoma cells.

Prostate cancer: Novel genetic and immunologic biomarkers

Prostate cancer (PCa) is considered one of the most prevalent male malignancies worldwide with a global burden estimated to increase over the next two decades. Due to significant mortality and debilitation of survival, early diagnosis has been described as key. Unfortunately, current diagnostic serum-based strategies have low specificity and sensitivity. Histologic examination is invasive and not useful for treatment and monitoring purposes. Hence, a plethora of studies have been conducted to identify and validate an efficient noninvasive approach in the diagnosis, staging, and prognosis of PCa. These investigations may be categorized as genetic (non-coding biomarkers and gene markers), immunologic (immune cells, interleukins, cytokines, antibodies, and auto-antibodies), and heterogenous (PSA-related markers, PHI-related indices, and urinary biomarkers) subgroups. This review examines current approaches and potential strategies using biomarker panels in PCa.

Biomarkers in Cancer Detection, Diagnosis, and Prognosis

Biomarkers are vital in healthcare as they provide valuable insights into disease diagnosis, prognosis, treatment response, and personalized medicine. They serve as objective indicators, enabling early detection and intervention, leading to improved patient outcomes and reduced costs. Biomarkers also guide treatment decisions by predicting disease outcomes and facilitating individualized treatment plans. They play a role in monitoring disease progression, adjusting treatments, and detecting early signs of recurrence. Furthermore, biomarkers enhance drug development and clinical trials by identifying suitable patients and accelerating the approval process. In this review paper, we described a variety of biomarkers applicable for cancer detection and diagnosis, such as imaging-based diagnosis (CT, SPECT, MRI, and PET), blood-based biomarkers (proteins, genes, mRNA, and peptides), cell imaging-based diagnosis (needle biopsy and CTC), tissue imaging-based diagnosis (IHC), and genetic-based biomarkers (RNAseq, scRNAseq, and spatial transcriptomics).

Development of Galectin-3 Targeting Drugs for Therapeutic Applications in Various Diseases

Galectin-3 (Gal3) is one of the most studied members of the galectin family that mediate various biological processes such as growth regulation, immune function, cancer metastasis, and apoptosis. Since Gal3 is pro-inflammatory, it is involved in many diseases that are associated with chronic inflammation such as cancer, organ fibrosis, and type 2 diabetes. As a multifunctional protein involved in multiple pathways of many diseases, Gal3 has generated significant interest in pharmaceutical industries. As a result, several Gal3-targeting therapeutic drugs are being developed to address unmet medical needs. Based on the PubMed search of Gal3 to date (1987-2023), here, we briefly describe its structure, carbohydrate-binding properties, endogenous ligands, and roles in various diseases. We also discuss its potential antagonists that are currently being investigated clinically or pre-clinically by the public and private companies. The updated knowledge on Gal3 function in various diseases could initiate new clinical or pre-clinical investigations to test therapeutic strategies, and some of these strategies could be successful and recognized as novel therapeutics for unmet medical needs.

Gal-3 Protein Expression and Localization in Prostate Tumours

Gal-3 plays an important role in cell survival, mRNA splicing, and cell–cell and cell–matrix interactions. Depending on its cellular localization and cancer type, Gal-3 may have tumour-suppressive or tumour-promoting activities. Given the promising diagnostic role of Gal-3 in the urine of PCa patients found in our previous study, its concordant gene and protein expression levels, and its involvement in PCa-related biological processes (e.g., morphogenesis of the prostate gland epithelium), we aimed to investigate this protein immunohistochemically in tumour and normal prostate tissues. Gal-3 protein expression was evaluated in 48 tumour prostate tissues, eight normal prostate tissues and 14 adjacent-normal prostate tissues. Decreased Gal-3 staining was detected in tumour tissues compared with normal tissues. Although Gal-3 staining was decreased in tumour tissues with GS 5-8 and pT2 and pT3 stages compared with normal prostate tissue, no correlation was found between Gal-3 expression and PCa progression. In the present study, the pattern of cellular localization differed between groups, as Gal-3 was predominantly excluded from the nucleus in tumour tissues. Furthermore, Gal-3 had no significant effect on survival and relapse in these PCa patients. This work confirms Gal-3 as a promising marker for PCa diagnosis.

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.

Clinical significance of galectin-3 expression in urinary bladder carcinoma

OBJECTIVE

To uncover the clinical significance of galectin-3 in the evolution of urinary bladder cancer by defining galectin-3 expression and examining the relationship between its expression in a group of urothelial carcinomas versus normal tissues along with clinicopathological factors.

METHODS

This retrospective study included histopathological reports and archival blocks and slides of all patients with urinary bladder cancer treated at King Abdulaziz University Hospital (Jeddah, Saudi Arabia). An anti-galectin-3 monoclonal antibody was used for immunohistochemical staining of tissue microarray slides comprising 128 cases of urothelium carcinoma and 24 specimens of normal bladder mucosa.

RESULTS

Galectin-3 was downregulated during transformation, with positive expression found in 50 (39%) urinary bladder neoplasms, of which 33 (66%) showed weak immunostaining. All positively-stained malignant tumor and normal bladder mucosa samples showed cytoplasmic staining; a few samples also showed nuclear staining. No correlation was noted between galectin-3 and histotype, grade, stage, muscularis propria invasion, lymph node invasion, vascular invasion, or metastasis. A Cox proportional hazards model and Kaplan-Meier survival curves did not show differences in survival on the basis of galectin-3 expression.

CONCLUSION

Galectin-3 is down-regulated in bladder cancer but is not a helpful marker for the diagnosis or prognosis of urinary bladder cancer.

Distinct cholangiocarcinoma cell migration in 2D monolayer and 3D spheroid culture based on galectin-3 expression and localization

Introduction

Cholangiocarcinoma (CCA) is difficult to cure due to its ineffective treatment and advanced stage diagnosis. Thoroughly mechanistic understandings of CCA pathogenesis crucially help improving the treatment success rates. Using three-dimensional (3D) cell culture platform offers several advantages over a traditional two-dimensional (2D) culture as it resembles more closely to in vivo tumor.

Methods

Here, we aimed to establish the 3D CCA spheroids with lowly (KKU-100) and highly (KKU-213A) metastatic potentials to investigate the CCA migratory process and its EMT-associated galectin-3 in the 3D setting.

Results and discussion

Firstly, the growth of lowly metastatic KKU-100 cells was slower than highly metastatic KKU-213A cells in both 2D and 3D systems. Hollow formation was observed exclusively inside the KKU-213A spheroids, not in KKU-100. Additionally, the migration activity of KKU-213A cells was higher than that of KKU-100 cells in both 2D and 3D systems. Besides, altered expression of galectin-3 were observed across all CCA culture conditions with substantial relocalization from inside the 2D cells to the border of spheroids in the 3D system. Notably, the CCA migration was inversely proportional to the galectin-3 expression in the 3D culture, but not in the 2D setting. This suggests the contribution of culture platforms to the alternation of the CCA cell migration process.

Conclusions

Thus, our data revealed that 3D culture of CCA cells was phenotypically distinct from 2D culture and pointed to the superiority of using the 3D culture model for examining the CCA cellular mechanisms, providing knowledges that are better correlated with CCA phenotypes in vivo.

Molecular regulation of prostate cancer by Galectin-3 and estrogen receptor

Prostate cancer remains the most prevalent cancer among men worldwide. This cancer is hormone-dependent; therefore, androgen, estrogen, and their receptors play an important role in development and progression of this disease, and in emergence of the castration-resistant prostate cancer (CRPC). Galectins are a family of β-galactoside-binding proteins which are frequently altered (upregulated or downregulated) in a wide range of tumors, participating in different stages of tumor development and progression, but the molecular mechanisms which regulate its expression are still poorly understood. This review provides an overview of the current and emerging knowledge on Galectin-3 in cancer biology with focus on prostate cancer and the interplay with estrogen receptor (ER) signaling pathways, present in androgen-independent prostate cancer cells. We suggest a molecular mechanism where ER, Galectin-3 and β-catenin can modulate nuclear transcriptional events, such as, proliferation, migration, invasion, and anchorage-independent growth of androgen-independent prostate cancer cells. Despite a number of achievements in targeted therapy for prostate cancer, CRPC may eventually develop, therefore new effective drug targets need urgently to be found. Further understanding of the role of Galectin-3 and ER in prostate cancer will enhance our understanding of the molecular mechanisms of prostate cancer development and the future treatment of this disease.

Predictive role of galectin-3 for immune checkpoint blockades (ICBs) in advanced or metastatic non-small cell lung cancer: a potential new marker for ICB resistance

PURPOSE

We aimed to assess the predictive value of galectin-3 (Gal-3) in patients with non-small cell lung cancer (NSCLC) treated with immune checkpoint blockades (ICBs) therapy using both enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC).

METHODS

This retrospective study was conducted at Seoul National University Hospital. Patients with EGFR/ALK-wild-type advanced or metastatic NSCLC who received ICBs between December 2013 and December 2019 were enrolled. Patients with archived blood samples collected prior to ICB treatment were assigned to the ELISA cohort. In addition, those with tissue samples from sites of recurrence or metastasis were assigned to an IHC cohort. Then, we analyzed Gal-3 expression in both cohorts.

RESULTS

Fifty-six patients in the ELISA cohort were grouped into low (N = 36) and high (N = 20) groups, using the mean Gal-3 ELISA level (13.24 pg/ml) as a cutoff. The high group demonstrated trends toward reduced progression-free survival (PFS) (0.9 vs. 3.7 months, p = 0.196) and significantly shorter overall survival (OS) (1.6 vs. 12.3 months, p = 0.018) than the low group. We categorized 94 patients in the IHC cohort into negative (N = 31) and positive (N = 63) groups based on Gal-3 IHC positivity. However, the median PFS (4.6 vs. 4.6 months for the negative vs. positive IHC group, respectively, p = 0.345) and OS (16.4 vs. 9.0 months, p = 0.137) were not significantly different.

CONCLUSION

High blood Gal-3 levels may predict inferior survival in patients with advanced or metastatic NSCLC treated with ICBs.

Association between Galectin Levels and Neurodegenerative Diseases: Systematic Review and Meta-Analysis

Galectins are a family of proteins with an affinity for β-galactosides that have roles in neuroprotection and neuroinflammation. Several studies indicate that patients with neurodegenerative diseases have alterations in the concentration of galectins in their blood and brain. However, the results of the studies are contradictory; hence, a meta-analysis is performed to clarify whether patients with neurodegenerative diseases have elevated galectin levels compared to healthy individuals. Related publications are obtained from the databases: PubMed, Central-Conchrane, Web of Science database, OVID-EMBASE, Scope, and EBSCO host until February 2022. A pooled standard mean difference (SMD) with a 95% confidence interval (CI) is calculated by fixed-effect or random-effect model analysis. In total, 17 articles are included in the meta-analysis with a total of 905 patients. Patients with neurodegenerative diseases present a higher level of galectin expression compared to healthy individuals (MDS = 0.70, 95% CI 0.28-1.13, p = 0.001). In the subgroup analysis by galectin type, a higher galectin-3 expression is observed in patients with neurodegenerative diseases. Patients with Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALD), and Parkinson's disease (PD) expressed higher levels of galectin-3. Patients with multiple sclerosis (MS) have higher levels of galectin-9. In conclusion, our meta-analysis shows that patients with neurovegetative diseases have higher galectin levels compared to healthy individuals. Galectin levels are associated with the type of disease, sample, detection technique, and region of origin of the patients.

Use of Glycoproteins-Prostate-Specific Membrane Antigen and Galectin-3 as Primary Tumor Markers and Therapeutic Targets in the Management of Metastatic Prostate Cancer

Simple Summary

Prostate specific membrane antigen and galectins are proteins expressed on cell surface and their expression is associated with cancer growth and spread. The goal of this research was to look at the pattern of these two glycoproteins in the human prostate cancer microenvironment. Prostate specific membrane antigen and galectins-1,3 and 8 were the most frequently detected glycoproteins in various phases of this disease. Furthermore, prostate specific membrane antigen and galectin-3 expression are good indicators of tumor aggressiveness, and their combined expression can be valuable tool for prostate cancer diagnosis and treatment in future. Together, our findings reveal a tightly regulated “Prostate specific membrane antigen-galectin-pattern” that accompanies disease in prostate cancer and point to a key role for combined prostate specific membrane antigen and galectin-3 inhibitors in prostate cancer treatment along with standard chemotherapy.

Abstract

Galectins and prostate specific membrane antigen (PSMA) are glycoproteins that are functionally implicated in prostate cancer (CaP). We undertook this study to analyze the “PSMA-galectin pattern” of the human CaP microenvironment with the overarching goal of selecting novel-molecular targets for prognostic and therapeutic purposes. We examined CaP cells and biopsy samples representing different stages of the disease and found that PSMA, Gal-1, Gal-3, and Gal-8 are the most abundantly expressed glycoproteins. In contrast, other galectins such as Gal-2, 4–7, 9–13, were uniformly expressed at lower levels across all cell lines. However, biopsy samples showed markedly higher expression of PSMA, Gal-1 and Gal-3. Independently PSA and Gleason score at diagnosis correlated with the expression of PSMA, Gal-3. Additionally, the combined index of PSMA and Gal-3 expression positively correlated with Gleason score and was a better predictor of tumor aggressiveness. Together, our results recognize a tightly regulated “PSMA-galectin- pattern” that accompanies disease in CaP and highlight a major role for the combined PSMA and Gal-3 inhibitors along with standard chemotherapy for prostate cancer treatment. Inhibitor combination studies show enzalutamide (ENZ), 2-phosphonomethyl pentanedioic acid (2-PMPA), and GB1107 as highly cytotoxic for LNCaP and LNCaP-KD cells, while Docetaxel (DOC) + GB1107 show greater efficacy in PC-3 cells. Overall, 2-PMPA and GB1107 demonstrate synergistic cytotoxic effects with ENZ and DOC in various CaP cell lines.

Immunoprotective neo-glycoproteins: Chemoenzymatic synthesis of multivalent glycomimetics for inhibition of cancer-related galectin-3

Galectin-3 plays a crucial role in cancerogenesis; its targeting is a prospective pathway in cancer diagnostics and therapy. Multivalent presentation of glycans was shown to strongly increase the affinity of glycoconjugates to galectin-3. Further strengthening of interaction with galectin-3 may be accomplished using artificial glycomimetics with apt aryl substitutions. We established a new, as yet undescribed chemoenzymatic method to produce selective C-3-substituted N,N'-diacetyllactosamine glycomimetics and coupled them to human serum albumin. From a library of enzymes, only β-N-acetylhexosaminidase from Talaromyces flavus was able to efficiently synthesize the C-3-propargylated disaccharide. Various aryl residues were attached to the functionalized N,N'-diacetyllactosamine via click chemistry to assess the impact of the aromatic substitution. In ELISA-type assays with galectin-3, free glycomimetics exhibited up to 43-fold stronger inhibitory potency to Gal-3 than the lactose standard. Coupling to human serum albumin afforded multivalent neo-glycoproteins with up to 4209-fold increased inhibitory potency per glycan compared to the monovalent lactose standard. Surface plasmon resonance brought further information on the kinetics of galectin-3 inhibition. The potential of prepared neo-glycoproteins to target galectin-3 was demonstrated on colorectal adenocarcinoma DLD-1 cells. We investigated the uptake of neo-glycoproteins into cells and observed limited non-specific transport into the cytoplasm. Therefore, neo-glycoproteins primarily act as efficient scavengers of exogenous galectin-3 of cancer cells, inhibiting its interaction with the cell surface, and protecting T-lymphocytes against galectin-3-induced apoptosis. The present neo-glycoproteins combine the advantage of a straightforward synthesis, selectivity, non-toxicity, and high efficiency for targeting exogenous galectin-3, with possible application in the immunomodulatory treatment of galectin-3-overexpressing cancers.

Prognostic significance of galectin-3 expression in patients with resected NSCLC treated with platinum-based adjuvant chemotherapy

BACKGROUND

Galectin-3 (GAL3), a protein encoded by the LGALS3 gene, plays diverse roles in cancer initiation, progression, and drug resistance. Accordingly, high GAL3 expression in tumor cells is associated with poor prognosis in non-small cell lung cancer (NSCLC). However, the prognostic impact of GAL3 expression on patients with resected NSCLC receiving platinum-based adjuvant chemotherapy (AC) remains unclear. This study aimed to determine the prognostic significance of GAL3 expression in NSCLC patients receiving platinum-based AC.

METHODS

The study included 111 patients with completely resected stages II and IIIA NSCLC who were receiving platinum-based AC. GAL3 expression in cancer cells was evaluated immunohistochemically according to H-score ("histo score), with a score of ≥170 considered as high expression. The correlation of GAL3 expression with clinicopathological characteristics and survival was subsequently evaluated.

RESULTS

In survival analysis, GAL3 expression was significantly associated with recurrence-free survival (RFS) and overall survival (OS). In multivariate analysis, GAL3 expression was an independent predictive factor of RFS rather than OS.

CONCLUSIONS

GAL3 expression is a reliable biomarker to predict the prognosis of completely resected NSCLC patients receiving platinum-based AC.

Mechanistic Biomarkers Informative of Both Cancer and Cardiovascular Disease: JACC State-of-the-Art Review

Cardiovascular disease (CVD) and cancer are leading causes of morbidity and mortality worldwide. Although conventionally managed as separate disease processes, recent research has lent insight into compelling commonalities between CVD and cancer, including shared mechanisms for disease development and progression. In this review, the authors discuss several pathophysiological processes common to both CVD and cancer, such as inflammation, resistance to cell death, cellular proliferation, neurohormonal stress, angiogenesis, and genomic instability, in an effort to understand common mechanisms of both disease states. In particular, the authors highlight key circulating and genomic biomarkers associated with each of these processes, as well as their associations with risk and prognosis in both cancer and CVD. The purpose of this state-of-the-art review is to further our understanding of the potential mechanisms underlying cancer and CVD by contextualizing pathways and biomarkers common to both diseases.

Non-classical role of Galectin-3 in cancer progression: translocation to nucleus by carbohydrate-recognition independent manner

Galectin-3 is a carbohydrate-binding protein and regulates diverse functions, including cell proliferation and differentiation, mRNA splicing, apoptosis induction, immune surveillance and inflammation, cell adhesion, angiogenesis, and cancer-cell metastasis. Galectin-3 is also recommended as a diagnostic or prognostic biomarker of various diseases, including heart disease, kidney disease, and cancer. Galectin-3 exists as a cytosol, is secreted in extracellular spaces on cells, and is also detected in nuclei. It has been found that galectin-3 has different functions in cellular localization: (i) Extracellular galectin-3 mediates cell attachment and detachment. (ii) cytosolic galectin-3 regulates cell survival by blocking the intrinsic apoptotic pathway, and (iii) nuclear galectin-3 supports the ability of the transcriptional factor for target gene expression. In this review, we focused on the role of galectin-3 on translocation from cytosol to nucleus, because it happens in a way independent of carbohydrate recognition and accelerates cancer progression. We also suggested here that intracellular galecin-3 could be a potent therapeutic target in cancer therapy. [BMB Reports 2020; 53(4): 173-180].

Galectin-3 in Prostate Cancer Stem-Like Cells Is Immunosuppressive and Drives Early Metastasis

Galectin-3 (Gal-3) is an extracellular matrix glycan-binding protein with several immunosuppressive and pro-tumor functions. The role of Galectin-3 in cancer stem-like cells (CSCs) is poorly investigated. Here, we show that prostate CSCs also colonizing prostate-draining lymph nodes of transgenic adenocarcinoma of the mouse prostate (TRAMP) mice overexpress Gal-3. Gal-3 contributes to prostate CSC-mediated immune suppression because either Gal-3 silencing in CSCs, or co-culture of CSCs and T cells in the presence of the Gal-3 inhibitor N-Acetyl-D-lactosamine rescued T cell proliferation. N-Acetyl-D-lactosamine also rescued the proliferation of T cells in prostate-draining lymph nodes of TRAMP mice affected by prostate intraepithelial neoplasia. Additionally, Gal-3 impacted prostate CSC tumorigenic and metastatic potential in vivo, as Gal-3 silencing in prostate CSCs reduced both primary tumor growth and secondary invasion. Gal-3 was also found expressed in more differentiated prostate cancer cells, but with different intracellular distribution as compared to CSCs, which suggests different functions of Gal-3 in the two cell populations. In fact, the prevalent nuclear and cytoplasmic distribution of Gal-3 in prostate CSCs made them less susceptible to apoptosis, when compared to more differentiated prostate cancer cells, in which Gal-3 was predominantly intra-cytoplasmic. Finally, we found Gal-3 expressed in human and mouse prostate intraepithelial neoplasia lesions and in metastatic lymph nodes. All together, these findings identify Gal-3 as a key molecule and a potential therapeutic target already in the early phases of prostate cancer progression and metastasis.

Glycopolymers for Efficient Inhibition of Galectin-3: In Vitro Proof of Efficacy Using Suppression of T Lymphocyte Apoptosis and Tumor Cell Migration

The development of efficient galectin-3 (Gal-3) inhibitors draws attention in the field of anti-cancer therapy, especially due to the prominent role of extra- and intracellular Gal-3 in vital processes of cancerogenesis, such as immunosuppression, stimulation of tumor cells proliferation, survival, invasion, apoptotic resistance, and metastasis formation and progression. Here, by combining poly-LacNAc (Galβ4GlcNAc)-derived oligosaccharides with N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers, we synthesized multivalent glycopolymer inhibitors with a high potential to target extracellular and intracellular Gal-3. The inhibitory capabilities of the best conjugate in the studied series were in the nanomolar range proving the excellent Gal-3 inhibitory potential. Moreover, thorough investigation of the inhibitory effect in the biological conditions showed that the glycopolymers strongly inhibited Gal-3-induced apoptosis of T lymphocytes and suppressed migration and spreading of colorectal, breast, melanoma, and prostate cancer cells. In sum, the strong inhibitory activity toward Gal-3, combined with favorable pharmacokinetics of HPMA copolymers ensuring enhanced tumor accumulation via the enhanced permeability and retention effect, nominate the glycopolymers containing LacdiNAc-LacNAc (GalNAcβ4GlcNAcβ3Galβ4GlcNAc) tetrasaccharide as promising tools for preclinical in anti-cancer therapy evaluation.

Relationship of Galectin-3 Expression in Canine Cutaneous Squamous Cell Carcinomas with Histopathological Grading and Proliferation Indices

Squamous cell carcinoma (SCC) is a frequent malignant neoplasm of the skin that usually arises from areas of solar dermatosis. It is characterized by local invasiveness and regional lymph node metastasis, mainly in poorly differentiated tumours. Galectin-3 (Gal-3) is a lectin that is expressed in the nucleus or cytoplasm and has been identified as a prognostic tool for human neoplasms. The purpose of this study was to characterize Gal-3 expression in canine cutaneous SCCs and to investigate its relationship with tumour differentiation and cell proliferation indices. Immunohistochemical analysis of 50 SCCs for Gal-3 revealed no correlation between the localization or intensity of immunolabelling, or number of immunopositive cells, with histological grade of tumour or proliferative activity. The results suggest that Gal-3 expression is not a reliable prognostic marker for cutaneous SCC in dogs.

Low Galectin-3 Expression Level in Primary Tumors Is Associated with Metastasis in T1 Lung Adenocarcinoma

BACKGROUND AND OBJECTIVE

Although nodal and distant metastasis is rare in T1 lung adenocarcinoma, it is related to poor clinical prognosis. Association between galectin-3 (Gal-3) expression level, and clinical outcome of T1 lung adenocarcinoma has not been clarified.

METHODS

From January 2009 to December 2014, 74 patients with surgically resected T1 lung adenocarcinoma were enrolled in this retrospective cohort study. Patient outcomes were followed up until December 2019. Gal-3 expression level in primary tumors was assessed immunohistochemically and evaluated based on the staining intensity and percentage. Patient characteristics and correlation between Gal-3 expression level and clinical outcomes were reviewed.

RESULTS

Low Gal-3 expression was associated with increased metastatic events (p = 0.03), especially distant metastasis (p = 0.007), and mortality rate (p = 0.04). Kaplan-Meier analysis revealed that high Gal-3 expression level was associated with favorable recurrence-free survival in T1 lung adenocarcinoma (log-rank p = 0.048) and T1a (≤ 2 cm, American Joint Committee on Cancer (AJCC) 7th edition) lung adenocarcinoma (log-rank p = 0.043). Gal-3 expression along with tumor size showed a larger area under curve (AUC) than tumor size alone for predicting metastatic events (AUC = 0.747 vs. 0.681) and recurrence (AUC = 0.813 vs. 0.766) in T1a lung adenocarcinoma in the receiver-operating characteristic curve.

CONCLUSION

Low Gal-3 expression level in primary tumors was remarkably associated with increased metastatic events and reduced recurrence-free survival in T1 lung adenocarcinoma. We suggest that Gal-3 expression level in addition to tumor size may potentially be stronger than tumor size alone in predicting metastasis in T1a lung adenocarcinoma patients.

Galectins in prostate and bladder cancer: tumorigenic roles and clinical opportunities

Advanced prostate and bladder cancer are two outstanding unmet medical needs for urological oncologists. The high prevalence of these tumours, lack of effective biomarkers and limited effective treatment options highlight the importance of basic research in these diseases. Galectins are a family of β-galactoside-binding proteins that are frequently altered (upregulated or downregulated) in a wide range of tumours and have roles in different stages of tumour development and progression, including immune evasion. In particular, altered expression levels of different members of the galectin family have been reported in prostate and bladder cancers, which, together with the aberrant glycosylation patterns found in tumour cells and the constituent cell types of the tumour microenvironment, can result in malignant transformation and tumour progression. Understanding the roles of galectin family proteins in the development and progression of prostate and bladder cancer could yield key insights to inform the clinical management of these diseases.

Prognostic role of galectin-3 expression in patients with solid tumors: a meta-analysis of 36 eligible studies

Background

Galectin-3 as a β-galactoside-binding protein, has been found to be involved in tumor cell growth, anti-apoptosis, adhesion, angiogenesis, invasion, and distant metastases, indicating that it may play a pivotal role in cancer development and progression. However, their results remain debatable and inconclusive. Hence, this meta-analysis was performed to clarify the precise predictive value of galectin-3 in various cancers.

Methods

PubMed, Web of Science, Embase, Cochrane Library, CNKI and Wanfang databases were searched comprehensively for eligible studies up to July 15, 2018. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) of OS or DFS/PFS/RFS were calculated to demonstrate their associations.

Results

A total of 36 relevant studies were ultimately enrolled in this meta-analysis. Our results shed light on the significant association of elevated galectin-3 expression with reduced OS or DFS/RFS/PFS in overall cancer patients (pooled HR = 1.79, 95% CI 1.42–2.27, I²= 67.3%, p < 0.01; pooled HR = 1.57, 95% CI 1.04–2.37, I²= 67.1%, p = 0.001). In tumor type subgroup analysis, we found high expression of galectin-3 was correlated with shorter OS or DFS/RFS/PFS in colorectal cancer (pooled HR = 3.05, 95% CI 2.13–4.35, I²= 0.0%, p = 0.734; pooled HR = 2.49, 95% CI 1.82–3.41, I² = 0.0%, p = 0.738; respectively) and meanwhile it merely associated with reduced OS in ovarian cancer or non-small cell lung cancer (pooled HR = 2.24, 95% CI 1.38–3.64, I²= 0.0%, p = 0.910; pooled HR = 2.07, 95% CI 1.48–2.88, I²= 0.0%, p = 0.563; separately).

Conclusions

Taken together, our results suggested that galectin-3 played an oncogenic role in colorectal cancer, ovarian cancer and non-small cell lung cancer, indicating it could be a promising biomarker and a novel therapeutic target for them. Further studies were warranted to validate our findings.

Galectin-3: One Molecule for an Alphabet of Diseases, from A to Z

Galectin-3 (Gal-3) regulates basic cellular functions such as cell-cell and cell-matrix interactions, growth, proliferation, differentiation, and inflammation. It is not surprising, therefore, that this protein is involved in the pathogenesis of many relevant human diseases, including cancer, fibrosis, chronic inflammation and scarring affecting many different tissues. The papers published in the literature have progressively increased in number during the last decades, testifying the great interest given to this protein by numerous researchers involved in many different clinical contexts. Considering the crucial role exerted by Gal-3 in many different clinical conditions, Gal-3 is emerging as a new diagnostic, prognostic biomarker and as a new promising therapeutic target. The current review aims to extensively examine the studies published so far on the role of Gal-3 in all the clinical conditions and diseases, listed in alphabetical order, where it was analyzed.

Runt-Related Transcription Factor 2 (Runx2) Is Responsible for Galectin-3 Overexpression in Human Thyroid Carcinoma

Runx2 promotes metastatic ability of cancer cells by directly activating some of the mediators regarding malignancy. Galectin-3 (Gal-3) extensively expressed in normal and transformed cells and it is responsible for many cellular processes. In this study, we aimed to investigate whether there is any relationship between runx2 transcription factor and regulation of galectin-3 expression in different human thyroid carcinoma cell lines. To show effects of runx2 transcription factor on gal-3 expression, we developed runx2 knockdown model in the thyroid carcinoma cell lines; anaplastic 8505C and 8305C and, papillary TPC-1 and follicular FTC-133 by using siRNA transfection. We analyzed the protein expressions and mRNA levels of gal-3 and MMP2/9 in the runx2-silenced cell lines using Western blotting, qPCR, and fluorescent microscopy. Our results showed that mRNA expression levels of gal-3 and MMP2/9 were downregulated in runx2-silenced cell lines. In this investigation, we revealed that regulation of gal-3 expression was strongly correlated with runx2 transcription factor in human thyroid carcinoma. Considering the contribution of human gal-3 in collaboration with MMP2/9 to the malignant characters of many cancers, regulation of their expressions through runx2 seems like one of the key regulatory mechanism for malignant potential of human thyroid carcinoma. Accordingly, runx2 transcription factor inhibitors can be a potential target in order to prevent gal-3 mediated malignancy of human thyroid carcinoma. J. Cell. Biochem. 118: 3911-3919, 2017. © 2017 Wiley Periodicals, Inc.

Role of Apoptosis in the Pathogenesis of Nasal Polyps Based Upon Galectin-3 Expression

OBJECTIVE

The authors aimed to investigate the antiapoptotic mechanisms in nasal polyps that occur after glandular hyperplasia.

STUDY DESIGN

Retrospective histopathological analyses of patients with nasal polyps.

METHODS

The study comprised 54 patients (19 females; 35 males). Group-1 patients with a diagnosis of nasal polyposis; group-2 patients with a diagnosis of antrochoanal polyps; group-3 with a diagnosis of deviation of the nasal septum as a control group. Tissues were taken during their surgery and fixed in paraffin blocks, stained to detect galectin-3, and evaluated under a light microscope. Polymorphonuclear leukocytes on the surface epithelium, glandular epithelium, and connective tissue were divided into groups according to the intensity of galectin-3 staining: "mild," "moderate," and "strong." The percentage of stained tissue was also graded: <10%, 10% to 50%, 51% to 80%, and >80%. Hence, the extent of expression of galectin-3 and percentage of stained tissue was calculated.

RESULTS

Significant differences in the staining intensity of polymorphonuclear leukocytes for galectin-3 were observed between the 3 groups (P <0.01). Staining intensity in control group was significantly lower than that in group I and group II (P = 0.001; P <0.01). However, there was no significant difference between group I and group II (P >0.05).

CONCLUSION

These findings suggest that galectin-3 has a role in the formation of nasal polyps.

Molecular regulation of galectin-3 expression and therapeutic implication in cancer progression

Galectin-3, a multifunctional protein, distributes inside and outside cells and plays an important role in tumor cell adhesion, proliferation, differentiation, angiogenesis, and metastasis in multiple tumors. Changes in galectin-3 expression are commonly seen in cancer and pre-cancerous conditions. Therefore, to understand the molecular regulation of galectin-3 expression could aid the development of new approach for cancer treatment. This review summarizes different expression of galectin-3 in cancer cells and patients' serum, the regulation mechanism and the potential therapeutic targets of galectin-3 in cancer progression.

Galectin-3 as a Potential Target to Prevent Cancer Metastasis

Interactions between two cells or between cell and extracellular matrix mediated by protein–carbohydrate interactions play pivotal roles in modulating various biological processes such as growth regulation, immune function, cancer metastasis, and apoptosis. Galectin-3, a member of the β-galactoside-binding lectin family, is involved in fibrosis as well as cancer progression and metastasis, but the detailed mechanisms of its functions remain elusive. This review discusses its structure, carbohydrate-binding properties, and involvement in various aspects of tumorigenesis and some potential carbohydrate ligands that are currently investigated to block galectin-3 activity.

A Mutation in the Carbohydrate Recognition Domain Drives a Phenotypic Switch in the Role of Galectin-7 in Prostate Cancer

The observation that galectin-7 (gal-7) is specifically expressed in mammary myoepithelial (basal) cells prompted us to investigate whether this protein is expressed in the basal cells of other tissues. Given that breast and prostate cancer have remarkable underlying biological similarities and given the important roles of basal cells in prostate cancer, we examined the expression patterns and role of gal-7 in human prostate cancer. Using tissue microarray, we found that although gal-7 is readily expressed in basal cells in normal prostate tissue, it is downregulated in prostate cancer (PCa) cells. De novo expression of gal-7 in prostate cancer cells increases their sensitivity to apoptosis in response to etoposide and cisplatin. The assessment of a carbohydrate-recognition domain (CRD)-defective mutant form of gal-7 (R7S) showed that the ability of this protein to modulate apoptosis was independent of its CRD activity. This activity was also independent of its ability to translocate to the mitochondrial and nuclear compartments. However, CRD activity was necessary to inhibit the invasive behaviors of prostate cancer cells. In vivo, gal-7 overexpression in PCa cells led to a modest yet significant reduction in tumor size, while its CRD-defective mutant form significantly increased tumor growth compared to controls. Taken together, these results suggest that although de novo expression of gal-7 may be an interesting means of increasing the tumorigenic phenotypes of PCa cells, alterations in the CRD activity of this protein drive a phenotypic switch in its role in PCa cells. This CRD-independent activity represents a paradigm shift in our understanding of the functions of galectin. The R74S model will be useful to distinguish CRD-dependent and CRD-independent functions of gal-7 in cancer progression.

Why anti-Bcl-2 clinical trials fail: a solution

The alteration in expression of B cell lymphoma-2 (Bcl-2) family of protein members in cancer is involved mainly in the regulation of apoptosis. Bcl-2 family proteins are currently used as major targets in the development of methods to improve treatment outcomes for cancer patients that underwent clinical trials. Although many agents have been developed for targeting Bcl-2 in the past decade, some previous attempts to target Bcl-2 have not resulted in beneficial clinical outcome for reasons unknown. Here, we propose that this was due in part for not considering the cellular level of a different antiapoptotic protein, i.e., galectin-3 (Gal-3). Gal-3 is a member of the β-galactoside binding protein family and a multifunctional oncogenic protein which regulates cell growth, cell adhesion, cell proliferation, angiogenesis, and apoptosis. Gal-3 is the sole protein that contains the NWGR anti-death motif of the Bcl-2 family and inhibits cell apoptosis induced by chemotherapeutic agents through phosphorylation, translocation and regulation of survival signaling pathways. It is now established that Gal-3 is a candidate target protein to suppress antiapoptotic activity and anticancer drug resistance. In this review, we describe the role and relevance of Gal-3 and Bcl-2 protein family in the regulation of apoptosis and propose a novel combination therapy modality. Combination therapy that targets Gal-3 could be essential for improvement of the efficacy of Bcl-2 targeting therapy in cancers and should be studied in future clinical trials. Otherwise, not considering Gal-3 cellular level could lead to trial failure.

Prostate cancer stroma: an important factor in cancer growth and progression

Reactive stromal changes that occur in different human cancers might play a role in local tumor spreading and progression. Studies done on various human cancers have shown activated stromal cell phenotypes, modified extracellular matrix (ECM) composition, and increased microvessel density. Furthermore, they exhibit biological markers consistent with stroma at the site of wound repair. In prostate cancer, stroma is composed of fibroblasts, myofibroblasts, endothelial cells and immune cells. Predominant cells in the tumorous stroma are, however, fibroblasts/myofibroblasts. They are responsible for the synthesis, deposition and remodeling of the ECM. Epithelial tumorous cells, in interaction with stromal cells and with the help of various molecules of ECM, create a microenvironment suitable for cancer cell proliferation, movement, and differentiation. In this review, we discussed the role of different stromal components in prostate cancer as well as their potential prognostic and therapeutic significance.

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.

Identification and validation of potential new biomarkers for prostate cancer diagnosis and prognosis using 2D-DIGE and MS

This study was designed to identify and validate potential new biomarkers for prostate cancer and to distinguish patients with and without biochemical relapse. Prostate tissue samples analyzed by 2D-DIGE (two-dimensional difference in gel electrophoresis) and mass spectrometry (MS) revealed downregulation of secernin-1 (P < 0.044) in prostate cancer, while vinculin showed significant upregulation (P < 0.001). Secernin-1 overexpression in prostate tissue was validated using Western blot and immunohistochemistry while vinculin expression was validated using immunohistochemistry. These findings indicate that secernin-1 and vinculin are potential new tissue biomarkers for prostate cancer diagnosis and prognosis, respectively. For validation, protein levels in urine were also examined by Western blot analysis. Urinary vinculin levels in prostate cancer patients were significantly higher than in urine from nontumor patients (P = 0.006). Using multiple reaction monitoring-MS (MRM-MS) analysis, prostatic acid phosphatase (PAP) showed significant higher levels in the urine of prostate cancer patients compared to controls (P = 0.012), while galectin-3 showed significant lower levels in the urine of prostate cancer patients with biochemical relapse, compared to those without relapse (P = 0.017). Three proteins were successfully differentiated between patients with and without prostate cancer and patients with and without relapse by using MRM. Thus, this technique shows promise for implementation as a noninvasive clinical diagnostic technique.

Glycans and galectins in prostate cancer biology, angiogenesis and metastasis

Prostate cancer is the second most common cause of cancer and the sixth leading cause of cancer death among men worldwide. While localized prostate cancer can be cured, advanced and metastatic prostate cancer remains a significant therapeutic challenge. Malignant transformation is associated with important modifications of the cellular glycosylation profile, and it is postulated that these changes have a considerable relevance for tumor biology. Metastasis is a multiphasic process that encompasses angiogenesis, the spread of tumor cells and their growth at distant sites from the primary tumor location. Recognition of glycoconjugates by galectins, among other lectins, plays a fundamental role in the metastatic spread, tumor immune escape and the neovascularization process. Particularly in prostate cancer, both carbohydrates and galectins have been implicated in many cellular processes such as proliferation, apoptosis, migration and invasion. However, a limited number of studies assessed their potential implications in the induction of metastasis in prostate cancer patients or in animal models. Moreover, the role of galectin-glycan interactions in vivo still remains poorly understood; concerted effort should thus be made in order to shed some light on this question. This review summarizes current evidence on both the expression and role of glycans and galectins in prostate cancer, particularly turning our attention to the angiogenic and metastatic processes.

Nuclear transport of galectin-3 and its therapeutic implications

Galectin-3, a member of β-galactoside-binding gene family is a multi-functional protein, which regulates pleiotropic biological functions such as cell growth, cell adhesion, cell-cell interactions, apoptosis, angiogenesis and mRNA processing. Its unique structure enables it to interact with a plethora of ligands in a carbohydrate dependent or independent manner. Galectin-3 is mainly a cytosolic protein, but can easily traverse the intracellular and plasma membranes to translocate into the nucleus, mitochondria or get externalized. Depending on the cell type, specific experimental conditions in vitro, cancer type and stage, galectin-3 has been reported to be exclusively cytoplasmic, predominantly nuclear or distributed between the two compartments. In this review we have summarized the dynamics of galectin-3 shuttling between the nucleus and the cytoplasm, the nuclear transport mechanisms of galectin-3, how its specific interactions with the members of β-catenin signaling pathways affect tumor progression, and its implications as a therapeutic target.

Galectin-3 in cancer

Galectin-3 (Gal-3) plays important roles in cell proliferation, adhesion, differentiation, angiogenesis and apoptosis in normal and pathologic tissues. Accumulated evidences indicate that Gal-3 is closely involved in tumor cell transformation, migration, invasion and metastasis. In this review, the associations of the expression and localization of Gal-3 as well as its potential action mechanism in tumorigenesis in a variety of cancers were summarized and concluded. Gal-3 is gaining its attraction as a potential new biomarker for the diagnosis, treatment and prognosis of certain tumors.

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.

Adiponectin attenuates osteolysis in aseptic loosening of total hip replacements

Joint replacements have a longer durability in patients with high serum levels of adiponectin (APN) than in patients with low levels. We aimed to characterize the unknown pathophysiological effects of APN on wear particle-induced inflammation, apoptosis and osteolysis. Immunohistochemistry was performed to detect APN, its receptors and apoptosis in patients with and without aseptic loosening. Additionally, APN knockout mouse studies and pharmacological intervention of APN were performed in an established calvarial mouse model. Osteolysis and inflammation were quantified by histomorphometry and microcomputed tomography, apoptosis by immunohistochemistry and TUNEL assay. In a cell culture model, human monocyte-derived macrophages were incubated with or without metal wear debris particles and partially treated with APN. Expression of APN, AdipoR1 and calreticulin in specimens from patients with aseptic loosening were significantly higher than in patients without aseptic loosening. Administration of APN in mice significantly reduced wear particle-induced inflammation, osteolysis and the number of caspase-3-positive macrophages. The cell culture model showed that APN leads to significantly lower values of TNF-α. These findings support a prominent role of APN in the development of particle-induced osteolysis and APN may be therapeutically useful in patients with aseptic loosening.

Galectins as new prognostic markers and potential therapeutic targets for advanced prostate cancers

A better understanding of multimolecular interactions involved in tumor dissemination is required to identify new effective therapies for advanced prostate cancer (PCa). Several groups investigated protein-glycan interactions as critical factors for crosstalk between prostate tumors and their microenvironment. This review both discusses whether the “galectin-signature” might serve as a reliable biomarker for the identification of patients with high risk of metastasis and assesses the galectin-glycan lattices as potential novel targets for anticancer therapies. The ultimate goal of this review is to convey how basic findings related to galectins could be in turn translated into clinical settings for patients with advanced PCa.

Galectin-1 as a potent target for cancer therapy: role in the tumor microenvironment

The microenvironment of a tumor is a highly complex milieu, primarily characterized by immunosuppression, abnormal angiogenesis, and hypoxic regions. These features promote tumor progression and metastasis, resulting in poor prognosis and greater resistance to existing cancer therapies. Galectin-1 is a β-galactoside binding protein that is abundantly secreted by almost all types of malignant tumor cells. The expression of galectin-1 is regulated by hypoxia-inducible factor-1 (HIF-1) and it plays vital pro-tumorigenic roles within the tumor microenvironment. In particular, galectin-1 suppresses T cell-mediated cytotoxic immune responses and promotes tumor angiogenesis. However, since galectin-1 displays many different activities by binding to a number of diverse N- or O-glycan modified target proteins, it has been difficult to fully understand how galectin-1 supports tumor growth and metastasis. This review explores the importance of galectin-1 and glycan expression patterns in the tumor microenvironment and the potential effects of inhibiting galectin-1 as a therapeutic target for cancer treatment.

Galectin-3: a possible complementary marker to the PSA blood test

The prostate-specific antigen (PSA) test has served as a blood marker of prostate cancer (PCa), and for monitoring recurrence/metastasis in patients after therapeutic intervention. However, the applicability/reliability of the PSA test was recently questioned as it is not without challenges, in particular in men who have PCa without an elevated PSA (false negative), or in men who are disease-free with elevated levels of PSA (false positive). Galectin-3 is a tumor-associated protein; present in the seminal fluid and is a substrate for the PSA enzyme e.g., a chymotrypsin-like serine protease. We hypothesized that the cleavage status and level of galectin-3 in the prostate tissue and sera are associated with PCa. Thus, we compared galectin-3 levels obtained from sera of non-cancer urology patients to those of metastatic PCa patients. The data were confirmed by analyzing PCa tissue arrays. Here, we report that galectin-3 levels in the sera of patients with metastatic PCa were uniformly higher as compared to the non-cancer patient controls. The data suggest that galectin-3 serum level may be a useful serum complementary marker to the PSA blood test to be used for initial and follow-up PSA complimentary diagnostic/prognostic tool for recurrence in PCa patients.

A unique galectin signature in human prostate cancer progression suggests galectin-1 as a key target for treatment of advanced disease

Galectins, a family of glycan-binding proteins, influence tumor progression by modulating interactions between tumor, endothelial, stromal, and immune cells. Despite considerable progress in identifying the roles of individual galectins in tumor biology, an integrated portrait of the galectin network in different tumor microenvironments is still missing. We undertook this study to analyze the "galectin signature" of the human prostate cancer microenvironment with the overarching goal of selecting novel-molecular targets for prognostic and therapeutic purposes. In examining androgen-responsive and castration-resistant prostate cancer cells and primary tumors representing different stages of the disease, we found that galectin-1 (Gal-1) was the most abundantly expressed galectin in prostate cancer tissue and was markedly upregulated during disease progression. In contrast, all other galectins were expressed at lower levels: Gal-3, -4, -9, and -12 were downregulated during disease evolution, whereas expression of Gal-8 was unchanged. Given the prominent regulation of Gal-1 during prostate cancer progression and its predominant localization at the tumor-vascular interface, we analyzed the potential role of this endogenous lectin in prostate cancer angiogenesis. In human prostate cancer tissue arrays, Gal-1 expression correlated with the presence of blood vessels, particularly in advanced stages of the disease. Silencing Gal-1 in prostate cancer cells reduced tumor vascularization without altering expression of other angiogenesis-related genes. Collectively, our findings identify a dynamically regulated "galectin-specific signature" that accompanies disease evolution in prostate cancer, and they highlight a major role for Gal-1 as a tractable target for antiangiogenic therapy in advanced stages of the disease.

Galectin-3 expression in prostate cancer and benign prostate tissues: correlation with biochemical recurrence

BACKGROUND

Galactin-3 is a cell adhesion molecule involved in tumor progression. Our aim was to examine Gal-3 expression in tumor, benign tissue adjacent to the tumor (adjacent-benign) and benign prostate specimens and correlated it with biochemical recurrence.

MATERIALS AND METHODS

Tissue microarrays were prepared from 83 tumor, 78 adjacent-benign and 75 benign tissues obtained from 83 patients undergoing prostatectomy for clinically localized prostate cancer. Tissues were stained using a Gal-3 antibody and immunohistochemistry. The staining was graded between 0 and 300 depending upon staining intensity and the area of staining. In 37 patients on whom there was follow-up (Mean: 57.8 months; Median: 68 months), staining intensity was correlated with biochemical recurrence.

RESULTS

Gal-3 showed both nuclear and cytoplasmic localization in benign, adjacent-benign and tumor tissues. Median Gal-3 staining scores significantly decreased from benign (192.5) to adjacent-benign (148.8 p = 0.007) and to tumor (108.8; p < 0.0001) tissues. In univariate analysis, age (p = 0.028), Gleason sum (p = 0.007), T stage (p = 0.011), seminal vesicle invasion (p = 0.009), pre-operative prostate-specific antigen (p = 0.045) and Gal-3 staining in tumor tissues (0.018) significantly correlated with biochemical recurrence. In multivariate analysis, Gal-3 expression in tumor (p = 0.04), adjacent-benign (p = 0.037) and benign (p = 0.005) tissues significantly correlated with biochemical recurrence. Gal-3 staining in tumor tissues had 91.7 % sensitivity, 64 % specificity and 73 % accuracy in predicting biochemical recurrence.

CONCLUSIONS

This is the first study that showed a decreasing gradient of Gal-3 expression in benign, adjacent-benign and tumor tissues. Gal-3 expression may be useful in predicting biochemical recurrence.

Nuclear export of proteins and drug resistance in cancer

The intracellular location of a protein is crucial to its normal functioning in a cell. Cancer cells utilize the normal processes of nuclear-cytoplasmic transport through the nuclear pore complex of a cell to effectively evade anti-neoplastic mechanisms. CRM1-mediated export is increased in various cancers. Proteins that are exported in cancer include tumor-suppressive proteins such as retinoblastoma, APC, p53, BRAC1, FOXO proteins, INI1/hSNF5, galectin-3, Bok, nucleophosmin, RASSF2, Merlin, p21(CIP), p27(KIP1), N-WASP/FAK, estradiol receptor and Tob, drug targets topoisomerase I and IIα and BCR-ABL, and the molecular chaperone protein Hsp90. Here, we review in detail the current processes and known structures involved in the export of a protein through the nuclear pore complex. We also discuss the export receptor molecule CRM1 and its binding to the leucine-rich nuclear export signal of the cargo protein and the formation of a nuclear export trimer with RanGTP. The therapeutic potential of various CRM1 inhibitors will be addressed, including leptomycin B, ratjadone, KOS-2464, and specific small molecule inhibitors of CRM1, N-azolylacrylate analogs, FOXO export inhibitors, valtrate, acetoxychavicol acetate, CBS9106, and SINE inhibitors. We will also discuss examples of how drug resistance may be reversed by targeting the exported proteins topoisomerase IIα, BCR-ABL, and galectin-3. As effective and less toxic CRM1 export inhibitors become available, they may be used as both single agents and in combination with current chemotherapeutic drugs. We believe that the future development of low-toxicity, small-molecule CRM1 inhibitors may provide a new approach to treating cancer.