Bone morphogenetic protein 7 induces mesenchymal-to-epithelial transition in melanoma cells, leading to inhibition of metastasis

Shaping Oncogenic Microenvironments: Contribution of Fibronectin

The extracellular matrix (ECM) is a complex network of proteins and glycans, dynamically remodeled and specifically tailored to the structure/function of each organ. The malignant transformation of cancer cells is determined by both cell intrinsic properties, such as mutations, and extrinsic variables, such as the mixture of surrounding cells in the tumor microenvironment and the biophysics of the ECM. During cancer progression, the ECM undergoes extensive remodeling, characterized by disruption of the basal lamina, vascular endothelial cell invasion, and development of fibrosis in and around the tumor cells resulting in increased tissue stiffness. This enhanced rigidity leads to aberrant mechanotransduction and further malignant transformation potentiating the de-differentiation, proliferation and invasion of tumor cells. Interestingly, this fibrotic microenvironment is primarily secreted and assembled by non-cancerous cells. Among them, the cancer-associated fibroblasts (CAFs) play a central role. CAFs massively produce fibronectin together with type I collagen. This review delves into the primary interactions and signaling pathways through which fibronectin can support tumorigenesis and metastasis, aiming to provide critical molecular insights for better therapy response prediction.

Activin receptors in human cancer: Functions, mechanisms, and potential clinical applications

Activins are members of the transforming growth factor-β (TGF-β) superfamily and act as key regulators in various physiological processes, such as follicle and embryonic development, as well as in multiple human diseases, including cancer. They have been established to signal through three type I and two type II serine/threonine kinase receptors, which, upon ligand binding, form a final signal-transducing receptor complex that activates downstream signaling and governs gene expression. Recent research highlighted the dysregulation of the expression or activity of activin receptors in multiple human cancers and their critical involvement in cancer progression. Furthermore, expression levels of activin receptors have been associated with clinicopathological features and patient outcomes across different cancers. However, there is currently a paucity of comprehensive systematic reviews of activin receptors in cancer. Thus, this review aimed to consolidate existing knowledge concerning activin receptors, with a primary emphasis on their signaling cascade and emerging biological functions, regulatory mechanisms, and potential clinical applications in human cancers in order to provide novel perspectives on cancer prognosis and targeted therapy.

Expression Analysis of Early Metastatic Seeding of Colorectal Cancer

BACKGROUND

Distant metastasis is the leading cause of death in patients with colorectal cancer (CRC). Tumor dissemination for metastasis formation occurs in advanced cancers and also during early stages of tumorigenesis. Here, we investigated the genes involved in early metastatic seeding of CRC using gene expression analysis.

PATIENTS AND METHODS

We performed a cDNA microarray using specimens resected from stages I-II CRC with and without metachronous metastatic recurrence. For the candidate genes, we immunohistochemically validated protein expression using a tissue microarray of stages I-III CRC.

RESULTS

The expression of TROP2, VWCE, and BMP7 was upregulated in the recurrence group rather than in the non-recurrence group. Protein expression analysis revealed significant association of these genes with distant metastatic recurrence. The specimens with high expression of BMP7 showed worse recurrence-free survival (RFS; p = 0.02). Those with high expression of TROP2 and VWCE showed worse overall survival (OS) and RFS (TROP2: p = 0.01 and p = 0.03; VWCE: p < 0.05 and p < 0.001, respectively). In the multivariate analysis, high expression of VWCE and BMP7 was an independent predictor of recurrence [VWCE: hazard ratio (HR) 3.41, p < 0.001; BMP7: HR 2.93, p = 0.005]. In contrast, TROP2 was an independent prognostic factor for OS (HR 4.58, p = 0.03).

CONCLUSIONS

Gene expression analysis revealed that TROP2, VWCE, and BMP7 were involved in early metastatic seeding. The high expression of these genes may warrant careful surveillance or adjuvant therapy, even in stages I-II CRC cases.

Potential of bone morphogenetic protein-7 in treatment of lupus nephritis: addressing the hurdles to implementation

Up to 50% of systemic lupus erythematosus (SLE) patients world-wide develop lupus nephritis (LN). In low to middle income countries and in particular in sub-Saharan Africa, where SLE is prevalent with a more aggressive course, LN and end stage renal disease is a major cause of mortality. While developed countries have the funding to invest in SLE and LN research, patients of African descent are often underrepresented in clinical trials. Thus, the complex influence of ethnicity and genetic background on outcome of LN and SLE as a whole, is not fully understood. Several pathophysiological mechanisms including major role players driving LN have been identified. A large body of literature suggest that prevention of fibrosis-which contributes to chronicity of LN-may significantly improve long-term prognosis. Bone morphogenetic protein-7 (BMP-7) was first identified as a therapeutic option in this context decades ago and evidence of its benefit in various conditions, including LN, is ever-increasing. Despite these facts, BMP-7 is not being implemented as therapy in the context of renal disease. With this review, we briefly summarise current understanding of LN pathology and discuss the evidence in support of therapeutic potential of BMP-7 in this context. Lastly, we address the obstacles that need to be overcome, before BMP-7 may become available as LN treatment.

Elucidation of the Role of SMAD4 in Epithelial-Mesenchymal Plasticity: Does It Help to Better Understand the Consequences of DPC4 Inactivation in the Malignant Progression of Pancreatic Ductal Adenocarcinoma?

Pancreatic ductal adenocarcinoma (PDAC) is the 4th leading cause of cancer-related mortality worldwide, with a 5-year-survival rate below 10% that is the lowest of all cancer types [...].

Suppressive Role of ACVR1/ALK2 in Basal and TGFβ1-Induced Cell Migration in Pancreatic Ductal Adenocarcinoma Cells and Identification of a Self-Perpetuating Autoregulatory Loop Involving the Small GTPase RAC1b

Pancreatic ductal adenocarcinoma (PDAC) cells are known for their high invasive/metastatic potential, which is regulated in part by the transforming growth factor β1 (TGFβ1). The involvement of at least two type I receptors, ALK5 and ALK2, that transmit downstream signals of the TGFβ via different Smad proteins, SMAD2/3 and SMAD1/5, respectively, poses the issue of their relative contribution in regulating cell motility. Real-time cell migration assays revealed that the selective inhibition of ALK2 by RNAi or dominant-negative interference with a kinase-dead mutant (ALK2-K233R) strongly enhanced the cells’ migratory activity in the absence or presence of TGFβ1 stimulation. Ectopic ALK2-K233R expression was associated with an increase in the protein levels of RAC1 and its alternatively spliced isoform, RAC1b, both of which are implicated in driving cell migration and invasion. Conversely, the RNAi-mediated knockdown or CRISPR/Cas9-mediated knockout of RAC1b resulted in the upregulation of the expression of ALK2, but not that of the related BMP type I receptors, ALK3 or ALK6, and elevated the phosphorylation of SMAD1/5. PDAC is a heterogeneous disease encompassing tumors with different histomorphological subtypes, ranging from epithelial/classical to extremely mesenchymal. Upon treatment of various established and primary PDAC cell lines representing these subtypes with the ALK2 inhibitor, LDN-193189, well-differentiated, epithelial cell lines responded with a much stronger increase in the basal and TGFβ1-dependent migratory activity than poorly differentiated, mesenchymal ones. These data show that (i) ALK2 inhibits migration by suppressing RAC1/RAC1b proteins, (ii) ALK2 and RAC1b act together in a self-perpetuating the autoregulatory negative feedback loop to mutually control their expression, and (iii) the ALK2 antimigratory function appears to be particularly crucial in protecting epithelial subtype cells from becoming invasive, both spontaneously and in a TGFβ-rich tumor microenvironment.

Functional Differentiation of BMP7 Genes in Zebrafish: bmp7a for Dorsal-Ventral Pattern and bmp7b for Melanin Synthesis and Eye Development

Bone morphogenetic protein 7 (BMP7) belongs to the transforming growth factor β (TGF-β) family, which not only induces cartilage and bone formation, but also regulates eye development and melanoma tumorigenesis in mammals. In teleosts, BMP7 differentiates into two subtypes, bmp7a and bmp7b, which have clearly differentiated structures. To fully understand the functional differentiation of bmp7a and bmp7b in fish species, we successfully constructed bmp7a and bmp7b gene deletion mutants in zebrafish using CRISPR/Cas9-mediated gene editing technology. Our results showed that bmp7a mutation caused abnormal development of the embryo’s dorsal-ventral pattern that led to death; bmp7b mutation induced growth inhibition and increased melanin production in the skin and eye of mutants. Histological analysis revealed that melanin in the retina of the eyes in bmp7b mutants increased, and behavioral observation showed that the vision and sensitivity to food of the mutants were reduced. Transcriptome analysis of the skin and eye tissues showed that the expression changes of wnt7ba and gna14 in bmp7b mutants might promote the increase of melanin. Additionally, the eye transcriptome analysis indicated that changes in the structure of the eyes in bmp7b mutants led to defects in phototransduction, and seven DEGs (rgs9a, rgs9b, rcvrn2, guca1d, grk1b, opn1mw4, and gc2) were identified as key candidate genes that affected the photonic response of the eyes. The study revealed the functional differentiation of bmp7a and bmp7b in teleosts and the first report about the inhibitory effect of bmp7b on melanogenesis may provide useful information for the future research on human melanoma-related diseases.

Novel Concepts: Langerhans Cells in the Tumour Microenvironment

Langerhans cells (LCs) are immune cells that reside in the stratified epithelium of the skin and mucosal membranes. They play a range of roles in the skin, including antigen presentation and maintenance of peripheral tolerance. Reports of LC numbers have been variable in different cancer types, with the majority of studies indicating a reduction in their number. Changes in the cytokine profile and other secreted molecules, downregulation of surface molecules on cells and hypoxia all contribute to the regulation of LCs in the tumour microenvironment. Functionally, LCs have been reported to regulate immunity and carcinogenesis in different cancer types. An improved understanding of the function and biology of LCs in tumours is essential knowledge that underpins the development of new cancer immunotherapies.

Height, nevus count, and risk of cutaneous malignant melanoma: Results from 2 large cohorts of US women

BACKGROUND

Taller individuals are at higher risk of melanoma.

OBJECTIVE

To prospectively investigate the association of height with nevus count and melanoma and estimate the proportion of height-melanoma association explained by nevus count among white participants from the Nurses' Health Study (NHS) and Nurses' Health Study 2 (NHS2).

METHODS

We used Cox proportional hazards regression and multinomial logistic regression for data analyses, with adjustment of potential confounders in the multivariate model.

RESULTS

We included 82,468 and 106,069 women from NHS and NHS2, respectively. The hazard ratio was 1.21 (95% confidence interval [CI] 1.12-1.31) for the association between every 10-cm increase in height and melanoma. Compared with women with no nevi, the odds ratios (95% CIs) associated with a 10-cm increase in height were 1.35 (95% CI 1.23-1.48) in the NHS and 1.12 (95% CI 1.09-1.15) in the NHS2 for women with greater than or equal to 10 moles. The proportion of excess melanoma risk associated with each 10-cm increase in height explained by nevus count was 8.03% in the NHS and 10.22% in the NHS2.

LIMITATION

Self-reported height and nevus count. Mole counts were limited to 1 arm or both legs.

CONCLUSION

Nevus count is an important explanatory factor for the excess risk of melanoma among taller white women.

Expression of BMP7 in cervical cancer and inhibition of epithelial‑mesenchymal transition by BMP7 knockdown in HeLa cells

The aim of the present study was to investigate the expression of bone morphogenetic protein 7 (BMP7) in cervical cancer tissues, the effect of BMP7 on the proliferation, migration and epithelial-mesenchymal transition (EMT) of cervical cancer HeLa cells and the possible mechanism involved. Immunohistochemistry was used to stain the cervical cancer tissues and benign or precancerous lesions. Lentivirus containing BMP7 knockdown was transfected in HeLa cells and western blotting was performed to analyze BMP7 expression. At the same time, the influence of BMP7 knockdown on the expression of phosphorylated (p)-mothers against decapentaplegic homolog 1/5/9 and EMT-related markers [epithelial-cadherin, neural-cadherin, Vimentin, Snail and Slug] was detected. Cell Counting Kit-8 was used to detect cell proliferation. Transwell migration and invasion assays were performed to measure cell invasion and migration. The cell cycle was detected by flow cytometry. Compared with normal cervical epithelial and paracancerous cells, the positive rate of BMP7 expression in cervical cancer tissues was significantly increased. As compared with the control group, the expression of BMP7 was decreased in HeLa cells transfected with lentivirus. The knockdown of BMP7 in cervical cancer HeLa cells inhibited cell proliferation, migration and invasion, resulted in G1 cell cycle arrest and reversed the EMT process. In addition, the expression of p-Smad1/5/9 was significantly decreased in HeLa cells with BMP7 knockdown. BMP7 is expected to be a possible target for the treatment of cervical cancer.

Expression Of BMP7 In Ovarian Cancer And Biological Effect Of BMP7 Knockdown On Ovarian Cancer Cells

Purpose

The aim of our research was to investigate the expression of BMP7 in ovarian cancer (OC) and the biological effect of knocking down BMP7 on ovarian cancer A2780 cells.

Methods

We detected BMP7 expression in ovarian cancer and normal ovarian tissue by immunohistochemistry (IHC). We downregulated BMP7 expression using lentivirus-mediated RNAi and then examined the effects of knocking down BMP7 on the cell growth and invasion, cell cycle and paclitaxel sensitivity of A2780 cells. The mRNA and protein levels were detected by total RNA extraction and quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting, respectively. Cell proliferation was measured by CCK-8 and colony formation assays. The number of cells in each cell cycle stage and those undergoing apoptosis were measured by flow cytometry.

Results

BMP7 expression was significantly higher in the ovarian cancer tissues than it was in the normal ovarian tissues. Knocking down BMP7 in ovarian cancer A2780 cells inhibited cell proliferation, migration and invasion; led to G1 cell cycle arrest; and reversed the epithelial-mesenchymal transformation (EMT) process. In addition, downregulating BMP7 increased the sensitivity of the A2780 cells to paclitaxel. Moreover, BMP7 downregulation resulted in decreased expression of Smad1/5/9, p-Smad1/5/9, ID2 and cyclin D1 protein.

Conclusion

The results presented here are expected to contribute to the development of possible therapeutic targets for patients with ovarian cancer.

Dormancy and cancer stem cells: An enigma for cancer therapeutic targeting

Dormancy occurs when cells remain viable but stop proliferating. When most of a cancer population undergoes this phenomenon, the result is called tumor dormancy, and when a single cancer cell undergoes this process, it is termed quiescence. Cancer stem cells (CSCs) share several overlapping characteristics and signaling pathways with dormant cancer cells, including therapy resistance, and an ability to metastasize and evade the immune system. Cancer cells can be broadly grouped into dormancy-competent CSCs (DCCs), cancer-repopulating cells (CRCs), dormancy-incompetent CSCs and disseminated tumor cells (DTCs). The settings in which cancer cells exploit the dormancy phase to survive and adapt are: (i) primary cancer dormancy; (ii) metastatic dormancy; (iii) therapy-induced dormancy; and (iv) immunologic dormancy. Dormancy, therapy resistance and plasticity of CSCs are fundamentally interconnected processes mediated through mechanisms involving reversible genetic alterations. Niches including metastatic, bone marrow, and perivascular are known to harbor dormant cancer cells. Mechanisms of dormancy induction are complex and multi-factorial and can involve angiogenic switching, addictive oncogene inhibition, immunoediting, anoikis, therapy, autophagy, senescence, epigenetic, and biophysical regulation. Therapy can have opposing effects on cancer cells with respect to dormancy; some therapies can induce dormancy, while others can reactivate dormant cells. There is a lack of consensus relative to the value of therapy-induced dormancy, i.e., some researchers view dormancy induction as a beneficial strategy as it can lead to metastasis inhibition, while others argue that reactivating dormant cancer cells and then eliminating them through therapy are a better approach. More focused investigations of intrinsic cell kinetics and environmental dynamics that promote and maintain cancer cells in a dormant state, and the long-term consequences of dormancy are critical for improving current therapeutic treatment outcomes.

BMP6-induced modulation of the tumor micro-milieu

Melanoma is the deadliest form of skin cancer with rising incidence, creating a significant health problem. We discovered increased expression of bone morphogenetic protein 6 (BMP6) in melanoma cells and tissues, and observed that BMP6 deficiency caused significantly delayed tumor onset and decelerated tumor progression in a melanoma mouse model. Moreover, we determined that BMP6 inhibits dermal mast cell recruitment and found that mast cell-derived mediators significantly reduced melanoma growth in vitro. In line with this, mast cell deficiency accelerated tumor onset and progression in a melanoma mouse model. Analysis of human melanoma tissues revealed a strong negative correlation between melanoma proliferation and mast cell infiltration. This study elucidates a novel role of BMP6-induced modulation of the tumor microenvironment.

Cytokine sensitivity screening highlights BMP4 pathway signaling as a therapeutic opportunity in ER+ breast cancer

Despite the success of approved systemic therapies for estrogen receptor α (ER)-positive breast cancer, drug resistance remains common. We hypothesized that secreted factors from the human tumor microenvironment could modulate drug resistance. We previously screened a library of 297 recombinant-secreted microenvironmental proteins for the ability to confer resistance to the anti-estrogen fulvestrant in 2 ER⁺ breast cancer cell lines. Herein, we considered whether factors that enhanced drug sensitivity could be repurposed as therapeutics and provide leads for drug development. Screening data revealed bone morphogenic protein (BMP)4 as a factor that inhibited cell growth and synergized with approved anti-estrogens and cyclin-dependent kinase 4/6 inhibitors (CDK4/6_i). BMP4-mediated growth inhibition was dependent on type I receptor activin receptor-like kinase (ALK)3-dependent phosphorylation (P) of mothers against decapentaplegic homolog (SMAD/P-SMAD)1 and 5, which could be reversed by BMP receptor inhibitors and ALK3 knockdown. The primary effect of BMP4 on cell fate was cell-cycle arrest, in which RNA sequencing, immunoblot analysis, and RNA interference revealed to be dependent on p21^WAF1/Cip1 upregulation. BMP4 also enhanced sensitivity to approved inhibitors of mammalian target of rapamycin complex 1 and CDK4/6 via ALK3-mediated P-SMAD1/5 and p21 upregulation in anti-estrogen-resistant cells. Patients bearing primary ER⁺ breast tumors, exhibiting a transcriptomic signature of BMP4 signaling, had improved disease outcome following adjuvant treatment with anti-estrogen therapy, independently of age, tumor grade, and tumor stage. Furthermore, a transcriptomic signature of BMP4 signaling was predictive of an improved biologic response to the CDK4/6_i palbociclib, in combination with an aromatase inhibitor in primary tumors. These findings highlight BMP4 and its downstream pathway activation as a therapeutic opportunity in ER⁺ breast cancer.-Shee, K., Jiang, A., Varn, F. S., Liu, S., Traphagen, N. A., Owens, P., Ma, C. X., Hoog, J., Cheng, C., Golub, T. R., Straussman, R., Miller, T. W. Cytokine sensitivity screening highlights BMP4 pathway signaling as a therapeutic opportunity in ER⁺ breast cancer.

Biological effects of BMP7 on small-cell lung cancer cells and its bone metastasis

Small-cell lung cancer (SCLC) is typically fatal if untreated. It is characterized by early and widespread metastases, and has the ability to rapidly develop resistance to chemotherapy. Bone morphogenetic protein 7 (BMP7), a member of the BMP family of signaling molecules, has been implicated in various types of cancer, particularly prostate cancer and breast cancer. However, there is little knowledge of the function of BMP7 in SCLC. The aim of the present study was to investigate the biological function of recombinant human (rh)BMP7 on SCLC cells and the underlying molecular basis for this regulatory mechanism. The effect of rhBMP7 on SCLC cell lines and associated signaling pathways was investigated. Results suggested that rhBMP7 significantly inhibited the proliferation, motility and invasion of SBC-3 and SBC-5 cells. However, rhBMP7 exhibited no effect on the apoptosis of SBC-5 cells, but promoted apoptosis of SBC-3 cells. Furthermore, cell cycle analysis revealed that rhBMP7 was able to increase the proportion of cells in G1 phase and decrease the S phase proportion. Total and membrane BMP receptor (BMPR)IA and BMPRIB were highly expressed in SBC-5 cells, whereas cytoplasmic BMPRIA and BMPRIB expression was higher in SBC-3 cells. However, activin A receptor type I expression was higher in SBC-3 cells in total and cytoplasmic proteins. Furthermore, following stimulation with rhBMP7, Smad2, Smad4 and p21 were downregulated. We hypothesized that rhBMP7 inhibited the progressiveness of SCLC cells by inducing G1 phase arrest and inhibiting S phase entry. The results of the present study indicated that BMP7 serves a key function in regulating the progression of SCLC.

Dual role of Par-4 in abrogation of EMT and switching on Mesenchymal to Epithelial Transition (MET) in metastatic pancreatic cancer cells

Epithelial-mesenchymal transition (EMT) is a critical event that occurs during the invasion and metastatic spread of cancer cells. Here, we conceive a dual mechanism of Par-4-mediated inhibition of EMT and induction of MET in metastatic pancreatic cancer cells. First, we demonstrate that 1,1'-β-D-glucopyranosyl-3,3'-bis(5-bromoindolyl)-octyl methane (NGD16), an N-glycosylated derivative of medicinally important phytochemical 3,3'-diindolylmethane (DIM) abrogates EMT by inducing pro-apoptotic protein Par-4. Induction of Par-4 (by NGD16 or ectopic overexpression) strongly impedes invasion with inhibition of major mesenchymal markers viz. Vimentin and Twist-1 epithelial marker- E-cadherin. Further, NGD16 triggers MET phenotypes in pancreatic cancer cells by augmenting ALK2/Smad4 signaling in a Par-4-dependent manner. Conversely, siRNA-mediated silencing of endogenous Par-4 unveil reversal of MET with diminished E-cadherin expression and invasive phenotypes. Additionally, we demonstrate that intact Smad4 is essential for Par-4-mediated maintenance of E-cadherin level in MET induced cells. Notably, we imply that Par-4 induction regulates E-cadherin levels in the pancreatic cancer cells via modulating Twist-1 promoter activity. Finally, in vivo studies with syngenic mouse metastatic pancreatic cancer model reveal that NGD16 strongly suppresses metastatic burden, ascites formation, and prolongs the overall survival of animals effectively.

BMP signaling and its paradoxical effects in tumorigenesis and dissemination

Bone morphogenetic proteins (BMPs) play important roles in embryonic and postnatal development by regulating cell differentiation, proliferation, motility, and survival, thus maintaining homeostasis during organ and tissue development. BMPs can lead to tumorigenesis and regulate cancer progression in different stages. Therefore, we summarized studies on BMP expression, the clinical significance of BMP dysfunction in various cancer types, and the molecular regulation of various BMP-related signaling pathways. We emphasized on the paradoxical effects of BMPs on various aspects of carcinogenesis, including epithelial–mesenchymal transition (EMT), cancer stem cells (CSCs), and angiogenesis. We also reviewed the molecular mechanisms by which BMPs regulate tumor generation and progression as well as potential therapeutic targets against BMPs that might be valuable in preventing tumor growth and invasion.

Langerhans Cells: Sensing the Environment in Health and Disease

In the last few decades, our understanding of Langerhans cells (LCs) has drastically changed based on novel findings regarding the developmental origin and biological functions of these epidermis-specific resident immune cells. It has become clear that LCs not only exert pivotal roles in immune surveillance and homeostasis but also impact on pathology by either inducing tolerance or mediating inflammation. Their unique capabilities to self-renew within the epidermis, while also being able to migrate to lymph nodes in order to present antigen, place LCs in a key position to sample the local environment and decide on the appropriate cutaneous immune response. Exciting new data distinguishing LCs from Langerin⁺ dermal dendritic cells (DCs) on a functional and ontogenic level reveal crucial roles for LCs in trauma and various skin pathologies, which will be thoroughly discussed here. However, despite rapid progress in the field, the exact role of LCs during immune responses has not been completely elucidated. This review focuses on what mouse models that have been developed in order to enable the study of murine LCs and other Langerin-expressing DCs have taught us about LC development and function.

Ligand-activated BMP signaling inhibits cell differentiation and death to promote melanoma

Oncogenomic studies indicate that copy number variation (CNV) alters genes involved in tumor progression; however, identification of specific driver genes affected by CNV has been difficult, as these rearrangements are often contained in large chromosomal intervals among several bystander genes. Here, we addressed this problem and identified a CNV-targeted oncogene by performing comparative oncogenomics of human and zebrafish melanomas. We determined that the gene encoding growth differentiation factor 6 (GDF6), which is the ligand for the BMP family, is recurrently amplified and transcriptionally upregulated in melanoma. GDF6-induced BMP signaling maintained a trunk neural crest gene signature in melanomas. Additionally, GDF6 repressed the melanocyte differentiation gene MITF and the proapoptotic factor SOX9, thereby preventing differentiation, inhibiting cell death, and promoting tumor growth. GDF6 was specifically expressed in melanomas but not melanocytes. Moreover, GDF6 expression levels in melanomas were inversely correlated with patient survival. Our study has identified a fundamental role for GDF6 and BMP signaling in governing an embryonic cell gene signature to promote melanoma progression, thus providing potential opportunities for targeted therapy to treat GDF6-positive cancers.

Cancer cell dormancy: mechanisms and implications of cancer recurrence and metastasis

More recently, disease metastasis and relapse in many cancer patients several years (even some decades) after surgical remission are regarded as tumor dormancy. However, the knowledge of this phenomenon is cripplingly limited. Substantial quantities of reviews have summarized three main potential models that can be put forth to explain such process, including angiogenic dormancy, immunologic dormancy, and cellular dormancy. In this review, newly uncovered mechanisms governing cancer cell dormancy are discussed, with an emphasis on the cross talk between dormant cancer cells and their microenvironments. In addition, potential mechanisms of reactivation of these dormant cells in certain anatomic sites including lymph nodes and bone marrow are discussed. Molecular mechanism of cellular dormancy in head and neck cancer is also involved.

Effects of exogenous recombinant human bone morphogenic protein-7 on the corneal epithelial mesenchymal transition and fibrosis

AIM

To evaluate the effect of exogenous recombinant human bone morphogenic protein-7 (rhBMP-7) on transforming growth factor-β (TGF-β)-induced epithelial mesenchymal cell transition (EMT) and assessed its antifibrotic effect via topical application.

METHODS

The cytotoxic effect of rhBMP-7 was evaluated and the EMT of human corneal epithelial cells (HECEs) was induced by TGF-β. HECEs were then cultured in the presence of rhBMP-7 and/or hyaluronic acid (HA). EMT markers, fibronectin, E-cadherin, α-smooth muscle actin (α-SMA), and matrix metaloproteinase-9 (MMP-9), were evaluated. The level of corneal fibrosis and the reepithelization rate were evaluated using a rabbit keratectomy model. Expression of α-SMA in keratocytes were quantified following treatment with different concentrations of rhBMP-7.

RESULTS

Treatment with rhBMP-7 attenuated TGF-β-induced EMT in HECEs. It significantly attenuated fibronectin secretion (31.6%; P<0.05), the α-SMA protein level (72.2%; P<0.01), and MMP-9 expression (23.6%, P<0.05) in HECEs compared with cells grown in the presence of TGF-β alone. E-cadherin expression was significantly enhanced (289.7%; P<0.01) in the presence of rhBMP-7. Topical application of rhBMP-7 combined with 0.1% HA significantly reduced the amount of α-SMA⁺ cells by 43.18% (P<0.05) at a concentration of 2.5 µg/mL and by 47.73% (P<0.05) at 25 µg/mL, compared with the control group, without disturbing corneal reepithelization.

CONCLUSION

rhBMP-7 attenuates TGF-β-induced EMT in vitro, and topical application of rhBMP-7 reduces keratocyte myodifferentiation during the early wound healing stages in vivo without hindering reepithelization. Topical rhBMP-7 application as biological eye drops seems to be feasible in diseases involving TGF-β-related corneal fibrosis with corneal reepithelization disorders.

Migration and epithelial-to-mesenchymal transition of lung cancer can be targeted via translation initiation factors eIF4E and eIF4GI

Metastasis underlies cancer morbidity and accounts for disease progression and significant death rates generally and in non-small cell lung cancer (NSCLC) particularly. Therefore, it is critically important to understand the molecular events that regulate metastasis. Accumulating data portray a central role for protein synthesis, particularly translation initiation (TI) factors eIF4E and eIF4G in tumorigenesis and patients' survival. We have published that eIF4E/eIF4GI activities and consequently NSCLC cell migration are modulated by bone-marrow mesenchymal stem cell secretomes, suggesting a role for TI in metastasis. Here, we aimed to expand our understanding of the TI factors significance to NSCLC characteristics, particularly epithelial-to-mesenchymal transition (EMT) and migration, supportive of metastasis. In a model of NSCLC cell lines (H1299, H460), we inhibited eIF4E/eIF4GI's expressions (siRNA, ribavirin) and assessed NSCLC cell lines' migration (scratch), differentiation (EMT, immunoblotting), and expression of select microRNAs (qPCR). Initially, we determined an overexpression of several TI factors (eIF4E, eIF4GI, eIF4B, and DHX29) and their respective targets in NSCLC compared with normal lung samples (70-350%↑, P<0.05). Knockdown (KD) of eIF4E/eIF4GI in NSCLC cell lines (70%↓, P<0.05) also manifested in decreased target levels (ERα, SMAD5, NFkB, CyclinD1, c-MYC, and HIF1α) (20-50%↓, P<0.05). eIF4E/eIF4GI KD also attenuated cell migration (60-75%↓, P<0.05), EMT promoters (15-90%↓, P<0.05), and enhanced EMT suppressors (30-380%↑, P<0.05). The importance of eIF4E KD to NSCLC phenotype was further corroborated with its inhibitor, ribavirin. Changes in expression of essential microRNAs implicated in NSCLC cell migration concluded the study (20-100%, P<0.05). In summary, targeting eIF4E/eIF4GI reduces migration and EMT, both essential for metastasis, thereby underscoring the potential of TI targeting in NSCLC therapy, especially the already clinically employed agents (ribavirin/4EGI). Comparison of these findings with previously reported effects of eIF4E/eIF4GI KD in multiple myeloma suggests a collective role for these TI factors in cancer progression.

Bone morphogenetic protein-7 prevented epithelial-mesenchymal transition in RLE-6TN cells

Bone morphogenetic protein-7 (BMP-7) plays an important role in the epithelial-mesenchymal transition (EMT) process, and has been identified as the most potent factor that can promote mesenchymal-epithelial transition (MET) and reduce organ fibrosis. Here we examined the important role of BMP-7 in silica-induced EMT and investigated the relationship between BMP-7 and the balance of EMT/MET. We found that silica induced EMT and decreased the expression of BMP-7 in vivo and in vitro, while silica activated the p38 MAPK/transcription factor signaling pathway in RLE-6TN cells. Lentivirus mediated transfection was used to stably upregulate the expression of BMP-7. Exogenous BMP-7 brought on MET exceeded silica-induced EMT and restrained the p38 MAPK/transcription factor signaling pathway in RLE-6TN cells. Our results revealed that BMP-7 promoted MET above EMT induced by silica associated with inhibition of the p38 MAPK/transcription factor signaling pathway, and BMP-7 was a potential target for treatment of silicosis fibrosis.

Epithelial to Mesenchymal Transition in a Clinical Perspective

Tumor growth and metastatic dissemination rely on cellular plasticity. Among the different phenotypes acquired by cancer cells, epithelial to mesenchymal transition (EMT) has been extensively illustrated. Indeed, this transition allows an epithelial polarized cell to acquire a more mesenchymal phenotype with increased mobility and invasiveness. The role of EMT is quite clear during developmental stage. In the neoplastic context in many tumors EMT has been associated with a more aggressive tumor phenotype including local invasion and distant metastasis. EMT allows the cell to invade surrounding tissues and survive in the general circulation and through a stem cell phenotype grown in the host organ. The molecular pathways underlying EMT have also been clearly defined and their description is beyond the scope of this review. Here we will summarize and analyze the attempts made to block EMT in the therapeutic context. Indeed, till today, most of the studies are made in animal models. Few clinical trials are ongoing with no obvious benefits of EMT inhibitors yet. We point out the limitations of EMT targeting such tumor heterogeneity or the dynamics of EMT during disease progression.

Modulation of the EMT/MET process by pyrrole-imidazole polyamide targeting human transforming growth factor-β1

Transforming growth factor-β1 (TGF-β1) is a potent induction factor for epithelial-mesenchymal transition (EMT). Mesenchymal-epithelial transition (MET), as the inverse process of EMT, has recently been reported to promote the induction of induced pluripotent stem cells (iPSCs). We have developed pyrrole-imidazole (PI) polyamide, a novel gene regulator that targets human TGF-β1, and investigated its effects on the EMT/MET process. PI polyamide targeted to TGF-β1 significantly inhibited the mRNA expression of TGF-β1 and SNAI1 as an EMT marker and increased mRNA and protein expression of E-cadherin in human epithelial cells. To enhance the induction of iPSCs by the MET process, PI polyamide targeted to TGF-β1 was applied to human fibroblasts transfected with exogenous reprogramming factors by Sendai virus vector and grown in human iPSCs. The PI polyamide significantly increased the number of alkaline phosphatase-positive colonies. The expression of undifferentiated markers was also observed in these colonies. These results suggest that PI polyamide targeted to human TGF-β is a novel compound that can control the EMT/MET process of human epithelial cells and enhance the induction of human fibroblasts to iPSCs.

Loss of GDF10/BMP3b as a prognostic marker collaborates with TGFBR3 to enhance chemotherapy resistance and epithelial-mesenchymal transition in oral squamous cell carcinoma

Growth differentiation factor-10 (GDF10), commonly referred as BMP3b, is a member of the transforming growth factor-β (TGF-β) superfamily. GDF10/BMP3b has been considered as a tumor suppressor, however, little is known about the molecular mechanism of its roles in tumor suppression in oral cancer. Clinical significance of GDF10 downregulation in oral squamous cell carcinoma (OSCC) was evaluated using three independent cohorts of OSCC patients. The molecular mechanisms of GDF10 in the suppression of cell survival, cell migration/invasion and epithelial-mesenchymal transition (EMT) were investigated by using oral cancer cell lines. The present study shows that GDF10 is downregulated during oral carcinogenesis, and GDF10 expression is also an independent risk factor for overall survival of OSCC patients. Overexpression of GDF10 attenuates cell proliferation, transformation, migration/invasion, and EMT. GDF10-inhibited EMT is mediated by ERK signaling but not by typical TGF-β signaling. In addition, overexpression of GDF10 promotes DNA damage-induced apoptosis and sensitizes the response to all-trans retinoic acid (ATRA) and camptothecin (CPT). Intriguingly, the expression of GDF10 is induced by type III TGF-β receptor (TGFBR3) through TGF-β-SMAD2/3 signaling. Our findings suggest that TGFBR3 is an upstream activator of GDF10 expression and they share the same signaling to inhibit EMT and migration/invasion. These results support that GDF10 acts as a hinge to collaborate with TGFBR3 in the transition of EMT-MET program. Taken together, we illustrated the clinical significance and the molecular mechanisms of tumor-suppressive GDF10 in OSCC.

Height and bone mineral density are associated with naevus count supporting the importance of growth in melanoma susceptibility

Naevus count is the strongest risk factor for melanoma. Body Mass Index (BMI) has been linked to melanoma risk. In this study, we investigate the link between naevus count and height, weight and bone mineral density (BMD) in the TwinsUK cohort (N = 2119). In addition we adjusted for leucocyte telomere length (LTL) as LTL is linked to both BMD and naevus count. Naevus count was positively associated with height (p = 0.001) but not with weight (p = 0.187) despite adjusting for age and twin relatedness. This suggests that the previously reported melanoma association with BMI may be explained by height alone. Further adjustment for LTL did not affect the significance of the association between height and naevus count so LTL does not fully explain these results. BMD was associated with naevus count at the spine (coeff 18.9, p = 0.01), hip (coeff = 18.9, p = 0.03) and forearm (coeff = 32.7, p = 0.06) despite adjusting for age, twin relatedness, weight, height and LTL. This large study in healthy individuals shows that growth via height, probably in early life, and bone mass are risk factors for melanoma via increased naevus count. The link between these two phenotypes may possibly be explained by telomere biology, differentiation genes from the neural crests but also other yet unknown factors which may influence both bones and melanocytes biology.

Placenta-breast cancer cell interactions promote cancer cell epithelial mesenchymal transition via TGFβ/JNK pathway

Women diagnosed with pregnancy associated breast cancer often have advanced cancer with metastases and reduced expression of ERα compared to non-pregnant women. Nevertheless, metastases to the placenta are uncommon. Previously, we demonstrated that breast cancer cells (MCF-7/T47D) migrated from ex vivo human placental explant implantation sites. We aimed to analyze the effect of factors produced during placental implantation or as a result of the interaction between the implanted placentae to cancer cells on cancer cells migration and aggressiveness. We collected supernatants from implanted placentae and placental-breast cancer cells cocultures and analyzed their effects on cancer cells phenotype and pathways. Supernatants collected from breast cancer cells served as controls. We found that supernatants collected from implanted placentae induced modest cancer cells migration that was not accompanied by epithelial to mesenchymal transition (EMT), supported breast cancer cells survival and elevated MCF-7 cell number. The coculture supernatant induced excessive motility and EMT of the MCF-7 cells. This EMT was mediated by Smad3 and JNK/ERK activation. Both placenta and coculture supernatants reduced ERα expression in the cancer cells. Finally, we showed that MCF-7 cocultured with the human placental explants underwent continuous activation of JNK and Smad3 pathways and the EMT process, which led to their migration away from the placental implantation sites. These findings may explain the reduced ERα and elevated metastases found in breast cancer during pregnancy and highlights pathways involved in it.

BMP-7 blocks the effects of TGF-β-induced EMT in cholangiocarcinoma

Epithelial-mesenchymal transition (EMT) is characterized by the loss of epithelial markers and the gain of mesenchymal markers. EMT is believed to be a major mechanism supporting cancer cell metastasis. The activation of EMT can be induced by various types of inflammatory cytokines including transforming growth factor β (TGF-β) whereas bone morphogenetic protein-7 (BMP-7) can inhibit this process. In this study, the up-regulation of Twist transcription factor and N-cadherin, mesenchymal marker in CCA tissues, has been demonstrated and it has been found that the high expression of Twist was significantly associated with poor prognosis of CCA patients (P = 0.010). Moreover, CCA samples showing Twist nuclear expression were significantly correlated with the up-regulation of N-cadherin (P = 0.024). These results also showed that the inflammatory mediator TGF-β induces CCA cell migration, one of the metastatic processes possibly via stimulation of Twist, N-cadherin and vimentin expression. Additionally, it has been shown that BMP-7 inhibits TGF-β-induced CCA cell migration, through inhibition of TGF-β-mediated Twist and N-cadherin expressions. These data reinforce the rationale to use BMP-7 as an EMT inhibitor to suppress the progression of CCA and might be a therapeutic approach to improve efficiency for CCA treatment.

Stem cells and targeted approaches to melanoma cure

Melanoma stem cells, also known as malignant melanoma-initiating cells, are identifiable through expression of specific biomarkers such as ABCB5 (ATP-binding cassette, sub-family B (MDR/TAP), member 5), NGFR (nerve growth factor receptor, CD271) and ALDH (aldehyde dehydrogenase), and drive melanoma initiation and progression based on prolonged self-renewal capacity, vasculogenic differentiation and immune evasion. As we will review here, specific roles of these aggressive subpopulations have been documented in tumorigenic growth, metastatic dissemination, therapeutic resistance, and malignant recurrence. Moreover, recent findings have provided pre-clinical proof-of-concept for the potential therapeutic utility of the melanoma stem cell concept. Therefore, melanoma stem cell-directed therapeutic approaches represent promising novel strategies to improve therapy of this arguably most virulent human cancer.

Twist: a molecular target in cancer therapeutics

Twist, the basic helix-loop-helix transcription factor, is involved in the process of epithelial to mesenchymal transitions (EMTs), which play an essential role in cancer metastasis. Overexpression of Twist or its promoter methylation is a common scenario in metastatic carcinomas. Twist is activated by a variety of signal transduction pathways, including Akt, signal transducer and activator of transcription 3, mitogen-activated protein kinase, Ras, and Wnt signaling. Activated Twist upregulates N-cadherin and downregulates E-cadherin, which are the hallmarks of EMT. Moreover, Twist plays an important role in some physiological processes involved in metastasis, like angiogenesis, invadopodia, extravasation, and chromosomal instability. Twist also protects cancer cells from apoptotic cell death. In addition, Twist is responsible for the stemness of cancer cells and the generation of drug resistance. Recently, targeting Twist has gained significant interests in cancer therapeutics. The inactivation of Twist by small RNA technology or chemotherapeutic approach has been proved successful. Moreover, several inhibitors which are antagonistic to the upstream or downstream molecules of Twist signaling pathways have also been identified. Development of potential treatment strategies by targeting Twist has a great promise in cancer therapeutics.

Genetic parameters and genome-wide association study of hyperpigmentation of the visceral peritoneum in chickens

BACKGROUND

Hyperpigmentation of the visceral peritoneum (HVP) has recently garnered much attention in the poultry industry because of the possible risk to the health of affected animals and the damage it causes to the appearance of commercial chicken carcasses. However, the heritable characters of HVP remain unclear. The objective of this study was to investigate the genetic parameters of HVP by genome-wide association study (GWAS) in chickens.

RESULTS

HVP was found to be influenced by genetic factors, with a heritability score of 0.33. HVP had positive genetic correlations with growth and carcass traits, such as leg muscle weight (rg = 0.34), but had negative genetic correlations with immune traits, such as the antibody response to Newcastle disease virus (rg = -0.42). The GWAS for HVP using 39,833 single nucleotide polymorphisms indicated the genetic factors associated with HVP displayed an additive effect rather than a dominance effect. In addition, we determined that three genomic regions, involving the 50.5-54.0 Mb region of chicken (Gallus gallus) chromosome 1 (GGA1), the 58.5-60.5 Mb region of GGA1, and the 10.5-12.0 Mb region of GGA20, were strongly associated (P < 6.28 × 10-7) with HVP in chickens. Variants in these regions explained >50% of additive genetic variance for HVP. This study also confirmed that expression of BMP7, which codes for a bone morphogenetic protein and is located in one of the candidate regions, was significantly higher in the visceral peritoneum of Huiyang Beard chickens with HVP than in that of chickens without pigmentation (P < 0.05).

CONCLUSIONS

HVP is a quantitative trait with moderate heritability. Genomic variants resulting in HVP were identified on GGA1 and GGA20, and expression of the BMP7 gene appears to be upregulated in HVP-affected chickens. Findings from this study should be used as a basis for further functional validation of candidate genes involved in HVP.

Activation of the PTHRP/adenylate cyclase pathway promotes differentiation of rat XEN cells into parietal endoderm, whereas Wnt/β-catenin signaling promotes differentiation into visceral endoderm

During early mammalian development, primitive endoderm (PrE) is specified and segregated away from the pluripotent epiblast. At a later developmental stage, PrE forms motile parietal endoderm (PE) lying proximal to the trophectoderm, and visceral endoderm (VE) that contacts the developing epiblast and extraembryonic ectoderm. Mouse extraembryonic endoderm (XEN) cells were isolated and became widely used to study signals governing lineage specification. Rat XEN cell lines have also been derived, but were distinguished from mouse by expression of SSEA1 and Oct4. We showed here that rat XEN cells grown in the presence of a GSK3 inhibitor or overexpressing β-catenin exhibited enhanced formation of cell contacts and decreased motility. Rat XEN cells treated with BMP4 revealed similar morphological changes. Furthermore, we observed that rat XEN cells cultured with GSK3 inhibitor formed adhesion and tight junctions, and acquired bottom-top polarity, indicating the formation of VE cells. In contrast, forskolin, an activator of the cAMP pathway, induced the disruption of cell contacts in rat XEN cells. Treatment with forskolin induced PE formation and epithelial-mesenchymal transition (EMT) in rat XEN cells. Using microarray and real-time PCR assays, we found that VE versus PE formation of rat XEN cells was correlated with change in expression levels of VE or PE marker genes. Similar to forskolin, EMT was prompted upon treatment of rat XEN cells with recombinant parathyroid hormone related peptide (PTHRP), an activator of the cAMP pathway in vivo. Taken together, our data suggest that rat XEN cells are PrE-like cells. The activation of Wnt or BMP4 pathways in rat XEN cells leads to the acquisition of VE characteristics, whereas the activation of the PTHRP/cAMP pathway leads to EMT and the formation of PE.

Microenvironmental regulation of epithelial-mesenchymal transitions in cancer

The evolution of the cancer cell into a metastatic entity is the major cause of death in patients with cancer. Activation of the epithelial-to-mesenchymal transition (EMT) endows invasive and metastatic properties upon cancer cells that favor successful colonization of distal target organs. The observation that in many cancers distant metastases resemble the epithelial phenotype of primary tumors has led to speculation that the disseminated tumor cells recruited to the target organs undergo mesenchymal-to-epithelial transition (MET). However, the MET cascade has not been recapitulated in vivo, and the cellular and molecular regulators that promote MET remain unknown. In a recent report, using a model of spontaneous breast cancer, we have shown that bone marrow-derived myeloid progenitor cells in the premetastatic lung secrete the proteoglycan versican, which induces MET of metastatic tumor cells and accelerates metastases. This review summarizes recent progress in MET research, outlines a unique paracrine cross-talk between the microenvironment and the cancer cells, which promotes tumor outgrowth in the metastatic organ, and discusses opportunities for novel antimetastatic approaches for cancer therapy.

Loss of microRNA-200a and c, and microRNA-203 expression at the invasive front of primary cutaneous melanoma is associated with increased thickness and disease progression

Loss of E-cadherin expression in melanoma correlates with increased tumor thickness and reduced disease-free survival. The molecular mechanisms underpinning its differential expression in melanoma tissue remain elusive. MicroRNAs (miRNAs) have been implicated in tumor progression and regulation of E-cadherin expression. Here, we demonstrate a significant correlation between tumor thickness and loss of expression of miR-200a, miR-200c, and miR-203 in a series of 23 frozen primary melanomas, where it was confirmed in two subsequent validation series (series 1: six nevi, 15 primary melanomas, and 16 metastases; series 2: 11 matched pairs of primary melanomas and metastases). Decreased levels of miR-200a, miR-200c, and miR-203 correlated with increasing thickness in the combined validation series (P = 0.024, 0.033, and 0.031, respectively). In addition, progressive loss of miR-200a expression with disease progression was observed in series 1 (P < 0.001) and in series 2 (P = 0.029). MiR-200 in situ hybridization and E-cadherin immunohistochemistry demonstrated reduced expression of both at the deep invasive margin of the tumor. Furthermore, a functional validation study using an anti-miR200 strategy demonstrated that loss of miR-200 expression in melanoma cell lines reduced E-cadherin expression. Collectively, our data point towards an important role for miR-200 and miR203 expression in regulating E-cadherin during melanoma progression.

Death inducer-obliterator 1 (Dido1) is a BMP target gene and promotes BMP-induced melanoma progression

Bone morphogenetic proteins (BMPs) are known to play an important role in melanoma development and progression. However, the downstream targets of BMPs have not been investigated thus far. Therefore, we treated melanoma cell lines with the Smad-specific BMP inhibitor Dorsomorphin and performed a cDNA microarray. We identified death inducer-obliterator 1 (Dido1) as a BMP-specific Smad-regulated target gene, which was confirmed by qRT-PCR, immunofluorescence staining and electrophoretic mobility shift assay experiments. An analysis of Dido1 expression revealed an upregulation of Dido1 levels in melanoma cell lines and tissues compared with normal melanocytes. Colony-formation assays showed that siDido1-transfected cells formed significantly smaller colonies when grown in soft agar compared with control cells. In addition, fluorescence-activated cell sorting and western blot experiments revealed that transfection of melanoma cells with Dido1 small interfering RNAs led to an upregulation of apoptosis. Furthermore, cell migratory and invasive potentials were strongly reduced in siDido1-transfected cells compared with control cells. Finally, we demonstrated that Dido1 induces the expression of Integrin αV, thereby promoting the attachment, migration, invasion and apoptosis resistance of melanoma cells.

Progesterone receptor activates Msx2 expression by downregulating TNAP/Akp2 and activating the Bmp pathway in EpH4 mouse mammary epithelial cells

Previously we demonstrated that EpH4 mouse mammary epithelial cells induced the homeobox transcription factor Msx2 either when transfected with the progesterone receptor (PR) or when treated with Bmp2/4. Msx2 upregulation was unaffected by Wnt inhibitors s-FRP or Dkk1, but was inhibited by the Bmp antagonist Noggin. We therefore hypothesized that PR signaling to Msx2 acts through the Bmp receptor pathway. Herein, we confirm that transcripts for Alk2/ActR1A, a non-canonical BmpR Type I, are upregulated in mammary epithelial cells overexpressing PR (EpH4-PR). Increased phosphorylation of Smads 1,5, 8, known substrates for Alk2 and other BmpR Type I proteins, was observed as was their translocation to the nucleus in EpH4-PR cells. Analysis also showed that Tissue Non-Specific Alkaline Phosphatase (TNAP/Akp2) was also found to be downregulated in EpH4-PR cells. When an Akp2 promoter-reporter construct containing a ½PRE site was transfected into EpH4-PR cells, its expression was downregulated. Moreover, siRNA mediated knockdown of Akp2 increased both Alk2 and Msx2 expression. Collectively these data suggest that PR inhibition of Akp2 results in increased Alk2 activity, increased phosphorylation of Smads 1,5,8, and ultimately upregulation of Msx2. These studies imply that re-activation of the Akp2 gene could be helpful in downregulating aberrant Msx2 expression in PR+ breast cancers.

Augmented autocrine bone morphogenic protein (BMP) 7 signaling increases the metastatic potential of mouse breast cancer cells

As malignant breast cancers progress, they acquire the ability to spread to other regions of the body, including bone and lung, but the molecular mechanism underlying the increase in metastatic potential is not fully understood. Here we studied murine 4T1E/M3 highly bone marrow metastatic breast cancer cells, which we established previously. These cells show upregulated expression of bone morphogenetic protein (BMP) 7 and BMP receptors, as well as augmented phosphorylation of Smad1/5/8. Both anchorage-independent cell growth measured in colony forming assays and cell migration measured in wound healing assays were suppressed in 4T1E/M3 cells following treatment with a neutralizing anti-BMP7 antibody or knockdown of BMP7 gene expression. In addition, metastasis of 4T1E/M3 cells to the spine and lung and intracellular levels of phosphorylated Smad1/5/8 were suppressed by knocking down BMP7. Conversely, overexpression of BMP7 in the weakly metastatic parental 4T1E cells augmented their anchorage-independent growth, migration and metastasis to spine and lung. Taken together, our results strongly suggest that augmented autocrine BMP7 signaling leads to increases in the anchorage-independent cell growth, migration and metastatic potential in our bone marrow metastatic breast cancer model.

Downregulation of hemojuvelin prevents inhibitory effects of bone morphogenetic proteins on iron metabolism in hepatocellular carcinoma

Recently, we revealed that bone morphogenetic protein (BMP) 4 is increased in hepatocellular carcinoma (HCC). Furthermore, latest reports described BMPs, in particular BMP6, as important regulators of hepcidin expression in iron homeostasis. Therefore, we aimed to unravel why enhanced BMP expression in HCC patients does not lead to severe changes in iron metabolism. Initial analysis of the BMP4 and BMP6 expression patterns revealed enhanced expression on mRNA and protein level in HCC cell lines and tissue samples compared with primary human hepatocytes (PHHs) and normal liver tissues. However and interestingly, hepcidin expression was reduced in HCC cell lines and tissues. Analysis of BMP6 receptor expression revealed loss of BMP6-specific receptor subunit in HCC. To identify a possible regulatory mechanism causing lack of reaction to BMP4 we analyzed the expression of hemojuvelin (HJV), which is involved in iron metabolism as BMP co-receptor. HJV expression was markedly decreased in HCC cell lines and tissues. HJV promoter analysis revealed potential HNF-1α and snail-binding sites, but functional analysis ruled out that these transcriptional regulators or promoter methylation are the cause of HJV downregulation in HCC. However, we identified AU-rich elements in the HJV 3'-untranslated region and revealed significantly faster decay of HJV mRNA in HCC cells as compared with PHH indicating decreased mRNA-stability as the reason for the loss of HJV expression in HCC.

BMP4 signaling directs primitive endoderm-derived XEN cells to an extraembryonic visceral endoderm identity

The visceral endoderm (VE) is an epithelial tissue in the early postimplantation mouse embryo that encapsulates the pluripotent epiblast distally and the extraembryonic ectoderm proximally. In addition to facilitating nutrient exchange before the establishment of a circulation, the VE is critical for patterning the epiblast. Since VE is derived from the primitive endoderm (PrE) of the blastocyst, and PrE-derived eXtraembryonic ENdoderm (XEN) cells can be propagated in vitro, XEN cells should provide an important tool for identifying factors that direct VE differentiation. In this study, we demonstrated that BMP4 signaling induces the formation of a polarized epithelium in XEN cells. This morphological transition was reversible, and was associated with the acquisition of a molecular signature comparable to extraembryonic (ex) VE. Resembling exVE which will form the endoderm of the visceral yolk sac, BMP4-treated XEN cells regulated hematopoiesis by stimulating the expansion of primitive erythroid progenitors. We also observed that LIF exerted an antagonistic effect on BMP4-induced XEN cell differentiation, thereby impacting the extrinsic conditions used for the isolation and maintenance of XEN cells in an undifferentiated state. Taken together, our data suggest that XEN cells can be differentiated towards an exVE identity upon BMP4 stimulation and therefore represent a valuable tool for investigating PrE lineage differentiation.

Mechanism of the mesenchymal-epithelial transition and its relationship with metastatic tumor formation

Cancer metastasis consists of a sequential series of events, and the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are recognized as critical events for metastasis of carcinomas. A current area of focus is the histopathological similarity between primary and metastatic tumors, and MET at sites of metastases has been postulated to be part of the process of metastatic tumor formation. Here, we summarize accumulating evidence from experimental studies that directly supports the role of MET in cancer metastasis, and we analyze the main mechanisms that regulate MET or reverse EMT in carcinomas. Given the critical role of MET in metastatic tumor formation, the potential to effectively target the MET process at sites of metastasis offers new hope for inhibiting metastatic tumor formation.

Appropriate Bmp7 levels are required for the differentiation of midline guidepost cells involved in corpus callosum formation

Guidepost cells are essential structures for the establishment of major axonal tracts. How these structures are specified and acquire their axon guidance properties is still poorly understood. Here, we show that in mouse embryos appropriate levels of Bone Morphogenetic Protein 7 (Bmp7), a member of the TGF-β superfamily of secreted proteins, are required for the correct development of the glial wedge, the indusium griseum, and the subcallosal sling, three groups of cells that act as guidepost cells for growing callosal axons. Bmp7 is expressed in the region occupied by these structures and its genetic inactivation in mouse embryos caused a marked reduction and disorganization of these cell populations. On the contrary, infusion of recombinant Bmp7 in the developing forebrain induced their premature differentiation. In both cases, changes were associated with the disruption of callosal axon growth and, in most animals fibers did not cross the midline forming typical Probst bundles. Addition of Bmp7 to cortical explants did not modify the extent of their outgrowth nor their directionality, when explants were exposed to a focalized source of the protein. Together, these results indicate that Bmp7 is indirectly required for corpus callosum formation by controlling the timely differentiation of its guidepost cells.

The aldehyde dehydrogenase enzyme 7A1 is functionally involved in prostate cancer bone metastasis

High aldehyde dehydrogenase (ALDH) activity can be used to identify tumor-initiating and metastasis-initiating cells in various human carcinomas, including prostate cancer. To date, the functional importance of ALDH enzymes in prostate carcinogenesis, progression and metastasis has remained elusive. Previously we identified strong expression of ALDH7A1 in human prostate cancer cell lines, primary tumors and matched bone metastases. In this study, we evaluated whether ALDH7A1 is required for the acquisition of a metastatic stem/progenitor cell phenotype in human prostate cancer. Knockdown of ALDH7A1 expression resulted in a decrease of the α2^hi/αv^hi/CD44⁺ stem/progenitor cell subpopulation in the human prostate cancer cell line PC-3M-Pro4. In addition, ALDH7A1 knockdown significantly inhibited the clonogenic and migratory ability of human prostate cancer cells in vitro. Furthermore, a number of genes/factors involved in migration, invasion and metastasis were affected including transcription factors (snail, snail2, and twist) and osteopontin, an ECM molecule involved in metastasis. Knockdown of ALDH7A1 resulted in decreased intra-bone growth and inhibited experimentally induced (bone) metastasis, while intra-prostatic growth was not affected. In line with these observations, evidence is presented that TGF-β, a key player in cancer invasiveness and bone metastasis, strongly induced ALDH activity while BMP7 (an antagonist of TGF-β signaling) down-regulated ALDH activity. Our findings show, for the first time, that the ALDH7A1 enzyme is functionally involved in the formation of bone metastases and that the effect appeared dependent on the microenvironment, i.e., bone versus prostate.

Melanoma stem cells: not rare, but well done

Since the identification of self-renewing cells in the hematopoietic system, stem cells have transformed the study of medicine. Cancer biologists have identified stem-like cells in multiple malignancies, including those of solid organs. This has led to the development of a stem cell theory of cancer, which purports that a subpopulation of self-renewing tumor cells is responsible for tumorigenesis. This contrasts with the stochastic model of tumor development, which advances that all tumor cells are capable of tumor formation. Within the field of melanoma, the identity and existence of cancer stem cells has been the subject of recent debate. Much of the controversy may be traced to differences in interpretations and definitions related to the cancer stem cell theory, and the use of dissimilar methodologies to study melanoma cells. Accumulating evidence suggests that cancer stem cells may exist in melanoma, although their frequency may vary and they may be capable of phenotypic plasticity. Importantly, these primitive melanoma cells are not only capable of self-renewal and differentiation plasticity, but also may confer virulence via immune evasion and multidrug resistance, and potentially via vasculogenic mimicry and transition to migratory and metastasizing derivatives. Therapeutic targeting of melanoma stem cells and the pathways that endow them with virulence hold promise for the design of more effective strategies for amelioration and eradication of this most lethal form of skin cancer.