Increased expression of P-glycoprotein is associated with doxorubicin chemoresistance in the metastatic 4T1 breast cancer model

Mechanisms of Sorafenib Resistance in HCC Culture Relate to the Impaired Membrane Expression of Organic Cation Transporter 1 (OCT1)

Introduction

Sorafenib, an FDA-approved drug for advanced hepatocellular carcinoma (HCC) treatment, encounters resistance in many patients. Deciphering the mechanisms underlying sorafenib resistance is crucial for devising alternative strategies to overcome it.

Aim

This study aimed to investigate sorafenib resistance mechanisms using a diverse panel of HCC cell lines.

Methods

HCC cell lines were subjected to continuous sorafenib treatment, and stable cell lines (Huh 7.5 and Huh 7PX) exhibiting sustained growth in its presence were isolated. The investigation of drug resistance mechanisms involved a comparative analysis of drug-targeted signal transduction pathways (EGFR/RAF/MEK/ERK/Cyclin D), sorafenib uptake, and membrane expression of the drug uptake transporter.

Results

HCC cell lines (Huh 7.5 and Huh 7PX) with a higher IC50 (10μM) displayed a more frequent development of sorafenib resistance compared to those with a lower IC50 (2-4.8μM), indicating a potential impact of IC50 variation on initial treatment response. Our findings reveal that activated overexpression of Raf1 kinases and impaired sorafenib uptake, mediated by reduced membrane expression of organic cation transporter-1 (OCT1), contribute to sorafenib resistance in HCC cultures. Stable expression of the drug transporter OCT1 through cDNA transfection or adenoviral delivery of OCT1 mRNA increased sorafenib uptake and successfully overcame sorafenib resistance. Additionally, consistent with sorafenib resistance in HCC cultures, cirrhotic liver-associated human HCC tumors often exhibited impaired membrane expression of OCT1 and OCT3.

Conclusion

Intrinsic differences among HCC cell clones, affecting sorafenib sensitivity at the expression level of Raf kinases, drug uptake, and OCT1 transporters, were identified. This study underscores the potential of HCC tumor targeted OCT1 expression to enhance sorafenib treatment response.

Exosomal miR-122-3p represses the growth and metastasis of MCF-7/ADR cells by targeting GRK4-mediated activation of the Wnt/β-catenin pathway

Breast cancer (BC) is a common cancer whose incidence continues to grow while its medical progress has stagnated. miRNAs are vital messengers that facilitate communications among different cancer cells. This study was to reveal the correlation of miR-122-3p expression with BC metastasis and Adriamycin (ADM) resistance and its mechanism of inhibiting BC metastasis. We found that expression of miR-122-3p is negatively correlated with BC metastasis and is lower in MCF-7/ADR cells. Overexpression of miR-122-3p in MCF-7/ADR cancer cells impairs their ability to migrate, invade, and stimulate blood vessel formation. Further research found that miR-122-3p directly binds to the 3' UTR of GRK4, reducing the phosphorylation of LRP6, which activates the Wnt/β-catenin signaling pathway, facilitating BC development and metastasis. In addition, we observed that miR-122-3p is present in MCF-7  cells, and treatment of MCF-7/ADR cells with MCF-7-derived exosomes, but not with exosomes from miR-122-3p-deficient MCF-7 cells, has identical effects to miR-122-3p overexpression. Data from xenograft experiments further suggest that excess miR-122-3p and MCF-7-derived exosomes inhibit the growth and metastasis of MCF-7/ADR cancer cells in vivo. In conclusion our data reveal that exosomal miR-122-3p may negatively regulate BC growth and metastasis, potentially serving as a diagnostic and druggable target for BC treatment.

Cholesterol-modified sphingomyelin chimeric lipid bilayer for improved therapeutic delivery

Cholesterol (Chol) fortifies packing and reduces fluidity and permeability of the lipid bilayer in vesicles (liposomes)-mediated drug delivery. However, under the physiological environment, Chol is rapidly extracted from the lipid bilayer by biomembranes, which jeopardizes membrane stability and results in premature leakage for delivered payloads, yielding suboptimal clinic efficacy. Herein, we report a Chol-modified sphingomyelin (SM) lipid bilayer via covalently conjugating Chol to SM (SM-Chol), which retains membrane condensing ability of Chol. Systemic structure activity relationship screening demonstrates that SM-Chol with a disulfide bond and longer linker outperforms other counterparts and conventional phospholipids/Chol mixture systems on blocking Chol transfer and payload leakage, increases maximum tolerated dose of vincristine while reducing systemic toxicities, improves pharmacokinetics and tumor delivery efficiency, and enhances antitumor efficacy in SU-DHL-4 diffuse large B-cell lymphoma xenograft model in female mice. Furthermore, SM-Chol improves therapeutic delivery of structurally diversified therapeutic agents (irinotecan, doxorubicin, dexamethasone) or siRNA targeting multi-drug resistant gene (p-glycoprotein) in late-stage metastatic orthotopic KPC-Luc pancreas cancer, 4T1-Luc2 triple negative breast cancer, lung inflammation, and CT26 colorectal cancer animal models in female mice compared to respective FDA-approved nanotherapeutics or lipid compositions. Thus, SM-Chol represents a promising platform for universal and improved drug delivery.

Role of microRNA-4739 in enhancing cisplatin chemosensitivity by negative regulation of RHBDD2 in human cervical cancer cells

BACKGROUND

Cisplatin (DDP) is a widely used chemotherapy drug for advanced cervical cancer (CC), but resistance poses a significant challenge. While miR-4739 has been implicated in tumor development, its specific role in regulating DDP resistance in CC remains unclear.

METHODS

We analyzed the expression levels of miR-4739 and RHBDD2 in DDP-resistant and DDP-sensitive CC tissues using quantitative real-time polymerase chain reaction (PCR) and assessed their correlation through Spearman's correlation analysis. DDP-resistant CC cell lines (HeLa/DDP and SiHa/DDP) were established by gradually increasing DDP concentrations, followed by transfection with miR-4739 mimics, si-RHBDD2, or a RHBDD2 overexpression vector. A series of functional assays, including CCK-8 assay, colony formation, flow cytometry, and transwell assay were performed. The interaction between miR-4739 and RHBDD2 was confirmed by luciferase reporter assay. We examined the protein levels of RHBDD2, P-gP, MRP1, cleaved caspase-3, and E-cadherin through western blot analysis. Moreover, we generated xenograft tumors by injecting stably transfected HeLa/DDP cells into mice to compare their tumorigenesis capacity.

RESULTS

We observed downregulation of miR-4739 and upregulation of RHBDD2 in DDP-resistant CC tissues and cell lines. MiR-4739 was shown to directly bind to RHBDD2 gene sequences to repress RHBDD2 expression in HeLa/DDP and SiHa/DDP cells. Our in vitro and in vivo experiments demonstrated that overexpressing miR-4739 overcame DDP resistance in CC cells by targeting RHBDD2. Furthermore, RHBDD2 overexpression reversed the effects of miR-4739 mimics on drug-resistance-related proteins (P-gP and MRP1) and the expression of cleaved caspase-3 and E-cadherin in HeLa/DDP cells.

CONCLUSIONS

In summary, our study revealed that miR-4739 can reverse DDP resistance by modulating RHBDD2 in CC cells.

Pemigatinib, a selective FGFR inhibitor overcomes ABCB1-mediated multidrug resistance in cancer cells

P: -glycoprotein (P-gp/ABCB1) overexpression is one of the primary causes of multidrug resistance (MDR). Therefore, it is crucial to discover effective pharmaceuticals to combat multidrug resistance mediated by ABCB1. Pemigatinib is a selective the fibroblast growth factor receptor (FGFR) inhibitor that is used to treat a variety of solid tumors, Clinical Trials for Urothelial Carcinoma (NCT02872714) completed its research on Pemigatinib. This study aimed to determine whether Pemigatinib can reverse ABCB1-mediated multidrug resistance, as well as its mechanism of action. Pemigatinib substantially reversed ABCB1-mediated multidrug resistance, as determined by a CCK8 assay, and immunofluorescence experiments revealed that Pemigatinib had no effect on the intracellular localization of ABCB1. Pemigatinib was discovered to increase intracellular drug accumulation, thereby reversing multidrug resistance. In addition, Docking analysis revealed that Pemigatinib and ABCB1 have a high affinity for one another. This study concludes that Pemigatinib is capable of reversing the multidrug resistance mediated by ABCB1, offering ideas and references for the clinical application of Pemigatinib.

Overexpression of ABCB1 confers resistance to FLT3 inhibitor FN-1501 in cancer cells: in vitro and in vivo characterization

FN-1501 is a potent FLT3 inhibitor with antitumor activity. A phase 1 trial of FN-1501 monotherapy in patients with advanced solid tumors and R/R AML is in progress. Since one of the primary causes of multidrug resistance (MDR) is the overexpression of ATP-binding cassette superfamily B member 1 (ABCB1), the objective of this study was to investigate the potential relationship between FN-1501 and the ABCB1 transporter. We found ABCB1 overexpressing-cancer cells conferred FN-1501 resistance, which could be reversed by an ABCB1 inhibitor. Molecular docking study revealed that FN-1501 docked the ligand binding site with an affinity score of -9.77 kcal/mol, denoting a strong interaction between FN-1501 and ABCB1. Additionally, the ABCB1 ATPase assay indicated that FN-1501 could significantly stimulate ABCB1 ATPase activity. Furthermore, we observed a similar trend of ABCB1-facilated FN-1501 resistance in tumor-bearing mice model. In sum, we demonstrate that FN-1501 is a substrate of ABCB1 transporter from both in vivo and in vitro studies. Therefore, our findings provide new insight on the mechanism of chemoresistance due to ABCB1 overexpression.

Enhancing Paclitaxel Efficacy with Piperine-Paclitaxel Albumin Nanoparticles in Multidrug-Resistant Triple-Negative Breast Cancer by Inhibiting P-Glycoprotein

Triple-negative breast cancer (TNBC) is a highly aggressive disease with rapid progression and poor prognosis due to multidrug resistance (MDR). Piperine (PIP) shows promise as a P-gp inhibitor, capable of sensitizing chemotherapeutic drugs and exhibiting antitumor properties. This study explores the inhibitory mechanism of PIP on P-glycoprotein (P-gp) and its capacity to enhance the sensitivity of paclitaxel (PTX). We subsequently evaluated the efficacy and safety of albumin nanoparticles that co-encapsulate PTX and PIP (PP@AN). The results demonstrated that PIP enhanced the accumulation of PTX intracellularly, as determined with HPLC/MS/MS analysis. PIP was also found to increase cell sensitivity to PTX. Furthermore, we explored the inhibitory mechanism of PIP on P-gp, utilizing molecular docking simulations, RT-qPCR, and Western blot analysis. PIP appears to compete with the active paclitaxel binding site on P-gp, affecting ATPase activity and downregulating the MDR1 gene and P-gp expression. In summary, PIP could inhibit P-gp and act as a sensitizer in the treatment of TNBC with PTX. Moreover, stable and uniform PP@AN was successfully formulated, resulting in a significant increase in drug accumulation within cells as well as the downregulation of P-gp in tumors at the optimal ratio (PTX:PIP = 1:2). This led to an improvement in the antitumor effect in vivo while also reducing hepatotoxicity and hemototoxicity following chemotherapy. This study comprehensively investigated PIP's inhibitory effect and mechanism on P-gp. We present a new approach for co-delivering PIP and PTX using albumin nanoparticles, which reduced toxicity and improved therapeutic efficacy both in vivo and in vitro.

Increasing Chemotherapeutic Efficacy Using pH-Modulating and Doxorubicin-Releasing Injectable Chitosan-Poly(ethylene glycol) Hydrogels

Modulation of pH is crucial to maintaining the chemical homeostasis of biological environments. The irregular metabolic pathways exhibited by cancer cells result in the production of acidic byproducts that are excreted and accumulate in the extracellular tumor microenvironment, reducing the pH. As a consequence of the lower pH in tumors, cancer cells increase the expression of metastatic phenotypes and chemotherapeutic resistance. A significant limitation in current cancer therapies is the inability to locally deliver chemotherapeutics, leading to significant damage to healthy cells in systemic administration. To overcome these challenges, we present an injectable chitosan-poly(ethylene glycol) hydrogel that is dual-loaded with doxorubicin and sodium bicarbonate providing alkaline buffering of extracellular acidity and simultaneous chemotherapeutic delivery to increase chemotherapeutic efficacy. We conducted in vitro studies of weak base chemotherapeutic and alkaline buffer release from the hydrogel. The release of doxorubicin from hydrogels increased in a low-pH environment and was dependent on the encapsulated sodium bicarbonate concentration. We investigated the influence of pH on the doxorubicin efficacy and viability of MCF-7 and MDA-MB-231 breast cancer cell lines. The results show a 2- to 3-fold increase in IC50 values from neutral pH to low pH, showing decreased cancer cell viability at neutral pH as compared to acidic pH. The IC50 results were shown to correlate with a decrease in intracellular uptake of doxorubicin at low pH. The proposed hydrogels were confirmed to be nontoxic to healthy MCF-10A mammary epithelial cells. Rheological studies were performed to verify that the dual-loaded hydrogels were injectable. The mechanical and release properties of the hydrogels were maintained after extended storage. The chemotherapeutic activity of doxorubicin was evaluated in the presence of the proposed pH-regulating hydrogels. The findings suggest a promising nontoxic, biodegradable hydrogel buffer delivery system that can achieve two simultaneous important goals of local acidosis neutralization and chemotherapeutic release.

Albumin pre-opsonized membrane-active iPep nanomedicine potentiates chemo to immunotherapy of cancer

Chemotherapy-conjugated immunotherapy in clinical oncology conceptually resembles the combined effects of cytoreduction and immunostimulation in membrane targeted cell killings mediated by pore-forming proteins or host defense peptides. Of the similar concept, targeting cancer cell membrane using membrane active peptides is a hopeful therapeutic modality but had long been hindered from in vivo application. Here we report an enabling strategy of pre-opsonizing a membrane penetrating Ir-complexed octa-arginine peptide (iPep) with serum albumin via intrinsic amphipathicity-driven bimodal interactions into nanoparticles (NP). We found that NP triggered stress-mediated 4T1 cell oncosis which induced potent immunological activation, surpassing several well-known immunogenic medicines. Vested with albumin-enhanced in vivo tumor targeting specificity and pharmacokinetic properties, NP showed combined chemo to immunotherapies of s. c. tumors in mice, with decreased percentages of MDSC, Treg, M2-like macrophage and improved infiltration of CTLs in tumor site, caused complete regression of 4T1 and CT26 tumors, outperforming clinical medicines. In a challenging orthotopic breast cancer model, boost i. v. injections of NP acted as in situ tumor vaccine that drastically enhanced 4T1-specific cellular and humoral immunities to reverse disease progression. Thus, with combined effects of direct cytoreduction, immune activation and tumor vaccine, iPep-NP presents the promise and potential of a new modality of cancer medicine.

In Vivo Investigation of Supportive Immunotherapeutic Combination of Bifidobacterium infantis 35624 and Doxorubicin in Murine Breast Cancer

The aim of the study is to investigate the anti-tumor effect of Bifidobacterium infantis 35624 in a xenograft model in BALB/c mice injected with 4T1 cells as a support for chemotherapeutic treatments of doxorubicin in vivo. The MTT assay was used to determine the cytotoxicity of doxorubicin against cancer cells, and apoptosis was analyzed by using flow cytometry. 4T1 cells (2 × 104 cells/mouse) were injected to BALB/c mice, and mice were fed with/without gavage B. infantis milk (108 CFU/mL) for 14 days and treated with doxorubicin on 5th and 10th days. The weights of the mice were recorded during the study, and the tumor sizes were measured by caliper at the 14th day. CD8 + T cell response was analyzed by using flow cytometer, and the results were compared to control and tumor control groups. The IC50 value for doxorubicin on 4T1 cell lines was determined as 0.053 ± 0.012 µg/mL. The apoptotic effect of doxorubicin at IC50 concentration was determined as 82.3% of cells to late apoptosis, 3.6% of cells to pro-apoptosis, and 6.2% of cells to necrosis. The treatment of doxorubicin, B. infantis milk, and the combination of them inhibited the tumor volumes by 55.50%, 40.69%, and 75.95%, respectively. B. infantis administration significantly enhanced the PHA-induced splenocyte proliferation (P < 0.05). It was shown that IFN-γ was effective in tumor growth and regression of metastasis. Consequently, the combination of B. infantis milk and doxorubicin showed the best anti-tumor effect.

Therapeutic Effects of Plant Extracts of Anoectochilus roxburghii on Side Effects of Chemotherapy in BALB/c Breast Cancer Mice

Breast cancer is the most common cancer in women, and chemotherapy is an effective treatment. However, chemotherapy often causes adverse side effects such as cardiotoxicity, myelosuppression, immunodeficiency, and osteoporosis. Our study focused on the alleviating effects of Anoectochilus roxburghii extracts (AREs) on the adverse side effects of chemotherapy in mice with breast cancer. We individually evaluated the antioxidant capacity and cytotoxicity of the AREs using DPPH and MTT assays. We also examined the effects of the AREs on intracellular F-actin, reactive oxygen species (ROS), and the mitochondrial membrane potential (MMP) of 4T1 cancer cells before and after doxorubicin (DOX) treatment. Our results showed that ARE treatment enhanced the effects of DOX chemotherapy by promoting cell morphology damage, oxidative stress, and ROS generation, as well as by reducing MMP in the 4T1 breast cancer cells. By using BALB/c mice with breast cancer with DOX treatment, our results showed that the DOX treatment reduced body weight, blood pressure, and heart rate and induced myelosuppression, immunodeficiency, cardiotoxicity, and osteoporosis. After oral ARE treatment of BALB/c mice with breast cancer, the chemotherapeutic effects of DOX were enhanced, and the adverse side effects of DOX chemotherapy were alleviated. Based on the above results, we suggest that AREs can be used as an adjuvant reliever to DOX chemotherapy in BALB/c mice with breast cancer.

Beta-blockade enhances anthracycline control of metastasis in triple-negative breast cancer

Beta-adrenergic blockade has been associated with improved cancer survival in patients with triple-negative breast cancer (TNBC), but the mechanisms of these effects remain unclear. In clinical epidemiological analyses, we identified a relationship between beta-blocker use and anthracycline chemotherapy in protecting against TNBC progression, disease recurrence, and mortality. We recapitulated the effect of beta-blockade on anthracycline efficacy in xenograft mouse models of TNBC. In metastatic 4T1.2 and MDA-MB-231 mouse models of TNBC, beta-blockade improved the efficacy of the anthracycline doxorubicin by reducing metastatic development. We found that anthracycline chemotherapy alone, in the absence of beta-blockade, increased sympathetic nerve fiber activity and norepinephrine concentration in mammary tumors through the induction of nerve growth factor (NGF) by tumor cells. Moreover, using preclinical models and clinical samples, we found that anthracycline chemotherapy up-regulated β₂-adrenoceptor expression and amplified receptor signaling in tumor cells. Neurotoxin inhibition of sympathetic neural signaling in mammary tumors using 6-hydroxydopamine or genetic deletion of NGF or β₂-adrenoceptor in tumor cells enhanced the therapeutic effect of anthracycline chemotherapy by reducing metastasis in xenograft mouse models. These findings reveal a neuromodulatory effect of anthracycline chemotherapy that undermines its potential therapeutic impact, which can be overcome by inhibiting β₂-adrenergic signaling in the tumor microenvironment. Supplementing anthracycline chemotherapy with adjunctive β₂-adrenergic antagonists represents a potential therapeutic strategy for enhancing the clinical management of TNBC.

Glycolipid-peptide conjugate vaccines elicit CD8+ T-cell responses and prevent breast cancer metastasis

Objectives

Metastasis is the principal cause of breast cancer mortality. Vaccines targeting breast cancer antigens have yet to demonstrate clinical efficacy, and there remains an unmet need for safe and effective treatment to reduce the risk of metastasis, particularly for people with triple-negative breast cancer (TNBC). Certain glycolipids can act as vaccine adjuvants by specifically stimulating natural killer T (NKT) cells to provide a universal form of T-cell help.

Methods

We designed and made a series of conjugate vaccines comprising a prodrug of the NKT cell-activating glycolipid α-galactosylceramide covalently linked to tumor-expressed peptides, and assessed these using E0771- and 4T1-based breast cancer models in vivo. We employed peptides from the model antigen ovalbumin and from clinically relevant breast cancer antigens HER2 and NY-ESO-1.

Results

Glycolipid-peptide conjugate vaccines that activate NKT cells led to antigen-presenting cell activation, induced inflammatory cytokines, and, compared with peptide alone or admixed peptide and α-galactosylceramide, specifically enhanced CD8⁺ T-cell responses against tumor-associated peptides. Primary tumor growth was delayed by vaccination in all tumor models. Using 4T1-based cell lines expressing HER2 or NY-ESO-1, a single administration of the relevant conjugate vaccine prevented tumor colonisation of the lung following intravenous inoculation of tumor cells or spontaneous metastasis from breast, respectively.

Conclusion

Glycolipid-peptide conjugate vaccines that activate NKT cells prevent lung metastasis in breast cancer models and warrant investigation as adjuvant therapies for high-risk breast cancer.

Involvement of the NF-κB and PI3K/Akt/mTOR pathways in cell death triggered by stypoldione, an o-quinone isolated from the brown algae Stypopodium zonale

Multiple myeloma (MM) is a clonal plasma cell malignancy that remains incurable to date. Thus, the aims of this study were to evaluate the involvement of the NF-κB and PI3K/Akt/mTOR pathways in the cytotoxicity of stypoldione, an o-quinone isolated from the brown algae Stypopodium zonale, in MM cells (MM1.S). The cytotoxic effect was evaluated in MM1.S cells and peripheral blood mononuclear cells (PBMCs) by MTT assay. The stypoldione reduced the cell viability of MM1.S cells in a concentration and time-dependent manner (IC50 in MM.1S from 2.55 to 5.38 μM). However, it was also cytotoxic to PBMCs, but at a lower range. Additionally, no significant hemolysis was observed even at concentration up to 10 times the IC50 . Apoptotic cell death was confirmed by cell morphology and Annexin V-FITC assay. Stypoldione induced intrinsic and extrinsic apoptosis by increasing FasR expression and reactive oxygen species (ROS) production, inverting the Bax/Bcl-2 ratio, and inducing ΔΨm loss, which resulted in AIF release and caspase-3 activation. It also increased Ki-67 and survivin expression and inhibited the NF-κB and PI3K/Akt/mTOR pathways. These results suggest that stypoldione is a good candidate for the development of new drugs for MM treatment.

Iron Promotes Cardiac Doxorubicin Retention and Toxicity Through Downregulation of the Mitochondrial Exporter ABCB8

In several cancers, the efflux and resistance against doxorubicin (DOX), an effective anticancer drug, are associated with cellular iron deficiency and overexpression of the mitochondrial exporter ABCB8. Conversely, decreased ABCB8 expression and disrupted iron homeostasis in the heart have been implicated in DOX-associated cardiotoxicity. While studies have demonstrated that altered iron status can modulate the susceptibility to DOX cardiotoxicity, the exact molecular mechanisms have not been clearly understood. Here, we hypothesized that iron stores influence cardiac ABCB8 expression and consequently cardiac retention and toxicity of DOX. First, we found that ABCB8 deficiency in cardiomyocytes decreased DOX efflux, increased DOX-induced toxicity, and decreased cell viability. Conversely, intracellular DOX retention and toxicity were ameliorated by ABCB8 overexpression. To determine if altered cardiac iron status modifies ABCB8 expression, we treated cardiomyocytes with high iron or iron chelators. Western blot and qPCR analyses revealed that ABCB8 levels were decreased in iron overload and increased in iron deficiency. Subsequently, DOX retention and toxicity were increased in cardiomyocytes with iron overload, whereas iron deficiency ameliorated these effects. Next, we validated our results using a mouse model of hereditary hemochromatosis (HH), a genetic iron overload disorder. HH mice exhibited decreased ABCB8 expression and increased DOX retention and toxicity. These changes were abolished by the treatment of HH mice with a low-iron diet. Finally, cardiac-specific overexpression of ABCB8 in HH mice prevented cardiac DOX accumulation and abrogated DOX-induced cardiotoxicity without altering iron overload in the heart. Together, our results demonstrate that ABCB8 mediates DOX efflux and that iron regulates DOX retention and toxicity by altering cardiac ABCB8 expression. Our study identifies a novel role of iron in DOX-induced cardiotoxicity and suggests potential therapeutic intervention for DOX and anthracycline-based cancer pharmacology.

A comparative study of the effects of crab derived exosomes and doxorubicin in 2 & 3-dimensional in vivo models of breast cancer

INTRODUCTION

Using tissue engineering and modifying the tumor microenvironment, three-dimensional (3D) in vitro and in vivo cancer modeling can be performed with appropriate similarity to native. Exosomes derived from different sources have recently been used in cancer studies due to their anticancer effects. In this study, the effect of crab derived exosomes in 2 & 3-dimensional (2& 3D) in vivo models of breast cancer (BC) were investigated and compared with the doxorubicin (DOX).

METHODS

2D and 3D models of BC were induced using the chitosan/β-glycerol phosphate hydrogel (Ch/β-GP) and 1 × 10⁶ 4T1 cells in the female mice aged 6-8 weeks. 1 mg/ml exosome and 5 mg/kg DOX were injected by intratumoral (IT), intravenous (IV), and intraperitoneal (IP) methods into mice on day 9, 13, and 17 with and without hydrogel as a drug delivery system. After 21 days, the mice were sacrificed, and the tissues (lung, liver, and tumor) were removed. The weight and size of the tumor were measured. Real-time PCR assessed changes of VEGF, Bcl2, and P53 genes expression levels. Nitric oxide (NO) secretion from the cancer 3D model was evaluated by Griess assay.

RESULTS AND CONCLUSION

Based on the results, the size and weight of tumors in treated groups with exosomes and DOX were reduced significantly (P ≤ 0.001, P ≤ 0.002, P ≤ 0.02) in 2D and 3D models. Changes in VEGF, Bcl2 and P53 gene expression levels were less in the 3D model than in the 2D model. Drug delivery with hydrogel increased tumor inhibition compared to drug injection without hydrogel. Decreased NO secretion was observed in all treatment groups compared to the control group (untreated). Crab exosomes showed anti cancer effects on 2&3D models of BC. 3D model of BC showed greater drug resistance than the 2D model after treating with crab derived exosomes and DOX. 3D model of BC mimics native tumor better than 2D and can be used in cancer studies and for drug screening with greater confidence than 2D model. Also, the use of slow release drug delivery system reduced drug resistance in both models.

Antiproliferative, Antiangiogenic, and Antimetastatic Therapy Response by Mangiferin in a Syngeneic Immunocompetent Colorectal Cancer Mouse Model Involves Changes in Mitochondrial Energy Metabolism

In spite of the current advances and achievements in cancer treatments, colorectal cancer (CRC) persists as one of the most prevalent and deadly tumor types in both men and women worldwide. Drug resistance, adverse side effects and high rate of angiogenesis, metastasis and tumor relapse remain one of the greatest challenges in long-term management of CRC and urges need for new leads of anticancer drugs. We demonstrate that CRC treatment with the phytopharmaceutical mangiferin (MGF), a glucosylxanthone present in Mango tree stem bark and leaves (Mangifera Indica L.), induces dose-dependent tumor regression and decreases lung metastasis in a syngeneic immunocompetent allograft mouse model of murine CT26 colon carcinoma, which increases overall survival of mice. Antimetastatic and antiangiogenic MGF effects could be further validated in a wound healing in vitro model in human HT29 cells and in a matrigel plug implant mouse model. Interestingly, transcriptome pathway enrichment analysis demonstrates that MGF inhibits tumor growth, metastasis and angiogenesis by multi-targeting of mitochondrial oxidoreductase and fatty acid β-oxidation metabolism, PPAR, SIRT, NFκB, Stat3, HIF, Wnt and GP6 signaling pathways. MGF effects on fatty acid β-oxidation metabolism and carnitine palmitoyltransferase 1 (CPT1) protein expression could be further confirmed in vitro in human HT29 colon cells. In conclusion, antitumor, antiangiogenic and antimetastatic effects of MGF treatment hold promise to reduce adverse toxicity and to mitigate therapeutic outcome of colorectal cancer treatment by targeting mitochondrial energy metabolism in the tumor microenvironment.

Acquired Drug Resistance Enhances Imidazoquinoline Efflux by P-Glycoprotein

Multidrug-Resistant (MDR) cancers attenuate chemotherapeutic efficacy through drug efflux, a process that transports drugs from within a cell to the extracellular space via ABC (ATP-Binding Cassette) transporters, including P-glycoprotein 1 (P-gp or ABCB1/MDR1). Conversely, Toll-Like Receptor (TLR) agonist immunotherapies modulate activity of tumor-infiltrating immune cells in local proximity to cancer cells and could, therefore, benefit from the enhanced drug efflux in MDR cancers. However, the effect of acquired drug resistance on TLR agonist efflux is largely unknown. We begin to address this by investigating P-gp mediated efflux of TLR 7/8 agonists. First, we used functionalized liposomes to determine that imidazoquinoline TLR agonists Imiquimod, Resiquimod, and Gardiquimod are substrates for P-gp. Interestingly, the least potent imidazoquinoline (Imiquimod) was the best P-gp substrate. Next, we compared imidazoquinoline efflux in MDR cancer cell lines with enhanced P-gp expression relative to parent cancer cell lines. Using P-gp competitive substrates and inhibitors, we observed that imidazoquinoline efflux occurs through P-gp and, for Imiquimod, is enhanced as a consequence of acquired drug resistance. This suggests that enhancing efflux susceptibility could be an important consideration in the rational design of next generation immunotherapies that modulate activity of tumor-infiltrating immune cells.

Circadian Influences on Chemotherapy Efficacy in a Mouse Model of Brain Metastases of Breast Cancer

Chemotherapy is more effective in the treatment of peripheral tumors than brain metastases, likely reflecting the reduced ability of chemotherapy to cross the blood-brain barrier (BBB) and blood-tumor barrier at efficacious concentrations. Recent studies demonstrate circadian regulation of the BBB. Thus, we predicted that optimally timed chemotherapy would increase anti-tumor efficacy in a model of brain metastases of breast cancer (BMBC). First, we characterized novel daily alterations in BBB permeability to a commonly used chemotherapeutic, 14C-paclitaxel, within BMBC following injections given at four time points across the day. Peak and trough 14C-paclitaxel concentrations within BMBC occurred during the mid-dark phase and at the beginning of the light phase, respectively. Notably, chemotherapy injections during the dark phase increased cell death within BMBC and delayed onset of neurological symptoms relative to injections during the light phase. These data provide strong evidence for the beneficial effects of chrono-chemotherapy for the treatment of BMBC.

Intracellular Water Lifetime as a Tumor Biomarker to Monitor Doxorubicin Treatment via FFC-Relaxometry in a Breast Cancer Model

This study aims to explore whether the water exchange rate constants in tumor cells can act as a hallmark of pathology status and a reporter of therapeutic outcomes. It has been shown, using 4T1 cell cultures and murine allografts, that an early assessment of the therapeutic effect of doxorubicin can be detected through changes in the cellular water efflux rate constant kio. The latter has been estimated by analyzing the magnetization recovery curve in standard NMR T1 measurements when there is a marked difference in the proton relaxation rate constants (R1) between the intra- and the extra-cellular compartments. In cellular studies, T1 measurements were carried out on a relaxometer working at 0.5 T, and the required difference in R1 between the two compartments was achieved via the addition of a paramagnetic agent into the extracellular compartment. For in-vivo experiments, the large difference in the R1 values of the two-compartments was achieved when the T1 measurements were carried out at low magnetic field strengths. This task was accomplished using a Fast Field Cycling (FFC) relaxometer that was properly modified to host a mouse in its probe head. The decrease in kio upon the administration of doxorubicin is the result of the decreased activity of Na+/K+-ATPase, as shown in an independent test on the cellular uptake of Rb ions. The results reported herein suggest that kio can be considered a non-invasive, early and predictive biomarker for the identification of responsive patients immediately from the first doxorubicin treatment.

piR-39980 mediates doxorubicin resistance in fibrosarcoma by regulating drug accumulation and DNA repair

Resistance to doxorubicin (DOX) is an obstacle to successful sarcoma treatment and a cause of tumor relapse, with the underlying molecular mechanism still unknown. PIWI-interacting RNAs (piRNAs) have been shown to enhance patient outcomes in cancers. However, there are few or no reports on piRNAs affecting chemotherapy in cancers, including fibrosarcoma. The current study aims to investigate the relationship between piR-39980 and DOX resistance and the underlying mechanisms. We reveal that piR-39980 is less expressed in DOX-resistant HT1080 (HT1080/DOX) fibrosarcoma cells. Our results show that inhibition of piR-39980 in parental HT1080 cells induces DOX resistance by attenuating intracellular DOX accumulation, DOX-induced apoptosis, and anti-proliferative effects. Its overexpression in HT1080/DOX cells, on the other hand, increases DOX sensitivity by promoting intracellular DOX accumulation, DNA damage, and apoptosis. The dual-luciferase reporter assay indicates that piR-39980 negatively regulates RRM2 and CYP1A2 via direct binding to their 3'UTRs. Furthermore, overexpressing RRM2 induces DOX resistance of HT1080 cells by rescuing DOX-induced DNA damage by promoting DNA repair, whereas CYP1A2 confers resistance by decreasing intracellular DOX accumulation, which piR-39980 restores. This study reveals that piR-39980 could reduce fibrosarcoma resistance to DOX by modulating RRM2 and CYP1A2, implying that piRNA can be used in combination with DOX.

The Large GTPase, GBP-2, Regulates Rho Family GTPases to Inhibit Migration and Invadosome Formation in Breast Cancer Cells

Simple Summary

Too many women still die of breast cancer each year. Those breast cancers that kill are those with cells that have migrated away from the primary tumor in the breast and established new tumors at other sites in the body. These tumors are not reached when the original tumor in the breast is removed. This study was designed to determine why some breast cancers move away from their primary tumor and others do not. We have identified a protein that inhibits this movement. Understanding this finding may provide us with ways to inhibit tumor cell movement in patients.

Abstract

Breast cancer is the most common cancer in women. Despite advances in early detection and treatment, it is predicted that over 43,000 women will die of breast cancer in 2021. To lower this number, more information about the molecular players in breast cancer are needed. Guanylate-Binding Protein-2 has been correlated with better prognosis in breast cancer. In this study, we asked if the expression of GBP-2 in breast cancer merely provided a biomarker for improved prognosis or whether it actually contributed to improving outcome. To answer this, the 4T1 model of murine breast cancer was used. 4T1 cells themselves are highly aggressive and highly metastatic, while 67NR cells, isolated from the same tumor, do not leave the primary site. The expression of GBP-2 was examined in the two cell lines and found to be inversely correlated with aggressiveness/metastasis. Proliferation, migration, and invadosome formation were analyzed after altering the expression levels of GBP-2. Our experiments show that GBP-2 does not alter the proliferation of these cells but inhibits migration and invadosome formation downstream of regulation of Rho GTPases. Together these data demonstrate that GBP-2 is responsible for cell autonomous activities that make breast cancer cells less aggressive.

Iron oxide nanoparticle targeted chemo-immunotherapy for triple negative breast cancer

Triple negative breast cancer is difficult to treat effectively, due to its aggressiveness, drug resistance, and lack of the receptors required for hormonal therapy, particularly at the metastatic stage. Here, we report the development and evaluation of a multifunctional nanoparticle formulation containing an iron oxide core that can deliver doxorubicin, a cytotoxic agent, and polyinosinic:polycytidylic acid (Poly IC), a TLR3 agonist, in a targeted and simultaneous fashion to both breast cancer and dendritic cells. Endoglin-binding peptide (EBP) is used to target both TNBC cells and vasculature epithelia. The nanoparticle demonstrates favorable physicochemical properties and a tumor-specific targeting profile. The nanoparticle induces tumor apoptosis through multiple mechanisms including direct tumor cell killing, dendritic cell-initiated innate and T cell-mediated adaptive immune responses. The nanoparticle markedly inhibits tumor growth and metastasis and substantially extends survival in an aggressive and drug-resistant metastatic mouse model of triple negative breast cancer (TNBC). This study points to a promising platform that may substantially improve the therapeutic efficacy for treating metastatic TNBC.

Asiatic acid inhibits angiogenesis and vascular permeability through the VEGF/VEGFR2 signaling pathway to inhibit the growth and metastasis of breast cancer in mice

Anti-angiogenic medicines have been evaluated as anticancer therapies, however, their use remains limited in clinical practice due to associated adverse effects. Asiatic acid (AA) is known to have broad-spectrum anticancer properties, however, its effects on angiogenesis in breast cancer remain to be fully established. In this study, we analyzed the inhibitory effects of AA on angiogenesis using human umbilical vein endothelial cells (HUVECs) cultured in vitro and on the growth and metastasis of a subcutaneous breast cancer 4T1 tumor model and a lung metastasis model in vivo. AA significantly inhibited HUVECs proliferation, migration, and tube formation in vitro. In vivo, AA significantly reduced the microvascular density and blood vascular permeability in breast cancer tumors and inhibited growth and lung metastasis. AA inhibited the expression of vascular endothelial growth factor (VEGF) in HUVECs and subsequently downregulated the phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2) and its downstream target proteins including ERK1/2, Src, and FAK. These results indicate that AA significantly inhibits angiogenesis and blood vessel permeability through the VEGF/VEGFR2 signal axis to inhibit the growth and metastasis of breast cancer. Our data strongly demonstrate the potential applications of AA in the treatment of breast cancer.

Visualization of the cancer cell cycle by tissue-clearing technology using the Fucci reporter system

Tissue-clearing technology is an emerging imaging technique currently utilized not only in neuroscience research but also in cancer research. In our previous reports, tissue-clearing methods were used for the detection of metastatic tumors. Here, we showed that the cell cycles of primary and metastatic tumors were visualized by tissue-clearing methods using a reporter system. First, we established cancer cell lines stably expressing fluorescent ubiquitination-based cell cycle indicator (Fucci) reporter with widely used cancer cell lines A549 and 4T1. Fluorescence patterns of the Fucci reporter were investigated in various tumor inoculation models in mice. Interestingly, fluorescence patterns of the Fucci reporter of tumor colonies were different between various organs, and even among colonies in the same organs. The effects of antitumor drugs were also evaluated using these Fucci reporter cells. Of the three antitumor drugs studied, 5-fluorouracil treatment on 4T1-Fucci cells resulted in characteristic fluorescent patterns by the induction of G2 /M arrest both in vitro and in vivo. Thus, the combination of a tissue-clearing method with the Fucci reporter is useful for analyzing the mechanisms of cancer metastasis and drug resistance.

Eupatorin Suppressed Tumor Progression and Enhanced Immunity in a 4T1 Murine Breast Cancer Model

Eupatorin is a polymethoxy flavone extracted from Orthosiphon stamineus and was reported to exhibit cytotoxic effects on several cancer cell lines. However, its effect as an anti-breast cancer agent in vivo has yet to be determined. This study aims to elucidate the potential of eupatorin as an anti-breast cancer agent in vivo using 4T1 challenged BALB/c mice model. In this article, BALB/c mice (20-22 g) challenged with 4T1 cells were treated with 5 mg/kg or 20 mg/kg eupatorin, while the untreated and healthy mice were fed with olive oil (vehicle) via oral gavage. After 28 days of experiment, the mice were sacrificed and blood was collected for serum cytokine assay, while tumors were harvested to extract RNA and protein for gene expression assay and hematoxylin-eosin staining. Organs such as spleen and lung were harvested for immune suppression and clonogenic assay, respectively. Eupatorin (20 mg/kg) was effective in delaying the tumor development and reducing metastasis to the lung compared with the untreated mice. Eupatorin (20 mg/kg) also enhanced the immunity as the population of NK1.1+ and CD8+ in the splenocytes and the serum interferon-γ were increased. Concurrently, eupatorin treatment also has downregulated the expression of pro-inflammatory and metastatic related genes (IL-1β. MMP9, TNF-α, and NF-κB). Thus, this study demonstrated that eupatorin at the highest dosage of 20 mg/kg body weight was effective in delaying the 4T1-induced breast tumor growth in the animal model.

Essential Oils, Pituranthos chloranthus and Teucrium ramosissimum, Chemosensitize Resistant Human Uterine Sarcoma MES-SA/Dx5 Cells to Doxorubicin by Inducing Apoptosis and Targeting P-Glycoprotein

The multidrug resistance phenotype is a global phenomenon and causes chemotherapy failure in various cancers, such as in uterine sarcomas that have a high mortality rate. To overcome this phenotype, there is growing research interest in developing new treatment strategies. In this study, we highlight the potential of two essential oils from the Apiaceae family, Pituranthos chloranthus (PC) and Teucrium ramosissimum Desf. (TR), to act as chemopreventive and chemosensitizing agents against two uterine sarcoma cell lines, MES-SA and P-gp-overexpressing MES-SA/Dx5 cells. We found that PC and TR were able to inhibit the cell viability of sensitive MES-SA and resistant MES-SA/Dx5 cells by a slight modulation of the cell cycle and its regulators, but also through a significant induction of apoptosis. The molecular mechanism involved both caspase pathways associated with an overproduction of reactive oxygen species (ROS) and mitochondrial membrane depolarization. Very interestingly, the combination of doxorubicin with PC or TR induced a synergism to increase cell death in resistant MES-SA/Dx5 cells and, subsequently, had the benefit of decreasing the resistance index to doxorubicin. These synergistic effects were reinforced by a decrease in P-gp expression and its P-gp adenosine triphosphatase (ATPase) activity, which subsequently led to intracellular doxorubicin accumulation in resistant sarcoma cells.

Bioguided Fractionation of Local Plants against Matrix Metalloproteinase9 and Its Cytotoxicity against Breast Cancer Cell Models: In Silico and In Vitro Study (Part II)

In our previous work, the partitions (1 mg/mL) of Ageratum conyzoides (AC) aerial parts and Ixora coccinea (IC) leaves showed inhibitions of 94% and 96%, respectively, whereas their fractions showed IC₅₀ 43 and 116 µg/mL, respectively, toward Matrix Metalloproteinase9 (MMP9), an enzyme that catalyzes a proteolysis of extracellular matrix. In this present study, we performed IC₅₀ determinations for AC n-hexane, IC n-hexane, and IC ethylacetate partitions, followed by the cytotoxicity study of individual partitions against MDA-MB-231, 4T1, T47D, MCF7, and Vero cell lines. Successive fractionations from AC n-hexane and IC ethylacetate partitions led to the isolation of two compounds, oxytetracycline (OTC) and dioctyl phthalate (DOP). The result showed that AC n-hexane, IC n-hexane, and IC ethylacetate partitions inhibit MMP9 with their respective IC₅₀ as follows: 246.1 µg/mL, 5.66 µg/mL, and 2.75 × 10⁻² µg/mL. Toward MDA-MB-231, 4T1, T47D, and MCF7, AC n-hexane demonstrated IC₅₀ 2.05, 265, 109.70, and 2.11 µg/mL, respectively, whereas IC ethylacetate showed IC₅₀ 1.92, 57.5, 371.5, and 2.01 µg/mL, respectively. The inhibitions toward MMP9 by OTC were indicated by its IC₅₀ 18.69 µM, whereas DOP was inactive. A molecular docking study suggested that OTC prefers to bind to PEX9 rather than its catalytic domain. Against 4T1, OTC showed inhibition with IC₅₀ 414.20 µM. In conclusion, this study furtherly supports the previous finding that AC and IC are two herbals with potential to be developed as triple-negative anti-breast cancer agents.

Albumin-stabilized layered double hydroxide nanoparticles synergized combination chemotherapy for colorectal cancer treatment

Combination chemotherapy with two or more complimentary drugs has been widely used for clinical cancer treatment. However, the efficacy and side effects of combination chemotherapy still remain a challenge. Here, we constructed an albumin-stabilized layered double hydroxide nanoparticle (BLDH) system to simultaneously load and deliver two widely used anti-tumor drugs, i.e. 5-fluorouracil (5FU) and albumin-bound PTX (Abraxane, ABX) for colorectal cancer treatment. The cellular uptake test has revealed that 5FU-ABX encapsulated BLDH (BLDH/5FU-ABX) nanoparticles were efficiently internalized by the colorectal cancer cell (HCT-116), synergistically inducing apoptosis of colon cancer cells. The in vivo test has demonstrated that BLDH/5FU-ABX nanomedicine significantly inhibited the tumor growth after three intravenous injections, without any detectable side effects. The enhanced therapeutic effectiveness is attributed to efficient accumulation of BLDH/5FU-ABX at tumor sites and acid-sensitive release of co-loaded drugs. Thus, combination chemotherapy based on BLDH/5FU-ABX nanomedicine would be a new strategy for colorectal cancer treatment.

miR-21 inhibition reverses doxorubicin-resistance and inhibits PC3 human prostate cancer cells proliferation

Many approaches have been examined to reversing multidrug resistance (MDR), but sub-optimal target-based strategies have limited their efficacy. Herein, we investigate microRNA (miR-21) suppression on the doxorubicin (DOX)-sensitisation of the DOX-resistant (PC3/DOX) cell line in prostate cancer (PCa). Expression levels of miR-21, P-glycoprotein (P-gp), MDR-1 and PTEN evaluated in PC3/DOX cancer cells by qRT-PCR and western blot analyses. The cytotoxic effects of transfected of miR-21 were assessed by MTT assay for 72 hr. Rhodamine123 (Rh123) assay was employed to define the activity of P-gp. Apoptosis was detected by Flow cytometry. As expected, miR-21 was expressed highly in PC3/DOX cells (p < 0.05). It was shown that miRNA-21 suppression considerably hindered PC3/DOX cell viability. miR-21 suppression dramatically downregulated P-gp expression and activity in DOX-resistance cells and abolished MDR by an increment of intracellular accumulation of DOX in PC3/DOX cells (p < 0.05). PTEN is a key modulator of the PI3K/Akt/P-gp cascade, which miR-21 suppression led to the upregulation of PTEN and sequentially lower-expression of P-gp that reversed MDR. Also, miR-21 repression enhanced the apoptosis rate of PC3/DOX cells. The findings of this paper contribute to the current understanding of the functions of miR-21 in MDR-reversing in PCa.

A multistage oral delivery system of PTX for improving oral bioavailability and enhancing anticancer efficacy

OBJECTIVE

Bromotetrandrine (W198) was reported as a P-glycoprotein (P-gp) inhibitor. We aimed to prepare oral W198 micelles following by paclitaxel (PTX) micelles (W198/PTX micelles) to improve the clinical application of PTX.

SIGNIFICANCE

The poor water solubility, intestinal permeability, and multidrug resistance (MDR) of PTX can be improved in the multistage oral delivery system.

METHODS

The novel W198/PTX oral micelles were developed by water-bath ultrasound method and were evaluated in vivo and in vitro in 4T1 orthotopic tumor-bearing mice model.

RESULTS

PTX micelles and W198 micelles were prepared to be round and uniform. W198 micelles pre-administrated group showed higher cellular uptake efficiency of PTX on Caco-2 cells and more prominent cytotoxicity compared with W198-untreated group on 4T1 cells. The oral bioavailability of W198/PTX micelles group was nearly 5.7-folds higher than the PTX micelles only group. In addition, W198/PTX micelles showed enhanced anticancer efficacy.

CONCLUSIONS

We established a multistage oral delivery system to improve oral bioavailability and anticancer efficacy of PTX.

Immunoexpression and Prognostic Significance of Multidrug Resistance Markers in Feline Mammary Carcinomas

Feline mammary carcinomas (FMCs) are commonly characterized by high clinical aggressiveness and poor prognosis. FMCs share many features with the corresponding human disease, allowing the comparative investigation of tumour biology and therapeutic strategies, including multidrug resistance (MDR) mechanisms. Although transporting/binding proteins, including permeability glycoprotein (P-gp), lung resistance protein (LRP) and metallothionein (MT), are frequently associated with tumour aggressiveness and unresponsiveness to chemotherapy in human breast cancer, they have not been analysed in FMCs. We investigated the immunoexpression of P-gp, LRP and MT in FMCs and their correlation with clinicopathological parameters and overall survival (OS) time in 46 FMCs, with a median follow-up period of 289 days. These markers were co-expressed in 85% of tumours. P-gp was expressed in 93.4% of FMCs and was positively associated with tumour grade (P = 0.049). While unequivocally observed in all FMCs, LRP immunoexpression did not correlate with any clinicopathological parameters or OS. Expression of MT was significant in triple-negative basal- and normal-like molecular subtypes of FMCs (P = 0.023). The concurrent expression of MDR proteins indicates the potential existence of chemotherapy resistance-related mechanisms in FMCs. The positive association between P-gp and MT immunoexpression and aggressive phenotypes could open new therapeutic and translational strategies for FMCs.

Doxorubicin treatment modulates chemoresistance and affects the cell cycle in two canine mammary tumour cell lines

BACKGROUND

Doxorubicin (DOX) is widely used in both human and veterinary oncology although the onset of multidrug resistance (MDR) in neoplastic cells often leads to chemotherapy failure. Better understanding of the cellular mechanisms that circumvent chemotherapy efficacy is paramount. The aim of this study was to investigate the response of two canine mammary tumour cell lines, CIPp from a primary tumour and CIPm, from its lymph node metastasis, to exposure to EC50(20h) DOX at 12, 24 and 48 h of treatment. We assessed the uptake and subcellular distribution of DOX, the expression and function of P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP), two important MDR mediators. To better understand this phenomenon the effects of DOX on the cell cycle and Ki67 cell proliferation index and the expression of p53 and telomerase reverse transcriptase (TERT) were also evaluated by immunocytochemistry (ICC).

RESULTS

Both cell lines were able to uptake DOX within the nucleus at 3 h treatment while at 48 h DOX was absent from the intracellular compartment (assessed by fluorescence microscope) in all the surviving cells. CIPm, originated from the metastatic tumour, were more efficient in extruding P-gp substrates. By ICC and qRT-PCR an overall increase in both P-gp and BCRP were observed at 48 h of EC50(20h) DOX treatment in both cell lines and were associated with a striking increase in the percentage of p53 and TERT expressing cells by ICC. The cell proliferation fraction was decreased at 48 h in both cell lines and cell cycle analysis showed a DOX-induced arrest in the S phase for CIPp, while CIPm had an increase in cellular death without arrest. Both cells lines were therefore composed by a fraction of cells sensible to DOX that underwent apoptosis/necrosis.

CONCLUSIONS

DOX administration results in interlinked modifications in the cellular population including a substantial effect on the cell cycle, in particular arrest in the S phase for CIPp and the selection of a subpopulation of neoplastic cells bearing MDR phenotype characterized by P-gp and BCRP expression, TERT activation, p53 accumulation and decrease in the proliferating fraction. Important information is given for understanding the dynamic and mechanisms of the onset of drug resistance in a neoplastic cell population.

Red Light-Initiated Cross-Linking of NIR Probes to Cytoplasmic RNA: An Innovative Strategy for Prolonged Imaging and Unexpected Tumor Suppression

Improving the enrichment of drugs or theranostic agents within tumors is very vital to achieve effective cancer diagnosis and therapy while greatly reducing the dosage and damage to normal tissues. Herein, as a proof of concept, we for the first time report a red light-initiated probe-RNA cross-linking (RLIPRC) strategy that can not only robustly promote the accumulation and retention of the probe in the tumor for prolonged imaging but also significantly inhibits the tumor growth. A near-infrared (NIR) fluorescent probe f-CR consisting of a NIR dye (Cyanine 7) as a signal reporter, a cyclic-(arginine-glycine-aspartic acid) (cRGD) peptide for tumor targeting, and a singlet oxygen (¹O₂)-sensitive furan moiety for RNA cross-linking was rationally designed and synthesized. This probe possessed both passive and active tumor targeting abilities and emitted intense NIR/photoacoustic (PA) signals, allowing for specific and sensitive dual-modality imaging of tumors in vivo. Notably, probe f-CR could be specifically and covalently cross-linked to cytoplasmic RNAs via the cycloaddition reaction between furan and adenine, cytosine, or guanine under the oxidation of ¹O₂ generated in situ by irradiation of methylene blue (MB) with 660 nm laser light, which effectively blocks the exocytosis of the probes resulting in enhanced tumor accumulation and retention. More excitingly, for the first time, we revealed that the covalent cross-linking of probe f-CR to cytoplasmic RNAs could induce severe apoptosis of cancer cells leading to remarkable tumor suppression. This study thus represents the first red light-initiated RNA cross-linking system with high potential to improve the diagnostic and therapeutic outcomes of tumors in vivo.

The systemic administration of neural stem cells expressing an inducible and soluble form of growth arrest specific 1 inhibits mammary gland tumor growth and the formation of metastases

BACKGROUND AIMS

Metastasis to different organs is the major cause of death in breast cancer patients. The poor clinical prognosis and lack of successful treatments for metastatic breast cancer patients demand the development of new tumor-selective therapies. Thus, it is necessary to develop treatments capable of releasing therapeutic agents to both primary tumors and metastases that avoid toxic side effects in normal tissue, and neural stem cells are an attractive vehicle for tracking tumor cells and delivering anti-cancer agents. The authorspreviously demonstrated that a soluble form of growth arrest specific 1 (GAS1) inhibits the growth of triple-negative breast tumors and glioblastoma.

METHODS

In this study, the authors engineered ReNcell CX (EMD Millipore, Temecula, CA, USA) neural progenitor cells to express truncated GAS1 (tGAS1) under a tetracycline/on inducible system using lentiviral vectors.

RESULTS

Here the authors show that treatment with ReNcell-tGAS1 in combination with tetracycline decreased primary tumor growth and inhibited the formation of metastases in tumor-bearing mice by diminishing the phosphorylation of AKT and ERK1/2 in orthotopic mammary gland tumors. Moreover, the authors observed that ReNcell-tGAS1 prolonged the survival of 4T1 tumor-bearing mice.

CONCLUSIONS

These data suggest that the delivery of tGAS1 by ReNcell cells could be an effective adjuvant for the treatment of triple-negative breast cancer.

Probing the Superiority of Diselenium Bond on Docetaxel Dimeric Prodrug Nanoassemblies: Small Roles Taking Big Responsibilities

The current state of chemotherapy is far from satisfaction, restricted by the inefficient drug delivery and the off-target toxicity. Prodrug nanoassemblies are emerging as efficient platforms for chemotherapy. Herein, three docetaxel dimeric prodrugs are designed using diselenide bond, disulfide bond, or dicarbide bond as linkages. Interestingly, diselenide bond-bridged dimeric prodrug can self-assemble into stable nanoparticles with impressive high drug loading (≈70%, w/w). Compared with disulfide bond and dicarbide bond, diselenide bond greatly facilitates the self-assembly of dimeric prodrug, and then improves the colloidal stability, blood circulation time, and antitumor efficacy of prodrug nanoassemblies. Furthermore, the redox-sensitive diselenide bond can specifically respond to the overexpressed reactive oxygen species and glutathione in tumor cells, leading to tumor-specific drug release. Therefore, diselenide bond bridged prodrug nanoassemblies exhibit discriminating cytotoxicity between tumor cells and normal cells, significantly alleviating the systemic toxicity of docetaxel. The present work gains in-depth insight into the impact of diselenide bond on the dimeric prodrug nanoassemblies, and provides promising strategies for the rational design of the high efficiency-low toxicity chemotherapeutical nanomedicines.

Differential Impact of Calcitriol and Its Analogs on Tumor Stroma in Young and Aged Ovariectomized Mice Bearing 4T1 Mammary Gland Cancer

(1) Background: Vitamin D compounds (VDC) are extensively studied in the field of anticancer properties, including breast cancer. Previously, we showed that calcitriol and its analogs (PRI-2191 and PRI-2205) stimulate metastasis in 4T1 murine mammary gland cancer models in young mice, whereas the reverse effect was observed in aged ovariectomized (OVX) mice; (2) Methods: We determined the phenotype of monocytes/macrophages using FACS and examined the expression of selected genes and proteins by Real-Time PCR and ELISA; (3) Results: Activities of VDC are accompanied by an increase in the percentage of Ly6Clow anti-inflammatory monocytes in the spleen of young and a decrease in aged OVX mice. Treatment of young mice with VDC resulted in an increase of CCL2 plasma and tumor concentration and Arg1 in tumor. In later stage of tumor progression the expression of genes related to metastasis in lung tissue was decreased or increased, in old OVX or young mice, respectively; (4) Conclusions: Pro- or anti-metastatic effects of calcitriol and its analogs in young or aged OVX mice, respectively, can be attributed to the differences in the effects of VDC on the tumor microenvironment, as a consequence of differences in the immunity status of young and aged mice.

MicroRNA‑145 promotes the apoptosis of leukemic stem cells and enhances drug‑resistant K562/ADM cell sensitivity to adriamycin via the regulation of ABCE1

Leukemia is a type of cancer which originates in blood-forming tissues. MicroRNAs (miRNAs or miRs) have been shown to be involved leukemogenesis. In the present study, following the gain- and loss-function of miR-145 and ATP-binding cassette sub-family E member 1 (ABCE1) in K562 cells and K562 adriamycin-resistant cells (K562/ADM cells), the levels of multidrug resistance protein 1 (MRP1) and P-glycoprotein (P-gp) were measured. The viability of the K562 cells and K562/ADM cells treated with various concentrations of ADM, and cell sensitivity to ADM were measured. The apoptosis of stem cells was detected. K562/ADM cells were transfected with miR-145 mimic or with miR-145 mimic together with ABCE1 overexpression plasmid to examine the effects of ABCE1 on the sensitivity of K562/ADM cells to ADM. The association between miR-145 and ABCE1/MRP1 was then verified. The dose- and time-dependent effects of ADM on the K562 cells and K562/ADM cells were examined. The K562/ADM cells exhibited a greater resistance to ADM, higher levels of MRP1 and P-gp, and a lower miR-145 expression. The K562/ADM cells and stem cells in which miR-145 was overexpressed exhibited a suppressed cell proliferation, decreased MRP1 and P-gp levels, and an increased apoptotic rate. However, K562 cells with a low expression of miR-145 exhibited an increased cell proliferation, increased levels of MRP1 and P-gp, and a suppressed apoptotic rate. Compared with the overexpression of miR-145, the combination of miR-145 and ABCE1 decreased the sensitivity of drug-resistant K562/ADM cells to ADM. The above-mentioned effects of miR-145 were achieved by targeting ABCE1. Taken together, the findings of the present study demonstrate that the overexpression of miR-145 promotes leukemic stem cell apoptosis and enhances the sensitivity of K562/ADM cells to ADM by inhibiting ABCE1.

Comparing the immunogenicity of glycosidase-directed resiquimod prodrugs mediated by cancer cell metabolism

We have recently developed an enzyme-directed immunostimulant (EDI) prodrug motif, which is metabolized to active immunostimulant by cancer cells and, following drug efflux, activates nearby immune cells, resulting in immunogenicity. In this study, we synthesized several EDI prodrugs featuring an imidazoquinoline immunostimulant resiquimod (a Toll-like receptor 7/8 agonist) covalently modified with glycosidase enzyme-directing groups selected from substrates of β-glucuronidase, α-mannosidase, or β-galactosidase. We compared the glycosidase-dependent immunogenicity elicited by each EDI in RAW-Blue macrophages following conversion to active immunostimulant by complementary glycosidase. At a cellular level, we examined EDI metabolism across three cancer cell lines (B16 melanoma, TC2 prostate, and 4T1 breast cancer). Comparing the relative immunogenicity elicited by each EDI/cancer cell combination, we found that B16 cells produced the highest EDI prodrug immunogenicity, achieving >95% of that elicited by unmodified resiquimod, followed by TC2 and 4T1 cells (40% and 30%, respectively). Immunogenicity elicited was comparable for a given cell type and independent of the glycosidase substrate in the EDIs or differences in functional glycosidase activity between cell lines. Measuring drug efflux of the immunostimulant payload and efflux protein expression revealed that EDI/cancer cell-mediated immunogenicity was governed by efflux potential of the cancer cells. We determined that, following EDI conversion, immunostimulant efflux occurred through both P-glycoprotein-dependent and P-glycoprotein-independent transport mechanisms. Overall, this study highlights the broad ability of EDIs to couple immunogenicity to the metabolism of many cancers that exhibit drug efflux and suggests that designing future generations of EDIs with immunostimulant payloads that are optimized for drug efflux could be particularly beneficial.

In Vitro and In Vivo Efficacy of AZD3965 and Alpha-Cyano-4-Hydroxycinnamic Acid in the Murine 4T1 Breast Tumor Model

Monocarboxylate transporter 1 (MCT1) represents a potential therapeutic target in cancer. The objective of this study was to determine the efficacy of AZD3965 (a specific inhibitor of MCT1) and α-cyano-4-hydroxycinnamic acid (CHC, a nonspecific inhibitor of MCTs) in the murine 4T1 tumor model of triple-negative breast cancer (TNBC). Expression of MCT1 and MCT4 in 4T1 and mouse mammary epithelial cells were determined by Western blot. Inhibition of MCT1-mediated L-lactate uptake and cellular proliferation by AZD3965 and CHC was determined. Mice bearing 4T1 breast tumors were treated with AZD3965 100 mg/kg i.p. twice-daily or CHC 200 mg/kg i.p. once-daily. Tumor growth, metastasis, intra-tumor lactate concentration, immune function, tumor MCT expression, and concentration-effect relationships were determined. AZD3965 and CHC inhibited cell growth and L-lactate uptake in 4T1 cells. AZD3965 treatment resulted in trough plasma and tumor concentrations of 29.1 ± 13.9 and 1670 ± 946 nM, respectively. AZD3965 decreased the tumor proliferation biomarker Ki67 expression, increased intra-tumor lactate concentration, and decreased tumor volume, although tumor weight was not different from untreated controls. CHC had no effect on tumor volume and weight, or intra-tumor lactate concentration. AZD3965 treatment reduced the blood leukocyte count and spleen weight and increased lung metastasis, while CHC did not. These findings indicate AZD3965 is a potent MCT1 inhibitor that accumulates to high concentrations in 4T1 xenograft tumors, where it increases tumor lactate concentrations and produces beneficial effects on markers of TNBC; however, overall effects on tumor growth were minimal and lung metastases increased.

Combining Tumor Microenvironment Modulating Nanoparticles with Doxorubicin to Enhance Chemotherapeutic Efficacy and Boost Antitumor Immunity

BACKGROUND

Tumor microenvironment (TME) and associated multiple factors are found to contribute to the failures in cancer therapies, including chemo- and immunotherapy. Here we report a new multimodal strategy that uses a bioreactive multifunctional hybrid polymer-lipid encapsulated manganese dioxide nanoparticle (PLMD NP) system to remodel the TME, suppress drug resistance factors, reverse immunosuppressive conditions, and enhance chemotherapy efficacy.

METHODS

The influence of PLMD NPs on enhancing cellular uptake in EMT6 mouse breast cancer cells and tumor penetration of doxorubicin (DOX) in EMT6 orthotopic breast tumor mouse model was evaluated using confocal microscopy (n = 3-4). Immunohistochemistry was employed to examine the effect of PLMD NPs on downregulating hypoxia-induced drug resistance proteins and anticancer activity of DOX (n = 3-4). The efficacy of the combination therapy with PLMD NPS and DOX was assessed in murine EMT6 (n = 15-23) and 4T1 (n = 7) orthotopic breast tumor mouse models. Rechallenge and splenocyte transfer were performed to validate the stimulation of adaptive tumor immunity in the surviving mice.

RESULTS

PLMD NPs enhanced intratumoral penetration and efficacy of DOX, and reduced intratumoral expression of P-glycoprotein, p53, and carbonic anhydrase IX by 74.5%, 38.0%, and 58.8% vs saline control, respectively. Combination treatment with PLMD NPs and DOX increased the number of tumor-infiltrated CD8+ T cells and resulted in up to 60.0% complete tumor regression. Of naïve mice (n = 7) that received splenocytes from the PLMD+DOX-treated surviving mice, 57.1% completely suppressed tumor growth whereas 100% of mice that received splenocytes from DOX-treated mice (n = 3) and the control group (n = 7) showed rapid tumor growth.

CONCLUSIONS

The clinically suitable PLMD NPs can effectively downregulate TME-associated drug resistance and immunosuppression. The combination therapy with PLMD NPs and DOX is a multimodal and translational treatment approach for enhancing chemotherapeutic efficacy and boosting antitumor immunity.

Anti-Tumor Efficacy of an Adjuvant Built-In Nanovaccine Based on Ubiquitinated Proteins from Tumor Cells

Background and Aim

We have previously identified ubiquitinated proteins (UPs) from tumor cell lysates as a promising vaccine for cancer immunotherapy in different mouse tumor models. In this study, we aimed at developing a highly efficient therapeutic adjuvant built-in nanovaccine (α-Al₂O₃-UPs) by a simple method, in which UPs from tumor cells could be efficiently and conveniently enriched by α-Al₂O₃ nanoparticles covalently coupled with Vx3 proteins (α-Al₂O₃-CONH-Vx3).

Methods

The α-Al₂O₃ nanoparticles were modified with 4-hydroxybenzoic acid followed by coupling with ubiquitin-binding protein Vx3. It was then used to enrich UPs from 4T1 cell lysate. The stability and the efficiency for the UPs enrichment of α-Al₂O₃-CONH-Vx3 were examined. The ability of α-Al₂O₃-UPs to activate DCs was examined in vitro subsequently. The splenocytes from the vaccinated mice were re-stimulated with inactivated tumor cells, and the IFN-γ secretion was detected by ELISA and flow cytometry. Moreover, the therapeutic efficacy of α-Al₂O₃-UPs, alone and in combination with chemotherapy, was examined in 4T1 tumor-bearing mice.

Results

Our results showed that α-Al₂O₃-UPs were successfully synthesized and abundant UPs from tumor cell lysate were enriched by the new method. In vitro study showed that compared to the physical mixture of α-Al₂O₃ nanoparticles and UPs (α-Al₂O₃+UPs), α-Al₂O₃-UPs stimulation resulted in higher upregulations of CD80, CD86, MHC class I, and MHC class II on DCs, indicating the higher ability of DC activation. Moreover, α-Al₂O₃-UPs elicited a more effective immune response in mice, demonstrated by higher IFN-γ secretion than α-Al₂O₃+UPs. Furthermore, α-Al₂O₃-UPs also exhibited a more potent effect on tumor growth inhibition and survival prolongation in 4T1 tumor-bearing mice. Notably, when in combination with low dose chemotherapy, the anti-tumor effect was further enhanced, rather than using α-Al₂O₃-UPs alone.

Conclusion

This study presents an adjuvant built-in nanovaccine generated by a new simple method that can be potentially applied to cancer immunotherapy and lays the experimental foundation for future clinical application.

Doxorubicin-polyglycerol-nanodiamond conjugates disrupt STAT3/IL-6-mediated reciprocal activation loop between glioblastoma cells and astrocytes

Astrocytes are key stromal components in glioblastoma (GBM) and have complex interactions with the GBM cells (GBC) promoting the survival, progression and therapy resistance of GBM. In this study, we first demonstrated the existence of a reciprocal activation loop mediated by the STAT3/IL-6 signaling between GBC and astrocytes. This loop of reciprocity was found to be initiated by the constitutive activity of STAT3 and downstream expression of IL-6 in the GBC. GBC-derived IL-6 activated STAT3 and thereby upregulated IL-6 expression in the astrocytes. Astrocyte-derived IL-6 acted back on the GBC causing further activation of STAT3 and leading to enhanced downstream events that promote proliferation, migration, invasion and apoptosis resistance of the GBC. Next, we showed that doxorubicin-polyglycerol-nanodiamond conjugates (Nano-DOX), which could be delivered via GBM-associated macrophages, suppressed STAT3 activity in the GBC reducing their IL-6 output to the astrocytes and thereby abolished the astrocytes' feedback activation of the GBC. Moreover, Nano-DOX also suppressed stimulated activation of STAT3 and IL-6 induced by temozolomide, a first-line anti-GBM chemotherapy, resistance to which critically involves STAT3 activation. In conclusion, Nano-DOX could disrupt the STAT3/IL-6-mediated reciprocal activation loop between the GBC and astrocytes. Nano-DOX also provides a novel approach to therapeutic modulation of the GBM microenvironment.

Aptamer-functionalized Hybrid Nanoparticles to Enhance the Delivery of Doxorubicin into Breast Cancer Cells by Silencing P-glycoprotein

OBJECTIVE

The MDR of metastatic breast cancer cells is accompanied by the overexpression of P-gp transporter. This study has been focused to determine whether silencing the expression of P-gp by aptamer-labeled siRNA nanoparticles could enhance the delivery of doxorubicin into breast cancer cells in culture.

METHODOLOGY

The nanoparticle F-31 was prepared using DOTAP, cholesterol, and PLGA, and then incorporating Mal-PEG to facilitate aptamer-binding. The nanoparticles were surface-functionalized with aptamer A6, which targets Her-2 receptors overexpressed on the surface of breast cancer cells.

RESULTS

This study has shown that the uptake of Dox by Dox-resistant 4T1-R is significantly less than Dox-sensitive 4T1-S which is partly attributed to the higher expression of drug-efflux pump P-gp on the surface of the resistant cells. The targeted knockdown of P-gp has been enhanced when the particles carrying P-gp siRNA was labeled with aptamer. Concurrently, the uptake of Dox into the Dox-resistant 4T1-R breast cancer cells has increased significantly when the P-gp was silenced by P-gp siRNA-encapsulated aptamer-labeled nanoparticles.

CONCLUSIONS

This preliminary study concludes that downregulating P-gp expression by targeted delivery of P-gp siRNA using aptamer-labeled lipid-based hybrid nanoparticles could effectively increase the intracellular trafficking of doxorubicin in Dox-resistant mouse breast cancer cells.

HSP90 inhibitor PU-H71 increases radiosensitivity of breast cancer cells metastasized to visceral organs and alters the levels of inflammatory mediators

Heat shock protein 90 (HSP90) inhibitors are considered as new radiosensitizing agents. PU-H71, a novel HSP90 inhibitor, is under evaluation for the treatment of advanced cancer. It is however not known whether PU-H71 alters radiosensitivity of metastatic breast cancer. Hence, we here evaluated mechanisms of possible anti-tumoral and radiosensitizing effects of PU-H71 on breast carcinoma cells metastasized to vital organs such as the liver and brain. The effect of PU-H71 on proliferation of breast carcinoma cells was determined using 4T1 cells and its brain (4TBM), liver (4TLM), and heart (4THM) metastatic subsets as well as non-metastatic 67NR cells. Changes in radiation sensitivity were determined by clonogenic assays. Changes in client proteins and levels of angiogenic and inflammatory mediators from these cancer cell cultures and ex vivo cultures were detected. PU-H71 alone inhibited ERK1/2, p38, and Akt activation and reduced N-cadherin and HER2 which further documented the anti-tumoral effects of PU-H71. The combination of PU-H71 and radiotherapy induced cytotoxic effect than PU-H71 alone, and PU-H71 showed a radiosensitizing effect in vitro. On the other hand, PU-H71 and radiation co-treatment increased p38 phosphorylation which is one of the hallmarks of inflammatory response. Accordingly, IL-6 secretion was increased following PU-H71 and radiotherapy co-treatment ex vivo. Levels of angiogenic and inflammatory factors such as MIP-2, SDF-1, and VEGF were increased under in vitro conditions but not under ex vivo conditions. These results demonstrated for the first time that PU-H71 enhances therapeutic effects of radiotherapy especially in highly metastatic breast carcinoma but a possible increase in inflammatory response should also be considered.

Targeting Delivery of Platelets Inhibitor to Prevent Tumor Metastasis

Activated platelets have a high affinity for tumor cells, and consequently, they can protect tumor cells from environmental stress and immune attacks. Therefore, preventing platelet-tumor cell interaction can lead to the elimination of circulating tumor cells via natural killer cells and finally metastasis inhibition. It is also shown that CREKA (Cys-Arg-Glu-Lys-Ala), a tumor-homing pentapeptide, targets fibrin-fibronectin complexes that are found on the tumor stroma and the vessel walls. In this study, we linked CREKA to Ticagrelor, a reversible antagonist of the P2Y₁₂ receptor on platelets. In vitro experiments indicated that CREKA-Ticagrelor could not only inhibit the platelet-induced migration of tumor cells with an invasive phenotype but also prevent tumor-platelet interaction. In vivo antitumor and antimetastasis results of this drug showed that CREKA-Ticagrelor could specifically target the tumor tissues within 24 h post intravenous injection and suppress lung metastasis. Meanwhile, by having this antiplatelet drug targeted, its side effects were minimized, and bleeding risk was decreased. Thus, CREKA-Ticagrelor offers an efficient antimetastatic agent.

Tumor-targeted drug delivery and sensitization by MMP2-responsive polymeric micelles

Low tumor specificity and multidrug resistance (MDR) remain challenging for many anticancer drugs. In this study, the micelles assembled by a matrix metalloproteinase 2 (MMP2)-sensitive self-assembling efflux inhibitor (PEG2k-pp-PE) were developed and evaluated in various cancer models. In vitro, the PEG2k-pp-PE micelles enhanced the cellular uptake and tissue penetration and sensitized the cancers to drug treatments in MDR cancer cells and their three-dimensional multicellular spheroids. Their efflux inhibitory capability was comparable to those of the well-known small-molecule P-glycoprotein (P-gp) inhibitor and polymeric P-gp inhibitor. In vivo, the PEG2k-pp-PE micelles could specifically and effectively deliver the loaded cargoes to the tumor, as evidenced by the enhanced drug accumulation and prolonged drug retention in the tumor tissue, resulting in the improved anticancer activity. Our results suggest that the PEG2k-pp-PE micelles may have great potential to be a simple but multifunctional nanocarrier for concurrent tumor-targeted drug delivery and sensitization of resistant cancers.