Sprouty4, a suppressor of tumor cell motility, is down regulated by DNA methylation in human prostate cancer

Mechanism of Antitumor Effects of Saffron in Human Prostate Cancer Cells

Prostate cancer is the most common cancer and the second leading cause of cancer deaths among men in the USA. Several studies have demonstrated the antitumor properties of saffron in different types of cancers, including prostate cancer. The oral administration of saffron extract has been reported to have antitumor effects on aggressive prostate-cancer-cell-line-derived xenografts in nude male mice. The objective of this study was to carry out in vitro studies of saffron-treated prostate cancer cells to ascertain the effects of saffron on key intermediates in prostate carcinogenesis. Our studies demonstrated the significant inhibition of cell proliferation for androgen-sensitive prostate cancer cell lines via apoptotic pathways. We also demonstrate the statistically significant down-regulation of DNA methyltransferases (COMT, MGMT, EHMT2, and SIRT1 deacetylase) in saffron-treated prostate cancer cells. In addition, saffron-treated prostate cancer cells displayed a statistically significant dysregulation of DNA repair intermediates (WRN, p53, RECQ5, MST1R, and WDR70) in a time-dependent manner. Furthermore, Western blot analysis demonstrated that saffron treatment induced changes in the expression of other key genes (DNMT1, DNMT3b, MBD2, CD44, HDAC3, c-Myc, NF-kB, TNFα, AR, N-RAS, and PTEN) in prostate cancer cells. Collectively, our findings demonstrate the important mechanisms by which saffron mediates anti-tumor properties in prostate cancer. These findings suggest that the use of saffron supplements alongside standard treatment protocols may yield beneficial effects for individuals with prostate cancer.

Sprouty4 is epigenetically upregulated in human colorectal cancer

Sprouty4 (SPRY4) has been frequently reported as a tumor suppressor and is therefore downregulated in various cancers. For the first time, we report that SPRY4 is epigenetically upregulated in colorectal cancer (CRC). In this study, we explored DNA methylation and hydroxymethylation levels of SPRY4 in CRC cells and patient samples and correlated these findings with mRNA and protein expression levels. Three loci within the promoter region of SPRY4 were evaluated for 5mC levels in CRC using the combined bisulfite restriction analysis. In addition, hydroxymethylation levels within SPRY4 were measured in CRC patients. Lastly, DNA methylation and mRNA expression data were extracted from CRC patients in multiple high-throughput data repositories like Gene Expression Omnibus and The Cancer Genome Atlas. Combined in vitro and in silico analysis of promoter methylation levels of SPRY4 clearly demonstrates that the distal promoter region undergoes hypomethylation in CRC patients and is associated with increased expression. Moreover, a decrease in gene body hydroxymethylation and an increase in gene body methylation within the coding region of SPRY4 were found in CRC patients and correlated with increased expression. SPRY4 is epigenetically upregulated in CRC by promoter hypomethylation and hypermethylation within the gene body that warrants future investigation of atypical roles of this established tumor suppressor.

SPRY4 inhibits and sensitizes the primary KIT mutants in gastrointestinal stromal tumors (GISTs) to imatinib

BACKGROUND

KIT is frequently mutated in gastrointestinal stromal tumors (GISTs), and the treatment of GISTs largely relies on targeting KIT currently. In this study, we aimed to investigate the role of sprouty RTK signaling antagonist 4 (SPRY4) in GISTs and related mechanisms.

METHODS

Ba/F3 cells and GIST-T1 cell were used as cell models, and mice carrying germline KIT/V558A mutation were used as animal model. Gene expression was examined by qRT-PCR and western blot. Protein association was examined by immunoprecipitation.

RESULTS

Our study revealed that KIT increased the expression of SPRY4 in GISTs. SPRY4 was found to bind to both wild-type KIT and primary KIT mutants in GISTs, and inhibited KIT expression and activation, leading to decreased cell survival and proliferation mediated by KIT. We also observed that inhibition of SPRY4 expression in KITV558A/WT mice led to increased tumorigenesis of GISTs in vivo. Moreover, our results demonstrated that SPRY4 enhanced the inhibitory effect of imatinib on the activation of primary KIT mutants, as well as on cell proliferation and survival mediated by the primary KIT mutants. However, in contrast to this, SPRY4 did not affect the expression and activation of drug-resistant secondary KIT mutants, nor did it affect the sensitivity of secondary KIT mutants to imatinib. These findings suggested that secondary KIT mutants regulate a different downstream signaling cascade than primary KIT mutants.

CONCLUSIONS

Our results suggested that SPRY4 acts as negative feedback of primary KIT mutants in GISTs by inhibiting KIT expression and activation. It can increase the sensitivity of primary KIT mutants to imatinib. In contrast, secondary KIT mutants are resistant to the inhibition of SPRY4.

The risk model construction of the genes regulated by H3K36me3 and H3K79me2 in breast cancer

Abnormal histone modifications (HMs) can promote the occurrence of breast cancer. To elucidate the relationship between HMs and gene expression, we analyzed HM binding patterns and calculated their signal changes between breast tumor cells and normal cells. On this basis, the influences of HM signal changes on the expression changes of breast cancer-related genes were estimated by three different methods. The results showed that H3K79me2 and H3K36me3 may contribute more to gene expression changes. Subsequently, 2109 genes with differential H3K79me2 or H3K36me3 levels during cancerogenesis were identified by the Shannon entropy and submitted to perform functional enrichment analyses. Enrichment analyses displayed that these genes were involved in pathways in cancer, human papillomavirus infection, and viral carcinogenesis. Univariate Cox, LASSO, and multivariate Cox regression analyses were then adopted, and nine potential breast cancer-related driver genes were extracted from the genes with differential H3K79me2/H3K36me3 levels in the TCGA cohort. To facilitate the application, the expression levels of nine driver genes were transformed into a risk score model, and its robustness was tested via time-dependent receiver operating characteristic curves in the TCGA dataset and an independent GEO dataset. At last, the distribution levels of H3K79me2 and H3K36me3 in the nine driver genes were reanalyzed in the two cell lines and the regions with significant signal changes were located.

Sprouty 4 expression in human oral squamous cell carcinogenesis

Background/purpose

Reviewing literature, sprouty 4 (SPRY4) has not been studied in human oral squamous cell carcinomas (OSCCs). The study aimed to examine SPRY4 expression in human oral squamous cell carcinogenesis.

Materials and methods

A total of 95 OSCCs, 10 OPMDs with malignant transformation (MT), 17 OPMDs without MT, and six normal oral mucosa (NOM) samples were recruited for immunohistochemical staining; three OSCC tissues with normal tissue counterpart NOM were employed for Western blotting. Three human oral cancer cell lines (OCCLs), an oral precancer cell line (dysplastic oral keratinocyte, DOK), and a primary culture of normal oral keratinocytes (HOK) were used for Western blotting; OCCLs and HOK were employed for real-time quantitative reverse transcription-polymerase chain reaction. OCCLs were evaluated in terms of proliferation, migration, and invasion assays.

Results

SPRY4 protein expression was significantly increased in OSCCs compared with NOM. Protein and mRNA SPRY4 expression in OCCLs were significantly elevated compared with HOK. Significant increases in the degrees of proliferation, migration, and invasion were noted in OCCLs with SPRY4 siRNA transfection compared with those without transfection. SPRY4 protein level was increased in OPMD with MT compared to OPMD without MT. SPRY4 protein was significant increase in DOK in comparison with HOK. SPRY4 protein expression was significantly increased from NOM and OPMD without MT to OSCC. SPRY4 protein expression in OCCLs was significantly enhanced compared with DOK and HOK respectively.

Conclusion

Our results indicate that SPRY4 expression is possibly involved in human oral squamous cell carcinogenesis.

Downregulated miR-18a and miR-92a synergistically suppress non-small cell lung cancer via targeting Sprouty 4

As a novel noncoding RNA cluster, miR-17-92 cluster include six members: miR-17, miR-18a, miR-19a, miR-19b-1, miR-20a, and miR-92a. Dysregulation of miR-17-92 has been proved to be connected with the advancement of a series of human diseases, but the roles of miR-17-92 cluster in non-small cell lung cancer (NSCLC) have not been absolutely elaborated. Herein, we determined that miR-17-92 cluster were upregulated significantly in NSCLC tissues, and the cell proliferation, migration and cycle progression of NSCLC were also facilitated under the function of miR-17-92 cluster. Sprouty 4 (SPRY4) was a direct target of miR-92a, and its overexpression restrained the exacerbation of NSCLC induced by miR-92a. Furthermore, the tumor xenograft assay showed that miR-92a facilitated tumor growth by inhibiting the expression of SPRY4 and mediating Epithelial-Mesenchymal Transition (EMT) in vivo. Finally, we looked into the synergistic effects of miR-92a and miR-18a on NSCLC, and found that antagomiR-18a treatment arrested the tumor growth rate of xenografted mice markedly.

Identification of SPRY4 as a Novel Candidate Susceptibility Gene for Familial Nonmedullary Thyroid Cancer

Background: The molecular basis of familial nonmedullary thyroid cancer (FNMTC) is still poorly understood, representing a limitation for molecular diagnosis and clinical management. In this study, we aimed to identify new susceptibility genes for FNMTC through whole-exome sequencing (WES) analysis of leukocyte DNA of patients from a highly informative FNMTC family. Methods: We selected six affected family members to conduct WES analysis. Bioinformatic analyses were undertaken to filter and select the genetic variants shared by the affected members, which were subsequently validated by Sanger sequencing. To select the most likely pathogenic variants, several studies were performed, including family segregation analysis, in silico impact characterization, and gene expression (messenger RNA and protein) depiction in databases. For the most promising variant identified, we performed in vitro studies to validate its pathogenicity. Results: Several potentially pathogenic variants were identified in different candidate genes. After filtering with appropriate criteria, the variant c.701C>T, p.Thr234Met in the SPRY4 gene was prioritized for in vitro functional characterization. This SPRY4 variant led to an increase in cell viability and colony formation, indicating that it confers a proliferative advantage and potentiates clonogenic capacity. Phosphokinase array and Western blot analyses suggested that the effects of the SPRY4 variant were mediated through the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway, which was further supported by a higher responsiveness of thyroid cancer cells with the SPRY4 variant to a MEK inhibitor. Conclusions: WES analysis in one family identified SPRY4 as a likely novel candidate susceptibility gene for FNMTC, allowing a better understanding of the cellular and molecular mechanisms underlying thyroid cancer development.

Sprouty4 negatively regulates ERK/MAPK signaling and the transition from in situ to invasive breast ductal carcinoma

Breast ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive ductal carcinoma (IDC). It is still unclear which DCIS will become invasive and which will remain indolent. Patients often receive surgery and radiotherapy, but this early intervention has not produced substantial decreases in late-stage disease. Sprouty proteins are important regulators of ERK/MAPK signaling and have been studied in various cancers. We hypothesized that Sprouty4 is an endogenous inhibitor of ERK/MAPK signaling and that its loss/reduced expression is a mechanism by which DCIS lesions progress toward IDC, including triple-negative disease. Using immunohistochemistry, we found reduced Sprouty4 expression in IDC patient samples compared to DCIS, and that ERK/MAPK phosphorylation had an inverse relationship to Sprouty4 expression. These observations were reproduced using a 3D culture model of disease progression. Knockdown of Sprouty4 in MCF10.DCIS cells increased ERK/MAPK phosphorylation as well as their invasive capability, while overexpression of Sprouty4 in MCF10.CA1d IDC cells reduced ERK/MAPK phosphorylation, invasion, and the aggressive phenotype exhibited by these cells. Immunofluorescence experiments revealed reorganization of the actin cytoskeleton and relocation of E-cadherin back to the cell surface, consistent with the restoration of adherens junctions. To determine whether these effects were due to changes in ERK/MAPK signaling, MEK1/2 was pharmacologically inhibited in IDC cells. Nanomolar concentrations of MEK162/binimetinib restored an epithelial-like phenotype and reduced pericellular proteolysis, similar to Sprouty4 overexpression. From these data we conclude that Sprouty4 acts to control ERK/MAPK signaling in DCIS, thus limiting the progression of these premalignant breast lesions.

SPRY4 suppresses proliferation and induces apoptosis of colorectal cancer cells by repressing oncogene EZH2

Colorectal cancer (CRC), a common malignant tumor in the digestive tract, is a leading cause of cancer-related death. SPRY4 has been reported to act as a tumor suppressor gene in various tumors. This study aims to assess the role of SPRY4 in colorectal cancer (CRC) and uncover its underlying mechanisms. Firstly, the expression levels of SPRY4 were measured in CRC cell lines. SPRY4-overexpressing or silencing plasmids were transfected into CRC cells to regulate its expression level. CCK-8, colony formation, EdU assay, wound-healing and Transwell assays were performed to determine cell proliferation, invasion and migration abilities. Then, apoptosis was measured by flow cytometry analysis, and the expression of apoptosis-related protein was analyzed by western-blotting. Next, the in vivo tumorigenesis assay was performed in nude mice. According to the results, there was a lower expression of SPRY4 in CRC cell lines compared with normal cell line, and the overexpression of SPRY4 significantly suppressed cell proliferation, migration and invasion, and promoted apoptosis in SW480 cells. Moreover, the enhanced proliferation, invasion and migration upon SPRY4 silencing was reversed by EZH2 inhibition. In addition, we found that the overexpression of SPRY4 inhibited tumorigenesis in vivo by diminishing the size and weight of the tumors. Our study indicates that SPRY4 might be a potential tumor suppressor gene and prognostic factor for patients with CRC.

A Sprouty4 Mutation Identified in Kallmann Syndrome Increases the Inhibitory Potency of the Protein towards FGF and Connected Processes

Kallmann syndrome is the result of innate genetic defects in the fibroblast growth factor (FGF) regulated signaling network causing diminished signal transduction. One of the rare mutations associated with the syndrome alters the Sprouty (Spry)4 protein by converting the serine at position 241 into a tyrosine. In this study, we characterize the tyrosine Spry4 mutant protein in the primary human embryonic lung fibroblasts WI-38 and osteosarcoma-derived cell line U2OS. As demonstrated in a cell signaling assay, Spry4 gains the capability of inhibiting FGF, but not epithelial growth factor (EGF)-induced signaling as a consequence of the tyrosine substitution. Additionally, migration of normal embryonic lung fibroblasts and osteosarcoma-derived cells is potently inhibited by the tyrosine Spry4 variant, while an effect of the wildtype Spry4 protein is hardly measureable. Concerning cell proliferation, the unaltered Spry4 protein is ineffective to influence the WI-38 cells, while the mutated Spry4 protein decelerates the cell doubling. In summary, these data emphasize that like the other mutations associated with Kallmann syndrome the described Spry4 mutation creates a hyperactive version of a selective inhibitory molecule and can thereby contribute to a weakened FGF signaling. Additionally, the study pinpoints a Spry4 variation expanding the applicability of Spry4 in a potential cancer therapy.

The FGF/FGFR system in the physiopathology of the prostate gland

Fibroblast growth factors (FGFs) are a family of proteins possessing paracrine, autocrine, or endocrine functions in a variety of biological processes, including embryonic development, angiogenesis, tissue homeostasis, wound repair, and cancer. Canonical FGFs bind and activate tyrosine kinase FGF receptors (FGFRs), triggering intracellular signaling cascades that mediate their biological activity. Experimental evidence indicates that FGFs play a complex role in the physiopathology of the prostate gland that ranges from essential functions during embryonic development to modulation of neoplastic transformation. The use of ligand- and receptor-deleted mouse models has highlighted the requirement for FGF signaling in the normal development of the prostate gland. In adult prostate, the maintenance of a functional FGF/FGFR signaling axis is critical for organ homeostasis and function, as its disruption leads to prostate hyperplasia and may contribute to cancer progression and metastatic dissemination. Dissection of the molecular landscape modulated by the FGF family will facilitate ongoing translational efforts directed toward prostate cancer therapy.

SPRY4 regulates trophoblast proliferation and apoptosis via regulating IFN-γ-induced STAT1 expression and activation in recurrent miscarriage

PROBLEM

The dysregulation of trophoblast functions is one of the leading causes of recurrent miscarriage (RM), which frustrates 1%-5% of couples of childbearing ages. Sprouty 4 (SPRY4) is considered as a tumour suppressor and exerts a negative role in cell viability. However, its role in regulating trophoblast behaviors at the maternal-fetal interface remains largely unknown.

METHOD OF STUDY

First-trimester villous samples were collected from RM patients and healthy controls (HCs) to determine the SPRY4 expression in human placenta during early pregnancy. The HTR8/SVneo cell line was introduced to clarify trophoblast cell functions via transfecting with specific short interfering RNA against SPRY4 or SPRY4-overexpressing lentivirus in vitro. In addition, gene expression microarray analysis was performed to explore the downstream molecules and pathways.

RESULTS

Our results revealed that SPRY4 expression was significantly increased in the first-trimester cytotrophoblasts of RM patients compared with HCs. Furthermore, SPRY4 overexpression inhibited trophoblast proliferation and accelerated apoptosis in vitro, while SPRY4 knockdown reversed these effects. Mechanistically, IFN-γ -induced STAT1 expression and activation were involved in the regulation of trophoblast proliferation and apoptosis by SPRY4, and IFN-γ promoted SPRY4 expression and STAT1 phosphorylation through PI3K/AKT pathway. Additionally, both STAT1 and phosphorylated STAT (p-STAT) levels were also upregulated in trophoblasts from RM patients and positively correlated with SPRY4 expression.

CONCLUSION

Our findings indicate that SPRY4 may act as a negative regulator of trophoblast functions through upregulating IFN-γ/PI3K/AKT-induced STAT1 activation. High levels of SPRY4 and STAT1 may contribute to RM development and progression, and blocking of either target could be a novel therapeutic strategy for RM patients.

Sprouty3 and Sprouty4, Two Members of a Family Known to Inhibit FGF-Mediated Signaling, Exert Opposing Roles on Proliferation and Migration of Glioblastoma-Derived Cells

Dysregulation of receptor tyrosine kinase-induced pathways is a critical step driving the oncogenic potential of brain cancer. In this study, we investigated the role of two members of the Sprouty (Spry) family in brain cancer-derived cell lines. Using immunoblot analyses we found essential differences in the pattern of endogenous Spry3 and Spry4 expression. While Spry4 expression was mitogen-dependent and repressed in a number of cells from higher malignant brain cancers, Spry3 levels neither fluctuated in response to serum withdrawal nor were repressed in glioblastoma (GBM)-derived cell lines. In accordance to the well-known inhibitory role of Spry proteins in fibroblast growth factor (FGF)-mediated signaling, both Spry proteins were able to interfere with FGF-induced activation of the MAPK pathway although to a different extent. In response to serum solely, Spry4 exerts its role as a negative regulator of MAPK activation. Ectopic expression of Spry4 inhibited proliferation and migration of GBM-originated cells, positioning it as a tumor suppressor in brain cancer. In contrast, elevated Spry3 levels accelerated both proliferation and migration of these cell lines, while repression of Spry3 levels using shRNA caused a significant diminished growth and migration velocity rate of a GBM-derived cell line. This argues for a tumor-promoting function of Spry3 in GBMs. Based on these data we conclude that Spry3 and Spry4 fulfill different if not opposing roles within the cancerogenesis of brain malignancies.

Commonly integrated epigenetic modifications of differentially expressed genes lead to adaptive resistance in cancer

Aim:

To investigate the integrated epigenetic regulation of acquired drug resistance in cancer.

Materials & methods:

Our gene expression data of five induced drug-tolerant cell models, one resistant cell line and one publicly available drug-resistant dataset were integrated to identify common differentially expressed genes and pathways. ChIP-seq and DNA methylation by HM450K beadchip were used to study the epigenetic profile of differential expressed genes.

Results & conclusion:

Integrated transcriptomic analysis identified a common ‘viral mimicry’ related gene signature in induced drug-tolerant cells and the resistant state. Analysis of the epigenetic regulation revealed a common set of down-regulated genes, which are marked and regulated by a concomitant loss of H3K4me3, gain of H3K9me3 and increment of regional DNA methylation levels associated with tumor suppressor genes and apoptotic signaling.

The Sprouty/Spred family as tumor suppressors: Coming of age

The Ras/Raf/ERK pathway is one of the most frequently dysregulated signaling pathways in various cancers. In some such cancers, Ras and Raf are hotspots for mutations, which cause continuous activation of this pathway. However, in some other cancers, it is known that negative regulators of the Ras/Raf/ERK pathway are responsible for uncontrolled activation. The Sprouty/Spred family is broadly recognized as important negative regulators of the Ras/Raf/ERK pathway, and its expression is downregulated in many malignancies, leading to hyperactivation of the Ras/Raf/ERK pathway. After the discovery of this family, intensive research investigated the mechanism by which it suppresses the Ras/Raf/ERK pathway and its roles in developmental and pathophysiological processes. In this review, we discuss the complicated roles of the Sprouty/Spred family in tumor initiation, promotion, and progression and its future therapeutic potential.

Oncogenic microRNA-411 promotes lung carcinogenesis by directly targeting suppressor genes SPRY4 and TXNIP

Lung cancer is one of the most common malignant diseases globally, composed of non-small cell lung cancer (NSCLC, 85%) and small cell lung cancer (SCLC, 15%). MicroRNAs (miRNAs) are single-stranded noncoding RNAs having important roles in lung cancer development. miR-411-5p/3p were reported to be increased significantly in human NSCLC tissues and cell lines. Moreover, miR-411-5p/3p overexpression could accelerate cell proliferation and migration, and impede cell apoptosis in NSCLC cell lines. Mechanically, SPRY4 is confirmed a direct target of miR-411-5p/3p. Furthermore, our findings showed that miR-411-5p/3p promoted lung tumor growth in vivo, decreased SPRY4 expression dramatically, and induced EGFR, AKT signaling activation, as well as epithelial–mesenchymal transition (EMT) simultaneously in tumor tissues. In addition, we showed that miR-411-5p also targeted tumor suppressor TXNIP, involved in regulating positively cell cycle progress in SPC-A1 cells rather than in H1299. Whether cell specificity of low TXNIP mRNA level in H1299 is responsible for the different response to cell cycle between H1299 and SPC-A1 would need further explorations. Collectively, these results suggest that miR-411-5p/3p are required for NSCLC development by suppressing SPRY4 and TXNIP; thus, the miR-411-SPRY4-AKT axis might act as a promising target for lung cancer therapy clinically.

The role of Sprouty1 in the proliferation, differentiation and apoptosis of epidermal keratinocytes

OBJECTIVES

Sprouty (SPRY) 1 is one of the SPRY proteins that inhibits signalling from various growth factors pathways and has also been known as a tumour suppressor in various malignancies. However, no study elucidates the role of SPRY1 in the skin. Our study was conducted to determine the function of SPRY1 in human keratinocytes and the epidermis.

MATERIALS AND METHODS

In vitro primary cultured epidermal keratinocytes were used to investigate the proliferation, differentiation and apoptosis of these cells. We also established overexpression of SPRY1 in vitro and K14-SPRY1 transgenic mice.

RESULTS

SPRY1 was mainly located in the cytoplasm of the epidermal keratinocytes from the granular epidermal layer of the skin and cultured cells. Overexpressed SPRY1 in keratinocytes resulted in up-regulation of P21, P27 and down-regulation of cyclin B1; decrease in MMP3 and integrin α6. SPRY1-overexpressed primary keratinocytes exhibited a lower proliferation and migration capability and higher rates of apoptosis. Epidermis of SPRY1-TG mice represented delayed wound healing. Proteomics analysis and GO enrichment showed DEPs of SPRY1 TG mice epidermis is significantly enriched in immune- and inflammatory-associated biological process.

CONCLUSIONS

In summary, SPRY1 expression was inversely correlated with cell proliferation, migration and promote cell apoptosis of keratinocytes. SPRY1 maybe a negative feedback regulator in normal human epidermal keratinocytes and cutaneous inflammatory responses. Our study raised the possibility that enhancing expression of SPRY1 may have the potential to promote anti-inflammatory effects.

Knockdown of SPRY4 and SPRY4-IT1 inhibits cell growth and phosphorylation of Akt in human testicular germ cell tumours

Testicular germ cell tumour (TGCT) is the most common cancer in young men in large parts of the world, but the aetiology is mainly unknown. Genome-wide association studies have so far identified about 50 susceptibility loci associated with TGCT, including SPRY4. SPRY4 has shown tumour suppressor activity in several cancer cells, such as lung and prostate, while it was found to act as an oncogene in ovarian cancer. An intronic region within the SPRY4 gene produces a long non-coding RNA, SPRY4-IT1, which has been reported to act as an oncogene in melanoma, breast cancer, and colorectal cancer, and as a tumour suppressor in lung cancer. The roles of SPRY4 and SPRY4-IT1 in TGCT development are yet unknown. We found higher expression levels of SPRY4, both mRNA and protein, and of SPRY4-IT1 in human TGCT than in normal adult testis. Small-interfering RNA (siRNA)-mediated transient knockdown of SPRY4 and SPRY4-IT1 in two TGCT cell lines 833 K and NT2-D1 resulted in decreased cell growth, migration, and invasion. Knockdown of SPRY4 and SPRY4-IT1 also led to a significant reduction in the phosphorylation of Akt. Our findings indicate that SPRY4 and SPRY4-IT1 may act as oncogenes in TGCTs via activation of the PI3K / Akt signalling pathway.

ARF1 promotes prostate tumorigenesis via targeting oncogenic MAPK signaling

ADP-ribosylation factor 1 (ARF1) is a crucial regulator in vesicle-mediated membrane trafficking and involved in the activation of signaling molecules. However, virtually nothing is known about its function in prostate cancer. Here we have demonstrated that ARF1 expression is significantly elevated in prostate cancer cells and human tissues and that the expression levels of ARF1 correlate with the activation of mitogen-activated protein kinases (MAPK) ERK1/2. Furthermore, we have shown that overexpression and knockdown of ARF1 produce opposing effects on prostate cancer cell proliferation, anchorage-independent growth and tumor growth in mouse xenograft models and that ARF1-mediated cell proliferation can be abolished by the Raf1 inhibitor GW5074 and the MEK inhibitors U0126 and PD98059. Moreover, inhibition of ARF1 activation achieved by mutating Thr48 abolishes ARF1's abilities to activate the ERK1/2 and to promote cell proliferation. These data demonstrate that the aberrant MAPK signaling in prostate cancer is, at least in part, under the control of ARF1 and that, similar to Ras, ARF1 is a critical regulator in prostate cancer progression. These data also suggest that ARF1 may represent a key molecular target for prostate cancer therapeutics and diagnosis.

The role of SMAD3 in the genetic predisposition to papillary thyroid carcinoma

PURPOSE

To identify and characterize the functional variants, regulatory gene networks, and potential binding targets of SMAD3 in the 15q22 thyroid cancer risk locus.

METHODS

We performed linkage disequilibrium (LD) and haplotype analyses to fine map the 15q22 locus. Luciferase reporter assays were applied to evaluate the regulatory effects of the candidate variants. Knockdown by small interfering RNA, microarray analysis, chromatin immunoprecipitation (ChIP) and quantitative real-time polymerase chain reaction assays were performed to reveal the regulatory gene network and identify its binding targets.

RESULTS

We report a 25.6-kb haplotype within SMAD3 containing numerous single-nucleotide polymorphisms (SNPs) in high LD. SNPs rs17293632 and rs4562997 were identified as functional variants of SMAD3 by luciferase assays within the LD region. These variants regulate SMAD3 transcription in an allele-specific manner through enhancer elements in introns of SMAD3. Knockdown of SMAD3 in thyroid cancer cell lines revealed its regulatory gene network including two upregulated genes, SPRY4 and SPRY4-IT1. Sequence analysis and ChIP assays validated the actual binding of SMAD3 protein to multiple SMAD binding element sites in the region upstream of SPRY4.

CONCLUSION

Our data provide a functional annotation of the 15q22 thyroid cancer risk locus.

Clinical impact of KMT2C and SPRY4 expression levels in intensively treated younger adult acute myeloid leukemia patients

OBJECTIVE

To evaluate the prognostic impact of gene expression levels (ELs) of two tumor suppressor genes, sprouty 4 (SPRY4, located on 5q) and lysine methyltransferase 2C (KMT2C, located on 7q) in correlation with clinical characteristics and genetic abnormalities assessed at initial diagnosis in acute myeloid leukemia (AML).

METHOD

Gene expression levels were measured on cDNA by RT-qPCR from diagnostic bone marrow samples of 275 intensively treated adult AML patients (median age, 48 years).

RESULTS

KMT2C ELs were significantly lower in abn7q/-7 (P = .001), whereas SPRY4 ELs were not associated with abn5q/-5. Higher KMT2C and SPRY4 ELs were significantly associated with lower genetic risk groups as defined by the European LeukemiaNet classification. Additionally, KMT2C ELs were lower in cytogenetically normal patients with DNMT3A (P = .01) or FLT3-ITD mutations (P = .05). KMT2C ELs were not associated with prognosis, whereas higher SPRY4 ELs showed a favorable impact on event-free (EFS, P = .01), relapse-free (RFS, P = .01) and in-trend on overall survival (P = .06) for cytogenetically abnormal patients, which was confirmed in multivariable analysis for EFS (HR, 0.84; 95%-CI, 0.73-0.97; P = .02) and RFS (HR, 0.85; 95%-CI, 0.73-0.98; P = .02).

CONCLUSION

Our data indicate that KMT2C ELs are associated with specific genetic features and that SPRY4 ELs may add prognostic information.

H3K27 acetylation activated-long non-coding RNA CCAT1 affects cell proliferation and migration by regulating SPRY4 and HOXB13 expression in esophageal squamous cell carcinoma

Recently, long non-coding RNAs (lncRNAs) have been shown to have important regulatory roles in human cancer biology. In our study, we found that lncRNA CCAT1, whose expression is significantly increased and is correlated with outcomes in Esophageal Squamous Cell Carcinoma (ESCC). Consecutive experiments confirmed that H3K27-acetylation could activate expression of colon cancer associated transcript-1 (CCAT1). Further experiments revealed that CCAT1 knockdown significantly repressed the proliferation and migration both in vitro and in vivo. RNA-seq analysis revealed that CCAT1 knockdown preferentially affected genes that are linked to cell proliferation, cell migration and cell adhesion. Mechanistic investigations found that CCAT1 could serve as a scaffold for two distinct epigenetic modification complexes (5΄ domain of CCAT1 binding Polycomb Repressive Complex 2 (PRC2) while 3΄ domain of CCAT1 binding SUV39H1) and modulate the histone methylation of promoter of SPRY4 (sprouty RTK signaling antagonist 4) in nucleus. In cytoplasm, CCAT1 regulates HOXB13 as a molecular decoy for miR-7, a microRNA that targets both CCAT1 and HOXB13, thus facilitating cell growth and migration. Together, our data demonstrated the important roles of CCAT1 in ESCC oncogenesis and might serve as targets for ESCC diagnosis and therapy.

Hypoxia inducible factors regulate the transcription of the sprouty2 gene and expression of the sprouty2 protein

Receptor Tyrosine Kinase (RTK) signaling plays a major role in tumorigenesis and normal development. Sprouty2 (Spry2) attenuates RTK signaling and inhibits processes such as angiogenesis, cell proliferation, migration and survival, which are all upregulated in tumors. Indeed in cancers of the liver, lung, prostate and breast, Spry2 protein levels are markedly decreased correlating with poor patient prognosis and shorter survival. Thus, it is important to understand how expression of Spry2 is regulated. While prior studies have focused on the post-translation regulation of Spry2, very few studies have focused on the transcriptional regulation of SPRY2 gene. Here, we demonstrate that in the human hepatoma cell line, Hep3B, the transcription of SPRY2 is inhibited by the transcription regulating hypoxia inducible factors (HIFs). HIFs are composed of an oxygen regulated alpha subunit (HIF1α or HIF2α) and a beta subunit (HIF1β). Intriguingly, silencing of HIF1α and HIF2α elevates SPRY2 mRNA and protein levels suggesting HIFs reduce the transcription of the SPRY2 promoter. In silico analysis identified ten hypoxia response elements (HREs) in the proximal promoter and first intron of SPRY2. Using chromatin immunoprecipitation (ChIP), we show that HIF1α/2α bind near the putative HREs in the proximal promoter and intron of SPRY2. Our studies demonstrated that not only is the SPRY2 promoter methylated, but silencing HIF1α/2α reduced the methylation. ChIP assays also showed DNA methyltransferase1 (DNMT1) binding to the proximal promoter and first intron of SPRY2 and silencing HIF1α/2α decreased this association. Additionally, silencing of DNMT1 mimicked the HIF1α/2α silencing-mediated increase in SPRY2 mRNA and protein. While simultaneous silencing of HIF1α/2α and DNMT1 increased SPRY2 mRNA a little more, the increase was not additive suggesting a common mechanism by which DNMT1 and HIF1α/2α regulate SPRY2 transcription. Together these data suggest that the transcription of SPRY2 is inhibited by HIFs, in part, via DNMT1- mediated methylation.

Sprouty4 mRNA variants and protein expressions in breast and lung-derived cells

Sprouty proteins are modulators of mitogen-induced signalling processes and are therefore hypothesized to affect malignant diseases. As a member of the Sprouty family, Sprouty4 has been previously shown to function as a tumour suppressor in lung and breast cancer. The present study analysed the expression of two known Sprouty4 splice variants in cells established from malignant and normal lung and breast tissues using semi-quantitative reverse transcription-polymerase chain reaction and immunoblotting. The results indicated that the expression of the two messenger RNA (mRNA) variants was reduced in the cells derived from malignant tissue in comparison to the normal counterparts. Although the expression of the two splice variants were associated in both tissue types, on average, the relative expression of the longer variant was slightly increased in malignant cells compared with normal tissues. Notably, the protein levels reflected the expression observed at the mRNA level only in breast-derived cells. Contrarily, with regards to the measured mRNA levels, Sprouty4 protein was disproportional augmented in lung cells known to harbour the mutated K-Ras gene.

Suppression of Spry4 enhances cancer stem cell properties of human MDA-MB-231 breast carcinoma cells

BACKGROUND

Cancer stem cells contribute to tumor initiation, heterogeneity, and recurrence, and are critical targets in cancer therapy. Sprouty4 (Spry4) is a potent inhibitor of signal transduction pathways elicited by receptor tyrosine kinases, and has roles in regulating cell proliferation, migration and differentiation. Spry4 has been implicated as a tumor suppressor and in modulating embryonic stem cells.

OBJECTIVES

The purpose of this research was to test the novel idea that Spry4 regulates cancer stem cell properties in breast cancer.

METHODS

Loss-of function of Spry4 in human MDA-MB-231 cell was used to test our hypothesis. Spry4 knockdown or control cell lines were generated using lentiviral delivery of human Spry4 or non-targeting control shRNAs, and then selected with 2 μg/ml puromycin. Cell growth and migratory abilities were determined using growth curve and cell cycle flow cytometry analyses and scratch assays, respectively. Xenograft tumor model was used to determine the tumorigenic activity and metastasis in vivo. Cancer stem cell related markers were evaluated using immunoblotting assays and fluorescence-activated cell sorting. Cancer stem cell phenotype was evaluated using in vitro mammosphere formation and drug sensitivity tests, and in vivo limiting dilution tumor formation assay.

RESULTS

Two out of three tested human Spry4 shRNAs significantly suppressed the expression of endogenous Spry4 in MDA-MB-231 cells. Suppressing Spry4 expression increased MDA-MB-231 cell proliferation and migration. Suppressing Spry4 increased β3-integrin expression, and CD133(+)CD44(+) subpopulation. Suppressing Spry4 increased mammosphere formation, while decreasing the sensitivity of MDA-MB-231 cells to Paclitaxel treatment. Finally, suppressing Spry4 increased the potency of MDA-MB-231 cell tumor initiation, a feature attributed to cancer stem cells.

CONCLUSIONS

Our findings provide novel evidence that endogenous Spry4 may have tumor suppressive activity in breast cancer by suppressing cancer stem cell properties in addition to negative effects on tumor cell proliferation and migration.

Aberrant expression of hSef and Sprouty4 in endometrial adenocarcinoma

Fibroblast growth factor (FGF) 2-mediated signaling of the mitogen-activated protein kinase/RAS/extracellular signal-regulated kinase 1/2 pathway is a critical modulator in angiogenesis and is therefore essential for the pathogenesis of endometrial carcinoma. Human similar expression to FGFs (hSef) and Sprouty4 have each been reported to be negative regulators of FGF signaling. The aim of the present study was to investigate the expression of hSef and Sprouty4 in human endometrial adenocarcinoma. Using immunohistochemistry analysis, the expression of hSef and Sprouty4 was detected in human endometrial adenocarcinomas. Increased hSef expression was found to be present in endometrial adenocarcinomas. In addition, decreased hSef expression was identified in the blood vessels of endometrial adenocarcinoma samples. However, the expression of Sprouty4 was downregulated in human endometrial adenocarcinoma. Aberrant expression of hSef and Sprouty4 are involved in the pathogenesis of human endometrial adenocarcinoma.

Fibrosis in the lens. Sprouty regulation of TGFβ-signaling prevents lens EMT leading to cataract

Cataract is a common age-related condition that is caused by progressive clouding of the normally clear lens. Cataract can be effectively treated by surgery; however, like any surgery, there can be complications and the development of a secondary cataract, known as posterior capsule opacification (PCO), is the most common. PCO is caused by aberrant growth of lens epithelial cells that are left behind in the capsular bag after surgical removal of the fiber mass. An epithelial-to-mesenchymal transition (EMT) is central to fibrotic PCO and forms of fibrotic cataract, including anterior/posterior polar cataracts. Transforming growth factor β (TGFβ) has been shown to induce lens EMT and consequently research has focused on identifying ways of blocking its action. Intriguingly, recent studies in animal models have shown that EMT and cataract developed when a class of negative-feedback regulators, Sprouty (Spry)1 and Spry2, were conditionally deleted from the lens. Members of the Spry family act as general antagonists of the receptor tyrosine kinase (RTK)-mediated MAPK signaling pathway that is involved in many physiological and developmental processes. As the ERK/MAPK signaling pathway is a well established target of Spry proteins, and overexpression of Spry can block aberrant TGFβ-Smad signaling responsible for EMT and anterior subcapsular cataract, this indicates a role for the ERK/MAPK pathway in TGFβ-induced EMT. Given this and other supporting evidence, a case is made for focusing on RTK antagonists, such as Spry, for cataract prevention. In addition, and looking to the future, this review also looks at possibilities for supplanting EMT with normal fiber differentiation and thereby promoting lens regenerative processes after cataract surgery. Whilst it is now known that the epithelial to fiber differentiation process is driven by FGF, little is known about factors that coordinate the precise assembly of fibers into a functional lens. However, recent research provides key insights into an FGF-activated mechanism intrinsic to the lens that involves interactions between the Wnt-Frizzled and Jagged/Notch signaling pathways. This reciprocal epithelial-fiber cell interaction appears to be critical for the assembly and maintenance of the highly ordered three-dimensional architecture that is central to lens function. This information is fundamental to defining the specific conditions and stimuli needed to recapitulate developmental programs and promote regeneration of lens structure and function after cataract surgery.

The developing story of Sprouty and cancer

Sprouty proteins are evolutionarily conserved modulators of MAPK/ERK pathway. Through interacting with an increasing number of effectors, mediators, and regulators with ultimate influence on multiple targets within or beyond ERK, Sprouty orchestrates a complex, multilayered regulatory system and mediates a crosstalk among different signaling pathways for a coordinated cellular response. As such, Sprouty has been implicated in various developmental and physiological processes. Evidence shows that ERK is aberrantly activated in malignant conditions. Accordingly, Sprouty deregulation has been reported in different cancer types and shown to impact cancer development, progression, and metastasis. In this article, we have tried to provide an overview of the current knowledge about the Sprouty physiology and its regulatory functions in health, as well as an updated review of the Sprouty status in cancer. Putative implications of Sprouty in cancer biology, their clinical relevance, and their proposed applications are also revisited. As a developing story, however, role of Sprouty in cancer remains to be further elucidated.

Sprouty 2 protein, but not Sprouty 4, is an independent prognostic biomarker for human epithelial ovarian cancer

Sprouty proteins are evolutionary-conserved modulators of receptor tyrosine kinase signaling, deregulation of which has been implicated in the pathophysiology of cancer. In the present study, the expression status of Spry2 and Spry4 proteins and its clinical relevance in human epithelial ovarian cancer (EOC) were investigated retrospectively. We examined the immunohistochemical expression of Spry2 and Spry4 in matched tumor and normal tissue samples from 99 patients. The expression of ERK, p-ERK, Ki67, fibroblast growth factor-2, vascular endothelial growth factor and interleukin-6 and their correlation with Sprouty homologs were also evaluated. Moreover, the correlation between Spry2 and Spry4 and the clinicopathological characteristics were analyzed along with their predictive value for overall survival (OS) and disease-free survival (DFS). Our data indicated significant downregulation of Spry2 and Spry4 in tumor tissues (p < 0.0001). A significant inverse correlation was evident between Spry2 and p-ERK/ERK (p = 0.048), Ki67 (p = 0.011), disease stage (p = 0.013), tumor grade (p = 0.003), recurrence (p < 0.001) and post-treatment ascites (p = 0.001), individually. It was found that Spry2 low-expressing patients had significantly poorer OS (p = 0.002) and DFS (p = 0.004) than those with high expression of Spry2. Multivariate analysis showed that high Spry2 (p = 0.018), low stage (p = 0.049) and no residual tumor (p =0.006) were independent prognostic factors for a better OS. With regard to DFS, high Spry2 (p = 0.044) and low stage (p = 0.046) remained as independent predictors. In conclusion, we report for the first time significant downregulation of Spry2 and Spry4 proteins in human EOC. Spry2 expression was revealed to significantly impact tumor behavior with predictive value as an independent prognostic factor for survival and recurrence.

Loss of Sprouty2 in human high-grade serous ovarian carcinomas promotes EGF-induced E-cadherin down-regulation and cell invasion

Sprouty (SPRY) proteins are well-characterized factors that inhibit receptor tyrosine kinase signaling. Our Human Exonic Evidence-Based Oligonucleotide (HEEBO) microarray results showed that the mRNA levels of SPRY2, but not of SPRY1 or SPRY4, are down-regulated in high-grade serous ovarian carcinoma (HGSC) tissues and epithelial ovarian cancer (EOC) cell lines. Molecular inversion probe (MIP) copy number analysis showed the deletion of the SPRY2 locus in HGSC. Overexpression of SPRY2 reduced EGF-induced cell invasion by attenuating EGF-induced E-cadherin down-regulation. Moreover, a positive correlation between SPRY2 and E-cadherin protein levels was observed in HGSC tissues. This study reveals the loss of SPRY2 in HGSC and indicates an important tumor-suppressive role for SPRY2 in mediating the stimulatory effect of EGF on human EOC progression.

SPRY4-mediated ERK1/2 signaling inhibition abolishes 17β-estradiol-induced cell growth in endometrial adenocarcinoma cell

OBJECTIVE

Basic fibroblast growth factor (FGF2)-mediated Extracellular signal-regulated kinases1/2 (ERK1/2) signaling is a critical modulator in angiogenesis. SPRY4 has been reported to be a feedback negative regulator of FGFs-induced ERK1/2 signaling. The aim of this study was to explore the role of SPRY4 in endometrial adenocarcinoma cell.

MATERIALS AND METHODS

The effect of SPRY4 expression on FGF2-mediated ERK1/2 signaling was detected by luciferase assay and Western blot analysis. The growth of Ishikawa cells was detected using colony formation assay and cell number counting experiment.

RESULTS

We found that plasmid-driven SPRY4 expression efficiently blocked the activity of FGF2-induced ERK1/2 signaling in Ishikawa cells. SPRY4 expression significantly reduced the proliferation and 17β-estradiol-induced proliferation of Ishikawa cells.

CONCLUSION

SPRY4 may function as a tumor suppressor in endometrial adenocarcinoma.

Functional Epigenetic Analysis of Prostate Carcinoma: A Role for Seryl-tRNA Synthetase?

Transcriptional silencing, as a result of aberrant promoter hypermethylation, is a common mechanism through which genes in cancer cells become inactive. Functional epigenetic screens using demethylating agents to reexpress transcriptional silenced genes may identify such inactivated genes for needing further evaluation. We aimed to identify genes so far not known to be inactivated by promoter hypermethylation in prostate cancer. DU-145 and LNCaP cells were treated with the DNMT inhibitor zebularine. Expression changes of total RNA from treated and untreated cells were compared using an RNA expression microarray. Genes upregulated more than 2-fold were evaluated by RT-qPCR in 50 cases of paired normal and tumor tissues of prostate cancer patients. SARS was found to be downregulated in prostate cancer in 42/50 cases (84%). In addition, GADD45A and SPRY4 showed a remarkable diminished expression (88% and 74%, resp.). The gold standard for promoter hypermethylation-inactivated genes in prostate cancer (GSTP1) was repressed in 90% of our patient samples. ROC analyses reported statistically significant AUC curves in SARS, GADD45A, and GSTP1 and positive Spearman correlations were found between these genes. SARS was discovered to be a novel gene that is repressed in prostate cancer and could therefore be recommended for its involvement in prostate carcinogenesis.

Sprouty4 interferes with cell proliferation and migration of breast cancer-derived cell lines

Sprouty proteins are modulators of mitogen-induced signal transduction processes and therefore can influence the process of cancerogenesis. In particular, Sprouty2 has been shown to have an important role in cancer development of many tumor entities including breast cancer. In this report, we investigated the role of Sprouty4 in breast cancer-derived cell lines. We have found that ectopic Sprouty4 expression inhibits cell proliferation of breast cancer cell lines independently of their endogenous expression levels. Corroborating Sprouty4 downregulation causes accelerated growth. Furthermore, we demonstrate that an increase in Sprouty4 content interferes with serum-induced activation of mitogen-activated protein kinase pathway. Additionally, Sprouty4 expression negatively influences cell migration. These data suggest that Sprouty4 is a possible candidate for a tumor suppressor in breast cancer.

Relative impact of multi-layered genomic data on gene expression phenotypes in serous ovarian tumors

Background

The emerging multi-layers of genomic data have provided unprecedented opportunities for cancer research, especially for the association study between gene expressions and other types of genomic features. No previous approaches, however, provide an adequate statistical framework for or global analysis on the relative impact of different genomic feature layers to gene expression phenotypes.

Methods

We propose an integrative statistical framework based on a sparse regression to model the impact of multi-layered genomic features on gene expression traits. The proposed approach can be regarded as an integrative expression Quantitative Traits Loci approach in which not only the genetic variations of SNPs or copy number variations but also other features in both genomic and epigenomic levels are used to explain the expression of genes. To highlight the validity of the proposed approach, the TCGA ovarian cancer dataset was analysed as a pilot task.

Results

The analysis shows that our integrative approach has consistently superior power in predicting gene expression levels compared to that from each single data type-based analysis. Moreover, the proposed method has the advantage of producing a substantially reduced number of spurious associations. We provide an interesting characterization of genes in terms of its genomic association patterns. Important genomic features reported in previous ovarian cancer research are successfully identified as major hubs in the resulting association network between heterogeneous types of genomic features and genes.

Conclusions

In this paper, we model the gene expression phenotypes with respect to multiple different types of genomic data in an integrative framework. Our analysis reveals the global view on the relative contribution of different genomic feature types to gene expression phenotypes in ovarian cancer.

Sprouty2 but not Sprouty4 is a potent inhibitor of cell proliferation and migration of osteosarcoma cells

As negative regulators of receptor tyrosine kinase-mediated signalling, Sprouty proteins fulfil important roles during carcinogenesis. In this report, we demonstrate that Sprouty2 protein expression inhibits cell proliferation and migration in osteosarcoma-derived cells. Although earlier reports describe a tumour-promoting function, these results indicate that Sprouty proteins also have the potential to function as tumour suppressors in sarcoma. In contrast to Sprouty2, Sprouty4 expression failed to interfere with proliferation and migration of the osteosarcoma-derived cells, possibly due to a less pronounced interference with mitogen-activated protein kinase activity. Sequences within the NH2-terminus are responsible for the specific inhibitory function of Sprouty2 protein.

Initial report on differential expression of sprouty proteins 1 and 2 in human epithelial ovarian cancer cell lines

Sprouty (Spry) proteins, modulators of receptor tyrosine kinase signaling pathways, have been shown to be deregulated in a variety of pathological conditions including cancer. In the present study we investigated the expression of Spry1 and Spry2 isoforms in a panel of human ovarian cancer cell lines in vitro. Our western blot analysis showed nonuniform patterns of Spry expression in the cancer cells, none of which conformed to the pattern observed in the normal ovarian epithelial cells employed as the control. Among the seven cancer cell lines studied, Spry1 was expressed lower in four cell lines and higher in one as compared with the control. As for Spry2, four cell lines showed lower and two exhibited higher expression. Results from RT-PCR assay raised the possibility that Spry protein levels may not necessarily correspond with its expression at mRNA level. Our immunostaining study revealed that Spry2 was predominantly distributed within the whole cytoplasm in vesicular structures whereas Spry1 was found in both the cytoplasm and nucleus. This might provide clues to further investigation of Spry mode of action and/or function. Collectively, our study unveiled the differential expression of Spry1 and Spry2 proteins in various ovarian cancer cell lines.

Targeting fibroblast growth factor receptor signaling inhibits prostate cancer progression

PURPOSE

Extensive correlative studies in human prostate cancer as well as studies in vitro and in mouse models indicate that fibroblast growth factor receptor (FGFR) signaling plays an important role in prostate cancer progression. In this study, we used a probe compound for an FGFR inhibitor, which potently inhibits FGFR-1-3 and significantly inhibits FGFR-4. The purpose of this study is to determine whether targeting FGFR signaling from all four FGFRs will have in vitro activities consistent with inhibition of tumor progression and will inhibit tumor progression in vivo.

EXPERIMENTAL DESIGN

Effects of AZ8010 on FGFR signaling and invasion were analyzed using immortalized normal prostate epithelial (PNT1a) cells and PNT1a overexpressing FGFR-1 or FGFR-4. The effect of AZ8010 on invasion and proliferation in vitro was also evaluated in prostate cancer cell lines. Finally, the impact of AZ8010 on tumor progression in vivo was evaluated using a VCaP xenograft model.

RESULTS

AZ8010 completely inhibits FGFR-1 and significantly inhibits FGFR-4 signaling at 100 nmol/L, which is an achievable in vivo concentration. This results in marked inhibition of extracellular signal-regulated kinase (ERK) phosphorylation and invasion in PNT1a cells expressing FGFR-1 and FGFR-4 and all prostate cancer cell lines tested. Treatment in vivo completely inhibited VCaP tumor growth and significantly inhibited angiogenesis and proliferation and increased cell death in treated tumors. This was associated with marked inhibition of ERK phosphorylation in treated tumors.

CONCLUSIONS

Targeting FGFR signaling is a promising new approach to treating aggressive prostate cancer.

Sprouty 2 is an independent prognostic factor in breast cancer and may be useful in stratifying patients for trastuzumab therapy

BACKGROUND

Resistance to trastuzumab is a clinical problem, partly due to overriding activation of MAPK/PI3K signalling. Sprouty-family proteins are negative regulators of MAPK/PI3K signalling, but their role in HER2-therapy resistance is unknown.

PATIENTS AND METHODS

Associations between Sprouty gene expression and clinicopathological features were investigated in a breast cancer microarray meta-analysis. Changes in expression of Spry2 and feedback inhibition on trastuzumab resistance were studied in SKBr3 and BT474 breast carcinoma cell lines using cell viability assays. Spry2 protein expression was measured by quantitative immunofluorescence in a cohort of 122 patients treated with trastuzumab.

RESULTS

Low gene expression of Spry2 was associated with increased pathological grade, high HER2 expression, and was a significant independent prognostic factor. Overexpression of Spry2 in SKBr3s resulted in enhanced inhibition of cell viability after trastuzumab treatment, and the PI3K-inhibitor LY294002 had a similar effect. Low Spry2 expression was associated with increased risk of death (HR = 2.28, 95% CI 1.22-4.26; p = 0.008) in trastuzumab-treated patients, including in multivariate analysis. Stratification of trastuzumab-treated patients using PTEN and Spry2 was superior to either marker in isolation.

CONCLUSION

In breast cancers with deficient feedback inhibition, combinatorial therapy with negative regulators of growth factor signalling may be an effective therapeutic strategy.

Integrated miRNA and mRNA expression profiling of mouse mammary tumor models identifies miRNA signatures associated with mammary tumor lineage

Background

MicroRNAs (miRNAs) are small, non-coding, endogenous RNAs involved in regulating gene expression and protein translation. miRNA expression profiling of human breast cancers has identified miRNAs related to the clinical diversity of the disease and potentially provides novel diagnostic and prognostic tools for breast cancer therapy. In order to further understand the associations between oncogenic drivers and miRNA expression in sub-types of breast cancer, we performed miRNA expression profiling on mammary tumors from eight well-characterized genetically engineered mouse (GEM) models of human breast cancer, including MMTV-H-Ras, -Her2/neu, -c-Myc, -PymT, -Wnt1 and C3(1)/SV40 T/t-antigen transgenic mice, BRCA1^fl/fl;p53^+/-;MMTV-cre knock-out mice and the p53^fl/fl;MMTV-cre transplant model.

Results

miRNA expression patterns classified mouse mammary tumors according to luminal or basal tumor subtypes. Many miRNAs found in luminal tumors are expressed during normal mammary development. miR-135b, miR-505 and miR-155 are expressed in both basal human and mouse mammary tumors and many basal-associated miRNAs have not been previously characterized. miRNAs associated with the initiating oncogenic event driving tumorigenesis were also identified. miR-10b, -148a, -150, -199a and -486 were only expressed in normal mammary epithelium and not tumors, suggesting that they may have tumor suppressor activities. Integrated miRNA and mRNA gene expression analyses greatly improved the identification of miRNA targets from potential targets identified in silico.

Conclusions

This is the first large-scale miRNA gene expression study across a variety of relevant GEM models of human breast cancer demonstrating that miRNA expression is highly associated with mammary tumor lineage, differentiation and oncogenic pathways.

Transcriptional and post-transcriptional regulation of Sprouty1, a receptor tyrosine kinase inhibitor in prostate cancer

Sprouty1 (Spry1) is a negative regulator of fibroblast growth factor signaling with a potential tumor suppressor function in prostate cancer (PCa). Spry1 is downregulated in human PCa, and Spry1 expression can markedly inhibit PCa proliferation in vitro. We have reported DNA methylation as a mechanism for controlling Spry1 expression. However, promoter methylation does not seem to explain gene silencing in all PCa cases studied to suggest other mechanisms of gene inactivation, such as alterations in trans-acting factors and/or post-transcriptional activity may be responsible for the decreased expression in those cases. Binding sites for Wilm's tumor (WT1) transcription factors EGR1, EGR3 and WTE are highly conserved between the mouse and human Spry1 promoter regions, suggesting an evolutionary conserved mechanism(s) involving WT1 and EGR in Spry1 regulation. Spry1 mRNA contains multiple microRNA (miRNA) binding sites in its 3'UTR region suggesting post-transcriptional control. We demonstrate that Spry1 is a target for miR-21-mediated gene silencing. miRNA-based therapeutic approaches to treat cancer are emerging. Spry1 is highly regulated by miRNAs and could potentially be an excellent candidate for such approaches.

Targeting fibroblast-growth-factor-receptor-dependent signaling for cancer therapy

INTRODUCTION

Fibroblast growth factors (FGF) exert a combination of biological effects that contribute to four of the six essential hallmarks of cancer. It is no surprise that FGF-dependent signaling has increasingly moved to the center of cancer therapy research during the past decade. This is illustrated by the large number of publications focusing on various aspects of this theme that have been published in the past 5 years.

AREAS COVERED

Information from these sources as well as ongoing work from the authors' groups is used to outline the physiological functions of FGF signaling and to highlight how the high oncogenic effects of deregulated FGFs and FGFRs derive from their physiological functions. The biological effect of deregulated FGFR signaling in malignant diseases is described and the current state of therapeutic targeting of FGFR is summarized.

EXPERT OPINION

Strategies for targeting FGFR-signaling for cancer therapy are very promising, but need to be carefully developed based on the physiological roles of FGF signaling. Preventive measures may be necessary for protection from FGF-related side effects. Combined targeting of several receptor tyrosine kinases or combination with other therapies may be a useful way of avoiding or ameliorating side effects. FGF-related markers of prognosis and therapy response still need to be investigated.

Expression and functional role of negative signalling regulators in tumour development and progression

Alterations in intracellular signalling pathways such as the mitogen-activated protein kinases (MAPKs) are key common mechanisms of tumour development and progression. As such, there has been intense research into developing drugs that can inhibit or attenuate intracellular signalling. In recent years, there has been increasing recognition that the cell already has innate negative regulatory proteins that achieve this in normal homeostasis. These regulators provide a feedback inhibitory mechanism that controls the intensity and duration of activated signalling by exogenous stimuli. Members of this group include Raf kinase inhibitor protein 1, the MAPK phosphatases, the SPROUTY and SPRED families and similar expression to FGF. A number of studies have now demonstrated significant alterations in expression of negative regulators in malignant tissue in different cancer types. In functional studies, manipulated expression of these regulators has been shown to significantly influence tumour cell behaviour and phenotype. Here, we summarise the evidence for the functional expression of negative signalling regulators in tumour growth and progression and discuss their potential role as cancer biomarkers and targets for novel drug therapy.

Sprouty-4 inhibits transformed cell growth, migration and invasion, and epithelial-mesenchymal transition, and is regulated by Wnt7A through PPARgamma in non-small cell lung cancer

Sprouty proteins are potent receptor tyrosine kinase inhibitors that antagonize growth factor signaling and are involved in lung development. However, little is known about the regulation or targets of Sprouty-4 (Spry4) in lung cancer. Our study aimed to determine the role of Spry4 in non-small cell lung cancer (NSCLC). We found that Spry4 mRNA expression was decreased in NSCLC cell lines and in dysplastic lung cell lines compared with a nontransformed cell line, suggesting that Spry4 has tumor-suppressing activity. When Spry4 was stably transfected into H157 and H2122 NSCLC cell lines, decreased migration and invasion were observed. Matrix metalloproteinase-9 activity was decreased, and the expression of matrix metalloproteinase inhibitors TIMP1 and CD82 were increased. Stable expression of Spry4 led to reduced cell growth and reduced anchorage-independent growth in NSCLC cell lines, along with upregulation of tumor suppressors p53 and p21. Changes in epithelial and mesenchymal markers indicated that Spry4 expression induces a reversal of the epithelial to mesenchymal transition characteristic of tumor cells. Treatment of a nontransformed lung epithelial cell line with short hairpin RNA to Spry4 led to the decreased expression of epithelial markers and increased cell growth, supporting the concept of Spry4 acting as a tumor suppressor. We showed that the activity of the Spry4 promoter is increased by Wnt7A/Fzd9 signaling through peroxisome proliferator-activated receptor gamma. These data present previously undescribed targets of Spry4 and suggest that Spry4 is a downstream target of Wnt7A/Fzd 9 signaling. Spry4 may have efficacy in the treatment of NSCLC.

Bimodal expression of Sprouty2 during the cell cycle is mediated by phase-specific Ras/MAPK and c-Cbl activities

Sprouty2 is an important inhibitor of cell proliferation and signal transduction. In this study, we found a bimodal expression of Sprouty2 protein during cell cycle progression after exit from quiescence, whereas elevated Sprouty4 expression in the G1 phase stayed high throughout the rest of the cell cycle. Induction of the mitogen-activated protein kinase via activated Ras was crucial for increased Sprouty2 expression at the G0/G1 transition. Following the first peak, accelerated proteasomal protein degradation caused a transient attenuation of Sprouty2 abundance during late G1. Since the decline in its expression was abolished by dominant negative c-Cbl and the timely restricted interaction between Sprouty2 and c-Cbl disappeared at the second peak of Sprouty2 expression, we conclude that the second phase in the cell cycle-specific expression profile of Sprouty2 is solely dependent on ubiquitination by c-Cbl. Our results suggest that Sprouty2 abundance is the result of strictly coordinated activities of Ras and c-Cbl.