Targeted disruption of the galectin-3 gene results in decreased susceptibility to NNK-induced lung tumorigenesis: an oligonucleotide microarray study

Emerging Roles of Galectin-3 in Pulmonary Diseases

Galectin-3 is a multifunctional protein that is involved in various physiological and pathological events. Emerging evidence suggests that galectin-3 also plays a critical role in the pathogenesis of pulmonary diseases. Galectin-3 can be produced and secreted by various cell types in the lungs, and the overexpression of galectin-3 has been found in acute lung injury/acute respiratory distress syndrome (ALI/ARDS), pulmonary hypertension (PH), pulmonary fibrosis diseases, lung cancer, lung infection, chronic obstructive pulmonary disease (COPD), and asthma. Galectin-3 exerts diverse effects on the inflammatory response, immune cell activation, fibrosis and tissue remodeling, and tumorigenesis in these pulmonary disorders, and genetic and pharmacologic modulation of galectin-3 has therapeutic effects on the treatment of pulmonary illnesses. In this review, we summarize the structure and function of galectin-3 and the underlying mechanisms of galectin-3 in pulmonary disease pathologies; we also discuss preclinical and clinical evidence regarding the therapeutic potential of galectin-3 inhibitors in these pulmonary disorders. Additionally, targeting galectin-3 may be a very promising therapeutic approach for the treatment of pulmonary diseases.

The emerging role of galectins in high-fatality cancers

Although we witnessed considerable progress in the prevention and treatment of cancer during the past few decades, a number of cancers remain difficult to treat. The main reasons for this are a lack of effective biomarkers necessary for an early detection and inefficient treatments for cancer that are diagnosed at late stages of the disease. Because of their alarmin-like properties and their protumorigenic role during cancer progression, members of the galectin family are uniquely positioned to provide information that could be used for the exploration of possible avenues for the treatment of high fatality cancer (HFC). A rapid overview of studies that examined the expressions and functions of galectins in cancer cells reveals that they play a central role in at least three major features that characterize HFCs: (1) induction of systemic and local immunosuppression, (2) chemoresistance of cancer cells, and (3) increased invasive behavior. Defining the galectinome in HFCs will also lead to a better understanding of tumor heterogeneity while providing critical information that could improve the accuracy of biomarker panels for a more personalized treatment of HFCs. In this review, we discuss the relevance of the galectinome in HFC and its possible contribution to providing potential solutions.

The role of Galectin-3 in modulating tumor growth and immunosuppression within the tumor microenvironment

The efficacy of cancer immunotherapy is limited, in part, by the multitude of immunosuppressive mechanisms present within the tumor microenvironment (TME). Galectin-3 (Gal-3) is a lectin that contributes to TME immunosuppression and regulates diverse functions including cellular homeostasis and cancer biology. Increased Gal-3 expression during cancer progression augments tumor growth, invasiveness, metastatic potential, and immune suppression, which highlights the potential use of Gal-3 as a therapeutic target capable of modulating anti-tumor immunity. Here, we discuss the mechanisms by which Gal-3 regulates lymphocytes, the role of Gal-3 in lung and prostate tumors, and the contribution of Gal-3 to TME immunosuppression.

The impact of low-dose carcinogens and environmental disruptors on tissue invasion and metastasis

The purpose of this review is to stimulate new ideas regarding low-dose environmental mixtures and carcinogens and their potential to promote invasion and metastasis. Whereas a number of chapters in this review are devoted to the role of low-dose environmental mixtures and carcinogens in the promotion of invasion and metastasis in specific tumors such as breast and prostate, the overarching theme is the role of low-dose carcinogens in the progression of cancer stem cells. It is becoming clearer that cancer stem cells in a tumor are the ones that assume invasive properties and colonize distant organs. Therefore, low-dose contaminants that trigger epithelial-mesenchymal transition, for example, in these cells are of particular interest in this review. This we hope will lead to the collaboration between scientists who have dedicated their professional life to the study of carcinogens and those whose interests are exclusively in the arena of tissue invasion and metastasis.

The TAM family: phosphatidylserine sensing receptor tyrosine kinases gone awry in cancer

The TYRO3, AXL (also known as UFO) and MERTK (TAM) family of receptor tyrosine kinases (RTKs) are aberrantly expressed in multiple haematological and epithelial malignancies. Rather than functioning as oncogenic drivers, their induction in tumour cells predominately promotes survival, chemoresistance and motility. The unique mode of maximal activation of this RTK family requires an extracellular lipid–protein complex. For example, the protein ligand, growth arrest-specific protein 6 (GAS6), binds to phosphatidylserine (PtdSer) that is externalized on apoptotic cell membranes, which activates MERTK on macrophages. This triggers engulfment of apoptotic material and subsequent anti-inflammatory macrophage polarization. In tumours, autocrine and paracrine ligands and apoptotic cells are abundant, which provide a survival signal to the tumour cell and favour an anti-inflammatory, immunosuppressive microenvironment. Thus, TAM kinase inhibition could stimulate antitumour immunity, reduce tumour cell survival, enhance chemosensitivity and diminish metastatic potential.

Galectin-3 in cancer

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

The roles of Galectin-3 in autoimmunity and tumor progression

Galectin-3, a unique chimera-type member of the β-galactoside-binding soluble lectin family, is widely expressed in numerous cells. Here, we discuss the role of Galectin-3 in T-cell-mediated inflammatory (auto) immunity and tumor rejection by using Galectin-3-deficient mice and four disease models of human pathology: experimental autoimmune encephalomyelitis (EAE), Con-A-induced hepatitis, multiple low-dose streptozotocin-induced diabetes (MLD-STZ diabetes) and metastatic melanoma. We present evidence which suggest that Galectin-3 plays an important pro-inflammatory role in Con-A-induced hepatitis by promoting the activation of T lymphocytes, NKT cells and DCs, cytokine secretion, prevention of M2 macrophage polarization and apoptosis of mononuclear cells, and it leads to severe liver injury. In addition, experiments in Galectin-3-"knock-out" mice indicate that Galectin-3 is also involved in immune-mediated β-cell damage and is required for diabetogenesis in MLD-STZ model by promoting the expression of IFN-gamma, TNF-alpha, IL-17 and iNOS in immune and accessory effector cells. Next, our data demonstrated that Galectin-3 plays an important disease-exacerbating role in EAE through its multifunctional roles in preventing cell apoptosis and increasing IL-17 and IFN-gamma synthesis, but decreasing IL-10 production. Finally, based on our findings, we postulated that expression of Galectin-3 in the host may also facilitate melanoma metastasis by affecting tumor cell adhesion and modulating anti-melanoma immune response, in particular innate antitumor immunity. Taken together, we discuss the evidence of pro-inflammatory and antitumor activities of Galectin-3 and suggest that Galectin-3 may be an important therapeutic target.

Reprogramming of mouse fibroblasts to an intermediate state of differentiation by chemical induction

Induced pluripotent stem cells (iPSCs) generated by forced expression of four transcription factors offer promises for regenerative and therapeutic uses in human diseases. However, it is necessary to overcome the risk of tumorigenicity caused by the use of potent oncogenes and the use of randomly integrating vectors before the iPSC technology can be applied to human medicine. Stem cells and cancer cells share many features in common, implying that there are similar underlying mechanisms in their development. Small molecules have been used to induce cell reprogramming for lineage trans-differentiation and for maintaining pluripotency of stem cells. In this study, we investigated the possibility of replacing all reprogramming viral factors with small molecules. To this end, we evaluated the effects of carcinogens at nongenotoxic levels on somatic cells. We identified 16 candidate chemicals through biology-oriented in silico high-throughput screening with commercially available inventories from Sigma-Aldrich for cancer research, and established a reprogramming protocol of 16-day treatment followed by 5 days of recovery. This protocol was applied to B6/129 mouse embryonic fibroblasts (MEFs) at passage 3. From recovery day 2, colonies appeared at an efficiency of 0.02%. These colonies were positive for both alkaline phosphatase and surface specific embryonic antigen-1 (SSEA-1) at a comparable level to those of mouse embryonic stem cells (ESCs). Global gene expression analysis with a 38K gene MEEBO microarray revealed that the colonies had 564 (1.5%) differentially expressed genes compared to MEFs at day 0 of treatment, and these genes were enriched in "neuromuscular differentiation." Moreover, 122 differentially expressed genes in the colonies were ESC-enriched, including downregulated somatic markers and upregulated stem cell markers. In conclusion, combined chemical treatment of MEFs herein might have caused these cells to transverse to an intermediate state within the mesodermal lineages.

NNK-Induced Lung Tumors: A Review of Animal Model

The incidence of lung adenocarcinoma has been remarkably increasing in recent years due to the introduction of filter cigarettes and secondary-hand smoking because the people are more exposed to higher amounts of nitrogen oxides, especially 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone(NNK), which is widely applied in animal model of lung tumors. In NNK-induced lung tumors, genetic mutation, chromosome instability, gene methylation, and activation of oncogenes have been found so as to disrupt the expression profiles of some proteins or enzymes in various cellular signal pathways. Transgenic animal with specific alteration of lung cancer-related molecules have also been introduced to clarify the molecular mechanisms of NNK in the pathogenesis and development of lung tumors. Based on these animal models, many antioxidant ingredients and antitumor chemotherapeutic agents have been proved to suppress the NNK-induced lung carcinogenesis. In the future, it is necessary to delineate the most potent biomarkers of NNK-induced lung tumorigenesis, and to develop efficient methods to fight against NNK-associated lung cancer using animal models.

Deletion of galectin-3 in the host attenuates metastasis of murine melanoma by modulating tumor adhesion and NK cell activity

Galectin-3, a β galactoside-binding lectin, plays an important role in the processes relevant to tumorigenesis such as malignant cell transformation, invasion and metastasis. We have investigated whether deletion of Galectin-3 in the host affects the metastasis of B16F1 malignant melanoma. Galectin-3-deficient (Gal-3(-/-)) mice are more resistant to metastatic malignant melanoma as evaluated by number and size of metastatic colonies in the lung. In vitro assays showed lower number of attached malignant cells in the tissue section derived from Gal-3(-/-) mice. Furthermore, lack of Galectin-3 correlates with higher serum levels of IFN-γ and IL-17 in tumor bearing hosts. Interestingly, spleens of Gal-3(-/-) mice have lower number of Foxp3(+) T cells after injection of B16F1 melanoma cells. Finally, we found that while CD8(+) T cell and adherent cell cytotoxicity were similar, there was greater cytotoxic activity of splenic NK cells of Gal-3(-/-) mice compared with "wild-type" (Gal-3( +/+ )) mice. Despite the reduction in total number of CD3ε(-)NK1.1(+), Gal-3(-/-) mice constitutively have a significantly higher percentage of effective cytotoxic CD27(high)CD11b(high) NK cells as well as the percentage of immature CD27(high)CD11b(low) NK cells. In contrast, CD27(low)CD11b(high) less functionally exhausted NK cells and NK cells bearing inhibitory KLRG1 receptor were more numerous in Gal-3( +/+ ) mice. It appears that lack of Galectin-3 affects tumor metastasis by at least two independent mechanisms: by a decrease in binding of melanoma cells onto target tissue and by enhanced NK-mediated anti-tumor response suggesting that Galectin-3 may be considered as therapeutic target.

Absence of galectin-3 does not affect the development of experimental tongue carcinomas in mice

BACKGROUND

Galectin-3 is a lectin that presents pivotal roles in tumor biology and there are no studies evaluating their expression in dysplasias and carcinomas developed from tongue carcinogenesis models.

AIMS

To investigate the role of galectin-3 in the development of tongue carcinomas using a mouse model of oral carcinogenesis.

METHODS

Galectin-3-deficient (gal3(-/-)) and wild-type (gal3(+/+)) mice were challenged with 4-nitroquinoline-1-oxide in drinking water for 16weeks and killed at different times. Tongues were removed and the number of dysplasias and carcinomas was counted. An immunohistochemical study for galectin-3 was performed only in the tongue from gal3(+/+) mice.

RESULTS

In both groups, a reduction of dysplasias and an increase of carcinomas from week 16 to week 32 (p>0.05) were observed. A predominance of high cytoplasmic and nuclear galectin-3 expression was observed in carcinomas (64.7%) and dysplasias (55.5%), respectively (p>0.05). The perilesional areas always presented a statistical cytoplasmic and nuclear galectin-3 overexpression.

CONCLUSIONS

Absence of galectin-3 did not directly affect the process of carcinogenesis and a cytoplasm shift of galectin-3 seems to be associated with development of tongue carcinomas.

A novel clinically relevant animal model for studying galectin-3 and its ligands during colon carcinogenesis

Galectin-3 (Gal-3) is a multifunctional protein that plays different roles in cancer biology. To better understand the role of Gal-3 and its ligands during colon carcinogenesis, we studied its expression in tumors induced in rats treated with 1,2-dimethylhydrazine (DMH) and in human tissues. Normal colon from untreated rats showed no staining using two specific monoclonal antibodies. In contrast, morphologically normal colon from DMH-treated rats and dysplastic aberrant crypt foci were strongly stained, indicating that increased Gal-3 expression is an early event during the neoplastic transformation in colon cells. Gal-3 was weakly expressed in adenocarcinomas. Overall, the Gal-3 expression pattern observed in the DMH rat model closely resembles that displayed by human colon stained with the same antibodies. We also found that Gal-3 phosphorylation diminishes in serines while increasing in tyrosines during rat colon carcinogenesis. Finally, we showed that Gal-3-ligands expression is strikingly similar in rat and human malignant colon and in non-malignant tissues. In conclusion, the DMH-induced rat colon cancer model displays expression patterns of Gal-3 and its ligands very similar to those observed in human samples. This animal model should contribute to clarifying the role of Gal-3 in colon carcinogenesis and also to finding effective preventive cancer agents based on Gal-3 targeting.

Galectin 3 induces a distinctive pattern of cytokine and chemokine production in rheumatoid synovial fibroblasts via selective signaling pathways

OBJECTIVE

High expression of galectin 3 at sites of joint destruction in rheumatoid arthritis (RA) suggests that galectin 3 plays a role in RA pathogenesis. Previous studies have demonstrated the effects of galectins on immune cells, such as lymphocytes and macrophages. This study was undertaken to investigate the hypothesis that galectin 3 induces proinflammatory effects in RA by modulating the pattern of cytokine and chemokine production in synovial fibroblasts.

METHODS

Matched samples of RA synovial and skin fibroblasts were pretreated with galectin 3 or tumor necrosis factor alpha (TNFalpha), and the levels of a panel of cytokines, chemokines, and matrix metalloproteinases (MMPs) were determined using enzyme-linked immunosorbent assays and multiplex assays. Specific inhibitors were used to dissect signaling pathways, which were confirmed by Western blotting and NF-kappaB activation assay.

RESULTS

Galectin 3 induced secretion of interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor, CXCL8, and MMP-3 in both synovial and skin fibroblasts. By contrast, galectin 3-induced secretion of TNFalpha, CCL2, CCL3, and CCL5 was significantly greater in synovial fibroblasts than in skin fibroblasts. TNFalpha blockade ruled out autocrine TNFalpha-stimulated induction of chemokines. The MAPKs p38, JNK, and ERK were necessary for IL-6 production, but phosphatidylinositol 3-kinase (PI 3-kinase) was required for selective CCL5 induction. NF-kappaB activation was required for production of both IL-6 and CCL5.

CONCLUSION

Our findings indicate that galectin 3 promotes proinflammatory cytokine secretion by tissue fibroblasts. However, galectin 3 induces the production of mononuclear cell-recruiting chemokines uniquely from synovial fibroblasts, but not matched skin fibroblasts, via a PI 3-kinase signaling pathway. These data provide further evidence of the role of synovial fibroblasts in regulating the pattern and persistence of the inflammatory infiltrate in RA and suggest a new and important functional consequence of the observed high expression of galectin 3 in the rheumatoid synovium.

Current concepts on the role of inflammation in COPD and lung cancer

Chronic obstructive pulmonary disease (COPD) and lung cancer are leading cause of death, and both are associated with cigarette smoke exposure. It has been shown that 50-70% of patients diagnosed with lung cancer suffer from COPD, and reduced lung function is an important event in lung cancer suggesting an association between COPD and lung cancer. However, a causal relationship between COPD and lung tumorigenesis is not yet fully understood. Recent studies have suggested a central role of chronic inflammation in the pathogenesis of both the diseases. For example, immune dysfunction, abnormal activation of NF-kappaB, epithelial-to-mesenchymal transition, altered adhesion signaling pathways, and extracellular matrix degradation/altered signaling are the key underlying mechanisms in both COPD and lung cancer. These parameters along with other processes, such as chromatin modifications/epigenetic changes, angiogenesis, and autophagy/apoptosis are altered by cigarette smoke, are crucial in the development of COPD and lung cancer. Understanding the cellular and molecular mechanisms underlying these processes will provide novel avenues for halting the chronic inflammation in COPD and devising therapeutic strategies against lung cancer.

SV40 T antigen disrupted the cell metabolism and the balance between proliferation and apoptosis in lens tumors of transgenic mice

PURPOSE

Simian Vacuolating Virus 40 (SV40) T antigen perturbed p53 and RB to cause cell malignant transformation. The purpose of this study was to identify the molecular changes during lens carcinogenesis and cancer progression induced by SV40 T antigen.

METHODS

The different lens lesions of alpha A-crystallin/SV40 T antigen transgenic mice were examined using cDNA microarray, immunohistochemistry and TUNEL to scan the influenced molecules and signal pathways.

RESULTS

There appeared dysplasia, carcinoma in situ, followed by invasion inside or outside eyeball, and final metastasis into lymph node or lung. Cell functions largely changed from such many aspects as cell cycle, cell morphology, cell development, cell-to-cell signaling and so forth since lens carcinogenesis. The significant differences were observed in such signaling pathways as metabolism about carbohydrate, amino acid, nucleotides, Xenobiotics and nitrogen (P < 0.05).The remarkable distinction of cell proliferation and cell death was found after carcinoma began to invade. There was significant alteration in cell growth, cell cycle, cell-to-cell signaling and metabolism since carcinoma invasion outside the eyeball happened. Parafibromin, Stat 1alpha, Mek kinase-1, CK2alpha, GRP78, Arp2 and Apr3 were not expressed in wild-type mice lens, but in others. The proliferative levels of dysplasia, carcinoma in situ and invasive carcinoma inside eyeballs were statistically higher than other groups (P < 0.05). The apoptotic levels of dysplasia were significantly higher than wild-type control (P < 0.05), but lower than the others (P < 0.05).

CONCLUSION

SV40 T antigen remarkably targeted the cell metabolism and disrupted the balance between proliferation and apoptosis during the lens carcinogenesis and following progression.