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

LncRNA SLNCR1 facilitates angiogenesis and tumor growth in melanoma via DNMT1-mediated epigenetically silencing SPRY2

BACKGROUND

The malignancy of melanoma is attributed to its pronounced invasiveness, extensive vascularization, and rapid tumor cell growth and metastasis. LncRNA SLNCR1 is closely associated with a variety of aggressive tumors. However, our understanding of SLNCR1 influences on malignant melanoma growth metastasis mechanism especially proangiogenic mechanism remains unclear.

METHODS

The expression of SLNCR1 was evaluated in melanoma tissues, adjacent tissues, melanoma cell lines. The abilities of SLNCR1 on proliferation, migration, and angiogenesis of HUVECs were detected by CCK-8, flow cytometry, and Western blot assays. The association between SLNCR1, DNMT1, and SPRY2 was assessed by ChIP, RIP, and Western blot assays. The effect of SLNCR1 on tumor growth was determined using a xenograft model in nude mice.

RESULTS

SLNCR1 was confirmed to be highly expressed in melanoma tissues and cells. CM from melanoma cells transfected with sh-SLNCR1 attenuated proliferation, migration, and angiogenesis of HUVECs. Moreover, loss of SLNCR1 hindered tumor growth and metastasis, as evidenced by reduced tumor size and weight, as well as angiogenesis. Mechanistic studies revealed that SLNCR1 silenced SPRY2 expression, likely through enhancing DNMT1-mediated DNA methylation of SPRY2 promoter.

CONCLUSION

SLNCR1 is an oncogene that interacts with DNMT1 to mediate SPRY2 methylation, thereby suppressing SPRY2 expression and promoting the angiogenesis and tumor growth in melanoma. SLNCR1 may serve as a potential target for melanoma treatment.

Loss of SPRY2 contributes to cancer-associated fibroblasts activation and promotes breast cancer development

The communication between tumor cells and tumor microenvironment plays a critical role in cancer development. Cancer-associated fibroblasts (CAFs) are the major components of the tumor microenvironment and take part in breast cancer formation and progression. Here, by comparing the gene expression patterns in CAFs and normal fibroblasts, we found SPRY2 expression was significantly decreased in CAFs and decreased SPRY2 expression was correlated with worse prognosis in breast cancer patients. SPRY2 knockdown in fibroblasts promoted tumor growth and distant metastasis of breast cancer in mice. Loss of stromal SPRY2 expression promoted CAF activation dependent on glycolytic metabolism. Mechanically, SPRY2 suppressed Y10 phosphorylation of LDHA and LDHA activity by interfering with the interaction between LDHA and SRC. Functionally, SPRY2 knockdown in fibroblasts enhanced the stemness of tumor cell dependent on glycolysis in fibroblasts. Collectively, this work identified SPRY2 as a negative regulator of CAF activation, and SPRY2 in CAFs may potentially be therapeutically targeted in breast cancer treatment.

Crocin suppresses breast cancer cell proliferation by down-regulating tumor promoter miR-122-5p and up-regulating tumor suppressors FOXP2 and SPRY2

Crocin has been reported to have antitumor activity in several tumors including breast cancer. Nevertheless, the mechanism of action of crocin on breast cancer remains unclear. The cytotoxicity of crocin was evaluated by CCK-8 assay. Cell proliferation was assessed using EdU incorporation assay and western blot analysis. Breast cancer-related genes were extracted from GEPIA. miR-122-5p targets were predicted using Targetscan, starbase, and miRDB softwares. Luciferase reporter assay was employed to confirm whether miR-122-5p targeted sprouty2 (SPRY2) and forkhead box P2 (FOXP2). Results showed that crocin exhibited cytotoxicity and suppressed the proliferation in breast cancer cells. miR-122-5p was upregulated in breast cancer tissues and cells. Crocin suppressed miR-122-5p to block the proliferation of breast cancer cells. Seven targets of miR-122-5p were identified in breast cancer. SPRY2 and FOXP2 were selected for further experiments due to their involvement in breast cancer. miR-122-5p targeted SPRY2 and FOXP2 to inhibit their expression. miR-122-5p knockdown restrained breast cancer cell proliferation by targeting SPRY2 and FOXP2. Additionally, crocin increased SPRY2 and FOXP2 expression by inhibiting miR-122-5p expression. Together, our results suggested that crocin inhibited proliferation of breast cancer cells through decreasing miR-122-5p expression and the subsequent increase of SPRY2 and FOXP2 expression.

Sprouty 4 suppresses glioblastoma invasion by inhibiting ERK phosphorylation and ETS-1-induced matrix metalloproteinase-9

BACKGROUND

Glioblastoma multiforme (GBM) is the most malignant glioma with highly aggressive behavior and the worst prognosis. Many efforts have been made to develop new drugs and improve the patient's survival, but the effects are not satisfactory. Here we aimed to evaluate the clinical significance and tumor-repressive function of Sprouty4 (SPRY4) in GBM.

METHODS

In our study, we detected the expression of SPRY4 in 109 GBM patients and 12 pairs of GBM tissues and the corresponding adjacent tissues. χ² test was applied to analyze the association between SPRY4 expression and the clinicopathological factors. The prognostic significances were evaluated with univariate and multivariate analyses, which were carried out by the Kaplan-Meier method and the Cox-regression proportional hazards model, respectively. With in-vitro experiments, we investigated the tumor-suppressing function of SPRY4 in GBM invasion and investigated the underlying mechanism.

RESULTS

SPRY4 mRNAs in GBMs were significantly lower than those in adjacent brain tissues. We demonstrated that SPRY4 expression could predict the favorable prognosis of GBM, and SPRY4 was an independent favorable prognostic factor of GBM. SPRY4 repressed GBM invasion via inhibiting ERK phosphorylation; therefore, suppressing ETS-1-induced MMP9 expression.

CONCLUSIONS

SPRY4 was an independent favorable prognostic factor of GBM, and it could suppress GBM invasion by ERK-ETS-MMP9 axis. Our results indicated that SPRY4 may be a promising drug target of GBM and SPRY4 detection could stratify patients with low SPRY4 expression who may benefit from anti-FGFR therapy.

HOXA1, a breast cancer oncogene

More than 25 years ago, the first literature records mentioned HOXA1 expression in human breast cancer. A few years later, HOXA1 was confirmed as a proper oncogene in mammary tissue. In the following two decades, molecular data about the mode of action of the HOXA1 protein, the factors contributing to activate and maintain HOXA1 gene expression and the identity of its target genes have accumulated and provide a wider view on the association of this transcription factor to breast oncogenesis. Large-scale transcriptomic data gathered from wide cohorts of patients further allowed refining the relationship between breast cancer type and HOXA1 expression. Several recent reports have reviewed the connection between cancer hallmarks and the biology of HOX genes in general. Here we take HOXA1 as a paradigm and propose an extensive overview of the molecular data centered on this oncoprotein, from what its expression modulators, to the interactors contributing to its oncogenic activities, and to the pathways and genes it controls. The data converge to an intricate picture that answers questions on the multi-modality of its oncogene activities, point towards better understanding of breast cancer aetiology and thereby provides an appraisal for treatment opportunities.

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.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

Sprouty4 correlates with favorable prognosis in perihilar cholangiocarcinoma by blocking the FGFR-ERK signaling pathway and arresting the cell cycle

Background

Perihilar cholangiocarcinoma (PHCC) is the most common subtype of cholangiocarcinoma(CCA). We previously investigated the expression pattern of Sprouty(SPRY) in intrahepatic cholangiocarcinoma(ICC), but the expression and clinical significance of SPRY family members in PHCC are still unknown.

Methods

The expression of SPRY family members(SPRY1-4) was detected in different subtypes of CCA and corresponding adjacent tissues. SPRY4 expression in 142 cases of PHCC was detected by immunohistochemistry, and its clinical significance was evaluated using univariate and multivariate analyses. The functions of SPRY4 in the FGFR-induced proliferation and migration of PHCC cells were investigated through in vitro and in vivo experiments. We further investigated the effects and mechanisms of SPRY4 on FGFR-induced ERK phosphorylation and cell cycle distribution in the presence of FGFR and ERK inhibitors.

Findings

SPRY4 was the only SPRY family member associated with PHCC prognosis, and it was identified as an independent factor predicting favorable prognosis. In PHCC, SPRY4 expression was extensively associated with FGFR2, and its expression can be induced by ectopic FGFR2 activation. Through in vitro and in vivo experiments, we demonstrated that SPRY4 suppressed FGFR-induced proliferation and migration by inhibiting ERK phosphorylation. Moreover, SPRY4 knockdown was shown to decrease the percentage of cells in the G1 phase and promote the percentage of cells in the S and G2/M phases by increasing cyclin D1 expression, which also required FGFR-induced ERK phosphorylation.

Interpretation

High expression of SPRY4 was an independent biomarker of favorable prognosis in PHCC. SPRY4 expression can be induced by ectopic FGFR2 activation in PHCC. SPRY4 arrested the cell cycle at G1 phase and suppressed FGFR-induced proliferation and migration by inhibiting ERK phosphorylation, indicating that SPRY4 may be a potential therapeutic target in PHCC.

Quantitative Phosphoproteomics Reveals System-Wide Phosphorylation Network Altered by Spry in Mouse Mammary Stromal Fibroblasts

Understanding the fundamental role of the stroma in normal development and cancer progression has been an emerging focus in recent years. The receptor tyrosine kinase (RTK) signaling pathway has been reported playing critical roles in regulating the normal and cancer microenvironment, but the underlying mechanism is still not very clear. By applying the quantitative phosphoproteomic analysis of Sprouty proteins (SPRYs), generic modulators of RTK signaling and deleted mouse mammary fibroblasts, we quantified a total of 11,215 unique phosphorylation sites. By contrast, 554 phosphorylation sites on 425 proteins had SPRY-responsive perturbations. Of these, 554 phosphosites, 362 sites on 277 proteins, were significantly increased, whereas 192 sites on 167 proteins were decreased. Among the regulated proteins, we identified 31 kinases, 7 phosphatases, and one phosphatase inhibitor that were not systematically characterized before. Furthermore, we reconstructed a phosphorylation network centered on RTK signaling regulated by SPRY. Collectively, this study uncovered a system-wide phosphorylation network regulated by SPRY, providing an additional insight into the complicated RTK signaling pathways involved in the mammary gland microenvironment.

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.

Expression Signatures of Cisplatin- and Trametinib-Treated Early-Stage Medaka Melanomas

Small aquarium fish models provide useful systems not only for a better understanding of the molecular basis of many human diseases, but also for first-line screening to identify new drug candidates. For testing new chemical substances, current strategies mostly rely on easy to perform and efficient embryonic screens. Cancer, however, is a disease that develops mainly during juvenile and adult stage. Long-term treatment and the challenge to monitor changes in tumor phenotype make testing of large chemical libraries in juvenile and adult animals cost prohibitive. We hypothesized that changes in the gene expression profile should occur early during anti-tumor treatment, and the disease-associated transcriptional change should provide a reliable readout that can be utilized to evaluate drug-induced effects. For the current study, we used a previously established medaka melanoma model. As proof of principle, we showed that exposure of melanoma developing fish to the drugs cisplatin or trametinib, known cancer therapies, for a period of seven days is sufficient to detect treatment-induced changes in gene expression. By examining whole body transcriptome responses we provide a novel route toward gene panels that recapitulate anti-tumor outcomes thus allowing a screening of thousands of drugs using a whole-body vertebrate model. Our results suggest that using disease-associated transcriptional change to screen therapeutic molecules in small fish model is viable and may be applied to pre-clinical research and development stages in new drug discovery.

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.

Increased expression of miR-27 predicts poor prognosis and promotes tumorigenesis in human multiple myeloma

Multiple myeloma (MM) is an incurable hematological malignancy characterized by abnormal infiltration of plasma cells in the bone marrow. MicroRNAs (miRNAs) have emerged as crucial regulators in human tumorigenesis and tumor progression. miR-27, a novel cancer-related miRNA, has been confirmed to be implicated in multiple types of human tumors; however, its biological role in MM remains largely unknown. The present study aimed to characterize the biological role of miR-27 in MM and elucidate the potential molecular mechanisms. Here we found that miR-27 was significantly up-regulated in MM samples compared with normal bone marrow samples from healthy donors. Moreover, the log-rank test and Kaplan-Meier survival analysis displayed that MM patients with high miR-27 expression experienced a significantly shorter overall survival than those with low miR-27 expression. In the current study, we transfected MM cells with miR-27 mimics or miR-27 inhibitor to manipulate its expression. Functional studies demonstrated that miR-27 overexpression promoted MM cell proliferation, facilitated cell cycle progression, and expedited cell migration and invasion; whereas miR-27 knockdown inhibited cell proliferation, induced cell cycle arrest, and slowed down cell motility. Mechanistic studies revealed that Sprouty homolog 2 (SPRY2) was a direct target of miR-27 and that rescuing SPRY2 expression reversed the promoting effects of miR-27 on MM cell proliferation, migration, and invasion. Besides, miR-27 ablation suppressed tumorigenecity of MM cells in mouse xenograft models. Collectively, our data indicate that miR-27 exerts its oncogenic functions in MM by targetting SPRY2 and that miR-27 may be used as a promising candidate target in MM treatment.

Regulation Is in the Air: The Relationship between Hypoxia and Epigenetics in Cancer

Hypoxia is an inherent condition of tumors and contributes to cancer development and progression. Hypoxia-inducible factors (HIFs) are the major transcription factors involved in response to low O₂ levels, orchestrating the expression of hundreds of genes involved in cancer hallmarks’ acquisition and modulation of epigenetic mechanisms. Epigenetics refers to inheritable mechanisms responsible for regulating gene expression, including genes involved in the hypoxia response, without altering the sequence of DNA bases. The main epigenetic mechanisms are DNA methylation, non-coding RNAs, and histone modifications. These mechanisms are highly influenced by cell microenvironment, such as O₂ levels. The balance and interaction between these pathways is essential for homeostasis and is directly linked to cellular metabolism. Some of the major players in the regulation of HIFs, such as prolyl hydroxylases, DNA methylation regulators, and histone modifiers require oxygen as a substrate, or have metabolic intermediates as cofactors, whose levels are altered during hypoxia. Furthermore, during pathological hypoxia, HIFs’ targets as well as alterations in epigenetic patterns impact several pathways linked to tumorigenesis, such as proliferation and apoptosis, among other hallmarks. Therefore, this review aims to elucidate the intricate relationship between hypoxia and epigenetic mechanisms, and its crucial impact on the acquisition of cancer hallmarks.

A potential clinical significance of DAB2IP and SPRY2 transcript variants in prostate cancer

Deregulation of key signaling pathways is one of the primary phenomena in carcinogenesis. DAB2IP and SPRY2 are regulatory elements, which act as feedback inhibitors of receptor tyrosine kinases signaling in mitogen-activated protein kinase pathway. These elements have also been implicated in the pathophysiology of cancer. Therefore, this study is aimed to investigate the expression of all known splice variants of DAB2IP and SPRY2 in prostate tissue. Fresh Prostate tissue samples (50 prostate cancer/ matched normal tissue and 30 BPH) were collected and total RNA was extracted followed by cDNA synthesis. The expression of DAB2IP and SPRY2 transcript variants were evaluated using RT-PCR and quantitative Real-time PCR. The results indicated significant down-regulation of DAB2IP transcript variant 1 in cancerous tissues compared to paired normal tissues (P = 0.001) as well as SPRY2 transcript variant 2 in cancerous tissues in comparison with the normal counterparts and BPH (P = 0.008 and P = 0.025, respectively). In addition, there was a significant negative correlation between DAB2IP.1 and SPRY2.2 expression with PSA levels in prostate cancer (P = 0.039 ρ =-0.24 and P = 0.045 ρ =-0.3, respectively). Interestingly, the down-regulation of DAB2IP.1 mRNA and SPRY2.2 mRNA was positively correlated in tumor samples (P = 0.002 ρ = 0.434). For the first time, this experiment highlights the deregulation of DAB2IP and SPRY2 transcript variants in human prostate cancer. The present study confirms and extends the previous reports through indicating transcript-specific down-regulation and significant association of DAB2IP and SPRY2 in prostate tumorigenesis.

Sprouty2 suppresses progression and correlates to favourable prognosis of intrahepatic cholangiocarcinoma via antagonizing FGFR2 signalling

Fibroblast growth factor receptor 2 (FGFR2) was demonstrated to correlate to the progression and prognosis of intrahepatic cholangiocarcinoma (ICC) by numerous evidences. However, as a well‐recognized suppressor of FGFR2 signalling, the clinical significance of Sprouty (SPRY) family of ICC has not been investigated. In our study, the expressions of SPRY1‐4 in 20 pairs of fresh tumour tissues were detected with qPCR, and in 108 cases of paraffin‐embedded tissues with immunohistochemistry. The prognostic value of SPRY family in ICC was estimated with univariate analysis and multivariate analysis. As a result, SPRY2 was identified as an independent prognostic biomarker predicting favourable prognosis of ICC. High SPRY2 expression was correlated with good differentiation of ICC. With silencing SPRY2 expression, we demonstrated that SPRY2 could suppress FGFR2‐induced ERK phosphorylation, migration, invasion and epithelial‐mesenchymal transition (EMT) under FGF1 stimulation. By overexpressing SPRY2‐wide type or SPRY2‐Y55F, the tyrosine‐55 of SPRY2 was demonstrated to be essential in suppressing ERK phosphorylation, tumour invasion and EMT of ICC cells. In conclusion, SPRY2 was correlated with favourable prognosis of ICC via suppressing FGFR2‐induced ERK phosphorylation, invasion and EMT. The phosphorylation of SPRY2‐Y55 was required in this tumour‐suppressing function of SPRY2.

Review of recent efforts to discover biomarkers for early detection, monitoring, prognosis, and prediction of treatment responses of patients with gastric cancer

Gastric cancer (GC) is the leading cause of cancer-related death worldwide. Despite recent advances in diagnosis and therapy, the prognosis of patients with GC is poor. Many patients have inoperable disease upon diagnosis or experience recurrent disease after curative gastrectomy. Unfortunately, tumor markers for GC, such as serum carcinoembryonic antigen and carbohydrate antigen 19-9, lack sufficient sensitivity and specificity. Therefore, effective biomarkers are required to detect early GC and to predict tumor recurrence and chemosensitivity. Areas covered: Here we aimed to review recent developments in techniques that improve the detection of aberrant expression of GC-associated molecules, including protein coding genes, microRNAs, long noncoding RNAs, and methylated promoter DNAs. Expert commentary: Detection of genetic and epigenetic alterations in gastric tissue or in the circulation will likely improve the diagnosis and management of GC to achieve significantly improved outcomes.

SIK2 attenuates proliferation and survival of breast cancer cells with simultaneous perturbation of MAPK and PI3K/Akt pathways

Salt Inducible Kinase2 (SIK2) has been shown to contribute to tumorigenesis in multiple tumor types in a dichotomous manner. However, little is known about its contribution to breast malignancies. Here, we report SIK2 as a potential tumor suppressor in breast cancer whose expression was reduced in tumor tissues and breast cancer cell lines compared to normal counterparts. In vitro loss- and gain-of-function experiments combined with xenograft studies demonstrated that SIK2-mediated attenuation of proliferation and survival of breast cancer cells with parallel inhibition of both Ras/Erk and PI3K/Akt pathways. Our findings elucidated that SIK2 has also an inhibitory role in migration/invasion ability of breast cancer cells through regulation of epithelial mesenchymal transition. Immunostaining of patient tumors revealed that SIK2 protein level is frequently downregulated in invasive mammary carcinomas and negatively correlated with the mitotic activity of the cells in triple negative breast cancers and hormone positive tumors. Strikingly, patient survival analysis indicated that higher levels of SIK2 are significantly associated with better survival, especially in basal breast cancer cases. Overall, our findings suggest SIK2 as a potential tumor suppressor in the control of breast tumorigenesis, at least in part, via inhibiting PI3K/Akt and Ras/ERK signaling cascades simultaneously and a novel prognostic marker, especially in basal subtypes of breast cancer.

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.

Sprouty2 correlates with favorable prognosis of gastric adenocarcinoma via suppressing FGFR2-induced ERK phosphorylation and cancer progression

Fibroblast growth factor receptor 2 (FGFR2) has been identified as a predictive biomarker for unfavorable prognosis of gastric adenocarcinoma. As a well-defined antagonist in FGFR2-induced RAS/ERK activation, ectopic expression of sprouty (SPRY) family was reported in several kinds of cancers except gastric cancer. To explore the clinical significance of SPRY family and its correlation with FGFR2, we detected the expression of FGFR2 and SPRY family in 104 cases of gastric adenocarcinoma and subsequently analyzed their correlations with clinicopathological factors and overall survival rates by univariate and multivariate analysis. As the result, we demonstrated that both FGFR2 high-expression and SPRY2 low-expression indicated poorer prognosis of gastric adenocarcinoma. SPRY2 low-expression was significantly associated with FGFR2 high-expression, positive lymphatic invasion and metastasis. We further proved that SPRY2 could suppress FGFR2-induced ERK phosphorylation, cell proliferation and invasion with experiments in vitro and in vivo. In conclusion, we demonstrated that SPRY2 low-expression is a biomarker for unfavorable prognosis in gastric adenocarcinoma. SPRY2 can antagonize FGFR2-induced proliferation and invasion via suppressing ERK phosphorylation in gastric cancer cells, indicating SPRY2 as a potential therapeutic target for gastric adenocarcinoma treatment.

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.

Sprouty2 Protein Regulates Hypoxia-inducible Factor-α (HIFα) Protein Levels and Transcription of HIFα-responsive Genes

The α-subunits of hypoxia-inducible factors (HIF1α and HIF2α) promote transcription of genes that regulate glycolysis and cell survival and growth. Sprouty2 (Spry2) is a modulator of receptor tyrosine kinase signaling and inhibits cell proliferation by a number of different mechanisms. Because of the seemingly opposite actions of HIFα subunits and Spry2 on cellular processes, we investigated whether Spry2 regulates the levels of HIF1α and HIF2α proteins. In cell lines from different types of tumors in which the decreased protein levels of Spry2 have been associated with poor prognosis, silencing of Spry2 elevated HIF1α protein levels. Increases in HIF1α and HIF2α protein levels due to silencing of Spry2 also up-regulated HIFα target genes. Using HIF1α as a prototype, we show that Spry2 decreases HIF1α stability and enhances the ubiquitylation of HIF1α by a von Hippel-Lindau protein (pVHL)-dependent mechanism. Spry2 also exists in a complex with HIF1α. Because Spry2 can also associate with pVHL, using a mutant form of Spry2 (3P/3A-Spry2) that binds HIF1α, but not pVHL, we show that WT-Spry2, but not the 3P/3A-Spry2 decreases HIF1α protein levels. In accordance, expression of WT-Spry2, but not 3P/3A-Spry2 results in a decrease in HIF1α-sensitive glucose uptake. Together our data suggest that Spry2 acts as a scaffold to bring more pVHL/associated E3 ligase in proximity of HIF1α and increase its ubiquitylation and degradation. This represents a novel action for Spry2 in modulating biological processes regulated by HIFα subunits.

Suppression of Spry1 inhibits triple-negative breast cancer malignancy by decreasing EGF/EGFR mediated mesenchymal phenotype

Sprouty (Spry) proteins have been implicated in cancer progression, but their role in triple-negative breast cancer (TNBC), a subtype of lethal and aggressive breast cancer, is unknown. Here, we reported that Spry1 is significantly expressed in TNBC specimen and MDA-MB-231 cells. To understand Spry1 regulation of signaling events controlling breast cancer phenotype, we used lentiviral delivery of human Spry1 shRNAs to suppress Spry1 expression in MDA-MB-231, an established TNBC cell line. Spry1 knockdown MDA-MB-231 cells displayed an epithelial phenotype with increased membrane E-cadherin expression. Knockdown of Spry1 impaired MDA-MB-231 cell migration, Matrigel invasion, and anchorage-dependent and -independent growth. Tumor xenografts originating from Spry1 knockdown MDA-MB-231 cells grew slower, had increased E-cadherin expression, and yielded fewer lung metastases compared to control. Furthermore, suppressing Spry1 in MDA-MB-231 cells impaired the induction of Snail and Slug expression by EGF, and this effect was associated with increased EGFR degradation and decreased EGFR/Grb2/Shp2/Gab1 signaling complex formation. The same phenotype was also observed in the TNBC cell line MDA-MB-157. Together, our results show that unlike in some tumors, where Spry may mediate tumor suppression, Spry1 plays a selective role in at least a subset of TNBC to promote the malignant phenotype via enhancing EGF-mediated mesenchymal phenotype.

Characterization of MNK1b DNA Aptamers That Inhibit Proliferation in MDA-MB231 Breast Cancer Cells

Elevated expression levels of eukaryotic initiation factor 4E (eIF4E) promote cancer development and progression. MAP kinase interacting kinases (MNKs) modulate the function of eIF4E through the phosphorylation that is necessary for oncogenic transformation. Therefore, pharmacologic MNK inhibitors may provide a nontoxic and effective anticancer strategy. MNK1b is a truncated isoform of MNK1a that is active in the absence of stimuli. Using in vitro selection, high-affinity DNA aptamers to MNK1b were selected from a library of ssDNA. Selection was monitored using the enzyme-linked oligonucleotide assay (ELONA), and the selected aptamer population was cloned and sequenced. Four groups of aptamers were identified, and the affinities of one representative for rMNK1b were determined using ELONA and quantitative polymerase chain reaction. Two aptamers, named apMNK2F and apMNK3R, had a lower Kd in the nmol/l range. The secondary structure of the selected aptamers was predicted using mFold, and the QGRS Mapper indicated the presence of potential G-quadruplex structures in both aptamers. The selected aptamers were highly specific against MNK1, showing higher affinity to MNK1b than to MNK1a. Interestingly, both aptamers were able to produce significant translation inhibition and prevent tumor cell proliferation and migration and colony formation in breast cancer cells. These results indicate that MNK1 aptamers have an attractive therapeutic potential.

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.

SPROUTY-2 represses the epithelial phenotype of colon carcinoma cells via upregulation of ZEB1 mediated by ETS1 and miR-200/miR-150

SPROUTY-2 (SPRY2) is a modulator of tyrosine kinase receptor signaling with receptor- and cell type-dependent inhibitory or enhancing effects. Studies on the action of SPRY2 in major cancers are conflicting and its role remains unclear. Here we have dissected SPRY2 action in human colon cancer. Global transcriptomic analyses show that SPRY2 downregulates genes encoding tight junction proteins such as claudin-7 and occludin and other cell-to-cell and cell-to-matrix adhesion molecules in human SW480-ADH colon carcinoma cells. Moreover, SPRY2 represses LLGL2/HUGL2, PATJ1/INADL and ST14, main regulators of the polarized epithelial phenotype, and ESRP1, an epithelial-to-mesenchymal transition (EMT) inhibitor. A key action of SPRY2 is the upregulation of the major EMT inducer ZEB1, as these effects are reversed by ZEB1 knock-down by means of RNA interference. Consistently, we found an inverse correlation between the expression level of claudin-7 and those of SPRY2 and ZEB1 in human colon tumors. Mechanistically, ZEB1 upregulation by SPRY2 results from the combined induction of ETS1 transcription factor and the repression of microRNAs (miR-200 family, miR-150) that target ZEB1 RNA. Moreover, SPRY2 increased AKT activation by epidermal growth factor, whereas AKT and also Src inhibition reduced the induction of ZEB1. Altogether, these data suggest that AKT and Src are implicated in SPRY2 action. Collectively, these results show a tumorigenic role of SPRY2 in colon cancer that is based on the dysregulation of tight junction and epithelial polarity master genes via upregulation of ZEB1. The dissection of the mechanism of action of SPRY2 in colon cancer cells is important to understand the upregulation of this gene in a subset of patients with this neoplasia that have poor prognosis.

Atypical role of sprouty in p21 dependent inhibition of cell proliferation in colorectal cancer

Sprouty (SPRY) appears to act as a tumor suppressor in cancer, whereas we reported that SPRY2 functions as a putative oncogene in colorectal cancer (CRC) [Oncogene, 2010, 29: 5241-5253]. In general, various studies established inhibition of cell proliferation by SPRY in cancer. The mechanisms by which SPRY regulates cell proliferation in CRC are investigated. We demonstrate, for the first time, suppression of SPRY2 augmented EGF-dependent oncogenic signaling, however, surprisingly decreased cell proliferation in colon cancer cells. Our data suggest that cell cycle inhibitor p21(WAF1/CIP1) transcriptional activity being regulated by SPRY2. Indeed, suppression of SPRY2 significantly increased p21(WAF1/CIP1) mRNA and protein expression as well as p21(WAF1/CIP1) promoter activity. Conversely, overexpressing SPRY2 triggered a decrease in p21(WAF1/CIP1) promoter activity. Concurrent down-regulation of both SPRY1 and SPRY2 also increased p21(WAF1/CIP1) expression in colon cancer cells. Increased nuclear localization of p21(WAF1/CIP1) in SPRY2 downregulated colon cancer cells may explain the inhibition of cell proliferation in colon cancer cells. Underscoring the biological relevance of these findings in SPRY1 and SPRY2 mutant mouse, recombination of floxed SPRY1 and SPRY2 alleles in mouse embryonic fibroblasts (MEFs) resulted in increased expression and nuclear localization of p21(WAF1/CIP1) and decreased cell proliferation. In CRC, the relationship of SPRY with p21 may provide unique strategies for cancer prevention and treatment. © 2015 The Authors. Molecular Carcinogenesis published by Wiley Periodicals, Inc.

Sprouty2 protein in prediction of post-treatment ascites in epithelial ovarian cancer treated with adjuvant carbotaxol chemotherapy

Ascites development and resistance to chemotherapy with carbotaxol are common clinical problems in epithelial ovarian cancer, partly due to the activation of MAPK/ERK signaling. Sprouty proteins are negative modulators of MAPK/ERK pathway, but their role in predicting resistance to carbotaxol chemotherapy and ascites development is unknown. In this study, we evaluated the expression of Sprouty protein isoforms by immunohistochemistry. The associations between the Sprouty expression and the clinicopathological features, including chemoresistance and the presence of ascites, were then explored. We found that the decreased expression of Spry2 was correlated with the post-treatment development of ascites and represented an independent predictor of this condition in carbotaxol-treated patients. However, no association was observed between the Sprouty expression and chemoresistance. In conclusion, our results suggest that Spry2 may be useful for patient follow-up and monitoring as it predicts the development of ascites in epithelial ovarian cancer cases treated with carbotaxol.

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 1 predicts prognosis in human epithelial ovarian cancer

Sprouty proteins are evolutionary-conserved modulators of receptor tyrosine kinase (RTK) signaling. We have previously reported inverse correlation of the Sprouty 1 (Spry1) protein expression with ovarian cancer cell proliferation, migration, invasion and survival. In the present study, the expression status of Spry1 protein and its clinical relevance in patients with epithelial ovarian cancer were explored. Matched tumor and normal tissue samples from 100 patients with epithelial ovarian cancer were immunohistochemically stained for Spry1. Expression of ERK, p-ERK, Ki67, FGF-2, VEGF and IL-6 and their correlation with Spry1 were also evaluated. In addition, correlation between Spry1 and clinicopathological characteristics and predictive significance of Spry1 for overall survival (OS) and disease-free survival (DFS) were analysed. Our data indicated that Spry1 was significantly downregulated in tumor tissues (p=0.004). Spry1 showed significant inverse correlation with p-ERK/ERK (p=0.045), Ki67 (p=0.010), disease stage (p=0.029), tumor grade (p=0.037), recurrence (p=0.001) and lymphovascular invasion (p=0.042). It was revealed that Spry1 low-expressing patients had significantly poorer OS (p=0.010) and DFS (p=0.012) than those with high expression of Spry1. Multivariate analysis showed that high Spry1 (p=0.030), low stage (p=0.048) and no residual tumor (p=0.007) were independent prognostic factors for a better OS, among which high Spry1 (p=0.035) and low stage (p=0.035) remained as independent predictors of DFS, too. We also found that the expression of Spry1 significantly correlates with the expression of Spry2 (p<0.001), but not that of Spry4. In conclusion, we report for the first time to our knowledge that Spry1 protein is downregulated in human epithelial ovarian cancer. Spry1 expression significantly impacts tumor behavior and shows predictive value as an independent prognostic factor for survival and recurrence.

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.

Sprouty2 protein is downregulated in human squamous cell carcinoma of the head and neck and suppresses cell proliferation in vitro

Sprouty2 is known for its tumor-suppressing effect in various human malignant diseases. In head and neck squamous cell carcinoma (HNSCC), the role of sprouty2 in tumorigenesis and clinical implication remains elusive. The aim of the present study was to investigate the expression of sprouty2 in patients with HNSCC and its function in vitro. Quantitative analysis of mRNA expression of sprouty2 was performed on frozen tumor samples from 42 patients with HNSCC and 19 with oral verrucous hyperplasia (OVH) with paired counterparts of normal mucosa. Downregulation of sprouty2 expression was demonstrated in 79% of HNSCC samples and in 58% of OVH samples compared with paired samples of normal mucosa. Enhanced expression of sprouty2 protein suppressed the growth of HNSCC cells and signaling of the phosphorylated AKT pathway. Following transfection of the sprouty2 plasmid, HNSCC cells were more sensitive to sorafenib, a tyrosine kinase inhibitor of Raf and vascular endothelial growth factor receptor. The present study suggested that sprouty2 expression was downregulated and behaved as a tumor suppressor in HNSCC. Sprouty2 expression in tumor cells enhanced sensitivity to sorafenib. Further studies are required to define the clinical impact of sprouty2 in patients with HNSCC.

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.

Modulation of fibroblast growth factor signaling is essential for mammary epithelial morphogenesis

Fibroblast growth factor (FGF) signaling is essential for vertebrate organogenesis, including mammary gland development. The mechanism whereby FGF signaling is regulated in the mammary gland, however, has remained unknown. Using a combination of mouse genetics and 3D ex vivo models, we tested the hypothesis that Spry2 gene, which encodes an inhibitor of signaling via receptor tyrosine kinases (RTKs) in certain contexts, regulates FGF signaling during mammary branching. We found that Spry2 is expressed at various stages of the developing mammary gland. Targeted removal of Spry2 function from mammary epithelium leads to accelerated epithelial invasion. Spry2 is up-regulated by FGF signaling activities and its loss sensitizes mammary epithelium to FGF stimulation, as indicated by increased expression of FGF target genes and epithelia invasion. By contrast, Spry2 gain-of-function in the mammary epithelium results in reduced FGF signaling, epithelial invasion, and stunted branching. Furthermore, reduction of Spry2 expression is correlated with tumor progression in the MMTV-PyMT mouse model. Together, the data show that FGF signaling modulation by Spry2 is essential for epithelial morphogenesis in the mammary gland and it functions to protect the epithelium against tumorigenesis.

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.

Research on drug resistance mechanism of trastuzumab caused by activation of the PI3K/Akt signaling pathway

Aim of the study

To discuss the activation of the signal transduction pathway of phosphatidylinositol 3’-kinase/serine-threonine kinase (PI3K/Akt), one of the important targets of drug resistance of trastuzumab, which provides a theoretical basis for the targeted therapy of drug resistance of trastuzumab in breast cancer.

Material and methods

Establish the drug-resistance sub-strain BT-HerR of trastuzumab for the continuous treatment of human breast cancer cell strain BT474, conduct Her-2 phenotype analysis on the drug-resistance cell strain BT-HerR with the FISH method, detect the proliferation inhibition in vitro of trastuzumab to BT474 and BT-HerR cells with the MTT method, detect the apoptosis variation after interference of trastuzumab with a flow cytometer and detect p-Akt and apoptosis-related protein expression with Western blot after PI3K/Akt inhibitor LY294002 interferes with the cells.

Results

The gene expression of drug-resistance cell strain BT-HerR Her-2 is strongly positive; 72 hours after interference of trastuzumab, the proliferation in vitro of the BT474 and BT-HerR cells is inhibited, which is strengthened with the increase of concentration, showing a significant difference (p < 0.01); after treatment of trastuzumab, comparison of the cell apoptosis rate of BT474 and BT-HerR shows a significant difference (p < 0.01); trastuzumab can only inhibit the Akt protein phosphorylation of BT474, while LY294002 can inhibit the BT-HerR and BT474 Akt protein phosphorylation simultaneously.

Conclusions

Akt protein phosphorylation of trastuzumab drug-resistance cells is activated; LY294002, a PI3K/Akt inhibitor, can obviously inhibit Akt protein phosphorylation of trastuzumab drug-resistance cells and there is a clear association between the PI3K/Akt signal transduction pathway and trastuzumab resistance.

Expression and functional role of sprouty-2 in breast morphogenesis

Branching morphogenesis is a mechanism used by many species for organogenesis and tissue maintenance. Receptor tyrosine kinases (RTKs), including epidermal growth factor receptor (EGFR) and the sprouty protein family are believed to be critical regulators of branching morphogenesis. The aim of this study was to analyze the expression of Sprouty-2 (SPRY2) in the mammary gland and study its role in branching morphogenesis. Human breast epithelial cells, breast tissue and mouse mammary glands were used for expression studies using immunoblotting, real rime PCR and immunohistochemistry. Knockdown of SPRY2 in the breast epithelial stem cell line D492 was done by lentiviral transduction of shRNA constructs targeting SPRY2. Three dimensional culture of D492 with or without endothelial cells was done in reconstituted basement membrane matrix. We show that in the human breast, SPRY2 is predominantly expressed in the luminal epithelial cells of both ducts and lobuli. In the mouse mammary gland, SPRY2 expression is low or absent in the virgin state, while in the pregnant mammary gland SPRY2 is expressed at branching epithelial buds with increased expression during lactation. This expression pattern is closely associated with the activation of the EGFR pathway. Using D492 which generates branching structures in three-dimensional (3D) culture, we show that SPRY2 expression is low during initiation of branching with subsequent increase throughout the branching process. Immunostaining locates expression of phosphorylated SPRY2 and EGFR at the tip of lobular-like, branching ends. SPRY2 knockdown (KD) resulted in increased migration, increased pERK and larger and more complex branching structures indicating a loss of negative feedback control during branching morphogenesis. In D492 co-cultures with endothelial cells, D492 SPRY2 KD generates spindle-like colonies that bear hallmarks of epithelial to mesenchymal transition. These data indicate that SPRY2 is an important regulator of branching morphogenesis and epithelial to mesenchymal transition in the mammary gland.

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.

SPRY2 loss enhances ErbB trafficking and PI3K/AKT signalling to drive human and mouse prostate carcinogenesis

Loss of SPRY2 and activation of receptor tyrosine kinases are common events in prostate cancer (PC). However, the molecular basis of their interaction and clinical impact remains to be fully examined. SPRY2 loss may functionally synergize with aberrant cellular signalling to drive PC and to promote treatment-resistant disease. Here, we report evidence for a positive feedback regulation of the ErbB-PI3K/AKT cascade by SPRY2 loss in in vitro as well as pre-clinical in vivo models and clinical PC. Reduction in SPRY2 expression resulted in hyper-activation of PI3K/AKT signalling to drive proliferation and invasion by enhanced internalization of EGFR/HER2 and their sustained signalling at the early endosome in a PTEN-dependent manner. This involved p38 MAPK activation by PI3K to facilitate clathrin-mediated ErbB receptor endocytosis. Finally, in vitro and in vivo inhibition of PI3K suppressed proliferation and invasion, supporting PI3K/AKT as a target for therapy particularly in patients with PTEN-haploinsufficient-, low SPRY2- and ErbB-expressing tumours. In conclusion, SPRY2 is an important tumour suppressor in PC since its loss drives the PI3K/AKT pathway via functional interaction with the ErbB system.