RAC1 GTP-ase signals Wnt-beta-catenin pathway mediated integrin-directed metastasis-associated tumor cell phenotypes in triple negative breast cancers

A landscape of patient-derived cancer-associated fibroblast signals in endometrial cancers

In conversation with endometrial tumor cells, the endometrial cancer-associated fibroblasts (CAFs) are the "partners in crime" of uterine neoplasm's highly heterogeneous tumor microenvironment (TME). We designed a laboratory-friendly method to culture endometrial CAFs on a patient-to-patient basis for studying the CAF-TME and CAF-tumor cell interaction(s). Here, we present a comprehensive characterization of endometrial CAFs derived from patients' tumor tissues (T) and tumor-adjacent normal tissues (N). We used more than 80 T and N from 53 consecutive consented patients with endometrial cancers at the Avera Cancer Institute. We derived TCAF and NCAF in a non-enzymatic feeder-layer culture and characterized their expression of markers by qRT-PCR, flow cytometry, immunocytochemistry, immunofluorescence, and Western blot. Although similar in the expression pattern of EpCAM-/CK18-/vimentin+ as in ovarian CAFs, endometrial NCAFs, and TCAFs characteristically presented dual morphology in culture. Endometrial CAFs were EpCAM-/CK18-/CD45-/CD31-/SMA+/TE-7+/PDGFRA+/CXCL12+/Meflin+/CD155+/CD90+ with patient-specific positivity for S100A4/FAP/PD-L1/CD44. Endometrial CAFs expressed mRNAs for signaling proteins of several pathways and receptor-ligands, including (1) cell cycle pathway, (2) TGF pathway, (3) FGF pathway, (4) Wnt-beta-catenin pathway, (5) HER pathway, (6) tyrosine kinase receptor ligands, and (7) steroid receptors. We tested the hypoxic response of CAFs to show that endometrial CAFs upregulate MMP1 in a HIF-1a-independent manner. In trying to delineate the relationship between expressions of CAF markers and T-cells in the tumor tissue, we observed that FAP-positive CAFs that are derived from CD4/CD8 positive tumor tissue expressed CXCL12 mRNA. The data indicate the role of the CXCL12-CXCR4 pathway of the CAF-rich stroma in the lymphocytic infiltration of the tumor. We demonstrate that endometrial CAFs can be cultured in an enzymatic-digestion-independent manner, and their signaling landscape can be mapped toward understanding CAF-TME dialogue. Our data will help unearth the functional relevance of endometrial CAFs in the context of clinical outcomes and designing CAF-inclusive therapy in the future.

In vitro synergistic effect of hesperidin and doxorubicin downregulates epithelial-mesenchymal transition in highly metastatic breast cancer cells

Background

We previously reported that in highly metastatic breast cancer cells, doxorubicin (DOX) at non-toxic concentrations promoted cell migration and invasion. Hesperidin (30, 5, 9-dihydroxy-40-methoxy-7-orutinosyl flavanone) is a flavonoid glycoside isolated from citrus/lemon plant that possesses a cytotoxic effect in several cancer cells. In this study, we investigate whether DOX efficacy is enhanced by hesperidin (Hsd) and the molecular pathway involved in highly metastatic breast cancer, 4T1.

Methods

Combined cytotoxicity of Hsd and DOX was evaluated with MTT assay and was analyzed using Chou-Talalay’s method. To better understand the underlying mechanism, several factors, including apoptosis and cell cycle arrest were analyzed by flow cytometry. In addition, antimigration activity was evaluated by scratch wound healing assay, MMP-9 expression by ELISA and gelatin zymography, and Rac-1 protein level using western blot. The data on survival rate and expression level of MMP-9 and Rac-1 were obtained from Gene Expression OMNIBUS (GEO).

Results

Under MTT assay, Hsd showed a cytotoxic effect in a concentration-dependent manner with an IC50 value of 284 µM on 4T1 cells. Hsd synergistically enhanced the cytotoxic effect of DOX which seemed to correlate with an increase in apoptotic cell death, G2/M cell cycle arrest and blocked the migration of 4T1 cells. At 10 nM, doxorubicin induced lamellipodia formation, and increased the level of Rac-1 and metalloproteinase-9 (MMP-9) expression. Interestingly, combined treatment of DOX and Hsd dramatically downregulated the expression of MMP-9 and Rac-1. These results indicated that Hsd block the cell migration induced by DOX under in vitro studies.

Conclusion

These findings strongly suggest that Hsd possesses a potential synergistic effect that can be developed to enhance the anticancer efficacy of DOX and reduce the risks of chemotherapy use in highly metastatic breast cancer.

A Cell-Based Systematic Review on the Role of Annexin A1 in Triple-Negative Breast Cancers

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype that is often associated with a poorer prognosis and does not respond to hormonal therapy. Increasing evidence highlights the exploitability of Annexin A1 (AnxA1), a calcium dependent protein, as a precision medicine for TNBC. To systematically summarize the role of AnxA1 and its associated mechanisms in TNBC, we performed data mining using three main databases: PubMed, Scopus, and Ovid/Medline. The papers retrieved were based on two different sets of key words such as “Annexin A1” or “Lipocortin 1” and “Breast cancer” or “TNBC”. A total of 388 articles were identified, with 210 chosen for comprehensive screening and 13 papers that met inclusion criteria were included. Current evidence from cell culture studies showed that AnxA1 expression is correlated with NF-κB, which promotes migration by activating ERK phosphorylation. AnxaA1 also activates TGF-β signaling which upregulates MMP-9 and miR196a expression to enhance epithelial-mesenchymal transition and migratory capacity of TNBC cells. AnxA1 can steer the macrophage polarization toward the M2 phenotype to create a pro-tumor immune environment. Existing research suggests a potential role of AnxA1 in the metastasis and immune landscape of TNBC tumors. Preclinical and clinical experiments are warranted to investigate the feasibility and effectiveness of targeting AnxA1 in TNBC.

Rho GTPase gene expression and breast cancer risk: a Mendelian randomization analysis

The Rho GTPase family consists of 20 genes encoding intracellular signalling proteins that influence cytoskeletal dynamics, cell migration and cell cycle progression. They are implicated in breast cancer progression but their role in breast cancer aetiology is unknown. As aberrant Rho GTPase activity could be associated with breast cancer, we aimed to determine the potential for a causal role of Rho GTPase gene expression in breast cancer risk, using two-sample Mendelian randomization (MR). MR was undertaken in 122,977 breast cancer cases and 105,974 controls, including 69,501 estrogen receptor positive (ER+) cases and 105,974 controls, and 21,468 ER negative (ER-) cases and 105,974 controls. Single nucleotide polymorphisms (SNPs) underlying expression quantitative trait loci (eQTLs) obtained from normal breast tissue, breast cancer tissue and blood were used as genetic instruments for Rho GTPase expression. As a sensitivity analysis, we undertook co-localisation to examine whether findings reflected shared causal variants or genomic confounding. We identified genetic instruments for 14 of the 20 human Rho GTPases. Using eQTLs obtained from normal breast tissue and normal blood, we identified evidence of a causal role of RHOD in overall and ER+ breast cancers (overall breast cancer: odds ratio (OR) per standard deviation (SD) increase in expression level 1.06; (95% confidence interval (CI) 1.03, 1.09; P = 5.65 × 10-5) and OR 1.22 (95% CI 1.11, 1.35; P = 5.22 × 10-5) in normal breast tissue and blood respectively). There was a consistent direction of association for ER- breast cancer, although the effect-estimate was imprecisely estimated. Using eQTLs from breast cancer tissue and normal blood there was some evidence that CDC42 was negatively associated with overall and ER + breast cancer risk. The evidence from colocalization analyses strongly supported our MR results particularly for RHOD. Our study suggests a potential causal role of increased RHOD gene expression, and, although the evidence is weaker, a potential protective role for CDC42 gene expression, in overall and ER+ breast cancers. These finding warrant validation in independent samples and further biological investigation to assess whether they may be suitable targets for drug targeting.

Pathophysiological Mechanisms in Neurodevelopmental Disorders Caused by Rac GTPases Dysregulation: What's behind Neuro-RACopathies

Rho family guanosine triphosphatases (GTPases) regulate cellular signaling and cytoskeletal dynamics, playing a pivotal role in cell adhesion, migration, and cell cycle progression. The Rac subfamily of Rho GTPases consists of three highly homologous proteins, Rac 1-3. The proper function of Rac1 and Rac3, and their correct interaction with guanine nucleotide-exchange factors (GEFs) and GTPase-activating proteins (GAPs) are crucial for neural development. Pathogenic variants affecting these delicate biological processes are implicated in different medical conditions in humans, primarily neurodevelopmental disorders (NDDs). In addition to a direct deleterious effect produced by genetic variants in the RAC genes, a dysregulated GTPase activity resulting from an abnormal function of GEFs and GAPs has been involved in the pathogenesis of distinctive emerging conditions. In this study, we reviewed the current pertinent literature on Rac-related disorders with a primary neurological involvement, providing an overview of the current knowledge on the pathophysiological mechanisms involved in the neuro-RACopathies.

Efficacy of Rac and Cdc42 Inhibitor MBQ-167 in Triple-negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer, with a high predisposition for locally invasive and metastatic cancer. With the objective to reduce cancer metastasis, we developed small molecule inhibitors to target the drivers of metastasis, the Rho GTPases Rac and Cdc42. Of these, MBQ-167 inhibits both Rac and Cdc42 with IC50s of 103 and 78 nmol/L, respectively; and consequently, inhibits p21-activated kinase (PAK) signaling, metastatic cancer cell proliferation, migration, and mammosphere growth; induces cell-cycle arrest and apoptosis; and decreases HER2-type mammary fatpad tumor growth and metastasis (Humphries-Bickley and colleagues, 2017). Herein, we used nuclear magnetic resonance to show that MBQ-167 directly interacts with Rac1 to displace specific amino acids, and consequently inhibits Rac.GTP loading and viability in TNBC cell lines. Phosphokinome arrays in the MDA-MB-231 human TNBC cells show that phosphorylation status of kinases independent of the Rac/Cdc42/PAK pathway are not significantly changed following 200 nmol/L MBQ-167 treatment. Western blotting shows that initial increases in phospho-c-Jun and phospho-CREB in response to MBQ-167 are not sustained with prolonged exposure, as also confirmed by a decrease in their transcriptional targets. MBQ-167 inhibits tumor growth, and spontaneous and experimental metastasis in immunocompromised (human TNBC) and immunocompetent (mouse TNBC) models. Moreover, per oral administration of MBQ-167 at 100 mg/kg body weight is not toxic to immunocompetent BALB/c mice and has a half-life of 4.6 hours in plasma. These results highlight the specificity, potency, and bioavailability of MBQ-167, and support its clinical potential as a TNBC therapeutic.

Molecular targets and therapeutics in chemoresistance of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a specific subtype of breast cancer (BC), which shows immunohistochemically negative expression of hormone receptor i.e., Estrogen receptor and Progesterone receptor along with the absence of Human Epidermal Growth Factor Receptor-2 (HER2/neu). In Indian scenario the prevalence of BC is 26.3%, whereas, in West Bengal the cases are of 18.4%. But the rate of TNBC has increased up to 31% and shows 27% of total BC. Conventional chemotherapy is effective only in the initial stages but with progression of the disease the effectivity gets reduced and shown almost no effect in later or advanced stages of TNBC. Thus, TNBC patients frequently develop resistance and metastasis, due to its peculiar triple-negative nature most of the hormonal therapies also fails. Development of chemoresistance may involve various factors, such as, TNBC heterogeneity, cancer stem cells (CSCs), signaling pathway deregulation, DNA repair mechanism, hypoxia, and other molecular factors. To overcome the challenges to treat TNBC various targets and molecules have been exploited including CSCs modulator, drug efflux transporters, hypoxic factors, apoptotic proteins, and regulatory signaling pathways. Moreover, to improve the targets and efficacy of treatments researchers are emphasizing on targeted therapy for TNBC. In this review, an effort has been made to focus on phenotypic and molecular variations in TNBC along with the role of conventional as well as newly identified pathways and strategies to overcome challenge of chemoresistance.

Addressing activation of WNT beta-catenin pathway in diverse landscape of endometrial carcinogenesis

The WNT-beta-catenin pathway (WP) is one of the major oncogenic pathways in solid tumors. Wnt beta-catenin pathway plays a unique role in a wide range of endometrial dysfunctions, from embryo implantation failure to severe pathogenic changes like endometriosis and endometrial cancer. Although abnormal activation of the pathway has long been known to be associated with endometrial tumorigenesis, the pathway's exact mode of involvement remains to be understood. As more evidence has been presented in favor of a crucial role of the WP in solid tumors, including endometrial cancer, anti-WP drugs are currently being tested to manage the disease. Aggressive tumor cells are nurtured by the tumor microenvironment (TME). The genetic alterations within tumor cells are the primary driving force to activate the extra-tumoral micro-environment. TME (a) provides metabolic support for the proliferation of tumor cells, (b) orchestrates immune-evasion, (c) initiates mechanistic signaling for several metastasis-associated phenotypes, and (d) supports cellular events for the development of drug resistance. To get metabolic as well as immune support from the tumor microenvironment, tumor cells cross-talk with components of the TME, most critically to the cancer-associated fibroblasts. Thus it is expected that the tumor-TME cross-talk throughout the process of tumorigenesis and metastasis is one of the characteristic features of an aggressive tumor. Here we review the WP's mechanistic involvement as a common culprit (Un Colpevole Comune) in endometrial tumor cells and endometrial cancer-associated fibroblast (CAF). In this review, we have attempted to discuss the activation of the WP in the genesis and progression of endometrial cancers, including endometrial tumor biology, tumor microenvironment, cancer-associated fibroblasts, and wnt-beta catenin genetic alteration. We interrogated the available literature on the various aspects of endometrial carcinogenesis leading to the pathway's activation. We examined how genetic alterations in WP directly influence tumor cell signaling to bring out different tumor cell phenotypes, and present palpable evidence to envision a role of WP inhibitors in the future management of the disease.

Inhibition of Wnt-β-Catenin Signaling by ICRT14 Drug Depends of Post-Transcriptional Regulation by HOTAIR in Human Cervical Cancer HeLa Cells

BACKGROUND

In Cervical cancer (CC), in addition to HPV infection, the most relevant alteration during CC initiation and progression is the aberrant activation of Wnt/β-catenin pathway. Several inhibitory drugs of this pathway are undergoing preclinical and clinical studies. Long non-coding RNAs (lncRNAs) are associated with resistance to treatments. In this regard, understanding the efficiency of drugs that block the Wnt/β-catenin pathway in CC is of relevance to eventually propose successful target therapies in patients with this disease.

METHODS

We analyzed the levels of expression of 249 components of the Wnt/β-catenin pathway in a group of 109 CC patients. Three drugs that blocking specific elements of Wnt/β-catenin pathway (C59, NSC668036 and ICRT14) by TOP FLASH assays and qRT-PCR were tested in vitro in CC cells.

RESULTS

137 genes of the Wnt/β-catenin pathway were up-regulated and 112 down-regulated in CC patient's samples, demonstrating that this pathway is dysregulated. C59 was an efficient drug to inhibit Wnt/β-catenin pathway in CC cells. NSC668036, was not able to inhibit the transcriptional activity of the Wnt/β-catenin pathway. Strikingly, ICRT14 was neither able to inhibit this pathway in HeLa cells, due to HOTAIR interaction with β-catenin, maintaining the Wnt/β-catenin pathway activated.

CONCLUSIONS

These results demonstrate a mechanism by which HOTAIR evades the effect of ICRT14, a Wnt/β-catenin pathway inhibitory drug, in HeLa cell line. The emergence of these mechanisms reveals new scenarios in the design of target therapies used in cancer.

Inhibition of RAC1 activity in cancer associated fibroblasts favours breast tumour development through IL-1β upregulation

Cancer-associated fibroblasts (CAFs) are highly abundant stromal components in the tumour microenvironment. These cells contribute to tumorigenesis and indeed, they have been proposed as a target for anti-cancer therapies. Similarly, targeting the Rho-GTPase RAC1 has also been suggested as a potential therapeutic target in cancer. Here, we show that targeting RAC1 activity, either pharmacologically or by genetic silencing, increases the pro-tumorigenic activity of CAFs by upregulating IL-1β secretion. Moreover, inhibiting RAC1 activity shifts the CAF subtype to a more aggressive phenotype. Thus, as RAC1 suppresses the secretion of IL-1β by CAFs, reducing RAC1 activity in combination with the depletion of this cytokine should be considered as an interesting therapeutic option for breast cancer in which tumour cells retain intact IL-1β signalling.

Regulatory interplay between Vav1, Syk and β-catenin occurs in lung cancer cells

Vav1 exhibits two signal transducing properties as an adaptor protein and a regulator of cytoskeleton organization through its Guanine nucleotide Exchange Factor module. Although the expression of Vav1 is restricted to the hematopoietic lineage, its ectopic expression has been unraveled in a number of solid tumors. In this study, we show that in lung cancer cells, as such in hematopoietic cells, Vav1 interacts with the Spleen Tyrosine Kinase, Syk. Likewise, Syk interacts with β-catenin and, together with Vav1, regulates the phosphorylation status of β-catenin. Depletion of Vav1, Syk or β-catenin inhibits Rac1 activity and decreases cell migration suggesting the interplay of the three effectors to a common signaling pathway. This model is further supported by the finding that in turn, β-catenin regulates the transcription of Syk gene expression. This study highlights the elaborated connection between Vav1, Syk and β-catenin and the contribution of the trio to cell migration.

Prognostic signatures associated with high infiltration of Tregs in bone metastatic prostate cancer

Metastatic cancer especially bone metastasis (BM) is the lethal end-stage of castration-resistant prostate cancer (CRPC). To understand the possible molecular mechanisms underlying the development of the distant metastasis is of potential clinical value. We sought to identify differentially expressed genes between patient-matched primary and bone metastatic CRPC tumors. Functional enrichment, protein-protein interaction networks, and survival analysis of DEGs were performed. DEGs with a prognostic value considered as candidate genes were evaluated, followed by genetic analysis of tumor infiltrating immune cells based on Wilcoxon test and immunofluorescence identification. Expression profiles analysis showed that 381 overlapping genes were screened as differentially expressed genes (DEGs), of which 16 DEGs were randomly selected to be validated and revealed that most of these genes showed a transcriptional profile similar to that seen in the datasets (Pearson’s r = 0.76). Six core genes were found to be involved in regulation of extracellular matrix receptor interaction and chemotactic activity, and four of them were significantly correlated with the survival of PCa patients with bone metastases. Immune infiltration analysis showed that the expressions levels of COL3A1, RAC1, FN1, and SDC2 in CD4+T cells were significantly higher than those in tumor cells, especially regulatory T cell infiltration was significantly increased in BM tumors. We analyzed gene expression signatures specifically associated with the development of bone metastases of CRPC patients. Characterization of genes associated with BM of mCRPC is critical for identification of predictive biomarkers and potential therapeutic targets.

Therapeutic Strategies for Metastatic Triple-Negative Breast Cancers: From Negative to Positive

Metastatic triple-negative breast cancer (TNBC) is a distinct and immensely complex form of breast cancer. Among all subtypes of breast cancers, TNBC has a comparatively high rate of relapse, a high rate of distant metastasis, and poor overall survival after standard chemotherapy. Chemotherapy regimens are an essential component of the management of this estrogen receptor-negative, progesterone receptor-negative, and epidermal growth factor receptor2 negative subtype of breast cancers. Chemotherapy is critical for preventing the recurrence of the disease and for achieving long-term survival. Currently, a couple of agents are approved for the management of this disease, including chemotherapy like eribulin, targeted therapy like PARP inhibitor, as well as an antibody-drug conjugate (ADC) to target TROP2. Like many other metastatic cancers, immune checkpoint inhibitors (ICIs) have also been approved for TNBC patients with PD-L1 positive tumors and high tumor mutational burden. In this review article, we discuss these newly approved and promising novel agents that may change the therapeutic landscape for advanced/metastatic TNBC patients.

An Overview of Potential Therapeutic Agents Targeting WNT/PCP Signaling

Since the discovery of the proto-oncogene Wnt1 (Int1) in 1982, WNT signaling has been identified as one of the most important pathways that regulates a wide range of fundamental developmental and physiological processes in multicellular organisms. The canonical WNT signaling pathway depends on the stabilization and translocation of β-catenin and plays important roles in development and homeostasis. The WNT/planar cell polarity (WNT/PCP) signaling, also known as one of the β-catenin-independent WNT pathways, conveys directional information to coordinate polarized cell behaviors. Similar to WNT/β-catenin signaling, disruption or aberrant activation of WNT/PCP signaling also underlies a variety of developmental defects and cancers. However, the pharmacological targeting of WNT/PCP signaling for therapeutic purposes remains largely unexplored. In this review, we briefly discuss WNT/PCP signaling in development and disease and summarize the known drugs/inhibitors targeting this pathway.

Systematic investigation of promoter substitutions resulting from somatic intrachromosomal structural alterations in diverse human cancers

One of the ways in which genes can become activated in tumors is by somatic structural genomic rearrangements leading to promoter swapping events, typically in the context of gene fusions that cause a weak promoter to be substituted for a strong promoter. While identifiable by whole genome sequencing, limited availability of this type of data has prohibited comprehensive study of the phenomenon. Here, we leveraged the fact that copy number alterations (CNAs) arise as a result of structural alterations in DNA, and that they may therefore be informative of gene rearrangements, to pinpoint recurrent promoter swapping at a previously intractable scale. CNA data from nearly 9500 human tumors was combined with transcriptomic sequencing data to identify several cases of recurrent activating intrachromosomal promoter substitution events, either involving proper gene fusions or juxtaposition of strong promoters to gene upstream regions. Our computational screen demonstrates that a combination of CNA and expression data can be useful for identifying novel fusion events with potential driver roles in large cancer cohorts.

Rho GTPases: Big Players in Breast Cancer Initiation, Metastasis and Therapeutic Responses

Rho GTPases, a family of the Ras GTPase superfamily, are key regulators of the actin cytoskeleton. They were originally thought to primarily affect cell migration and invasion; however, recent advances in our understanding of the biology and function of Rho GTPases have demonstrated their diverse roles within the cell, including membrane trafficking, gene transcription, migration, invasion, adhesion, survival and growth. As these processes are critically involved in cancer initiation, metastasis and therapeutic responses, it is not surprising that studies have demonstrated important roles of Rho GTPases in cancer. Although the majority of data indicates an oncogenic role of Rho GTPases, tumor suppressor functions of Rho GTPases have also been revealed, suggesting a context and cell-type specific function for Rho GTPases in cancer. This review aims to summarize recent progresses in our understanding of the regulation and functions of Rho GTPases, specifically in the context of breast cancer. The potential of Rho GTPases as therapeutic targets and prognostic tools for breast cancer patients are also discussed.

Active RAC1 Promotes Tumorigenic Phenotypes and Therapy Resistance in Solid Tumors

Acting as molecular switches, all three members of the Guanosine triphosphate (GTP)-ase-family, Ras-related C3 botulinum toxin substrate (RAC), Rho, and Cdc42 contribute to various processes of oncogenic transformations in several solid tumors. We have reviewed the distribution of patterns regarding the frequency of Ras-related C3 botulinum toxin substrate 1 (RAC1)-alteration(s) and their modes of actions in various cancers. The RAC1 hyperactivation/copy-number gain is one of the frequently observed features in various solid tumors. We argued that RAC1 plays a critical role in the progression of tumors and the development of resistance to various therapeutic modalities applied in the clinic. With this perspective, here we interrogated multiple functions of RAC1 in solid tumors pertaining to the progression of tumors and the development of resistance with a special emphasis on different tumor cell phenotypes, including the inhibition of apoptosis and increase in the proliferation, epithelial-to-mesenchymal transition (EMT), stemness, pro-angiogenic, and metastatic phenotypes. Our review focuses on the role of RAC1 in adult solid-tumors and summarizes the contextual mechanisms of RAC1 involvement in the development of resistance to cancer therapies.

Cytotoxic and Antimetastatic Activity of Hesperetin and Doxorubicin Combination Toward Her2 Expressing Breast Cancer Cells

OBJECTIVE

This study aimed to explore Hesperetin (Hst) potency as a co-chemotherapeutics agent combined with Doxorubicin (Dox), particularly cytotoxic and antimetastasis effects toward MCF-7/HER2 cells.

METHODS

The cytotoxic effects were measured under MTT assay. The flowcytometry analysis was used to examine the cell cycle modulation and apoptosis evidence, while the effect of migration was assayed by scratch wound healing assay. Western blotting and gelatin zymography were carried out to examine the expression level of proteins, HER2, and Rac1.

RESULTS

Under MTT assay, Hst and Dox exhibited to decrease cell viability in a dose-dependent manner with the IC50 value of 377 and 0,8 µM, respectively. The combination of Hst and Dox at the respective doses of 95 and 0,2 µM showed a synergistic effect with the combination index of 0,63. Flow cytometry analysis of Hst-Dox revealed that those compounds caused cell cycle arrest at the G2/M phase and induced apoptosis. Hst also decreased HER2 and Rac1 expression, as shown by western blot. Hst inhibited lamellipodia formation and cell migration, as indicated by microscopic observation and wound healing scratch assay. The antimetastatic activity of Hst was associated with the reduction of Rac1 and MMP9 expression as measured by gelatine zymography assay.

CONCLUSION

These results indicated that the combination of Hst and Dox-induced cell cycle arrest, apoptosis, decreased HER2, Rac1, MMP9 expression, and cell migration. Thus, Hst may have the potential to be developed as a co-chemotherapeutic agent combined with doxorubicin toward HER2 overexpressing breast cancer cells.

Wnt-C59 Attenuates Pressure Overload-Induced Cardiac Hypertrophy via Interruption of Wnt Pathway

Background

Cardiac hypertrophy usually results in heart failure and is an important cause of mortality worldwide. Wnt/β-catenin signaling pathway hyper-activation is involved in the pathogenesis and progression of cardiac hypertrophy. Wnt-C59 is a small molecular compound, which strongly and specifically targets at Porcupine to pharmacologically inhibit Wnt palmitoylation, secretion, and other biological activities. However, the role of Wnt-C59 in cardiac hypertrophy remains unknown.

Material/Methods

We performed transverse aortic constriction (TAC) in adult male mice to induce pressure overload and establish an in vivo model of cardiac hypertrophy. Angiotensin II (Ang-II) was utilized to culture cardiomyocyte to establish a model of in vitro cardiomyocyte hypertrophy. Daily administration of Porcupine inhibitor Wnt-C59 was performed for 4 weeks after TAC surgery.

Results

Wnt-C59 significantly improved cardiac function and enhanced survival of mice subjected to TAC surgery. Histologically, Wnt-C59 attenuated TAC-induced increase in heart mass, cross-section area of cardiomyocyte, cardiac fibrosis, cardiomyocyte apoptosis, and expression of the hypertrophic biomarkers β-MHC, ANP, and BNP. TAC-induced oxidative stress was also ameliorated by Wnt-C59. Wnt-C59 attenuated Ang-II-induced in vitro cardiomyocyte hypertrophy, as indicated by decreased cell size and lower expression of ANP, BNP, and β-MHC. Moreover, Wnt/β-catenin activation was blocked by Wnt-C59 in cardiac hypertrophy, as indicated by decreased protein expression of Wnt3a and β-catenin and the Wnt target genes cyclin D1 and c-Myc.

Conclusions

Collectively, Porcupine inhibitor Wnt-C59 attenuates pressure overload-induced cardiac hypertrophic via interruption of the Wnt/β-catenin signaling pathway, and it might be a promising drug for patients with cardiac hypertrophy.

Targeting Rac and Cdc42 GEFs in Metastatic Cancer

The Rho family GTPases Rho, Rac, and Cdc42 have emerged as key players in cancer metastasis, due to their essential roles in regulating cell division and actin cytoskeletal rearrangements; and thus, cell growth, migration/invasion, polarity, and adhesion. This review will focus on the close homologs Rac and Cdc42, which have been established as drivers of metastasis and therapy resistance in multiple cancer types. Rac and Cdc42 are often dysregulated in cancer due to hyperactivation by guanine nucleotide exchange factors (GEFs), belonging to both the diffuse B-cell lymphoma (Dbl) and dedicator of cytokinesis (DOCK) families. Rac/Cdc42 GEFs are activated by a myriad of oncogenic cell surface receptors, such as growth factor receptors, G-protein coupled receptors, cytokine receptors, and integrins; consequently, a number of Rac/Cdc42 GEFs have been implicated in metastatic cancer. Hence, inhibiting GEF-mediated Rac/Cdc42 activation represents a promising strategy for targeted metastatic cancer therapy. Herein, we focus on the role of oncogenic Rac/Cdc42 GEFs and discuss the recent advancements in the development of Rac and Cdc42 GEF-interacting inhibitors as targeted therapy for metastatic cancer, as well as their potential for overcoming cancer therapy resistance.

Knockdown of lncRNA LSINCT5 suppresses growth and metastasis of human glioma cells via up-regulating miR-451

Background: Glioma is a main cause of brain-cancer relevant death. The present paper designed to reveal the possible role of LSINCT5 in human glioma GL15 cells. Methods: LSINCT5 and miR-451 expression in glioma tissues was examined using qRT-PCR. The impacts of LSINCT5, miR-451 and Rac1 in GL15 cells were checked by carrying out CCK-8 assay, transwell assay, and flow cytometric analysis. Further, the target gene of LSINCT5 and miR-451 was explored. Accumulation of PI3K/AKT, Wnt/β-catenin and NF-κB pathway proteins was examined using Western blot. Results: LSINCT5 was highly expressed while miR-451 low expressed in glioma tissues when compared to normal controls. Down-regulating LSINCT5 effectively declined GL15 cells viability, migration and invasion, but accelerated apoptosis. Nonetheless, the above-mentioned effects of LSINCT5 down-regulation were weakened when miR-451 was silenced. Rac1 was a target of miR-451. The tumour-suppressive effects of miR-451 on GL15 cells were weakened when Rac1 was overexpressed. Further, LSINCT5-miR-451-Rac1 axis could impact the activation of PI3K/AKT, Wnt/β-catenin and NF-κB pathways. Conclusion: Down-regulation of LSINCT5 represses glioma cells growth and metastasis in vitro likely through targeting miR-451 and thereby inhibiting Rac1-regulated PI3K/AKT, Wnt/β-catenin and NF-κB pathways.

TUFT1 Promotes Triple Negative Breast Cancer Metastasis, Stemness, and Chemoresistance by Up-Regulating the Rac1/β-Catenin Pathway

Objectives: Triple negative breast cancer (TNBC) is a subtype of breast cancer with stronger invasion and metastasis, but its specific mechanism of action is still unclear. Tuft1 plays an important regulatory role in the survival of breast cancer cells; however, its role in regulating TNBC metastatic potential has not been well-characterized. Our aim was therefore to systematically study the mechanism of TUFT1 in the metastasis, stemness, and chemoresistance of TNBC and provide new predictors and targets for BC treatment. Methods: We used western blotting and IHC to measure TUFT1and Rac1-GTP expression levels in both human BC samples and cell lines. A combination of shRNA, migration/invasion assays, sphere formation assay, apoptosis assays, nude mouse xenograft tumor model, and GTP activity assays was used for further mechanistic studies. Results: We demonstrated that silencing TUFT1 in TNBC cells significantly inhibited cell metastasis and stemness in vitro. A nude mouse xenograft tumor model revealed that TUFT1 knockdown greatly decreased spontaneous lung metastasis of TNBC tumors. Mechanism studies showed that TUFT1 promoted tumor cell metastasis and stemness by up-regulating the Rac1/β-catenin pathway. Moreover, mechanistic studies indicated that the lack of TUFT1 expression in TNBC cells conferred more sensitive to chemotherapy and increased cell apoptosis via down-regulating the Rac1/β-catenin signaling pathway. Further, TUFT1 expression positively correlated with Rac1-GTP in TNBC samples, and co-expression of TUFT1 and Rac1-GTP predicted poor prognosis in TNBC patients who treated with chemotherapy. Conclusion: Our findings suggest that TUFT1/Rac1/β-catenin pathway may provide a potential target for more effective treatment of TNBC.

RAC1 Takes the Lead in Solid Tumors

Three GTPases, RAC, RHO, and Cdc42, play essential roles in coordinating many cellular functions during embryonic development, both in healthy cells and in disease conditions like cancers. We have presented patterns of distribution of the frequency of RAC1-alteration(s) in cancers as obtained from cBioPortal. With this background data, we have interrogated the various functions of RAC1 in tumors, including proliferation, metastasis-associated phenotypes, and drug-resistance with a special emphasis on solid tumors in adults. We have reviewed the activation and regulation of RAC1 functions on the basis of its sub-cellular localization in tumor cells. Our review focuses on the role of RAC1 in cancers and summarizes the regulatory mechanisms, inhibitory efficacy, and the anticancer potential of RAC1-PAK targeting agents.

Identification of Triple-Negative Breast Cancer Genes and a Novel High-Risk Breast Cancer Prediction Model Development Based on PPI Data and Support Vector Machines

Triple-negative breast cancer (TNBC) is a special subtype of breast cancer that is difficult to treat. It is crucial to identify breast cancer-related genes that could provide new biomarkers for breast cancer diagnosis and potential treatment goals. In the development of our new high-risk breast cancer prediction model, seven raw gene expression datasets from the NCBI gene expression omnibus (GEO) database (GSE31519, GSE9574, GSE20194, GSE20271, GSE32646, GSE45255, and GSE15852) were used. Using the maximum relevance minimum redundancy (mRMR) method, we selected significant genes. Then, we mapped transcripts of the genes on the protein-protein interaction (PPI) network from the Search Tool for the Retrieval of Interacting Genes (STRING) database, as well as traced the shortest path between each pair of proteins. Genes with higher betweenness values were selected from the shortest path proteins. In order to ensure validity and precision, a permutation test was performed. We randomly selected 248 proteins from the PPI network for shortest path tracing and repeated the procedure 100 times. We also removed genes that appeared more frequently in randomized results. As a result, 54 genes were selected as potential TNBC-related genes. Using 14 out the 54 genes, which are potential TNBC associated genes, as input features into a support vector machine (SVM), a novel model was trained to predict high-risk breast cancer. The prediction accuracy of normal tissues and TNBC tissues reached 95.394%, and the predictions of Stage II and Stage III TNBC reached 86.598%, indicating that such genes play important roles in distinguishing breast cancers, and that the method could be promising in practical use. According to reports, some of the 54 genes we identified from the PPI network are associated with breast cancer in the literature. Several other genes have not yet been reported but have functional resemblance with known cancer genes. These may be novel breast cancer-related genes and need further experimental validation. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to appraise the 54 genes. It was indicated that cellular response to organic cyclic compounds has an influence in breast cancer, and most genes may be related with viral carcinogenesis.

Focus on Cdc42 in Breast Cancer: New Insights, Target Therapy Development and Non-Coding RNAs

Breast cancer is the most common malignant tumors in females. Although the conventional treatment has demonstrated a certain effect, some limitations still exist. The Rho guanosine triphosphatase (GTPase) Cdc42 (Cell division control protein 42 homolog) is often upregulated by some cell surface receptors and oncogenes in breast cancer. Cdc42 switches from inactive guanosine diphosphate (GDP)-bound to active GTP-bound though guanine-nucleotide-exchange factors (GEFs), results in activation of signaling cascades that regulate various cellular processes such as cytoskeletal changes, proliferation and polarity establishment. Targeting Cdc42 also provides a strategy for precise breast cancer therapy. In addition, Cdc42 is a potential target for several types of non-coding RNAs including microRNAs and lncRNAs. These non-coding RNAs is extensively involved in Cdc42-induced tumor processes, while many of them are aberrantly expressed. Here, we focus on the role of Cdc42 in cell morphogenesis, proliferation, motility, angiogenesis and survival, introduce the Cdc42-targeted non-coding RNAs, as well as present current development of effective Cdc42-targeted inhibitors in breast cancer.

The Role of Tumor Microenvironment in Chemoresistance: 3D Extracellular Matrices as Accomplices

BACKGROUND

The functional interplay between tumor cells and their adjacent stroma has been suggested to play crucial roles in the initiation and progression of tumors and the effectiveness of chemotherapy. The extracellular matrix (ECM), a complex network of extracellular proteins, provides both physical and chemicals cues necessary for cell proliferation, survival, and migration. Understanding how ECM composition and biomechanical properties affect cancer progression and response to chemotherapeutic drugs is vital to the development of targeted treatments.

METHODS

3D cell-derived-ECMs and esophageal cancer cell lines were used as a model to investigate the effect of ECM proteins on esophageal cancer cell lines response to chemotherapeutics. Immunohistochemical and qRT-PCR evaluation of ECM proteins and integrin gene expression was done on clinical esophageal squamous cell carcinoma biopsies. Esophageal cancer cell lines (WHCO1, WHCO5, WHCO6, KYSE180, KYSE 450 and KYSE 520) were cultured on decellularised ECMs (fibroblasts-derived ECM; cancer cell-derived ECM; combinatorial-ECM) and treated with 0.1% Dimethyl sulfoxide (DMSO), 4.2 µM cisplatin, 3.5 µM 5-fluorouracil and 2.5 µM epirubicin for 24 h. Cell proliferation, cell cycle progression, colony formation, apoptosis, migration and activation of signaling pathways were used as our study endpoints.

RESULTS

The expression of collagens, fibronectin and laminins was significantly increased in esophageal squamous cell carcinomas (ESCC) tumor samples compared to the corresponding normal tissue. Decellularised ECMs abrogated the effect of drugs on cancer cell cycling, proliferation and reduced drug induced apoptosis by 20⁻60% that of those plated on plastic. The mitogen-activated protein kinase-extracellular signal-regulated kinase (MEK-ERK) and phosphoinositide 3-kinase-protein kinase B (PI3K/Akt) signaling pathways were upregulated in the presence of the ECMs. Furthermore, our data show that concomitant addition of chemotherapeutic drugs and the use of collagen- and fibronectin-deficient ECMs through siRNA inhibition synergistically increased cancer cell sensitivity to drugs by 30⁻50%, and reduced colony formation and cancer cell migration.

CONCLUSION

Our study shows that ECM proteins play a key role in the response of cancer cells to chemotherapy and suggest that targeting ECM proteins can be an effective therapeutic strategy against chemoresistant tumors.

Triple Fluorescence staining to Evaluate Mechanism-based Apoptosis following Chemotherapeutic and Targeted Anti-cancer Drugs in Live Tumor Cells

We present a protocol for live cancer cell-imaging by triple-fluorescent staining to test 3 crucial mechanisms of apoptosis; the enzymatic activity of executioner caspase3, caspase-dependent phosphatidylserine presentation on the cell surface and mitochondrial function. We standardized a protocol to co-stain live tumor cells with the NucView488-Casp3 substrate, CF594 AnnexinV, and MitoViewBlue. We validated this protocol following apoptosis induction with paclitaxel or in combination with BKM120. Fluorescent imaging of cells using simultaneous live/dead cell markers (CalceinAM green/EthD-1red) was used as internal control. We used quantitative confluence (Essen), AnnexinV-PE staining (Accuri C6), expression of cl-caspase3, Cl-PARP and mitochondrial potential (TMRE-A) as validation criteria in A2780 and OVK18 cells following drug treatment which decreased proliferation, & increased apoptotic signaling with mitochondrial depolarization. Treatment blocked cytoplasmic MitoViewBlue staining while increased both nuclear NucView488-Casp3 substrate and red membranous CF594 AnnexinV staining. Merged images showed 100% mutual exclusivity between MitoViewBlue and caspase3 or AnnexinV stains in control and treated cells as determined by overlap and colocalization coefficients. Caspase3 and AnnexinV staining in treated cells were both separate and overlapped (yellow fluorescence) indicating the sequence of apoptotic-events. The protocol will help in deciphering mechanistic involvement of different stages/features of apoptosis in tumor cell following anti-cancer drugs in real-time.

Porcupine inhibitors impair trabecular and cortical bone mass and strength in mice

WNT signaling is involved in the tumorigenesis of various cancers and regulates bone homeostasis. Palmitoleoylation of WNTs by Porcupine is required for WNT activity. Porcupine inhibitors are under development for cancer therapy. As the possible side effects of Porcupine inhibitors on bone health are unknown, we determined their effects on bone mass and strength. Twelve-week-old C57BL/6N female mice were treated by the Porcupine inhibitors LGK974 (low dose = 3 mg/kg/day; high dose = 6 mg/kg/day) or Wnt-C59 (10 mg/kg/day) or vehicle for 3 weeks. Bone parameters were assessed by serum biomarkers, dual-energy X-ray absorptiometry, µCT and histomorphometry. Bone strength was measured by the 3-point bending test. The Porcupine inhibitors were well tolerated demonstrated by normal body weight. Both doses of LGK974 and Wnt-C59 reduced total body bone mineral density compared with vehicle treatment (P < 0.001). Cortical thickness of the femur shaft (P < 0.001) and trabecular bone volume fraction in the vertebral body (P < 0.001) were reduced by treatment with LGK974 or Wnt-C59. Porcupine inhibition reduced bone strength in the tibia (P < 0.05). The cortical bone loss was the result of impaired periosteal bone formation and increased endocortical bone resorption and the trabecular bone loss was caused by reduced trabecular bone formation and increased bone resorption. Porcupine inhibitors exert deleterious effects on bone mass and strength caused by a combination of reduced bone formation and increased bone resorption. We suggest that cancer targeted therapies using Porcupine inhibitors may increase the risk of fractures.

Targeting Rac and Cdc42 GTPases in Cancer

Rac and Cdc42 are small GTPases that have been linked to multiple human cancers and are implicated in epithelial to mesenchymal transition, cell-cycle progression, migration/invasion, tumor growth, angiogenesis, and oncogenic transformation. With the exception of the P29S driver mutation in melanoma, Rac and Cdc42 are not generally mutated in cancer, but are overexpressed (gene amplification and mRNA upregulation) or hyperactivated. Rac and Cdc42 are hyperactivated via signaling through oncogenic cell surface receptors, such as growth factor receptors, which converge on the guanine nucleotide exchange factors that regulate their GDP/GTP exchange. Hence, targeting Rac and Cdc42 represents a promising strategy for precise cancer therapy, as well as for inhibition of bypass signaling that promotes resistance to cell surface receptor-targeted therapies. Therefore, an understanding of the regulatory mechanisms of these pivotal signaling intermediates is key for the development of effective inhibitors. In this review, we focus on the role of Rac and Cdc42 in cancer and summarize the regulatory mechanisms, inhibitory efficacy, and the anticancer potential of Rac- and Cdc42-targeting agents. Cancer Res; 78(12); 3101-11. ©2018 AACR.

Co-targeting of Tiam1/Rac1 and Notch ameliorates chemoresistance against doxorubicin in a biomimetic 3D lymphoma model

Lymphoma is a heterogeneous disease with a highly variable clinical course and prognosis. Improving the prognosis for patients with relapsed and treatment-resistant lymphoma remains challenging. Current in vitro drug testing models based on 2D cell culture lack natural tissue-like structural organization and result in disappointing clinical outcomes. The development of efficient drug testing models using 3D cell culture that more accurately reflects in vivo behaviors is vital. Our aim was to establish an in vitro 3D lymphoma model that can imitate the in vivo 3D lymphoma microenvironment. Using this model, we explored strategies to enhance chemosensitivity to doxorubicin, an important chemotherapeutic drug widely used for the treatment of hematological malignancies. Lymphoma cells grown in this model exhibited excellent biomimetic properties compared to conventional 2D culture including (1) enhanced chemotherapy resistance, (2) suppressed rate of apoptosis, (3) upregulated expression of drug resistance genes (MDR1, MRP1, BCRP and HIF-1α), (4) elevated levels of tumor aggressiveness factors including Notch (Notch-1, -2, -3, and -4) and its downstream molecules (Hes-1 and Hey-1), VEGF and MMPs (MMP-2 and MMP-9), and (5) enrichment of a lymphoma stem cell population. Tiam1, a potential biomarker of tumor progression, metastasis, and chemoresistance, was activated in our 3D lymphoma model. Remarkably, we identified two synergistic therapeutic oncotargets, Tiam1 and Notch, as a strategy to combat resistance against doxorubicin in EL4 T and A20 B lymphoma. Therefore, our data suggest that our 3D lymphoma model is a promising in vitro research platform for studying lymphoma biology and therapeutic approaches.

Down's Syndrome and Triple Negative Breast Cancer: A Rare Occurrence of Distinctive Clinical Relationship

Down’s syndrome (DS), the most common genetic cause of significant intellectual disability in children and adults is caused by the trisomy of either all or a part of human chromosome 21 (HSA21). Patients with DS mostly suffer from characteristic tumor types. Although individual patients of DS are at a higher risk for acute leukemia and testicular cancers, other types of solid tumors including breast cancers are mostly uncommon and have significantly lower-than-expected age-adjusted incidence rates. Except for an increased risk of retinoblastomas, and lymphomas, the risk of developing solid tumors has been found to be lower in both children and adults, and breast cancer was found to be almost absent (Hasle H., The Lancet Oncology, 2001). A study conducted in the United States found only one death when 11.65 were expected (Scholl T et al., Dev Med Child Neurol. 1982). A recent study examined mammogram reports of women with DS treated in the largest medical facility specifically serving adults with DS in the United States. It was found that only 0.7% women with DS had been diagnosed with breast cancers (Chicoine B et al., Intellect Dev Disabil. 2015). Here we describe a case of breast cancer in a 25-year-old patient with DS. The disease was presented as lymph node positive carcinoma with alterations of tumor suppressor genes characteristic to the triple negative breast cancer subtype. Comprehensive Genomic Profiling (CGP) revealed a wild-type status for BRCA1. The CGP report showed a frameshift mutation, A359fs*10 of the tumor suppressor gene INPP4B and another frameshift mutation, R282fs*63 of tumor suppressor gene TP53 in the tumor biopsy as characteristically found in triple-negative breast cancers. The VUS (Variance of Unknown Significance) alteration(s) were identified in ASXL1 (L1395V), NTRK1 (G18E), DDR2 (I159T), RUNX1 (amplification), ERG (amplification), SOX2 (T26A), FAM123B (G1031D), and HNF1A (A301T). Bonafide cancer-related genes of chromosome 21 amplified in the patient’s tumor are RUNX1 and ERG genes. After the completion of the radiation, the patient was placed on everolimus which was based on the result of her CGP report. Thus, post-mastectomy radiation therapy was completed with a recommendation for everolimus for one year. During the time of writing of this report, no metastatic lesions were identified. The patient currently has no evidence of disease.

Cadmium stimulates metastasis-associated phenotype in triple-negative breast cancer cells through integrin and β-catenin signaling

Cadmium (Cd) is a carcinogenic heavy metal which is implicated in breast cancer development. While the mechanisms of Cd-induced breast cancer initiation and promotion have been studied, the molecular processes involved in breast cancer progression remain to be investigated. The purpose of the present study was to evaluate the influence of Cd on metastasis-associated phenotypes, such as cell adhesion, migration, and invasion in triple-negative breast cancer cells. Treatment of MDA-MB-231 cells with 1μM Cd increased cell spreading and cell migration. This was associated with the activation of integrin β1, FAK, Src, and Rac1. Treatment with Cd also inhibited GSK3β activity and induced T-cell factor/lymphoid enhancer factor (TCF/LEF) transcription, indicating the involvement of β-catenin signaling. Furthermore, treatment with 3μM Cd for 4weeks increased the expression of β-catenin and enhanced TCF/LEF-mediated transcription. Furthermore, enhanced expressions of integrins α5 and β1, paxillin, and vimentin indicated that prolonged Cd treatment reorganized the cytoskeleton, which aided malignancy, as evidenced by enhanced matrix metalloprotease 2/9 (MMP2/9) secretion and cell invasion. Prolonged Cd treatment also caused an increase in cell growth. Together, these results indicate that Cd alters key signaling processes involved in the regulation of cytoskeleton to enhance cancer cell migration, invasion, adhesion, and proliferation.