Galectin-7 Induction by EHMT2 Inhibition Enhances Immunity in Microsatellite Stability Colorectal Cancer

BACKGROUND & AIMS

Although immunotherapy shows substantial advancement in colorectal cancer (CRC) with microsatellite instability high, it has limited efficacy for CRC with microsatellite stability (MSS). Identifying combinations that reverse immune suppression and prime MSS tumors for current immunotherapy approaches remains an urgent need.

METHODS

An in vitro CRISPR screen was performed using coculture models of primary tumor cells and autologous immune cells from MSS CRC patients to identify epigenetic targets that could enhance immunotherapy efficacy in MSS tumors.

RESULTS

We revealed EHMT2, a histone methyltransferase, as a potential target for MSS CRC. EHMT2 inhibition transformed the immunosuppressive microenvironment of MSS tumors into an immunomodulatory one by altering cytokine expression, leading to T-cell-mediated cytotoxicity activation and improved responsiveness to anti-PD1 treatment. We observed galectin-7 up-regulation upon EHMT2 inhibition, which converted a "cold" MSS tumor environment into a T-cell-inflamed one. Mechanistically, CHD4 repressed galectin-7 expression by recruiting EHMT2 to form a cotranscriptional silencing complex. Galectin-7 administration enhanced anti-PD1 efficacy in MSS CRC, serving as a potent adjunct cytokine therapy.

CONCLUSIONS

Our findings suggest that targeting the EHMT2/galectin-7 axis could provide a novel combination strategy for immunotherapy in MSS CRC.

Galectin-7 promotes cisplatin efficacy by facilitating apoptosis and G3BP1 degradation in cervical cancer

The emergence of chemoresistance in cervical cancer is extremely challenging in chemotherapy. Oxidative stress has emerged as the regulatory factor in drug resistance, but the detailed mechanism is still unknown. Stress granules, are membrane-less ribonucleoprotein-based condensates, could enhance chemoresistance by sequestering proapoptotic proteins inhibition of cell death upon exposure to drug-induced oxidative stress. Galectin-7, a member of galectin family, exerts varied roles in tumor repression or progression in different cancers. However, its role in cervical cancer has not been sufficiently studied. Here, we found that galectin-7 promotes cisplatin (CDDP) induced apoptosis and associates with stress granule-nucleating protein G3BP1 degradation. With the treatment of cisplatin, galectin-7 could enhance apoptosis by upregulating cleaved-PARP1 and the generation of reactive oxygen species (ROS), promoting mitochondrial fission, and reducing mitochondrial membrane potential (MMP). Furthermore, galectin-7 also reduces resistance by facilitating cisplatin-induced stress granules clearance through galectin-7/RACK1/G3BP1 axis. All these data suggested that galectin-7 promotes cisplatin sensitivity, and it would be potential target for potentiating efficacy in cervical cancer chemotherapy.

Galectin-7 dysregulates renin-angiotensin-aldosterone and NADPH oxide synthase pathways in preeclampsia

OBJECTIVES

Preeclampsia is a life-threatening disorder of pregnancy unique to humans. Poor placentation in the first trimester of pregnancy is widely accepted to be an underlying cause of preeclampsia. Galectin-7 is abnormally elevated in chorionic villous samples and serum from women that subsequently develop pre-term preeclampsia. Administration of exogenous galectin-7 to pregnant mice causes preeclampsia-like features (hypertension, proteinuria), associated with dysregulation of the renin-angiotensin system (RAS). In this study investigated the mechanism by which galectin-7 induces alterations to tissue RAS homeostasis and ROS production. We hypothesized that galectin-7 induces alterations in the production of either placental RAS or NADPH oxidases (or both) to drive the dysregulated RAS and ROS production seen in preeclampsia.

STUDY DESIGN

Mated female mice (n = 5-6/group) received single (embryonic day [E]12/13) or multiple (E8-12) subcutaneous injections of 400 μg/kg/day galectin-7 or vehicle control and killed on E13 or E18. Human first trimester placental villous and decidual tissue (n = 11) was cultured under 8 % oxygen with 1 µg/mL galectin-7 or vehicle control for 16 h.

RESULTS

Galectin-7 administration to pregnant mice impaired placental labyrinth formation, suppressed circulating aldosterone and altered placental RAS (Agt, Renin) and NADPH oxidase (Cyba, Cybb and Icam1) mRNA expression. In vitro, galectin-7 regulated human placental villous RAS (AGT) and NADPH oxidase (CYBA, ICAM1 and VCAM1) mRNA expression.

CONCLUSIONS

Overall, galectin-7 likely drives hypertension in preeclampsia via its direct regulation of multiple pathways associated with preeclampsia in the placenta. Galectin-7 may therefore be a therapeutic target to improve placental function and prevent preeclampsia.

CCCTC-binding factor transcriptionally regulates Galectin-7 and activates the JNK/STAT3 axis to aggravate bronchial epithelial cell injury

OBJECTIVE

Studies have shown that the expression of CCCTC-binding factor (CTCF) is significantly upregulated in the airway epithelial cells of asthmatic patients, suggesting that CTCF may play an important role in the progression of asthma.

MATERIAL/METHODS

Human bronchial epithelial cells BEAS-2B were stimulated with transforming growth factor-β1 (TGF-β1) at a concentration of 10 ng/ml, and CTCF overexpression plasmid and CTCF small interfering RNA were transfected into the cells. The proliferation, apoptosis, inflammatory factor secretion, and airway remodeling marker protein expression of injured cells were detected. We bidirectionally regulated Galectin-7 expression in TGF-β1-induced BEAS-2B cells and overexpress CTCF, while interfering with Galectin-7 to further explore the regulatory effect of CTCF on Galectin-7. We introduced SP600125, a c-Jun N-terminal kinase c-Jun (JNK) pathway inhibitor, to investigate whether CTCF affects asthma progression through the JNK pathway.

RESULTS

The expression of CTCF in BEAS-2B cells induced by TGF-β1 was significantly upregulated, interfering with CTCF expression promoted cell proliferation, inhibited apoptosis, reduced inflammatory factors secretion, and decreased the expression of airway remodeling marker protein. Luciferase reporter gene analysis and chromatin immunoprecipitation verified that CTCF directly bound to Galectin-7 promoter. The effect of Galectin-7 on cells is consistent with the effect of CTCF on cells. The regulatory effect of CTCF on injured cells was indeed mediated by activation of the JNK/STAT3 axis.

CONCLUSIONS

CTCF transcriptionally regulated Galectin-7 and activated JNK/STAT3 axis to aggravate bronchial epithelial cell injury.

Galectin-7 promotes proliferation and wound healing capacities in periodontal ligament fibroblasts by activating ERK signaling

Periodontitis is a progressive inflammation condition and a primary cause of tooth loss in adults. As one of the abundant cell types in the periodontium, periodontal ligament fibroblasts (PDLFs) play an integral role in the maintenance and regeneration of periodontal tissue. Our previous work has shown that the application of Er:YAG laser increased the cell proliferation and migratory capacity of PDLFs via induction of galectin-7. In the present study, we aimed to evaluate if the forced expression of galectin-7 directly affected the cellular phenotypes of PDLFs. Our results showed that the cell proliferation, transwell migration, invasion, and wound healing capacities were all upregulated in PDLFs with the ectopic expression of galectin-7. These results suggest that therapeutic approaches to enhance the expression of galectin-7 in periodontium may accelerate tissue regeneration by recruiting more PDLFs to the injured site.

Ultrasound‑targeted microbubble destruction‑mediated Galectin‑7‑siRNA promotes the homing of bone marrow mesenchymal stem cells to alleviate acute myocardial infarction in rats

Bone marrow mesenchymal stem cells (BMSCs) are accepted as a form of cellular therapy to improve cardiac function following acute myocardial infarction (AMI). The present study was performed to investigate the synergistic effect of ultrasound-targeted microbubble destruction (UTMD)-mediated Galectin-7-small interfering (si)RNA with the homing of BMSCs for AMI. The rat model of AMI was established, followed by identification of BMSCs. Rats with AMI received BMSC transplantation, BMSC transplantation + UTMD + siRNA negative control, or BMSC transplantation + UTMD + Galectin-7-siRNA. The cardiac function, hemodynamics indexes, degree of myocardial fiber injury and expression of apoptosis-related proteins in myocardial tissues of rats were detected. The homing of BMSCs was observed, and the indexes of myocardial microenvironment and the TGF-β/Smads pathway-related proteins in myocardial tissues were determined. AMI rats treated with UTMD-mediated Galectin-7-siRNA exhibited improved cardiac function and hemodynamics-related indices, decreased myocardial fiber injury and apoptotic cells, as well as enhanced homing ability of BMSCs, improved myocardial microenvironment, and suppressed TGF-β1/Smads pathway activation. In conclusion, the present study demonstrated that UTMD-mediated Galectin-7-siRNA treatment could enhance the homing ability of BMSCs, thus alleviating AMI in rats.

Targeted galectin-7 inhibition with ultrasound microbubble targeted gene therapy as a sole therapy to prevent acute rejection following heart transplantation in a Rodent model

BACKGROUND

Despite significant advances in transplantation, acute cellular rejection (AR) remains a major obstacle that is most prevalent in the first months post heart transplantation (HT). Current treatments require high doses of immunosuppressive drugs followed by maintenance therapies that have systemic side effects including early infection. In this study, we attempted to prevent AR with a myocardial-targeted galectin-7-siRNA delivery method using cationic microbubbles (CMBs) combined with ultrasound targeted microbubble destruction (UTMD) to create local immunosuppression in a rat abdominal heterotopic heart transplantation acute rejection model.

METHODS AND RESULTS

Galectin-7-siRNA (siGal-7) bound to CMBs were synthesized and effective ultrasound-targeted delivery of siGal-7 into target cells confirmed in vitro. Based on these observations, three transplant rat models were tested：①isograft (ISO); ② Allograft (ALLO) +UTMD; and ③ALLO + PBS. UTMD treatments were administered at 1, 3, 5, 7 days after HT. Galectin 7 expression was reduced by 50% compared to ALLO + PBS (p < 0.005), and this was associated with significant reductions in both galectin 7 and Interleukin-2 protein levels (p < 0.001). The ALLO + UTMD group had Grade II or less inflammatory infiltration and myocyte damage in 11/12 rats using International Society For Heart and Lung Transplantation grading, compared to 0/12 rats with this grading in the ALLO + PBS group at 10 days post HT (p < 0.001).

CONCLUSIONS

Ultrasound-targeted galectin-7-siRNA knockdown with UTMD can prevent acute cellular rejection in the early period after allograft heart transplantation without the need for systemic immunosuppression.

KEY WORDS

Microbubble, Acute Rejection, Heart Transplantation, Galectin-7, RNA.

Silencing of Gal-7 inhibits TGF-β1-induced apoptosis of human airway epithelial cells through JNK signaling pathway

Apoptosis of epithelial cells is regarded as the initial pathological process of many lung diseases, including asthma. Previous studies have identified that galectin-7 (Gal-7), a regulator of apoptosis, was overexpressed in bronchial epithelial cells in asthma. However, the effect and mechanism of Gal-7 in the progression of asthma is still unclear. In this study, we investigated the expression and role of Gal-7 in the apoptosis of bronchial epithelial cells BEAS-2B upon TGF-β₁ stimulation. TGF-β₁ significantly induced apoptosis of BEAS-2B cells, as determined by flow cytometry. Western blot results revealed that the mRNA and protein expression of Gal-7 were obviously increased after TGF-β₁ stimulation. Small interfering RNA (siRNA)-mediated knockdown of Gal-7 abrogated TGF-β₁-evoked cell apoptosis. Simultaneously, increased Bcl-2 expression, decreased Bax expression and the cleavage of poly ADP-ribose polymerase (PARP) and caspase-3 activity were also monitored in TGF-β₁-treated cells after Gal-7 siRNA transfection. Gal-7 silence also inhibited TGF-β₁-induced c-Jun N-terminal kinase (JNK) phosphorylation in BEAS-2B cells. Furthermore, anisomycin, a specific activator for JNK, reversed the effect of Gal-7 siRNA on cell apoptosis induced by TGF-β₁. These results demonstrate that Gal-7 silence attenuates TGF-β₁-induced apoptosis in bronchial epithelial cells through the inactivation of JNK pathway. Therefore, Gal-7 may act as a potential target for asthma treatment.

HSP40 co-chaperone protein Tid1 suppresses metastasis of head and neck cancer by inhibiting Galectin-7-TCF3-MMP9 axis signaling

Human tumorous imaginal disc (Tid1), a DnaJ co-chaperone protein, is classified as a tumor suppressor. Previously, we demonstrated that Tid1 reduces head and neck squamous cell carcinoma (HNSCC) malignancy. However, the molecular details of Tid1-mediated anti-metastasis remain elusive.

Methods: We used affinity chromatography and systemic mass spectrometry to identify Tid1-interacting client proteins. Immunohistochemical staining of Tid1 in HNSCC patient tissues was examined to evaluate the association between the expression profile of Tid1-interacting client proteins with pathologic features and prognosis. The roles of Tid1-interacting client proteins in metastasis were validated both in vitro and in vivo. The interacting partner and downstream target of Tid1-interacting client protein were determined.

Results: Herein, we first revealed that Galectin-7 was one of the Tid1-interacting client proteins. An inverse association of protein expression profile between Tid1 and Galectin-7 was determined in HNSCC patients. Low Tid1 and high Galectin-7 expression predicted poor overall survival in HNSCC. Furthermore, Tid1 abolished the nuclear translocation of Galectin-7 and suppressed Galectin-7-induced tumorigenesis and metastasis. Keratinocyte-specific Tid1-deficient mice with 4-nitroquinoline-1-oxide (4NQO) treatment exhibited increased protein levels of Galectin-7 and had a poor survival rate. Tid1 interacted with Galectin-7 through its N-linked glycosylation to promote Tid1-mediated ubiquitination and proteasomal degradation of Galectin-7. Additionally, Galectin-7 played a critical role in promoting tumorigenesis and metastatic progression by enhancing the transcriptional activity of TCF3 transcription factor through elevating MMP-9 expression.

Conclusions: Overall, future treatments through activating Tid1 expression or inversely repressing the oncogenic function of Galectin-7 may exhibit great potential in targeting HNSCC progression.

Galectin-7 promotes proliferation and Th1/2 cells polarization toward Th1 in activated CD4+ T cells by inhibiting The TGFβ/Smad3 pathway

Galectin-7 (Gal-7) has been associated with cell proliferation and apoptosis. It is known that Gal-7 antagonises TGFβ-mediated effects in hepatocytes by interacting with Smad3. Previously, we have demonstrated that Gal-7 is related to CD4+ T cells responses; nevertheless, its effect and functional mechanism on CD4+ T cells responses remain unclear. The murine CD4+ T cells were respectively cultured with Gal-7, anti-CD3/CD28 mAbs, or with anti-CD3/CD28 mAbs & Gal-7. The effects of Gal-7 on proliferation and the phenotypic changes in CD4+ T cells were assessed by flow cytometry. The cytokines from CD4+ T cells were analysed by quantitative real-time PCR. Subcellular localisation and expression of Smad3 were determined by immunofluorescence staining and Western blot, respectively. Gal-7 enhanced the proliferation of activated CD4+ T cells in a dose- and β-galactoside-dependent manner. Additionally, Gal-7 treatment did not change the ratio of Th2 cells in activated CD4+ T cells, while it increased the ratio of Th1 cells. Gal-7 also induced activated CD4+ T cells to produce a higher level of IFN-γ and TNF-α and a lower level of IL-10. Moreover, Gal-7 treatment significantly accelerated nuclear export of Smad3 in activated CD4+ T cells. These results revealed a novel role of Gal-7 in promoting proliferation and Th1/2 cells polarization toward Th1 in activated CD4+ T cells by inhibiting the TGFβ/Smad3 pathway.

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-glucose environment induced intracellular O-GlcNAc glycosylation and reduced galectin-7 expression in keratinocytes: Implications on impaired diabetic wound healing

BACKGROUND

Diabetes is an important global health issue due to its increasing prevalence and association with various complications. Impaired wound healing is a serious complication associated with diabetes that frequently results in infection and amputation. Galectin-7 (Gal-7) has been reported to play an important role during skin wound healing. Previously, we had demonstrated that high glucose environment alters physiologic functions of keratinocytes and contributes to impaired wound healing in diabetic condition.

OBJECTIVE

In this study, we hypothesized that Gal-7 expression of keratinocytes may be involved in delayed wound healing of diabetics.

METHODS

Using cultured human keratinocytes and diabetic mice model, the Gal-7 expression was evaluated under high glucose environment.

RESULTS

Our results demonstrated that high-glucose environment reduced Gal-7 expression, a molecule that plays an important role in keratinocyte migration. Additionally, we found that increased O-linked N-Acetyl-glucosamine (O-GlcNAc) is responsible for reduced Gal-7 expression in keratinocytes exposed to high glucose environment.

CONCLUSION

Taken together, restoring the levels of Gal-7 and O-GlcNAc glycosylation may present novel therapeutic approach to promote wound healing in diabetic patients.

Systems-level effects of ectopic galectin-7 reconstitution in cervical cancer and its microenvironment

Background

Galectin-7 (Gal-7) is negatively regulated in cervical cancer, and appears to be a link between the apoptotic response triggered by cancer and the anti-tumoral activity of the immune system. Our understanding of how cervical cancer cells and their molecular networks adapt in response to the expression of Gal-7 remains limited.

Methods

Meta-analysis of Gal-7 expression was conducted in three cervical cancer cohort studies and TCGA. In silico prediction and bisulfite sequencing were performed to inquire epigenetic alterations. To study the effect of Gal-7 on cervical cancer, we ectopically re-expressed it in the HeLa and SiHa cervical cancer cell lines, and analyzed their transcriptome and SILAC-based proteome. We also examined the tumor and microenvironment host cell transcriptomes after xenotransplantation into immunocompromised mice. Differences between samples were assessed with the Kruskall-Wallis, Dunn’s Multiple Comparison and T tests. Kaplan–Meier and log-rank tests were used to determine overall survival.

Results

Gal-7 was constantly downregulated in our meta-analysis (p < 0.0001). Tumors with combined high Gal-7 and low galectin-1 expression (p = 0.0001) presented significantly better prognoses (p = 0.005). In silico and bisulfite sequencing assays showed de novo methylation in the Gal-7 promoter and first intron. Cells re-expressing Gal-7 showed a high apoptosis ratio (p < 0.05) and their xenografts displayed strong growth retardation (p < 0.001). Multiple gene modules and transcriptional regulators were modulated in response to Gal-7 reconstitution, both in cervical cancer cells and their microenvironments (FDR < 0.05 %). Most of these genes and modules were associated with tissue morphogenesis, metabolism, transport, chemokine activity, and immune response. These functional modules could exert the same effects in vitro and in vivo, even despite different compositions between HeLa and SiHa samples.

Conclusions

Gal-7 re-expression affects the regulation of molecular networks in cervical cancer that are involved in diverse cancer hallmarks, such as metabolism, growth control, invasion and evasion of apoptosis. The effect of Gal-7 extends to the microenvironment, where networks involved in its configuration and in immune surveillance are particularly affected.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2700-8) contains supplementary material, which is available to authorized users.