Galectin-3 as an immunohistochemical tool to distinguish pilocytic astrocytomas from diffuse astrocytomas, and glioblastomas from anaplastic oligodendrogliomas

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).

Galectins as Emerging Glyco-Checkpoints and Therapeutic Targets in Glioblastoma

Despite recent advances in diagnosis and treatment, glioblastoma (GBM) represents the most common and aggressive brain tumor in the adult population, urging identification of new rational therapeutic targets. Galectins, a family of glycan-binding proteins, are highly expressed in the tumor microenvironment (TME) and delineate prognosis and clinical outcome in patients with GBM. These endogenous lectins play key roles in different hallmarks of cancer by modulating tumor cell proliferation, oncogenic signaling, migration, vascularization and immunity. Additionally, they have emerged as mediators of resistance to different anticancer treatments, including chemotherapy, radiotherapy, immunotherapy, and antiangiogenic therapy. Particularly in GBM, galectins control tumor cell transformation and proliferation, reprogram tumor cell migration and invasion, promote vascularization, modulate cell death pathways, and shape the tumor-immune landscape by targeting myeloid, natural killer (NK), and CD8⁺ T cell compartments. Here, we discuss the role of galectins, particularly galectin-1, -3, -8, and -9, as emerging glyco-checkpoints that control different mechanisms associated with GBM progression, and discuss possible therapeutic opportunities based on inhibition of galectin-driven circuits, either alone or in combination with other treatment modalities.

Novel Galectin-3 Roles in Neurogenesis, Inflammation and Neurological Diseases

Galectin-3 (Gal-3) is an evolutionarily conserved and multifunctional protein that drives inflammation in disease. Gal-3's role in the central nervous system has been less studied than in the immune system. However, recent studies show it exacerbates Alzheimer's disease and is upregulated in a large variety of brain injuries, while loss of Gal-3 function can diminish symptoms of neurodegenerative diseases such as Alzheimer's. Several novel molecular pathways for Gal-3 were recently uncovered. It is a natural ligand for TREM2 (triggering receptor expressed on myeloid cells), TLR4 (Toll-like receptor 4), and IR (insulin receptor). Gal-3 regulates a number of pathways including stimulation of bone morphogenetic protein (BMP) signaling and modulating Wnt signalling in a context-dependent manner. Gal-3 typically acts in pathology but is now known to affect subventricular zone (SVZ) neurogenesis and gliogenesis in the healthy brain. Despite its myriad interactors, Gal-3 has surprisingly specific and important functions in regulating SVZ neurogenesis in disease. Gal-1, a similar lectin often co-expressed with Gal-3, also has profound effects on brain pathology and adult neurogenesis. Remarkably, Gal-3's carbohydrate recognition domain bears structural similarity to the SARS-CoV-2 virus spike protein necessary for cell entry. Gal-3 can be targeted pharmacologically and is a valid target for several diseases involving brain inflammation. The wealth of molecular pathways now known further suggest its modulation could be therapeutically useful.

LGALS3 Is a Poor Prognostic Factor in Diffusely Infiltrating Gliomas and Is Closely Correlated With CD163+ Tumor-Associated Macrophages

Background: Glioma, the most common brain tumor, is a heterogeneous group of glia-derived tumors, the majority of which have characteristics of diffuse infiltration and immunosuppression. The LGALS protein family is a large class of sugar-binding proteins. Among them, LGALS3 has been reported to promote tumor development and progression in some cancers. However, the clinical significance and biological functions of LGALS3 in glioma remain virtually unknown. The purpose of our research is to detect LGALS3 expression and its prognostic value in glioma and reveal the relationship between its expression and the clinico/molecular-pathological features of patients and immune cell infiltration.

Methods: LGALS3 protein expression was examined by immunohistochemistry. The mRNA expression data of LGALS3 was downloaded and analyzed from TCGA and Rembrandt datasets. The association between LGALS3 and glioma clinically relevant diagnostic/molecular markers (IDH, 1p19q, ATRX, MGMT, and TERT) was examined using the Chi-Squared (χ²) test. The correlation between LGALS3 expression and the infiltration of multiple intra-tumoral immune cell types, including B cells (CD20), T cells (CD4 and CD8), macrophages (CD68), and M2 tumor-associated macrophages (CD163), was evaluated by Spearman correlation analysis. Kaplan-Meier analysis and the Cox regression analysis were applied to evaluate the prognostic value of LGALS3 in glioma. The log-rank test was used to evaluate Kaplan-Meier results for significance.

Results: Out of all 304 glioma cases, LGALS3 protein was expressed in 125 glioma cases (41.1%, 125/304), with 69.2% (9/13) in WHO I, 9.8% (8/82) in WHO II, 34.2% (26/76) in WHO III, and 61.7% (82/133) in WHO IV. The expression of LGALS3 was correlated with patient age, WHO grade, PHH3 (mitosis), Ki67 index, IDH, 1p/19q codeletion, and TERT promoter status. LGALS3 was an independent poor prognostic marker in diffusely infiltrating gliomas and was positively correlated with immune cell infiltration, particularly CD163+ tumor-associated macrophages in the TCGA dataset, Rembrandt dataset, and our SYSUCC cohort (R = 0.419, 0.627, and 0.724).

Conclusion: LGALS3 was highly expressed in pilocytic astrocytoma, GBM, and IDH wild-type LGG. It served as a poor prognostic marker in diffusely infiltrating gliomas. Based on its prognostic significance and strong correlation with CD163+ TAMs, it may act as an important therapeutic target for human glioma.

Clinical relevance of molecular subgrouping of gliomatosis cerebri per 2016 WHO classification: a clinicopathological study of 89 cases

The extremely invasive phenotypes and genotypes related to progression of gliomatosis cerebri (GC) remain unclear although GC has been removed as an independent entity from the 2016 WHO classification. Hence, categorization of GC under the current WHO molecular classification is essential, and the molecular subgroups that might contribute to GC progression should be compared with the histopathological differences between initial and new lesions identified during follow-up. Analyses of IDH1/2 and TERTp mutations and 1p/19q co-deletion, and immunohistochemistry of IDH1-R132H, ATRX, p53 and galectin-3 were performed. Anaplastic astrocytoma, IDH-wildtype (AA-IDHwt) was the common molecular subgroup (52.8%), followed by diffuse astrocytoma, IDH-wildtype (DA-IDHwt) and AA, IDH-mutant (AA-IDHmt) (each 16.9%), DA-IDHmt (7.9%), glioblastoma (GBM)-IDHwt (3.3%) and GBM-IDHmt (2.2%). Approximately 92% of the AA-IDHwt lesions progressed to histologically confirmed GBM in the newly enhanced lesions harboring the TERTp mutation and expressing galectin-3. Similar to primary GBMs, GC-related GBMs that progressed from the IDHwt subgroups showed microvascular proliferation, palisading necrosis or thrombotic occlusion, implying that a subset of IDHwt subgroups may evolve to overt GBM. Molecular subgrouping did not provide the perfect prediction for the survival of GC patients. The AA-IDHwt group showed worse overall and progression-free survival (PFS) than the AA-IDHmt group. Biopsy plus radiotherapy, chemotherapy and temozolomide treatment for DA-IDHwt, and resection plus radiotherapy and temozolomide treatment for AA-IDHwt prolonged PFS. In conclusions, majority of GC was of the AA-IDHwt subgroup, which progressed to GBM. Molecular subgroups may assist in the selection of treatment modalities, because "GC pattern" still remains as a special growth of gliomas in WHO 2016 classification without established treatment guideline.

Galectin-3 and cancer stemness

Over the last few decades galectin-3, a carbohydrate binding protein, with affinity for N-acetyllactosamine residues, has been unique due to the regulatory roles it performs in processes associated with tumor progression and metastasis such as cell proliferation, homotypic/heterotypic aggregation, dynamic cellular transformation, migration and invasion, survival and apoptosis. Structure-function association of galectin-3 reveals that it consists of a short amino terminal motif, which regulates its nuclear-cytoplasmic shuttling; a collagen α-like domain, susceptible to cleavage by matrix metalloproteases and prostate specific antigen; accountable for its oligomerization and lattice formation, and a carbohydrate-recognition/binding domain containing the anti-death motif of the Bcl2 protein family. This structural complexity permits galectin-3 to associate with numerous molecules utilizing protein-protein and/or protein-carbohydrate interactions in the extra-cellular as well as intracellular milieu and regulate diverse signaling pathways, a number of which appear directed towards epithelial-mesenchymal transition and cancer stemness. Self-renewal, differentiation, long-term culturing and drug-resistance potential characterize cancer stem cells (CSCs), a small cell subpopulation within the tumor that is thought to be accountable for heterogeneity, recurrence and metastasis of tumors. Despite the fact that association of galectin-3 to the tumor stemness phenomenon is still in its infancy, there is sufficient direct evidence of its regulatory roles in CSC-associated phenotypes and signaling pathways. In this review, we have highlighted the available data on galectin-3 regulated functions pertinent to cancer stemness and explored the opportunities of its exploitation as a CSC marker and a therapeutic target.

LGALS3 Promotes Treatment Resistance in Glioblastoma and Is Associated with Tumor Risk and Prognosis

BACKGROUND

LGALS3 promotes tumor progression in diverse cancers. However, the involvement of LGALS3 in glioblastoma has not yet been broadly illuminated.

METHODS

Microarray was performed to detect the gene expression profiles of radioresistance in T98G cells and identified a universally upregulated gene, LGALS3. The impact of LGALS3 on the survival of glioblastoma cells facing ionizing irradiation or temozolomide was investigated by the Cell Counting Kit-8 (CCK-8). A total of 120 glioblastoma cases were collected to analyze the relationship between LGALS3 expression and patient prognosis. Another 961 patients with glioma and 1,351 healthy controls were recruited to study the association of SNPs across the LGALS3 gene with glioblastoma susceptibility. The functional SNP sites were also studied in cellular experiments.

RESULTS

An effective protection of LGALS3 from ionizing irradiation or temozolomide-induced cell death in T98G and U251 cells was found. In addition, high expression of LGALS3 could work as an independent risk factor for survival of patients with glioblastoma. Two SNP sites (rs4644 and rs4652) across the LGALS3 gene were associated with increased risk for glioblastoma, and the C allele of rs4652 and the A allele of rs4644 could enhance glioblastoma resistance to radio-chemotherapy, but not cell proliferation.

CONCLUSIONS

Our results suggest that LGALS3 is an important biomarker influencing glioblastoma risk and prognosis and a potential target for treating the malignancy, especially ones with resistance against the standard therapy.

IMPACT

LGALS3 promotes glioblastoma cells' resistance to ionizing irradiation and temozolomide and predicts poor prognosis. Targeting LGALS3 may limit the therapeutic resistance in glioblastoma and increase patient survival.

Glycosylation Changes in Brain Cancer

Protein glycosylation is a posttranslational modification that affects more than half of all known proteins. Glycans covalently bound to biomolecules modulate their functions by both direct interactions, such as the recognition of glycan structures by binding partners, and indirect mechanisms that contribute to the control of protein conformation, stability, and turnover. The focus of this Review is the discussion of aberrant glycosylation related to brain cancer. Altered sialylation and fucosylation of N- and O-glycans play a role in the development and progression of brain cancer. Additionally, aberrant O-glycan expression has been implicated in brain cancer. This Review also addresses the clinical potential and applications of aberrant glycosylation for the detection and treatment of brain cancer. The viable roles glycans may play in the development of brain cancer therapeutics are addressed as well as cancer-glycoproteomics and personalized medicine. Glycoprotein alterations are considered as a hallmark of cancer while high expression in body fluids represents an opportunity for cancer assessment.

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

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

Serum Galectin-3 level, not Galectin-1, is associated with the clinical feature and outcome in patients with acute ischemic stroke

Aim

To study the diagnostic and prognostic role of serum galectin-1 (Gal-1) and -3 (Gal-3) in acute ischemic stroke (AIS) patients.

Methods

We enrolled 233 patients with first-ever acute ischemic stroke and 252 healthy controls in this study. The AIS severity was evaluated by National Institutes of Health Stroke Scale (NIHSS) scores. The serum Gal-1 and -3 levels were determined. All patients were followed for 1 years and the functional outcome were evaluated by modified Rankin Scale (mRS) scores.

Results

We found that AIS patients had higher serum Gal-1 and -3 levels than controls. The serum Gal-3 level was closely associated with the AIS severity indicated by NHSS and infarction volume. Serum Gal-3 levels were significantly higher in patients with a poor outcome indicated by mRS scores than those in patients with a good outcome. In contrast, the serum Gal-1 is not associated with the severity and outcome of acute AIS patients. Our in vitro studies show that Gal-3 knockdown with siRNA dramatically increased the culture neuron cell viability and reduced apoptosis under oxygen glucose deprivation treatment. Meanwhile, the pro-inflammatory cytokine expression decreased with the inhibition of Gal-3.

Conclusion

Our finding provides a novel biological marker, serum Gal-3, for monitor of acute AIS patients.

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

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

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.

Galectin-3 up-regulation in hypoxic and nutrient deprived microenvironments promotes cell survival

Galectin-3 (gal-3) is a β-galactoside binding protein related to many tumoral aspects, e.g. angiogenesis, cell growth and motility and resistance to cell death. Evidence has shown its upregulation upon hypoxia, a common feature in solid tumors such as glioblastoma multiformes (GBM). This tumor presents a unique feature described as pseudopalisading cells, which accumulate large amounts of gal-3. Tumor cells far from hypoxic/nutrient deprived areas express little, if any gal-3. Here, we have shown that the hybrid glioma cell line, NG97ht, recapitulates GBM growth forming gal-3 positive pseudopalisades even when cells are grafted subcutaneously in nude mice. In vitro experiments were performed exposing these cells to conditions mimicking tumor areas that display oxygen and nutrient deprivation. Results indicated that gal-3 transcription under hypoxic conditions requires previous protein synthesis and is triggered in a HIF-1α and NF-κB dependent manner. In addition, a significant proportion of cells die only when exposed simultaneously to hypoxia and nutrient deprivation and demonstrate ROS induction. Inhibition of gal-3 expression using siRNA led to protein knockdown followed by a 1.7–2.2 fold increase in cell death. Similar results were also found in a human GBM cell line, T98G. In vivo, U87MG gal-3 knockdown cells inoculated subcutaneously in nude mice demonstrated decreased tumor growth and increased time for tumor engraftment. These results indicate that gal-3 protected cells from cell death under hypoxia and nutrient deprivation in vitro and that gal-3 is a key factor in tumor growth and engraftment in hypoxic and nutrient-deprived microenvironments. Overexpression of gal-3, thus, is part of an adaptive program leading to tumor cell survival under these stressing conditions.

Systematic review of protein biomarkers of invasive behavior in glioblastoma

Glioblastoma (GBM) is an aggressive and incurable brain tumor with a grave prognosis. Recurrence is inevitable even with maximal surgical resection, in large part because GBM is a highly invasive tumor. Invasiveness also contributes to the failure of multiple cornerstones of GBM therapy, including radiotherapy, temozolomide chemotherapy, and vascular endothelial growth factor blockade. In recent years there has been significant progress in the identification of protein biomarkers of invasive phenotype in GBM. In this article, we comprehensively review the literature and survey a broad spectrum of biomarkers, including proteolytic enzymes, extracellular matrix proteins, cell adhesion molecules, neurodevelopmental factors, cell signaling and transcription factors, angiogenic effectors, metabolic proteins, membrane channels, and cytokines and chemokines. In light of the marked variation seen in outcomes in GBM patients, the systematic use of these biomarkers could be used to form a framework for better prediction, prognostication, and treatment selection, as well as the identification of molecular targets for further laboratory investigation and development of nascent, directed therapies.

Glioblastoma with oligodendroglial component represents a subgroup of glioblastoma with high prevalence of IDH1 mutation and association with younger age

Glioblastoma with an oligodendroglial component (GBMO) is recognized as a subgroup of glioblastoma (GBM); however, the molecular and clinicopathological characteristics of GBMO are obscure. We evaluated the methylation status of MGMT, IDH1/2 mutation, deletions of 1p and 19q and expression of IDH1, p53, p16, CD151, and galectin3 proteins in 42 GBMOs (32 primary and 10 secondary tumors). Our aims were to correlate our molecular findings with clinicopathologic features, and to compare molecular-to-clinical correlations in the 42 GBMOs with the corresponding correlations in 45 GBMs. GBMO was subdivided into two subgroups according to the predominant cell component comprising >50 % of tumors: the astrocytic predominant type (GBMO-A) and oligodendroglioma predominant type (GBMO-O). Methylation of MGMT, IDH1/2 mutation, and co-deletion of 1p and 19q were found in 31.0, 26.2, and 17.9 % of patients with GBMO, respectively. Clinicopathological and molecular characteristics did not differ significantly between GBMO-A and GBMO-O. However, patients with GBMO-O experienced better outcomes than patients with GBMO-A (p = 0.007). On multivariate analysis the predominant cell type was an independent prognostic factor in overall survival [hazard ratio 4.2 (95 % confidence interval 1.4-12.8), p = 0.011]. When compared to patients with classic GBM, those with GBMO were younger (49.21 vs. 57.47, p = 0.003) and more frequently had tumors with IDH1 mutation (23.8 vs. 4.4 %, p = 0.009). Survival was similar in patients with GBMO and with classic GBM. Based on these results, GBMO may represent a subgroup of GBM that is associated with IDH1 mutation and younger age, although similar to classic GBM in prognosis.

A biphasic tumor consisting of pilocytic astrocytoma with an anaplastic solitary fibrous tumor component in the pineal region: a case report and literature review

Here we report a case of a biphasic tumor consisting of pilocytic astrocytoma with anaplastic solitary fibrous tumor component in the pineal region. The majority of the tumor showed typical histologic features of pilocytic astrocytoma. A minor part of the tumor showed marked proliferation of short spindle cells around vessels. These spindle cells showed CD34 and CD99 immunoreactivity. From a review of the literature, we found that only one similar case has been reported. Contrary to the reported case, our case showed anaplastic features of solitary fibrous tumor histology.

The promigratory activity of the matricellular protein galectin-3 depends on the activation of PI-3 kinase

Expression of galectin-3 is associated with sarcoma progression, invasion and metastasis. Here we determined the role of extracellular galectin-3 on migration of sarcoma cells on laminin-111. Cell lines from methylcholanthrene-induced sarcomas from both wild type and galectin-3^−/− mice were established. Despite the presence of similar levels of laminin-binding integrins on the cell surface, galectin-3^−/− sarcoma cells were more adherent and less migratory than galectin-3^+/+ sarcoma cells on laminin-111. When galectin-3 was transiently expressed in galectin-3^−/− sarcoma cells, it inhibited cell adhesion and stimulated the migratory response to laminin in a carbohydrate-dependent manner. Extracellular galectin-3 led to the recruitment of SHP-2 phosphatase to focal adhesion plaques, followed by a decrease in the amount of phosphorylated FAK and phospho-paxillin in the lamellipodia of migrating cells. The promigratory activity of extracellular galectin-3 was inhibitable by wortmannin, implicating the activation of a PI-3 kinase dependent pathway in the galectin-3 triggered disruption of adhesion plaques, leading to sarcoma cell migration on laminin-111.

Galectin-1 and immunotherapy for brain cancer

The prognosis of patients diagnosed with high-grade glioma continues to be dismal in spite of multimodal treatment. Active specific immunotherapy by means of dendritic cell vaccination is considered to be a new promising concept that aims at generating an anti-tumoral immune response. However, it is now widely accepted that the success of immunotherapeutic strategies to promote tumor regression will rely not only on enhancing the effector arm of the immune response but also on downregulation of the counteracting tolerogenic signals. In this article, we summarize evidence that galectin-1, an evolutionarily conserved glycan-binding protein that is abundantly expressed in high-grade glioma, is an important player in glioma-mediated immune escape.

Increased β-catenin/Tcf signaling in pilocytic astrocytomas: a comparative study to distinguish pilocytic astrocytomas from low-grade diffuse astrocytomas

Although pilocytic and diffuse grade II astrocytomas considered as low-grade tumors, the distinction between them is still a major clinical problem. Previously we reported the activation of Wnt/β-catenin/Tcf signaling pathway in diffuse astrocytomas, however its role in pilocytic astrocytomas is not well understood. In this study, we investigated the Wnt/β-catenin/Tcf pathway in pilocytic astrocytomas and compared with diffuse astrocytomas. We observed the differential expression of β-catenin, Tcf4, Lef1 and c-Myc in astrocytomas particularly higher levels were observed in pilocytic astrocytomas and GBM while very little expression was documented in grade II tumors. Further, immunohistochemical analysis revealed the strong positivity of β-catenin, Tcf4, Lef1 and c-Myc in pilocytic astrocytomas than that of grade II tumors and also exhibited the strong positivity in vascular endothelial cells of pilocytic astrocytomas and GBM. Hence, Wnt/β-catenin/Tcf signaling pathway is differentially expressed in astrocytomas, activation of this pathway might be helpful in separating pilocytic astrocytomas from low-grade diffuse astrocytomas.

Galectin-3 expression: a useful tool in the differential diagnosis of posterior fossa tumors in children

OBJECTIVE

Galectin-3 (Gal-3) is a glycan-binding protein highly expressed in several tumors, including brain neoplasms. This protein has been demonstrated to be correlated with adverse prognosis in some tumor types. However, the role of Gal-3 in pediatric posterior fossa tumors (PPFTs) has not yet been fully addressed. The goals of this study were to evaluate Gal-3 expression in a series of PPFTs and verify whether this expression is related to patient outcome.

MATERIAL AND METHODS

Gal-3 expression was analyzed by immunohistochemistry in 42 cases of surgically resected primary PPFTs. Surgeries were performed in our institution from January 2003 to December 2006. Tumor samples consisted of 21 pilocytic astrocytomas (PAs), 13 medulloblastomas, 4 ependymomas, 2 diffuse cerebellar astrocytomas, and 2 atypical teratoid/rhabdoid tumors (AT/RTs).

RESULTS

All PAs and ependymomas strongly showed Gal-3 expression, whereas no immunostaining was observed in medulloblastomas and diffuse astrocytomas. In AT/RTs, Gal-3 expression was conspicuous but heterogeneous, being mainly observed in rhabdoid cells. Concerning the Gal-3 expressing tumors, no relationship was observed between the degree of expression and patient survival. Gal-3 was strongly expressed in reactive astrocytes, normal endothelial cells, and macrophages in the adjacent non-neoplastic brain parenchyma. Interestingly, the endothelial cells in the tumor bulk of PAs lacked Gal-3 expression.

CONCLUSIONS

Gal-3 is differentially expressed in PPFTs, but its expression shows no correlation with patient outcome. However, the evaluation of Gal-3 is helpful in establishing a differential diagnosis among PPFTs, especially between PAs and diffuse astrocytomas, and in some circumstances between medulloblastomas and AT/RTs.

Brain sweet brain: importance of sugars for the cerebral microenvironment and tumor development

The extracellular matrix (ECM) in the brain tissue is a complex network of glycoproteins and proteoglycans that fills the intercellular space serving as scaffolding to provide structural framework for the tissue and regulate the behavior of cells via specific receptors - integrins. There is enormous structural diversity among proteoglycans due to variation in the core protein, the number of glycosaminoglycans chains, the extent and position of sulfation. The lectican family of proteoglycans interacts with growth factors, hyaluronan and tenascin forming a complex structure that regulates neuronal plasticity and ion homeostasis around highly active neurons. In this review, we will discuss the latest insights into the roles of brain glycoproteins as modulators of cell adhesion, migration, neurite outgrowth and glial tumor invasion.

High expression of cancer testis antigens MAGE-A, MAGE-C1/CT7, MAGE-C2/CT10, NY-ESO-1, and gage in advanced squamous cell carcinoma of the larynx

BACKGROUND

Despite diagnostic and therapeutic advances in head and neck cancer, the 5-year survival of patients with laryngeal cancer has not improved in the last 30 years. Several recent studies indicate that specific targets for immunotherapeutic approaches can be useful in the control of cancer. There is considerable interest in the expression of cancer testis antigens in human cancers since they may serve as the basis for an immunologic approach to therapy.

METHODS

We evaluated by immunohistochemical analysis the expression of cancer testis antigens MAGE-A4 (57B), MAGE-C1 (CT7-33), MAGE-A1 (MA454), MAGE-A3 (M3H67), MAGE-C2 (CT10.5), NY-ESO-1 (E978), and GAGE (GAGE) in squamous cell carcinoma (SCC) of the larynx.

RESULTS

A total of 63 cases (57 men and 6 women) of laryngeal SCC were available for this study. The findings were correlated with the clinical course and laboratory data. Expression of at least 1 cancer testis antigen was detected in 42 of 63 of the laryngeal SCCs (67%). In 34 of 42 of the positive cases (81%) there was simultaneous expression of ≥2 cancer testis antigens. There was significant correlation between antigen expression and advanced tumor stage (stage III/IV) in cases with reactivity to only 1 antibody (p = .01) as well as in the cases with reactivity to ≥2 primary antibodies (≥2 mAbs, p = .04). There was no association between survival and expression of any of the analyzed antigens.

CONCLUSIONS

We find a high incidence of cancer testis antigen expression in SCCs of the larynx, which was correlated with advanced clinical stage. Our data indicate that cancer testis antigens could be valuable vaccine targets in laryngeal tumors, especially in those with a worse prognosis.

Immune therapeutic targeting of glioma cancer stem cells

Glioblastoma multiforme (GBM) is a lethal cancer that responds poorly to radiotherapy and chemotherapy. Glioma cancer stem cells (gCSCs) have been shown to recapitulate the characteristic features of GBM and to mediate chemotherapy and radiation resistance. Immunotherapeutic targeting of this cell population holds therapeutic promise but must be considered in the context of the immunosuppressive properties mediated by the gCSC. Recent findings have indicated that this goal will be challenging because the gCSC can suppress both the innate and adaptive immune systems by a variety of gCSC-secreted products and cell-membrane interactions. In this review article, we will attempt to reconcile the disparate research findings regarding the potential of immune targeting of the gCSC and propose several novel solutions.

In pursuit of prognostic factors in children with pilocytic astrocytomas

OBJECTIVE

This study described a 23-year experience in the treatment of children with pilocytic astrocytomas (piloA) with the aim of identifying putative clinical, histopathological, and/or immunohistochemical features that could be related to the outcome of these patients.

METHODS

Clinical data of 31 patients under 18 years of age with piloA were obtained from 1984 to 2006.

RESULTS

The mean age at the time of surgery was 7.8 +/- 4.2 years (1 to 17 years), and the mean follow-up was 5.7 +/- 5.4 years (1 to 20 years). The most common site of tumor formation was the cerebellum (17), followed by brainstem (4), optic chiasmatic hypothalamic region (4), cerebral hemisphere (3), cervical spinal cord (2), and optic nerve (1). Gross total resection (GTR) was achieved in 23 (74.1%), mainly in those with tumors located in the cerebellum and cerebral hemispheres (P = 0.02). The global mortality rate was 6.4%. Nine patients were reoperated. Rosenthal fibers, eosinophilic granular bodies, microvascular proliferation, and lymphocytic infiltration were observed in most cases. The mean Ki-67LI was 4.4 +/- 4.5%. In all cases, Gal-3 expression in tumor cells was observed with variable staining pattern.

CONCLUSIONS

Aside from GTR, no other clinical, histopathological, or immunohistochemical features were found to be related to the prognosis. We postulate that strict follow-up is recommended if piloA is associated with high mitotic activity/Ki67-LI, or if GTR cannot be achieved at surgery. Tumor recurrence or progression of the residual lesion should be strictly observed. In some aspects, childhood piloA remains an enigmatic tumor.

Galectins and gliomas

Malignant gliomas, especially glioblastomas, are associated with a dismal prognosis. Despite advances in diagnosis and treatment, glioblastoma patients still have a median survival expectancy of only 14 months. This poor prognosis can be at least partly explained by the fact that glioma cells diffusely infiltrate the brain parenchyma and exhibit decreased levels of apoptosis, and thus resistance to cytotoxic drugs. Galectins are a family of mammalian beta-galactoside-binding proteins characterized by a shared characteristic amino acid sequence. They are expressed differentially in normal vs. neoplastic tissues and are known to play important roles in several biological processes such as cell proliferation, death and migration. This review focuses on the role played by galectins, especially galectin-1 and galectin-3, in glioma biology. The involvement of these galectins in different steps of glioma malignant progression such as migration, angiogenesis or chemoresistance makes them potentially good targets for the development of new drugs to combat these malignant tumors.

Galectin-3 expression is ubiquitous in tumors of the sellar region, nervous system, and mimics: an immunohistochemical and RT-PCR study

Galectin-3 expression has been reported in spindle cell oncocytoma, certain pituitary adenoma subtypes, astrocytomas, oligodendrogliomas, and meningiomas. We evaluated galectin-3 protein expression by immunohistochemistry in 201 cases of a variety of nervous system and sellar tumors, as well as mRNA expression by reverse transcription-polymerase chain reaction in formalin-fixed paraffin-embedded tissue in a subset (20 cases). Immunohistochemical results were evaluated in a semiquantitative fashion on a 4-tiered scale (0 to 3). Strong (3+) immunoreactivity was seen in most of the cases (61%), followed by 2+(22%), and 1+(13%) staining. Only 4% of the lesions studied were immunonegative. Galectin-3 mRNA was present in 15 of the 18 cases (83%) in which reverse transcription-polymerase chain reaction was successful. Significant differences in protein expression were noted in the following 2 settings: specific meningioma subtypes (P=0.004, Fisher exact test) wherein clear cell meningioma demonstrated weak protein expression when compared with other meningioma variants. No significant difference was noted with respect to World Health Organization grade. Galectin-3 was also strongly expressed in benign nerve sheath tumors but only moderately expressed in malignant peripheral nerve sheath tumors (P=0.0009, Fisher exact test). Although galectin-3 positivity is a key feature of the immunophenotype of spindle cell oncocytoma, its consistent expression in other morphologically similar tumors (meningioma, pituicytoma, nerve sheath tumors, granular cell tumor, metastases) makes it of little use in the differential diagnosis of sellar region tumors, a setting in which it should be discouraged. Diagnostic uses of this marker may be limited to specific settings, including some meningioma subtypes and nerve sheath tumors.

Galectin-3: a useful biomarker for differential diagnosis of brain tumors

Galectin-3 (gal-3) is a 31 kDa beta-galactoside-binding lectin that is immunohistochemically expressed in macrophages, lymphocytes, and endothelial cells, and also in some neoplastic cells. Gal-3's expression in and significance to brain tumors has not been fully addressed. Here, we investigated its immunohistochemical expression in 409 cases of surgically resected primary brain tumors, including various glioneuronal tumors, pituitary adenomas, meningiomas and Schwannomas, among others. In normal brain tissues, gal-3 was robustly expressed in normal astrocytes, endothelial cells and macrophages. It showed consistent and diffuse positivity in 100% of the pilocytic astrocytomas, pleomorphic xanthoastrocytomas (PXA), Schwannomas, meningiomas, capillary hemangioblastomas, as well as in ependymomas, but it was completely negative in the diffuse astrocytomas, anaplastic astrocytomas, both low- and high-grades of the oligodendrogliomas, central neurocytomas, and medulloblastomas. Definitely positive but heterogeneous expression was found in various tumors including subependymal giant cell astrocytomas (SEGA), classic glioblastoma multiforme, anaplastic oligoastrocytomas, CNS primitive neuroectodermal tumors (CNS PNETs), and hemangiopericytomas. Eighty percent of small cell glioblstomas were completely negative, but 20% showed heterogeneous positivity for gal-3. Focal positivity for gal-3 was also found in dysembryoplastic neuroepithelial tumors (DNTs) and gangliogliomas, in which the positive cells were the astrocytic component. On the basis of our immunohistochemical data in conjunction with previous reports, we therefore conclude that gal-3 is differentially expressed in various brain tumors, and thereby, is a helpful biomarker in making differential diagnoses, especially in cases where a morphological diagnosis is controversial.

New roles for galectins in brain tumors--from prognostic markers to therapeutic targets

Despite advances in diagnosis and treatment, brain tumors continue to be the leading cause of cancer-related death in patients under 35 years of age, demonstrating the need for better prognostic and therapeutic targets. Galectins, a family of mammalian carbohydrate binding proteins, are involved in many processes important for tumor survival and dissemination, including proliferation, apoptosis, transcriptional regulation, intracellular signaling, cell adhesion, and cell migration. Several galectins are expressed in human brain, with many galectins demonstrating altered expression during tumor progression. Thus, galectins and the functions regulated by this family of proteins are potential targets for the diagnosis and treatment of brain cancer. This review highlights the roles of galectins in cancer and specifically, the developing field of galectins in brain cancer.