Low Expression of Slit2 and Robo1 is Associated with Poor Prognosis and Brain-specific Metastasis of Breast Cancer Patients

Emerging Role of the Slit/Roundabout (Robo) Signaling Pathway in Glioma Pathogenesis and Potential Therapeutic Options

Gliomas represent the most common primary Central Nervous System (CNS) tumors, characterized by increased heterogeneity, dysregulated intracellular signaling, extremely invasive properties, and a dismal prognosis. They are generally resistant to existing therapies and only a few molecular targeting options are currently available. In search of signal transduction pathways with a potential impact in glioma growth and immunotherapy, the Slit guidance ligands (Slits) and their Roundabout (Robo) family of receptors have been revealed as key regulators of tumor cells and their microenvironment. Recent evidence indicates the implication of the Slit/Robo signaling pathway in inflammation, cell migration, angiogenesis, and immune cell infiltration of gliomas, suppressing or promoting the expression of pivotal proteins, such as cell adhesion molecules, matrix metalloproteinases, interleukins, angiogenic growth factors, and immune checkpoints. Herein, we discuss recent data on the significant implication of the Slit/Robo signaling pathway in glioma pathology along with the respective targeting options, including immunotherapy, monoclonal antibody therapy, and protein expression modifiers.

LncRNA PGM5-AS1 inhibits non-small cell lung cancer progression by targeting miRNA-423-5p/SLIT2 axis

Non-small cell lung cancer (NSCLC) is a common and aggressive primary malignancy worldwide. Dysregulation of long non-coding RNAs (lncRNAs) has been shown to play an essential regulatory role in multiple cancers. However, the role of PGM5-AS1 in NSCLC remains unclear. Here, we found that PGM5-AS1 was down-regulated in NSCLC tissues and cells. Furthermore, reduced PGM5-AS1 expression levels were associated with larger tumor size, positive lymph node metastasis, advanced TNM stage and worse prognosis. We found that overexpression of PGM5-AS1 inhibited cell proliferation and metastasis, and induced apoptosis and G0/G1 cell cycle arrest in NSCLC cell lines. Using dual luciferase gene reporter and RNA immunoprecipitation assays, we confirmed that miR-423-5p interacted with PGM5-AS1, and that their expression levels were negatively correlated in NSCLC tissues. miR-423-5p was also found to reverse PGM5-AS1-induced malignant biological behavior. Moreover, we identified slit guidance ligand 2 (SLIT2) as a target gene of miR-423-5p. Using a dual luciferase gene reporter assay, we confirmed the regulatory relationship between SLIT2 and miR-423-5p and demonstrated that their expression levels were negatively correlated. Our rescue experiments showed that SLIT2 knockdown reversed miR-423-5p-mediated effects. Overall, this study identifies PGM5-AS1 as a potential prognostic biomarker for NSCLC and shows that PGM5-AS1 suppresses NSCLC development by regulating the miR-423-5p/SLIT2 axis.

The role of microRNAs in brain metastasis

Brain metastasis (BM) is the most common type of brain tumor and frequently foreshadows disease progression and poor overall survival with patients having a median survival of 6 months. 70,000 new cases of BM are diagnosed each year in the United States (US) and the incidence rate for BM is increasing with improved detection. MicroRNAs (miRNAs) are small non-coding RNAs that serve as critical regulators of gene expression and can act as powerful oncogenes and tumor suppressors. MiRNAs have been heavily implicated in cancer and proposed as biomarkers or therapeutic targets or agents. In this review, we summarize an extensive body of scientific work investigating the role of microRNAs in BM. We discuss miRNA dysregulation, functions, targets, and mechanisms of action in BM and present the current standing of miRNAs as biomarkers and potential therapeutics for BM. We conclude with future directions of miRNA basic and clinical research in BM.

Biological function analysis of ARHGAP39 as an independent prognostic biomarker in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common subtype of liver cancer, with a high morbidity and low survival rate. Rho GTPase activating protein 39 (ARHGAP39) is a crucial activating protein of Rho GTPases, a novel target in cancer therapy, and it was identified as a hub gene for gastric cancer. However, the expression and role of ARHGAP39 in hepatocellular carcinoma remain unclear. Accordingly, the cancer genome atlas (TCGA) data were used to analyze the expression and clinical value of ARHGAP39 in hepatocellular carcinoma. Further, the LinkedOmics tool suggested functional enrichment pathways for ARHGAP39. To investigate in depth the possible role of ARHGAP39 on immune infiltration, we analyzed the relationship between ARHGAP39 and chemokines in HCCLM3 cells. Finally, the GSCA website was used to explore drug resistance in patients with high ARHGAP39 expression. Studies have shown that ARHGAP39 is highly expressed in hepatocellular carcinoma and relevant to clinicopathological features. In addition, the overexpression of ARHGAP39 leads to a poor prognosis. Besides, co-expressed genes and enrichment analysis showed a correlation with the cell cycle. Notably, ARHGAP39 may worsen the survival of hepatocellular carcinoma patients by increasing the level of immune infiltration through chemokines. Moreover, N6-methyladenosine (m6A) modification-related factors and drug sensitivity were also found to be associated with ARHGAP39. In brief, ARHGAP39 is a promising prognostic factor for hepatocellular carcinoma patients that is closely related to cell cycle, immune infiltration, m6A modification, and drug resistance.

Aberrant Methylation of SLIT2 Gene in Plasma Cell-Free DNA of Non-Small Cell Lung Cancer Patients

Simple Summary

Despite significant advances in the detection, prevention, and treatment of lung cancer, the prognosis of the patients is still very poor due in part to micrometastasis of cancer cells to surrounding tissues at the time of diagnosis. Therefore, identifying biomarkers for early detection of lung cancer is very important for prolonging the lifespan of patients with lung cancer. The methylation statuses of SLIT1, SLIT2, SLIT3 genes were analyzed in bronchial washing, bronchial biopsy, sputum, tumor and matched normal tissues, or plasma samples obtained from a total of 208 non-small cell lung cancer (NSCLC) patients and 121 cancer-free patients to understand the feasibility of the genes as biomarkers for early detection and survival prediction of NSCLC. The present study suggests that aberrant methylation of SLIT2 in plasma cell-free DNA might be a potential biomarker for the early detection and prognosis prediction of NSCLC patient.

Abstract

This study aimed to understand aberrant methylation of SLITs genes as a biomarker for the early detection and prognosis prediction of non-small cell lung cancer (NSCLC). Methylation levels of SLITs were determined using the Infinium HumanMethylation450 BeadChip or pyrosequencing. Five CpGs at the CpG island of SLIT1, SLIT2 or SLIT3 genes were significantly (Bonferroni corrected p < 0.05) hypermethylated in tumor tissues obtained from 42 NSCLC patients than in matched normal tissues. Methylation levels of these CpGs did not differ significantly between bronchial washings obtained from 76 NSCLC patients and 60 cancer-free patients. However, methylation levels of SLIT2 gene were significantly higher in plasma cell-free DNA of 72 NSCLC patients than in that of 61 cancer-free patients (p = 0.001, Wilcoxon rank sum test). Prediction of NSCLC using SLIT2 methylation was achieved with a sensitivity of 73.7% and a specificity of 61.9% in a plasma test dataset (N = 40). A Cox proportional hazards model showed that SLIT2 hypermethylation in plasma cell-free DNA was significantly associated with poor recurrence-free survival (hazards ratio = 2.19, 95% confidence interval = 1.21–4.36, p = 0.01). The present study suggests that aberrant methylation of SLIT2 in plasma cell-free DNA is a valuable biomarker for the early detection of NSCLC and prediction of recurrence-free survival. However, further research is needed with larger sample size to confirm results.

Discovery of Cancer-Specific and Independent Prognostic Gene Subsets of the Slit-Robo Family Using TCGA-PANCAN Datasets

The Slit-Robo family of axon guidance molecules works in concert, playing important roles in organ development and cancer. Expressions of individual Slit-Robo genes have been used in calculating univariable hazard ratios (HR_uni) for predicting cancer prognosis in the literature. However, Slit-Robo members do not act independently; hence, hazard ratios from multivariable Cox regression (HR_multi) on the whole gene set can further lead to identification of cancer-specific, novel, and independent prognostic gene pairs or modules. Herein, we obtained mRNA expressions of the Slit-Robo family consisting of four Robos (ROBO1/2/3/4) and three Slits (SLIT1/2/3), along with four types of survival outcome across cancers found in the Cancer Genome Atlas (TCGA). We used cluster heat maps to visualize closely associated pairs/modules of prognostic genes across 33 different cancers. We found a smaller number of significant genes in HR_multi than in HR_uni, suggesting that the former analysis was less redundant. High ROBO4 expression emerged as relatively protective within the family, in both types of HR analyses. Multivariable Cox regression, on the other hand, revealed significantly more HR signatures containing Slit-Robo pairs acting in opposing directions than those containing Slit-Slit or Robo-Robo pairs for disease-specific survival. Furthermore, we discovered, through the online app SmulTCan's lasso regression, Slit-Robo gene subsets that significantly differentiated between high- versus low-risk prognosis patient groups, particularly for renal cancers and low-grade glioma. The statistical pipeline reported herein can help test independent and significant pairs/modules within a codependent gene family for cancer prognostication, and thus should also prove useful in personalized/precision medicine research.

The Role of Neurodevelopmental Pathways in Brain Tumors

Disruptions to developmental cell signaling pathways and transcriptional cascades have been implicated in tumor initiation, maintenance and progression. Resurgence of aberrant neurodevelopmental programs in the context of brain tumors highlights the numerous parallels that exist between developmental and oncologic mechanisms. A deeper understanding of how dysregulated developmental factors contribute to brain tumor oncogenesis and disease progression will help to identify potential therapeutic targets for these malignancies. In this review, we summarize the current literature concerning developmental signaling cascades and neurodevelopmentally-regulated transcriptional programs. We also examine their respective contributions towards tumor initiation, maintenance, and progression in both pediatric and adult brain tumors and highlight relevant differentiation therapies and putative candidates for prospective treatments.

Roundabout homolog 1 inhibits proliferation via the YY1-ROBO1-CCNA2-CDK2 axis in human pancreatic cancer

Pancreatic cancer (PC) is highly malignant and has a high mortality with a 5-year survival rate of less than 8%. As a member of the roundabout immunoglobulin superfamily of proteins, ROBO1 plays an important role in embryogenesis and organogenesis and also inhibits metastasis in PC. Our study was designed to explore whether ROBO1 has effects on the proliferation of PC and its specific mechanism. The expression of ROBO1 was higher in cancer tissues than in matched adjacent tissues by immunohistochemistry (IHC) and qRT-PCR. Low ROBO1 expression is associated with PC progression and poor prognosis. Overexpression of ROBO1 can inhibit the proliferation of PC cells in vitro, and the S phase fraction can also be induced. Further subcutaneous tumor formation in nude mice showed that ROBO1 overexpression can significantly inhibit tumor growth. YY1 was found to directly bind to the promoter region of ROBO1 to promote transcription by a luciferase reporter gene assay, a chromatin immunoprecipitation (ChIP) and an electrophoretic mobility shift assay (EMSA). Mechanistic studies showed that YY1 can inhibit the development of PC by directly regulating ROBO1 via the CCNA2/CDK2 axis. Taken together, our results suggest that ROBO1 may be involved in the development and progression of PC by regulating cell proliferation and shows that ROBO1 may be a novel and promising therapeutic target for PC.

M6A RNA Methylation Regulator HNRNPC Contributes to Tumorigenesis and Predicts Prognosis in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most malignant glioma with a high death rate. N6-methyladenosine (m6A) RNA methylation plays an increasingly important role in tumors. The current study aimed to determine the function of the regulators of m6A RNA methylation in GBM. We evaluated the difference, interaction, and correlation of these regulators with TCGA database. HNRNPC, WTAP, YTHDF2 and, YTHDF1 were significantly upregulated in GBM. To explore the expression characteristics of regulators in GBM, we defined two subgroups through consensus cluster. HNRNPC, WTAP, and YTHDF2 were significantly upregulated in the cluster2 which had a good overall survival (OS). To investigate the prognostic value of regulators, we used lasso cox regression algorithm to screen an independent prognostic risk characteristic based on the expression of HNRNPC, ZC3H13, and YTHDF2. The prognostic feature between the low and high-risk groups was significantly different (P < 0.05), which could predict significance of prognosis (area under the curve (AUC) = 0.819). Moreover, we used western blot, RT-PCR, and immunohistochemical staining to verify the expression of HNRNPC was associated with malignancy and development of gliomas. Similarly, the high expression of HNRNPC had a good prognosis. In conclusion, HNRNPC is a vital participant in the malignant progression of GBM and might be valuable for prognosis.

TGF-β1-induced miR-424 promotes pulmonary myofibroblast differentiation by targeting Slit2 protein expression

Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease with irreversible loss of lung tissue and function. Myofibroblasts in the lung are key cellular mediators of IPF progression. Transforming growth factor (TGF)-β1, a major profibrogenic cytokine, induces pulmonary myofibroblast differentiation, and emerging evidence has established the importance of microRNAs (miRs) in the development of IPF. The objective of this study was to define the pro-fibrotic roles and mechanisms of miRs in TGF-β1-induced pulmonary myofibroblast differentiation. Using RNA sequencing, we identified miR-424 as an important TGF-β1-induced miR in human lung fibroblasts (HLFs). Quantitative RT-PCR confirmed that miR-424 expression was increased by 2.6-fold in HLFs in response to TGF-β1 and was 1.7-fold higher in human fibrotic lung tissues as compared to non-fibrotic lung tissues. TGF-β1-induced upregulation of miR-424 was blocked by the Smad3 inhibitor SIS3, suggesting the involvement of this canonical TGF-β1 signaling pathway. Transfection of a miR-424 hairpin inhibitor into HLFs reduced TGF-β1-induced expression of classic myofibroblast differentiation markers including ɑ-smooth muscle actin (ɑ-SMA) and connective tissue growth factor (CTGF), whereas a miR-424 mimic significantly enhanced TGF-β1-induced myofibroblast differentiation. In addition, TGF-β1 induced Smad3 phosphorylation in HLFs, and this response was reduced by the miR-424 inhibitor. In silico analysis identified Slit2, a protein that inhibits TGF-β1 profibrogenic signaling, as a putative target of regulation by miR-424. Slit2 is less highly expressed in human fibrotic lung tissues than in non-fibrotic lung tissues, and knockdown of Slit2 by its siRNA enhanced TGF-β1-induced HLF differentiation. Overexpression of a miR-424 mimic down-regulated expression of Slit2 but not the Slit2 major receptor ROBO1 in HLFs. Luciferase reporter assays showed that the miR-424 mimic represses Slit2 3' untranslated region (3'-UTR) reporter activity, and mutations at the seeding regions in the 3'-UTR of Slit2 abolish this inhibition. Together, these data demonstrate a pro-fibrotic role of miR-424 in TGF-β1-induced HLF differentiation. It functions as a positive feed-back regulator of the TGF-β1 signaling pathway by reducing expression of the negative regulator Slit2. Thus, targeting miR-424 may provide a new therapeutic strategy to prevent myofibroblast differentiation and IPF progression.

Identification and validation of smoking-related genes in lung adenocarcinoma using an in vitro carcinogenesis model and bioinformatics analysis

Background

Lung cancer is one of the most common carcinomas in the world, and lung adenocarcinoma (LUAD) is the most lethal and most common subtype of lung cancer. Cigarette smoking is the most leading risk factor of lung cancer, but it is still unclear how normal lung cells become cancerous in cigarette smokers. This study aims to identify potential smoking-related biomarkers associated with the progression and prognosis of LUAD, as well as their regulation mechanism using an in vitro carcinogenesis model and bioinformatics analysis.

Results

Based on the integration analysis of four Gene Expression Omnibus (GEO) datasets and our mRNA sequencing analysis, 2 up-regulated and 11 down-regulated genes were identified in both S30 cells and LUAD. By analyzing the LUAD dataset in The Cancer Gene Analysis (TCGA) database, 3 of the 13 genes, viz., glycophorin C (GYPC), NME/NM23 nucleoside diphosphate kinase 1 (NME1) and slit guidance ligand 2 (SLIT2), were found to be significantly correlated with LUAD patients’ smoking history. The expression levels of GYPC, NME1 and SLIT2 in S30 cells and lung cancer cell lines were validated by quantitative PCR, immunofluorescence, and western blot assays. Besides, these three genes are associated with tumor invasion depth, and elevated expression of NME1 was correlated with lymph node metastasis. The enrichment analysis suggested that these genes were highly correlated to tumorigenesis and metastasis-related biological processes and pathways. Moreover, the increased expression levels of GYPC and SLIT2, as well as decreased expression of NME1 were associated with a favorable prognosis in LUAD patients. Furthermore, based on the multi-omics data in the TCGA database, these genes were found to be regulated by DNA methylation.

Conclusion

In conclusion, our observations indicated that the differential expression of GYPC, NME1 and SLIT2 may be regulated by DNA methylation, and they are associated with cigarette smoke-induced LUAD, as well as serve as prognostic factors in LUAD patients.

The proteomic analysis of breast cell line exosomes reveals disease patterns and potential biomarkers

Cancer cells release small extracellular vesicles, exosomes, that have been shown to contribute to various aspects of cancer development and progression. Differential analysis of exosomal proteomes from cancerous and non-tumorigenic breast cell lines can provide valuable information related to breast cancer progression and metastasis. Moreover, such a comparison can be explored to find potentially new protein biomarkers for early disease detection. In this study, exosomal proteomes of MDA-MB-231, a metastatic breast cancer cell line, and MCF-10A, a non-cancerous epithelial breast cell line, were identified by nano-liquid chromatography coupled to tandem mass spectrometry. We also tested three exosomes isolation methods (ExoQuick, Ultracentrifugation (UC), and Ultrafiltration–Ultracentrifugation) and detergents (n-dodecyl β-d-maltoside, Triton X-100, and Digitonin) for solubilization of exosomal proteins and enhanced detection by mass spectrometry. A total of 1,107 exosomal proteins were identified in both cell lines, 726 of which were unique to the MDA-MB-231 breast cancer cell line. Among them, 87 proteins were predicted to be relevant to breast cancer and 16 proteins to cancer metastasis. Three exosomal membrane/surface proteins, glucose transporter 1 (GLUT-1), glypican 1 (GPC-1), and disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), were identified as potential breast cancer biomarkers and validated with Western blotting and high-resolution flow cytometry. We demonstrated that exosomes are a rich source of breast cancer-related proteins and surface biomarkers that may be used for disease diagnosis and prognosis.

Aberrant HDAC3 expression correlates with brain metastasis in breast cancer patients

BACKGROUND

Brain metastasis is an unsolved clinical problem in breast cancer patients due to its poor prognosis and high fatality rate. Although accumulating evidence has shown that some pan-histone deacetylase (HDAC) inhibitors can relieve breast cancer brain metastasis, the specific HDAC protein involved in this process is unclear. Thus, identifying a specific HDAC protein closely correlated with breast cancer brain metastasis will not only improve our understanding of the functions of the HDAC family but will also help develop a novel target for precision cancer therapy.

METHODS

Immunohistochemical staining of HDAC1, HDAC2, and HDAC3 in 161 samples from breast invasive ductal carcinoma patients, including 63 patients with brain metastasis, was performed using the standard streptavidin-peroxidase method. The relationships between HDAC1, HDAC2, and HDAC3 and overall survival/brain metastasis-free survival/post-brain metastatic survival were evaluated using Kaplan-Meier curves and Cox regression analyses.

RESULTS

HDAC1, HDAC2, and cytoplasmic HDAC3 all displayed typical oncogenic characteristics and were independent prognostic factors for the overall survival of breast cancer patients. Only cytoplasmic HDAC3 was an independent prognostic factor for brain metastasis-free survival. Cytoplasmic expression of HDAC3 was further upregulated in the brain metastases compared with the matched primary tumors, while nuclear expression was downregulated. The HDAC1, HDAC2, and HDAC3 expression levels in the brain metastases were not correlated with survival post-brain metastasis.

CONCLUSIONS

Our studies first demonstrate a critical role for HDAC3 in the brain metastasis of breast cancer patients and it may serve as a promising therapeutic target for the vigorously developing field of precision medicine.

KEY POINTS

Significant findings of the study Cytoplasmic HDAC3 is an independent prognostic factor for the overall survival and brain metastasis-free survival of breast cancer patients. What this study adds Cytoplasmic expression of HDAC3 was further upregulated in the brain metastases compared with the matched primary tumours, while nuclear expression was downregulated.

Id Proteins Promote a Cancer Stem Cell Phenotype in Mouse Models of Triple Negative Breast Cancer via Negative Regulation of Robo1

Breast cancers display phenotypic and functional heterogeneity and several lines of evidence support the existence of cancer stem cells (CSCs) in certain breast cancers, a minor population of cells capable of tumor initiation and metastatic dissemination. Identifying factors that regulate the CSC phenotype is therefore important for developing strategies to treat metastatic disease. The Inhibitor of Differentiation Protein 1 (Id1) and its closely related family member Inhibitor of Differentiation 3 (Id3) (collectively termed Id) are expressed by a diversity of stem cells and are required for metastatic dissemination in experimental models of breast cancer. In this study, we show that ID1 is expressed in rare neoplastic cells within ER-negative breast cancers. To address the function of Id1 expressing cells within tumors, we developed independent murine models of Triple Negative Breast Cancer (TNBC) in which a genetic reporter permitted the prospective isolation of Id1+ cells. Id1+ cells are enriched for self-renewal in tumorsphere assays in vitro and for tumor initiation in vivo. Conversely, depletion of Id1 and Id3 in the 4T1 murine model of TNBC demonstrates that Id1/3 are required for cell proliferation and self-renewal in vitro, as well as primary tumor growth and metastatic colonization of the lung in vivo. Using combined bioinformatic analysis, we have defined a novel mechanism of Id protein function via negative regulation of the Roundabout Axon Guidance Receptor Homolog 1 (Robo1) leading to activation of a Myc transcriptional programme.

The Role of the Slit/Robo Signaling Pathway

The Slit family is a family of secreted proteins that play important roles in various physiologic and pathologic activities via interacting with Robo receptors. Slit/Robo signaling was first identified in the nervous system, where it functions in neuronal axon guidance; nevertheless, an increasing number of studies have shown that Slit/Robo signaling even regulates other activities, such as angiogenesis, inflammatory cell chemotaxis, tumor cell migration and metastasis. Although the precise role of the ligand-receptor in organisms has been obscure and the conclusions drawn are sometimes paradoxical, tremendous advances in understanding the Slit/Robo signaling pathway have been made. As such, our review summarizes the characteristics of the Slit/Robo signaling pathway and its role in various cell types.

The clinical significance of miR-335, miR-124, miR-218 and miR-484 downregulation in gastric cancer

Gastric cancer (GC) is one of the leading types of malignancy worldwide, particularly in Asian populations. Although the exact molecular mechanism of GC development remains unknown, microRNA (miRNA) has recently been shown to be involved. The current study aims to investigate the expression levels of bioinformatically ranked miRNAs in gastric tissues. Using bioinformatics tools, we prioritized miRNAs thought to be implicated in GC. Furthermore, polyA-qPCR was used to validate bioinformatics findings in 40 GC, 31 normal gastric tissue (NG) and 45 gastric dysplasia (GD) samples. As identified by bioinformatics analysis, miR-335 was shown to be the top-ranked miRNA implicated in GC. Moreover, a significant downregulation of miR-335, miR-124, miR-218 and miR-484 was found in GC and GD compared to NG samples. We found bioinformatics to be an efficient approach to finding candidate miRNAs relevant to GC development. Finally, the findings show that downregulation of miRNAs such as miR-124 and miR-218 in gastric tissue can be a significant indicator for neoplastic transformation.

Genetic susceptibility markers for a breast-colorectal cancer phenotype: Exploratory results from genome-wide association studies

BACKGROUND

Clustering of breast and colorectal cancer has been observed within some families and cannot be explained by chance or known high-risk mutations in major susceptibility genes. Potential shared genetic susceptibility between breast and colorectal cancer, not explained by high-penetrance genes, has been postulated. We hypothesized that yet undiscovered genetic variants predispose to a breast-colorectal cancer phenotype.

METHODS

To identify variants associated with a breast-colorectal cancer phenotype, we analyzed genome-wide association study (GWAS) data from cases and controls that met the following criteria: cases (n = 985) were women with breast cancer who had one or more first- or second-degree relatives with colorectal cancer, men/women with colorectal cancer who had one or more first- or second-degree relatives with breast cancer, and women diagnosed with both breast and colorectal cancer. Controls (n = 1769), were unrelated, breast and colorectal cancer-free, and age- and sex- frequency-matched to cases. After imputation, 6,220,060 variants were analyzed using the discovery set and variants associated with the breast-colorectal cancer phenotype at P<5.0E-04 (n = 549, at 60 loci) were analyzed for replication (n = 293 cases and 2,103 controls).

RESULTS

Multiple correlated SNPs in intron 1 of the ROBO1 gene were suggestively associated with the breast-colorectal cancer phenotype in the discovery and replication data (most significant; rs7430339, Pdiscovery = 1.2E-04; rs7429100, Preplication = 2.8E-03). In meta-analysis of the discovery and replication data, the most significant association remained at rs7429100 (P = 1.84E-06).

CONCLUSION

The results of this exploratory analysis did not find clear evidence for a susceptibility locus with a pleiotropic effect on hereditary breast and colorectal cancer risk, although the suggestive association of genetic variation in the region of ROBO1, a potential tumor suppressor gene, merits further investigation.

Transcriptomic and epigenetic analysis of breast cancer stem cells

AIM

Cancer stem cells (CSCs) drive triple-negative breast cancer recurrence via their properties of self-renewal, invasiveness and radio/chemotherapy resistance. This study examined how CSCs might sustain these properties.

MATERIALS & METHODS

Transcriptomes, DNA methylomes and histone modifications were compared between CSCs and non CSCs.

RESULTS

Transcriptome analysis revealed several pathways that were activated in CSCs, whereas cell cycle regulation pathways were inhibited. Cell development and signaling genes were differentially methylated, with histone methylation analysis suggesting distinct H3K4me2 and H3K27me3 enrichment profiles. An integrated analysis revealed several tumor suppressor genes downregulated in CSCs.

CONCLUSION

Differential activation of various signaling pathways and genes contributes to the tumor-promoting properties of CSCs. Therapeutic targets identified in the analysis may contribute to improving treatment options for patients.

Transcriptome profiling identified differentially expressed genes and pathways associated with tamoxifen resistance in human breast cancer

Tamoxifen (TAM) resistance is an important clinical problem in the treatment of breast cancer. In order to identify the mechanism of TAM resistance for estrogen receptor (ER)-positive breast cancer, we screened the transcriptome using RNA-seq and compared the gene expression profiles between the MCF-7 mamma carcinoma cell line and the TAM-resistant cell line TAMR/MCF-7, 52 significant differential expression genes (DEGs) were identified including SLIT2, ROBO, LHX, KLF, VEGFC, BAMBI, LAMA1, FLT4, PNMT, DHRS2, MAOA and ALDH. The DEGs were annotated in the GO, COG and KEGG databases. Annotation of the function of the DEGs in the KEGG database revealed the top three pathways enriched with the most DEGs, including pathways in cancer, the PI3K-AKT pathway, and focal adhesion. Then we compared the gene expression profiles between the Clinical progressive disease (PD) and the complete response (CR) from the cancer genome altas (TCGA). 10 common DEGs were identified through combining the clinical and cellular analysis results. Protein-protein interaction network was applied to analyze the association of ER signal pathway with the 10 DEGs. 3 significant genes (GFRA3, NPY1R and PTPRN2) were closely related to ER related pathway. These significant DEGs regulated many biological activities such as cell proliferation and survival, motility and migration, and tumor cell invasion. The interactions between these DEGs and drug resistance phenomenon need to be further elucidated at a functional level in further studies. Based on our findings, we believed that these DEGs could be therapeutic targets, which can be explored to develop new treatment options.

Pharmacogenetics of response to neoadjuvant paclitaxel treatment for locally advanced breast cancer

Locally advanced breast cancer (LABC) cases have a varying five-year survival rate, mainly influenced by the tumor response to chemotherapy. Paclitaxel activity (response rate) varies across populations from 21.5% to 84%. There are some reports on genetic traits and paclitaxel; however, there is still considerable residual unexplained variability. In this study, we aimed to test the association between eleven novel markers and tumor response to paclitaxel and to explore if any of them influenced tumor protein expression. We studied a cohort of 140 women with LABC. At baseline, we collected a blood sample (for genotyping), fine needle aspirates (for Western blot), and tumor measurements by imaging. After follow-up, we ascertained the response to paclitaxel monotherapy by comparing the percent change in the pre-, post- tumor measurements after treatment. To allocate exposure, we genotyped eleven SNPs with TaqMan probes on RT-PCR and regressed them to tumor response using linear modeling. In addition, we compared protein expression, between breast tumors and healthy controls, of those genes whose genetic markers were significantly associated with tumor response. After adjusting for multiple clinical covariates, SNPs on the LPHN2, ROBO1, SNTG1, and GRIK1 genes were significant independent predictors of poor tumor response (tumor growth) despite paclitaxel treatment. Moreover, proteins encoded by those genes are significantly downregulated in breast tumor samples.

Isolation of putative stem cells present in human adult olfactory mucosa

The olfactory mucosa (OM) has the unique characteristic of performing an almost continuous and lifelong neurogenesis in response to external injuries, due to the presence of olfactory stem cells that guarantee the maintenance of the olfactory function. The easy accessibility of the OM in humans makes these stem cells feasible candidates for the development of regenerative therapies. In this report we present a detailed characterization of a patient-derived OM, together with a description of cell cultures obtained from the OM. In addition, we present a method for the enrichment and isolation of OM stem cells that might be used for future translational studies dealing with neuronal plasticity, neuro-regeneration or disease modeling.

Integrative bioinformatics analysis identifies ROBO1 as a potential therapeutic target modified by miR-218 in hepatocellular carcinoma

Patients diagnosed with advanced hepatocellular carcinoma (HCC) presented poor prognosis and short survival time. Althouth accumulating contribution of continuous research has gradually revealed complex tumorigenesis mechanism of HCC with numerous and jumbled biomarkers, those specific ones for HCC diagnose and therapeutic treatment are required illustration. Multiple genes over-expressed in HCC specimens with at least 1.5 fold change were cohorted, compared with the non-cancerous tissues through integrative bioinformatics analysis from Gene Expression Omnibus (GEO) datasets GSE14520 and GSE6764, including 445 and 45 cases of samples spearatly, along with intensive exploration on the Cancer Genome Altas (TCGA) dataset of liver cancer. Thirteen genes significantly highly expressed, overlapping in the datasets above. The Database for Annotation Visualization and Integrated Discovery (DAVID) program was utilized for functional pathway enrichment analysis. Protein-protein Interaction (PPI) analysis was conducted through the Search Tool for the Retrieval of Interacting Genes (STRING) database. ROBO1 was highlighted as one of the most probable molecules among the 13 candidates participating in cancer process. Cancer Cell Line Encycolopedia (CCLE) database was utilized exploring ROBO1 expression in cell lines. Immunochemistry analysis and qRT-PCR assay were performed in our medical center, which indicates significant over-expression status in either HCC tumor specimens and 3 HCC cell lines. Furtherly, we recognized that miR-218, a tumor suppressor, might be an upstream regulator for ROBO1 directly binding to the mRNA 3’UTR and potentially modifying the expression and function of ROBO1. Herein, we conclude that ROBO1 is a mighty therapeutic targets modified by miR-218 in HCC deserving further investigation.

Slit2 suppresses endothelial cell proliferation and migration by inhibiting the VEGF-Notch signaling pathway

Slit homolog 2 (Slit2) is distributed in various tissues and participates in numerous cellular processes; however, the role of Slit2 in the regulation of angiogenesis remains controversial, since it has previously been reported to exert proangiogenic and antiangiogenic activities. The present study aimed to investigate the effects of Slit2 on vascular endothelial cell proliferation and migration in vitro, and to reveal the possible underlying signaling pathway. Aortic endothelial cells were isolated from Sprague Dawley rats and cultured. Cell proliferation assay, cell migration assay, immunocytochemistry and small interfering RNA transfection were subsequently performed. The results demonstrated that exogenous Slit2 administration markedly suppressed TNF-α-induced endothelial cell proliferation and migration in vitro. In addition, TNF-α application upregulated the protein expression levels of vascular endothelial growth factor (VEGF) and Notch in RAECs, whereas Slit2 administration downregulated VEGF and Notch expression in RAECs cultured in TNF-α conditioned medium. Further studies indicated that knockdown of VEGF suppressed the effects of TNF-α on the induction of RAEC proliferation and migration. VEGF knockdown-induced inhibition of RAEC proliferation and migration in TNF-α conditioned medium was also achieved without Slit2 administration. Furthermore, VEGF knockdown markedly decreased Notch1 and Notch2 expression. These results indicated that Slit2 suppresses TNF-α-induced vascular endothelial cell proliferation and migration in vitro by inhibiting the VEGF-Notch signaling pathway. Therefore, Slit2 may inhibit the proliferation and migration of endothelial cells during vascular development.

Interleukin-30 Promotes Breast Cancer Growth and Progression

The inflammatory tissue microenvironment that promotes the development of breast cancer is not fully understood. Here we report a role for elevated IL30 in supporting the breast cancer cell viability and invasive migration. IL30 was absent in normal mammary ducts, ductules, and acini of histologically normal breast and scanty in the few stromal infiltrating leukocytes. In contrast, IL30 was expressed frequently in breast cancer specimens where it was associated with triple-negative and HER2⁺ molecular subtypes. In stromal leukocytes found in primary tumors or tumor-draining lymph nodes, which included mainly CD14⁺ monocytes, CD68⁺ macrophages, and CD33⁺/CD11b⁺ myeloid cells, IL30 levels increased with disease stage and correlated with recurrence. A negative correlation was determined between IL30 expression by nodal stromal leukocytes and overall survival. In vitro studies showed that human recombinant IL30 upregulated expression of a pro-oncogenic program, including especially IL6 in both triple-negative and HER2⁺ breast cancer cells. In triple-negative breast cancer cells, IL30 boosted a broader program of proliferation, invasive migration, and an inflammatory milieu associated with KISS1-dependent metastasis. Silencing of STAT1/STAT3 signaling hindered the regulation of the primary growth and progression factors in breast cancer cells. IL30 administration in vivo fostered the growth of triple-negative breast cancer by promoting proliferation and vascular dissemination of cancer cells and the accumulation of intratumoral CD11b⁺/Gr1⁺ myeloid cell infiltrates. Overall, our results show how IL30 regulates breast cancer cell viability, migration, and gene expression to promote breast cancer growth and progression and its impact on patient outcome. Cancer Res; 76(21); 6218-29. ©2016 AACR.