New blocking antibodies impede adhesion, migration and survival of ovarian cancer cells, highlighting MFGE8 as a potential therapeutic target of human ovarian carcinoma

Integrated transcriptome sequencing and weighted gene co-expression network analysis reveals key genes of papillary thyroid carcinomas

Objective

Papillary thyroid carcinoma (PTC) accounts for the majority of thyroid cancers and has a high recurrence rate. We aimed to screen key genes involved in PTC to provide novel insights into the mechanisms of PTC.

Methods

Seven microarray datasets of PTC were downloaded from gene expression omnibus database. Differentially expressed genes (DEGs) between PTC and normal samples were screened in the merged dataset. Then, protein-protein interaction (PPIs) functional modules analysis and weighted gene co-expression network analysis (WGCNA) were utilized to identify PTC-associated key genes. The identified key genes were then characterized from various aspects, including gene set enrichment analysis (GSEA) and the associations with immune infiltration, methylation levels and prognosis.

Results

A large numbers of DEGs were identified, and these DEGs are involved in several cancer pathways. Nine key genes (including down-regulated genes GNA14, AVPR1A, and WFS1, and up-regulated genes LAMB3, PLAU, MET, MFGE8, PRSS23, and SERPINA1) were identified. Patients in the AVPR1A and GNA14 high expression groups had better disease-free survival (DFS) than those in the low expression group. Key genes were mainly involved in P53 pathway, estrogen response, apoptosis, glycolysis, NOTCH signaling, epithelial mesenchymal transition, WNT_beta catenin signaling, and inflammatory response. The expression of key genes was associated with immune cell infiltration and corresponding methylation levels. The verification results of key gene proteins and mRNA expression levels using external validation datasets were consistent with our expectations, implying the involvements of key genes in PTC.

Conclusion

The key genes may serve as potential therapeutic targets for PTC. This study provides novel insights into the mechanisms underlying PTC development.

Potent CTLs can be induced against tumor cells in an environment of lower levels of systemic MFG-E8

The direction and magnitude of immune responses are critically affected when dead cells are disposed of. Milk fat globule-epidermal growth factor-factor 8 (MFG-E8) promotes the engulfment of apoptotic normal and cancerous cells without inducing inflammation. We have previously reported that a certain proportion of the cancer cells express abundant MFG-E8, and that such expression is associated with the shorter survival of patients with esophageal cancer who had received chemotherapy before surgery. However, the influence of tumor-derived and systemically existing MFG-E8 on antitumor immune responses has not yet been fully investigated. Herein, we showed that CTL-dependent antitumor immune responses were observed in mice with no or decreased levels of systemic MFG-E8, and that such responses were enhanced further with the administration of anti-PD-1 antibody. In mice with decreased levels of systemic MFG-E8, the dominance of regulatory T cells in tumor-infiltrating lymphocytes was inverted to CD8+ T cell dominance. MFG-E8 expression by tumor cells appears to affect antitumor immune responses only when the level of systemic MFG-E8 is lower than the physiological status. We have also demonstrated in the clinical setting that lower levels of plasma MFG-E8, but not MFG-E8 expression in tumor cells, before the treatment was associated with objective responses to anti-PD-1 therapy in patients with non-small cell lung cancer. These results suggest that systemic MFG-E8 plays a critical role during the immunological initiation process of antigen-presenting cells to increase tumor-specific CTLs. Regulation of the systemic level of MFG-E8 might induce efficient antitumor immune responses and enhance the potency of anti-PD-1 therapy.

Lactadherin immunoblockade in small extracellular vesicles inhibits sEV-mediated increase of pro-metastatic capacities

BACKGROUND

Tumor-derived small extracellular vesicles (sEVs) can promote tumorigenic and metastatic capacities in less aggressive recipient cells mainly through the biomolecules in their cargo. However, despite recent advances, the specific molecules orchestrating these changes are not completely defined. Lactadherin is a secreted glycoprotein typically found in the milk fat globule membrane. Its overexpression has been associated with increased tumorigenesis and metastasis in breast cancer (BC) and other tumors. However, neither its presence in sEVs secreted by BC cells, nor its role in sEV-mediated intercellular communication have been described. The present study focused on the role of lactadherin-containing sEVs from metastatic MDA-MB-231 triple-negative BC (TNBC) cells (sEV-MDA231) in the promotion of pro-metastatic capacities in non-tumorigenic and non-metastatic recipient cells in vitro, as well as their pro-metastatic role in a murine model of peritoneal carcinomatosis.

RESULTS

We show that lactadherin is present in sEVs secreted by BC cells and it is higher in sEV-MDA231 compared with the other BC cell-secreted sEVs measured through ELISA. Incubation of non-metastatic recipient cells with sEV-MDA231 increases their migration and, to some extent, their tumoroid formation capacity but not their anchorage-independent growth. Remarkably, lactadherin blockade in sEV-MDA231 results in a significant decrease of those sEV-mediated changes in vitro. Similarly, intraperitoneally treatment of mice with MDA-MB-231 BC cells and sEV-MDA231 greatly increase the formation of malignant ascites and tumor micronodules, effects that were significantly inhibited when lactadherin was previously blocked in those sEV-MDA231.

CONCLUSIONS

As to our knowledge, our study provides the first evidence on the role of lactadherin in metastatic BC cell-secreted sEVs as promoter of: (i) metastatic capacities in less aggressive recipient cells, and ii) the formation of malignant ascites and metastatic tumor nodules. These results increase our understanding on the role of lactadherin in sEVs as promoter of metastatic capacities which can be used as a therapeutic option for BC and other malignancies.

Effects of MFG-E8 expression on the biological characteristics of ovarian cancer cells via the AKT/mTOR/S6K signalling pathway

In this study, we assessed the effects of MFG-E8 on the biological characteristics of ovarian cancer cells and explored the underlying mechanisms. Human ovarian cancer SKOV3 cells were transfected with MFG-E8 siRNA or NC siRNA. CCK-8, cell adhesion, scratch-wound, and Transwell assays were used to detect changes in cell metastatic processes. Effects of MFG-E8 silencing on the proteins involved in AKT/mTOR/S6K signalling pathway were assessed using qRT-PCR and Western blotting. Transient silencing of MFG-E8 in SKOV3 cells decreased cell proliferation and downregulated the expression of CDK4, cyclin D1, and caspase-3 proteins. Cell adhesion, migration, and invasion were also suppressed. p-AKT, p-mTORC1, and p-p70S6K levels decreased following MFG-E8 knockdown. Hence, MFG-E8 enhances carcinogenesis and affects the AKT/mTOR/S6K signalling pathway in ovarian cancer cells. In conclusion, our results suggested that MFG-E8 could promote ovarian cancer via AKT/mTOR/S6K signalling pathway which improved our understanding of the molecular mechanisms involved in ovarian cancer.IMPACT STATEMENTWhat is already known on this subject? Milk fat globule-epidermal growth factor 8 (MFG-E8) is expressed in several types of cancers such as oesophageal, breast, and liver. However, the mechanism of MFG-E8 involving in EOC remains unknown. We previously found that MFG-E8 expression was related to pathological staging, tissue differentiation, platinum sensitivity, ascites state, and other clinicopathological characteristics.What the results of this study add? Due to a series of in vitro studies, we confirmed that MFG-E8 is involved in the process of proliferation, invasion and metastasis. Our results show that silencing MFG-E8 can significantly inhibit the expression of cyclin D1 and CDK4 in EOC SKOV3 cells. MFG-E8 enhances carcinogenesis and affects the AKT/mTOR/S6K signaling pathway in ovarian cancer.What the implications are of these findings for clinical practice and/or further research? Taken together, our findings suggest that MFG-E8 may be an oncogene in EOC and provide new insights into the mechanism of MFG-E8 in the progression of EOC.

The role of lncRNA SNHG14 in gastric cancer: enhancing tumor cell proliferation and migration, and mechanisms of CDH2 expression

LncRNAs are a class of non-coding RNAs that play an important role in regulating gene expression. However, their specific molecular mechanisms in gastric carcinogenesis and metastasis need further exploration. TCGA data showed that the expression of MFGE8, which was closely related to survival, was significantly positively correlated with lncRNA SNHG14. And moreover, the results of high-throughput sequencing and qRT-PCR showed that lncRNA SNHG14 was significantly elevated in gastric cancer. Further, in vitro functional realization showed that lncRNA SNHG14 overexpression significantly increased gastric cancer's proliferation, invasion and migration. Animal experiments also showed that lncRNA SNHG14 overexpression promoted tumorigenesis and metastasis in vivo. Mechanistically, MFGE8 activates the expression of lncRNA SNHG14, which activates the cellular EMT by stabilizing CDH2. Our study suggests that lncRNA SNHG14 could be a potential target for gastric cancer therapy.

Human astrocytes and microglia show augmented ingestion of synapses in Alzheimer's disease via MFG-E8

Synapse loss correlates with cognitive decline in Alzheimer's disease (AD). Data from mouse models suggests microglia are important for synapse degeneration, but direct human evidence for any glial involvement in synapse removal in human AD remains to be established. Here we observe astrocytes and microglia from human brains contain greater amounts of synaptic protein in AD compared with non-disease controls, and that proximity to amyloid-β plaques and the APOE4 risk gene exacerbate this effect. In culture, mouse and human astrocytes and primary mouse and human microglia phagocytose AD patient-derived synapses more than synapses from controls. Inhibiting interactions of MFG-E8 rescues the elevated engulfment of AD synapses by astrocytes and microglia without affecting control synapse uptake. Thus, AD promotes increased synapse ingestion by human glial cells at least in part via an MFG-E8 opsonophagocytic mechanism with potential for targeted therapeutic manipulation.

Comparative analysis of the occupancy of Histone H3 Lysine 4 methylation in the cells treated with TGFβ and Interferonγ

In this current study, we have compared our H3K4me3 Chip-Sequencing data in PC3 cells in response to 6h and 24h TGFβ stimulation with the IFNγ stimulated/unstimulated HeLa S3 cells Since both TGFβ and IFNγ play an essential role in tumorigenesis both as a tumor promoter and tumor suppressor and known to antagonize each other's signalling, it would be of utmost importance to find out the regions undergoing histone modification changes in response to TGFβ and IFNγ and compare them to explore the genes common to both as well as the specific for each ligand. Our study has compared the genes showing H3K4me3 occupancy in response to both TGFβ and IFNγ. Several genes were found to be shared between the TGFβ and IFNγ. DAVID Functional enrichment analysis in the TGFβ and IFNγ dataset revealed association of genes with different biological processes such as miRNA-mediated gene silencing, positive regulation of ERK cascade, hypoxia-induced apoptosis repression, translational regulation and molecular functions such as TGFβR activity, GPCR activity, TGFβ binding activity. Further analysis of these genes can reveal fascinating insights into epigenetic regulation by growth factor stimulation.

Gastric cancer cell-derived extracellular vesicles disrupt endothelial integrity and promote metastasis

The endothelium is the critical barrier that controls transendothelial communications. Blood vessels in cancer tissue are poorly developed and highly permeable. However, it is poorly understood how circulating cancer cells released through these "leaky" vessels break the intact vasculature of remote organs to metastasize. We investigated the roles of cancer cell-derived extracellular vesicles (CEVs) in regulating cancer metastasis by analyzing samples from gastric cancer patients, performing in vitro experiments, and studying mouse models. We made several novel observations. First, the rate of metastasis was closely associated with plasma levels of CEVs in patients with gastric cancer. Second, cultured endothelial cells endocytosed CEVs, resulting in cytoskeletal rearrangement, low expression of the junction proteins cadherin and CD31, and forming large intercellular gaps to allow the transendothelial migration of cancer cells. The dynamin inhibitor Dynasore prevented these CEV-induced changes of endothelial cells by blocking CEVs endocytosis. Third, CEVs disrupted the endothelial barrier of cancer-bearing mice to promote cancer metastasis. Finally, lactadherin promoted the clearance of circulating CEVs to reduce metastasis. These results demonstrate the essential role of CEVs in promoting the metastasis of gastric cancer.

High Levels of MFG-E8 Confer a Good Prognosis in Prostate and Renal Cancer Patients

Simple Summary

In the present study, we analyzed the distribution and prognostic impact of milk fat globule-epidermal growth factor-8 (MFG-E8) protein expression in patients with prostate and renal cancers. Our data highlighted MFG-E8 expression by tumor cells in the epithelium. Our results also showed that low levels of MFG-E8 in prostate and renal cancers were associated with worse clinical outcomes. Furthermore, higher numbers of CD206⁺ cells were found in the peripheral regions of renal clear cell carcinoma that expressed lower MFG-E8 levels. Globally, our results suggest that MFG-E8 expression could potentially be used as a prognostic marker in prostate and renal cancers.

Abstract

Milk fat globule-epidermal growth factor-8 (MFG-E8) is a glycoprotein secreted by different cell types, including apoptotic cells and activated macrophages. MFG-E8 is highly expressed in a variety of cancers and is classically associated with tumor growth and poor patient prognosis through reprogramming of macrophages into the pro-tumoral/pro-angiogenic M2 phenotype. To date, correlations between levels of MFG-E8 and patient survival in prostate and renal cancers remain unclear. Here, we quantified MFG-E8 and CD68/CD206 expression by immunofluorescence staining in tissue microarrays constructed from renal (n = 190) and prostate (n = 274) cancer patient specimens. Percentages of MFG-E8-positive surface area were assessed in each patient core and Kaplan–Meier analyses were performed accordingly. We found that MFG-E8 was expressed more abundantly in malignant regions of prostate tissue and papillary renal cell carcinoma but was also increased in the normal adjacent regions in clear cell renal carcinoma. In addition, M2 tumor-associated macrophage staining was increased in the normal adjacent tissues compared to the malignant areas in renal cancer patients. Overall, high tissue expression of MFG-E8 was associated with less disease progression and better survival in prostate and renal cancer patients. Our observations provide new insights into tumoral MFG-E8 content and macrophage reprogramming in cancer.

Lactadherin: From a Well-Known Breast Tumor Marker to a Possible Player in Extracellular Vesicle-Mediated Cancer Progression

Lactadherin is a secreted glycoprotein associated with the milk fat globule membrane, which is highly present in the blood and in the mammary tissue of lactating women. Several biological functions have been associated with this protein, mainly attributable to its immunomodulatory role promoting phagocyte-mediated clearance of apoptotic cells. It has been shown that lactadherin also plays important roles in cell adhesion, the promotion of angiogenesis, and tissue regeneration. On the other hand, this protein has been used as a marker of breast cancer and tumor progression. Recently, high levels of lactadherin has been associated with poor prognosis and decreased survival, not only in breast cancer, but also in melanoma, ovarian, colorectal, and other types of cancer. Although the mechanisms responsible for the tumor-promoting effects attributed to lactadherin have not been fully elucidated, a growing body of literature indicates that lactadherin could be a promising therapeutic target and/or biomarker for breast and other tumors. Moreover, recent studies have shown its presence in extracellular vesicles derived from cancer cell lines and cancer patients, which was associated with cancer aggressiveness and worse prognosis. Thus, this review will focus on the link between lactadherin and cancer development and progression, its possible use as a cancer biomarker and/or therapeutic target, concluding with a possible role of this protein in cellular communication mediated by extracellular vesicles.

A Novel Therapeutic Strategy Targeting the Mesenchymal Phenotype of Malignant Pleural Mesothelioma By Suppressing LSD1

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor that has a low overall survival; however, no significant treatment advances have been made in the past 15 years. Large-scale molecular studies have identified a poor prognostic subset of MPM linked to the epithelial-mesenchymal transition (EMT) that may contribute toward resistance to chemotherapy, suggesting that EMT could be targeted to treat patients with MPM. Previously, we reported that histone modifiers regulating EMT could be therapeutic targets; therefore, in this study, we investigated whether targeting lysine-specific demethylase 1 (LSD1/KDM1), a histone-modifying enzyme responsible for demethylating histone H3 lysine 4 and lysine 9, could represent a novel therapeutic strategy for MPM. We suppressed LSD1 and investigated the EMT phenotype using EMT marker expression and wound-healing assay; and chemosensitivity using apoptosis assay. We found that suppressing LSD1 induces an epithelial phenotype in sarcomatoid MPM cells, while attenuating the mesenchymal phenotype sensitized MPM cells to cisplatin-induced apoptosis. Subsequent genome-wide identification, comprehensive microarray analysis, and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) to assess genome-wide changes in chromatin accessibility suggested that LSD1 directly regulates milk fat globulin protein E8 (MFGE8), an integrin ligand that is involved in the FAK pathway. Furthermore, we found that LSD1 regulates the mesenchymal phenotype and apoptosis by activating the FAK-AKT-GSK3β pathway via a positive feedback loop involving MFGE8 and Snail expression, thereby leading to cisplatin resistance. IMPLICATIONS: This study suggests that LSD1 regulates the mesenchymal phenotype and apoptosis, and that LSD1 inhibitors could be combined with the cisplatin as a novel therapy for patients with MPM.

TGF-β Increases MFGE8 Production in Myeloid-Derived Suppressor Cells to Promote B16F10 Melanoma Metastasis

There is growing evidence that myeloid-derived suppressor cells (MDSCs) are directly involved in all stages leading to metastasis. Many mechanisms for this effect have been proposed, but mechanisms of coregulation between tumor cells and MDSCs remain poorly understood. In this study, we demonstrate that MDSCs are a source of milk fat globule-epidermal growth factor (EGF) factor 8 (MFGE8), which is known to be involved in tumor metastasis. Interestingly, TGF-β, an abundant cytokine in the tumor microenvironment (TME), increased MFGE8 production by MDSCs. In addition, co-culturing MDSCs with B16F10 melanoma cells increased B16F10 cell migration, while MFGE8 neutralization decreased their migration. Taken together, these findings suggest that MFGE8 is an important effector molecule through which MDSCs promote tumor metastasis, and the TME positively regulates MFGE8 production by MDSCs through TGF-β.

Transcriptome Analysis Reveals MFGE8-HAPLN3 Fusion as a Novel Biomarker in Triple-Negative Breast Cancer

Background

Triple-negative breast cancer (TNBC) is a highly aggressive cancer with poor prognosis. The lack of effective targeted therapies for TNBC remains a profound clinical challenge. Fusion transcripts play critical roles in carcinogenesis and serve as valuable diagnostic and therapeutic targets in cancer. The present study aimed to identify novel fusion transcripts in TNBC.

Methods

We analyzed the RNA sequencing data of 360 TNBC samples to identify and filter fusion candidates through SOAPfuse and ChimeraScan analysis. The characteristics, including recurrence, fusion type, chromosomal localization, TNBC subgroup distribution, and clinicopathological correlations, were analyzed in all candidates. Furthermore, we selected the promising fusion transcript and predicted its fusion type and protein coding capacity.

Results

Using the RNA sequencing data, we identified 189 fusion transcripts in TNBC, among which 22 were recurrent fusions. Compared to para-tumor tissues, TNBC tumor tissues accumulated more fusion events, especially in high-grade tumors. Interestingly, these events were enriched at specific chromosomal loci, and the distribution pattern varied in different TNBC subtypes. The vast majority of fusion partners were discovered on chromosomes 1p, 11q, 19p, and 19q. Besides, fusion events mainly clustered on chromosome 11 in the immunomodulatory subtype and chromosome 19 in the luminal androgen receptor subtype of TNBC. Considering the tumor specificity and frameshift mutation, we selected MFGE8-HAPLN3 as a novel biomarker and further validated it in TNBC samples using PCR and Sanger sequencing. Further, we successfully identified three types of MFGE8-HAPLN3 (E6-E2, E5-E3, and E6-E3) and predicted the ORF of E6-E2, which could encode a protein of 712 amino acids, suggesting its critical role in TNBC.

Conclusions

Improved bioinformatic stratification and comprehensive analysis identified the fusion transcript MFGE8-HAPLN3 as a novel biomarker with promising clinical application in the future.

Autoregulation of insulin receptor signaling through MFGE8 and the αvβ5 integrin

The role of integrins, in particular αv integrins, in regulating insulin resistance is incompletely understood. We have previously shown that the αvβ5 integrin ligand milk fat globule epidermal growth factor like 8 (MFGE8) regulates cellular uptake of fatty acids. In this work, we evaluated the impact of MFGE8 on glucose homeostasis. We show that acute blockade of the MFGE8/β5 pathway enhances while acute augmentation dampens insulin-stimulated glucose uptake. Moreover, we find that insulin itself induces cell-surface enrichment of MFGE8 in skeletal muscle, which then promotes interaction between the αvβ5 integrin and the insulin receptor leading to dampening of skeletal-muscle insulin receptor signaling. Blockade of the MFGE8/β5 pathway also enhances hepatic insulin sensitivity. Our work identifies an autoregulatory mechanism by which insulin-stimulated signaling through its cognate receptor is terminated through up-regulation of MFGE8 and its consequent interaction with the αvβ5 integrin, thereby establishing a pathway that can potentially be targeted to improve insulin sensitivity.

Desmoplastic Crosstalk in Pancreatic Ductal Adenocarcinoma Is Reflected by Different Responses of Panc-1, MIAPaCa-2, PaTu-8902, and CAPAN-2 Cell Lines to Cancer-associated/Normal Fibroblasts

BACKGROUND/AIM

Pancreatic ductal adenocarcinoma (PDAC) still represents one of the most aggressive cancers. Understanding of the epithelial-mesenchymal crosstalk as a crucial part of the tumor microenvironment should pave the way for therapies to improve patient survival rates. Well-established cell lines present a useful and reproducible model to study PDAC biology. However, the tumor-stromal interactions between cancer cells and cancer-associated fibroblasts (CAFs) are still poorly understood.

MATERIALS AND METHODS

We studied interactions between four PDAC cell lines (Panc-1, CAPAN-2, MIAPaCa-2, and PaTu-8902) and conditioned media derived from primary cultures of normal fibroblasts/PDAC-derived CAFs (PANFs).

RESULTS

When the tested PDAC cell lines were stimulated by PANF-derived conditioned media, the most aggressive behavior was acquired by the Panc-1 cell line (increased number and size of colonies, remaining expression of vimentin and keratin 8 as well as increase of epithelial-to-mesenchymal polarization markers), whereas PaTu-8902 cells were rather inhibited. Of note, administration of the conditioned media to MIAPaCa-2 cells resulted in an inverse effect on the size and number of colonies, whereas CAPAN-2 cells were rather stimulated. To explain the heterogeneous pattern of the observed PDAC crosstalk at the in vitro level, we further compared the phenotype of primary cultures of cells derived from ascitic fluid with that of the tested PDAC cell lines, analyzed tumor samples of PDAC patients, and performed gene expression profiling of PANFs. Immuno-cyto/histo-chemical analysis found specific phenotype differences within the group of examined patients and tested PDAC cell lines, whereas the genomic approach in PANFs found the key molecules (IL6, IL8, MFGE8 and periostin) that may contribute to the cancer aggressive behavior.

CONCLUSION

The desmoplastic patient-specific regulation of cancer cells by CAFs (also demonstrated by the heterogeneous response of PDAC cell lines to fibroblasts) precludes simple targeting and development of an effective treatment strategy and rather requires establishment of an individualized tumor-specific treatment protocol.

Identification of key genes of papillary thyroid carcinoma by integrated bioinformatics analysis

BACKGROUND

Papillary thyroid carcinoma (PTC) is one of the fastest-growing malignant tumor types of thyroid cancer. Therefore, identifying the interaction of genes in PTC is crucial for elucidating its pathogenesis and finding more specific molecular biomarkers.

METHODS

Four pairs of PTC tissues and adjacent tissues were sequenced using RNA-Seq, and 3745 differentially expressed genes were screened (P<0.05, |logFC|>1). The enrichment analysis indicated that the vast majority of differentially expressed genes (DEGs) may play a positive role in the development of cancer. Then, the significant modules were analyzed using Cytoscape software in the protein-protein interaction network. Survival analysis, TNM analysis, and immune infiltration analysis of key genes were analyzed. And the expression of ADORA1, APOE, and LPAR5 genes were verified by qPCR in PTC compared with matching adjacent tissues.

RESULTS

Twenty-five genes were identified as hub genes with nodes greater than 10. The expression of 25 genes were verified by the GEPIA database, and the overall survival and disease-free survival analyses were conducted with Kaplan-Meier plotter. We found only three genes were confirmed with our validation and were statistically significant in PTC, namely ADORA1, APOE, and LPAR5. Further analysis found that the mRNA levels and methylation degree of these three genes were significantly correlated with the TNM staging of PTC. And these three genes were related to PTC immune infiltration. Verification of the expression of these three genes by RT-qPCR and Western blot further confirmed the reliability of our results.

CONCLUSION

Our study identified three genes that may play key regulatory roles in the development, metastasis, and immune infiltration of papillary thyroid carcinoma.

Clinical significance of CD8+ and FoxP3+ tumor-infiltrating lymphocytes and MFG-E8 expression in lower rectal cancer with preoperative chemoradiotherapy

Preoperative chemoradiotherapy (CRT) for rectal cancer contributes to tumor down-staging and decreases locoregional recurrence. However, each patient shows a significantly different response to CRT. Therefore, the identification of predictive factors to CRT response would be beneficial to avoid unnecessary treatment. Cancer immunity in patients has been suggested to play an important role in the eradication of the tumor by CRT. In the present study, the utility of CD8⁺ and forkhead box P3 (FoxP3)⁺ tumor-infiltrating lymphocytes (TILs) and the expression of a novel immuno-regulatory factor, lactadherin (MFG-E8), in predicting CRT effectiveness in patients with rectal cancer was examined. A total of 61 patients with rectal cancer, who underwent curative resection following CRT were included in the study. The numbers of CD8⁺ and FoxP3⁺ TILs in a biopsy taken before CRT and MFG-E8 expression level in the specimens obtained at the time of the surgery after CRT were examined using immunohistochemical staining, and their association with clinicopathological characteristics, including patient survival, was determined. The tumors with more CD8⁺ TILs in the biopsy samples before CRT showed a significantly more favorable CRT response. The patients with tumors and a higher number of CD8⁺ TILs before CRT also exhibited significantly longer disease-free and overall survival times. Higher MFG-E8 expression level in post-CRT specimens was significantly associated with favorable CRT response; however, no significant association was found with any other clinicopathological characteristics, including survival time. The number of CD8⁺ TILs before CRT was a valuable predictor for CRT response and was associated with favorable prognosis in patients with lower rectal cancer and who were treated with CRT. High MFG-E8 expression level after CRT was also associated with a favorable CRT response.

Roles and mechanisms of MFG-E8 in vascular aging-related diseases

The aging of the vasculature plays a crucial role in the pathological progression of various vascular aging-related diseases. As endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are essential parts in the inner and medial layers of vessel wall, respectively, the structural and functional alterations of ECs and VSMCs are the major causes of vascular aging. Milk fat globule-epidermal growth factor 8 (MFG-E8) is a multifunctional glycoprotein which exerts a regulatory role in the intercellular interactions involved in a variety of biological and pathological processes. Emerging evidence suggests that MFG-E8 is a novel and outstanding modulator for vascular aging via targeting at ECs and VSMCs. In this review, we will summarise the cumulative roles and mechanisms of MFG-E8 in vascular aging and vascular aging-related diseases with special emphasis on the functions of ECs and VSMCs. In addition, we also aim to focus on the promising diagnostic function as a biomarker and the potential therapeutic application of MFG-E8 in vascular aging and the clinical evaluation of vascular aging-related diseases.

The expression levels and clinical significance of MFG-E8 and CD133 in epithelial ovarian cancer

The aim of our study was to test whether there is an association between high expression of milk fat globule EGF factor 8 (MFG-E8) and CD133 presence or clinical outcomes of patients with epithelial ovarian cancer (EOC). MFG-E8 and CD133 expression levels were analyzed by immunohistochemistry in 88 EOC tumor specimens. High expression of MFG-E8 directly and significantly correlated with the presence of CD133 immunostaining (R = 0.353, p=.001), whereas immunostaining of MFG-E8 and CD133 significantly correlated with FIGO stage, tumor grade, debulking status, the dualistic model, ascites status, and nonresponse to chemotherapy (p<.05). It was also found that high expression of MFG-E8 and CD133 presence is a potent predictor of poor clinical outcomes among patients with EOC. Our study is the first to show that high expression of MFG-E8 in EOCs positively correlates with CD133 presence. Further research on MFG-E8 in EOC is needed to determine whether MFG-E8 is a new tumor marker of ovarian cancer and a new target for anticancer therapy as well as whether it can interact with cancer stem cell inhibitors for the treatment of refractory tumors.

Exosomes released upon mitochondrial ASncmtRNA knockdown reduce tumorigenic properties of malignant breast cancer cells

During intercellular communication, cells release extracellular vesicles such as exosomes, which contain proteins, ncRNAs and mRNAs that can influence proliferation and/or trigger apoptosis in recipient cells, and have been proposed to play an essential role in promoting invasion of tumor cells and in the preparation of metastatic niches. Our group proposed the antisense non-coding mitochondrial RNA (ASncmtRNA) as a new target for cancer therapy. ASncmtRNA knockdown using an antisense oligonucleotide (ASO-1537S) causes massive death of tumor cells but not normal cells and strongly reduces metastasis in mice. In this work, we report that exosomes derived from ASO-1537S-treated MDA-MB-231 breast cancer cells (Exo-1537S) inhibits tumorigenesis of recipient cells, in contrast to exosomes derived from control-ASO-treated cells (Exo-C) which, in contrast, enhance these properties. Furthermore, an in vivo murine peritoneal carcinomatosis model showed that Exo-1537S injection reduced tumorigenicity compared to controls. Proteomic analysis revealed the presence of Lactadherin and VE-Cadherin in exosomes derived from untreated cells (Exo-WT) and Exo-C but not in Exo-1537S, and the latter displayed enrichment of proteasomal subunits. These results suggest a role for these proteins in modulation of tumorigenic properties of exosome-recipient cells. Our results shed light on the mechanisms through which ASncmtRNA knockdown affects the preparation of breast cancer metastatic niches in a peritoneal carcinomatosis model.

Application of Impedance-Based Techniques in Hepatology Research

There are a variety of end-point assays and techniques available to monitor hepatic cell cultures and study toxicity within in vitro models. These commonly focus on one aspect of cell metabolism and are often destructive to cells. Impedance-based cellular assays (IBCAs) assess biological functions of cell populations in real-time by measuring electrical impedance, which is the resistance to alternating current caused by the dielectric properties of proliferating of cells. While the uses of IBCA have been widely reported for a number of tissues, specific uses in the study of hepatic cell cultures have not been reported to date. IBCA monitors cellular behaviour throughout experimentation non-invasively without labelling or damage to cell cultures. The data extrapolated from IBCA can be correlated to biological events happening within the cell and therefore may inform drug toxicity studies or other applications within hepatic research. Because tight junctions comprise the blood/biliary barrier in hepatocytes, there are major consequences when these junctions are disrupted, as many pathologies centre around the bile canaliculi and flow of bile out of the liver. The application of IBCA in hepatology provides a unique opportunity to assess cellular polarity and patency of tight junctions, vital to maintaining normal hepatic function. Here, we describe how IBCAs have been applied to measuring the effect of viral infection, drug toxicity /IC50, cholangiopathies, cancer metastasis and monitoring of the gut-liver axis. We also highlight key areas of research where IBCAs could be used in future applications within the field of hepatology.

The significance of tumor cells-derived MFG-E8 in tumor growth of angiosarcoma

BACKGROUND

Previous studies have indicated that MFG-E8 enhances tumor cell survival, invasion and angiogenesis. However, the role of MFG-E8 in angiosarcoma (AS) has not been clarified.

OBJECTIVE

Objective was to elucidate the mechanism of the regulation by MFG-E8 in AS and the association between MFG-E8 and clinicopathological features of AS.

METHODS

The effects of the depletion of MFG-E8 by siRNA on tube formation, migration and proliferation in murine AS cells were examined. The effect of administration of anti-MFG-E8 antibody (Ab) on tumor growth of AS in mice was examined. The associations of MFG-E8 expression and clinicopathological features of human AS were assessed.

RESULTS

The expressions of MFG-E8 in murine and human AS cells were significantly higher than those in melanoma cells, macrophages and endothelial cells. Depletion of MFG-E8 in murine AS cells by siRNA significantly inhibited the formation of capillary-like structures and migration, but not proliferation. Administration of anti-MFG-E8 Ab significantly inhibited tumor growth and decreased the number of tumor-associated macrophages (TAMs) in AS tumors. Tumor size and the number of TAMs in human AS with high expression of MFG-E8 were significantly increased compared to those of AS with low expression of MFG-E8. Progression-free survival and overall survival time of the patients of AS with high expression of MFG-E8 were significantly shorter than those of AS with low expression of MFG-E8.

CONCLUSIONS

AS-derived MFG-E8 might enhance tumor growth via angiogenesis and the induction of TAMs in autocrine/paracrine manner, and administration of anti-MFG-E8 Ab could be a therapeutic potential for AS.

Irradiation increases the immunogenicity of lung cancer cells and irradiation-based tumor cell vaccine elicits tumor-specific T cell responses in vivo

Background: During the past decades, great efforts have been built to develop lung cancer vaccines. Whole tumor cell lysate (TCL) are ideal sources of antigens for cancer vaccine design, which however have limited efficacy due to insufficient immunogenicity. Recently, radiotherapy has been closely related to immunotherapy. Numerous studies have demonstrated the regulatory effect of irradiation (IR) on tumor immune response. Purpose: To explore the immunogenicity modulation effect of IR on lung cancer cells. Methods: RNA-sequence and qPCR assay was used to evaluate the change of tumor antigens expression after repeated X rays radiation on A549 cells. Vaccine based on TCL of irradiated Lewis lung cancer cells (IR-LLC) was established; therapeutic effect of TCL (IR-LLC) was examined in xenografted tumor model of mice. Flow cytometry was conducted to evaluate the rate of immune cells in spleen; ELISA was used to detect the level of cytokines in plasma. Immunohistochemistry was performed to evaluate the infiltrations of T-cell in tumor tissues; TIMER analysis was used to explore the correlations between tumor antigen expressions and the abundances of immune infiltrates. Results: IR upregulated the expression of tumor antigens in A549 cells. Compared to the control group and unirradiated tumor cell vaccine, TCL(IR-LLC) had a significantly stronger anti-tumor effect in mice bearing with LLC xenografts. TCL(IR-LLC) significantly increased matured DCs and total CD4+ T cells but downregulated Tregs and PD-1+ CD8+ T cells in mice spleen; TCL(IR-LLC) vaccine upregulated the level of IFN-γ and IL-4 while decreased IL-10 in serum; increased infiltrations of CD4+ T-cells and CD8+ T-cells were observed in the tumor issues of mice immunized with TCL(IR-LLC). Tumor antigens including FN1, MFGE8, MMP2, MYL9 may contribute to the enhanced T-cell response. Conclusion: This study confirmed the immunogenicity modulation effect of IR in NSCLC cells, indicating IR might be an effective strategy to enhance the anti-tumor immunity of cancer cell vaccine.

Mining Featured Biomarkers Linked with Epithelial Ovarian CancerBased on Bioinformatics

Epithelial ovarian cancer (EOC) is the18th most common cancer worldwide and the 8th most common in women. The aim of this study was to diagnose the potential importance of, as well as novel genes linked with, EOC and to provide valid biological information for further research. The gene expression profiles of E-MTAB-3706 which contained four high-grade ovarian epithelial cancer samples, four normal fallopian tube samples and four normal ovarian epithelium samples were downloaded from the ArrayExpress database. Pathway enrichment and Gene Ontology (GO) enrichment analysis of differentially expressed genes (DEGs) were performed, and protein-protein interaction (PPI) network, microRNA-target gene regulatory network and TFs (transcription factors) -target gene regulatory network for up- and down-regulated were analyzed using Cytoscape. In total, 552 DEGs were found, including 276 up-regulated and 276 down-regulated DEGs. Pathway enrichment analysis demonstrated that most DEGs were significantly enriched in chemical carcinogenesis, urea cycle, cell adhesion molecules and creatine biosynthesis. GO enrichment analysis showed that most DEGs were significantly enriched in translation, nucleosome, extracellular matrix organization and extracellular matrix. From protein-protein interaction network (PPI) analysis, modules, microRNA-target gene regulatory network and TFs-target gene regulatory network for up- and down-regulated, and the top hub genes such as E2F4, SRPK2, A2M, CDH1, MAP1LC3A, UCHL1, HLA-C (major histocompatibility complex, class I, C), VAT1, ECM1 and SNRPN (small nuclear ribonucleoprotein polypeptide N) were associated in pathogenesis of EOC. The high expression levels of the hub genes such as CEBPD (CCAAT enhancer binding protein delta) and MID2 in stages 3 and 4 were validated in the TCGA (The Cancer Genome Atlas) database. CEBPD andMID2 were associated with the worst overall survival rates in EOC. In conclusion, the current study diagnosed DEGs between normal and EOC samples, which could improve our understanding of the molecular mechanisms in the progression of EOC. These new key biomarkers might be used as therapeutic targets for EOC.

Immunoregulatory influence of abundant MFG-E8 expression by esophageal cancer treated with chemotherapy

Milk fat globule‐epidermal growth factor factor 8 (MFG‐E8) is secreted from macrophages and is known to induce immunological tolerance mediated by regulatory T cells. However, the roles of the MFG‐E8 that is expressed by cancer cells have not yet been fully examined. Expression of MFG‐E8 was examined using immunohistochemistry in surgical samples from 134 patients with esophageal squamous cell carcinoma. The relationships between MFG‐E8 expression levels and clinicopathological factors, including tumor‐infiltrating lymphocytes, were evaluated. High MFG‐E8 expression was observed in 23.9% of the patients. The patients with tumors highly expressing MFG‐E8 had a significantly higher percentage of neoadjuvant chemotherapy (NAC) history (P < .0001) and shorter relapse‐free survival (P = 0.012) and overall survival (OS; P = .0047). On subgroup analysis, according to NAC history, patients with high MFG‐E8 expression had significantly shorter relapse‐free survival (P = .027) and OS (P = .0039) only when they had been treated with NAC. Furthermore, tumors with high MFG‐E8 expression had a significantly lower ratio of CD8⁺ T cells/regulatory T cells in tumor‐infiltrating lymphocytes (P = .042) only in the patients treated with NAC, and those with a lower ratio had a shorter OS (P = .026). High MFG‐E8 expression was also found to be an independent prognostic factor in multivariate analysis. The abundant MFG‐E8 expression in esophageal squamous cell carcinoma might have a negative influence on the long‐term survival of patients after chemotherapy by affecting T‐cell regulation in the tumor microenvironment.

Extracellular Vesicles Containing IL-4 Modulate Neuroinflammation in a Mouse Model of Multiple Sclerosis

Extracellular vesicles (EVs) play a major role in cell-to-cell communication in physiological and pathological conditions, and their manipulation may represent a promising therapeutic strategy. Microglia, the parenchymal mononuclear phagocytes of the brain, modulate neighboring cells also through the release of EVs. The production of custom EVs filled with desired molecules, possibly targeted to make their uptake cell specific, and their administration in biological fluids may represent a valid approach for drug delivery. We engineered a murine microglia cell line, BV-2, to release EVs overexpressing the endogenous "eat me" signal Lactadherin (Mfg-e8) on the surface to target phagocytes and containing the anti-inflammatory cytokine IL-4. A single injection of 10⁷ IL-4⁺Mfg-e8⁺ EVs into the cisterna magna modulated established neuroinflammation and significantly reduced clinical signs in the mouse model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). Injected IL-4⁺Mfg-e8⁺ EVs target mainly phagocytes (i.e., macrophages and microglia) surrounding liquoral spaces, and their cargo promote the upregulation of anti-inflammatory markers chitinase 3-like 3 (ym1) and arginase-1 (arg1), significantly reducing tissue damage. Engineered EVs may represent a biological drug delivery tool able to deliver multiple functional molecules simultaneously to treat neuroinflammatory diseases.

Effect of soluble factors derived from ZR 75.30 breast cancer cells on endothelial activation

In this study, we analyzed soluble factors secreted by two Estrogen Receptor Positive (ER-α) human breast cancer cell lines, ZR 75.30 (luminal B) and MCF7 (luminal A), and evaluated their effect on endothelial activation. The composition of tumoral soluble factors (TSFs) was analyzed by ELISA (Bio-Plex). TSFs from ZR 75.30 cells expressed higher levels of TNF, IFN-γ, IL-6, and IL-8 compared to TSFs from MCF-7 cells. TSFs from ZR 75.30 cells induced a pro-adhesive phenotype in human umbilical vein endothelial cells (HUVECs), as characterized by increased monocytic cell adhesion, adhesion molecule expression and NF-κB activation and decreased IκB-α expression. Conversely, TSFs from MCF-7 cells exerted none of these effects on HUVECs. We then added TNF, IFN-γ, IL-6 or IL-8 alone or in combination with TSFs from MCF-7 cells to HUVECs. Only the combinations that included TNF induced endothelial activation. A neutralizing antibody against IL-1β (this cytokine was not measured in the ELISA) had a modest blocking effect on cellular adhesion or the expression of adhesion molecules induced by TSFs from ZR 75.30 cells in HUVECs. However neutralizing antibodies against TNF, IFN-γ, IL-6 or IL-8 had no effect. Our results suggest that although TNF is an inducer of endothelial cell activation, it is not the only molecule that is responsible for this effect in TSFs from ZR 75.30 cells.

Prognostic Correlation Between MFG-E8 Expression Level and Colorectal Cancer

BACKGROUND AND AIMS

Colorectal cancer (CRC) is one of the leading causes of cancer-related death all over the world. Milk fat globule-epidermal growth factor (EGF)-factor VIII (MFG-E8) was found to be highly expressed in a variety of cancers. However its role in CRC is unclear. This study investigates the expression of MFG-E8 in CRC tissues and the correlation with clinicopathological features and prognosis in CRC patients.

METHODS

The expression of MFG-E8 proteins was detected by immunohistochemical staining in 90 samples of CRC. The localization of MFG-E8 in colorectal tumor was examined by immunofluorescence staining. The correlation between MFG-E8 protein expression and the clinical pathological features of CRC were evaluated by χ² test and Fisher's exact test. The survival rates were analyzed by the Kaplan-Meier method, and the relationship between prognostic factors and patient survival was analyzed by the Cox proportional hazard models.

RESULTS

Our results showed that MFG-E8 expression increased significantly in colorectal cancer compared with normal mucosa tissues (p <0.001). We further validated MFG-E8 overexpression in 6 pairs of fresh tumor and adjacent normal mucosa tissues from colorectal cancer patients by Western blot (p <0.05). Immunofluorescence staining showed that MFG-E8 accumulated in close proximity to endothelial cells in human colorectal tumor tissue. In addition, high MFG-E8 protein expression was correlated with lymph node metastasis and some pathological classifications (p <0.05). Furthermore, patients with high protein level of MFG-E8 showed shortened overall survivals (p <0.05).

CONCLUSION

Our results showed that MFG-E8 could be a potential novel prognostic marker for CRC and overexpression of MFG-E8 might be involved in lymph node metastasis and angiogenesis of CRC.

Restoration of Circulating MFGE8 (Milk Fat Globule-EGF Factor 8) Attenuates Cardiac Hypertrophy Through Inhibition of Akt Pathway

Cardiac hypertrophy occurs in response to numerous stimuli like neurohumoral stress, pressure overload, infection, and injury, and leads to heart failure. Mfge8 (milk fat globule-EGF factor 8) is a secreted protein involved in various human diseases, but its regulation and function during cardiac hypertrophy remain unexplored. Here, we found that circulating MFGE8 levels declined significantly in failing hearts from patients with dilated cardiomyopathy. Correlation analyses revealed that circulating MFGE8 levels were negatively correlated with the severity of cardiac dysfunction and remodeling in affected patients. Deleting Mfge8 in mice maintained normal heart function at basal level but substantially exacerbated the hypertrophic enlargement of cardiomyocytes, reprogramming of pathological genes, contractile dysfunction, and myocardial fibrosis after aortic banding surgery. In contrast, cardiac-specific Mfge8 overexpression in transgenic mice significantly blunted aortic banding-induced cardiac hypertrophy. Whereas MAPK (mitogen-activated protein kinase) pathways were unaffected in either Mfge8-knockout or Mfge8-overexpressing mice, the activated Akt/PKB (protein kinase B)-Gsk-3β (glycogen synthase kinase-3β)/mTOR (mammalian target of rapamycin) pathway after aortic banding was significantly potentiated by Mfge8 deficiency but suppressed by Mfge8 overexpression. Inhibition of Akt with MK-2206 blocked the prohypertrophic effects of Mfge8 deficiency in angiotensin II-treated neonatal rat cardiomyocytes. Finally, administering a recombinant human MFGE8 in mice in vivo alleviated cardiac hypertrophy induced by aortic banding. Our findings indicate that Mfge8 is an endogenous negative regulator of pathological cardiac hypertrophy and may, thus, have potential both as a novel biomarker and as a therapeutic target for treatment of cardiac hypertrophy.

iCELLigence real-time cell analysis system for examining the cytotoxicity of drugs to cancer cell lines

The recently developed iCELLigence™ real-time cell analyzer (RTCA) can be used for the label-free real-time monitoring of cancer cell proliferation, viability, invasion and cytotoxicity. The RTCA system uses 16-well microtiter plates with a gold microelectrode biosensor array that measures impedance when cells adhere to the microelectrodes causing an alternating current. By measuring the electric field generated in this process, the RTCA system can be used for the analysis of cell proliferation, viability, morphology and migration. The present review aimed to summarize the working method of the RTCA system, in addition to discussing the research performed using the system for various applications, including cancer drug discovery via measuring cytotoxicity.

In Vivo Genetic Screens of Patient-Derived Tumors Revealed Unexpected Frailty of the Transformed Phenotype

The identification of genes maintaining cancer growth is critical to our understanding of tumorigenesis. We report the first in vivo genetic screen of patient-derived tumors, using metastatic melanomas and targeting 236 chromatin genes by expression of specific shRNA libraries. Our screens revealed unprecedented numerosity of genes indispensable for tumor growth (∼50% of tested genes) and unexpected functional heterogeneity among patients (<15% in common). Notably, these genes were not activated by somatic mutations in the same patients and are therefore distinguished from mutated cancer driver genes. We analyzed underlying molecular mechanisms of one of the identified genes, the Histone-lysine N-methyltransferase KMT2D, and showed that it promotes tumorigenesis by dysregulating a subset of transcriptional enhancers and target genes involved in cell migration. The assembly of enhancer genomic patterns by activated KMT2D was highly patient-specific, regardless of the identity of transcriptional targets, suggesting that KMT2D might be activated by distinct upstream signaling pathways.

SIGNIFICANCE

Drug targeting of biologically relevant cancer-associated mutations is considered a critical strategy to control cancer growth. Our functional in vivo genetic screens of patient-derived tumors showed unprecedented numerosity and interpatient heterogeneity of genes that are essential for tumor growth, but not mutated, suggesting that multiple, patient-specific signaling pathways are activated in tumors. Cancer Discov; 6(6); 650-63. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 561.

Proteomic comparison defines novel markers to characterize heterogeneous populations of extracellular vesicle subtypes

Extracellular vesicles (EVs) have become the focus of rising interest because of their numerous functions in physiology and pathology. Cells release heterogeneous vesicles of different sizes and intracellular origins, including small EVs formed inside endosomal compartments (i.e., exosomes) and EVs of various sizes budding from the plasma membrane. Specific markers for the analysis and isolation of different EV populations are missing, imposing important limitations to understanding EV functions. Here, EVs from human dendritic cells were first separated by their sedimentation speed, and then either by their behavior upon upward floatation into iodixanol gradients or by immuno-isolation. Extensive quantitative proteomic analysis allowing comparison of the isolated populations showed that several classically used exosome markers, like major histocompatibility complex, flotillin, and heat-shock 70-kDa proteins, are similarly present in all EVs. We identified proteins specifically enriched in small EVs, and define a set of five protein categories displaying different relative abundance in distinct EV populations. We demonstrate the presence of exosomal and nonexosomal subpopulations within small EVs, and propose their differential separation by immuno-isolation using either CD63, CD81, or CD9. Our work thus provides guidelines to define subtypes of EVs for future functional studies.

Evidence that HIV-1 restriction factor SAMHD1 facilitates differentiation of myeloid THP-1 cells

Background

SAMHD1 counteracts HIV-1 or HIV-2/SIVsmm that lacks Vpx by depleting the intracellular pool of nucleotides in myeloid cells and CD4+ quiescent T cells, thereby inhibiting the synthesis of retroviral DNA by reverse transcriptase. Depletion of nucleotides has been shown to underline the establishment of quiescence in certain cellular systems. These observations led us to investigate whether SAMHD1 could control the transition between proliferation and quiescence using the THP-1 cell model.

Findings

The entry of dividing THP-1 myeloid cells into a non-dividing differentiated state was monitored after addition of phorbol-12-myristate-13-acetate (PMA), an inducer of differentiation. Under PMA treatment, cells overexpressing SAMHD1 display stronger and faster adhesion to their support, compared to cells expressing a catalytically inactive form of SAMHD1, or cells depleted of SAMHD1, which appear less differentiated. After PMA removal, cells overexpressing SAMHD1 maintain low levels of cyclin A, in contrast to other cell lines. Interestingly, SAMHD1 overexpression slightly increases cell adhesion even in the absence of the differentiation inducer PMA. Finally, we found that levels of SAMHD1 are reduced in proliferating primary CD4+ T cells after T cell receptor activation, suggesting that SAMHD1 may also be involved in the transition from a quiescent state to a dividing state in primary T cells.

Conclusions

Altogether, we provide evidence that SAMHD1 may facilitate some aspects of THP-1 cell differentiation. Restriction of HIV-1 by SAMHD1 may rely upon its ability to modify cell cycle parameters, in addition to the direct inhibition of reverse transcription.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-015-0425-y) contains supplementary material, which is available to authorized users.

Low density lipoprotein receptor-related protein 1 mediated endocytosis of β1-integrin influences cell adhesion and cell migration

The low density lipoprotein receptor-related protein 1 (LRP1) has been shown to interact with β1-integrin and regulate its surface expression. LRP1 knock-out cells exhibit altered cytoskeleton organization and decreased cell migration. Here we demonstrate coupled endocytosis of LRP1 and β1-integrin and the involvement of the intracellular NPxY2 motif of LRP1 in this process. Mouse embryonic fibroblasts harboring a knock in replacement of the NPxY2 motif of LRP1 by a multiple alanine cassette (AAxA) showed elevated surface expression of β1-integrin and decreased β1-integrin internalization rates. As a consequence, cell spreading was altered and adhesion rates were increased in our cell model. Cells formed more focal adhesion complexes, whereby in vitro cell migration rates were decreased. Similar results could be observed in a corresponding mouse model, the C57Bl6 LRP1 NPxYxxL knock in mice, therefore, the biochemistry of cellular adhesion was altered in primary cortical neurons. In vivo cell migration experiments demonstrated a disturbance of neuroblast cell migration along the rostral migratory stream. In summary, our results indicate that LRP1 interacts with β1-integrin mediating integrin internalization and thus correlates with downstream signaling of β1-integrin such as focal adhesion dynamics. Consequently, the disturbance of this interaction resulted in a dysfunction in in vivo and in vitro cell adhesion and cell migration.

MFG-E8 expression for progression of oral squamous cell carcinoma and for self-clearance of apoptotic cells

Milk fat globule--epidermal growth factor (EGF)--factor VIII (MFG-E8) is a secreted glycoprotein that promotes clearance of apoptotic cells by bridging phosphatidylserine on apoptotic cells and integrin αvβ3/5 on phagocytes. High expression of MFG-E8 has been reported in various types of cancer in humans. Apoptotic figures are frequently found in the surgical samples of oral squamous cell carcinoma (SCC) and carcinoma in situ, and we have often observed apoptotic carcinoma cells engulfed by macrophages or even by neighboring carcinoma cells. Thus we hypothesized that MFG-E8 might promote engulfment of apoptotic carcinoma cells by living carcinoma cells and that MFG-E8 expressed by carcinoma cells could contribute to tumor progression. The aim of this study was to elucidate the biological role of MFG-E8 in oral SCC. Fifty-three surgical specimens of oral SCC were used for immunohistochemistry for MFG-E8, and the expression profiles were correlated with clinicopathological properties. Also, we examined the MFG-E8 expression patterns and functions using three human oral SCC cell lines. Most of the cases had MFG-E8-positive SCC cells, and the expression of MFG-E8 was correlated with such clinicopathological features as tumor size, pathological stage, locoregional recurrence, scattering invasion pattern, and SCC cell figures engulfing apoptotic SCC cells. The MFG-E8 staining was enhanced in apoptotic SCC cells, some of which were apparently engulfed by the neighboring SCC cells. ZK-1 cells showed high MFG-E8 expression, and its localization was found in the cytoplasm and the cell surface. Transient MFG-E8 knockdown by siRNA in ZK-1 decreased cell proliferation and invasiveness and increased cell death. Thus we have demonstrated that MFG-E8 promotes tumor progression in oral SCC and that it might be involved in the clearance of apoptotic SCC cells by living SCC cells.

Low expression levels of microRNA-124-5p correlated with poor prognosis in colorectal cancer via targeting of SMC4

A component of polycomb repressor complex 2, enhancer of zeste homolog 2 (EZH2), plays an important role in tumor malignancy and metastasis, while milk fat globule-epidermal growth factor-factor 8 (MFGE8) plays a key role in tumor progression and prognosis. MicroRNAs (miRs) are also critically involved in various physiological and pathological processes. We here evaluated the relationship between overall survival (OS) in colorectal cancer patients and the expression of onco-miRs and miRs, which may target EZH2 and MFGE8. Plasma and formalin-fixed paraffin-embedded (FFPE) samples were obtained from 71 colorectal cancer patients. The expression levels of miRs complementary to EZH2 and MFGE8 mRNA and cancer malignancies were evaluated. The miRs analyzed were as follows: miR-16, miR-21, miR-26a, miR-34a, miR-98, miR-101-3p, miR-101-5p, miR-124-5p (also known as miR-124*), miR-126-3p, miR-126-5p, miR-210, miR-217, and miR-630. The plasma expression levels of MFGE8 in completely resected patients were significantly lower than those in unresectable patients. Lower miR-26a expression levels were correlated with a higher probability of OS. Higher miR-124-5p expression levels in plasma and FFPE samples were correlated with a higher probability of OS. The transfection of mimic miR-124-5p into WiDr and COLO201 cells inhibited the expression of structural maintenance of chromosomes 4 (SMC4) mRNA. Our results indicate that miR-124-5p may target the tumorigenesis gene, SMC4, which suggests that expression levels of miR-124-5p in plasma and FFPE samples; therefore, the expression of MFGE8, miR-26a, and miR-124-5p in plasma may be used as biomarkers to determine the prognosis of colorectal cancer patients.

An essential role for decorin in bladder cancer invasiveness

Muscle-invasive forms of urothelial carcinomas are responsible for most mortality in bladder cancer. Finding new treatments for invasive bladder tumours requires adequate animal models to decipher the mechanisms of progression, in particular the way tumours interact with their microenvironment. Herein, using the murine bladder tumour cell line MB49 and its more aggressive variant MB49-I, we demonstrate that the adaptive immune system efficiently limits progression of MB49, whereas MB49-I has lost tumour antigens and is insensitive to adaptive immune responses. Furthermore, we unravel a parallel mechanism developed by MB49-I to subvert its environment: de novo secretion of the proteoglycan decorin. We show that decorin overexpression in the MB49/MB49-I model is required for efficient progression, by promoting angiogenesis and tumour cell invasiveness. Finally, we show that these results are relevant to muscle-invasive human bladder carcinomas, which overexpress decorin together with angiogenesis- and adhesion/migration-related genes, and that decorin overexpression in the human bladder carcinoma cell line TCCSUP is required for efficient invasiveness in vitro. We thus propose decorin as a new therapeutic target for these aggressive tumours.