BMP-6 inhibits MMP-9 expression by regulating heme oxygenase-1 in MCF-7 breast cancer cells

Gibberellin derivative GA-13315 overcomes multidrug resistance in breast cancer by up-regulating BMP6 expression

Chemoresistance represents a major obstacle in breast cancer treatment. Bone morphogenetic protein 6 (BMP6) was reported to participate in the occurrence and development of various tumors. In the present study, the results of transcriptome sequencing, qRT-PCR and western blot analysis revealed that BMP6 was down-regulated in multidrug resistant MCF-7/Adr breast cancer cells and BMP6 overexpression sensitized MCF-7/Adr cells to chemotherapeutic drugs, indicating that BMP6 downregulation was involved in the mechanisms of multidrug resistance (MDR) of MCF-7/Adr breast cancer cells. GA-13315 (GA5) is a new tetracyclic diterpenoid selected from a series of gibberellin derivatives. Here, we found that GA5 exhibited more potent anti-tumor activity in multidrug resistant MCF-7/Adr breast cancer cells and xenografts, indicating that GA5 could overcome MDR. Mechanistically, GA5 increased BMP6 expression, and BPM6 knockdown partially reversed the inhibitory effect of GA5 on cell proliferation. Furthermore, we found that ERK phosphorylation and P-gp expression were increased in MCF-7/Adr cells when compared with MCF-7 cells. Either overexpression of BMP6 or treatment the cells with GA5 significantly decreased ERK phosphorylation and P-gp expression, indicating that GA5 reversed MDR of MCF-7/Adr cells by upregulating BMP6, thereby inhibiting the activation of ERK signaling pathway and reducing P-gp expression. Collectively, our present study demonstrated that the MDR of MCF-7/Adr cells was closely related to the low expression of BMP6, and revealed the molecular mechanisms by which GA5 overcame MDR in breast cancer, providing evidence in supporting the development of GA5 to be a promising agent for overcoming MDR in clinical cancer therapy in the future.

Bone morphogenic protein-2 signaling in human disc degeneration and correlation to the Pfirrmann MRI grading system

BACKGROUND CONTEXT

Back and neck pain secondary to disc degeneration is a major public health burden. There is a need for therapeutic treatments to restore intervertebral disc (IVD) composition and function.

PURPOSE

To quantify ALK3, BMP-2, pSMAD1/5/8 and MMP-13 expression in IVD specimens collected from patients undergoing surgery for disc degeneration, to correlate ALK3, BMP-2, pSMAD1/5/8 and MMP-13 expression in IVD specimens to the 5-level Pfirrmann MRI grading system, and to compare ALK3, BMP-2, pSMAD1/5/8 and MMP-13 expression between cervical and lumbar degenerative disc specimens.

STUDY DESIGN

An immunohistochemical study assessing ALK3, BMP-2, pSMAD1/5/8, and MMP-13 expression levels in human control and degenerative IVD specimens.

METHODS

Human IVD specimens were collected from surgical patients who underwent discectomy and interbody fusion at our institution between 1/2015 and 8/2017. Each patient underwent MRI prior to surgery. The degree of disc degeneration was measured according to the 5-level Pfirrmann MRI grading system. Patients were categorized into either the 1) control group (Pfirrmann grades I-II) or 2) degenerative group (Pfirrmann grades III-V). Histology slides of the collected IVD specimens were prepared and immunohistochemical staining was performed to assess ALK3, BMP-2, pSMAD1/5/8, and MMP-13 expression levels in the control and degenerative specimens. Expression levels were also correlated to the Pfirrmann criteria. Lastly, the degenerative specimens were stratified according to their vertebral level and expression levels between the degenerative lumbar and cervical discs were compared.

RESULTS

Fifty-two patients were enrolled; however, 2 control and 2 degenerative patients were excluded due to incomplete data sets. Of the remaining 48 patients, there were 12 control and 36 degenerative specimens. Degenerative specimens had increased expression levels of BMP-2 (p=.0006) and pSMAD1/5/8 (p<.0001). Pfirrmann grade 3 (p=.0365) and grade 4 (p=.0008) discs had significantly higher BMP-2 expression as compared to grade 2 discs. Pfirrmann grade 4 discs had higher pSMAD1/5/8 expression as compared to grade 2 discs (p<.0001). There were no differences in ALK3 or MMP-13 expression between the control and degenerative discs (p>.05). Stratifying the degenerative specimens according to their vertebral level showed no significant differences in expression levels between the lumbar and cervical discs (p>.05).

CONCLUSIONS

BMP-2 and pSMAD1/5/8 signaling activity was significantly upregulated in the human degenerative specimens, while ALK3 and MMP-13 expression were not significantly changed. The expression levels of BMP-2 and pSMAD1/5/8 correlate positively with the degree of disc degeneration measured according to the Pfirrmann MRI grading system.

CLINICAL SIGNIFICANCE

BMP-SMAD signaling represents a promising therapeutic target to restore IVD composition and function in the setting of disc degeneration.

Molecular mechanisms and clinical management of cancer bone metastasis

As one of the most common metastatic sites of malignancies, bone has a unique microenvironment that allows metastatic tumor cells to grow and flourish. The fenestrated capillaries in the bone, bone matrix, and bone cells, including osteoblasts and osteoclasts, together maintain the homeostasis of the bone microenvironment. In contrast, tumor-derived factors act on bone components, leading to subsequent bone resorption or excessive bone formation. The various pathways involved also provide multiple targets for therapeutic strategies against bone metastases. In this review, we summarize the current understanding of the mechanism of bone metastases. Based on the general process of bone metastases, we specifically highlight the complex crosstalk between tumor cells and the bone microenvironment and the current management of cancer bone metastases.

Heme Oxygenase-1 Has an Antitumor Role in Breast Cancer

Aims: Heme oxygenase-1 (HO-1) is an enzyme involved in cellular responses to oxidative stress and has also been shown to regulate processes related to cancer progression. In this regard, HO-1 has been shown to display a dual effect with either antitumor or protumor activity, which is also true for breast cancer (BC). In this work, we address this discrepancy regarding the role of HO-1 in BC. Results: HO-1 was detected in human BC tissues, and its protein levels correlated with reduced tumor size and longer overall survival time of patients, thus suggesting the clinical importance of HO-1 in this type of cancer. Contrariwise, nuclear localization of HO-1 correlated with higher tumor grade suggesting that the effect of HO-1 is dependent on its cellular localization. In vivo experiments showed that both pharmacological activation and genetic overexpression of HO-1 reduce the tumor burden in two different animal models of BC. Furthermore, the pharmacological and genetic activation of HO-1 in several BC cell lines reduce the cellular viability by inducing apoptosis and cell cycle arrest and decrease the cellular migration and invasion rates by modulating pathways involved in the epithelial-mesenchymal transition. Furthermore, HO-1 activation impaired in vivo the metastatic dissemination. Innovation and Conclusion: By using various BC cell lines and animal models as well as human tumor samples, we demonstrated that total HO-1 displays antitumor activities in BC. Furthermore, our study suggests that HO-1 subcellular localization may explain the differential effects observed for the protein in different tumor types.

Bone morphogenetic protein signaling in breast cancer progression

Breast cancer is the most prevalent type of cancer amongst women worldwide. The mortality rate for patients with early-stage breast cancer has been decreasing, however, the 5-year survival rate for patients with metastatic disease remains poor, currently at 27%. Here, we have reviewed the current understanding of the role of bone morphogenetic protein (BMP) signaling in breast cancer progression, and have highlighted the discordant results that are reported in different studies. We propose that some of these contradictory outcomes may result from signaling through either the canonical or non-canonical pathways in different cell lines and tumors, or from different tumor-stromal interactions that occur in vivo.

Identifying chondroprotective diet-derived bioactives and investigating their synergism

Osteoarthritis (OA) is a multifactorial disease and nutrition is a modifiable factor that may contribute to disease onset or progression. A detailed understanding of mechanisms through which diet-derived bioactive molecules function and interact in OA is needed. We profiled 96 diet-derived, mainly plant-based bioactives using an in vitro model in chondrocytes, selecting four candidates for further study. We aimed to determine synergistic interactions between bioactives that affected the expression of key genes in OA. Selected bioactives, sulforaphane, apigenin, isoliquiritigenin and luteolin, inhibited one or more interleukin-1-induced metalloproteinases implicated in OA (MMP1, MMP13, ADAMTS4, ADAMTS5). Isoliquiritigenin and luteolin showed reactive oxygen species scavenging activity in chondrocytes whereas sulforaphane had no effect and apigenin showed only a weak trend. Sulforaphane inhibited the IL-1/NFκB and Wnt3a/TCF/Lef pathways and increased TGFβ/Smad2/3 and BMP6/Smad1/5/8 signalling. Apigenin showed potent inhibition of the IL-1/NFκB and TGFβ/Smad2/3 pathways, whereas luteolin showed only weak inhibition of the IL-1/NFκB pathway. All four bioactives inhibited cytokine-induced aggrecan loss from cartilage tissue explants. The combination of sulforaphane and isoliquiritigenin was synergistic for inhibiting MMP13 gene expression in chondrocytes. We conclude that dietary-derived bioactives may be important modulators of cartilage homeostasis and synergistic relationships between bioactives may have an anti-inflammatory and chondroprotective role.

Prognostic significance of bone morphogenetic protein 6 (BMP6) expression, clinical and pathological factors in clinically node-negative oral squamous cell carcinoma (OSCC)

Bone morphogenetic protein 6 (BMP6) has unique properties regarding structure and function in supporting bone formation during development and adult life. Despite its known role in various malignant tumors, the prognostic significance of BMP6 expression in oral squamous cell carcinoma (OSCC) remains unknown. The aim of the study was to investigate immunohistochemical expression of BMP6 in OSCC in correlation with clinical and pathological parameters, disease recurrence and survival. In addition, we investigated other parameters in order to identify prognosticators of neck metastases and final outcome. The study included 120 patients with clinically T1-3N0 OSCC who were primarily surgically treated between 2003 and 2008. There were 99 (82.5%) male and 21 (17.5%) female patients. The five-year disease-specific survival for the whole cohort was 79.7%. Tumors smaller than 2 cm in diameter showed higher incidence of strong BMP6 expression. No statistical correlation was observed between other clinico-pathological factors and BMP6 expression. Expression of BMP6 was not associated with disease recurrence and survival. BMP6 may not serve as prognosticator of final outcome or recurrence in clinically node-negative OSCC subjects. In multivariate analysis predictors of poorer survival were positive surgical margin, moderate tumor cell differentiation and pathological involvement of levels IV and/or V.

The Association of Matrix Metalloproteinase-1 Promoter Polymorphisms with Breast Cancer

BACKGROUND/AIM

The family of matrix metalloproteinases (MMPs) are responsible for the homeostasis of extracellular matrix components and their genetic polymorphisms may be associated with cancer susceptibility. The serum levels of MMP-1 have been reported to be lower in breast cancer patients than healthy subjects. In the current study, we aimed at investigating the contribution of a polymorphism in the promoter region of MMP-1 to breast cancer in Taiwan.

MATERIALS AND METHODS

The MMP-1 rs1799705 polymorphic genotypes were genotyped among 1,232 breast cancer patients and 1,232 healthy controls by the typical polymerase chain reaction-restriction fragment length polymorphism methodology.

RESULTS

The percentages of 2G/2G, 1G/2G, and 1G/1G for MMP1 -1607 genotypes were 35.4, 40.6 and 24.0% in the breast cancer group and 34.1, 43.6, and 22.3% in the healthy control group (p trend=0.3025), respectively. The odds ratios (ORs) after adjusting for age, smoking and alcohol drinking status for those carrying 1G/2G and 1G/1G genotypes at MMP1 -1607 were 0.93 (95%CI=0.76-1.11, p=0.2390) and 1.01 (95%CI=0.77-1.23, p=0.7377), respectively, compared to those carrying the wild-type 2G/2G genotype. Supporting this finding, the adjusted OR for those carrying the 1G allele at MMP-1 -1607 was 1.03 (95%CI=0.91-1.18, p=0.8860), compared to those carrying the wild-type 2G allele. Our findings suggest that the polymorphic genotypes at MMP1 promoter -1607 investigated in the current study, may not play a major role in determining cancer susceptibility to breast cancer in Taiwan. Other early diagnostic and predictive markers are urgently needed for personalized and precise breast cancer detection and therapy.

Overexpression of colorectal cancer oncogene CHRDL2 predicts a poor prognosis

Bone morphogenetic proteins (BMPs) both promote and suppress tumorigenesis, and multiple BMP antagonists reportedly contribute to cancer progression. In this study, we demonstrated that the BMP antagonist Chordin-like 2 (CHRDL2) is upregulated in colorectal cancer (CRC) tissues, and that CHRDL2 levels correlate with clinical features of CRC patients, including tumor size, TNM staging, and tumor differentiation. In addition, survival rate and Cox proportional hazards model analyses showed that high CHRDL2 levels correlate with a poor prognosis in CRC. Moreover, CHRDL2 promoted CRC cell proliferation in vitro and in vivo, perhaps through up-regulation of Cyclin D1 and down-regulation of P21. Co-immunoprecipitation assays showed that CHRDL2 bound to BMPs, which inhibited p-Smad1/5, thereby promoting CRC cell proliferation and inhibiting apoptosis. These results suggest CHRDL2 could serve as a biomarker of poor prognosis in CRC, and provide evidence that CHRDL2 acts as an oncogene in human CRC, making it a novel potential therapeutic target.

BMP-6 inhibits the metastasis of MDA-MB-231 breast cancer cells by regulating MMP-1 expression

Bone morphogenetic protein-6 (BMP-6) is a multifunctional molecule with distinct abilities in embryogenesis and organogenesis. In the present study, our results showed that the rate of BMP-6-negative expression was 30.56% in breast cancer tissues, but was 9.58% in normal tissues by immunohistochemical staining. This implied that BMP-6 expression is absent in breast cancer tissues and may suppress breast cancer metastasis. In addition, stable overexpression of BMP-6 in MDA-MB‑231 cells was established to analyze the metastatic ability. The Boyden chamber assay showed that BMP-6 inhibited the migration and invasion of MDA-MB-231 cells. Moreover, real-time PCR analysis showed that BMP-6 markedly downregulated matrix metalloproteinase-1 (MMP-1) expression at both the mRNA and protein levels in the MDA-MB‑231 cells. Importantly, the results of luciferase and CHIP assays revealed that BMP-6 inhibited MMP-1 promoter activity through the AP-1 response element. In MDA-MB-231 cells treated with BMP-6, a significant decrease in the recruitment of AP-1 components, c-Jun/c-Fos, to the endogenous MMP-1 promoter was noted. We also demonstrated that BMP-6 inhibited the invasion of MDA-MB-231 cells, and this effect was significantly attenuated by overexpression of MMP-1. In contrast, MMP-1 knockdown by RNA interference or MMP-1 inhibitor exhibited an opposite effect. These observations suggest a novel role of BMP-6 in the inhibition of breast cancer metastasis by regulating secretion of MMPs in the tumor microenvironment.

The integrative epigenomic-transcriptomic landscape of ER positive breast cancer

Background

While recent integrative analyses of copy number and gene expression data in breast cancer have revealed a complex molecular landscape with multiple subtypes and many oncogenic/tumour suppressor driver events, much less is known about the role of DNA methylation in shaping breast cancer taxonomy and defining driver events.

Results

Here, we applied a powerful integrative network algorithm to matched DNA methylation and RNA-Seq data for 724 estrogen receptor (ER)-positive (ER+) breast cancers and 111 normal adjacent tissue specimens from The Cancer Genome Atlas (TCGA) project, in order to identify putative epigenetic driver events and to explore the resulting molecular taxonomy. This revealed the existence of nine functionally deregulated epigenetic hotspots encompassing a total of 146 genes, which we were able to validate in independent data sets encompassing over 1000 ER+ breast cancers. Integrative clustering of the matched messenger RNA (mRNA) and DNA methylation data over these genes resulted in only two clusters, which correlated very strongly with the luminal-A and luminal B subtypes. Overall, luminal-A and luminal-B breast cancers shared the same epigenetically deregulated hotspots but with luminal-B cancers exhibiting increased aberrant DNA methylation patterns relative to normal tissue. We show that increased levels of DNA methylation and mRNA expression deviation from the normal state define a marker of poor prognosis. Our data further implicates epigenetic silencing of WNT signalling antagonists and bone morphogenetic proteins (BMP) as key events underlying both luminal subtypes but specially of luminal-B breast cancer. Finally, we show that DNA methylation changes within the identified epigenetic interactome hotspots do not exhibit mutually exclusive patterns within the same cancer sample, instead exhibiting coordinated changes within the sample.

Conclusions

Our results indicate that the integrative DNA methylation and transcriptomic landscape of ER+ breast cancer is surprisingly homogeneous, defining two main subtypes which strongly correlate with luminal-A/B subtype status. In particular, we identify WNT and BMP signalling as key epigenetically deregulated tumour suppressor pathways in luminal ER+ breast cancer, with increased deregulation seen in luminal-B breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0159-0) contains supplementary material, which is available to authorized users.

Nrf2-heme oxygenase-1 axis in mucoepidermoid carcinoma of the lung: Antitumoral effects associated with down-regulation of matrix metalloproteinases

Lung mucoepidermoid carcinoma (MEC) is a very poorly characterized rare subtype of non-small-cell lung cancer (NSCLC) associated with more favorable prognoses than other forms of intrathoracic malignancies. We have previously identified that heme oxygenase-1 (HO-1, encoded by HMOX1) inhibits MEC tumor growth and modulates the transcriptome of microRNAs. Here we investigate the role of a major upstream regulator of HO-1 and a master regulator of cellular antioxidant responses, transcription factor Nrf2, in MEC biology. Nrf2 overexpression in the NCI-H292 MEC cell line mimicked the phenotype of HO-1 overexpressing cells, leading to inhibition of cell proliferation and migration and down-regulation of oncogenic miR-378. HMOX1 silencing identified HO-1 as a major mediator of Nrf2 action. Nrf2- and HO-1 overexpressing cells exhibited strongly diminished expression of multiple matrix metalloproteinases and inflammatory cytokine interleukin-1β, which was confirmed in an NCI-HO-1 xenograft model. Overexpression of HO-1 altered not only human MMP levels in tumor cells but also murine MMP levels within tumor microenvironment and metastatic niche. This could possibly contribute to decreased metastasis to the lungs and inhibitory effects of HO-1 on MEC tumor growth. Our profound transcriptome analysis and molecular characterization of the mucoepidermoid lung carcinoma helps to understand the specific clinical presentations of these tumors, emphasizing a unique antitumoral role of the Nrf2-HO-1 axis.

Bone morphogenetic protein 4 (BMP-4) and epidermal growth factor (EGF) inhibit metalloproteinase-9 (MMP-9) expression in cancer cells

Matrix metalloproteinase-9 (MMP-9) plays a central role in the progression of the cancer. While a large number of studies have contributed to our understanding of the molecular mechanisms responsible for upregulating MMP-9 gene expression in normal and cancer cells, our knowledge on the signals that suppress MMP-9 expression is much more limited. Here, we report that EGF and BMP-4 cooperate to inhibit MMP-9 expression in cancer cells. Treatment with EGF reduces the expression of MMP-9 at both mRNA while augmenting BMP-4 expression. Interestingly, recombinant BMP-4 suppressed constitutive and PMA-induced MMP-9 expression in both fibrosarcoma and breast cancer cells. Addition of gremlin a natural inhibitor of BMP-4, inhibited the suppression of MMP-9 by EGF. The suppression of MMP-9 by BMP-4 likely occurs at the transcriptional level since BMP-4 suppressed MMP-9 mRNA expression and activation of a reporter vector encoding the human MMP-9 promoter. The suppressive effect of BMP-4 occurs via Smad1/5/8 and is specific since BMP-4 did not inhibit MMP-2 while BMP-2 was ineffective in suppressing MMP-9. Taken together, these results are consistent with a new paradigm for the role of EGF and BMPs in controlling MMP gene expression in cancer cells.

Quercetin prevents ethanol-induced iron overload by regulating hepcidin through the BMP6/SMAD4 signaling pathway

Emerging evidence has demonstrated that chronic ethanol exposure induces iron overload, enhancing ethanol-mediated liver damage. The purpose of this study was to explore the effects of the naturally occurring compound quercetin on ethanol-induced iron overload and liver damage, focusing on the signaling pathway of the iron regulatory hormone hepcidin. Adult male C57BL/6J mice were pair-fed with isocaloric-Lieber De Carli diets containing ethanol (accounting for 30% of total calories) and/or carbonyl iron (0.2%) and treated with quecertin (100 mg/kg body weight) for 15 weeks. Mouse primary hepatocytes were incubated with ethanol (100 mM) and quercetin (100 μM) for 24 h. Mice exposed to either ethanol or iron presented significant fatty infiltration and iron deposition in the liver; these symptoms were exacerbated in mice cotreated with ethanol and iron. Quercetin attenuated the abnormity induced by ethanol and/or iron. Ethanol suppressed BMP6 and intranuclear SMAD4 as well as decreased hepcidin expression. These effects were partially alleviated by quercetin supplementation in mice and hepatocytes. Importantly, ethanol caused suppression of SMAD4 binding to the HAMP promoter and of hepcidin messenger RNA expression. These effects were exacerbated by anti-BMP6 antibody and partially alleviated by quercetin or human recombinant BMP6 in cultured hepatocytes. In contrast, co-treatment with iron and ethanol, especially exposure of iron alone, activated BMP6/SMAD4 pathway and up-regulated hepcidin expression, which was also normalized by quercetin in vivo. Quercetin prevented ethanol-induced hepatic iron overload different from what carbonyl iron diet elicited in the mechanism, by regulating hepcidin expression via the BMP6/SMAD4 signaling pathway.

BMP-6 inhibits cell proliferation by targeting microRNA-192 in breast cancer

Although bone morphogenetic protein-6 (BMP-6) has been identified as a tumor suppressor associated with breast cancer differentiation and metastasis, the potential roles of BMP-6 in regulating cell cycle progression have not been fully examined. In the present study, we provide the novel finding that induction of BMP-6 in MDA-MB-231 breast cancer cells significantly inhibits cell proliferation by decreasing the number of cells in S phase of the cell cycle, resulting in inhibition of tumorigenesis in a nude mouse xenograft model. Further investigation indicated that BMP-6 up-regulates the expression of microRNA-192 (miR-192) in MDA-MB-231 cells. Elevated expression of miR-192 caused cell growth arrest, which is similar to the effect of BMP-6 induction. Importantly, depletion of endogenous miR-192 by miRNA inhibition significantly attenuated BMP-6-mediated repression of cell cycle progression. In breast cancer tissue, miR-192 expression is significantly down-regulated in tumor samples and positively correlates with the expression of BMP-6, demonstrating the inhibitory effect of BMP-6 on cell proliferation through miR-192 regulation. Additionally, using the RT(2) Profiler PCR Array, retinoblastoma 1 (RB1) was identified as a direct target of the BMP-6/miR-192 pathway in regulating cell proliferation in breast cancer. In conclusion, we have identified an important role for BMP-6/miR-192 signaling in the regulation of cell cycle progression in breast cancer. Furthermore, BMP-6/miR-192 was expressed at low levels in breast cancer specimens, indicating that this pathway might represent a promising therapeutic target for breast cancer treatment.

Inhibition of matrix metalloproteinase-9 expression by docosahexaenoic acid mediated by heme oxygenase 1 in 12-O-tetradecanoylphorbol-13-acetate-induced MCF-7 human breast cancer cells

Matrix metalloproteinase-9 (MMP-9) plays a crucial role in tumor metastasis. Previous studies showed that polyunsaturated fatty acids exhibit an anti-cancer effect in various human carcinoma cells, but the effect of docosahexaenoic acid (DHA) and linoleic acid (LA) on metastasis of breast cancer cells is not fully clarified. We studied the anti-metastasis potential of DHA and LA in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MCF-7 cells. We found that TPA (100 ng/ml) induced MMP-9 enzyme activity both dose- and time-dependently, and 200 μM DHA and LA significantly inhibited MMP-9 mRNA and protein expression, enzyme activity, cell migration, and invasion. Treatment with PD98059 (10 μM), wortmannin (10 μM), and GF109203X (0.5 μM) decreased TPA-induced MMP-9 protein expression and enzyme activity. TPA-induced activation of ERK1, Akt, and PKCδ was attenuated by DHA, whereas LA attenuated only ERK1 activation. GF109203X also suppressed ERK1 activation. EMSA showed that DHA, LA, PD98059, and wortmannin decreased TPA-induced NF-κB and AP-1 DNA-binding activity. Furthermore, DHA rather than LA dose-dependently increased HO-1 expression. HO-1 siRNA alleviated the inhibition by DHA of TPA-induced MMP-9 protein expression and enzyme activity in MCF-7 cells, and HO-1 knockdown reversed the DHA inhibition of cell migration. These results suggest that DHA and LA have both similar and divergent signaling pathways in the suppression of TPA-induced MCF-7 metastasis.

Osteopontin increases heme oxygenase-1 expression and subsequently induces cell migration and invasion in glioma cells

Malignant gliomas are associated with high morbidity and mortality because they are highly invasive into surrounding brain tissue, making complete surgical resection impossible. Osteopontin is abundantly expressed in the brain and is involved in cell adhesion, migration, and invasion. The aim of the present study was to investigate the mechanisms of glioma cell migration. Migration and invasion activity were determined by transwell and wound-healing assays. Gene and protein expressions were analyzed by reverse transcription-PCR, real time-PCR, and Western blotting. Nrf2-DNA binding activity was determined by electrophoretic mobility shift assay. Establishment of migration-prone sublines were performed to select highly migratory glioma. An intracranial xenograft mouse model was used for the in vivo study. Application of recombinant human osteopontin enhanced the migration of glioma cells. Expression of heme oxygenase (HO)-1 mRNA and protein also increased in response to osteopontin stimulation. Osteopontin-induced increase in cell migration was antagonized by HO-1 inhibitor or HO-1 small interfering (si)RNA. Osteopontin-mediated HO-1 expression was reduced by treatment with MEK/ERK and phosphatidylinositol 3-kinase/Akt inhibitors, as well as siRNA against Nrf2. Furthermore, osteopontin stimulated Nrf2 accumulation in the nucleus and increased Nrf2-DNA binding activity. In migration-prone sublines, cells with greater migration ability had higher osteopontin and HO-1 expression, and zinc protoporphyrin IX treatment could effectively reduce the enhanced migration ability. In an intracranial xenograft mouse model, transplantation of migration-prone subline cells exhibited higher cell migration than parental tumor cells. These results indicate that osteopontin activates Nrf2 signaling, resulting in enhanced HO-1 expression and cell migration in glioma cells.

Cancer module genes ranking using kernelized score functions

Background

Co-expression based Cancer Modules (CMs) are sets of genes that act in concert to carry out specific functions in different cancer types, and are constructed by exploiting gene expression profiles related to specific clinical conditions or expression signatures associated to specific processes altered in cancer. Unfortunately, genes involved in cancer are not always detectable using only expression signatures or co-expressed sets of genes, and in principle other types of functional interactions should be exploited to obtain a comprehensive picture of the molecular mechanisms underlying the onset and progression of cancer.

Results

We propose a novel semi-supervised method to rank genes with respect to CMs using networks constructed from different sources of functional information, not limited to gene expression data. It exploits on the one hand local learning strategies through score functions that extend the guilt-by-association approach, and on the other hand global learning strategies through graph kernels embedded in the score functions, able to take into account the overall topology of the network. The proposed kernelized score functions compare favorably with other state-of-the-art semi-supervised machine learning methods for gene ranking in biological networks and scales well with the number of genes, thus allowing fast processing of very large gene networks.

Conclusions

The modular nature of kernelized score functions provides an algorithmic scheme from which different gene ranking algorithms can be derived, and the results show that using integrated functional networks we can successfully predict CMs defined mainly through expression signatures obtained from gene expression data profiling. A preliminary analysis of top ranked "false positive" genes shows that our approach could be in perspective applied to discover novel genes involved in the onset and progression of tumors related to specific CMs.

Regulation of DCIS to invasive breast cancer progression by Singleminded-2s (SIM2s)

Singleminded-2s (SIM2s) is a member of the bHLH/PAS family of transcription factors and a key regulator of mammary epithelial cell differentiation. SIM2s is highly expressed in mammary epithelial cells and down regulated in human breast cancer. Loss of Sim2s causes aberrant mouse mammary ductal development with features suggestive of malignant transformation, whereas over-expression of SIM2s promotes precocious alveolar differentiation in nulliparous mouse mammary glands, suggesting that SIM2s is required for establishing and enhancing mammary gland differentiation. To test the hypothesis that SIM2s regulates tumor cell differentiation, we analyzed SIM2s expression in human primary breast ductal carcinoma in situ (DCIS) samples and found that SIM2s is lost with progression from DCIS to invasive ductal cancer (IDC). Utilizing a MCF10DCIS.COM progression model, we have shown that SIM2s expression is decreased in MCF10DCIS.COM cells compared to MCF10A cells and reestablishment of SIM2s in MCF10DCIS.COM cells significantly inhibits growth and invasion in vitro and in vivo. Analysis of SIM2s-MCF10DCIS.com tumors showed that SIM2s promoted a more differentiated tumor phenotype including the expression of a broad range of luminal markers (CSN2 (β-casein), CDH1 (E-cadherin), and KER18 (keratin-18)) and suppressed genes associated with stem cell maintenance and a basal phenotype (SMO (smoothened), p63, SLUG (snail-2), KER14 (keratin-14) and VIM (vimentin)). Furthermore, loss of SIM2s expression in MCF10DCIS.COM xenografts resulted in a more invasive phenotype and increased lung metastasis likely due to an increase in hedgehog signaling and matrix metalloproteinase expression. Together, these exciting new data support a role for SIM2s in promoting human breast tumor differentiation and maintaining epithelial integrity.

Curcumin-induced heme oxygenase-1 expression plays a negative role for its anti-cancer effect in bladder cancers

Some phytochemicals with the characteristics of cytotoxicity and anti-metastasis has generated intense interest among the invasive cancer study. Curcumin, one of these anti-cancer phytochemicals, has been reported to induce the cytoprotective enzyme heme oxygenase-1 expression. Since heme oxygenase-1 has been suggested to enhance cancer cell invasion, we investigated the anti-invasive effect of curcumin when heme oxygenase-1 was knocked down in vitro, and the heme oxygenase-1 expression after curcumin treatment in vivo. Curcumin inhibited cell viability and the MMP-2/9 activities of human bladder cancer cells. At 10 μM, curcumin inhibited cell viability and cell invasive activity by 15% and 40%, respectively. Ten micrometer curcumin increased the intracellular reactive oxygen species concentration and heme oxygenase-1 protein and mRNA expression in bladder cancer cells. The anti-invasive activity of curcumin was elevated when heme oxygenase-1 was knocked down by siRNA or inhibited by pharmacological inhibitor. In vivo, curcumin induced heme oxygenase-1 protein expression in the lung tissue of murine lung metastasis tumor model and in the bladder tissue of murine orthotopic bladder tumor model. Taken together, our data suggest that curcumin-induced heme oxygenase-1 attenuates the anti-invasive effect of curcumin in cancer therapy, and co-treatment by heme oxygenase-1 inhibitor enhances the anti-invasive activity of curcumin.