Emerging roles of the bone morphogenetic protein pathway in cancer: potential therapeutic target for kinase inhibition

Genome-wide identification, evolution, and expression analysis of the bone morphogenetic protein gene family in Myxocyprinus asiaticus

Bone morphogenetic proteins (BMPs) are important growth factors belonging to the TGF-β superfamily. These factors not only play a vital role in skeleton formation in young fish but also regulate the morphological development of M. asiaticus, with Group II genes regulating morphology mainly during the juvenile stage. This study investigated how BMP genes regulate Myxocyprinus asiaticus development and function and explored the role of the BMP family in fish morphological development. In this study, 43 BMPs were identified and classified into five groups: BMP1/3/11/15 (Group I), BMP12/13/14 (Group II), BMP2/4/16 (Group III), BMP9/10 (Group IV), and BMP5/6/7/8 (Group V). Analyses of the gene structures and conserved motifs revealed the conservation of the BMP gene family in M. asiaticus. In M. asiaticus, gene fragmentation, duplication, and 4R whole-genome duplication events contributed to BMP gene family expansion. Furthermore, expression pattern analysis and qRT-PCR revealed that changes in M. asiaticus BMP gene expression during different developmental stages were due to body size alterations, highlighting the major impact of the BMP gene on body size variation in this species. Our study provides fundamental data for investigating the morphological development of M. asiaticus and lays the framework for understanding the genetic mechanisms of body size variation in scleractinian fishes, with potential applications in the artificial breeding and conservation of M. asiaticus.

Elucidation of Factors Affecting the Age-Dependent Cancer Occurrence Rates

Cancer occurrence rates exhibit diverse age-related patterns, and understanding them may shed new and important light on the drivers of cancer evolution. This study systematically analyzes the age-dependent occurrence rates of 23 carcinoma types, focusing on their age-dependent distribution patterns, the determinants of peak occurrence ages, and the significant difference between the two genders. According to the SEER reports, these cancer types have two types of age-dependent occurrence rate (ADOR) distributions, with most having a unimodal distribution and a few having a bimodal distribution. Our modeling analyses have revealed that (1) the first type can be naturally and simply explained using two age-dependent parameters: the total number of stem cell divisions in an organ from birth to the current age and the availability levels of bloodborne growth factors specifically needed by the cancer (sub)type, and (2) for the second type, the first peak is due to viral infection, while the second peak can be explained as in (1) for each cancer type. Further analyses indicate that (i) the iron level in an organ makes the difference between the male and female cancer occurrence rates, and (ii) the levels of sex hormones are the key determinants in the onset age of multiple cancer types. This analysis deepens our understanding of the dynamics of cancer evolution shared by diverse cancer types and provides new insights that are useful for cancer prevention and therapeutic strategies, thereby addressing critical gaps in the current paradigm of oncological research.

Targeting BMP2 for therapeutic strategies against hepatocellular carcinoma

OBJECTIVES

This study aimed to investigate the role of BMP2 in hepatocellular carcinoma (HCC) growth and metastasis using a dual approach combining single-cell RNA sequencing (scRNA-seq) and bulk RNA-seq.

METHODS

scRNA-seq data from the GEO database and bulk RNA-seq data from the TCGA database were analyzed. Differentially expressed marker genes of endothelial cells were identified and analyzed using enrichment analysis, PPI analysis, correlation analysis, and GSEA. In vitro, experiments were conducted using the Huh-7 HCC cell line, and in vivo, models of HCC growth and metastasis were established by knocking down BMP2.

RESULTS

The scRNA-seq analysis identified BMP2 as a key marker gene in endothelial cells of HCC samples. Elevated BMP2 expression correlated with poor prognosis in HCC. In vitro experiments showed that silencing BMP2 inhibited the proliferation, migration, and invasion of liver cancer cells. In vivo studies confirmed increased BMP2 expression in HCC tissues, promoting angiogenesis and HCC growth.

CONCLUSION

This study highlights the role of BMP2 in tumor angiogenesis and HCC progression. Targeting BMP2 could be a promising therapeutic strategy against HCC.

Macrocyclization strategy for improving candidate profiles in medicinal chemistry

Macrocycles are defined as cyclic compounds with 12 or more members. In medicinal chemistry, they are categorized based on their core chemistry into cyclic peptides and macrocycles. Macrocycles are advantageous because of their structural diversity and ability to achieve high affinity and selectivity towards challenging targets that are often not addressable by conventional small molecules. The potential of macrocyclization to optimize drug-like properties while maintaining adequate bioavailability and permeability has been emphasized as a key innovation in medicinal chemistry. This review provides a detailed case study of the application of macrocyclization over the past 5 years, starting from the initial analysis of acyclic active compounds to optimization of the resulting macrocycles for improved efficacy and drug-like properties. Additionally, it illustrates the strategic value of macrocyclization in contemporary drug discovery efforts.

Inhibition of the bone morphogenetic protein pathway suppresses tumor growth through downregulation of epidermal growth factor receptor in MEK/ERK-dependent colorectal cancer

The bone morphogenetic protein (BMP) pathway promotes differentiation and induces apoptosis in normal colorectal epithelial cells. However, its role in colorectal cancer (CRC) is controversial, where it can act as context-dependent tumor promoter or tumor suppressor. Here we have found that CRC cells reside in a BMP-rich environment based on curation of two publicly available RNA-sequencing databases. Suppression of BMP using a specific BMP inhibitor, LDN193189, suppresses the growth of select CRC organoids. Colorectal cancer organoids treated with LDN193189 showed a decrease in epidermal growth factor receptor, which was mediated by protein degradation induced by leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) expression. Among 18 molecularly characterized CRC organoids, suppression of growth by BMP inhibition correlated with induction of LRIG1 gene expression. Notably, knockdown of LRIG1 in organoids diminished the growth-suppressive effect of LDN193189. Furthermore, in CRC organoids, which are susceptible to growth suppression by LDN193189, simultaneous treatment with LDN193189 and trametinib, an FDA-approved MEK inhibitor, resulted in cooperative growth inhibition both in vitro and in vivo. Taken together, the simultaneous inhibition of BMP and MEK could be a novel treatment option in CRC cases, and evaluating in vitro growth suppression and LRIG1 induction by BMP inhibition using patient-derived organoids could offer functional biomarkers for predicting potential responders to this regimen.

CRISPR-Cas9 Library Screening Identifies Novel Molecular Vulnerabilities in KMT2A-Rearranged Acute Lymphoblastic Leukemia

In acute lymphoblastic leukemia (ALL), chromosomal translocations involving the KMT2A gene represent highly unfavorable prognostic factors and most commonly occur in patients less than 1 year of age. Rearrangements of the KMT2A gene drive epigenetic changes that lead to aberrant gene expression profiles that strongly favor leukemia development. Apart from this genetic lesion, the mutational landscape of KMT2A-rearranged ALL is remarkably silent, providing limited insights for the development of targeted therapy. Consequently, identifying potential therapeutic targets often relies on differential gene expression, yet the inhibition of these genes has rarely translated into successful therapeutic strategies. Therefore, we performed CRISPR-Cas9 knock-out screens to search for genetic dependencies in KMT2A-rearranged ALL. We utilized small-guide RNA libraries directed against the entire human epigenome and kinome in various KMT2A-rearranged ALL, as well as wild-type KMT2A ALL cell line models. This screening approach led to the discovery of the epigenetic regulators ARID4B and MBD3, as well as the receptor kinase BMPR2 as novel molecular vulnerabilities and attractive therapeutic targets in KMT2A-rearranged ALL.

Design and Synthesis of Pyrazole-Based Macrocyclic Kinase Inhibitors Targeting BMPR2

Bone morphogenetic protein (BMP) signaling is mediated by transmembrane protein kinases that form heterotetramers consisting of type-I and type-II receptors. Upon BMP binding, the constitutively active type-II receptors activate specific type-I receptors by transphosphorylation, resulting in the phosphorylation of SMAD effector proteins. Drug discovery in the receptor tyrosine kinase-like (TKL) family has largely focused on type-I receptors, with few inhibitors that have been published targeting type-II receptors. BMPR2 is involved in several diseases, most notably pulmonary arterial hypertension, but also contributes to Alzheimer's disease and cancer. Here, we report that macrocyclization of the promiscuous inhibitor 1, based on a 3-amino-1H-pyrazole hinge binding moiety, led to a selective and potent BMPR2 inhibitor 8a.

Bone morphogenetic protein pathway responses and alterations of osteogenesis in metastatic prostate cancers

BACKGROUND

Prostate cancer is a common cancer in men that annually results in more than 33 000 US deaths. Mortality from prostate cancer is largely from metastatic disease, reflecting on the great strides in the last century of treatments in care for the localized disease. Metastatic castrate resistant prostate cancer (mCRPC) will commonly travel to the bone, creating unique bone pathology that requires nuanced treatments in those sites with surgical, radio and chemotherapeutic interventions. The bone morphogenetic protein (BMP) pathway has been historically studied in the capacity to regulate the osteogenic nature of new bone. New mineralized bone generation is a frequent and common observation in mCRPC and referred to as blastic bone lesions. Less common are bone destructive lesions that are termed lytic.

METHODS

We queried the cancer genome atlas (TCGA) prostate cancer databases for the expression of the BMP pathway and found that distinct gene expression of the ligands, soluble antagonists, receptors, and intracellular mediators were altered in localized versus metastatic disease. Human prostate cancer cell lines have an innate ability to promote blastic- or lytic-like bone lesions and we hypothesized that inhibiting BMP signaling in these cell lines would result in a distinct change in osteogenesis gene expression with BMP inhibition.

RESULTS

We found unique and common changes by comparing these cell lines response and unique BMP pathway alterations. We treated human PCa cell lines with distinct bone pathologic phenotypes with the BMP inhibitor DMH1 and found distinct osteogenesis responses. We analyzed distinct sites of metastatic PCa in the TCGA and found that BMP signaling was selectively altered in commons sites such as lymph node, bone and liver compared to primary tumors.

CONCLUSIONS

Overall we conclude that BMPs in metastatic prostate cancer are important signals and functional mediators of diverse processes that have potential for individualized precision oncology in mCRPC.

Bone morphogenetic proteins, activins, and growth and differentiation factors in tumor immunology and immunotherapy resistance

The TGF-β superfamily is a group of secreted polypeptides with key roles in exerting and regulating a variety of physiologic effects, especially those related to cell signaling, growth, development, and differentiation. Although its central member, TGF-β, has been extensively reviewed, other members of the family-namely bone morphogenetic proteins (BMPs), activins, and growth and differentiation factors (GDFs)-have not been as thoroughly investigated. Moreover, although the specific roles of TGF-β signaling in cancer immunology and immunotherapy resistance have been extensively reported, little is known of the roles of BMPs, activins, and GDFs in these domains. This review focuses on how these superfamily members influence key immune cells in cancer progression and resistance to treatment.

The Roles of Tumor-Associated Macrophages in Prostate Cancer

The morbidity of prostate cancer (PCa) is rising year by year, and it has become the primary cause of tumor-related mortality in males. It is widely accepted that macrophages account for 50% of the tumor mass in solid tumors and have emerged as a crucial participator in multiple stages of PCa, with the huge potential for further treatment. Oftentimes, tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) behave like M2-like phenotypes that modulate malignant hallmarks of tumor lesions, ranging from tumorigenesis to metastasis. Several clinical studies indicated that mean TAM density was higher in human PCa cores versus benign prostatic hyperplasia (BPH), and increased biopsy TAM density potentially predicts worse clinicopathological characteristics as well. Therefore, TAM represents a promising target for therapeutic intervention either alone or in combination with other strategies to halt the “vicious cycle,” thus improving oncological outcomes. Herein, we mainly focus on the fundamental aspects of TAMs in prostate adenocarcinoma, while reviewing the mechanisms responsible for macrophage recruitment and polarization, which has clinical translational implications for the exploitation of potentially effective therapies against TAMs.

Hematopoietic Stem and Progenitor Cells (HSPCs) and Hematopoietic Microenvironment: Molecular and Bioinformatic Studies of the Zebrafish Models

Hematopoietic stem cells (HSCs) reside in a specialized microenvironment in a peculiar anatomic location which regulates the maintenance of stem cells and controls its functions. Recent scientific progress in experimental technologies have enabled the specific detection of epigenetic factors responsible for the maintenance and quiescence of the hematopoietic niche, which has improved our knowledge of regulatory mechanisms. The aberrant role of RNA-binding proteins and their impact on the disruption of stem cell biology have been reported by a number of recent studies. Despite recent modernization in hematopoietic microenvironment research avenues, our comprehension of the signaling mechanisms and interactive pathways responsible for integration of the hematopoietic niche is still limited. In the past few decades, zebrafish usage with regards to exploratory studies of the hematopoietic niche has expanded our knowledge for deeper understanding of novel cellular interactions. This review provides an update on the functional roles of different genetic and epigenetic factors and molecular signaling events at different sections of the hematopoietic microenvironment. The explorations of different molecular approaches and interventions of latest web-based tools being used are also outlined. This will help us to get more mechanistic insights and develop therapeutic options for the malignancies.

Bone morphogenetic protein inhibitors and mitochondria targeting agents synergistically induce apoptosis-inducing factor (AIF) caspase-independent cell death in lung cancer cells

BACKGROUND

Bone morphogenetic proteins (BMP) are evolutionarily conserved morphogens that are reactivated in lung carcinomas. In lung cancer cells, BMP signaling suppresses AMP activated kinase (AMPK) by inhibiting LKB1. AMPK is activated by mitochondrial stress that inhibits ATP production, which is enhanced 100-fold when phosphorylated by LKB1. Activated AMPK can promote survival of cancer cells but its "hyperactivation" induces cell death. The studies here reveal novel cell death mechanisms induced by BMP inhibitors, together with agents targeting the mitochondria, which involves the "hyperactivation" of AMPK.

METHODS

This study examines the synergistic effects of two BMP inhibitors together with mitochondrial targeting agents phenformin and Ym155, on cell death of lung cancer cells expressing LKB1 (H1299), LKB1 null (A549), and A549 cells transfected with LKB1 (A549-LKB1). Cell death mechanisms evaluated were the activation of caspases and the nuclear localization of apoptosis inducing factor (AIF). A769662 was used to allosterically activate AMPK. Knockdown of BMPR2 and LKB1 using siRNA was used to examine their effects on nuclear localization of AMPK. Validation studies were performed on five passage zero primary NSCLC.

RESULTS

Both BMP inhibitors synergistically suppressed growth when combined with Ym155 or phenformin in cells expressing LKB1. The combination of BMP inhibitors with mitochondrial targeting agents enhanced the activation of AMPK in lung cancer cells expressing LKB1. Allosteric activation of AMPK with A769662 induced cell death in both H1299 and A549 cells. Cell death induced by the combination of BMP inhibitors and mitochondrial-targeting agents did not activate caspases. The combination of drugs induced nuclear localization of AIF in cells expressing LKB1, which was attenuated by knockdown of LKB1. Knockdown of BMPR2 together with Ym155 increased nuclear localization of AIF. Combination therapy also enhanced cell death and AIF nuclear localization in primary NSCLC.

CONCLUSIONS

These studies demonstrate that inhibition of BMP signaling together with mitochondrial targeting agents induce AIF caspase-independent cell death, which involves the "hyperactivation" of AMPK. AIF caspase-independent cell death is an evolutionarily conserved cell death pathway that is infrequently studied in cancer. These studies provide novel insight into mechanisms inducing AIF caspase-independent cell death in cancer cells using BMP inhibitors. Video Abstract.

Bone morphogenetic protein signaling regulation of AMPK and PI3K in lung cancer cells and C. elegans

BACKGROUND

Bone morphogenetic protein (BMP) is a phylogenetically conserved signaling pathway required for development that is aberrantly expressed in several age-related diseases including cancer, Alzheimer's disease, obesity, and cardiovascular disease. Aberrant BMP signaling in mice leads to obesity, suggesting it may alter normal metabolism. The role of BMP signaling regulating cancer metabolism is not known.

METHODS

To examine BMP regulation of metabolism, C. elegans harboring BMP gain-of-function (gof) and loss-of-function (lof) mutations were examined for changes in activity of catabolic and anabolic metabolism utilizing Western blot analysis and fluorescent reporters. AMP activated kinase (AMPK) gof and lof mutants were used to examine AMPK regulation of BMP signaling. H1299 (LKB1 wild-type), A549 (LKB1 lof), and A549-LKB1 (LKB1 restored) lung cancer cell lines were used to study BMP regulation of catabolic and anabolic metabolism. Studies were done using recombinant BMP ligands to activate BMP signaling, and BMP receptor specific inhibitors and siRNA to inhibit signaling.

RESULTS

BMP signaling in both C. elegans and cancer cells is responsive to nutrient conditions. In both C. elegans and lung cancer cell lines BMP suppressed AMPK, the master regulator of catabolism, while activating PI3K, a regulator of anabolism. In lung cancer cells, inhibition of BMP signaling by siRNA or small molecules increased AMPK activity, and this increase was mediated by activation of LKB1. BMP2 ligand suppressed AMPK activation during starvation. BMP2 ligand decreased expression of TCA cycle intermediates and non-essential amino acids in H1299 cells. Furthermore, we show that BMP activation of PI3K is mediated through BMP type II receptor. We also observed feedback signaling, as AMPK suppressed BMP signaling, whereas PI3K increased BMP signaling.

CONCLUSION

These studies show that BMP signaling suppresses catabolic metabolism and stimulates anabolic metabolism. We identified feedback mechanisms where catabolic induced signaling mediated by AMPK negatively regulates BMP signaling, whereas anabolic signaling produces a positive feedback regulation of BMP signing through Akt. These mechanisms were conserved in both lung cancer cells and C. elegans. These studies suggest that aberrant BMP signaling causes dysregulation of metabolism that is a potential mechanism by which BMP promotes survival of cancer cells.

Differential bioactivity of four BMP-family members as function of biomaterial stiffness

While a soft film itself is not able to induce cell spreading, BMP-2 presented via such soft film (so called "matrix-bound BMP-2") was previously shown to trigger cell spreading, migration and downstream BMP-2 signaling. Here, we used thin films of controlled stiffness presenting matrix-bound BMPs to study the effect of four BMP members (BMP-2, 4, 7, 9) on cell adhesion and differentiation of skeletal progenitors. We performed automated high-content screening of cellular responses, including cell number, cell spreading area, SMAD phosphorylation and alkaline phosphatase activity. We revealed that the cell response to bBMPs is BMP-type specific, and involved certain BMP receptors and beta chain integrins. In addition, this response is stiffness-dependent for several receptors. The basolateral presentation of the BMPs allowed us to discriminate the specificity of cellular response, especiallyd the role of type I and II BMP receptors and of β integrins in a BMP-type and stiffness-dependent manner. Notably, BMP-2 and BMP-4 were found to have distinct roles, while ALK5, previously known as a TGF-β receptor was revealed to be involved in the BMP-pathway.

The Diverse Applications of Pancreatic Ductal Adenocarcinoma Organoids

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies. While immortalized cancer cell lines and genetically engineered murine models have increased our understanding of PDAC tumorigenesis, they do not recapitulate inter- and intra-patient heterogeneity. PDAC patient derived organoid (PDO) biobanks have overcome this hurdle, and provide an opportunity for the high throughput screening of potential new therapies. This review provides a summary of the PDAC PDO biobanks established to date, and discusses how they have advanced our understanding of PDAC biology. Looking forward, the development of coculturing techniques for specific immune or stromal cell populations will enable a better understanding of the crosstalk that occurs within the tumor microenvironment, and the impact of this crosstalk on treatment response.

BMP4 enhances anoikis resistance and chemoresistance of breast cancer cells through canonical BMP signaling

Bone morphogenetic proteins (BMPs) regulate cell fate during development and mediate cancer progression. In this study, we investigated the role of BMP4 in proliferation, anoikis resistance, metastatic migration, and drug resistance of breast cancer cells. We utilized breast cancer cell lines and clinical samples representing different subtypes to understand the functional effect of BMP4 on breast cancer. The BMP pathway was inhibited with the small molecule inhibitor LDN193189 hydrochloride (LDN). BMP4 signaling enhanced the expression of stem cell genes CD44, ALDH1A3, anti-apoptotic gene BCL2 and promoted anoikis resistance in MDA-MB-231 breast cancer cells. BMP4 enhanced self-renewal and chemoresistance in MDA-MB-231 by upregulating Notch signaling while LDN treatment abrogated anoikis resistance and proliferation of anoikis resistant breast cancer cells in the osteogenic microenvironment. Conversely, BMP4 downregulated proliferation, colony-forming ability, and suppressed anoikis resistance in MCF7 and SkBR3 cells, while LDN treatment promoted tumor spheroid formation and growth. These findings indicate that BMP4 has a context-dependent role in breast cancer. Further, our data with MDA-MB-231 cells representing triple-negative breast cancer suggest that BMP inhibition might impair its metastatic spread and colonization.

Mir-106b Cluster Regulates Primordial Germ Cells Differentiation from Human Mesenchymal Stem Cells

Objective

Numerous evidence indicates that microRNAs (miRNAs) are critical regulators in the spermatogenesis process. The aim of this study was to investigate Mir-106b cluster regulates primordial germ cells (PGCs) differentiation from human mesenchymal stem cells (MSCs).

Materials and Methods

In this experimental study, samples containing male adipose (n: 9 samples- age: 25-40 years) were obtained from cosmetic surgeries performed for the liposuction in Imam Khomeini Hospital. The differentiation of MSCs into PGCs was accomplished by transfection of a lentivector expressing miR-106b. The transfection of miR- 106b was also confirmed by the detection of a clear green fluorescent protein (GFP) signal in MSCs. MSCs were treated with bone morphogenic factor 4 (BMP4) protein, as a putative inducer of PGCs differentiation, to induce the differentiation of MSCs into PGCs (positive control). After 4 days of transfection, the expression of miR-106b, STELLA, and FRAGILIS genes was evaluated by real-time polymerase chain reaction (PCR). Also, the levels of thymocyte differentiation antigen 1 (Thy1) protein was assessed by the western blot analysis. The cell surface expression of CD90 was also determined by immunocytochemistry method. The cytotoxicity of miR-106b was examined in MSCs after 24, 48, and 72 hours using the MTT assay.

Results

MSCs treated with BMP4 or transfected by miR-106b were successfully differentiated into PGCs. The results of this study also showed that the expression of miR-106b was significantly increased after 48 hours from transfection. Also, we showed STELLA, FARGILIS, as well as the protein expression of Thy1, was significantly higher in MSCs transfected by lentivector expressing miR-106b in comparison with MSCs treated with BMP4 (P≤0.05). MTT assay showed miR-106b was no toxic during 72 hours in 1 µg/ml dose, that this amount could elevated germ cells marker significantly higher than other experimental groups (P≤0.05).

Conclusion

According to this findings, it appears that miR-106b plays an essential role in the differentiation of MSCs into PGCs.

Mini review: The FDA-approved prescription drugs that target the MAPK signaling pathway in women with breast cancer

Breast cancer (BC) is the most common cancer and the prevalent type of malignancy among women. Multiple risk factors, including genetic changes, biological age, dense breast tissue, and obesity are associated with BC. The mitogen-activated protein kinases (MAPK) signaling pathway has a pivotal role in regulating biological functions such as cell proliferation, differentiation, apoptosis, and survival. It has become evident that the MAPK pathway is associated with tumorigenesis and may promote breast cancer development. The MAPK/RAS/RAF cascade is closely associated with breast cancer. RAS signaling can enhance BC cell growth and progression. B-Raf is an important kinase and a potent RAF isoform involved in breast tumor initiation and differentiation. Depending on the reasons for cancer, there are different strategies for treatment of women with BC. Till now, several FDA-approved treatments have been investigated that inhibit the MAPK pathway and reduce metastatic progression in breast cancer. The most common breast cancer drugs that regulate or inhibit the MAPK pathway may include Farnesyltransferase inhibitors (FTIs), Sorafenib, Vemurafenib, PLX8394, Dabrafenib, Ulixertinib, Simvastatin, Alisertib, and Teriflunomide. In this review, we will discuss the roles of the MAPK/RAS/RAF/MEK/ERK pathway in BC and summarize the FDA-approved prescription drugs that target the MAPK signaling pathway in women with BC.

High-throughput measurements of bone morphogenetic protein/bone morphogenetic protein receptor interactions using biolayer interferometry

Bone morphogenetic proteins (BMPs) are an important family of growth factors playing a role in a large number of physiological and pathological processes, including bone homeostasis, tissue regeneration, and cancers. In vivo, BMPs bind successively to both BMP receptors (BMPRs) of type I and type II, and a promiscuity has been reported. In this study, we used biolayer interferometry to perform parallel real-time biosensing and to deduce the kinetic parameters (ka, kd) and the equilibrium constant (KD) for a large range of BMP/BMPR combinations in similar experimental conditions. We selected four members of the BMP family (BMP-2, 4, 7, 9) known for their physiological relevance and studied their interactions with five type-I BMP receptors (ALK1, 2, 3, 5, 6) and three type-II BMP receptors (BMPR-II, ACTR-IIA, ACTR-IIB). We reveal that BMP-2 and BMP-4 behave differently, especially regarding their kinetic interactions and affinities with the type-II BMPR. We found that BMP-7 has a higher affinity for the type-II BMPR receptor ACTR-IIA and a tenfold lower affinity with the type-I receptors. While BMP-9 has a high and similar affinity for all type-II receptors, it can interact with ALK5 and ALK2, in addition to ALK1. Interestingly, we also found that all BMPs can interact with ALK5. The interaction between BMPs and both type-I and type-II receptors in a ternary complex did not reveal further cooperativity. Our work provides a synthetic view of the interactions of these BMPs with their receptors and paves the way for future studies on their cell-type and receptor specific signaling pathways.

MicroRNA-129-5p promotes proliferation and metastasis of hepatocellular carcinoma by regulating the BMP2 gene

Hepatocellular carcinoma (HCC) is a malignant tumor that poses a serious threat to human health. Due to its occult onset and rapid development, HCC is a challenge to diagnose early and effectively treat, and thus patients with HCC often have an unfavorable prognosis. MicroRNA (miR)-129 and its target gene play an important role in the regulation of various diseases. Therefore, the aim of the present study was to investigate the role and mechanism of action for miR-129-5p in the development of HCC. Quantitative results of clinical samples analyzed using reverse transcription-quantitative PCR suggested that miR-129-5p had a significantly lower expression level in tumoral tissues compared with corresponding peritumoral tissues. Overexpression of miR-129-5p in HCC cells was performed using a transfection technique, followed by MTT, Transwell, invasion and wound healing assays to detect the effect of miR-129-5p on the cell cytotoxicity and metastasis of liver cancer in vitro. The downstream target gene of miR-129-5p, bone morphogenetic protein 2 (BMP2), was determined using a luciferase reporter assay. Overexpression of miR-129-5p played a vital role in decreasing cytotoxicity and promoting metastasis of HCC, which may be attributed to its inhibitory effect on the expression of its target gene, BMP2. In clinical samples, miR-129-5p expression levels were found to be negatively correlated with BMP2 and closely associated with HCC metastasis and infiltration. Collectively, the results suggested that miR-129-5p may contribute to proliferation and metastasis of HCC through its target gene, BMP2, and thus may be a potential novel therapeutic target for the treatment of HCC.

BMP6 Regulates Corneal Epithelial Cell Stratification by Coordinating Their Proliferation and Differentiation and Is Upregulated in Pterygium

Purpose

Proper balance between cell proliferation and differentiation is essential for corneal epithelial (CE) stratification and homeostasis. Although bone morphogenetic protein-6 (BMP6) is known to be expressed in the CE for over 25 years, its function in this tissue remains unknown. Here, we test the hypothesis that BMP6 promotes CE cell stratification and homeostasis by regulating their proliferation and differentiation.

Methods

We employed postnatal day-12 (PN-12), PN-14, PN-20, and PN-90 mouse eyes; human corneal limbal epithelial (HCLE) cells; and ocular surface fibrovascular disease pterygium tissues to evaluate the role of BMP6 in CE proliferation, differentiation, and pathology by RT-qPCR, immunoblots, and/or immunofluorescent staining. Cell proliferation was quantified by immunostaining for Ki67.

Results

Coincident with the mouse CE stratification between PN-12 and PN-20, BMP6 was significantly upregulated and the BMP6 antagonist Noggin downregulated. Mature CE retained high BMP6 and low Noggin expression at PN-90. BMP6 and its receptors BMPR1A and BMPR2 were upregulated during in vitro stratification of HCLE cells. Consistent with its anti-proliferative role, exogenous BMP6 suppressed HCLE cell proliferation, downregulated cyclin-D1 and cyclin-D2, and upregulated cell-cycle inhibitors Krüppel-like factor 4 (KLF4) and p21. BMP6 also upregulated the desmosomal cadherins desmoplakin and desmoglein in HCLE cells, consistent with its pro-differentiation role. Human pterygium displayed significant upregulation of BMP6 coupled with downregulation of Noggin and cell-cycle suppressors KLF4 and p21.

Conclusions

BMP6 coordinates CE stratification and homeostasis by regulating their proliferation and differentiation. BMP6 is significantly upregulated in human pterygium concurrent with downregulation of Noggin, KLF4, and p21.

BMP-2 Variants in Breast Epithelial to Mesenchymal Transition and Microcalcifications Origin

This study aims to investigate the possible different roles of the BMP-2 variants, cytoplasmic and nuclear variant, in both epithelial to mesenchymal transition and in microcalcifications origin in human breast cancers. To this end, the in situ expression of cytoplasmic and nuclear BMP-2 was associated with the expression of the main epithelial to mesenchymal transition biomarkers (e-cadherin and vimentin) and molecules involved in bone metabolisms (RUNX2, RANKL, SDF-1) by immunohistochemistry. In addition, the expression of cytoplasmic and nuclear BMP-2 was associated with the presence of microcalcifications. Our data showed a significant association among the number of cytoplasmic BMP-2-positive cells and the number of both vimentin (positive association) and e-cadherin (negative association) positive breast cells. Conversely, no associations were found concerning the nuclear BMP-2-positive breast cells. Surprisingly, the opposite result was obtained by analyzing the variants of BMP-2 and both the expression of RANKL and SDF-1 and the presence of microcalcifications. Specifically, the presence of microcalcifications was related to the expression of nuclear BMP-2 variant rather than the cytoplasmic one, as well as a strong association between the number of nuclear BMP-2 and the expression of the main breast osteoblast-like cells (BOLCs) biomarkers. To further corroborate these data, an in vitro experiment for demonstrating the co-expression of nBMP-2 and RANKL or vimentin or SDF-1 in breast cancer cells that acquire the capability to produce microcalcifications was developed. These investigations confirmed the association between the nBMP-2 expression and both RANKL and SDF-1. The data supports the idea that whilst cytoplasmic BMP-2 can be involved in epithelial to mesenchymal transition phenomenon, the nuclear variant is related to the essential mechanisms for the formation of breast microcalcifications. In conclusion, from these experimental and translational perspectives, the complexity of BMP-2 signaling will require a detailed understanding of the involvement of specific BMP-2 variants in breast cancers.

Loss of Myeloid BMPR1a Alters Differentiation and Reduces Mouse Prostate Cancer Growth

The Bone Morphogenetic Protein (BMP) pathway is a member of the TGFβ signaling family and has complex roles in cancer. BMP signaling is rarely mutated and can be frequently overexpressed in many human cancers. The dichotomous role of BMPs as both tumor promoters and suppressors appears to be largely context based in both the cancer cell and the surrounding microenvironment. Myeloid cells including macrophages and neutrophils have been shown to be tumor promoting when stimulated from BMPs. We found that conditional deletion of BMPR1a in myeloid cells (LysMCre) restricts tumor progression in a syngeneic mouse prostate cancer model. Specific changes occurred in myeloid cells both in tumor bearing mice and tumor naïve mice throughout multiple tissues. We profiled myeloid subsets in the bone marrow, spleen and primary tumor and found myeloid BMPR1a loss altered the differentiation and lineage capability of distinct populations by histologic, flow cytometry and high dimensional mass cytometry analysis. We further confirmed the requirement for BMP signaling with pharmacologic inhibition of THP-1 and Raw264.7 activated into M2 macrophages with the BMP inhibitor DMH1. M2 polarized primary bone marrow derived cells from LysMCre BMPR1a knockout mice indicated a distinct requirement for BMP signaling in myeloid cells during M2 activation. These results indicate a unique necessity for BMP signaling in myeloid cells during tumor progression.

Bone marrow niche crosses paths with BMPs: a road to protection and persistence in CML

Chronic myeloid leukaemia (CML) is a paradigm of precision medicine, being one of the first cancers to be treated with targeted therapy. This has revolutionised CML therapy and patient outcome, with high survival rates. However, this now means an ever-increasing number of patients are living with the disease on life-long tyrosine kinase inhibitor (TKI) therapy, with most patients anticipated to have near normal life expectancy. Unfortunately, in a significant number of patients, TKIs are not curative. This low-level disease persistence suggests that despite a molecularly targeted therapeutic approach, there are BCR-ABL1-independent mechanisms exploited to sustain the survival of a small cell population of leukaemic stem cells (LSCs). In CML, LSCs display many features akin to haemopoietic stem cells, namely quiescence, self-renewal and the ability to produce mature progeny, this all occurs through intrinsic and extrinsic signals within the specialised microenvironment of the bone marrow (BM) niche. One important avenue of investigation in CML is how the disease highjacks the BM, thereby remodelling this microenvironment to create a niche, which enables LSC persistence and resistance to TKI treatment. In this review, we explore how changes in growth factor levels, in particular, the bone morphogenetic proteins (BMPs) and pro-inflammatory cytokines, impact on cell behaviour, extracellular matrix deposition and bone remodelling in CML. We also discuss the challenges in targeting LSCs and the potential of dual targeting using combination therapies against BMP receptors and BCR-ABL1.

Bidirectional tumor/stroma crosstalk promotes metastasis in mesenchymal colorectal cancer

Patients with the mesenchymal subtype colorectal cancer (CRC) have a poor prognosis, in particular patients with stroma-rich tumors and aberrant SMAD4 expression. We hypothesized that interactions between SMAD4-deficient CRC cells and cancer-associated fibroblasts provide a biological explanation. In transwell invasion assays, fibroblasts increased the invasive capacity of SMAD4-deficient HT29 CRC cells, but not isogenic SMAD4-proficient HT29 cells. A TGF-β/BMP-specific array showed BMP2 upregulation by fibroblasts upon stimulation with conditioned medium from SMAD4-deficient CRC cells, while also stimulating their invasion. In a mouse model for experimental liver metastasis, the co-injection of fibroblasts increased metastasis formation of SMAD4-deficient CRC cells (p = 0.02) but not that of SMAD4-proficient CRC cells. Significantly less metastases were seen in mice co-injected with BMP2 knocked-down fibroblasts. Fibroblast BMP2 expression seemed to be regulated by TRAIL, a factor overexpressed in SMAD4-deficient CRC cells. In a cohort of 146 stage III CRC patients, we showed that patients with a combination of high stromal BMP2 expression and the loss of tumor SMAD4 expression had a significantly poorer overall survival (HR 2.88, p = 0.04). Our results suggest the existence of a reciprocal loop in which TRAIL from SMAD4-deficient CRC cells induces BMP2 in fibroblasts, which enhances CRC invasiveness and metastasis.

The BMP antagonist, SOSTDC1, restrains gastric cancer progression via inactivation of c-Jun signaling

Gastric cancer is commonly diagnosed at an advanced stage when metastasis is almost inevitable. Despite numerous novel regulators have been identified in driving gastric cancer progression, much remains unclear due to the complex nature of cancer. Comparison of the transcriptome profiles of gastric primary tumor tissue, with its matched non-tumor and lymph node metastasis revealed frequent stepwise down-regulation of sclerostin domain containing 1 (SOSTDC1) related with tumor progression. Clinically, deficiency of this gene is associated with shortened survival of patients. Our results suggest that SOSTDC1 confers tumor-suppressive features in gastric cancer and silencing of it accelerates tumor growth and promotes the formation of lung metastasis. Although SOSTDC1 displayed limited inhibition of canonical SMAD-dependent bone morphogenetic proteins (BMP) pathway, it remarkably restrained the c-Jun activation and transcription of c-Jun downstream targets in the noncanonical BMP signaling pathway. Furthermore, c-Jun N-terminal kinase (JNK) blockage attenuated cell proliferative and migrative advantages of SOSTDC1 knockdown cell lines. Our study comprehensively elucidated the role of SOSTDC1 in gastric cancer progression and the results translate into potential therapy for gastric cancer.

Adipocyte and lipid metabolism in cancer drug resistance

Development of novel and effective therapeutics for treating various cancers is probably the most congested and challenging enterprise of pharmaceutical companies. Diverse drugs targeting malignant and nonmalignant cells receive clinical approval each year from the FDA. Targeting cancer cells and nonmalignant cells unavoidably changes the tumor microenvironment, and cellular and molecular components relentlessly alter in response to drugs. Cancer cells often reprogram their metabolic pathways to adapt to environmental challenges and facilitate survival, proliferation, and metastasis. While cancer cells' dependence on glycolysis for energy production is well studied, the roles of adipocytes and lipid metabolic reprogramming in supporting cancer growth, metastasis, and drug responses are less understood. This Review focuses on emerging mechanisms involving adipocytes and lipid metabolism in altering the response to cancer treatment. In particular, we discuss mechanisms underlying cancer-associated adipocytes and lipid metabolic reprogramming in cancer drug resistance.

The Bone Morphogenetic Protein Signaling Inhibitor LDN-193189 Enhances Metastasis Development in Mice

Breast cancer with bone metastasis is essentially incurable with current anticancer therapies. The bone morphogenetic protein (BMP) pathway is an attractive therapeutic candidate, as it is involved in the bone turnover and in cancer cell formation and their colonization of distant organs such as the bone. We previously reported that in breast cancer cells, the ZNF217 oncogene drives BMP pathway activation, increases the metastatic growth rate in the bone, and accelerates the development of severe osteolytic lesions in mice. In the present study, we aimed at investigating the impact of the LDN-193189 compound, a potent inhibitor of the BMP type I receptor, on metastasis development in vivo. ZNF217-revLuc cells were injected into the left ventricle of nude mice (n = 16) while control mice (n = 13) were inoculated with control pcDNA6-revLuc cells. Mice from each group were treated or not with LDN-193189 for 35 days. We found that systemic LDN-193189 treatment of mice significantly enhanced metastasis development, by increasing both the number and the size of metastases. In pcDNA6-revLuc-injected mice, LDN-193189 also affected the kinetics of metastasis emergence. Altogether, these data suggest that in vivo, LDN-193189 might affect the interaction between breast cancer cells and the bone environment, favoring the emergence and development of multiple metastases. Hence, our report highlights the importance of the choice of drugs and therapeutic strategies used in the management of bone metastases.

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.

Investigation into the Molecular Mechanisms underlying the Anti-proliferative and Anti-tumorigenesis activities of Diosmetin against HCT-116 Human Colorectal Cancer

Diosmetin (Dis) is a bioflavonoid with cytotoxicity properties against variety of cancer cells including hepatocarcinoma, breast and colorectal (CRC) cancer. The exact mechanism by which Dis acts against CRC however, still remains unclear, hence in this study, we investigated the possible molecular mechanisms of Dis in CRC cell line, HCT-116. Here, we monitored the viability of HCT-116 cells in the presence of Dis and investigated the underlying mechanism of Dis against HCT-116 cells at the gene and protein levels using NanoString and proteome profiler array technologies. Findings demonstrated that Dis exhibits greater cytotoxic effects towards HCT-116 CRC cells (IC50 = 3.58 ± 0.58 µg/ml) as compared to the normal colon CCD-841 cells (IC50 = 51.95 ± 0.11 µg/ml). Arrests of the cells in G2/M phase confirms the occurrence of mitotic disruption via Dis. Activation of apoptosis factors such as Fas and Bax at the gene and protein levels along with the release of Cytochrome C from mitochondria and cleavage of Caspase cascades indicate the presence of turbulence as a result of apoptosis induction in Dis-treated cells. Moreover, NF-ƙB translocation was inhibited in Dis-treated cells. Our results indicate that Dis can target HCT-116 cells through the mitotic disruption and apoptosis induction.

HDAC2 Inhibitor Valproic Acid Increases Radiation Sensitivity of Drug-Resistant Melanoma Cells

Resistance to anticancer drugs limits the effectiveness of chemotherapy in cancers. Melanoma cell lines B16F10C and A375C (parental) and B16F10R and A375R (drug-resistant sublines) were used to test radiation sensitization potential of valproic acid (VPA), an inhibitor of Histone deacetylase2 (HDAC2) and LDN193189 (BMP inhibitor). Inhibitors of other signaling pathways were tested for cross-resistance with the resistant cell lines. Cells were pretreated with low concentrations of VPA/ LDN193189 and exposed to 2 Gy radiation for radiation sensitization experiments. Assays-3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT), live/dead, clonogenic, and melanin estimation were performed to test the effects of radiation sensitization. Interactions of VPA and HDAC2 were studied in silico. Dose-dependent growth inhibition was observed with all tested drugs. Radiation sensitization of melanoma cells with low dose of VPA induced synergistic cell death, decreased clonogenicity, and decreased melanin content. In silico docking showed two stable interactions between Arg39 of HDAC2 and VPA. In conclusion, pretreatment with low doses of VPA has a potential for sensitizing melanoma cells to low doses of radiation. The binding of VPA to HDAC2 reverses the drug resistance in melanoma and induces the cell death. Sensitization effects of VPA can be used for targeting drug-resistant cancers.

Consequences of BMPR2 Deficiency in the Pulmonary Vasculature and Beyond: Contributions to Pulmonary Arterial Hypertension

Since its association with familial pulmonary arterial hypertension (PAH) in 2000, Bone Morphogenetic Protein Receptor II (BMPR2) and its related signaling pathway have become recognized as a key regulator of pulmonary vascular homeostasis. Herein, we define BMPR2 deficiency as either an inactivation of the receptor, decreased receptor expression, or an impairment of the receptor’s downstream signaling pathway. Although traditionally the phenotypic consequences of BMPR2 deficiency in PAH have been thought to be limited to the pulmonary vasculature, there is evidence that abnormalities in BMPR2 signaling may have consequences in many other organ systems and cellular compartments. Revisiting how BMPR2 functions throughout health and disease in cells and organs beyond the lung vasculature may provide insight into the contribution of these organ systems to PAH pathogenesis as well as the potential systemic manifestation of PAH. Here we review our knowledge of the consequences of BMPR2 deficiency across multiple organ systems.

Shared ACVR1 mutations in FOP and DIPG: Opportunities and challenges in extending biological and clinical implications across rare diseases

Gain-of-function mutations in the Type I Bone Morphogenic Protein (BMP) receptor ACVR1 have been identified in two diseases: Fibrodysplasia Ossificans Progressiva (FOP), a rare autosomal dominant disorder characterized by genetically driven heterotopic ossification, and in 20-25% of Diffuse Intrinsic Pontine Gliomas (DIPGs), a pediatric brain tumor with no effective therapies and dismal median survival. While the ACVR1 mutation is causal for FOP, its role in DIPG tumor biology remains under active investigation. Here, we discuss cross-fertilization between the FOP and DIPG fields, focusing on the biological mechanisms and principles gleaned from FOP that can be applied to DIPG biology. We highlight our current knowledge of ACVR1 in both diseases, and then describe the growing opportunities and barriers to effectively investigate ACVR1 in DIPG. Importantly, learning from other seemingly unrelated diseases harboring similar mutations may uncover novel mechanisms or processes for future investigation.

The critical role of the ZNF217 oncogene in promoting breast cancer metastasis to the bone

Bone metastasis affects >70% of patients with advanced breast cancer. However, the molecular mechanisms underlying this process remain unclear. On the basis of analysis of clinical datasets, and in vitro and in vivo experiments, we report that the ZNF217 oncogene is a crucial mediator and indicator of bone metastasis. Patients with high ZNF217 mRNA expression levels in primary breast tumours had a higher risk of developing bone metastases. MDA-MB-231 breast cancer cells stably transfected with ZNF217 (MDA-MB-231-ZNF217) showed the dysregulated expression of a set of genes with bone-homing and metastasis characteristics, which overlapped with two previously described 'osteolytic bone metastasis' gene signatures, while also highlighting the bone morphogenetic protein (BMP) pathway. The latter was activated in MDA-MB-231-ZNF217 cells, and its silencing by inhibitors (Noggin and LDN-193189) was sufficient to rescue ZNF217-dependent cell migration, invasion or chemotaxis towards the bone environment. Finally, by using non-invasive multimodal in vivo imaging, we found that ZNF217 increases the metastatic growth rate in the bone and accelerates the development of severe osteolytic lesions. Altogether, the findings of this study highlight ZNF217 as an indicator of the emergence of breast cancer bone metastasis; future therapies targeting ZNF217 and/or the BMP signalling pathway may be beneficial by preventing the development of bone metastases. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.