Discovery of a natural small-molecule compound that suppresses tumor EMT, stemness and metastasis by inhibiting TGFβ/BMP signaling in triple-negative breast cancer

Aspongopyrimidine A, a N-Peralkylated Histidine Zwitterion from Aspongopus chinensis against Alzheimer's Disease Targeting MAPRE3

Aspongopyrimidine A (1), a hexa-1,3-diene-histidine-hexanoic acid adduct featuring a 4,5-dihydro-2H-10λ4-imidazo[5,1-f]pyrrolo[2,1-b]pyrimidine motif, was isolated from the insect Aspongopus chinensis. The structure was clarified by spectroscopic and computational methods and X-ray diffraction. Peralkylation of N-atoms in histidine by two C6 units makes 1 an inner salt with a 5/6/5 tricyclic system. Biological evaluation found that 1 exerts activity against Alzheimer's disease targeting MAPRE3 through a chemical proteomics approach. This study revealed unusual modifications of amino acids as the fundamental units of protein.

A novel FGFR1 inhibitor CYY292 suppresses tumor progression, invasion, and metastasis of glioblastoma by inhibiting the Akt/GSK3β/snail signaling axis

Glioblastoma (GBM) is a malignant brain tumor that grows quickly, spreads widely, and is resistant to treatment. Fibroblast growth factor receptor (FGFR)1 is a receptor tyrosine kinase that regulates cellular processes, including proliferation, survival, migration, and differentiation. FGFR1 was predominantly expressed in GBM tissues, and FGFR1 expression was negatively correlated with overall survival. We rationally designed a novel small molecule CYY292, which exhibited a strong affinity for the FGFR1 protein in GBM cell lines in vitro. CYY292 also exerted an effect on the conserved Ser777 residue of FGFR1. CYY292 dose-dependently inhibited cell proliferation, epithelial-mesenchymal transition, stemness, invasion, and migration in vitro by specifically targeting the FGFR1/AKT/Snail pathways in GBM cells, and this effect was prevented by pharmacological inhibitors and critical gene knockdown. In vivo experiments revealed that CYY292 inhibited U87MG tumor growth more effectively than AZD4547. CYY292 also efficiently reduced GBM cell proliferation and increased survival in orthotopic GBM models. This study further elucidates the function of FGFR1 in the GBM and reveals the effect of CYY292, which targets FGFR1, on downstream signaling pathways directly reducing GBM cell growth, invasion, and metastasis and thus impairing the recruitment, activation, and function of immune cells.

Novel spirooxindole alkaloid derivatives from the medicinal insect Blaps japanensis and their biological evaluation

Blapspirooxindoles A-C (1-3), three novel spirooxindole alkaloids with a unique spiro[chromane-4,3'-indoline]-2,2'-dione motif, blapcumaranons A and B (4 and 5), two new 2-cumaranon derivatives, blapoxindoles A-J (6-15), ten new oxindole alkaloid derivatives, along with one known compound (16), were isolated from the whole bodies of Blaps japanensis. Their structures including absolute configurations were determined by using spectroscopic, X-ray crystallographic, and computational methods. Compounds 1-11 and 13 exist as racemic mixtures in nature, and their (-)- and (+)-antipodes were separated by chiral HPLC. Biological evaluations of these compounds were determined with multiple assays including anti-tumor, anti-inflammatory, and renal protection activities in vitro. Several compounds displayed effective activity in one or more assays.

miR-181-5p/KLHL5 Promoted Proliferation and Migration of Gastric Cancer Through Activating METTL3-Mediated m6A Process

KLHL5 was a member of kelch-repeat protein family and was involved in the initiation of progression of a plethora of cancers. However, its specific role in gastric cancer was not explicitly illustrated. In this context, we aimed to investigate the biological role and mechanisms about KLHL5 in gastric cancer. qRT-PCR and western blot were used to investigate the expression of KLHL5 and EMT biomarkers. Wound healing assay, CCK-8, and Transwell assay were used to investigate the biological function of KLHL5. We found that KLHL5 was highly expressed in gastric cancer both in vivo and in vitro; besides, its high expression led to a shorter overall survival. Following statistical analysis showed that KLHL5 was associated with M stage. As for molecular experiments, we found that KLHL5 knockdown significantly reduced the proliferation, migration, and invasion ability of gastric cancer cell line MKN45 and SGC-7901. Furthermore, we found that miR-181-5p targeted KLHL5 to regulate m6A level through METTL3. In addition, KLHL5 knockdown could significantly reduce the lung metastasis rate in mice. In conclusion, we found that miR-181-5p/KLHL5 could promote the proliferation, migration, and invasion of gastric cancer by activating m6A process through regulating METTL3.

Signaling pathways governing the maintenance of breast cancer stem cells and their therapeutic implications

Breast cancer stem cells (BCSCs) represent a distinct subpopulation of cells with the ability to self-renewal and differentiate into phenotypically diverse tumor cells. The involvement of CSC in treatment resistance and cancer recurrence has been well established. Numerous studies have provided compelling evidence that the self-renewal ability of cancer stem cells is tightly regulated by specific signaling pathways, which exert critical roles to maintain an undifferentiated phenotype and prevent the differentiation of CSCs. Signaling pathways such as Wnt/β-catenin, NF-κB, Notch, Hedgehog, TGF-β, and Hippo have been implicated in the promotion of self-renewal of many normal and cancer stem cells. Given the pivotal role of BCSCs in driving breast cancer aggressiveness, targeting self-renewal signaling pathways holds promise as a viable therapeutic strategy for combating this disease. In this review, we will discuss the main signaling pathways involved in the maintenance of the self-renewal ability of BCSC, while also highlighting current strategies employed to disrupt the signaling molecules associated with stemness.

Aquilariperoxide A, a Sesquiterpene Dimer from Agarwood of Aquilaria sinensis with Dual Antitumor and Antimalarial Effects

Aquilariperoxide A (1), an unprecedented sesquiterpene dimer characterized by a dioxepane ring connecting two sesquiterpene units via a C-C bond, was isolated from agarwood of Aquilaria sinensis-containing resins. The structure was elucidated by spectroscopic and computational methods. A bioassay revealed that 1 significantly inhibits cell proliferation and migration in human cancer cells. The mechanism of 1 against cancer cells was briefly discussed by analysis of RNA sequence data and epithelial-mesenchymal transition. Besides, the antimalarial activity of 1 was also evaluated.

Timosaponin BII inhibits TGF-β mediated epithelial-mesenchymal transition through Smad-dependent pathway during pulmonary fibrosis

Pulmonary fibrosis (PF) is a progressive and fatal interstitial lung disease with limited therapeutic options at present, and epithelial-mesenchymal transition (EMT) is recognized as a major cause of lung fibrosis. Our previous work has confirmed that total extract of Anemarrhena asphodeloides Bunge [Asparagaceae] exerted the effect of anti-PF. As a main constituent of Anemarrhena asphodeloides Bunge [Asparagaceae], the effect of timosaponin BII (TS BII) on drug-induced EMT process in PF animals and alveolar epithelial cells remains unknown. In this study, we evaluated the effect of TS BII on bleomycin (BLM)-induced PF. The results showed that TS BII could restore the structure of lung architecture and MMP-9/TIMP-1 balance in fibrotic rat lung and inhibit collagen deposition. Moreover, we found that TS BII could reverse the abnormal expression of TGF-β1 and EMT-related marker proteins including E-cadherin, vimentin, and α-SMA. Besides, aberrant TGF-β1 expression and phosphorylation of Smad2 and Smad3 in BLM-induced animal model and TGF-β1-induced cell model were downregulated by TS BII treatment, indicating that EMT in fibrosis was suppressed by inhibition of TGF-β/Smad pathway both in vivo and in vitro. In summary, our study suggested that TS BII could be a promising candidate for PF treatment.

Meso-Hannokinol inhibits breast cancer bone metastasis via the ROS/JNK/ZEB1 axis

Distal metastases from breast cancer, especially bone metastases, are extremely common in the late stages of the disease and are associated with a poor prognosis. EMT is a biomarker of the early process of bone metastasis, and MMP-9 and MMP-13 are important osteoclastic activators. Previously, we found that meso-Hannokinol (HA) could significantly inhibit EMT and MMP-9 and MMP-13 expressions in breast cancer cells. On this basis, we further explored the role of HA in breast cancer bone metastasis. In vivo, we established a breast cancer bone metastasis model by intracardially injecting breast cancer cells. Intraperitoneal injections of HA significantly reduced breast cancer cell metastasis to the leg bone in mice and osteolytic lesions caused by breast cancer. In vitro, HA inhibited the migration and invasion of breast cancer cells and suppressed the expressions of EMT, MMP-9, MMP-13, and other osteoclastic activators. HA inhibited EMT and MMP-9 by activating the ROS/JNK pathway as demonstrated by siJNK and SP600125 inhibition of JNK phosphorylation and NAC scavenging of ROS accumulation. Moreover, HA promoted bone formation and inhibited bone resorption in vitro. In conclusion, our findings suggest that HA may be an excellent candidate for treating breast cancer bone metastasis.

Potential bioactive compounds and mechanisms of Fibraurea recisa Pierre for the treatment of Alzheimer's disease analyzed by network pharmacology and molecular docking prediction

Introduction

Heat-clearing and detoxifying Chinese medicines have been documented to have anti-Alzheimer's disease (AD) activities according to the accumulated clinical experience and pharmacological research results in recent decades. In this study, Fibraurea recisa Pierre (FRP), the classic type of Heat-clearing and detoxifying Chinese medicine, was selected as the object of research.

Methods

12 components with anti-AD activities were identified in FRP by a variety of methods, including silica gel column chromatography, multiple databases, and literature searches. Then, network pharmacology and molecular docking were adopted to systematically study the potential anti-AD mechanism of these compounds. Consequently, it was found that these 12 compounds could act on 235 anti-AD targets, of which AKT and other targets were the core targets. Meanwhile, among these 235 targets, 71 targets were identified to be significantly correlated with the pathology of amyloid beta (Aβ) and Tau.

Results and discussion

In view of the analysis results of the network of active ingredients and targets, it was observed that palmatine, berberine, and other alkaloids in FRP were the key active ingredients for the treatment of AD. Further, Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis revealed that the neuroactive ligand-receptor interaction pathway and PI3K-Akt signaling pathway were the most significant signaling pathways for FRP to play an anti-AD role. Findings in our study suggest that multiple primary active ingredients in FRP can play a multitarget anti-AD effect by regulating key physiological processes such as neurotransmitter transmission and anti-inflammation. Besides, key ingredients such as palmatine and berberine in FRP are expected to be excellent leading compounds of multitarget anti-AD drugs.

Metastasis prevention: targeting causes and roots

The spread of tumor cells from the primary focus, metastasis, is the main cause of cancer mortality. Therefore, anticancer therapy should be focused on the prevention of metastatic disease. Key targets can be conditions in the primary tumor that are favorable for the appearance of metastatic cells and the first steps of the metastatic cascade. Here, we discuss different approaches for targeting metastasis causes (hypoxia, metabolism changes, and tumor microenvironment) and roots (angiogenesis, epithelial-mesenchymal transition, migration, and invasion). Also, we emphasize the challenges of the existing approaches for metastasis prevention and suggest opportunities to overcome them. In conclusion, we highlight the importance of clinical evaluation of the agents showing antimetastatic effects in vivo, especially in patients with early-stage cancers, the identification of metastatic seeds, and the development of therapeutics for their eradication.

Structural Optimization and Improving Antitumor Potential of Moreollic Acid from Gamboge

Moreollic acid, a caged-tetraprenylated xanthone from Gamboge, has been indicated as a potent antitumor molecule. In the present study, a series of moreollic acid derivatives with novel structures were designed and synthesized, and their antitumor activities were determined in multifarious cell lines. The preliminary screening results showed that all synthesized compounds selectively inhibited human colon cancer cell proliferation. TH12-10, with an IC50 of 0.83, 1.10, and 0.79 μM against HCT116, DLD1, and SW620, respectively, was selected for further antitumor mechanism studies. Results revealed that TH12-10 effectively inhibited cell proliferation by blocking cell-cycle progression from G1 to S. Besides, the apparent structure-activity relationships of target compounds were discussed. To summarize, a series of moreollic acid derivatives were discovered to possess satisfactory antitumor potentials. Among them, TH12-10 displays the highest antitumor activities against human colon cancer cells, in which the IC50 values in DLD1 and SW620 are lower than that of 5-fluorouracil.

The Antibiotic Drug Trimethoprim Suppresses Tumor Growth and Metastasis via Targeting Snail

BACKGROUND AND PURPOSE

The zinc finger transcription factor Snail is aberrantly activated in many human cancers and strongly associated with poor prognosis. As a transcription factor, Snail has been traditionally considered an "undruggable" target. Here, we identified a potent small molecule inhibitor of Snail, namely trimethoprim, and investigated its potential antitumor effects and the underlying mechanisms.

EXPERIMENTAL APPROACH

The inhibitory action of trimethoprim on Snail protein and the related molecular mechanisms were revealed by molecular docking, biolayer interferometry, immunoblotting, immunoprecipitation, qRT-PCR, pull-down, and cycloheximide pulse-chase assays. The anti-proliferative and anti-metastatic effects of trimethoprim via targeting Snail were tested in multiple cell-based assays and animal models.

KEY RESULTS

This study identified trimethoprim, an antimicrobial drug, as a potent anti-tumor agent via targeting Snail. Molecular modeling analysis predicted that trimethoprim directly binds to the arginine-174 pocket of Snail protein. We further discovered that trimethoprim strongly interrupts the interaction of Snail with CREB-binding protein (CBP)/p300, which consequently suppresses Snail acetylation and promotes Snail degradation through ubiquitin-proteasome pathway. Furthermore, trimethoprim sufficiently inhibited the proliferation, epithelial-mesenchymal transition (EMT), and migration of cancer cells in vitro via specifically targeting Snail. More importantly, trimethoprim effectively reduced Snail-driven tumor growth and metastasis to vital organs such as lung, bone, and liver.

CONCLUSIONS AND IMPLICATIONS

These findings indicate, for the first time, that trimethoprim suppresses tumor growth and metastasis via targeting Snail. This study provides insights for a better understanding of the anticancer effects of trimethoprim and offers a potential anti-cancer therapeutic agent for clinical treatment.

Heterogeneity of BCSCs contributes to the metastatic organotropism of breast cancer

Breast cancer is one of the most-common female malignancies with a high risk of relapse and distant metastasis. The distant metastasis of breast cancer exhibits organotropism, including brain, lung, liver and bone. Breast cancer stem cells (BCSCs) are a small population of breast cancer cells with tumor-initiating ability, which participate in regulating distant metastasis in breast cancer. We investigated the heterogeneity of BCSCs according to biomarker status, epithelial or mesenchymal status and other factors. Based on the classical “seed and soil” theory, we explored the effect of BCSCs on the metastatic organotropism in breast cancer at both “seed” and “soil” levels, with BCSCs as the “seed” and BCSCs-related microenvironment as the “soil”. We also summarized current clinical trials, which assessed the safety and efficacy of BCSCs-related therapies. Understanding the role of BCSCs heterogeneity for regulating metastatic organotropism in breast cancer would provide a new insight for the diagnosis and treatment of advanced metastatic breast cancer.

Basic approaches, challenges and opportunities for the discovery of small molecule anti-tumor drugs

Chemotherapy is one of the main treatments for cancer, especially for advanced cancer patients. In the past decade, significant progress has been made with the research into the molecular mechanisms of cancer cells and the precision medicine. The treatment on cancer patients has gradually changed from cytotoxic chemotherapy to precise treatment strategy. Research into anticancer drugs has also changed from killing effects on all cells to targeting drugs for target genes. Besides, researchers have developed the understanding of the abnormal physiological function, related genomics, epigenetics, and proteomics of cancer cells with cancer genome sequencing, epigenetic research, and proteomic research. These technologies and related research have accelerated the development of related cancer drugs. In this review, we summarize the research progress of anticancer drugs, the current challenges, and future opportunities.

Inhibiting roles of FOXA2 in liver cancer cell migration and invasion by transcriptionally suppressing microRNA-103a-3p and activating the GREM2/LATS2/YAP axis

Forkhead box A2 (FOXA2) has emerged as a tumor inhibitor in several human malignancies. This work focused on the effect of FOXA2 on liver cancer (LC) cell invasion and migration and the involving molecules. FOXA2 expression in LC tissues and cell lines was determined. The potential target microRNA (miRNA) of FOXA2 was predicted via bioinformatic analysis and validated through a ChIP assay. The mRNA target of miRNA-103a-3p was predicted via bioinformatic analysis and confirmed via a luciferase assay. Altered expression of FOXA2, miR-103a-3p and GREM2 was introduced in cells to identify their roles in LC cell migration and invasion. Consequently, FOXA2 and GREM2 were poorly expressed while miR-103a-3p was highly expressed in LC samples. Overexpression of FOXA2 or GREM2 suppressed migration and invasion of LC cells, while up-regulation of miR-103a-3p led to inverse trends. FOXA2 transcriptionally suppressed miR-103a-3p to increase GREM2 expression. Silencing of GREM2 blocked the effects of FOXA2. GREM2 increased LATS2 activity and YAP phosphorylation and degradation. To conclude, this study demonstrated that FOXA2 suppressed miR-103a-3p transcription to induce GREM2 upregulation, which increased LATS2 activity and YAP phosphorylation to inhibit migration and invasion of LC cells.

Deciphering molecular mechanisms of metastasis: novel insights into targets and therapeutics

BACKGROUND

The transition of a primary tumour to metastatic progression is driven by dynamic molecular changes, including genetic and epigenetic alterations. The metastatic cascade involves bidirectional interactions among extracellular and intracellular components leading to disintegration of cellular junctions, cytoskeleton reorganization and epithelial to mesenchymal transition. These events promote metastasis by reprogramming the primary cancer cell's molecular framework, enabling them to cause local invasion, anchorage-independent survival, cell death and immune resistance, extravasation and colonization of distant organs. Metastasis follows a site-specific pattern that is still poorly understood at the molecular level. Although various drugs have been tested clinically across different metastatic cancer types, it has remained difficult to develop efficacious therapeutics due to complex molecular layers involved in metastasis as well as experimental limitations.

CONCLUSIONS

In this review, a systemic evaluation of the molecular mechanisms of metastasis is outlined and the potential molecular components and their status as therapeutic targets and the associated pre-clinical and clinical agents available or under investigations are discussed. Integrative methods like pan-cancer data analysis, which can provide clinical insights into both targets and treatment decisions and help in the identification of crucial components driving metastasis such as mutational profiles, gene signatures, associated pathways, site specificities and disease-gene phenotypes, are discussed. A multi-level data integration of the metastasis signatures across multiple primary and metastatic cancer types may facilitate the development of precision medicine and open up new opportunities for future therapies.

New Therapeutic Options for Advanced Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), one of the most common lethal diseases in the world, has a 5-year survival rate of only 7%. Hepatocellular carcinoma has no symptoms in the early stage but obvious symptoms in the late stage, leading to delayed diagnosis and reduced treatment efficacy. In recent years, as the scope of HCC research has increased in depth, the clinical development and application of molecular targeted drugs and immunotherapy drugs have brought new breakthroughs in HCC treatment. Targeted therapy drugs for HCC have high specificity, allowing them to selectively kill tumor cells and minimize damage to normal tissues. At present, these targeted drugs are mainly classified into 3 categories: small molecule targeted drugs, HCC antigen-specific targeted drugs, and immune checkpoint targeted drugs. This article reviews the latest research progress on the targeted drugs for HCC.

Paving the way for small-molecule drug discovery

Small-molecule drugs are organic compounds affecting molecular pathways by targeting important proteins, which have a low molecular weight, making them penetrate cells easily. Small-molecule drugs can be developed from leads derived from rational drug design or isolated from natural resources. As commonly used medications, small-molecule drugs can be taken orally, which enter cells to act on intracellular targets. These characteristics make small-molecule drugs promising candidates for drug development, and they are increasingly favored in the pharmaceutical market. Despite the advancements in molecular genetics and effective new processes in drug development, the drugs currently used in clinical practice are inadequate due to their poor efficacy or severe side effects. Therefore, developing new safe and efficient drugs is a top priority for disease control and curing.

Nonpeptide small molecules with a ten-membered macrolactam or a morpholine motif from the insect American cockroach and their antiangiogenic activity

(±)-Periplactam A (1), a rare ten-membered macrolactam composed of lignan and putrescine, (±)-periplanol E (2), a dimeric phenethyl alcohol derivative formed via morpholine, and periplactams B (3) and C (4) were isolated from American cockroach.

Long non‑coding RNA NEAT1 promotes ovarian cancer cell invasion and migration by interacting with miR‑1321 and regulating tight junction protein 3 expression

Previous studies have reported that long non‑coding RNAs (lncRNAs) have a significant role in the metastasis of tumors, including ovarian cancer (OC). The aim of the present study was to demonstrate the function and working mechanism of lncRNA nuclear enriched abundant transcript 1 (NEAT1) in OC. The expressions of NEAT1 in OC were measured by reverse transcription‑quantitativePCR (RT‑qPCR). The effects of NEAT1 on cell proliferation, invasion, migration and epithelial‑mesenchymal transition (EMT) were detected by Cell Counting Kit‑8, transwell and wound healing assays, and western blotting. Dual‑luciferase reporter assays were performed to confirm the correlated between NEAT and miR‑1321, miR‑1321 and TJP3. The effect of NEAT1 on miR‑1321 and TJP3 was confirmed by RT‑qPCR and western blotting. Elevated expression of NEAT1 was observed in OC cell lines, and NEAT1 expression was found to be positively related to the expression of tight junction protein 3 (TJP3), which is important in cancer development. Moreover, the present results indicated that NEAT1 and TJP3 expression levels were negatively correlated with microRNA (miR)‑1321 expression in OC. Knockdown of NEAT1 attenuated the migration and invasion of OC cells, as well as increased miR‑1321 expression and in turn led to the reduction of TJP3. Thus, the present study demonstrated that NEAT1 regulates TJP3 expression by sponging miR‑1321 and enhances the epithelial‑mesenchymal transition, invasion and migration of OC cells. Overall, the present study identified the function and mechanism of NEAT1 in OC, suggesting that NEAT1 may be a promising therapeutic target for OC metastasis.

Annurca apple polyphenol extract promotes mesenchymal-to-epithelial transition and inhibits migration in triple-negative breast cancer cells through ROS/JNK signaling

Aberrant activation of epithelial-to-mesenchymal transition has been shown to correlate with triple-negative breast cancer (TNBC) progression and metastasis. Thus, the induction of the reverse process might offer promising opportunities to restrain TNBC metastatic spreading and related mortality. Recently, the Annurca apple polyphenol extract (APE) has been highlighted as a multi-faceted agent that selectively kills TNBC cells by ROS generation and sustained JNK activation. Here, by qualitatively and quantitatively monitoring the real-time movements of live cells we provided the first evidence that APE inhibited the migration of MDA-MB-231 and MDA-MB-468 TNBC cells and downregulated metalloproteinase-2 and metalloproteinase-9. In MDA-MB-231 cells APE decreased SMAD-2/3 and p-SMAD-2/3 levels, increased E-cadherin/N-cadherin protein ratio, induced the switch from N-cadherin to E-cadherin expression and greatly reduced vimentin levels. Confocal and scanning electron microscopy imaging of APE-treated MDA-MB-231 cells evidenced a significant cytoskeletal vimentin and filamentous actin reorganization and revealed considerable changes in cell morphology highlighting an evident transition from the mesenchymal to epithelial phenotype with decreased migratory features. Notably, all these events were reverted by N-acetyl-l-cysteine and JNK inhibitor SP600125 furnishing evidence that APE exerted its effects through the activation of ROS/JNK signaling. The overall data highlighted APE as a potential preventing agent for TNBC metastasis.

Osteolytic metastasis in breast cancer: effective prevention strategies

INTRODUCTION

Breast cancer is the most common cancer in women throughout the world. Patients who are diagnosed early generally have better prognosis and survivability. Indeed, advanced stage breast cancer often develops osteolytic metastases, leading to bone destruction. Although there are select drugs available to treat bone metastatic disease, these drugs have shown limited success.

AREA COVERED

This paper emphasizes updated mechanisms of bone remodeling and osteolytic bone metastases of breast cancer. This article also aims to explore the potential of novel natural and synthetic therapeutics in the effective prevention of breast cancer-induced osteolysis and osteolytic metastases of breast cancer.

EXPERT OPINION

Targeting TGFβ and BMP signaling pathways, along with osteoclast activity, appears to be a promising therapeutic strategy in the prevention of breast cancer-induced osteolytic bone destruction and metastatic growth at bone metastatic niches. Pilot studies in animal models suggest various natural and synthetic compounds and monoclonal antibodies as putative therapeutics in the prevention of breast cancer stimulated osteolytic activity. However, comprehensive pre-clinical studies demonstrating the PK/PD and in-depth understanding of molecular mechanism(s) by which these potential molecules exhibit anti-tumor growth and anti-osteolytic activity are still required to develop effective therapies against breast cancer-induced osteolytic bone disease.

Secreted BMP antagonists and their role in cancer and bone metastases

Bone morphogenetic proteins (BMPs) are multifunctional secreted cytokines that act in a highly context-dependent manner. BMP action extends beyond the induction of cartilage and bone formation, to encompass pivotal roles in controlling tissue and organ homeostasis during development and adulthood. BMPs signal via plasma membrane type I and type II serine/threonine kinase receptors and intracellular SMAD transcriptional effectors. Exquisite temporospatial control of BMP/SMAD signalling and crosstalk with other cellular cues is achieved by a series of positive and negative regulators at each step in the BMP/SMAD pathway. The interaction of BMP ligand with its receptors is carefully controlled by a diverse set of secreted antagonists that bind BMPs and block their interaction with their cognate BMP receptors. Perturbations in this BMP/BMP antagonist balance are implicated in a range of developmental disorders and diseases, including cancer. Here, we provide an overview of the structure and function of secreted BMP antagonists, and summarize recent novel insights into their role in cancer progression and bone metastasis. Gremlin1 (GREM1) is a highly studied BMP antagonist, and we will focus on this molecule in particular and its role in cancer. The therapeutic potential of pharmacological inhibitors for secreted BMP antagonists for cancer and other human diseases will also be discussed.

Breast cancer metastasis to bone: From epithelial to mesenchymal transition to breast osteoblast-like cells

In this review we highlighted the newest aspects concerning the physiopathology of breast cancer metastatization into the bone including: a) in situ biomarkers of breast cancer metastatic diseases, b) biological processes related to the origin of metastatic cells (epithelial to mesenchymal transition), c) the nature and the possible role of Breast Osteoblast-Like Cells in the formation of bone lesions and d) the prognostic value of breast microcalcifications for the bone metastatic disease. In addition, the more recent data about the biology of breast cancer metastatic process and the origin and function of Breast Osteoblast-Like Cells have been analyzed to propose the use of molecular imaging investigations able to identify early neoplastic lesions with high propensity to form bone metastasis in vivo.

Self-Renewal Signalling Pathway Inhibitors: Perspectives on Therapeutic Approaches for Cancer Stem Cells

The poor survival and prognosis of individuals with cancer are often attributed to tumour relapse and metastasis, which may be due to the presence of cancer stem cells (CSCs). CSCs have the characteristics of self-renewal, differentiation potential, high carcinogenicity, and drug resistance. In addition, CSCs exhibit many characteristics similar to those of embryonic or tissue stem cells while displaying persistent abnormal activation of self-renewal pathways associated with development and tissue homeostasis, including the Wnt, Notch, Hedgehog (Hh), TGF-β, JAK/STAT3, and NF-κB pathways. Therefore, we can eliminate CSCs by targeting these self-renewal pathways to constrain stem cell replication, survival and differentiation. At the same time, we cannot neglect the ping-pong effect of the tumour microenvironment, which releases cytokines and promotes self-renewal pathways in CSCs. Recently, meaningful progress has been made in the study of inhibitors of self-renewal pathways in tumours. This review primarily summarizes several representative and novel agents targeting these self-renewal signalling pathways and the tumour microenvironment and that represent a promising strategy for treating refractory and recurrent cancer.

The E-Cadherin and N-Cadherin Switch in Epithelial-to-Mesenchymal Transition: Signaling, Therapeutic Implications, and Challenges

Epithelial-to-Mesenchymal Transition (EMT) has been shown to be crucial in tumorigenesis where the EMT program enhances metastasis, chemoresistance and tumor stemness. Due to its emerging role as a pivotal driver of tumorigenesis, targeting EMT is of great therapeutic interest in counteracting metastasis and chemoresistance in cancer patients. The hallmark of EMT is the upregulation of N-cadherin followed by the downregulation of E-cadherin, and this process is regulated by a complex network of signaling pathways and transcription factors. In this review, we summarized the recent understanding of the roles of E- and N-cadherins in cancer invasion and metastasis as well as the crosstalk with other signaling pathways involved in EMT. We also highlighted a few natural compounds with potential anti-EMT property and outlined the future directions in the development of novel intervention in human cancer treatments. We have reviewed 287 published papers related to this topic and identified some of the challenges faced in translating the discovery work from bench to bedside.

Atypical Mesenchymal Stromal Cell Responses to Topographic Modifications of Titanium Biomaterials Indicate Cytoskeletal- and Genetic Plasticity-Based Heterogeneity of Cells

Titanium (Ti) is widely used as a biomaterial for endosseous implants due to its relatively inert surface oxide layer that enables implanted devices the ability of assembling tissue reparative components that culminate in osseointegration. Topographic modifications in the form of micro- and nanoscaled structures significantly promote osseointegration and enhance the osteogenic differentiation of adult mesenchymal stromal cells (MSCs). While the biological mechanisms central to the differential responses of tissues and cells to Ti surface modifications remain unknown, adhesion and morphological adaptation are amongst the earliest events at the cell-biomaterial interface that are highly influenced by surface topography and profoundly impact the regulation of stem cell fate determination. This study correlated the effects of Ti topographic modifications on adhesion and morphological adaptation of human MSCs with phenotypic change. The results showed that modified Ti topographies precluded the adhesion of a subset of MSCs while incurring distinct morphological constraints on adherent cells. These effects anomalously corresponded with a differential expression of stem cell pluripotency and Wnt signalling-associated markers on both modified surfaces while additionally differing between hydrophobic and hydrophilic surface modifications—though extent of osteogenic differentiation induced by both modified topographies yielded similarly significant higher levels of cellular mineralisation in contrast to polished Ti. These results suggest that in the absence of deposited proteins and soluble factors, both modified topographies incur the selective adhesion of a subpopulation of progenitors with relatively higher cytoskeletal plasticity. While the presence of deposited proteins and soluble factors does not significantly affect adherence of cells, nanotopographic modifications enhance expression of pluripotency markers in proliferative conditions, which are conversely overridden by both modified topographies in osteogenic inductive conditions. Further deciphering the mechanisms underlying cellular selectivity and Ti topographic responsiveness will improve our understanding of stem cell heterogeneity and advance the potential of MSCs in regenerative medicine.