High Gal-1 Expression Research Articles

Galectin-1-mediated high NCAPG expression correlates with poor prognosis in gastric cancer.

Galectin-1 (Gal1) and non-SMC condensin I complex, subunit G (NCAPG) are associated with metastasis in several malignant tumors. However, their precise roles in gastric cancer (GC) remain uncertain. This study explored the clinical significance and relationship of Gal1 and NCAPG in GC. Gal1 and NCAPG expressions were significantly up-regulated in GC compared to adjacent non-cancerous tissues by immunohistochemistry (IHC) and Western blotting. Besides, methods including stable transfection, quantitative real-time reverse transcription PCR, Western blotting, Matrigel invasion and wound-healing assays in vitro, were also conducted. IHC scores for Gal1 and NCAPG had a positive correlation in GC tissues. High Gal1 or NCAPG expression significantly correlated with poor prognosis in GC, and Gal1 combined with NCAPG had a synergetic effect on the prediction of GC prognosis. Gal1 overexpression in vitro enhanced NCAPG expression, cell migration, and invasion in SGC-7901 and HGC-27 cells. Simultaneous Gal1 overexpression and NCAPG knockdown in GC cells partly rescued the migrative and invasive abilities. Thus, Gal1 promoted GC invasion through increased NCAPG expression. The present study demonstrated the prognostic significance of the combination of Gal1 and NCAPG in GC for the first time.

High Intratumoral Galectin-1 Is Associated with Adverse Outcome in ALK-Negative, CD30-Positive Peripheral T-Cell Lymphomas

Galectin-1 (Gal-1) has been associated with prognosis in several cancers including lymphomas. CD30-dependent cell signaling mediated by Gal-1 has been proposed in CD30-positive lymphomas and cell lines. Still, Gal-1 expression has not been systematically assessed as a possible prognosticator in nodal peripheral T-cell lymphomas (PTCL).Tissue micro arrays with pre-therapeutic tumor specimens from 169 patients with nodal PTCL (n=29 AITL, n=37 ALK-negative ALCL, n=14 ALK-positive ALCL, and n=83 PTCL-NOS) were assessed for intratumoral Gal-1 expression by immunohistochemistry and quantified using digital image analysis. For outcome analysis Gal-1 expression in tumors was categorized in two groups i.e. i) the quartile of patients with highest expression values (Gal-1 high) and ii) the lower three quartiles taken as one group (Gal-1 low). Overall survival (OS) in high and low Gal-1 groups was compared in the entire cohort and in CD30-positive subsets of PTCL.Gal-1 stains were evaluable in 163 cases (96%). The Gal-1 expression level was significantly different between PTCL subtypes (P<0.001) with ALK-positive and ALK-negative ALCL having the highest levels. Moreover, CD30-positive PTCLs showed higher expression compared with CD30-negative ones (P=0.001). No significant difference in OS according to Gal-1 expression was seen in the PTCL cohort as a whole or in the CD30-positive subgroup when including ALK-positive ALCL. Due to the superior survival and very few events among ALK-positive ALCL patients (P<0.001), a CD30-positive cohort without ALK-positive ALCL was analyzed separately. This cohort consisted of ALK-negative ALCL (n=37), PTCL-NOS (n=5), and AITL (n=1). Within this cohort, patients with ‘Gal-1 high’ had significantly poorer outcome (5 yrs OS 10%, 95% confidence interval (CI): 0.1-36) than their ‘Gal-1 low’ counterparts (5 yrs OS 48%, 95%CI: 30-64, P=0.025). Risk factors were evenly distributed between the groups. In univariate analyses age≤60, normal LDH, and performance score <2 correlated with superior survival, whereas high Gal-1 expression significantly predicted adverse outcome at both univariate (HR 2.4, 95%CI: 1,1-5.5, P=0.030) and multivariate level (HR 2.9, 95%CI: 1.1-7.8, P=0.027). We conclude that high intratumoral Gal-1 expression correlates with inferior survival in nodal ALK-negative, CD30-positive PTCL patients. Disclosuresd'Amore:Nordic Nanovector: Other: Advisory Board; Sanofi: Research Funding; Les Laboratoires Servier: Honoraria, Other: Advisory Board; Takeda Pharma: Honoraria, Other: Advisory Board, Research Funding.

High intratumoural galectin-1 expression predicts adverse outcome in ALK- ALCL and CD30+ PTCL-NOS.

Galectin-1 (Gal-1) has been associated with adverse prognosis in several cancers including lymphoma entities with CD30 expression. However, Gal-1 expression has not been systematically assessed in peripheral T-cell lymphomas (PTCL). Specimens from 169 nodal PTCL were assessed for intratumoural Gal-1 expression by immunohistochemistry. Overall survival (OS) in groups exhibiting high and low Gal-1 expression was compared in the cohort and in a subset analysis of CD30-positive PTCL only. Gal-1 expression was also correlated with biomarkers of the tumour microenvironment. No significant difference in OS based on Gal-1 expression was observed in the entire PTCL cohort. However, in the CD30-positive cohort, patients with high Gal-1 levels had significantly poorer outcome (5 years OS 10%, 95% confidence interval CI, 1-36) than their low Gal-1 counterparts (5 years OS 48%, 95% CI, 30-64, P = .021). In univariate analyses age 60 or younger, non-elevated lactate dehydrogenase (LDH), and performance score less than 2 correlated with superior survival but high Gal-1 expression significantly predicted adverse outcome at both univariate (HR 2.5, 95% CI, 1.1-5.7, P = .026) and multivariate levels (HR 3.2, 95% CI, 1.2-8.5, P = .017). Tumours with high Gal-1 had few cytotoxic T cells in the tumour microenvironment. High intratumoural Gal-1 expression before therapeutic intervention correlates with adverse outcome in nodal CD30+ , ALK- PTCL patients.

CHIP-mediated ubiquitination of Galectin-1 predicts colorectal cancer prognosis.

CHIP and Galectin-1 are associated with the development of metastasis in cancer. However, the precise roles of CHIP or Gal1 in colorectal cancer are uncertain. Here, our study explored the relationship and clinical significance of CHIP or Gal1 in CRC. CHIP or Gal1 expression was significantly decreased or up-regulated in CRC compared with adjacent noncancerous tissues by immunohistochemistry on a CRC tissue microarray, respectively. Low CHIP or high Gal1 expression significantly correlated with clinicopathological characteristics in patients, as well as with shorter overall survival. Multivariate Cox regression analysis revealed that CHIP or Gal1 expression was an independent prognostic factor for CRC patients. Moreover, CHIP associated with Gal1 has a synergistic effect on the prediction of CRC prognosis. In vitro and vivo, high CHIP or low Gal1 expression inhibit CRC growth or metastasis. Our results found that CHIP could degradate Gal1 by ubiquitination. In summary, CHIP could inhibit CRC growth or metastasis through promoting Gal1 ubiquitination and degradation by proteasome. CHIP and Gal1 expressions are novel candidate prognostic markers in CRC. A combined effect of CHIP and Gal1 as efficient prognostic indicators was found for the first time.

P11.38 The Galectin-1 inhibitor OTX-008 has antiproliferative effects on human glioblastoma cells independent of MGMT-promotor status

Abstract BACKGROUND The protein Galectin-1 (gal-1) is known to be involved in proliferation and progression of several malignancies. The allosteric gal-1 inhibitor OTX-008 has an antiproliferative effect on various tumors in vitro and in vivo. However, the effect of OTX-008 on patient derived GBM cultures is unknown. The aim of our study was to investigate the antiproliferative effects of OTX-008 on U87-MG and A172 cells, patient derived GBM cultures, and cultured human astrocytes (HCA). MATERIAL AND METHODS GBM specimens from 10 patients were intraoperatively retrieved out of the 5-ALA-positive areas and were cultured in DMEM. In these cell cultures, U87-MG and A172 cell lines, and in HCA the gal-1 expression was determined by quantitative RT-PCR. Gal-1 expression below the median was defined as low-gal-1 expression (LGE), above as high-gal-1 expression (HGE). OTX-008 was administered and cell viability was assessed after 72h with MTT assay. Dose-response curves and influence of gal-1 expression were calculated by probit analysis in a logit model with logarithmic transformation of x-axis. Comparison between MGMT promotor methylated and unmethylated cells was performed using the Mann-Whitney U test. RESULTS OTX-008 inhibited cell proliferation of all 10 patient derived GBM cell cultures with a mean ED50 of 34.28 (95% CI: 20.29- 61.57) μM and a mean ED95 of 100.90 (59.30- 199.33) μM. Antiproliferative effects of OTX-008 for U87-MG and A172 cells were found with an ED50 of 17.44 (95% CI: 13.24- 22.52) μM and 33.36 (95% CI: 24.30- 45.86) μM. In 5 cell cultures of the patient derived cells LGE and in the other 5 HGE was determined. Probit analysis showed an ED50 of 20.43 (95% CI: 16.03- 24.89) μM for the LGE group and an ED50 of 33.98 (95% CI: 28.15- 40.89) μM for the HGE-group. Between MGMT-promotor methylated and unmethylated cells no statistically significant difference for the ED50 was observed (38.36 vs. 31.56; P=0.454). Probit analysis of OTX-008 administration in HCA showed no dose-response-relation. CONCLUSION OTX-008 has antiproliferative effects on human glioblastoma cells independent of MGMT-promotor methylation status. The sensitivity of GBM cells to OTX-008 depends on the gal-1 expression level. In HCA no effect on cell viability was observed. OTX-008 seems a promising novel substance in glioblastoma therapy.

Galectins-1, -3, and -7 Are Prognostic Markers for Survival of Ovarian Cancer Patients.

There is a tremendous need for developing new useful prognostic factors in ovarian cancer. Galectins are a family of carbohydrate binding proteins which have been suggested to serve as prognostic factors for various cancer types. In this study, the presence of Galectin-1, -3, and -7 was investigated in 156 ovarian cancer specimens by immunochemical staining. Staining was evaluated in the cytoplasm and nucleus of cancer cells as well as the peritumoral stroma using a semi quantitative score (Remmele (IR) score). Patients’ overall survival was compared between different groups of Galectin expression. Galectin (Gal)-1 and -3 staining was observed in the peritumoral stroma as well as the nucleus and cytoplasm of tumor cells, while Gal-7 was only present in the cytoplasm of tumor cells. Patients with Gal-1 expression in the cytoplasm or high Gal-1 expression in the peritumoral stroma showed reduced overall survival. Nuclear Gal-3 staining correlated with a better outcome. We observed a significantly reduced overall survival for cases with high Gal-7 expression and a better survival for Gal-7 negative cases, when compared to cases with low expression of Gal-7. We were able to show that both tumor and stroma staining of Gal-1 could serve as negative prognostic factors for ovarian cancer. We were able to confirm cytoplasmic Gal-7 as a negative prognostic factor. Gal-3 staining in the nucleus could be a new positive prognosticator for ovarian cancer.

High Intratumoral Expression of Galectin-1 Correlates with Superior Outcome in HIV-Associated DLBCL

Introduction. HIV infected individuals have an increased risk of developing lymphoma even in the era of combined antiretroviral therapy. Galectin-1 (Gal-1) is known to promote various immunomodulatory functions, including Treg expansion (Dalotto-Moreno et al, Cancer Res 2013), promotion of tolerogenic dendritic cells (Ilarregui et al, Nat Immunol 2009) and apoptosis of fully-differentiated effector T-cells (Toscano et al, Nat Immunol 2007). In the context of cancer, Gal-1 is expressed on both tumor cells and cells in the tumor microenvironment, and is usually associated with immune privilege, tumor escape and hypoxia-driven angiogenesis (Juszczynski et al, Proc Natl Acad Sci 2007; Cedeno-Laurent et al, Blood 2012). Previously, high intratumoral Gal-1 levels have been suggested as an unfavorable outcome predictor in patients with classical Hodgkin lymphoma (cHL) (Kamper et al, Blood 2011). Furthermore, several in vitro studies revealed the benefit of Gal-1 inhibition with regards to overcoming treatment resistance e.g., after anti-VEGF and anti-CD20 therapy (Croci et al, Cell 2014; Lykken et al, Blood 2016). Thus, Gal-1 inhibition may prospectively be an important tool in lymphoma treatment. In this study, we have investigated the Gal-1 expression in pre-therapeutic tumoral tissue samples from patients with HIV-associated lymphoma and its correlation to clinicopathological features at lymphoma diagnosis.Methods. Adequate pre-treatment formalin-fixed paraffin embedded samples from 40 HIV-positive lymphoma patients were included in a tissue micro array. The study samples were immunohistochemically characterized by a panel of monoclonal antibodies including CD3, CD4, CD8, CD10, CD20, CD79a (MRQ-48), CD30 (Ber-H2) and MUM1, granzyme B, CD68 and CD163. Epstein-Barr virus (EBV) proteins were visualized by latent membrane protein 1 and Epstein-Barr nuclear protein 2. Expression of EBV-encoded smallRNAs was analyzed by in-situ hybridization. Immunohistochemical cell-of-origin (COO) evaluation was carried out according to the Hans classifier. Gal-1 expression was digitally quantified as an area fraction (AF) of the total core area. Estimates of differences between groups were evaluated using Students t test, Pearsons χ2, Fisher’s exact test or Spearman correlation where appropriate. Optimal cut-off values of the AF were established by a ROC analysis and calculated using Youden’s index for diffuse large B-cell lymphoma (DLBCL) (n=22). Outcome was estimated by Kaplan-Meier time-to-event analyses and compared using the log-rank test. Independent prognostic values were tested by Cox-regression analysis in a multivariate model for factors showing a crude association with p<0.1and proportional hazards between groups.Results. High intratumoral Gal-1 expression in HIV-associated DLBCL tissue correlated with improved outcome (p=0.041), Figure 1. Patients with high Gal-1 expression had a higher occurrence of nodal disease and B-symptoms (p=0.006). Gal-1 expression did not vary according to tumoral EBV status, latency type, International prognostic index (IPI), clinical stage or COO signature. In multivariate analysis adjusted for rituximab treatment, both Gal-1 expression and IPI retained independent prognostic value. Furthermore, intratumoral Gal-1 expression correlated positively with a Th1-signature of the tumor microenvironment including the macrophage marker CD68 (p<0.001), markers of cytotoxic T-cells such as CD8 (p=0.027) and granzyme B (p<0.001), together with the activation marker CD30 (p=0.006). Markers of a Th2-associated microenvironmental signature had no correlation with Gal-1 expression, except for CD163 (p<0.01) that also significantly correlated with CD68 expression (p<0.01).Conclusion. In HIV-associated DLBCL, intratumoral Gal-1 expression positively correlated with a Th1-signature of the tumor microenvironment. In addition, high pre-therapeutic intratumoral Gal-1 expression was found to be an independent predictor of improved outcome in HIV-associated DLBCL. Interestingly, this is the reverse of our previous findings in non-overtly immunocompromised patients with cHL (Kamper et al, Blood 2011). Further investigations on the potential clinical application of intratumoral Gal-1 expression as a predictive marker in different lymphoma types of the immunocompromised vs immunocompetent host are warranted. [Display omitted] Disclosuresd'Amore:CTI LIfe Sciences: Honoraria, Other: Advisory Boards; Servier: Honoraria, Other: Advisory Boards.

Expression of galectin-1 in carcinoma-associated fibroblasts promotes gastric cancer cell invasion through upregulation of integrin β1.

Increased expression of galectin-1 (Gal-1) in carcinoma-associated fibroblasts (CAFs) has been reported to correlate with progression and prognosis in many cancers. However, rarely have reports sought to determine whether high Gal-1 expression in CAFs in gastric cancer is involved in the tumor process, and the specific mechanism by which it promotes the evolution of gastric cancer is still unknown. In this study, we cultured gastric cancer CAFs, which showed strong expression of Gal-1, and established a co-culture system of CAFs with gastric cancer cells. Specific siRNA and in vitro migration and invasion assays were used to explore the effects of the interaction between Gal-1 expression of CAFs and gastric cancer cells on cell migration and invasion. We found that the overexpression of Gal-1 in CAFs enhanced gastric cancer cell migration and invasion, and these stimulatory effects could be blocked by specific siRNA which reduced the Gal-1 expression level. A set of cancer invasion-associated genes were then chosen to identify the possible mechanism of Gal-1-induced cell invasion. Among these genes, integrin β1 expression in cancer cells was considered to be associated with Gal-1 expression. Pre-blocking of the integrin β1 expression in gastric cancer cells with siRNA could interrupt the invasion-promoting effect of CAFs with high Gal-1 expression. Furthermore, immunohistochemical assay confirmed a positive correlation between Gal-1 and integrin β1 expression. Our results showed that high expression of Gal-1 in CAFs might facilitate gastric cancer cell migration and invasion by upregulating integrin β1 expression in gastric cancer.

Galectin-1 induces vascular permeability through the neuropilin-1/vascular endothelial growth factor receptor-1 complex

Galectin-1 (Gal-1) is a β-galactoside-binding lectin that regulates endothelial cell migration, proliferation, and adhesion. However, the effect of Gal-1 on vascular permeability and the underlying mechanisms are unclear. We found that high Gal-1 expression was associated with elevated tumor vascular permeability in specimens of oral squamous cell carcinoma. Using transendothelial passage of FITC-dextran and a Miles assay, we demonstrated that Gal-1 increased vascular permeability extracellularly through its carbohydrate recognition domain. Mechanism dissection revealed that the neuropilin (NRP)-1/vascular endothelial growth factor receptor- (VEGFR)-1 complex was required for Gal-1-regulated vascular permeability. Activation of VEGFR-1 triggered activation of Akt which led to a reduction in vascular endothelial-cadherin at cell-cell junctions and resulted in cytoskeletal rearrangement. Both inhibition of Gal-1 secreted from cancer cells and administration of an anti-Gal-1 antibody in the tumor microenvironment suppressed tumor growth and vascular permeability in xenograft models. In conclusion, our results demonstrate a novel function of Gal-1 of increasing vascular permeability through the NRP-1/VEGFR1 and Akt signaling pathway and indicate that targeting Gal-1 by an anti-Gal-1 antibody is a feasible therapy for vascular hyperpermeability and cancer.

Clinical relevance of galectin-1 expression in non-small cell lung cancer patients

BackgroundIdentification of biomarkers in lung cancer, a leading cause of cancer-related mortality, has a meaningful clinical relevance in the quest of novel prognostic factors and therapeutic targets. The glycan-binding protein galectin-1 (Gal-1) modulates tumor progression by mediating cell–cell and cell–extracellular matrix interactions, as well as angiogenesis and tumor immune-escape. Previous works reported the expression of Gal-1 in lung cancer, although its clinical significance remains uncertain. ObjectiveTo assess the clinicopathologic relevance and prognostic value of Gal-1 expression in a cohort of 103 Stage I–III non-small cell lung cancer (NSCLC) patients. MethodsGal-1 expression was determined by immunohistochemistry in tumor tissue samples. The percentage of immunoreactive tumor cells and stroma, as well as the presence of blood vessels with positively stained endothelium in the tumor and surrounding normal tissue, were recorded. Results were correlated with the clinicopathologic factors of the patients (Spearman's rank correlation coefficient, chi-square test) and overall survival by univariate (Kaplan Meier) and multivariate analyses (Cox regression hazard model). ResultsWe did not observe significant associations between Gal-1 expression and relevant clinicopathologic features at diagnosis of NSCLC. However, Kaplan Meier analysis revealed a significant association between Gal-1 expression and overall survival, when Gal-1 expression was analyzed on tumor cells alone (“tumor cell percentage”) or when an integrated score accounting for tumor cell as well as stromal expression of Gal-1 (“total score”) was assessed. Patients showing high Gal-1 expression evidenced a poorer clinical outcome. Furthermore, “total score” remained significantly associated with survival by multivariate Cox regression analysis in the whole cohort of patients, even when controlling for the classical predictors and prognostic factors of NSCLC. ConclusionWe conclude that Gal-1 expression may be a useful biomarker for better prediction of the clinical outcome and management of NSCLC patients.

The clinical implication of tumoral Gal-1 expression in laryngeal squamous cell carcinomas

To explore the expression of tumoral Gal-1 in association with clinical parameters and outcome in a large population with laryngeal squamous cell carcinomas (LSCCs). A total of 187 patients with LSCC were retrospectively enrolled. Immunohistochemistry was performed to evaluate the tumoral expression of Gal-1, apoptosis-related proteins and the density of tumor infiltrating lymphocytes (TILs) in tumor tissues before any intervene. Survival curves were estimated by the Kaplan-Meier method, and differences in survival between groups were determined using the log-rank test. Prognostic effects were evaluated by Cox regression analysis. A total of 102 carcinomas (54.5%) were identified as high Gal-1 expression, and 85 carcinomas (45.5%) as low expression. Tumoral Gal-1 expression was not significantly related with clinical stage and histology differentiation. No correlation of Gal-1 expression with apoptosis-related protein was identified. Instead, Gal-1 status was correlated positively with the ratio of FOXP3(+)/CD8(+) TILs (P=0.024). In multivariate regression analysis, advanced clinical stage and the presence of metastases were identified as the independent predictors for poor survival in entire cohort. Especially, the statistical correlation between the Gal-1 expression and prognosis was particularly due to the late-stage tumors (P<0.05). Current results represent valuable advancements in Gal-1 research and provided further support for using Gal-1 as a diagnostic biomarker and immunotherapeutic target for LSCC.

Nuclear factor (NF)-κB controls expression of the immunoregulatory glycan-binding protein galectin-1

The inflammatory response is a self-limiting process which involves the sequential activation of signaling pathways leading to the production of both pro- and anti-inflammatory mediators. Galectin-1 (Gal-1), an endogenous lectin found in peripheral lymphoid organs and inflammatory sites, elicits a broad spectrum of biological functions predominantly by acting as a potent anti-inflammatory factor and as a suppressive agent for T-cell responses. However, the molecular pathways underlying Gal-1 expression and function remain poorly understood. Here we identified a regulatory loop linking Gal-1 expression and function to NF-κB activation. NF-κB-activating stimuli increased Gal-1 expression on T cells, an effect which could be selectively prevented by inhibitors of NF-κB signaling. Accordingly, transient transfection of the p65 subunit of NF-κB was sufficient to induce high Gal-1 expression. Using in silico studies and chromatin immunoprecipitation analysis we have identified a functional NF-κB binding site within the first intron of the LGALS1 gene. In addition, our results show that exogenous Gal-1 can attenuate NF-κB activation, as shown by inhibition of IκB-α degradation induced by pro-inflammatory stimuli, higher cytoplasmic retention of p65, lower NF-κB DNA binding activity and impaired transcriptional activation of target genes. The present study suggest a novel regulatory loop by which NF-κB induces expression of Gal-1, which in turn may lead to negative control of NF-κB signaling.

Proteomic analysis identifies galectin-1 as a predictive biomarker for relapsed/refractory disease in classical Hodgkin lymphoma

AbstractConsiderable effort has been spent identifying prognostic biomarkers in classic Hodgkin lymphoma (cHL). The aim of our study was to search for possible prognostic parameters in advanced-stage cHL using a proteomics-based strategy. A total of 14 cHL pretreatment tissue samples from younger, advanced-stage patients were included. Patients were grouped according to treatment response. Proteins that were differentially expressed between the groups were analyzed using 2D-PAGE and identified by liquid chromatography mass spectrometry. Selected proteins were validated using Western blot analysis. One of the differentially expressed proteins, the carbohydrate-binding protein galectin-1 (Gal-1), was further analyzed using immunohistochemistry HC and its expression was correlated with clinicopathologic and outcome parameters in 143 advanced-stage cHL cases. At the univariate level, high Gal-1 expression in the tumor microenvironment was correlated with poor event-free survival (P = .02). Among younger (≤ 61 years) patients, high Gal-1 was correlated with poorer overall and event-free survival (both P = .007). In this patient group and at the multivariate level, high Gal-1 expression retained a significant predictive impact on event-free survival. Therefore, in addition to its functional role in cHL-induced immunosuppression, Gal-1 is also associated with an adverse clinical outcome in this disease.

Galectin-1 is a major effector of TrkB-mediated neuroblastoma aggressiveness

Expression of Trk receptors is an important prognostic factor in neuroblastoma (NB) and other cancers. TrkB and its ligand brain-derived neurotrophic factor (BDNF) are preferentially expressed in NB with poor prognosis, conferring invasive and metastatic potential to the tumor cells as well as enhancing therapy resistance. Galectin-1 (Gal-1) has emerged as an interesting cancer target, as it is involved in modulating cell proliferation, cell death and cell migration, all of which are linked to cancer initiation and progression. We previously identified Gal-1 mRNA to be upregulated in patients with aggressive, relapsing NB and found that Gal-1 protein was upregulated in human SY5Y NB cells on activation of ectopically expressed TrkB (SY5Y-TrkB), but not TrkA (SY5Y-TrkA). Here, we report that Gal-1 mRNA levels positively correlated with TrkB expression and anticorrelated with TrkA expression in a cohort of 102 primary NB. Immunohistochemical analyses of 92 primary NB specimens revealed high Gal-1 expression in stromal septae and in neuroblasts. BDNF-mediated activation of TrkB enhanced invasiveness and migration in vitro, which could be impaired by transient transfection using Gal-1-specific siRNA or a neutralizing antibody directed against Gal-1. The addition of recombinant Gal-1 (rGal-1) in the absence of BDNF partially restored migration and invasive capacity. Using the Trk inhibitor K252a, we could show that the upregulation of Gal-1 protein strictly depended on activated TrkB. Our data suggest that targeting Gal-1 might be a promising strategy for the treatment of aggressive NB.

Differential regulation of constitutive and retinoic acid-induced galectin-1 gene transcription in murine embryonal carcinoma and myoblastic cells

Galectin-1 (gal-1), a galactoside-binding lectin, is found in many vertebrate tissues and its expression is regulated during development. We had found that gal-1 expression is increased in F9 murine embryonal carcinoma cells concurrently with induction of differentiation by all- trans retinoic acid (RA). In contrast, gal-1 expression was constitutively high in murine myoblastic C2C12 cells. Therefore, we used these two cell types as models to begin to understand the mechanisms underlying constitutive and RA-induced gal-1 expression. We transfected transiently into F9 cells a series of reporter constructs containing different deletions of the 5′ upstream region of the gal-1 gene promoter placed upstream of the chloramphenicol acetyltransferase reporter cDNA and evaluated the activation of transcription by RA treatment. The results indicate that the induction of gal-1 by RA is regulated at least partially at the level of transcription. A strong RA responsiveness region was found within the sequence from −1578 to −1448 upstream of the transcription start site (+1). In contrast, the high constitutive gal-1 expression in C2C12 cells appeared to be mediated by a sequence within the promoter region from −62 to +1, which contains an Sp1 consensus sequence. A gel electrophoretic mobility shift assay indicated that the transcription factor SP1 bound to the gal-1 Sp1 site and mutagenesis of this Sp1 site abolished both the binding of nuclear proteins to the mutated Sp1 site and the high constitutive expression of the gal-1 gene. The results demonstrate that gal-1 expression is cell type-specific and suggest that different factors regulate constitutive and RA-induced gal-1 expression.