WAVE3-NFκB interplay is essential for the survival and invasion of cancer cells

Role of WAVE3 as an of actin binding protein in the pathology of triple negative breast cancer

Breast cancer, a prevalent global health concern, has sparked extensive research efforts, particularly focusing on triple negative breast cancer (TNBC), a subtype lacking estrogen receptor (ER), progesterone receptor, and epidermal growth factor receptor. TNBC's aggressive nature and resistance to hormone-based therapies heightens the risk of tumor progression and recurrence. Actin-binding proteins, specifically WAVE3 from the Wiskott-Aldrich syndrome protein (WASP) family, have emerged as major drivers in understanding TNBC biology. This review delves into the intricate molecular makeup of TNBC, shedding light on actin's fundamental role in cellular processes. Actin, a structural element in the cytoskeleton, regulates various cellular pathways essential for homeostasis. Its dynamic nature enables functions such as cell migration, motility, intracellular transport, cell division, and signal transduction. Actin-binding proteins, including WAVE3, play pivotal roles in these processes. WAVE3, a member of the WASP family, remains the focus of this review due to its potential involvement in TNBC progression. While actin-binding proteins are studied for their roles in healthy cellular cycles, their significance in TNBC remains underexplored. This review aims to discuss WAVE3's impact on TNBC, exploring its molecular makeup, functions, and significance in tumor progression. The intricate structure of WAVE3, featuring elements like the verprolin-cofilin-acidic domain and regulatory elements, plays a crucial role in regulating actin dynamics. Dysregulation of WAVE3 in TNBC has been linked to enhanced cell migration, invasion, extracellular matrix remodeling, epithelial-mesenchymal transition, tumor proliferation, and therapeutic resistance. Understanding the role of actin-binding proteins in cancer biology has potential clinical implications, making them potential prognostic biomarkers and promising therapeutic targets. The review emphasizes the need for further research into actin-binding proteins' clinical applications, diagnostic value, and therapeutic interventions. In conclusion, this comprehensive review explores the complex interplay between actin and actin-binding proteins, with special emphasis on WAVE3, in the context of TNBC. By unraveling the molecular intricacies, structural characteristics, and functional significance, the review paves the way for future research directions, clinical applications, and potential therapeutic strategies in the challenging landscape of TNBC.

The WAVE3/β-catenin oncogenic signaling regulates chemoresistance in triple negative breast cancer

BACKGROUND

Metastatic breast cancer is responsible for the death of the majority of breast cancer patients. In fact, metastatic BC is the 2nd leading cause of cancer-related deaths in women in the USA and worldwide. Triple negative breast cancer (TNBC), which lacks expression of hormone receptors (ER-α and PR) and ErbB2/HER2, is especially lethal due to its highly metastatic behavior, propensity to recur rapidly, and for its resistance to standard of care therapies, through mechanisms that remain incompletely understood. WAVE3 has been established as a promoter of TNBC development and metastatic progression. In this study, we investigated the molecular mechanisms whereby WAVE3 promotes therapy-resistance and cancer stemness in TNBC, through the regulation of β-catenin stabilization.

METHODS

The Cancer Genome Atlas dataset was used to assess the expression of WAVE3 and β-catenin in breast cancer tumors. Kaplan-Meier Plotter analysis was used to correlate expression of WAVE3 and β-catenin with breast cancer patients' survival probability. MTT assay was used to quantify cell survival. CRISPR/Cas9-mediated gene editing, 2D and 3D tumorsphere growth and invasion assays, Immunofluorescence, Western blotting, Semi-quantitative and real-time quantitative PCR analyses were applied to study the WAVE3/β-catenin oncogenic signaling in TNBC. Tumor xenograft assays were used to study the role of WAVE3 in mediating chemotherapy resistance of TNBC tumors.

RESULTS

Genetic inactivation of WAVE3 in combination of chemotherapy resulted in inhibition of 2D growth and 3D tumorsphere formation and invasion of TNBC cells in vitro, as well as tumor growth and metastasis in vivo. In addition, while re-expression of phospho-active WAVE3 in the WAVE3-deficient TNBC cells restored the oncogenic activity of WAVE3, re-expression of phospho-mutant WAVE3 did not. Further studies revealed that dual blocking of WAVE3 expression or phosphorylation in combination with chemotherapy treatment inhibited the activity and expression and stabilization of β-catenin. Most importantly, the combination of WAVE3-deficiency or WAVE3-phospho-deficiency and chemotherapy suppressed the oncogenic behavior of chemoresistant TNBC cells, both in vitro and in vivo.

CONCLUSION

We identified a novel WAVE3/β-catenin oncogenic signaling axis that modulates chemoresistance of TNBC. This study suggests that a targeted therapeutic strategy against WAVE3 could be effective for the treatment of chemoresistant TNBC tumors.

The antihyperlipidemic drug potassium piperonate impairs the migration and tumorigenesis of breast cancer cells via the upregulation of miR-31

Background

Breast cancer is the second cause of cancer death in women, and tumor metastasis is the primary cause of mortality. Due to the involvement of many regulatory molecules and signaling pathways, the occurrence and development of metastases needs to be further studied. MicroRNAs (miRNAs) are ubiquitously expressed small non-coding RNAs that have been shown to play an important role in the diagnosis and treatment of many diseases, as well as representing an attractive candidate for metastasis control. In this study, we investigated the mechanism of potassium piperonate (GBK) in impairing breast cancer cell invasion and metastasis by targeting miR-31.

Methods

Breast cancer cells, either treated with GBK or left untreated, were assessed for migration and invasion capacities using wound healing and transwell assays. GBK-targeted miRNAs were identified and verified using RT-qPCR. Western blotting was used to validate the changes in expression levels of miR-31-targeted genes. Methylation specific PCR was performed to detect the effect of GBK on the methylation levels of the lncRNA LOC554202 host gene. The synergistic effect of GBK and the chemotherapy drug cisplatin (DDP) on breast cancer cells was verified using cell proliferation, colony formation, and RT-qPCR assays in vitro, and the tumor xenograft model in vivo.

Results

We found that miR-31 was the main target of GBK. GBK treatment affected the epigenetic modification at CpG sites by downregulating DNA methyltransferases. Thus, the CpG-associated methylation levels of lncRNA LOC554202 decreased significantly, and in turn upregulated both miR-31 and its host gene LOC554202 in breast cancer cells. We also observed the significant inhibition of miR-31-targeted genes following GBK treatment, including RHOA, WAVE3, and SATB2, with functions closely related to cancer cell invasion, migration, and proliferation. Furthermore, we revealed that the combination of GBK and DDP had a synergistic effect on inhibiting the proliferation of breast cancer cells in vitro and in vivo, especially in triple negative breast cancer (TNBC).

Conclusions

This study investigated the target of GBK in the inhibition of breast cancer migration and invasion, and the underlying mechanisms involved, providing theoretical support for the development of GBK as an auxiliary drug for clinical treatment.

YB1 Is a Major Contributor to Health Disparities in Triple Negative Breast Cancer

Simple Summary

Triple negative breast cancer (TNBC) is a devastating disease that affects many women, due to the lack of FDA-approved targeted therapy. In the absence of cell surface receptors ER, PR, and Her2 that can be targeted with hormonal and antibody treatments, cytotoxic chemotherapy remains the major course of treatment, with a dismal response and rapid recurrence due to the acquisition of resistance. TNBC is also twice as more prevalent in African American (AA) when compared to Caucasian American (CA) women. This study investigated the role of the YB1 gene in the disparities in TNBC between AA and CA women. We found that YB1 is highly expressed in TNBC tumors of AA origin when compared to CAs. Increased expression levels and activity of YB1 correlates with poor disease outcomes, resistance to chemotherapy, and the activation of the cancer stem cell (CSC) phenotype, with higher levels in AA than in CA TNBC tumors. More importantly, we found that the targeted inhibition of the expression and activity of YB1 significantly inhibited the oncogenic behavior of AA tumors through sensitization to chemotherapy and inhibition of CSCs. Our study is the first to show that YB1 activity may be a major biological contributor to the health disparities in TNBC, and that development of therapies that specifically target YB1 could reduce these disparities.

Abstract

Triple negative breast cancer (TNBC) is the most aggressive amongst all breast cancer (BC) subtypes. While TNBC tumors represent less than 20% of all BC subtypes, they are responsible for the most BC-related deaths. More significantly, when considering TNBC incidence across all racial/ethnic groups, TNBC accounts for less than 20% of all BCs. However, in non-Hispanic black women, the incidence rate of TNBC is more than 40%, which may be a contributing factor to the higher BC-related death rate in this population. These disparities remain strong even after accounting for differences in socioeconomic status, healthcare access, and lifestyle factors. Increased evidence now points to biological mechanisms that are intrinsic to the tumor that contribute to disparate TNBC disease burdens. Here, we show that YB1, a multifunction gene, plays a major role in the TNBC disparities between African American (AA) and Caucasian American (CA) women. We show in three independent TNBC tumors cohorts, that YB1 is significantly highly expressed in AA TNBC tumors when compared to CAs, and that increased levels of YB1 correlate with poor survival of AA patients with TNBC. We used a combination of genetic manipulation of YB1 and chemotherapy treatment, both in vitro and in animal models of TNBC to show that YB1 oncogenic activity is more enhanced in TNBC cell lines of AA origin, by increasing their tumorigenic and aggressive behaviors, trough the activation of cancer stem cell phenotype and resistance to chemotherapeutic treatments.

Phosphorylation of the proline-rich domain of WAVE3 drives its oncogenic activity in breast cancer

Post-translational modification of proteins, such as tyrosine phosphorylation, plays a major role in driving the oncogenic activity of oncogenes. WAVE3 (WASF3), an adaptor and actin cytoskeleton remodeling protein, contributes to cell migration, cancer cell invasion, and metastasis. WAVE3 plays a vital role in the progression and metastasis of triple negative breast cancer (TNBC), in part through the regulation of cancer stem cells (CSCs). Several studies have shown that WAVE3 tyrosine phosphorylation is required for its oncogenic activity. Moreover, our recent study showed that the proline rich domain (PRD) of WAVE3 is required for maintenance of the CSC niche in breast cancer by regulating the nuclear translocation of the CSC-specific nuclear transcription factor YB1. Here, we show that the PRD domain of WAVE3 and its phosphorylation are essential for driving the oncogenic activity of WAVE3. We show that phosphorylation of WAVE3 PRD is essential for migration and invasion of breast cancer cells in vitro, as well as tumor growth and metastasis in vivo. Mechanistically, we show that phosphorylation of the WAVE3 PRD is essential for interaction between WAVE3 and YB1. Loss of PRD phosphorylation inhibits such interaction and the YB1-mediated activation of expression of CSC markers, as well as the WAVE3 mediated activation of EMT. Together, our study identifies a novel role of WAVE3 and its PRD domain in the regulation of the invasion metastasis cascade in BC that is independent of the known function of WAVE3 as an actin cytoskeleton remodeling protein through the WAVE regulatory complex (WRC).

Targeting WASF3 Signaling in Metastatic Cancer

Increasing evidence indicates that cancer metastasis is regulated by specific genetic pathways independent of those controlling tumorigenesis and cancer growth. WASF3, a Wiskott–Aldrich syndrome protein family member, appears to play a major role not only in the regulation of actin cytoskeleton dynamics but also in cancer cell invasion/metastasis. Recent studies have highlighted that WASF3 is a master regulator and acts as a pivotal scaffolding protein, bringing the various components of metastatic signaling complexes together both spatially and temporally. Herein, targeting WASF3 at the levels of transcription, protein stability, and phosphorylation holds great promise for metastasis suppression, regardless of the diverse genetic backgrounds associated with tumor development. This review focuses on the critical and distinct contributions of WASF3 in the regulation of signal pathways promoting cancer cell invasion and metastasis.

Deficiency of Wiskott-Aldrich syndrome protein has opposing effect on the pro-oncogenic pathway activation in nonmalignant versus malignant lymphocytes

Immunodeficiency is associated with cancer risk. Accordingly, hematolymphoid cancers develop in Wiskott-Aldrich syndrome (WAS), an X-linked primary immunodeficiency disorder (PID) resulting from the deficiency of WAS-protein (WASp) expressed predominantly in the hematolymphoid cell lineages. Despite the correlation between WASp deficiency and hematolymphoid cancers, the molecular mechanism underlying the oncogenic role of WASp is incompletely understood. Employing the WASp-sufficient and WASp-deficient cell-pair model of human T and B lymphocytes, we show that WASp deficiency differentially influences hyperactivation versus inhibition of both CDC42:ERK1/2 and NF-κB:AP-1 pro-oncogenic signaling pathways in nonmalignant versus malignant T and B lymphocytes. Furthermore, WASp deficiency induces a cell-type specific up/down-modulation of the DNA-binding activities of NF-κB, AP-1, and multiple other transcription factors with known roles in oncogenesis. We propose that WASp functions as a putative "tumor-suppressor" protein in normal T and B cells, and "oncoprotein" in a subset of established T and B cell malignancies that are not associated with the NPM-ALK fusion.

Invadopodia: clearing the way for cancer cell invasion

The invasive nature of many cancer cells involves the formation of F-actin-based, lipid-raft-enriched membrane protrusions known as invadopodia or, more broadly, invadosomes. Invadopodia are specialized adhesive structures arising from ventral cell surface within cell-extracellular matrix (ECM) contacts and concentrate high proteolytic activities that allow cells to overcome the dense scaffold of local microenvironment, comprising a natural barrier to cell spreading. This degradative activity distinguishes invadopodia from other adhesive structures like focal adhesions, lamellipodia or filopodia, and is believed to drive cancer progression.

Elucidating the molecular signaling pathways of WAVE3

Cancer metastasis is a complex, multistep process that requires tumor cells to evade from the original site and form new tumors at a distant site or a different organ, often via bloodstream or the lymphatic system. Metastasis is responsible for more than 90% of cancer-related deaths. WAVE3 belongs to the Wiskott-Aldrich syndrome protein (WASP) family, which regulate actin cytoskeleton remodeling as well as several aspects of cell migration, invasion, and metastasis. In fact, WAVE3 has been established as a driver of tumor progression and metastasis in cancers from several origins, including triple negative breast cancers (TNBCs), which are classified as the most lethal subtype of breast cancer, due to their resistance to standard of care therapy and highly metastatic behavior. In this review, we will attempt to summarize the recent advances that have been made to understand how WAVE3 contributes to the molecular mechanisms that control cancer progression and metastasis. We will also review the signaling pathways that are involved in the regulation of WAVE3 expression and function to identify potential therapeutic options targeted against WAVE3 for the treatment of patients with metastatic tumors.

WAVE3 upregulation in esophageal squamous cell carcinoma and its effect on the migration of human esophageal cancer cell lines in vitro

The present study aimed to investigate the role of Wiskott-Aldrich syndrome verprolin-homologous protein 3 (WAVE3) in the progression of esophageal squamous cell carcinoma (ESCC), and to explore its effect on the migration of esophageal cancer cell lines in vitro. The expression level of WAVE3 in ESCC tissues was determined via immunohistochemistry, and the relative levels of WAVE3 mRNA and micro (mi)RNA200b were assessed in the serum of patients with ESCC using reverse transcription-quantitative PCR (RT-qPCR). Following cell transfection, the levels of miRNA200b and WAVE3 protein were determined via RT-qPCR and western blot analysis, and cell migration was examined using a Transwell assay. Subsequently, the clinical parameters were used to analyze whether the expression of WAVE3 in tissues and serum was associated with the occurrence and development of ESCC. The results demonstrated that the expression of WAVE3 was increased in ESCC tissues compared with normal tissues. The results also revealed increased expression levels of WAVE3 and decreased expression levels of miRNA200b in the serum of patients with ESCC, compared with healthy volunteers. High expression of WAVE3 was significantly associated with tumor TNM stage, invasion depth and lymphatic invasion of ESCC. In cells transfected with miRNA200b mimic, the miRNA200b was overexpressed, WAVE3 protein was downregulated and cell migration ability was decreased. The results of the present study suggest that WAVE3 may serve as an oncogene in ESCC, and its inhibition via miRNA200b decreased tumor cell migration. Therefore, WAVE3 may serve as a novel biological marker and therapeutic target for ESCC.

MicroRNAs Contribute to Breast Cancer Invasiveness

Cancer statistics in 2018 highlight an 8.6 million incidence in female cancers, and 4.2 million cancer deaths globally. Moreover, breast cancer is the most frequent malignancy in females and twenty percent of these develop metastasis. This provides only a small chance for successful therapy, and identification of new molecular markers for the diagnosis and prognostic prediction of metastatic disease and development of innovative therapeutic molecules are therefore urgently required. Differentially expressed microRNAs (miRNAs) in cancers cause multiple changes in the expression of the tumorigenesis-promoting genes which have mostly been investigated in breast cancers. Herein, we summarize recent data on breast cancer-specific miRNA expression profiles and their participation in regulating invasive processes, in association with changes in cytoskeletal structure, cell-cell adhesion junctions, cancer cell-extracellular matrix interactions, tumor microenvironments, epithelial-to-mesenchymal transitions and cancer cell stem abilities. We then focused on the epigenetic regulation of individual miRNAs and their modified interactions with other regulatory genes, and reviewed the function of miRNA isoforms and exosome-mediated miRNA transfer in cancer invasiveness. Although research into miRNA’s function in cancer is still ongoing, results herein contribute to improved metastatic cancer management.

Rosiglitazone blocks first trimester in-vitro placental injury caused by NF-κB-mediated inflammation

Increased inflammation and abnormal placentation are common features of a wide spectrum of pregnancy-related disorders such as intra uterine growth restriction, preeclampsia and preterm birth. The inflammatory response of the human placenta has been mostly investigated in relation to cytokine release, but the direct molecular consequences on trophoblast differentiation have not been investigated. This study measured the general effects of LPS on both extravillous and villous trophoblast physiology, and the involvement of the transcription factors PPARγ and NF-κB, specifically using 1^st trimester explants and HTR-8/ SVneo cell line models. While both proteins are known for their roles in inflammatory pathways, PPARγ has been identified as an important molecule in trophoblast differentiation, suggesting its potential role in mediating a crosstalk between inflammation and trophoblast differentiation. Here, LPS (1 µg/ml) exposure of first trimester placental villous explants resulted in secretion of inflammatory cytokines, induction of apoptosis and reduction in trophoblast cell proliferation. Additionally, LPS significantly reduced expression of the trophoblast differentiation proteins GCM1 and β-hCG, and increased invasion of the extravillous trophoblast. Activation of PPARγ by Rosiglitazone (10 µM) reversed the LPS-mediated effects on inflammatory cytokine release, trophoblast apoptosis and proliferation compared to controls. Lastly, markers of trophoblast differentiation and invasion reverted to control levels upon activation of PPARγ and concomitant inhibition of NF-κB (either by Rosiglitazone or NF-κB specific inhibitor), revealing a new role for NF-κB in trophoblast invasion. This study reveals a novel PPARγ - NF-κB axis that coordinates inflammatory and differentiation pathways in the human placenta. The ability to reverse trophoblast-associated inflammation with Rosiglitazone offers promise that the PPARγ - NF-κB pathway could one day provide a therapeutic target for placental dysfunction associated with both inflammation and abnormal trophoblast differentiation.

Targeting invadopodia for blocking breast cancer metastasis

Dissemination of cancer cells from the primary tumor and their spread to distant sites of the body is the leading cause of mortality in metastatic cancer patients. Metastatic cancer cells invade surrounding tissues and blood vessels by forming F-actin-rich protrusions known as invadopodia, which degrade the extracellular matrix and enable invasion of tumor cells through it. Invadopodia have now been observed in vivo, and recent evidence demonstrates direct molecular links between assembly of invadopodia and cancer metastasis in both mouse models and in human patients. While significant progress has been achieved in the last decade in understanding the molecular mechanisms and signaling pathways regulating invadopodia formation and function, the application of this knowledge to development of prognostic and therapeutic approaches for cancer metastasis has not been discussed before. Here, we provide a detailed overview of current prognostic markers and tests for cancer metastasis and discuss their advantages, disadvantages, and their predicted efficiency. Using bioinformatic patient database analysis, we demonstrate, for the first time, a significant correlation between invadopodia-associated genes to breast cancer metastasis, suggesting that invadopodia could be used as both a prognostic marker and as a therapeutic target for blocking cancer metastasis. We include here a novel network interaction map of invadopodia-associated proteins with currently available inhibitors, demonstrating a central role for the recently identified EGFR-Pyk2-Src-Arg-cortactin invadopodial pathway, to which re-purposing of existent inhibitors could be used to block breast cancer metastasis. We then present an updated overview of current cancer-related clinical trials, demonstrating the negligible number of trials focusing on cancer metastasis. We also discuss the difficulties and complexity of performing cancer metastasis clinical trials, and the possible development of anti-metastasis drug resistance when using a prolonged preventive treatment with invadopodia inhibitors. This review presents a new perspective on invadopodia-mediated tumor invasiveness and may lead to the development of novel prognostic and therapeutic approaches for cancer metastasis.

The Kindlin-2 regulation of epithelial-to-mesenchymal transition in breast cancer metastasis is mediated through miR-200b

Metastasis is the main cause of death in cancer patients, including breast cancer (BC). Despite recent progress in understanding the biological and molecular determinants of BC metastasis, effective therapeutic treatments are yet to be developed. Among the multitude of molecular mechanisms that regulate cancer metastasis, the epithelial-to-mesenchymal transition (EMT) program plays a key role in the activation of the biological steps leading to the metastatic phenotype. Kindlin-2 has been associated with the pathogenesis of several types of cancers, including BC. The role of Kindlin-2 in the regulation of BC metastasis, and to a lesser extent in EMT is not well understood. In this study, we show that Kindlin-2 is closely associated with the development of the metastatic phenotype in BC. We report that knockout of Kindlin-2 in either human or mouse BC cells, significantly inhibits metastasis in both human and mouse models of BC metastasis. We also report that the Kindlin-2-mediated inhibition of metastasis is the result of inhibition of expression of key molecular markers of the EMT program. Mechanistically, we show that miR-200b, a master regulator of EMT, directly targets and inhibits the expression of Kindlin-2, leading to the subsequent inhibition of EMT and metastasis. Together, our data support the targeting of Kindlin-2 as a therapeutic strategy against BC metastasis.

The WAVE3-YB1 interaction regulates cancer stem cells activity in breast cancer

Resistance to therapy is the main cause of tumor recurrence and metastasis and cancer stem cells (CSCs) play a crucial role in this process, especially in triple-negative breast cancers (TNBCs). Unfortunately, no FDA-approved treatment is currently available for this subtype of BC, which explains the high rate of mortality in patients with TNBC tumors. WAVE3, a member of the WASP/WAVE actin-cytoskeleton remodeling family of protein, has been established as a major driver of tumor progression and metastasis of several solid tumors, including those originating in the breast. Our recently published studies found WAVE3 to mediate the process of chemoresistance in TNBCs. The molecular mechanisms whereby WAVE3 regulates chemoresistance in TNBC tumors remains largely unknown, as does the role of WAVE3 in CSC maintenance. Here we show that WAVE3 promotes CSC self-renewal and regulates transcription of CSC-specific genes, which, in part, provides a mechanistic explanation for the function of WAVE3 in chemoresistance in TNBCs. Our data show that WAVE3 is enriched in the CSC-subpopulation of TNBC cell lines. Knockout of WAVE3 via CRISPR/Cas9 significantly attenuates the CSC-subpopulation and inhibits transcription of CSC transcription factors. Mechanistically, we established a link between WAVE3 and the Y-box-binding protein-1 (YB1), a transcription factor and CSC-maintenance gene. Indeed, the interaction of WAVE3 with YB1 is required for YB1 translocation to the nucleus of cancer cells, and activation of transcription of CSC-specific genes. Our findings identify a new WAVE3/YB1 signaling axis that regulates the CSC-mediated resistance to therapy and opens a new therapeutic window for TNBCs treatment.

TLR5/7-mediated PI3K activation triggers epithelial-mesenchymal transition of ovarian cancer cells through WAVE3-dependent mesothelin or OCT4/SOX2 expression

Toll-like receptor (TLR)-mediated signaling induces cell migration or invasion in several tumors and various stages of cancer. Interactions of mesothelin, a 40-kDa cell surface glycoprotein, with cancer antigen 125 (CA125) is associated with drug resistance, metastasis, and poor clinical outcome of ovarian cancer patients. In this study, we examined the role of TLR5 and TLR7 in the metastasis of ovarian cancer through the induction of mesothelin/CA125 expression and investigated its underlying mechanism. TLR5 agonist (flagellin) and TLR7 agonist (imiquimod) upregulated mesenchymal phenotypes and produced epithelial-mesenchymal transition (EMT)-related cytokines in the SKOV3 cells; however, TLR7 expressing CaOV3 cells had no response to the specific ligand, imiquimod, for enhancing its EMT processes. Stimulation of the SKOV3 cells with flagellin or imiquimod activated Wiskott-Aldrich syndrome protein verprolin-homologous 3 (WAVE3) and mesothelin/CA125, whereas it suppressed the expression of TAp63. Moreover, knockdown of TLR5 or TLR7 in SKOV3 cells profoundly impaired the TLR5- or TLR7-intiated downstream signaling pathway. Loss of WAVE3 in SKOV3 cells led to the inhibition of invasion, suppression of mesenchymal characteristics, prevention of OCT4/SOX2 secretion, and attenuation of mesothelin/CA125 expression after stimulation with flagellin or imiquimod. Although the disruption of mesothelin decreased the migratory activity of the TLR5/7-activated SKOV3 cells, knockdown of mesothelin failed to reduce the expression of mesenchymal markers, OCT4, and SOX2. In addition, targeting OCT4 or SOX2 with siRNA had no effect on the expression of mesothelin and the suppression of transcriptionally active p63 (TAp63) in the TLR5/7-stimulated SKOV3 cells. Our results suggest that TLR5/7-mediated WAVE3 activation not only controls the mesothelin-related EMT processes but also modulates OCT4/SOX2-mediated mesenchymal marker expression. Taken together, both TLR5 and TLR7 expression are critical for the TLR5/7-induced metastasis of ovarian cancer and the inhibition of WAVE3 might be a new therapeutic target to control ovarian cancer metastasis.

TNF-α promotes breast cancer cell migration and enhances the concentration of membrane-associated proteases in lipid rafts

Purpose

Tumor progression is associated with cell migration, invasion and metastasis. These processes are accompanied by the activation of specific proteases that are either linked to cellular membranes or are secreted into extracellular spaces. TNF-α is known to play an important role in various aspects of tumor progression. The aim of this work was to assess the effect of TNF-α on the migration of breast cancer cells and, in addition, to assess its association with the location of membrane-associated proteases in lipid rafts.

Methods

Wound scratch healing and Transwell migration assays were used to study the effect of TNF-α on the migration of both hormone-dependent and hormone-independent breast cancer-derived cells, i.e., MCF7 and MDA-MB-231, respectively. The expression and secretion of three matrix metalloproteases, MMP9, MMP2 and MT1-MMP, and two dipeptidyl peptidases, CD26 and FAP-α, was investigated using RT-PCR, Western blotting and gelatin zymography. In addition, activation of the MAPK/ERK signaling pathway was investigated by Western blotting.

Results

We found that a TNF-α-induced enhancement of breast cancer cell migration was accompanied by an increased secretion of MMP9, but not MMP2, into the culture media. We also found that TNF-α upregulated the expression of the dipeptidyl peptidases CD26 and FAP-α in a dose-dependent manner and, in addition, enhanced the concentration of all five proteases in lipid rafts in the breast cancer-derived cells tested, regardless of cell type. Furthermore, we found that TNF-α activated the MAPK/ERK signaling pathway by increasing the ERK1/2 phosphorylation level. Application of the MEK/ERK1/2 inhibitor U-0126 resulted in down-regulation of TNF-α-induced MMP9 secretion and abrogation of the enhanced concentration of proteases in the lipid rafts.

Conclusions

From our results we conclude that TNF-α-induced activation of the MAPK/ERK signaling pathway may promote breast cancer cell migration via both upregulation of MMP9, CD26 and FAP-α and concentration of these proteases, as also MT1-MMP and MMP2, in the lipid rafts. TNF-α may serve as a potential therapeutic target in breast cancers susceptible to TNF-α stimulation.

Effects of a pyrrole-based, microtubule-depolymerizing compound on RAW 264.7 macrophages

RAW 264.7 murine macrophages were exposed to the pyrrole-based compound 3,5-Dibromo-4-(3,4-dimethoxyphenyl)-1H-pyrrole-2-carboxylic acid ethyl ester (JG-03-14), which is a known microtubule depolymerizing agent with antitumor activity [1,2,3]. In this study exposure to JG-03-14 reduced the production of pro-inflammatory molecules by macrophages activated with lipopolysaccharide (LPS). Treatment with the pyrrole-based compound decreased the concentration of tumor necrosis factor-α (TNF-α) and nitric oxide (NO) released from the macrophages. Exposure to JG-03-14 also decreased TNF-α mRNA expression levels and the protein expression levels of inducible nitric oxide synthase (iNOS), the enzyme responsible for NO production in the activated macrophages. Furthermore, JG-03-14 treatment significantly changed the degradation profile of IκB-β, an inhibitor of the NF-κB transcription factor, which suggests that JG-03-14 may attenuate the activation of the LPS-induced NF-κB signaling pathway needed to produce the pro-inflammatory mediators. We conclude that JG-03-14 possesses anti-inflammatory properties.

Lysophosphatidic acid activates the RhoA and NF-κB through Akt/IκBα signaling and promotes prostate cancer invasion and progression by enhancing functional invadopodia formation

We have demonstrated previously that increased RhoA and nuclear factor (NF)-κB activities are associated with increased PC-3 prostate cancer cell invasion and that lysophosphatidic acid (LPA) significantly increases cancer invasion through RhoA and NF-κB activation. In this study, we identified the intermediate signaling molecules and specialized cell structures which are activated by LPA, resulting in enhanced cellular invasion. LPA-induced Akt and IκBα signaling pathways were necessary for RhoA and NF-κB activation, and these LPA effects were abolished by RhoA inhibition. Mice injected with PC-3 cells expressing dominant-negative RhoA N19 developed significantly less tumor growth compared with those injected with control (pcDNA 3.1). In addition, LPA treatment increased functional invadopodia formation. Activation of RhoA and NF-κB through the Akt and IκBα signaling pathway was required for LPA-stimulated gelatin degradation activity. LPA administration increased tumor growth and osteolytic lesions in a mouse xenograft model. These results indicate that LPA promotes PC-3 cell invasion by increasing functional invadopodia formation via upregulating RhoA and NF-κB signaling which contributes to prostate cancer progression. Therefore, the LPA and RhoA-NF-κB signaling axis may represent key molecular targets to inhibit prostate cancer invasion and progression.

miR-138-Mediated Regulation of KINDLIN-2 Expression Modulates Sensitivity to Chemotherapeutics

Prostate cancer is the second leading cause of cancer-related death in men, second only to lung cancer, mainly due to disease reoccurrence as a result to lack of response to androgen deprivation therapies (ADT) after castration. Patients with metastatic castration-resistant prostate cancer (mCRPC) have very limited treatment options, with docetaxel as the first-line standard of care, for which resistance to this chemotherapeutic ultimately develops. Therefore, finding ways to sensitize tumors to chemotherapies and to limit chemoresistance provides a viable strategy to extend the survival of mCRPC patients. This study investigated the role of Kindlin-2 (FERMT2/K2), a member of the Kindlin family of FERM domain proteins and key regulators of the adhesive functions mediated by integrin, in the sensitization of mCRPC to chemotherapeutics. Loss of K2, which is overexpressed in prostate cancer cells derived from mCRPC tumors, compared with those cells derived from androgen-dependent tumors, significantly enhanced apoptosis and cell death of docetaxel-treated PC3 cells. Furthermore, it was determined that K2-mediated sensitization to docetaxel treatment is the result of inhibition of β1-integrin signaling. Finally, miR-138 specifically targeted K2 and inhibited its expression, thereby regulating a miR-138/K2/β1-integrin signaling axis in mCRPC that is critical for the modulation of sensitivity to chemotherapeutics. Thus, these data identify a novel signaling axis where K2 in combination with chemotherapeutics provides a new target for the treatment of mCRPC.

IMPLICATIONS

Targeted inhibition of Kindlin-2 in combination with chemotherapy represents an effective treatment option for mCRPC.

Loss of WAVE3 sensitizes triple-negative breast cancers to chemotherapeutics by inhibiting the STAT-HIF-1α-mediated angiogenesis

Chemoresistance allows for disease to recur and ultimately causes the death of most breast cancer patients. This scenario is particularly relevant in patients harboring triple-negative breast cancer (TNBC) tumors for which there are no effective FDA-approved drugs. However, a recent study determined that TNBCs can be segregated into 6 genetically distinct subtypes that do in fact exhibit differential rates of pathological complete response (pCR) to standard-of-care chemotherapies. Of these, the mesenchymal and mesenchymal stem-like subtypes of TNBCs exhibit the lowest rates of pCR when treated with standard-of-care chemotherapies. WAVE3 is an actin-cytoskeleton remodeling protein, and recent studies have highlighted a potential role for WAVE3 in promoting tumor progression and metastasis in TNBC. However, whether WAVE3 activity is involved in the development of chemoresistance in TNBCs remains unclear. Here we show that loss of WAVE3 expression resensitizes human TNBC cells to doxorubicin and docetaxel, as measured by increased apoptosis and cell death. We also show that WAVE3 knockdown in the chemotherapy-treated TNBC cells results in inhibition of STAT1 phosphorylation, as well as a significant decrease in expression levels of its downstream effector HIF-1α. Since HIF-1α is a major activator of VEGF-A production, and therefore a stimulator of tumor angiogenesis, loss of HIF-1α in the WAVE3-knockdown cells resulted in the inhibition the chemotherapy-mediated VEGF-A secretion and the downstream activation of angiogenesis, a phenomenon that often accompanies chemoresistance. Our data identify a critical role of WAVE3 in sensitizing TNBC to chemotherapy by inhibiting the STAT1→HIF-1α→VEGF-A signaling axis, and support the possibility that WAVE3 inhibition may be a promising target for TNBC cancer therapy.