Epithelial membrane protein-1 is a biomarker of gefitinib resistance

A comprehensive meta-analysis of transcriptome data to identify signature genes associated with pancreatic ductal adenocarcinoma

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) has a five-year survival rate of less than 5%. Absence of symptoms at primary tumor stages, as well as high aggressiveness of the tumor can lead to high mortality in cancer patients. Most patients are recognized at the advanced or metastatic stage without surgical symptom, because of the lack of reliable early diagnostic biomarkers. The objective of this work was to identify potential cancer biomarkers by integrating transcriptome data.

METHODS

Several transcriptomic datasets comprising of 11 microarrays were retrieved from the GEO database. After pre-processing, a meta-analysis was applied to identify differentially expressed genes (DEGs) between tumor and nontumor samples for datasets. Next, co-expression analysis, functional enrichment and survival analyses were used to determine the functional properties of DEGs and identify potential prognostic biomarkers. In addition, some regulatory factors involved in PDAC including transcription factors (TFs), protein kinases (PKs), and miRNAs were identified.

RESULTS

After applying meta-analysis, 1074 DEGs including 539 down- and 535 up-regulated genes were identified. Pathway enrichment analyzes using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that DEGs were significantly enriched in the HIF-1 signaling pathway and focal adhesion. The results also showed that some of the DEGs were assigned to TFs that belonged to 23 conserved families. Sixty-four PKs were identified among the DEGs that showed the CAMK family was the most abundant group. Moreover, investigation of corresponding upstream regions of DEGs identified 11 conserved sequence motifs. Furthermore, weighted gene co-expression network analysis (WGCNA) identified 8 modules, more of them were significantly enriched in Ras signaling, p53 signaling, MAPK signaling pathways. In addition, several hubs in modules were identified, including EMP1, EVL, ELP5, DEF8, MTERF4, GLUP1, CAPN1, IGF1R, HSD17B14, TOM1L2 and RAB11FIP3. According to survival analysis, it was identified that the expression levels of two genes, EMP1 and RAB11FIP3 are related to prognosis.

CONCLUSION

We identified several genes critical for PDAC based on meta-analysis and system biology approach. These genes may serve as potential targets for the treatment and prognosis of PDAC.

CUL4B-DDB1-COP1-mediated UTX downregulation promotes colorectal cancer progression

BACKGROUND

UTX (encoded by KDM6A), a histone demethylase for H3K27me2/3, is frequently mutated in human cancers. However, its functional and regulatory mechanisms in colorectal cancer (CRC) remain unclear.

METHODS

Immunohistochemistry staining was used to investigate the clinical relevance of UTX in CRC. Additionally, we generated a spontaneous mouse CRC model with conditional Utx knockout to explore the role of UTX in the colorectal tumorigenesis. Post-translational regulation of UTX was determined by co-immunoprecipitation and immunoblot analyses.

RESULTS

Herein, we identify that downregulation of UTX, mediated by the Cullin 4B-DNA Damage Binding Protein-1-Constitutive Photomorphogenesis Protein 1 (CUL4B-DDB1-COP1) complex, promotes CRC progression. Utx deletion in intestinal epithelial cells enhanced the susceptibility to tumorigenesis in AOM/DSS-induced spontaneous mouse CRC model. However, this effect is primarily alleviated by GSK126, an inhibitor of histone methyltransferase EZH2. Mechanistically, EMP1 and AUTS2 are identified as putative UTX target genes mediating UTX functions in limiting intestinal tumorigenesis. Notably, the CUL4B-DDB1-COP1 complex is identified as the functional E3 ligase responsible for targeting UTX for degradation in CRC cells. Thus, Cop1 deficiency in mouse intestinal tissue results in UTX accumulation and restricts tumorigenesis. Furthermore, patient cohort analysis reveals that UTX expression is negatively correlated with clinical stage, favorable disease outcomes, and COP1 expression.

CONCLUSIONS

In the current study, the tumor suppressor function and regulation of UTX in CRC provide a molecular basis and the rationale to target EZH2 in UTX-deficient CRC.

Expression of EMP 1, 2, and 3 in Adrenal Cortical Neoplasm and Pheochromocytoma

The purpose of this study is to investigate the expression of the epithelial membrane proteins (EMP) 1, 2, and 3 in adrenal gland neoplasm and to explore the broader implications of this. Tissue microarrays were constructed for 132 cases of adrenal cortical neoplasms (ACN) (adrenal cortical adenoma (115 cases), and carcinoma (17 cases)) and 189 cases of pheochromocytoma. Immunohistochemical staining was performed to identify EMP 1, 2, and 3, and was compared with clinicopathological parameters. The H-score of EMP 3 (p < 0.001) was higher in pheochromocytoma when compared to that of ACN, and the H-score of EMP 1 (p < 0.001) and EMP 3 (p < 0.001) was higher in adrenal cortical carcinomas when compared to that of adrenal cortical adenomas. A higher EMP 1 H-score was observed in pheochromocytomas with a GAPP score ≥3 (p = 0.018). In univariate analysis, high levels of EMP 1 and EMP 3 expression in ACN were associated with shorter overall survival (p = 0.001). Differences were observed in the expression of EMPs between ACN and pheochromocytoma. EMPs are associated with malignant tumor biology in adrenal cortical neoplasm and pheochromocytoma, suggesting the role of a prognostic and/or predictive factor for EMPs in adrenal tumor.

Identification of EMP1 as a critical gene for cisplatin resistance in ovarian cancer by using integrated bioinformatics analysis

BACKGROUND

Cisplatin resistance is among the main reasons for the poor prognosis of ovarian cancer (OC) patients. Until now, effective biomarkers for predicting cisplatin resistance in OC and specific drugs for reversing this resistance are lacking. This study identified the critical gene associated with cisplatin resistance in OC and provided a potential target for overcoming this resistance.

METHODS

Differentially expressed genes between cisplatin-resistant and -sensitive OCs were identified by screening public datasets. Survival analysis was conducted to screen prognosis-related DEGs. CIBERSORT, ESTIMATE, and immune checkpoint genes were used to assess the association between EMP1 expression and tumor microenvironment features. CTRP and GDSC databases were employed to analyze the correlation between EMP1 expression and cisplatin resistance. Furthermore, immunohistochemistry, qPCR, Western blotting, siRNA interference, and the CCK8 assay were performed to verify the role of EMP1 in cisplatin resistance in vitro. Finally, xenograft mouse models were generated to further confirm the role of EMP1 in cisplatin resistance in vivo.

RESULTS

EMP1 was identified as a critical gene associated with cisplatin resistance in OC. According to bioinformatics analyses, increased EMP1 expression was linked to higher stromal/ESTIMATE scores as well as greater ICG expression levels. The in vitro experiments showed that EMP1 was highly expressed in cisplatin-resistant OC tissues and cells, and silencing this EMP1 expression enhanced OC cell sensitivity to cisplatin. Finally, in vivo experiments confirmed that EMP1 promotes tumor growth and cisplatin resistance.

CONCLUSIONS

EMP1 can act as a predictive biomarker for cisplatin resistance in OC and as a potential therapeutic target.

EMP1 as a Potential Biomarker in Liver Fibrosis: A Bioinformatics Analysis

Liver fibrosis is a wound-healing response to chronic injury, which may result in cirrhosis and liver failure. Studies have been carried on the mechanisms and pathogenesis of liver fibrosis. However, the potential cell-specific expressed marker genes involved in fibrotic processes remain unknown. In this study, we combined a publicly accessible single-cell transcriptome of human liver with microarray datasets to evaluate the cell-specific expression patterns of differentially expressed genes in the liver. We noticed that EMP1 (epithelial membrane protein 1) is significantly active not only in CCl₄ (carbon tetrachloride)-treated mouse liver fibrosis but also in BDL (bile duct ligation)-induced liver fibrosis and even in human fibrotic liver tissues such as alcoholic hepatitis, NASH (nonalcoholic steatohepatitis), and advanced stage liver fibrosis. Furthermore, we demonstrated that EMP1 is a specific fibrotic gene expressed in HSCs (hepatic stellate cells) and endothelial cells using the Protein Atlas single-cell transcriptome RNA-sequencing clustering. Its expression was significantly elevated in fibrotic HSCs or CCl₄ and NASH-induced fibroblasts. Previous research revealed that EMP1 plays a role in proliferation, migration, metastasis, and tumorigeneses in different cancers via a variety of mechanisms. Because HSC activation and proliferation are two important steps following liver injury, it would be interesting to investigate the role of EMP1 in these processes. All of this information suggested that EMP1 could be used as a novel fibrotic liver marker and a possible target in the future.

Loss of EMP1 promotes the metastasis of human bladder cancer cells by promoting migration and conferring resistance to ferroptosis through activation of PPAR gamma signaling

Metastasis, in which cancer cells detach from the original site and colonise other organs, is the primary cause of death induced by bladder cancer (BCa). Epithelial Membrane Protein 1 (EMP1) is dysregulated in many human cancers, and its clinical significance and biological function in diseases, including BCa, are largely unclear. Here, we demonstrated that EMP1 was downregulated in BCa cells. The deficiency of EMP1 promotes migration and confers resistance to ferroptosis/oxidative stress in BCa cells, favouring tumour cell metastasis. Mechanistically, we demonstrated that EMP1 deficiency enhanced tumour metastasis by increasing PPARG expression and promoting its activation, leading to upregulation of pFAK(Y397) and SLC7A11, which promoted cell migration and anti-ferroptotic cell death respectively. Moreover, we found EMP1-deficient sensitized cells to PPARG's ligand, which effect are metastatic phenotype promoted and could be mitigated by FABP4 knockdown. In conclusion, our study, for the first time, reveals that EMP1 deficiency promotes BCa cell migration and confers resistance to ferroptosis/oxidative stress, thus promoting metastasis of BCa via PPARG. These results revealed a novel role of EMP1-mediated PPARG in bladder cancer metastasis.

Epithelial Membrane Protein 1 Promotes Sensitivity to RSL3-Induced Ferroptosis and Intensifies Gefitinib Resistance in Head and Neck Cancer

Epithelial membrane protein (EMP1), a member of the peripheral myelin protein (PMP22) family, is involved in the development of various human malignancies. However, the expression level of EMP1 and its functional role in head and neck squamous cell carcinoma (HNSCC) remain unclear to date. Ferroptosis, a newly characterized form of regulated cell death, plays an essential role in tumorigenesis. In this study, we aimed to investigate the expression levels of EMP1 in HNSCC and normal tissues, as well as to identify the function of EMP1 in regulating ferroptosis during the progression of HNSCC. To further explore the biological function of EMP1 in vitro, transient transfection was used to overexpress EMP1 in the HNSCC cell lines Hep2 and Detroit562. Functionally, our results indicated that EMP1 overexpression could not affect the initiation of ferroptosis directly but reinforced RSL3-induced ferroptosis on HNSCC cells. Furthermore, mechanical study indicated that EMP1 mediated the ferroptosis via cell density-regulated Hippo-TAZ pathway and regulated the expression of Rac1 and NOX1. In addition, our study demonstrated that EMP1 overexpression could promote gefitinib resistance by targeting the MAPK pathway. In summary, our findings indicate that EMP1 may act as an oncogene and serve as a therapeutic target against malignant progression of HNSCC.

Serum epithelial membrane protein 1 serves as a feasible biomarker in extrahepatic cholangiocarcinoma

BACKGROUND

Extrahepatic cholangiocarcinoma is a malignancy that originates from bile duct epithelium with an unfavorable prognosis. Epithelial membrane protein 1 was first discovered in 1995, functioning as an oncogene or anti-tumor gene in various cancers. However, the clinical role of epithelial membrane protein 1 extrahepatic cholangiocarcinoma remained unclear.

METHODS

Differentially expressed genes were identified using Gene Ontology and the Kyoto Encyclopedia and Genomes pathway analysis. Out of 183 extrahepatic cholangiocarcinoma patients and 61 healthy controls, the expression level of epithelial membrane protein 1 was detected and compared using reverse transcription-quantitative polymerase chain reaction analysis and western blot assay. Meanwhile, the diagnosis and prognosis of EMP1 in ECCA were measured by receiver operating characteristic and Kaplan-Meier analysis. Finally, the relationship between epithelial membrane protein 1 expression and clinicopathological indexes were compared to further verify the clinical role of epithelial membrane protein 1 in extrahepatic cholangiocarcinoma.

RESULTS

After analyzing data from GSE76297, GSE89749, and GSE26566GO, we found 1554 down-regulated and 1065 up-regulated genes. Through Gene Ontology and Kyoto Encyclopedia and Genomes analysis, extracellular matrix organization, extracellular structure organization, cholesterol metabolism, interleukin-17 signaling pathway, and vitamin digestion and absorption were significantly enriched and involved in targeted differentially expresses genes. Epithelial membrane protein 1 messenger ribonucleic acid was notably decreased in serum samples from extrahepatic cholangiocarcinoma patients, compared with that in healthy controls. Receiver operating characteristic analysis revealed that the area under the curve of epithelial membrane protein 1 messenger ribonucleic acid for the diagnosis of extrahepatic cholangiocarcinoma was 0.9281 (95% CI = 0.8967-0.9595). Moreover, the correlation analysis presented that epithelial membrane protein 1 expression was negatively correlated with lymph node metastasis, tumour node metastasis stage, cancer antigen 19-9 level, and carcinoembryonic antigen level.

CONCLUSION

Aberrant expression of epithelial membrane protein 1 contributed to distinguishing extrahepatic cholangiocarcinoma patients and healthy controls, and a low expression level of epithelial membrane protein 1 indicated an unfavorable prognosis. Hence, epithelial membrane protein 1 was a feasible and credible biomarker for extrahepatic cholangiocarcinoma diagnosis and prognosis, with high accuracy, sensitivity, and specificity.

RNA sequencing of long-term label-retaining colon cancer stem cells identifies novel regulators of quiescence

Recent data suggest that therapy-resistant quiescent cancer stem cells (qCSCs) are the source of relapse in colon cancer. Here, using colon cancer patient-derived organoids and xenografts, we identify rare long-term label-retaining qCSCs that can re-enter the cell cycle to generate new tumors. RNA sequencing analyses demonstrated that these cells display the molecular hallmarks of quiescent tissue stem cells, including expression of p53 signaling genes, and are enriched for transcripts common to damage-induced quiescent revival stem cells of the regenerating intestine. In addition, we identify negative regulators of cell cycle, downstream of p53, that we show are indicators of poor prognosis and may be targeted for qCSC abolition in both p53 wild-type and mutant tumors. These data support the temporal inhibition of downstream targets of p53 signaling, in combination with standard-of-care treatments, for the elimination of qCSCs and prevention of relapse in colon cancer.

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Colon tumors contain therapy-resistant quiescent cancer stem cells (qCSCs)

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qCSC gene expression mirrors that of quiescent stem cells of the regenerating gut

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qCSCs are enriched for p53 signaling genes

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qCSC elimination may be achieved by inhibiting downstream targets of p53 signaling

Epithelial Membrane Protein 2 Suppresses Non-Small Cell Lung Cancer Cell Growth by Inhibition of MAPK Pathway

Epithelial membrane proteins (EMP1-3) are involved in epithelial differentiation and carcinogenesis. Dysregulated expression of EMP2 was observed in various cancers, but its role in human lung cancer is not yet clarified. In this study, we analyzed the expression of EMP1-3 and investigated the biological function of EMP2 in non-small cell lung cancer (NSCLC). The results showed that lower expression of EMP1 was significantly correlated with tumor size in primary lung tumors (p = 0.004). Overexpression of EMP2 suppressed tumor cell growth, migration, and invasion, resulting in a G1 cell cycle arrest, with knockdown of EMP2 leading to enhanced cell migration, related to MAPK pathway alterations and disruption of cell cycle regulatory genes. Exosomes isolated from transfected cells were taken up by tumor cells, carrying EMP2-downregulated microRNAs (miRNAs) which participated in regulation of the tumor microenvironment. Our data suggest that decreased EMP1 expression is significantly related to increased tumor size in NSCLC. EMP2 suppresses NSCLC cell growth mainly by inhibiting the MAPK pathway. EMP2 might further affect the tumor microenvironment by regulating tumor microenvironment-associated miRNAs.

MicroRNA-95-3p serves as a contributor to cisplatin resistance in human gastric cancer cells by targeting EMP1/PI3K/AKT signaling

MicroRNAs (miRNAs) are thought to be involved in the development of cisplatin (DDP) resistance in gastric cancer (GC). Using RNA sequencing analysis (RNA-seq), we found that miR-95-3p is associated with DDP resistance in GC. We discovered that miR-95-3p is highly expressed in DDP-resistant GC tissues and cell lines (SGC7901/DDP and AGS/DDP). Furthermore, results from the BrdU and MTT assays indicated that miR-95-3p promotes GC cell proliferation. Additionally, data from transwell chamber assay, wound healing test and in vivo experiments illustrated that miR-95-3p can effectively promote invasion, migration and tumorigenic capacity, respectively, of DDP-resistant GC cells. Subsequently, results from dual luciferase assay and qRT-PCR collectively indicated that EMP1 is a target of miR-95-3p with inhibitory function through suppression of the EMT process and drug-resistance proteins. Furthermore, PI3K/AKT was identified as a downstream pathway of miR-95-3p, which promotes DDP resistance in GC. In summary, miR-95-3p helped develop DDP-resistance through down-regulation of EMP1 and increasing phosphorylation of the PI3K/Akt pathway in GC.

High expression of EMP1 predicts a poor prognosis and correlates with immune infiltrates in bladder urothelial carcinoma

Epithelial membrane protein 1 (EMP1) is a key gene that regulates cell proliferation and metastatic capability in various types of cancer, and serves an important role in tumor-immune interactions. However, the association between EMP1 and clinical prognosis, as well as the presence of tumor-infiltrating lymphocytes in bladder urothelial carcinoma (BLCA) remains unclear. The present study aimed to explore the relationship between EMP1 expression and tumor immune cell infiltration in BLCA. In the present study, EMP1 expression in BLCA was analyzed using the Oncomine database, The Cancer Genome Atlas (TCGA) and the Tumor Immune Estimation Resource (TIMER). The effects of EMP1 on clinical prognosis were evaluated using the Kaplan-Meier plotter and Gene Expression Profiling Interactive Analysis. The correlations between EMP1, cancer immune infiltrates and lymphocyte abundance were determined using the TIMER and Tumor immune system interaction database. In addition, correlations between EMP1 expression and gene markers in immune infiltrates were analyzed using cBioportal. The results demonstrated that, compared with adjacent normal tissues, EMP1 was downregulated in BLCA tissues. High expression of EMP1 was significantly associated with poor overall survival (OS) in BLCA cases obtained from TCGA. Multivariate Cox analysis revealed that EMP1 was an independent predictor of OS in patients with BLCA. Gene set enrichment analysis revealed that EMP1 was associated with cancer-related pathways and was positively correlated with the levels of infiltrating CD8⁺ T cells, macrophages, neutrophils and dendritic cells in BLCA. Further analysis demonstrated that EMP1 was significantly associated with the enrichment of multiple types of lymphocyte. EMP1 expression exhibited a strong correlation with a range of immune markers in BLCA. In conclusion, the results of the present study demonstrated that EMP1 was associated with a poor prognosis in patients with BLCA, and that the levels of immune infiltration and multiple immunomarker groups were associated with EMP1 expression. These results suggested that EMP1 may be used as a predictive biomarker to determine the prognosis and immune infiltration in BLCA.

The Pivotal Roles of the Epithelial Membrane Protein Family in Cancer Invasiveness and Metastasis

The members of the family of epithelial membrane proteins (EMPs), EMP1, EMP2, and EMP3, possess four putative transmembrane domain structures and are composed of approximately 160 amino acid residues. EMPs are encoded by the growth arrest-specific 3 (GAS3)/peripheral myelin protein 22 kDa (PMP22) gene family. The GAS3/PMP22 family members play roles in cell migration, growth, and differentiation. Evidence indicates an association of these molecules with cancer progression and metastasis. Each EMP has pro- and anti-metastatic functions that are likely involved in the complex mechanisms of cancer progression. We have recently demonstrated that the upregulation of EMP1 expression facilitates cancer cell migration and invasion through the activation of a small GTPase, Rac1. The inoculation of prostate cancer cells overexpressing EMP1 into nude mice leads to metastasis to the lymph nodes and lungs, indicating that EMP1 contributes to metastasis. Pro-metastatic properties of EMP2 and EMP3 have also been proposed. Thus, targeting EMPs may provide new insights into their clinical utility. Here, we highlight the important aspects of EMPs in cancer biology, particularly invasiveness and metastasis, and describe recent therapeutic approaches.

The Hippo Pathway Effector TAZ Regulates Ferroptosis in Renal Cell Carcinoma

Despite recent advances, the poor outcomes in renal cell carcinoma (RCC) suggest novel therapeutics are needed. Ferroptosis is a form of regulated cell death, which may have therapeutic potential toward RCC; however, much remains unknown about the determinants of ferroptosis susceptibility. We found that ferroptosis susceptibility is highly influenced by cell density and confluency. Because cell density regulates the Hippo-YAP/TAZ pathway, we investigated the roles of the Hippo pathway effectors in ferroptosis. TAZ is abundantly expressed in RCC and undergoes density-dependent nuclear or cytosolic translocation. TAZ removal confers ferroptosis resistance, whereas overexpression of TAZS89A sensitizes cells to ferroptosis. Furthermore, TAZ regulates the expression of Epithelial Membrane Protein 1 (EMP1), which, in turn, induces the expression of nicotinamide adenine dinucleotide phosphate (NADPH) Oxidase 4 (NOX4), a renal-enriched reactive oxygen species (ROS)-generating enzyme essential for ferroptosis. These findings reveal that cell density-regulated ferroptosis is mediated by TAZ through the regulation of EMP1-NOX4, suggesting its therapeutic potential for RCC and other TAZ-activated tumors.

EMP1 regulates cell proliferation, migration, and stemness in gliomas through PI3K-AKT signaling and CD44

Glioblastoma multiforme (GBM) is an intracranial tumor; the feature is higher malignant and poorer prognosis. The search for therapeutic targets for gliomas has always been a focus of research in the field of neurology. The unusual expression of epithelial membrane protein 1 (EMP1) has been proved in most tumors. In our study, we determined the expression level of EMP1 expression in glioma tissues. There were higher levels of EMP1 in glioma tissues-particularly GBM tissues-than those in normal brain tissues. Then we discovered that silencing EMP1 inhibited glioma cell invasion and proliferation through inhibiting the PI3K-AKT signaling pathway. Subsequently, we investigated the function of EMP1 on glioma stem cells and found that it regulates the expression of CD44 in such cells to promote stemness. Taken together, the new strategies for the treatment of glioma may be provided by these finding, thereby improving the prognosis associated with it.

Epithelial membrane protein 1 promotes tumor metastasis by enhancing cell migration via copine-III and Rac1

Tumor metastasis is the most common cause of cancer death. Elucidation of the mechanism of tumor metastasis is therefore important in the development of novel, effective anti-cancer therapies to reduce cancer mortality. Interaction between cancer cells and surrounding stromal cells in the tumor microenvironment is a key factor in tumor metastasis. Using a co-culture assay system with human prostate cancer LNCaP cells and primary human prostate stromal cells, we identified epithelial membrane protein 1 (EMP1) as a gene with elevated expression in the cancer cells. The orthotopic injection of LNCaP cells overexpressing EMP1 (EMP1-LNCaP cells) into the prostate of nude mice induced lymph node and lung metastases, while that of control LNCaP cells did not. EMP1-LNCaP cells had higher cell motility and Rac1 activity than control LNCaP cells. These results were also observed in other lines of cancer cells. We newly identified copine-III as an intracellular binding partner of EMP1. Knockdown of copine-III attenuated the increased cell motility and Rac1 activity in EMP1-LNCaP cells. Reduced cell motility and Rac1 activity following knockdown of copine-III in EMP1-LNCaP cells were recovered by re-expression of wild-type copine-III, but not of a copine-III mutant incapable of interacting with EMP1, suggesting the importance of the EMP1–copine-III interaction. Phosphorylated and activated Src and a Rac guanine nucleotide exchange factor Vav2 were found to be involved in the EMP1-induced enhancement of cell motility and Rac1 activation. Moreover, EMP1 was highly expressed in prostate cancer samples obtained from patients with higher Gleason score. These results demonstrate that upregulation of EMP1 significantly increases cancer cell migration that leads to tumor metastasis, suggesting that EMP1 may play an essential role as a positive regulator of tumor metastasis.

The effects of restricted glycolysis on stem-cell like characteristics of breast cancer cells

Altered glycolysis is a characteristic of many cancers, and can also be associated with changes in stem cell-like cancer (SCLC) cell populations. We therefore set out to directly examine the effect of glycolysis on SCLC cell phenotype, using a model where glycolysis is stably reduced by adapting the cells to a sugar source other than glucose. Restricting glycolysis using this approach consistently resulted in cells with increased oncogenic potential; including an increase in SCLC cells, proliferation in 3D matrigel, invasiveness, chemoresistance, and altered global gene expression. Tumorigenicity in vivo was also markedly increased. SCLC cells exhibited increased dependence upon alternate metabolic pathways. They also became c-KIT dependent, indicating that their apparent state of maturation is regulated by glycolysis. Single-cell mRNA sequencing identified altered networks of metabolic-, stem- and signaling- gene expression within SCLC-enriched populations in response to glycolytic restriction. Therefore, reduced glycolysis, which may occur in niches within tumors where glucose availability is limiting, can promote tumor aggressiveness by increasing SCLC cell populations, but can also introduce novel, potentially exploitable, vulnerabilities in SCLC cells.

Synthesis and photophysical properties of a fluorescent cyanoquinoline probe for profiling ERBB2 kinase inhibitor response

A fluorescent probe targeting the ERBB2 receptor tyrosine was designed, synthesized and evaluated as reporter of ERBB2 dynamics in overexpressing BT474, i.e. Her2(+), cells. Two cyanoquinazoline (CQ) probes modeled after type-I (CQ1) or active state and type-II (CQ2) or inactive state inhibitors were designed and synthesized with extended π systems that impart binding-induced, turn-on fluorescence. Solution spectroscopy revealed that CQ1 exhibited attractive photophysical properties and displayed turn-on emission in the presence of purified, soluble ERBB2 kinase domain, while CQ2 was found to be non-emissive, likely due to quenching via a photoinduced electron transfer mechanism. Live cell imaging with CQ1 revealed that this probe targeted an intracellular population of ERBB2, which increased following treatment with type-I inhibitors, gefinitib and canertinib, but showed no response to type-II inhibitors. CQ1 thus provides a novel means of imaging the dynamic response of ERBB2(+) cells to kinase inhibitors.

EMP1, EMP 2, and EMP3 as novel therapeutic targets in human cancer

The epithelial membrane protein genes 1, 2, and 3 (EMP1, EMP2, and EMP3) belong to the peripheral myelin protein 22-kDa (PMP22) gene family, which consists of at least seven members: PMP22, EMP1, EMP2, EMP3, PERP, brain cell membrane protein 1, and MP20. This review addresses the structural and functional features of EMPs, detailing their tissue distribution and functions in the human body, their expression pattern in a variety of tumors, and highlighting the underlying mechanisms involved in carcinogenesis. The implications in cancer biology, patient prognosis prediction, and potential application in disease therapy are discussed. For example, EMP1 was reported to be a biomarker of gefitinib resistance in lung cancer and contributes to prednisolone resistance in acute lymphoblastic leukemia patients. EMP2 functions as an oncogene in human endometrial and ovarian cancers; however, characteristics of EMP2 in urothelial cancer fulfill the criteria of a suppressor gene. Of particular interest, EMP3 overexpression in breast cancer is significantly related to strong HER-2 expression. Co-expression of HER-2 and EMP3 is the most important indicator of progression-free and metastasis-free survival for patients with urothelial carcinoma of the upper urinary tract. Altogether, discovery of pharmacological inhibitors and/or regulators of EMP protein activity could open novel strategies for enhanced therapy against EMP-mediated human diseases.

Gene Expression Profiling in Peripheral Blood Cells and Synovial Membranes of Patients with Psoriatic Arthritis

Background

Psoriatic arthritis (PsA) is an inflammatory arthritis whose pathogenesis is poorly understood; it is characterized by bone erosions and new bone formation. The diagnosis of PsA is mainly clinical and diagnostic biomarkers are not yet available. The aim of this work was to clarify some aspects of the disease pathogenesis and to identify specific gene signatures in paired peripheral blood cells (PBC) and synovial biopsies of patients with PsA. Moreover, we tried to identify biomarkers that can be used in clinical practice.

Methods

PBC and synovial biopsies of 10 patients with PsA were used to study gene expression using Affymetrix arrays. The expression values were validated by Q-PCR, FACS analysis and by the detection of soluble mediators.

Results

Synovial biopsies of patients showed a modulation of approximately 200 genes when compared to the biopsies of healthy donors. Among the differentially expressed genes we observed the upregulation of Th17 related genes and of type I interferon (IFN) inducible genes. FACS analysis confirmed the Th17 polarization. Moreover, the synovial trascriptome shows gene clusters (bone remodeling, angiogenesis and inflammation) involved in the pathogenesis of PsA. Interestingly 90 genes are modulated in both compartments (PBC and synovium) suggesting that signature pathways in PBC mirror those of the inflamed synovium. Finally the osteoactivin gene was upregulared in both PBC and synovial biopsies and this finding was confirmed by the detection of high levels of osteoactivin in PsA sera but not in other inflammatory arthritides.

Conclusions

We describe the first analysis of the trancriptome in paired synovial tissue and PBC of patients with PsA. This study strengthens the hypothesis that PsA is of autoimmune origin since the coactivity of IFN and Th17 pathways is typical of autoimmunity. Finally these findings have allowed the identification of a possible disease biomarker, osteoactivin, easily detectable in PsA serum.

EMP1, a novel poor prognostic factor in pediatric leukemia regulates prednisolone resistance, cell proliferation, migration and adhesion

Still 20% of pediatric acute lymphoblastic leukemia (ALL) patients relapse on or after current treatment strategies. Treatment failure is associated with resistance to prednisolone. We aimed to find new druggable targets that modulate prednisolone resistance. We generated microarray gene expression profiles of 256 pediatric ALL patient samples and identified a 3.4-fold increase in epithelial membrane protein 1 (EMP1) expression in in vitro prednisolone-resistant compared with -sensitive patients (P=0.003). EMP1 silencing in six precursor-B ALL (BCP-ALL) and T-ALL cell lines induced apoptosis and cell-cycle arrest leading to 84.1±4.5% reduction in survival compared with non-silencing control transduced cells (non-silencing control short hairpin, shNSC) (P=0.014). Moreover, EMP1 silencing sensitized to prednisolone up to 18.8-fold (P<0.001). EMP1 silencing also abrogated migration and adhesion to mesenchymal stromal cells (MSCs) by 78.3±9.0 and 29.3±4.1% compared with shNSC (P<0.05). We discovered that EMP1 contributes to MSC-mediated prednisolone resistance. Pathway analysis indicated that EMP1 signals through the Src kinase family. EMP1-high BCP-ALL patients showed a poorer 5-year event-free survival compared with EMP1-low patients (77±2 vs. 89±2%, P=0.003). Multivariate analysis taking along white blood cell count, age, prednisolone resistance and subtype identified EMP1 as an independent predictor for poor outcome in BCP-ALL (P=0.004, hazard ratio: 2.36 (1.31-4.25). This study provides preclinical evidence that EMP1 is an interesting candidate for drug development to optimize treatment of BCP-ALL.

MicroRNA-147 induces a mesenchymal-to-epithelial transition (MET) and reverses EGFR inhibitor resistance

Background

The epithelial-mesenchymal transition (EMT) is a key developmental program that is often activated during cancer progression and may promote resistance to therapy. An analysis of patients (n = 71) profiled with both gene expression and a global microRNA assessment (∼415 miRs) identified miR-147 as highly anti-correlated with an EMT gene expression signature score and postulated to reverse EMT (MET).

Methods and Findings

miR-147 was transfected into colon cancer cells (HCT116, SW480) as well as lung cancer cells (A-549). The cells were assessed for morphological changes, and evaluated for effects on invasion, motility, and the expression of key EMT markers. Resistance to chemotherapy was evaluated by treating cells with gefitinib, an EGFR inhibitor. The downstream genes regulated by miR-147 were assayed using the Affymetrix GeneChip U133 Plus2.0 platform. miR-147 was identified to: 1. cause MET primarily by increasing the expression of CDH1 and decreasing that of ZEB1; 2. inhibit the invasion and motility of cells; 3. cause G1 arrest by up-regulating p27 and down-regulating cyclin D1. miR-147 also dramatically reversed the native drug resistance of the colon cancer cell line HCT116 to gefitinib. miR-147 significantly repressed Akt phosphorylation, and knockdown of Akt with siRNA induced MET. The morphologic effects of miR-147 on cells appear to be attenuated by TGF-B1, promoting a plastic and reversible transition between MET and EMT.

Conclusion

miR-147 induced cancer cells to undergo MET and induced cell cycle arrest, suggesting a potential tumor suppressor role. miR-147 strikingly increased the sensitivity to EGFR inhibitor, gefitinib in cell with native resistance. We conclude that miR-147 might have therapeutic potential given its ability to inhibit proliferation, induce MET, as well as reverse drug sensitivity.

The homeobox only protein homeobox (HOPX) and colorectal cancer

The HOP (homeobox only protein) homeobox (HOPX) is most closely related to the homeobox protein that contains a homeobox-like domain but lacks certain conserved residues required for DNA binding. Here, we review the current understanding of HOPX in the progression of colorectal cancer (CRC). HOPX was initially reported as a differentiation marker and is expressed in various normal tissues. In the colon, HOPX is expressed uniquely in the quiescent stem cell, +4, and in differentiated mucosal cells of the colon. HOPX expression is markedly suppressed in a subset of cancers, mainly in an epigenetic manner. CRC may include separate entities which are differentially characterized by HOPX expression from a prognostic point of view. HOPX itself can regulate epigenetics, and defective expression of HOPX can result in loss of tumor suppressive function and differentiation phenotype. These findings indicate that HOPX may be both a central regulator of epigenetic dynamics and a critical determinant for differentiation in human cells. HOPX downstream targets were identified in CRC cell lines and hold promise as candidates for therapeutic targets of CRC, such as EphA2 or AP-1. Further analysis will elucidate and confirm the precise role of such proteins in CRC progression.

Claudin-20 promotes an aggressive phenotype in human breast cancer cells

Claudin-20 is a member of the Claudin family of transmembrane proteins located in the tight junction (TJ) of cells of epithelial origin. Due to the increasing evidence supporting the role of TJ proteins in preventing tumor cell metastatic behavior, this study sought to evaluate the distribution of Claudin-20 in human breast cancer and the effect of Claudin-20 overexpression in human breast cancer cells. Q-PCR data from breast cancer primary tumors (n = 114) and matched background tissue (n = 30) showed that high claudin-20 expression was correlated with poor survival of patients with breast cancer (p = 0.022). Following transformation of the breast cancer cell lines MDA-MB-231 and MCF7 with a Claudin-20 expression construct functional assays were performed to ascertain changes in cell behavior. Claudin-20 transformed cells showed significantly increased invasion (p &lt; 0.005) and were significantly less adhesive than wild type cells (p &lt; 0.05). There was no effect on growth (either in vitro or in vivo) for either cell line. Overexpression of Claudin-20 resulted in reduced transepithelial resistance (induced by the motogen HGF at 25 ng/ml, p = 0.0007). Interestingly, this was not mirrored by paracellular permeability, as overexpression of Claudin-20 caused a decrease in permeability. The introduction of Claudin-20 into human breast cancer cells resulted in breast cancer cells with an aggressive phenotype and reduced trans-epithelial resistance. There was no corresponding decrease in paracellular permeability, indicating that this Claudin has a differential function in epithelial TJ. This provides further insight into the importance of correctly functioning TJ in preventing the progression of human breast cancer.

Differences and similarities in the transcriptional profile of peripheral whole blood in early and late-onset preeclampsia: insights into the molecular basis of the phenotype of preeclampsiaa

OBJECTIVE

Preeclampsia (PE) can be sub-divided into early- and late-onset phenotypes. The pathogenesis of these two phenotypes has not been elucidated. To gain insight into the mechanisms of disease, the transcriptional profiles of whole blood from women with early- and late-onset PE were examined.

METHODS

A cross-sectional study was conducted to include women with: i) early-onset PE (diagnosed prior to 34 weeks, n=25); ii) late-onset PE (after 34 weeks, n=47); and iii) uncomplicated pregnancy (n=61). Microarray analysis of mRNA expression in peripheral whole blood was undertaken using Affymetrix microarrays. Differential gene expression was evaluated using a moderated t-test (false discovery rate <0.1 and fold change >1.5), adjusting for maternal white blood cell count and gestational age. Validation by real-time qRT-PCR was performed in a larger sample size [early PE (n=31), late PE (n=72) and controls (n=99)] in all differentially expressed genes. Gene ontology analysis and pathway analysis were performed.

RESULTS

i) 43 and 28 genes were differentially expressed in early- and late-onset PE compared to the control group, respectively; ii) qRT-PCR confirmed the microarray results for early and late-onset PE in 77% (33/43) and 71% (20/28) of genes, respectively; iii) 20 genes that are involved in coagulation (SERPINI2), immune regulation (VSIG4, CD24), developmental process (H19) and inflammation (S100A10) were differentially expressed in early-onset PE alone. In contrast, only seven genes that encoded proteins involved in innate immunity (LTF, ELANE) and cell-to-cell recognition in the nervous system (CNTNAP3) were differentially expressed in late-onset PE alone. Thirteen genes that encode proteins involved in host defense (DEFA4, BPI, CTSG, LCN2), tight junctions in blood-brain barrier (EMP1) and liver regeneration (ECT2) were differentially expressed in both early- and late-onset PE.

CONCLUSION

Early- and late-onset PE are characterized by a common signature in the transcriptional profile of whole blood. A small set of genes were differentially regulated in early- and late-onset PE. Future studies of the biological function, expression timetable and protein expression of these genes may provide insight into the pathophysiology of PE.

Acquired resistance of non-small cell lung cancer to epidermal growth factor receptor tyrosine kinase inhibitors

Activation of epidermal growth factor receptor (EGFR) triggers anti-apoptotic signaling, proliferation, angiogenesis, invasion, metastasis, and drug resistance, which leads to development and progression of human epithelial cancers, including non-small cell lung cancer (NSCLC). Inhibition of EGFR by tyrosine kinase inhibitors such as gefitinib and erlotinib has provided a new hope for the cure of NSCLC patients. However, acquired resistance to gefitinib and erlotinib via EGFR-mutant NSCLC has occurred through various molecular mechanisms such as T790M secondary mutation, MET amplification, hepatocyte growth factor (HGF) overexpression, PTEN downregulation, epithelial-mesenchymal transition (EMT), and other mechanisms. This review will discuss the biology of receptor tyrosine kinase inhibition and focus on the molecular mechanisms of acquired resistance to tyrosine kinase inhibitors of EGFR-mutant NSCLC.

Down-regulation of EMP1 is associated with epithelial hyperplasia and metaplasia in nasal polyps

AIMS

The aim of this study was to assess protein and mRNA expression of epithelial membrane protein 1 (EMP1) in the nasal mucosa of patients with nasal polyps (NP), and to determine what changes occur in response to glucocorticosteroid (GC) treatment.

METHODS AND RESULTS

NP tissue was obtained from 55 patients, 18 of whom were treated with nasal GCs (i.e. these 18 patients had NP biopsies taken before and after treatment). Biopsies of inferior turbinate mucosa from 30 healthy subjects were used as controls. Quantitative PCR and immunohistochemistry were performed to determine the expression levels of EMP1. EMP1 mRNA expression was significantly lower (2.77-fold) in tissues from NP patients before GC treatment when compared to controls, but was increased in these patients after GC treatment. EMP1 staining in nasal epithelium co-localized with both basal (p63(+)) and differentiated (CK18(+)) epithelial cells. Their immunoreactivity was significantly greater in controls than NP patients. EMP1 mRNA levels were lower in the epithelium with severe hyperplasia (1.79-fold) or with metaplasia (1.85-fold) as compared to those with mild to moderate hyperplasia or non-metaplastic epithelium, respectively. Positive correlations between EMP1 and other epithelial cell-related gene (e.g. JUN, PTGS2, AREG etc.) mRNAs were observed.

CONCLUSIONS

EMP1 could be a biomarker for aberrant epithelial remodelling and metaplasia in chronic inflammatory upper airway mucosa (e.g. NP).

Knockdown of the Bcl-2 gene increases sensitivity to EGFR tyrosine kinase inhibitors in the H1975 lung cancer cell line harboring T790M mutation

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are being widely used as targeted therapy in non-small cell lung cancer (NSCLC), but most cases acquire drug-resistance in 9 months. However, the mechanisms of resistance are still not fully understood. Since it has been demonstrated that EGFR-TKI-mediated repression of downstream signaling cascades and apoptosis induction is a key mechanism through which EGFR-TKIs exert their cytotoxic effects, we reasoned that activation of downstream signaling pathways and changes in the expression of apoptosis-related proteins contribute to the acquired resistance to EGFR-TKIs. We analyzed the protein levels of p-Akt, Bcl-2, Bax between gefitinib-sensitive and gefitinib-resistant lung cancer cell lines and evaluated whether targeting the anti-apoptotic protein Bcl-2 induces cell apoptosis and further sensitizes resistant H1975 cells to gefitinib. The data showed that p-Akt was activated and accompanied by substantial Bcl-2 in the H1975 lung cancer cell line, whereas no evidence was observed in HCC827 cells. Using small interfering RNA (siRNA) to silence Bcl-2 in H1975 cells led to significant downregulation of Bcl-2 protein expression, decreased cell viability in vitro and induced intrinsic apoptosis confirmed by flow cytometry and PARP cleavage. In Bcl-2 siRNA-transfected cells, adding gefitinib further reduced the number of viable cells, induced apoptosis to a greater extent compared to either treatment alone. These preclinical data suggested that downregulation of Bcl-2 by RNAi in the gefitinib-resistant H1975 lung cancer cell line with T790M mutation enhanced the effects of gefitinib and may offer a novel therapeutic strategy for the treatment of NSCLC.

EMP-1 promotes tumorigenesis of NSCLC through PI3K/AKT pathway

This study examined the role of EMP-1 in tumorigenesis of non-small cell lung carcinoma (NSCLC) and the possible mechanism. Specimens were collected from 28 patients with benign lung diseases and 28 with NSCLC, and immunohistochemically detected to evaluate the correlation of EMP-1 expression to the clinical features of NSCLC. Recombinant adenovirus was constructed to over-express EMP-1 and then infect PC9 cells. Cell proliferation was measured by Ki67 staining. Western blotting was performed to examine the effect of EMP-1 on the PI3K/AKT signaling. Moreover, tumor xenografts were established by subcutaneous injection of PC9 cell suspension (about 5×10(7)/mL in 100 μL of PBS) into the right hind limbs of athymic nude mice. The results showed EMP-1 was significantly up-regulated in NSCLC patients as compared with those with benign lung diseases. Over-expression of EMP-1 promoted proliferation of PC9 cells, which coincided with the activation of the PI3K/AKT pathway. EMP-1 promoted the growth of xenografts of PC9 cells in athymic nude mice. It was concluded that EMP-1 expression may contribute to the development and progress of NSCLC by activating PI3K/AKT pathway.

The somatostatin analogue octreotide inhibits growth of small intestine neuroendocrine tumour cells

Octreotide is a widely used synthetic somatostatin analogue that significantly improves the management of neuroendocrine tumours (NETs). Octreotide acts through somatostatin receptors (SSTRs). However, the molecular mechanisms leading to successful disease control or symptom management, especially when SSTRs levels are low, are largely unknown. We provide novel insights into how octreotide controls NET cells. CNDT2.5 cells were treated from 1 day up to 16 months with octreotide and then were profiled using Affymetrix microarray analysis. Quantitative real-time PCR and western blot analyses were used to validate microarray profiling in silico data. WST-1 cell proliferation assay was applied to evaluate cell growth of CNDT2.5 cells in the presence or absence of 1 µM octreotide at different time points. Moreover, laser capture microdissected tumour cells and paraffin embedded tissue slides from SI-NETs at different stages of disease were used to identify transcriptional and translational expression. Microarrays analyses did not reveal relevant changes in SSTR expression levels. Unexpectedly, six novel genes were found to be upregulated by octreotide: annexin A1 (ANXA1), rho GTPase-activating protein 18 (ARHGAP18), epithelial membrane protein 1 (EMP1), growth/differentiation factor 15 (GDF15), TGF-beta type II receptor (TGFBR2) and tumour necrosis factor (ligand) superfamily member 15 (TNFSF15). Furthermore, these novel genes were expressed in tumour tissues at transcript and protein levels. We suggest that octreotide may use a potential novel framework to exert its beneficial effect as a drug and to convey its action on neuroendocrine cells. Thus, six novel genes may regulate cell growth and differentiation in normal and tumour neuroendocrine cells and have a role in a novel octreotide mechanism system.

Array-based pharmacogenomics of molecular-targeted therapies in oncology

The advent of microarrays over the past decade has transformed the way genome-wide studies are designed and conducted, leading to an unprecedented speed of acquisition and amount of new knowledge. Microarray data have led to the identification of molecular subclasses of solid tumors characterized by distinct oncogenic pathways, as well as the development of multigene prognostic or predictive models equivalent or superior to those of established clinical parameters. In the field of molecular-targeted therapy for cancer, in particular, the application of array-based methodologies has enabled the identification of molecular targets with 'key' roles in neoplastic transformation or tumor progression and the subsequent development of targeted agents, which are most likely to be active in the specific molecular setting. Herein, we present a summary of the main applications of whole-genome expression microarrays in the field of molecular-targeted therapies for solid tumors and we discuss their potential in the clinical setting. An emphasis is given on deciphering the molecular mechanisms of drug action, identifying novel therapeutic targets and suitable agents to target them with, and discovering molecular markers/signatures that predict response to therapy or optimal drug dose for each patient.

MS-based glycomic strategies for probing the structural details of polylactosaminoglycan chain on N-glycans and glycoproteomic identification of its protein carriers

Most MS-based glycomic and glycoproteomic analyses focus on identifying changes in terminal glyco-epitopes represented by sialylation and fucosylation at specific positions of the terminal N-acetyllactosamine units. Much less attention was accorded to the underlying linear or branched poly-N-acetyllactosamine extension from the N-glycan trimannosyl core other than a simple inference of its presence due to mass data and hence glycosyl compositional assignment. Using the EA.hy926 cell line derived from human umbilical vein endothelial cells (HUVEC), we have systematically investigated the MALDI- and ESI-MS-based methodologies for probing the structural details of endothelial polylactosaminoglycans at both MS and MS(2) levels in conjunction with the use of endo-β-galactosidase to identify branching motifs and initiation sites. We showed that the polylactosaminoglycan chains on the N-glycans of EA.hy926 were less sialylated and fucosylated but more extended and branched than those of human umbilical vein endothelial cells, thus demonstrating a fundamental glycomic difference. For EA.hy926 that was investigated in more details, its polylactosaminoglycan chains were shown to be not restricted to extending from a specific antenna including the biologically important 6-arm position. Finally, experimental conditions for glycopeptide enrichment by tomato lectin were further optimized, which led to identification of over 40 candidate endothelial membrane protein carriers of polylactosaminoglycans by proteomic analysis.

Cyclin A2 confers cisplatin resistance to endometrial carcinoma cells via up-regulation of an Akt-binding protein, periplakin

Although overexpression of cyclin A2 is reportedly an indicator of a poor prognosis of various malignancies including endometrial carcinoma, its molecular mechanism remains undetermined. To address this issue, we examined the effect of cyclin A2 on the development of resistance to chemotherapeutic drugs. The expression of cyclin A2 protein was increased in advanced-stage and chemotherapy-refractory stage endometrial carcinomas compared with that in early-stage tumours. The expression levels of cyclin A2 in endometrial carcinoma cell lines correlated positively with the IC₅₀ for cisplatin. Endometrial carcinoma HHUA cells that overexpressed cyclin A2 showed increased resistance to cisplatin in vitro and in vivo, via the activation of a survival pathway, the inositol-3 phosphate kinase (PI3K) cascade. The use of a cDNA microarray identified an Akt-binding protein, periplakin, as a novel target of cyclin A2. The cyclin A2-induced up-regulation of periplakin was mediated via direct binding of Sp1 to the promoter that was activated by cyclin A2 along with chromatin remodelling involving CBP/p300, and the siRNA-mediated silencing of periplakin suppressed the PI3K pathway. These results indicate cyclin A2 to be involved in the acquisition of aggressive behaviour of tumour cells through the activation of PI3K by cyclin A2-induced periplakin, and to be a promising therapeutic target.

Gene expression and association analysis of the epithelial membrane protein 1 gene in major depressive disorder in the Japanese population

The epithelial membrane protein 1 (EMP1) plays a role in neuronal differentiation and neurite outgrowth, which are involved in the pathogenesis of major depressive disorder (MDD). We sought to determine whether the EMP1 gene is implicated in MDD. We determined the mRNA expression levels of the EMP1 gene in peripheral-blood leukocytes of patients and control subjects (n=27 each). Next, we performed case-control association analyses (MDD, n=182; controls, n=350) in the Japanese population. The level of expression of the EMP1 mRNA was significantly lower in medication-free patients compared with control subjects (P<0.001). The association analysis revealed an absence of association between the polymorphisms studied and MDD, whereas a gender-specific association was observed between male controls and male patients for marker rs7315725 (permutation P=0.039). Our results suggest that the EMP1 gene may be implicated in the pathophysiology of MDD in the Japanese population.

Transcriptional profiling of ErbB signalling in mammary luminal epithelial cells--interplay of ErbB and IGF1 signalling through IGFBP3 regulation

BACKGROUND

Members of the ErbB family of growth factor receptors are intricately linked with epithelial cell biology, development and tumourigenesis; however, the mechanisms involved in their downstream signalling are poorly understood. Indeed, it is unclear how signal specificity is achieved and the relative contribution each receptor has to specific gene expression.

METHODS

Gene expression profiling of a human mammary luminal epithelial cell model of ErbB2-overexpression was carried out using cDNA microarrays with a common RNA reference approach to examine long-term overlapping and differential responses to EGF and heregulin beta1 treatment in the context of ErbB2 overexpression. Altered gene expression was validated using quantitative real time PCR and/or immunoblotting. One gene of interest was targeted for further characterisation, where the effects of siRNA-mediated silencing on IGF1-dependent signalling and cellular phenotype were examined and compared to the effects of loss of ErbB2 expression.

RESULTS

775 genes were differentially expressed and clustered in terms of their growth factor responsiveness. As well as identifying uncharacterized genes as novel targets of ErbB2-dependent signalling, ErbB2 overexpression augmented the induction of multiple genes involved in proliferation (e.g. MYC, MAP2K1, MAP2K3), autocrine growth factor signalling (VEGF, PDGF) and adhesion/cytoskeletal regulation (ZYX, THBS1, VCL, CNN3, ITGA2, ITGA3, NEDD9, TAGLN), linking them to the hyper-poliferative and altered adhesive phenotype of the ErbB2-overexpressing cells. We also report ErbB2-dependent down-regulation of multiple interferon-stimulated genes that may permit ErbB2-overexpressing cells to resist the anti-proliferative action of interferons. Finally, IGFBP3 was unique in its pattern of regulation and we further investigated a possible role for IGFBP3 down-regulation in ErbB2-dependent transformation through suppressed IGF1 signalling. We show that IGF1-dependent signalling and proliferation were enhanced in ErbB2-overexpressing cells, whilst loss of ErbB2 expression by siRNA silencing reduced IGF1 signalling. Furthermore, IGFBP3 knockdown resulted in basal ERK and Akt activation in luminal epithelial cells and increased invasiveness and anchorage-independent colony formation in SKBR3 cells.

CONCLUSIONS

These data show IGFBP3 as a negative regulator of transformation and that its down-regulation enhances IGF1-dependent signalling. They also show that ErbB2 can up-regulate IGF1-dependent signalling, possibly via the regulated expression of IGFBP3.

Cancer-associated fibroblasts derived from EGFR-TKI-resistant tumors reverse EGFR pathway inhibition by EGFR-TKIs

Epidermal growth factor receptor (EGFR) plays a critical role in oncogenesis, which makes it an attractive target for pharmacologic inhibition. Yet, EGFR inhibition with tyrosine kinase inhibitors (TKI) does not result in a measurable and sustainable clinical benefit in a vast majority of tumors. This emphasizes the need for further investigations into resistance mechanisms against EGFR-TKIs. We previously reported the generation of an in vivo adenocarcinoma model of EGFR-TKI-acquired resistance that was devoid of the known mechanisms of resistance. Using this same xenograft model, we now show that the tumor stroma plays an important role in limiting responsiveness to EGFR-TKIs. EGFR-TKI-resistant tumors display increased surface expression of CD44(hi)/CD24(lo) and markers of epithelial to mesenchymal transition (EMT), SNAI1, and N-cadherin. An in vivo green fluorescent protein-tagging approach reveals that the tumor stroma of the EGFR-TKI-resistant tumors is distinct in that 24% of its cancer-associated fibroblast (CAF) population is composed of EMT-derived tumor cells that represent the in vivo escape from EGFR-TKIs. We further show that EMT subpopulation-harboring CAFs isolated from the EGFR-TKI-resistant tumors are tumorigenic and express the biomarker of gefitinib resistance, epithelial membrane protein-1. Finally, we provide evidence that paracrine factors secreted from the EGFR-TKI-resistant CAFs mitigate the EGFR-TKI-mediated blockade of pEGFR and pMAPK in cocultured tumor cells, regardless of their EGFR mutational status. This is the first demonstration that the tumor stroma is modified with acquisition of EGFR-TKI resistance and that it further contributes in promoting drug resistance.

Positive selection on apoptosis related genes

Apoptosis is a form of programmed cell death crucial for development, homeostasis, immunity, spermatogenesis, and prevention of cancer. Positive selection acting on mammalian apoptosis related genes targets protein interfaces that interact with pathogens and also elements of signaling complexes. Selection appears primarily to be driven by the immune/defense related function of these genes. Moreover, competitive interactions could be driving positive selection among sperm cells, as well as the need for protection against female anti-sperm immune responses. Trade-offs in fitness are expected out of these selective pressures, which could explain the involvement of these genes in various diseases, including cancer.

Up-regulation of epithelial membrane protein-1 in the temporal neocortex of patients with intractable epilepsy

Epithelial membrane protein-1 (EMP-1), called Tumor-associated membrane protein, is the marker of a drug-resistant tumor and take part in the drug-resistant mechanism of tumor, with the relationship of epidermal growth factor receptor (EGFR). Because there are some similarities between the pathogenesis and the drug resistance mechanism of tumor and the drug resistance mechanisms in epilepsy. EMP1 expression may be connected with the drug-resistance mechanism of epilepsy. We detected EMP-1 by gene scanning and immunohistochemistry staining, comparing the IE group and the control group, and we investigated the relationship between EMP-1 and EGFR by double-label immunofluorescence staining in the IE group. We found expression of EMP-1 mRNA was higher in IE per the gene scanning, EMP-1 immunoreactivity was apparent in neurons of IE patients but not in the control group, and the expression of EMP-1 and EGFR occurred in the same neuron. We confirm EMP-1 is abnormally expressed in IE and suggest the interaction of EGFR and EMP-1 plays a role in the mechanism of drug resistance in epilepsy and may be a new gene for drug resistance.

Targeted and nontargeted effects of ionizing radiation that impact genomic instability

Radiation-induced genomic instability, in which the progeny of irradiated cells display a high frequency of nonclonal genomic damage, occurs at a frequency inconsistent with mutation. We investigated the mechanism of this nontargeted effect in human mammary epithelial cells (HMEC) exposed to low doses of radiation. We identified a centrosome-associated expression signature in irradiated HMEC and show here that centrosome deregulation occurs in the first cell cycle after irradiation, is dose dependent, and that viable daughters of these cells are genomically unstable as evidenced by spontaneous DNA damage, tetraploidy, and aneuploidy. Clonal analysis of genomic instability showed a threshold of >10 cGy. Treatment with transforming growth factor beta1 (TGFbeta), which is implicated in regulation of genomic stability and is activated by radiation, reduced both the centrosome expression signature and centrosome aberrations in irradiated HMEC. Furthermore, TGFbeta inhibition significantly increased centrosome aberration frequency, tetraploidy, and aneuploidy in nonirradiated HMEC. Rather than preventing radiation-induced or spontaneous centrosome aberrations, TGFbeta selectively deleted unstable cells via p53-dependent apoptosis. Together, these studies show that radiation deregulates centrosome stability, which underlies genomic instability in normal human epithelial cells, and that this can be opposed by radiation-induced TGFbeta signaling.

Preclinical pharmacokinetic/pharmacodynamic models of gefitinib and the design of equivalent dosing regimens in EGFR wild-type and mutant tumor models

Epidermal growth factor receptor (EGFR) inhibitors, such as gefitinib, are examples of targeted anticancer drugs whose drug sensitivity is related to gene mutations that adds a pharmacogenetic (PG) dimension to any pharmacokinetic (PK) and pharmacodynamic (PD) analysis. The goal of this investigation was to cast the combined PG/PK/PD variables into models that could be used to design equivalent PK/PD dosing regimens for gefitinib in genetically distinct tumor models. To this end, groups of mice bearing either s.c. LN229-wild-type EGFR or LN229-EGFRvIII mutant tumors, an EGFR inhibitor-sensitizing mutation, were given gefitinib at doses of 10 mg/kg i.v., 50 mg/kg intraarterially, and 150 mg/kg p.o. In each group, gefitinib plasma and tumor concentrations were quantitated, as were tumoral amounts of phosphorylated extracellular signal-regulated kinase (ERK) 1/2 (pERK), a PD end point that was shown to respond in a dose-dependent manner in each tumor type. Hybrid physiologically based PK/PD models were developed for each tumor type, which consisted of a forcing function describing the plasma drug concentration profile, a tumor compartment depicting drug disposition in tumor, and a mechanistic target-response PD model characterizing pERK in the tumor. Gefitinib showed analogous PK properties in each tumor type yet different PD characteristics consistent with the EGFR status of the tumors. Using the PK/PD model for each tumor type, simulations were done to define multiple-dose regimens for gefitinib that yielded equivalent PD profiles of pERK in each tumor type. The novel concept of PK/PD equivalent dosing regimens could be applied in drug development and to delineate PG differences in drug activity.

Using LongSAGE to Detect Biomarkers of Cervical Cancer Potentially Amenable to Optical Contrast Agent Labelling

Sixteen longSAGE libraries from four different clinical stages of cervical intraepithelial neoplasia have enabled us to identify novel cell-surface biomarkers indicative of CIN stage. By comparing gene expression profiles of cervical tissue at early and advanced stages of CIN, several genes are identified to be novel genetic markers. We present fifty-six cell-surface gene products differentially expressed during progression of CIN. These cell surface proteins are being examined to establish their capacity for optical contrast agent binding. Contrast agent visualization will allow real-time assessment of the physiological state of the disease process bringing vast benefit to cancer care. The data discussed in this publication have been submitted to NCBIs Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/) and are accessible through GEO Series accession number GSE6252.

Loss of homotypic cell adhesion by epithelial-mesenchymal transition or mutation limits sensitivity to epidermal growth factor receptor inhibition

Overexpression and enhanced activation of the epidermal growth factor receptor (EGFR) is frequently observed in human carcinomas. Inhibitors of EGFR signaling have shown clinical utility; however, understanding response at the molecular level is important to define patient subsets most likely to benefit, as well as to support the rational design of drug combinations. Pancreatic and colorectal tumor cell lines insensitive to EGFR inhibition were those that had lost or mutated the epithelial junction constituents E-cadherin and gamma-catenin, had lost homotypic adhesion, and often gained proteins associated with an epithelial to mesenchymal-like transition, such as vimentin, zeb1, or snail. In matched pairs of colorectal tumor cells, the epithelial lines showed an average 7-fold greater sensitivity than mesenchymal-like lines. In human pancreatic and colorectal tumor tissues, gain of mesenchymal characteristics and loss of epithelial characteristics correlated with advancing tumor stage. These data indicate an especially sensitive patient subset as well as a rationale for the combination of EGFR antagonists with agents that affect the epithelial to mesenchymal-like transition process as a mechanism to enhance sensitivity for more advanced mesenchymal-like tumors.

Breast cancer expressing the activated HER2/neu is sensitive to gefitinib in vitro and in vivo and acquires resistance through a novel point mutation in the HER2/neu

The HER2/neu oncogene is an important diagnostic and prognostic factor and therapeutic target in breast and other cancers. We developed and characterized a breast cancer cell line (Bam1a) that overexpresses the activated HER2/neu and ErbB-3 and has a gene expression profile consistent with the ErbB-2 genetic signature. We evaluated the effects of the epidermal growth factor receptor (EGFR)/HER2 inhibitor, gefitinib, on this breast tumor line in vitro and in vivo. We characterized the effects of gefitinib on EGFR, HER2, and ErbB-3 phosphorylation by Western blot and determined the effects on downstream signaling through growth, survival, and stress pathways and the effect on proliferation, cell cycle, and apoptosis. Gefitinib treatment diminished phosphorylation of the ErbB-3 > EGFR > HER2/neu and signal transducers and activators of transcriptions in a dose-dependent fashion. Downstream mitogenic signaling through mitogen-activated protein (MAP)/extracellular signal regulated kinase kinase, p44/42 MAP kinase (MAPK) and stress signaling through c-Jun-NH(2)-kinase (JNK) 1 and c-Jun was impaired (1 micromol/L, 4-24 h), leading to cytostasis and cell cycle arrest within 24 h by decreased cyclin D1, cyclin B1, and p(Ser795)Rb and increased p27. Proliferation and colony formation were inhibited at 0.5 and 1 micromol/L, respectively, and correlated with altered gene expression profiles. Diminished survival signaling through Akt, induction of bim, loss of connexin43, and decreased production of vascular endothelial growth factor-D preceded caspase-3 and poly(ADP)ribose polymerase (PARP) cleavage and apoptosis (>50% 2 micromol/L, 48 h). Oral administration of gefitinib was able to prevent the outgrowth of Bam1a tumor cells from palpable lesions, shrink established tumors, eliminate HER2 and HER3 phosphorylation, and decrease MAPK and Akt signaling in vivo. A variant of the Bam1a cell line, IR-5, with acquired ability to grow in 5 micromol/L gefitinib was developed and characterized. IR-5 bears a novel point mutation in the HER2/neu that corresponds to a L726I in the ATP-binding pocket and correlates with a log decrease in sensitivity to gefitinib, increased heterodimerization with EGFR and HER3, and impaired down-regulation. Gene expression profiling of IR-5 showed increased expression of EMP-1, NOTCH-1, FLT-1, PDGFB, and several other genes that may contribute to the resistant phenotype and sustain signaling through MAPK and Akt. This model will be useful in understanding the differences between intrinsic drug sensitivity and acquired resistance in the context of therapeutic strategies that target oncogene addicted diseases.

Beta-2-microglobulin is an androgen-regulated secreted protein elevated in serum of patients with advanced prostate cancer

PURPOSE

A better understanding of secreted proteins may lead to the discovery of new biomarkers, which, along with prostate-specific antigen (PSA), may be useful in the diagnosis and treatment of prostate cancer patients.

EXPERIMENTAL DESIGN

Conditioned medium was collected from LNCaP cells following stimulation with methyltrienolone (R1881), 17beta-estradiol (estradiol), or interleukin-6 and analyzed for differential protein expression with surface-enhanced laser desorption/ionization-time of flight mass spectrometry. Quantitative reverse transcription-PCR, immunoblots, and ELISA were used to measure beta-2-microglobulin (B2M) message and protein levels in cells, conditioned medium, and serum.

RESULTS

Surface-enhanced laser desorption/ionization-time of flight revealed that many peaks were induced or repressed following stimulation with R1881 or estradiol. A peak of interest centered at 11.8 kDa was chosen for additional analysis. Immunodepletion identified the peak of interest as B2M. Reverse transcription-PCR and immunoblots confirmed that PSA and B2M were induced by R1881. However, unlike PSA, B2M was not increased on stimulation with estradiol or interleukin-6. Human B2M is identified in the serum of mice bearing human prostate cancer xenograft. B2M is expressed in human prostate cancer cell lines and tissues. Serum B2M levels are elevated in patients with metastatic, androgen-independent prostate cancer.

CONCLUSIONS

B2M is a secreted protein expressed in prostate cancer, which is more specific for androgen stimulation than PSA under the conditions tested. Additional studies are warranted to explore if B2M is as useful marker for prostate cancer. Identification of proteins secreted from cancer cells in preclinical models may be a useful strategy for biomarker discovery.