Doxycycline as an inhibitor of the epithelial-to-mesenchymal transition and vasculogenic mimicry in hepatocellular carcinoma

Role of epigenetic regulation in glaucoma

Glaucoma is the world's leading irreversible blinding eye disease. Lowering intraocular pressure is currently the only effective clinical treatment. However, there is a lack of long-acting IOP-lowering drugs, and some patients still experience retinal ganglion cell loss even with good intraocular pressure control. Currently, there is no effective method for neuroprotection and regeneration in clinical practice for glaucoma. In recent years, epigenetics has been widely researched and reported for its role in glaucoma's neuroprotection and regeneration. This article reviews the changes in histone modifications, DNA methylation, non-coding RNA, and m6A methylation in glaucoma, aiming to provide new perspectives for glaucoma management, protection of retinal ganglion cells, and axon regeneration by understanding epigenetic alterations.

Multiple Roles of the RUNX Gene Family in Hepatocellular Carcinoma and Their Potential Clinical Implications

Hepatocellular carcinoma (HCC) is one of the most frequent cancers in humans, characterised by a high resistance to conventional chemotherapy, late diagnosis, and a high mortality rate. It is necessary to elucidate the molecular mechanisms involved in hepatocarcinogenesis to improve diagnosis and treatment outcomes. The Runt-related (RUNX) family of transcription factors (RUNX1, RUNX2, and RUNX3) participates in cardinal biological processes and plays paramount roles in the pathogenesis of numerous human malignancies. Their role is often controversial as they can act as oncogenes or tumour suppressors and depends on cellular context. Evidence shows that deregulated RUNX genes may be involved in hepatocarcinogenesis from the earliest to the latest stages. In this review, we summarise the topical evidence on the roles of RUNX gene family members in HCC. We discuss their possible application as non-invasive molecular markers for early diagnosis, prognosis, and development of novel treatment strategies in HCC patients.

Repurposing approved non-oncology drugs for cancer therapy: a comprehensive review of mechanisms, efficacy, and clinical prospects

Cancer poses a significant global health challenge, with predictions of increasing prevalence in the coming years due to limited prevention, late diagnosis, and inadequate success with current therapies. In addition, the high cost of new anti-cancer drugs creates barriers in meeting the medical needs of cancer patients, especially in developing countries. The lengthy and costly process of developing novel drugs further hinders drug discovery and clinical implementation. Therefore, there has been a growing interest in repurposing approved drugs for other diseases to address the urgent need for effective cancer treatments. The aim of this comprehensive review is to provide an overview of the potential of approved non-oncology drugs as therapeutic options for cancer treatment. These drugs come from various chemotherapeutic classes, including antimalarials, antibiotics, antivirals, anti-inflammatory drugs, and antifungals, and have demonstrated significant antiproliferative, pro-apoptotic, immunomodulatory, and antimetastatic properties. A systematic review of the literature was conducted to identify relevant studies on the repurposing of approved non-oncology drugs for cancer therapy. Various electronic databases, such as PubMed, Scopus, and Google Scholar, were searched using appropriate keywords. Studies focusing on the therapeutic potential, mechanisms of action, efficacy, and clinical prospects of repurposed drugs in cancer treatment were included in the analysis. The review highlights the promising outcomes of repurposing approved non-oncology drugs for cancer therapy. Drugs belonging to different therapeutic classes have demonstrated notable antitumor effects, including inhibiting cell proliferation, promoting apoptosis, modulating the immune response, and suppressing metastasis. These findings suggest the potential of these repurposed drugs as effective therapeutic approaches in cancer treatment. Repurposing approved non-oncology drugs provides a promising strategy for addressing the urgent need for effective and accessible cancer treatments. The diverse classes of repurposed drugs, with their demonstrated antiproliferative, pro-apoptotic, immunomodulatory, and antimetastatic properties, offer new avenues for cancer therapy. Further research and clinical trials are warranted to explore the full potential of these repurposed drugs and optimize their use in treating various cancer types. Repurposing approved drugs can significantly expedite the process of identifying effective treatments and improve patient outcomes in a cost-effective manner.

The driving mechanism and targeting value of mimicry between vascular endothelial cells and tumor cells in tumor progression

The difficulty and poor prognosis of malignant tumor have always been a difficult problem to be solved. The internal components of solid tumor are complex, including tumor cells, stromal cells and immune cells, which play an important role in tumor proliferation, migration, metastasis and drug resistance. Hence, targeting of only the tumor cells will not likely improve survival. Various studies have reported that tumor cells and endothelial cells have high plasticity, which is reflected in the fact that they can simulate each other's characteristics by endothelial-mesenchymal transition (EndMT) and vasculogenic mimicry (VM). In this paper, this mutual mimicry concept was integrated and reviewed for the first time, and their similarities and implications for tumor development are discussed. At the same time, possible therapeutic methods are proposed to provide new directions and ideas for clinical targeted therapy and immunotherapy of tumor.

Gastric Cancer Vascularization and the Contribution of Reactive Oxygen Species

Blood vessels are the most important way for cancer cells to survive and diffuse in the body, metastasizing distant organs. During the process of tumor expansion, the neoplastic mass progressively induces modifications in the microenvironment due to its uncontrolled growth, generating a hypoxic and low pH milieu with high fluid pressure and low nutrients concentration. In such a particular condition, reactive oxygen species play a fundamental role, enhancing tumor proliferation and migration, inducing a glycolytic phenotype and promoting angiogenesis. Indeed, to reach new sources of oxygen and metabolites, highly aggressive cancer cells might produce a new abnormal network of vessels independently from endothelial cells, a process called vasculogenic mimicry. Even though many molecular markers and mechanisms, especially in gastric cancer, are still unclear, the formation of such intricate, leaky and abnormal vessel networks is closely associated with patients' poor prognosis, and therefore finding new pharmaceutical solutions to be applied along with canonical chemotherapies in order to control and normalize the formation of such networks is urgent.

Doxycycline-Induced Changes in Circulating MMP or TIMP2 Levels Are Not Associated with Skeletal-Related Event-Free or Overall Survival in Patients with Bone Metastases from Breast Cancer

Doxycycline is often used as a promoter of inducible gene expression in preclinical models; however, it can also have direct effects on tumor growth and survival. This is due in part to its ability to inhibit cell invasion and regulate matrix metalloproteinase (MMP) expression. Given that doxycycline is also osteotropic, a clinical study to assess its effects on modulation of tumor progression or prevention of skeletal-related events (SRE) in patients with bone metastases from breast cancer (the Achilles trial) was undertaken. Patients received 100 mg of oral doxycycline twice daily for 12 weeks, with serum obtained at baseline and 4, 8 and 12 weeks post-initiation of doxycycline treatment. Exploratory analysis of the effects of doxycycline on circulating levels of MMP or tissue inhibitor of matrix metalloproteinase 2 (TIMP2) was performed in enrolled patients. Statistically significant associations were observed between MMP2, MMP9 and TIMP2 at baseline with significant associations maintained between absolute levels and changes in levels of MMP2 and TIMP2 at weeks 4-12 post initiation of doxycycline. Treatment with doxycycline generally resulted in decreases in MMP2 and MMP9 levels with concurrent upregulation of TIMP2 at 12 weeks post-initiation of doxycycline treatment. Despite this, we observed no association with the levels of any of these factors with either SRE-free or overall survival in this patient cohort. In summary, despite observing hypothesized effects of doxycycline administration on surrogate markers of its anti-tumor activity, measures of circulating levels of these biomarkers were not prognostic in this patient population.

Doxycycline Hydrochloride Regulates Cytoskeletal Rearrangement and Epithelial-To-Mesenchymal Transition in Malignant Rhabdoid Tumour of the Kidney

Objective. As a highly malignant tumour, malignant rhabdoid tumours of the kidney (MRTK) are prone to metastasis and invasion, while tumour metastasis and invasion are inseparable from matrix metalloproteinases (MMPs) and epithelial-mesenchymal transformation (EMT). Moreover, the key to EMT is remodelling of the cytoskeleton. Therefore, our study is aimed at investigating whether doxycycline hydrochloride (DCH), an inhibitor of MMPs, could reverse EMT in MRTK to exert an antitumour effect by regulating MMPs and the cytoskeleton. Methods. The existence of EMT in MRTK cells was verified by bioinformatics analysis, immunofluorescence, and western blotting (WB). In vitro, the proliferation, migration, and invasion abilities of G401 cells were examined by Cell Counting Kit-8 (CCK-8), scratch, and Transwell assays, respectively. The effect of DCH on tumour growth in tumour-bearing mice was explored in in vivo experiments, and the expression of MMP2 and MMP9 and EMT correlation indexes was measured by immunofluorescence and WB, and the changes in cytoskeletal F-actin and β-tubulin were measured by fluorescence. Results. The altered extracellular matrix (ECM) composition, EMT, and high expression of MMP2 and MMP9 existed in MRTK. DCH inhibited the proliferation, migration, and invasion of G401 cells in vitro. In vivo, DCH inhibited tumour growth in mice, downregulated the expression of MMP2 and MMP9, and partially reversed EMT. Alternatively, DCH resulted in cytoskeletal rearrangements of G401 cells. Conclusions. DCH, as an MMP inhibitor, is used for the first time in MRTK research, showing good antitumour effects by reversing EMT and potentially providing new therapeutic measures for MRTK treatment.

Human embryonic stem cell-specific role of YAP in maintenance of self-renewal and survival

Human embryonic stem cells (hESCs) have unique characteristics, such as self-renewal and pluripotency, which are distinct from those of other cell types. These characteristics of hESCs are tightly regulated by complex signaling mechanisms. In this study, we demonstrate that yes-associated protein (YAP) functions in an hESC-specific manner to maintain self-renewal and survival in hESCs. hESCs were highly sensitive to YAP downregulation to promote cell survival. Interestingly, hESCs displayed dynamic changes in YAP expression in response to YAP downregulation. YAP was critical for the maintenance of self-renewal. Additionally, the function of YAP in maintenance of self-renewal and cell survival was hESC-specific. Doxycycline upregulated YAP in hESCs and attenuated the decreased cell survival induced by YAP downregulation. However, decreased expression of self-renewal markers triggered by YAP downregulation and neural/cardiac differentiation were affected by doxycycline treatment. Collectively, the results reveal the mechanism underlying the role of YAP and the novel function of doxycycline in hESCs.

Doxycycline Suppresses Vasculogenic Mimicry in Human Pterygium Fibroblasts

PURPOSE

To explore the effect of doxycycline on vasculogenic mimicry (VM) formation and the potential mechanism in human pterygium fibroblasts in order to find novel targets for pterygium therapy.

METHODS

First, we demonstrate the existence of VM in 73 pterygium specimens by CD31 and periodic acid Schiff (PAS) dual staining. Then we used cell counting kit-8, clone formation assay and flow cytometry to prove the inhibitory effect of doxycycline on cell proliferation and apoptosis. The VM formation was evaluated through wound healing assay, cell transwell assay and three-dimensional cell culture combined with PAS staining. Finally, we used Western blot to testify the correlation of the VM and the factors in protein level preliminarily.

RESULTS

Our results showed that VM existed in human pterygium specimens exactly. Otherwise, in human pterygium fibroblasts, doxycycline induced a dose-dependent inhibitory effect on cell proliferation and apoptosis induction. Besides, doxycycline significantly suppressed vasculogenic mimicry tube formation, cell migration and invasion. Furthermore, doxycycline impaired the expression of MMP-9, MMP-2 and VEGF which may related to pterygium VM formation.

CONCLUSIONS

Doxycycline decelerated pterygium progression might be through inhibiting VM formation according to the downregulation of MMP-9, MMP-2 and VEGF, which may provide the basis of further studies involving doxycycline for pterygium treatment.

Drug Repurposing Strategies for Non-Cancer to Cancer Therapeutics

Global efforts invested for the prevention and treatment of cancer need to be repositioned to develop safe, effective, and economic anticancer therapeutics by adopting rational approaches of drug discovery. Drug repurposing is one of the established approaches to reposition old, clinically approved off patent noncancer drugs with known targets into newer indications. The literature review suggests key role of drug repurposing in the development of drugs intended for cancer as well as noncancer therapeutics. A wide category of noncancer drugs namely, drugs acting on CNS, anthelmintics, cardiovascular drugs, antimalarial drugs, anti-inflammatory drugs have come out with interesting outcomes during preclinical and clinical phases. In the present article a comprehensive overview of the current scenario of drug repurposing for the treatment of cancer has been focused. The details of some successful studies along with examples have been included followed by associated challenges.

Antibody-drug conjugate as targeted therapeutics against hepatocellular carcinoma: preclinical studies and clinical relevance

An antibody-drug conjugate (ADC) is an advanced chemotherapeutic option with immense promises in treating many tumor. They are designed to selectively attack and kill neoplastic cells with minimal toxicity to normal tissues. ADCs are complex engineered immunoconjugates that comprise a monoclonal antibody for site-directed delivery and cytotoxic payload for targeted destruction of malignant cells. Therefore, it enables the reduction of off-target toxicities and enhances the therapeutic index of the drug. Hepatocellular carcinoma (HCC) is a solid tumor that shows high heterogeneity of molecular phenotypes and is considered the second most common cause of cancer-related death. Studies show enormous potential for ADCs targeting GPC3 and CD24 and other tumor-associated antigens in HCC with their high, selective expression and show potential outputs in preclinical evaluations. The review mainly highlights the preclinical evaluation of different antigen-targeted ADCs such as MetFab-DOX, Anti-c-Met IgG-OXA, Anti CD 24, ANC-HN-01, G7mab-DOX, hYP7-DCand hYP7-PC, Anti-CD147 ILs-DOX and AC133-vcMMAF against hepatocellular carcinoma and its future relevance.

A Brief look at antitumor effects of doxycycline in the treatment of colorectal cancer and combination therapies

Colorectal cancer (CRC) is considered the second most frequent cancer globally and one of the deadliest malignancies in humans. On the other hand, over time and facing the challenges of cancer treatment, several therapeutic approaches, including surgery, radiotherapy, chemotherapy, and immunotherapy, are being developed. Evidence showed that combination therapies had given relatively satisfactory clinical outcomes in inhibiting tumor progression and increasing patient survival compared with monotherapy. Among the available compounds and drugs used in chemotherapy, doxycycline, an antimicrobial drug, has been suitable for treating several malignancies such as CRC. It has been revealed that doxycycline has anti-tumor properties and can help control tumor growth in various mechanisms, such as inhibiting anti-apoptotic and angiogenic proteins. In addition, studies have shown that combination therapy with doxycycline and other anti-tumor drugs, such as doxorubicin, anti-angiogenic factors, and anti-check-point blockers, can inhibit tumor progression. Therefore, this review summarized the anti-tumor mechanisms of doxycycline in CRC treatment and related combination therapies.

Targeting myeloid-derived suppressor cells to attenuate vasculogenic mimicry and synergistically enhance the anti-tumor effect of PD-1 inhibitor

Myeloid-derived suppressor cells (MDSCs) enhance the proliferation of endothelial cells to stimulate angiogenesis. However, many aggressive malignant tumors do not have endothelial cell-dependent blood vessels in the early stage and instead generate microcirculation by forming vasculogenic mimicry (VM). To date, the relationship between MDSCs and tumor cells remains the focus of ongoing studies. In this work, MDSCs were co-cultured with mouse melanoma cells and can enhance proliferation and VM formation of melanoma cells. For MDSCs targeting, doxycycline (DOX) was found to selectively suppress PMN-MDSCs but has no influence on T cells. In addition, DOX pretreatment substantially reduced the promoting ability of MDSCs for the VM formation of B16-F10 cells. DOX also inhibited tumor growth and enhanced the antitumor activity of PD-1 inhibitors in C57BL6 and BALB/c mice subcutaneously inoculated with B16-F10 and 4T1 cells, respectively. In conclusion, the combination of DOX and PD-1 inhibitor could be an anticancer strategy.

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MDSCs accumulated in the B16-F10 tumor-bearing mice

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MDSCs promote the formation of vasculogenic mimicry

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Doxycycline selectively suppressed PMN-MDSCs

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Doxycycline combined with PD-1 inhibitor significantly inhibited tumor growth

TET-dependent GDF7 hypomethylation impairs aqueous humor outflow and serves as a potential therapeutic target in glaucoma

Glaucoma is the leading cause of irreversible vision loss, affecting more than 70 million individuals worldwide. Circulatory disturbances of aqueous humor (AH) have long been central pathological contributors to glaucomatous lesions. Thus, targeting the AH outflow is a promising approach to treat glaucoma. However, the epigenetic mechanisms initiating AH outflow disorders and the targeted treatments remain to be developed. Studying glaucoma patients, we identified GDF7 (growth differentiation factor 7) hypomethylation as a crucial event in the onset of AH outflow disorders. Regarding the underlying mechanism, the hypomethylated GDF7 promoter was responsible for the increased GDF7 production and secretion in primary open-angle glaucoma (POAG). Excessive GDF7 protein promoted trabecular meshwork (TM) fibrosis through bone morphogenetic protein receptor type 2 (BMPR2)/Smad signaling and upregulated pro-fibrotic genes, α-smooth muscle actin (α-SMA) and fibronectin (FN). GDF7 protein expression formed a positive feedback loop in glaucomatous TM (GTM). This positive feedback loop was dependent on the activated TET (ten-eleven translocation) enzyme, which kept the GDF7 promoter region hypomethylated. The phenotypic transition in TM fortified the AH outflow resistance, thus elevating the intraocular pressure (IOP) and attenuating the nerve fiber layer. This methylation-dependent mechanism is also confirmed by a machine-learning model in silico with a specificity of 84.38% and a sensitivity of 89.38%. In rhesus monkeys, we developed GDF7 neutralization therapy to inhibit TM fibrosis and consequent AH outflow resistance that contributes to glaucoma. The neutralization therapy achieved high-efficiency control of the IOP (from 21.3 ± 0.3 to 17.6 ± 0.2 mmHg), a three-fold improvement in the outflow facility (from 0.1 to 0.3 μL/min · mmHg), and protection of nerve fibers. This study provides new insights into the epigenetic mechanism of glaucoma and proposes an innovative GDF7 neutralization therapy as a promising intervention.

Regulatory mechanisms and therapeutic targeting of vasculogenic mimicry in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a typical hyper-vascular solid tumor; aberrantly rich in tumor vascular network contributes to its malignancy. Conventional anti-angiogenic therapies seem promising but transitory and incomplete efficacy on HCC. Vasculogenic mimicry (VM) is one of functional microcirculation patterns independent of endothelial vessels which describes the plasticity of highly aggressive tumor cells to form vasculogenic-like networks providing sufficient blood supply for tumor growth and metastasis. As a pivotal alternative mechanism for tumor vascularization when tumor cells undergo lack of oxygen and nutrients, VM has an association with the malignant phenotype and poor clinical outcome for HCC, and may challenge the classic anti-angiogenic treatment of HCC. Current studies have contributed numerous findings illustrating the underlying molecular mechanisms and signaling pathways supporting VM in HCC. In this review, we summarize the correlation between epithelial-mesenchymal transition (EMT), cancer stem cells (CSCs) and VM, the role of hypoxia and extracellular matrix remodeling in VM, the involvement of adjacent non-cancerous cells, cytokines and growth factors in VM, as well as the regulatory influence of non-coding RNAs on VM in HCC. Moreover, we discuss the clinical significance of VM in practice and the potential therapeutic strategies targeting VM for HCC. A better understanding of the mechanism underlying VM formation in HCC may optimize anti-angiogenic treatment modalities for HCC.

Vascular mimicry: changing the therapeutic paradigms in cancer

Cancer is a major problem in the health system, and despite many efforts to effectively treat it, none has yet been fully successful. Angiogenesis and metastasis are considered as major challenges in the treatment of various cancers. Researchers have struggled to succeed with anti-angiogenesis drugs for the effective treatment of cancer, although new challenges have emerged in the treatment with the emergence of resistance to anti-angiogenesis and anti-metastatic drugs. Numerous studies have shown that different cancers can resist anti-angiogenesis drugs in a new process called vascular mimicry (VM). The studies have revealed that cells resistant to anti-angiogenesis cancer therapies are more capable of forming VMs in the in vivo and in vitro environment, although there is a link between the presence of VM and poor clinical outcomes. Given the importance of the VM in the challenges facing cancer treatment, researchers are trying to identify factors that prevent the formation of these structures. In this review article, it is attempted to provide a comprehensive overview of the molecules and main signaling pathways involved in VM phenomena, as well as the agents currently being identified as anti-VM and the role of VM in response to treatment and prognosis of cancer patients.

The anti-neoplastic effect of doxycycline in osteosarcoma as a metalloproteinase (MMP) inhibitor: a systematic review

Background

Osteosarcoma is a very aggressive primary bone tumour, affecting mainly young populations. Most cases diagnosed have distant macro- and micro-metastases at the time of diagnosis. Surgical resection with neoadjuvant and adjuvant therapies improves the overall and disease-free survival of patients. Doxycycline, a synthetic tetracycline, has been found to act either as an antibiotic drug or as a chemotherapeutic agent. Its anti-neoplastic role has been found to be significant, in vitro and in vivo laboratory trials, in various types of cancer, such as prostate, intestinal, central neural system cancers and osteosarcoma. Inhibition of metalloproteinases (MMPs) in different stages of tumour expansion is the most well-understood mechanism. MMPs are secreted molecules from various normal cells, such as fibroblasts, leucocytes and vascular smooth muscles, as well as from cells with high proliferative potential, such as tumour cells. In osteosarcoma, MMPs have been found to be overexpressed. MMPs help osteosarcoma cells survive, grow and produce metastases in distant sites, mainly in the lungs. Doxycycline blocks extracellular matrix and basic membrane degradation by suppressing MMP function. As a consequence, osteosarcoma cells lose their ability to invade and metastasize. Additionally, doxycycline eliminates the secretion of vascular endothelial growth factor (VEGF) and deprives the supply of circulating nutrients by its anti-angiogenesis action. The aim of this review is to evaluate doxycycline’s action against osteosarcoma cells as an MMP-inhibitor and interpret its usage as a chemotherapeutic agent.

Methods

We checked PubMed and Google Scholar for recently published data, on the tumour-supportive role of MMPs and VEGF in osteosarcoma cells. We further studied published experimental trials on the role of doxycycline as a tumour-suppressive agent via MMPs and VEGF inhibition.

Results

MMPs and VEGF have been found to play a fundamental role in osteosarcoma cells survival and high aggressiveness by in vitro, in vivo and clinical trials. Nevertheless, doxycycline has proved its tumour-suppressive effect by in vivo experimental trials in various cancers but not yet in osteosarcoma.

Conclusion

Doxycycline remains a promising chemotherapeutic agent against osteosarcoma via MMP inhibition, showing the need for further in vivo and clinical trials to be carried out in the future.

Paradigms of vascularization in melanoma: Clinical significance and potential for therapeutic targeting

Melanoma is the most aggressive form of skin cancer. Malignant melanoma in particular has a poor prognosis and although treatment has improved, drug resistance continues to be a challenge. Angiogenesis, the formation of blood vessels from existing microvessels, precedes the progression of melanoma from a radial growth phase to a malignant phenotype. In addition, melanoma cells can form networks of vessel-like fluid conducting channels through vasculogenic mimicry (VM). Both angiogenesis and VM have been postulated to contribute to the development of resistance to treatment and to enable metastasis. Also, the metastatic spread of melanoma is highly dependent on lymphangiogenesis, the formation of lymphatic vessels from pre-existing vessels. Interestingly, the design and clinical testing of drugs that target VM and lymphangiogenesis lag behind that of angiogenesis inhibitors. Despite this, antiangiogenic drugs have not significantly improved the overall survival of melanoma patients, thus necessitating the targeting of alternative mechanisms. In this article, I review the roles of the three paradigms of tissue perfusion, namely, angiogenesis, VM and lymphangiogenesis, in promoting melanoma progression and metastasis. This article also explores the latest development and potential opportunities in the therapeutic targeting of these processes.

Identification of the targeted therapeutic potential of doxycycline for a subset of gastric cancer patients

The identification of new drugs for the targeted therapy of gastric cancer remains an important need. The RAS/RAF/MEK/ERK/ELK1 signaling cascade is activated in many cancers, including gastric cancer. To identify the targetable inhibitors of the ERK/MAPK pathway, we performed a repurposing screening of a panel of antimicrobial agents in gastric cancer cells using an ERK/MAPK-driven firefly luciferase reporter assay. Multiple antibiotics were identified to inhibit ERK-mediated transcriptional activity. Among them, doxycycline showed high inhibition of ERK/MAPK-regulated transcriptional activity and the levels of ERK proteins. Doxycycline was further identified to inhibit the proliferation and the colony- and spheroid-forming potential of gastric cancer cells. By in vitro signaling pathway and genome-wide expression profiling analyses, doxycycline was identified to inhibit signaling pathways and transcriptional activities regulated by ER, Myc, E2F1, Wnt, SMAD2/3/4, Notch, and OCT4. Doxycycline was also found to activate p53-, ATF6-, NRF1/2-, and MTF1-mediated transcription and inhibit the transcription of histones, proteasomal genes, fibroblast growth factor, and other oncogenic factors. These observations show the multitargeting and targeted therapeutic features of doxycycline for a subset of gastric tumors.

Molecular Mechanisms and Anticancer Therapeutic Strategies in Vasculogenic Mimicry

Vasculogenic mimicry (VM) is a vascular formation mechanism used by aggressive tumor cells. VM provides an alternative pathway for adequate blood perfusion and challenges the traditional angiogenesis mechanism that depends only on endothelial cells (ECs), as VM-forming tumor cells express a mixed endothelial/tumor phenotype. VM is closely correlated with tumor invasion, migration, and progression. Hence, anticancer therapeutic strategies targeting VM biogenesis are essential. It is widely acknowledged that the VM formation mechanism involves multiple pathways. The purpose of this review is to describe the potential molecular mechanisms related to different pathways and discuss the involvement of microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) in VM formation. Moreover, we discuss the significance of VM in clinical practice and present new anticancer therapeutic strategies that target VM.

Fact or Fiction, It Is Time for a Verdict on Vasculogenic Mimicry?

The term vasculogenic mimicry (VM) refers to the capacity of certain cancer cells to form fluid-conducting structures within a tumor in an endothelial cell (EC)-free manner. Ever since its first report by Maniotis in 1999, the existence of VM has been an extremely contentious issue. The overwhelming consensus of the literature suggests that VM is frequently observed in highly aggressive tumors and correlates to lower patient survival. While the presence of VM in vivo in animal and patient tumors are claimed upon the strong positive staining for glycoproteins (Periodic Acid Schiff, PAS), it is by no means universally accepted. More controversial still is the existence of an in vitro model of VM that principally divides the scientific community. Original reports demonstrated that channels or tubes occur in cancer cell monolayers in vitro when cultured in matrigel and that these structures may support fluid movement. However, several years later many papers emerged stating that connections formed between cancer cells grown on matrigel represented VM. We speculate that this became accepted by the cancer research community and now the vast majority of the scientific literature reports both presence and mechanisms of VM based on intercellular connections, not the presence of fluid conducting tubes. In this opinion paper, we call upon evidence from an exhaustive review of the literature and original data to argue that the majority of in vitro studies presented as VM do not correspond to this phenomenon. Furthermore, we raise doubts on the validity of concluding the presence of VM in patient samples and animal models based solely on the presence of PAS+ staining. We outline the requirement for new biomarkers of VM and present criteria by which VM should be defined in vitro and in vivo.

Doxycycline, salinomycin, monensin and ivermectin repositioned as cancer drugs

Chemotherapy is one of the standard methods for the treatment of malignant tumors. It aims to cause lethal damage to cellular structures, mainly DNA. Noteworthy, in recent years discoveries of novel anticancer agents from well-known antibiotics have opened up new treatment pathways for several cancer diseases. The aim of this review article is to describe new applications for the following antibiotics: doxycycline (DOX), salinomycin (SAL), monensin (MON) and ivermectin (IVR) as they are known to show anti-tumor activity, but have not yet been introduced into standard oncological therapy. To date, these agents have been used for the treatment of a broad-spectrum of bacterial and parasitic infectious diseases and are widely available, which is why they were selected. The data presented here clearly show that the antibiotics mentioned above should be recognised in the near future as novel agents able to eradicate cancer cells and cancer stem cells (CSCs) across several cancer types.

The role of sema4D in vasculogenic mimicry formation in non-small cell lung cancer and the underlying mechanisms

Vasculogenic mimicry (VM) is a special vascular pattern in malignant tumors, which is composed of highly aggressive tumor cells. This tumor cell-mediated blood supply pattern is closely associated with a poor prognosis in cancer patients. The interaction of axon guidance factor Sema4D and its high affinity receptor plexinB1 could activate small GTPase RhoA and its downstream ROCKs; this process has an active role in the migration of endothelial cells and tumor angiogenesis. Here, we have begun to uncover the role of this pathway in VM formation in non-small cell lung cancer (NSCLC). First, we confirmed this special form of vasculature in NSCLC tissues and found the existence of VM channels in tumor tissues was correlated with Sema4D expression. Further, we found that inhibition of Sema4D in the human NSCLC cells H1299 and HCC827 reduces VM formation both in vitro and in vivo. Moreover, we demonstrated that downregulating the expression of plexinB1 by siRNA expressing vectors and inhibiting the RhoA/ROCK signaling pathway using fasudil can reduce VM formation of H1299 and HCC827 cells. Finally, we found that suppression of Sema4D leads to less stress fibers and depleted the motility of H1299 and HCC827 cells. Collectively, our study implicates Sema4D plays an important role in the process of VM formation in NSCLC through activating the RhoA/ROCK pathway and regulating tumor cell plasticity and migration. Modulation of the Sema4D/plexinB1 and downstream RhoA/ROCK pathway may prevent the tumor blood supply through the VM pattern, which may eventually halt growth and metastasis of NSCLC.

LOXL2 promotes vasculogenic mimicry and tumour aggressiveness in hepatocellular carcinoma

Lysyl oxidase‐like 2 (LOXL2) has shown to promote metastasis and poor prognosis in hepatocellular carcinoma (HCC). Also, we have previously reported that vasculogenic mimicry (VM) is associated with invasion, metastasis and poor survival in HCC patients. In the present study, we investigated molecular function of LOXL2 in HCC and VM. We used the immunohistochemical and CD31/periodic acid‐Schiff double staining to detect the relationship between LOXL2 and VM formation. We performed the gain and loss of function studies and analysed the migratory, invasion and tube formation in HCC cell lines. We analysed the function of LOXL2 in VM formation and HCC metastasis both in vitro and in vivo. We have showed that LOXL2 was overexpression in HCC and was positively correlated with tumour grade, metastasis, VM formation and poor survival in 201 HCC patients. Secondly, our studies have showed that LOXL2 overexpression in HCC cells significantly promoted migration, invasion and tube formation. Finally, we found that LOXL2 may increase SNAIL expression, thereby enabling VM. Our study indicated that LOXL2 may promote VM formation and tumour metastasis by collaborating with SNAIL in HCC. What's more, the overexpression of LOXL2 indicated a poor prognosis in HCC patients.

Overview of advances in vasculogenic mimicry - a potential target for tumor therapy

Vasculogenic mimicry (VM) describes the process utilized by highly aggressive cancer cells to generate vascular-like structures without the presence of endothelial cells. VM has been vividly described in various tumors and participates in cancer progression dissemination and metastasis. Diverse molecular mechanisms and signaling pathways are involved in VM formation. Furthermore, the patterning characteristics of VM, detected with molecular imaging, are being investigated for use as a tool to aid clinical practice. This review explores the most recent studies investigating the role of VM in tumor induction. Indeed, the recognition of these advances will increasingly affect the development of novel therapeutic target strategies for VM in human cancer.

Mechanism of fibrosis inhibition in laser induced choroidal neovascularization by doxycycline

To explore the mechanisms underlying doxycycline suppression of fibrosis in laser-induced choroidal neovascularization (LCNV), C57BL/6J male mice (aged from 6 to 8 weeks) received intraperitoneal injections of PBS/doxycycline solution from one day before laser injury until they were sacrificed. Leakage was assessed by FA, and CNV (stained by IB4) or fibrosis (stained by collagen type I) size was measured. The percentage of Pan-keratin⁺α-SMA⁺ cells was counted in the eyes' cryostat sections by immunohistochemistry. qPCR was used to measure the mRNA of markers of pan-macrophages, M1 and M2-type macrophages (M1 and M2), markers of EMT, and markers in the downstream of STAT6 signaling. Western blotting was used to analyze the expression of Arg-1, α-SMA, E-cadherin, pSTAT6 and STAT6. Our data showed that doxycycline inhibited leakage from CNV, areas of CNV on day 7 and day 14, and suppressed fibrosis, and the ratio of fibrotic/angiogenic areas during day 7 to day 35. We also showed attenuation of EMT in the doxycycline group. The percentage of Pan-keratin⁺α-SMA⁺ cells was lower in the doxycycline group than in the control group. The mRNA and protein levels of mesenchymal markers were downregulated in the doxycycline group, while the epithelial marker was upregulated. In addition, our data showed that the protein expression of Arg-1, the mRNA expression of M1 and M2-markers, were both inhibited by doxycycline, while the level of pan-macrophages (f4/80) showed no significant difference in two groups. Finally, our results showed that doxycycline was able to modulate the STAT6 signaling in transcript and protein levels. Accordingly, we suggested that the mechanism of doxycycline-mediated inhibition of fibrosis in CNV occurs through the STAT6 pathway.

Angiogenesis and vasculogenic mimicry are inhibited by 8-Br-cAMP through activation of the cAMP/PKA pathway in colorectal cancer

Introduction

Vasculogenic mimicry (VM) describes the formation of an epithelial-independent tumor microcirculation system that differs from traditional angiogenesis. Angiogenesis and the formation of VM are closely related through the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway and the epithelial–mesenchymal transition (EMT) process.

Materials and methods

In this study, 8-Br-cAMP, a cAMP analog and PKA activator, was used to activate the cAMP/PKA pathway to evaluate the effects of cAMP/PKA on angiogenesis and VM in colorectal cancer (CRC) cells. We used a syngeneic model of CRC in BALB/c mice.

Results

We discovered that treatment with 8-Br-cAMP significantly reduced tumor number compared to control mice after the 7th, 14th, and 28th days of treatment. VM was evaluated by periodic acid–schiff (PAS)–CD31 staining, and we found that VM was inhibited by 8-Br-cAMP treatment in vivo. Immunohistochemistry confirmed the inhibition of vascular endothelial growth factor (VEGF) and cAMP and the activation of PKA by 8-Br-cAMP; quantitative real-time-PCR (qRT-PCR) demonstrated that 8-Br-cAMP regulated the expression of vascular endothelial (VE)-cadherin, matrix metalloproteinase 2 (MMP2), ephrin type-A receptor 2 (EphA2), and VEGF in vivo. Experiments in vitro revealed that treatment with 8-Br-cAMP and U0126 decreased VEGF expression through PKA–ERK in CT26 cells by qRT-PCR. We further confirmed that tube formation of human umbilical vein endothelial cells was inhibited by 8-Br-cAMP in vitro.

Discussion

This study demonstrates that angiogenesis and VM are inhibited by 8-Br-cAMP treatment. Our data indicate that 8-Br-cAMP acts through the cAMP/PKA–ERK pathway and through EMT processes in CRC. These findings provide an insight into mechanisms of CRC and suggest that the cAMP/PKA–ERK pathway is a novel potential therapeutic target for the treatment of CRC.

Vasculogenic mimicry in hepatocellular carcinoma contributes to portal vein invasion

Portal vein invasion (PVI) is common in hepatocellular carcinoma (HCC) and largely contributes to tumor recurrence after radical tumor resection or liver transplantation. Vasculogenic mimicry (VM) was an independent vascular system lined with tumor cells and associated with poor prognosis of HCC. The present study was conducted to evaluate the relationship between VM and portal vein invasion. A total of 44 HCC cases receiving anatomic liver resection were included in the study and were divided into groups with and without PVI. The prevalence of VM in each group was examined by CD34-PAS dual staining. The regulatory molecules of VM formation such as Notch1, Vimentin and matrix metalloproteinases (MMPs) were investigated by immunohistochemical staining. Analysis was performed to explore the association of PVI, VM and the VM regulatory molecules. PVI was found in 40.91% (18/44) cases and VM was found in 38.64% (17/44) cases in total samples. The incidence of VM was 72.22% (13/18) in PVI group while it was 15.38% (4/26) in non-PVI group (P<0.001), VM formation was positively correlated with PVI (r=0.574, P<0.001). The VM forming regulatory molecules such as Notch1, Vimentin, MMP-2 and MMP-9 were found to be correlated with PVI in HCC patients. Taken together, our results suggested that VM formation, alone with its regulatory molecules, is the promoting factor of PVI in hepatocellular carcinoma.

Epithelial-to-endothelial transition and cancer stem cells: two cornerstones of vasculogenic mimicry in malignant tumors

Vasculogenic mimicry (VM) is a functional microcirculation pattern in malignant tumors accompanied by endothelium-dependent vessels and mosaic vessels. VM has been identified in more than 15 solid tumor types and is associated with poor differentiation, late clinical stage and poor prognosis. Classic anti-angiogenic agents do not target endothelium-dependent vessels and are not efficacious against tumors exhibiting VM. Further insight into the molecular signaling that triggers and promotes VM formation could improve anti-angiogenic therapeutics. Recent studies have shown that cancer stem cells (CSCs) and epithelium-to-endothelium transition (EET), a subtype of epithelial-to-mesenchymal transition (EMT), accelerate VM formation by stimulating tumor cell plasticity, remodeling the extracellular matrix (ECM) and connecting VM channels with host blood vessels. VM channel-lining cells originate from CSCs due to expression of EMT inducers such as Twist1, which promote EET and ECM remodeling. Hypoxia and high interstitial fluid pressure in the tumor microenvironment induce a specific type of cell death, linearly patterned programmed cell necrosis (LPPCN), which spatially guides VM and endothelium-dependent vessel networks. This review focuses on the roles of CSCs and EET in VM, and on possible novel anti-angiogenic strategies against alternative tumor vascularization.

Nodal signaling promotes vasculogenic mimicry formation in breast cancer via the Smad2/3 pathway

Vasculogenic mimicry (VM) is a nonangiogenesis-dependent pathway that promotes tumor growth and disease progression. Nodal signaling has several vital roles in both embryo development and cancer progression. However, the effects of Nodal signaling on VM formation in breast cancer and its underlying mechanisms are ill-defined. We analyzed the relationship between Nodal signaling and VM formation in one hundred human breast cancer cases and the results showed that the expression of Nodal was significantly correlated with VM formation, tumor metastasis, differentiation grade, TNM stage and poor prognosis. Furthermore, up-regulation of Nodal expression promoted VM formation of breast cancer cells in vitro and in vivo. Knockdown of Nodal expression restrained VM formation. In addition, Nodal induced EMT and up-regulated the expression of Slug, Snail and c-Myc. We found that blocking the Smad2/3 pathway by administering SB431542 inhibited VM formation in breast cancer cell lines and xenografts. Taken together, Nodal signaling through the Smad2/3 pathway up-regulated Slug, Snail and c-Myc to induce EMT, thereby promoting VM formation. Our study suggests that the Nodal signaling pathway may serve as a therapeutic target to inhibit VM formation and improve prognosis in breast cancer patients.

CDH1 promoter methylation in patients with cervical carcinoma: a systematic meta-analysis with trial sequential analysis

AIM

This study was performed to evaluate the correlation between CDH1 promoter methylation and cervical cancer.

METHODS

Trial sequential analysis was conducted to evaluate the required information size.

RESULTS

A total of 15 studies with 950 cervical cancers and 829 controls were identified. CDH1 promoter methylation was higher in cervical cancer than in cervical intraepithelial neoplasia lesions and normal cervical tissues. Subgroup analysis of ethnicity showed that CDH1 promoter methylation correlated with cervical cancer in Caucasians, but not in Asians. CDH1 promoter methylation was higher in cervical cancer cytology samples than in normal cytology samples. It was higher in squamous cell carcinoma than adenocarcinoma, but was not correlated with tumor stage, grade and overall survival.

CONCLUSION

CDH1 promoter methylation may be correlated with cervical cancer carcinogenesis, especially for Caucasians. It was associated with histological subtypes. Trial sequential analysis showed that more studies are needed.

Down-regulating Myoferlin inhibits the vasculogenic mimicry of melanoma via decreasing MMP-2 and inducing mesenchymal-to-epithelial transition

Vasculogenic mimicry (VM) constitutes a novel approach for tumour blood supply and contributes to tumour metastasis and poor prognosis in patients with melanoma. Myoferlin (MYOF), a type II membrane protein involved in membrane regeneration and repair, is elevated in several malignant tumours, especially in advanced melanomas. This study aims to investigate the role and mechanism of MYOF in the regulation of VM. VM structures were found in 14 of 52 tested melanoma samples, and high MYOF expression correlated with VM structures. According to Kaplan–Meier survival curves, VM channels and elevated MYOF expression both correlated with poor prognosis in melanoma patients. Down‐regulation of MYOF by siRNA severely impaired the capability of A375 cells to form VM structures in vitro. Further studies demonstrated MYOF knockdown inhibited cell migration and invasion, which is required for VM formation, via decreasing MMP‐2 expression as evidenced by Western blotting, RT‐RCP and ELISA results. SB‐3CT, a specific inhibitor of MMP‐2, showed similar inhibiting effects with siMYOF, further supporting that MYOF down‐regulation inhibits MMP‐2 expression to affect VM formation. Moreover, MYOF knockdown suppress VM formation by A375 cells by inducing mesenchymal‐to‐epithelial transition (MET). After down‐regulating MYOF, focal adhesions were enlarged and A375 cells developed into a clear epithelial morphology. Such cells acquired the expression of E‐cadherin at adherens junctions along with a loss of mesenchymal markers, such as Vimentin and Twist1. In conclusion, MYOF plays an important role in VM and knockdown of MYOF suppresses VM formation via decreasing MMP‐2 and inducing MET in A375 melanoma cells.

Matrix Metalloproteinases: A challenging paradigm of cancer management

Matrix metalloproteinases (MMPs) are members of zinc-dependent endopeptidases implicated in a variety of physiological and pathological processes. Over the decades, MMPs have been studied for their role in cancer progression, migration, and metastasis. As a result, accumulated evidence of MMPs incriminating role has made them an attractive therapeutic target. Early generations of broad-spectrum MMP inhibitors exhibited potent inhibitory activities, which subsequently led to clinical trials. Unexpectedly, these trials failed to meet the desired goals, mainly due to the lack of efficacy, poor oral bioavailability, and toxicity. In this review, we discuss the regulatory role of MMPs in cancer progression, current strategies in targeting MMPs for cancer treatment including prodrug design and tumor imaging, and therapeutic value of MMPs as biomarkers in breast, lung, and prostate cancers.

Derivatives of alkyl gallate triphenylphosphonium exhibit antitumor activity in a syngeneic murine model of mammary adenocarcinoma

We previously demonstrated that alkyl gallates coupled to triphenylphosphine have a selective and efficient antiproliferative effect by inducing mitochondrial uncoupling in vitro due to the increased mitochondrial transmembrane potential of tumor cells. Therefore, in this work, the in vivo antitumor activities of alkyl gallate triphenylphosphonium derivatives (TPP+C8, TPP+C10 and TPP+C12) were evaluated in a syngeneic murine model of breast cancer. We found that TPP+C10 increased the cytosolic ADP/ATP ratio and significantly increased the AMP levels in a concentration-dependent manner in TA3/Ha murine mammary adenocarcinoma cells. Interestingly, TPP+C10 induced a decrease in the levels of cellular proliferation markers and promoted caspase-3 activation in tumor-bearing mice. Additionally, TPP+C10 inhibited tumor growth in the syngeneic mouse model. Importantly, 30days of intraperitoneal (i.p.) administration of the combination of TPP+C10 (10mg/kg/48h) and the antibiotic doxycycline (10mg/kg/24h) completely eliminated the subcutaneous tumor burden in mice (n=6), without any relapses at 60days post-treatment. This enhancement of the individual activities of TPP+C10 and doxycycline is due to the uncoupling of oxidative phosphorylation by TPP+C10 and the inhibition of mitochondrial biogenesis by doxycycline, as demonstrated by loss of mitochondrial mass and overexpression of PGC1-α as an adaptive response. Moreover, i.p. administration of TPP+C10 (10mg/kg/24h) to healthy mice did not produce toxicity or damage in organs important for drug metabolism and excretion, as indicated by hematological, biochemical and histological assessments. These findings suggest that the combination of TPP+C10 with doxycycline is a valuable candidate therapy for breast cancer management.

Drug repurposing in cancer

Cancer is a major health issue worldwide, and the global burden of cancer is expected to increase in the coming years. Whereas the limited success with current therapies has driven huge investments into drug development, the average number of FDA approvals per year has declined since the 1990s. This unmet need for more effective anti-cancer drugs has sparked a growing interest for drug repurposing, i.e. using drugs already approved for other indications to treat cancer. As such, data both from pre-clinical experiments, clinical trials and observational studies have demonstrated anti-tumor efficacy for compounds within a wide range of drug classes other than cancer. Whereas some of them induce cancer cell death or suppress various aspects of cancer cell behavior in established tumors, others may prevent cancer development. Here, we provide an overview of promising candidates for drug repurposing in cancer, as well as studies describing the biological mechanisms underlying their anti-neoplastic effects.

HnRNPM and CD44s expression affects tumor aggressiveness and predicts poor prognosis in breast cancer with axillary lymph node metastases

HnRNPM is an essential splicing factor and its expression is closely correlated with invasion and metastasis of tumor cells. The CD44 cell adhesion molecule is aberrantly expressed in many breast tumors and CD44 splice variants have been implicated in specific oncogenic signaling pathways. To investigate the clinical significance and biological function of hnRNPM, immunohistochemistry, quantitative, and semiquantitative polymerase chain reaction, lentiviral transfection system and transwell invasion assays were performed. We found that hnRNPM expression was significantly upregulated in breast cancer tissues compared with benign breast lesions. Although there was no significant correlation between hnRNPM and total CD44 protein or mRNA level, there was a negative correlation between hnRNPM and CD44v6. HnRNPM and CD44s expression showed positive correlation and in particular, they were dually expressed in breast cancer tissues. Interestingly, cancer stem cells marker, ALDH1⁺ phenotype was positively associated with overexpression of CD44s or hnRNPM and negatively related to CD44v6. Patients with high hnRNPM tended to have higher levels of CD44s, shorter overall survival (OS) and higher rates of lymph node metastases (LNM). Remarkably, Kaplan-Meier and Cox regression analyses displayed that hnRNPM⁺ or CD44s^high was a poor prognostic factor for OS of patients with LNM. Upregulation of hnRNPM in MCF-7 cells caused a significant increase in cell invasion, and this effect may occur through the regulation of CD44s expression. In conclusion, overexpression of hnRNPM promotes breast cancer aggressiveness by regulating the level of CD44s, indicates a poor prognosis for patients with LNM, and has potential as therapeutic targets.

TRA2A Promoted Paclitaxel Resistance and Tumor Progression in Triple-Negative Breast Cancers via Regulating Alternative Splicing

Treatment of triple-negative breast cancer (TNBC) has been challenging, and paclitaxel resistance is one of the major obstacles to the better prognosis. Deregulation of alternative splicing (AS) may contribute to tumor progression and chemotherapy resistance. Human AS factor TRA2 has two separate gene paralogs encoding TRA2A and TRA2B proteins. TRA2B is associated with cancer cell survival and therapeutic sensitivity. However, the individual role of TRA2A in cancer progression has not been reported. Here we report that TRA2A facilitates proliferation and survival and migration and invasion of TNBC cells. In addition, TRA2A promotes paclitaxel resistance of TNBC by specifically controlling cancer-related splicing, which is independent of other splicing factors. TRA2A overexpression could promote AS of CALU, RSRC2, and PALM during paclitaxel treatment of TNBC cells. The isoform shift of RSRC2 from RSRC2s to RSRC2l leads to a decreased RSRC2 protein expression, which could contribute to TNBC paclitaxel resistance. TRA2A can regulate RSRC2 AS by specifically binding upstream intronic sequence of exon4. Strikingly, TRA2A expression is increased dramatically in patients with TNBC, and has a close relationship with decreased RSRC2 expression; both are associated with poor survival of TNBC. Collectively, our findings suggest that paclitaxel targets the TRA2A-RSRC2 splicing pathway, and deregulated TRA2A and RSRC2 expression may confer paclitaxel resistance. In addition to providing a novel molecular mechanism of cancer-related splicing dysregulation, our study demonstrates that expression of TRA2A in conjunction with RSRC2 may provide valuable molecular biomarker evidence for TNBC clinical treatment decisions and patient outcome. Mol Cancer Ther; 16(7); 1377-88. ©2017 AACR.

The Expression and Functional Significance of Runx2 in Hepatocellular Carcinoma: Its Role in Vasculogenic Mimicry and Epithelial-Mesenchymal Transition

The transcription factor Runx2 has been reported to promote epithelial-mesenchymal transition (EMT) in many tumors. Vasculogenic mimicry (VM) is described as the mimicry of endothelial cells by tumor cells to form microvascular tubes in aggressive tumors. Galectin-3 has been reported to regulate cell invasion, migration, and VM formation; it could be regulated by Runx2. However, the relationship between Runx2, Galectin-3, EMT, and VM has not been studied in hepatocellular carcinoma (HCC). We examined Runx2 expression in 89 human HCC samples and found Runx2 expression was associated with VM. Clinical-pathological data analysis revealed that Runx2 expression was associated with a shorter survival period. Overexpression of Runx2 promoted EMT and enhanced cell migration, invasion, and VM formation in HepG2 cells. Conversely, the downregulation of Runx2 inhibited EMT and reduced cell invasion, migration, and VM formation in SMMC7721. Galectin-3 expression declined following the downregulation of Runx2 in HepG2 cells, and increased in SMMC7721 cells after Runx2 knockdown. We consistently demonstrated that the downregulation of LGALS3 in HepG2-Runx2 cells reduced cell migration; invasion and VM formation; while upregulation of LGALS3 in SMMC7721-shRunx2 cells enhanced cell migration, invasion, and VM formation. The results indicate that Runx2 could promote EMT and VM formation in HCC and Galectin-3 might have some function in this process.

Doxycycline inhibits the cancer stem cell phenotype and epithelial-to-mesenchymal transition in breast cancer

Experimental evidence suggest that breast tumors originate from breast cancer stem cells (BCSCs), and that mitochondrial biogenesis is essential for the anchorage-independent clonal expansion and survival of CSCs, thus rendering mitochondria a significant target for novel treatment approaches. One of the recognized side effects of the FDA-approved drug, doxycycline is the inhibition of mitochondrial biogenesis. Here we investigate the mechanism by which doxycycline exerts its inhibitory effects on the properties of breast cancer cells and BCSCs, such as mammosphere forming efficiency, invasion, migration, apoptosis, the expression of stem cell markers and epithelial-to-mesenchymal transition (EMT) related markers of breast cancer cells. In addition, we explored whether autophagy plays a role in the inhibitory effect of doxycycline on breast cancer cells. We find that doxycyline can inhibit the viability and proliferation of breast cancer cells and BCSCs, decrease mammosphere forming efficiency, migration and invasion, and EMT of breast cancer cells. Expression of stem cell factors Oct4, Sox2, Nanog and CD44 were also significantly downregulated after doxycycline treatment. Moreover, doxycycline could down-regulate the expression of the autophagy marker LC-3BI and LC-3BII, suggesting that inhibiting autophagy may be responsible in part for the observed effects on proliferation, EMT and stem cell markers. The potent inhibition of EMT and cancer stem-like characteristics in breast cancer cells by doxycycline treatment suggests that this drug can be repurposed as an anti-cancer drug in the treatment of breast cancer patients in the clinic.

Escaping Antiangiogenic Therapy: Strategies Employed by Cancer Cells

Tumor angiogenesis is widely recognized as one of the "hallmarks of cancer". Consequently, during the last decades the development and testing of commercial angiogenic inhibitors has been a central focus for both basic and clinical cancer research. While antiangiogenic drugs are now incorporated into standard clinical practice, as with all cancer therapies, tumors can eventually become resistant by employing a variety of strategies to receive nutrients and oxygen in the event of therapeutic assault. Herein, we concentrate and review in detail three of the principal mechanisms of antiangiogenic therapy escape: (1) upregulation of compensatory/alternative pathways for angiogenesis; (2) vasculogenic mimicry; and (3) vessel co-option. We suggest that an understanding of how a cancer cell adapts to antiangiogenic therapy may also parallel the mechanisms employed in the bourgeoning tumor and isolated metastatic cells delivering responsible for residual disease. Finally, we speculate on strategies to adapt antiangiogenic therapy for future clinical uses.

C-myc overexpression drives melanoma metastasis by promoting vasculogenic mimicry via c-myc/snail/Bax signaling

c-Myc is a well-characterized proto-oncogene that induces cellular transformation and modulates programmed cell death. While recent studies have demonstrated high expression of c-Myc protein in advanced and metastatic melanoma, the clinical and biological implications remain to be fully elucidated. In this study, we investigated the effect of c-Myc overexpression in melanoma tumorigenesis. Clinicopathological analysis demonstrated that c-Myc expression positively correlated with the formation of vasculogenic mimicry (VM) and linearly patterned programmed cell necrosis (LPPCN). Clinically, high c-Myc expression was significantly associated with distant metastasis and poor prognosis, while biologically, c-Myc overexpression led to significant increases in cell motility, invasiveness and metastasis. Moreover, c-Myc induced the formation of VM and promoted the expression of epithelial-mesenchymal transition (EMT)-associated protein Snail both in vivo and in vitro. High expression of c-Myc increased Bax expression in hypoxic conditions and induced cell apoptosis. Taken together, we conclude that c-Myc overexpression promotes the formation of VM by EMT and LPPCN in melanoma. Our improved understanding of the clinical and biological effects of c-Myc overexpression in melanoma highlights the incomplete understanding of this oncogene, and indicates that c-Myc is a potential therapeutic target of this disease.

KEY MESSAGE

High c-Myc expression is associated with tumor metastasis and poor prognosis in human melanoma. c-Myc upregulates Snail expression to promote EMT via the TGF-β/Snail/Ecadherin signal pathway. c-Myc leads to cell death by upregulating Bax expression causing a lower Bcl2/Bax ratio under severe hypoxic conditions. c-Myc promotes vasculogenic mimicry and linearly patterned programmed cell necrosis.

Cystatin E/M Suppresses Tumor Cell Growth through Cytoplasmic Retention of NF-κB

We and others have shown that the cystatin E/M gene is inactivated in primary human tumors, pointing to its role as a tumor suppressor gene. However, the molecular mechanism of tumor suppression is not yet understood. Using plasmid-directed cystatin E/M gene overexpression, a lentivirus-mediated tetracycline-inducible vector system, and human papillomavirus 16 (HPV 16) E6 and E7 gene-immortalized normal human epidermal keratinocytes, we demonstrated intracellular and non-cell-autonomous apoptotic growth inhibition of tumor cell lines and that growth inhibition is associated with cytoplasmic retention of NF-κB. We further demonstrated decreased phosphorylation of IκB kinase (IKKβ) and IκBα in the presence of tumor necrosis factor alpha (TNF-α), confirming the role of cystatin E/M in the regulation of the NF-κB signaling pathway. Growth suppression of nude mouse xenograft tumors carrying a tetracycline-inducible vector system was observed with the addition of doxycycline in drinking water, confirming that the cystatin E/M gene is a tumor suppressor gene. Finally, immunohistochemical analyses of cervical carcinoma in situ and primary tumors have shown a statistically significant inverse relationship between the expression of cystatin E/M and cathepsin L and a direct relationship between the loss of cystatin E/M expression and nuclear expression of NF-κB. We therefore propose that the cystatin E/M suppressor gene plays an important role in the regulation of NF-κB.

Twist1-related miR-26b-5p suppresses epithelial-mesenchymal transition, migration and invasion by targeting SMAD1 in hepatocellular carcinoma

Twist1 is well known to induce epithelial-mesenchymal transition (EMT) and promote tumor metastasis. MicroRNAs (miRNAs) are involved in the EMT process and are associated with metastasis in hepatocellular carcinoma (HCC). In the present study, microRNA-26b-5p (miR-26b-5p) expression was consistently and significantly downregulated in HepG2-Twist1 HCC cell lines compared with HepG2-vector cell lines using microarrays (the HepG2-Twist1 cell line can stably express Twist1). miR-26b- 5p downregulation was directly mediated by Twist1 through binding to the promoter region of miR-26b-5p in HepG2-Twist1 cells by ChIP-seq technology. Both gain- and loss-of-function studies showed that miR-26b-5p dramatically suppressed EMT and the invasion ability of HCC cells in vitro. Using mouse models, tumors derived from miR- 26b-5p-overexpressed HCC cells exhibited a significant reduction in tumorigenicity compared with the control group. Subsequent investigation revealed that miR-26b-5p directly inhibited SMAD family member 1 (SMAD1) expression. miR-26b-5p repressed BMP4/Smad1 signaling following SMAD1 inhibition. Overexpression of SMAD1 reversed the function of miR-26b-5p. In human HCC tissues and mouse xenograft tumors, miR-26b-5p levels were inversely correlated with SMAD1 expression as well as metastasis.

CONCLUSION

miR-26b-5p suppresses Twist1-induced EMT, invasion, and metastasis of HCC cells by targeting SMAD1 and BMP4/Smad1 signaling. This suggests a promising application for miR-26b-5p in anti-HCC therapy.

miR-27a-3p suppresses tumor metastasis and VM by down-regulating VE-cadherin expression and inhibiting EMT: an essential role for Twist-1 in HCC

Twist-1 and miRNAs have been reported to be associated with tumor metastasis and angiogenesis. However, the relationship between Twist-1 and miRNAs and the function of miRNAs remain largely undefined. We aimed to reveal the Twist-1-related miRNA expression profile and to determine whether Twist-1 functions in tumor metastasis and vasculogenic mimicry (VM) by regulating miRNA expression in hepatocellular carcinoma (HCC). Results showed that the expression of miR-27a-3p was consistently down-regulated in HCC cell lines and tissue samples displaying high expression of Twist-1. Both loss- and gain-of-function assays revealed suppressive effects of miR-27a-3p. Low miR-27a-3p expression was significantly associated with early metastasis in HCC. Subsequent investigations revealed that miR-27a-3p mediated the inhibition of epithelial–mesenchymal transition (EMT). Additional experiments showed that VE-cadherin is a direct target of miR-27a-3p and further demonstrated the critical role of miR-27a-3p in suppressing tumor metastasis and VM. Conclusions: Twist-1 up-regulation in HepG2 cells resulted in the differential expression of 18 miRNAs. Among them, miR-27a-3p deregulation contributed to VM and metastasis. The miR-27a-3p-mediated down-regulation of VE-cadherin and inhibition of EMT may be essential for Twist-1 to induce tumor metastasis and VM. Our findings highlight the importance of miR-27a-3p and suggest a promising new strategy for anti-HCC therapy.

Antibiotic drug tigecycline inhibits melanoma progression and metastasis in a p21CIP1/Waf1-dependent manner

Antibiotics are common drugs with low toxicity but high effectiveness. They have been suggested to be drug candidates for cancer therapy in recent years. Here, we tried to investigate the antitumour effect of tigecycline on malignant melanoma. We showed that tigecycline dramatically inhibited cell proliferation and induced cell cycle arrest at G0/G1 phase. At the same time, tigecycline suppressed cell invasion and migration through preventing epithelial-mesenchymal transition (EMT) process. In addition, tigecycline also significantly blocked tumor growth in vivo. Expression of cell cycle-related proteins were investigated and resulted in downregulation of G1/S checkpoint proteins, such as CDK2 and Cyclin E. However, cyclin-dependent kinase inhibitor 1 (CDKN1A, p21(CIP1/Waf1)) was downregulated after tigecycline treatment, which was not conformed to its conventional function. To explain this, we overexpressed p21 in melanoma cells. We found that p21 overexpression significantly rescued tigecycline-induced cell proliferation inhibition as well as migration and invasion suppression. Taken together, our results revealed that the essential role of p21 in the inhibitory effect of tigecycline on proliferation, migration and invasion of melanoma. Tigecycline might act as a candidate therapeutic drug for treatment of patients suffering from malignant melanoma.