Penetration of anticancer drugs through tumour tissue as a function of cellular packing density and interstitial fluid pressure and its modification by bortezomib

Modulation of Breast Cancer Cell Apoptosis and Macrophage Polarization by Mistletoe Lectin in 2D and 3D Models

Korean mistletoe (Viscum album L. var. coloratum) is renowned for its medicinal properties, including anti-cancer and immunoadjuvant effects. This study aimed to elucidate the mechanisms by which Korean mistletoe lectin (V. album L. var. coloratum agglutinin; VCA) modulates breast cancer cell apoptosis and macrophage polarization. The specific objectives were to (1) investigate the direct effects of VCA on MCF-7 breast cancer cells and THP-1-derived M1/M2 macrophages; (2) analyze the impact of VCA on the paracrine interactions between these cell types; and (3) compare the efficacy of VCA in 2D vs. 3D co-culture models to bridge the gap between in vitro and in vivo studies. We employed both 2D and 3D models, co-culturing human M1/M2 macrophages with human MCF-7 breast cancer cells in a Transwell system. Our research demonstrated that M1 and M2 macrophages significantly influenced the immune and apoptotic responses of breast cancer cells when exposed to VCA. M1 macrophages exhibited cytotoxic characteristics and enhanced VCA-induced apoptosis in both 2D and 3D co-culture models. Conversely, M2 macrophages initially displayed a protective effect by reducing apoptosis in breast cancer cells, but this protective effect was reversed upon exposure to VCA. Furthermore, our findings illustrate VCA's ability to modulate M1 and M2 polarization in breast cancer cells. Finally, the use of magnetic 3D cell cultures suggests their potential to yield results comparable to conventional 2D cultures, bridging the gap between in vitro and in vivo studies.

Minimum latency effects for cancer associated with exposures to radiation or other carcinogens

BACKGROUND

In estimating radiation-associated cancer risks a fixed period for the minimum latency is often assumed. Two empirical latency functions have been used to model latency, continuously increasing from 0. A stochastic biologically-based approach yields a still more plausible way of describing latency and can be directly estimated from clinical data.

METHODS

We derived the parameters for a stochastic biologically-based model from tumour growth data for various cancers, and least-squares fitted the two types of empirical latency function to the stochastic model-predicted cumulative probability.

RESULTS

There is wide variation in growth rates among tumours, particularly slow for prostate and thyroid cancer and particularly fast for leukaemia. The slow growth rate for prostate and thyroid tumours implies that the number of tumour cells required for clinical detection cannot greatly exceed 106. For all tumours, both empirical latency functions closely approximated the predicted biological model cumulative probability.

CONCLUSIONS

Our results, illustrating use of a stochastic biologically-based model using clinical data not tied to any particular carcinogen, have implications for estimating latency associated with any mutagen. They apply to tumour growth in general, and may be useful for example, in planning screenings for cancer using imaging techniques.

Fluoxetine enhances the antitumor effect of olfactory ensheathing cell-thymidine kinase/ganciclovir gene therapy in human glioblastoma multiforme cells through upregulation of Connexin43 levels

Glioblastoma multiforme (GBM) is the most invasive form of primary brain astrocytoma, resulting in poor clinical outcomes. Herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy is considered a promising strategy for GBM treatment. Since Connexin43 (Cx43) expression is reduced in GBM cells, increasing Cx43 levels could enhance the effectiveness of gene therapy. The present study aims to examine the impact of fluoxetine on HSV-TK/GCV gene therapy in human GBM cells using human olfactory ensheathing cells (OECs) as vectors. The effect of fluoxetine on Cx43 levels was assessed using the western blot technique. GBM-derived astrocytes and OECs-TK were Cocultured, and the effect of fluoxetine on the Antitumor effect of OEC-TK/GCV gene therapy was evaluated using MTT assay and flow cytometry. Our results showed that fluoxetine increased Cx43 levels in OECs and GBM cells and augmented the killing effect of OECs-TK on GBM cells. Western blot data revealed that fluoxetine enhanced the Bax/Bcl2 ratio and the levels of cleaved caspase-3 in the coculture of OECs-TK and GBM cells. Moreover, flow cytometry data indicated that fluoxetine increased the percentage of apoptotic cells in the coculture system. This study suggests that fluoxetine, by upregulating Cx43 levels, could strengthen the Antitumor effect of OEC-TK/GCV gene therapy on GBM cells.

Comparative analysis of response to treatments and molecular features of tumor-derived organoids versus cell lines and PDX derived from the same ovarian clear cell carcinoma

BACKGROUND

In the era of personalized medicine, the establishment of preclinical models of cancer that faithfully recapitulate original tumors is essential to potentially guide clinical decisions.

METHODS

We established 7 models [4 cell lines, 2 Patient-Derived Tumor Organoids (PDTO) and 1 Patient-Derived Xenograft (PDX)], all derived from the same Ovarian Clear Cell Carcinoma (OCCC). To determine the relevance of each of these models, comprehensive characterization was performed based on morphological, histological, and transcriptomic analyses as well as on the evaluation of their response to the treatments received by the patient. These results were compared to the clinical data.

RESULTS

Only the PDX and PDTO models derived from the patient tumor were able to recapitulate the patient tumor heterogeneity. The patient was refractory to carboplatin, doxorubicin and gemcitabine, while tumor cell lines were sensitive to these treatments. In contrast, PDX and PDTO models displayed resistance to the 3 drugs. The transcriptomic analysis was consistent with these results since the models recapitulating faithfully the clinical response grouped together away from the other classical 2D cell culture models. We next investigated the potential of drugs that have not been used in the patient clinical management and we identified the HDAC inhibitor belinostat as a potential effective treatment based on PDTO response.

CONCLUSIONS

PDX and PDTO appear to be the most relevant models, but only PDTO seem to present all the necessary prerequisites for predictive purposes and could constitute relevant tools for therapeutic decision support in the context of these particularly aggressive cancers refractory to conventional treatments.

Targeted therapy of breast tumor by PLGA-based nanostructures: The versatile function in doxorubicin delivery

Breast carcinoma is a molecularly diverse illness, and it is among the most prominent and often reported malignancies in female across the globe. Surgical intervention, chemotherapy, immunotherapy, gene therapy, and endocrine treatment are among the currently viable treatment options for the carcinoma of breast. Chemotherapy is among the most prevalent cancer management strategy. Doxorubicin (DOX) widely employed as a cytostatic medication for the treatment of a variety of malignancies. Despite its widespread acceptance and excellent efficacy against an extensive line up of neoplasia, it has a variety of shortcomings that limit its therapeutic potential in the previously mentioned indications. Employment of nanoparticulate systems has come up as a unique chemo medication delivery strategy and are being considerably explored for the amelioration of breast carcinoma. Polylactic-co-glycolic acid (PLGA)-based nano systems are being utilized in a number of areas within the medical research and medication delivery constitutes one of the primary functions for PLGA given their inherent physiochemical attributes, including their aqueous solubility, biocompatibility, biodegradability, versatility in formulation, and limited toxicity. Herein along with the different application of PLGA-based nano formulations in cancer therapy, the present review intends to describe the various research investigations that have been conducted to enumerate the effectiveness of DOX-encapsulated PLGA nanoparticles (DOX-PLGA NPs) as a feasible treatment option for breast cancer.

Cancer 3D Models for Metallodrug Preclinical Testing

Despite being standard tools in research, the application of cellular and animal models in drug development is hindered by several limitations, such as limited translational significance, animal ethics, and inter-species physiological differences. In this regard, 3D cellular models can be presented as a step forward in biomedical research, allowing for mimicking tissue complexity more accurately than traditional 2D models, while also contributing to reducing the use of animal models. In cancer research, 3D models have the potential to replicate the tumor microenvironment, which is a key modulator of cancer cell behavior and drug response. These features make cancer 3D models prime tools for the preclinical study of anti-tumoral drugs, especially considering that there is still a need to develop effective anti-cancer drugs with high selectivity, minimal toxicity, and reduced side effects. Metallodrugs, especially transition-metal-based complexes, have been extensively studied for their therapeutic potential in cancer therapy due to their distinctive properties; however, despite the benefits of 3D models, their application in metallodrug testing is currently limited. Thus, this article reviews some of the most common types of 3D models in cancer research, as well as the application of 3D models in metallodrug preclinical studies.

Targeted bacteria-mediated therapy of mouse colorectal cancer using baicalin, a natural glucuronide compound, and E. coli overexpressing β-glucuronidase

The side effects of common chemotherapeutic drugs that damage healthy tissues account for one of the most important problems in cancer research that needs careful addressing. Bacterial-Directed Enzyme Prodrug Therapy (BDEPT) is a promising strategy that uses bacteria to direct a converting enzyme to the tumor site and activate a systemically injected prodrug selectively within the tumor; so that the side effects of the therapy would significantly decrease. In this study, we evaluated the efficacy of baicalin, a natural compound, as a glucuronide prodrug in association with an engineered strain of Escherichia coli DH5α harboring the pRSETB-lux/βG plasmid in a mouse model of colorectal cancer. E. coli DH5α-lux/βG was designed to emit luminescence and overexpress the β-glucuronidase. Unlike the non-engineered bacteria, E. coli DH5α-lux/βG showed the ability to activate baicalin, and the cytotoxic effects of baicalin on the C26 cell line were increased in the presence of E. coli DH5α-lux/βG. Analyzing the tissue homogenates of mice bearing C26 tumors inoculated with E. coli DH5α-lux/βG indicated the specific accumulation and multiplication of bacteria in the tumor tissues. While both baicalin and E. coli DH5α-lux/βG could inhibit tumor growth as monotherapy, an enhanced inhibition was observed when animals were subjected to combination therapy. Moreover, no significant side effects were observed after histological investigation. The results of this study indicate that baicalin has the capability of being used as a suitable prodrug in the BDEPT, however further research is required before it can be applied in the clinic.

The Extracellular Matrix: Its Composition, Function, Remodeling, and Role in Tumorigenesis

The extracellular matrix (ECM) is a ubiquitous member of the body and is key to the maintenance of tissue and organ integrity. Initially thought to be a bystander in many cellular processes, the extracellular matrix has been shown to have diverse components that regulate and activate many cellular processes and ultimately influence cell phenotype. Importantly, the ECM's composition, architecture, and stiffness/elasticity influence cellular phenotypes. Under normal conditions and during development, the synthesized ECM constantly undergoes degradation and remodeling processes via the action of matrix proteases that maintain tissue homeostasis. In many pathological conditions including fibrosis and cancer, ECM synthesis, remodeling, and degradation is dysregulated, causing its integrity to be altered. Both physical and chemical cues from the ECM are sensed via receptors including integrins and play key roles in driving cellular proliferation and differentiation and in the progression of various diseases such as cancers. Advances in 'omics' technologies have seen an increase in studies focusing on bidirectional cell-matrix interactions, and here, we highlight the emerging knowledge on the role played by the ECM during normal development and in pathological conditions. This review summarizes current ECM-targeted therapies that can modify ECM tumors to overcome drug resistance and better cancer treatment.

Effect of paclitaxel priming on doxorubicin penetration in a multicellular layer model of human colorectal cancer cells

Tumor priming is considered a promising strategy for improving drug distribution in malignant tissues. Multicellular layers (MCLs) of human cancer cells are potentially useful models for evaluating tumor-priming agents. We evaluated the priming effects of paclitaxel (PTX) on doxorubicin (DOX) penetration using MCLs of the human colorectal cancer cell lines including DLD-1, HCT-116, and HT-29. The penetration of DOX treated at 50 μM for 3 h was highly limited in all three MCLs. The penetration of the priming agent PTX into MCLs was determined using rhodamine-labeled PTX and appeared to be cell line-dependent: full penetration was observed in HCT-116 and HT-29 MCLs, whereas only limited penetration occurred in DLD-1 MCLs. PTX pretreatment at 20 μM for 24 or 48 h induced a tumor-priming effect in DOX distribution, with a 3 to 5.6-fold-increase in HCT-116 and HT-29 MCLs but a less than two-fold increase in DLD-1 MCLs. PTX treatment decreased fibronectin expression in HCT-116 and HT-29 MCLs but not in DLD-1, suggesting that the prominent priming effect of PTX in HCT-116 and HT-29 MCLs may be associated with the downregulation of fibronectin expression. Our study demonstrated that MCLs of human cancer cells are a useful model not only for the study of drug penetration into tumor tissues but also for screening and evaluating tumor-priming agents.

Future directions in cancer immunotherapy with monoclonal antibodies

Introduction: Cancer immunotherapy with monoclonal antibodies (mAbs) has become a therapy with great potential nowadays. It is based on the affinity of antibodies to bind to specific molecules, thus inhibiting the growth and spread of cancer. There is a wide variety of mAbs with differentiated mechanisms and enormous clinical benefits. However, different immunotherapeutic alternatives have emerged due to their limitations, such as the long duration of organ toxicity and the inability to penetrate intracellularly. This mini-review will discuss the emerging alternatives of cancer immunotherapies based on mAbs.

Bispecific antibodies (BsAbs): Antibodies designed to bind to two epitopes of an antigen.

Antibody fragments: Fragments of the Fab region generated from the variable region of IgG and IgM and a scFv.

Antibody-drug conjugates (ADCs): Administration of mAbs and a toxin of high specificity for a tumour target.

Nanobodies (or nanocomponents): Small fragments of antibody heavy chain.

Intrabodies (or intracellular antibodies): Antibodies that are expressed intracellularly and synthesised inside cells by retroviral delivery systems.

Stereospecific and catalytic mAbs: Antibodies that recognise the 3D configurations of target molecules.

Combination immunotherapies: Therapies that combine cytokines with tumour-targeted mAbs.

Small molecule immunotherapeutics: Small molecule drugs that can stimulate intracellular pathways primarily involved in immune cell checkpoints and bind to mAb-like targets.

Conclusion: These new varieties of immunotherapy present significant advantages, but future research should continue to improve their efficacy and safety and identify new biomarkers.

Graphical abstract:

Human Myometrial and Uterine Fibroid Stem Cell-Derived Organoids for Intervening the Pathophysiology of Uterine Fibroid

Uterine fibroids (UFs) (leiomyomas or myomas) are the most common clonal neoplasms of the uterus in women of reproductive age worldwide. UFs originate from myometrium consist of smooth muscle and fibroblast components, in addition to a substantial amount of fibrous extracellular matrix which all contribute to the pathogenetic process. Current treatments are primarily limited to surgical and interventional. Here, we have established a novel and promising organoid model from both normal and patient myometrial stem cells (MMSCs). MMSCs embedded in Matrigel in stem cell media swiftly formed organoids which successfully proliferate and self-organized into complex structures developing a sustainable organoid culture that maintain their capacity to differentiate into the different cell types recapitulating their tissue of origin and shows responsiveness to the reproductive hormones (estrogen and progesterone). Gene expression analysis and structural features indicated the early onset of uterine fibrosis led to the accumulation of extracellular matrix suggesting the potential use of this model in better understanding of the pathophysiology associated with UFs and inventing novel therapeutics for the treatment of UFs.

GM101 in Combination with Histone Deacetylase Inhibitor Enhances Anti-Tumor Effects in Desmoplastic Microenvironment

Oncolytic adenoviruses (oAds) have been evaluated in numerous clinical trials due to their promising attributes as cancer therapeutics. However, the therapeutic efficacy of oAds was limited due to variable coxsackie and adenovirus receptor (CAR) expression levels and the dense extracellular matrix (ECM) of heterogenic clinical tumors. To overcome these limitations, our present report investigated the therapeutic efficacy of combining GM101, an oAd with excellent tumor ECM degrading properties, and histone deacetylase inhibitor (HDACi). Four different HDACi (suberohydroxamic acid (SBHA), MS-275, trichostatin A (TSA), and valproic acid) candidates in combination with replication-incompetent and GFP-expressing Ad (dAd/GFP) revealed that SBHA and MS-275 exerted more potent enhancement in Ad transduction efficacy than TSA or valproic acid. Further characterization revealed that SBHA and MS-275 effectively upregulated CAR expression in cancer cells, improved the binding of Ad with cancer cell membranes, and led to dynamin 2- and clathrin-mediated endocytosis of Ad. The combination of GM101 with HDACi induced superior cancer cell killing effects compared to any of the monotherapies, without any additional cytotoxicity in normal cell lines. Further, GM101+SBHA and GM101+MS-275 induced more potent antitumor efficacy than any monotherapy in U343 xenograft tumor model. Potent antitumor efficacy was achieved via the combination of GM101 with HDACi, inducing necrotic and apoptotic cancer cell death, inhibiting cancer cell proliferation, degrading ECM in tumor tissue, and thus exerting the highest level of virus dispersion and accumulation. Collectively, these data demonstrate that the combination of GM101 and HDACi can enhance intratumoral dispersion and accumulation of oAd through multifaced mechanisms, making it a promising strategy to address the challenges toward successful clinical development of oAd.

Drug penetration in pediatric brain tumors: Challenges and opportunities

Larger clinical trial enrollments and a greater understanding of biological heterogeneity have led to improved survival rates for children diagnosed with brain tumors in the last 50 years. However, reducing long-term morbidities and improving survival rates of high-risk tumors remain major challenges. Chemotherapy can reduce tumor burden, but effective drug penetration at the tumor site is limited by barriers in the route of drug administration and within the tumor microenvironment. Bioavailability of drugs is impeded by the blood-brain barrier, plasma protein binding, and structural components by the tumor including the matrix and vasculature contributing to increased interstitial fluid pressure, hypoxia, and acidity. Designing drug delivery systems to circumvent these barriers could lead to improved drug penetration at the tumor site and reduce adverse systemic side effects. In this review, we expand on how systemic and local barriers limit drug penetration and present potential methods to enhance drug penetration in pediatric brain tumors.

A human Myogenin promoter modified to be highly active in alveolar rhabdomyosarcoma drives an effective suicide gene therapy

Rhabdomyosarcoma is a rare childhood soft tissue cancer whose cells resemble poorly differentiated skeletal muscle, expressing myogenic proteins including MYOGENIN. Alveolar rhabdomyosarcoma (ARMS) accounts for ~40% of cases and is associated with a poorer prognosis than other rhabdomyosarcoma variants, especially if containing the chromosomal translocation generating the PAX3-FOXO1 hybrid transcription factor. Metastasis is commonly present at diagnosis, with a five-year survival rate of <30%, highlighting the need for novel therapeutic approaches. We designed a suicide gene therapy by generating an ARMS-targeted promoter to drive the herpes simplex virus thymidine kinase (HSV-TK) suicide gene. We modified the minimal human MYOGENIN promoter by deleting both the NF1 and MEF3 transcription factor binding motifs to produce a promoter that is highly active in ARMS cells. Our bespoke ARMS promoter driving HSV-TK efficiently killed ARMS cells in vitro, but not skeletal myoblasts. Using a xenograft mouse model, we also demonstrated that ARMS promoter-HSV-TK causes apoptosis of ARMS cells in vivo. Importantly, combining our suicide gene therapy with standard chemotherapy agents used in the treatment of rhabdomyosarcoma, reduced the effective drug dose, diminishing deleterious side effects/patient burden. This modified, highly ARMS-specific promoter could provide a new therapy option for this difficult-to-treat cancer.

A pilot trial of intravital microscopy in the study of the tumor vasculature of patients with peritoneal carcinomatosis

Aberrancies in the tumor microvasculature limit the systemic delivery of anticancer agents, which impedes tumor response. Using human intravital microscopy (HIVM), we hypothesized that HIVM would be feasible in patients with peritoneal carcinomatosis (PC). During cytoreductive surgery with hyperthermic intraperitoneal chemotherapy for PC, HIVM was performed in both tumor and non-tumor areas. The primary outcome was HIVM feasibility to measure vessel characteristics. We secondarily evaluated associations between HIVM vessel characteristics and oncologic outcomes (RECIST response to neoadjuvant therapy and disease-specific survival). Thirty patients with PC were enrolled. Nineteen patients (63.3%) received neoadjuvant therapy. HIVM was feasible in all patients. Compared to non-tumor (control) areas, PC areas had a lower density of functional vessels, higher proportion of non-functional vessels, smaller lumenal diameters, and lower blood flow velocity. Qualitative differences in these vessel characteristics were observed among patients who had partial response, stable disease, or progressive disease after receiving neoadjuvant therapy. However, no statistically significant relationships were found between HIVM vessel characteristics and oncologic outcomes. These novel findings comprise the first-in-human, real-time evidence of the microscopic differences between normal and tumor-associated vessels and form the basis for our larger, ongoing clinical trial appropriately powered to determine the clinical utility of HIVM (NCT03823144).

Opportunities for Quantitative Translational Modeling in Oncology

A 2-day meeting was held by members of the UK Quantitative Systems Pharmacology Network () in November 2018 on the topic of Translational Challenges in Oncology. Participants from a wide range of backgrounds were invited to discuss current and emerging modeling applications in nonclinical and clinical drug development, and to identify areas for improvement. This resulting perspective explores opportunities for impactful quantitative pharmacology approaches. Four key themes arose from the presentations and discussions that were held, leading to the following recommendations: Evaluate the predictivity and reproducibility of animal cancer models through precompetitive collaboration. Apply mechanism of action (MoA) based mechanistic models derived from nonclinical data to clinical trial data. Apply MoA reflective models across trial data sets to more robustly quantify the natural history of disease and response to differing interventions. Quantify more robustly the dose and concentration dependence of adverse events through mathematical modelling techniques and modified trial design.

Multiplexed non-invasive tumor imaging of glucose metabolism and receptor-ligand engagement using dark quencher FRET acceptor

Rationale: Following an ever-increased focus on personalized medicine, there is a continuing need to develop preclinical molecular imaging modalities to guide the development and optimization of targeted therapies. Near-Infrared (NIR) Macroscopic Fluorescence Lifetime Förster Resonance Energy Transfer (MFLI-FRET) imaging offers a unique method to robustly quantify receptor-ligand engagement in live intact animals, which is critical to assess the delivery efficacy of therapeutics. However, to date, non-invasive imaging approaches that can simultaneously measure cellular drug delivery efficacy and metabolic response are lacking. A major challenge for the implementation of concurrent optical and MFLI-FRET in vivo whole-body preclinical imaging is the spectral crowding and cross-contamination between fluorescent probes. Methods: We report on a strategy that relies on a dark quencher enabling simultaneous assessment of receptor-ligand engagement and tumor metabolism in intact live mice. Several optical imaging approaches, such as in vitro NIR FLI microscopy (FLIM) and in vivo wide-field MFLI, were used to validate a novel donor-dark quencher FRET pair. IRDye 800CW 2-deoxyglucose (2-DG) imaging was multiplexed with MFLI-FRET of NIR-labeled transferrin FRET pair (Tf-AF700/Tf-QC-1) to monitor tumor metabolism and probe uptake in breast tumor xenografts in intact live nude mice. Immunohistochemistry was used to validate in vivo imaging results. Results: First, we establish that IRDye QC-1 (QC-1) is an effective NIR dark acceptor for the FRET-induced quenching of donor Alexa Fluor 700 (AF700). Second, we report on simultaneous in vivo imaging of the metabolic probe 2-DG and MFLI-FRET imaging of Tf-AF700/Tf-QC-1 uptake in tumors. Such multiplexed imaging revealed an inverse relationship between 2-DG uptake and Tf intracellular delivery, suggesting that 2-DG signal may predict the efficacy of intracellular targeted delivery. Conclusions: Overall, our methodology enables for the first time simultaneous non-invasive monitoring of intracellular drug delivery and metabolic response in preclinical studies.

Dynamic control of tumor vasculature improves antitumor responses in a regional model of melanoma

Despite advances in therapy for melanoma, heterogeneous responses with limited durability represent a major gap in treatment outcomes. The purpose of this study was to determine whether alteration in tumor blood flow could augment drug delivery and improve antitumor responses in a regional model of melanoma. This approach to altering tumor blood flow was termed "dynamic control." Dynamic control of tumor vessels in C57BL/6 mice bearing B16 melanoma was performed using volume expansion (saline bolus) followed by phenylephrine. Intravital microscopy (IVM) was used to observe changes directly in real time. Our approach restored blood flow in non-functional tumor vessels. It also resulted in increased chemotherapy (melphalan) activity, as measured by formation of DNA adducts. The combination of dynamic control and melphalan resulted in superior outcomes compared to melphalan alone (median time to event 40.0 vs 25.0 days, respectively, p = 0.041). Moreover, 25% (3/12) of the mice treated with the combination approach showed complete tumor response. Importantly, dynamic control plus melphalan did not result in increased adverse events. In summary, we showed that dynamic control was feasible, directly observable, and augmented antitumor responses in a regional model of melanoma. Early clinical trials to determine the translational feasibility of dynamic control are ongoing.

The Proteasome Inhibitor Ixazomib Inhibits the Formation and Growth of Pulmonary and Abdominal Osteosarcoma Metastases in Mice

Osteosarcoma is the most common form of primary bone cancer. Over 20% of osteosarcoma patients present with pulmonary metastases at diagnosis, and nearly 70% of these patients fail to respond to treatment. Previous work revealed that human and canine osteosarcoma cell lines are extremely sensitive to the therapeutic proteasome inhibitor bortezomib in vitro. However, bortezomib has proven disappointingly ineffective against solid tumors including sarcomas in animal experiments and clinical trials. Poor tumor penetration has been speculated to account for the inconsistency between in vitro and in vivo responses of solid tumors to bortezomib. Here we show that the second-generation proteasome inhibitor ixazomib, which reportedly has enhanced solid tumor penetration compared to bortezomib, is toxic to human and canine osteosarcoma cells in vitro. We used experimental osteosarcoma metastasis models to compare the efficacies of ixazomib and bortezomib against primary tumors and metastases derived from luciferase-expressing KRIB or 143B human osteosarcoma cell lines in athymic mice. Neither proteasome inhibitor reduced the growth of primary intramuscular KRIB tumors, however both drugs inhibited the growth of established pulmonary metastases created via intravenous inoculation with KRIB cells, which were significantly better vascularized than the primary tumors. Only ixazomib slowed metastases from KRIB primary tumors and inhibited the growth of 143B pulmonary and abdominal metastases, significantly enhancing the survival of mice intravenously injected with 143B cells. Taken together, these results suggest ixazomib exerts better single agent activity against osteosarcoma metastases than bortezomib. These data provide hope that incorporation of ixazomib, or other proteasome inhibitors that penetrate efficiently into solid tumors, into current regimens may improve outcomes for patients diagnosed with metastatic osteosarcoma.

In vivo antitumoral effect of 4-nerolidylcatechol (4-NC) in NRAS-mutant human melanoma

NRAS-mutations arise in 15-20% of all melanomas and are associated with aggressive disease and poor prognosis. Besides, the treatment for NRAS-mutant melanoma are not very efficient and is currently limited to immune checkpoints inhibitors or aggressive chemotherapy. 4-nerolidylcathecol (4-NC), a natural product extracted from Pothomorphe umbellata, induces apoptosis in melanoma cells by ROS production, DNA damage and increased p53 expression, in addition to inhibiting invasion in reconstructed skin. Moreover, 4-NC showed cytotoxicity in BRAF/MEKi-resistant and naive melanoma cells by Endoplasmic Reticulum (ER) stress induction in vitro. We evaluated the in vivo efficacy and the systemic toxicity of 4-NC in a NRAS-mutant melanoma model. 4-NC was able to significantly suppress tumor growth 4-fold compared to controls. Cleaved PARP and p53 expression were increased indicating cell death. As a proof of concept, MMP-2 and MMP-14 gene expression were decreased, demonstrating a possible role of 4-NC in melanoma invasion inhibition. Toxicological analysis indicated minor changes in the liver and bone marrow, but this toxicity was very mild when compared to other proteasome inhibitors and ER stress inductors already described. Our data indicate that 4-NC can counteract melanoma growth in vivo with minor adverse effects, suggesting further investigation as a potential NRAS-mutant melanoma treatment.

Maximizing the Value of Cancer Drug Screening in Multicellular Tumor Spheroid Cultures: A Case Study in Five Head and Neck Squamous Cell Carcinoma Cell Lines

With approval rates <5% and the probability of success in oncology clinical trials of 3.4%, more physiologically relevant in vitro three-dimensional models are being deployed during lead generation to select better drug candidates for solid tumors. Multicellular tumor spheroids (MCTSs) resemble avascular tumor nodules, micrometastases, or the intervascular regions of large solid tumors with respect to morphology, cell-cell and cell-extracellular matrix contacts, and volume growth kinetics. MCTSs develop gradients of nutrient and oxygen concentration resulting in diverse microenvironments with differential proliferation and drug distribution zones. We produced head and neck squamous cell carcinoma (HNSCC) MCTSs in 384-well U-bottom ultra-low-attachment microtiter plates and used metabolic viability and imaging methods to measure morphologies, growth phenotypes and the effects of 19 anticancer drugs. We showed that cell viability measurements underestimated the impact of drug exposure in HNSCC MCTS cultures, but that incorporating morphology and dead-cell staining analyses increased the number of drugs judged to have substantially impacted MCTS cultures. A cumulative multiparameter drug impact score enabled us to stratify MCTS drug responses into high-, intermediate-, and low-impact tiers, and maximized the value of these more physiologically relevant tumor cultures. It is conceivable that the viable cells present in MCTS cultures after drug exposure arise from drug-resistant populations that could represent a source of drug failure and recurrence. Long-term monitoring of treated MCTS cultures could provide a strategy to determine whether these drug-resistant populations represent circumstances where tumor growth is delayed and may ultimately give rise to regrowth.

pH/redox sequentially responsive nanoparticles with size shrinkage properties achieve deep tumor penetration and reversal of multidrug resistance

pH/redox sequentially responsive nanoparticles with size shrinkage properties achieve deep tumor penetration and reversal of multidrug resistance.

Intratumoral distribution of YSNSG cyclopeptide in a mouse melanoma model using microdialysis

The YSNSG peptide is a synthetic cyclopeptide targeting α_vβ₃ integrin with antitumor activity. Previous study has determined main pharmacokinetic parameters in plasma and in tissue in healthy animals using microdialysis. First we aim to assess the impact of a 20 mg/kg dosage instead of 10 mg/kg in tumor growth inhibition. Secondly we aim to investigate the YSNSG peptide distribution in two different tumor regions in animals with melanoma. C57BL/6 mice were exposed at Days 8, 10 and 12 after melanoma cells implantation (B16F1) to different dosage of YSNSG peptide or control, respectively (n = 10 per group). Data analysis was performed at D16, 20 and 24 with a Nonlinear Mixed-Effects (NLME) approach. For pharmacokinetic study n = 8 mice (same disease condition) received YSNSG peptide by intravenous after insertion of two microdialysis probes in central peripheral region of tumor, respectively. Plasma and tissue samples were collected during 2 h. A non-compartmental analysis was performed to determine main pharmacokinetic parameters. There was a significant tumor growth inhibition in mice receiving 20 mg/kg vs Control (p < 0.02). Main plasma parameters were half-life elimination 25.8 ± 8.2 min, volume of distribution 11.9 ± 0.4 mL, clearance 19.8 ± 9.4 mL/h and area under the curve 1,173.6 µg.min/mL. Penetration rate of the YSNSG peptide from plasma to tumor tissue were 3.3 ± 2.1% and 3.4 ± 2.7% in central and peripheral, respectively. Contrary to subcutaneous distribution in healthy animals the distribution of the YSNSG peptide into tumoral tissue is low but seems non-heterogeneous between central and peripheral tumor region.

Boyden chamber-based compartmentalized tumor spheroid culture system to implement localized anticancer drug treatment

In anticancer drug development, it is important to simultaneously evaluate both the effect of drugs on cell proliferation and their ability to penetrate tissues. To realize such an evaluation process, here, we present a compartmentalized tumor spheroid culture system utilizing a thin membrane with a through-hole to conduct localized anticancer treatment of tumor spheroids and monitor spheroid dimensions as an indicator of cell proliferation. The system is based on a commercialized Boyden chamber plate; a through-hole was bored through a porous membrane of the chamber, and the pre-existing 0.4 μm membrane pores were filled with parylene C. A HepG2 spheroid was immobilized onto the through-hole, separating the upper and lower compartments. Fluorescein (to verify the isolation between the compartments) and tirapazamine (TPZ; to treat only the lower part of the spheroid) were added to the upper and lower compartments, respectively. Since the transportation of fluorescein was blocked during treatment, i.e., the upper and lower compartments were isolated, it was confirmed that localized TPZ treatment was successfully conducted using the developed system. The effect of localized TPZ treatment on cell proliferation was estimated by measuring the maximum horizontal cross-sectional areas in the upper and lower parts of the spheroid by microscopic observations. This system can, thus, be used to perform localized anticancer drug treatment of tumor spheroids and evaluate the effect of drugs on cell proliferation.

Monoclonal Antibodies: Past, Present and Future

Monoclonal antibodies (mAbs) are immunoglobulins designed to target a specific epitope on an antigen. Immunoglobulins of identical amino-acid sequence were originally produced by hybridomas grown in culture and, subsequently, by recombinant DNA technology using mammalian cell expression systems. The antigen-binding region of the mAb is formed by the variable domains of the heavy and light chains and contains the complementarity-determining region that imparts the high specificity for the target antigen. The pharmacokinetics of mAbs involves target-mediated and non-target-related factors that influence their disposition.Preclinical safety evaluation of mAbs differs substantially from that of small molecular (chemical) entities. Immunogenicity of mAbs has implications for their pharmacokinetics and safety. Early studies of mAbs in humans require careful consideration of the most suitable study population, route/s of administration, starting dose, study design and the potential difference in pharmacokinetics in healthy subjects compared to patients expressing the target antigen.Of the ever-increasing diversity of therapeutic indications for mAbs, we have concentrated on two that have proved dramatically successful. The contribution that mAbs have made to the treatment of inflammatory conditions, in particular arthritides and inflammatory bowel disease, has been nothing short of revolutionary. Their benefit has also been striking in the treatment of solid tumours and, most recently, as immunotherapy for a wide variety of cancers. Finally, we speculate on the future with various new approaches to the development of therapeutic antibodies.

High Content Screening Characterization of Head and Neck Squamous Cell Carcinoma Multicellular Tumor Spheroid Cultures Generated in 384-Well Ultra-Low Attachment Plates to Screen for Better Cancer Drug Leads

Multicellular tumor spheroid (MCTS) cultures represent more physiologically relevant in vitro cell tumor models that recapitulate the microenvironments and cell-cell or cell-extracellular matrix interactions which occur in solid tumors. We characterized the morphologies, viability, and growth behaviors of MCTSs produced by 11 different head and neck squamous cell carcinoma (HNSCC) cell lines seeded into and cultured in ultra-low attachment microtiter plates (ULA-plates) over extended periods of time. HNSCC MCTS cultures developed microenvironments, which resulted in differences in proliferation rates, metabolic activity, and mitochondrial functional activity between cells located in the outer layers of the MCTS and cells in the interior. HNSCC MCTS cultures exhibited drug penetration and distribution gradients and some developed necrotic cores. Perhaps the most profound effect of culturing HNSCC cell lines in MCTS cultures was their dramatically altered and varied growth phenotypes. Instead of the exponential growth that are characteristic of two-dimensional HNSCC growth inhibition assays, some MCTS cultures displayed linear growth rates, categorized as rapid, moderate, or slow, dormant MCTSs remained viable but did not grow, and some MCTSs exhibited death phenotypes that were either progressive and slow or rapid. The ability of MCTS cultures to develop microenvironments and to display a variety of different growth phenotypes provides in vitro models that are more closely aligned with solid tumors in vivo. We anticipate that the implementation MCTS models to screen for new cancer drugs for solid tumors like HNSCC will produce leads that will translate better in in vivo animal models and patients.

Cancer Stem Cells: Emergent Nature of Tumor Emergency

A functional analysis of 167 genes overexpressed in Krebs-2 tumor initiating cells was performed. In the first part of the study, the genes were analyzed for their belonging to one or more of the three groups, which represent the three major phenotypic manifestation of malignancy of cancer cells, namely (1) proliferative self-sufficiency, (2) invasive growth and metastasis, and (3) multiple drug resistance. 96 genes out of 167 were identified as possible contributors to at least one of these fundamental properties. It was also found that substantial part of these genes are also known as genes responsible for formation and/or maintenance of the stemness of normal pluri-/multipotent stem cells. These results suggest that the malignancy is simply the ability to maintain the stem cell specific genes expression profile, and, as a consequence, the stemness itself regardless of the controlling effect of stem niches. In the second part of the study, three stress factors combined into the single concept of "generalized cellular stress," which are assumed to activate the expression of these genes, were defined. In addition, possible mechanisms for such activation were identified. The data obtained suggest the existence of a mechanism for the de novo formation of a pluripotent/stem phenotype in the subpopulation of "committed" tumor cells.

Multilayered Cultures of NSCLC cells grown at the Air-Liquid Interface allow the efficacy testing of inhaled anti-cancer drugs

Evidence supports the advantages of inhalation over other drug-administration routes in the treatment of lung diseases, including cancer. Although data obtained from animal models and conventional in vitro cultures are informative, testing the efficacy of inhaled chemotherapeutic agents requires human-relevant preclinical tools. Such tools are currently unavailable. Here, we developed and characterized in vitro models for the efficacy testing of inhaled chemotherapeutic agents against non-small-cell lung cancer (NSCLC). These models recapitulated key elements of both the lung epithelium and the tumour tissue, namely the direct contact with the gas phase and the three-dimensional (3D) architecture. Our in vitro models were formed by growing, for the first time, human adenocarcinoma (A549) cells as multilayered mono-cultures at the Air-Liquid Interface (ALI). The in vitro models were tested for their response to four benchmarking chemotherapeutics, currently in use in clinics, demonstrating an increased resistance to these drugs as compared to sub-confluent monolayered 2D cell cultures. Chemoresistance was comparable to that detected in 3D hypoxic tumour spheroids. Being cultured in ALI conditions, the multilayered monocultures demonstrated to be compatible with testing drugs administered as a liquid aerosol by a clinical nebulizer, offering an advantage over 3D tumour spheroids. In conclusion, we demonstrated that our in vitro models provide new human-relevant tools allowing for the efficacy screening of inhaled anti-cancer drugs.

3D breast cancer microtissue reveals the role of tumor microenvironment on the transport and efficacy of free-doxorubicin in vitro

The use of 3D cancer models will have both ethical and economic impact in drug screening and development, to promote the reduction of the animals employed in preclinical studies. Nevertheless, to be effective, such cancer surrogates must preserve the physiological relevance of the in vivo models in order to provide realistic information on drugs' efficacy. To figure out the role of the architecture and composition of 3D cancer models on their tumor-mimicking capability, here we studied the efficacy of doxorubicin (DOX), a well-known anticancer molecule in two different 3D cancer models: our 3D breast cancer microtissue (3D-μTP) versus the golden standard represented by spheroid model (sph). Both models were obtained by using cancer associated fibroblast (CAF) and breast cancer cells (MCF-7) as cellular component. Unlike spheroid model, 3D-μTP was engineered in order to induce the production of endogenous extracellular matrix by CAF. 3D-μTP have been compared to spheroid in mono- (MCF-7 alone) and co-culture (MCF-7/CAF), after the treatment with DOX in order to study cytotoxicity effect, diffusional transport and expression of proteins related to cancer progression. Compared to the spheroid model, 3D-μTP showed higher diffusion coefficient of DOX and lower cell viability. Also, the expression of some tumoral biomarkers related to cell junctions were different in the two models.

STATEMENTS OF SIGNIFICANCE

Cancer biology has made progress in unraveling the mechanism of cancer progression, anyway the most of the results are still obtained by 2D cell cultures or animal models, that do not faithfully copycat the tumor microenvironment. The lack of correlation between preclinical models and in vivo organisms negatively influences the clinical efficacy of chemotherapeutic drugs. Consequently, even if a huge amount of new drugs has been developed in the last decades, still people are dying because of cancer. Pharmaceutical companies are interested in 3D tumor model as valid alternative in drug screening in preclinical studies. However, a 3D tumor model that completely mimics tumor heterogeneity is still far to achieve. In our work we compare 3D human breast cancer microtissues and spheroids in terms of response to doxorubicin and drug diffusion. We believe that our results are interesting because they highlight the potential role of the proposed tumor model in the attempts to improve efficacy tests.

A multiscale model for heterogeneous tumor spheroid in vitro

In this paper, a novel multiscale method is proposed for the study of heterogeneous tumor spheroid growth in vitro. The entire tumor spheroid is described by an ellipsoid-based model while nutrient and other environmental factors are treated as continua. The ellipsoid-based discrete component is capable of incorporating mechanical effects and deformability, while keeping a minimum set of free variables to describe complex shape variations. Moreover, our purely cell-based description of tumor avoids the complex mutual conversion between a cell-based model and continuum model within a tumor, such as force and mass transformation. This advantage makes it highly suitable for the study of tumor spheroids in vitro whose size are normally less than 800 μm in diameter. In addition, our numerical scheme provides two computational options depending on tumor size. For a small or medium tumor spheroid, a three-dimensional (3D) numerical model can be directly applied. For a large spheroid, we suggest the use of a 3D-adapted 2D cross section configuration, which has not yet been explored in the literature, as an alternative for the theoretical investigation to bridge the gap between the 2D and 3D models. Our model and its implementations have been validated and applied to various studies given in the paper. The simulation results fit corresponding in vitro experimental observations very well.

Investigating Low-Velocity Fluid Flow in Tumors with Convection-MRI

Several distinct fluid flow phenomena occur in solid tumors, including intravascular blood flow and interstitial convection. Interstitial fluid pressure is often raised in solid tumors, which can limit drug delivery. To probe low-velocity flow in tumors resulting from raised interstitial fluid pressure, we developed a novel MRI technique named convection-MRI, which uses a phase-contrast acquisition with a dual-inversion vascular nulling preparation to separate intra- and extravascular flow. Here, we report the results of experiments in flow phantoms, numerical simulations, and tumor xenograft models to investigate the technical feasibility of convection-MRI. We observed a significant correlation between estimates of effective fluid pressure from convection-MRI with gold-standard, invasive measurements of interstitial fluid pressure in mouse models of human colorectal carcinoma. Our results show how convection-MRI can provide insights into the growth and responsiveness to vascular-targeting therapy in colorectal cancers.Significance: A noninvasive method for measuring low-velocity fluid flow caused by raised fluid pressure can be used to assess changes caused by therapy. Cancer Res; 78(7); 1859-72. ©2018 AACR.

High-Content Screening Comparison of Cancer Drug Accumulation and Distribution in Two-Dimensional and Three-Dimensional Culture Models of Head and Neck Cancer

High cancer drug development attrition rates have provoked considerable debate about whether the two-dimensional tumor growth inhibition high-throughput screening assays used in pre-clinical lead discovery adequately reflect solid tumor complexity. We used automated high-content screening image acquisition and analysis methods to compare fluorescent drug uptake, accumulation, and distribution in Cal33 and FaDu head and neck cancer (HNC) monolayer and multicellular tumor spheroid (MCTS) models. Ellipticine, idarubicin, daunorubicin, and doxorubicin were studied because of their fluorescent properties and broad anti-tumor activities. HNC MCTSs were generated in 384-well ultra-low attachment plates where compound exposure, image acquisition, and analysis could be performed in situ. Fluorescent drug accumulation in Cal33 monolayer and MCTS cultures was linear with respect to concentration, and appeared to achieve steady-state levels within 10-15 min of drug exposure, which were maintained through 30-45 min. Drug accumulation in monolayers was independent of cell number and/or density, and every cell achieved uniform drug concentrations. In MCTSs, however, drug accumulation increased as the number of cells and sizes of the MCTSs became bigger. Drugs exhibited restricted penetration and distribution gradients, accumulating preferentially in cells in the outer layers of MCTSs relative to those in the inner cores. Cal33 monolayers were 6-, 20-, 10-, and 16-fold more sensitive than MCTSs to growth inhibition by ellipticine, idarubicin, daunorubicin, and doxorubicin, respectively. In Cal33 MCTSs exposed to ellipticine or doxorubicin for 24 h, MCTSs were smaller and although they still exhibited drug penetration and distribution gradients, the fluorescent intensity difference between outer and inner cells was reduced. After a 24 h exposure, both drugs had penetrated throughout FaDu MCTSs, consistent with drug-induced death of peripheral cell layers enhancing drug penetration. The increased resistance of MCTS cultures and their ability to recapitulate drug penetration and distribution gradients argues strongly for the deployment of these more physiological models in cancer lead discovery. MCTSs have the potential to enhance the correlation between in vitro potencies and in vivo efficacy, and ultimately may lead to improved cancer drug approval rates.

Multiphoton fluorescence lifetime imaging of chemotherapy distribution in solid tumors

Doxorubicin is a commonly used chemotherapeutic employed to treat multiple human cancers, including numerous sarcomas and carcinomas. Furthermore, doxorubicin possesses strong fluorescent properties that make it an ideal reagent for modeling drug delivery by examining its distribution in cells and tissues. However, while doxorubicin fluorescence and lifetime have been imaged in live tissue, its behavior in archival samples that frequently result from drug and treatment studies in human and animal patients, and murine models of human cancer, has to date been largely unexplored. Here, we demonstrate imaging of doxorubicin intensity and lifetimes in archival formalin-fixed paraffin-embedded sections from mouse models of human cancer with multiphoton excitation and multiphoton fluorescence lifetime imaging microscopy (FLIM). Multiphoton excitation imaging reveals robust doxorubicin emission in tissue sections and captures spatial heterogeneity in cells and tissues. However, quantifying the amount of doxorubicin signal in distinct cell compartments, particularly the nucleus, often remains challenging due to strong signals in multiple compartments. The addition of FLIM analysis to display the spatial distribution of excited state lifetimes clearly distinguishes between signals in distinct compartments such as the cell nuclei versus cytoplasm and allows for quantification of doxorubicin signal in each compartment. Furthermore, we observed a shift in lifetime values in the nuclei of transformed cells versus nontransformed cells, suggesting a possible diagnostic role for doxorubicin lifetime imaging to distinguish normal versus transformed cells. Thus, data here demonstrate that multiphoton FLIM is a highly sensitive platform for imaging doxorubicin distribution in normal and diseased archival tissues.

Antibody or Antibody Fragments: Implications for Molecular Imaging and Targeted Therapy of Solid Tumors

The use of antibody-based therapeutics has proven very promising for clinical applications in cancer patients, with multiple examples of antibodies and antibody–drug conjugates successfully applied for the treatment of solid tumors and lymphomas. Given reported recurrence rates, improvements are clearly still necessary. A major factor limiting the efficacy of antibody-targeted cancer therapies may be the incomplete penetration of the antibody or antibody–drug conjugate into the tumor. Incomplete tumor penetration also affects the outcome of molecular imaging, when using such targeting agents. From the injection site until they arrive inside the tumor, targeting molecules are faced with several barriers that impact intratumoral distribution. The primary means of antibody transport inside tumors is based on diffusion. The diffusive penetration inside the tumor is influenced by both antibody properties, such as size and binding affinity, as well as tumor properties, such as microenvironment, vascularization, and targeted antigen availability. Engineering smaller antibody fragments has shown to improve the rate of tumor uptake and intratumoral distribution. However, it is often accompanied by more rapid clearance from the body and in several cases also by inherent destabilization and reduction of the binding affinity of the antibody. In this perspective, we discuss different cancer targeting approaches based on antibodies or their fragments. We carefully consider how their size and binding properties influence their intratumoral uptake and distribution, and how this may affect cancer imaging and therapy of solid tumors.

Modeling tumor cell adaptations to hypoxia in multicellular tumor spheroids

Under hypoxic conditions, tumor cells undergo a series of adaptations that promote evolution of a more aggressive tumor phenotype including the activation of DNA damage repair proteins, altered metabolism, and decreased proliferation. Together these changes mitigate the negative impact of oxygen deprivation and allow preservation of genomic integrity and proliferative capacity, thus contributing to tumor growth and metastasis. As a result the presence of a hypoxic microenvironment is considered a negative clinical feature of many solid tumors. Hypoxic niches in tumors also represent a therapeutically privileged environment in which chemo- and radiation therapy is less effective. Although the negative impact of tumor hypoxia has been well established, the precise effect of oxygen deprivation on tumor cell behavior, and the molecular signals that allow a tumor cell to survive in vivo are poorly understood. Multicellular tumor spheroids (MCTS) have been used as an in vitro model for the avascular tumor niche, capable of more accurately recreating tumor genomic profiles and predicting therapeutic response. However, relatively few studies have used MCTS to study the molecular mechanisms driving tumor cell adaptations within the hypoxic tumor environment. Here we will review what is known about cell proliferation, DNA damage repair, and metabolic pathways as modeled in MCTS in comparison to observations made in solid tumors. A more precise definition of the cell populations present within 3D tumor models in vitro could better inform our understanding of the heterogeneity within tumors as well as provide a more representative platform for the testing of therapeutic strategies.

The Role of Tumor Microenvironment in Chemoresistance: To Survive, Keep Your Enemies Closer

Chemoresistance is a leading cause of morbidity and mortality in cancer and it continues to be a challenge in cancer treatment. Chemoresistance is influenced by genetic and epigenetic alterations which affect drug uptake, metabolism and export of drugs at the cellular levels. While most research has focused on tumor cell autonomous mechanisms of chemoresistance, the tumor microenvironment has emerged as a key player in the development of chemoresistance and in malignant progression, thereby influencing the development of novel therapies in clinical oncology. It is not surprising that the study of the tumor microenvironment is now considered to be as important as the study of tumor cells. Recent advances in technological and analytical methods, especially ‘omics’ technologies, has made it possible to identify specific targets in tumor cells and within the tumor microenvironment to eradicate cancer. Tumors need constant support from previously ‘unsupportive’ microenvironments. Novel therapeutic strategies that inhibit such microenvironmental support to tumor cells would reduce chemoresistance and tumor relapse. Such strategies can target stromal cells, proteins released by stromal cells and non-cellular components such as the extracellular matrix (ECM) within the tumor microenvironment. Novel in vitro tumor biology models that recapitulate the in vivo tumor microenvironment such as multicellular tumor spheroids, biomimetic scaffolds and tumor organoids are being developed and are increasing our understanding of cancer cell-microenvironment interactions. This review offers an analysis of recent developments on the role of the tumor microenvironment in the development of chemoresistance and the strategies to overcome microenvironment-mediated chemoresistance. We propose a systematic analysis of the relationship between tumor cells and their respective tumor microenvironments and our data show that, to survive, cancer cells interact closely with tumor microenvironment components such as mesenchymal stem cells and the extracellular matrix.

Intein-mediated site-specific synthesis of tumor-targeting protein delivery system: Turning PEG dilemma into prodrug-like feature

Poor tumor-targeted and cytoplasmic delivery is a bottleneck for protein toxin-based cancer therapy. Ideally, a protein toxin drug should remain stealthy in circulation for prolonged half-life and reduced side toxicity, but turn activated at tumor. PEGylation is a solution to achieve the first goal, but creates a hurdle for the second because PEG rejects interaction between the drugs and tumor cells therein. Such PEG dilemma is an unsolved problem in protein delivery. Herein proposed is a concept of turning PEG dilemma into prodrug-like feature. A site-selectively PEGylated, gelatinase-triggered cell-penetrating trichosanthin protein delivery system is developed with three specific aims. The first is to develop an intein-based ligation method for achieving site-specific modification of protein toxins. The second is to develop a prodrug feature that renders protein toxins remaining stealthy in blood for reduced side toxicity and improved EPR effect. The third is to develop a gelatinase activatable cell-penetration strategy for enhanced tumor targeting and cytoplasmic delivery. Of note, site-specific modification is a big challenge in protein drug research, especially for such a complicated, multifunctional protein delivery system. We successfully develop a protocol for constructing a macromolecular prodrug system with intein-mediated ligation synthesis. With an on-column process of purification and intein-mediated cleavage, the site-specific PEGylation then can be readily achieved by conjugation with the activated C-terminus, thus constructing a PEG-capped, cell-penetrating trichosanthin system with a gelatinase-cleavable linker that enables tumor-specific activation of cytoplasmic delivery. It provides a promising method to address the PEG dilemma for enhanced protein drug delivery, and importantly, a facile protocol for site-specific modification of such a class of protein drugs for improving their druggability and industrial translation.

NANOMEDICINE: will it offer possibilities to overcome multiple drug resistance in cancer?

This review is written with the purpose to review the current nanomedicine literature and provide an outlook on the developments in utilizing nanoscale drug constructs in treatment of solid cancers as well as in the potential treatment of multi-drug resistant cancers. No specific design principles for this review have been utilized apart from our active choice to avoid results only based on in vitro studies. Few drugs based on nanotechnology have progressed to clinical trials, since most are based only on in vitro experiments which do not give the necessary data for the research to progress towards pre-clinical studies. The area of nanomedicine has indeed spark much attention and holds promise for improved future therapeutics in the treatment of solid cancers. However, despite much investment few targeted therapeutics have successfully progressed to early clinical trials, indicating yet again that the human body is complicated and that much more understanding of the fundamentals of receptor interactions, physics of nanomedical constructs and their circulation in the body is indeed needed. We believe that nanomedical therapeutics can allow for more efficient treatments of resistant cancers, and may well be a cornerstone for RNA based therapeutics in the future given their general need for shielding from the harsh environment in the blood stream.

TGF-β Negatively Regulates CXCL1 Chemokine Expression in Mammary Fibroblasts through Enhancement of Smad2/3 and Suppression of HGF/c-Met Signaling Mechanisms

Fibroblasts are major cellular components of the breast cancer stroma, and influence the growth, survival and invasion of epithelial cells. Compared to normal tissue fibroblasts, carcinoma associated fibroblasts (CAFs) show increased expression of numerous soluble factors including growth factors and cytokines. However, the mechanisms regulating expression of these factors remain poorly understood. Recent studies have shown that breast CAFs overexpress the chemokine CXCL1, a key regulator of tumor invasion and chemo-resistance. Increased expression of CXCL1 in CAFs correlated with poor patient prognosis, and was associated with decreased expression of TGF-β signaling components. The goal of these studies was to understand the role of TGF-β in regulating CXCL1 expression in CAFs, using cell culture and biochemical approaches. We found that TGF-β treatment decreased CXCL1 expression in CAFs, through Smad2/3 dependent mechanisms. Chromatin immunoprecipitation and site-directed mutagenesis assays revealed two new binding sites in the CXCL1 promoter important for Smad2/3 modulation of CXCL1 expression. Smad2/3 proteins also negatively regulated expression of Hepatocyte Growth Factor (HGF), which was found to positively regulate CXCL1 expression in CAFs through c-Met receptor dependent mechanisms. HGF/c-Met signaling in CAFs was required for activity of NF-κB, a transcriptional activator of CXCL1 expression. These studies indicate that TGF-β negatively regulates CXCL1 expression in CAFs through Smad2/3 binding to the promoter, and through suppression of HGF/c-Met autocrine signaling. These studies reveal novel insight into how TGF-β and HGF, key tumor promoting factors modulate CXCL1 chemokine expression in CAFs.

Overview of Methods for Overcoming Hindrance to Drug Delivery to Tumors, with Special Attention to Tumor Interstitial Fluid

Every drug used to treat cancer (chemotherapeutics, immunological, monoclonal antibodies, nanoparticles, radionuclides) must reach the targeted cells through the tumor environment at adequate concentrations, in order to exert their cell-killing effects. For any of these agents to reach the goal cells, they must overcome a number of impediments created by the tumor microenvironment (TME), beginning with tumor interstitial fluid pressure (TIFP), and a multifactorial increase in composition of the extracellular matrix (ECM). A primary modifier of TME is hypoxia, which increases the production of growth factors, such as vascular endothelial growth factor and platelet-derived growth factor. These growth factors released by both tumor cells and bone marrow recruited myeloid cells form abnormal vasculature characterized by vessels that are tortuous and more permeable. Increased leakiness combined with increased inflammatory byproducts accumulates fluid within the tumor mass (tumor interstitial fluid), ultimately creating an increased pressure (TIFP). Fibroblasts are also up-regulated by the TME, and deposit fibers that further augment the density of the ECM, thus, further worsening the TIFP. Increased TIFP with the ECM are the major obstacles to adequate drug delivery. By decreasing TIFP and ECM density, we can expect an associated rise in drug concentration within the tumor itself. In this overview, we will describe all the methods (drugs, nutraceuticals, and physical methods of treatment) able to lower TIFP and to modify ECM used for increasing drug concentration within the tumor tissue.

Enhancement of Intratumoral Chemotherapy with Cisplatin with or without Microwave Ablation and Lipiodol. Future Concept for Local Treatment in Lung Cancer

Novel therapies for lung cancer are being explored nowadays with local therapies being the tip of the arrow. Intratumoral chemotherapy administration and local microwave ablation have been investigated in several studies. It has been previously proposed that lipiodol has the ability to modify the microenvironment matrix. In our current study we investigated this theory in BALBC mice. In total 160 BALBC mice were divided in eight groups: a) control, b) cisplatin, c) microwave, d) microwave and lipiodol, e) cisplatin and lipiodol, f) microwave and cisplatin, g) lipiodol and h) lipiodol, cisplatin and microwave. Lewis lung carcinoma cell lines (10⁶) were injected into the right back leg of each mouse. After the 8th day, when the tumor volume was about 100mm³ the therapy application was initiated, once per week for four weeks. Magnetic resonance imaging was performed for each tumor when a mouse died or when sacrificed if they were still alive by the end of the experiment (8-Canal multifunctional spool; NORAS MRI products, Gmbh, Germany). Imaging and survival revealed efficient tumor apoptosis for the groups b,c,d,e and f. However; severe toxicity was observed in group h and no follow up was available for this group after the second week of therapy administration. Lipiodol in its current form does assist in a more efficient way the distribution of cisplatin, as the microwave apoptotic effect. Future modification of lipiodol might provide a more efficient method of therapy enhancement. Combination of drug and microwave ablation is possible and has an efficient apoptotic effect.

Three-dimensional in vitro co-culture model of breast tumor using magnetic levitation

In this study, we investigate a novel in vitro model to mimic heterogeneous breast tumors without the use of a scaffold while allowing for cell-cell and tumor-fibroblast interactions. Previous studies have shown that magnetic levitation system under conventional culturing conditions results in the formation of three-dimensional (3D) structures, closely resembling in vivo tissues (fat tissue, vasculature, etc.). Three-dimensional heterogeneous tumor models for breast cancer were designed to effectively model the influences of the tumor microenvironment on drug efficiency. Various breast cancer cells were co-cultured with fibroblasts and then magnetically levitated. Size and cell density of the resulting tumors were measured. The model was phenotypically compared to in vivo tumors and examined for the presence of ECM proteins. Lastly, the effects of tumor stroma in the 3D in vitro model on drug transport and efficiency were assessed. Our data suggest that the proposed 3D in vitro breast tumor is advantageous due to the ability to: (1) form large-sized (millimeter in diameter) breast tumor models within 24 h; (2) control tumor cell composition and density; (3) accurately mimic the in vivo tumor microenvironment; and (4) test drug efficiency in an in vitro model that is comparable to in vivo tumors.

Low-molecular-weight protamine-modified PLGA nanoparticles for overcoming drug-resistant breast cancer

Multidrug resistance (MDR) is a major challenge for cancer therapy. Herein, we report a simple yet effective system, cell-penetrating peptide (CPP)-assisted poly(lactic-co-glycolic acid nanoparticles (PLGA NPs), for improving doxorubicin (DOX) delivery and overcoming MDR cancer. We selected the naturally derived CPP low-molecular-weight protamine (LMWP) to modify PLGA NP for enhanced drug delivery. We demonstrated that multiple mechanisms ("synergistic multipronged delivery") were responsible for the anti-MDR effects of LMWP/PLGA NP. This delivery system could boost intracellular and intranuclear delivery, thereby circumventing drug efflux. Use of a P-glycoprotein inhibitor did not further increase the efficiency of intracellular delivery of LMWP/PLGA/DOX NP, suggesting that delivery of LMWP-based NP was not affected by transporter-mediated drug efflux. Importantly, enhanced uptake and penetration within the tumor was found in mice given LMWP-based NP. LMWP/PLGA NP effectively arrested tumor growth in mice harboring drug-resistant breast tumors, thereby improving treatment outcomes without detectable toxicities. These data suggest that our system could provide effective yet safe anti-MDR cancer therapy based on a synergistic, multipronged drug-delivery strategy.

Human mesenchymal stem cells promote cancer motility and cytokine secretion in vitro

Interactions of human mesenchymal stem cells (hMSC) with tumors are controversially discussed since there is evidence for both tumor progression as well as tumor inhibition by hMSC. The objective of the present study is to investigate whether hMSC support cell motility and cytokine secretion in a head and neck squamous cell carcinoma cell line (HLaC 78). A spheroid model was generated in which the ultrastructure of spheroids was analyzed using scanning electron microscopy (SEM). The migration capability was monitored in a monolayer as well as in a spheroid model. The variation in migration and secretion of interleukin (IL)-6, IL-8 and vascular endothelial growth factor (VEGF), as well as the expression of the multidrug resistance gene (MDR-1) was investigated. Finally, the alteration in the cell cycle was analyzed by flow cytometry. SEM showed a tight cell-cell contact with extensive secretion of extracellular matrix. The migration and invasion capability of HLaC 78 was enhanced by hMSC. Cancer cell motility was also increased by hMSC as well as secretion of the cytokines IL-6, IL-8 and VEGF. hMSC did not induce the expression of MDR-1 in HLaC 78, and there was no alteration in the cell cycle of HLaC 78 after cocultivation with hMSC. Our results confirm the important role of hMSC in cancer biology since both an enhancement of cell motility as well as cytokine secretion could be shown. However, based on these findings and those in the current literature, caution must be applied when using hMSC as a carrier for tumor therapy in cancer treatment.