Sensitivity Of Breast Cancer Cells Research Articles

Abstract 645: Network-based assessment of HDAC6 activity is highly predictive of pre-clinical and clinical responses to the HDAC6 inhibitor ricolinostat

Abstract Despite the anticancer activity of pan-histone deacetylase (HDAC) inhibitors, their clinical use has been limited due to toxicity. However, the development of more specific inhibitors that selectively inhibit individual HDACs is emerging as a novel and well-tolerated alternative. Here, we present the results of the first clinical trial evaluating the activity of ricolinostat (the leading HDAC6 inhibitor) in breast cancer (BC) patients. We have developed a computational network-based algorithm to evaluate the activity of the HDAC6 protein, based on the enrichment of its transcriptional targets in differentially expressed genes (HDAC6 score). Through preclinical in vitro and in vivo studies, we confirmed that the HDAC6 score can stratify the sensitivity of BC cells to ricolinostat treatment and may thus have value as a predictive biomarker. Moreover, analysis of ~3,000 primary human breast cancers showed that ~30% of them present high HDAC6 scores. Based on these results, we designed a phase Ib clinical trial to evaluate the activity of ricolinostat plus nab-paclitaxel in metastatic BC patients. Study results showed that the two agents can be safely combined, that clinical activity is identified specifically in patients with HR+/HER2- disease, and that the HDAC6 score was predictive of response. Expansion of our analysis to other tumor types identified multiple cohorts enriched in high HDAC6 score samples. These results suggest that the HDAC6 score may provide an effective, CLIA certified predictive biomarker of ricolinostat sensitivity in multiple human cancers. Citation Format: Qingfei Pan, Tizita Zeleke, Cody Chiuzan, Maika Onishi, Mariano Alvarez, Erin Honan, Min Yang, Pei Ling Chia, Partha Mukhopadhyay, Sean Kelly, Ruby Wu, Kathleen Fenn, Meghna Trivedi, Melissa Accordino, Katherine Crew, Dawn Hershman, Matthew Maurer, Simon Jones, Andrea Califano, Kevin Kalinsky, Jiyang Yu, Jose Silva. Network-based assessment of HDAC6 activity is highly predictive of pre-clinical and clinical responses to the HDAC6 inhibitor ricolinostat [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 645.

LncRNA NEAT1 promotes the Taxol resistance of breast cancer via sponging the miR-23a-3p-FOXA1 axis.

Breast cancer is the most prevalent malignancy among women worldwide. Paclitaxel (Taxol) is a widely applied chemotherapeutic agent against breast cancer. Although Taxol therapy has achieved improvements recently, development of chemoresistance of breast cancer patients is a major obstacle, leading to therapeutic failure. Long non-coding RNAs (lncRNAs) play pivotal roles in tumorigenesis and progresses of breast cancer. However, the biological roles and molecular targets of lncRNA NEAT1 in Taxol-resistant breast cancer remain unclear. Here, we report that NEAT1 is significantly upregulated in breast tumors and cell lines. In addition, silencing NEAT1 effectively sensitizes breast cancer cells to Taxol. Bioinformatical analysis and luciferase assay demonstrated that miR-23a-3p could be sponged and downregulated by NEAT1. We demonstrated that miR-23a-3p was downregulated and functioned as a tumor suppressor in breast cancer. Furthermore, in the established Taxol-resistant MDA-MB-231 breast cancer cell line, we detected significantly increased NEAT1 expression and downregulated miR-23a-3p expression. Importantly, FOXA1 was identified and validated as a direct target of miR-23a-3p in breast cancer cells. Rescue experiments demonstrated that the restoration of miR-23a-3p in NEAT1-overexpressing Taxol-resistant breast cancer cells successfully overcame the NEAT1-promoted Taxol resistance. Taken together, our results revealed the clinical roles and molecular mechanisms for the NEAT1-mediated chemoresistance, providing new insights into the development of non-coding RNA-based therapeutic strategies for enhancing the anti-cancer effects of traditional chemotherapeutic drugs.

The Impact of Extracellular Ca2+ and Nanosecond Electric Pulses on Sensitive and Drug-Resistant Human Breast and Colon Cancer Cells.

Simple SummaryThe drug resistance phenomenon in cancer constantly induces problems in therapeutic protocols. Pulsed electric fields (PEFs) seem to be a promising method in drug molecule delivery. Here we have proved that electroporation supported by calcium ions can alternate the activity of drug resistance proteins. Our results indicated that MDR1 expression is not significantly modified by nanosecond electroporation in multidrug-resistant cells. However, PEF significantly inhibited MDR1 activity and cell viability when combined with calcium ions.(1) Background: Calcium electroporation (CaEP) is based on the application of electrical pulses to permeabilize cells (electroporation) and allow cytotoxic doses of calcium to enter the cell. (2) Methods: In this work, we have used doxorubicin-resistant (DX) and non-resistant models of human breast cancer (MCF-7/DX, MCF-7/WT) and colon cancer cells (LoVo, LoVo/DX), and investigated the susceptibility of the cells to extracellular Ca2+ and electric fields in the 20 ns–900 ns pulse duration range. (3) Results: We have observed that colon cancer cells were less susceptible to PEF than breast cancer cells. An extracellular Ca2+ (2 mM) with PEF was more disruptive for DX-resistant cells. The expression of glycoprotein P (MDR1, P-gp) as a drug resistance marker was detected by the immunofluorescent (CLSM) method and rhodamine-123 efflux as an MDR1 activity. MDR1 expression was not significantly modified by nanosecond electroporation in multidrug-resistant cells, but a combination with calcium ions significantly inhibited MDR1 activity and cell viability. (4) Conclusions: We believe that PEF with calcium ions can reduce drug resistance by inhibiting drug efflux activity. This phenomenon of MDR mechanism disruption seems promising in anticancer protocols.

Pluronic F127 micelles improve the stability and enhance the anticancer stem cell efficacy of citral in breast cancer.

Aim: Improving the stability and anti-cancer stem cell (CSC) activity of citral, a natural ALDH1A inhibitor. Materials & methods: Citral-loaded micelles (CLM) were obtained using Pluronic® F127 and its efficacy tested on the growth of four breast cancer cell lines. The impact of the CLM on the growth and functional hallmarks of breast CSCs were also evaluated using mammosphere and CSC reporter cell lines. Results: CLM improved the stability and growth inhibitory effects of citral. Importantly, CLM fully blocking the stemness features of CSCs (self-renewal, differentiation and migration) and in combination with paclitaxel CLM sensitized breast cancer cells to the chemotherapy. Conclusion: Targeting CSCs with CLM could improve the treatment of advanced breast cancer in combination with the standard chemotherapy.

LncRNA FGD5-AS1 Facilitates the Radioresistance of Breast Cancer Cells by Enhancing MACC1 Expression Through Competitively Sponging miR-497-5p.

BackgroundLncRNA-FGD5-AS1, as an oncogene, participates in the development and progress of various cancers. However, the exact role and the molecular mechanisms by which FGD5-AS1 regulates radiosensitivity in breast cancer (BC) remains largely unknown.MethodsWe used X-Ray weekly-dose-increase method to establish radiation-resistance cell lines. Bioinformatics tools analyze the expression of FGD5-AS1 in breast cancer tissue and evaluated the relationship between FGD5-AS1 and clinic-pathological features. CCK-8 and colony formation were used to analyze cell proliferation. Western blotting and qPCR were applied to detect protein and gene expression, respectively. RNA interference was used to knock down the endogenous gene expression. Luciferase reporter system and immunoprecipitates were applied to verify the target of FGD5-AS1.ResultFGD5-AS1 was overexpressed in BC tissues and radiation-resistance cell lines. Higher levels of FGD5-AS1 predicted poorer clinical characteristics and prognosis. Loss-of-function FGD5-AS1 sensitized BC cells to X-ray, meanwhile, the cell gained radiation-resistance when exogenous FGD5-AS1 was expressed. FGD5-AS1 depletion arrested cells at G0/G1 and triggers cell apoptosis. The starBase database (ENCORI), predicted binding site of miR-497-5p in FGD5-AS1 sequence, and luciferase reporter system and immunoprecipitates verified miR-497-5p was the target of FGD5-AS1. Furthermore, MACC1 was predicted and verified as the target of miR-497-5p. Loss-of-function FGD5-AS1 sensitized ionizing radiation was rescued by the up-regulation of MACC1 and the inhibition of miR-497.ConclusionFGD5-AS1 displays an oncogene profile in CRC; patients with high expression of FGD5-AS1 should benefit less from radiotherapy and need a more frequent follow-up. Besides, FGD5-AS1 may be a potential therapeutic target for CRC.

Targeting of lactate dehydrogenase C dysregulates the cell cycle and sensitizes breast cancer cells to DNA damage response targeted therapy.

The cancer testis antigen (CTA) lactate dehydrogenase C (LDHC) is a promising anticancer target with tumor‐specific expression and immunogenicity. Interrogation of breast cancer patient cohorts from The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) indicate that upregulation of LDHC expression correlates with unfavorable prognosis. Although the role of LDHC is well characterized in spermatocytes, its role in tumors remains largely unknown. We investigated whether LDHC is involved in regulating genomic stability and whether it could be targeted to affect tumor cellular fitness. Silencing LDHC in four breast cancer cell lines significantly increased the presence of giant cells, nuclear aberrations, DNA damage, and apoptosis. LDHC‐silenced cells demonstrated aberrant cell cycle progression with differential expression of cell cycle checkpoint and DNA damage response regulators. In addition, LDHC silencing‐induced microtubule destabilization, culminating in increased mitotic catastrophe and reduced long‐term survival. Notably, the clonogenicity of LDHC‐silenced cells was further reduced by treatment with the poly (ADP‐ribose) polymerase (PARP) inhibitor olaparib and with the DNA‐damaging drug cisplatin. This study supports the therapeutic potential of targeting LDHC to mitigate cancer cell survival and improve sensitivity to agents that cause DNA damage or inhibit its repair.

Compensatory expression of NRF2-dependent antioxidant genes is required to overcome the lethal effects of Kv11.1 activation in breast cancer cells and PDOs

Potassium channels are important regulators of cellular homeostasis and targeting these proteins pharmacologically is unveiling important mechanisms in cancer cell biology. Here we demonstrate that pharmacological stimulation of the Kv11.1 potassium channel activity results in mitochondrial reactive oxygen species (ROS) production and fragmentation in breast cancer cell lines and patient-derived organoids independent of breast cancer subtype. mRNA expression profiling revealed that Kv11.1 activity significantly altered expression of genes controlling the production of ROS and endoplasmic-reticulum (ER) stress. Characterization of the transcriptional signature of breast cancer cells treated with Kv11.1 potassium channel activators strikingly revealed an adaptive response to the potentially lethal augmentation of ROS by increasing Nrf2-dependent transcription of antioxidant genes. Nrf2 in this context was shown to promote survival in breast cancer, whereas knockdown of Nrf2 lead to Kv11.1-induced cell death. In conclusion, we found that the Kv11.1 channel activity promotes oxidative stress in breast cancer cells and that suppression of the Nrf2-mediated anti-oxidant survival mechanism strongly sensitized breast cancer cells to a lethal effect of pharmacological activation of Kv11.1.

MiR-27-3p Enhances the Sensitivity of Triple-Negative Breast Cancer Cells to the Antitumor Agent Olaparib by Targeting PSEN-1, the Catalytic Subunit of Γ-Secretase.

Olaparib has been used in the treatment of triple-negative breast cancer (TNBC) with BRCA mutations. In the present study, we demonstrated the effect of miR-27-3p on the γ-secretase pathway by regulating the sensitivity of TNBC cells to olaparib. miR-27-3p, a microRNA with the potential to target PSEN-1, the catalytic subunit of γ-secretase mediating the second step of the cleavage of the Notch protein, was identified by the online tool miRDB and found to inhibit the expression of PSEN-1 by directly targeting the 3’-untranslated region (3’-UTR) of PSEN-1. The overexpression of miR-27-3p inhibited the activation of the Notch pathway via the inhibition of the cleavage of the Notch protein, mediated by γ-secretase, and, in turn, enhanced the sensitivity of TNBC cells to the antitumor agent olaparib. Transfection with PSEN-1 containing mutated targeting sites for miR-27-3p or the expression vector of the Notch protein intracellular domain (NICD) almost completely blocked the effect of miR-27-3p on the Notch pathway or the sensitivity of TNBC cells to olaparib, respectively. Therefore, our results suggest that the miR-27-3p/γ-secretase axis participates in the regulation of TNBC and that the overexpression of miR-27-3p represents a potential approach to enhancing the sensitivity of TNBC to olaparib.

Carbon Monoxide Inhibits Cytochrome P450 Enzymes CYP3A4/2C8 in Human Breast Cancer Cells, Increasing Sensitivity to Paclitaxel.

Paclitaxel (PTX) is a first-line treatment in breast cancer, though resistance develops quickly and frequently. Cytochrome P450 enzymes CYP3A4 and CYP2C8, which metabolically inactivate PTX in hepatic tissue, are overexpressed in malignant breast tissues. CYP3A4 expression correlates with PTX therapy failure and poor outcomes, though no direct evidence of CYP3A4 contributing to PTX sensitivity exists. Because CYP3A4/2C8 is susceptible to carbon monoxide (CO)-mediated inhibition and CO (a gaseous signaling molecule) has previously exhibited drug-sensitizing effects in cancer cells, we hypothesized that CO-mediated inhibition of CYP3A4/2C8 could lead to enhanced drug sensitivity. Using a photo-activated CO-releasing molecule, we have assessed the ability of CO to alter the pharmacokinetics of PTX in breast cancer cells via inhibition of CYP3A4/2C8 and determined that CO does enhance sensitivity of breast cancer cells to PTX. Inhibition of CYP3A4/2C8 by CO could therefore be a promising therapeutic strategy to enhance PTX response in breast cancer.

SWIM domain protein ZSWIM4 is required for JAK2 inhibition resistance in breast cancer

AimsJanus kinase 2 (JAK2)/signal transducer and activator of transcription (STAT) signaling plays a critical role in the progression of breast cancer. However, a small part of tumor cells survived from the killing effect of JAK2 inhibitor. We aimed to find out the mechanism of drug resistance in breast cancer cells and develop new therapeutic strategies. Materials and methodsThe anti-tumor effect of TG101209 in breast cancer cells was confirmed by cell counting kit 8 and flow cytometry. Western blotting was used to determine the up-regulation of zinc finger SWIM-type containing 4 (ZSWIM4) induced by TG101209. In vitro and in vivo experiments were performed to evaluate the role of ZSWIM4 in the resistance of breast cancer cells to TG101209. Through the determination and analysis of 50% inhibiting concentration (IC50) curves, the effect of combination therapy was confirmed. Key findingsOur data indicate that the elevated expression of ZSWIM4 contributes to JAK2 inhibition resistance, as knockdown of ZSWIM4 significantly enhances the sensitivity of breast cancer cells to TG101209 and over-expression of this gene mitigates the killing effect. Furthermore, the expression of vitamin D receptor (VDR) and utilization of 1α,25-(OH)2VD3 is decreased in ZSWIM4-knockdown breast cancer cells. VDR-silencing or GW0742-mediated blockade of VDR activity can partially reverse the JAK2 inhibition resistance. SignificanceOur data implicated that ZSWIM4 might be an inducible resistance gene of JAK2 inhibition in breast cancer cells. The combination of JAK2 inhibitor and VDR inhibitor may achieve better coordinated therapeutic effect in breast cancer.

Epithelial-mesenchymal transition sensitizes breast cancer cells to cell death via the fungus-derived sesterterpenoid ophiobolin A

The epithelial–mesenchymal transition (EMT) imparts properties of cancer stem-like cells, including resistance to frequently used chemotherapies, necessitating the identification of molecules that induce cell death specifically in stem-like cells with EMT properties. Herein, we demonstrate that breast cancer cells enriched for EMT features are more sensitive to cytotoxicity induced by ophiobolin A (OpA), a sesterterpenoid natural product. Using a model of experimentally induced EMT in human mammary epithelial (HMLE) cells, we show that EMT is both necessary and sufficient for OpA sensitivity. Moreover prolonged, sub-cytotoxic exposure to OpA is sufficient to suppress EMT-imparted CSC features including sphere formation and resistance to doxorubicin. In vivo growth of CSC-rich mammary cell tumors, is suppressed by OpA treatment. These data identify a driver of EMT-driven cytotoxicity with significant potential for use either in combination with standard chemotherapy or for tumors enriched for EMT features.

Abemaciclib, a CDK4 and 6 inhibitor with unique pharmacological properties for breast cancer therapy.

e12506 Background: Breast cancer is the second most common cancer worldwide. Pharmacologically targeting cyclin-dependent kinases 4 and 6 (CDK4 & 6) has proven to be a successful therapeutic approach in patients with estrogen receptor positive (ER+) breast cancer. Differences in both efficacy and toxicity among the available CDK4 & 6 inhibitors has generated interest in a biological explanation. Abemaciclib is an adenosine triphosphate-competitive, reversible, selective inhibitor of CDK4 & 6 that has shown antitumor activity as a single agent and in combination with standard endocrine therapy (ET), in hormone receptor positive (HR+) metastatic breast cancer patients including those with ET resistance, and in combination with ET in high-risk early breast cancer patients. This study examines attributes of abemaciclib and other CDK4 & 6 inhibitors. Methods: The potency of abemaciclib for CDK4 was evaluated using biochemicals and breast cancer cell-based assays. Additionally, different combinations with an anti-estrogen therapy (e.g., tamoxifen, fulvestrant) were analyzed in an in vitro palbociclib (CDK4 & 6 inhibitor)-resistant breast cancer cell model, as well as in a set of CDK4 & 6 sensitive breast cancer cell models. Using cell-free assays, high content imaging and flow cytometry approaches, a subset of markers were monitored to characterize the phenotype of sensitive cell lines in a continuous dose schedule. Results: In in vitro, cell-free assays, abemaciclib shows selectivity for CDK4 over CDK6, and in cell-based assays, abemaciclib preferentially inhibits the proliferation of cells dependent on the presence of CDK4, not CDK6. Abemaciclib inhibits cell proliferation in a wide range of breast cancer cell lines, showing activity regardless of human epidermal growth factor receptor 2 (HER2) and PI3KCA gene mutation status. Furthermore, in a cell line resistant to palbociclib, abemaciclib in combination with fulvestrant (ET) restores CDK4 & 6 sensitivity, leading to cell senescence and cell death. Finally, in human bone marrow progenitor cells, abemaciclib shows a lesser impact on myeloid maturation than other CDK4 & 6 inhibitors, palbociclib and ribociclib, allowing for continuous dosing. Conclusions: In pre-clinical experiments, abemaciclib is a potent cell growth inhibitor, inhibiting preferentially the CDK4/CyclinD1 complex, leading to cell senescence and cell death. These pre-clinical results support the differentiated safety and efficacy profile of abemaciclib observed in clinical trials.

Long non-coding RNA TPT1-AS1 sensitizes breast cancer cell to paclitaxel and inhibits cell proliferation by miR-3156-5p/caspase 2 axis

Long non-coding RNAs (lncRNAs) are key modulators during cancer progression. Application of using lncRNA expression to evaluate patient prognosis and sensitivity to treatment is highly anticipated, yet the expression and mechanism of many lncRNAs remain unknown. Herein, we projected for the investigation of TPT1-AS1 function in breast cancer. TPT1-AS1 was assessed by bioinformatic analysis of publicly available datasets and quantitative real-time PCR (qRT-PCR). Cell sensitivity to paclitaxel and cell proliferation was measured by flow cytometry and CCK-8. Interaction among TPT1-AS1, microRNA (miRNA, miR)-3156-5p and Caspase 2 (CASP2) was studied by bioinformatic analysis, qRT-PCR, western blot as well as dual luciferase reporter assay. Herein, TPT1-AS1 was significantly diminished in breast cancer from publicly available datasets and our collected samples. In breast cancer cells, TPT1-AS1 overexpression repressed cell proliferation and sensitized breast cancer cells to paclitaxel. RegRNA 2.0 predicted a potential interaction between TPT1-AS1 and miR-3156-5p which was confirmed by qRT-PCR as well as dual luciferase reporter assay. CASP2, a proapoptotic gene, was corroborated to be targeted by miR-3156-5p. Meanwhile, TPT1-AS1 upregulated CASP2 in breast cancer cells, and its biological function was reversed by CASP2 knockdown. Collectively, TPT1-AS1 diminished cell proliferation and sensitized cells to chemotherapy by sponging miR-3156-5p and upregulating CASP2, acting as a biomarker for patients with breast cancer.

A Comprehensive RNA Study to Identify circRNA and miRNA Biomarkers for Docetaxel Resistance in Breast Cancer.

To investigate the relationship between non-coding RNAs [especially circular RNAs (circRNAs)] and docetaxel resistance in breast cancer, and to find potential predictive biomarkers for taxane-containing therapies, we have performed transcriptome and microRNA (miRNA) sequencing for two established docetaxel-resistant breast cancer (DRBC) cell lines and their docetaxel-sensitive parental cell lines. Our analyses revealed differences between circRNA signatures in the docetaxel-resistant and -sensitive breast cancer cells, and discovered circRNAs generated by multidrug-resistance genes in taxane-resistant cancer cells. In DRBC cells, circABCB1 was identified and validated as a circRNA that is strongly up-regulated, whereas circEPHA3.1 and circEPHA3.2 are strongly down-regulated. Furthermore, we investigated the potential functions of these circRNAs by bioinformatics analysis, and miRNA analysis was performed to uncover potential interactions between circRNAs and miRNAs. Our data showed that circABCB1, circEPHA3.1 and circEPHA3.2 may sponge up eight significantly differentially expressed miRNAs that are associated with chemotherapy and contribute to docetaxel resistance via the PI3K-Akt and AGE-RAGE signaling pathways. We also integrated differential expression data of mRNA, long non-coding RNA, circRNA, and miRNA to gain a global profile of multi-level RNA changes in DRBC cells, and compared them with changes in DNA copy numbers in the same cell lines. We found that Chromosome 7 q21.12-q21.2 was a common region dominated by multi-level RNA overexpression and DNA amplification, indicating that overexpression of the RNA molecules transcribed from this region may result from DNA amplification during stepwise exposure to docetaxel. These findings may help to further our understanding of the mechanisms underlying docetaxel resistance in breast cancer.

Silencing long non-coding RNA HNF1A-AS1 inhibits growth and resistance to TAM of breast cancer cells via the microRNA-363/SERTAD3 axis

Long non-coding RNAs (lncRNAs) can exert effects on drug resistance of cancer cells. This study investigated the role of lncRNA HNF1A-antisense 1 (HNF1A-AS1) in growth and Tamoxifen (TAM) sensitivity of breast cancer (BC) cells. HNF1A-AS1 expression was promoted in BC cells and tissues. BC cells with HNF1A-AS1 silencing were constructed to detect cell proliferation. TAM resistant cell line with HNF1A-AS1 silencing and parent cell line with overexpressed HNF1A-AS1 were constructed to measure drug resistance. Silencing HNF1A-AS1 reduced proliferation and TAM resistance of BC cells. The downstream microRNAs (miRs) of HNF1A-AS1 and its targets were figured out and their functions in TAM resistance of BC cells were identified. HNF1A-AS1 sponged miR-363 to promote SERTAD3 expression. Downregulation of miR-363 or upregulation of SERTAD3 stimulated TAM resistance of BC cells. The findings in vitro were reproduced in in vivo experiments. It could be concluded that silencing HNF1A-AS1 inhibited growth and drug resistance to TAM of BC cells through the miR-363/SERTAD3 axis and the inactivation of the TGF-β/Smad pathway.

Multifunctional Liposomes Enable Active Targeting and Twinfilin 1 Silencing to Reverse Paclitaxel Resistance in Brain Metastatic Breast Cancer.

Paclitaxel (PTX) is a first-line chemotherapeutic drug for breast cancer, but PTX resistance often occurs in metastatic breast cancer. In addition, due to the poor targeting of chemotherapeutic drugs and the presence of the blood-brain barrier (BBB), it is hard to effectively treat brain metastatic breast cancer using paclitaxel. Thus, it is urgent to develop an effective drug delivery system for the treatment of brain metastatic breast cancer. The current study found that TWF1 gene, an epithelial-mesenchymal transition-associated gene, was overexpressed in brain metastatic breast cancer (231-BR) cells and was associated with the PTX resistance of 231-BR cells. Knockdown of TWF1 by small interference RNA (siRNA) in 231-BR cells could effectively increase the sensitivity of brain metastatic breast cancer cells to paclitaxel. Then, a liposome-based drug delivery system was developed for PTX delivery across BBB, enhancing PTX sensitivity and brain metastases targeting via BRBP1 peptide modification. The results showed that BRBP1-modified liposomes could effectively cross the BBB, specifically accumulate in brain metastases, and effectively interfere TWF1 gene expression in vitro and in vivo, and thus they enhanced proliferation inhibition, cell cycle arrest, and apoptosis induction, thereby inhibiting the formation and growth of brain metastases. In summary, our results indicated that BRBP1-modified and PTX- and TWF1 siRNA-loaded liposomes have the potential for the treatment of brain metastatic breast cancer, which lays the foundation for the development of a new targeted drug delivery system.

Magnetic Particles with Polymeric Shells Bearing Cholesterol Moieties Sensitize Breast Cancer Cells to Low Doses of Doxorubicin.

One of the promising strategies for improvement of cancer treatment is application of a combination therapy. The aim of this study was to investigate the anticancer activity of nanoformulations containing doxorubicin and iron oxide particles covered with polymeric shells bearing cholesterol moieties. It was postulated that due to high affinity to cell membranes, particles comprising poly(cholesteryl acrylate) can sensitize cancer cells to doxorubicin chemotherapy. The performed analyses revealed that the developed systems are effective against the human breast cancer cell lines MCF-7 and MDA-MB-231 even at low doses of the active compound applied (0.5 µM). Additionally, high compatibility and lack of toxicity of the tested materials against human red blood cells, immune (monocytic THP-1) cells, and cardiomyocyte H9C2(2-1) cells was demonstrated. Synergistic effects observed upon administration of doxorubicin with polymer–iron oxide hybrids comprising poly(cholesteryl acrylate) may provide an opportunity to limit toxicity of the drug and to improve its therapeutic efficiency at the same time.

Long non-coding RNA TMPO-AS1 facilitates chemoresistance and invasion in breast cancer by modulating the miR-1179/TRIM37 axis.

Breast cancer has become the most common female tumor in the world. Although great progress has been made in the past decade, the treatment of advanced breast cancer remains unsatisfactory. An increasing number of reports have indicated that long non-coding RNAs (lncRNAs) have a pivotal role in chemoresistance as potential oncogenes in numerous types of cancer. However, the precise mechanisms underlying the action of lncRNAs in breast cancer resistance to chemotherapy have yet to be fully elucidated. In the present study, the function and molecular mechanisms of the lncRNA TMPO-antisense RNA 1 (AS1) in terms of its resistance to docetaxel (DOC) were explored in the MDA-MB-231 and MCF7 breast cancer cell lines. The results obtained suggested that TMPO-AS1 was markedly upregulated in DOC-resistant breast cancer cells compared with the sensitive breast cancer cells. Functionally, TMPO-AS1-knockdown sensitized MDA-231/DOC and MCF-7/DOC cells to DOC and suppressed cell invasion, with increased rates of DOC-induced apoptosis. Mechanistically, TMPO-AS1-downregulation induced DOC-sensitivity in breast cancer cells via depleting tripartite motif-containing protein 37 (TRIM37) by sponging microRNA (miR)-1179. Taken together, the present study has revealed the existence of a novel TMPO-AS1/miR-1179/TRIM37 molecular axis conferring DOC resistance of breast cancer cells, thereby suggesting a promising novel therapeutic target for breast cancer.

Preparation, characterization, and in vitro tumor-suppressive effect of anti-miR-21-equipped RNA nanoparticles

MicroRNAs play an irreplaceable role in gene expression regulation. Upregulation of several miRNAs increases the risk of invasion and metastasis of breast cancer cells. An oncogenic miRNA, miR-21, is highly expressed in triple-negative breast cancer (TNBC) and is associated with tumor proliferation, invasion, carcinogenesis, prognosis, and therapeutic resistance. However, targeted delivery of therapeutic anti-miRNAs into cancer cells remains challenging, especially for TNBC. In this study, we report the application of an RNA nanotechnology-based platform for the targeted delivery of anti-miR-21 by epidermal growth factor receptor (EGFR) aptamer in vitro to TNBC and chemical-resistant breast cancer cells. RNA nanoparticles reduced cell viability and sensitized breast cancer cells to doxorubicin (DOX) treatment in vitro. Inhibition of miR-21 by RNA nanoparticles suppressed TNBC cell invasion, migration, and colony formation. The results indicate the potential application of nanotechnology-based delivery platforms in clinical anti-cancer therapeutics.

Glucosamine attenuates drug resistance in Mitoxantrone-resistance breast cancer cells.

This study was aimed at investigating the cytotoxicity and multi-drug resistance (MDR) reversal effect of Glucosamine (GlcN) on resistant BCRP-overexpressing breast cancer MCF-7/MX cells. After confirming the overexpression of BCRP, the cytotoxicity and MDR reversing potential of GlcN on MCF-7/MX mitoxantrone-resistant and MCF-7 sensitive breast cancer cells were assessed via MTT assay. The effects of GlcN on mitoxantrone accumulation were analyzed through flow cytometry. Finally, the expression of BCRP and Epithelial-Mesenchymal Transition (EMT)-related markers following the exposure to GlcN were assessed by real-time RT-PCR. This study showed that glucosamine had an inhibitory effect on the proliferation of human breast cancer cells. The respective IC50 values for MCF-7/MX cells following exposure to mitoxantrone (MX) in the presence of GlcN (0, 0.5 and 1 mm) for 72 h were 3.61 ± 0.21, 0.598 ± 0.041 and 0.284 ± 0.016 μm, respectively. Furthermore, GlcN reduced the expression of BCRP mRNA without any significant effect on EMT-related markers in breast cancer cells. These results proposed that glucosamine as a natural sugar could down regulate the BCRP expression and increased MX cytotoxicity in breast cancer cells.