Combined anti-Galectin-1 and anti-EGFR siRNA-loaded chitosan-lipid nanocapsules decrease temozolomide resistance in glioblastoma: in vivo evaluation

Glioblastoma is the most frequent primary malignant brain tumor in adults. Despite treatments including surgery, radiotherapy and chemotherapy by oral Temozolomide (TMZ), the prognosis of patients with glioblastoma remains very poor. This is partly due to the resistance of malignant cells to therapy particularly TMZ. Overexpression of epidermal growth factor receptor (EGFR) and Galectin-1 by tumor cells significantly contributes to TMZ resistance. The purpose of this study was to evaluate in vivo, the effect of local administration by convection enhanced delivery (CED) of the anti-EGFR and anti-Galectin-1 siRNAs administered separately or in combination on (i) the survival of nude mice-bearing orthotopic U87MG glioblastoma cells and on (ii) the EGFR and Galectin-1 expression in excised U87MG tumor tissue. Both siRNAs were carried by chitosan lipid nanocapsules (LNCs). Survival of mice treated 14 days after tumor implantation by the combination of anti-EGFR and anti-Galectin-1 siRNAs and TMZ (40 mg/kg) was significantly increased compared to animals treated by single anti-EGFR or anti-Galectin-1 siRNAs carried by chitosan-LNCs. This was confirmed by a decreased EGFR and Galectin-1 expression at the protein level in excised U87MG tumor tissue, 8 days post-transfection, visualized by immunofluorescence. This study demonstrates the potential of our strategy in glioblastoma therapy.

Thwarting galectin-induced immunosuppression in breast cancer

Novel therapeutic strategies are needed to counteract breast cancer-associated immunosuppression. Silencing the expression of galectin-1 in a breast carcinoma model inhibited tumor growth and prevented lung metastasis by reducing the frequency and immunosuppressive activity of CD4⁺CD25⁺ FOXP3⁺ regulatory T cells.

Targeting Galectin-1 in pancreatic cancer: immune surveillance on guard

The tumor microenviroment and immune barrier are known to modulate malignant disease progression. We have recently identified Galectin-1 as a key player in a novel stromal regulatory reaction driving immune evasion in pancreatic tumors in vivo. These results suggest that Galectin-1 inhibition represents a potential therapeutic strategy for one of the most deadly types of cancer.

OTX008, a selective small-molecule inhibitor of galectin-1, downregulates cancer cell proliferation, invasion and tumour angiogenesis

BACKGROUND

Galectin-1 (Gal1), a carbohydrate-binding protein is implicated in cancer cell proliferation, invasion and tumour angiogenesis. Several Gal1-targeting compounds have recently emerged. OTX008 is a calixarene derivative designed to bind the Gal1 amphipathic β-sheet conformation. Our study contributes to the current understanding of the role of Gal1 in cancer progression, providing mechanistic insights into the anti-tumoural activity of a novel small molecule Gal1-inhibitor.

METHODS

We evaluated in vitro OTX008 effects in a panel of human cancer cell lines. For in vivo studies, an ovarian xenograft model was employed to analyse the antitumour activity. Finally, combination studies were performed to analyse potential synergistic effects of OTX008.

RESULTS

In cultured cancer cells, OTX008 inhibited proliferation and invasion at micromolar concentrations. Antiproliferative effects correlated with Gal1 expression across a large panel of cell lines. Furthermore, cell lines expressing epithelial differentiation markers were more sensitive than mesenchymal cells to OTX008. In SQ20B and A2780-1A9 cells, OTX008 inhibited Gal1 expression and ERK1/2 and AKT-dependent survival pathways, and induced G2/M cell cycle arrest through CDK1. OTX008 enhanced the antiproliferative effects of Semaphorin-3A (Sema3A) in SQ20B cells and reversed invasion induced by exogenous Gal1. In vivo, OTX008 inhibited growth of A2780-1A9 xenografts. OTX008 treatment was associated with downregulation of Gal1 and Ki67 in treated tumours, as well as decreased microvessel density and VEGFR2 expression. Finally, combination studies showed OTX008 synergy with several cytotoxic and targeted therapies, principally when OTX008 was administered first.

CONCLUSION

This study provides insights into the role of Gal1 in cancer progression as well as OTX008 mechanism of action, and supports its further development as an anticancer agent.

Differential expression of galectin-1 and galectin-3 in canine non-malignant and malignant mammary tissues and in progression to metastases in mammary tumors

BACKGROUND

Galectin-1 and galectin-3 are carbohydrate-binding proteins that have been implicated in the pathobiology of several types of cancer. The aim of the present study was to investigate the expression pattern of both these galectins in canine non-neoplastic mammary tissues and mammary tumors (CMT).

MATERIALS AND METHODS

Protein and mRNA expression of galectin-1 and -3 were assessed in 12 benign and 41 malignant CMT.

RESULTS

Galectin-1 was overexpressed in the majority of malignant CMT cases in tumor cells and stroma. Its expression in malignant tumor cells was associated with smaller-sized tumours. Distant metastases presented a strong intensity of galectin-1 and reduced galectin-3 expression, while the opposite was observed in circulating tumor cells. Interestingly intravascular tumor cells presented galectin-3 up-regulation at the mRNA level. Double-labelling further made it clear that galectin-3 and galectin-1 expression did not overlap in normal-adjacent mammary and CMT cells.

CONCLUSION

Taken together, our data suggest that malignant CMT cell sub-populations have alternating expression of galectin-1 or -3. This might confer survival advantage to tumour cells in different phases of tumour progression.

Expression, purification and characterization of galectin-1 in Escherichia coli

As a member of beta-galactoside-binding proteins family, Galectin-1 (Gal-1) contains a single carbohydrate recognition domain, by means of which it can bind glycans both as a monomer and as a homodimer. Gal-1 is implicated in modulating cell-cell and cell-matrix interactions and may act as an autocrine negative growth factor that regulates cell proliferation. Besides, it can also suppress TH1 and TH17 cells by regulating dendritic cell differentiation or suppress inflammation via IL-10 and IL-27. In the present study, Gal-1 monomer and concatemer (Gal-1②), which can resemble Gal-1 homodimer, were expressed in Escherichia coli and their bioactivities were analyzed. The results of this indicate that both Gal-1 and Gal-1② were expressed in E. coli in soluble forms with a purity of over 95% after purifying with ion-exchange chromatography. Clearly, both Gal-1 and Gal-1② can effectively promote erythrocyte agglutination in hemagglutinating activity assays and inhibit Jurkat cell proliferation in MTT assays. All these data demonstrate that bacterially-expressed Gal-1 and Gal-1② have activities similar to those of wild type human Gal-1 whereas the bioactivity of concatemer Gal-1② was stronger than those of the bacterially-expressed and wild type human Gal.

Phosphoproteomic analyses reveal that galectin-1 augments the dynamics of B-cell receptor signaling

B-cell activation is important for mounting humoral immune responses and antibody production. Galectin-1 has multiple regulatory functions in immune cells. However, the effects of galectin-1 modulation and the mechanisms underlying the coordination of B-cell activation are unclear. To address this issue, we applied label-free quantitative phosphoproteomic analysis to investigate the dynamics of galectin-1-induced signaling in comparison with that following anti-IgM treatment. A total of 3247 phosphorylation sites on 1245 proteins were quantified, and 70-80% of the 856 responsive phosphoproteins were commonly activated during various biological functions. The similarity between galectin-1- and anti-IgM-elicited B-cell receptor (BCR) signaling pathways was also revealed. Additionally, the mapping of the 149 BCR-responsive phosphorylation sites provided complementary knowledge of BCR signaling. Compared to anti-IgM induction, the phosphoproteomic profiling of BCR signaling, along with validation by western blot analysis and pharmacological inhibitors, revealed that the activation of Syk, Btk, and PI3K may be dominant in galectin-1-mediated activation. We further demonstrated that the proliferation of antigen-primed B cells was diminished in the absence of galectin-1 in an animal model. Together, these findings provided evidence for a new role and insight into the mechanism of how galectin-1 augments the strength of the immunological synapse by modulating BCR signaling.

BIOLOGICAL SIGNIFICANCE

The current study revealed the first systematic phosphorylation-mediated signaling network and its dynamics in B cell activation. The comparative phosphoproteomic analysis on the dynamics of galectin-1 induced activation profiles not only showed that exogenously added galectin-1 augmented B-cell activation but also revealed its relatively enhanced activation in PI3K pathway. Together with proliferation assay, we further delineated that galectin-1 is important for B-cell proliferation in response to antigen challenge. Our phosphoproteomic study reveals a new role for galectin-1 in augmenting the strength of immunological synapse by modulating BCR signaling.

Transcriptional and metabolic pre-B cell receptor-mediated checkpoints: implications for autoimmune diseases

At the pre-B cell stage of lymphocyte development, immunoglobulin light-chains are not yet produced, and heavy-chains are covalently linked to surrogate light-chains composed of VpreB and λ5 to form the pre-B cell receptor (pre-BCR) in a non-covalent association with signal-transducing modules. Even tough the pre-BCR does not have the potential to bind conventional antigens, accumulating evidence indicates that pre-BCR-mediated checkpoints are important both for negative and positive selection of self-reactivity, and that defects in these regulatory nodes may be associated with autoimmune disease. Thus, the transcription factor BACH2, which represents a susceptibility locus for rheumatoid arthritis, has recently emerged as a crucial mediator of negative selection at a pre-BCR checkpoint. The lysosome-associated protein LAPTM5, which is highly expressed in an animal model of Sjögren's syndrome, plays a role in down-modulation of the pre-BCR. Studies of copy number variation in rheumatoid arthritis suggest that a reduced dosage of the VPREB1 gene is involved in disease pathogenesis. Notably, animal models of autoimmune disease exhibit defects in pre-B to naïve B cell checkpoints. Administration of a pre-BCR ligand, which also plays a role in anergy both in human and murine B lymphocytes, ameliorates disease in experimental models of autoimmunity. Further investigation is required to gain a better insight into the molecular mechanisms of pre-BCR-mediated checkpoints and to determine their relevance to autoimmune diseases.

Myosin IIa activation is crucial in breast cancer derived galectin-1 mediated tolerogenic dendritic cell differentiation

BACKGROUND

Tolerogenic dendritic cells (tDCs) play important roles in immune tolerance, autoimmune disease, tissue transplantation, and the tumor micro-environment. Factors that induce tDCs have been reported, however the intracellular mechanisms involved are rarely discussed.

METHODS

Circulating CD14(+)CD16(+) of breast cancer patients and induced CD14(+)CD16(+) DCs were identified as tDCs by treating CD14(+) monocytes with galectin-1 and cancer cell-derived medium combined with IL-4 and GM-CSF. In addition, the 4T1 breast cancer syngeneic xenograft model was used to investigate the effect of galectin-1 in vivo.

RESULTS

The CD14(+)CD16(+) tDC population in the breast cancer patients was comparatively higher than that in the healthy donors, and both the MDA-MB-231 conditioned medium and galectin-1 could induce tDC differentiation. In a BALB/c animal model, the 4T1 breast cancer cell line enhanced IL-10 expression in CD11c(+) DCs which was down-regulated after knocking down the galectin-1 expression of 4T1 cells. Analysis of galectin-1 interacting proteins showed that myosin IIa was a major target of galectin-1 after internalization through a caveolin-dependent endocytosis. Myosin IIa specific inhibitor could diminish the effects of galectin-1 on monocyte-derived tDCs and also block the 4T1 cell induced CD11c(+)/Ly6G(+)/IL-10(+) in the BALB/c mice.

CONCLUSIONS

Galectin-1 can induce tDCs after internalizing into CD14(+) monocytes through the caveolae-dependent pathway and activating myosin IIa. For the breast cancer patients with a high galectin-1 expression, blebbistatin and genistein show potential in immune modulation and cancer immunotherapy.

GENERAL SIGNIFICANCE

Myosin IIa activation and galectin-1 endocytosis are important in tumor associated tDC development.

Expression of Galectins 1, 3 and 9 in normal oral epithelium, oral squamous papilloma, and oral squamous cell carcinoma

BACKGROUND

The aim of this study was to characterize the immunohistochemical expression of galectin 1, 3, and 9 in normal oral epithelium, oral squamous papilloma, and oral squamous cell carcinoma.

MATERIALS AND METHODS

Immunohistochemical staining for galectins 1, 3, and 9 was evaluated in 8 samples of normal oral squamous epithelium, 15 samples of oral squamous papilloma, and 41 samples of oral squamous cell carcinoma. Immunohistochemical data were assessed by Kruskal-Wallis non-parametric test followed by Dunn's test. For all analyzes, it was adopted the value of P <0.05 for statistical significance.

RESULTS

Significant differences were found in galectin- 3 expression when comparing ordinary mucosa and oral squamous papilloma with the oral squamous cell carcinoma samples.

CONCLUSION

These findings indicate that galectin-3 is closely involved in malignant transformation of oral mucosa cells.

Autocrine galectin-1 promotes collective cell migration of squamous cell carcinoma cells through up-regulation of distinct integrins

We found that high galectin-1 (Gal-1) mRNA levels were associated with invasive squamous cell carcinoma (SCC) cells that expressed Snail, an epithelial-to-mesenchymal transition (EMT) regulator. Both Gal-1 overexpression and soluble Gal-1 treatment accelerated invasion and collective cell migration, along with activation of cdc42 and Rac. Soluble Gal-1 activated c-Jun N-terminal kinase to increase expression levels of integrins α2 and β5, which were essential for Gal-1 dependent collective cell migration and invasiveness. Soluble Gal-1 also increased the incidence of EMT in Snail-expressing SCC cells; these were a minor population with an EMT phenotype under growing conditions. Our findings indicate that soluble Gal-1 promotes invasiveness through enhancing collective cell migration and increasing the incidence of EMT.

Unraveling galectin-1 as a novel therapeutic target for cancer

Galectins belong to a family of carbohydrate-binding proteins with an affinity for β-galactosides. Galectin-1 is differentially expressed by various normal and pathologic tissues and displays a wide range of biological activities. In oncology, galectin-1 plays a pivotal role in tumor growth and in the multistep process of invasion, angiogenesis, and metastasis. Evidence indicates that galectin-1 exerts a variety of functions at different steps of tumor progression. Moreover, it has been demonstrated that galectin-1 cellular localization and galectin-1 binding partners depend on tumor localization and stage. Recently, galectin-1 overexpression has been extensively documented in several tumor types and/or in the stroma of cancer cells. Its expression is thought to reflect tumor aggressiveness in several tumor types. Galectin-1 has been identified as a promising drug target using synthetic and natural inhibitors. Preclinical data suggest that galectin-1 inhibition may lead to direct antiproliferative effects in cancer cells as well as antiangiogenic effects in tumors. We provide an up-to-date overview of available data on the role of galectin-1 in different molecular and biochemical pathways involved in human malignancies. One of the major challenges faced in targeting galectin-1 is the translation of current knowledge into the design and development of effective galectin-1 inhibitors in cancer therapy.

Clinicopathological and prognostic significance of galectin-1 and vascular endothelial growth factor expression in gastric cancer

AIM: To evaluate the expression of galectin-1 and vascular endothelial growth factor (VEGF) in gastric cancer and investigate their relationships with clinicopathologic factors and prognostic significance.

METHODS: Galectin-1 and VEGF were immunohistochemically investigated in tumor samples obtained from 214 gastric cancer patients with all tumor stages. Immunohistochemical analyses for galectin-1 and VEGF expression were performed on formalin-fixed, paraffin-embedded sections of surgical specimens. The relationship between the expression and staining intensity of galectin-1 and VEGF, clinicopathologic variables, and patient survival were analyzed. All patients underwent follow-up until cancer-related death or more than five years after tumor resection. P values < 0.05 were considered statistically significant.

RESULTS: Immunohistochemical staining demonstrated that 138 of 214 gastric cancer samples (64.5%) were positive for galectin-1, and 116 out of 214 gastric cancer samples (54.2%) were positive for VEGF. There was a significant association between galectin-1 and VEGF expression; VEGF was detected in 60.1% of galectin-1-positive samples and 43.4% of galectin-1-negative samples (P < 0.05). Galectin-1 expression was associated with tumor size, tumor location, stage, lymph node metastases, and VEGF expression (all P < 0.05). VEGF expression was related to tumor size, stage, and lymph node metastases (all P < 0.05). The 5-year survival rate was 56.6% for galectin-1-positive patients and 69.2% for galectin-1-negative patients, and the prognosis for galectin-1-positive patients was significantly poorer compared with galectin-1-negative patients (χ² = 13.880, P = 0.000). The 5-year survival rates for VEGF-positive and VEGF-negative patients were 53.4% and 70.5%, respectively (χ² = 4.619, P = 0.032). The overall survival rate of patients with both galectin-1 and VEGF overexpression in gastric cancer tissue samples was significantly poorer than other groups (both P < 0.05).

CONCLUSION: Galectin-1 expression was positively associated with VEGF expression. Both galectin-1 and VEGF can serve as independent prognostic indicators of poor survival for gastric cancer after gastrectomy.

Galectin-1-mediated biochemical controls of melanoma and glioma aggressive behavior

Gliomas and melanomas are associated with dismal prognosis because of their marked intrinsic resistance to proapoptotic stimuli, such as conventional chemotherapy and radiotherapy, as well as their ability to escape immune cell attacks. In addition, gliomas and melanomas display pronounced neoangiogenesis. Galectin-1 is a hypoxia-sensitive protein, which is abundantly secreted by glioma and melanoma cells, which displays marked proangiogenic effects. It also provides immune tolerogenic environments to melanoma and glioma cells through the killing of activated T cells that attack these tumor cells. Galectin-1 protects glioma and melanoma cells against cytotoxic insults (including chemotherapy and radiotherapy) through a direct role in the unfolded protein response. Altogether, these facts clearly point to galectin-1 as an important target to be combated in gliomas and melanomas in order to: (1) weaken the defenses of these two types of cancers against radiotherapy, chemotherapy and immunotherapy/vaccine therapy; and (2) reinforce antiangiogenic therapies. In the present article, we review the biochemical and molecular biology-related pathways controlled by galectin-1, which are actually beneficial for melanoma and glioma cells, and therefore detrimental for melanoma and glioma patients.

Overexpression of alpha1-protease inhibitor and galectin-1 in radiation-induced early phase of pulmonary fibrosis

PURPOSE

Radiation-induced pulmonary fibrosis (RIF) is a significant complication of radiotherapy for lung cancer. Despite the large number of studies, the molecular mechanisms of RIF are poorly understood. Therefore, the complex protein expression pattern in RIF was characterized by identifying the proteins with an altered expression level after thorax irradiation using two-dimensional electrophoresis (2-DE) and mass spectrometry.

MATERIALS AND METHODS

A mouse model of RIF was used to examine the alteration of the lung proteome because of availability of murine data related to human cases and the abundance of murine fibrotic lung samples. A mouse model of RIF was induced in radiosensitive C57BL/6 mice. Twenty-one weeks after 25 Gy irradiation, hematoxylin-eosin staining and hydroxyproline assay confirmed the early-phase pulmonary fibrosis.

RESULTS

Lung samples from the irradiated and age-matched control mice were used to generate 16 high quality 2-DE gels containing approximately 1,000 spots. Of the 31 significantly up- or down-regulated protein spots, 17 were identified by MALDI-TOF/MS.

CONCLUSIONS

Two important upregulated proteins were found, the alpha1-protease inhibitor and galectin-1, which might be used as potential markers for the early phase of RIF.