Dual Inhibition of Key Proliferation Signaling Pathways in Triple-Negative Breast Cancer Cells by a Novel Derivative of Taiwanin A

Dysregulated Gab1 signalling in triple negative breast cancer

BACKGROUND

Breast cancer is the most common cancer in women worldwide. Triple-negative breast cancer (TNBC) is especially aggressive and associated with high metastasis. The aetiology of TNBC is heterogeneous and characterised by multiple different mutations that amongst others cause constitutive and dysregulated MAPK and PI3K signalling. Additionally, in more than 50% of TNBC patients, the epidermal growth factor receptor (EGFR) is overexpressed and constitutively active. The multi-site docking protein Grb2-associated binder 1 (Gab1) is a central signalling hub that connects MAPK and PI3K signalling.

METHODS

Expression and activation of members of the Gab1/PI3K/MAPK signalling network were assessed in cells from different breast cancer subtypes. Influence of short- and long-term inhibition of EGFR, MAPK and PI3K on the activation of the Gab1/PI3K/MAPK signalling network as well as on cell viability, proliferation and migration was determined. Additionally, cellular localisation of Gab1 and Gab1 variants in naive cells and cells treated with the above-mentioned inhibitors was investigated.

RESULTS

We show that, activation of the Gab1/PI3K/MAPK signalling network is heterogeneous between different breast cancer subtypes. Gab1 phosphorylation and plasma membrane recruitment of Gab1 are dysregulated in the EGFRhigh TNBC cell line MDA-MB-468. While the Gab1/MAPK/PI3K signalling network follows canonical Gab1 signalling in naive MDA-MB-468 cells, Gab1 signalling is changed in cells that acquired resistance towards MAPK and PI3K inhibition. In resistant cells, Gab1 is not located at the plasma membrane despite strong activation of PI3K and MAPK. Furthermore, Gab1 tyrosine phosphorylation is uncoupled from plasma membrane recruitment.

CONCLUSION

Our study indicates that Gab1 signalling changes fundamentally during the acquisition of resistance to pharmacological inhibitors. Given the molecular heterogeneity between breast cancer subtypes, the detailed understanding of dysregulated and aberrant signalling is an absolute necessity in order to develop personalised therapies for patients with TNBC.

Systems-level analyses of protein-protein interaction network dysfunctions via epichaperomics identify cancer-specific mechanisms of stress adaptation

Systems-level assessments of protein-protein interaction (PPI) network dysfunctions are currently out-of-reach because approaches enabling proteome-wide identification, analysis, and modulation of context-specific PPI changes in native (unengineered) cells and tissues are lacking. Herein, we take advantage of chemical binders of maladaptive scaffolding structures termed epichaperomes and develop an epichaperome-based 'omics platform, epichaperomics, to identify PPI alterations in disease. We provide multiple lines of evidence, at both biochemical and functional levels, demonstrating the importance of these probes to identify and study PPI network dysfunctions and provide mechanistically and therapeutically relevant proteome-wide insights. As proof-of-principle, we derive systems-level insight into PPI dysfunctions of cancer cells which enabled the discovery of a context-dependent mechanism by which cancer cells enhance the fitness of mitotic protein networks. Importantly, our systems levels analyses support the use of epichaperome chemical binders as therapeutic strategies aimed at normalizing PPI networks.

1-(4-((5-chloro-4-((2-(isopropylsulfonyl)phenyl)amino)pyrimidin-2-yl)amino)-3-methoxyphenyl)-3-(2-(dimethylamino)ethyl)imidazolidin-2-one (ZX-42) inhibits cell proliferation and induces apoptosis via inhibiting ALK and its downstream pathways in Karpas299 cells

Anaplastic lymphoma kinase (ALK) belongs to the family of receptor tyrosine kinases. Recently, the incidence of anaplastic large cell lymphoma (ALCL) with ALK rearrangement has raised considerably. The application of ALK-targeted inhibitors such as ceritinib provides an effective therapy for the treatment of ALK-positive cancers. However, with the prolongation of treatment time, the emergence of resistance is inevitable. We found that 1-(4-((5-chloro-4-((2-(isopropylsulfonyl)phenyl)amino)pyrimidin-2-yl)amino)-3-methoxyphenyl)-3-(2-(dimethylamino)ethyl)imidazolidin-2-one (ZX-42), a novel ceritinib derivative, could inhibit the proliferation of ALK-positive ALCL cells, induce the apoptosis of Karpas299 cells through the mitochondrial pathway in a caspase-dependent manner. In addition, ZX-42 could suppress ALK and downstream pathways including PI3K/Akt, Erk and JAK3/STAT3 and reduce the nuclear translocation of NFκB by inhibiting TRAF2/IKK/IκB pathway. Taken together, our findings indicate that ZX-42 shows more effective activity than ceritinib against ALK-positive ALCL. We hope this study can provide a direction for the structural modification of ceritinib and lay the foundation for the further development of clinical research in ALK-positive ALCL.

SH003 and Docetaxel Show Synergistic Anticancer Effects by Inhibiting EGFR Activation in Triple-Negative Breast Cancer

Although many anticancer drugs have been developed for triple-negative breast cancer (TNBC) treatment, there are no obvious therapies. Moreover, the combination of epidermal growth factor receptor- (EGFR-) targeted therapeutics and classical chemotherapeutic drugs has been assessed in clinical trials for TNBC treatment, but those are not yet approved. Our serial studies for newly developed herbal medicine named SH003 provide evidence of its broad effectiveness in various cancers, especially on TNBC. The current study demonstrates a synergic effect of combinatorial treatment of SH003 and docetaxel (DTX) by targeting EGFR activation. The combinatorial treatment reduced the viability of both BT-20 and MDA-MB-231 TNBC cells, displaying the synergism. The combination of SH003 and DTX also caused the synergistic effect on apoptosis. Mechanistically, the cotreatment of SH003 and DTX inhibited phosphorylation of EGFR and AKT in both BT-20 and MDA-MB-231 cells. Moreover, our xenograft mouse tumor growth assays showed the inhibitory effect of the combinatorial treatment with no effect on body weight. Our immunohistochemistry confirmed its inhibition of EGFR phosphorylation in vivo. Collectively, combinatorial treatment of SH003 and DTX has a synergistic anticancer effect at a relatively low concentration by targeting EGFR in TNBC, indicating safety and efficacy of SH003 as adjuvant combination therapy with docetaxel. Thus, it is worth testing the combinatorial effect in clinics for treating TNBC.

The epithelial sodium channel has a role in breast cancer cell proliferation

PURPOSE

Breast cancer is the most common cancer affecting women worldwide with half a million associated deaths annually. Despite a huge global effort, the pathways of breast cancer progression are not fully elucidated. Ion channels have recently emerged as novel regulators of cancer cell proliferation and metastasis. The epithelial sodium channel, ENaC, made up of α, β and γ subunits is well known for its role in Na⁺ reabsorption in epithelia, but a number of novel roles for ENaC have been described, including potential roles in cancer. A role for ENaC in breast cancer, however, has yet to be described. Therefore, the effects of ENaC level and activity on breast cancer proliferation were investigated.

METHODS

Through the publicly available SCAN-B dataset associations between αENaC mRNA expression and breast cancer subtypes, proliferation markers and epithelial-mesenchymal transition markers (EMT) were assessed. αENaC expression, through overexpression or siRNA-mediated knockdown, and activity, through the ENaC-specific inhibitor amiloride, were altered in MCF7, T47D, BT549, and MDAMB231 breast cancer cells. MTT and EdU cell proliferation assays were used to determine the effect of these manipulations on breast cancer cell proliferation.

RESULTS

High αENaC mRNA expression was associated with less aggressive and less proliferative breast cancer subtypes and with reduced expression of proliferation markers. Decreased αENaC expression or activity, in the mesenchymal breast cancer cell lines BT549 and MDAMB231, increased breast cancer cell proliferation. Conversely, increased αENaC expression decreased breast cancer cell proliferation.

CONCLUSION

αENaC expression is associated with a poor prognosis in breast cancer and is a novel regulator of breast cancer cell proliferation. Taken together, these results identify ENaC as a potential future therapeutic target.

Pre-existing Cell States Control Heterogeneity of Both EGFR and CXCR4 Signaling

INTRODUCTION

CXCR4 and epidermal growth factor receptor (EGFR) represent two major families of receptors, G-protein coupled receptors and receptor tyrosine kinases, with central functions in cancer. While utilizing different upstream signaling molecules, both CXCR4 and EGFR activate kinases ERK and Akt, although single-cell activation of these kinases is markedly heterogeneous. One hypothesis regarding the origin of signaling heterogeneity proposes that intercellular variations arise from differences in pre-existing intracellular states set by extrinsic noise. While pre-existing cell states vary among cells, each pre-existing state defines deterministic signaling outputs to downstream effectors. Understanding causes of signaling heterogeneity will inform treatment of cancers with drugs targeting drivers of oncogenic signaling.

METHODS

We built a single-cell computational model to predict Akt and ERK responses to CXCR4- and EGFR-mediated stimulation. We investigated signaling heterogeneity through these receptors and tested model predictions using quantitative, live-cell time-lapse imaging.

RESULTS

We show that the pre-existing cell state predicts single-cell signaling through both CXCR4 and EGFR. Computational modeling reveals that the same set of pre-existing cell states explains signaling heterogeneity through both EGFR and CXCR4 at multiple doses of ligands and in two different breast cancer cell lines. The model also predicts how phosphatidylinositol-3-kinase (PI3K) targeted therapies potentiate ERK signaling in certain breast cancer cells and that low level, combined inhibition of MEK and PI3K ablates potentiated ERK signaling.

CONCLUSIONS

Our data demonstrate that a conserved motif exists for EGFR and CXCR4 signaling and suggest potential clinical utility of the computational model to optimize therapy.

Mild hypothermia protects rat cortical neurons against oxygen-glucose deprivation/reoxygenation injury via the PI3K/Akt pathway

Ischemic stroke is the most frequent cause of long-term morbidity and mortality in the elderly worldwide. Mild hypothermia (32-35°C) has been found to have a neuroprotective effect against ischemic stroke. However, the protective mechanisms remain unclear. In the present study, we explore the neuroprotective effect of mild hypothermia in neuron-astrocyte cocultures by oxygen-glucose deprivation/reoxygenation (OGD/R) as well as the underlying mechanisms. Thionin staining was performed and cell viability, extracellular glutamate concentration and the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) pathway-related proteins were detected after OGD/R. The results indicated that mild hypothermia significantly alleviated damage to Nissl bodies and increased the viability of neurons, which alleviated OGD/R-triggered neuronal injury. Furthermore, mild hypothermia significantly enhanced the phosphorylation of Akt (pAkt) and glutamate transporter-1 (GLT-1) and reduced extracellular glutamate concentration after OGD/R. When the PI3K inhibitor LY294002 was added, neuronal viability and the expression of pAkt and GLT-1 decreased, and extracellular glutamate concentration increased. The protective effect of mild hypothermia was counteracted by LY294002. There was no significant change in neuronal viability or the expression of pAkt and GLT-1 in the group treated with dihydrokainate, an inhibitor of GLT-1-function, compared with the mild hypothermia + OGD/R (HOGD) group, but extracellular glutamate concentration was increased. Consequently, mild hypothermia promoted glutamate clearance by regulating GLT-1 expression via the PI3K/Akt pathway, providing a neuroprotective effect against OGD/R injury.

Ginsenoside Rb1 exerts antidepressant-like effects via suppression inflammation and activation of AKT pathway

Depression-like behaviors caused by chronic stress are related to inflammation and microglia activation. Antidepressant therapy may contribute to inhibiting inflammation responses and microglia activation. Ginsenoside Rb1 (GRb1) is known to display antidepressant-like effect on chronic unpredictable mild stress-induced depressive rats. However, the antidepressant-like effects of GRb1 on chronic restraint stress (CRS) mice and the potential anti-inflammatory mechanisms are unclear. Here, we focused on the molecular mechanisms related to inhibition of inflammation response and the protection on microglia. Our results showed that GRb1 had an antidepressant effects via relieving the depression-like behaviors in CRS model. Furthermore, GRb1 increased the protein expressions of brain-derived neurotrophic factor and phospho- protein kinase B/ protein kinase B (p-AKT/AKT), and decreased the protein expressions of interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α) and ionized calcium binding adapter molecule 1 in hippocampus, reduced the levels IL-1β and TNF-α in serum. Finally, GRb1 lowered the protein expressions of IL-1β and TNF-α in BV-2 microglia induced by lipopolysaccharides. Taken together, the results indicate that GRb1 prevents CRS-induced depression-like behaviors in mice, which may be related to anti-inflammatory effects in hippocampus, serum and microglia and activation of AKT pathway.

Comprehensive Proteomic Characterization Reveals Subclass-Specific Molecular Aberrations within Triple-negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer lacking targeted therapies. This is attributed to its high heterogeneity that complicates elucidation of its molecular aberrations. Here, we report identification of specific proteome expression profiles pertaining to two TNBC subclasses, basal A and basal B, through in-depth proteomics analysis of breast cancer cells. We observed that kinases and proteases displayed unique expression patterns within the subclasses. Systematic analyses of protein-protein interaction and co-regulation networks of these kinases and proteases unraveled dysregulated pathways and plausible targets for each TNBC subclass. Among these, we identified kinases AXL, PEAK1, and TGFBR2 and proteases FAP, UCHL1, and MMP2/14 as specific targets for basal B subclass, which represents the more aggressive TNBC cell lines. Our study highlights intricate mechanisms and distinct targets within TNBC and emphasizes that these have to be exploited in a subclass-specific manner rather than a one-for-all TNBC therapy.

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Proteome profiling reveals functionally distinct subclasses within TNBC

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Kinases and proteases underlie unique functional signatures among the subclasses

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Kinase-protease-centric networks highlight subclass-specific molecular rewiring

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Protein association dysregulations reveal TNBC subclass-specific protein targets

Taiwanin E Induces Cell Cycle Arrest and Apoptosis in Arecoline/4-NQO-Induced Oral Cancer Cells Through Modulation of the ERK Signaling Pathway

Taiwanin E is a bioactive compound extracted from Taiwania cryptomerioides Hayata. In this research endeavor, we studied the anti-cancer effect of Taiwanin E against arecoline and 4-nitroquinoline-1-oxide-induced oral squamous cancer cells (OSCC), and elucidated the underlying intricacies. OSCC were treated with Taiwanin E and analyzed through MTT assay, Flow cytometry, TUNEL assay, and Western blotting for their efficacy against OSCC. Interestingly, it was found that Taiwanin E significantly attenuated the cell viability of oral cancer cells (T28); however, no significant cytotoxic effects were found for normal oral cells (N28). Further, Flow cytometry analysis showed that Taiwanin E induced G1cell cycle arrest in T28 oral cancer cells and Western blot analysis suggested that Taiwanin E considerably downregulated cell cycle regulatory proteins and activated p53, p21, and p27 proteins. Further, TUNEL and Western blot studies instigated that it induced cellular apoptosis and attenuated the p-PI3K/p-Akt survival mechanism in T28 oral cancer cells seemingly through modulation of the ERK signaling cascade. Collectively, the present study highlights the prospective therapeutic efficacy of Taiwanin E against arecoline and 4-nitroquinoline-1-oxide-induced oral cancer.

Aurantoside C Targets and Induces Apoptosis in Triple Negative Breast Cancer Cells

Triple negative breast cancer (TNBC) is a subtype of breast cancers that currently lacks effective targeted therapy. In this study, we found that aurantoside C (C828), isolated from the marine sponge Manihinealynbeazleyae collected from Western Australia, exhibited higher cytotoxic activities in TNBC cells compared with non-TNBC (luminal and normal-like) cells. The cytotoxic effect of C828 was associated to the accumulation of cell at S-phase, resulting in the decline of cyclin D1, cyclin E1, CDK4, and CDK6, and an increase in p21. We also found that C828 inhibited the phosphorylation of Akt/mTOR and NF-kB pathways and increased the phosphorylation of p38 MAPK and SAPK/JNK pathways, leading to apoptosis in TNBC cells. These effects of C828 were not observed in non-TNBC cells at the concentrations that were cytotoxic to TNBC cells. When compared to the cytotoxic effect with the chemotherapeutic drugs doxorubicin and cisplatin, C828 was found to be 20 times and 35 times more potent than doxorubicin and cisplatin, respectively. These results indicate that C828 could be a promising lead for developing new anticancer agents that target TNBC cells.

Effects of Ginsenoside Rb1 on Expressions of Phosphorylation Akt/Phosphorylation mTOR/Phosphorylation PTEN in Artificial Abnormal Hippocampal Microenvironment in Rats

Artificial abnormal microenvironment caused by microperfusion of L-glutamate (Glu) and Ca²⁺ in the hippocampus results in neuron damage, which is closely related to cerebral ischemia. Ginsenoside Rb1, a compound from Panax notoginseng, was previously used to counter the artificial abnormal hippocampal environment in a microperfusion model. In addition, while the Akt/mTOR/PTEN signaling pathway has been shown to mediate neuronprotection in cerebral ischemia, whether this pathway is involved in the neuroprotection of ginsenoside Rb1 is unknown. Here SH-SY5Y cells exposed to OGD/R injury in treated with LY294002, ginsenoside Rb1, ginsenoside Rb1+ LY294002. Expressions of phosphorylation (P-)Akt/P-mTOR/P-PTEN (24 h after OGD/R) were detected by Western blotting. Effects were examined via the memory function of rats (by Morris water maze test), morphological changes in pyramidal cell (by histology), and mRNA expression (by qRT-PCR) and phosphorylation (P-) (by Western blotting and immunohistochemical staining) of Akt, P-mTOR, and P-PTEN in the hippocampus. The memory deficit of rats and pyramidal cellular necrosis and apoptosis in the CA1 region of hippocampus after microperfusion of Glu and Ca²⁺ were dose dependently alleviated by ginsenoside Rb1.Moreover,Western blot showed that ginsenoside Rb1 increased the expressions of P-Akt, P-mTOR and reduced P-PTEN in vivo and vitro. Thus, the potent neuroprotection of ginsenoside Rb1 in artificial abnormal microenvironment is, at least partially, related to the activation of P-AKT/P-mTOR signaling pathway and inhibition of P-PTEN protein.

Effects of PHA-665752 and vemurafenib combination treatment on in vitro and murine xenograft growth of human colorectal cancer cells with BRAFV600E mutations

It remains unknown whether blockade of B-Raf proto-oncogene, serine/threonine kinase (BRAF)^V600E signaling and MET proto-oncogene, receptor tyrosine kinase (c-Met) signaling is effective in suppressing the growth of human colorectal cancer (CRC) cells. The present study investigated the effects of the vemurafenib alone and in combination with c-Met inhibitor PHA-665752 on the growth of human CRC cells in vitro and in mouse xenografts. HT-29 and RKO CRC cell lines with BRAF^V600E mutations and mice bearing HT-29 xenografts were treated with vemurafenib in the absence or presence of PHA-665752. Cell viability and cycle phase were respectively examined by using the MTT and flow cytometry assay. Immunohistochemistry was conducted to detect the protein expression levels of hepatocyte growth factor (HGF), phosphorylated (p)-c-Met, p-AKT serine/threonine kinase (AKT) and p-extracellular signal-regulated kinase (p-ERK). The MTT assay demonstrated that the growth of RKO and HT-29 cells was inhibited by PHA-665752 in a time- and dose-dependent manner (P<0.05), however no significant suppressive effects were observed with vemurafenib. Relative to the PHA-665752 or vemurafenib stand-alone treatment groups, the combination of PHA-665752 and vemurafenib had a significant inhibitory effect on the proliferation of CRC cell lines (P<0.05). The mean tumor volume in mice treated with vemurafenib in combination with PHA-665752 was significantly smaller compared with those treated with only vemurafenib or PHA-665752 (P<0.05). Flow cytometry assay revealed that the G0/G1 phase frequency was significantly increased in the combination group compared with any other treatment groups (P<0.05). Immunohistochemistry demonstrated that vemurafenib in combination with PHA-665752 effectively induced the expression of p-c-Met, p-AKT and p-ERK, however had no effect on HGF.

Combination therapy with telmisartan and parecoxib induces regression of endometriotic lesions

BACKGROUND AND PURPOSE

Telmisartan suppresses the development of endometriotic lesions. However, the drug also up-regulates the expression of COX-2, which has been suggested to promote the progression of endometriosis. Accordingly, in the present study we analysed whether a combination therapy with telmisartan and a COX-2 inhibitor may be more effective in the treatment of endometriotic lesions than the application of telmisartan alone.

EXPERIMENTAL APPROACH

Endometriotic lesions were induced in the peritoneal cavity of C57BL/6 mice, which were treated daily with an i.p. injection of telmisartan (10 mg·kg^-1 ), parecoxib (5 mg·kg^-1 ), a combination of telmisartan and parecoxib or vehicle. Therapeutic effects on lesion survival, growth, vascularization, innervation and protein expression were studied over 4 weeks by high-resolution ultrasound imaging as well as immunohistochemical and Western blot analyses.

KEY RESULTS

Telmisartan-treated lesions exhibited a significantly reduced lesion volume when compared with vehicle-treated controls and parecoxib-treated lesions. This inhibitory effect of telmisartan was even more pronounced when it was used in combination with parecoxib. The combination therapy resulted in a reduced microvessel density as well as lower numbers of proliferating Ki67-positive cells and higher numbers of apoptotic cleaved caspase-3-positive stromal cells within the lesions. This was associated with a lower expression of COX-2, MMP-9 and p-Akt/Akt when compared with controls. The application of the two drugs further inhibited the ingrowth of nerve fibres into the lesions.

CONCLUSIONS AND IMPLICATIONS

Combination therapy with telmisartan and a COX-2 inhibitor represents a novel, effective pharmacological strategy for the treatment of endometriosis.