Systematic Drug Screening Identifies Tractable Targeted Combination Therapies in Triple-Negative Breast Cancer

Combination of monensin and erlotinib synergistically inhibited the growth and cancer stem cell properties of triple-negative breast cancer by simultaneously inhibiting EGFR and PI3K signaling pathways

BACKGROUND

Cancer stem cells (CSCs) in triple-negative breast cancer (TNBC) are recognized as a highly challenging subset of cells, renowned for their heightened propensity for relapse and unfavorable prognosis. Monensin, an ionophoric antibiotic, has been reported to exhibit significant therapeutic efficacy against various cancers, especially CSCs. Erlotinib is classified as one of the EGFR-TKIs and has been previously identified as a promising therapeutic target for TNBC. Our research aims to assess the effectiveness of combination of monensin and erlotinib as a potential treatment strategy for TNBC.

METHODS

The combination of monensin and erlotinib was assessed for its potential anticancer activity through various in vitro assays, including cytotoxicity assay, colony formation assay, wound healing assay, transwell assay, mammosphere formation assay, and proportion of CSCs assay. Additionally, an in vivo study using tumor-bearing nude mice was conducted to evaluate the inhibitory effect of the monensin and erlotinib combination on tumor growth.

RESULTS

The results indicated that combination of monensin with erlotinib synergistically inhibited cell proliferation, the migration rate, the invasion ability and decreased the CSCs proportion, and CSC markers SOX2 and CD133 in vivo and in vitro. Furthermore, the primary proteins involved in the signaling pathways of the EGFR/ERK and PI3K/AKT are simultaneously inhibited by the combination treatment of monensin and erlotinib in vivo and in vitro.

CONCLUSIONS

The simultaneous inhibition of the EGFR/ERK and PI3K/AKT/mTOR signaling pathways by the combination of monensin and erlotinib exhibited a synergistic effect on suppressing tumor proliferation and cancer cell stemness in TNBC.

Discovery of novel small molecules targeting the USP21/JAK2/STAT3 axis for the treatment of triple-negative breast cancer

The deficiency in available targeted agents and frequency of chemoresistance are primary challenges in clinical management of triple-negative breast cancer (TNBC). The aberrant expression of USP21 and JAK2 represents a characterized mechanism of TNBC progression and resistance to paclitaxel (PTX). Despite its clear that high expression of USP21-mediated de-ubiquitination leads to increased levels of JAK2 protein, we lack regulator molecules to dissect the mechanisms that the interaction between USP21 and JAK2 contributes to the phenotype and resistance of TNBC. Here, we report a USP21/JAK2/STAT3 axis-targeting regulator 13c featuring a N-anthraniloyl tryptamine scaffold that showed excellent anti-TNBC potency and promising safety profile. Importantly, the therapeutic potential of using 13c in combination with PTX in PTX-resistant TNBC was demonstrated. This study showcases N-anthraniloyl tryptamine derivatives as a novel anti-TNBC chemotype with a pharmacological mode of action targeting the USP21/JAK2/STAT3 axis and provides a potential therapeutic target for the treatment of TNBC.

Efficacy of Cold Atmospheric Plasma vs. Chemotherapy in Triple-Negative Breast Cancer: A Systematic Review

Breast cancer is a growing disease, with a high worldwide incidence and mortality rate among women. Among the various types, the treatment of triple-negative breast cancer (TNBC) remains a challenge. Considering the recent advances in cold atmospheric plasma (CAP) cancer research, our goal was to evaluate efficacy data from studies based on chemotherapy and CAP in TNBC cell lines and animal models. A search of the literature was carried out in the PubMed, Web of Science, Cochrane Library, and Embase databases. Of the 10,999 studies, there were fifty-four in vitro studies, three in vivo studies, and two in vitro and in vivo studies included. MDA-MB-231 cells were the most used. MTT, MTS, SRB, annexin-V/propidium iodide, trypan blue, and clonogenic assay were performed to assess efficacy in vitro, increasing the reliability and comprehensiveness of the data. There was found to be a decrease in cell proliferation after both chemotherapy and CAP; however, different protocol settings, including an extensive range of drug doses and CAP exposure times, were reported. For both therapies, a considerable reduction in tumor volume was observed in vivo compared with that of the untreated group. The treatment of TNBC cell lines with CAP proved successful, with apoptosis emerging as the predominant type of cellular death. This systematic review presents a comprehensive overview of the treatment landscape in chemotherapy and CAP regarding their efficacy in TNBC cell lines.

Challenges and Opportunities in Developing Targeted Therapies for Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is a heterogeneous group of breast cancers characterized by their lack of estrogen receptors, progesterone receptors, and the HER2 receptor. They are more aggressive than other breast cancer subtypes, with a higher mean tumor size, higher tumor grade, the worst five-year overall survival, and the highest rates of recurrence and metastasis. Developing targeted therapies for TNBC has been a major challenge due to its heterogeneity, and its treatment still largely relies on surgery, radiation therapy, and chemotherapy. In this review article, we review the efforts in developing targeted therapies for TNBC, discuss insights gained from these efforts, and highlight potential opportunities going forward. Accumulating evidence supports TNBCs as multi-driver cancers, in which multiple oncogenic drivers promote cell proliferation and survival. In such multi-driver cancers, targeted therapies would require drug combinations that simultaneously block multiple oncogenic drivers. A strategy designed to generate mechanism-based combination targeted therapies for TNBC is discussed.

Targeting Senescence as a Therapeutic Opportunity for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is associated with an elevated risk of recurrence and poor prognosis. Historically, only chemotherapy was available as systemic treatment, but immunotherapy and targeted therapies currently offer prolonged benefits. TNBC is a group of diseases with heterogeneous treatment sensitivity, and resistance is inevitable and early for a large proportion of the intrinsic subtypes. Although senescence induction by anticancer therapy offers an immediate favorable clinical outcome once the rate of tumor progression reduces, these cells are commonly dysfunctional and metabolically active, culminating in treatment-resistant repopulation associated with worse prognosis. This heterogeneous response can also occur without therapeutic pressure in response to damage or oncogenic stress, playing a relevant role in the carcinogenesis. Remarkably, there is preclinical and exploratory clinical evidence to support a relevant role of senescence in treatment resistance. Therefore, targeting senescent cells has been a scientific effort in many malignant tumors using a variety of targets and strategies, including increasing proapoptotic and decreasing antiapoptotic stimuli. Despite promising results, there are some challenges to applying this technology, including the best schedule of combination, assessment of senescence, specific vulnerabilities, and the best clinical scenarios. This review provides an overview of senescence in TNBC with a focus on future-proofing senotherapy strategies.

Effective combination treatments for breast cancer inhibition by FOXM1 inhibitors with other targeted cancer drugs

PURPOSE

Few targeted treatment options currently exist for patients with advanced, often recurrent breast cancers, both triple-negative breast cancer (TNBC) and hormone receptor-positive breast cancer. Forkhead box M1 (FOXM1) is an oncogenic transcription factor that drives all cancer hallmarks in all subtypes of breast cancer. We previously developed small-molecule inhibitors of FOXM1 and to further exploit their potential as anti-proliferative agents, we investigated combining FOXM1 inhibitors with drugs currently used in the treatment of breast and other cancers and assessed the potential for enhanced inhibition of breast cancer.

METHODS

FOXM1 inhibitors alone and in combination with other cancer therapy drugs were assessed for their effects on suppression of cell viability and cell cycle progression, induction of apoptosis and caspase 3/7 activity, and changes in related gene expressions. Synergistic, additive, or antagonistic interactions were evaluated using ZIP (zero interaction potency) synergy scores and the Chou-Talalay interaction combination index.

RESULTS

The FOXM1 inhibitors displayed synergistic inhibition of proliferation, enhanced G2/M cell cycle arrest, and increased apoptosis and caspase 3/7 activity and associated changes in gene expression when combined with several drugs across different pharmacological classes. We found especially strong enhanced effectiveness of FOXM1 inhibitors in combination with drugs in the proteasome inhibitor class for ER-positive and TNBC cells and with CDK4/6 inhibitors (Palbociclib, Abemaciclib, and Ribociclib) in ER-positive cells.

CONCLUSION

The findings suggest that the combination of FOXM1 inhibitors with several other drugs might enable dose reduction in both agents and provide enhanced efficacy in treatment of breast cancer.

Modification of Breast Cancer Milieu with Chemotherapy plus Dendritic Cell Vaccine: An Approach to Select Best Therapeutic Strategies

BACKGROUND

The addition of dendritic cell vaccines (DCV) to NAC could induce immune responses in those patients with residual disease (RD) by transforming the tumor microenvironment.

METHODS

Core diagnostic biopsies and surgical specimens from 80 patients (38 in the vaccinated group plus NAC (VG) and 42 in the control group (CG, treated only with NAC) were selected. We quantify TILs (CD8, CD4 and CD45RO) using immunohistochemistry and the automated cellular imaging system (ACIS III) in paired samples.

RESULTS

A CD8 rise in TNBC samples was observed after NAC plus DCV, changing from 4.48% in the biopsy to 6.70% in the surgical specimen, not reaching statistically significant differences (p = 0.11). This enrichment was seen in up to 67% of TNBC patients in the experimental arm as compared with the CG (20%). An association between CD8 TILs before NAC (4% cut-off point) and pathological complete response in the VG was found in the univariate and multivariate analysis (OR = 1.41, IC95% 1.05-1.90; p = 0.02, and OR = 2.0, IC95% 1.05-3.9; p = 0.03, respectively).

CONCLUSION

Our findings suggest that patients with TNBC could benefit from the stimulation of the antitumor immune system by using DCV together with NAC.

Role of p53 in breast cancer progression: An insight into p53 targeted therapy

The transcription factor p53 is an important regulator of a multitude of cellular processes. In the presence of genotoxic stress, p53 is activated to facilitate DNA repair, cell cycle arrest, and apoptosis. In breast cancer, the tumor suppressive activities of p53 are frequently inactivated by either the overexpression of its negative regulator MDM2, or mutation which is present in 30-35% of all breast cancer cases. Notably, the frequency of p53 mutation is highly subtype dependent in breast cancers, with majority of hormone receptor-positive or luminal subtypes retaining the wild-type p53 status while hormone receptor-negative patients predominantly carry p53 mutations with gain-of-function oncogenic activities that contribute to poorer prognosis. Thus, a two-pronged strategy of targeting wild-type and mutant p53 in different subtypes of breast cancer can have clinical relevance. The development of p53-based therapies has rapidly progressed in recent years, and include unique small molecule chemical inhibitors, stapled peptides, PROTACs, as well as several genetic-based approaches using vectors and engineered antibodies. In this review, we highlight the therapeutic strategies that are in pre-clinical and clinical development to overcome p53 inactivation in both wild-type and mutant p53-bearing breast tumors, and discuss their efficacies and limitations in pre-clinical and clinical settings.

Synergistic PIM kinase and proteasome inhibition as a therapeutic strategy for MYC-overexpressing triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the breast cancer subtype with the poorest clinical outcome. The PIM family of kinases has emerged as a factor that is both overexpressed in TNBC and associated with poor outcomes. Preclinical data suggest that TNBC with an elevated MYC expression is sensitive to PIM inhibition. However, clinical observations indicate that the efficacy of PIM inhibitors as single agents may be limited, suggesting the need for combination therapies. Our screening effort identifies PIM and the 20S proteasome inhibition as the most synergistic combination. PIM inhibitors, when combined with proteasome inhibitors, induce significant antitumor effects, including abnormal accumulation of poly-ubiquitinated proteins, increased proteotoxic stress, and the inability of NRF1 to counter loss in proteasome activity. Thus, the identified combination could represent a rational combination therapy against MYC-overexpressing TNBC that is readily translatable to clinical investigations.

DSTYK Enhances Chemoresistance in Triple-Negative Breast Cancer Cells

Breast cancer, as the most prevalent cancer in women, is responsible for more than 15% of new cancer cases and about 6.9% of all cancer-related death in the US. A major cause of therapeutic failure in breast cancer is the development of resistance to chemotherapy, especially for triple-negative breast cancer (TNBC). Therefore, how to overcome chemoresistance is the major challenge to improve the life expectancy of breast cancer patients. Our studies demonstrate that TNBC cells surviving the chronic treatment of chemotherapeutic drugs show significantly higher expression of the dual serine/threonine and tyrosine protein kinase (DSTYK) than non-treated parental cells. In our in vitro cellular models, DSTYK knockout via the CRISPR/Cas9-mediated technique results in apoptotic cell death of chemoresistant cells upon drug treatment. Moreover, DSTYK knockout promotes chemotherapeutic drug-induced tumor cell death in an orthotopic mouse model. These findings suggest that DSTYK exerts an important and previously unknown role in promoting chemoresistance. Our studies provide fundamental insight into the role of DSTYK in chemoresistance in TNBC cells and lay the foundation for the development of new strategies targeting DSTYK for improving TNBC therapy.

Identification of nuclear export inhibitor-based combination therapies in preclinical models of triple-negative breast cancer

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High-throughput drug screening reveals promising therapeutic candidates for TNBC.

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KPT-330, an XPO1 inhibitor, and GSK2126458 exhibit synergism in preclinical models of TNBC.

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XPO1 is overexpressed in basal-like breast tumors.

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XPO1 expression is associated with PIK3CA, MTOR, and MKI67 expression at the single-cell level.

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XPO1 overexpression in basal-like patients is associated with greater rates of metastases.

An estimated 284,000 Americans will be diagnosed with breast cancer in 2021. Of these individuals, 15–20% have basal-like triple-negative breast cancer (TNBC), which is known to be highly metastatic. Chemotherapy is standard of care for TNBC patients, but chemoresistance is a common clinical problem. There is currently a lack of alternative, targeted treatment strategies for TNBC; this study sought to identify novel therapeutic combinations to treat basal-like TNBCs. For these studies, four human basal-like TNBC cell lines were utilized to determine the cytotoxicity profile of 1363 clinically-used drugs. Ten promising therapeutic candidates were identified, and synergism studies were performed in vitro. Two drug combinations that included KPT-330, an XPO1 inhibitor, were synergistic in all four cell lines. In vivo testing of four basal-like patient-derived xenografts (PDX) identified one combination, KPT-330 and GSK2126458 (a PI3K/mTOR inhibitor), that decreased tumor burden in mice significantly more than monotherapy with either single agent. Bulk and single-cell RNA-sequencing, immunohistochemistry, and analysis of published genomic datasets found that XPO1 was abundantly expressed in human basal-like TNBC cell lines, PDXs, and patient tumor samples. Within basal-like PDXs, XPO1 overexpression was associated with increased proliferation at the cellular level. Within patient datasets, XPO1 overexpression was correlated with greater rates of metastasis in patients with basal-like tumors. These studies identify a promising potential new combination therapy for patients with basal-like breast cancer.

In vitro Evaluation of Isatin derivatives as Potent Anti-Breast Cancer Agents against MCF-7, MDA MB 231, MDA-MB 435 and MDA-MB 468 Breast Cancers cell lines: A Review

INTRODUCTION

Breast cancer (BC) is one of the most frequent malignancy and most common reasons of impermanence in women. The backbone of therapy for BC is principally chemotherapy, but due to its non-specific nature between normal cells and cancer cells and severe side effects are the main barriers in its therapy. So, there is an intense requirement for the enlargement of more efficacious, more specific and safer anti-BC agents.

OBJECTIVE

Isatin (IST) is an endogenous molecule which is a principal class of heterocyclic compounds and exhibits a wide range of therapeutic activities which can be used as a starting material for the synthesis of several drug molecules. Many literatures were reported previously on different pharmacological activities of IST derivatives and particularly on anticancer activity but this review mainly focus on anti-BC activities of IST derivatives through MCF-7, MDA MB 231, MDA-MB 435 and MDA-MB 468 cell lines. Here in we mentioned, a total 33 IST derivatives (compound 24- 56) which shown good anti-BC activity. IST derived compounds are also available in market and are used for various cancer types like sunitinib for renal cell carcinoma (RCC) and Nintedanib used for the cryptogenic fibrosing alveolitis treatment but when evaluated for BC did not get much success.

CONCLUSION

This review mainly highlights anti-BC activities of various IST analogues using MCF-7, MDA MB 231, MDA-MB 435 and MDA-MB 468 cell lines, display the potent compound of the series and structure-activity relationships of compounds with molecular docking also. So, this study mainly shows the importance of IST as major sources for drug design and development of newer anti-BC drugs.

Investigational Drug Treatments for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer (BC) and accounts for 10–20% of cases. Due to the lack of expression of several receptors, hormone therapy is largely ineffective for treatment purposes. Nevertheless, TNBC often responds very well to chemotherapy, which constitutes the most often recommended treatment. New beneficial targeted therapies are important to be investigated in order to achieve enhanced outcomes in patients with TNBC. This review will focus on recent therapeutic innovations for TNBC, focusing on various inhibitors such as phosphoinositide 3-kinase (PI3K) pathway inhibitors, poly-ADP-ribosyl polymerase (PARP) inhibitors, aurora kinase inhibitors, histone deacetylase inhibitors (HDACIs), and immune checkpoint inhibitors.

Treatment scheduling effects on the evolution of drug resistance in heterogeneous cancer cell populations

The effect of scheduling of targeted therapy combinations on drug resistance is underexplored in triple-negative breast cancer (TNBC). TNBC constitutes heterogeneous cancer cell populations the composition of which can change dynamically during treatment resulting in the selection of resistant clones with a fitness advantage. We evaluated crizotinib (ALK/MET inhibitor) and navitoclax (ABT-263; Bcl-2/Bcl-xL inhibitor) combinations in a large design consisting of 696 two-cycle sequential and concomitant treatment regimens with varying treatment dose, duration, and drug holiday length over a 26-day period in MDA-MB-231 TNBC cells and found that patterns of resistance depend on the schedule and sequence in which the drugs are given. Further, we tracked the clonal dynamics and mechanisms of resistance using DNA-integrated barcodes and single-cell RNA sequencing. Our study suggests that longer formats of treatment schedules in vitro screening assays are required to understand the effects of resistance and guide more realistically in vivo and clinical studies.

SYNERGxDB: an integrative pharmacogenomic portal to identify synergistic drug combinations for precision oncology

Drug-combination data portals have recently been introduced to mine huge amounts of pharmacological data with the aim of improving current chemotherapy strategies. However, these portals have only been investigated for isolated datasets, and molecular profiles of cancer cell lines are lacking. Here we developed a cloud-based pharmacogenomics portal called SYNERGxDB (http://SYNERGxDB.ca/) that integrates multiple high-throughput drug-combination studies with molecular and pharmacological profiles of a large panel of cancer cell lines. This portal enables the identification of synergistic drug combinations through harmonization and unified computational analysis. We integrated nine of the largest drug combination datasets from both academic groups and pharmaceutical companies, resulting in 22 507 unique drug combinations (1977 unique compounds) screened against 151 cancer cell lines. This data compendium includes metabolomics, gene expression, copy number and mutation profiles of the cancer cell lines. In addition, SYNERGxDB provides analytical tools to discover effective therapeutic combinations and predictive biomarkers across cancer, including specific types. Combining molecular and pharmacological profiles, we systematically explored the large space of univariate predictors of drug synergism. SYNERGxDB constitutes a comprehensive resource that opens new avenues of research for exploring the mechanism of action for drug synergy with the potential of identifying new treatment strategies for cancer patients.

Bufalin attenuates triple-negative breast cancer cell stemness by inhibiting the expression of SOX2/OCT4

Triple-negative breast cancer (TNBC) has the poorest prognosis among all types of breast cancer and there is yet no effective therapy. Chemotherapy is the traditional standard of care for patients with TNBC; however, treatment of TNBC with chemotherapy may lead to the enrichment of cancer stem cells (CSCs), which exhibitan enhanced capacity for self-renewal, tumor initiation and metastasis. The present study demonstrated that bufalin, a small molecular compound used in traditional Chinese medicine, exerted anticancer effects on a wide range of cancer cell lines, inhibited cell proliferation through inducing G2/M cell cycle arrest, and triggered apoptosis in the TNBC cell lines MDA-MB-231 and HCC-1937. Consistently, bufalin markedly suppressed TNBC growth in a cell line-derived xenograft model. More importantly, unlike common chemotherapeutic drugs, bufalin reduced the stemness of TNBC stem cells. A mechanistic study suggested that bufalin may suppress the proliferation of TNBC stem cells by inhibiting the expression of octamer-binding transcription factor 4 (OCT4) and sex determining region Y-box 2 (SOX2) in MDA-MB-231 and HCC-1937 cells. These results indicated that bufalin may hold promise as a therapeutic agent in TNBC, and its effects may be mediated through the SOX2/OCT4 axis.

Multi-Omics Investigation of Innate Navitoclax Resistance in Triple-Negative Breast Cancer Cells

Cancer cells employ various defense mechanisms against drug-induced cell death. Investigating multi-omics landscapes of cancer cells before and after treatment can reveal resistance mechanisms and inform new therapeutic strategies. We assessed the effects of navitoclax, a BCL2 family inhibitor, on the transcriptome, methylome, chromatin structure, and copy number variations of MDA-MB-231 triple-negative breast cancer (TNBC) cells. Cells were sampled before treatment, at 72 h of exposure, and after 10-day drug-free recovery from treatment. We observed transient alterations in the expression of stress response genes that were accompanied by corresponding changes in chromatin accessibility. Most of these changes returned to baseline after the recovery period. We also detected lasting alterations in methylation states and genome structure that suggest permanent changes in cell population composition. Using single-cell analyses, we identified 2350 genes significantly upregulated in navitoclax-resistant cells and derived an 18-gene navitoclax resistance signature. We assessed the navitoclax-response-predictive function of this signature in four additional TNBC cell lines in vitro and in silico in 619 cell lines treated with 251 different drugs. We observed a drug-specific predictive value in both experiments, suggesting that this signature could help guiding clinical biomarker studies involving navitoclax.

Application of Machine Learning Approaches for the Design and Study of Anticancer Drugs

BACKGROUND

Globally the number of cancer patients and deaths are continuing to increase yearly, and cancer has, therefore, become one of the world's highest causes of morbidity and mortality. In recent years, the study of anticancer drugs has become one of the most popular medical topics.

OBJECTIVE

In this review, in order to study the application of machine learning in predicting anticancer drugs activity, some machine learning approaches such as Linear Discriminant Analysis (LDA), Principal components analysis (PCA), Support Vector Machine (SVM), Random forest (RF), k-Nearest Neighbor (kNN), and Naïve Bayes (NB) were selected, and the examples of their applications in anticancer drugs design are listed.

RESULTS

Machine learning contributes a lot to anticancer drugs design and helps researchers by saving time and is cost effective. However, it can only be an assisting tool for drug design.

CONCLUSION

This paper introduces the application of machine learning approaches in anticancer drug design. Many examples of success in identification and prediction in the area of anticancer drugs activity prediction are discussed, and the anticancer drugs research is still in active progress. Moreover, the merits of some web servers related to anticancer drugs are mentioned.

Inhibition of Anti-Apoptotic Bcl-2 Proteins in Preclinical and Clinical Studies: Current Overview in Cancer

The dynamic interplay between pro-death and pro-survival Bcl-2 family proteins is responsible for a cell’s fate. Due to the recognized relevance of this family in cancer progression and response to therapy, different efforts have made in recent years in order to develop small molecules able to target anti-apoptotic proteins such as Bcl-2, Bcl-xL and Mcl-1. The limitations of the first Bcl-2 family targeted drugs, regarding on-target and off-target toxicities, have been overcome with the development of venetoclax (ABT-199), the first BH3 mimetic inhibitor approved by the FDA. The purpose of this review is to discuss the state-of-the-art in the development of drugs targeting Bcl-2 anti-apoptotic proteins and to highlight the potential of their application as single agents or in combination for improving anti-cancer therapy, focusing in particular on solid tumors.

Application of a Biphasic Mathematical Model of Cancer Cell Drug Response for Formulating Potent and Synergistic Targeted Drug Combinations to Triple Negative Breast Cancer Cells

Triple negative breast cancer is a collection of heterogeneous breast cancers that are immunohistochemically negative for estrogen receptor, progesterone receptor, and ErbB2 (due to deletion or lack of amplification). No dominant proliferative driver has been identified for this type of cancer, and effective targeted therapy is lacking. In this study, we hypothesized that triple negative breast cancer cells are multi-driver cancer cells, and evaluated a biphasic mathematical model for identifying potent and synergistic drug combinations for multi-driver cancer cells. The responses of two triple negative breast cancer cell lines, MDA-MB-231 and MDA-MB-468, to a panel of targeted therapy drugs were determined over a broad range of concentrations. The analyses of the drug responses by the biphasic mathematical model revealed that both cell lines were indeed dependent on multiple drivers, and inhibitors of individual drivers caused a biphasic response: a target-specific partial inhibition at low nM concentrations, and an off-target toxicity at μM concentrations. We further demonstrated that combinations of drugs, targeting each driver, cause potent, synergistic, and cell-specific cell killing. Immunoblotting analysis of the effects of the individual drugs and drug combinations on the signaling pathways supports the above conclusion. These results support a multi-driver proliferation hypothesis for these triple negative breast cancer cells, and demonstrate the applicability of the biphasic mathematical model for identifying effective and synergistic targeted drug combinations for triple negative breast cancer cells.

Biphasic Mathematical Model of Cell-Drug Interaction That Separates Target-Specific and Off-Target Inhibition and Suggests Potent Targeted Drug Combinations for Multi-Driver Colorectal Cancer Cells

Quantifying the response of cancer cells to a drug, and understanding the mechanistic basis of the response, are the cornerstones for anti-cancer drug discovery. Classical single target-based IC₅₀ measurements are inadequate at describing cancer cell responses to targeted drugs. In this study, based on an analysis of targeted inhibition of colorectal cancer cell lines, we develop a new biphasic mathematical model that accurately describes the cell–drug response. The model describes the drug response using three kinetic parameters: ratio of target-specific inhibition, F₁, potency of target-specific inhibition, K_d1, and potency of off-target toxicity, K_d2. Determination of these kinetic parameters also provides a mechanistic basis for predicting effective combination targeted therapy for multi-driver cancer cells. The experiments confirmed that a combination of inhibitors, each blocking a driver pathway and having a distinct target-specific effect, resulted in a potent and synergistic blockade of cell viability, improving potency over mono-agent treatment by one to two orders of magnitude. We further demonstrate that mono-driver cancer cells represent a special scenario in which F₁ becomes nearly 100%, and the drug response becomes monophasic. Application of this model to the responses of >400 cell lines to kinase inhibitor dasatinib revealed that the ratio of biphasic versus monophasic responses is about 4:1. This study develops a new mathematical model of quantifying cancer cell response to targeted therapy, and suggests a new framework for developing rational combination targeted therapy for colorectal and other multi-driver cancers.

Identification and Validation of a Novel Biologics Target in Triple Negative Breast Cancer

The goal of this study was to identify a novel target for antibody-drug conjugate (ADC) development in triple negative breast cancer (TNBC), which has limited treatment options, using gene expression datasets and in vitro siRNA/CRISPR and in vivo functional assays. We analyzed 4467 breast cancers and identified GABRP as top expressed gene in TNBC with low expression in most normal tissues. GABRP protein was localized to cell membrane with broad range of receptors/cell (815–53,714) and expressed by nearly half of breast cancers tissues. GABRP gene knockdown inhibited TNBC cell growth and colony formation in vitro and growth of MDA-MB-468 xenografts in nude mice. Commercially available anti-GABRP antibody (5–100 μg/ml) or de novo generated Fabs (20 μg/ml) inhibited TNBC cell growth in vitro. The same antibody conjugated to mertansine (DM1) also showed significant anticancer activity at nanomolar concentrations. Our results indicate that GABRP is a potential novel therapeutic target for ADC development.

CEP55 is a determinant of cell fate during perturbed mitosis in breast cancer

The centrosomal protein, CEP55, is a key regulator of cytokinesis, and its overexpression is linked to genomic instability, a hallmark of cancer. However, the mechanism by which it mediates genomic instability remains elusive. Here, we showed that CEP55 overexpression/knockdown impacts survival of aneuploid cells. Loss of CEP55 sensitizes breast cancer cells to anti‐mitotic agents through premature CDK1/cyclin B activation and CDK1 caspase‐dependent mitotic cell death. Further, we showed that CEP55 is a downstream effector of the MEK1/2‐MYC axis. Blocking MEK1/2‐PLK1 signaling therefore reduced outgrowth of basal‐like syngeneic and human breast tumors in in vivo models. In conclusion, high CEP55 levels dictate cell fate during perturbed mitosis. Forced mitotic cell death by blocking MEK1/2‐PLK1 represents a potential therapeutic strategy for MYC‐CEP55‐dependent basal‐like, triple‐negative breast cancers.

A multitargeted probe-based strategy to identify signaling vulnerabilities in cancers

Most cancer cells are dependent on a network of deregulated signaling pathways for survival and are insensitive, or rapidly evolve resistance, to selective inhibitors aimed at a single target. For these reasons, drugs that target more than one protein (polypharmacology) can be clinically advantageous. The discovery of useful polypharmacology remains serendipitous and is challenging to characterize and validate. In this study, we developed a non-genetic strategy for the identification of pathways that drive cancer cell proliferation and represent exploitable signaling vulnerabilities. Our approach is based on using a multitargeted kinase inhibitor, SM1-71, as a tool compound to identify combinations of targets whose simultaneous inhibition elicits a potent cytotoxic effect. As a proof of concept, we applied this approach to a KRAS-dependent non-small cell lung cancer (NSCLC) cell line, H23-KRAS^G12C Using a combination of phenotypic screens, signaling analyses, and kinase inhibitors, we found that dual inhibition of MEK1/2 and insulin-like growth factor 1 receptor (IGF1R)/insulin receptor (INSR) is critical for blocking proliferation in cells. Our work supports the value of multitargeted tool compounds with well-validated polypharmacology and target space as tools to discover kinase dependences in cancer. We propose that the strategy described here is complementary to existing genetics-based approaches, generalizable to other systems, and enabling for future mechanistic and translational studies of polypharmacology in the context of signaling vulnerabilities in cancers.

Recent therapeutic trends and promising targets in triple negative breast cancer

Breast cancer accounts for 25% of all types of cancer in women, and triple negative breast cancer (TNBC) comprises around 15~20% of breast cancers. Conventional chemotherapy and radiation are the primary systemic therapeutic strategies; no other FDA-approved targeted therapies are yet available as for TNBC. TNBC is generally characterized by a poor prognosis and high rates of proliferation and metastases. Due to these aggressive features and lack of targeted therapies, numerous attempts have been made to discover viable molecular targets for TNBC. Massive cohort studies, clinical trials, and in-depth analyses have revealed diverse molecular alterations in TNBC; however, controversy exists as to whether many of these changes are beneficial or detrimental in caner progression. Here we review the complicated tumorigenic processes and discuss critical findings and therapeutic trends in TNBC with a focus on promising therapeutic approaches, the clinical trials currently underway, and potent experimental compounds under preclinical and evaluation.

One-Step Generation of a Drug-Releasing Hydrogel Microarray-On-A-Chip for Large-Scale Sequential Drug Combination Screening

Large-scale screening of sequential drug combinations, wherein the dynamic rewiring of intracellular pathways leads to promising therapeutic effects and improvements in quality of life, is essential for personalized medicine to ensure realistic cost and time requirements and less sample consumption. However, the large-scale screening requires expensive and complicated liquid handling systems for automation and therefore lowers the accessibility to clinicians or biologists, limiting the full potential of sequential drug combinations in clinical applications and academic investigations. Here, a miniaturized platform for high-throughput combinatorial drug screening that is "pipetting-free" and scalable for the screening of sequential drug combinations is presented. The platform uses parallel and bottom-up formation of a heterogeneous drug-releasing hydrogel microarray by self-assembly of drug-laden hydrogel microparticles. This approach eliminates the need for liquid handling systems and time-consuming operation in high-throughput large-scale screening. In addition, the serial replacement of the drug-releasing microarray-on-a-chip facilitates different drug exchange in each and every microwell in a simple and highly parallel manner, supporting scalable implementation of multistep combinatorial screening. The proposed strategy can be applied to various forms of combinatorial drug screening with limited amounts of samples and resources, which will broaden the use of the large-scale screening for precision medicine.

MYC-Induced miR-203b-3p and miR-203a-3p Control Bcl-xL Expression and Paclitaxel Sensitivity in Tumor Cells

Taxanes are chemotherapeutic agents used in the treatment of solid tumors, particularly of breast, ovarian, and lung origin. However, patients show divergent therapy responses, and the molecular determinants of taxane sensitivity have remained elusive. Especially the signaling pathways that promote death of the taxane-treated cells are poorly characterized. Here we describe a novel part of a signaling route in which c-Myc enhances paclitaxel sensitivity through upregulation of miR-203b-3p and miR-203a-3p; two clustered antiapoptosis protein Bcl-xL controlling microRNAs. In vitro, the miR-203b-3p decreases the expression of Bcl-xL by direct targeting of the gene's mRNA 3'UTR. Notably, overexpression of the miR-203b-3p changed the fate of paclitaxel-treated breast and ovarian cancer cells from mitotic slippage to cell death. In breast tumors, high expression of the miR-203b-3p and MYC was associated with better therapy response and patient survival. Interestingly, in the breast tumors, MYC expression correlated negatively with BCL2L1 expression but positively with miR-203b-3p and miR-203a-3p. Finally, silencing of MYC suppressed the transcription of both miRNAs in breast tumor cells. Pending further validation, these results may assist in patient stratification for taxane therapy.

B7-H4 overexpression contributes to poor prognosis and drug-resistance in triple-negative breast cancer

Background

The expression of the immunoregulatory protein B7-H4 has been reported in many types of cancer, including breast cancer. However, its role in triple-negative breast cancer (TNBC), especially its correlation with patients’ prognosis and chemoresistance remains unclear.

Methods

The expression of B7-H4 in TNBC tissues and cell lines were measured with Real-Time PCR and western blotting. 65 cases of TNBC tissue samples and adjacent non-tumor tissue samples were analyzed by immunochemistry to demonstrate the correlation between the B7-H4 expression and clinicopathological characteristics. In vitro studies assessed mAb MIH43 alone and in combination with transfecting B7-H4 siRNA on the growth of chemosensitive and chemoresistant TNBC cell lines by CCK-8 and apoptotic enzyme-linked immunosorbent assay (ELISA).

Results

B7-H4 expression was detected positive in 59 of 65 (90.8%) different stage TNBC patients, especially in the samples of recurrence TNBC patients after receiving neoadjuvant chemotherapy treatment. Survival curves showed that patients with B7-H4 overexpression had significantly shorter survival and recurrence time than those with low B7-H4 expression (p < 0.005). Univariate and multivariate COX regression analysis demonstrated that B7-H4 was an independent predictor for advanced tumor stage. The monoclonal antibody of B7-H4 has the potential anti-proliferative effects on inhibiting the chemoresistant TNBC cell lines and increasing the sensitivity of TNBC cell lines to doxorubicin, paclitaxel or carboplatin. RNAi-mediated silencing of B7-H4 in TNBC cells enhanced drug-induced apoptosis via inhibiting PTEN/PI3K/AKT pathway, whereas reexpression of B7-H4 in B7-H4 knockdown and low B7-H4 expressing cells increased the phosphorylation of PI3K and AKT along with restoration of PETN expression.

Conclusions

Our data show that B7-H4 is a biomarker indicative of a poor prognosis in TNBC patients and at least partially downregulated in chemoresistance via PTEN/PI3K/AKT pathway. Targeting B7-H4 might provide an attractive therapeutic approach specifically for TNBC patients.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0597-9) contains supplementary material, which is available to authorized users.

Nitric oxide antagonism to glioblastoma photodynamic therapy and mitigation thereof by BET bromodomain inhibitor JQ1

Endogenous nitric oxide (NO) generated by inducible NO synthase (iNOS) promotes glioblastoma cell proliferation and invasion and also plays a key role in glioblastoma resistance to chemotherapy and radiotherapy. Non-ionizing photodynamic therapy (PDT) has anti-tumor advantages over conventional glioblastoma therapies. Our previous studies revealed that glioblastoma U87 cells up-regulate iNOS after a photodynamic challenge and that the resulting NO not only increases resistance to apoptosis but renders surviving cells more proliferative and invasive. These findings were largely based on the effects of inhibiting iNOS activity and scavenging NO. Demonstrating now that iNOS expression in photostressed U87 cells is mediated by NF-κB, we hypothesized that (i) recognition of acetylated lysine (acK) on NF-κB p65/RelA by bromodomain and extra-terminal (BET) protein Brd4 is crucial; and (ii) by suppressing iNOS expression, a BET inhibitor (JQ1) would attenuate the negative effects of photostress. The following evidence was obtained. (i) Like iNOS, Brd4 protein and p65-acK levels increased severalfold in photostressed cells. (ii) JQ1 at minimally toxic concentrations had no effect on Brd4 or p65-acK up-regulation after PDT but strongly suppressed iNOS, survivin, and Bcl-xL up-regulation, along with the growth and invasion spurt of PDT-surviving cells. (iii) JQ1 inhibition of NO production in photostressed cells closely paralleled that of growth/invasion inhibition. (iv) Finally, at 1% the concentration of iNOS inhibitor 1400W, JQ1 reduced post-PDT cell aggressiveness to a far greater extent. This is the first evidence for BET inhibitor targeting of iNOS expression in cancer cells and how such targeting can markedly improve therapeutic efficacy.

Synthesis and Investigation of S-Substituted 2-Mercaptobenzoimidazoles as Inhibitors of Hedgehog Signaling

Due to the arising resistance of common drugs targeting the Hedgehog signaling pathway, the identification of new compound classes with inhibitory effect is urgently needed. We were able to identify S-alkylated 2-mercaptobenzoimidazoles as a new compound class that exhibits Hedgehog signaling activity in a low micromolar range. The scope of the 2-mercaptobenzoimidazole motif has been investigated by the syntheses of diverse derivatives, revealing that the elongation of the linker unit and the exchange of particular substitution patterns are tolerable with respect to the activity of the compound class.

The microRNAs miR-200b-3p and miR-429-5p target the LIMK1/CFL1 pathway to inhibit growth and motility of breast cancer cells

Triple-negative breast cancer (TNBC) has the worst prognosis of all subtypes of breast cancer (BC), with limited options for conventional therapy and no targeted therapies. MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate gene expression. In this study, we aimed to determine whether two members of the miR-200 family, miR-200b-3p and miR-429-5p, are involved in BC cell proliferation and motility and to elucidate their target genes and pathways. We performed a meta-analysis that reveals down-regulated expression of miR-200b-3p and miR-429-5p in BC tissues and cell lines, consistent with a lower expression of miR-200b-3p and miR-429-5p in MDA-MB-231 and HCC1937 cells than in MCF-7 and MCF-10 cells. Overexpression of miR-200b-3p and miR-429-5p significantly inhibited the proliferation, migration, and invasion of TNBC cells; suppressed the expression of markers for proliferation and metastasis in TNBC cells. We next demonstrated that LIM domain kinase 1 (LIMK1) is a direct target gene of miR-200b-3p and miR-429-5p. Inhibition of LIMK1 reduced the expression and phosphorylation of cofilin 1 (CFL1), which polymerizes and depolymerizes F-actin and G-actin to reorganize cellular actin cytoskeleton. In addition, transfection with mimics for miR-200b-3p and miR-429-5p arrested G2/M and G0/G1 cell cycles respectively, suppressed the expression of the cell cycle–related complexes, cyclin D1/CDK4/CDK6 and cyclin E1/CDK2, in TNBC cells. In conclusion, miR-200b-3p and miR-429-5p suppress proliferation, migration, and invasion in TNBC cells, via the LIMK1/CFL1 pathway. These results provide insight into how specific miRNAs regulate TNBC progression and suggest that the LIMK1/CFL1 pathway is a therapeutic target for treating TNBC.

MDM2/X inhibitors under clinical evaluation: perspectives for the management of hematological malignancies and pediatric cancer

The two murine double minute (MDM) family members MDM2 and MDMX are at the center of an intense clinical assessment as molecular target for the management of cancer. Indeed, the two proteins act as regulators of P53, a well-known key controller of the cell cycle regulation and cell proliferation that, when altered, plays a direct role on cancer development and progression. Several evidence demonstrated that functional aberrations of P53 in tumors are in most cases the consequence of alterations on the MDM2 and MDMX regulatory proteins, in particular in patients with hematological malignancies where TP53 shows a relatively low frequency of mutation while MDM2 and MDMX are frequently found amplified/overexpressed. The pharmacological targeting of these two P53-regulators in order to restore or increase P53 expression and activity represents therefore a strategy for cancer therapy. From the discovery of the Nutlins in 2004, several compounds have been developed and reported with the ability of targeting the P53-MDM2/X axis by inhibiting MDM2 and/or MDMX. From natural compounds up to small molecules and stapled peptides, these MDM2/X pharmacological inhibitors have been extensively studied, revealing different biological features and different rate of efficacy when tested in in vitro and in vivo experimental tumor models. The data/evidence coming from the preclinical experimentation have allowed the identification of the most promising molecules and the setting of clinical studies for their evaluation as monotherapy or in therapeutic combination with conventional chemotherapy or with innovative therapeutic protocols in different tumor settings. Preliminary results have been recently published reporting data about safety, tolerability, potential side effects, and efficacy of such therapeutic approaches. In this light, the aim of this review is to give an updated overview about the state of the art of the clinical evaluation of MDM2/X inhibitor compounds with a special attention to hematological malignancies and to the potential for the management of pediatric cancers.